Lithography Alignment via Local Mark Shift Detection
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Solution Overview
Problem
Existing lithography apparatuses face challenges in accurately transferring patterns to shot regions on substrates due to individual positional shifts of marks caused by manufacturing errors and substrate deformation, which are not adequately addressed by current alignment methods.
Innovation Solution
A lithography apparatus equipped with a detection unit to detect marks on both the substrate and the original, and a control unit that adjusts alignment based on positional shift information to ensure accurate pattern transfer, even when overlay errors fall within an allowable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If alignment is performed based on detection result of marks without considering individual positional shifts, then the alignment process is simple, but the pattern transfer accuracy deteriorates
Solution Approach 1:
The patent segments the shot region into multiple areas, each with its own alignment marks. Instead of treating the entire shot region as a single unit, the system performs separate alignment measurements for each segment, capturing individual positional shifts that occur within different regions of the shot. This segmentation enables the detection of local variations in mark positions that would be averaged out in a global alignment approach.
Solution Approach 2:
The patent applies local quality by making the alignment correction specific to each detected mark rather than applying a uniform correction across the entire shot region. The control unit calculates and applies individual positional shift amounts for each mark based on its specific location and detected deviation, allowing each local area to be corrected according to its actual conditions rather than using a blanket correction approach.
2Reliability
If multiple marks are used for alignment detection, then the measurement reliability improves, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent employs multiple detection units that can detect multiple marks simultaneously within the shot region. Each detection unit is capable of detecting the position of alignment marks, and the system is designed to handle and process information from multiple marks in a unified manner. This multi-functional detection system improves reliability by providing multiple measurement points while managing the complexity through standardized detection and processing procedures.
Data Source
AI summary
The present invention provides a lithography apparatus for transferring a pattern formed on an original to each of a plurality of shot regions on a substrate, comprising a detection unit configured to detect a mark provided in the shot region and a mark provided on the original, and a control unit configured to control alignment between a target shot region and the pattern of the original such that the mark in the target region detected by the detection unit and the mark on the original are shifted by a positional shift amount which is generated between each mark in the shot region and each mark on the original when an overlay error between the shot region and the pattern of the original falls within an allowable range.