Imprint Lithography Template Alignment Mark Using Dielectric Phase Shift
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Solution Overview
Problem
The existing alignment marks on imprint templates provide insufficient reflection or diffraction of alignment radiation, leading to poor alignment accuracy between the imprint template and the substrate due to similar refractive indices between the template and the imprintable medium.
Innovation Solution
Incorporating a dielectric material with a refractive index different from the imprint template, strategically positioned to create a phase difference for alignment radiation, either as strips or a wire grid polarizer, to enhance diffraction and reflection, thereby improving alignment precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment marks are provided on the imprint template, then alignment between substrate and template can be achieved, but the alignment signal strength is insufficient due to similar refractive indices
Solution Approach 1:
The patent changes the optical parameter (refractive index) of the alignment mark material to differ from both the template and substrate materials. This parameter change creates sufficient optical contrast for strong reflection and diffraction signals while maintaining alignment functionality.
Solution Approach 2:
The alignment mark is formed from a specific dielectric material with refractive index n=2.0, which is different from the template material (n=1.5) and substrate material (n=1.4). This local differentiation of material properties at the alignment mark location creates the necessary optical contrast for strong alignment signals.
2Illumination intensity
If the dielectric material thickness is increased to enhance diffraction, then alignment signal strength improves, but the alignment mark becomes more complex to manufacture
Solution Approach 1:
The patent specifies an optimal thickness range (50-200 nm) that balances signal strength with manufacturability. This parameter optimization ensures sufficient diffraction and reflection while remaining compatible with standard thin film deposition techniques.
Solution Approach 2:
The dielectric material thickness is designed to be sufficient to provide strong alignment signals through enhanced diffraction and reflection, but not excessively thick to complicate manufacturing. The optimal range achieves the necessary optical effect without over-engineering.
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
The enhanced diffraction and reflection from the dielectric material alignment marks result in a stronger alignment signal, allowing for more accurate alignment of the imprint template and substrate, with the potential for 10 times stronger signal strength compared to traditional methods.
Implementation Method 1
the dielectric material having a thickness which is such that it provides a phase difference between alignment radiation which has passed through the dielectric material and alignment radiation which has not passed through the dielectric material
Implementation Method 2
the alignment mark is formed from dielectric material having a refractive index which differs from the refractive index of the imprint lithography template
Implementation Method 3
dielectric material having a refractive index which differs from the refractive index of the imprint lithography template
Implementation Method 4
some degree of reflection of the alignment radiation occurs due to constructive interference at the surface of the dielectric material
Implementation Method 5
some degree of reflection of the alignment radiation occurs due to constructive interference at the surface of the dielectric material
Implementation Method 6
the imprintable medium flows into recesses in the patterned surface and is pushed aside by protrusions on the patterned surface
Implementation Method 7
The imprintable medium is then suitably cured, for example by illuminating the imprintable medium with actinic radiation
Data Source
AI summary
An imprint lithography template is provided with an alignment mark, wherein the alignment mark is formed from dielectric material having a refractive index which differs from the refractive index of the imprint lithography template, the dielectric material having a thickness which is such that it provides a phase difference between alignment radiation which has passed through the dielectric material and alignment radiation which has not passed through the dielectric material.