Aerial Image Correlation for Lithography Overlay Correction
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Solution Overview
Problem
Existing lithographic processes face challenges in accurately positioning features on substrates, particularly in achieving overlay and critical dimension control, which are critical for producing high-yield semiconductor devices, and current methods for correcting these issues are time-consuming and indirect.
Innovation Solution
A method involving the measurement of aerial image data during exposure apparatus actions, such as component movements and fluid flows, to correlate and determine corrections or mitigations for overlay and critical dimension errors, using a TIS system to estimate and correct dynamic contributions to imaging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If in-resist metrology is used to measure overlay and critical dimension, then measurement accuracy is improved, but measurement time is excessive and productivity is reduced
Solution Approach 1:
The patent introduces an intermediary measurement system that captures aerial image data before the resist development process. This intermediary measurement approach allows overlay and critical dimension parameters to be measured without requiring the time-consuming in-resist metrology process, thereby maintaining measurement accuracy while significantly improving productivity
Solution Approach 2:
The system performs preliminary measurements of aerial image data during the exposure process itself, before the substrate undergoes resist processing. By capturing and analyzing the aerial image at this earlier stage, the system obtains overlay and critical dimension information without waiting for the resist development step, thus eliminating the time delay associated with in-resist metrology
2Productivity
If dynamic actions are performed on the exposure apparatus during exposure, then productivity is improved, but overlay and critical dimension control deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where aerial image data is measured during exposure operations, and the measured data is used to determine corrections for overlay and critical dimension. This real-time feedback allows dynamic actions to be performed during exposure while maintaining precision control through continuous monitoring and correction
Solution Approach 2:
The system embraces dynamic operations during exposure by allowing component movements and fluid flows to occur simultaneously with aerial image measurement. Rather than restricting dynamic actions, the system adapts by measuring the aerial image under actual operating conditions and using this data to determine appropriate corrections, thus maintaining precision while enabling high productivity
3Manufacturing precision
If corrections for overlay and critical dimension are determined after exposure, then manufacturing precision is improved, but time consumption increases
Solution Approach 1:
The system performs preliminary measurement of aerial image data during the exposure process itself, rather than waiting until after exposure is complete. By capturing the aerial image at the moment of exposure and immediately analyzing it for overlay and critical dimension parameters, the system determines corrections without adding post-exposure time, thus maintaining precision while minimizing time loss
Data Source
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AI summary
Disclosed is a method of determining a correction and/or mitigation for an effect of an exposure apparatus action of an exposure process on at least one exposure performance metric of the exposure process. The method comprises measuring aerial image data; performing at least one exposure apparatus action simultaneously with the step of measuring aerial image data, the exposure apparatus action comprising a movement of a component of the exposure apparatus and/or an initiation of a fluid flow within the exposure apparatus; correlating the aerial image data with the at least one exposure performance metric to obtain correlated aerial image data; and determining a correction and/or mitigation for the exposure process based on the correlated aerial image data.