Method of forming a semiconductor device featuring copper wiring layers of different widths having metal capping layers of different thicknesses formed thereon

A method for manufacturing a semiconductor device, comprising:

• a first step of forming a first wiring layer and a second wiring layer which are substantially composed of copper, a width of said first wiring layer is wider than that of said second wiring layer;
• and
• a second step of forming a first metal capping layer and a second capping layer on said respective first and second wiring layers, the formation of said second metal capping layer is carried out at a smaller time than a time at which the formation of said first metal capping layer is carried out,
• wherein said second step is executed such that the formation of said second metal capping layer is started later after a starting of the formation of said first metal capping layer, and such that both the formations of said first and second metal capping layers end at substantially a same time,
• wherein said first step includes a step of forming a first copper oxide layer and a second copper oxide layer on said respective first and second wiring layers, and
• wherein said second step includes:
• a step of immersing the semiconductor device in a plating solution containing a copper oxide removal agent for removing said first and second copper oxide layers from said first and second wiring layers;
• a step of removing said first and second copper oxide layers with said copper oxide removal agent;
• and
• a step of carrying out both the formations of said first and second metal capping layers by said plating solution after the removals of said first and second copper oxide layers.