Exposure Apparatus Imaging Correction via Illumination Distribution
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Solution Overview
Problem
Existing exposure methods face challenges in accurately controlling imaging performance during changes in illumination conditions, leading to focus and alignment errors due to heat generation in projection optical systems, and result in decreased throughput as they require stopping exposure or measuring imaging performance.
Innovation Solution
An exposure method that involves a first and second exposure step with different pupil plane illumination distributions, obtaining the change amount of imaging performance, and using this to calculate a correction amount for accurate imaging performance correction during the second exposure step, allowing continuous exposure without stopping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If exposure is performed while continuously irradiating light to the projection optical system, then productivity is improved, but imaging performance changes due to heat generation causing focus and alignment errors
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction amounts for imaging performance changes in a lookup table before exposure begins. The correction amounts are prepared in advance for various illumination conditions and accumulated energy amounts, allowing immediate correction without waiting for actual performance degradation to occur.
Solution Approach 2:
The patent implements feedback by continuously monitoring the accumulated energy amount in the projection optical system and using this information to dynamically select appropriate correction amounts from the pre-prepared data. The correction amounts are applied in real-time to maintain imaging performance accuracy while allowing continuous exposure operation.
2Manufacturing precision
If exposure is stopped to allow temperature distribution to stabilize after illumination condition changes, then imaging performance accuracy is improved, but productivity decreases
Solution Approach 1:
The patent prepares correction amounts in advance for various illumination conditions and accumulated energy states, so when an illumination condition change occurs, the appropriate correction can be immediately applied without stopping exposure. This eliminates the need to wait for temperature stabilization while maintaining imaging accuracy.
Solution Approach 2:
The patent enables continuous exposure operation by applying dynamic corrections based on accumulated energy amounts. Instead of stopping exposure to allow thermal stabilization, the system continuously corrects imaging performance parameters based on real-time energy accumulation data, maintaining both productivity and precision.
3Manufacturing precision
If correction amount is adjusted based on accumulated energy amount after illumination condition changes, then imaging performance accuracy in transient state is improved, but device complexity increases
Solution Approach 1:
The patent creates a simplified model of the complex thermal behavior by pre-measuring and storing correction amounts in a lookup table. Instead of implementing complex real-time thermal modeling and calculation systems, the patent copies the results of thorough thermal analysis into accessible data structures that can be quickly queried and applied during exposure operations.
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
This method improves exposure accuracy by accurately determining and correcting imaging performance changes during illumination condition transitions, maintaining high throughput without the need for continuous measurement or stopping exposure.
Implementation Method 1
heat is generated by absorbing a part of the exposure energy
Implementation Method 2
heat is generated by absorbing a part of the exposure energy
Implementation Method 3
the temperature distribution in the lens in the vicinity of a pupil plane of the projection optical system becomes a transient state
Data Source
AI summary
This exposure method comprises a first step of performing the exposure processing by irradiating a projection optical system (the system) by a first pupil plane illumination distribution (the first distribution) of the system; a second step of performing the exposure processing by irradiating the system by a second pupil plane illumination distribution (the second distribution) that is different from the first distribution, after the first step; a change amount obtaining step of obtaining a change amount of an imaging performance of the system in a condition of the second distribution, with respect to the imaging performance in the first step; and a correction amount obtaining step of obtaining a correction amount for correcting the imaging performance in the second step, by using the change amount, wherein, in the second step, the exposure processing is performed by correcting the imaging performance using the correction amount.