The effect of gate oxidation method on the electrical properties of metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated on 4H-SiC C(000)
face has been investigated. In the case of SiC MOSFETs fabricated by dry gate oxidation, the peak value of field-effect mobility (μFE)
is 16.3 cm2/V s.
On the other hand, pyrogenic gate oxidation and pyrogenic gate oxidation followed by H2
postoxidation annealing (POA) considerably decreased the interface trap density (Dit)
and the threshold voltage, and markedly improved the μFE.
The depth profiles of hydrogen density were measured using secondary ion mass spectroscopy. These verified that pyrogenic gate oxidation increases hydrogen density at the SiO2/SiC
interface compared to dry gate oxidation, and that the pyrogenic gate oxidation followed by H2
POA increases considerably it. It is thought that the Dit
reduction might be caused by the passivation of interface states by –H or –OH. The peak value of μFE
for SiC MOSFETs fabricated by pyrogenic gate oxidation followed by H2
POA is 111 cm2/V s,
which is much higher than that of SiC MOSFETs fabricated on a Si(0001) face. Therefore, the 4H-SiC C(000)
face is suitable for the fabrication of SiC power MOSFETs. © 2004 American Institute of Physics.