Electrical Characterization and Reliability of Nitrided-Gate Insulators for N- and P-Type 4H-SiC MIS Devices

摘要

In this paper, nitrided insulators such as N_2O-grown oxides, deposited SiO_2 annealed in N_2O, and deposited SiN_x/SiO_2 annealed in N_2O on thin-thermal oxides have been investigated for realization of high performance n- and p-type 4H-SiC MIS devices. The MIS capacitors were utilized to evaluate MIS interface characteristics and the insulator reliability. The channel mobility was determined by using the characteristics of planar MISFETs. Although the N_2O-grown oxides are superior to the dry O_2-grown oxides, the deposited SiO_2 and the deposited SiN_x/SiO_2 exhibited lower interface state density (n-MIS: below 7×10~(11) cm~(-2)eV~(-1) at E_C-0.2 eV, p-MIS: below 6×10~(11) cm~(-2)eV~(-1) at E_V+0.2 eV) and higher channel mobility (n-MIS: over 25 cm~2/Vs, p-MIS: over 10 cm~2/Vs). In terms of reliability, the deposited SiO_2 annealed in N_2O exhibits a high charge-to-breakdown over 50 C/cm~2 at room temperature and 15 C/cm~2 at 200°C. The nitrided-gate insulators formed by deposition method have superior characteristics than the thermal oxides grown in N_2O.