Method for depositing an aluminium nitride layer

1. A method for depositing an aluminium nitride layer on a silicon substrate, comprising:

providing a silicon substrate;

placing the substrate in a vacuum chamber;

conditioning a surface of the substrate by plasma soft-etching the surface under vacuum by heating the substrate to a temperature T 2 , introducing Ar gas into the vacuum chamber and subjecting the surface of the substrate to a plasma, and thereby providing a conditioned surface;

heating the substrate to a temperature T 1 ;

depositing an aluminum film onto the conditioned surface of the substrate by a sputtering method under an atmosphere of Argon; and

depositing an epitaxial aluminium nitride layer on the aluminum film by a sputtering method under an atmosphere of Nitrogen and Argon.

2. The method according to claim 1 , wherein T 2 is 35° C. to 70° C.

3. The method according to claim 1 , wherein the plasma soft-etching is carried out at a pressure of 2.10 −4 mbar to 8.10 −4 mbar with a RF plasma comprising Ar + ions.

4. The method according to claim 1 , wherein T 2 <T 1 .

5. The method according to claim 1 , wherein the providing of the silicon substrate includes the providing of a <111> silicon substrate.

6. The method according to claim 1 , wherein the conditioning the surface of the substrate comprises chemical etching the surface.

7. The method according to claim 1 , wherein the etching comprises removing chemically bound oxygen from the substrate.

8. The method according to claim 1 , wherein after the depositing of the aluminum film the surface is mainly Al-terminated.

9. The method according to claim 1 , further comprising subjecting the conditioned surface to a hydrogen containing gas flow in the vacuum chamber after the conditioning.

10. The method according to claim 1 , wherein T 1 lies in the range 650° C. to 800° C.

11. The method according to claim 1 , further comprising flowing Argon gas over the substrate whilst the substrate is heated up to the temperature T 1 .

12. The method according to claim 1 , wherein the conditioning is carried out in a first vacuum chamber and the depositing is carried out in a second vacuum chamber.

13. The method according to claim 1 , further comprising reducing a pressure in the vacuum chamber after the conditioning.

14. The method according to claim 1 , wherein the aluminium nitride film is deposited onto the conditioned surface of the substrate by reactive sputtering.

15. The method according to claim 14 , wherein a DC power of approximately 100 W is used to sputter the aluminum film onto the conditioned surface.

16. The method according to claim 1 , wherein the aluminium nitride layer is deposited onto the aluminum film by reactive sputtering.

17. The method according to claim 16 , wherein a DC power of approximately 1.0 to 3 kW is used to sputter the aluminium nitride layer onto the aluminum film.

18. The method according to claim 1 , further comprising actively cooling the substrate after depositing the aluminium nitride layer.

19. A method of producing a layered substrate, comprising:

providing a silicon substrate;

placing the substrate in a vacuum chamber;

conditioning a surface of the substrate by plasma soft-etching the surface under vacuum by heating the substrate to a temperature T 2 , introducing Ar gas into the vacuum chamber and subjecting the surface of the substrate to a plasma, thereby providing a conditioned surface;

heating the substrate to a temperature T 1 ;

depositing an aluminum film onto the conditioned surface of the substrate by a sputtering method under an atmosphere of Argon; and

depositing an epitaxial aluminium nitride layer on the aluminum film by a sputtering method under an atmosphere of Nitrogen and Argon.