Reflective Image Sensor Structure for Crosstalk and Quantum Efficiency
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Solution Overview
Problem
The challenge in the semiconductor industry is to form reliable semiconductor devices, such as image sensors, at increasingly smaller sizes, where feature sizes continue to decrease, making fabrication processes more difficult and complex.
Innovation Solution
The process involves forming a semiconductor substrate with isolation structures, light-sensing regions, and a reflective structure in trenches to reduce optical reflection and improve quantum efficiency, including a protection layer to neutralize surface charges and an insulating layer to isolate light-sensing regions, with a reflective layer to prevent crosstalk and enhance light detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes are decreased to increase functional density, then productivity and production efficiency are improved, but fabrication process difficulty and manufacturing precision requirements increase
Solution Approach 1:
The device is divided into multiple light-sensing regions separated by isolation structures. This segmentation allows each region to be independently formed and controlled, reducing the overall manufacturing difficulty while maintaining high functional density through compact arrangement of multiple small regions.
Solution Approach 2:
Different regions of the semiconductor substrate are given different properties through selective doping and isolation structures. The light-sensing regions have specific electrical characteristics while the isolation regions provide electrical separation, allowing optimized performance in each local area without compromising the entire device.
2Productivity
If light-sensing regions are placed closer together to increase functional density, then productivity is improved, but optical crosstalk between regions increases
Solution Approach 1:
Isolation structures are introduced to extract and remove the harmful optical crosstalk between adjacent light-sensing regions. These structures physically separate the optical paths and electrical signals, eliminating the interference that would otherwise occur when regions are placed close together for high density.
Solution Approach 2:
The isolation structures serve as intermediary elements between adjacent light-sensing regions. They provide both optical isolation to prevent light leakage between regions and electrical isolation to prevent signal crosstalk, enabling high functional density without compromising signal integrity.
3Reliability
If reflective structures are added to reduce optical reflection and improve quantum efficiency, then light detection efficiency is improved, but device complexity increases
Solution Approach 1:
The reflective structure is merged with the isolation structures, combining multiple functions into a single integrated component. The reflective layer is positioned within or adjacent to the isolation regions, simultaneously providing optical reflection to improve quantum efficiency and maintaining electrical isolation between light-sensing regions, thereby reducing overall device complexity.
Solution Approach 2:
The isolation structures are designed to perform multiple functions: electrical isolation between regions, optical reflection to improve quantum efficiency, and structural support. This multi-functionality reduces the need for separate components, simplifying the overall device architecture while achieving high performance.
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 approach improves the quantum efficiency of image sensors by reducing optical reflection and crosstalk between light-sensing regions, allowing for more efficient light detection and processing at smaller scales.
Implementation Method 1
a protection layer to neutralize surface charges
Implementation Method 2
a reflective structure in trenches between the light-sensing regions to reflect incident light arriving at the reflective structure
Implementation Method 3
an insulating layer covering the back surface and extending into the semiconductor substrate, wherein the insulating layer surrounds the light-sensing region
Data Source
AI summary
An image sensor device is provided. The image sensor device includes a semiconductor substrate having a front surface, a back surface opposite to the front surface, and a light-sensing region close to the front surface. The image sensor device includes an insulating layer covering the back surface and extending into the semiconductor substrate. The protection layer has a first refractive index, and the first refractive index is less than a second refractive index of the semiconductor substrate and greater than a third refractive index of the insulating layer, and the protection layer conformally and continuously covers the back surface and extends into the semiconductor substrate. The image sensor device includes a reflective structure surrounded by insulating layer in the semiconductor substrate.