Moiré Mark Alignment Correction for Imprint Overlay Accuracy
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Solution Overview
Problem
Existing imprint apparatuses face challenges in accurately evaluating the performance of detection units due to variations in the detection of moire images formed by mold and substrate marks, leading to deteriorated accuracy in alignment.
Innovation Solution
An alignment method that includes detecting a moire fringe using a detection unit, correcting the detection result with an evaluation mark having a pattern interval less than the detection unit's resolution, and determining the relative position of the marks to accurately align the mold and substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detection unit detects the moire image formed by the mold mark and the substrate mark, then the alignment between the mold and substrate can be performed, but the detection accuracy is deteriorated due to variation in detection results
Solution Approach 1:
The patent introduces an evaluation mark as an intermediary element to bridge the detection unit and the moire image detection. The evaluation mark, which has a known pattern interval, serves as a reference standard that allows the detection unit's performance to be characterized and compensated, thereby resolving the variability in moire image detection accuracy without requiring the evaluation mark to be part of the actual alignment measurement path.
Solution Approach 2:
The patent implements a feedback mechanism where the detection unit first detects the evaluation mark to obtain characterization data, then uses this data to correct or compensate for subsequent moire image detection results. This feedback loop allows the system to account for detection unit variations and improve measurement precision and reliability.
2Measurement precision
If the evaluation mark has a pattern interval equal to or larger than the detection unit's resolution, then the evaluation mark can be detected, but the correction capability for detection accuracy is insufficient
Solution Approach 1:
The patent applies parameter changes by setting the evaluation mark's pattern interval to be smaller than the detection unit's resolution limit. This creates a situation where the detection unit cannot fully resolve the evaluation mark pattern, causing the detected frequency to deviate systematically from the actual frequency. This controlled deviation provides a measurable error signal that can be used to characterize and correct the detection unit's performance, thereby improving correction capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables high-accuracy detection of moire images and precise alignment of the mold and substrate, improving the overall alignment process in imprint apparatuses.
Implementation Method 1
detecting a moire fringe formed by a mark of the first object and a mark of the second object by using a detection unit
Data Source
AI summary
An alignment method of aligning a first object and a second object includes detecting a moire fringe formed by a mark of the first object and a mark of the second object by using a detection unit, detecting an evaluation mark for correcting a detection result of the moire fringe, by the detection unit, and acquiring a detection result of the evaluation mark, determining a relative position of the mark of the first object and the mark of the second object by correcting a detection result of the moire fringe by use of the detection result of the evaluation mark, and aligning the first object and the second object based on the relative position. The evaluation mark is provided in at least one of the first object and the second object.