Polishing Composition for Silicon Substrates with Aggregation Inhibitor

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Solution Overview

Problem

Current polishing compositions for semiconductor substrates face challenges in reducing light point defects (LPDs) caused by aggregates of silica particles and water-soluble polymers, which also lead to filter clogging and inadequate dispersibility of abrasive grains, while maintaining high hydrophilicity and polishing efficiency.

Innovation Solution

A polishing composition comprising abrasive grains, a water-soluble polymer, an aggregation inhibitor, and water, with a specific particle size distribution and inhibitor ratio to minimize aggregation and enhance dispersibility, thereby improving filtration properties and surface smoothness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a water-soluble polymer with high molecular weight is used to impart hydrophilicity to the substrate surface, then the hydrophilicity is improved, but aggregates form with silica particles causing light point defects

Engineering Contradiction:

Improvehydrophilicity of substrate surfaceVSAvoidlight point defects from aggregates

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A surfactant is introduced as an intermediary substance between the water-soluble polymer and silica particles. The surfactant adsorbs onto the silica particle surfaces and interacts with the polymer, preventing direct aggregation while maintaining the polymer's hydrophilicity-imparting function on the substrate surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical parameters of the polishing composition by adding a surfactant with specific HLB value (8-16). This parameter change modifies the interfacial properties between polymer and particles, preventing aggregation while preserving the desired hydrophilicity effect on the substrate.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If filtration is applied to remove aggregates from the polishing composition, then light point defects are reduced, but the filter clogs frequently requiring frequent exchange

Engineering Contradiction:

Improvelight point defectsVSAvoidfilter operation continuity

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The surfactant is added to the polishing composition in advance to prevent aggregate formation before filtration occurs. This preliminary protective action reduces the burden on the filtration system, allowing filters to operate longer without clogging while still achieving low LPD levels.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If a surfactant is added to improve the dispersibility of abrasive grains, then the polishing rate is improved, but no water-soluble polymer with high molecular weight is included to prevent aggregation

Engineering Contradiction:

Improvepolishing rateVSAvoiddispersibility stability with polymer

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The invention merges the functions of multiple additives by combining a surfactant (for dispersibility and polishing rate) with a high molecular weight water-soluble polymer (for aggregate prevention and hydrophilicity). The surfactant handles particle dispersion while the polymer maintains compositional stability and surface properties.

Inventive Principle:

Principle #5Merging (Combining)

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

The composition achieves high hydrophilicity, reduced LPDs, and improved dispersibility of abrasive grains, leading to enhanced polishing performance and surface accuracy, including reduced scratches and improved filtration stability.

Implementation Method 1

This protective film imparts hydrophilicity to the surface of the polished substrate

Methodology Applied

Scientific EffectHydrophilicity: Hydrophile

Implementation Method 2

containing an aggregation inhibitor... R1/R2 is 1.3 or less, indicating effective inhibition of particle aggregation

Methodology Applied

Scientific EffectAggregation inhibition: Dispersion (of waves)

Data Source

PatentUS9579769B2Composition for polishing purposes, polishing method using same, and method for producing substrate

Publication Date: 2017.02.28 FUJIMI INCORPORATED

AI summary

Provided is a polishing composition, which comprises abrasive grains, a water-soluble polymer, an aggregation inhibitor and water. The ratio R1/R2 is 1.3 or less, where R1 represents the average particle diameter of the particles present in the polishing composition and R2 represents the average particle diameter of the abrasive grains when the abrasive grains are dispersed in water at the same concentration as that of the abrasive grains in the polishing composition. The polishing composition can be used mainly for polishing the surface of a silicon substrate.