Semiconductor device including metal silicide layer and fabrication method thereof

A semiconductor device comprising:

• a substrate having an active region and an isolation region;
• a plurality of gate stack structures, each of gate stack structures locating between a first source/drain region and a second source/drain region;
• a plurality of channel regions under the corresponding gate stack structures, each of channel regions having a first LDD junction region formed between the first source/drain region and one end of the channel region and a second LDD junction region formed between the second source/drain region and the other end of the channel region;
• a metal silicide layer having a first metal formed on the active region other than the plurality of gate structures;
• an insulating layer having a plurality of openings to expose the metal silicide layer;
• and
• a plurality of conductive layers filling the openings and contacting the metal silicide layer, wherein each of the plurality of conductive layers includes a barrier layer having the first metal and a contact plug, and wherein the barrier layer is formed on an inner sidewall of the plurality of openings and the contact plug is formed on the barrier layer, and wherein the barrier layer and the contact plug are in direct contact with the metal silicide layer.