Flexible Photomask with Microstructures for Contact Lithography
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Solution Overview
Problem
Conventional photolithography methods face issues with photomask durability, dimension errors due to uneven substrates, and inability to create high aspect ratio photoresist structures due to direct contact and light scattering, leading to shortened photomask lifespan and precision issues.
Innovation Solution
A photomask manufacturing method using a flexible substrate with microstructures and a single-layer shading material, such as polyurethane acrylate or carbon black photoresist, which is coated and solidified, and optionally patterned using a thermoplastic macromolecule sheet to improve tightness and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contact photolithography is used with direct contact between photomask and photoresist layer, then manufacturing cost is reduced and manufacturing speed is increased, but photomask lifespan is shortened due to damage from rubbing and the ability to create high aspect ratio structures is lost due to light scattering
Solution Approach 1:
The patent uses a flexible substrate with microstructures that can conform to the photoresist layer surface, maintaining contact while reducing mechanical stress and damage to the photomask during rubbing, thereby extending photomask lifespan while preserving contact lithography benefits
Solution Approach 2:
The photomask is segmented into multiple microstructures rather than a continuous rigid structure, allowing localized adaptation to surface variations and reducing stress concentration that would otherwise lead to photomask damage and shortened lifespan
2Productivity
If contact photolithography is used with direct contact between photomask and photoresist layer, then manufacturing cost is reduced and manufacturing speed is increased, but manufacturing precision deteriorates due to dimension errors from light scattering and diffraction
Solution Approach 1:
The flexible substrate conformally contacts the photoresist layer surface, eliminating gaps and air interfaces that cause light scattering and diffraction, thereby maintaining exposure precision while enabling contact lithography's high productivity
Solution Approach 2:
The microstructures on the flexible substrate are designed with curved surfaces that conform to the photoresist layer, eliminating flat-interface light scattering and improving exposure precision by ensuring optimal optical contact
3Strength
If conventional metal layer is used as shading material, then photomask structural integrity is maintained, but manufacturing cost increases, manufacturing process time increases, and operating temperature increases
Solution Approach 1:
The patent uses a flexible substrate with microstructures that can be easily manufactured and replaced, substituting expensive metal layers with lower-cost materials that achieve the same functional purpose, thereby reducing manufacturing cost and process time
Solution Approach 2:
The invention changes the material parameters from conventional metal layers to flexible polymer-based substrates, which can be processed at lower temperatures and faster rates, improving manufacturing productivity while maintaining sufficient structural integrity for the application
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 method reduces manufacturing costs and time, lowers operating temperatures, enhances layer uniformity, and improves the precision and tightness between the photomask and semiconductor substrate, enabling more accurate exposure and development.
Implementation Method 1
utilizing the flexible substrate further results in that the tightness between the photomask and the semiconductor substrate becomes higher
Implementation Method 2
the shading material is formed on the substrate by spin coating
Implementation Method 3
because the shading material is a solution, the layer uniformity of the shading layer is improved
Implementation Method 4
In conventional photolithography, utilizing the photomask to proceed with the ultraviolet (UV) exposure on the photoresist layer
Implementation Method 5
the exposure on the photoresist is carried out by the projection provided by an optical system
Data Source
AI summary
A method for manufacturing a photomask is provided. The method includes providing a flexible substrate, forming a plurality of microstructures on the flexible substrate, coating the flexible substrate with a shading material to form a shading layer on the substrate, and solidifying the shading layer which is a single layer.