FORMATION OF A CRYSTALLINE METAL-RICH SILICIDE IN THIN-FILM TITANIUM SILICON REACTIONS/

In-situ X-ray diffraction during rapid thermal annealing at rates from 3 to 20 degrees C s(-1) was used to study the formation of titanium s ilicide phases from a thin film of Ti and doped single-crystal or undo ped polycrystalline silicon substrates. In all cases, a metal-rich sil icide (identified as either Ti5Si4 or Ti5Si3) was the first crystallin e phase to form between 500 and 550 degrees C, followed by C49-TiSi2 b etween 575 and 600 degrees C. The formation of C49-TiSi2 completely co nsumed the metal-rich silicide before transforming into the low-resist ance C54-TiSi2 phase at approximately 800 degrees C. These results ind icate that while there is sufficient thermodynamic driving forces to n ucleate both a metal-rich silicide and C49-TiSi2 the subsequent growth of C49-TiSi2 is kinetically favored over the growth of Ti5Si4 or Ti5S i3.