Properties of N-rich Silicon Nitride Film Deposited by Plasma-Enhanced Atomic Layer Deposition

• Published in: Solid-state electronics 2017-07, Vol.133, p.10-16
• Main Authors: Jhang, Pei-Ci, Lu, Chi-Pin, Shieh, Jung-Yu, Yang, Ling-Wu, Yang, Tahone, Chen, Kuang-Chao, Lu, Chih-Yuan
• Format: Article
• Language: English
• Subjects: Charge-trapping; Metal-Al2O3-oxide-nitride-oxide-silicon (MAONOS) and retention; N-rich silicon nitride; Plasma-enhanced atomic layer deposition (PEALD)
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/j.sse.2017.04.005

•N-rich silicon nitride film with a wide range N/Si ratio by PEALD process.•Study the kinetics of the PEALD process for N-rich silicon nitride films.•The application of N-rich silicon nitride films as charge-trapping layer in MAONOS devices. An N-rich silicon nitride film, with a lower refractive index (RI) than the stoichiometric silicon nitride (RI=2.01), was deposited by alternating the exposure of dichlorosilane (DCS, SiH2Cl2) and that of ammonia (NH3) in a plasma-enhanced atomic layer deposition (PEALD) process. In this process, the plasma ammonia was easily decomposed to reactive radicals by RF power activating so that the N-rich silicon nitride was easily formed by excited ammonia radicals. The growth kinetics of N-rich silicon nitride were examined at various deposition temperatures ranging from 400°C to 630°C; the activation energy (Ea) decreased as the deposition temperature decreased below 550°C. N-rich silicon nitride film with a wide range of values of refractive index (RI) (RI=1.86–2.00) was obtained by regulating the deposition temperature. At the optimal deposition temperature, the effects of RF power, NH3 flow rate and NH3 flow time were on the characteristics of the N-rich silicon nitride film were evaluated. The results thus reveal that the properties of the N-rich silicon nitride film that was formed by under plasma-enhanced atomic layer deposition (PEALD) are dominated by deposition temperature. In charge trap flash (CTF) study, an N-rich silicon nitride film was applied to MAONOS device as a charge-trapping layer. The films exhibit excellent electron trapping ability and favor a fresh cell data retention performance as the deposition temperature decreased.