Solid-state image sensor, manufacturing method thereof, and electronic device
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Solution Overview
Problem
Solid-state image sensors with compound semiconductors face issues with dark current deterioration due to strong electric fields generated by P-type diffusion regions as pixel electrodes.
Innovation Solution
Incorporating a pixel separation portion between pixel electrodes in the solid-state image sensor, which are formed within a photoelectric conversion layer containing a compound semiconductor, to suppress dark currents by gradually decreasing impurity concentration and preventing excessive diffusion of P-type impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If P-type diffusion regions are formed as pixel electrodes to read out signal charges, then signal charge extraction capability is improved, but dark currents increase due to strong electric fields
Solution Approach 1:
The pixel separation portion is introduced at specific locations (pixel boundaries) to create local electric field modulation. This structure has a different impurity concentration configuration compared to the pixel electrode regions, allowing localized control of electric field strength to suppress dark currents at pixel boundaries while preserving signal charge extraction capability within pixel regions
Solution Approach 2:
The pixel separation portion divides the pixel array into distinct pixel regions, creating separate zones with different electrical characteristics. This segmentation allows independent optimization of each zone: pixel electrodes for signal extraction and pixel separation portions for dark current suppression
2Ease of manufacture
If P-type impurities are diffused to form pixel electrodes, then pixel electrode functionality is achieved, but impurity diffusion causes leakage between adjacent pixels
Solution Approach 1:
The pixel separation portion acts as an intermediary structure between adjacent pixel electrodes. It serves as a buffer zone that prevents direct interaction and leakage between pixel regions while allowing the pixel electrodes to be formed using standard diffusion processes. The pixel separation portion absorbs excess impurity diffusion and maintains electrical isolation between 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
The solution effectively reduces dark currents by creating a gentle electric field and preventing leakage between pixels, thereby enhancing the uniformity and quality of signal charge extraction.
Implementation Method 1
there is a concern about the deterioration of dark currents due to the strong electric field generated by the P-type diffusion regions as pixel electrodes
Implementation Method 2
preventing excessive diffusion of P-type impurities
Data Source
AI summary
The present disclosure relates to a solid-state image sensor configured to be capable of suppressing dark currents in a solid-state image sensor including a compound semiconductor and a manufacturing method thereof, and an electronic device. A solid-state image sensor includes a photoelectric conversion layer containing a compound semiconductor, pixel electrodes that take out electric charges generated in the photoelectric conversion layer for each pixel, and a pixel separation portion disposed between the pixel electrodes of each pixel. The technique of the present disclosure can be applied to a solid-state image sensor that photoelectrically converts light with wavelengths within the visible region and the short infrared region.