Method for etching a layer on a silicon semiconductor substrate
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 ClF 3 and/or ClF 5 , a gas selected from the group including Cl 2 and/or HCl being added to the etching gas.
1. 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 Cl 2 and HCl, to the etching gas, wherein the etching gas includes at least one of ClF 3 and ClF 5 ; and
dry chemical etching the SiGe mixed semiconductor layer with the aid of the etching gas and the added gas;
wherein a ratio of partial pressures of the etching gas to the added gas, which includes at least one of Cl 2 and HCl, is in the range of ≧1:5 to ≦5:1, and
wherein the etching is a plasma-less etch based on ClF 3 or ClF 5 and not a plasma etch, so that no plasma reaches a process chamber with the substrate.
2. The method of claim 1 , wherein a partial pressure of the added gas, which includes at least one of Cl 2 and HCl, is in the range of ≧0.5 Pa to ≦500 Pa.
3. The method of claim 1 , wherein a partial pressure of the etching gas, which includes at least one of ClF 3 and ClF 5 , is in the range of ≧0.5 Pa to ≦500 Pa.
4. The method of claim 1 , wherein a total pressure of the etching gas and added gas is in the range of ≧0.5 Pa to ≦1000 Pa.
5. The method of claim 1 , wherein the ClF 3 etching gas is produced by generating a high-density plasma in a plasma reactor, a first gas including at least one of Cl 2 and HCl, and a second gas including at least one of NF 3 , F 2 , and SF 6 , 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.
6. The method of claim 1 , wherein an excess of a first gas including at least one of Cl 2 and HCl with respect to a second gas is supplied to a 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.
7. The method of claim 1 , wherein the gas including at least one of Cl 2 and HCl is added to chlorine trifluoride, the chlorine trifluoride and the gas including at least one of Cl 2 and HCl being jointly supplied to a process chamber in which the etching takes place.
8. The method of claim 1 , wherein the gas including at least one of Cl 2 and HCl is supplied to a process chamber separately from chlorine trifluoride.
9. The method of claim 1 , wherein a ratio of partial pressures of the etching gas, which is ClF 3 , to the added gas, which includes at least one of Cl 2 and HCl, is in the range of ≧1:5 to ≦5:1.
10. The method of claim 1 , wherein a ratio of partial pressures of the etching gas, which is ClF 3 , to the added gas, which includes at least one of Cl 2 and HCl, is in the range of ≧1:2 to ≦4:1.
11. The method of claim 1 , wherein a ratio of partial pressures of the etching gas, which is ClF 3 , to the added gas, which includes at least one of Cl 2 and HCl, is in the range of ≧1:1 to ≦2:1.
12. The method of claim 1 , wherein a partial pressure of the added gas, which includes at least one of Cl 2 and HCl, is in the range of ≧1 Pa to ≦100 Pa.
13. The method of claim 1 , wherein a partial pressure of the added gas, which includes at least one of Cl 2 and HCl, is in the range of ≧20 Pa to ≦50 Pa.
14. The method of claim 1 , wherein a partial pressure of the etching gas, which includes at least one of ClF 3 and ClF 5 , is in the range of ≧1 Pa to ≦100 Pa.
15. The method of claim 1 , wherein a partial pressure of the etching gas, which includes at least one of ClF 3 and ClF 5 , is in the range of ≧20 Pa to ≦50 Pa.
16. The method of claim 1 , wherein a total pressure of the etching gas and added gas is in the range of ≧1 Pa to ≦200 Pa.
17. The method of claim 1 , wherein a total pressure of the etching gas and added gas is in the range of ≧20 Pa to ≦100 Pa.
18. The method of claim 1 , wherein the ClF 3 etching gas is produced by generating a high-density plasma in a plasma reactor, a first gas including at least one of Cl 2 and HCl, and a second gas including at least NF 3 , 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.
19. The method of claim 1 , wherein an excess of a first gas which includes at least one of Cl 2 and HCl with respect to a second gas, which is NF 3 , is supplied to a 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.
20. The method of claim 1 , wherein an excess of a first gas which includes at least one of Cl 2 and HCl with respect to a second gas, which is NF 3 , is supplied to a 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.
21. The method of claim 1 , wherein the ClF 3 etching gas is produced by generating a high-density plasma in a plasma reactor, a first gas including at least one of Cl 2 and HCl, and a second gas including at least one of NF 3 , F 2 , and SF 6 , 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, wherein an excess of a first gas including at least one of Cl 2 and HCl with respect to a second gas is supplied to a 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, and wherein the gas including at least one of Cl 2 and HCl is added to chlorine trifluoride, the chlorine trifluoride and the gas including at least one of Cl 2 and HCl being jointly supplied to a process chamber in which the etching takes place.
22. The method of claim 1 , wherein the ClF 3 etching gas is produced by generating a high-density plasma in a plasma reactor, a first gas including at least one of Cl 2 and HCl, and a second gas including at least one of NF 3 , F 2 , and SF 6 , 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, wherein an excess of a first gas including at least one of Cl 2 and HCl with respect to a second gas is supplied to a 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, and wherein the gas including at least one of Cl 2 and HCl is supplied to a process chamber separately from chlorine trifluoride.