Two-Stage Optimization for Microlithography Projection Lens Aberration Correction
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Solution Overview
Problem
Current microlithographic projection exposure apparatuses face inefficiencies in establishing travel commands during operating and maintenance adjustments due to the time-consuming nature of conventional optimization algorithms, which often disregard application-specific structure information, leading to insufficient cycle rates and prolonged setup times.
Innovation Solution
A two-stage optimization method is implemented, where the first stage uses a fast optimization algorithm based on a predefined standard angular distribution to generate an approximation of the travel command, and the second stage, using a more complex algorithm, accounts for application-specific structure information to adapt the travel command, allowing for faster and more accurate adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fundamental optimization algorithms are used to calculate travel commands taking account of application-specific structure information, then manufacturing precision is improved, but productivity deteriorates due to insufficient cycle rates
Solution Approach 1:
The optimization process is divided into two distinct stages: a first stage using fast optimization algorithms to generate an initial approximation of the travel command, and a second stage using fundamental optimization algorithms to refine this approximation with application-specific structure information. This segmentation allows the system to benefit from both speed and precision without sacrificing cycle rate requirements.
2Manufacturing precision
If fundamental optimization algorithms are used during maintenance adjustment, then manufacturing precision is improved, but loss of time increases due to prolonged setup times
Solution Approach 1:
During maintenance adjustment, the first optimization stage generates an approximation of the travel command in advance, which serves as a starting point for the second stage. This preliminary action significantly reduces the computational time required for the fundamental optimization algorithms, thereby reducing overall setup time while maintaining correction precision.
3Productivity
If fast optimization algorithms are used to maintain productivity, then cycle rate is improved, but manufacturing precision deteriorates due to simplified assumptions and disregard of application-specific structure information
Solution Approach 1:
The approximation generated by the fast optimization algorithm serves as an intermediary result that bridges the gap between speed and precision. This intermediate solution is then refined by the second stage using fundamental optimization algorithms with application-specific structure information, ensuring both cycle rate requirements and manufacturing precision are met.
4Adaptability or versatility
If semiactive manipulators are used to extend manipulator system range, then adaptability is improved, but reliability deteriorates due to limited lifetime drivings
Solution Approach 1:
The optimization algorithm determines the minimal necessary adjustment travels for manipulators, including semiactive ones. By calculating only the essential corrections needed to achieve the desired aberration correction, the system extends the usable lifetime of semiactive manipulators while maintaining the adaptability to handle various aberration conditions.
Data Source
AI summary
A microlithographic projection exposure apparatus includes: a projection lens for imaging mask structures via an exposure radiation including at least one optical element and at least one manipulator; a read-in device for reading in application-specific structure information defining at least one property of an angular distribution of the exposure radiation upon entering the projection lens; and a travel establishing device for establishing a travel command defining a change to be made in an optical effect of the at least one optical element by manipulation of a property of the optical element via the at least one manipulator along a travel. The travel establishing device is configured to establish the travel command in an at least two-stage optimization.