Active Spectral Control of Lithography Light Source
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Solution Overview
Problem
In deep ultraviolet optical lithography, achieving precise control over the spectral properties of light beams is crucial for maintaining critical dimension (CD) accuracy, but existing methods struggle with real-time adjustments and accurate estimation of bandwidth, especially under varying optical and mechanical imaging conditions.
Innovation Solution
A system that includes a light source, a beam directing system, a controller, and a spectral property selection system, which receives information about the light beam's spectral properties and optical imaging conditions to estimate characteristic values and adjust the bandwidth within specific ranges, using metrics like focus blur distribution and spectrum width to maintain target values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If real-time spectral control is implemented, then manufacturing precision of critical dimension is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback control system where the actual spectral properties of the light beam are measured and compared to target values, and control parameters are adjusted based on the deviation. This closed-loop feedback mechanism enables real-time spectral control to maintain critical dimension accuracy while systematically managing the complexity through automated control algorithms.
Solution Approach 2:
The system dynamically adjusts spectral parameters (bandwidth, spectral shape) of the light beam based on measured deviations from target values. By changing optical parameters in real-time through controlled adjustment of light source characteristics, the system achieves manufacturing precision improvement while managing complexity through parameter-based control rather than structural complexity.
2Adaptability or versatility
If bandwidth is adjusted within multiple ranges, then adaptability to different imaging conditions is improved, but control system complexity increases
Solution Approach 1:
The patent implements dynamic bandwidth control where the light source bandwidth can be adjusted within multiple ranges (first range and second range) depending on the imaging conditions. This dynamic adaptability allows the system to optimize performance for different critical dimension requirements while managing control complexity through structured control modes that select appropriate bandwidth ranges based on process needs.
3Measurement precision
If spectral property measurement and control are implemented, then measurement precision of light beam characteristics is improved, but device complexity increases
Solution Approach 1:
The system incorporates measurement devices that continuously monitor spectral properties of the light beam and feed this information back to the control system. This feedback loop enables high measurement precision by using actual measured values rather than theoretical calculations, while managing complexity through integrated measurement-control architecture that automates the measurement and adjustment process.
Solution Approach 2:
The patent replaces mechanical or manual spectral adjustment methods with automated electronic control systems that use measured spectral data to drive adjustments. This substitution of mechanical systems with electronic feedback-based control improves measurement precision while managing complexity through software-based control algorithms rather than complex mechanical adjustment mechanisms.
Data Source
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AI summary
A method of controlling a spectral property of a light beam includes directing a light beam to a lithography exposure apparatus configured to create a pattern on a wafer; receiving information representative of a spectral property of the light beam; receiving information representative of an optical imaging condition of the lithography exposure apparatus; estimating a characteristic value of the light beam based on the received spectral property information and the received optical imaging condition information; determining whether the estimated light beam characteristic value matches a target light beam characteristic value; and if it is determined that the estimated light beam characteristic value does not match the target light beam characteristic value, adjusting the spectral property of the light beam.