Improved Electrical Characteristics of 1200V/20A 4H-SiC Diode by Substrate Thinning and Laser Annealing

In this paper, two kinds of silicon carbide (SiC) backside metallization processes were developed, which were backside thinning combined with laser annealing to form ohmic contact and direct rapid annealing (RTA) to form ohmic contact. The specific contact resistivity obtained by both annealing processes was 3.4E-5 Ω·cm2 to 3.8E-5 Ω·cm2. In order to obtain the effect of thinning combined with laser annealing process on forward conduction characteristics of medium voltage devices,1200V/20A JBS diode was developed, and the backside contact adopted the above two annealing schemes, the thickness of 4H-SiC substrate is 200μm. According to the statistical results of hundreds of JBS diodes, the electrical characteristics of the two types JBS are basically the same. Compared with the JBS diode without substrate thinning, the forward conduction voltage (VF) of the thinned JBS diode is decreased about 0.048V. When the substrate of 1200V SiC JBS diodes is reduced to 80μm, the value of VF can only be reduced by about 0.0868V.