Microlens Coating Structure for Higher-Sensitivity Image Sensors
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Solution Overview
Problem
Current image sensors face challenges in achieving improved sensitivity due to limitations in light collection and pixel separation, leading to reduced image quality and increased noise.
Innovation Solution
The implementation of a multi-layered structure in image sensors, including a first and second coating layer with different densities for the lens coating, and a protective layer with aluminum oxide or hafnium oxide, along with a fence pattern and micro lenses, enhances light concentration and reduces cross-talk between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a single-layer lens coating is used, then the manufacturing process is simple, but light concentration efficiency is insufficient
Solution Approach 1:
The lens coating layer is divided into multiple sub-layers (first lens coating layer, second lens coating layer, third lens coating layer) with different refractive indices and thicknesses. Each sub-layer serves a specific optical function, collectively improving light concentration efficiency while managing the increased structural complexity through systematic design.
Solution Approach 2:
The patent employs composite coating structures combining materials with different optical properties (different refractive indices). This composite approach allows optimization of light transmission and concentration by leveraging the complementary characteristics of each material layer, achieving superior optical performance compared to single-material coatings.
2Measurement precision
If pixels are placed close together to increase pixel density, then the sensor resolution improves, but cross-talk between adjacent pixels increases
Solution Approach 1:
The patent extracts and removes the pixel isolation layer in certain embodiments, relying instead on the precise positioning and optical design of the microlens array and color filter layers to prevent cross-talk. This extraction simplifies the structure while maintaining pixel separation through optimized optical paths and physical spacing in the remaining layers.
Solution Approach 2:
The patent implements localized optical control through individually positioned microlenses and color filters for each pixel. Each pixel region has optimized local optical properties (lens curvature, coating thickness, filter characteristics) that concentrate light precisely onto the corresponding photodetector, preventing light from adjacent pixels from interfering while maintaining high pixel density.
3Reliability
If the protective layer material is changed to aluminum oxide or hafnium oxide, then the sensitivity and reliability improve, but the manufacturing complexity increases
Solution Approach 1:
The patent changes the material parameter of the protective layer from conventional materials to aluminum oxide or hafnium oxide, which offer superior optical clarity, hardness, and chemical stability. This material substitution improves sensor sensitivity and reliability by providing better protection against environmental degradation while maintaining optical performance, despite requiring specialized deposition 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
This configuration improves the sensitivity and reliability of image sensors by effectively concentrating light and minimizing noise, resulting in enhanced image quality and reduced defects during manufacturing.
Implementation Method 1
The photodiode may convert incident light into an electrical signal
Implementation Method 2
micro lenses on the color filters
Data Source
AI summary
An image sensor includes a first substrate including pixel regions, each of the pixel regions including a photoelectric conversion region, color filters on the pixel regions, the color filters on a first surface of the first substrate, micro lenses on the color filters, and a lens coating layer on the micro lenses. The lens coating layer includes a first coating layer and a second coating layer, the second coating layer is on the first coating layer, the first and second coating layers include a same material, and a density of the second coating layer is greater than a density of the first coating layer.