Silicides for Highly Integrated Memory and Logic Circuits

Abstract

ABSTRACTState of the art DRAM and logic processes widely make use of silicides formed by refractory metals like Ta, Mo, W, Ti, Co, or others. The methods for silicide formation range from sputtering, reaction with predeposited metal, to selective CVD deposition.The most common application of silicides in state of the art CMOS processes is to use them as a conducting layer that can withstand high temperature processes and that has a significantly lower sheet resistivity than doped mono or poly crystalline silicon. Besides their role as a temperature stable conductor silicides have further interesting properties when using them as a diffusion source for impurities to generate shallow junctions, or as an alternative gate material with a work function in the middle of the silicon band gap.Based on the example of the self aligned silicidation with titanium silicide the limitations of the state of the art technology will be shown and requirements for future applications will be discussed.