Polishing Agent Selectivity for Shallow Trench Isolation
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Solution Overview
Problem
In the CMP step for semiconductor element production, particularly for shallow trench isolation, there is a need to enhance the polishing selectivity of insulating materials to stopper materials without relying on convex pattern density, as conventional polishing agents often result in excessive polishing of stopper materials in regions with low convex pattern density, leading to uneven stopper thickness and device performance issues.
Innovation Solution
A polishing agent comprising a liquid medium, hydroxide of a tetravalent metal element, a polymer compound with an aromatic ring and a polyoxyalkylene chain, and a cationic polymer, where the weight average molecular weight of the polymer compound is 1000 or more, is used to improve polishing selectivity and suppress stopper material polishing rates independently of convex pattern density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional polishing agent is used, then the polishing rate of insulating material is improved, but the polishing selectivity of insulating material to stopper material deteriorates due to excessive polishing of stopper material in regions with low convex pattern density
Solution Approach 1:
The invention changes the chemical composition parameters of the polishing agent by incorporating specific polymers (polyvinyl alcohol with 95-99 mol% degree of saponification and polyethylene glycol with specific molecular weight range) to modify the interaction between polishing particles and stopper material, thereby reducing the polishing rate of stopper material while maintaining the polishing rate of insulating material
Solution Approach 2:
The invention uses a composite polishing agent system combining multiple components: abrasive particles, polyvinyl alcohol polymer, polyethylene glycol polymer, and other additives in specific concentration ranges to achieve synergistic effects that improve polishing selectivity through the combined action of these materials
2Manufacturing precision
If the polishing rate of stopper material is increased to improve flatness, then the polishing selectivity deteriorates, but if the polishing rate is decreased to improve selectivity, then the flatness and productivity are worsened
Solution Approach 1:
The invention optimizes multiple parameters simultaneously: the degree of saponification of polyvinyl alcohol (95-99 mol%), the molecular weight of polyethylene glycol (1000-10000), and their respective concentrations to achieve a balance where the polishing selectivity is improved while maintaining adequate polishing rate and flatness
3Manufacturing precision
If fine polishing scratches are generated by conventional polishing agents, then the surface quality is improved for conventional wiring widths, but the scratches become problematic when further miniaturization of wiring is achieved
Solution Approach 1:
The invention changes the particle size distribution parameters of the abrasive grains and the chemical composition parameters of the polymer additives to reduce the severity and density of polishing scratches, making the surface quality suitable for further miniaturization of wiring where even fine scratches become problematic
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 enhances the polishing selectivity of insulating materials to stopper materials, reduces polishing scratches, and maintains uniform stopper thickness across varying convex pattern densities, thereby improving the flatness and performance of semiconductor devices.
Implementation Method 1
A polishing agent comprising a liquid medium, hydroxide of a tetravalent metal element
Implementation Method 2
a polymer compound having an aromatic ring and a polyoxyalkylene chain, and a cationic polymer
Data Source
AI summary
A polishing agent according to one embodiment of the present invention contains a liquid medium, an abrasive grain including a hydroxide of a tetravalent metal element, a polymer compound having an aromatic ring and a polyoxyalkylene chain, and a cationic polymer, wherein a weight average molecular weight of the polymer compound is 1000 or more.