Exposure Apparatus Telecentricity Correction
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Solution Overview
Problem
The existing exposure apparatuses face challenges in accurately correcting image deviations caused by non-zero telecentricity and defocus amounts, especially with the miniaturization of patterns and increased use of thick film resists, which result in significant image shifts and distortions that affect overlay accuracy.
Innovation Solution
An exposure apparatus that includes a projection optical system, a substrate stage, and a controller that uses telecentricity and height information to calculate and correct image deviations by adjusting the substrate and mask stages, as well as the optical systems, to maintain optimal focus and reduce aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the projection optical system is designed to be telecentric to maintain magnification factor deviation and rotation deviation constant, then overlay accuracy is improved, but image deviation correction accuracy deteriorates due to non-zero telecentricity caused by optical aberration
Solution Approach 1:
The system performs preliminary measurement of the actual defocus amount using a focus detection system before exposure, and pre-calculates the image deviation based on the measured defocus amount and stored telecentricity information. This allows the correction amount to be determined in advance, compensating for the non-zero telecentricity effect before the actual exposure occurs.
Solution Approach 2:
The system measures the actual defocus amount during the exposure process using a focus detection system, and uses this measured feedback to calculate and apply the appropriate image deviation correction. This closed-loop feedback mechanism ensures that the correction is based on actual conditions rather than theoretical values, improving correction accuracy despite non-zero telecentricity.
2Adaptability or versatility
If thick film resists are used to increase process capability, then manufacturing versatility is improved, but image shift and distortion increase due to defocus amount, deteriorating overlay accuracy
Solution Approach 1:
The system performs preliminary measurement of the actual defocus amount caused by thick film resist using a focus detection system, and pre-calculates the image deviation based on the measured defocus amount and stored telecentricity information. This allows the correction amount to be determined in advance, compensating for the image shift and distortion caused by thick film resist before the actual exposure occurs.
Solution Approach 2:
The system dynamically changes the correction parameters (image deviation correction amount) based on the measured defocus amount. By storing telecentricity information for respective image heights and calculating the correction amount based on actual defocus measurement, the system adapts to the conditions created by thick film resist, maintaining overlay accuracy despite the increased process capability requirements.
3Device complexity
If independent control of shot region correction and focus position is used to simplify control structure, then device complexity is reduced, but image deviation correction accuracy deteriorates due to non-zero telecentricity
Solution Approach 1:
The system merges the focus position control and shot region correction control into a unified control process. The controller integrates the defocus amount measurement, telecentricity information, and image deviation calculation into a single control flow, allowing both corrections to be applied together based on actual measured conditions, thereby improving correction accuracy without significantly increasing structural complexity.
Solution Approach 2:
The controller is designed with multi-functionality to perform both focus position control and shot region correction control using a unified approach. By storing telecentricity information for respective image heights and using it to calculate image deviation based on measured defocus amount, the controller serves multiple correction purposes through a single integrated system, improving accuracy while maintaining reasonable complexity.
Data Source
AI summary
An exposure apparatus includes a projection optical system configured to project a pattern of a mask onto a substrate, a substrate stage configured to hold and move the substrate, and a controller configured to control exposure of the substrate held by the substrate stage, wherein the controller obtains an amount of deviation of an image of the pattern projected onto the substrate with respect to the pattern of the mask based on telecentricity information, which is information on telecentricity for respective image heights of the projection optical system, and height information, which is information on the height of a surface of the substrate, and corrects deviation of the image based on the obtained amount of deviation to expose the substrate.