Interaction of TEMAHf precursor with OH-terminated Si (001) surface: a first principles study.

We performed a first principles study to investigate the interaction of tetrakis-ethylmethylaminohafnium (4[(C2H5)(CH3)N]Hf, TEMAHf) precursors with an OH-terminated Si (001) surface that is the initial stage of atomic layer deposition (ALD). When TEMAHf reacted on the OH-terminated Si surface, there were two reaction mechanisms. One was the reaction with one -OH, and the other was the reaction with two -OH's. When TEMAHf reacted with an -OH on the Si (001) surface, an ethylmethylamine ((C2H5)(CH3)NH, EMA) was produced as a by-product and the trikis-ethylmethylaminohafnium group (3[(C2H5)(CH3)N]Hf) was attached to the O atom of the -OH. There were five reaction sites for TEMAHf to react with two -OH's to form the dikis-ethylmethylaminohafnium group (2[(C2H5)(CH3)N]Hf): Inter-dimer, intra-dimer, inter-row, cross-dimer, and cross-row. The reaction with two -OH's on the inter-dimer, intra-dimer, and inter-row sites were more favorable than the reaction with one -OH. Since the inter-dimer reaction was the most favorable, the energy barrier on the inter-dimer site for the reaction of the trikis-ethylmethylaminohafnium group with -OH to form the dikis-ethylmethylaminohafnium group was calculated, and the result was 0.19 eV. An extra energy of 0.25 eV was needed to remove EMA from the surface. Four TEMAHf's reacted with the surface and these reactions were exothermic by -7.77 eV, and the calculated Hf coverage of the first-half ALD cycle was 1.67 x 10(14)/cm2.