Light Receiving Element With Inter-Pixel Infrared Shielding
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Solution Overview
Problem
Near infrared rays with a wavelength of approximately 940 nm used in indirect ToF schemes have low absorption and quantum efficiency in silicon semiconductor layers, leading to concerns about leakage of incident light to adjacent pixels.
Innovation Solution
A light receiving element with a semiconductor layer and wiring layer that includes photodiodes and transfer transistors, featuring an inter-pixel light shielding unit at the pixel boundary to prevent light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical path length is extended to increase quantum efficiency, then quantum efficiency is improved, but light leakage to adjacent pixels increases
Solution Approach 1:
The patent introduces inter-pixel light shielding units that divide and segment the optical path between adjacent pixels. These shielding units create separate light reception zones for each pixel, preventing cross-talk while maintaining extended optical path length for improved quantum efficiency in indirect ToF schemes
Solution Approach 2:
The patent applies local quality by creating spatially varying optical properties through the inter-pixel light shielding units. Each pixel region has optimized light reception characteristics with localized shielding at boundaries, allowing extended optical path length in pixel centers while preventing light leakage at pixel edges
2Adaptability or versatility
If near infrared rays with wavelength of approximately 940 nm are used, then compatibility with indirect ToF schemes is maintained, but absorption coefficient and quantum efficiency remain low
Solution Approach 1:
The patent employs dynamic charge distribution using transfer transistors that can rapidly switch between different pixel regions. This dynamic control allows the system to maintain compatibility with indirect ToF schemes using 940 nm light while compensating for low quantum efficiency through rapid charge redistribution and accumulation in optimized regions
Solution Approach 2:
The patent changes the operational parameters by implementing rapid voltage modulation to control transfer transistors. This enables dynamic optimization of charge collection efficiency for 940 nm infrared light, maintaining ToF compatibility while improving effective quantum efficiency through timed charge accumulation
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
Enhances quantum efficiency and sensitivity by reducing light leakage between pixels, improving the accuracy of distance measurement.
Implementation Method 1
a semiconductor layer in which photodiodes performing photoelectric conversion of infrared rays are formed in units of pixels
Implementation Method 2
an inter-pixel light shielding unit that shields the infrared rays is formed at a pixel boundary portion of the wiring layer
Data Source
AI summary
The present technology relates to a light receiving element, a distance measurement module, and electronic equipment which are capable of reducing leakage of incident light to adjacent pixels. A light receiving element includes a semiconductor layer in which photodiodes performing photoelectric conversion of infrared rays are formed in units of pixels, and a wiring layer in which a transfer transistor reading charge generated by the photodiodes is formed, and an inter-pixel light shielding unit that shields the infrared rays is formed at a pixel boundary portion of the wiring layer. The present technology can be applied to, for example, a distance measurement module that measures a distance to a subject, and the like.