Pad metallization with oxide layer to reduce deformation of conductive films

A method of manufacturing a semiconductor device, the method comprising:

• (a) forming a multilayer wiring layer on a semiconductor substrate;
• (b) forming a dielectric film so as to cover a pad electrode formed in an uppermost wiring layer of the multilayer wiring layer;
• (c) forming an opening portion in the dielectric film so as to reach the pad electrode;
• (d) forming a first conductive film on the pad electrode in the opening portion by a plating method;
• (f) after the (d), forming a second conductive film on the first conductive film by a plating method;
• (g) after the (f), forming a third conductive film on the second conductive film by a plating method;
• and
• (e) after the (g), performing an oxidation treatment to the first conductive film and oxidizing a material contained in the first conductive film, thereby forming an oxide layer on a side surface of the first conductive film,
• wherein a width of the oxide layer is 200 nm or more,
• wherein Vickers hardness of the third conductive film is smaller than Vickers hardness of each of the first conductive film and the second conductive film, and
• wherein a thickness of the third conductive film is thicker than a thickness of each of the first conductive film and the second conductive film.