Semiconductor Range-Finding Element Background Charge Exhaustion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current time-of-flight (TOF) range-finding sensors face challenges in reducing the influence of background light, leading to decreased range measurement precision and dynamic range due to shot noise caused by background charges.
Innovation Solution
A semiconductor range-finding element with a semiconductor photoelectric conversion element, transfer gate electrodes, floating drain regions, and exhausting gate electrodes is designed to alternately transfer signal and background charges, using insulating films to control potentials and effectively remove background charges, thereby enhancing range measurement precision and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If background light is present in the signal, then the sensor can detect more light photons, but shot noise from background charges causes drop in range measurement precision
Solution Approach 1:
The patent segments the charge accumulation function by providing separate floating drain regions for signal charges and background charges. The photoelectric conversion element is divided into regions that can independently transfer signal charges and background charges to different accumulation areas, allowing precise measurement of signal charges without background noise interference.
Solution Approach 2:
The patent extracts background charges from the signal path by providing a dedicated background charge accumulation region separate from the signal charge accumulation region. This extraction is achieved through separate transfer gate electrodes that can independently move background charges away from the signal measurement path, eliminating shot noise from range measurements.
2Quantity of substance
If background charges are present in the floating drain region, then more charges are available for measurement, but dynamic range decreases due to noise
Solution Approach 1:
The patent segments the floating drain structure into multiple independent regions: signal charge accumulation regions and background charge accumulation regions. This segmentation allows each region to be optimized for its specific function without interference, maintaining high dynamic range for signal detection while separately handling background charges.
Solution Approach 2:
The patent extracts background charges from the signal measurement path by providing separate transfer mechanisms and accumulation regions. This extraction prevents background charges from occupying signal charge capacity and introduces shot noise, thereby preserving dynamic range for actual signal measurements.
3Device complexity
If the same semiconductor region is used for both signal and background charge transfer, then device complexity is reduced, but charge transfer control becomes difficult
Solution Approach 1:
The patent segments the charge transfer control by providing separate transfer gate electrodes for signal charges and background charges, even though they operate on the same semiconductor region. This segmentation allows independent control of each charge type through dedicated gate electrodes, simplifying the control logic while maintaining structural efficiency.
Solution Approach 2:
The patent merges the signal and background charge transfer paths by using the same semiconductor region for both, reducing device complexity. The merging is made operable through separate transfer gate electrodes that can independently control charge movement, combining structural simplicity with operational independence.
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
The solution effectively suppresses the influence of background light, achieving high range measurement precision, wide dynamic range, and maximum range measurement coverage by maximizing the capacity of floating drain regions for signal charges.
Implementation Method 1
a semiconductor photoelectric conversion element configured to receive an optical pulse, which is reflected by a target sample, as an optical signal, and configured to convert into signal charges in a charge generation region
Implementation Method 2
first and second transfer gate electrodes configured to electrostatically control potentials of first and second transfer channels implemented by a same semiconductor region as the charge generation region through insulating films formed on the first and second transfer channels
Data Source
AI summary
To transfer signal charges generated by a semiconductor photoelectric conversion element in opposite directions, the center line of a first transfer gate electrode and that of a second transfer gate electrodes are arranged on the same straight line, and a U-shaped first exhausting gate electrode and a second exhausting gate electrode are arranged to oppose to each other. The first exhausting gate electrode exhausts background charges generated by a background light in the charge generation region, and the second exhausting gate electrode exhausts background charges generated by the background light in the charge generation region. The background charges exhausted by the first exhausting gate electrode are received by a first exhausting drain region and the background charges exhausted by the second exhausting gate electrode are received by a first exhausting drain region.