Real-Time Etch Compensation Using Optical Feedback and ML
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Solution Overview
Problem
Existing etching techniques face challenges in ensuring uniformity of etch rates within substrates and lack real-time feedback for compensating abnormal process conditions, leading to potential etch process failures and non-uniform critical dimensions.
Innovation Solution
The implementation of Interferometer Endpoint (IEP) systems with multiple sensors and a beam conditioning assembly that uses spectral analysis and machine learning models to monitor etch spectra, predict etch depths, and adjust process parameters in real-time to achieve uniformity and detect production issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If broadband light source and spectrometer are used to monitor etch rate in real-time, then etch process uniformity and endpoint detection are improved, but device complexity and cost increase
Solution Approach 1:
The patent implements real-time optical monitoring during the etch process by directing broadband light through the process chamber and analyzing reflected light with a spectrometer. The system continuously monitors etch rate and provides feedback to adjust process parameters, ensuring uniform etching across the substrate and accurate endpoint detection.
Solution Approach 2:
The patent introduces an optical intermediary system that uses broadband light and spectral analysis to indirectly measure etch depth and rate. Instead of direct physical measurement, the system uses light reflection characteristics as an intermediary to infer etch process status, enabling non-contact real-time monitoring.
2Loss of time
If traditional APC systems are used with delay of 3-20 hours, then data analysis is simplified, but process control responsiveness and productivity are reduced
Solution Approach 1:
The patent implements continuous real-time monitoring during the etch process itself, eliminating the discontinuous delayed measurement approach of traditional APC systems. The optical monitoring system operates continuously throughout the etch process, providing uninterrupted data on etch rate and depth, enabling immediate process adjustments without waiting for post-process measurements.
Solution Approach 2:
The patent performs etch depth and rate measurement during the etch process itself rather than after completion. By measuring in real-time, the system can detect deviations early and make corrective adjustments before the etch process finishes, preventing defects rather than detecting them after the fact.
3Reliability
If only one to two wafers are monitored in a lot of 25 wafers, then measurement complexity is reduced, but detection of process errors and failures is insufficient
Solution Approach 1:
The patent divides the substrate surface into multiple measurement zones and uses multiple sensors positioned at different locations to monitor each zone independently. This segmentation allows comprehensive coverage of all 25 wafers in a lot, detecting local variations in etch rate and identifying process anomalies that would be missed by monitoring only one or two wafers.
Solution Approach 2:
The patent creates a multi-functional monitoring system that simultaneously performs multiple functions: measuring etch rate, detecting endpoint, monitoring uniformity across multiple wafers, and identifying process anomalies. The optical system serves as a universal monitoring tool that handles all these functions through spectral analysis of light reflected from different substrate locations.
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 approach enables real-time etch process adjustments, improving etch rate uniformity, detecting production issues, and ensuring accurate endpoint detection, thereby enhancing the reliability and precision of the etching process.
Implementation Method 1
directing a beam having a plurality of wavelengths to a substrate being etched and collecting wavelengths reflected from the substrate
Data Source
AI summary
A method for real-time compensation control of an etch process includes: providing a substrate having a layer in a process chamber; performing the etch process on the layer; directing one or more wavelengths to a region of the layer by a beam conditioning assembly; receiving one or more reflected wavelengths from the region of the layer; predicting a process variable by processing the one or more reflected wavelengths using a machine learning model; and comparing the predicted process variable with a predetermined process variable to obtain a comparison result.