Lithography Overlay Correction Using Pre-Exposure Wafer Grouping
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Solution Overview
Problem
Current lithographic processes face challenges in accurately measuring and correcting overlay and alignment residuals, which are difficult to trace back to their root causes, leading to inefficiencies in high-volume manufacturing due to the need for extensive measurement operations and time-consuming correction strategies.
Innovation Solution
A method and system for determining process corrections by assigning substrates to groups based on pre-exposure parameter data and post-exposure metrology, allowing for dynamic updating of corrections to optimize run-to-run control strategies and improve throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If full overlay measurement is performed on each substrate to take advantage of wafer level control, then manufacturing precision is improved, but productivity deteriorates due to prohibitive time and throughput costs
Solution Approach 1:
The patent segments substrates into different groups based on pre-exposure parameter data characteristics. Instead of applying uniform correction to all substrates, the system divides them into groups (e.g., first group with first characteristics, second group with second characteristics) and applies group-specific corrections. This segmentation enables efficient processing by reducing the number of individual measurements needed while maintaining correction accuracy for each substrate type.
Solution Approach 2:
The patent changes the parameter of correction application from individual-substrate basis to group-based basis. By determining corrections for groups of substrates based on their pre-exposure parameter characteristics rather than performing full overlay measurements on each individual substrate, the system achieves wafer-level control efficiency while maintaining near-per-substrate accuracy through the use of representative group corrections.
2Manufacturing precision
If extensive measurement operations are performed to accurately measure features on substrate, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary classification of substrates into groups based on pre-exposure parameter data before the actual exposure and measurement processes. By determining substrate characteristics in advance and assigning them to appropriate groups, the system prepares correction strategies beforehand, eliminating the need for time-consuming individual measurements during production while maintaining measurement accuracy through group-based correction selection.
3Manufacturing precision
If run-to-run control strategy with historic performance measurements is used to calculate corrections, then manufacturing precision is improved, but productivity deteriorates due to time-consuming correction implementation
Solution Approach 1:
The patent segments the run-to-run control process by dividing substrates into groups based on their characteristics. Instead of calculating and implementing corrections for each substrate individually based on historic performance data, the system calculates group-specific corrections and applies them to all substrates within each group. This segmentation dramatically reduces correction implementation time while maintaining accuracy by ensuring each substrate receives the appropriate correction for its characteristic class.
Data Source
AI summary
A method of determining a correction for a process parameter related to a lithographic process, wherein the lithographic process includes a plurality of runs during each one of which a pattern is applied to one or more substrates. The method of determining includes obtaining pre-exposure metrology data describing a property of a substrate; obtaining post-exposure metrology data comprising one or more measurements of the process parameter having been performed on one or more previously exposed substrates; assigning, based on the pre-exposure metrology data, a group membership status from one or more groups to the substrate; and determining the correction for the process parameter based on the group membership status and the post-exposure metrology data.