Image Sensor Isolation Structure for Crosstalk Reduction
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Solution Overview
Problem
Image sensors face challenges with crosstalk between pixels, leading to increased noise and reduced signal quality due to inadequate isolation structures.
Innovation Solution
The implementation of a trench isolation structure comprising multiple dielectric layers and a dielectric post, formed in a grid pattern on a semiconductor substrate, which enhances the depth and isolation performance by using high-k materials and specific deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional isolation structure is used, then the manufacturing process is simple, but crosstalk between pixels increases and signal quality deteriorates
Solution Approach 1:
The isolation structure is divided into multiple dielectric layers (first dielectric layer, second dielectric layer, third dielectric layer) with different materials and functions. Each layer segments the isolation task, with lower layers providing mechanical support and upper layers providing optical isolation, thereby reducing crosstalk while maintaining manufacturability
Solution Approach 2:
The patent employs composite dielectric materials with different properties in different layers. The first dielectric layer uses a material with lower refractive index, while the second and third layers use materials with higher refractive indices. This composite structure optimizes both optical isolation performance and mechanical stability
2Reliability
If the isolation structure depth is increased to reduce crosstalk, then optical confinement improves, but manufacturing difficulty increases
Solution Approach 1:
Instead of simply increasing the depth of a single-layer isolation structure, the patent transitions to a multi-layer horizontal segmentation approach. The optical isolation function is achieved through the stacking of multiple layers with different refractive indices, converting a vertical depth problem into a layered compositional solution that is easier to manufacture
Solution Approach 2:
The isolation structure employs a nested configuration where the first dielectric layer is positioned at the bottom, the second dielectric layer is nested above it, and the third dielectric layer is nested at the top. This nested arrangement allows each layer to contribute to optical confinement without requiring excessive total depth, thereby improving manufacturability
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 significantly reduces crosstalk and noise, improving the signal-to-noise ratio and overall image quality by providing better optical confinement and isolation between pixels.
Implementation Method 1
providing better optical confinement and isolation between pixels
Data Source
AI summary
A device including a semiconductive substrate having opposite first and second surfaces, a light-sensitive element in the semiconductive substrate, an isolation structure extending at least from the second surface of the semiconductive substrate to within the semiconductive substrate, and a color filter over the second surface of the semiconductive substrate. The isolation structure includes a dielectric fill and a first high-k dielectric layer wrapping around the dielectric fill.