Transcript Alphaboost: The next generation of Ultra

Transforming Technologies Presents
ALPHABOOST™
THE NEXT GENERATION OF
ULTRA-CLEAN AIR IONIZATION
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
Effects of Static Charge on
High Technology Manufacturing
Particle
attraction &
bonding to
charged surfaces
Robotic
lockup
Damage to
product
Contamination Study
A Particle Contamination Study
200 mm wafer in a Class 1 Mini-Environment
Wafer at 0 V
Wafer at 2000 V
class 1 mini environment for 6 weeks
class 1 mini environment for 6 weeks
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
5
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
CD circa 1990
500
nm
1995
2000
2005
2010
2
0
•Ionizer Performance can no longer be judged by Fed Std 209E.
•Ionizer performance must be related to KILLER Particles!
Semiconductor Front End Processing
ITRS Roadmap
2009 ITRS 2009
Roadmap
60
Critical Dimension (nm)
50
40
DRAM stagger-contacted Metal
1 (M1) ½Pitch (nm)
30
Flash Uncontacted Poly Si ½
Pitch (nm)
20
10
0
2005
2010
2015
Year
2020
2025
Semiconductor Fab: What Particle Size
Causes Yield Loss?
For the present 45 nm node (DRAM 1st Level Metal ½ Pitch)*
90 nm
Metal 1
45 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)
* 2009 Intl. Technology Roadmap for Semiconductors Update, http://www.itrs.net/
How Small is 22 nm?
Size of Small Objects
1000
100
Size (um)
10
1
0.1
0.01
0.001
Size (um)
dollar
bill
110
110mm
hair
germ
virus
killer
DNA
60
3 mm 1.00E-01
100 nm 2.20E-02
22 nm 2.00E-03
2 nm
60 mm 3.00E+00
Corona Ionizers and their
Contamination Mechanisms
The invisible contaminant
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
Particles Per Cubic Foot
10000
1000
100
10
1
0.01
0.1
1
0.1
Particle Size (Microns)
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!
Corona Ionizer 1
Particles Per Cubic Foot
100
10
1
0
0.1
0.2
0.3
0.4
0.5
0.1
Particle Size (Microns)
Extrapolation based upon normalized 1/x3 distribution accepted by the industry
0.6
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 greater
Laminar flow rate in Mini-environment, v= 60 ft/min
Wafer 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!
Effect of Particle Load on Yield
7
6
5
% Yield Loss
4
yield enhancement from
electrostatic micro
contamination control
3
yield degradation from corona
ionizer particles
2
1
Net Yield Improvement
0
1990
-1
1995
2000
2005
Year
-2
-3
2010
2015
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:
There are lots of organic vapors in a semiconductor cleanroom.
Cyclohexasiloxane
These chemicals are “cooked” by corona ionizers.
ANY Corona Ionizer in Fab Air will be
Effected by these AMCs.
The corona process generates heat at the very tip of the emitter
25oC
W=iV
oC
100
=5 mA*10kV
500oC
oC mW of heat
750=50
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 Particles
 Corona Ionizers all Must be Cleaned and ReBalanced every 1-3 months – this is expensive
and time consuming.
AlphaBoost® Eliminates all of these Issues
AlphaBoost – the Advantages of
Corona Without the Tradeoffs
The invisible contaminant
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 Emitter Technology Employs
Po210, a 5.3 MeV Alpha Source
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.
The Alphas Collide with Air
Atoms and Ionize Them
ion
ion
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
 Don’t eat alpha sources
by
 Don’t smoke alpha sources!
 a sheet of paper
 Return them after they are
 or by the dead skin covering
your body
 Once they stop, Alpha
particles become harmless
helium atoms
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
Half Cycle ~
Laminar Flow Velocity
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 *
1.25.2±0.9 particles/ft3 with ionizer ON and 3.3±0.15 particles/ft3 with ionizer OFF
*Robert Wilson, ESDA Symposium 1987, A Novel Nuclear Ionization Source Employing a
Pulsed Electric Field
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
ULPA
80 fpm air flow
Typical Discharge
Performance 25 cm below the
ionizer :
75 cm
Discharge times ± 7 seconds
Voltage Swing +5 V
25 cm
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
Critical Dimension (nanometers)
60
50
40
30
20
10
0
2005
2010
2015
Year
2020
2025