Method of producing high quality relaxed silicon germanium layers
A method for minimizing particle generation during deposition of a graded Si 1-x Ge x layer on a semiconductor material includes providing a substrate in an atmosphere including a Si precursor and a Ge precursor, wherein the Ge precursor has a decomposition temperature greater than germane, and depositing the graded Si 1-x Ge x layer having a final Ge content of greater than about 0.15 and a particle density of less than about 0.3 particles/cm 2 on the substrate.
1. A method for minimizing particle generation during deposition of a graded Si 1-x Ge x layer on a semiconductor material within a reactor, the method comprising the steps of:
(a) providing a substrate in an atmosphere comprising a Si precursor and a Ge precursor, wherein the Ge precursor has a higher decomposition temperature than germane; and
(b) depositing the graded Si 1-x Ge x layer on the substrate, the Si 1-x Ge x layer having a final Ge content wherein x is greater than about 0.20 and a particle density less than about 0.3 particles/cm 2 .
2. The method of claim 1 wherein the Ge precursor comprises a germanium halide.
3. The method of claim 1 wherein the graded Si 1-x Ge x layer is deposited at a temperature of greater than about 600° C.
4. The method of claim 1 wherein the graded Si 1-x Ge x layer is deposited at a temperature of greater than about 800° C.
5. The method of claim 1 wherein the graded Si 1-x Ge x layer is deposited at a temperature of greater than about 1000° C.
6. The method of claim 1 wherein the graded Si 1-x Ge x layer is deposited at a temperature of about 1100° C.
7. The method of claim 1 wherein the final Ge content of the graded Si 1-x Ge x layer has a value for x substantially equal to 1.0.
8. The method of claim 1 further comprising providing a substantially relaxed Si 1-x Ge x layer disposed above the graded Si 1-x Ge x layer wherein y is approximately equal to the final Ge content of the graded Si 1-x Ge x layer.
9. The method of claim 8 further comprising providing a thin, strained semiconductor layer disposed above the graded Si 1-y Ge y layer.
10. The method of claim 9 wherein the thin, strained semiconductor layer is selected from the group consisting of Si, Ge, and SiGe.
11. The method of claim 1 wherein the Ge content is increased at a rate less than about 25% per micron resulting in a density of threading dislocation intersecting the surface of the graded Si 1-x Ge x layer of less than about 1×10 6 /cm 2 .
12. The method of claim 1 wherein the Ge content is increased at a rate greater than about 25% per micron resulting in a density of threading dislocation intersecting the surface of the graded Si 1-x Ge x layer of less than about 1×10 6 /cm 2 .
13. The method of claim 1 wherein a deposition rate of the graded Si 1-x Ge x layer is greater than about 0.3 microns per minute.
14. The method of claim 1 wherein a deposition rate of the graded Si 1-x Ge x layer is greater than about 1 micron per minute.
15. The method of claim 1 wherein a deposition rate of the graded Si 1-x Ge x layer is greater than about 3 micron per minute.
16. The method of claim 2 wherein the Ge precursor is selected from the group consisting of GeCl 4 , GeHCl 3 , and GeH 2 Cl 2 .
17. The method of claim 1 wherein the Si precursor is selected from the group consisting of SiH 2 Cl 2 , SiHCl 3 , SiH 4 , and SiCl 4 .
18. The method of claim 1 further comprising rotating the substrate during deposition of the graded Si 1-x Ge x layer.
19. The method of claim 1 further comprising depositing the graded Si 1-x Ge x layer to include a surface roughness of less than about 5 nm for a 40×40 micron scan.
20. The method of claim 1 further comprising depositing the graded Si 1-x Ge x layer at a pressure between about 760 torr and about 0.010 torr.
21. The method of claim 1 wherein step (b) comprises:
depositing the graded Si 1-x Ge x layer on the substrate while preventing the deposition of a coating greater than about 1 micron thick on an inner surface of the reactor, the Si 1-x Ge x layer having a final Ge content wherein x is greater than about 0.20 and a particle density of less than about 0.3 particles/cm 2 .
22. A method for minimizing particle generation during deposition of a graded Si 1-x Ge x layer on a semiconductor material within a reactor, the method comprising the steps of:
(a) providing a substrate in an atmosphere comprising a Si precursor, a Ge precursor, and an etchant gas, wherein the etchant gas includes a halide source and reduces accumulation of semiconductor deposits on reactor walls; and
(b) depositing the graded Si 1-x Ge x layer on the substrate, the Si 1-x Ge x layer having a final Ge content wherein x is greater than about 0.20 and a particle density less than about 0.3 particles/cm 2 .
23. The method of claim 22 wherein the etchant gas is selected from the group consisting of HCl, HBr, HF, HI, Cl 2 , Br 2 , F 2 , and I 2 .
24. A semiconductor material formed by the process of claim 1 .
25. The semiconductor material of claim 24 wherein the graded Si 1-x Ge x layer has a localized light-scattering defect level of less than about 0.3 defects/cm 2 , the particle defects having a size greater than about 0.13 microns.
26. The semiconductor material of claim 24 wherein the graded Si 1-x Ge x layer has a localized light-scattering defect level of less than about 0.2 defects/cm 2 , the particle defects having a size greater than about 0.16 microns.
27. The semiconductor material of claim 24 wherein the graded Si 1-x Ge x layer has a localized light-scattering defect level of less than about 0.1 defects/cm 2 , the particle defects having a size greater than about 0.2 microns.
28. The semiconductor material of claim 24 wherein the graded Si 1-x Ge x layer has a localized light-scattering defect level of less than about 0.03 defects/cm 2 , the particle defects having a size greater than about 1 micron.
29. The semiconductor material of claim 24 wherein each layer within the graded Si 1-x Ge x layer has a substantially uniform composition across the substrate.
30. A method for minimizing particle generation during deposition of a semiconductor material, the method comprising the steps of:
(a) providing a substrate in an atmosphere comprising SiH 2 Cl 2 and GeCl 4 ;
(b) depositing a Si 1-x Ge x layer on the substrate, wherein x≧0.02 and the Si 1-x Ge x layer has a particle density of less than about 0.3 particles/cm 2 ; and
(c) depositing additional Si 1-x Ge x layers, wherein a Ge content of successively deposited Si 1-x Ge x layers is increased to x being greater than about 0.20.
31. The method of claim 30 wherein the successively deposited Si 1-x Ge x layers comprises a graded Si 1-x Ge x layer having a particle density of less than about 0.3 particles/cm 2 .
32. The method of claim 30 wherein the Si 1-x Ge x layer is deposited at a temperature of greater than about 600° C.
33. The method of claim 30 wherein the Si 1-x Ge x layer is deposited at a temperature of about 1100° C.
34. The method of claim 31 further comprising providing a thin, strained semiconductor layer disposed above the graded Si 1-x Ge x layer.
35. The method of claim 34 wherein the thin, strained semiconductor layer is selected from the group consisting of Si, Ge, and SiGe.
36. The method of claim 31 wherein the Ge content is increased at a rate greater than about 25% per micron resulting in a density of threading dislocation intersecting the surface of the graded Si 1-x Ge x layer of less than about 1×10 6 /cm 2 .
37. The method of claim 31 wherein the Ge content is increased at a rate less than about 25% per micron resulting in a density of threading dislocation intersecting the surface of the graded Si 1-x Ge x layer of less than about 1×10 6 /cm 2 .
38. The method of claim 30 wherein a deposition rate of the Si 1-x Ge x layer is greater than about 0.3 microns per minute.