CMP Polishing Pad Micro-Recess Structure for Higher Removal Rate
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Solution Overview
Problem
The increasing frequency of Chemical Mechanical Polishing (CMP) processes in semiconductor fabrication, particularly for three-dimensional structures, requires a method to enhance polishing efficiency.
Innovation Solution
A polishing pad with a surface featuring small, high-density recess portions (pores) that are 20 μm or less in width and 1,300/mm² or more in density, made of polyurethane foam, which improves slurry distribution and retention, thereby increasing the polishing rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frequency of CMP process is increased for three-dimensional structures, then the polishing efficiency is improved, but the polishing quality and substrate integrity may deteriorate due to excessive polishing pressure and heat
Solution Approach 1:
The polishing pad incorporates a porous layer with controlled pore size (20 μm or less) and high density (1,300/mm² or more) that allows slurry to penetrate and be retained within the pad structure. This porous structure distributes polishing pressure more evenly across the substrate surface, preventing localized overheating and excessive pressure that could damage three-dimensional structures, while maintaining high polishing efficiency through increased process frequency
Solution Approach 2:
The polishing pad features non-uniform pore distribution with different pore densities in different regions - higher density near the surface for slurry retention and deeper pores for slurry supply. This local variation in pore quality optimizes both slurry distribution and pressure management, enabling efficient polishing of three-dimensional structures without compromising substrate integrity
2Quantity of substance
If the pore width is reduced to 20 μm or less and density increased to 1,300/mm² or more, then the slurry retention and distribution are improved, but the manufacturing complexity of the polishing pad increases
Solution Approach 1:
The polishing pad is constructed with a porous layer formed by controlled foaming or phase separation of polyurethane, creating the required pore structure (20 μm width, 1,300/mm² density) through material selection and processing parameters rather than complex post-manufacturing steps. This approach achieves high slurry retention while maintaining relative manufacturing simplicity
Solution Approach 2:
The polishing pad uses a composite structure combining a porous polyurethane layer with specific pore characteristics and a supporting base layer. This composite design achieves the complex pore geometry requirements through material properties and layer integration rather than intricate manufacturing processes, balancing slurry retention performance with ease of manufacture
3Productivity
If the polishing rate is increased for efficient CMP processing, then the productivity is improved, but the risk of scratches and surface defects increases
Solution Approach 1:
The porous layer with high pore density (1,300/mm² or more) and small pore size (20 μm or less) acts as a buffer that distributes polishing pressure uniformly across the substrate surface. This pressure distribution enables higher polishing rates through increased process frequency while preventing localized stress concentrations that could cause scratches, thus improving productivity without increasing defect risk
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 polishing pad achieves improved removal rates and enhanced wettability, leading to efficient polishing of substrates with increased efficiency and reduced risk of scratches, while maintaining suitable hardness and elastic modulus for effective CMP processes.
Implementation Method 1
a polishing pad includes a surface having plural recess portions, and a substrate is polished by the surface. In the pad, an average width of the recess portions at one area of the surface in a direction parallel to the surface is 20 μm or less, and an average density of the recess portions at one area of the surface is 1,300/mm2 or more
Data Source
AI summary
A polishing pad is described. The polishing pad includes a surface having plural recess portions, and a substrate is polished by the surface. In the pad, an average width of the recess portions at one area of the surface in a direction parallel to the surface is 20 μm or less, and an average density of the recess portions at one area of the surface is 1,300/mm2 or more.