Wavefront Optimization for Lithography Scanner Tuning
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Solution Overview
Problem
Current lithographic projection apparatuses face challenges in accurately transferring patterns with dimensions smaller than the classical resolution limit, due to limitations in wavelength and numerical aperture, leading to difficulties in reproducing intended patterns for precise electrical functionality and performance.
Innovation Solution
A method is developed to determine the wavefront of a patterning apparatus by obtaining a reference performance, a lens model, and a lens fingerprint of a tuning scanner, using a cost function to iteratively adjust wavefront parameters based on simulation and metrology data, optimizing actuator movements to improve edge placement error and critical dimension accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography with fixed wavelength and numerical aperture is used, then the apparatus structure is simple, but the manufacturing precision of patterns smaller than the classical resolution limit deteriorates
Solution Approach 1:
The patent implements dynamic wavefront optimization by adjusting wavefront parameters in real-time during the lithography process. The system dynamically modifies the wavefront shape through controlled deformation of the projection lens, allowing the apparatus to adapt to different pattern requirements and achieve high manufacturing precision without requiring complex hardware changes.
Solution Approach 2:
The patent changes physical parameters of the projection lens, specifically the wavefront shape parameters, to improve pattern transfer accuracy. By controlling the deformation amount of the lens wavefront within a specific range, the system achieves enhanced manufacturing precision while maintaining relatively simple apparatus structure.
2Manufacturing precision
If wavefront parameters are iteratively optimized using simulation and metrology data, then the manufacturing precision improves, but the loss of time increases
Solution Approach 1:
The patent performs preliminary wavefront optimization by pre-calculating optimal wavefront parameters using simulation data before actual lithography operations. The system uses metrology data from test patterns to determine wavefront parameters in advance, reducing the time required during production while maintaining high edge placement accuracy.
Solution Approach 2:
The patent implements feedback mechanisms by comparing simulated performance with actual metrology measurements and using this information to iteratively refine wavefront parameters. This feedback loop allows the system to achieve high manufacturing precision while minimizing optimization time by learning from previous iterations.
Data Source
AI summary
A method for determining a wavefront parameter of a patterning process. The method includes obtaining a reference performance (e.g., a contour, EPE, CD) of a reference apparatus (e.g., a scanner), a lens model for a patterning apparatus configured to convert a wavefront parameter of a wavefront to actuator movement, and a lens fingerprint of a tuning apparatus (e.g., a to-be-matched scanner). Further, the method involves determining the wavefront parameter (e.g., a wavefront parameter such as tilt, offset, etc.) based on the lens fingerprint of the tuning apparatus, the lens model, and a cost function, wherein the cost function is a difference between the reference performance and a tuning apparatus performance.