Bonding structure, semiconductor device, and bonding structure formation method

A method for forming a bonded structure that includes:

• a semiconductor element having an element obverse surface and an element reverse surface spaced apart from each other in a first direction, the semiconductor element including a reverse-surface electrode on the element reverse surface;
• an electrical conductor having a mount surface facing in a same direction as the element obverse surface and supporting the semiconductor element with the mount surface facing the element reverse surface;
• and
• a sintered metal layer that bonds the semiconductor element to the electrical conductor and electrically connects the reverse-surface electrode and the electrical conductor, the method comprising:
• a process of preparing the electrical conductor;
• a roughening process of forming a roughened area on at least a part of the mount surface;
• a paste application process of applying a metal paste for sintering on at least a part of the roughened area;
• a mounting process of placing the semiconductor element on the metal paste, with the element reverse surface facing the mount surface;
• and
• a sintering process of thermally treating the metal paste to form the sintered metal layer.