Semiconductor device and having trench interconnection

A semiconductor device comprising:

• a first interconnection layer which is formed on an upper side of a substrate, and includes a first interconnection metal;
• and
• an interlayer insulating layer which is formed on said first interconnection layer, and includes a second interconnection metal formed within said interlayer insulating layer and a via formed within said interlayer insulating layer, said via connected with said first interconnection metal at one end thereof and connected with said second interconnection metal at the other end thereof;
• wherein said interlayer insulating film has a relative dielectric constant lower than that of a silicon oxide film;
• at least one of a portion corresponding to a sidewall of said via and a portion corresponding to a sidewall of said second interconnection in said interlayer insulating layer is in at least one of a nitrided state and a carbonized state;
• and
• an upper portion of said interlayer insulating layer includes a silicon oxide film, a silicon nitride film and a silicon oxide film in order from a lower portion of said interlayer insulating layer.