Semiconductor integrated structure having an epitaxial SiGe layer extending from silicon-containing regions formed between segments of oxide regions
A modified silicon substrate having a substantially defect-free strain relaxed buffer layer of SiGe is suitable for use as a foundation on which to construct a high performance CMOS FinFET device. The substantially defect-free SiGe strain-relaxed buffer layer can be formed by making cuts in, or segmenting, a strained epitaxial film, causing edges of the film segments to experience an elastic strain relaxation. When the segments are small enough, the overall film is relaxed so that the film is substantially without dislocation defects. Once the substantially defect-free strain-relaxed buffer layer is formed, strained channel layers can be grown epitaxially from the relaxed SRB layer. The strained channel layers are then patterned to create fins for a FinFET device. In one embodiment, dual strained channel layers are formed—a tensilely strained layer for NFET devices, and a compressively strained layer for PFET devices.
1. A semiconductor integrated structure comprising:
a silicon base;
a strain-relaxed buffer layer overlying the silicon base, the strain-relaxed buffer layer including:
an oxide layer in which a plurality of oxide segments form regions spaced apart from one another,
silicon-containing regions positioned between the segments of the oxide regions, and
a SiGe layer overlying the oxide layer, the SiGe layer having a surface, portions of the SiGe layer extending between the segments of the oxide regions and abutting the silicon-containing regions, the SiGe layer having a first germanium concentration; and
an array of SiGe fins on the surface of the SiGe layer, the surface of the SiGe layer extending between adjacent ones of the SiGe fins, the SiGe fins having a second germanium concentration that is greater than the first germanium concentration, each of the SiGe fins including a source region, a drain region, and a channel region between the source and drain regions, each of the source region, the drain region, and the channel region being on a surface of the SiGe layer.
2. The semiconductor integrated structure of claim 1 , further comprising an array of tensilely-strained silicon fins on the SiGe layer.
3. The semiconductor integrated structure of claim 1 wherein the second germanium concentration in the SiGe fins is within a range of about 70%-90%.
4. The semiconductor integrated structure of claim 1 wherein the first germanium concentration in the SiGe layer is within a range of about 25-50%.
5. The semiconductor integrated structure of claim 1 wherein the strain-relaxed buffer layer is substantially free of dislocation defects.
6. The semiconductor integrated structure of claim 1 wherein each of the SiGe fins has a substantially uniform height from the surface of the SiGe layer.
7. A device, comprising:
a semiconductor base of a first semiconductor material;
a plurality of oxide segments on the semiconductor base, the plurality of oxide segments being separated from one another by respective portions of the semiconductor base;
a semiconductor layer of a second semiconductor material overlying the oxide segments and extending between respective pairs of the oxide segments, the semiconductor layer having a surface;
a first array of fins of the first semiconductor material formed on, and in abutting contact with, the surface of the semiconductor layer, the surface of the semiconductor layer extending between adjacent ones of the first array of fins; and
a second array of fins of the second semiconductor material, each of the fins of the second array of fins including a source region, a drain region, and a channel region formed on, and in abutting contact with, the surface of the semiconductor layer, the surface of the semiconductor layer extending between adjacent ones of the second array of fins, the second semiconductor material being different than the first semiconductor material.
8. The device of claim 7 wherein the semiconductor layer abuts the respective portions of the semiconductor base between respective oxide segments.
9. The device of claim 7 wherein the first semiconductor material includes silicon.
10. The device of claim 9 wherein the second semiconductor material includes silicon germanium.
11. The device of claim 7 wherein the first array of fins are tensilely-strained.
12. The device of claim 11 wherein the first array of fins are formed of silicon.
13. The device of claim 7 wherein the second array of fins are compressively-strained.
14. The device of claim 13 wherein the second array of fins are formed of silicon germanium.
15. A semiconductor integrated structure comprising:
a semiconductor base of a first semiconductor material;
a strain-relaxed buffer layer overlying the semiconductor base, the strain-relaxed buffer layer including:
an oxide layer including a plurality of oxide segments spaced apart from one another, portions of the semiconductor base extending between the oxide segments, and
a semiconductor layer of a second semiconductor material overlying the oxide layer, portions of the semiconductor layer extending between the oxide segments and abutting respective portions of the semiconductor base, the semiconductor layer having a surface;
a first array of tensilely-strained fins of the first semiconductor material overlying and in abutting contact with the surface of the semiconductor layer, the surface of the semiconductor layer extending between adjacent ones of the first array of fins; and
a second array of compressively-strained fins of the second semiconductor material, each of the fins of the second array including a source region, a drain region, and a channel region overlying and in abutting contact with the surface of the semiconductor layer, the surface of the semiconductor layer extending between adjacent ones of the second array of fins, the second semiconductor material being different than the first semiconductor material.
16. The semiconductor integrated structure of claim 15 wherein the first semiconductor material comprises silicon.
17. The semiconductor integrated structure of claim 16 wherein the second semiconductor material comprises silicon germanium.
18. The semiconductor integrated structure of claim 17 wherein a concentration of germanium in the semiconductor layer is in the range of about 25-50%.
19. The semiconductor integrated structure of claim 15 wherein the strain-relaxed buffer layer is substantially free of dislocation defects.