UV Pixel δ-Doped Silicon Layer for CMOS Image Sensor Arrays
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Solution Overview
Problem
Conventional CMOS image sensors optimized for visible light spectrum perform poorly in near infrared (NIR) and ultraviolet (UV) wavelengths due to high absorption of shorter wavelength light, leading to reduced charge collection efficiency and increased noise.
Innovation Solution
The implementation of a thin δ-doped silicon layer over UV sub-pixels in the image sensor array, using Metal Organic Chemical Vapor Deposition (MOCVD), enhances UV light detection by generating an electric field that accelerates electrons towards the depletion region, while maintaining performance for visible and NIR wavelengths through selective pixel optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensor is optimized for visible spectrum, then manufacturing cost is reduced, but multi-spectral capability is limited
Solution Approach 1:
The thin layer is deposited during the standard CMOS fabrication process using existing deposition equipment and工艺流程. The deposition is performed as an additional step in the standard manufacturing sequence, utilizing the same cleanroom facilities and equipment already present in conventional sensor production. This preliminary integration into the standard process minimizes additional manufacturing complexity and cost.
Solution Approach 2:
The sensor array is designed to perform multiple spectral detection functions using a single unified structure. By selectively coating only UV pixels with a thin dielectric layer, the same sensor array simultaneously provides UV, visible, and NIR detection capabilities. This multi-functional design eliminates the need for separate sensors for different spectral ranges, reducing overall system complexity and manufacturing cost.
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 significantly improves the quantum efficiency and reduces leakage current for UV pixels, enabling high-performance UV light detection without degrading visible or NIR light performance, suitable for applications like biometric identification and materials scanning.
Implementation Method 1
The thin layer is charged to generate an electric field that accelerates electrons towards the depletion region for collection
Implementation Method 2
A camera includes a subset of its pixels optimized for UV light sensitivity... to enhance the detection of UV light in that subpixel
Data Source
AI summary
Per-pixel performance is improved in a combined visible and ultraviolet image sensor array such as for a hyperspectral camera. In one example, an array of photodetectors is formed on a silicon substrate. A subset of the photodetectors are improved to improve sensitivity to ultraviolet light, and the photodetector array is finished to form an image sensor.