Anamorphic Projection Optical Unit for Lithography Mask Transfer
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Solution Overview
Problem
Current projection lithography systems face challenges in increasing throughput and achieving compact optical designs while maintaining optimal projection resolution and efficient substrate coverage.
Innovation Solution
The development of an optical system and projection optical unit that allows for the transfer of lithography mask structure portions onto a substrate with varying imaging scales, enabling a continuous scanning process with reduced displacement and compact structure, using a catoptric or dioptric projection optical unit with anamorphic imaging scales that can be negative, facilitating efficient substrate coverage and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a lithography mask with multiple original structure portions arranged in a row is used with continuous scanning, then throughput is improved, but mask displacement complexity increases
Solution Approach 1:
The patent implements continuous scanning during projection exposure, where the lithography mask and substrate move continuously through the optical system. This allows uninterrupted transfer of original structure portions onto the substrate, maximizing throughput by eliminating idle time between exposure steps while maintaining precise positional control through synchronization mechanisms.
2Productivity
If different imaging scales are used in two object dimensions, then substrate coverage efficiency is improved, but optical system complexity increases
Solution Approach 1:
The patent employs an anamorphic projection optical unit with different magnification factors in the x and y directions (e.g., 4x in x-direction and 1x in y-direction). This asymmetric imaging approach allows efficient coverage of rectangular substrates by stretching the projected image in one dimension while maintaining natural scaling in the other, reducing the number of required transfer operations without requiring complex multi-axis movement mechanisms.
3Productivity
If the aspect ratio of original structure portions is greater than 4:1, then transfer efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies that original structure portions on the lithography mask should have an aspect ratio greater than 4:1 (length in scanning direction divided by width perpendicular to scanning direction). This parameter optimization allows each structure portion to be transferred efficiently during continuous scanning while the anamorphic optical system compensates for the high aspect ratio through its differential magnification, maintaining imaging precision despite the elongated geometry.
Data Source
AI summary
An optical system transfers original structure portions (13) of a lithography mask (10), which have an x/y-aspect ratio of greater than 4:1, and are aligned on the lithography mask, separated respectively by separating portions (14) that carry no structures to be imaged. The optical system transfers the original structure portions onto image portions (31) of a substrate (26). Each of the original structure portions is transferred to a separate image portion. The image portions onto which the original structure portions are transferred are arranged in a line next to one another. An associated projection optical unit may have an anamorphic embodiment with different imaging scales for two mutually perpendicular field coordinates specifically, one that is reducing for one of the field coordinates and the other is magnifying for the other field coordinates.