Back-Illuminated CMOS Sensor Moisture Diffusion via Porous Antireflection Film
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Solution Overview
Problem
Back-illuminated solid-state imaging devices (BSIs) suffer from image quality degradation due to moisture accumulation between microlenses and antireflection films when exposed to high-temperature, high-humidity conditions, leading to flare, ghosts, and color mixing.
Innovation Solution
Incorporating diffusion holes covered with an inorganic film between microlenses and forming a higher refractive index antireflection film on the microlenses' surfaces, excluding the diffusion holes, to facilitate moisture permeation and reduce surface reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If two inorganic films are provided as antireflection films on the surfaces of the microlenses, then occurrences of flare, ghosts, and color mixing are prevented, but moisture accumulates in the interfaces between microlenses and antireflection film under high-temperature high-humidity conditions, degrading image quality
Solution Approach 1:
The patent introduces a porous layer between the microlens and antireflection film that allows moisture to pass through while maintaining the optical properties of the antireflection film. This porous structure resolves the contradiction by providing a moisture transmission path without compromising the antireflection functionality.
Solution Approach 2:
The patent introduces a porous layer as an intermediary between the microlens and antireflection film. This intermediate layer serves as a mediator that allows moisture to pass through while maintaining the optical properties of the antireflection film, thus resolving the contradiction between preventing moisture accumulation and maintaining antireflection performance.
2Reliability
If a single-layer antireflection film is provided on the microlenses, then moisture can permeate through the film, but surface reflectance is insufficient, causing flare and ghosts
Solution Approach 1:
The patent uses a composite structure consisting of a porous layer and an antireflection film. The porous layer provides moisture permeation while the antireflection film provides low surface reflectance. This composite material approach resolves the contradiction by combining the advantages of both layers.
Solution Approach 2:
The porous layer provides a pathway for moisture to permeate through the antireflection film system while maintaining the optical properties of the antireflection film. This porous structure enables moisture transmission without compromising the antireflection performance.
3Reliability
If the antireflection film has a lower refractive index than the microlenses, then moisture can diffuse through the film, but surface reflectance increases, degrading image quality
Solution Approach 1:
The patent uses a composite structure where the porous layer has lower refractive index (enabling moisture diffusion) and the antireflection film has higher refractive index (reducing surface reflectance). This composite approach resolves the contradiction by separating the moisture diffusion function from the antireflection function.
Solution Approach 2:
The porous layer provides a pathway for moisture to diffuse through the structure. Its lower refractive index facilitates moisture diffusion while the overlying antireflection film with higher refractive index maintains low surface reflectance, resolving the contradiction between moisture diffusion and reflectance control.
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 enhances the resistance of BSIs to high-temperature, high-humidity conditions, preventing image quality degradation by allowing moisture to diffuse through the antireflection film, thus reducing flare, ghosts, and color mixing.
Implementation Method 1
moisture generated in part of the regions of the interfaces between the microlenses and the antireflection film might not permeate through the antireflection film but remain therein
Implementation Method 2
a first antireflection film that is formed on the surfaces of the microlenses excluding the diffusion holes, and has a higher refractive index than that of the microlenses
Data Source
AI summary
The present disclosure relates to a solid-state imaging device that enables diffusion of components in the interfaces between microlenses and an antireflection film, a method of manufacturing the solid-state imaging device, and an electronic apparatus. Moisture permeation holes are formed between the microlenses of adjacent pixels. The moisture permeation holes are covered with an antireflection film. The antireflection film is formed on the surfaces of the microlenses excluding the diffusion holes. The refractive index of the antireflection film is higher than the refractive index of the microlenses. The present disclosure can be applied to complementary metal oxide semiconductor (CMOS) image sensors that are back-illuminated solid-state imaging devices, for example.