Time-of-Flight Demodulation Pixels with Light Directing Elements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current time of flight sensors face limitations in speed and sensitivity due to deep penetration of light into the semiconductor substrate, leading to delayed charge carrier collection and reduced sensitivity.
Innovation Solution
Incorporating demodulation pixels with light directing elements, such as diffraction elements, to direct light and charge carriers near the surface and within the depletion region, along with extending the lateral extent of the charge generation region and creating potential gradients, enhances the speed and sensitivity of the sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is allowed to penetrate deeply into the semiconductor substrate to increase the charge generation volume, then the quantum efficiency is improved, but the charge carrier collection time is delayed and the sensing speed is reduced
Solution Approach 1:
The patent extends the charge generation region laterally (in the plane parallel to the substrate surface) rather than increasing its depth. This dimensional shift allows the light-sensitive area to be enlarged without increasing the penetration depth, thereby maintaining fast charge carrier collection while improving quantum efficiency through increased lateral collection area.
Solution Approach 2:
The charge generation region is segmented into multiple laterally extended zones with different doping concentrations, creating a structured approach to light absorption and charge collection. This segmentation allows optimized charge carrier generation and collection pathways that maintain speed while improving overall quantum efficiency.
2Measurement precision
If the charge generation region is extended laterally to increase the light absorption area, then the quantum efficiency is improved, but the device complexity increases
Solution Approach 1:
Different regions of the laterally extended charge generation structure are doped with different concentrations, creating local variations in electrical properties optimized for specific functions. This allows the complex lateral structure to be managed through localized doping patterns rather than requiring complex three-dimensional architectures.
Solution Approach 2:
The patent varies the doping concentration parameter across different lateral regions of the charge generation structure. By changing this electrical parameter rather than requiring complex geometric variations, the patent achieves functional differentiation while maintaining manufacturing simplicity and reducing overall device complexity.
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 allows for rapid charge carrier sensing, increased sensitivity, and high quantum efficiency by containing light and charge carriers within the depletion region, enabling fast response times and improved image generation in 3D imaging applications.
Implementation Method 1
a charge generation region in the semiconductor substrate, the charge generation region having a lateral extent, the charge generation region being configured to convert light into charge carriers
Implementation Method 2
a light directing element in the charge generation region of the semiconductor substrate, the light directing element being configured to direct light through at least a portion of the lateral extent of the charge generation region
Data Source
AI summary
A time of flight sensor includes at least one demodulation pixel. Each demodulation pixel includes a semiconductor substrate; a charge generation region in the semiconductor substrate, the charge generation region having a lateral extent, the charge generation region being configured to convert light into charge carriers; a light directing element in the charge generation region of the semiconductor substrate, the light directing element being configured to direct light through at least a portion of the lateral extent of the charge generation region; a collection region in the semiconductor substrate, the collection region being configured to collect the charge carriers generated in at least a portion of the lateral extent of the charge generation region, and a readout component in electrical communication with the collection region, the readout component being operable to control an electrical coupling between the charge generation region and the collection region.