Effects of N implantation before Gate Oxidation on the Performance of 4H-SiC MOSFET

The electrical characteristics of MOSFETs fabricated on 4H-SiC with a process based on N implantation in the channel region before the growth of the gate oxide are reported as a Function of the N concentration at the SiO(2)/SiC interface up to 6 x 10(19) cm(-3). The field effect mobility improves with increasing N concentration. At room temperature values change from 4 cm(2)/Vs for the not implanted sample up to 42 cm(2)/Vs for the sample with the highest N concentration. Furthermore, the field effect mobility increases with temperature and presents values above 60 cm(2)/Vs at 200 degrees C. The MOSFETs with the better electrical characteristics (higher mobility, lower threshold voltage, lower Subthreshold swing) were fabricated by a low thermal budget oxidation process, thank to the use of a high N implantation close able to produce all amorphous SiC surface layer. A strong correlation among the increasing of the N concentration at the SiO(2)/SiC interface, the reduction of the interface state density located near the conduction band and the improvement of the MOSFETs performance was obtained.