Hollow Cathode Plasma (HCP) Enhanced Atomic Layer Deposition of Silicon Nitride (SiN x ) Thin Films Using Pentachlorodisilane (PCDS)

Silicon nitride (SiN x ) films have drawn great attention due to the wide range of applications such as passivation layer, gate dielectric, spacer, charge trap layer, and diffusion barrier [1]. Conventionally used LPCVD and PECVD for SiN x deposition have limitations in terms of conformal deposition and thickness scalability. Since plasma enhanced atomic layer deposition (PEALD) is expected to overcome these shortcomings, several research groups have reported SiN x film deposition. A number of studies on PEALD SiN x process using various chlorine-containing silicon precursors have been reported due to their ease in synthesis as well as good thermal stability [2]. Recently, PEALD SiN x film using a novel chlorosilane precursor, pentachlorodisilane (PCDS, HSi 2 Cl 5 ) with NH 3 /N 2 plasma was reported [3]. Under the NH 3 /N 2 plasma condition, PCDS enhanced the growth rate (approximately > 20 %) compared to the hexachlorodisilane (HCDS, Si 2 Cl 6 ), but still showed relatively poor wet etch resistance. Inspired the film characteristics, we propose to explore the feasibility of improving the wet etch resistance of PEALD-SiN x films using the different gas mixture for plasma. It has been reported that the wet etch rate of SiN x films has a linear relationship with the hydrogen concentration in the films [1]. Compared to NH 3 /N 2 plasma, N 2 -H 2 (forming gas) plasma improves the wet etch rate possibly due to less N-H and H-N-H bonds in the SiN x films [2]. Herein, PEALD SiN x films using PCDS as Si precursor and N 2 -H 2 (10 % forming gas) plasma as the reactant were evaluated. The combination with PCDS and N 2 -H 2 plasma showed a relatively lower (approximately < 10 %) growth rate than NH 3 /N 2 plasma under a range of process temperatures (270−300 °C) whereas the wet etch resistance to HF acid was improved (> 1.5 nm/min, 500:1 HF). Studying these results, we suggest the effect of hydrogen on film properties such as growth rate, film composition, and wet etch resistance. [1] H.S. Kim, X. Meng, S.J. Kim, A.T. Lucero, L. Cheng, Y.C. Byun, J.S. Lee, S.M. Hwang, A.L.N. Kondusamy, R.M. Wallace, G. Goodman, A.S. Wan, M. Telgenhoff, B.K. Hwang, and J. Kim, ACS Appl. Mater. Interfaces 10 , 44825 (2018). [2] X. Meng, Y.C. Byun, H.S. Kim, J.S. Lee, A.T. Lucero, L. Cheng, and J. Kim, Materials 9 , 1007 (2016). [3] X. Meng, H.S. Kim, A.T. Lucero, S.M. Hwang, J.S. Lee, Y.C. Byun, J. Kim, B.K. Hwang, X. Zhou, J. Young, and M. Telgenhoff, ACS Appl. Mater. Interfaces 10 ,