CMP Polishing Liquid Suppresses Dishing via Protective Layer
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Solution Overview
Problem
In the CMP technique for semiconductor element manufacturing, excessive dishing occurs during the polishing process due to the difficulty in controlling the polishing rate of insulating materials, leading to poor flatness of the base substrate, despite the use of polishing liquids with high selectivity towards stopper materials.
Innovation Solution
A polishing liquid containing abrasive grains, hydroxy acid components, and a compound Z with a hydrocarbon group and polyoxyalkylene group, where the Z value is 20 or more, is used to suppress excessive dishing by forming a protective layer on the insulating material, thereby controlling the polishing rate and preventing over-polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing is performed until the stopper is exposed to control the polishing amount, then the polishing amount of the insulating material is controlled, but excessive dishing occurs due to over-polishing
Solution Approach 1:
The patent introduces a protective layer as an intermediary between the insulating material and the polishing liquid. This protective layer mediates the polishing action, allowing the stopper to be exposed for polishing control while preventing excessive polishing of the insulating material that causes dishing. The protective layer is formed by specific compounds (polymer or surfactant) that adsorb onto the insulating material surface.
Solution Approach 2:
The patent changes the chemical and physical parameters of the polishing liquid by adding specific compounds (polymer with molecular weight 10,000-1,000,000 or surfactant with HLB value 8-18) to control the polishing rate. This parameter change creates a protective layer that moderates the polishing action, suppressing excessive dishing while maintaining polishing control.
2Manufacturing precision
If polishing liquid with high selectivity towards stopper material is used, then polishing selectivity of insulating material with respect to stopper is improved, but excessive dishing still occurs
Solution Approach 1:
The patent creates a composite polishing liquid system by combining high-selectivity polishing liquid with additional compounds (polymer or surfactant). This composite formulation maintains the high polishing selectivity towards the stopper material while the added compounds form a protective layer on the insulating material, preventing excessive dishing during over-polishing.
Solution Approach 2:
The patent applies different properties to different areas: the polishing liquid maintains high selectivity for the stopper material (local high reactivity), while the protective layer provides protection specifically to the insulating material areas (local protection). This local differentiation allows selective polishing control without excessive dishing.
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 effectively suppresses excessive dishing and improves the flatness of the base substrate by moderating the polishing rate, allowing for precise control during the polishing process, especially when using silicon oxide and silicon nitride materials.
Implementation Method 1
the compound Z has a hydrocarbon group which may be substituted and a polyoxyalkylene group
Implementation Method 2
at least one hydroxy acid component selected from the group consisting of a hydroxy acid and a salt thereof
Data Source
AI summary
A polishing liquid containing: abrasive grains; at least one hydroxy acid component selected from the group consisting of a hydroxy acid and a salt thereof; and a compound Z, in which the compound Z has a hydrocarbon group which may be substituted and a polyoxyalkylene group, and a Z value represented by General Formula (1) below is 20 or more:Z=0.1×a2×b/c (1)[in Formula (1), “a” represents the number of carbon atoms of the hydrocarbon group, “b” represents the total number of oxyalkylene groups in the compound Z, and “c” represents an HLB value of the compound Z.]