Polishing Member Height Detection for Cutting Rate Correction
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Solution Overview
Problem
In chemical mechanical polishing (CMP) processes, maintaining consistent polishing rates is challenging due to variations in the surface height of polishing members, which can be affected by moisture absorption and swelling, leading to inappropriate undulations and polishing failures.
Innovation Solution
A substrate polishing device equipped with a height detection unit to measure the surface height of the polishing member and a cutting rate calculation unit that corrects the cutting rate based on past calculations when it falls outside a predetermined range, ensuring optimal dressing conditions and maintaining consistent polishing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the polishing member absorbs moisture and swells with the elapse of time, then the apparent height of the polishing member increases, but it becomes impossible to appropriately calculate the cutting rate of the polishing member
Solution Approach 1:
The system performs preliminary measurement of the polishing member's surface height using a height detection unit before calculating the cutting rate. By measuring the actual height at the time of operation and using this value in the cutting rate calculation, the system compensates for swelling effects in advance, ensuring accurate calculation despite changes in the polishing member's dimensions over time.
2Manufacturing precision
If dressing is not appropriately performed, then an inappropriate undulation occurs on the surface of the polishing member, but performing dressing under inappropriate conditions also causes variations in the cutting rate
Solution Approach 1:
The system uses a height detection unit to continuously monitor the surface height of the polishing member and feeds this information back to the control unit. The control unit adjusts the dresser rotation speed and moving speed based on the detected height and calculated cutting rate, creating a closed-loop control system that automatically maintains appropriate dressing conditions without requiring complex manual intervention.
Solution Approach 2:
The system enables the polishing device to automatically adjust its own dressing parameters based on real-time measurements. The control unit autonomously determines the appropriate dresser rotation speed and moving speed by calculating the cutting rate from the detected surface height, allowing the system to self-regulate and maintain optimal dressing conditions without external intervention.
3Reliability
If the rotation speed of the polishing member, rotation speed of the dresser, dressing load, or moving speed of the dresser is not appropriately controlled, then variations in the cutting rate occur, but strict control of all these parameters increases system complexity
Solution Approach 1:
The system dynamically changes the dresser rotation speed and moving speed parameters based on the detected surface height of the polishing member. By calculating the cutting rate from the actual height measurement and adjusting these parameters accordingly, the system maintains consistent cutting rates without requiring strict control of all dressing parameters simultaneously, thereby reducing system complexity while ensuring reliability.
Data Source
AI summary
A substrate polishing device includes a height detection unit configured to measure a surface height of a polishing member, and a cutting rate calculation unit configured to calculate a cutting rate of the polishing member based on the surface height. The cutting rate calculation unit corrects the current cutting rate based on the cutting rate calculated in the past when the calculated current cutting rate falls outside a search range.