Forming strained and relaxed silicon and silicon germanium fins on the same wafer

1. A method for fabricating strained and relaxed silicon and silicon germanium fins on a semiconductor wafer comprising a substrate, a dielectric layer formed on the substrate, and a strained silicon germanium (SiGe) layer formed on the dielectric layer, the method comprising:

transforming at least one region of the strained SiGe layer into at least one relaxed SiGe region;

forming at least one strained SiGe fin from at least a first strained SiGe region of the strained SiGe layer, and at least one relaxed SiGe fin from at least a first portion of the at least one relaxed SiGe region;

epitaxially growing relaxed silicon on at least a second strained SiGe region of the strained SiGe layer, and strained silicon on at least a second portion of the relaxed SiGe region; and

forming at least one relaxed silicon fin from the relaxed silicon, and at least one strained silicon fin from the strained silicon.

2. The method of claim 1 , further comprising:

forming a plurality of mandrels, wherein at least a first mandrel is formed above the first strained SiGe region and the first portion of the at least one relaxed SiGe region, and

wherein at least a second mandrel is formed above the second strained SiGe region and the second portion of the at least one relaxed SiGe region.

3. The method of claim 2 , further comprising:

depositing a spacer material over the plurality of mandrels; and

removing the spacer material from horizontal surfaces of the plurality of mandrels, wherein the removing forms a first sidewall spacer and at least a second sidewall spacer on each of the plurality of mandrels.

4. The method of claim 3 , further comprising:

removing the first and second sidewall spacers from at least the second mandrel; and

removing at least the first mandrel after the first and second sidewall spacers have been removed from at least the second mandrel, wherein the first sidewall spacer of the first mandrel remains above a portion of the at least one relaxed SiGe region, and the second sidewall spacer of the first mandrel remains above a portion of the at least first strained SiGe region.

5. The method of claim 4 , wherein forming the at least one strained SiGe fin and the at least one relaxed SiGe fin further comprises:

etching exposed regions of the strained SiGe layer and the at last one relaxed SiGe region, wherein the etching forms the at the least one relaxed SiGe fin and the at least one strained SiGe fin.

6. The method of claim 4 , wherein epitaxially growing relaxed silicon and strained silicon further comprises:

etching exposed regions of the strained SiGe layer and the at last one relaxed SiGe region, wherein the etching forms the at least second strained SiGe region and the at least second portion of the relaxed SiGe region.

7. The method of claim 1 , further comprising:

forming a pad layer on the SiGe layer prior to transforming the at least one region of the strained SiGe layer into the relaxed SiGe region.

8. The method of claim 7 , further comprising:

forming a plurality of mandrels, wherein at least a first mandrel is forms on a first portion of the pad layer over the first strained SiGe region and the first portion of the at least one relaxed SiGe region, and wherein at least a second mandrel is formed on at least a second portion of the pad layer over the second strained SiGe region and the second portion of the at least one relaxed SiGe region;

forming a first sidewall spacer and at least a second sidewall spacer on each of the plurality of mandrels;

removing the first and second sidewall spacers from at least the second mandrel; and

removing at least the first mandrel after the first and second sidewall spacers have been removed from at least the second mandrel, wherein the first sidewall spacer of the first mandrel remains over a third portion of the pad, and the second sidewall spacer of the first mandrel remains over a fourth portion of the pad layer.

9. The method of claim 8 , further comprising:

etching exposed portions of the pad layer, wherein the second portion of the pad layer remains under the at least second mandrel, and wherein the third portion of the pad layer remains under the first sidewall of the first mandrel and the fourth portion of the pad layer remains under the second sidewall of the first mandrel; and

after etching the exposed portions of the pad layer, removing the second mandrel, the first sidewall of the first mandrel, and the second sidewall of the first mandrel.

10. The method of claim 9 , wherein forming the at least one strained SiGe fin and the at least one relaxed SiGe fin further comprises:

etching exposed regions of the strained SiGe layer and the at last one relaxed SiGe region, wherein the etching forms the at the least one relaxed SiGe fin under the third portion of the pad layer and the at least one strained SiGe fin under the fourth portion of the pad layer; and

removing at least the third and fourth portions of the pad layer, and wherein epitaxially growing relaxed silicon and strained silicon further comprises:

etching exposed regions of the strained SiGe layer and the at last one relaxed SiGe region, wherein the etching forms the at least second strained SiGe region and the at least second portion of the relaxed SiGe region under the at least second portion of the pad layer; and

removing the at least second portion of the pad layer.