Semiconductor devices including silicide regions and methods of fabricating the same

A semiconductor device, comprising:

• a substrate including a first region and a second region;
• a device isolation layer in the substrate and which demarcates a first active region in the first region of the substrate and a second active region in the second region of the substrate;
• a PMOS transistor disposed at the first region of the substrate, the PMOS transistor comprising a first gate electrode located on the first active region,
• first and second epitaxial regions located in the first active region at opposite sides of the first gate electrode, respectively, the first and second epitaxial regions both comprising SiGe, and
• first and second silicide layers on upper surfaces of the first and second epitaxial regions, respectively, wherein at least a portion of each of the first and second silicide layers is devoid of germanium and comprises Si—Y, where Y is a metal or metal alloy;
• and
• an NMOS transistor disposed at the second region of the substrate and electrically connected to the PMOS.

A method of fabricating a semiconductor device, comprising:

• forming a gate electrode structure comprising a gate electrode on an active region of a substrate;
• forming first and second epitaxial regions in the active region at opposite sides of the gate electrode structure, respectively;
• forming a silicon layer on the first and second epitaxial regions including by depositing silicon on each of the first and second epitaxial regions;
• and
• converting at least a portion of the silicon layer, on each of the first and second epitaxial regions, to a silicide.