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Fixed Abrasive Design for Chemical Mechanical Polishing

SFR WorkshopMay 24, 2001

Edward Hwang, David DornfeldBerkeley, CA

2001 GOAL: To build integrated CMP model for basic mechanical and chemical elements. Develop periodic grating metrology by

9/30/2001.

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Content

• Micro-Fabrication Techniques for Fixed Abrasive for Chemical Mechanical Polishing (CMP)

• Control of Abrasive Shape

• Construction of Micro-Scale Wear Mode Diagram

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Background Study & Examples

Abrasive shape decides the wear mode

Fixed Abrasive – Cylindrical Shape

Pad Conditioner – Random geometry

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Standard Fabrication ProcessPR

Oxide

Si

Oxide

Si

Thermal Oxidation

Uniform Pattern of Oxide Islands

Silicon Etching

Silicon Etching Process Determines Abrasive Shape

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Oxidation Sharpening

Planar Oxidation

Non-Planar Oxidation

Anomaly of Silicon Oxidation at Regions of High Curvature due to Stress Configuration

HF Etching

Low Cost

limitations of various abrasive shape with the etching process due to crystallographic structure of silicon

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Simulations with TSUPREM

Dry etching + 6 consecutive dry oxidations at 950 C for 2 ½ hour

Isotropic 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

2-step wet etching + 4 consecutive wet + 4 Consecutive dry oxidations at 950 C for 2 ½ hour

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Scanned Images

Oxidation process sharpens the abrasive and sharpened image depends on the precursor

Dry Etching + Oxidation

Wet Etching + Oxidation

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Lift-Off Technique

• Additive Process

• Abrasive Shape

deposited material

silicon dioxidesilicon substrate

silicon oxide thickness, the opening

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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.