Atomic-layer deposition of ZrO2 with a Si nitride barrier layer

Abstract

ZrO 2 thin films for gate dielectrics have been formed at low temperatures (200 °C) by an atomic-layer deposition (ALD) technique using Zr(t-OC4H9)4 and H2O source gases. An ultrathin (physical thickness Tphy of ∼0.5 nm) Si nitride layer was deposited on a Si substrate by ALD before the deposition of ZrO2. Transmission electron microscopy showed that the Si nitride barrier layer successfully suppressed the formation of a SiO2 interfacial layer. Because of the extremely uniform thickness control capability in the ultrathin region and the low thermal budget of the ALD process, the ALD process for the ZrO2/Si nitride stack structure is a promising candidate for fabricating the ultrathin gate dielectrics for sub-0.1-μm complementary metal–oxide–semiconductor transistors.