Back-Illuminated Image Sensor Grooves With Fixed-Charge Void Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Back-illuminated solid-state imaging devices face challenges in reducing optical color mixing due to insufficient reflection characteristics in groove portions between photoelectric conversion elements, leading to light transmission and color mixing issues.
Innovation Solution
Incorporating a fixed charge film containing hafnium, aluminum, zirconium, tantalum, or titanium on the sidewall and bottom surfaces of groove portions, with some open ends closed by the film to create a void inside, enhancing reflection characteristics and reducing optical color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If groove portions are provided between adjacent photoelectric conversion portions to reduce optical color mixing, then optical color mixing is reduced, but reflection characteristics remain insufficient leading to light transmission issues
Solution Approach 1:
The patent changes the physical and chemical parameters of the groove portion by forming a fixed charge film containing specific elements (hafnium, aluminum, zirconium, tantalum, or titanium) with controlled thickness (1 nm to 10 nm). This modifies the refractive index and electrical properties of the groove region, enhancing reflection characteristics while maintaining optical isolation between adjacent photoelectric conversion portions.
Solution Approach 2:
The patent creates a composite structure by combining the fixed charge film with the substrate and groove portion. The fixed charge film contains specific metal elements that provide both electrical fixed charge properties and optical reflection properties, creating a multi-functional composite material that addresses both optical color mixing and reflection characteristics simultaneously.
2Object-affected harmful factors
If insulation film is embedded without void in groove portions to reduce optical color mixing, then optical color mixing is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent intentionally introduces a void (porous structure) within the fixed charge film in the groove portion. This void structure simplifies the manufacturing process by eliminating the need for complete insulation film embedding while still providing sufficient optical isolation. The void acts as an optical barrier without requiring complex multi-layer insulation structures.
3Reliability
If fixed charge film covers sidewall and bottom surfaces of groove portions, then signal charge isolation is improved, but optical color mixing reduction is insufficient without void structure
Solution Approach 1:
The patent segments the fixed charge film structure by creating a void within the film in the groove portion. This segmentation divides the film into regions that can perform different functions: the film portions covering the sidewall and bottom surfaces provide signal charge isolation, while the void structure provides enhanced optical isolation by creating an optical barrier with different refractive index properties.
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 effectively curbs optical color mixing by increasing reflection in the groove portions and improving signal charge isolation, leading to enhanced image quality and reduced blooming in solid-state imaging devices.
Implementation Method 1
The fixed charge film covers a sidewall surface and a bottom surface of the groove portions... effectively curbs optical color mixing by increasing reflection in the groove portions
Data Source
AI summary
Groove portions are provided between adjacent photoelectric conversion portions, and sidewall surfaces and bottom surfaces of the groove portions are covered with a first fixed charge film, and open ends of the groove portions are closed by a second fixed charge film with voids inside of the groove portions.