Ribbed Substrate Roughness Control for Optical Noise Suppression
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Solution Overview
Problem
Optical semiconductor devices face issues with optical noise generation, such as flares and ghosts, due to intense light incidence, which affects imaging characteristics as they are required to be smaller and higher definition.
Innovation Solution
A ribbed substrate with a transparent substrate and a rib member formed in a frame shape, featuring specific roughness and skewness values, and a photosensitive composition with controlled filler content, is used to diffuse stray light and reduce optical noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional smooth rib member is used, then the manufacturing process is simple, but optical noise (flares and ghosts) is generated when intense light is incident
Solution Approach 1:
The rib member is designed with non-uniform surface roughness: the inner peripheral surface has controlled roughness (Ra: 50-3000 nm) to diffuse stray light and reduce optical noise, while other surfaces maintain standard smoothness for manufacturing simplicity. This localized application of surface treatment resolves the contradiction between optical performance and manufacturing complexity.
Solution Approach 2:
The invention changes the surface roughness parameter of the rib member from a conventional smooth finish to a controlled roughness range (Ra: 50-3000 nm, preferably 200-900 nm). This parameter modification enables effective stray light diffusion to suppress optical noise while maintaining manufacturing feasibility through standard photosensitive composition formulation and processing.
2Object-affected harmful factors
If the rib member surface is made very rough to diffuse light, then optical noise is suppressed, but manufacturing precision and pattern accuracy deteriorate
Solution Approach 1:
The invention optimizes the surface roughness parameter within a specific range (Ra: 50-3000 nm, preferably 200-900 nm) that balances optical noise suppression with manufacturing precision. This controlled parameter range ensures sufficient light diffusion while maintaining pattern accuracy achievable through standard photolithography processes.
Solution Approach 2:
Surface roughness is applied selectively only to the inner peripheral surface of the rib member where stray light diffusion is most critical, while other surfaces remain smooth for precise pattern formation. This localized approach concentrates the optical benefit without compromising overall manufacturing precision.
3Object-affected harmful factors
If a photosensitive composition with high filler content is used to increase roughness, then optical noise is reduced, but the composition becomes difficult to process and pattern
Solution Approach 1:
The invention controls the filler content parameter at 30 wt% or less in the photosensitive composition, which generates sufficient surface roughness (Ra: 50-3000 nm) for optical noise suppression while maintaining the composition's processability. This optimized filler concentration ensures the paste remains workable during screen printing and curing operations.
Solution Approach 2:
The photosensitive composition is formulated as a composite material with carefully selected filler content (≤30 wt%) that provides the necessary surface roughness for optical performance while maintaining compatibility with standard photolithography processing. The composite structure balances optical functionality with manufacturing ease.
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 ribbed substrate effectively suppresses optical noise by diffusing stray light, maintaining imaging quality and reliability in high-definition optical semiconductor devices.
Implementation Method 1
an arithmetic mean roughness Ra of an inner peripheral surface of the rib member is 50 nm or more and 3,000 nm or less
Data Source
AI summary
A ribbed substrate includes a transparent substrate and a rib member provided on one principal surface of the transparent substrate. The rib member is formed in a frame shape. An arithmetic mean roughness of an inner peripheral surface of the rib member is 50 nm or more and 3,000 nm or less. A value of a skewness of the inner peripheral surface of the rib member is preferably negative. The arithmetic mean roughness of the inner peripheral surface of the rib member is preferably 200 nm or more and 900 nm or less.