Semiconductor Detector With Through Electrode for Time Resolution
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Solution Overview
Problem
Conventional detectors for X-ray CT and PET systems have insufficient time resolution, leading to suboptimal performance in detecting X-rays and γ-rays.
Innovation Solution
A detector design featuring a wiring board with two-dimensionally arranged semiconductor chips, each equipped with APDs and a through electrode to reduce carrier transmission path length, along with a scintillator for improved sensitivity and a quenching resistance structure for enhanced time resolution and reduced crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photodetector structures are used, then the detector can be manufactured with standard processes, but the time resolution is insufficient
Solution Approach 1:
The detector is divided into multiple semiconductor chips, each containing multiple APD elements. This segmentation allows for optimized carrier transmission paths in each chip while maintaining overall detector functionality, thereby improving time resolution without excessive complexity
Solution Approach 2:
The patent introduces a three-dimensional electrode structure with through-electrodes extending through the semiconductor substrate thickness direction. This vertical dimension reduces carrier transmission path length from the APD active region to the electrode, improving time resolution by enabling faster carrier collection
2Measurement precision
If longer carrier transmission paths are used, then the detector structure can be simpler, but the time resolution deteriorates
Solution Approach 1:
Through-electrodes are implemented that extend vertically through the semiconductor substrate, creating a direct short path for carrier collection in the thickness direction. This three-dimensional approach significantly reduces the carrier transmission path length compared to conventional planar electrode structures, thereby improving time resolution
3Device complexity
If photodetectors are arranged in a matrix with shared readout lines, then the device complexity is reduced, but crosstalk between adjacent pixels increases
Solution Approach 1:
The detector is segmented into multiple independent semiconductor chips, each with its own dedicated readout circuitry. This physical separation eliminates crosstalk between chips while maintaining manageable wiring complexity within each chip through localized readout lines
Solution Approach 2:
Metal layers are introduced as intermediary structures to provide electrical connection between APD elements and readout lines while providing electrical isolation. This mediator approach reduces crosstalk by preventing direct electrical interference between adjacent pixel elements
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 improved detector design enhances time resolution, leading to higher accuracy in photon detection and the ability to acquire high-quality images in both X-ray CT and PET systems.
Implementation Method 1
when a photon is incident on the APD, a carrier generated within the APD is outputted to the outside
Implementation Method 2
A current flows through a pixel where an electron avalanche is generated in the APD, while a voltage drop occurs in a quenching resistance
Data Source
AI summary
Each semiconductor chip of a detector comprises a semiconductor substrate having a plurality of photodetector units, an insulating layer formed on a front face of the semiconductor substrate, a common electrode arranged on the insulating layer, a readout line for electrically connecting a quenching resistance of each photodetector unit and the common electrode to each other, and a through electrode extending from the common electrode to a rear face of the semiconductor substrate through a through hole of the semiconductor substrate.