CMP Slurry Selectivity via Comb Polymer Adsorption
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Solution Overview
Problem
Current CMP processes lack effective polishing selectivity, particularly in achieving a low polishing rate for single-crystalline silicon or polysilicon layers while maintaining a high polishing rate for silicon oxide layers, which is crucial for high-density integration and performance in semiconductor devices.
Innovation Solution
A CMP slurry composition comprising abrasive particles, a dispersant, an ionic polymer additive with a comb-type copolymer structure, and a non-ionic polyolefin-polyethylene glycol copolymer, which provides a low polishing rate for single-crystalline silicon or polysilicon layers and a high polishing rate for silicon oxide layers, achieving excellent selectivity through controlled dispersion and surface interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP slurry compositions are used, then the polishing rate to silicon oxide layer is high, but the polishing rate to single-crystalline silicon or polysilicon layer is also high, resulting in poor polishing selectivity
Solution Approach 1:
The patent changes the chemical composition parameters of the CMP slurry by introducing specific polymers (polyacrylic acid with specific molecular weight range, and polyethylene glycol with specific molecular weight range) to alter the interaction between slurry and different material layers, achieving differential polishing rates
Solution Approach 2:
The patent uses a composite slurry system combining multiple components (abrasives, oxidants, complexing agents, and specifically formulated polymer additives) that work synergistically to achieve selective polishing - the polymers adsorb preferentially on silicon layers to reduce polishing rate while allowing high polishing rate on silicon oxide
2Manufacturing precision
If the polishing rate to polishing stop layer is reduced to improve selectivity, then the polishing rate to silicon oxide layer may also be reduced, affecting productivity
Solution Approach 1:
The patent applies different functional properties to different components of the slurry system - the polyacrylic acid provides protection to silicon layers through adsorption, while the polyethylene glycol enhances oxidation and polishing of silicon oxide, creating localized chemical effects that achieve high selectivity without sacrificing overall polishing efficiency
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 CMP slurry composition demonstrates a polishing selectivity ratio of 1:35 or more for polysilicon to silicon oxide layers, ensuring uniform planarization and minimizing dishing or erosion, thereby enhancing the performance and reliability of semiconductor devices.
Implementation Method 1
an ionic polymer additive
Implementation Method 2
The CMP process is to polish the wafer mechanically with abrasive particles
Implementation Method 3
The CMP process is to polish the wafer mechanically with abrasive particles
Implementation Method 4
The CMP process is to polish chemically with the chemicals in the slurry composition
Data Source
AI summary
The present invention relates to a CMP slurry composition comprising an abrasive particle; a dispersant; an ionic polymer additive; and a non-ionic polymer additive including a polyolefin-polyethylene glycol copolymer including at least two polyethylene glycol repeat unit as a backbone and at least a polyethylene glycol repeating unit as a side chain, and a polishing method with using the slurry composition. The CMP slurry composition shows a low polishing rate to a single-crystalline silicon layer or a polysilicon layer and a high polishing rate to a silicon oxide layer, resulting in having an excellent polishing selectivity.