A semiconductor device is provided. A semiconductor device includes: a lower metal layer including first, second, and third conductive patterns spaced apart from each other in a first insulating film; first and second interlayer insulating films between the first and second conductive patterns and between the second and third conductive patterns, respectively, so as to be spaced apart from each other; a via metal layer inside a recess on the lower metal layer and electrically connected to the lower metal layer; and a second insulating film at least partially surrounding side surfaces of the via metal layer and having a first insulating film portion on a concave portion between the first and second interlayer insulating films and a second insulating film portion on the first insulating film portion, wherein a carbon concentration in the first insulating film portion is higher than a carbon concentration in the second insulating film portion.