CMP Retaining Ring Wear Monitoring via Acoustic Sensor
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes face challenges in efficiently monitoring the wear status and break-in time of retaining rings, leading to increased downtime and non-uniform polishing due to uneven wear and potential grooving on the inner surface, which affects polishing uniformity and efficiency.
Innovation Solution
Incorporating an acoustic sensor system that monitors the retaining ring in real-time during CMP, allowing for the determination of break-in status and wear geometry, enabling adjustments to polishing parameters and timely replacement of the retaining ring to maintain uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional periodic replacement of retaining ring is used, then downtime is reduced, but polishing uniformity deteriorates due to uneven wear and grooving
Solution Approach 1:
The acoustic sensor provides real-time feedback on the retaining ring's condition by detecting acoustic emissions during polishing. The controller monitors these signals to determine wear status and break-in completion, enabling dynamic adjustment of polishing parameters or timely replacement of the retaining ring before it causes non-uniform polishing, thus resolving the contradiction between minimizing downtime and maintaining polishing uniformity.
2Device complexity
If retaining ring is monitored without acoustic sensing, then device complexity is low, but wear status detection precision is insufficient leading to non-uniform polishing
Solution Approach 1:
The patent replaces complex mechanical measurement systems with an acoustic sensing system. The acoustic sensor detects wear status and break-in conditions through acoustic emissions during polishing, providing precise real-time monitoring with simpler device architecture. This substitution achieves high measurement precision for wear status while maintaining relatively low device complexity.
3Manufacturing precision
If real-time acoustic monitoring is implemented, then polishing uniformity is improved through timely detection, but device complexity increases due to additional sensors and controllers
Solution Approach 1:
The retaining ring essentially monitors itself through acoustic emissions generated during its own operation. The acoustic sensor captures these self-generated signals, and the controller processes them to determine wear status and break-in completion. This self-service approach provides precise polishing uniformity control while adding minimal system complexity, as the monitored object itself provides the monitoring signal.
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 reduces the time required for break-in and prevents non-uniform polishing by providing real-time monitoring of retaining ring wear and grooving, improving wafer-to-wafer and within-wafer polishing uniformity and reducing the likelihood of downtime.
Implementation Method 1
acoustic sensor travels in a path below the carrier head and the retaining ring... analyze a signal from the acoustic sensor and determine a characteristic of the retaining ring
Data Source
AI summary
A chemical mechanical polishing apparatus includes a platen supporting a polishing pad, a carrier head to hold a surface of a substrate against the polishing pad, an acoustic sensor supported on the platen, and a motor to generate relative motion between the platen and the carrier head so as to polish the substrate. The carrier head includes a retaining ring for holding the substrate, and the acoustic sensor travels in a path below the carrier head and the retaining ring. A controller is configured to analyze a signal from the acoustic sensor and determine a characteristic of the retaining ring based on the signal.