Dummy Disk Stabilizes Polishing Table Height Measurement
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Solution Overview
Problem
The existing methods for measuring the height of the polishing table surface in CMP devices are prone to inaccuracies due to manual operation and instability caused by liquids, leading to variations in measurement results and difficulties in maintaining a stable pad profile for effective polishing.
Innovation Solution
A dummy disk with liquid discharge channels is used to contact the polishing table surface, allowing for accurate measurement of table surface heights and stabilization of the dresser's posture, enabling precise measurement of table and pad profiles despite the presence of liquids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manual measurement method is used to measure table surface heights, then measurement process is simple, but measurement precision and reliability deteriorate due to operator skill variations
Solution Approach 1:
The patent replaces manual mechanical measurement with an automated optical measurement system. A surface height measurement instrument uses light to non-contactly measure the heights of table surface at multiple measurement points, eliminating operator skill variations and achieving consistent, precise measurements automatically.
2Productivity
If liquid is supplied to the table surface during measurement, then measurement can be performed during normal operation, but measurement precision deteriorates due to liquid interference and dresser posture instability
Solution Approach 1:
The patent introduces a dummy disk as an intermediary between the liquid-covered table surface and the measurement system. The dummy disk contacts the liquid surface at multiple points, providing stable reference positions that are not affected by liquid interference, thereby enabling accurate measurements during normal operation with liquid supply.
3Adaptability or versatility
If dresser is moved on liquid-covered polishing surface, then pad profile management can be performed, but measurement reliability deteriorates due to dresser posture instability
Solution Approach 1:
The dummy disk serves as a stable intermediary that contacts the liquid surface without being affected by it. Unlike the dresser which becomes unstable on liquid, the dummy disk maintains consistent contact positions, providing reliable measurement data even when liquid is present on the polishing surface.
4Manufacturing precision
If multiple measurement points are used to create accurate table profile, then table profile accuracy improves, but device complexity increases due to need for automated measurement system
Solution Approach 1:
The dummy disk enables automated multi-point measurement by serving as a stable reference that contacts the table surface at multiple points simultaneously. This intermediary allows the optical measurement system to automatically capture height data at multiple locations without complex mechanical scanning mechanisms.
Data Source
AI summary
A method is provided and includes making a polishing table and a dummy disk rotate; bringing the dummy disk into contact with a table surface of the polishing table while a liquid is supplied to the table surface; measuring heights of the table surface at a plurality of measurement points while the dummy disk is moved on the table surface; and creating a table profile showing tilt of the table surface from measurement values of the heights of the table surface.