CMP Pad Wear Diagnosis via Height and Motor Torque
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Solution Overview
Problem
Existing polishing apparatuses struggle to accurately determine the end of life for polishing pads and dressers in CMP processes, leading to frequent replacements and increased operational costs due to the variability in pad thickness and groove depths, as well as the wear of dressers, which affects polishing performance.
Innovation Solution
A polishing apparatus equipped with a pad-height measuring device and a diagnostic device that monitors the height of the polishing pad, torque, and current of the rotating motors to calculate wear and diagnose the condition of both the polishing pad and dresser, allowing for precise determination of their replacement times based on wear and performance metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polishing pad replacement is determined based on the number of substrates polished, then the polishing performance can be maintained, but the replacement frequency is too high and operating rate decreases
Solution Approach 1:
The patent replaces the mechanical counting method (based on substrate number) with a sensor-based measurement system that directly measures pad height and dresser wear. This substitution enables continuous monitoring of actual wear conditions, allowing optimization of replacement timing to balance performance maintenance with maximum operating efficiency.
Solution Approach 2:
The patent implements feedback through sensors that continuously measure pad height and dresser wear, providing real-time information about consumable condition. This feedback loop enables dynamic adjustment of replacement timing based on actual wear rates, preventing both premature replacement and performance degradation.
2Reliability
If polishing pad replacement is performed frequently to maintain performance, then polishing performance is maintained, but operational costs increase
Solution Approach 1:
The patent replaces subjective judgment and fixed schedules with objective sensor measurements of pad height and dresser wear. This substitution enables precise determination of actual consumable life, allowing extension of usage until performance thresholds are reached, thereby maximizing consumable utilization and reducing waste.
Solution Approach 2:
The measurement system enables the polishing apparatus to self-monitor its own consumable conditions, automatically tracking pad and dresser wear without external intervention. This self-service capability ensures optimal replacement timing is achieved consistently, minimizing both performance loss and unnecessary replacement costs.
3Adaptability or versatility
If individual polishing pads with different thicknesses and groove depths are used, then manufacturing flexibility is improved, but accurate determination of pad life becomes difficult
Solution Approach 1:
The patent replaces indirect inference methods with direct physical measurement using height sensors. By measuring the actual height of each pad at its installation position, the system adapts to individual pad characteristics (thickness, groove depth) and accurately tracks wear from the actual starting point, regardless of pad variety.
Solution Approach 2:
The patent applies local measurement by positioning the height sensor to measure pad height at the specific location where the pad contacts the substrate during polishing. This local quality approach accounts for variations in pad geometry and ensures accurate wear measurement that reflects actual polishing conditions, enabling precise life determination for each individual pad.
Data Source
AI summary
A polishing apparatus includes a table rotating motor configured to rotate a polishing table about its own axis, a top ring rotating motor configured to rotate a top ring about its own axis, a dresser configured to dress a polishing pad, and a pad-height measuring device configured to measure a height of the polishing pad. The polishing apparatus also includes a diagnostic device configured to calculate an amount of wear of the polishing pad from the height of the polishing pad and to determine the end of a life of the polishing pad based on the amount of the wear of the polishing pad, the torque or current of the table rotating motor, and the torque or current of the top ring rotating motor.