Solid-State Imaging Device Pixel Light Receiving Efficiency
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Solution Overview
Problem
Conventional solid-state imaging devices with shared pixel drain regions suffer from reduced light receiving efficiency, leading to image sensitivity deterioration and color shading defects due to misalignment of light receiving regions and converging lenses.
Innovation Solution
The solid-state imaging device is designed such that the center of each pixel coincides with the center of its light receiving region, with a converging lens optical axis passing through the pixel center, allowing for symmetrical pixel layouts and improved light convergence efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If multiple pixels share one drain region to reduce pixel size, then pixel size is reduced, but light receiving efficiency deteriorates due to misalignment between light receiving regions and converging lenses
Solution Approach 1:
The invention repositions the light receiving region within the pixel structure, specifically placing it at the center of the pixel rather than at the corner. This dimensional repositioning allows the light receiving region to align with the optical axis of the converging lens, thereby resolving the misalignment issue that occurs when multiple pixels share a drain region. The photoelectric conversion section is configured to extend beneath the gate electrode, creating space for the centrally positioned light receiving region without increasing pixel area.
2Reliability
If light receiving regions are positioned at pixel centers to improve light receiving efficiency, then light receiving efficiency improves, but pixel layout complexity increases due to shared drain regions
Solution Approach 1:
The invention introduces asymmetry in the pixel layout by positioning the light receiving region at the center of the pixel while allowing adjacent pixels to share a common drain region. This asymmetric arrangement resolves the contradiction by decoupling the light receiving function (centered for optimal lens alignment) from the readout function (shared drain region for compactness). The photoelectric conversion section extends asymmetrically beneath the gate electrode to accommodate this configuration.
3Reliability
If converging lenses are aligned with pixel centers, then light convergence improves, but misalignment with light receiving regions causes sensitivity variations and color shading defects
Solution Approach 1:
The invention performs preliminary positioning of the light receiving region at the pixel center during the design and fabrication stage. This preliminary action ensures that when converging lenses are aligned with pixel centers (as is standard practice), they automatically align with the light receiving regions as well. The photoelectric conversion section is pre-configured to extend beneath the gate electrode, creating the necessary space for this centered arrangement, thereby eliminating sensitivity variations and color shading defects before the imaging process begins.
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 light receiving efficiency, reducing sensitivity variations and color shading defects, resulting in improved image characteristics.
Implementation Method 1
converging lenses 119... In order to converge a light to the pixels 102a and 102b as much as possible
Implementation Method 2
a photoelectric conversion section (not shown) for converting an incident light into a signal electric charge
Data Source
AI summary
Realized is a solid-state imaging device capable of achieving both a finer pixel size and high light receiving efficiency with an excellent image characteristic. A high concentration p-well layer (5) is partially formed in the interior of a semiconductor substrate (1) centering on a region under a STI (6), and a photoelectric conversion layer (9a, 9b) is formed so as to extend to a region under a gate electrode (10a, 10b). Furthermore, a salicide region (12a, 12b) covers only a portion of a surface of the gate electrode (10a, 10b) and is formed at a position closer to a side at which a drain region (13) is provided. Thus, an incident light is allowed to pass through a portion, included in the surface of the gate electrode (10a, 10b), on which the salicide region (12a, 12b) is not formed, and then to be further incident on the photoelectric conversion layer (9a, 9b) extending to the region under the gate electrode (10a, 10b).