Fin stack including tensile-strained and compressively strained fin portions
A fin stack including compressively strained and tensile-strained semiconductor fin regions allows CMOS fabrication to form vertically stacked p-type FinFETs and n-type FinFETs. Aspect ratio trapping within a semiconductor base region within the fin stack provides a relaxed semiconductor base region on which uniaxially strained regions are grown. A dielectric layer may be formed to electrically isolate the compressively strained semiconductor fin region from the tensile-strained semiconductor fin region.
1. A finned, monolithic semiconductor structure, comprising:
a substrate layer; and
a fin structure extending vertically with respect to the substrate layer, the fin structure comprising vertically stacked layers including:
a bottom semiconductor fin region having a first strain type;
a top semiconductor fin region having a second strain type; and
a dielectric layer between and electrically isolating the bottom semiconductor fin region with respect to the top semiconductor fin region;
wherein the first strain type is different from the second strain type,
wherein the fin structure further includes an epitaxial bottom semiconductor base region on the substrate layer and including a relaxed upper portion, the bottom semiconductor fin region being epitaxial with respect to the bottom semiconductor base region.
2. The finned, monolithic semiconductor structure of claim 1 , wherein the bottom semiconductor fin region and the bottom semiconductor base region comprise germanium, the bottom semiconductor base region having a different germanium concentration than the bottom semiconductor fin region.
3. The finned, monolithic semiconductor structure of claim 2 , further including a silicon layer between the bottom semiconductor fin region and the dielectric layer.
4. The finned, monolithic semiconductor structure of claim 1 , wherein the bottom semiconductor fin region and the top semiconductor fin region include {100} or {110} sidewall planes.
5. The finned, monolithic semiconductor structure of claim 1 , wherein the top semiconductor fin region comprises a compound semiconductor material.
6. The finned monolithic semiconductor structure of claim 5 , wherein the bottom semiconductor fin region comprises a germanium or silicon germanium layer having a faceted top surface adjoining the dielectric layer.
7. The finned monolithic semiconductor structure of claim 1 , further including:
an oxide layer on the substrate layer, the fin structure being partially embedded within the oxide layer; and
dielectric anchor structures adjoining first and second end portions of the fin structure and extending through the oxide layer.
8. A semiconductor device, comprising:
a semiconductor substrate layer; and
a multi-layer stack extending vertically with respect to the semiconductor substrate layer, the multi-layer stack including:
an n-type FinFET including a tensile-strained channel region;
a p-type FinFET including a compressive-strained channel region; and
a dielectric layer vertically between and electrically isolating the n-type FinFET from the p-type FinFET,
wherein the multi-layer stack includes:
a bottom semiconductor fin region having a first uniaxial strain type, the first uniaxial strain type comprising one of a tensile strain and a compressive strain;
a top semiconductor fin region having a second uniaxial strain type, the second uniaxial strain type being different from the first uniaxial strain type;
the dielectric layer being between and electrically isolating the bottom semiconductor fin region and the top semiconductor fin region; and
a bottom semiconductor base region on the substrate layer and including a relaxed upper portion, the bottom semiconductor fin region being epitaxial with respect to the bottom semiconductor base region;
wherein the tensile-strained channel region of the n-type FinFET includes a portion of one of the bottom semiconductor fin region and the top semiconductor fin region, and further wherein the compressive-strained channel region of the p-type FinFET includes a portion of another of the bottom semiconductor fin region and the top semiconductor fin region.
9. The semiconductor device of claim 8 , wherein the bottom semiconductor fin region and the bottom semiconductor base region comprise germanium, the bottom semiconductor base region having a different germanium concentration than the bottom semiconductor fin region.
10. The semiconductor device of claim 8 , wherein a portion of the bottom semiconductor fin region comprises the channel region of the p-type FinFET and a portion of the top semiconductor fin region comprises the channel region of the n-type FinFET.
11. The semiconductor device of claim 10 wherein the bottom semiconductor fin region is a germanium or silicon germanium fin region having a faceted top surface and the top semiconductor fin region comprises a compound semiconductor material.
12. The semiconductor device of claim 10 wherein the bottom semiconductor fin region comprises silicon germanium having n-type conductivity and the top semiconductor fin region comprises silicon having p-type conductivity.
13. The semiconductor device of claim 8 , wherein the tensile-strained channel region and the compressive-strained channel region comprise fin sidewall portions comprising {100} or {110} planes.