Method for manufacturing semiconductor device and semiconductor device

A method for manufacturing a semiconductor device, comprising:

• forming an etching stopper on a semiconductor substrate;
• forming a porous film over said semiconductor substrate and said etching stopper;
• forming a resist film having a predetermined pattern over said porous film;
• forming a concave portion with a bottom thereof being an exposed surface of said etching stopper by etching said porous film through a mask of said resist film;
• forming a nonporous film so as to cover a whole of an interior wall of said concave portion and the surface of said porous film;
• selectively removing a portion of said nonporous film formed on the bottom of said concave portion, a portion of said non-porous film located on said porous film and a portion of said etching stopper by an anisotropic etch process to expose said semiconductor substrate;
• forming a barrier metal film so as to cover said porous film and the interior wall of said concave portion having said non-porous film on the side wall thereof;
• and
• forming a metallic film on said barrier metal film to fill said concave portion and then partially removing portions of said barrier metal film and said metallic film that are outside of said concave portion, thereby partially leaving the barrier metal film and the metallic film only in said concave portion,
• wherein, in said selectively removing said non-porous film, the anisotropic etch process is conducted by employing an etching gas having a mixing ratio within a range of equal to or more than 45 and equal to or less than 100, said mixing ratio being represented by a formula:
• ((gaseous “nitrogen” containing compound)+(inert gas))/(gaseous “fluorine” containing compound).