CMP Slurry for Silicon Oxide and Nitride Polishing
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Solution Overview
Problem
Conventional chemical-mechanical polishing (CMP) techniques fail to provide high removal rates and optimal surface topography for 3D flash memory devices, particularly for silicon oxide, silicon nitride, and polysilicon, with existing CMP compositions often resulting in low defect levels and significant dishing.
Innovation Solution
A CMP method and composition utilizing a particulate ceria abrasive suspended in an aqueous carrier with a pH of 3 to 9.5, containing a cationic polymer such as poly(2-methacryloyloxyethyltrimethyl ammonium chloride) and ammonium nitrate, which achieves high removal rates (>1000 Å/min) for silicon oxide, silicon nitride, and polysilicon, suitable for 3D flash memory applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions are used, then removal rate is achieved, but surface topography deteriorates with significant dishing
Solution Approach 1:
The patent changes the chemical composition parameters of the CMP slurry by incorporating specific organic acids (succinic acid, glutaric acid, or adipic acid) at controlled concentrations (0.01-5% by weight) and adjusting pH to specific ranges (3-9.5), which modifies the removal mechanism to achieve both high removal rates and minimal dishing
Solution Approach 2:
The patent uses composite abrasive systems combining cerium oxide particles (0.1-5% by weight) with specific organic acid additives, creating a composite slurry formulation that simultaneously provides mechanical abrasion for high removal rates and chemical control for superior surface topography
2Productivity
If conventional CMP compositions are used, then material removal is achieved, but defect levels increase
Solution Approach 1:
The patent optimizes pH parameters to specific ranges (3-9.5, preferably 4-8) and controls organic acid concentrations (0.01-5% by weight) to create optimal chemical conditions that enable high removal rates while minimizing defect generation through controlled chemical-mechanical interaction
Solution Approach 2:
The organic acids (succinic, glutaric, or adipic acid) act as intermediary substances that mediate between the abrasive particles and the material being polished, facilitating controlled material removal while reducing defect formation through their specific chemical properties
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 described method and composition achieve high removal rates for silicon oxide, silicon nitride, and polysilicon, ensuring low defect levels and minimal dishing, making them particularly effective for 3D flash memory manufacturing.
Implementation Method 1
The slurry of claim 1, wherein said particulate ceria abrasive comprises a cationic polymer adsorbed onto a surface thereof
Data Source
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AI summary
The present invention provides a chemical mechanical polishing method for polishing a substrate comprising silicon dioxide, silicon nitride, and polysilicon. The method comprises abrading a surface of the substrate with a CMP composition to remove at least some silicon dioxide, silicon nitride and polysilicon therefrom. The CMP composition comprising a particulate ceria abrasive suspended in an aqueous carrier having a pH of about 3 to 9.5 and containing a cationic polymer; wherein the cationic polymer consists of a quaternary methacryloyloxyalkylammonium polymer.