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Published byAdele Crawford Modified over 9 years ago
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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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Numerical Simulations Fluid Thickness Thermal Gradients Mixing Measurements Polishing Data Results Year 3 Integration Research Strategy Friction Data FdFd
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Polishing Platform 100 RPM Struers RotoPol-31 Drill Press Weighted Traverse Two Aligned 12 Bit Camera Three Way Solenoid Valve Tagged Slurry Slurry
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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 Interrogation Region Wafer Post Examining; -Mean slurry age -Residence time -Slurry Gradients (flat pads) -Drag on wafer -fluid thickness measurements Pad
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Repeatability Flat Pad Grooved Pad Manufacturer: Cabot Slurry Flow Rate: 35 cc/min Wafer Down Force: 4 psi Platen Speed: 60 rpm X-Y Groove Depth: 20 mils Time (sec) Percent New Slurry
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Repeatability Flat Pad Grooved Pad Manufacturer: Rodel Slurry Flow Rate: 35 cc/min Wafer Down Force: 4 psi Platen Speed: 60 rpm X-Y Groove Depth: 20 mils Time (sec) Percent New Slurry
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Slurry Flow Rate Flat Pad Grooved Pad Manufacturer: Rodel Slurry Flow Rate: x cc/min Wafer Down Force: 4 psi Platen Speed: 60 rpm X-Y Groove Depth: 20 mils Time (sec) Percent New Slurry
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In Situ Conditioning Time (sec) Percent New Slurry Oscillation Period
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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 Flat Pad Grooved Pad Time (sec) Percent New Slurry
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Static Case Pad deformation: (4 psi, 0 rpm) Image of a single pad Thickness profile as determined by ratiometric technique
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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 PAD Trapped slurry Asperity? Surface tension?
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Static Fluid Thickness Measurements
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Friction Measurements
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Cabot Pad 6 psi down force 35 cc/min 30 rpm platen speed 20 mils x-y groove depth Friction Data ~0.5 Hz Sine Wave Time (sec) Coefficient of Friction
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Friction Measurements Down Force (psi) Friction Force (lbs)
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Stribeck Curve Coefficient of Friction Sommerfield Number: (Viscosity*Linear 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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