in at least one of two substrates using micro electronic processing techniques and bonding the substrates bonding is performed by forming on a first substrate bonding regions of deformable material and pressing the substrates one against another so as to deform the bonding regions and to cause them to react chemically with the second substrate the bonding regions are preferably formed by a thick layer of a material chosen from among aluminum copper and nickel covered by a thin layer of a material chosen from between palladium and platinum spacing regions ensure exact spacing between the two wafers application_number US 24397202 A description the invention is based upon the use of a material having characteristics allowing good quality bonding of two substrates namely two wafers of semiconductor material in which electronic devices and or micro electromechanical structures are integrated even in presence of non planar areas and or undesired particles acting as spacers as generally happens in the case of substrates that have undergone previous fabrication processes according to one aspect of the invention on one of two substrates a layer possibly a composite layer is formed having characteristics of high deformability soft material and capacity for reaction with the other substrate bonding material in what follows.