Semiconductor devices and methods of forming the same

A method of forming a semiconductor device, comprising:

• providing a substrate having a gate stack thereon, an epitaxial layer therein, and a dielectric layer aside the gate stack and over the epitaxial layer;
• forming an opening through the dielectric layer, the opening exposing the epitaxial layer;
• forming a first metal layer on a sidewall and a bottom of the opening, wherein a first melting point of the first metal layer is about 1700° C. or higher;
• removing the first metal layer from the sidewall of the opening;
• forming a second metal layer on the sidewall and the bottom of the opening, wherein the second metal layer is in contact with the first metal layer;
• performing a first annealing process, so as to silicidize the first metal layer and the second metal layer on the epitaxial layer and therefore form a silicide layer or a silicon-germanide layer on the epitaxial layer;
• removing the second metal layer from the sidewall of the opening;
• and
• forming a connector over the silicide layer or the silicon-germanide layer in the opening.

A semiconductor device, comprising:

• a substrate having at least one fin;
• a gate stack across the at least one fin;
• an epitaxial layer in the substrate aside the gate stack;
• a connector disposed over the epitaxial layer;
• and
• a metal silicon-germanide layer disposed between the epitaxial layer and the connector, wherein the metal silicon-germanide layer comprises a metal having a melting point of about 1700° C. or higher.