Method of manufacturing semiconductor device and semiconductor device

A method of manufacturing a semiconductor device, comprising:

• forming a lower-layer interconnection;
• forming a protective film on a surface of the lower-layer interconnection;
• forming a multilayer-structured film by stacking a first porous film, a first non-porous film, a second porous film, and a second non-porous film on a surface of the protective film in this order;
• forming a via hole in the first porous film and the first non-porous film, and forming an interconnect trench communicating with the via hole in the second porous film and the second non-porous film, by dry etching the multilayer-structured film using a resist mask;
• removing the protective film exposed at a bottom of the via hole;
• removing the resist mask after removing the protective film;
• and
• forming an upper-layer interconnection of dual damascene structure by embedding an interconnect material in the via hole and the interconnect trench, upper-layer interconnection being connected to the lower-layer interconnection,
• wherein for the first non-porous film, used is a multilayer film including at least two layers in which a first layer, which is located close to the first porous film, is made of a material that has a high etching selectivity ratio relative to the resist mask, and a second layer, which is located closer to the second porous film than the first layer is, is made of a material that has a high etching selectivity ratio relative to the protective film and the second porous film.

A semiconductor device, comprising:

• a lower-layer interconnection formed on a semiconductor substrate with an insulating film interposed therebetween;
• a protective film formed on a surface of the insulating film, including on the lower-layer interconnection;
• a multilayer-structured film formed by stacking at least a first porous film, a first non-porous film, and a second porous film on a surface of the protective film in this order;
• and
• an upper-layer interconnection of dual damascene structure formed in the protective film and the multilayer-structured film, the upper-layer interconnection including a via plug part connected to the lower-layer interconnection and an interconnect part connected to the via plug part with a boundary of the first non-porous film,
• wherein the first non-porous film is a multilayer film including at least two layers, the first non-porous film including any one of the layers is made of a material which has a high etching selectivity ratio relative to the protective film, a layer located close to the first porous film is made of a material which has a high etching selectivity ratio relative to a layer located close to the second porous film, and a layer located close to the second porous film is made of a material which has a high etching selectivity ratio relative to the second porous film.