Stacked Solid-State Image Sensor for UV and Visible Resolution
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Solution Overview
Problem
Conventional solid-state imaging elements that detect both visible and ultraviolet light suffer from decreased resolution due to separate light detection regions and difficulties in color interpolation processing.
Innovation Solution
A solid-state imaging element configuration with a first photoelectric conversion element on one face of a silicon substrate for visible light and a second photoelectric conversion element on the other face for ultraviolet light, connected by a penetrating electric conductor, allowing for simultaneous detection and charge transfer, and optionally including a hafnium film and potential barriers for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate light detection regions are allocated for ultraviolet and visible light in a planar fashion, then both wavelengths can be detected, but resolution decreases
Solution Approach 1:
The patent transitions from planar allocation to three-dimensional vertical stacking, placing UV and visible light detection regions at different depths along the vertical axis. This dimensional change allows both detection functions to coexist without lateral separation, maintaining high resolution while achieving multi-wavelength detection capability.
Solution Approach 2:
The detection system is segmented into distinct vertical layers: a first detection region for visible light and a second detection region for ultraviolet light at different depths. This segmentation allows independent optimization of each detection region while maintaining overall system resolution through vertical rather than lateral separation.
2Adaptability or versatility
If separate light detection regions are used for ultraviolet and visible light, then both can be detected, but color interpolation processing becomes difficult
Solution Approach 1:
By stacking detection regions vertically rather than arranging them laterally in a Bayer pattern, the patent enables all color information to be captured at each pixel location. This eliminates the need for color interpolation processing while maintaining multi-wavelength detection capability, simplifying the overall system complexity.
3Ease of manufacture
If photoelectric conversion elements are formed on a silicon substrate for both visible and ultraviolet light, then integration is achieved, but dark current increases
Solution Approach 1:
The patent applies different structural characteristics to different depth regions: the first detection region for visible light uses standard silicon substrate characteristics, while the second detection region for ultraviolet light is positioned at a specific depth range (0-40 nanometers from surface) with optimized properties. This local quality differentiation reduces dark current while maintaining integration on silicon substrate.
Solution Approach 2:
An insulating film is introduced as an intermediary layer between the UV detection region and the silicon substrate. This intermediary structure prevents direct interaction that would generate dark current, while still allowing UV light to reach the detection region and maintain electrical integration with the substrate.
4Productivity
If ultraviolet photoelectric conversion element is formed near the surface, then UV detection efficiency improves, but visible light detection is affected
Solution Approach 1:
The patent resolves the conflict between UV and visible light detection by separating them in the vertical dimension. The UV detection region is positioned at 0-40 nanometers depth for high UV detection efficiency, while the visible light detection region is positioned at greater depth, allowing both to function independently without mutual interference.
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
Enables high-resolution detection of both visible and ultraviolet light in a single pixel without resolution loss, reducing dark current and eliminating the need for color filters, while allowing for autofocusing through phase difference detection.
Implementation Method 1
a first photoelectric conversion element; a first accumulation part configured to accumulate electric charges photoelectrically converted by the first photoelectric conversion element
Implementation Method 2
a second photoelectric conversion element disposed on one face of a substrate and configured to accumulate electric charges photoelectrically converted by the second photoelectric conversion element
Implementation Method 3
a connection part connected to the second accumulation part and configured to transfer the electric charges accumulated in the second accumulation part to another face of the substrate
Data Source
AI summary
A solid-state imaging element which detects visible light and ultraviolet light in one pixel provides improved resolution. First and second photoelectric conversion elements each perform photoelectric conversion of incident light. A first accumulation part accumulates electric charges that are photoelectrically converted by the first photoelectric conversion element second accumulation part is disposed on one face of a substrate and accumulates electric charges that are photoelectrically converted by the second photoelectric conversion element. A connection part is connected to the second accumulation part and transfers the electric charges accumulated in the second accumulation part to another face of the substrate.