Laser-induced titanium disilicide formation for submicron technologies

Abstract

Currently, a two-step anneal is employed for the formation of titanium selfaligned silicide (Salicide). The first rapid thermal anneal (RTA) step is to achieve the C49 TiSi2 phase, and the second step is to form the low resistivity C54 phase. However, as the width of the polysilicon line decreases, conversion of C49 to C54 TiSi2 becomes increasingly difficult. This is because the C49 to C54 phase transformation nucleates only at locations where three C49 grains intersect and the number of such intersection points is reduced as the gate length decreases. In this paper; we have investigated the effect of replacing the first RTA step by a laser anneal step on the formation of C54 TiSi2, with all other steps remaining unchanged. Our results show that the laser annealing process can form a fine-grained metastable C49 TiSi2 precursor layer. Upon subjecting this precursor layer to a second RTA step, C54 titanium disilicide can be obtained.