PIN Photodiode Structure for Faster Time-of-Flight Distance Sensing
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Solution Overview
Problem
Conventional 3D image sensors based on time-of-flight distance measuring techniques face challenges in achieving high speed, which affects their accuracy.
Innovation Solution
The use of a PIN diode in the light sensor to enhance the speed of electron movement in photodiodes, thereby improving the accuracy of the time-of-flight distance measuring system by increasing the speed of the light sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photodiodes are used in time-of-flight sensors, then the sensor can detect light and generate images, but the electron movement speed is insufficient which limits measurement accuracy and speed
Solution Approach 1:
The patent changes the electrical parameters of the photodiode by introducing a PIN structure with an intrinsic layer between P-type and N-type regions. This structural parameter change creates a wider depletion region and stronger electric field, which accelerates electron movement speed and improves both the speed and accuracy of time-of-flight distance measurements.
2Measurement precision
If the sensor speed is increased to improve accuracy, then measurement precision improves, but power consumption may increase
Solution Approach 1:
The PIN photodiode structure changes the electrical field distribution parameters to create a more efficient charge carrier generation and collection mechanism. The intrinsic layer reduces recombination losses and improves quantum efficiency, allowing faster electron movement without proportionally increasing power consumption, thus improving accuracy while maintaining reasonable power usage.
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 enhances the accuracy of the time-of-flight distance measuring system by accelerating charge movement in the photodiode, reducing estimated flight time errors and improving measurement precision without significantly increasing power consumption.
Implementation Method 1
uses a PIN diode to increase the speed that electrons move in the photodiodes of the pixels
Implementation Method 2
a pixel comprises a photodiode in a semiconductor substrate... generate a corresponding light sensing signal
Data Source
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AI summary
This application discloses a light sensor (103, 300) and a related time-of-flight distance measuring system (100). The light sensor (103, 300) includes a semiconductor substrate (302), having a first surface (302a) and a second surface (302b); a photodiode (PD), disposed in the semiconductor substrate (302) and adjacent to the first surface (302a), wherein the photodiode (PD) is configured to sense light to generate charges; a first floating diffusion region (FDNI), disposed in the semiconductor substrate (302) and adjacent to the first surface (302a), and configured to collect charges during a sampling operation; a gate (D1), disposed on the semiconductor substrate (302), and configured to selectively control the charges to enter the first floating diffusion region (FDNI); and PIN diode (304), disposed on the photodiode (PD), wherein the PIN diode (304) at least partially overlaps with the photodiode (PD), when viewed from a top view.