Film Thickness Signal Processing for Edge Detection Accuracy
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Solution Overview
Problem
Current film thickness sensors in semiconductor polishing processes face challenges in accurately detecting film thickness at edge parts of the polishing object, leading to incomplete data collection and reduced in-plane uniformity.
Innovation Solution
A film thickness signal processing apparatus that receives data from sensors, identifies effective ranges by determining edge parts through film thickness differences, and corrects data within these ranges to enhance accuracy and coverage, allowing for improved detection and control of the polishing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If edge cut processing is performed to discard sensor output at locations where output does not reach 100%, then the reliability of film thickness data is improved, but the measurement precision at edge parts deteriorates
Solution Approach 1:
The patent changes the parameter of sensor output threshold from a fixed 100% requirement to a variable effective range determined by actual sensor response characteristics. By identifying the effective range where the sensor output reaches a predetermined threshold (not necessarily 100%) and using this adaptive range for correction, the system maintains data reliability while preserving edge part measurement precision.
Solution Approach 2:
The patent replaces the mechanical edge cut processing approach (physically discarding data points) with a signal processing approach (correcting data within the effective range). Instead of removing edge data, the system identifies the effective range and applies correction algorithms to restore measurement precision while maintaining the reliability benefits of threshold-based selection.
2Measurement precision
If the film thickness sensor is positioned to face the central part of the surface to be polished, then the output of the film thickness sensor reaches approximately 100%, but the effective range of detection is reduced
Solution Approach 1:
The patent extends the detection coverage by processing data in the temporal dimension - identifying the effective range over time as the sensor rotates and detecting film thickness at multiple positions. This allows the system to capture edge part data that would be missed if only central position data were used, effectively expanding the detection area without changing the physical sensor position.
3Area of stationary object
If only part of the spot diameter faces the polishing object at edge parts, then the sensor can detect edge regions, but the output of the film thickness sensor does not reach 100%
Solution Approach 1:
The patent implements feedback by using the identified effective range information to guide the correction process. The system determines where the sensor output is sufficient (within the effective range) and applies correction algorithms specifically to those regions, using the known good data to restore and enhance the quality of edge part measurements where output is weaker.
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 solution improves the accuracy of film thickness detection at edge parts and widens the effective range of sensor output, resulting in enhanced in-plane uniformity and control of the polishing process.
Implementation Method 1
The eddy-current sensor induces an eddy current in the polishing object, such as a conductive film, and detects the thickness of the polishing object from a change in a magnetic field caused by the eddy current induced in the polishing object.
Implementation Method 2
The eddy-current sensor induces an eddy current in the polishing object, such as a conductive film, and detects the thickness of the polishing object from a change in a magnetic field caused by the eddy current induced in the polishing object.
Implementation Method 3
the optical sensor radiates light to the polishing object and measures an interference wave reflected from the polishing object, thereby detecting the thickness of the polishing object.
Data Source
AI summary
The present invention improves the accuracy of film thickness detection. A film thickness signal processing apparatus 230 is provided with a receiving unit 232 for receiving film thickness data output from an eddy-current sensor 210 for detecting the film thickness of a polishing object 102 along a surface to be polished thereof; an identifying unit 236 for identifying the effective range of the film thickness data on the basis of the film thickness data received by the receiving unit 232; and a correcting unit 238 for correcting the film thickness data within the effective range identified by the identifying unit 236.