METHOD FOR ETCHING A LAYER ON A SILICON SEMICONDUCTOR SUBSTRATE

• US 20100203739A1
• Filed: 07/02/2008
• Published: 08/12/2010
• Est. Priority Date: 07/19/2007
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Becker, Volker, Laermer, Franz, Fuchs, Tino, Leinenbach, Christina
• Granted Patent: US 8,946,090 B2
• Time in Patent Office: Days
• US Class Current: 438/735
• CPC Class Codes: B81C 1/00531 Dry etching
• CPC Class Codes: B81C 1/00595 Control etch selectivity
• CPC Class Codes: B81C 2201/0132 Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling
• CPC Class Codes: B81C 2201/0138 Monitoring physical parameters in the etching chamber, e.g. pressure, temperature or gas composition
• CPC Class Codes: H01L 21/02019 Chemical etching
• CPC Class Codes: H01L 21/30621 Vapour phase etching
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/32135 by vapour etching only

Abstract

A method for selective etching of an SiGe mixed semiconductor layer on a silicon semiconductor substrate by dry chemical etching of the SiGe mixed semiconductor layer with the aid of an etching gas selected from the group including ClF₃ and/or ClF₅, a gas selected from the group including Cl₂ and/or HCl being added to the etching gas.

Claims

1-10. -10. (canceled)

11. A method for etching an SiGe mixed semiconductor layer on a silicon semiconductor substrate, the method comprising:

adding a gas, which includes at least one of Cl₂ and HCl, to the etching gas, wherein the etching gas includes at least one of ClF₃ and ClF₅; and

dry chemical etching the SiGe mixed semiconductor layer with the aid of the etching gas and the added gas.

12. The method of claim 11, wherein a ratio of partial pressures of the etching gas to the added gas, which includes at least one of Cl₂ and HCl, is in the range of ≧

1;

5 to ≦

5;

1.

13. The method of claim 11, wherein a partial pressure of the added gas, which includes at least one of Cl₂ and HCl, is in the range of ≧

0.5 Pa to ≦

500 Pa.

14. The method of claim 11, wherein a partial pressure of the etching gas, which includes at least one of ClF₃ and ClF₅, is in the range of ≧

0.5 Pa to ≦

500 Pa.

15. The method of claim 11, wherein a total pressure of the etching gas and added gas is in the range of ≧

0.5 Pa to ≦

1000 Pa.

16. The method of claim 11, wherein the ClF₃ etching gas is produced by generating a high-density plasma in a plasma reactor, a first gas including at least one of Cl₂ and HCl, and a second gas including at least one of NF₃, F₂, and SF₆, being supplied to the plasma reactor, and the gases reacting under the effect of the high-density plasma in the plasma reactor, forming chlorine trifluoride.

17. The method of claim 11, wherein an excess of the first gas including at least one of Cl₂ and HCl with respect to the second gas is supplied to the plasma reactor, a ratio of the gas flows of the first gas to the second gas being in the range of ≧

1;

3 to ≦

4;

1.

18. The method of claim 11, wherein the gas including at least one of Cl₂ and HCl is added to the formed chlorine trifluoride, chlorine trifluoride and the gas including at least one of Cl₂ and HCl being jointly supplied to a process chamber in which the etching takes place.

19. The method of claim 11, wherein the gas including at least one of Cl₂ and HCl is supplied to the process chamber separately from the formed chlorine trifluoride.

21. The method of claim 11, wherein a ratio of partial pressures of the etching gas, which is ClF₃, to the added gas, which includes at least one of Cl₂ and HCl, is in the range of ≧

1;

5 to ≦

5;

1.

22. The method of claim 11, wherein a ratio of partial pressures of the etching gas, which is ClF₃, to the added gas, which includes at least one of Cl₂ and HCl, is in the range of ≧

1;

2 to ≦

4;

1.

23. The method of claim 11, wherein a ratio of partial pressures of the etching gas, which is ClF₃, to the added gas, which includes at least one of Cl₂ and HCl, is in the range of ≧

1;

1 to ≦

2;

1.

24. The method of claim 11, wherein a partial pressure of the added gas, which includes at least one of Cl₂ and HCl, is in the range of ≧

1 Pa to ≦

100 Pa.

25. The method of claim 11, wherein a partial pressure of the added gas, which includes at least one of Cl₂ and HCl, is in the range of ≧

20 Pa to ≦

50 Pa.

26. The method of claim 11, wherein a partial pressure of the etching gas, which includes at least one of ClF₃ and ClF₅, is in the range of ≧

1 Pa to ≦

100 Pa.

27. The method of claim 11, wherein a partial pressure of the etching gas, which includes at least one of ClF₃ and ClF₅, is in the range of ≧

20 Pa to ≦

50 Pa.

28. The method of claim 11, wherein a total pressure of the etching gas and added gas is in the range of ≧

1 Pa to ≦

200 Pa.

29. The method of claim 11, wherein a total pressure of the etching gas and added gas is in the range of ≧

20 Pa to ≦

100 Pa.

30. The method of claim 11, wherein the ClF₃ etching gas is produced by generating a high-density plasma in a plasma reactor, a first gas including at least one of Cl₂ and HCl, and a second gas including at least NF₃, being supplied to the plasma reactor, and the gases reacting under the effect of the high-density plasma in the plasma reactor, forming chlorine trifluoride.

31. The method of claim 11, wherein an excess of the first gas 2 which includes at least one of Cl₂ and HCl with respect to the second gas, which is NF₃, is supplied to the plasma reactor, a ratio of the gas flows of the first gas to the second gas being in the range of ≧

1;

5 to ≦

6;

1.

32. The method of claim 11, wherein an excess of the first gas which includes at least one of Cl₂ and HCl with respect to the second gas, which is NF₃, is supplied to the plasma reactor, a ratio of the gas flows of the first gas to the second gas being in the range of ≧

1;

2 to ≦

2;

1.

20. A device for etching an SiGe mixed semiconductor layer on a silicon semiconductor substrate, comprising:

an etching device for etching an SiGe mixed semiconductor layer on a silicon semiconductor substrate;

an etching gas device for producing an etching gas, wherein the devices are associated with a process chamber, which is connected to a plasma reactor via a gas inlet, the semiconductor substrate being situated in the process chamber and exposed to a gaseous chlorine trifluoride produced by the etching gas device for producing the chlorine trifluoride; and

an additional gas supply arrangement, which includes a mass flow regulator, for adjusting a supply of the gas, which is selected from at least one of Cl₂ and HCl, that is supplied to at least one of the plasma reactor, the gas outlet of the plasma reactor, and the process chamber;

wherein a gas, which includes at least one of Cl₂ and HCl, is added to the etching gas, wherein the etching gas includes at least one of ClF₃ and ClF₅, and

wherein the SiGe mixed semiconductor layer is dry etched with the aid of the etching gas and the added gas.