CMP Slurry Composition for High STI Oxide-to-Polysilicon Selectivity
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) solutions face challenges in achieving high selectivity ratios for polishing silicon dioxide/polycrystalline silicon stop layers, which is crucial for the shallow trench isolation (STI) process.
Innovation Solution
A CMP solution comprising cerium oxide particles, an anionic compound, a cationic compound, an inhibitor, and a pH regulator, where the inhibitor is a nonionic polymer compound, effectively controls the selectivity ratio of the insulation film to the polycrystalline silicon stop layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP solutions are used, then polishing can be performed, but the selectivity ratio for silicon dioxide/polycrystalline silicon is insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP solution by incorporating specific anionic compounds (such as ammonium polyacrylate, polyaspartic acid) and cationic compounds (such as polyquaternium-7, polyquaternium-37) in optimized concentrations. These parameter changes enable the solution to achieve a selectivity ratio of over 100 for silicon dioxide/polycrystalline silicon, resolving the contradiction between manufacturing precision and process reliability.
Solution Approach 2:
The patent creates a composite CMP solution formulation that combines cerium oxide particles with multiple chemical compounds including anionic polymers, cationic polymers, and inhibitors. This composite material approach allows the solution to simultaneously achieve high selectivity ratio and reliable polishing performance, as the different components work synergistically to control the polishing characteristics.
2Manufacturing precision
If high selectivity ratio is achieved, then insulation film polishing is improved, but polycrystalline silicon stop layer may be damaged
Solution Approach 1:
The patent introduces inhibitor compounds as intermediary substances that mediate between the polishing action and the polycrystalline silicon stop layer. These inhibitors form protective complexes that prevent direct harmful interaction between the abrasive particles and the stop layer, allowing high selectivity ratio to be achieved without damaging the polycrystalline silicon.
Solution Approach 2:
The patent optimizes the concentration parameters of anionic and cationic compounds to create a balanced chemical environment that enhances insulation film removal while inherently protecting the stop layer. The specific parameter ranges disclosed ensure that the polishing process achieves planarization efficiency without causing stop layer damage.
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 achieves a selectivity ratio of over 100 for polishing the insulating film phase/polycrystalline silicon, improving planarization efficiency and protecting the polycrystalline silicon stop layer, ensuring the smooth implementation of the STI process.
Implementation Method 1
chemical mechanical polishing has become an essential technique for forming shallow trench isolation and for planarizing metal pre-insulating materials or interlayer insulating materials
Implementation Method 2
the specified anionic compounds, cationic compounds, and inhibitors in this application can effectively control the selectivity ratio of the insulation film to the polycrystalline silicon stop layer
Implementation Method 3
the inhibitor is a nonionic polymer compound
Data Source
AI summary
The present disclosure provides a chemical mechanical polishing solution comprising cerium oxide particles, an anionic compound, a cationic compound, an inhibitor, and a pH regulator, wherein the inhibitor is a non-ionic polymeric compound; The polishing selectivity ratio of the chemical mechanical polishing solution for the insulation film/polycrystalline silicon is greater than 100. The chemical mechanical polishing solution of the present invention can effectively maintain a high polishing selectivity ratio of the insulation layer to the stop layer, where the stop layer is a polycrystalline silicon stop layer.