Templating Effects On C54-Tisi₂ Formation In Ternary Reactions.

Abstract

Titanium disilicide (C54-TiSi2) is a low resistivity silicide (15 - 20 μ-cm) and is widely used in the device industry. It is formed at about 750-850 °C when thin layers (∼30- lOOnm) of Ti on poly- or single-crystal Si substrates are subjected to rapid thermal annealing (3 °C/sec) in a controlled atmosphere (N2). During the anneal, other Ti silicides such as Ti5Si3, Ti5Si4,TiSi and C49-TiSi2 may form prior to the desirable C54-TiSi2. Some attempts have been made to promote low-temperature C54-TiSi2 formation. Depositing a Mo (l-2nm) interlayer between Ti and Si has been reported to decrease the C54 formation temperature by 100 °C.2 Codepositing Ti with Ta, Nb or Mo has successfully decreased the formation temperature by about 150 °C.3 These findings have been interpreted in terms of a template mechanism which facilitates formation of C54 by advantageous lattice matching between similar planes in C54 and a hexagonal ternary (Ti- X-Si, X=Ta, Nb, Mo) C40 precursor phase.