Photomask Production via Single-Step Resist Dose Variation
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Solution Overview
Problem
Current methods for producing photomasks require multiple lithography steps to form fine-line patterns, leading to prolonged production times and potential foreign matter issues due to repeated resist film usage.
Innovation Solution
A method involving a single photolithography step where a resist film is irradiated with different doses to form transfer and frame patterns, allowing for etching of light-shielding and halftone films with varying resistances, thereby forming a photomask efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple lithography steps are used to form transfer pattern and frame pattern separately, then the photomask can be produced with proper pattern formation, but the production time is prolonged and foreign matter issues occur due to repeated resist film usage
Solution Approach 1:
The patent combines the formation of transfer pattern and frame pattern into a single lithography step by using a single resist film layer. The resist film is exposed to different doses of light in different regions, allowing both patterns to be formed simultaneously without requiring multiple lithography steps, thus reducing production time and eliminating foreign matter contamination from repeated resist film application
Solution Approach 2:
The patent applies local quality by irradiating different regions of the same resist film with different light doses. The first region (transfer pattern area) receives a first dose that makes it removable, while the second region (frame pattern area) receives a second dose that makes it remain after development. This spatial variation in exposure dose enables differential pattern formation within a single lithography step
2Manufacturing precision
If multiple lithography steps are used to form transfer pattern and frame pattern separately, then the photomask can be produced with proper pattern formation, but the process complexity increases
Solution Approach 1:
The patent merges multiple lithography processes into a single step by using selective light dose irradiation on a single resist film. This eliminates the need for multiple resist film applications, developments, and etching steps, thereby simplifying the overall manufacturing process while maintaining the ability to form both transfer and frame patterns with high precision
Solution Approach 2:
The patent changes the exposure dose parameter spatially across the resist film to achieve different pattern outcomes. By controlling the light dose (first dose vs. second dose) in different regions, the same resist film exhibits different developability characteristics, enabling complex pattern formation through a simplified single-step process
3Manufacturing precision
If repeated resist film usage is performed in multiple lithography steps, then proper pattern formation can be achieved, but foreign matter contamination occurs
Solution Approach 1:
The patent eliminates foreign matter contamination by combining all pattern formation operations into a single lithography step using one resist film. Since the resist film is applied only once and then selectively removed or retained in different regions through differential light dosing, there is no repeated handling or application of resist film that could introduce foreign matter contamination
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 reduces production time and minimizes foreign matter by enabling the formation of transfer and frame patterns with distinct etch resistances in a single photolithography step, enhancing the efficiency of photomask production.
Implementation Method 1
a resist film is irradiated with different doses to form transfer and frame patterns
Implementation Method 2
etching the light-shielding film using the mask pattern and the mask frame pattern as etch mask
Data Source
AI summary
A method for manufacturing a photomask includes obtaining a substrate on which a halftone film, a light-shielding film, and a resist film are stacked, irradiating a first region of the resist film at a first dose and a second region of the resist film that surrounds the first region at a second dose greater than the first dose, developing the resist film in the first region to form a mask pattern while leaving the resist film in the second region to form a mask frame pattern, and then patterning the light-shielding film using the mask pattern formed in the resist film.