Effect of Annealing on Ion Implantation Process in 4H-SiC power semiconductor devices

Abstract

In this paper, the effect of annealing at 1750°C for 30min on ion implantation results is analyzed in 4H-SiC power semiconductor devices are studied. The main method is to prepare the injection mask to separating P and P-space by lithography, etching and other processes. Then, the concentration of 5E18cm-3 Al ion is implanted at the high temperature of 500°C, and the 1# sample is retained. After the removal of the mask, the remaining samples are annealing at high temperature for 30min, and the 2# sample is retained. Schottky contact and Ohmic contact was prepared on the front and back side respectively, and sample 3# was prepared. Scanning electron microscopy (SEM), electron energy spectroscopy (EDX), secondary mass spectrometry (SIMS) and capacitance-voltage (C-V) tests were used to test the injection line and activation rate before and after annealing. The test results show that the P region of the ion implantation line of the 1# sample changes from 1.53um to 1.65um of the 2# sample before and after annealing, which indicates that the annealing at 1750 °C will make the implanted ion Al diffuse in SiC to a certain extent, resulting in a decrease in the implanted concentration per unit area. This is also proved by the results of the SIMS test. At the same time, high temperature annealing will repair the lattice, impurity ion Al replaces Si ion at high temperature, and bonds with C ion, so as to play a role and provide holes. Its activation rate has a very low value of 40%, which can be close to 100% after annealing.