Global Shutter Pixel Structure for Parasitic Light Noise Blocking
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Solution Overview
Problem
Solid-state imaging devices with global shutter function face issues with parasitic light sensitivity noise due to incident light being diffracted by light blocking films and entering memory portions, which affects image quality and sensitivity.
Innovation Solution
The design includes a solid-state imaging device with pixels arranged in a matrix on a substrate, featuring a photoelectric conversion region, a charge retaining region, and an indented region with a light blocking film covering the charge retaining region's surface and side walls, preventing light from entering the charge retaining region and thus eliminating parasitic light sensitivity noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light blocking film is used to block incident light, then optical noise is reduced, but parasitic light sensitivity noise is generated due to diffraction by the light blocking film
Solution Approach 1:
The patent introduces a new spatial dimension by creating an indented region that extends vertically into the substrate. This dimensional change allows the light blocking film to be positioned in a new spatial location (within the indented region) where it can block diffracted light paths without directly contacting the charge retaining region, thus eliminating parasitic light sensitivity noise while maintaining optical noise reduction
Solution Approach 2:
The patent segments the light blocking function into two distinct components: a first light blocking film positioned in the indented region to block diffracted light, and a second light blocking film positioned at the surface to block direct light. This segmentation allows each film to perform its specific function without causing parasitic noise, as the first film is separated from the charge retaining region by the indented structure
2Area of stationary object
If the pixel size is reduced to achieve high image quality, then device size is reduced, but sensitivity and optical performance deteriorate
Solution Approach 1:
By utilizing the vertical dimension through the indented region, the patent enables effective light blocking without increasing the horizontal pixel area. The indented region creates a vertical space that allows the first light blocking film to intercept diffracted light paths, improving sensitivity and optical performance while maintaining small pixel dimensions
Solution Approach 2:
The patent nests the first light blocking film within the indented region, which itself is nested within the pixel structure. This nested arrangement allows the light blocking function to be integrated into the existing pixel architecture without increasing overall pixel size, thereby maintaining high sensitivity and optical performance in compact pixels
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 enhances image quality and sensitivity by eliminating parasitic light sensitivity noise, allowing for improved sensitivity and F number characteristics without trade-offs, enabling a more optimized condensing structure for better optical performance.
Implementation Method 1
a photoelectric conversion region disposed inside the substrate and configured to convert light entering the substrate into charge
Implementation Method 2
a light blocking film formed covering the charge retaining region at the surface side of the substrate and extending along a side wall of the indented region
Data Source
AI summary
A solid-state imaging device includes: a plurality of pixels arranged in a matrix form on a substrate, wherein the plurality of pixels each include a photoelectric conversion region disposed inside the substrate and configured to convert light entering the substrate into charge, a charge retaining region disposed more on a side from which the light enters, than the photoelectric conversion region inside the substrate and configured to retain the charge converted in the photoelectric conversion region, an indented region indented from a surface of the substrate on the side from which the light enters, toward the photoelectric conversion region to at least a depth corresponding to the charge retaining region, and a light blocking film formed covering the charge retaining region at the surface side of the substrate and extending along a side wall of the indented region.