Back Surface Polishing Tool for Substrate Foreign Matter Removal

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Solution Overview

Problem

Conventional methods for cleaning the back surface of substrates, such as wafers, are inefficient in removing foreign matters, particularly those with deposited films, and fail to effectively cover the entire surface, leading to issues like patterning shifts and focal length errors.

Innovation Solution

A method involving a polishing tool placed in sliding contact with both the outer circumferential and center-side regions of the substrate's back surface, using a combination of first and second polishing units with transfer robots to ensure comprehensive removal, utilizing pure water as the polishing liquid to scrape away foreign matters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a pen-type brush or roll sponge is used to scrub the wafer while rotating, then the cleaning process is simple to operate, but the removal rate of foreign matters is low and it is difficult to remove foreign matters from the entire back surface

Engineering Contradiction:

Improveease of operationVSAvoidremoval rate of foreign matters

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent replaces the conventional mechanical scrubbing method (pen-type brush or roll sponge) with a polishing tool that performs sliding contact polishing. This substitution transforms the cleaning mechanism from simple friction-based scrubbing to a more effective polishing action that achieves both high removal rate and complete surface coverage while maintaining operational simplicity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters by introducing sliding contact motion between the polishing tool and the wafer back surface. The polishing tool moves in sliding contact while the wafer rotates, creating effective polishing action that removes foreign matters including those with deposited films, thereby improving the removal rate without complicating the operation

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a pen-type brush or roll sponge is used to scrub the wafer, then the device complexity is low, but it is difficult to remove foreign matters from the entire back surface

Engineering Contradiction:

Improvedevice complexityVSAvoidcoverage of back surface

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent replaces the simple scrubbing device with a polishing tool system that provides sliding contact polishing. This substitution maintains relatively low device complexity while dramatically improving the coverage of the back surface, enabling removal of foreign matters from the entire area including edge regions

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If conventional cleaning techniques are used, then the process is simple, but the removal rate of foreign matters with deposited films is particularly low

Engineering Contradiction:

Improveease of manufactureVSAvoidremoval rate of foreign matters with deposited films

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent replaces conventional cleaning techniques with sliding contact polishing using a polishing tool. This substitution maintains ease of manufacture while achieving high removal rate of foreign matters with deposited films, as the polishing action effectively removes even adhered contaminants from the entire back surface

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 approach enables a high removal rate of foreign matters from the entire back surface of the substrate, preventing defects and ensuring accurate device fabrication by effectively polishing both regions.

Implementation Method 1

a polishing tool 44 is placed in sliding contact with the back surface of the substrate W to thereby scrape away the back surface slightly

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS9808903B2Method of polishing back surface of substrate and substrate processing apparatus

Publication Date: 2017.11.07 EBARA CORP

AI summary

A polishing method which can remove foreign matters from an entire back surface of a substrate at a high removal rate is provided. The polishing method includes placing a polishing tool in sliding contact with an outer circumferential region of a back surface of a substrate while holding a center-side region of the back surface of the substrate, and placing a polishing tool in sliding contact with the center-side region of the back surface of the substrate while holding a bevel portion of the substrate to polish the back surface in its entirety.