CMP FtF 9 Nov 06 Friction Updates 1. Last FtF • Past issues & solutions 2. Latest data • CoF vs. slurry dilution • CoF vs. rotation rate • Fz vs. slurry dilution 3. Laser displacement sensor tests • Feasibility • Specifications 4. Thesis Roadmap • Microscale friction and polishing model • Macroscale measurements 5. Questions/Requests 6. Future work Jim Vlahakis PhD. Candidate Tufts University
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CMP FtF 9 Nov 06 Friction Updates 1.Last FtF Past issues & solutions 2.Latest data CoF vs. slurry dilution CoF vs. rotation rate Fz vs. slurry dilution.
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CMP FtF9 Nov 06
Friction Updates1. Last FtF
• Past issues & solutions
2. Latest data• CoF vs. slurry dilution• CoF vs. rotation rate• Fz vs. slurry dilution
3. Laser displacement sensor tests
• Feasibility• Specifications
4. Thesis Roadmap• Microscale friction and
polishing model• Macroscale
measurements
5. Questions/Requests6. Future work
Jim VlahakisPhD. CandidateTufts University
CMP FtF9 Nov 06
Friction Updates – Last FtF
• External noise issues• New wafer motor power
supply eliminated noise
• Issues concerning slurry dilution
• Moved from 9:1 to 3:2 dilution, more in line with industry practice
• Data runs at 30/60rpm• Now using 60/120rpm (.5
& 1m/s), more in line with industry practice
• Irregularities due to changes in wafer shape
• Controls in place to monitor wafer shape
CMP FtF9 Nov 06
Friction Updates – Latest Data
• CoF vs. slurry dilution• 60rpm & 1.7psi• Note large CoF (and
large σ) for pure slurry. A result of shear thickening?
• CoF remains fairly constant over a wide range of slurry dilutions
• CoF for pure H2O seems strongly dependent on pH
• Next steps• study slurry
compositions in the range of 1 part H2O to 2/3/5/7 parts slurry
• Investigate pH dependence for H2O
• Perform experiment “backwards”
CoF vs. slurry composition
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0.3
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0.5
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1
1.1
1.2
pure slurry 1 to 1 3 to 2 3 to 1 5 to 1 7 to 1 9 to 1 pHadjusted
H2O
slurry composition
Co
F
CMP FtF9 Nov 06
Friction Updates – Latest Data
CoF vs. rotation rate, note development of CoF plots and spectra
CMP FtF9 Nov 06
Friction Updates – Latest Data
CoF vs. rotation rate, note development of CoF plots and spectra
CMP FtF9 Nov 06
Friction Updates – Latest Data
• Fx vs. slurry dilution• 60rpm - 1.7psi• Decrease in Fz tracks
decrease in density of slurry as it is mixed with H20
• Increasing σ corresponds to increasing chatter (except for pure slurry case)
• Next steps• study slurry
compositions in the range of 1 part H2O to 2/3/5/7 parts slurry
• Investigate pH dependence for H2O
Fz vs. slurry composition
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pure slurry 1 to 1 3 to 2 3 to 1 5 to 1 7 to 1 9 to 1 pHadjusted