Initial Surface Reaction of Di-Isopropylaminosilane on a Fully Hydroxyl-Terminated Si (001) Surface

Abstract

We studied the interaction of di-isopropylaminosilane (SiH3N(C3H7)2, DIPAS) molecules with a fully hydroxyl-terminated Si (001) surface for SiO2 thin-film growth by using density functional theory. The amino group consisting of DIPAS was chosen in order to obtain a high adsorption energy because its lone-pair electrons in the N atom would help in the adsorption of DIPAS. The absolute value of the adsorption energy (0.67 eV) of DIPAS was higher than its reaction energy barrier of 0.38 eV. Thus, DIPAS could react with the surface without desorption. The reaction between DIPAS and the surface produced a silyl group (-SiH3) as a primary product and di-isopropylamine (NH(C3H7)2, DIPA) as a by-product. A second DIPAS, which was adsorbed near the pre-adsorbed DIPAS or -SiH3 with DIPA, required higher reaction energy barriers of 3.91 or 1.92 eV, respectively, because of its interaction with the first DIPAS or DIPA. However, when the second DIPAS was adsorbed near -SiH3 without DIPA, a low reaction energy barrier of 0.42 eV was required, indicating a negligible effect of -SiH3 on the second DIPAS reaction. Therefore, to obtain a highly dense Si layer, DIPA must desorb from the surface. DIPA requires a relatively high desorption energy of 0.40 eV because the lone-pair electrons in the N atom of DIPA also enhance its adsorption on the surface. The high desorption energy could reduce the process window of atomic layer deposition.

Design of efficient mono-aminosilane precursors for atomic layer deposition of SiO2 thin films

“…12,25 Recently, various alkylaminosilane-based molecules with appropriately reactive functional ligands have been evaluated and tested with the aim to identify most suitable precursors for SiO 2 thin lm growth both experimentally [26][27][28][29][30][31][32] and theoretically. [15][16][17][33][34][35] It was found that an increase in the degree of alkylamino substitution on Si atom would result in a reduced deposition rate and a use of tris(alkylamino)silane-based precursors may lead to a higher degree of impurity in the lms, especially in a low temperature range of the ALD window. 18,36 For example, the dissociative chemisorption of tris(dimethylamino)silane (TDMAS) occurs only up to the second step with dimethylaminosilylenyl fragment anchored on the surface, which would give rise to surface impurity.…”

Bottom-up plasma-enhanced atomic layer deposition of SiO2 by utilizing growth inhibition using NH3 plasma pre-treatment for seamless gap-fill process

“…The surface functional groups and their chemistry and density strongly influence the growth behavior in the ALD process. In the SiO 2 PE-ALD process, the Si–OH bonding, generally called the hydroxyl group, contributes to the ligand exchange reaction with diisopropylamino silane (DIPAS) (Si precursor) 15 , 24 . The Si–OH bonding on the surface is changed to Si (from the surface) –O–Si (from the DIPAS) –H 3 during the precursor feeding step 24 .…”

Effects of H2 and N2 treatment for B2H6 dosing process on TiN surfaces during atomic layer deposition: an ab initio study

“…In addition, PBE-D2 predictions have proven useful for prediction of the dissociative reactions of various molecules on different surfaces as shown by the numerous studies on the dissociation of different large molecules on Au (gold), 46 oxygen reduction reaction on Co(acetylaetonate) 2 , 47 water dissociation on mackinawite (FeS), 48,49 and the dissociative reaction of silicon precursor on Si. 50 To calculate the transition state, the distance between the two dissociative atoms was slightly separated, and energy relaxation was performed with the constrained distance. The same procedures were carried out until the force between two dissociative atoms became almost zero at the saddle point energy.…”

“…In addition, PBE-D2 predictions have proven useful for prediction of the dissociative reactions of various molecules on different surfaces as shown by the numerous studies on the dissociation of different large molecules on Au (gold), 46 oxygen reduction reaction on Co(acetylaetonate) 2 , 47 water dissociation on mackinawite (FeS), 48,49 and the dissociative reaction of silicon precursor on Si. 50 …”