1 Risk analysis for improving production ramp-up Bassetto 1, Mili 1, Siadat 2, Tollenaere 1 2 1.

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Risk analysis for improving production ramp-up

Bassetto1, Mili1, Siadat2, Tollenaere1

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Outline

Industrial context and question

Enterprise risk audit – practices analyses

Proposition & on going subject

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Industrial context of this research

• In semiconductor industry: ‘FE techno’– One new product generation: a technology– 2 years of development (Engineering)– 30 Development engineers– 1 techno 1B€– Commercial windows : From 2 to 5 years

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technological context

• From 120nm To 32nm techno Master 1,2nm +/- Å, Metrology tools @ 0,1 Å!

• Billion of times / wafer & 2.103 to 4.103 w/w

1,2nm +/- Å >1E10 times

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Number > 107/chip

Number > 103C/Wafer

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Industrial context

• Over 400 Process Operations

• Around 2 months to 1 full wafer

• 1 Fab Over than 40K Control Charts

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Industrial context

[Benfer, 96]I

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Semiconductor industries

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industrialization

Production size

Launch, 1 year

Maturation 1 year

Production, 2 years

Stop, 3 years

Time

YieldProduction volume max

100 %

Stakes

Launch Maturation Production Transfert and stop

Production life cycle in Semiconductor industries

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Learning Curves – eg on quality

• Several scenarios for quality managment:WIP

NC

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WIP

NC

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WIP

NC

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WIP

NC

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Case 1Case 2

Case 3 Case 4

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Research quest:

How being systematically in the case 3 or better ?

Before the ramp-up, risks are potentials (being known or not). During it, they become real events and reduce performance.

How prevent and mitigating them in a reliable manner?

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Outline




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Enterprise Description

• A best in class manufacture– ISO/TS – ISO 14001– Non conformity Mgt, Customer Claims,

Preventative & Predictive maintenance, Powerfull Process control, effective FMEA, Functional & Used Electronic Documentation, a cuting edge R&D…

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Risk management status

• Risk management methods & tools are not connected

FAB IN PROCESS

Reading sens

Non conformities

Scrap

Customer reclaim

Process Ctrl Issue

Maintenance Issue

Change

8DRisk analysis

FMEAQuality

analysis

New Technology Introduction

Eg Analysis

FMEAActions & Controls

Quality analysisActions & Controls

Eg AnalysisActions & Controls

Risk Analysis Actions &Controls

8D Actions & Controls

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• What happened when IS are not connected…

Eg. 2

Risk analysis

8D

Non conformities

Scrap

Customer reclaim

Process Ctrl Issue

Change

Quality analysis




FAB IN PROCESS

Reading sens

Maintenance Issue

FMEA


Eg Analysis



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• Experts are thinking that

Extract from the Preliminary analysis of a tool

1 occurrence MAX each an !

The lack of links between risk management processes (1/2)

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• Facts Underline an other reality for the « Wafer aligner » element

3 occurrences over 13 weeks 12 per year: If FMEA have been updated RPN ranking

grow up from 10 to 25

‘OCC’ will pass from 2 to 5

The lack of links between risk management processes (2/2)

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• Risk management not uniform

FAB IN PROCESS

Reading sens

Non conformities

Scrap

Customer reclaim

Process Ctrl Issue

Maintenance Issue

Change

8DRisk analysis

FMEAQuality

analysis


Eg Analysis






W

L

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S

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S Action plan coherency ?

Risked zone of the process ?

Coherency on ctrls ?

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Outline




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• Risk management not uniform

FAB IN PROCESS

Reading sens

Non conformities

Scrap

Customer reclaim

Process Ctrl Issue

Maintenance Issue

Change

8DRisk analysis

FMEAQuality analysis


Eg Analysis






Action plan & Controls

Risk Analysis

FAB IN PROCESS

Reading sens

Non conformities

Scrap

Customer reclaim

Process Ctrl Issue

Maintenance Issue

Change

8DRisk analysis

FMEA

Quality analysis

New Technology Introduction Eng Analysis






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Risk management proposition

• Need of information update => info reliability

UpdateFAB IN PROCESS

FAB EVENTS : * Non conformities* Customr claims* Process ctrl issue* Maintenance issue* Change…

Risk analysis

Action plan

Control Plan

Risk documents

-FMEA-update

Applies on

control

Information on risks

Reading sens

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• Toward a more « rational » organization15000 Risks analysed in 3 main organizations,

involving more than 600 Engineers

Passed 5 customers Audit with success

Updates are performed:

1) Automatically for process NC,

2) Automatically unsched event on tool

3) Manually for Scraps (After team problem solving close its actions)

Results (1/3)

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Reusing risks analysis for technology assessment

• One central risk database for every technology developement.

Launch Maturation Production Stop


Technology n life cycle


Technology n+2 life cycle



Risk DataBase

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4) Reusing risk analyses for technology assessement

• Already used for CMOS120, CMOS90, CMOS 65 ramp-up and reliability analysis



Technology n life cycle





Risk DataBase

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• More than 1 year of Yield data

Impact on operations scraps

80

82

84

86

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90

92

94

96

98

100

1 2 3 4 5 6 7 8 9 10 11 12

improvement

Still massive scraps

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• Local improvement: Organizational improvement satisfactory

– Customer feedback very positive– Learning on going: ROI achieved @ the first lot

saved !

• Global plant improvement: Learning curve still NOT satisfactory

– Confidence in analyses can theorically be improved however many difficulties are encountered. (HR issues also to reduce fire fighting)

Results (3/3) - summary

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Outline




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Main issue for linking risks and manufacturing ctrl plan

One new central question: how to get process model?

• What is f ?

Process

Measured Inputs: I

(Prod operation)

Measured Outputs: O

(Product parameters)

Measured Internal Variables: V

(control parameters)O = f(I,V)

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Thank you for the audience

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2) How to get more robust control plans ?

How to find holes in the ctrl plan ? Links between risks analyses and control plans

R2R

FDC

SPC

PT

EWS

Visu

Tool Alarm- Maintenance

CustomerNon Conformity

Impacting events

Levels of controls

Visual inspection détection

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3) Update loop improvement (1/2)

• How to get the loop more effective ?

legend

Pg: Production

System

Pd : Detection

Pa : Analyse

Pap: Perform Action plan

Risk DataBase

Impact

E (Eg, Ef, Ed)

Eg*Ef

Ap (Ag, Af, Ad)

Ed (Eg, Ef, Ed)

> update

<help in the analysis

A (Ag, Af, Ad)

Objects

Activity

Pa : probability that this activity

happens

{R} ={ R / R=(Rgi, Rfi, Rdi, Vi : confidence in

the analysis)}

1 PhD StudentAymen MILI

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3) Update loop improvement (2/2)

• How to get the loop more effective ?

Pg: Production

System

Pd : Detection

Pa : Analyse

Pap: Perform Action plan

Risk DataBase

Impact

E (Eg, Ef, Ed)

Eg*Ef

Ap (Ag, Af, Ad)

Ed (Eg, Ef, Ed)

A (Ag, Af, Ad)

{R} ={ R / R=(Rgi, Rfi, Rdi, Vi : confidence in

the analysis)}

1 PhD StudentAymen MILI

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Risk management processes audit (1/3) @ STMicroelectronics

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• 5 procedures of risks managment held by 5 different organizations

• All these procedures are isolated from each others

Audit Conclusions @ STmicro.

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• A more realistic scenario:

WIP

NC

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Case 5

2) LESS VARIATIONS1) NO SLOPE

Learning Curves – eg on quality

WANTED ON NC :

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• Production point of view• ∞ failure modes number :• Failure modes come from a preliminary risk analysis

(PRA)

Actual risk

Potential Cause/ Mechanism of Failure

OCC

N°

Item/Function Potential Failure Mode Potential Effects of

Failure Recommended Actions

Current Controls Prevention

Current Controls Detection

DET

RPN

SEV

CLASS

Risk actions

Prod operation

Thickness too low

Yield loss Equipment drift

2 SPC, PT Parameter

PM

FDC on tool

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All steps Defectivity

Residues and/or particles affecting via or line continuity--> Yield loss

6 RF 4Bi-weekly monitoring

In-line defectivity after every CMP level (line continuityES25 inspection after M2 CMP (via continuity)

4 96

All steps Defectivity

Residues and/or particles affecting via or line continuity--> Yield loss

6 Temperature 2Bi-weekly monitoring

In-line defectivity after every CMP level (line continuityES25 inspection after M2 CMP (via continuity)

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All steps UnderetchVia resistance OOSYield loss

6 C

Metalic contamination due to gasket corrosion 4 None 8 192

1/ Gasket wo Nickel2/ APC implemented

All steps UnderetchVia resistance OOSYield loss

6

Metalic contamination due to gasket corrosion 2

Gasket without Nickel

1/ Gasket wo Nickel2/ APC implemented 6 72

FDC to be implemented on lot

FMEAFMEA

1) The point of view vs risk analysis

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SPC approach in the FMEA template

• The process control Point Of View• For 1 item function: 3 associated failure modes:

– Variable too low

– Variable too high

– Variable gradien (temporal or surfacic) Toward an AUTOMATIC RISK ANALYSIS UPDATE

Actual risk


OCC

N°





DET

RPN

SEV

CLASS

Risk actions

PT Variable to control

OOC Product impact, increase scrap rate

7 Tbd ?

Cpk V

alue

TBD PT 6


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Main issue for linking risks and manufacturing ctrl plan

1) Analysis is not performed2) Link does not exist between product FMEA and

product control plan

SEV

OCC

DET

RPN

Actual risk


OCC

N°



Responsible & Target

Completion Date

Forcasted



DET

RPN

SEV

CLASS

Risk actions

Prod operation Thickness too low

Yield loss Equipment drift

2 SPC, PT Parameter

PM

FDC on tool

16 12

SEV

OCC

DET

RPN

Actual risk


OCC

N°



Responsible & Target

Completion Date

Forcasted



DET

RPN

SEV

CLASS

Risk actions

PT Variable to control

OOC Product impact, increase scrap rate

7 Tbd ?

Cpk V

alue

TBD PT 6

Are our control plan coherent toward customers needs ?


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• What happened when SI are not connected

– Every change impact, difficult to evaluate

– Multiplicaiton of way to control the process and stop the process

– No clear vision of control efficiency• It is not necessary to add cameras

on highways to reduce speed if deadly accidents are in national roads !

– Multiplication of action plan => dispersion of working teams

– Multiplication of SI to analyse the process

– Control is no more a question of facts but people lobbying

FAB IN PROCESS

Reading sens

Non conformities

Scrap

Customer reclaim

Process Ctrl Issue

Maintenance Issue

Change

8DRisk analysis

FMEAQuality analysis


Eg Analysis






R2R

FDC

SPC

PT

EWS

Visu

Tool Alarm- Maintenance

CustomerNon Conformity

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Date post:	20-Jan-2016
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1 Risk analysis for improving production ramp-up Bassetto 1, Mili 1, Siadat 2, Tollenaere 1 2 1.

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