Polishing Endpoint Detection via Drive Current Adjustment
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Solution Overview
Problem
The existing polishing processes face challenges in accurately detecting the endpoint of polishing due to small changes in torque current, which can lead to excessive polishing or incomplete circuit formation.
Innovation Solution
An end point detection method that adjusts current control parameters in the drive control unit to enhance the change in drive current with respect to driving load changes, allowing for more accurate detection of the polishing endpoint without altering the existing polishing recipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the existing polishing process is used to detect endpoint by monitoring torque current, then the polishing can be performed with standard equipment, but the detection accuracy is insufficient when torque current changes are small
Solution Approach 1:
The invention changes the parameter being monitored from torque current to motor speed. By detecting changes in motor speed during polishing, the system achieves higher detection accuracy because motor speed exhibits more significant changes when transitioning between different material layers compared to torque current. This parameter substitution resolves the contradiction by improving measurement precision without compromising process reliability.
2Measurement precision
If the polishing endpoint detection is improved by using more sensitive methods, then the accuracy increases, but the device complexity increases
Solution Approach 1:
The invention utilizes the motor's own operational parameters (speed) for detection purposes. The motor controller, which is already part of the polishing apparatus, provides speed information that is directly used for endpoint detection. This self-service approach allows high detection accuracy to be achieved without adding separate complex detection systems, thereby improving measurement precision while avoiding increased device complexity.
3Ease of manufacture
If the torque current monitoring is used for endpoint detection, then the existing polishing recipe can be maintained, but the detection accuracy is compromised due to noise and small signal changes
Solution Approach 1:
The invention switches from monitoring torque current to monitoring motor speed for endpoint detection. Motor speed provides larger signal changes and better noise characteristics during the polishing process, enabling accurate endpoint detection while maintaining the existing polishing recipe. This parameter change resolves the contradiction by improving measurement precision without requiring changes to the polishing process itself.
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 method effectively detects changes in torque current, improving the accuracy of polishing endpoint detection even when changes are small, thus preventing excessive polishing and ensuring proper circuit formation.
Implementation Method 1
a detection step of detecting the drive current supplied to the drive unit based on the current control parameter adjusted in the adjustment step
Implementation Method 2
a drive unit that rotates and drives one of a polishing table that holds a polishing pad and a holding unit that holds a polishing target and presses the polishing target against a polishing pad
Data Source
AI summary
An end point detection method is provided for detecting and end point based on a drive current supplied to a drive unit that rotates and drives one of a polishing table and a holding unit. The end point detection method includes: a step (S102) of determining whether a polishing condition of a polishing process to be executed coincides with a preset specific polishing condition; a step (S103) of adjusting a current control parameter in a drive control unit that controls the drive current, the current control parameter related to a change in the drive current with respect to a change in a driving load of the drive unit, if it is determined that the polishing condition coincides with the specific polishing condition; and a step (S105) of detecting the drive current supplied to the drive unit based on the adjusted current control parameter.