Polishing Composition with Modified Abrasive Grains
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Solution Overview
Problem
Conventional polishing compositions for semiconductor wafers face challenges in reducing surface contamination and abrasive grain aggregation, leading to defects such as light point defects and metal contamination, due to the use of hydroxyethyl cellulose and unmodified abrasive grains.
Innovation Solution
A polishing composition containing a polyvinyl alcohol resin with a 1,2-diol structure, an organic acid acting as a chelating agent, and abrasive grains with a minus zeta potential, which suppresses abrasive grain aggregation and metal adhesion, thereby reducing surface contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If hydroxyethyl cellulose is used as a hydrophilic polymer in the polishing composition, then the removal of foreign matter from the wafer surface is facilitated, but abrasive grains aggregate due to the large molecular weight and molecular structure of hydroxyethyl cellulose
Solution Approach 1:
The patent extracts the problematic hydroxyethyl cellulose from the polishing composition and replaces it with a different hydrophilic polymer that does not cause abrasive grain aggregation, thereby eliminating the harmful side effect while preserving the beneficial foreign matter removal capability
Solution Approach 2:
The patent changes the molecular weight parameter of the hydrophilic polymer from large (hydroxyethyl cellulose) to small (the polymer in the patent), which fundamentally alters the interaction between the polymer and abrasive grains, preventing aggregation while maintaining hydrophilic properties for effective foreign matter removal
2Ease of manufacture
If a coarse filter is used to filter the polishing composition containing hydroxyethyl cellulose, then the filtering process is simpler, but fine aggregate particles cannot be removed
Solution Approach 1:
The patent removes the cause of aggregation (hydroxyethyl cellulose) from the system, thereby eliminating the formation of fine aggregate particles that would require complex filtration, allowing standard filtration to effectively remove all particles
Solution Approach 2:
By completely preventing aggregation through the use of a small molecular weight hydrophilic polymer, the patent ensures that even standard filtration can remove all aggregate particles, providing excessive action in particle removal capability
3Device complexity
If conventional polishing compositions are used, then the polishing process is simple, but metal contamination adheres to the wafer surface causing pits
Solution Approach 1:
The patent introduces a specific hydrophilic polymer as an intermediary substance that interacts with metal ions in the polishing composition, preventing their adhesion to the wafer surface and thereby eliminating metal contamination without complicating the overall composition
Solution Approach 2:
The patent converts the potential harm of metal ions present in the polishing composition into a beneficial effect by using the hydrophilic polymer to sequester or interact with metal ions, preventing them from causing contamination and turning a harmful factor into a controlled element
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 effectively prevents abrasive grain aggregation and metal adhesion, resulting in reduced surface defects and contamination on the wafer, enhancing the polishing process by maintaining a low polishing rate and wettability while ensuring efficient removal of residual particles.
Implementation Method 1
a polyvinyl alcohol resin having a 1,2-diol structure in its side chain... a hydrophilic water soluble polymer that is hydrophilic with respect to the surface of the wafer
Implementation Method 2
a polyvinyl alcohol resin... being a copolymer of a monomer represented by Formula (1) below and a vinyl ester monomer
Implementation Method 3
an organic acid... an aminocarboxylic acid chelating agent and a phosphonic acid chelating agent
Implementation Method 4
abrasive grains whose surfaces are chemically modified so as to have a minus zeta potential on the surfaces in a solution with a pH of 2.0 or more and to have no isoelectric point
Implementation Method 5
polishing is performed generally using a polishing composition containing abrasive grains
Data Source
AI summary
A polishing composition of the present invention contains: a polyvinyl alcohol resin having a 1,2-diol structure in its side chain, the polyvinyl alcohol resin being a copolymer of a monomer represented by Formula (1) below and a vinyl ester monomer; an organic acid; and abrasive grains whose surfaces are chemically modified so as to have a minus zeta potential on the surfaces in a solution with a pH of 2.0 or more and to have no isoelectric point:(where R1 to R6 each independently denote a hydrogen atom or an organic group, X denotes a single bond or a linking group, and R7 and R8 each independently denote a hydrogen atom or R9—CO— (where R9 denotes an alkyl group)).