Research Of Novel Structures For Breakdown Enhancement And For Single Event Burnout Hardening Based On Enhancement-mode AlGaN/GaN MISFET

In power electronics and electronic equipment system,the energy consumption is very important.The switching device based on the third-generation semiconductor material GaN has high breakdown electric field and high electron mobility,which has higher energy efficiency than the first-generation semiconductor material Si.In addition,the high radiation tolerance of GaN makes the GaN power switching devices more advantageous than Si devices in the application of radiation environment,such as the solar power supply system of satellites.GaN power switching devices has attracted much attention in the industry in recent years.However,it still fails to give full play to its advantages.The breakdown in advance caused by leakage current lead to few commercial products of GaN enhanced switching devices in the high voltage segment(1200V).In addition,the research on anti-radiation reinforcement is insufficient,and there are also few products of anti-radiation hardened GaN power transistors.This paper takes a conventional enhanced AlGaN/GaN Metal-Insulator-Semiconductor Field-Effect Transistor with gate field plate(GFP-C MISFET)as the research object.In order to solve the problem of breakdown due to buffer layer leakage current,novel enhanced breakdown structure were designed to meet the requirements of the high voltage application,improve the electric field distribution,device's breakdown voltage and Baliga's Figure of Merit(BFOM)which make it more efficient.In order to supplement the research in the field of single event burnout(SEB)hardening of GaN power switching devices,the SEB mechanism of GFP-C MISFET was studied,and the hardening structure against the SEB were proposed to improve the radiation resistance.Through relevant theoretical research and simulation data analysis,the achievements obtained in the paper are summarized as follows:1.Breakdown-enhanced structure based on P-type buried layer and drain field plateIn order to improve the breakdown voltage of the device,a P-type buried layer(PBL)connected to the source is inserted into the buffer to suppress the leakage current and improve the electric field distribution near the gate,meanwhile,a drain field plate is set to improve the electric field distribution near the drain.The PBL only consumes part of the two-dimensional electron gas and the on-resistance is less degraded,so the breakdown voltage and the on-resistance can get a good compromise.By software Sentaurus TCAD(Technology Computer Aided Design)and parameter optimization,proposed breakdown-enhanced SC-PBL FPs MISFET(MISFET with A Source-Connected P-Burid Layer and Field Plates)have a enhanceed breakdown voltage of 1311.62 V and a BFOM of 2.6 GW·cm-2.2.Breakdown-enhanced structure based on electrode connected embedded PINIn order to further utilize the advantages of GaN materials and optimize the potential distribution near drain region,a voltage breakdown-enhanced technique is proposed in which a source-connected P-type buried layer and a drain-connected N-type buried layer are combined.On the one hand,the N-type buried layer can provide additional carriers for the device and improve the on-resistance;on the other hand,the P-type buried layer,the buffer layer and the N-type buried layer can be considered as a reverse biased PIN diode,which can effectively improve the potential distribution between the gate and the drain.Although the process is more complex than SC-PBL FPs MISFET,the MISFET with an electrode-connected PIN diode inserted in the buffer layer(EC-PIN MISFET)could achieve a breakdown voltage of 1400V with a BFOM of 3.08 GW·cm-2 after final optimization.3.Study on mechanism and hardened structure of single event burnout(SEB)effectThe stream of electrons and holes are analyzed by the method of transient analysis with the heavy ions incidenting at different positions,the mechanism of SEB and its dependence on electric field distribution in enhanced-mode AlGaN/GaN MISFET are further understood and determined.In order to improve the radiation tolerance of the device,a hardened technology combining a drain-connected N-type plug and a source-connected P-type plug is proposed,and based on this technology,a novel radiation-hardened device EC-DP MISFET(MISFET with Electrode-Connected Doped Plugs)is proposed.Using the same radiation environment comparison research method,it was found that compared with GFP-C MISFET,EC-DP MISFET can effectively discharge electron holes generated by heavy ion irradiation,reducing the risk of device burnout and obtaining a safer operation area against SEB.