Soft X-ray Detection Unit Layout for Charge Collection Accuracy
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Solution Overview
Problem
Current solid-state image pickup devices are unable to accurately detect soft X-ray radiation due to inefficiencies in charge collection and signal amplification, particularly because transistors are often disposed between semiconductor regions, leading to partial discharge of electric charge and inaccurate energy measurement of soft X-rays.
Innovation Solution
A soft X-ray detection apparatus is designed with a semiconductor substrate featuring detection units that include a conversion unit for charge generation and a circuit unit with an amplifier transistor, where transistors are strategically positioned to minimize discharge regions and maximize charge collection, using isolation units and specific transistor placement to ensure accurate signal readout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If transistors are disposed between semiconductor regions for signal amplification, then signal amplification capability is improved, but charge collection accuracy deteriorates due to partial discharge
Solution Approach 1:
The patent extracts the transistor from the position between semiconductor regions and relocates it to the periphery of the detection unit. This removes the harmful effect of the transistor causing partial charge discharge while preserving its signal amplification function through the readout circuit.
Solution Approach 2:
The patent introduces a readout circuit as an intermediary between the semiconductor region and the transistor. This readout circuit collects the charge from the semiconductor region and transfers it to the transistor for amplification, preventing direct interaction that would cause charge loss.
2Productivity
If detection units are arranged closely for higher pixel density, then device integration is improved, but charge discharge between adjacent regions increases
Solution Approach 1:
The patent segments the detection unit by clearly separating the semiconductor region from the transistor region using a readout circuit. This segmentation prevents charge from one pixel from discharging into adjacent pixels, maintaining charge collection reliability even with high pixel density.
3Area of stationary object
If transistors are positioned close to semiconductor regions for compact design, then device area is reduced, but charge discharge probability increases
Solution Approach 1:
The patent extracts the transistor from the immediate vicinity of the semiconductor region and positions it in the periphery through the readout circuit. This increases the distance between charge generation and amplification regions, reducing charge discharge probability while maintaining compact overall design.
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 apparatus effectively detects soft X-ray radiation by reducing discharge probabilities and enhancing the accuracy of energy measurement, allowing for nearly all electric charge generated by a photon to be read as a signal, thereby improving the precision of soft X-ray energy measurement.
Implementation Method 1
a first conductive type semiconductor region that is disposed in the semiconductor substrate and that collects electric charge generated upon incidence of soft X-ray radiation
Data Source
AI summary
A soft X-ray detection apparatus includes a semiconductor substrate. The semiconductor substrate has a plurality of detection units disposed thereon, each including a conversion unit and a circuit unit. The conversion unit is formed from, for example, a photodiode. The conversion unit collects electric charge generated upon incidence of soft X-ray radiation. A first conductive type (e.g., N-channel type) amplifier transistor is disposed in the circuit unit. The amplifier transistor serves as an amplifier unit that amplifies and outputs a signal supplied from the conversion unit. A first conductive type transistor is not disposed between the conversion units that are immediately adjacent to each other. Alternatively, transistors included in the detection units that are immediately adjacent to each other are disposed so as to be in close proximity to each other.