Polarization Imaging Pixel Layout for Crosstalk Reduction
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Solution Overview
Problem
Conventional imaging elements that acquire polarization information suffer from increased crosstalk between pixels due to insufficient depth of the light shielding film, leading to errors in polarization information and deteriorated image quality.
Innovation Solution
The imaging element incorporates a separation region in the semiconductor substrate to separate pixels and a non-separation region in the clearance of the separation region near the pixel corners, reducing crosstalk by minimizing variations in recess depth and preventing light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light shielding film is formed by etching lattice-shaped grooves and embedding conductive material, then pixel separation is achieved, but microloading phenomenon causes groove depth variation and insufficient shielding depth
Solution Approach 1:
The separation region is divided into a first separation region with light shielding film and a second separation region without light shielding film. This segmentation allows the etching process to target only specific areas, avoiding the microloading phenomenon at intersection points while maintaining effective light shielding where needed.
Solution Approach 2:
Different regions of the pixel array have different separation structures: the first separation region between adjacent pixels uses light shielding film for strong isolation, while the second separation region at corner intersections uses only etched grooves without light shielding material, optimizing both shielding effectiveness and manufacturing uniformity.
2Reliability
If light shielding film is embedded in all separation grooves, then pixel isolation is improved, but crosstalk increases due to insufficient groove depth from microloading
Solution Approach 1:
The separation structure is segmented into two types: regions with light shielding film and regions without. This allows the light shielding film to be applied only where maximum isolation is needed, while avoiding areas where etching depth uniformity would be compromised by the microloading phenomenon.
Solution Approach 2:
The etched groove structure serves as an intermediary between the light shielding film and the pixel elements. In the second separation region, the groove itself provides sufficient isolation without requiring light shielding material, thereby avoiding the depth variation problem while maintaining pixel isolation.
3Reliability
If etching grooves are made deeper to prevent light leakage, then crosstalk is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The etching process is segmented into two distinct operations: one for creating grooves that will receive light shielding film, and another for creating grooves that will remain as simple etched structures. This segmentation allows each etching process to be optimized independently, avoiding the need for uniformly deep etching across all regions.
Solution Approach 2:
Different groove depths and structures are created in different regions: the first separation region receives light shielding film in shallower grooves, while the second separation region has deeper etched grooves without light shielding material. This local differentiation achieves effective light leakage prevention without requiring complex deep etching throughout the entire structure.
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 reduces crosstalk between pixels, enhancing the accuracy of polarization information and improving the overall image quality by minimizing errors and light leakage.
Implementation Method 1
The incident light in the polarization direction parallel to an arrangement direction of the plurality of strip-shaped conductors is transmitted through the polarization unit including the wire grid, and the incident light in the polarization direction perpendicular to the arrangement direction of the plurality of strip-shaped conductors is reflected by the polarization unit and attenuated.
Implementation Method 2
a photoelectric conversion unit that is formed in a semiconductor substrate and performs photoelectric conversion of the polarized incident light
Data Source
AI summary
An imaging element is provided with a plurality of pixels, a separation region, and a non-separation region. Each of the plurality of pixels is provided with a polarization unit that polarizes incident light in a specific polarization direction and a photoelectric conversion unit that is formed in a semiconductor substrate and performs photoelectric conversion of the polarized incident light. The separation region is arranged in the semiconductor substrate and separates the plurality of pixels from each other. The non-separation region includes the semiconductor substrate and is arranged in a clearance formed in the separation region in the vicinity of a corner of each of the plurality of pixels.