Examination of some key CMP input parameters on slurry fluid mechanics

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Examination of some key CMP input parameters on
slurry fluid mechanics PI Chris
Rogers Researchers Jonathan Coppeta Chris
Duska Jeremy Javidi Samuel Brodsky
Corporate Sponsors Cabot Corporation (Frank
Kaufman) Intel Corporation (Ara
Philipossian) VEECO Corporation
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Research Strategy
Year 3 Integration
Results
Numerical Simulations
Fluid Thickness
Thermal Gradients
Mixing Measurements
Polishing Data
Fd
Friction Data
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Polishing Platform
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Conditioning System
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Design of Experiment
43 Runs Variables -Pad Manufacturer (Cabot,
Rodel, Freudenberg) -Pad Groove Depth (0-40
mils) -Wafer Down Force (2-6 psi) -Platen Speed
(30-90 rpm) -Slurry Flow Rate (20-50
ml/min) Constants -Groove Style (X-Y Grooving,
0.025 width) -Head Speed (60 rpm) -Head
Position (3/4 wafer to platen edge) -Injection
Location (pad center) -Conditioning (163 Micron
diamond grit)
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Design of Experiment
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Slurry Transport
Examining -Mean slurry age -Residence
time -Slurry Gradients (flat pads) -Drag on
wafer -fluid thickness measurements
Wafer
Post
Interrogation Region
Pad
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Repeatability
Manufacturer Cabot Slurry Flow Rate 35
cc/min Wafer Down Force 4 psi Platen Speed 60
rpm X-Y Groove Depth 20 mils
Grooved Pad
Percent New Slurry
Flat Pad
Time (sec)
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Repeatability
Manufacturer Rodel Slurry Flow Rate 35
cc/min Wafer Down Force 4 psi Platen Speed 60
rpm X-Y Groove Depth 20 mils
Grooved Pad
Percent New Slurry
Flat Pad
Time (sec)
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Slurry Flow Rate
Manufacturer Rodel Slurry Flow Rate x
cc/min Wafer Down Force 4 psi Platen Speed 60
rpm X-Y Groove Depth 20 mils
Grooved Pad
Percent New Slurry
Flat Pad
Time (sec)
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In Situ Conditioning
Oscillation Period
Percent New Slurry
Time (sec)
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Platen Speed
Manufacturer Freudenberg Slurry Flow Rate 35
cc/min Wafer Down Force 4 psi Platen Speed x
rpm X-Y Groove Depth 20 mils
Grooved Pad
Percent New Slurry
Flat Pad
Time (sec)
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Static Case
Pad deformation (4 psi, 0 rpm)
Thickness profile as determined by ratiometric
technique
Image of a single pad
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Pad Profile
Rodel Pad
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Radial Profile (static cases)
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Static Fluid Thickness Measurements
wafer
Asperity? Surface tension?
Trapped slurry
PAD
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Static Fluid Thickness Measurements
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Friction Measurements
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Friction Measurements
Friction Data
0.5 Hz Sine Wave
Cabot Pad 6 psi down force 35 cc/min 30 rpm
platen speed 20 mils x-y groove depth
Coefficient of Friction
Time (sec)
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Friction Measurements
Friction Force (lbs)
Down Force (psi)
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Stribeck Curve
Coefficient of Friction
Sommerfield Number (ViscosityLinear
Speed)/Pressure
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Flow Regime
Stribeck Curve
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Polishing Rates for Crown Glass
3.0 Diameter wafer
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Polishing Rates for BK7
3.5 Diameter wafer
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Conclusion

• -Functional scaled down polishing platform
• Polishing data
• Slurry mixing measurements
• Slurry film thickness measurements
• Friction measurements
• -Beginning of DOE analysis
• Slurry mixing rates depend on
• Platen speed
• Flow rate
• In situ conditioning

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Future Directions
-Optimize Struers Polishing performance -New DOE
study on pad material properties -Scale results
to an industrial polisher -Verify data on an
IPEC 372 polisher -Correlate fluid mechanics to
polishing performance
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