In-Situ Infrared Absorption Monitoring of Atomic Layer Deposition of Metal Oxides on Functionalized Si and Ge Surfaces

The nature of the interface between Si and Ge substrates and high-k dielectrics often controls the performance of MOSFET devices. Precleaning and/or chemical functionalization of the surfaces can dramatically affect the formation of an interfacial layer. We have used in-situ IR spectroscopy to probe the relevant interfaces during ALD growth for a variety of surface treatments, including H- and Cl-termination, and nitridation. This paper focuses on understanding of the mechanisms for interfacial SiO 2 (or GeO x ) formation during HfO 2 growth using tetrakis-ethylmethylamidohafnium (TEMAH) as the metal precursor and water or ozone as the oxygen precursor. We find that impurities arising from incomplete ligand elimination during growth (e.g. OH for H 2 O processing and CO- and NO-containing species for O3 processing) are incorporated into the HfO 2 film during growth. Upon annealing, most of these species react, but can also migrate to the interface. Nitridation of Si and Ge surfaces will in general prevent SiO2 or GeO x formation but can also affect the growth rate.