Semiconductor device and production method therefor

A method of manufacturing a semiconductor device comprising the steps of:

• forming a concave portion in an insulating film formed on a substrate;
• forming a barrier layer on an inner surface of said concave portion and on a surface of said insulating film and forming a conductive layer on the surface of said insulating film to be embedded in said concave portion through said barrier layer;
• removing said conductive layer such that said conductive layer is left in said concave portion and removing said barrier layer on a surface of said insulating film such that a top end of said barrier layer left in said concave portion is between a side of said conductive layer and a side wall of said concave portion;
• and
• forming a cobalt tungsten phosphorus coating to connect with said barrier layer on the side of said conductive layer and to selectively cover said conductive layer on an opening side of said concave portion with electroless plating.