Method of treatment of an electronic circuit for a hybrid molecular bonding

1. A method of treatment of an electronic circuit comprising at a location at least one electrically-conductive test pad having a first exposed surface, the method comprising at least partially etching the test pad from said first surface after a test of the electronic circuit, wherein, in the area where the test pad is etched, the test pad is etched across at least 50% of its average thickness, and forming on the electronic circuit an interconnection level covering said location and comprising, on the side opposite to said location, a second planar surface adapted for the performing of a hybrid molecular bonding.

2. The method according to claim 1 , wherein the interconnection level comprises electrically-conductive bonding pads exposed on the second surface.

3. The method according to claim 2 , wherein the electronic circuit comprises at least one electrically-conductive contact pad, and wherein one of the bonding pads is connected to the contact pad by at least one electrically-conductive via.

4. The method according to claim 2 , wherein the electronic circuit comprises, before the forming of the interconnection level, a first insulating layer covering the contact pad, covering the periphery of the test pad and crossed by a hole exposing the first surface.

5. The method according to claim 4 , wherein the at least partial etching of the test pad is performed through the hole by using the first insulating layer as an etch mask.

6. The method according to claim 4 , wherein the periphery of the test pad covered with the first insulating layer is not etched.

7. The method according to claim 1 , comprising forming an etch mask covering the electronic circuit and comprising an opening totally or partially exposing the first surface and etching the test pad through said opening.

8. The method according to claim 7 , wherein the etch mask is in contact with the first surface before the step of at least partial etching of the test pad.

9. The method according to claim 1 , wherein the step of forming of the interconnection level comprises a chemical-mechanical planarization step.

10. The method according to claim 1 , comprising, before the step of at last partial etching of the test pad, a step of testing of the electronic circuit comprising the application of at least one electrically-conductive probe against the test pad.

11. The method according to claim 1 , comprising the hybrid molecular bonding of the second surface to a third surface of another electronic circuit.

12. The method according to claim 1 , wherein, in the area where the test pad is etched, the test pad is etched across its entire thickness.

13. The method according to claim 1 , wherein the test pad is formed on a second layer, the at least partial etching of the test pad being performed to reach the second layer, the second layer being used as an etch stop layer.

14. The method according to claim 1 , wherein the test pad is totally etched.