VFET Radiation Sensor Using Charge Collector Dielectric Layer
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Solution Overview
Problem
Conventional vertical field effect transistors (VFETs) are not sensitive to radiation due to superior channel control by metal gates at both sides of fins, making them unsuitable for use in radiation sensors.
Innovation Solution
A radiation sensor is formed by modifying a VFET with a fin structure including semiconductor material on a substrate, where a gate is formed on an inner side and a charge collector dielectric layer is formed on an outer side of the fin structure, allowing radiation charges to be trapped and modulating transistor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal gates are formed at both sides of fins in a VFET, then channel control is improved, but radiation sensitivity deteriorates
Solution Approach 1:
The patent removes one of the metal gates from the VFET structure, extracting the gate component that prevents radiation sensitivity. By forming a charge collector dielectric layer in place of the removed gate, the structure enables radiation charge collection while maintaining channel control through the remaining gate, thus resolving the contradiction between channel control and radiation sensitivity.
Solution Approach 2:
The patent applies different material properties to different regions of the device. The inner side of the fin structure maintains metal gate control for channel management, while the outer side uses a charge collector dielectric layer with high-k properties for radiation charge collection. This local differentiation allows simultaneous achievement of channel control and radiation sensitivity.
2Object-affected harmful factors
If a charge collector dielectric layer is formed on the outer side of the fin structure, then radiation sensitivity is improved, but device complexity increases
Solution Approach 1:
The charge collector dielectric layer serves multiple functions: it collects radiation-induced charges, modulates the transistor threshold voltage to enable radiation detection, and maintains electrical isolation. By combining these functions into a single component, the patent achieves radiation sensitivity without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the charge collection function with the gate structure by forming the charge collector dielectric layer directly on the outer side of the fin structure, adjacent to where a second gate would normally be. This integration allows the dielectric layer to perform charge collection while the remaining gate structure maintains channel control, avoiding the need for completely separate components.
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 modified VFET radiation sensor becomes sensitive to radiation, enabling the detection of radiation doses through shifts in threshold voltage, effectively utilizing the charge collector dielectric layer as a back gate.
Implementation Method 1
a charge collector dielectric layer formed on an outer side of the fin structure... enabling the detection of radiation doses through shifts in threshold voltage, effectively utilizing the charge collector dielectric layer as a back gate
Implementation Method 2
When a MOSFET dosimeter is irradiated, electron-hole pairs are generated within the gate oxide of the MOSFET by the incident radiation
Data Source
AI summary
A semiconductor device includes a semiconductor structure formed on a substrate, a gate dielectric formed on a first side of the semiconductor structure, and a dielectric layer formed on a second side of the semiconductor structure.