Method to planarize and reduce defect density of silicon germanium

1. A method for blanket depositing a SiGe film comprising:

intermixing a silicon source, a germanium source and an etchant to form a gaseous precursor mixture;

flowing the gaseous precursor mixture over a substrate under chemical vapor deposition conditions; and

depositing a blanket layer of epitaxial SiGe over the substrate, the epitaxial SiGe formed from at least some of the components of the gaseous precursor mixture.

2. The method of claim 1 , wherein an underlying blanket layer is positioned over the substrate, such that the blanket layer of epitaxial SiGe is deposited over the underlying blanket layer.

3. The method of claim 1 , wherein the substrate is patterned with windows of single crystal material framed by a dielectric material.

4. The method of claim 1 , wherein the substrate is patterned with windows of single crystal material framed by a dielectric material, wherein the dielectric material is an oxide.

5. The method of claim 1 , wherein the substrate is patterned with windows of single crystal material within a dielectric material, wherein the dielectric material is a nitride.

6. The method of claim 1 , wherein the substrate is patterned with a shallow trench isolation scheme.

7. The method of claim 1 , wherein the blanket layer of epitaxial SiGe has a surface roughness of less than approximately 40 Årms.

8. The method of claim 1 , wherein the blanket layer of epitaxial SiGe has a surface roughness of less than approximately 20 Årms.

9. The method of claim 1 , wherein the substrate comprises a bare single crystal silicon substrate.

10. The method of claim 1 , wherein the epitaxial SiGe film has a greater silicon content at the interface with the substrate than at other points in the film.

11. The method of claim 1 , wherein the silicon source is selected from the group consisting of silane, disilane, trisilane, chlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane.

12. The method of claim 1 , wherein the germanium source is selected from the group consisting of germane, digermane, trigermane, chlorogermane, dichlorogermane, trichlorogermane, and tetrachlorogermane.

13. The method of claim 1 , wherein the etchant comprises hydrogen chloride.

14. The method of claim 1 , wherein the etchant is present in an amount that is less than the combined amounts of the silicon source and the germanium source, on a weight basis.

15. The method of claim 1 , wherein the blanket layer of epitaxial SiGe has a greater degree of planarity as compared to a reference blanket layer of epitaxial SiGe deposited under comparable conditions, except in the absence of the etchant.

16. The method of claim 1 , wherein the blanket layer of epitaxial SiGe has a reduced density of defects as compared to a reference blanket layer of epitaxial SiGe deposited under comparable conditions, except in the absence of the etchant.

17. The method of claim 1 , wherein the blanket layer of epitaxial SiGe has an etch pit density of less than 10 7 defects cm −2 .

18. The method of claim 1 , wherein the blanket layer of epitaxial SiGe has an etch pit density of less than 10 5 defects cm −2 .

19. A method comprising:

providing a single crystal silicon substrate in a chemical vapor deposition chamber;

supplying a mass of silicon precursor into the chamber;

supplying a mass of germanium precursor into the chamber;

supplying a mass of etchant into the chamber, wherein the mass of etchant supplied is less than the mass of silicon precursor and the mass of germanium precursor, combined; and

depositing a blanket SiGe film over the substrate.

20. The method of claim 19 , wherein the substrate is a bare wafer.

21. The method of claim 19 , wherein the substrate is patterned with windows of single crystal material with a dielectric material.

22. The method of claim 19 , wherein the substrate is a wafer having a first blanket layer deposited thereover, and wherein the SiGe film is deposited as a second blanket layer over the first blanket layer.

23. The method of claim 19 , wherein the chemical vapor deposition chamber is a single wafer chamber.

24. The method of claim 19 , wherein the SiGe film has a greater silicon content at the interface with the substrate than at other points in the film.

25. The method of claim 19 , wherein the silicon precursor is selected from the group consisting of silane, disilane, trisilane, chlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane.

26. The method of claim 19 , wherein the germanium source is selected from the group consisting of germane, digermane, trigermane, chlorogermane, dichlorogermane, trichlorogermane, and tetrachlorogermane.

27. The method of claim 19 , wherein the etchant comprises hydrogen chloride.

28. The method of claim 19 , wherein the germanium content of the blanket SiGe film is between approximately 20% and approximately 100%.

29. The method of claim 19 , wherein the germanium content of the SiGe film is between approximately 40% and approximately 80%.

30. The method of claim 19 , wherein the etchant is supplied into the chamber at a rate between approximately 25 sccm and 50 sccm.

31. The method of claim 19 , wherein the chamber has a temperature between approximately 350° C. and approximately 1100° C. during deposition of the SiGe film.

32. The method of claim 19 , wherein the chamber has a temperature between approximately 800° C. and approximately 900° C. during deposition of the SiGe film.

33. The method of claim 19 , wherein the chamber has a pressure between approximately 0.200 Torr and approximately 850 Torr during deposition of the SiGe film.

34. The method of claim 19 , wherein the chamber has a pressure between approximately 1 Torr and approximately 100 Torr during deposition of the SiGe film.

35. The method of claim 19 , wherein the SiGe film has a surface roughness of less than approximately 40 Årms.

36. The method of claim 19 , wherein the SiGe film has a surface roughness of less than approximately 30 Årms.

37. The method of claim 19 , wherein the SiGe film has a surface roughness of less than approximately 20 Årms.

38. A method of blanket depositing a SiGe film comprising:

intermixing a silicon source gas and a germanium source gas;

adding an etchant to the intermixed source gases to from a gaseous precursor mixture;

flowing the gaseous precursor mixture over a substrate under chemical vapor deposition conditions; and

depositing a blanket layer of epitaxial SiGe onto the substrate;

wherein the mass of etchant added to the intermixed source gases is less than a mass of etchant added to the intermixed source gases in a selective deposition process.

39. The method of claim 38 , wherein the mass of etchant added to the intermixed source gases is less than the mass of the intermixed source gases.

40. The method of claim 38 , wherein the substrate is positioned within a chemical vapor deposition chamber.

41. The method of claim 38 , wherein the substrate is positioned within a chemical vapor deposition chamber, and wherein the etchant is supplied to the chamber at between approximately 1 sccm and approximately 200 sccm.

42. The method of claim 38 , wherein the substrate is positioned within a chemical vapor deposition chamber, and wherein the etchant is supplied to the chamber at between approximately 25 sccm and approximately 50 sccm.

43. A method of blanket depositing a film comprising:

providing a single crystal substrate in a chemical vapor deposition chamber;

supplying a mass of germanium source gas into the chamber;

supplying a mass of etchant into the chamber, wherein the mass of etchant supplied is less than the mass of germanium source gas; and

blanket depositing a film over the single crystal substrate, wherein the film comprises germanium.

44. The method of claim 43 , wherein the germanium content of the film is between approximately 20% and approximately 100%.

45. The method of claim 43 , wherein the film has a surface roughness of less than approximately 40 Årms.

46. The method of claim 43 , wherein the film has a surface roughness of less than approximately 20 Årms.

47. The method of claim 43 , wherein the film has an etch pit density of less than 10 7 defects cm −2 .

48. The method of claim 43 , wherein the film has an etch pit density of less than 10 5 defects cm −2 .

49. The method of claim 43 , wherein the film has a greater degree of planarity as compared to a reference film deposited under comparable conditions, except in the absence of the etchant.

50. The method of claim 43 , wherein the single crystal substrate is a bare wafer.

51. The method of claim 43 , wherein the singe crystal substrate is patterned with windows of single crystal material with a dielectric constant.

52. The method of claim 43 , further comprising supplying a mass of silicon source gas into the chamber.