Back-Illuminated Image Sensor Groove Films for Color Mixing Isolation
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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 the film leaving a void inside, to enhance reflection and electrical isolation between adjacent photoelectric conversion elements.
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 in the groove portions are insufficient leading to light transmission and color mixing issues
Solution Approach 1:
The patent changes the material parameter of the groove portion by forming a fixed charge film containing high-refractive-index materials (hafnium, aluminum, zirconium, tantalum, or titanium). This material substitution increases the reflection characteristics in the groove portions, preventing light transmission and optical color mixing while maintaining the groove structure's isolating function.
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 inside the groove portion by controlling the fixed charge film formation process. This void structure simplifies manufacturing compared to completely filling the groove with insulation film, while still providing sufficient optical isolation. The fixed charge film with void maintains reflection characteristics without requiring complex multi-layer insulation film embedding.
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 reduces optical color mixing by increasing reflection characteristics in the groove portions and preventing signal charge leakage, thereby improving image quality and reducing blooming effects.
Implementation Method 1
The solution effectively reduces optical color mixing by increasing reflection characteristics in the groove portions
Implementation Method 2
a fixed charge film which covers a sidewall surface and a bottom surface of the groove portions, and a light reception surface side of the substrate and which contains at least one of hafnium, aluminum, zirconium, tantalum, and titanium
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.