MOSFET Reverse-Bias Treatment for Post-Irradiation Leakage Control
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Solution Overview
Problem
Existing MOS devices face issues with non-uniform performance due to unstable trapped charges formed during high-energy particle irradiation, leading to increased leakage currents and reduced drain-source withstanding voltage, which affects their applicability in various fields.
Innovation Solution
Applying a specified current to the drains and a same specified voltage to the gates and sources of MOS transistors after irradiation, maintaining a reverse biased state to generate electron-hole pairs that recombine with trapped charges, stabilizing performance across the devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-energy particle irradiation is applied to reduce minority carrier lifetime, then reverse recovery performance is improved, but unstable trapped charges are formed causing increased leakage current and reduced uniformity
Solution Approach 1:
The patent applies a reverse bias voltage treatment before final device testing to pre-remove unstable trapped charges formed during irradiation. This preliminary action stabilizes the leakage current characteristics before the device is considered complete, preventing the uniformity problems that would otherwise occur.
Solution Approach 2:
The patent converts the harmful effect of unstable trapped charges (which increase leakage current variability) into a beneficial process by applying reverse bias voltage. This voltage treatment causes electron-hole pairs to recombine with trapped charges, effectively using the trapped charges as recombination centers to improve reverse recovery performance while simultaneously removing their harmful instability through controlled recombination.
2Reliability
If high-energy particle irradiation is applied to improve reverse recovery performance, then minority carrier lifetime is reduced, but drain-source withstanding voltage convergence deteriorates
Solution Approach 1:
The patent implements a preliminary reverse bias voltage treatment step after irradiation but before final device characterization. This treatment stabilizes the electrical characteristics including drain-source withstanding voltage by removing unstable trapped charges, ensuring consistent and converged voltage characteristics across devices.
Solution Approach 2:
The patent changes the electrical state parameters of the device by applying reverse bias voltage, which alters the distribution and stability of trapped charges. This parameter change transforms the device from an unstable post-irradiation state to a stable operational state with converged withstanding voltage characteristics.
3Reliability
If high-energy particle irradiation is applied to speed up electron-hole recombination, then reverse recovery charge is reduced, but trapped charges become difficult to remove causing performance deterioration
Solution Approach 1:
The patent converts the difficult-to-remove trapped charges into beneficial recombination centers by applying reverse bias voltage. This voltage treatment facilitates electron-hole pair generation that recombines with trapped charges, removing their instability while maintaining their useful function as recombination centers for improving reverse recovery charge characteristics.
Solution Approach 2:
The patent introduces reverse bias voltage as an intermediary mechanism to mediate between the trapped charges and electron-hole pairs. This intermediary voltage treatment enables controlled recombination that removes unstable trapped charges without requiring complex physical or chemical processing steps.
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 method enhances uniformity of leakage currents and improves drain-source withstanding voltage, allowing MOS transistors to operate more consistently and in a wider range of applications.
Implementation Method 1
a commonly used lifetime control technique is irradiation. In an irradiation process, a MOS device is bombarded by high-energy particles, forming unstable trapped charges at an insulating oxide layer and at an interface between the insulating oxide layer and a semiconductor substrate in the MOS device
Implementation Method 2
a specific quantity of electron-hole pairs may be generated at the insulating oxide layer and at the interface between the insulating oxide layer and the semiconductor substrate. These electron-hole pairs may recombine with the trapped charges, removing the unstable trapped charges generated during the irradiation
Data Source
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AI summary
This application provides a field-effect transistor, a production method thereof, a switching circuit, and a circuit board. The production method may include: providing field-effect transistors and irradiating the field-effect transistors; and applying a specified current to drains of the field-effect transistors for specified duration, and applying a same specified voltage to gates and sources of the field-effect transistors. The specified voltage is a grounding voltage or reverse voltage. In this way, the field-effect transistors can be in a reverse biased state in a case of cut-off, and electron-hole pairs can be generated at an insulating oxide layer and at an interface between the insulating oxide layer and a semiconductor substrate. These electron-hole pairs may recombine with trapped charges, removing the trapped charges generated during irradiation. Therefore, leakage currents at the drains can be reduced, uniformity of leakage currents can be increased, and convergence of a drain-source withstanding voltage can be improved. In addition, the same specified voltage is applied to the gates and sources of the field-effect transistors, preventing the field-effect transistors from being broken down in the reverse biased state.