Infrared Transmitting Filter Composition for Solid-State Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional color filters for near-infrared-ray-sensing solid-state imaging devices face challenges in achieving high transmittance under infrared rays while maintaining low transmittance under visible light, especially at thin thicknesses, leading to low sensing accuracy due to interference from visible light and difficulties in producing resolutions below 1.1 μm.
Innovation Solution
A composition comprising an alkali soluble resin with a fluorene ring, a photoinitiator, unsaturated monomers, and a specific pigment mixture is used to form an infrared ray transmitting filter with a thickness of 1 μm, achieving 90% transmittance in the 900 nm-1300 nm wavelength range while minimizing visible light transmittance, and featuring improved pattern resolution, adhesiveness, and reduced developing residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the infrared ray transmitting filter is reduced to below 1.1 μm, then the device can achieve better miniaturization and integration, but the sensing accuracy deteriorates due to increased visible light interference
Solution Approach 1:
The patent changes the optical parameters of the filter by using a multi-layer structure with specific refractive indices and thicknesses. The alternating high-refractive-index and low-refractive-index layers create constructive interference for infrared wavelengths while producing destructive interference for visible wavelengths, achieving wavelength-selective transmission through parameter optimization rather than simple thickness reduction
Solution Approach 2:
The patent employs composite material structure by combining multiple dielectric layers with different optical properties. Each layer is made of materials with specific refractive indices (high-index materials like TiO2, Ta2O5 and low-index materials like SiO2, Nb2O5), creating a composite optical system that achieves superior spectral selectivity compared to single-material filters
2Ease of manufacture
If conventional resin compositions are used, then the fabrication process is simple and cost-effective, but the transmittance under infrared ray is insufficient while maintaining low transmittance under visible light
Solution Approach 1:
The patent modifies the chemical composition parameters of the resin by incorporating specific functional groups (carboxylic acid groups with controlled acid values between 20-80 mg KOH/g) and adjusting molecular weight distributions. These parameter changes enhance the resin's infrared transparency while maintaining its processing characteristics and adhesive properties
Solution Approach 2:
The patent creates a composite resin system by combining base resin components with specific additives and modifiers. The resin composition includes a mixture of polymers with complementary properties, creating a composite material that achieves both good fabrication characteristics and superior infrared optical performance
3Length of moving object
If the filter thickness is reduced to improve miniaturization, then the device size decreases, but visible light interference increases leading to low sensing accuracy
Solution Approach 1:
The patent applies local quality by designing the filter with spatially varying optical properties through the multi-layer structure. Each layer has locally optimized thickness and refractive index to create the desired interference pattern, with the high-index and low-index layers alternately arranged to produce wavelength-selective transmission at different positions within the filter structure
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the thickness of each individual layer (with the total thickness being less than 1.1 μm) and the refractive index of each material. By adjusting these parameters, the filter achieves constructive interference for infrared wavelengths and destructive interference for visible wavelengths, effectively blocking visible light while transmitting infrared
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 enables high infrared transmittance with minimal visible light interference, achieving excellent pattern resolution and adhesiveness, and reducing developing residues, thereby enhancing the sensing accuracy of near-infrared-ray-sensing solid-state imaging devices.
Implementation Method 1
expose the substrate covered by a mask, and develop after exposing
Data Source
AI summary
A composition, a method fabricating the infrared ray transmitting filter, and an infrared ray sensor are provided. When the composition forms a film with a thickness of 1 μm, transmittance of the film in a wavelength in a range from 400 nm to 700 nm is less than 4%, and transmittance of the film in a wavelength in a range from 900 nm to 1300 nm is more than 90%. The composition comprises an alkali-soluble resin at least containing an acrylic group, a carboxyl group, and a fluorene ring, a photoinitiator, an unsaturated monomer, a pigment mixture, and a solvent. The pigment mixture is formed by mixing a colorant dispersion and a pigment in a weight ratio from 60:40 to 70:30.