Semiconductor integrated circuit device and manufacturing method of semiconductor integrated circuit device

A manufacturing method of a semiconductor integrated circuit device, comprising:

• (a) forming a first interconnection groove in a first insulating film over the first main surface of a wafer,
• (b) forming, over the first main surface of the wafer having the first interconnection groove formed therein, a first metal film having copper as a main component to embed the first interconnection groove with the first metal film,
• (c) removing the first metal film outside the first interconnection groove by subjecting the first main surface of the wafer having the first metal film formed therein to first abrasive-grain-free chemical mechanical polishing,
• (d) subjecting the first main surface of the wafer from which the first metal film outside the first interconnection groove has been removed to first gas-phase treatment in a first gas-phase reducing atmosphere, thereby subjecting the upper surface of the first copper-embedded interconnection embedded in the first interconnection groove to reducing treatment, and
• (e) forming a cap insulating film, which has inhibitory action against the diffusion of copper atoms or copper-containing ions into an insulating film, over the first insulating film and first copper-embedded interconnection over the first main surface of the wafer subjected to reducing treatment.