Integrated CIS Collimator Structure for Infrared Noise Filtering
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Solution Overview
Problem
Contact image sensors (CIS) face challenges in filtering ambient infrared noise effectively due to the use of thick glass filters, resulting in bulky and costly assemblies.
Innovation Solution
A method is developed to integrate a filter function into a collimator structure for CIS, aligning incident light and filtering ambient noise with a compact design and low cost, using a semiconductor device fabrication process that includes a first substrate with optical sensing elements, a dielectric layer, and a second substrate with high impurity doping for light absorption, forming via holes to create a collimator structure that narrows and aligns light while filtering noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a thick glass filter is used to filter ambient infrared noise, then the filtering efficiency is improved, but the device size and cost increase
Solution Approach 1:
The patent combines the collimator structure with the infrared filter function by integrating a doped semiconductor layer into the collimator. This merged structure performs both light collimation and infrared filtering simultaneously, eliminating the need for a separate thick glass filter and reducing overall device volume.
Solution Approach 2:
The collimator structure is designed to serve multiple functions: it collimates incident light onto the sensor array and simultaneously filters ambient infrared noise through the integrated doped semiconductor layer. This multi-functional design reduces the number of components and overall device size.
2Object-affected harmful factors
If a thick glass filter is used to filter ambient infrared noise, then the filtering efficiency is improved, but the manufacturing cost increases
Solution Approach 1:
The filter function is merged into the collimator structure through integration of a doped semiconductor layer, eliminating the need for separate thick glass filter components. This reduces material costs and simplifies the manufacturing process by reducing the number of assembly steps.
Solution Approach 2:
The patent uses high impurity doping concentration (≥1×10^19 atoms/cm³) in the semiconductor layer to achieve infrared filtering through increased free carrier absorption. This parameter change enables filtering functionality without requiring thick glass, reducing material costs and manufacturing complexity.
3Object-affected harmful factors
If a thick glass filter is used, then infrared noise filtering is improved, but the device complexity increases
Solution Approach 1:
The collimator and infrared filter are merged into a single integrated structure with the doped semiconductor layer formed as part of the collimator fabrication process. This eliminates the need for separate filter assembly steps and reduces device complexity.
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 efficient filtering of ambient infrared noise while maintaining a compact and cost-effective design, suitable for use in space-limited applications, reducing the need for thick glass filters and lowering production costs.
Implementation Method 1
the second substrate has a bulk impurity doping concentration equal to or greater than 1×10^19 per cubic centimeter (cm^3) and a first thickness, and wherein the bulk impurity doping concentration and the first thickness of the second substrate are configured so as to allow the optical collimator to filter light in a range of wavelengths
Implementation Method 2
forming via holes to create a collimator structure that narrows and aligns light while filtering noise
Data Source
AI summary
Disclosed is a method to fabricate a multifunctional collimator structure In one embodiment, an optical collimator, includes: a dielectric layer; a substrate; and a plurality of via holes, wherein the dielectric layer is formed over the substrate, wherein the plurality of via holes are configured as an array along a lateral direction of a first surface of the dielectric layer, wherein each of the plurality of via holes extends through the dielectric layer and the substrate from the first surface of the dielectric layer to a second surface of the substrate in a vertical direction, wherein the substrate has a bulk impurity doping concentration equal to or greater than 1×1019 per cubic centimeter (cm−3) and a first thickness, and wherein the bulk impurity doping concentration and the first thickness of the substrate are configured so as to allow the optical collimator to filter light in a range of wavelengths.