Thin (equivalent oxide thickness T-eq of 2.4 nm) silicon nitride was deposited on Si substrates by atomic-layer deposition (ALD) at low temperatures (<550degreesC). 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.