Pixel Nanostructure Layout for Edge Sensitivity in Light Detection
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Solution Overview
Problem
Existing light detection devices, such as image sensors, suffer from reduced sensitivity and image quality due to the lower light amount on the peripheral edge side of the photoelectric conversion region, even when nanostructures are used to control light propagation.
Innovation Solution
A light detection device is designed with a pixel array that includes a photoelectric conversion region and a light guide region with nanostructures. The nanostructures in the light guide region direct light to the photoelectric conversion region and have characteristics that vary based on the position of the pixel unit in the array, controlling the opening range to optimize light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If nanostructures are disposed on the light incident surface side of the photodiode to control light propagation direction, then light collection capability is improved, but sensitivity is lowered on the peripheral edge side due to color mixture
Solution Approach 1:
The patent applies local quality by making the nanostructures have different characteristics at different positions in the pixel array. Specifically, the nanostructures in the peripheral region have different shapes, sizes, or arrangements compared to those in the central region, allowing each region to be optimized for its specific light collection needs while preventing color mixture that would reduce sensitivity.
Solution Approach 2:
The patent segments the pixel array into different regions (central region and peripheral region) and provides different nanostructure configurations for each region. This segmentation allows independent optimization of light collection for each region, preventing the uniform nanostructure design from causing color mixture and sensitivity loss in the peripheral areas.
2Illumination intensity
If on-chip lens is disposed on the light-incident surface side of the photoelectric conversion region, then light transmission is improved, but sensitivity of the peripheral edge part is lowered due to vignetting and cosine fourth rule
Solution Approach 1:
The patent replaces the uniform on-chip lens with position-dependent nanostructures that have different characteristics for central and peripheral regions. This local quality approach compensates for the vignetting effect by providing enhanced light collection capability specifically in the peripheral regions where the on-chip lens fails to deliver adequate light transmission.
3Quantity of substance
If nanostructures control the propagation direction of light, then light amount is increased, but color mixture occurs easily and sensitivity is lowered
Solution Approach 1:
The patent uses local quality by designing nanostructures with different characteristics in different regions of the pixel array. The nanostructures are configured to direct light within a controlled angular range that prevents color mixture while still increasing the light amount reaching the photodiode, with regional variations optimized for their specific positions.
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 configuration effectively suppresses the lowering of resolution while improving sensitivity by ensuring consistent light distribution across the photoelectric conversion region, even at the peripheral edges.
Implementation Method 1
a light guide region that guides light to the photoelectric conversion region... the nanostructures have at least one characteristic that varies based on a position of the pixel unit in the pixel array... controls the propagation direction of light
Data Source
AI summary
A light detection device comprises a pixel array including a plurality of pixel units. At least one pixel unit of the plurality of pixel units includes a photoelectric conversion region and a light guide region that guides light to the photoelectric conversion region. For each pixel unit of the at least one pixel unit, the light guide region includes nanostructures that direct light to the photoelectric conversion region, and the nanostructures have at least one characteristic that varies based on a position of the pixel unit in the pixel array.