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ALPHABOOST™THE NEXT GENERATION OF
ULTRA-CLEAN AIR IONIZATION
Transforming Technologies Presents
Outline
Microcontamination, Electrostatics and High Tech Manufacturing
Corona Ionizers and their Contamination Mechanisms collide with the 25nm node
Alphaboost® The Advantages of Corona without the Tradeoffs
Summary
Micro-Contamination in High Technology Manufacturing
Particle attraction & bonding to
charged surfaces
Damage to product
Robotic lockup
Effects of Static Charge on High Technology Manufacturing
5
Contamination Study
Wafer at 0 Vclass 1 mini environment for 6 weeks
Wafer at 2000 Vclass 1 mini environment for 6 weeks
200 mm wafer in a Class 1 Mini-Environment
Data from Frank Curran, MS thesis, "The Effects of Static Charge on Silicon Wafers in the Semiconductor Industry," The Engineering Council of England, Nov. 1997
A Particle Contamination Study
Electrostatic Attraction Defeated by Mini-Environment Ionizers
“Implementing a Static Control Program to Increase the Efficiency of Wet Cleaning Tools” Micro Magazine June 2001. Long, CW, Peterman, J and Levit, L.B. http://www.micromagazine.com/archive/06/01/long.html
In 1990 Corona Ionization Was the State of the Art
Corona Ion Bars were available with Sub Class 1 Cleanliness
This was absolutely acceptable for semiconductor manufacturing
Fed Std 209E Class 1 requires less than one 500 nm particle/cubic foot of fab air.
The CD Compared to 500 nm Particles
500 nm
1995
2000
200520
2010
CD circa 1990
• Ionizer Performance can no longer be judged by Fed Std 209E.
• Ionizer performance must be related to KILLER Particles!
2008 2010 2012 2014 2016 2018 2020 2022 2024 20260
10
20
30
40
50
60
2009 ITRS Roadmap
DRAM stagger-contacted Metal 1 (M1) ½Pitch (nm)Flash Uncontacted Poly Si ½ Pitch (nm)
Year
Criti
cal D
imen
sion
(nm
)
Semiconductor Front End Processing
2009 ITRS Roadmap
Semiconductor Fab: What Particle Size Causes Yield Loss?
For the present 45 nm node (DRAM 1st Level Metal ½ Pitch)*
Metal 1
* 2009 Intl. Technology Roadmap for Semiconductors Update, http://www.itrs.net/
90 nm45 nm
45 nm
Either of these contaminating particles can kill the die!
Define killer particle size as a ≥ ½ * 45 nm
for this 45 nm technology (allow for uneven pitch)
How Small is 22 nm?
dol-lar bill
hair germ
virus
killer
DNA
Size (um)
110 60 3 0.1 0.022
0.00200000000000001
0.003162277660168380.0316227766016838
0.3162277660168383.1622776601683831.6227766016838316.227766016838
Size of Small Ob-jects
Siz
e (
um
)
110 mm 60 mm 3 mm 100 nm 22 nm 2 nm
The invisible contaminant
Corona Ionizers and their Contamination Mechanisms
Corona Ionizers Use Sharp Points to Generate an Intense Electric Field
In time the plasma at the tips erodes the points.
Where did the material go?
This erosion is the main source of large particles and you pay extra to get points that do not erode easily.
But they still erode.
Even silicon points must be replaced every two years due to erosion.
Photograhs from http://www.ion.com/documents/technical/EmitterMaintenance.pdf
Beyond Erosion, All Corona Ionizers Turn AMC gasses into Solid Particles
This is Called Agglomeration
Range of Agglomerated Particle Emissions from High Technology Air Ionizers
0.01 0.1 10.1
1
10
100
1000
10000
Particle Size (Microns)
Part
icle
s P
er
Cu
bic
Foot
Data based upon a survey or readily available published results. E.G. see www.simco.com, www.ion.com, www.desco.com, www.meech.com
Specifying a Corona Ionizer at 0.5 mm Made Sense in 1990 but NOT in 2011!
0 0.1 0.2 0.3 0.4 0.5 0.60.1
1
10
100
Corona Ionizer 1
Particle Size (Microns)
Part
icle
s P
er
Cu
bic
Foot
Extrapolation based upon normalized 1/x3 distribution accepted by the industry
What is the Impact of These Tiny Particles? For Particles from the Cleanest Corona Ionizer…
Particle Density, (r r)=12 particles/ft3 @ 22.5 nm or greaterLaminar flow rate in Mini-environment, v= 60 ft/minWafer Residence Time in EFEM, t= 1 minute
The Number of Particles moving over a wafer :Take d=300 mm, N=(12part/ft3) (p d/2)2vt=267 particles 22.5 nm or greater!
Particles from Ionizers are Charged so Most (~50%) Will Stick!
For a 45 nm process with 22.5 nm as a killer particle size,
Particle Load/wafer~2700/2=267 particles @22.5 nm orgreater.
Assume 2% actually kill a die.Assume 500 die per wafer, 400 process steps.
Particle Limited Yield=98.67%Particle Limited Yield (1000 die/wafer)=99.27%
What Happens at the 25 nm Node?
For a 25 nm process with 10 nm as a killer particle size,
Particle Load/wafer~2700/2=1350 particles.
Assume 2% actually kill a die.Assume 500 die per wafer, 400 process steps.
Particle Limited Yield=94%!Particle Limited Yield (1000 die/wafer)=96%!
This yield loss cannot be tolerated!
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
-3
-2
-1
0
1
2
3
4
5
6
7
Effect of Particle Load on Yield
yield enhancement from electrostatic micro contam-ination controlyield degradation from corona ionizer particlesNet Yield Improvement
Year
% Y
ield
Loss
Are You an Adrenaline Junkie?
Which do You Want?
Fab Contamination Particle Load Ionizer Contamination Load? Neither?
We have found a way to allow neither!It’s Called AlphaBoost®
To Understand the Advantages of AlphaBoost®, Examine how these Particles are Made:
Cyclohexasiloxane
These chemicals are “cooked” by corona ionizers.
There are lots of organic vapors in a semiconductor cleanroom.
ANY Corona Ionizer in Fab Air will be Effected by these AMCs.
W=iV =5 mA*10kV =50 mW of heat750oC500oC100oC
25oC
The corona process generates heat at the very tip of the emitter
The heat disassembles the AMCs into radicals and cooks the “soup”.
A Free Radical Soup in an Electric Field will Grow Particles!
High Voltage On Point Creates Strong Electric Fields
Particle is drawn in by dielectrophoretic force
Particle picks up charge from emitter point
Particle is repelled from emitter point
+ -
+ -
+ -
As the Tiny Particle Crosses the Plasma (Twice) it Picks up Free Radicals from the Soup
Agglomeration: Molecules to Nano-Clusters to Micro-Clusters
Agglomeration in the Macro World:
Watch water droplets slide down the outside side of a cold glass of beer
Hail Falling From the clouds
Maintenance of Corona Ionizers Dealing with the Fuzz
Emitter points must be cleaned every few months and the ionizer must be rebalanced with a CPM
Summary:
Corona Ionizers ALL Make Sub Micron Particles
Most also make larger ParticlesCorona Ionizers all Must be Cleaned
and Re-Balanced every 1-3 months – this is expensive and time consuming.AlphaBoost® Eliminates all of these Issues
The invisible contaminant
AlphaBoost – the Advantages of Corona Without the Tradeoffs
Alpha Emitter Technology – the Engine in AlphaBoost ®
Alpha Technology Uses No High Voltage (kV) No Emitter Points No Electrical Power
Alpha Technology Requires No Cleaning No Adjusting
Alpha particles move up to 4 cm from the source and stop
They become Helium atoms and drift away harmlessly
As they Travel, each one makes ~250,000 ion Pairs`
No electricity is required to make ions
Ion output is automatically balanced with no adjustments.
Alpha Emitter Technology Employs Po210, a 5.3 MeV Alpha Source
The Alphas Collide with Air Atoms and Ionize Them
ionion
ion
ion
ion
ion ion
ion
ion ion
The process continues as long as the source is active ((1-2 years)
Is the Alpha Source Safe?
Yes! Safety Rules:
Alpha particles are stopped by a sheet of paper or by the dead skin
covering your body
Once they stop, Alpha particles become harmless helium atoms
Don’t eat alpha sources
Don’t smoke alpha sources!
Return them after they are spent They convert into lead
Ordinary Alpha Ionizers In Laminar Airflow may not Discharge an Entire EFEM
ULPA
No Ions Here!
Ions Recombine Before they Reach the Target
Alphaboost™ Separates Ion Polarities and Push Ions down Electrostatically in Waves
±300 - 500 V
Height of EFEM
Laminar Flow VelocityHalf Cycle ~
Ions move 1+ m!
The Product is Compact and Easy to Mount in an EFEM
The ionizing element is the size of a coin
AlphaBoost Has
No KiloVolt voltages No Need for Balance Adjustment No Corona No Sharp Points to Wear Out No Fuzz Ball Creation Mechanism No Gas to Particle Agglomeration
Mechanism
Ionizer LPC Cleanliness Study *
94.2±4 particles/ft3 with ionizer ON and 95.5±3 particles/ft3 with ionizer OFF
*Robert Wilson, ESDA Symposium 1987, A Novel Nuclear Ionization Source Employing a Pulsed Electric Field
Ionizer CNC Cleanliness Study *
*Robert Wilson, ESDA Symposium 1987, A Novel Nuclear Ionization Source Employing a Pulsed Electric Field
1.25.2±0.9 particles/ft3 with ionizer ON and 3.3±0.15 particles/ft3 with ionizer OFF
AlphaBoost® Discharge Performance
Operation of AlphaBoost® in an EFEM
ULPA
80 fpm air flow Typical Discharge Performance 1 m below the ionizer :
Discharge times ± 25 seconds
Voltage Swing +15 V
Set to ±500 V Bias Swing
Frequency 2.0 Hz
Operation of AlphaBoost® Adjacent to a Wafer Aligner
ULPA80 fpm air flow
75 cm
25 cm
Typical Discharge Performance 25 cm below the ionizer :
Discharge times ± 7 seconds
Voltage Swing +5 V
Set to ±300V Bias Swing
Frequency 4.0 Hz
AlphaBoost® Benefits
Fast Discharge time Balanced by Physics, not by
Adjustment Inherently Stable No Fuzzball to Clean Off No points to Replace No CPM Balance Adjustment Same Delivery Efficiency as Corona
Technology
AlphaBoost – Conclusions
Conclusions
Records went from the phonograph cylinder to 78 RPM hard plastic to Vinyl High Fidelity Recordings and Underwent Constant Improvement of the Same Technology But they Eventually they Became Obsolete – limited life, sensitivity to
handling & to dust
Cameras went from the pin-hole to lens to multi element lenses but it took digital photography to satisfy today’s photographers.
Corona Ionizers underwent Technology boosts from Tungsten to Titanium to Silicon points and from AC to DC to Pulsed DC to Complex Waveforms But Technology has passed them by
Electricity was Generated by Burning Dirty Coal in 1900. Now Clean Solar Electrical Power is Coming on Line rapidly!
Semiconductors at the 25 nm Node and Beyond Require Alphaboost® to Fab Chips Cleanly and Economically
2008 2010 2012 2014 2016 2018 2020 2022 2024 20260
10
20
30
40
50
60
Year
Criti
cal D
imen
sion
(nan
omet
ers)