In-Situ Infrared Spectroscopy and Density Functional Theory Modeling of Hafnium Alkylamine Adsorption on Si−OH and Si−H Surfaces

Abstract

In-situ attenuated total internal reflection infrared spectroscopy has been used to examine initial adsorption and reaction steps in atomic layer deposition of HfO 2 from tetrakis(diethylamino) hafnium (TDEAHf) on SiO 2 and hydrogen-terminated Si(100) surfaces. At low deposition temperatures (25-250 °C), TDEAHf directly reacts with the Si-H surface, resulting in partial removal of Si-H bonds and formation of a four-membered Si-O-Hf-Si bonding structure that can rapidly oxidize. The hydrogen removal process is observed to continue through many cycles of TDEAHf/H 2 O exposure, signifying continued reactivity of the Hf precursor with the silicon surface. Density functional theory calculations have been performed for various reactions between tetrakis(dimethylamino) hafnium and Si-H surfaces, and several possible reaction pathways for hydrogen removal have been identified and analyzed. The calculations suggest that hydrogen removal proceeds by H abstraction by an amine ligand of the Hf precursor and that the abstraction reaction is made more facile by the presence of OH on the otherwise H-terminated Si surface.

Chemical manipulation of multifunctional hydrocarbons on silicon surfaces

“…For example, the work of the groups of Kelly et al suggested that the oxygen impurities play a crucial role in the interface formation when aluminum oxide deposition is attempted on H-passivated Si(100) substrate [453]. A similar conclusion was reached by the analysis of hafnium alkylamine adsorption on H-covered Si (100) substrate by the groups of Musgrave and Parsons [454], where the reaction of tetrakis-(diethylamino)-hafnium was deemed unlikely on an ideal H-terminated Si(100) surface. Thus, instead of an ideal interface that is often presented in the ALD schemes, the impurities, and not the plain surface, may play the determining role.…”

Chemistry of Diffusion Barrier Film Formation: Adsorption and Dissociation of Tetrakis(dimethylamino)titanium on Si(100)-2 × 1

“…55 Other groups have also considered the same basis set for describing the reactions of adsorption of organohafnium compounds on silicon. 56 Energies corresponding to selected structures optimized with the LANL2DZ basis set were compared to single-point calculations using a more expensive basis set, 6-311+G(d,p). Table 1 discussed below shows very good agreement between the two basis sets.…”

Chemistry of Organometallic Compounds on Silicon: The First Step in Film Growth

“…[38,39] In particular, the adsorption of tetrakisdimethylamidohafnium, [Hf{NA C H T U N G T R E N N U N G (CH 3 ) 2 } 4 ] or TDMAH, on a hydrogen terminated SiA C H T U N G T R E N N U N G (100) surface has been studied by a combination of experimental and theoretical methods. [39] A room-temperature reaction is observed, but only to a limited extent and by using large doses of TDMAH. The ALD performed at 523 K with TDMAH and water shows that SiÀH species are present on a surface even after 100 reaction cycles at this temperature.…”