Photomask Recess Design for Light Diffraction Control
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Solution Overview
Problem
Existing photomasks used in photolithography processes face challenges in achieving high-resolution patterns due to light diffraction issues, which can affect the critical dimension of semiconductor or display elements.
Innovation Solution
A photomask design featuring a transparent substrate with a recessed area adjacent to the light-blocking film, which prevents light diffraction by refracting light away from the light-blocking area, thereby reducing the need for phase shift masks or hydrophobic polymer lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional photomask without recess is used, then the structure is simple and manufacturing is easier, but light diffraction occurs at the boundary between light-transmitting and light-blocking areas, reducing pattern resolution
Solution Approach 1:
The transparent substrate is segmented by forming a recess at the boundary between the light-transmitting and light-blocking areas. This segmentation creates distinct regions with different optical path lengths, allowing light to be refracted away from the light-blocking area and preventing diffraction, thereby improving pattern resolution.
Solution Approach 2:
The recess introduces a vertical dimension (depth) to the substrate structure at the critical boundary region. By creating a stepped configuration where part of the substrate is removed, the solution transitions from a two-dimensional flat surface to a three-dimensional structure that actively refracts light, resolving the diffraction problem without requiring additional components.
2Manufacturing precision
If phase shift masks or hydrophobic polymer lenses are added to prevent light diffraction, then pattern resolution improves, but manufacturing cost and production time increase
Solution Approach 1:
The diffraction prevention function is merged into the substrate itself by forming a recess during the substrate fabrication process. This eliminates the need for separate phase shift masks or hydrophobic polymer lenses, as the substrate structure itself performs the light refraction function, thereby reducing both manufacturing steps and production time.
Solution Approach 2:
The unnecessary components (phase shift masks and hydrophobic polymer lenses) are extracted from the photomask system. By taking out these additional elements and replacing them with a modified substrate structure, the solution simplifies the overall system while maintaining or improving pattern resolution and reducing production complexity.
3Manufacturing precision
If phase shift masks or hydrophobic polymer lenses are used to prevent light diffraction, then pattern resolution improves, but manufacturing cost increases
Solution Approach 1:
The diffraction prevention function is merged into the substrate itself by forming a recess during the substrate fabrication process. This eliminates the need for separate phase shift masks or hydrophobic polymer lenses, as the substrate structure itself performs the light refraction function, thereby reducing both manufacturing steps and production time.
Solution Approach 2:
The solution replaces expensive additional components (phase shift masks and hydrophobic polymer lenses) with a simple structural modification of the substrate. The recess can be formed using standard fabrication techniques, making the solution more cost-effective while achieving the same optical function.
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 proposed photomask design enhances pattern resolution by minimizing light diffraction, reduces manufacturing costs, and shortens production time by eliminating the need for additional diffraction-preventing components.
Implementation Method 1
light passing through the transparent substrate may be refracted by a surface in the recess
Data Source
AI summary
A photomask includes: transparent substrate including a light-transmitting area and a light-blocking area adjacent to the light-transmitting area, and a light-blocking film disposed under the transparent substrate in the light-blocking area, wherein the transparent substrate has a recess that is at least partially in the light-transmitting area and adjacent to the light-blocking area.