Method for direct hydrophilic bonding of substrates

A method for hydrophilic direct bonding of a first substrate onto a second substrate, the method comprising:

• providing the first substrate having a first main surface and the second substrate having a second main surface;
• bringing the first substrate and the second substrate into contact with one another, respectively, via the first and the second main surfaces thereof, so as to form a bonding interface between two bonding surfaces;
• applying a heat treatment configured to close the bonding interface;
• and
• prior to the step of bringing the first and the second substrates into contact with one another, forming, on the first main surface and/or on the second main surface, a bonding layer made of an amorphous semiconductor material having one of N-type and P-type doping elements and a thickness of less than or equal to 50 nm, a face of the bonding layer constituting one of the two bonding surfaces, an oxide layer being disposed less than 20 nm from the bonding interface,
• wherein the forming of the bonding layer made of the amorphous semiconductor material including doping elements comprises:
• a step of forming a polycrystalline layer containing a polycrystalline semiconductor material on the main surface of the corresponding substrate, then
• forming the bonding layer made of the amorphous semiconductor on an exposed surface of the polycrystalline layer.