Formation of titanium silicide on narrow gates using laser thermal processing

One of the crucial issues that must be faced when using titanium silicide in advanced IC structures is the difficulty encountered in transforming the silicide from its high to its low resistivity phase. As gate dimensions are reduced, there is a reduction in the number of nucleation sites available to initiate transformation on laterally and vertically confined films. In this paper we demonstrate a novel technique, using a pulsed excimer laser, to produce thicker silicides over the gate than over the source and drain regions. This is difficult to achieve using conventional thermal processing. The increased thickness of silicide over the gate region assists in alleviating the phase transformation constraints. In this paper, we demonstrate fabrication of low resistivity salicide on gate lengths as small as 0.07 μm. We also demonstrate, through the use of two-dimensional thermal simulations, the use of amorphization as a method for overcoming the barriers to integration of laser thermal processing in conventional MOSFET fabrication