Lithography Exposure Correction Using Filtered Process Time Series
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Solution Overview
Problem
Existing automated process control methods in lithographic manufacturing leave residual variations in parameters like focus, overlay, and critical dimension across substrates, leading to inefficiencies and unnecessary metrology steps.
Innovation Solution
A device manufacturing method that involves obtaining measurement and status data time series, applying filters to these data sets to correct exposure steps, and determining corrections for subsequent substrates, allowing for improved automated process control by leveraging time filters and status data from process tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automated process control uses measurements from multiple substrates to adjust exposures, then yield is improved, but residual variations (fingerprint) across substrates remain
Solution Approach 1:
The patent implements feedback control by measuring process parameters on substrates and using these measurements to adjust exposures on subsequent substrates. The system continuously monitors parameters like focus, overlay, and CD, then feeds this information back to modify the exposure process, thereby reducing residual variations while maintaining high yield.
Solution Approach 2:
The patent dynamically changes exposure parameters based on measured data from previous substrates. By adjusting exposure dose, focus, and other parameters in response to actual measurements, the system compensates for process variations and reduces the fingerprint effect across substrates while preserving the yield improvements from APC.
2Measurement precision
If measurements are performed on multiple substrates for process control, then accuracy is improved, but metrology time and complexity increase
Solution Approach 1:
The patent applies partial action by selectively measuring only the most critical process parameters on a subset of substrates rather than performing comprehensive metrology on all substrates. This approach maintains sufficient process control accuracy while reducing the time and complexity burden of extensive measurements.
Solution Approach 2:
The patent performs preliminary measurements on a few representative substrates to establish process trends and corrections before full production. This preliminary action provides sufficient guidance for process adjustments without requiring extensive metrology time during high-volume manufacturing, thus balancing accuracy with efficiency.
Data Source
AI summary
A device manufacturing method, the method comprising: obtaining a measurement data time series of a plurality of substrates on which an exposure step and a process step have been performed; obtaining a status data time series relating to conditions prevailing when the process step was performed on at least some of the plurality of substrates; applying a filter to the measurement data time series and the status data time series to obtain filtered data; and determining, using the filtered data, a correction to be applied in an exposure step performed on a subsequent substrate.