Method for producing bonded object and semiconductor device and copper bonding paste

A method for producing a semiconductor device, comprising:

• a step of preparing a laminate in which a first member, a copper bonding paste, and a second member are laminated in order;
• and
• a step of sintering the copper bonding paste under a pressure of 0.1 to 1 MPa,
• wherein at least one of the first member and the second member is a semiconductor element,
• the copper bonding paste contains metal particles and a dispersion medium,
• a content of the metal particles with respect to a total mass of the copper bonding paste is 50 mass % or more, and
• the metal particles contain 95 mass % or more of submicro copper particles having a volume average particle size of 0.12 μm or more and 0.8 μm or less with respect to a total mass of the metal particles.