Hybrid Deep Trench Isolation for Image Sensor Crosstalk
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Solution Overview
Problem
The miniaturization of image sensors increases the likelihood and magnitude of crosstalk between neighboring photosensitive elements, affecting the accuracy and quality of image capture.
Innovation Solution
The implementation of hybrid deep trench isolation structures, comprising a shallow and deep portion with dielectric and metal regions, electrically and optically isolates photodiodes, reducing both electrical and optical crosstalk by minimizing direct contact and optimizing light absorption and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between neighboring photosensitive elements is decreased to achieve miniaturization, then the image sensor can be made smaller and more integrated, but the likelihood and magnitude of crosstalk between photosensitive elements increases
Solution Approach 1:
The isolation structure is divided into two distinct segments: a shallow trench isolation portion extending from the first surface to a first depth, and a deep trench isolation portion extending from the first surface to a second depth greater than the first depth. This segmentation allows each portion to address different aspects of crosstalk isolation at different depths, effectively reducing electrical and optical interference while maintaining compact sensor dimensions
Solution Approach 2:
Different regions of the isolation structure are assigned different properties: the shallow trench isolation provides primary electrical isolation, while the deep trench isolation provides enhanced optical isolation. This local differentiation of isolation functions allows the structure to simultaneously address both electrical and optical crosstalk issues with targeted effectiveness at different spatial locations and depths
2Object-generated harmful factors
If hybrid deep trench isolation structures are implemented to reduce crosstalk, then electrical and optical isolation between photodiodes is improved, but the device complexity increases
Solution Approach 1:
The shallow trench isolation and deep trench isolation are merged into a single integrated isolation structure that serves both electrical and optical isolation functions. By combining these isolation functions into one unified structure rather than implementing separate independent structures, the patent reduces overall device complexity while maintaining effective crosstalk reduction
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 solution effectively reduces crosstalk between photodiodes, enhancing the accuracy and quality of image capture by maintaining the integrity of image charge generation and minimizing interference, thereby improving the overall performance of image sensors.
Implementation Method 1
a dielectric region disposed between the semiconductor material and the metal region
Implementation Method 2
electrically and optically isolates photodiodes, reducing both electrical and optical crosstalk by minimizing direct contact and optimizing light absorption and reflection
Data Source
AI summary
An image sensor includes a plurality of photodiodes disposed in a semiconductor material between a first side and a second side of the semiconductor material. The image sensor also includes a plurality of hybrid deep trench isolation (DTI) structures disposed in the semiconductor material, where individual photodiodes in the plurality of photodiodes are separated by individual hybrid DTI structures. The individual hybrid DTI structures include a shallow portion that extends from the first side towards the second side of the semiconductor material, and the shallow portion includes a dielectric region and a metal region such that at least part of the dielectric region is disposed between the semiconductor material and the metal region. The hybrid DTI structures also include a deep portion that extends from the shallow portion and is disposed between the shallow portion and the second side of the semiconductor material.