Polishing Pad with Transparent Window and Grooved Subpad
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) methods face challenges in achieving high polishing rates and maintaining substrate surface flatness and finish, particularly due to limitations in polishing pad materials and slurry distribution, which affect the efficiency and effectiveness of the process.
Innovation Solution
A linear polishing sheet with a transparent portion made from a flexible polyurethane material and a grooved subpad with a spiral groove pattern are used, allowing for the development of groove patterns in the polishing surface while advancing in small increments, and incorporating a dovetail-like joint for increased mechanical strength and optical monitoring capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a standard polishing pad is used, then the polishing process is simple, but the polishing rate and surface finish quality are insufficient
Solution Approach 1:
The polishing pad is divided into multiple layers including a top layer, bottom layer, and intermediate layer with different material properties. Each layer serves specific functions: the top layer provides polishing action, the intermediate layer with grooves facilitates slurry distribution, and the bottom layer provides structural support. This segmentation enables high polishing rate while maintaining manageable structural complexity.
Solution Approach 2:
The polishing pad uses composite materials with different properties in each layer. The top layer uses polishing-specific material, the intermediate layer uses material with groove-forming capability, and the bottom layer uses structurally robust material. This composite structure achieves superior polishing performance without excessive complexity.
2Productivity
If a fixed-abrasive pad is used, then material removal is efficient, but surface finish quality deteriorates
Solution Approach 1:
The polishing process is segmented into multiple stages using different pad layers. The top layer performs aggressive material removal for high productivity, while subsequent layers or conditioning passes provide finer finishing. This multi-stage approach through segmentation achieves both high material removal rate and excellent surface finish quality.
3Productivity
If slurry distribution is poor, then polishing efficiency decreases, but improving slurry distribution increases device complexity
Solution Approach 1:
The intermediate layer of the polishing pad incorporates grooves at specific locations and orientations to optimize slurry distribution locally where needed. These grooves channel slurry flow to areas of high polishing demand while maintaining simple overall device structure. This local quality enhancement improves polishing efficiency without significantly increasing device complexity.
4Adaptability or versatility
If the polishing pad material is not flexible enough, then it cannot conform to substrate curvature, but increasing flexibility reduces mechanical strength
Solution Approach 1:
The multi-layer composite structure provides optimal balance between flexibility and strength. The top layer uses softer, more flexible material for substrate conformability, the intermediate layer provides structural reinforcement, and the bottom layer offers robust mechanical support. This composite material approach achieves both adaptability to substrate curvature and sufficient mechanical strength.
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 enables efficient slurry transport and retention on the platen, improves polishing performance by maintaining high polishing rates and surface quality, and facilitates substrate dechuck after polishing, reducing material complexity and enhancing mechanical strength at the interface.
Implementation Method 1
a vacuum source connected to the groove of the subpad and configured to apply a vacuum sufficient to pull portions of the polishing sheet into the groove of the subpad
Implementation Method 2
a linear polishing sheet having a linear transparent portion... facilitating substrate dechuck after polishing, reducing material complexity and enhancing mechanical strength at the interface
Implementation Method 3
A polishing slurry, including at least one chemically-reactive agent, and abrasive particles if a standard pad is used, is supplied to the surface of the polishing pad
Implementation Method 4
The polishing pad may be either a standard pad or a fixed-abrasive pad... if a standard pad is used, is supplied to the surface of the polishing pad
Data Source
AI summary
A polishing article includes a polishing layer having a polishing surface and a solid light-transmissive window in the polishing layer, the window having a first non-linear edge that extends along a first axis parallel to the polishing surface, the first non-linear edge including a plurality of projections and a plurality of recesses extending parallel to the polishing surface and disposed in an alternating pattern along the first axis.