CMP Slurry for Polysilicon Dishing Reduction

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Solution Overview

Problem

Chemical mechanical polishing (CMP) slurries used for polycrystalline silicon surfaces often result in dishing, leading to within-wafer-non-uniformity and deteriorated electrical properties due to insufficient selectivity between polycrystalline silicon and insulating oxide films.

Innovation Solution

A CMP slurry composition comprising a metal oxide, a pH-adjusting agent, a fluorinated surfactant, and a quaternary ammonium surfactant, specifically formulated to improve polishing selectivity and within-wafer-non-uniformity, with the surfactants present in optimized weight ranges to control polishing rates and prevent dishing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional CMP slurry is used to achieve high polishing rate, then polishing efficiency is improved, but dishing occurs and within-wafer-non-uniformity deteriorates

Engineering Contradiction:

Improvepolishing rateVSAvoidwithin-wafer-non-uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent modifies the chemical composition parameters of the slurry by incorporating specific additives (amines, quaternary ammonium salts, polyhydric alcohols, inorganic salts) in optimized concentrations. These parameter changes alter the chemical mechanical interaction to achieve high polishing rates while controlling dishing and improving within-wafer-non-uniformity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The slurry is formulated as a composite system combining multiple components: abrasive particles (metal oxides), chemical additives (amines, quaternary ammonium salts), and polyhydric alcohols. This composite approach enables simultaneous achievement of high polishing rate and improved surface uniformity through synergistic chemical and mechanical actions

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If polishing selectivity between polycrystalline silicon and insulating oxide films is increased, then polishing precision is improved, but dishing of polycrystalline silicon films occurs

Engineering Contradiction:

Improvepolishing selectivityVSAvoiddishing

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The patent introduces intermediary substances (polyhydric alcohols and inorganic salts) that mediate between the abrasive particles and the polycrystalline silicon surface. These intermediaries modify the mechanical interaction to reduce excessive material removal from the center regions, thereby controlling dishing while maintaining polishing selectivity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The slurry composition parameters are optimized to achieve the right balance between chemical reactivity (for selectivity) and mechanical abrasion (to avoid dishing). Specific concentrations of additives are controlled to ensure high selectivity without excessive polishing rate that causes dishing

Inventive Principle:

Principle #35Parameter changes

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 slurry composition enhances polishing selectivity and reduces dishing, resulting in improved within-wafer-non-uniformity and maintaining effective polishing rates for polycrystalline silicon films relative to insulating oxide films.

Implementation Method 1

CMP compositions generally include a slurry, which is typically an abrasive solution

Methodology Applied

Scientific EffectAbrasion: Abrasion

Implementation Method 2

the slurry may chemically react with the surface of the wafer while the polishing pad physically removes portions of the surface of the wafer

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 3

a fluorinated surfactant and a quaternary ammonium surfactant, specifically formulated to improve polishing selectivity and within-wafer-non-uniformity

Methodology Applied

Scientific EffectSurfactant action: Surfactant

Implementation Method 4

an additive for controlling the polishing rate and selectivity

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentEP2092034B1Chemical mechanical polishing slurry compositions, methods of preparing the same and methods of using the same

Publication Date: 2012.02.29 CHEIL INDUSTRIES INC

AI summary

Provided herein are chemical mechanical polishing (CMP) slurries and methods for producing the same. Embodiments of the invention include CMP slurries that include (a) a metal oxide; (b) a pH-adjusting agent; (c) a fluorinated surfactant; and (d) a quaternary ammonium surfactant. In some embodiments, the fluorinated surfactant is a non-ionic perfluoroalkyl sulfonyl compound. Also provided herein are methods of polishing a polycrystalline silicon surface, including providing a slurry composition according to an embodiment of the invention to a polycrystalline silicon surface and performing a CMP process to polish the polycrystalline silicon surface.