Polishing Apparatus Coordinate Correction for Pad Wear
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Solution Overview
Problem
The accuracy of position coordinates associated with film thickness measurements in semiconductor wafer polishing is compromised due to the wear and thickness reduction of the polishing pad, leading to shifted measurement points and inaccurate film thickness determination.
Innovation Solution
A polishing apparatus equipped with a pad-thickness measuring device and an optical film-thickness measuring device that emits light obliquely to the substrate, allowing for the determination of the amount of movement of measurement coordinates based on correlation data, thereby correcting the measurement coordinates to maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the polishing pad is used continuously for polishing wafers, then the productivity is improved, but the thickness of the polishing pad decreases causing measurement coordinate shifts
Solution Approach 1:
The system continuously measures the polishing pad thickness using a pad thickness measuring device and feeds this information back to the control unit. The control unit then corrects the measurement coordinates of the optical film thickness measuring device based on the measured thickness change, maintaining measurement accuracy throughout the polishing pad's service life.
Solution Approach 2:
The system performs preliminary measurement of the polishing pad thickness at the beginning of the polishing process. This initial measurement establishes a baseline that is used to calculate and apply coordinate corrections throughout subsequent polishing operations, preventing cumulative measurement errors.
2Duration of action of stationary object
If the polishing pad thickness decreases due to wear, then the polishing process can continue, but the position coordinates of film thickness measurements become inaccurate
Solution Approach 1:
The control unit continuously monitors polishing pad thickness and dynamically adjusts the measurement coordinates of the optical film thickness measuring device in real-time, ensuring accurate film thickness measurements even as the polishing pad wears throughout its service life.
Solution Approach 2:
The system changes the measurement parameters (coordinates) of the optical film thickness measuring device based on the measured polishing pad thickness. As the pad thickness parameter changes due to wear, the measurement coordinates are相应ly adjusted to maintain measurement accuracy.
3Area of stationary object
If the optical sensor head scans across the substrate to measure film thickness at multiple points, then the measurement coverage is improved, but the complexity of the measuring device increases
Solution Approach 1:
The control unit acts as an intermediary that processes the relationship between the optical sensor head measurements and the polishing pad thickness. It calculates the coordinate corrections based on pad thickness and applies these corrections to the film thickness measurements, simplifying the overall system architecture.
Solution Approach 2:
The control unit performs multiple functions: it controls the polishing process, processes optical film thickness measurements, measures polishing pad thickness, and calculates coordinate corrections. This multi-functionality reduces the need for separate dedicated components for each function.
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
The apparatus improves the accuracy of position coordinates associated with film thickness measurements by accounting for the pad thickness changes, ensuring precise polishing endpoint detection and maintaining measurement accuracy despite pad wear.
Implementation Method 1
The optical film-thickness measuring device emits light obliquely to measurement points on the substrate, receive reflected light from the substrate, and determine measured values of film thickness at the measurement points based on the reflected light
Data Source
AI summary
A polishing apparatus that can improve an accuracy of position coordinates associated with a measured value of film thickness is disclosed. The polishing apparatus includes: a pad-thickness measuring device configured to measure a thickness of the polishing pad; an optical film-thickness measuring device configured to emit light obliquely to the substrate, and determine measured values of film thickness at measurement points; and a controller configured to associates the measured values of the film thickness with measurement coordinates indicating positions of the measurement points. The controller is configured to determine amount of movement of the measurement coordinates corresponding to a measured value of the thickness of the polishing pad based on correlation data indicating a relationship between the thickness of the polishing pad and the amount of movement of the measurement coordinates; and correct the measurement coordinates associated with the measured values of the film thickness based on the determined amount of movement of the measurement coordinates.