Semiconductor Magazine

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Indice

FlexyLAB: un sistema flessibile per testare laffidabilit dei circuiti integratiM. Salvi, EuroInstruments p.3

Applicazione della visione artificiale nellindustria dei semiconduttoriG. Fazio, ST MICROELECTRONICS p.5

Analog Devices Reduces MEMS Test Costs with PXI and LabVIEWWoody Beckford, Analog Devices Inc. p.8

Adopting NI PXI for Semiconductor Validation to Achieve Performance

Improvements and Three-Times Cost Savings

Ray Morgan, ON Semiconductor p.10

ST-Ericsson Automates RFIC Validation Using NI LabVIEW and NI TestStandSylvain Bertrand, ST-Ericsson p.12

NI TestStand Provides the Framework to Texas Instruments $4 Billion DivisionMarvin Landrum, Texas Instruments, Inc. p.14

Credence Systems Uses NI Modular Instruments to Extend Semiconductor Test FlexibilityDavid Pinto, Credence Systems Corp. p.16

PXI-Based Automated Wafer Probe Tester

Andrew Kahn, G Systems, LP p.17

Automated Semiconductor Wafer Sorting Using NI LabVIEW with Synchronized Motion,

Vision, and DAQ

Jeff Long, Automation Works, Inc. p.18

PXI-Based Embedded System Controls Semiconductor Metrology Tool

Craig Moore, EUV Technology p.20

Using NI LabVIEW and PXI to Reduce Video DAC Testing Time by 97 Percent

Sam Yang, Sunplus Technology Co. p.22

Creating a High-Speed Control System to Test MEMS Microshutters Using NI LabVIEW FPGA

Eric Lyness, Mink Hollow Systems p.23


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Sub-surface defect detection in Si-wafer for semiconductor industries by a LabVIEW based

real time digital shearography

Ganesha Udupa, Nanyang Technological University, Singapore

BKA Ngoi, Nanyang Technological University, Singapore p.25

Research Group Creates Flexible, High-Speed, Mixed-Signal System for On-Wafer Function

and Performance Testing

Axel Nackaerts, Interuniversity Microelectronics Centre p.27

A Low-Cost, Expandable PXI-Based Solution for Mixed-Signal ASIC Test

M. Cem Karahan, Cal. Bay Systems, Inc. p.28

TriQuint Semiconductor Uses NI PXI and LabVIEW to Reduce Characterization Time

of RF Power Amplifiers

Gary Shipley - TriQuint Semiconductor p.30


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FlexyLAB: un sistema flessibile per testare laffidabilit dei circuiti

integrati

M. Salvi, EuroInstruments

LA SFIDA

Realizzare un sistema che renda agevole e flessibilelattivit di test e debug dei circuiti integrati,consentendo di condurre la maggior parte delle prove diaffidabilit previste sui semiconduttori tra cui OLT,HTRB oltre a prove di continuit elettrica delle schededi interfaccia su cui montato il circuito integrato.

Prodotti utilizzati

LabVIEW, DAQ, Modular Instruments, PXI

Breve Riassunto

I circuiti integrati, di seguito IC (Integrated Circuits), chetrovano impiego nelle pi svariate apparecchiature edapplicazioni elettroniche, prima dellimmissione sulmercato devono sostenere determinate prove diaffidabilit e robustezza stabilite dalla casa produttrice.A tale scopo, il mercato dei sistemi di test per

semiconduttori annovera diversi produttori di macchineper il debug e laffidabilit degli IC, ma tipicamente talisistemi sono specifici di una singola tipologia di prova,quindi poco flessibili e, laccesso alle risorse deldispositivo, per analizzarne il comportamento a prova incorso, non sempre agevole.

In questo ambito FlexyLAB rappresenta unideainnovativa che consente di sottoporre gli IC alle pi noteed utilizzate prove di affidabilit, tra cui OLT (OperatingLife Test) ed HTRB (High Temperature Reverse BIAS),mediante un semplice cambio dellinterfaccia HW.Grazie ad un SW applicativo user-friendly lutente ingrado di impostare i parametri di prova in modo rapidoed intuitivo, cos come di monitorare comodamente isegnali critici e loggare i risultati di test consultandolisuccessivamente in un comodo formato HTML.

La struttura del sistema permette allutente di avere unfacile accesso alle risorse dell IC e le dimensioni ridottelo rendono utilizzabile in qualsiasi ambiente lavorativo.

Articolo

Ai giorni nostri lelettronica trova spazio in molteplicisettori ed il ritmo di crescita delle prestazioni e della

complessit delle apparecchiature e delle applicazionirende necessario sviluppare ed immettere sul mercatonuovi IC, in tempi sempre pi stringenti, a patto per di

LA SOLUZIONE

Larchitettura del sistema FlexyLAB basata sullapiattaforma PXI di National Instruments con controllerintegrato ed include schede DAQ, digitali, industriali emultimetri. Lapplicazione stata sviluppata sfruttandola potenzialit e la modularit degli ambienti di sviluppoNI LabVIEW e NI LabWindows/CVI, garantendo unridotto time-to-market. Il sistema ha unelevataflessibilit, consente allutente di eseguire moltepliciprove di affidabilit connettendo lopportuna interfacciaHW che fa da ponte tra il sistema ed il dispositivo sotto

test ed pronto ad eventuali customizzazioni e/oevoluzioni richieste dal mercato dei semiconduttori.

garantirne un continuo e corretto funzionamento persvariati anni.

Le case produttrici di semiconduttori hanno via viadefinito alcune prove per la valutazione dellarobustezza ed affidabilit degli IC, che possono esseredi tipo elettrico, ambientale e meccanico, le quali

simulano lintero ciclo vita del dispositivo in variecondizioni e permettono in tal modo al costruttore digarantirne il corretto funzionamento in campoapplicativo.

A tale proposito oggi sul mercato si trovano aziendeproduttrici di sistemi di test per laffidabilit deisemiconduttori, ma tipicamente tali sistemi sonospecifici per una singola tipologia di test e pensati per laprova di un intero lotto di dispositivi.

In questo contesto Euro Instruments ha ideato erealizzato un sistema di test flessibile e compatto, che

consente di effettuare molteplici tipologie di prove diaffidabilit elettrica anche su singolo dispositivo, inmodo semplice ed intuitivo.

FlexyLAB un sistema sviluppato per rendere il debuged il test degli IC, per quel che concerne le prove diaffidabilit elettriche, il pi flessibile e user-friendlypossibile.

A tale scopo il SW applicativo stato sviluppato in NILabVIEW e NI LabWindows CVI, mentre lHW basatosu un rack PXI National Instruments che alloggiadiverse schede gestite da un controller integrato, sono

inoltre presenti degli alimentatori programmabilicomandati tramite seriale, un gruppo di continuit e leinterfacce che connesse al backplane permettono


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allutente di passare da una tipologia di test allaltra inmodo agevole.

Grazie allesperienza maturata nel campo dellamicroelettronica Euro Instruments ha provveduto allaprogettazione e realizzazione dellintera elettronica del

sistema, che comprende il backplane, le interfacce perle prove di OLT, HTRB, ed il test di continuit elettrica(Figura 1).

Il test di continuit si differenzia dagli altri e permette diverificare la continuit elettrica delladapter su cui tipicamente saldato o zoccolato il dispositivo da testare,prima e dopo lesecuzione di una prova OLT o HTRB,che in talune condizioni potrebbe avere portato allarottura dell IC.

In tal caso lutente mediante linterfacciadellapplicazione SW in grado di sviluppare il test di

continuit per un dato dispositivo impostando delleopportune soglie di tensione e corrente per ciascun pine successivamente richiamarlo in modo agevole. Primadellesecuzione di uneventuale test di affidabilit laprova di continuit dovrebbe dare esito positivo, mentrese effettuata a seguito di un OLT o HTRB, potrebberiportare dei fallimenti e lutente dovrebbe essere cos ingrado di individuare i pin affetti da rottura.

Per quanto riguarda le prove OLT ed HTRB lutente unavolta connessa linterfaccia opportuna, tramitelapplicazione SW dovr andare ad impostare diversiparametri, come il numero di dispositivi sotto

test,tensione e corrente massima delle alimentazioni, imonitoraggi dei segnali critici, gli stimoli digitali edanalogici precedentemente realizzati utilizzando i toolsNI Digital e Analog Waveform Editor.

Durante i test OLT e HTRB le schede PXI gestiscono laconfigurazione dei rel, la programmazione via serialedegli alimentatori, la generazione degli stimoli digitali adalta velocit e quella delle forme donda analogiche edinfine il monitoraggio dei segnali impostati dallu tente.

Per potere effettuare una qualsiasi prova necessarioche lutente abbia collegato linterfaccia corretta, inquanto il SW effettua un controllo della scheda prima diconsentire lesecuzione del test.

A prova in corso, lutente in grado d i verificare ilcorretto funzionamento del dispositivo mediante ladefinizione di opportuni monitoraggi SW il cuiandamento viene visualizzato in un tab dedicato equalora questi non dovessero bastare, visto che lastruttura del FlexyLAB permette di avere pieno accesso

a tutte le risorse del dispositivo sotto test, pu collegarsicon un oscilloscopio ai segnali di interesse edeffettuarne unanalisi pi accurata. Inoltre il sistema provvisto anche di strumentazione integrata, disponibileallutente per effettuare misure sulla board durante ildebug in qualunque fase della prova.

FlexyLAB rappresenta una soluzione flessibile,compatta ed economica nel campo delle prove diaffidabilit dei semiconduttori, e visto il know-how chevanta Euro Instruments nella progettazione erealizzazione di schede elettroniche e la flessibilit delsistema basato su un rack PXI a 18 posizioni, nulla

vieta in futuro di sviluppare applicazioni per prove diaffidabilit custom, da affiancare a quelle attualmenteimplementate.

Nella realizzazione del sistema lutilizzo di schede HighSpeed Digital I/O ha permesso di gestire in modoagevole molteplici segnali e di tipo differente, mentrelutilizzo di LabVIEW e LabWindows CVI in fase diimplementazione dellapplicazione ha ridottosignificativamente i tempi di sviluppo.

Figura 1.


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Applicazione della Visione Artificiale nellindustria dei Semiconduttori

G. Fazio, ST MICROELECTRONICS

LA SFIDA

I due problemi affrontati sono: controllo del caricamentodei wafers in una macchina di produzione e il controllodi processo di attacco retro wafers. Nel primo caso ilcaricamento dei wafers in posizione errate nellecassette provoca danni importanti. Nel secondo casoun processo errato intacca irrimediabilmente i lotti diproduzione. In tutte e due i casi, nella macchinaproduzione dinteresse non sono previsti controlliautomatici.

LA SOLUZIONE

I due problemi sono stati affrontati introducendo uncontrollo automatico utilizzanto la stessa tecnica: lavisione artificiale. La soluzione adottata prevedelinspezione dei wafers nelle cassette prima dellavviodel processo e blocco del caricamento in caso dianomali; e controllo del reatro wafer subito dopolattacco e blocco del processo in caso di anomalia.

Prodotti utilizzati

Vision

Breve riassunto

Recentemente abbiamo dovuto affrontare due problemidi controllo di processo: controllo del caricamento deiwafers in una macchina di produzione e il controllo diprocesso di attacco retro wafers. Nel primo caso ilcaricamento dei wafers in posizione errate nellecassette provoca danni importanti. Nel secondo casoun processo errato intacca irrimediabilmente i lotti diproduzione. In tutti e due i casi sulla macchina di

produzione dinteresse non sono previsti controlli. Daqui la necessita di introdurre un controllo automatico.I due problemi sono stati affrontati utilizzando la tecnicadella Visione Artificiale.Il nostro sistema e composto da Hardware(Videocamera e PC) e Software della NatiolalInstruments e sviluppato (algoritmi, illuminatori,assemblaggio etc.) da ImagingLab (IL).

Articolo

Introduzione

I processi per la lavorazione dei semiconduttori hannoun buon livello di automazione, ma per la complessita'dell'ambiente molti aspetti possono essereulteriormente migliorati.L'automazione della fabbrica decisa e progettata infase di avvio della fabbrica stessa. Alcuni controlli,pero', sono introdotti in seguito (quando la fabbrica e laproduzione sono avviati) a fronte di eventi che sonoevidenziati durante la produzione e non possono esserevalutati a priori.In genere, tali controlli sono ispezioni visive o procedureper gli operatori.

Chiaramente il passo successivo sarebbe quello dicercare di automatizzarli per ridurre gli errori umani edaumentare la produttivita', ma la cosa non sempre e'cosi' semplice.

In alcuni casi pur essendo fattibile non risultaconveniente, in altri la fattibilita' e' praticamenteimpossibile. In ogni caso, volta per volta il problema vavalutato attentamente cosi come la soluzione tecnica daadottare.

In questo lavoro saranno presentati due applicazioniche prevedono l'utilizzo della visione artificiale come

sistema di controllo automatico nellindustria deisemiconduttori.La visione artificiale ha enormi potenzialit che almomento non sono ancora del tutto sfruttate. In alcuniambienti industriali lapplicazione di queste tecniche eampiamente consolidata, ma in altri casi non ancoracos diffusa. Le ragioni potrebbero essere varie tra lequali i costi e la reale fattibilit.Prendiamo per esempio la produzione di partimeccaniche (viti, ingranaggi etc.).Questi sono pezzi con una certa forma, tolleranza dilavorazione e ben visibili rispetto allambientecircostante (il nastro trasportatore etc.). Prendendolimmagine di un pezzo meccanico lavorato, risultarelativamente semplice catturarla con una videocamera,fornire le regole di controllo (spessore, forma etc.) eapplicare cosi il controllo automatico sulla produzionestandard.Di esempi simili ce ne sono tanti altri: controllare uncolore particolare, la posizione di un foro etc..Nella nostra realt industriale le cose sono un po piucomplicate.Infatti, le lavorazioni (spessori deposti, parti rimosseetc.) effettuate sono nanometriche (non visibili a occhionudo) e sono eseguite su materiali che per loro natura

sono molto riflettenti (e difficile distinguerlidallambiente esterno).Questa situazione richiede una progettazione delsistema molto particolare.


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In questi ultimi anni i costi per lapplicazione di tecnicheVA sono notevolmente ridotti e nello stesso tempo latecnologia ha raggiunto dei livelli altissimi.Questi fatti ci hanno spinto a prendere inconsiderazione tale tecnologia per i due progetti di

seguito descritti.

Applicazione della VA

Un controllo automatico e' un sistema piu' o menocomplesso composto da un "sensore", un "elaboratore"e una "interfaccia".Il nostro sistema e composto da Hardware(Videocamera e PC) e Software della NatiolalInstruments e sviluppato (algoritmi, illuminatori,assemblaggio etc.) da ImagingLab (IL).

Abbiamo scelto questo tipo di HW e di SW per laflessibilita del sistema, ma da solo non e bastato: unruolo molto importante lo ha giocato la parte di sviluppo.Come gia detto limplementazione di tale tecnologianon e risultata cosi banale.Si e dovuta prestare, infatti, particolare attenzione agliilluminatori (con design dedicato), agli algoritmi (nonstandard) e anche allinterfacciamento con la macchina.Questultimo aspetto risulta fondamentale perimplementare il controllo in automatico e consiste nelsincronizzare lacquisizione dellimmagine al momentoopportuno e bloccare il processo in caso di problemi.La flessibilita dellHW e del SW sono risultati importantianche in fase di sviluppo: ci ha consentito di eseguire

delle prove preliminare e scremare molte situazioni nonvalide. Lalternativa sarebbe stata quella di scrivere ilsw e testarne lapplicazione. Questapproccio avrebbeportato via parecchio tempo.Inoltre, la flessibilita del sistema ci consentira in futurodi ampliare lutilizzo attuale. Potremo cioe introdurrecontrolli aggiuntivi.Abbiamo ritenuto, infine, importante sviluppare ilsistema appoggiandosi ad esperti, invece di affidarsi adun acquisto a catalogo, per le ragioni indicate inprecedenza: essendo le applicazioni particolari intermini di materiali, dimensioni e ambiente e risultatoimportante eseguire il fine tuning della misura(adattamento degli algoritmi) in fase sperimentale.

Controllo wafers su stazione di caricamento

Il problema e' legato alla presenza di wafers in crossslot o appaiati che sono caricati sulla macchina diproduzione. In questa macchina di produzione, lecassette contenente i wafers sono spostate su unpiano, un robot li solleva e sono bloccati su un altrorobot.A questo punto sono caricate altre 25 fette in mezzo aquelle esistenti e trasportate nei bagni di chimico.Se ci sono wafers storti questi entrano forzando nelle

guide del robot danneggiandole in quanto sono fatte dimateriale plastico morbido con conseguenti gravi danni:costo manutenzione, costo wafers e fermo macchina.

In questo caso si tratta di analizzare la posizioneassunta dal singolo wafer allinterno dei 25 slot del carrier in fase di merge di due lotti da 25 wafersciascuno.Lobiettivo del progetto e, quindi, lindividuazione della

posizione assunta dal singolo wafer al fine diindividuare le circostanze di pi wafer inseriti nellostesso slot (sia su un solo lato che su entrambi).

Il sistema stato realizzato basandosi su hardware(CVS1455) e librerie National Instruments per la partedi acquisizione. invece stato necessario sviluppare ad hoc lacomponentistica di illuminazione e otticadi ripresa.Il tipo di illuminazione utilizzata prevede limpiego diilluminatori lineari a LED.Si volutamente evitato luso di luce strutturata consorgente laser per evitare qualsiasi restrizione e lanecessit di certificazioni legate alla normativamacchine. stata utilizzata una camera con sensore CCD ad altarisoluzione (1392 x 1040) e ottica Schneider con focale4.8 mm.Leffettiva focale, il posizionamento della videocamera eil FOV (field of view) andranno rivisti in base ai criteri diintegrazione sullapparecchiatura presente inproduzione nelle due differenti posizioni di test.

Controllo di processo rimozione retro wafer

Il processo in questione prevede lattacco del retro delwafer.Tale processo serve per rimuovere gli strati indesideratiche creerebbero problemi alle operazioni successive(diffusione, litho, rtp)In questo caso il problema riscontrato e' quello relativoal sovrattacco del silicio che puo' portare problemi perle operazioni successive.Le possibili cause del soprattacco sono:- Strati inaspettati sul retro- Ricetta associata/selezionata in modo errato- Problemi hardware (leak valvola, temperatura errata,etc.).

Per tale verifica sulla macchina di produzione non eprevisto nessun controllo e di conseguenza il problemasi ripete per tutti i Wafers. Per cercare di sopperire aquesta mancanza e stato introdotto una proceduramanuale (controllo visivo) e si basa esclusivamente suun controllo a campione dopo il processo: il waferprocessato correttamente presenta uniformita inlucidita e colore; mentre se il wafer non e processatocorrettamente presenta delle striature radiali visibili.Inoltre, per altri processi (quelli in cui non si arriva alsilicio) il controllo retro non esiste in quanto l'operatore

non e' in gado di stabilire se il wafer e' stato processatoo no: se e alonato non e' corretto e se e uniform e e'ok.


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Si tratta, quindi, di analizzare il risultato di un attaccochimico sulla superficie posteriore di un wafer da 8:- Una superfice uniforme indica un attacco corretto;- Una striatura radiale indica invece una condizione difault.

Lobiettivo delprogetto e di introdurre lispezioneautomatica di ogni singolo wafer e leliminazionedellintervento / errore umano.La superfice del wafer ha richiesto qualcheaccorgimento per la ripresa di immagini uniformementeilluminate e prive di riflessi.Inoltre, il tipo di illuminazione (fluorescente ad altafrequenza o LED) e langolo di incidenza sono statiscelti con molta cura.E stata utilizzata una CCD ad alta risoluzione (1280 x960) e ottica con focale di 12 mm, ad una distanzavariabile tra 300 e 800 mm.Leffettiva focale, il posizionamento della videocamera eil FOV (field of view) andranno rivisti in base ai criteri diintegrazione sullapparecchiatura di etching presente inproduzione.Per lidentificazione delle striature, fermo restando ilrequisito di una illuminazione uniforme e priva di riflessi,abbiamo adottato la seguente soluzione:

Analisi morfologica delle striature con compensazioneautomatica delle variazioni del background. Lamorfologia delle striature permette una robustadiscriminazione mediante filtri morfologici.Lanalisi e stata applicata a una regione di interesse

(ROI) del wafer.

Conclusioni

In questo lavoro sono state descritte due applicazionidella Visione Artificiale (VA) nellindustria deisemiconduttori.Forse per alcuni ambienti industriali lapplicazione diqueste tecniche risulta abbastanza semplice, ma non ecosi nel nostro caso.Le due applicazioni sono stare realizzate utilizzandocomponenti della National Instruments e sono statesviluppate da ImagingLab e consistono nellintroduzionedi due controlli automatici: controllo posizione wafersnella cassetta di carico e controllo attacco retro wafers.In tutte e due le applicazioni si e dovuta prestare moltaattenzione allo sviluppo del sistema e la flessibi lita deicomponenti scelti ci ha permesso di raggiungere degliottimi risultati in tempi relativamente brevi.

Figura 1.


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Analog Devices Reduces MEMS Test Costs with PXI and LabVIEW

Woody Beckford, Analog Devices Inc.

THE CHALLENGE

Developing an efficient, cost-effective, and compactsystem for MEMS testing in characterization andproduction.

Products used

LabVIEW, PXI

About Analog Devices Inc.

Analog Devices Inc. (ADI) provides analog, mixed-signal, and digital signal processing (DSP) integratedcircuits (ICs) that convert, condition, or otherwiseprocess light, sound, temperature, motion, or pressureinto electrical signals for use in electronic equipment.Our ICs are found almost everywhere, includingautomobiles, cameras, televisions, cellular handsets,medical imaging devices, and industrial automationequipment.

Over the past two decades, our company has made a

significant investment in microelectromechanicalsystems (MEMS) inertial sensing technology. As aleading MEMS innovator and a pioneer inmicromachine technology, we produced the industrysfirst fully integrated iMEMS (integrated Micro ElectricalMechanical System) accelerometers and gyroscopes,helping electronic designers incorporate acceleration,tilt, shock, vibration, rotation, and multiple degrees-of-freedom (DoF) motion into their designs. We offer a fullrange of inertial sensing solutions, including our award-winning iMEMS accelerometers and gyroscopes,iSensor intelligent sensors, inertial measurement

units (IMUs), and iMEMS digital microphones.

Requirements for a New MEMS Test System

MEMS testing poses a number of challenges for theproduction test process. We needed an ATE systemthat met the demands of our product test plan with thelowest possible cost while ensuring product quality. Forour needs, our traditional big iron ATE solution was fartoo costly, too highly featured, and physically too largeto efficiently meet our requirements of a dedicatedMEMS tester. We needed an application-specific testsystem for our MEMS products with a subset of themeasurement capability of a big-iron ATE system.

THE SOLUTION

Using NI LabVIEW software with PXI modularinstrumentation to create a MEMS test system that canbe used in both characterization and production testingand delivers 11X reduction in capital equipment costs,15X reduction in footprint, 66X reduction in weight, and16X reduction in power consumption over the previousautomated test equipment (ATE) used in production.

NI PXI and LabVIEW Deliver a COTS Alternative

We began evaluating a number of options as analternative to our traditional production ATE platform.We wanted to leverage as much commercial off-the-shelf (COTS) technology as possible to reduce theoverhead required for a custom test solution. We alsoneeded a test platform that was flexible enough toaccommodate custom MEMS test requirements whilenot sacrificing instrumentation speed or performance.

The PXI platform from National Instruments offered thetest instrumentation capability we needed to meet ourchallenge. PXI is a widely adopted, open standard thathas existed for more than 10 years and beenimplemented across a variety of industries. PXI gives usa high level of flexibility and modularity to develop atargeted MEMS test system, which is reconfigurable forvarious test needs. For multisite testing, we canduplicate test resources by plugging in additionalmodules without changing any of our software, allowingus to scale our test equipment as needed based on ourthroughput demands.

We also needed our software environment to beinherently easy to use with the ability to create operator,program, and data interfaces to existing tools to easethe process of integrating a new ATE system into ourproduction floor. We chose LabVIEW software, whichwas already widely used in our characterization anddesign labs, to meet these challenges. We hadconsidered using ANSI C or C++ for our test software,but after performing a number of benchmarks withLabVIEW, we were impressed with its performance andability to take advantage of multicore technology.

We developed our new production test solution solely


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ni.com/solutions/i 10

with PXI and LabVIEW. We chose National Instrumentsas our ATE supplier for this project for their support,product offering, and global footprint. NI offered themajority of the test equipment we needed from a singlesource. National Instruments local field engineers andsystem engineering teams worldwide provided support

for our development teams throughout this project. Theflexibility of the PXI system combined with the ease ofuse of LabVIEW made it possible for our engineers toquickly design and prototype our solution. Test timeswere comparable or better with our new test systembased on PXI and LabVIEW versus our previousproduction ATE test system. We felt confident indeploying a PXI-based production test solution basedon NI technology for our MEMS devices.

Major Benefits of Using NI COTS Technology

Our new system offers a dramatic reduction in capitalequipment expenditures, footprint, weight, and power

requirements for MEMS production test using PXI andLabVIEW.

Cost Savings: Our previous ATE system cost more forits basic configuration than our new PXI systems totalall-inclusive cost. The PXI system also takes up verylittle space. In fact, our entire system is now physicallysmall enough to wheel around on a cart.

Reduced Footprint on Production Floor: Our newPXI-based ATE system truly offers a zero-footprinttester. The system is small enough that we canphysically move it around on a cart, saving valuablespace on our production floor.

Smaller, Easier-to-Use System: The weightcomparison between the two systems offers a majorreduction in shipping cost. Now, if any problems arise,we can simply switch out PXI instruments on-site usinglocal spares, or even ship the entire test system back toour development labs from the production line with verylittle overhead. The shipping container for the previousATE system alone would cost as much as our entirenew PXI test system.

Decreased Power Usage: We previously had to getour facilities department involved months in advance tomodify power grids and cooling systems toaccommodate additional testers. Now, our new PXIsystem is capable of running off of a standard powerplug with absolutely no modifications required.

Increased Test Quality: The new system improved theoverall quality of our testing. Because we designed thetester, we can ensure that every tester we ship to ourbranch facilities features the exact same hardware andruns the exact same programming and codesequences. Furthermore, with LabVIEW controlling the

system, our programmed test code is modular andreusable for future test programs or in our developmentlabs.

Same Test System for Characterization and

Production: The added flexibility and ease of use fortest development has led to our teams using the samesystem in other phases outside of production, includingdesign, characterization, and metrology. We now canuse the same ATE equipment in all environments

without incurring an impact on cost. This helps reduceour time to market and increase our product quality.

Using PXI and LabVIEW, we were able to develop anapplication-specific MEMS test platform that could scalefrom production to lab characterization, dramaticallyallowing us to reduce our total cost of MEMS testing.

Figure 1: Using LabVIEW with our PXI instrumentation, we

created a dual-site production test system to test two MEMS

devices in parallel in less time than on our previous ATE

system.


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Adopting NI PXI for Semiconductor Validation to Achieve Performance

Improvements and Three-Times Cost Savings

Ray Morgan, ON Semiconductor

THE CHALLENGE

Increasing validation throughput for new semiconductorproduct introductions as well as legacy products with alow-cost solution that is accurate, precise, and easilyupgradable with software and hardware.

THE SOLUTION

Replacing costly, standalone test equipment with amodular PXI-based platform that uses the latestprocessor technologies to achieve semiconductorvalidation at 10 times the speed and at a fraction of thespace and price.

Products used

LabVIEW, PXI

Updating Our Test System to Meet Business Needs

At ON Semiconductor, we needed a low-cost solution toincrease validation throughput for our new productintroductions. Along with the shortened evaluation cycletime and reduced cost, we wanted to develop anaccurate and precise system that was easilyupgradable with software and hardware for future use.The new system needed to handle the channel count ofour older high-speed and metal gate products as wellas our newer high-speed voltage-level translators.Advancements in semiconductor technology oftenresulted in costly standalone test equipment that quickly

became obsolete for the applications. Because ournext-generation test platform had to be flexible enoughto grow with our technological advancements, weneeded to achieve upgradeable performance that wecould easily integrate into the system with minimal costand apply to future applications.

A hidden cost with the previous platform was the timefor test because the measurement throughput was oftenhindered by standalone instruments with varyingprocessor speeds as well as complicated test set ups.Even though we used a common software platform toautomate the tests, the execution speed was limited by

the slowest standalone instrument in the system.In addition, instrumentation cost became an issuebecause reducing the cost of test scrutinized everycomponent of the test system. The investment instandalone instrumentation resulted in extra costs forredundant components that could be shared betweeninstruments such as the instrument chassis, processor,and power supply. After conducting some research, wediscovered that we would overpay by three to five timesfor standalone instruments versus comparableperformance in a modular instrument platform.

The New PXI Test System DesignOur test platform addresses both AC and DCparametric testing of semiconductor devices. In thepast, we performed AC parametric validation across16

channels using multiple standalone high-bandwidthoscilloscopes.By adopting the PXI platform, we were able to spend$20,000 USD for one NI PXI-5154 1 GHz digitizer, twoNI PXI-2547 8x1 multiplexers, and active probesinstead of invest more than $60,000 USD for four 1GHz oscilloscopes. We realized three times the costsavings while maintaining both measurementperformance and integrity. In addition to the costsavings, our new platform performs tests 10 timesfaster than previous tests.We also considered two main variables when using

standalone instruments in an automated test system:the varying processor speeds between the instrumentsin the test system and the speed of the bus used toconnect all the instruments. Many systems are basedon a GPIB interface, which is a common bus forcommunication. The modular approach, based on thePCI backplane, provides throughput increases for ourcurrent system and offers a method to achieve moreimprovements in the future by upgrading the PXIcontroller as new processors become available.

Meeting PXI Migration Challenges

Migrating to PXI presented many challenges including

connecting to the device under test. With fourstandalone oscilloscopes, we were able to connect toand terminate all of the channels on a device under testsimultaneously. A digitizer, like most standaloneoscilloscopes, offers both a 50 and a high-impedance(1 M) termination.The challenge with a two-channel digitizer was that onlytwo signals on the device under test are highimpedance or 50 ohm terminated at a time, leaving theother signals on the board un-terminated. The platformneeded a connectivity solution that would allow high-bandwidth measurements with low-capacitive loading

characteristics typically associated with active probes,which are commonly offered with standaloneoscilloscopes, but not readily available with digitizers.


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By integrating high-impedance active probes along withprobe power supplies into the system, we sampled andproperly terminated all channels on the device undertest without loading down the input or output. Mostsemiconductor products in the industry can be validatedusing this approach for AC timing characteristics. A

modularized, PXI-based approach allowed us to quicklyadapt the test platform to ever-changing measurementrequirements as the industry performance and speed ofsemiconductor devices continues to increase.

In addition, we had to create a software interface to theinstruments that is immediately familiar and usable byour test engineers and technicians. We met thischallenge by enlisting the services of SystemsIntegration Plus Inc. (SPI Inc.), a National InstrumentsAlliance Partner and Certified LabVIEW Developerbased in Scottsdale, Arizona. They branchedsubroutines, or LabVIEW VIs, into a friendly userinterface for testing.

Most test and product engineers expect to be able toturn knobs and press buttons on their oscilloscope. Thedifference with a digitizer in a virtual instrumentationplatform is that these knobs and buttons are nowaccessible with a single mouse click. Most PXIinstrument vendors offer soft front panels that attemptto reproduce the hardware front panel found onstandalone instruments. Instead, we used the LabVIEWVIs, which allowed us to customize the user interfaceand measurement routines to our application. With this

approach, our next-generation test platform eliminatedthe overhead, resulting in longer learning curves foundin the more complex user interfaces of traditionalstandalone instruments.

Setting the New Standard of Validation Test Design

The PXI platform set a new standard for semiconductordesign validation and broke many of the paradigms andconstraints of previous testingmethodologies. Withournew platform based on NI PXI technologies and theprocessing speed of a PC, we maintainedmeasurement and performance integrity while achievinga three times cost reduction and 10 times improvement

in semiconductor validation time. We also reduced thetest system footprint to just a fraction of the spaceconsumed by the former test solution. Becausemodular, PXI-based instruments now deliver higherperformance that is also available with standaloneinstruments, PXI offers high-precision, accurate

measurements for AC performance parameters that arecommonly tested in semiconductor validation labs.

Figure 1: Due to the modularity of PXI, we can quickly adapt to

changing measurement requirements as the performance and

speed of semiconductor devices continues to increase.


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ST-Ericsson Automates RFIC Validation Using NI LabVIEW and NI

TestStand

Sylvain Bertrand, ST-Ericsson

THE CHALLENGE

Automating the characterization of complex RFICs in aglobal design environment that consists of multipleteams with varying levels of test automation.

Products used

LabVIEW, NI TestStand

ST-Ericsson is one of the leading wireless IC providers.

Our complex IC designs require significant validationand characterization to guarantee quality. To increaseproductivity in our laboratories, we developed softwareautomation tools on RF test benches using softwarebased on the NI LabVIEW Test Executive and severalcustom tools to facilitate measurements. To improvecode reuse and reduce test development time, weneeded to implement a new standard test automationframework built on common software tools in theindustry. The new test automation platform built on NITestStand and LabVIEW helped us reduce the timenecessary to validate an RFIC from two months to threeweeks.

Innovative Development FrameworkWe sought the help of two Alliance Partners,MESULOG and SAPHIR, to implement our newdevelopment framework called the Robust and FastTesting Solution (RFTS). We chose NI TestStand,LabVIEW, and Mesulog TS+ characterization tools toimplement the solution because the industry has widelyadopted these tools and several groups within ourcompany are familiar with these products. Using thisnew standard platform, the test application andvalidation teams can now more easily meet therequirements of the design and engineering teams andtheir customers through increased code reuse.With the UNiversal Layer (UNL) developed usingLabVIEW, the RFTS framework provides different levelsof abstraction for instrument control development. Thislayer consists of the features necessary to controlinterfaces and instruments, an order interpreter to helptest engineers program measurement modules, and themanagement of the electrical configurations. Using theRFTS, we can easily share the development softwarefor various types of measurements and instrumentdriver libraries throughout projects and sites.

THE SOLUTION

Deploying an RFIC characterization software platformbased on NI LabVIEW, NI TestStand, and softwaredeveloped by National Instruments Alliance Partners.

Drawing the Boundary between NI TestStand and

LabVIEW

The overlapping features offered by LabVIEW and NITestStand led to a debate among project developmentteam members about how to use these tools together.With LabVIEW and NI TestStand, we could developsome functionality such as report generation,instrument device control, and loops on differentparameters. Our seven years of experience usingLabVIEW combined with the experience of the twoAlliance Partners made it possible to take advantage ofthese two software tools and develop an environmentfor validation and characterization that is flexible,reliable, and scalable.

In the RFTS, we chose to use LabVIEW for instrumentcontrol, specifically to communicate with devices usingNI-VISA and NI-DAQ driver software. We use NITestStand for sequencing the LabVIEW code,managing test parameters, reporting, and databaselogging. It would have added unnecessary projectdevelopment time and maintenance if we had tried todevelop the functionality provided by NI TestStandusing LabVIEW. We also used LabVIEW to write acustom operator interface for controlling the NITestStand system. With the RFTS platform, we reducedtest development time and facilitated code sharing

across groups. Instead of each group developing itsown instrument control and test management software,the RFTS provides a complete set of software tools forautomating tests.

Sharing and Deployment Are the Keys to a

Successful Solution

Because the use of this new software environment isnot mandatory in the company laboratories, the RFTSdevelopment team created an installation CD for thetools to facilitate its adoption. With the CD, the


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engineers can share the different components, such asinstrument drivers or sample projects provided by theRFTS platform. Moreover, we can use this installationCD to install deployment stations.

The RFTS offers additional benefits to our engineers

including a common set of tools that we can shareacross projects and groups. The code comes withexample projects as well as detailed documentation tohelp users get started quickly. Additionally, AlliancePartners maintain the RFTS, guaranteeing that issuesare resolved quickly and that help is available outsideour organization.

Figure 1: The NI TestStand Interface Operator.


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NI TestStand Provides the Framework to Texas Instruments

$4 Billion Division

Marvin Landrum, Texas Instruments, Inc

THE CHALLENGE

Characterizing Texas Instruments (TI) increasinglycomplex wireless and RF devices in a global designenvironment.

Products used

LabVIEW, NI TestStand

Eliminating the Design Bottleneck

TI has been producing a significant portion of theworlds semiconductor chips for more than 45 years.With close to $4 billion in revenue, TI is one of theleading wireless IC providers. However, as designgrowth increases linearly with new productintroductions, characterization of dozens of tests hasincreased exponentially, creating a design bottleneck.With the increasing demand fueling the design of morewireless ICs, our characterization groups have beenstruggling to keep up. Todays wireless designsencompass a greater number of complicatedcharacterization tests, and our process for handling theload became inadequate. These characterization testsrange from the highly integrated to system-level powermanagement, analog baseband, RF, and customsystem-on-a-chip tests as examples. The evolution ofour current device characterization began with highlymanual tests dependent on operator intervention andcontrol. This was the first step, however, of an eventualsemiautomated NI LabVIEW-based characterizationprocess.

Following this was the need to automate and sequenceindividual characterization tests, which we solved bydeveloping an in-house sequencer using LabVIEW.

However, with the growth in demand of these devicesand the fact that our RF and wireless IC design centersspanned four worldwide sites in three continents, theneed for a maintainable, modular, and reusable processwas needed.

We developed the fourth-generation characterizationprocess to handle just that. It now features NITestStand as the characterization test managementand automation framework with LabVIEW devicecharacterization modules and instrument libraries. By

THE SOLUTION

Streamlining TI characterization process with testdevelopment, management, and automation softwarepowered by National Instruments LabVIEW and NITestStand.

developing a common test management and

automation framework that is deployed worldwide, it notonly provides a common interface but sets the stageand provides a template for developing modular,reusable device tests that engineers can use at any siteworldwide. The benefits include completecharacterization automation, direct integration withenterprise-level database logging, and automatedreport generation and data mining using our customDATAMINER client.

NI TestStand Provides Backbone for ACE

We developed the software architecture that includesseveral systems. The overall architecture is called theautomated characterization environment (ACE), and,the team developed the main software component, asoftware framework for plug-in modules and tests, fromNI TestStand. NI TestStand is the backbone of thedevice characterization tests and the software platformthat our engineers reuse at all sites worldwide. Wecustomized the NI TestStand process model to includeintegration with its distributed change management(DCM) system and the local databases.

Figure 1: NI TestStand assits in design verification process of

TI semiconductor chips.


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The DCM system uses Perforce file management and isintegrated with our global sites. We globally manage allcharacterization tests and ACE libraries. The ACElibraries include an instrument library for access tomany of the common instruments of the ACE hardwareplatform, a measurement library for many of the

functions needed by each of the characterizationgroups, and an analysis library. ACE supports morethan 50 instruments and can be integrated into thehardware platform. Characterization groups use the NITestStand system and download the necessary librariesto develop the necessary characterization for newdevices. They create tests as needed, but much of thetest uses the architecture and the pre-existing ACElibraries.

ACE also includes a data miner, which is a configurableautomated report generation system that can create700-page reports in four clicks. It supports multiple

outputs --including text (ASCII), PDF, XML, andMicrosoft Word -- and can mine data locally or on thecentral server, which is accessible anywhere in theworld. There is an enormous amount of commonalitybetween the tests, and this reuse, with a maintainablesoftware platform, is helping our characterization tokeep up with our design.

Our device characterization stations are typically builtwith a high-end Dell desktop using a 3.0 GHz singleprocessor system with typically 2 GB of RAM. Theoperating system on most of these systems is WindowsXP Professional. We chose high-end desktops becauseof the nature of the tests. The PLL characterization test,

for example, could run for multiple days and capturemore than 100,000 data points to measure jitter. Forwireless and RF characterization, we typically use GPIBand benchtop instruments.

NI TestStand and LabVIEW Provide Efficient

Platform

By leveraging commercial off-the-shelf softwaretechnologies such as NI TestStand and LabVIEW, weachieved the level of commonality, maintainability, andreuse with our characterization platform to keep up withthe design of new components. Using virtualinstrumentation has helped us expand our $4 billion

wireless and RF business without sacrificing quality anddoubling the number of test engineers.


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Credence Systems Uses NI Modular Instruments to Extend

Semiconductor Test Flexibility

David Pinto, Credence Systems Corp.

THE CHALLENGE THE SOLUTION

Creating a test solution that performs specialized high-frequency measurements to meet diversesemiconductor application needs.

Products used

NI PCI-5122, NI SCOPE

Using NI modular instruments inside the Credence ASL1000 linear test platform to offer an integrated means ofincreasing flexibility.

The semiconductor industry has widely adopted theCredence ASL 1000 linear and mixed-signal IC testplatform to perform many traditional and complex tests;

however, an increasing number of users needspecialized measurement capabilities such as the abilityto perform high-frequency measurements.

Cost-Effective IC Test SystemThe popular ASL 1000 is a low-cost mixed-signal andanalog semiconductor test solution that supports up to21 instruments in a fully configured system. It has thesmallest footprint in its class, is air-cooled, and uses astandard 110 or 220 V outlet. With a small test headthat makes docking easy, the ASL 1000 is extremelyadaptable and easily shared between engineering labs where it is a cost-effective desktop test system andin full production multisite test environments where itproves its low total cost of ownership on a daily basis.The ASL 1000 is most commonly used to test powermanagement, analog, sensor, and discrete IC devices,which can often require specialized and diverse mixed-signal capabilities. To accommodate these diverseneeds, the ASL 1000 implements a modulararchitecture so users can integrate a variety ofspecialized measurement modules into the samesystem.

NI Digitizer Integration for High-Frequency

MeasurementsFor high-frequency measurement capability, the ASL1000 incorporates the NI PCI-5122 14-bit, 100MS/sdigitizer. This combination also provides users theability to acquire audio and video signals. For thesemeasurements, the PCI-5122 high-speed digitizer offers

two independent inputs, a large dynamic range, asoftware-selectable 50 or 1 M input, ranges from200 mVpp to 20 Vpp, and the ability to acquire more

than 1 million waveforms in onboard memory. Byintegrating the PCI-5122 digitizer into the ASL 1000platform, we were able to offer users the ability to makeworld-class, high-frequency measurements withoutneeding to communicate with external measurementdevices.To integrate this functionality, we chose theinternal PCI backplane of the ASL 1000, which controlsthe ASL instrumentation, to communicate with the NIPCI digitizer. For synchronization, we used an externalclock that was generated by internal ASL circuitry androuted that to a PFI line on the PCI-5122 digitizer. Thenwe routed the analog signals from the test head through

buffering circuitry before sending them to the inputs ofthe PCI-5122.For programming, users can access the NI-SCOPE CAPI, provided by National Instruments, from within theASLs visual ATE software environment. They candebug NI-SCOPE using Microsoft Visual Studio in thesame way they debug the code that controls other ASLinstruments. Using NI modular instruments hardware,we were able to provide our users with more high-performance measurement options and expand theflexibility of our platform. The combination of the ASL1000 and the NI PCI-5122 can cost-effectively test high-performance audio amplifiers and other analog devices

that would normally require a more-expensive ATEsystem.

two independent inputs, a large dynamic range, asoftware-selectable 50 or 1 M input, ranges from200 mVpp to 20 Vpp, and the ability to acquire more than1 million waveforms in onboard memory.

Figure 1: The ASL 1000 is a low-cost mixed-signal

and analog semiconductor test solution that supports

u to 21 instruments ina ull con i ured s stem.


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PXI-Based Automated Wafer Probe Tester

Andrew Kahn, G Systems, LP

THE CHALLENGE

Increasing wafer probe test throughput and improvingtester flexibility for use with various semiconductorsensors.

THE SOLUTION

Designing and building an automated production testsystem with high-speed switching that is configurablefor multiple specification limits using NI LabVIEWsoftware and NI Switch Executive.

Products used

LabVIEW,PXI

G Systems developed an automatic test system to testpressure transducers at the wafer level. The tester isfully expandable and features complete DC parametricanalysis including functional tests. The new system

replaces an expensive 20-year-old Teradyne tester andhas reduced test time by 50 percent.

The system tests voltage, current, resistance, andpressure for individual sensor die on a silicon substrate.There are currently five separate test points per sensor,and the tester is configured for up to 20 test points persensor. Currently, 15 parameters are being tested perdie.

Increasing production throughput is a commonchallenge for any wafer probe operation. Using old

equipment that is not readily expandable andconfigurable only complicates the problem. To expandprobe capacity and have a dynamic and configurabletest system, a silicon sensor manufacturer contracted GSystems to design an automated wafer probe testerthat increased test flexibility and reduced total test timeby more than 50 percent.

A System based on NI Hardware

The G Systems wafer probe tester uses NI hardware tointerface between a vintage Electroglas prober and fourhigh-speed, high-sensitivity source measure units(SMUs). The signals are routed through the high-

density NI PXI-2532 512-crosspoint matrix switchmodule configured in an 8 x 32 two-wire array. The NIPXI-4070 FlexDMM measures voltage and sensorleakage.

LabVIEW for Control and Operator Interface

LabVIEW controls the system, sequences parametrictests, and updates results in a database. Each sensortype has an executable test program and a uniqueconfiguration file. This software architecture made itsimple to modify test parameters and adjust test limitsmaking changes in the code. The test software and files

are downloaded on demand from a remote, secure fileserver. With NI Switch Executive, we could easily routeall signals between the SMUs and the wafer through theprober.

We developed the test software with an operating modefor production testing and an engineering mode. Inengineering mode, the software provides access toadditional controls and test data, and a technician canstep through the individual tests one at a time andpause on request.

A configurable, high-speed PXI-based automated waferprobe tester was developed, which reduced test time bymore than 50 percent. A LabVIEW software programprovided a simple, operator-friendly test solution that is

configurable for multiple test limits and multiple sensortypes. Overall, test times were reduced at significantcost savings.

Figure 1:The above images shows G Systems automated

wafer probe tester that was enhanced by NI LabVIEW.


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Automated Semiconductor Wafer Sorting Using NI LabVIEW with

Synchronized Motion, Vision, and DAQ

Jeff Long, Automation Works, Inc.

THE CHALLENGE

Sorting semiconductor wafers automatically intocategories based on physical and electricalcharacteristics such as thickness, bow, warp, totalthickness variation (TTV), and type (N-type or P-type) inaddition to matching the precision and repeatability ofindustry-standard equipment with greater throughput,flexibility, and user friendliness at much lower cost.

Products used

LabVIEW, DAQmx, PCIIn semiconductor manufacturing, the push for greaterefficiency and higher yield of silicon semiconductormaterial is never ending. As circuit features shrink insize and global price competition intensifies, waferprocesses push the physical and operational limits ofequipment manufacturers. One result is increasinglynarrow tolerances for incoming wafer physical andelectrical parameters in delicate process steps, such asmask and etch. To accommodate tight process steptolerances, wafers must be pre-sorted into narrowcategories based on electrical and mechanical

parametric values such as thickness, bow, warp, TTV,and type after semiconductor wafers are sawn from aningot and before processing. Gigamat Technologies,Inc., a Milpitas, CA, manufacturer of sorting, polishing,and edge grinding equipment undertook the task ofdeveloping the model 200TRT, a new generation ofautomated, high-accuracy, high-throughput, full-scanwafer sorting machines with the help of Jeff Long ofAutomationWorks, Inc.

System Requirements

Measuring the bow, warp, and TTV of a wafer requiresperforming a full dimensional measurement scan of thewafer top and bottom surfaces. This is not onlytechnically challenging, but represents a significantincrease in process time compared to simple, single-point measurements that were previously sufficient. Forthese measurements to be useful, they must matchindustry-standard benchtop instruments, which have theluxury of taking a great deal of time to ensuremeasurements are precise. Gigamats challenge was toautomatically sort wafers from cassettes using full-scanmeasurements at high throughput rates, with industry-standard accuracy and repeatability.

THE SOLUTION

Taking advantage of NI LabVIEW software, toolkits, andadvanced analysis capabilities with tightly synchronizedmotion, vision, and data acquisition hardware to createa PC-based system that sets a new standard forsemiconductor wafer sorting.

LabVIEW with Synchronized DAQ, Motion, and

Vision on a single PCLabVIEW running on a PC was the key to integrating allof the high-performance technologies required to makethis project a success. Combining the hardwaresynchronization of PCI boards controlling eight NImotion axes with two NI data acquisition boards andone vision board, the inherent multi-tasking and re-entrant execution capabilities and DAQmx task, timing,and triggering programming simplicity in LabVIEW gaveengineers an ideal platform to rapidly implement, test,and validate multiple iterations of process code. Themeasurement process is comprised of two steps, waferalignment and wafer measurement. Wafer alignmentidentifies the location and orientation of the waferrelative to a vacuum chuck on which it is held andrepositions the wafer exactly on the chuck center andwith its primary fiducial precisely oriented. The secondfunctional step in the measurement process is theperformance of the full wafer scan. This step involvesacquiring top and bottom distance measurements frommany points across the surface of the wafer andperforming analysis on them to derive results.

Wafer AlignmentWafer alignment is performed using three axes ofmotion and a linescan camera. A wafer is aligned byrotating it in the field of view of the camera. Bysynchronizing camera scans with chuck rotation, a 6Megapixel image of the wafer edge is composed in asingle revolution , which takes about one second.Because camera scans are synchronized with chuckposition, they are independent of chuck velocity andmay be acquired during chuck acceleration anddeceleration ramps to save time. The wafer center, flatand other features are identified from image data using


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LabVIEW vision, math, and advanced analysis tools.The wafer is then rotated and indexed in two shortmoves to bring it into perfect alignment for themeasurement station.

Wafer Measurement

A full measurement scan is performed by gripping awafer from beneath with a rotational chuck and spinningit between top and bottom probes which measure thedistance to the wafer surface with a resolution of


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PXI-Based Embedded System Controls Semiconductor Metrology Tool

Craig Moore, EUV Technology

THE CHALLENGE

Developing a networked embedded control andmeasurement system for a semiconductor metrologytool to measure extreme ultraviolet lithography (EUVL)mask blanks.

Products used

LabVIEW, PXI, DAQmx

The Latest in Semiconductor Manufacturing

TechnologyThe semiconductor manufacturing industry is activelyevaluating new technologies to further reduce chip size

and increase circuit density. Extreme ultraviolet (EUV)lithography is a new technology utilizing a shorterwavelength of light than traditional optical lithography toachieve the goal of smaller circuit traces. One criticalcomponent of the EUVL process is a mirror called amask blank, which is coated with a nonreflectiveimage (a mask) of the circuit to be projected andburned onto the chip. For the image to be projectedevenly, the mask blanks must have a uniform and highreflectivity of EUV light across their entire surface.Because high-energy EUV light does not travel throughair, this process must be performed, and any

measurements taken, inside a high-vacuum chamber.

A reflectometer measures the reflectivity, and, thus, thequality, of the blanks by reflecting monochromatic EUVlight off the blank and measuring the corresponding lossof intensity. The reflectometer varies the wavelength oflight, sweeps through an entire target spectrum, andproduces a reflectivity versus wavelength curve. EUVTechnology, a short-wavelength electromagneticradiation utilization and analysis instrumentationmanufacturer, asked James Kring, Inc. to partner indesigning an embedded control and measurementsystem for an EUV reflectometer metrology tool used

on a semiconductor factory floor. Touch-screen userinterfaces would enable common tasks such as editingand running measurement recipes, viewing results,monitoring status, and servicing.

The tool control system manages the roboticsresponsible for transferring the mask blank from astandard mechanical interface (SMIF) pod into a high-vacuum measurement chamber, and the environmentalcontrol system of pumps, valves, and pressure gaugesresponsible for maintaining the high-vacuumenvironment. The reflectometers measurement systemencompasses a laser, a laser-powered meter, EUVoptical sensors, and a custom four-axis servo motordriver system that generates and monochromates the

THE SOLUTION

Using NI LabVIEW Real-Time and PXI for embeddedhardware control and LabVIEW for Linux to host thenetworked operator and supervisory graphical userinterfaces on multiple touch-screen displays.

EUV light.

Responsible for maintaining the high-vacuum

environment.

The reflectometers measurement systemencompasses a laser, a laser-powered meter, EUVoptical sensors, and a custom four-axis servo motordriver system that generates and monochromates theEUV light. The hardware system consists ofapproximately 10 RS232 serial devices, 40 digital I/Olines, two analog input signals, and four servo motioncontrol axes.

Integrated PXI and LabVIEW Real-Time Provide a

Powerful and Cost-Effective Solution

We chose the PXI-8145 RT embedded controller as the

LabVIEW Real-Time control and measurementapplication execution target. It provided ampleprocessing capabilities and integrated easily with a widearray of plug-in PXI modules. We selected the PXI-6527digital I/O module for its isolated input/outputcapabilities and its ability to switch and monitor non-TTLlevel signals found inside the tool. We chose the PXI-8420 16-port asynchronous RS232 interface module forits LabVIEW Real-Time compatibility and ease ofprogramming via NI-VISA driver software.

Each measurement iteration required synchronizing theEUV light source generation with the corresponding

EUV detector measurement. With the PXI platformReal-Time System Integration (RTSI) bus, we tightlysynchronized the laser firing with the analog inputacquisition by sharing high-speed digital trigger signalsdirectly on the PXI backplane. We used the PXI-6070Emultifunction data acquisition module for itsaforementioned digital triggering capability, its ability toeasily meet the customers 1 MHz sampling raterequirement, and the ease of programming via NI-DAQmx driver software. We chose the PXI-7344 motioncontrol module to control the custom servo motordrivers which generated and monochromatted the EUVlight source. We took advantage of the PXI-7344 for itsability to embed custom motion control programs writtenusing NI FlexMotion VIs and run them directly on its


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own onboard processor. This feature was instrumentalin controlling the reflectometers reel-to-reel constant-tension tape drive, a critical component in the EUVsource-generation process.

LabVIEW Real-Time Shortens Development Time

with Remote Development and DebuggingTraditional embedded system development requiresmany tedious, manual steps. For example, afterdeveloping the source code, the user must be compile itand transfer it onto the embedded system. Then theuser must test and debug the application, oftenrequiring special debugger cables to be hooked upbetween the embedded system and the debugging PC.If software changes are required, the user must repeatthe process until achieving the desired result.However, with LabVIEW Real-Time targeting ourembedded PXI controller over the network, these stepswere completely transparent, dramatically reducing

testing and debugging time. We used LabVIEW forWindows to rapidly develop our control andmeasurement application, and we used the LabVIEWReal-Time Module to upload, execute, and debug ourapplication on the PXI-8145 controller real-timeoperating system.LabVIEW also provided a powerful suite of TCP/IP VIsfor developing the communications portion of thisdistributed control and measurement system. Theembedded PXI application managed low-level hardwareand measurement control, while the LabVIEW for Linuxapplications running on the touch-screen terminals

performed high-level operator control and measurementanalysis. We customized existing NI TCP/IPclient/server software to develop a truly distributedsystem with three networked subsystems messagingcontrol, status, and response data via Ethernet.

Cost-Effective Solution Affords Increase in

Productivity

James Kring, Inc., and EUV Technology produced anaffordable system in less time by using PXI andLabVIEW Real-Time. We realized a significant increasein software productivity by utilizing the advanced

embedded system debugging tools of LabVIEW Real-Time and the ready-to-use data acquisition, motion,networking, and analysis VIs that ship with theLabVIEW development environment. Using the PXIhardware platform meant we could focus on customerperformance requirements and simply choose the

appropriate plug-in modules to get the job done. Shouldthe system evolve, we can easily add hardware andenhance the software using the flexible and scalablePXI and LabVIEW Real-Time platforms.

Figure 1: Extreme Ultraviolet Reflectometer

System Layout.


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Using NI LabVIEW and PXI to Reduce Video DAC Testing Time by 97

Percent

Sam Yang, Sunplus Technology Co.

THE CHALLENGE

Developing a system to quickly and efficiently validatevideo digital-to-analog converters (DAC).

Products used

LabVIEW, PXI

Previously, validation testing for a video DAC took morethan 10 working days. This inefficient hardware testmodel took too much time, and it was difficult for the

engineer to quickly identify problems on the electriccircuit, and in the time-constrained semiconductorindustry, this became a serious problem. To helpresolve this issue, we used the LabVIEW graphicaldevelopment environment with a combination of digitalmultimeters, digital I/O devices, and switches to rapidlyextract data and reduce test time by 97 percent. Byswitching the testing approach, we also reduced errorscaused by the manual configuration of plugs, whichfurther improves testing efficiency.

The Introduction of Software-Defined Hardware

The objectives of this project included:

- Developing an automated testing system for videoDAC systems used in digital electronic householdappliances- Improving the performance of product testing- Reducing the frequency of repetitive humanmanipulation by implementing a standardizedautomated platform- The entire testing infrastructure was separated intohardware and software elements.

Developing a High-Speed Hardware Architecture

We achieved a significant reduction of test time by

replacing the original test environment with NI PXIhardware. In the past, due to the speed limitation ofGPIB and digital multimeters it took one second to finishtesting voltage. To finish testing an entire channel, ittook about 10.5 hrs. With its exceptional efficiency, theNI PXI-4071 digital multimeter reduces the test time ofper step voltage to 33 ms. Thus, it now takes less than20 minutes to finish testing the entire item, resulting intremendous time savings.Using the NI PXI-4110 power supply to replace thetraditional power supply provides a stable source ofvoltage for the DAC that can be controlled and

minimizes the testing space.

THE SOLUTION

Using the NI LabVIEW development environment andPXI hardware to create a test platform that reduces testtime by 97 percent.

Due to the testing requirements, each channel can beswitched to two different load resistances for differentcurrent value modes: full current (37.5 ) and 1/4

current (150 ). Previously, we had to switch theelectronic current by manually soldering the resistor.For example, to test a chip with four channels we had tochange four resistances in one electric current. It wastime consuming, and it increased the risk of the padfalling off the printed circuit board.

Building an Intuitive Front Panel Using LabVIEW

We used LabVIEW graphical programming software asthe development environment to construct an intuitivefront panel interface. The front panel displays the real-time testing status and each block functions accordingto the following:

- Initial DAC voltage and the reference voltage value toshow the level being measured- Real-time voltage measure taken by the NI PXI-4071multimeter- X-Y plots to show the voltage change per digital code- Ability to automatically change the test mode to showthe current pin configuration status of the NI PXI-6542high-speed digital I/O device- Manual configuration block testing- Choice of the files directory and format (.txt or .xml)- Single status measurements with real-time reporting.

We developed the new testing platform successfullyusing NI PXI modules to reduce the testing time from4,756 s to 138 s. In the competitive electronic industry,time is of the essence and it is imperative to minimizethe time frame from R&D to mass production.Therefore, the testing time is heavily weighted in thesuccess of the whole process. The highly efficientautomated testing platform generated from thecombination of National Instruments software andhardware has greatly reduced the testing time. Ourdepartment is now able to produce the most accuratetesting numbers within the shortest possible timeframe.


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Creating a High-Speed Control System to Test MEMS Microshutters

Using NI LabVIEW FPGA

Eric Lyness, Mink Hollow Systems

THE CHALLENGE

Synchronizing the motion of a magnet moving morethan 1 m/s with the opening and closing of tens ofthousands of hair-sized microelectromechanical system(MEMS) microshutters.

Products usedLabVIEW, PXI

The James Webb Space Telescope (JWST) is the next

big telescope at NASA. More ambitious than itspredecessor, the Hubble Space Telescope, NASA willplace the JWST at a stable Lagrange pointapproximately 1 million miles from the earth. Thistelescope is the next stepping stone towardunderstanding the universe and studying the Big Bangtheory at NASA. The near infrared spectrometer(NIRSpec), developed by the European Space Agency(ESA) with major NASA contributions, is the primaryinstrument on the telescope. It observes thousands ofdistant galaxies to probe the epoch of initial galaxyformations in the universe. To measure numerous faintobjects, the instrument must simultaneously observe alarge number of objects in previously unknownpositions.To observe objects at these positions, NASA developedthe microshutter array, a 171 by 365 matrix of 100 by200 m shutters that can open under random accesscontrol. Four microshutter arrays in a 2 by 2 matrixcreate a programmable transmission mask of about250,000 shutters so that the NIRSpec cansimultaneously target more than 100 faint objects,proportionally improving the efficiency of this majorscientific facility. This system is essential to thedevelopment of the microshutter array, and it will be

critical for the arrays flight qualification in this majorinternational mission.

What is a Microshutter?

A microshutter is a 100 by 200 m rectangular door thatopens and closes to block light or let it pass through.The shutters pivot on a silicon nitride flexure, actuatemagnetically with the help of magnetic coating, andlatch electrostatically through electrical connections.When we began working on this project, manufacturingshutter arrays was a new and complex process thatwas still under development. NASA manufactures theshutters in arrays with 365 columns and 171 rows for a

total of more than 62,000 shutters per array.

THE SOLUTION

Using the NI LabVIEW FPGA Module and the NI PXI-7813R reconfigurable I/O module to precisely anddeterministically pinpoint the position of the magnet andthe proper outputs to control the MEMS microshutters inperfect synchronization.

When we began working on this project, manufacturing

shutter arrays was a new and complex process thatwas still under development. NASA manufactures theshutters in arrays with 365 columns and 171 rows for atotal of more than 62,000 shutters per array. Wemounted the shutters on a substrate and wired thearray in a grid so that we can assert its rows andcolumns to address each shutter. To open a shutter, wepassed a magnet across the front of the array whileapplying high voltage to the row and column of eachshutter. The magnetic field opened the shutter, and thestatic charge at the intersection of the row and columnheld it open. We fabricated each shutter array to testsome aspect of the overall design. Tests in this facilityinform the further definition of the fabrication process.Using the NI PCI-7344 four-axis stepper motorcontrollers and the NI MID-7604 power motor drivers,we developed the software that controls the vacuumchamber, shutter control instrumentation, cameras, andother apparatuses to evaluate array performance.Testing with this system revealed that uncontrolledshutter release limits shutter performance. In thisuncontrolled approach, one closed a shutter by turningoff the power to the row and column of the shutter.With each approach, the shutter impacts its light bafflein a way that significantly limits its lifetime. The

development team decided that we should release theshutters in synchronization with a passing magnet sothat the magnetic field cushions the impact as theshutter closes. A test chamber completed in 2005includes this new synchronized latching-and-releasecapability.

Microshutter Control System

The microshutters must function reliably for up to100,000 cycles on different shutter designs. Instead oftesting for years, the new test chamber must cycle theshutters rapidly. The motor rotates at up to 240 rpm;thus, the sled, connected to the motor with off-center

cables, crosses back and forth in front of the shutter


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array four times per second. The control system needsto latch or release each of the 365 columns of theshutter array exactly as the magnet passes. To get anidea of the precision and speed required, imagine thateach column of the shutter array is a slat 1 in. wide in apicket fence that is 30 ft long. The magnet would be like

a jet plane moving past it at more than 700 mph andonly 3 ft away.To control the shutters, we have tocommunicate with the control electronics and customhigh-voltage shift registers. The new system also needsto rapidly communicate and provide utilities to test andverify many operations of the 584 chips. The systemmust meet all of these control requirements and be fail-safe. The tests run for days at a time, opening andclosing all 62,000 shutters 240 times per minute. If thesystem loses synchronization, the loss can damage theshutters in just a few minutes. In order to meet theserequirements, we had to either design and manufacturea custom chip or use the LabVIEW FPGA Module. Weselected a PXI chassis and controller containing a PXI-7813R reconfigurable I/O module and used theLabVIEW FPGA Module to perform shutter control.

The Control Design

The entire system contains a host computer thatcontrols the test chamber, a field-programmable gatearray (FPGA) host program that runs on the PXIcontroller, and FPGA software that runs on the PXI-7813R. With the FPGA host interface, engineers cancalibrate the system and perform manual controlfunctions, create and download bitmaps to write to the

arrays, and run self-test diagnostics on the otherfunctions of the 584 chips.The FPGA software reads the position of the magnetfrom a quadrature encoder or an absolute encoder. Weplaced the encoder-decoding algorithm in a single-cycleloop running at 40 MHz to ensure it does not miss anysteps. After some filtering to remove jitter, we placedthe position value in a first-in-first-out memory buffer(FIFO). Another loop on the FPGA reads the FIFO anddetermines what to do with the shutters based on thecurrent location of the magnet. This state machinecommunicates with the 584 chips using the protocol toturn the appropriate rows and columns on or off.

If the FIFO overflows, the state machine controlling theshutters is not going fast enough. The softwareindicates a synchronization error to the host computer

so the system can shut down. This algorithm works verywell and has become the foundation for controlexperimentation on the shutter arrays. As engineersdevelop new ideas to improve shutter operation, we caneasily add or change algorithms in the state machineblock.

The LabVIEW FPGA Module and PXI-7813R saved ushundreds of man-hours and thousands of dollars overdeveloping a custom chip. In addition to saving costs,the control algorithm is also inexpensively modified toimprove testing, explore shutter issues, and further thedevelopment of the NASA microshutter arrays.

Figure 1: Fully Functional, 1/6th Scale Model of the JWST

Mirror in an Optics Test Bed.


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Sub-surface defect detection in Si-wafer for semiconductor industries

by a LabVIEW based real time digital shearography

Ganesha Udupa, Nanyang Technological University, Singapore

BKA Ngoi, Nanyang Technological University, Singapore

THE CHALLENGE

The sub-surface defects in Si-wafer, which cannot bedetected before the wafer reclamation process or waferfabrication process caused high wafer rejection rate atthe end of the finishing stage of the processes. There isno instrument currently available to inspect the wafersat sub-surface level before waferfabrication/reclamation processes.

Products usedLabVIEW, PCI, Vision

AbstractSilicon wafers are widely used in semiconductor andmicroelectronics industries. The current practice insemiconductor industry is to inspect the wafers for anysurface defects only at the end of final polishing stage.At this stage, the sub-surface defects are visible (asthey have been exposed by polishing) as minute spotsforming spiral rings or swirl. The present work relatesto subsurface defects inspection system forsemiconductor industries and particularly to aninspection system for a defect such as swirl defects andgroup of particles in an unpolished silicon wafer beforethe wafer reclamation and/or the wafer fabricationprocess by digital shearography technique.

IntroductionDefects in silicon wafers have been of great scientificand technological interest since before the earliest daysof the silicon transistor. It has been reported thatmillions of dollars were lost each year owing to thefailure of detecting these defects in silicon wafers priorto the wafer fabrication/reclamation processes.

Recently much attention has been focused on crystaloriginated pits (COPs) on the polished surface of thewafer. The Semiconductor Industry Associations (SIA)International Technology Roadmap for Semiconductors/1/ identifies the inspection and characterization ofdefects and particles on wafers to be a potentiallyshow-stopping barrier to device miniaturization. Withthe need to detect smaller defects, the costs ofinspecting wafers are skyrocketing. In order for newadvances to be implemented in productionenvironments, improvements in sensitivity must beachieved. In order to increase the yield in themanufacturing process, the defects are to be detected

THE SOLUTION

The subsurface defects are detected and evaluated bythermally stressing the silicon wafer while looking fordefect induced anomalies in a fringe pattern, generatedby the interference of two speckle patterns in the CCDcamera and digital image processing. The technique isbased on Laser digital Shearography.

at the early stage of the process as well as to controlthe defects during the production process. The KLAsTencor instrument, a commercial wafer defectinspection system currently available to surface inspectthe defects at the end of the manufacturing process insemiconductor industries. Unfortunately there is noinstrument available to detect the subsurface defects inthe wafer before polishing. As a result sub-surfacedefects comprise 65% of all the reasons for yield loss/2/. Optical Interferometric techniques have been knownfor non-destructive testing (NDT) of objects /3/. Thetechnique is called speckle shearing interferometry,also known as Shearography applied here for the firsttime to detect sub-surface defects in semiconductorwafer /4/. Figure 1 shows the flowchart for in-linemetrology of subsurface defect detection proposed tobenefit the semiconductor wafermanufacturing/reclamation industries.

Principles of Digital ShearographyDigital shearography is an optical interferometric

technique that measures surface strain concentrationscaused by surface and subsurface flaws or defects dueto some sort of load, usually either thermal, vacuum orvibration excitation. In Shearography one object pointsplits into two in the image plane by a shearing device,thus two laterally sheared images are observed usingCCD camera. The two laterally sheared imagesinterfere with each other producing a randominterference pattern commonly known as a specklepattern. The pattern is random, and depends on thecharacteristics of the surface of the object. When theobject is deformed, by temperature, pressure, or other

means, the random interference pattern will change. Acomparison of the random speckle patterns for the


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deformed and undeformed states, and their respectivefringe patterns, gives information about the structuralintegrity of the object. A flaw or defect in the objectusually induces a strain concentration, which istranslated into an anomaly in the fringe pattern. Themethod is called shearography because one image of

the object is laterally displaced, or sheared, relative tothe other image. Digital speckle shearing interferometryor digital shearography uses a CCD camera andcomputer image processing to produce the fringeanomaly patterns indicative of the defects in objects.

Wafer Defect Detection SystemThe major parts are the illumination source,shearographic head and the image acquisition. Thesource of light is a 35-mW He-Ne laser at a wavelengthof 632.8nm. The shearographic head consists of a CCDcamera and the shearing element. The shearingelement is an interferometer in Michelson arrangement.

A beam splitter and two adjustable mirrors (M3 and M4)followed by a zoom lens, which image the wafer ontothe CCD camera. The direction and amount of shearare altered by tilting the mirror M4 through the requiredangle. A macro video zoom lens (18-108 mm, F/2.5)having the working distance variable between amaximum of infinity (without close up lens) and aminimum of 140 mm (with close up lens) is fixed to theCCD camera. The zoom lens can be manually adjustedfor focus and aperture control. With the workingdistance of about 600 mm, the zoom lens and thecamera was capable of recording a field of view that

ranged from 198 264 mm at the low magnification to33 44 mm at the high magnification. To view 200-mmdiameter wafer, the camerato-object distance wasabout 600 mm. The camera is connected to thePentium 4 computer for image acquisition and analysis.The LabVIEW Express 7 software along with imageprocessing card IMAQ PCI-1409 is installed in aPentium 4 computer and a programme is written toperform the real time subtraction.

Results and DiscussionExperiments were conducted using an IR lamp as achoice for thermal stressing method. However, the

other thermal sources such as Halogen etc can also beused. An infrared lamp is placed at the center of thewafer mount. The results are obtained in real time asshown in Fig. 3 and it shows subsurface defects in theform of anomaly in the fringe pattern. The software iswritten using LabVIEW Express 7, either to save thefringe patterns directly into the hard disc at each 100ms duration or an operator can click on the save buttonto capture the desired pattern for future analysis. Theprogram subtracts the successive frame from the initial(reference) frame and display on the monitor in realtime which can be saved as a file in a suitable format.

The pattern may vary depending on the distribution ofCOPs inside the wafer. Even though the stressing isnot steady state, the real time shearography helps inobserving transient thermal deformation, revealinginternal defects in the form of anomaly in the fringepattern. The swirl defects or voids inside the Si-wafer

may consists of little air trappings. The heat will causethe trapped air to expand or the defect to deform itsshape. This defect deformation reflects on the surfaceof the wafer producing strain anomaly on the surfaceand hence the defects are detected. The defects orflaws are normally manifest in the fringe pattern asfringe anomalies such as bulls eye, butterflies, fringediscontinuities, abrupt curvature or curling changes orsudden fringe density changes.

Fringe anomalies can generally be seen between 30 Cand 60 C after which speckles decorrelate resulting indegradation of fringe quality. The experiments arecontinued with the other wafers of the batch to sortgood and defective wafers. Figure 4 shows the fringepattern of one of the good wafer which clearly showsuniform and smooth fringe distribution without anyfringe anomaly in it. The fringes represent thederivatives of deformation due to loading. The resultsare repetitive, and it shows that the technique iscapable of differentiating the good wafers fromdefective wafers before the wafer reclamation orfabrication processes. Experiments were alsoconducted with vacuum stressing method, but failed toregister any underlying defects in the wafer.. This

shows that the thermal stressing method is a suitabletechnique to detect defects in Si-wafer.

ConclusionA wafer defect detection system for detectingsubsurface defects in an unpolished silicon wafer hasbeen investigated based on real time digitalshearography for in-line inspection of wafer insemiconductor industries. In the present work, swirldefects (cluster defects) and group of particles can bedetected qualitatively in real time by whole fieldmeasurement of the wafer surface in few seconds usingpowerful LabVIEW Express 7 software. The method ofstressing the wafer is investigated and the thermalmethod is the best choice compared to the vacuumstressing method. The Fringe anoma

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