A semiconductor device includes an active fin extended in a first direction on a substrate. A gate structure extends in a second direction, wherein the gate structure intersects the active fin and covers an upper portion of the active fin. A source/drain region is positioned on the active fin adjacent to the gate structure. A silicide layer is on the source/drain region. A contact plug is connected to the source/drain region. A void is present between the silicide layer and the contact plug.