Diffraction Grating End Pattern Width Reduction for Imprint Alignment
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Solution Overview
Problem
The existing imprint techniques face alignment accuracy issues due to strong diffracted or scattered light from the ends of diffraction gratings, leading to pattern transfer failures during the alignment of molds and substrates, as these signals cause errors in the detection mechanism.
Innovation Solution
The position detection apparatus employs a design where the width of end patterns in at least one of the diffraction gratings is smaller than the remaining patterns, reducing the generation of strong diffracted and scattered light, and uses a processing unit to accurately detect the relative positions based on moire signals, thereby improving alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If diffraction gratings with uniform pattern widths are used for alignment detection, then the detection mechanism can operate, but strong diffracted light and scattered light are generated from the ends of the diffraction gratings, causing errors in detection signals and deteriorating alignment accuracy
Solution Approach 1:
The patent applies local quality by making the end patterns of the diffraction grating have different properties (smaller width) compared to the remaining patterns. Specifically, the diffraction grating includes a first pattern at an end with a first width and a second pattern adjacent to it with a second width smaller than the first width. This local modification reduces the generation of strong diffracted light and scattered light at the ends, thereby improving detection signal accuracy and alignment precision without affecting the overall functionality of the diffraction grating.
2Measurement precision
If the width of end patterns is reduced to minimize diffracted light, then alignment accuracy improves, but the diffraction grating design becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the diffraction grating into distinct pattern segments: a first pattern at the end with a larger width and a second pattern adjacent to it with a smaller width. This segmentation allows each segment to serve a specific function - the first pattern provides structural definition while the second pattern minimizes unwanted diffraction and scattering. The segmented design achieves improved measurement precision while maintaining reasonable manufacturing complexity through clear, discrete pattern definitions.
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 approach effectively minimizes the influence of unnecessary light at the ends of diffraction gratings, enhancing the accuracy of relative position detection and reducing pattern transfer failures by optimizing the design of diffraction gratings and their illumination.
Implementation Method 1
Light obliquely entering a diffraction grating on the substrate side is diffracted in a non-measurement direction by the diffraction grating
Implementation Method 2
The mark detection mechanism detects the moire caused by the overlap between a diffraction grating on the substrate side and a diffraction grating on the mold side
Data Source
AI summary
The present invention provides a position detection apparatus including a detection unit configured to detect moire caused by overlap between a first diffraction grating including patterns arrayed in a first direction and a second diffraction grating including patterns arrayed in the first direction, and a processing unit configured to obtain a relative position of the first diffraction grating and the second diffraction grating based on the moire, wherein a width of an end pattern of patterns included in at least one of the first diffraction grating and the second diffraction grating in the first direction is smaller than widths of remaining patterns of the at least one diffraction grating in the first direction.