A substrate, assembly and method for bonding and electrically interconnecting substrates are provided. According to the method, two substrates are provided, each comprising metal contact structures that are electrically isolated from each other by a bonding layer of dielectric material. Openings are produced in the bonding layer, the openings lying within the surface area of the respective contact structures, exposing the contact material of the structures at the bottom of the openings. Then a layer of conductive material is deposited, filling the openings, after which the material is planarized, removing it from the surface of the bonding layer and leaving a recessed contact patch in the openings. The substrates are then aligned, brought into contact, and bonded by applying an annealing step at a temperature suitable for causing thermal expansion of the contact structures. Deformation of the conductive material of the contact structures through creep pushes the material into the openings from the bottom up, thereby bringing the contact patches into mutual and conductive contact.