Shutter Control for Lithography Exposure Precision and Throughput
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exposure apparatuses face challenges in achieving high throughput and accurate dose control, particularly when reducing light intensity, which can lead to incomplete exposure and decreased throughput.
Innovation Solution
An exposure apparatus with a shutter and detector system that controls shutter operation based on detected dose, using two modes: a low speed exposure mode for accurate dose control and a high speed mode where shutter speed is adjusted based on stored correction information from the low speed mode, allowing for precise exposure without continuous dose monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the light intensity is reduced to enable accurate dose control with pulse counting, then the exposure precision is improved, but the throughput decreases
Solution Approach 1:
The system performs preliminary calibration by counting pulses at reduced light intensity to determine the relationship between pulse count and dose. This calibration data is stored and then used to enable high-speed exposure at full light intensity without real-time pulse counting, thus achieving both precision and throughput
Solution Approach 2:
The system dynamically switches between two operational modes: a calibration mode with reduced light intensity for accurate dose measurement, and a production mode with full light intensity for high-speed exposure. The controller adapts the operating parameters based on the operational phase
2Productivity
If the shutter closes without pulse counting to increase throughput, then the productivity is improved, but the exposure amount control accuracy deteriorates
Solution Approach 1:
The system uses feedback from pulse counting during calibration to determine the appropriate shutter open time for achieving the target dose. This feedback information is then used to control the shutter duration in high-speed mode, ensuring accurate dose delivery without real-time pulse counting
Solution Approach 2:
The system pre-determines the correct shutter open time by counting pulses during calibration. This preliminary determination of exposure parameters enables subsequent high-speed exposures to be performed accurately without continuous pulse counting
3Device complexity
If the shutter operation delay is not corrected, then the device complexity is reduced, but the exposure precision deteriorates due to dose errors during shutter transition
Solution Approach 1:
The system measures the actual shutter operation delay by comparing the commanded shutter close time with the actual time when the light intensity drops to zero. This feedback information is used to correct future shutter timing commands, compensating for the delay without adding complex hardware
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 approach enables high throughput and accurate exposure amount control, even at higher light intensities, by using correction information from the low speed mode to optimize shutter operation in the high speed mode, reducing variations in dose across shot regions.
Implementation Method 1
a detector configured to detect a dose to the substrate
Data Source
AI summary
An exposure apparatus which illuminates a reticle with illumination light from a light source and projects light from the reticle onto a substrate to expose the substrate to light is disclosed. The apparatus comprises a shutter located on a path of the illumination light, a detector configured to detect a dose to the substrate, and a controller configured to control operation of the shutter. In a first exposure mode which uses illumination light with a first light intensity, the controller controls an open time of the shutter based on an output from the detector, and to store the open time. In a second exposure mode which uses illumination light with a second light intensity higher than the first light intensity, the controller controls a speed of the shutter based on the stored open time.