Ultrathin silicon nitride gate dielectrics prepared by catalytic chemical vapor deposition at low temperatures

Abstract

The feasibility of using ultrathin silicon nitride (SiNx) films, prepared by catalytic chemical vapor deposition (Cat-CVD) method, as an ultrathin gate dielectric is reported. The effects of postdeposition treatments carried out using hydrogen (H2)-decomposed species or NH3-decomposed species formed by catalytic cracking of H2 and NH3 are also studied. A small hysteresis loop is seen in the C–V curve of as-deposited Cat-CVD SiNx films. The leakage current in the case of these films with equivalent oxide thickness (EOT) of 3 nm is slightly larger than that in the conventional thermal SiO2 films of similar EOT. However, it is found that the properties of Cat-CVD SiNx films are markedly improved by the postdeposition H2 or NH3 treatments, that is, the hysteresis loop disappears and the leakage current decreases by three orders of magnitude.