Unified Image-Depth Pixel Layout With Switchable Transfer Gates
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Solution Overview
Problem
Existing image and depth sensors face challenges due to the structural differences between image pixels and depth pixels, which complicate their joint integration, particularly when both types are implemented on the same semiconductor substrate.
Innovation Solution
A sensor design featuring an array of identical pixels, each comprising a doped semiconductor substrate with specific doping regions and transfer gates, allowing for the acquisition of either color or black-and-white images or depth maps by controlling the transfer gates to switch between integration and readout phases, and operating in rolling shutter mode for images and global shutter mode for depth maps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If image pixels and depth pixels are structurally different to enable their specific functions, then each pixel type can be optimized for its acquisition task, but the joint integration of these differently structured pixels in the same semiconductor substrate causes integration problems and increases device complexity
Solution Approach 1:
The patent implements a universal pixel structure that can function as either an image pixel or a depth pixel depending on the operational mode. Each pixel contains identical photoconversion areas and transfer gates that can be configured through control signals to perform different functions - capturing color image data when image pixels are activated, or capturing depth information when depth pixels are activated. This eliminates the need for structurally different pixel types while maintaining functional optimization for both applications.
2Adaptability or versatility
If different pixel types are used for image and depth acquisition, then functional requirements are met, but manufacturing complexity increases due to the need to integrate and differentiate pixel structures within the same substrate
Solution Approach 1:
The patent segments the pixel array into distinct regions where image pixels and depth pixels are spatially separated but structurally identical. This segmentation allows for simplified manufacturing processes since the same fabrication steps can be applied uniformly across the entire substrate, while the functional differentiation is achieved through control signals rather than structural variations. The vertical insulation structures and transfer gates are uniformly designed and can be manufactured using standard semiconductor processing techniques.
3Ease of manufacture
If all pixels are made identical to simplify integration, then manufacturing complexity is reduced, but the ability to optimize each pixel type for its specific acquisition function is compromised
Solution Approach 1:
The patent introduces dynamic control mechanisms through transfer gates that can be switched between different operational states based on the acquisition mode. During image acquisition, the transfer gates are configured to transfer charge to image readout circuits, while during depth acquisition, they are configured to transfer charge to depth readout circuits. This dynamic reconfiguration allows identical physical structures to perform optimized functions for different acquisition tasks, maintaining both manufacturing simplicity and acquisition efficiency.
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
Enables the creation of a unified image and depth sensor with identical pixels, improving integration efficiency and reducing power consumption by allowing simultaneous illumination for depth map acquisition, while maintaining image quality and depth accuracy.
Implementation Method 1
a first vertical transfer gate surrounding the first region; and at least two assemblies. Each assembly comprises: a second region of the first conductivity type more heavily doped than the substrate, and a second vertical transfer gate arranged opposite a corresponding portion of the first transfer gate
Data Source
AI summary
A sensor includes pixels supported by a substrate doped with a first conductivity type. Each pixel includes a portion of the substrate delimited by a vertical insulation structure with an image sensing assembly and a depth sensing assembly. The image sensing assembly includes a first region of the substrate more heavily doped with the first conductivity type and a first vertical transfer gate completely laterally surrounding the first region. Each of the depth sensing assemblies includes a second region of the substrate more heavily doped with the first conductivity type a second vertical transfer gate opposite a corresponding portion of the first vertical transfer gate. The second region is arranged between the second vertical transfer gate and the corresponding portion of the first vertical transfer gate.