Patent ID: 6972250

Claim:
A method of forming a vertically self-aligned silicide contact to an underlying SiGe layer, said method comprising: forming a silicon layer to selectively cover a layer of SiGe in one or more regions, said silicon layer having a first predetermined thickness; forming a metal layer to cover said layer of SiGe and said silicon layer, said metal layer having a second predetermined thickness; forming a first silicide of said silicon layer and said metal layer by a first thermal annealing process at a first predetermined lower temperature; and forming a second silicide of said silicon layer and said metal layer by a second thermal annealing process at a second predetermined higher temperature, said first predetermined temperature selected from a temperature range having a lower threshold temperature comprising a temperature at which said silicon layer interacts with said metal layer to form any silicide, said second predetermined temperature selected from a higher temperature range having an upper temperature threshold comprising a temperature at which any silicide formed from said metal layer interacts with said SiGe layer, wherein: said first predetermined thickness and said second predetermined thickness provide thicknesses appropriate for forming said vertically self-aligned characteristic of said silicide contact, in which said silicon layer is essentially completely converted into one of said one first silicide and said second silicide, each of said first silicide and said second silicide is essentially composed of silicon and said metal and is essentially free of precipitates, and an interface between said SiGe layer and said first and second silicides is essentially free of precipitates.