Avalanche Ranging Pixel Layout for Sensitivity Without Crosstalk
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Solution Overview
Problem
Existing ranging image sensors face challenges in improving light receiving sensitivity while maintaining signal reading accuracy.
Innovation Solution
The ranging image sensor incorporates a semiconductor layer with specific conductive type regions and electrodes, including avalanche multiplication regions, charge distribution regions, and transfer gate electrodes, designed to prevent depletion layers from reaching well regions, thereby enhancing light sensitivity and reducing crosstalk between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the avalanche multiplication region is formed to overlap the well region in the thickness direction to improve light receiving sensitivity, then the light receiving sensitivity is improved, but the depletion layer reaches the well region causing current flow and reducing signal reading accuracy
Solution Approach 1:
The patent changes the spatial arrangement from three-dimensional overlap to two-dimensional separation. The avalanche multiplication region and well region are positioned adjacent to each other in the planar direction rather than overlapping in the thickness direction, eliminating depletion layer penetration while preserving light receiving sensitivity through proper regional design
Solution Approach 2:
The charge distribution region serves as an intermediary structure between the avalanche multiplication region and the well region. This intermediate layer prevents direct contact and depletion layer penetration while facilitating charge collection and transfer, thus maintaining signal reading accuracy while allowing the avalanche region to be positioned for optimal light sensitivity
2Illumination intensity
If the avalanche multiplication region is formed to overlap the charge distribution region to improve light receiving sensitivity, then the light receiving sensitivity is improved, but crosstalk between pixels occurs
Solution Approach 1:
The patent divides the pixel structure into distinct segmented regions: avalanche multiplication region, charge distribution region, and well region, each with specific functions. The avalanche multiplication region is positioned to overlap the charge distribution region for sensitivity enhancement, while the well region is separately positioned to handle charge collection, thereby preventing crosstalk through functional segmentation
Solution Approach 2:
The charge distribution region acts as an intermediary layer that receives and manages charges from the avalanche multiplication region. This intermediate structure prevents direct interaction between adjacent pixels' well regions, thereby eliminating crosstalk while allowing the avalanche region to overlap the charge distribution region for improved light sensitivity
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 light receiving sensitivity while maintaining signal reading accuracy and preventing crosstalk, allowing for more accurate distance imaging.
Implementation Method 1
an avalanche multiplication region including a first conductive type first multiplication region formed in the semiconductor layer and a second conductive type second multiplication region formed on the first side of the first multiplication region
Data Source
AI summary
In a ranging image sensor, each pixel includes an avalanche multiplication region, a charge distribution region, a pair of first charge transfer regions, a pair of second charge transfer regions, a well region, a photogate electrode, a pair of first transfer gate electrodes, and a pair of second transfer gate electrodes. The first multiplication region of the avalanche multiplication region is formed so as to overlap the charge distribution region and so as not to overlap the well region in the Z direction. The second multiplication region of the avalanche multiplication region is formed so as to overlap the charge distribution region and the well region in the Z direction.