Low-temperature formation of highly reliable silicon-nitride gate dielectrics with suppressed soft-breakdown phenomena for advanced complementary metal–oxide–semiconductor technology

Abstract

Thin (equivalent oxide thickness Teq of 2.4 nm) silicon nitride was deposited on Si substrates by atomic-layer deposition (ALD) at low temperatures (<550 °C). Substantial enhancement of reliability was obtained with respect to the conventional SiO2 samples. An exciting feature of suppressed soft breakdown events was observed. Injected-carrier-induced physical damage, which results in the formation of the conductive filaments at the poly-Si/ALD-Si-nitride and ALD-Si-nitride/Si-substrate interfaces, is suppressed due to the higher stability of the Si–N bonds than that of the strained Si–O bonds. This suppression of physical damage leads to enhanced reliability. Therefore, the ALD silicon nitride can be a good choice for a highly reliable ultrathin gate dielectric in deep submicron complementary metal–oxide–semiconductor technology.