Characterization of MOS Capacitors Fabricated on n-type 4H-SiC Implanted with Nitrogen at High Dose
Aiming to minimize the interface state density, we fabricated MOS capacitors on n-type 4H-SiC by using wet oxidation of nitrogen implanted layers. We investigated a wide range of implantation dose, including a high dose able to amorphise a surface SiC layer with the intent to reduce the oxidation time. The oxide quality and the SiO2-SiC interface properties were characterized by capacitance-voltage measurements of the MOS capacitors. The proposed process, in which nitrogen is ion-implanted on SiC layer before a wet oxidation, is effective to reduce the density of interface states near the conduction band edge if a high concentration of nitrogen is introduced at the SiO2-SiC interface. We found that only the nitrogen implanted at the oxide-SiC interface reduces the interface states and we did not observe the generation of fixed positive charges in the oxide as a consequence of nitrogen implantation. Furthermore, the concentration of the slow traps evaluated from the Slow Trap Profiling technique was low and did not depend on the nitrogen implantation fluence.
N. Wright, C.M. Johnson, K. Vassilevski, I. Nikitina and A. Horsfall
A. Poggi et al., "Characterization of MOS Capacitors Fabricated on n-type 4H-SiC Implanted with Nitrogen at High Dose", Materials Science Forum, Vols. 556-557, pp. 639-642, 2007