Cerium Oxide Polishing Agent for High Selectivity CMP
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Solution Overview
Problem
Conventional polishing agents for chemical mechanical polishing (CMP) in semiconductor manufacturing fail to achieve a high selection ratio between silicon dioxide and silicon nitride films, leading to insufficient flatness and removal rate imbalances.
Innovation Solution
A polishing agent comprising cerium oxide particles, a water-soluble polyamine, potassium hydroxide, and an organic acid or its salt, with a pH of 10 or more, which optimizes the removal rate of silicon oxide films while suppressing the removal rate of silicon nitride films, thereby achieving a high selection ratio and improved flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing agents are used to achieve high removal rate of silicon dioxide film, then productivity is improved, but the selection ratio between silicon dioxide film and silicon nitride film is insufficient
Solution Approach 1:
The polishing agent uses pH as a critical parameter, maintaining a pH of 9 or higher (preferably 10-13) to achieve high removal rate of silicon dioxide film while suppressing removal of silicon nitride film. This parameter change enables the polishing agent to selectively remove oxide films without significantly removing nitride films, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The polishing agent employs a composite formulation combining cerium oxide particles (abrasive component) with specific organic additives including polyamines, carboxylic acids, and their complexes. This composite material approach creates synergistic effects where the cerium oxide provides mechanical abrasion for high removal rate, while the organic additives chemically modify the surfaces to enhance selectivity, simultaneously achieving high productivity and manufacturing precision.
2Productivity
If conventional polishing agents are used to increase removal rate of silicon dioxide film, then cost efficiency is improved, but flatness of polishing is insufficient
Solution Approach 1:
By controlling the pH parameter at 9 or higher, the polishing agent achieves uniform chemical-mechanical removal across the wafer surface. The alkaline environment promotes consistent softening of the silicon dioxide film, enabling uniform removal rates that produce excellent flatness while maintaining high productivity.
Solution Approach 2:
The composite formulation of cerium oxide particles with polyamines and carboxylic acids creates a polishing slurry that combines mechanical abrasion with chemical softening. This composite action ensures uniform material removal across the wafer surface, achieving both high removal rate and excellent flatness simultaneously.
3Productivity
If polishing agent contains cerium oxide particles and amine or carboxylic acid, then removal rate of silicon dioxide film is improved, but removal rate of silicon nitride film is not sufficiently suppressed
Solution Approach 1:
The polishing agent uses a composite system where cerium oxide particles provide mechanical abrasion for high removal rate, while polyamines and carboxylic acids (or their complexes) provide chemical selectivity. The organic additives preferentially interact with silicon dioxide through complexation and softening effects, while having minimal impact on silicon nitride, thereby achieving high selection ratio alongside high productivity.
Solution Approach 2:
The pH parameter is critical in achieving selectivity. By maintaining pH at 9 or higher, the polishing agent creates an alkaline environment where carboxylic acids and polyamines effectively complex with silicon dioxide, enhancing its removal rate, while silicon nitride remains relatively inert under these conditions, thus achieving high selection ratio.
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 proposed solution maintains a high removal rate for silicon oxide films while keeping a low removal rate for silicon nitride films, resulting in enhanced polishing flatness and a high selection ratio, suitable for semiconductor device manufacturing.
Implementation Method 1
chemical mechanical polishing (hereinafter referred to as "CMP")
Implementation Method 2
cerium oxide particles as abrasives
Implementation Method 3
suppression of a removal rate of a silicon nitride film is not sufficient
Data Source
AI summary
The present invention relates to a polishing agent including: cerium oxide particles; a water-soluble polyamine; potassium hydroxide; at least one selected from an organic acid and a salt thereof; and water, in which the polishing agent has a pH of 10 or more, a polishing method using the polishing agent, and a method for manufacturing a semiconductor integrated circuit device.