Please cite this article in press as: L.L. Yusup, et al., Surface reaction of silicon chlorides during atomic layer deposition of silicon nitride, Appl. Surf. Sci. (2017), http://dx.doi.org/10.1016/j.apsusc.2017.06.060 ARTICLE IN PRESS G Model APSUSC-36260; No. of Pages 5 Applied Surface Science xxx (2017) xxx–xxx Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc Full Length Article Surface reaction of silicon chlorides during atomic layer deposition of silicon nitride Luchana L. Yusup a , Jae-Min Park a , Tirta R. Mayangsari a , Young-Kyun Kwon b,∗ , Won-Jun Lee a,∗ a Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Korea b Department of Physics and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Korea a r t i c l e i n f o Article history: Received 31 October 2016 Received in revised form 4 June 2017 Accepted 5 June 2017 Available online xxx Keywords: Density functional theory (DFT) Atomic layer deposition (ALD) Silicon nitride Silicon chlorides Surface reaction a b s t r a c t The reaction of precursor with surface active site is the critical step in atomic layer deposition (ALD) process. We performed the density functional theory calculation with DFT-D correction to study the surface reaction of different silicon chloride precursors during the first half cycle of ALD process. SiCl 4 , SiH 2 Cl 2 , Si 2 Cl 6 and Si 3 Cl 8 were considered as the silicon precursors, and an NH/SiNH 2 *-terminated silicon nitride surface was constructed to model the thermal ALD processes using NH 3 as well as the PEALD processes using NH 3 plasma. The total energies of the system were calculated for the geometry-optimized structures of physisorption, chemisorption, and transition state. The order of silicon precursors in energy barrier, from lowest to highest, is Si 3 Cl 8 (0.92 eV), Si 2 Cl 6 (3.22 eV), SiH 2 Cl 2 (3.93 eV) and SiCl 4 (4.49 eV). Silicon precursor with lower energy barrier in DFT calculation showed lower saturation dose in literature for both thermal and plasma-enhanced ALD of silicon nitride. Therefore, DFT calculation is a promising tool in predicting the reactivity of precursor during ALD process. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Silicon nitride is one of the most popular dielectric materials in semiconductor manufacturing process due to its unique proper- ties, such as high etching selectivity against silicon oxide, superior diffusion barrier against copper or alkali ions, high charge trap density, and high dielectric constant. Major application of silicon nitride includes the sidewall spacer of CMOS device [1] and the charge trap layer in three-dimensional NAND flash device [2]. Sil- icon nitride thin films have been produced by low-pressure or plasma-enhanced chemical vapor deposition (CVD) techniques, and recently atomic layer deposition (ALD) technique was intro- duced for better step coverage and better film quality at lower temperatures. Silicon chloride precursors, such as SiCl 4 [3], SiH 2 Cl 2 [4,5] and Si 2 Cl 6 [6], were used as the silicon precursors with ammo- nia or hydrazine [8] as reactants in the thermal ALD of silicon nitride at 450 ◦ C or higher temperatures. Plasma-enhanced ALD (PEALD) process is gaining attention due to lower deposition tem- perature and lower saturation dose as compared with thermal ALD. ∗ Corresponding authors. E-mail addresses: ykkwon@khu.ac.kr (Y.-K. Kwon), wjlee@sejong.ac.kr (W.-J. Lee). PEALD of silicon nitride using silicon chloride precursors, such as SiH 2 Cl 2 [7] and Si 2 Cl 6 [8], with NH 3 plasma were reported at lower deposition temperatures below 400 ◦ C. The high reactivity of plasma species can give opportunity to use various precursors in deposition process, and the PEALD using aminosilane precursors, such as trisilylamine (TSA) [9], bis(tert-butylamino)silane (BTBAS) [10,11] and tris(dimethylamino)silane (TDMAS) [12], were also reported. Experimental and theoretical studies comparing nitrid- ing agents showed that N 2 plasma gives the highest growth rate in PEALD using BTBAS, and N 2 /H 2 or NH 3 plasma produces hydrogen- terminated silicon nitride surface which hinders the reaction of aminosilane precursor with the surface [13]. Only few theoretical study described the effect of silicon pre- cursors in thermal ALD or PEALD of silicon nitride. In our previous work [14], we reported the effect of different surface active sites of silicon nitride on the reactivity of silicon chloride precursors, SiCl 4 and Si 2 Cl 6 . Density functional theory (DFT) calculation showed that the reaction of silicon chlorides on NH/SiNH 2 *-terminated surface were plausible due to exothermic energy of chemisorption reac- tion. We also found out that different precursors can give different reactivity towards the surface. Therefore, in the present work we focuses on comparison of the reactivity of different silicon chloride precursors. ALD processes of silicon nitride using silicon chloride precursors are popular http://dx.doi.org/10.1016/j.apsusc.2017.06.060 0169-4332/© 2017 Elsevier B.V. All rights reserved.