Semiconductor device and method for fabricating the same

A semiconductor device comprising:

• an insulating film formed over a semiconductor substrate;
• an interconnect groove formed in the insulating film;
• a barrier film covering bottom and side surfaces of the interconnect groove;
• and
• a metal film filling the interconnect groove covered with the barrier film,
• wherein a portion of the barrier film covering the side surface of the interconnect groove is thicker than a portion thereof covering the bottom surface of the interconnect groove.

A semiconductor device comprising:

• a lower interconnect formed over a semiconductor substrate;
• an insulating film formed on the lower interconnect;
• a via hole penetrating the insulating film to reach the lower interconnect;
• a barrier film covering bottom and side surfaces of the via hole;
• and
• a metal film filling the via hole covered with the barrier film,
• wherein the bottom surface of the via hole is positioned below the interface between the lower interconnect and the insulating film, and
• the top surface of a portion of the barrier film covering the bottom surface of the via hole is positioned above the interface between the lower interconnect and the insulating film.

A method for fabricating a semiconductor device, comprising:

• the step (a) of forming a lower interconnect over a semiconductor substrate;
• the step (b) of forming an insulating film on the lower interconnect;
• the step (c) of forming a via hole penetrating the insulating film to reach the lower interconnect;
• the step (d) of forming a first barrier film covering bottom and side surfaces of the via hole;
• and
• the step (e) of forming, after the step (d), a metal film filling the via hole,
• wherein in the step (d), the first barrier film is formed to have a thickness greater in a portion covering a lower end of the side surface of the via hole than in a portion covering the bottom surface of the via hole.