Exposure Mask Translucent Layer for Resist Flatness
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Solution Overview
Problem
Existing exposure masks face challenges in precisely forming chromium layers with desired thicknesses, leading to undesired transmittances and high manufacturing costs, and result in surface irregularities in resist layers due to pattern transfer during photolithographic processes.
Innovation Solution
An exposure mask with a transparent substrate, a light-shielding pattern, and a translucent layer made of chromium oxide, where the translucent layer extends over the light-shielding pattern to create a gradient mask with varying transmittance, preventing pattern transfer to the resist layer and ensuring surface flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a chromium layer is formed with different thicknesses to create gradient transmittance, then the gradient mask function is achieved, but the manufacturing precision and cost are adversely affected
Solution Approach 1:
The exposure mask is divided into multiple regions with different transmittance characteristics by selectively forming light-shielding patterns in specific areas, rather than relying on continuous thickness variation of a single chromium layer. This segmentation approach simplifies the manufacturing process while achieving the desired gradient mask functionality.
Solution Approach 2:
A translucent layer is introduced as an intermediary element between the transparent substrate and the light-shielding pattern. This translucent layer modifies the optical path and enables gradient transmittance control without requiring precise thickness control of the chromium layer itself, thereby reducing manufacturing complexity.
2Adaptability or versatility
If a chromium layer is formed with different thicknesses to create gradient transmittance, then the gradient mask function is achieved, but the manufacturing cost increases
Solution Approach 1:
The mask structure is segmented into distinct functional regions (transparent substrate, translucent layer, light-shielding pattern regions) that can be manufactured using standard photolithography processes. This segmentation avoids the need for complex multi-step chromium deposition with precise thickness control, thereby reducing manufacturing cost.
Solution Approach 2:
The invention uses conventional, readily available materials and processes (standard chromium layers, translucent coatings) rather than requiring expensive specialized equipment or materials for precise thickness control, making the manufacturing process more economical.
3Manufacturing precision
If exposure light is applied through a striped or dotted pattern mask, then the pattern is transferred to the resist layer, but surface irregularities are caused
Solution Approach 1:
The translucent layer serves as an intermediary that diffuses and smooths the light transmission from the striped or dotted light-shielding patterns. This intermediary layer prevents the direct transfer of the pattern to the resist layer while maintaining the gradient transmittance function, thereby preserving resist layer surface flatness.
Solution Approach 2:
The translucent layer is selectively positioned in regions where pattern transfer would cause surface irregularities. By controlling the local optical properties in different areas of the mask, the invention achieves pattern transfer where needed while preventing surface irregularities in critical regions.
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 solution allows for precise formation of a gradient resist film, reducing surface irregularities and lowering manufacturing costs by enabling precise control of transmittance and pattern formation, thereby enhancing the reliability and efficiency of the photolithographic process.
Implementation Method 1
a translucent layer which is formed at a section including a first pattern region having the first pattern portion, which allows exposure light to pass therethrough, and which has a transmittance greater than that of the light-shielding pattern
Implementation Method 2
The exposure mask is used in a photolithographic step of a process for fabricating a thin-film transistor
Data Source
AI summary
An exposure mask includes a transparent substrate; a first pattern portion formed on the transparent substrate using at least one light-shielding pattern having a predetermined shape; and a translucent layer which is formed at a section including a first pattern region having the first pattern portion, which allows exposure light to pass therethrough, and which has a transmittance greater than that of the light-shielding pattern.