Atomic Layer Deposition of High k Dielectric and Metal Gate Stacks for MOS Devices

Abstract

High‐k gate stack fabrication via atomic layer deposition (ALD) of ultra thin HfO2 and HfxSi1−xO2 films is demonstrated utilizing metal‐amide precursors and ozone as an oxidant. High resolution transmission electron microscopy (TEM) shows that films near 2.0 nm are reproducible. X‐ray reflectivity (XRR) and Rutherford backscattering (RBS) indicate that this ALD chemistry proceeds similarly on multiple surface preparations including HF last without growth incubation. High field mobility of more than 85% of the universal SiO2 mobility has been achieved at EOT ∼1nm with a reduction of more than two orders of magnitude in leakage current density as compared with a SiO2/poly Si gate. Various ALD metal nitrides such as TiN, HfN, HfSiN have been deposited on HfO2 and HfSiOx dielectrics which enabled a study of the interfacial reaction between high‐k dielectrics and metal electrode materials. The thermal stability of PVD Ru deposited on ALD HfO2 has also been observed.