Laser thermal processing for shallow junction and silicide formation

Abstract

Verdant Technologies is developing Laser Thermal Processing (LTP) as an alternative to rapid thermal annealing (RTA) for ultra-shallow junction and self-aligned silicide contact formation. Although new, the laser-based technology is a strong contender in the area of contact formation because it offers superior technical performance. The control of dopant diffusion and improvement in activation offered by LTP has led to junctions shallower than 35 nm and with sheet resistance lower than 100 (Omega) /square. Titanium silicide has been shown to form on linewidths down through 0.07 micrometer -- effectively extending the useful lifetime of titanium silicide processing. In addition, the laser-based process allows the silicide thickness over source/drain and gate regions, for both cobalt and titanium, to be controlled independently. This has resulted in gate resistivity of 1 (Omega) /square on linewidths down to 0.07 micrometer. In the Verdant approach, laser light is used to heat the silicon through an absorption process, directly driving the doping or silicidation process in a non-equilibrium and area-specific manner. These aspects of the process allow ultra-shallow contact formation with significantly lower electrical resistance in the silicon and silicide.