Method for bonding by direct adhesion

1. A process for attaching a first substrate to a second substrate by direct bonding, the process comprising:

a) providing the first and second substrates, each comprising:

a first surface and an opposite, second surface, and

lateral edges connecting the first and second surfaces;

b) bonding the first substrate to the second substrate by direct bonding with the first surfaces of the first and second substrates so as to form a bonding interface (IC); and

c) making, after the bonding, the lateral edges of the first and second substrates hydrophobic on either side of the bonding interface (IC).

2. The process according to claim 1 , wherein c) is carried out by forming a layer on the lateral edges of the first and second substrates on either side of the bonding interface (IC), said layer being produced in a hydrophobic material.

3. The process according to claim 2 , wherein the hydrophobic material is selected from paraffin wax or a fluorinated coating.

4. The process according to claim 1 , wherein c) is carried out by applying a hydrophobic treatment to the lateral edges of the first and second substrates on either side of the bonding interface (IC).

5. The process according to claim 4 , wherein the hydrophobic treatment is a chemical treatment applied by an acid solution or acid vapour.

6. The process according to claim 4 , wherein the hydrophobic treatment is a surface treatment applied by a plasma.

7. The process according to claim 1 , wherein b) is followed by applying a heat treatment to the bonded first and second substrates, the heat treatment being carried out at a temperature of between 100° C. and 300° C.

8. A process for attaching a first substrate to a second substrate by direct bonding, the process comprising:

a) providing the first and second substrates, each comprising:

a first surface and an opposite, second surface, and

lateral edges connecting the first and second surfaces;

b) bonding the first substrate to the second substrate by direct bonding with the first surfaces of the first and second substrates so as to form a bonding interface (IC), wherein b) is carried out at a temperature of between 20° C. and 30° C.; and

c) making the lateral edges of the first and second substrates hydrophobic on either side of the bonding, interface (IC).

9. The process according to claim 1 , wherein c) is carried out subsequent to b), after a waiting time of less than six hours.

10. The process according to claim 1 , wherein the lateral edges of the first and second substrates provided in a) are produced in a material selected from Si, Ge, a silicon oxide, SiC, a III-V material, a II-VI material.

11. The process according to claim 4 , wherein the hydrophobic treatment is a surface treatment applied by a fluorine-based plasma.

12. The process according to claim 1 , wherein c) is carried out subsequent to b), after a waiting time of less than one hour.

13. The process according to claim 1 , wherein c) is carried out subsequent to b), after a waiting time of less than 15 minutes.

14. The process according to claim 1 , wherein the bonding in b) is hydrophilic bonding.

15. A process for attaching a first substrate to a second substrate by direct bonding, the first and second substrates each including a first surface and an opposite, second surface, and lateral edges connecting the first and second surfaces, the process comprising:

bonding the first substrate to the second substrate by direct bonding with the first surfaces of the first and second substrates so as to form a bonding interface (IC); and

making, after the bonding, the lateral edges of the first and second substrates hydrophobic on either side of the bonding interface (IC).