Fabrication method of semiconductor integrated circuit device

A process of fabricating a semiconductor integrated circuit device comprising the steps of:

• (a) forming a first interconnection made of a first conductive film containing copper as a main component over a main face of a semiconductor substrate;
• (b) forming a first insulating film containing silicon carbide or silicon carbonitride as a main component over the first interconnection;
• (c) forming a first interlayer insulating film over the first insulating film and subsequently dry-etching a portion of the first interlayer insulating film to make a portion of the first insulating film exposed;
• (d) using a first etching gas to dry-etch the first insulating film exposed in the step (c), to form a first interconnection groove wherein the surface of the first interconnection is exposed to its bottom;
• (e) forming a second interconnection made of a conductive film containing copper as a main component inside the first interconnection groove;
• (f) forming a second insulating film containing silicon carbide or silicon carbonitride as a main component over the second interconnection;
• (g) forming a second interlayer insulating film over the second insulating film and subsequently dry-etching a portion of the second interlayer insulating film to make a portion of the second insulating film exposed;
• (h) using a second etching gas to dry-etch the second insulating film exposed in the step (g), to form a second interconnection groove wherein the surface of the second interconnection is exposed to its bottom;
• and
• (i) forming a third interconnection made of a conductive film containing copper as a main component inside the second interconnection groove,
• wherein one of the first and second etching gases is a mixed gas of a third etching gas comprising at least one selected from the group made of SF6, HCl, HBr, Cl2, ClF3 and CF4 and a fourth etching gas comprising at least one selected from the group made of NH3, H2H4, and a mixed gas of N2 and H2;
• wherein the other thereof is a mixed gas of at least one of CHF3 and CF4, and N2;
• and
• wherein both of the first and second etching gases have a quality of substantially avoiding oxidizing the surface of the interconnection made of a conductive film containing copper.