Interferometer Etch Control for Real-Time Uniformity Compensation
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Solution Overview
Problem
Existing etching techniques struggle with ensuring good etch rate uniformity within a substrate and lack in-situ feedback for real-time compensation of etch processes, leading to potential errors and failures in etch processes.
Innovation Solution
The use of Interferometer Endpoint (IEP) systems to monitor etch spectra for process stability, with sensors located at strategic regions of the process chamber, allowing for real-time etch process adjustments to improve uniformity and detect production issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional APC systems are used for etch process control, then etch performance can be monitored, but the system has a delay of 3 to 20 hours and can only monitor one to two wafers in a lot of 25 wafers
Solution Approach 1:
The patent replaces traditional mechanical/electrical measurement systems with optical interferometry. The interferometer system uses light waves to measure etch depth and rate in real-time, eliminating the time delays associated with conventional post-processing measurement methods. This optical measurement approach enables immediate feedback during the etch process.
Solution Approach 2:
The patent implements real-time feedback control by continuously monitoring etch depth and rate during the etching process using interferometry. The system provides immediate feedback signals that can be used to adjust process parameters on-the-fly, eliminating the 3-20 hour delay of traditional APC systems and enabling monitoring of all wafers in a lot rather than just one or two.
2Reliability
If traditional APC systems monitor only one to two wafers in a lot of 25 wafers, then some etch performance data can be obtained, but errors or failures in etch processes may not be detected
Solution Approach 1:
The patent divides the monitoring function into multiple independent interferometer sensors that can be distributed throughout the etch chamber. Each sensor monitors specific regions or wafers independently, allowing comprehensive coverage of all 25 wafers in a lot. This segmented approach enables detection of localized process variations and failures that would be missed by monitoring only one or two wafers.
Solution Approach 2:
The interferometer system serves multiple functions simultaneously: it measures etch depth, calculates etch rate, detects endpoint, and monitors process uniformity across all wafers. This multi-functional capability provides comprehensive etch process monitoring and reliability assessment without requiring separate measurement systems for each function.
3Manufacturing precision
If interferometer systems are used for real-time etch process monitoring, then etch rate uniformity can be improved and production issues detected, but the system complexity increases
Solution Approach 1:
The patent uses interferometry to precisely measure changes in etch depth and rate in real-time. By monitoring these parameters continuously, the system can detect deviations from uniform etching and provide feedback for process adjustment. This precise parameter measurement capability enables improved etch rate uniformity across the wafer and throughout the production lot.
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
IEP systems enable real-time etch process adjustments, improving etch rate uniformity and allowing for the detection of production issues such as the first wafer effect, etch chamber stability, and gas or power abrupt changes, thereby enhancing the reliability of etch processes.
Implementation Method 1
a broadband light source to illuminate the substrate and a spectrometer to measure light reflected off the center of a substrate being etched
Implementation Method 2
Interferometer Endpoint (IEP) systems to monitor etch spectra
Data Source
AI summary
An apparatus includes a beam conditioning assembly configured to output one or more wavelengths to a substrate being processed and receive one or more reflected wavelengths from the substrate, and a machine learning device configured to process the one or more reflected wavelengths to predict a process variable and compare the predicted process variable with a measured process variable to obtain a comparison result.