CAPD ToF Pixel Separation Structure for Light Leakage Reduction
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Solution Overview
Problem
Conventional CAPD type indirect ToF sensors suffer from insufficient pixel separation, leading to light leakage and color mixing, which deteriorates distance measurement accuracy.
Innovation Solution
A light-receiving element with a semiconductor substrate divided into matrix-form pixel regions, each comprising a first semiconductor region, a second semiconductor region, and a dielectric blocking region between them, enhancing optical separation and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional CAPD type indirect ToF sensor is used, then rapid distribution of signal charges is achieved, but pixel separation is insufficient causing light leakage and color mixing
Solution Approach 1:
The sensor is divided into multiple pixel regions with lattice-shaped pixel separating parts between them. These separating parts physically segment the pixel regions to prevent light leakage while maintaining rapid signal charge distribution within each pixel region through the CAPD structure.
Solution Approach 2:
The pixel separating parts are strategically positioned only at the boundaries between pixel regions where light leakage occurs, rather than uniformly across the entire sensor. This localized approach prevents color mixing at critical interfaces while preserving the rapid charge distribution capability in the active pixel areas.
2Measurement precision
If pixel separating parts are added to improve pixel separation, then light leakage is reduced, but device complexity increases
Solution Approach 1:
The pixel separating parts are implemented as lattice-shaped structures that segment only the necessary boundary regions between pixels. This segmented approach provides effective light isolation without requiring complete coverage across the entire sensor area, thereby limiting the increase in device complexity.
Solution Approach 2:
The pixel separating parts act as intermediary structures between adjacent pixel regions, providing a compact barrier that prevents light leakage. These intermediaries are positioned only where needed at pixel boundaries, avoiding the complexity of modifying the entire sensor structure while still achieving the desired isolation effect.
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 reduces light leakage and improves pixel separation, thereby enhancing the accuracy of distance measurements in CAPD type indirect ToF sensors.
Implementation Method 1
a first blocking region disposed between the first semiconductor region and the second semiconductor region on the first surface side in the semiconductor substrate and having a dielectric constant different from that of the semiconductor substrate
Data Source
AI summary
Distance measurement accuracy is improved. A light-receiving element according to an embodiment includes a semiconductor substrate, and lattice-shaped pixel separating parts that divide the semiconductor substrate into a plurality of pixel regions arranged in a matrix form, wherein each of the pixel regions includes: a first semiconductor region disposed on a first surface side in the semiconductor substrate; a second semiconductor region disposed on the first surface side in the semiconductor substrate separately from the first semiconductor region; and a first blocking region disposed between the first semiconductor region and the second semiconductor region on the first surface side in the semiconductor substrate and having a dielectric constant different from that of the semiconductor substrate.