Wire Saw Abrasive Grain Cleaning for Wafer Purity

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Solution Overview

Problem

The reuse of abrasive grains in wire saw slicing introduces significant contamination of semiconductor wafers with metal impurities, particularly copper, due to the brass plating on the wire, leading to degraded wafer quality and increased production costs.

Innovation Solution

Treating used abrasive grains with a mixed liquid of sulfuric acid and hydrogen peroxide to reduce copper concentrations to 1 ppm or less, allowing for their reuse in the slicing process while minimizing metal impurity contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If abrasive grains are reused to reduce manufacturing cost, then productivity is improved, but metal impurity contamination increases

Engineering Contradiction:

Improvewafer production efficiencyVSAvoidmetal impurity contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by treating abrasive grains with a cleaning solution before reuse to remove copper contamination. This pre-treatment ensures that when abrasive grains are reused for cost and productivity benefits, the harmful metal impurity contamination is already eliminated, allowing safe reuse without compromising wafer quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the chemical state of the abrasive grains by treating them with a cleaning solution containing chelating agents. This parameter change transforms the abrasive grains from a contaminated state (with copper impurities) to a clean state (with copper removed), enabling their safe reuse while maintaining cutting effectiveness

Inventive Principle:

Principle #35Parameter changes

2Strength

If wire with brass plating is used for slicing, then wire strength is improved, but copper elution into slurry increases

Engineering Contradiction:

Improvewire tensile strengthVSAvoidcopper elution

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of copper elution from brass-plated wire into a treatable contamination issue. By collecting and treating the slurry with chelating agents, the copper that elutes from the wire is removed from the abrasive grains, allowing the wire to continue being used for its strength benefits while the harmful copper contamination is systematically eliminated

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces a cleaning solution with chelating agents as an intermediary between the brass-plated wire and the abrasive grains. This intermediary substance binds to copper ions eluting from the wire, preventing copper adhesion to abrasive grains and thereby eliminating the contamination pathway while allowing the wire to maintain its brass plating for strength

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If abrasive grains are reused without treatment, then manufacturing cost is reduced, but wafer purity deteriorates

Engineering Contradiction:

Improvemanufacturing costVSAvoidwafer purity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by implementing a treatment step before abrasive grain reuse. The cleaning solution with chelating agents is applied to remove copper contamination in advance, ensuring that when abrasive grains are reused for cost reduction, wafer purity is maintained through this pre-treatment process

Inventive Principle:

Principle #10Preliminary action

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 effectively suppresses metal impurity contamination in wafers, producing high-purity wafers with reduced copper concentrations and lower production costs by reusing treated abrasive grains.

Implementation Method 1

a used portion of the abrasive grains are subjected to a treatment with a mixed liquid of sulfuric acid and hydrogen peroxide

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

the abrasive grains subjected to the treatment are reused for the slicing of a workpiece

Methodology Applied

Scientific EffectChemical dissolution: Solvation

Data Source

PatentUS10189181B2Method for slicing workpiece and processing liquid

Publication Date: 2019.01.29 SHIN ETSU HANDOTAI CO LTD

AI summary

The present invention is a method for slicing a workpiece, including: forming a wire row by a wire spirally wound between a plurality of wire guides and traveling in an axial direction, and pressing a workpiece against the wire row while supplying a processing liquid containing abrasive grains to a contact portion between the workpiece and the wire, wherein a used portion of the abrasive grains are subjected to a treatment with a mixed liquid of sulfuric acid and hydrogen peroxide, and the abrasive grains subjected to the treatment are reused for the slicing of a workpiece. This makes it possible to slice a workpiece with suppressing contamination of a wafer with metal impurities when abrasive grains are reused in slicing a workpiece by use of a wire saw.