Exposing Device Mask With Uneven Boundaries For Sub-4um Patterning
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Solution Overview
Problem
Conventional exposing devices used in liquid crystal display device fabrication have limited resolving power, making it difficult to form patterns with line widths thinner than 4 μm, leading to defects such as pattern disconnection and line shorts.
Innovation Solution
A mask with a light shielding portion featuring a linear supporting portion and an uneven portion at its boundary, which induces refraction of light, allowing for the formation of patterns with line widths below 4 μm by using a UV beam with a wavelength greater than 300 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional mask with linear light shielding portions is used, then the exposing device can operate with simple mask structure, but the pattern line width cannot be reduced below 4 μm due to limited resolving power
Solution Approach 1:
The patent applies curvature by introducing uneven portions (protrusions or recesses) at the boundaries of the light shielding portions in the mask. This curved/uneven boundary structure refracts the UV light to concentrate it at specific points, enabling the formation of pattern lines thinner than the mask's linear feature size. The uneven boundary creates a focal effect that overcomes the diffraction limit of conventional linear masks.
Solution Approach 2:
The patent changes the physical parameters of the mask by introducing uneven portions with specific geometries (protrusions or recesses) at the light shielding portion boundaries. This modifies the light refraction parameters, allowing the UV beam to be focused into lines thinner than 4 μm despite the mask's overall feature size being larger than the exposing device's resolving power would normally allow.
2Manufacturing precision
If the mask light shielding portion width is reduced to form thinner patterns, then pattern resolution improves, but the exposing device with low resolving power cannot properly expose the photoresist
Solution Approach 1:
The uneven portions at the mask boundaries act as an intermediary optical element that mediates between the UV light source and the photoresist. By introducing these intermediate structural features, the system achieves effective sub-resolution patterning without requiring the exposing device itself to have higher resolving power. The uneven portions serve as the mediating structure that enables the light to form the desired fine patterns.
Solution Approach 2:
The patent changes the optical parameters by using the uneven portions to refract and concentrate the UV light. This parameter change in light distribution allows the photoresist to receive sufficient exposure energy even when the intended pattern line width is below the exposing device's nominal resolving power, ensuring reliable exposure quality.
3Ease of manufacture
If conventional linear light shielding portions are used, then the mask manufacturing is simple, but defects such as pattern disconnection and line shorts occur
Solution Approach 1:
The introduction of uneven portions (curved boundaries) at the light shielding portion edges modifies the light refraction pattern, preventing the formation of defects such as line shorts and pattern disconnections. The curved/uneven boundary creates a more controlled light distribution that avoids the defects associated with sharp linear edges, while still maintaining relatively simple mask manufacturing processes.
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
Enables the formation of micron patterns with line widths as small as 1 μm, improving aperture and reducing defects in liquid crystal display devices, even with exposing devices of low resolving power.
Implementation Method 1
A mask with a light shielding portion featuring a linear supporting portion and an uneven portion at its boundary, which induces refraction of light
Data Source
AI summary
The present invention relates a method for forming a pattern includes the steps of forming a thin film on a substrate, coating a photoresist film on the thin film, aligning a mask over the photoresist film, the mask formed on a base material, including a light shielding portion having a linear supporting portion and an uneven portion at a boundary of the supporting portion, and a transmission portion defined at regions excluding the light shielding portion, exposing the photoresist film with the mask thereon to a UV beam of a wavelength greater than 300nm to cause refraction in the vicinity of the uneven portion, and developing the photoresist film exposed thus to form a photoresist film pattern, and patterning the thin film by using the photoresist film pattern thus formed.