Method of producing high quality relaxed silicon germanium layers
View Patent ↗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 0.15 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−y Ge y 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 0.15 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 0.15 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.