Maskless Lithography Alignment Compensation
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Solution Overview
Problem
In maskless lithography, accurately determining the exposure start position and orientation of a substrate is challenging due to difficulties in aligning the substrate with the exposure scan direction, leading to deviations in the formed pattern from the desired exposure region.
Innovation Solution
A method involving the use of alignment marks on multiple pattern layers, measured by a measurement system, to calculate and compensate for relative position and orientation differences between the desired and obtained exposure start positions and orientations, utilizing equations to determine corrected command values for the exposure apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If maskless lithography is used to eliminate photo-masks, then production flexibility and lead time are improved, but alignment precision between substrate loading and exposure scan direction deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-patterning alignment marks on the substrate before the exposure process. These alignment marks serve as reference features that enable subsequent measurement and compensation of substrate position and orientation, allowing the system to correct alignment deviations without requiring perfect initial alignment
Solution Approach 2:
The patent implements feedback through a measurement system that detects the actual positions of alignment marks on the substrate. The measured position and orientation information is fed back to the control system, which then calculates compensation values to correct the exposure start position and orientation, closing the control loop to maintain alignment precision
2Ease of manufacture
If equipment is assembled without precise alignment, then device complexity and assembly difficulty are reduced, but exposure start position and orientation accuracy deteriorates
Solution Approach 1:
The patent applies self-service by enabling the measurement system to automatically detect alignment marks and calculate compensation values without requiring manual intervention for precise alignment. The system self-corrects for assembly deviations by using the measured alignment mark positions to determine the actual exposure start position and orientation, eliminating the need for complex manual alignment procedures
Data Source
AI summary
According to an example embodiment, a method to determine an exposure start position and orientation includes loading a substrate on a moving table. The substrate includes at least one alignment mark of a first set of alignment marks of a first pattern layer patterned thereon. At least one alignment mark of a second set of alignment marks of a second pattern layer is exposed on the substrate using maskless lithography. A position of the at least one alignment mark of the first set of alignment marks and a position of the at least one alignment mark of the second set of alignment marks on the substrate is measured. A relative orientation difference between a desired exposure start orientation and an obtained exposure start orientation is acquired using the measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks. A relative position difference between a desired exposure start position and an obtained start position is acquired using the measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks. An exposure start position and orientation compensated using the relative position difference and the relative orientation difference is determined.