Pixel Isolation Structure for Small-Pixel Image Signal Reliability
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Solution Overview
Problem
Current image sensors face challenges in maintaining reliability and performance due to the decreasing size of pixels and components, which affects the quality of image signals.
Innovation Solution
The image sensor design incorporates a substrate with unit pixel regions defined by a lattice-shaped pixel isolation trench, featuring a dielectric layer, semiconductor patterns, and buried insulating layers, with doped regions on the outer walls of the pixel isolation trench to enhance pixel isolation and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of pixels and components is decreased to increase integration, then the degree of integration is improved, but the reliability and image signal quality deteriorate
Solution Approach 1:
The patent applies local quality by creating a doped region specifically at the outer wall of the pixel isolation structure where charge accumulation occurs. This localized doping with a first dopant (opposite polarity to the photoelectric conversion element) addresses the specific problem of charge leakage at the isolation interface without requiring changes to the entire pixel structure, thus improving reliability while maintaining small pixel size
Solution Approach 2:
The patent implements preliminary action by forming the doped region in advance within the pixel isolation structure before final pixel operation. The doped region is pre-configured to prevent charge leakage and improve isolation effectiveness, ensuring reliable performance from the outset rather than attempting to correct issues after pixel miniaturization causes problems
2Ease of manufacture
If the pixel isolation structure is simplified, then the manufacturing process is easier, but the pixel isolation effectiveness and uniformity deteriorate
Solution Approach 1:
The patent applies segmentation by dividing the pixel isolation structure into distinct functional layers: a pixel isolation trench, a pixel isolation structure within the trench, and a doped region at the outer wall. This segmented approach allows each component to be optimized independently - the trench provides physical separation, the isolation structure provides electrical insulation, and the doped region provides charge management - achieving uniform isolation without overly complex manufacturing
Solution Approach 2:
The patent uses parameter changes by introducing doping concentration as a key parameter to control the electrical properties of the pixel isolation structure. By adjusting the dopant type and concentration in the doped region, the patent optimizes charge accumulation and isolation effectiveness, achieving uniform pixel isolation through controlled material properties rather than complex geometric arrangements
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 design improves the reliability and performance of image sensors by maintaining uniform doping concentration and effective pixel isolation, leading to improved image signal quality.
Implementation Method 1
a doped region on an outer wall of the pixel isolation structure, and the doped region includes the first dopant
Implementation Method 2
each pixel outputs an image signal from light energy. Each of the plurality of pixels accumulates photocharges corresponding to the amount of light incident through a photoelectric conversion element
Data Source
AI summary
An image sensor may include a substrate; a unit pixel region including a photoelectric conversion region; a pixel isolation trench defining the unit pixel region, and extending in a first and a second horizontal direction; and a pixel isolation structure in the pixel isolation trench, wherein the pixel isolation structure includes a dielectric layer on an inner wall of the pixel isolation trench; a first semiconductor pattern on the dielectric layer and including a first dopant; a first insulating layer on a first portion of the first semiconductor pattern overlapping the photoelectric conversion region; a second semiconductor pattern on a second portion of the first semiconductor pattern not overlapping with the photoelectric conversion region, wherein the photoelectric conversion region includes a doped region on an outer wall of the pixel isolation structure, and the doped region includes the first dopant.