X-Ray Light-Receiving Element Structure for Total Dose Mitigation
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Solution Overview
Problem
X-ray imaging elements face challenges in reducing the total dose effect caused by X-ray irradiation, which leads to degradation in semiconductor materials due to the accumulation of radioactive rays, resulting in increased interface states and decreased performance.
Innovation Solution
The implementation of a light-receiving element with a specific structure that includes a semiconductor substrate with a photoelectric conversion region, a p-type electrically-conductive region, an n-type electrically-conductive region, and a Lightly Doped Anode (LDA) with a lower impurity concentration, along with an insulating layer and a high-dielectric material, to mitigate the effects of X-ray irradiation by reducing the interface state generation and dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple integrated structure of photoelectric conversion region and floating diffusion region is used, then ease of manufacture is improved, but reliability deteriorates due to total dose effect from X-ray irradiation
Solution Approach 1:
The patent segments the originally integrated photoelectric conversion region and floating diffusion region into separate physical locations. The photoelectric conversion region is positioned in the semiconductor substrate while the floating diffusion region is formed on the surface through selective oxidation, creating spatial separation that reduces total dose effect while maintaining manufacturing feasibility through controlled oxidation processes.
Solution Approach 2:
The patent introduces an insulating layer as an intermediary between the photoelectric conversion region and the floating diffusion region. This insulating layer, formed through selective oxidation, acts as a mediator that electrically isolates the two regions, reducing the total dose effect while allowing signal charge transfer through controlled mechanisms.
2Measurement precision
If the photoelectric conversion region thickness is increased to improve sensitivity, then measurement precision is improved, but device complexity increases due to additional conductive regions and insulating layers
Solution Approach 1:
The patent applies local quality by forming the insulating layer selectively only in specific regions where needed for total dose effect mitigation. The selective oxidation process creates insulating regions localized between the photoelectric conversion region and floating diffusion region, while leaving other areas unchanged, thus improving sensitivity without uniformly increasing device complexity.
Solution Approach 2:
The patent utilizes parameter changes by controlling the oxidation conditions to adjust the thickness and distribution of the insulating layer. By varying oxidation time, temperature, and atmosphere, the insulating layer parameters can be optimized to achieve the desired balance between total dose effect reduction and signal charge transfer efficiency.
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 the influence of X-ray irradiation on the semiconductor substrate, minimizing the total dose effect and maintaining the conversion efficiency of the X-ray imaging element.
Implementation Method 1
a semiconductor substrate including a photoelectric conversion region
Data Source
AI summary
A first light-receiving element of an embodiment of the disclosure includes: a semiconductor substrate including a photoelectric conversion region; a first first electrically-conductive region provided at a first surface interface of the semiconductor substrate and coupled to a first electrode; a second first electrically-conductive region provided around the first first electrically-conductive region and coupled to a second electrode, at the first surface interface; a third first electrically-conductive region in an electrically floating state provided around the second first electrically-conductive region, at the first surface interface; a first second electrically-conductive region having a different electrically-conductive type between the first first electrically-conductive region and the second first electrically-conductive region, at the first surface interface; and a fourth first electrically-conductive region provided at least between the first first electrically conductive region and the first second electrically-conductive region and having an impurity concentration lower than the first first electrically-conductive region, near the first surface interface.