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 (T iSi2). 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-implant ed silicon substrates or on epitaxial silicon buffer layers selectively dep osited with varying thicknesses before TiSi2 depositions. SiH4 and TiCl4 we re used as precursors for TiSi2 depositions and Si2H6 and Cl-2 for selectiv e silicon epitaxial growth. Experimental data revealed that the majority of the implanted arsenic was lost from the silicon substrate into the deposit ed TiSi2 films when epitaxial silicon buffer layers were not employed. With the inclusion of the buffer layer, the arsenic loss could be reduced signi ficantly. The loss of arsenic observed could not be explained by considerin g substrate consumption alone. In both cases, arsenic exhibited strongly en hanced out-diffusion from the silicon substrate into the TiSi2 film. The in jection of vacancies during the TiSi2 depositions has been proposed as the reason for this enhanced out-diffusion. Monte Carlo simulations have been p erformed to verify the proposed model. (C) 2001 The Electrochemical Society . All rights reserved.