A process for obtaining a bonding surface for direct bonding includes: a) providing a substrate based on a sintered metal having a base surface with an RMS roughness lower than 6 nanometers and a PV roughness lower than 100 nanometers; b) bombarding the base surface with ionic species; c) depositing a metal layer on the base surface; and d) carrying out a mechanical and/or chemical polish of an exposed surface of the metal layer. A structure including a substrate based on a sintered metal the base surface of which is at least partially formed from a metal including ionic species implanted by bombardment of the base surface, and a metal layer of identical chemical composition to that of the metal base substrate and including a bonding surface with an RMS roughness lower than 0.6 nanometers and a PV roughness lower than 10 nanometers is also provided.