Study On The 4H-SiC Schottky Barrier Diode And Junction Termination Technology

4H-SiC Schottky Barrier Diode(SBD), fabricated by the new generation wide band gap semiconductor material, has incomparable superiority features to PN junction diode. The production and analysis of 4H-SiC materials and 4H-SiC SBD have been built up a more detailed report in foreign, but that in domestic start later, relatively have fewer research reports. Therefore the research of 4H-SiC SBD device has very important practical significance.In this thesis, the main electrical properties of 4H-SiC SBD are studied systematically. The main studies and contributions of this thesis are as follows:1. The main reason impacted the reverse breakdown characteristic is the electric field crowding at the edge of the 4H-SiC SBD device. In order to solve this problem, the junction termination structure to reduce the strong electric field on the surface of the device is added. Via the analysis of the classification of junction terminal structure, the expanded terminal structure is used to improve the reverse breakdown characteristics of the device.2. The simulation of different junction termination structures are realized by the Silvaco TCAD simulation software. Firstly, two-level Field Limiting Rings(FLRs) structure 4H-SiC SBD is simulated, and the main sensitive parameters of the FLRs structure are the space between two FLRs, the deep, and doping concentration, and the optical values of the parameters above respectively are 3μm, 0.4μm, and 1×1017cm-3 when the width of FLRs is 10μm, the breakdown voltage of the device is about 1200 V. However the FLRs structure is very sensitive to the surface charges of the device, the Field Plate(FP) structure is added under the basis of the FLRs, and the main sensitive parameter of the FP structure is the length, of which optimal value is 20μm, the breakdown voltage is about 1350 V. Secondly the Junction Terminal Extension(JTE) structure 4H-SiC SBD are simulated, and the main sensitive parameters of the JTE structure are the length, the deep, and doping concentration, the optical values of the parameters above respectively are 30μm, 1.0μm, 1×1018cm-3, and the breakdown voltage of the device is about 1500 V.3. The simulation results of different junction termination structures are analyzed in detail. Compared to the breakdown characteristics of the FLRs structure device and the FLRs-FP composite structure device, the breakdown characteristic of JTE structure device is better. Therfore the experiment of JTE structure 4H-SiC SBD device is conducted.Via secondary ion mass spectrometry(SIMS), the doping concentration of Al ions of the JTE structure is 1018cm-3 within the scope of 0.9μm. The opening voltage of the device testing by Keithley 4200 tracer is 0.9V when the current is 0.7A, the reverse voltage of the device is 1200 V when the reverse current is 10μA, and the reverse recovery time is only 25 ns according to the reverse recovery characteristic curve of the device.