Eddy Current Polishing Pad Thickness Monitoring
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Solution Overview
Problem
Conventional substrate processing technologies face challenges in accurately measuring the thickness of polishing pads and controlling chemical mechanical polishing process parameters, leading to inefficient process timing and degraded polishing quality due to unpredictable wear rates and interference from liquid fluids.
Innovation Solution
A substrate processing apparatus equipped with a thickness measuring unit using eddy current sensors to monitor the relative movement of a disk holder with respect to a conditioner head, allowing for real-time measurement of polishing pad thickness and continuous thickness distribution, enabling precise control of polishing parameters such as pressing force, rotational speed, and conditioning time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polishing pad is used for extended period to improve productivity, then productivity increases, but polishing quality deteriorates due to unpredictable wear
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring polishing pad thickness using eddy current sensors and other detection devices. The system measures the actual thickness of the polishing pad in real-time during the polishing process, feeds this information back to the control system, and automatically adjusts polishing parameters or triggers pad replacement alerts. This closed-loop feedback ensures polishing quality is maintained while maximizing productivity by preventing premature pad replacement.
2Manufacturing precision
If polishing pad replacement is performed based on predetermined lifetime to ensure quality, then polishing quality is maintained, but productivity decreases due to unnecessary replacements
Solution Approach 1:
The patent replaces conventional mechanical thickness measurement methods with non-contact eddy current sensing technology. Eddy current sensors detect changes in electromagnetic fields caused by variations in polishing pad thickness, enabling precise measurement without physical contact. This substitution allows for accurate, real-time monitoring of pad wear, eliminating the need for conservative predetermined replacement schedules and enabling extensions of pad service life while maintaining quality standards.
3Measurement precision
If conventional thickness measurement methods are used to detect pad wear, then wear detection is possible, but measurement precision is insufficient due to liquid fluid interference
Solution Approach 1:
The patent introduces eddy current sensors as an intermediary measurement device that indirectly detects polishing pad thickness through electromagnetic field interactions. Instead of directly measuring the pad surface (which would be contaminated by slurry and liquid fluids), the eddy current sensors measure changes in electromagnetic impedance caused by variations in pad thickness from a distance. This intermediary approach effectively eliminates interference from liquid fluids while maintaining high measurement precision.
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
This solution enables accurate detection of polishing pad wear, improves process efficiency, maintains polishing quality, and determines the optimal replacement time for pads, ensuring consistent substrate polishing without interference from liquid fluids.
Implementation Method 1
a thickness measuring unit which receives information on the relative movement distance of the disk holder with respect to the conditioner head to a sensing unit
Data Source
AI summary
Provided is a substrate processing apparatus. The substrate processing apparatus comprises a polishing table; a polishing pad disposed on an upper surface of the polishing table; a conditioner including a conditioner head, a disk holder movably coupled to the conditioner head in a vertical direction, and a conditioning disk mounted to the disk holder and in contact with the polishing pad; and a thickness measuring unit of obtaining the thickness of the polishing pad from the relative moving distance of the disk holder with respect to the conditioner head, wherein the information of the relative moving distance is received from sensing unit.