Study On The Irradiation Induced Damage Of SiC Power Vmosfets Devices

Silicon Carbide（SiC）material is a semiconductor material with a band gap of3.2e V.SiC based devices have strong core competitiveness in the field of high-power,high-frequency and high-temperature electronic devices by virtue of excellent electrical properties and high thermal conductivity.SiC vertical metal-oxide semiconductor field-effect transistors（VMOSFETs）can combine with the accumulated process foundation of silicon devices,which greatly reduces the development cost of SiC VMOSFETs.Theoretically,SiC devices have the ability to work stably in aerospace,military,nuclear and other fields of strong radiation,which also makes SiC devices attract much attention.However,the reliability of SiC VMOSFETs in space equipment still faces the challenge from the strong radiation environment.Therefore,it is very important to study the radiation effect of SiC VMOSFETs and reveal the radiation damage mechanism of SiC VMOSFETs.In this dissertation,commercial SiC VMOSFETS devices are taken as the research object to carry out experimental research on high-energy proton,neutron,gamma ray and heavy ion radiation.The main research contents and results of this dissertation are as follows:（1）The single-event burning（SEB）experiments of SiC VMOSFETs induced by protons and heavy ions were carried out relying on the 60-Me V proton,100-Me V proton and heavy ion irradiation sources.The SEB location was analyzed by in-situ measurement,optical microscopy,photoinduced resistance change（OBIRCH）,scanning electron microscopy（SEM）and focused ion beam（FIB）.It is found that the SEB caused by proton irradiation is different from that caused by heavy ions.Before the SEB caused by proton irradiation,there was no phenomenon of slow rise of drain current,which occurred in heavy ion-induced SEB.The results show that the sensitive region of SEB induced by proton irradiation is the same as that of SEB induced by heavy ions,both of which are in the active region of the device.After analysis,it is found that the main mechanisms of SEB caused by heavy ions and protons are shock ionization and indirect ionization,respectively.（2）Based on the ⁶⁰C_o irradiation source,the total dose radiation experiment of SiC VMOSFETs device was carried out.The electrical performance and low frequency noise（LFN）were characterized before and after theγ-ray experiment.The experimental results show that the device can be used normally when the total dose is accumulated up to 6 Mrad（Si）.（3）Based on the 14-Me V neutron irradiation source,the displacement damage experiment of SiC VMOSFETs was carried out.The electrical properties,LFN and deep level transient spectrum（DLTS）of the device were characterized before and after the experiment.The experimental results show that the leakage current and other properties decreased after irradiation.They were caused by the increase of the carbon vacancy defects,which cause the decrease of the carrier concentration and the carrier mobility.Under the synergistic effect of voltage and neutrons in bias devices,the reduction in device carrier concentration,mobility,and lifetime leads to increased displacement damage.Among them,the significant reduction in carrier lifetime due to the larger carrier trapping cross-section is the main reason.