Arsenic redistribution during rapid thermal chemical vapor deposition of TiSi2 on Si

This paper studies the redistribution behavior of implanted arsenic during selective rapid thermal chemical vapor deposition of titanium disilicide (TiSi2). The arsenic implant doses ranged from 3 x 10(14) cm(-2) to 5 x 10(15) cm(-2). The TiSi2 firms were deposited either directly on arsenic-implanted silicon substrates or on epitaxial silicon buffer layers selectively deposited with varying thicknesses before TiSi2 depositions. SiH4 and TiCl4 were used as precursors for TiSi2 depositions and Si2H6 and Cl-2 for selective silicon epitaxial growth. Experimental data revealed that the majority of the implanted arsenic was lost from the silicon substrate into the deposited TiSi2 films when epitaxial silicon buffer layers were not employed. With the inclusion of the buffer layer, the arsenic loss could be reduced significantly. The loss of arsenic observed could not be explained by considering substrate consumption alone. In both cases, arsenic exhibited strongly enhanced out-diffusion from the silicon substrate into the TiSi2 film. The injection of vacancies during the TiSi2 depositions has been proposed as the reason for this enhanced out-diffusion. Monte Carlo simulations have been performed to verify the proposed model. (C) 2001 The Electrochemical Society. All rights reserved.