CMP Polishing Fluid with Silica-Cerium Hydroxide Composite Particles
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Solution Overview
Problem
Conventional CMP polishing liquids face limitations in achieving a high enough polishing rate for insulating films, particularly for silicon oxide films, despite the addition of various additives.
Innovation Solution
A CMP polishing liquid containing composite particles with a core of silica and a shell of cerium hydroxide, where the pH is maintained at or below 9.5, enhancing the polishing rate and reducing scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional silica-based CMP polishing liquid is used, then versatility for polishing various films is maintained, but polishing rate for insulating films is insufficient
Solution Approach 1:
The invention uses composite particles comprising a silica core and a cerium hydroxide shell, combining the mechanical polishing capability of silica with the chemical reactivity of cerium hydroxide. This composite structure achieves high polishing rates for insulating films while maintaining controlled scratching, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The invention changes the chemical composition parameters by introducing cerium hydroxide as the shell material and controlling pH at 9.5 or lower. This parameter change enables the polishing liquid to achieve high polishing rates for insulating films while maintaining film quality, addressing both productivity and reliability requirements.
2Productivity
If cerium oxide particles are used as abrasive, then polishing rate for silicon oxide films increases, but mechanical scratching increases
Solution Approach 1:
The invention changes the chemical form of cerium from oxide to hydroxide in the shell structure, and controls pH at 9.5 or lower. This parameter change reduces mechanical scratching while maintaining high polishing rates, as the hydroxide form at controlled pH provides chemical reactivity without excessive mechanical abrasion.
Solution Approach 2:
The invention applies different materials with different properties to different parts of the abrasive particle: silica core for mechanical polishing and cerium hydroxide shell for chemical reactivity. This local differentiation allows high polishing rate from the chemically reactive shell while the core provides structural stability, reducing scratches.
3Manufacturing precision
If tetravalent metal element hydroxide particles are used, then chemical action increases and mechanical action decreases, but polishing rate is insufficient
Solution Approach 1:
The invention creates a composite particle with silica core and cerium hydroxide shell, combining mechanical polishing capability from silica with chemical reactivity from cerium hydroxide. This composite structure achieves both high surface quality through controlled mechanical action and high polishing rate through enhanced chemical reactivity.
Solution Approach 2:
The invention merges the mechanical polishing function of silica particles with the chemical reactivity of tetravalent metal element hydroxide particles into a single composite abrasive particle. This merging enables simultaneous achievement of high surface quality and high polishing rate that neither component could achieve alone.
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 solution significantly increases the polishing rate for insulating films, such as silicon oxide films, while minimizing scratches, outperforming conventional liquids using silica or cerium oxide particles alone or their simple mixtures.
Implementation Method 1
This technique takes advantage of a chemical action of the tetravalent metal element hydroxide particles
Implementation Method 2
a chemical mechanical polishing (CMP) technique is an essential technique
Data Source
AI summary
A CMP polishing liquid comprises water and an abrasive particle, wherein the abrasive particle comprises a composite particle having a core including a first particle, and a second particle provided on the core, the first particle contains silica, the second particle contains cerium hydroxide, and the pH of the CMP polishing liquid is equal to or lower than 9.5.