Dual-Density Polishing Pad for CMP Edge Uniformity
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Solution Overview
Problem
Existing polishing pads do not provide a high polishing rate and uniformity, particularly at the edge regions of semiconductor substrates, during chemical mechanical planarization processes.
Innovation Solution
A polishing pad comprising a top pad with distinct regions of differing densities, specifically a first region and a second region with a density difference of 0.03 g/cm3 or more, enhancing slurry inflow and diffusion for improved polishing uniformity and rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polishing pad with uniform density is used, then the manufacturing process is simple, but the polishing uniformity at edge regions is poor
Solution Approach 1:
The polishing pad is designed with a first region having a first density and a second region having a second density, where the densities differ by 0.03 g/cm³ or more. This local quality variation allows the pad to provide different polishing characteristics in different regions, specifically improving edge region polishing uniformity while maintaining overall polishing quality.
2Productivity
If a polishing pad with high density is used, then the polishing rate is high, but the slurry diffusion is insufficient
Solution Approach 1:
The polishing pad employs regions with different densities to balance polishing rate and slurry diffusion. The first region with higher density provides high polishing rate, while the second region with lower density facilitates slurry diffusion and supply, achieving both high productivity and adequate slurry flow.
3Quantity of substance
If a polishing pad with low density is used, then the slurry diffusion is good, but the polishing rate is low
Solution Approach 1:
The polishing pad strategically places low-density regions for slurry diffusion and high-density regions for polishing rate. The second region with lower density ensures adequate slurry supply, while the first region with higher density maintains high polishing rate, resolving the trade-off between slurry diffusion and productivity.
4Manufacturing precision
If the polishing pad structure is simplified, then the manufacturing cost is reduced, but the polishing quality control is insufficient
Solution Approach 1:
The polishing pad incorporates a multi-region density structure with a density difference of 0.03 g/cm³ or more between regions. This structured approach enables precise control of polishing quality across different areas of the substrate, achieving high manufacturing precision through a systematically designed but manufacturable structure.
Data Source
AI summary
According to embodiments of the present invention, there are provided a polishing pad, a process for preparing a polishing pad, and a process for preparing a semiconductor device using the polishing pad. The polishing pad comprises a sub pad and a top pad disposed on the sub pad and comprising a first region and a second region having different densities, wherein the difference between the density of the first region and the density of the second region is 0.03 g/cm3 or more. A high polishing rate can be provided in the central region of an object to be polished, and enhanced polishing flatness can be provided in the edge region of the object to be polished.