EUV Light Source Mirror Control for Pre-Pulse Path Compensation
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Solution Overview
Problem
In extreme ultraviolet lithography for semiconductor fabrication, existing systems face challenges in maintaining precise optical paths for pre-pulses and main pulses, leading to excessive compensation errors and reduced conversion efficiency due to heat-induced distortions in high-powered light sources.
Innovation Solution
A light source system with first and second pulse generators, reflection mirrors, and a beam splitting device that adjusts and compensates the optical paths of pre-pulses and main pulses using a controller to maintain constant optical paths, employing a beam detector to calculate error values and adjust reflection mirrors to prevent excessive correction of the main pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single reflection mirror system is used to compensate for pre-pulse optical path errors, then the pre-pulse optical path can be corrected, but the main pulse receives excessive compensation due to phase delays in the beam splitting device
Solution Approach 1:
The reflection mirror system is divided into two independent sets: a first reflection mirror for the pre-pulse path and a second reflection mirror for the main pulse path. This segmentation allows each mirror to be controlled independently, preventing the excessive compensation that occurs when a single mirror controls both paths. The beam splitting device is also segmented into first and second beam splitters that work with their respective mirrors to provide precise, separate control.
Solution Approach 2:
A feedback control system is implemented where optical path sensors detect actual path deviations, and the controller adjusts the first and second reflection mirrors based on detected errors. The controller receives feedback from both the pre-pulse and main pulse optical paths and makes real-time adjustments to compensate for deviations without causing excessive correction. This closed-loop feedback ensures that each pulse receives appropriate compensation based on actual measured errors.
2Productivity
If high-powered laser pulses are used to generate extreme ultraviolet light, then conversion efficiency improves, but heat-induced optical path distortions increase
Solution Approach 1:
The first reflection mirror compensates for the pre-pulse optical path error before the main pulse is generated. By pre-compensating the optical path using the pre-pulse and its dedicated reflection mirror, the system establishes a stable reference path before the high-powered main pulse is introduced. This preliminary action prevents heat-induced distortions from affecting the overall optical alignment, allowing high conversion efficiency to be maintained while preserving optical path stability.
Solution Approach 2:
The reflection mirrors are designed to be dynamically adjustable during operation. The controller can modify the mirror positions in real-time based on detected optical path deviations caused by heat. This dynamic adjustment capability allows the system to maintain stable optical paths even as thermal conditions change during high-powered laser operation, ensuring both high conversion efficiency and optical stability.
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 solution ensures accurate and stable generation of extreme ultraviolet light by maintaining precise optical paths, reducing excessive compensation errors and enhancing conversion efficiency, thereby improving semiconductor device fabrication capabilities.
Implementation Method 1
a first reflection mirror reflecting the pre-pulse and the main pulse to adjust optical paths of the pre-pulse and the main pulse
Implementation Method 2
third and fourth reflection mirrors reflecting the main pulse reflected by the first beam splitter to the second beam splitter to delay the phase of the main pulse
Implementation Method 3
an optical assembly disposed inside the exposure chamber, condensing the pre-pulse and the main pulse provided from the beam transfer device at respective focal positions
Data Source
AI summary
A light source capable of operating third and fourth reflection mirrors included in a beam splitting device in conjunction with movements of first and second reflection mirrors included in a beam transfer device and an optical assembly, respectively. The third and fourth reflection mirrors are disposed on optical paths of a pre-pulse and a main pulse emitted from first and second pulse generators, respectively. The light source operates the third and fourth reflection mirrors to offset an excessive compensation of the main pulse caused in a process of compensating for an optical path error of the pre-pulse. The light source may be included in an extreme ultraviolet light source system.