Solid-State Image Sensor Trench Layout for Color Balance
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Solution Overview
Problem
Solid-state imaging devices with trench element isolation areas face issues with color balance due to light leakage and wavelength-dependent sensitivity, leading to color shading and mixture, which affects imaging quality.
Innovation Solution
The trench element isolation areas are positioned displaced from the pixel boundaries, with their direction and volume adjusted based on the wavelength of received light, allowing for optimized photoelectric conversion unit sizes and improved light shielding to prevent color imbalance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If trench element isolation areas are formed at pixel boundaries to prevent light leakage, then light shielding between pixels is improved, but color balance deteriorates due to wavelength-dependent sensitivity
Solution Approach 1:
The patent applies asymmetry by intentionally displacing the trench element isolation areas from the pixel boundaries in specific directions. The displacement direction varies depending on the wavelength characteristics of adjacent pixels - trenches are shifted toward pixels with longer wavelength sensitivity and away from pixels with shorter wavelength sensitivity. This asymmetric positioning compensates for wavelength-dependent light leakage patterns, preventing color shading while maintaining effective pixel isolation.
Solution Approach 2:
The patent implements local quality by applying different trench displacement strategies to different spatial locations based on the wavelength characteristics of adjacent pixels. Each trench's displacement direction is locally optimized according to the specific pixel pair it separates, creating non-uniform but wavelength-appropriate isolation across the pixel array. This localized adjustment ensures that each region's color balance is optimized for its specific wavelength composition.
2Object-affected harmful factors
If trench element isolation areas are positioned at pixel boundaries, then light leakage between pixels is reduced, but color shading occurs due to sensitivity differences across the pixel surface
Solution Approach 1:
The patent resolves this contradiction by introducing asymmetric displacement of trenches from pixel boundaries. Instead of uniform positioning, trenches are shifted asymmetrically in directions determined by the wavelength sensitivity profiles of adjacent pixels. This asymmetric arrangement compensates for the non-uniform sensitivity distribution across pixel surfaces, eliminating color shading while maintaining effective prevention of color mixture between adjacent pixels.
3Reliability
If the volume of photoelectric conversion units is increased to improve sensitivity, then light reception capability is enhanced, but light leakage to adjacent pixels increases
Solution Approach 1:
The patent applies segmentation by introducing trench element isolation areas that physically divide and separate the photoelectric conversion units of adjacent pixels. These trenches create distinct isolation regions that prevent optical crosstalk between pixels. By segmenting the pixel array with strategically positioned trenches, the patent enables each pixel to maintain larger photoelectric conversion volume for improved sensitivity while the trenches provide the necessary separation to prevent light leakage to neighboring pixels.
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 color balance and imaging properties by preventing sensitivity shading and color mixture, ensuring accurate color representation without reducing absolute sensitivity.
Implementation Method 1
photoelectric conversion units provided for the respective pixels in the semiconductor layer
Implementation Method 2
a trench element isolation area formed by providing an insulating layer in a trench pattern formed on a light-receiving surface side of the semiconductor layer
Data Source
AI summary
A solid-state imaging device includes a semiconductor layer on which a plurality of pixels are arranged along a light-receiving surface being a main surface of the semiconductor layer, photoelectric conversion units provided for the respective pixels in the semiconductor layer, and a trench element isolation area formed by providing an insulating layer in a trench pattern formed on a light-receiving surface side of the semiconductor layer, the trench element isolation area being provided at a position displaced from a pixel boundary between the pixels.