Improvement of TiN Flow Modulation Chemical Vapor Deposition from TiCl 4 and NH 3 by Introducing Ar Purge Time

• Published in: Japanese Journal of Applied Physics 2004-04, Vol.43 (4R), p.1619
• Main Authors: Jun, Keeyoung, Im, Ik-Tae, Shimogaki, Yukihiro
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.43.1619

TiN films were deposited by using TiCl 4 /NH 3 flow modulation chemical vapor deposition (FMCVD). FMCVD consists of repetitive TiN deposition periods by TiCl 4 /NH 3 , each of which is followed by Cl reduction period. TiN deposition periods are typically 3 s and Cl reduction periods are 1 s. The effect of the number of deposition/reduction cycles and the effect of the partial pressure of TiCl 4 and NH 3 on film uniformity and resistivity were investigated. For a total reduction period of 100 s, increasing the number of reduction periods from 100×1-s periods to 300×0.33-s periods decreased the step coverage. This decrease in coverage was due to residual TiCl 4 during the Cl reduction period by NH 3 that cleared out TiCl 4 at a constant rate, independent of the length of the period of reduction cycle. An Ar purge cycle was used between the deposition and reduction cycles to allow the residual TiCl 4 to clear out before the NH 3 was used for the film reduction cycle. This significantly improved the film step coverage from 50% to over 90%. The minimum film resistivity occurred when the NH 3 partial pressure was 0.25 Torr. NH 3 partial pressure less than 0.25 Torr inhibited film reduction, and NH 3 partial pressure higher than 0.25 Torr enhanced the deposition rate, which also inhibited film reduction. By using the optimum conditions determined in this study, we could obtain TiN films that had film resistivity of about 240 µΩ·cm and step coverage of about 98% at 410°C.