Gamma ray irradiation response of the trench MOSFET amplifier

BackgroundDeveloping electronic devices, such as metal oxide semiconductor field effect transistor (MOSFET) amplifiers with high radiation resistance, is crucial for robots working in nuclear environments.PurposeThis study aims to test the irradiation resistance performance of commercial MOSFET amplifiers and reveal the corresponding irradiation failure mechanism.MethodsAn in-situ gamma rays irradiation experiment platform was employed to conduct irradiation test on three trench MOSFET amplifiers using a 60Co source. Response to different doses, and the electrical properties of these MOSFET amplifiers were investigated before and after irradiation. The failure analysis methods including electrical characteristics tests, thermal emission microscopy (EMMI) for failure location determination, focused ion beam (FIB) sample preparation, scanning electron microscope (SEM), and transmission electron microscope (TEM) characterization were employed to reveal the irradiation failure mechanism.ResultsExperimental results showed that the three MOSFET amplifiers failed after irradiation by absorbed doses of 982.6 Gy, 986.2 Gy, and 1 082.4 Gy, respectively. The drain-source breakdown voltage BVDSS of the MOSFET decreases from 110.5 V to 0.96 V, while the gate-source drive current IGSS increases from 2.9 nA to 81.3 mA, as well as the threshold voltage VGS(th) is not be detected due to the short circuit.ConclusionsWhen the MOSFET amplifiers are irradiated in a charged operating state, the accumulation of captured charges in the gate oxide will lead to a decrease in the threshold voltage and breakdown voltage. Electron-hole pairs generated by high-energy and high-dose gamma-ray irradiation may continue to accumulate under the action of the circuit electric field, resulting in local high electric fields and high heat areas. The superposition of these high electric fields and high heat areas will cause the source aluminum metal to melt and ablate, causing a short circuit between the gate and the source.