Chamfer Polishing Method for Semiconductor Wafer Edge Roll-Off

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Solution Overview

Problem

Existing semiconductor wafer manufacturing methods face challenges in preventing edge roll-off during mirror-polishing, as soft polishing cloths used for chamfered portions can cause over-polishing, and methods involving resin protection films increase production costs and complexity.

Innovation Solution

A two-stage mirror-finishing chamfer polishing method using an abrasive-grain-free polishing solution with a polymer, where the first stage employs an unwoven fabric polishing pad with low compression rate for pre-finish polishing and a suede polishing pad with high compression rate for finish polishing, ensuring the oxide film on the top and bottom sides acts as a stopper to prevent over-polishing on the chamfered portion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a resin protection film is formed on top and bottom sides of the wafer to prevent over-polishing, then the edge roll-off is prevented, but the production cost increases due to additional washing processes

Engineering Contradiction:

Improveflatness of wafer surfaceVSAvoidproduction cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention replaces the chemical/mechanical protection film method with a purely mechanical solution: a polishing pad with differentiated hardness layers. The harder sponge layer mechanically prevents the polishing cloth from contacting the top and bottom sides, eliminating the need for resin protection films and associated washing processes, thus reducing production cost while maintaining flatness control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If a resin protection film is formed on top and bottom sides of the wafer to prevent over-polishing, then the edge roll-off is prevented, but the production complexity increases

Engineering Contradiction:

Improveflatness of wafer surfaceVSAvoidnumber of manufacturing steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention substitutes the multi-step process of forming and removing resin protection films with a single-step mechanical solution using a differentiated hardness polishing pad. The pad's structure inherently prevents over-polishing during the chamfered portion polishing process, eliminating additional manufacturing steps and reducing production complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method enhances the flatness and reduces microroughness of the outer peripheral portion while efficiently removing scars and impressions on the chamfered portion, effectively preventing edge roll-off without increasing production costs.

Implementation Method 1

an oxide film 101A present on a chamfered portion 101 of a semiconductor wafer 100 is removed in the first step

Methodology Applied

Scientific EffectOxide film formation: Oxidation

Implementation Method 2

a first step for polishing the chamfered portion using an unwoven fabric polishing pad and abrasive-grain-containing polishing solution

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS9991110B2Method for manufacturing semiconductor wafer

Publication Date: 2018.06.05 SUMCO CORP

AI summary

A mirror-finishing chamfer polishing is applied using an abrasive-grain-free polishing solution to a chamfered portion of a semiconductor wafer having an oxide film on a top side or the top and bottom sides of the semiconductor wafer and having no oxide film on the chamfered portion. Further, prior to the mirror-finishing chamfer polishing, a pre-finish mirror chamfer polishing is applied using an abrasive-grain-containing polishing solution to the chamfered portion of the semiconductor wafer having the oxide film on the top side or the top and bottom sides and on the chamfered portion.