Imprint Lithography Mold Structure for Clearer Alignment Marks
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Solution Overview
Problem
The challenge of aligning a mold with high light transmittance to a substrate is exacerbated by the low contrast of alignment marks due to the small refractive index difference with the curable composition, leading to alignment difficulties and increased manufacturing costs from frequent mold deterioration and the need for complex processes to maintain mark contrast.
Innovation Solution
A mold design featuring a mesa portion with alignment marks formed on its surface and a pattern portion covered by an organic material, allowing for precise alignment and reduced degradation of alignment marks through a reusable base portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mold with high light transmittance is used, then the mold can be reused multiple times, but the alignment mark becomes unclear due to small refractive index difference with curable composition
Solution Approach 1:
The patent applies local quality by creating a high-contrast film only in the concave portion of the alignment mark on the mold surface. This localized modification maintains the overall high light transmittance and reusability of the mold while providing enhanced contrast specifically where needed for alignment, resolving the contradiction between mold reusability and alignment mark visibility.
2Measurement precision
If a high-contrast film is provided on the alignment mark, then alignment contrast is improved, but the film thickness decreases during mold cleaning leading to contrast degradation
Solution Approach 1:
The patent implements preliminary action by forming a thick high-contrast film in the concave portion of the alignment mark before the mold is put into service. This pre-formed thick film serves as a buffer that maintains sufficient thickness and contrast even after multiple cleaning cycles and repeated use, preventing the contrast degradation that would otherwise occur with thinner films.
3Measurement precision
If a complicated process is used to provide high-contrast film in concave portion, then alignment contrast is improved, but manufacturing cost increases
Solution Approach 1:
The patent resolves the manufacturing cost contradiction by applying local quality - the high-contrast film is formed only in the concave portion of the alignment mark rather than across the entire mold surface. This localized approach requires simpler and less expensive manufacturing processes compared to coating the whole mold, while still achieving the necessary alignment contrast improvement.
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
Enhances alignment accuracy and reduces manufacturing costs by maintaining alignment mark contrast and enabling the reuse of the mold, thus improving the efficiency of pattern transfer in imprint lithography.
Implementation Method 1
since the difference in refractive index between the mold and the curable composition is small, the alignment mark becomes unclear
Data Source
AI summary
A mold used in imprint lithography, including a base portion including a mesa portion protruding from a base, an alignment mark which includes a first surface combined to a surface of the mesa portion, and is formed to have a thickness from the first surface to a side opposite to the surface, and a pattern portion including a second surface with a pattern formed thereon and a third surface on an opposite side of the second surface, wherein the pattern portion is formed of an organic material, and the third surface and the surface are combined such that the pattern portion covers the alignment mark.