1 Fixed Abrasive Design for Chemical Mechanical Polishing

1 Fixed Abrasive Design for Chemical Mechanical Polishing SFR Workshop May 24, 2001 Edward Hwang, David Dornfeld Berkeley, CA 2001 GOAL: To build integrated CMP model for basic mechanical and chemical elements. Develop periodic grating metrology by 9/30/2001. 5/24/2001

2 Content • Micro-Fabrication Techniques for Fixed Abrasive for Chemical Mechanical Polishing (CMP) • Control of Abrasive Shape • Construction of Micro-Scale Wear Mode Diagram 5/24/2001

3 Background Study & Examples Fixed Abrasive – Cylindrical Shape Pad Conditioner – Random geometry Abrasive shape decides the wear mode 5/24/2001

4 Standard Fabrication Process PR Oxide Si Thermal Oxidation Oxide Si Uniform Pattern of Oxide Islands Silicon Etching Process Determines Abrasive Shape 5/24/2001

5 Oxidation Sharpening limitations of various abrasive shape with the etching process due to crystallographic structure of silicon Planar Oxidation Anomaly of Silicon Oxidation at Regions of High Curvature due to Stress Configuration HF Etching Low Cost Non-Planar Oxidation 5/24/2001

6 Simulations with TSUPREM Dry etching + 6 consecutive dry oxidations at 950 C for 2 ½ hour Wet etching + 6 consecutive wet + 4 consecutive dry oxidations at 950 C for 2 ½ hour Isotropic etching + 6 consecutive dry oxidations at 950 C for 2 ½ hour 2 -step wet etching + 4 consecutive wet + 4 Consecutive dry oxidations at 950 C for 2 ½ hour 5/24/2001

7 Scanned Images Wet Etching + Oxidation Dry Etching + Oxidation process sharpens the abrasive and sharpened image depends on the precursor 5/24/2001

8 Lift-Off Technique • Additive Process • Abrasive Shape silicon oxide thickness, the opening deposited material silicon dioxide silicon substrate 5/24/2001

9 2002 and 2003 Goals Third axis parameters to be determined Pin-on-disk set-up will be used to complete wear mode diagram Integrate initial chemical models into basic CMP model. Validate predicted pattern development by 9/30/2002. Develop comprehensive chemical and mechanical model. Perform experimental and metrological validation by 9/30/2003. 5/24/2001