Lattice-mismatched semiconductor structures with reduced dislocation defect densities and related methods for device fabrication
Fabrication of monolithic lattice-mismatched semiconductor heterostructures with limited area regions having upper portions substantially exhausted of threading dislocations, as well as fabrication of semiconductor devices based on such lattice-mismatched heterostructures.
1. A semiconductor device formed over a substrate having a surface and including a first semiconductor material, the device comprising:
(a) a dislocation-blocking mask disposed over the substrate, the mask having an opening extending to the surface of the substrate and defined by at least one sidewall, a ratio of a height of the opening to a width of the opening being greater than 0.5; and
(b) a regrowth region formed in the opening, the regrowth region including:
i. a first portion comprising a second semiconductor material and disposed proximal to the surface of the substrate, dislocation defects in the regrowth region substantially terminating in the first portion; and
ii. a second portion disposed above the first portion, the second portion comprising a third semiconductor material;
(c) a channel region disposed in the second portion of the regrowth region; and
(d) a source region and a drain region, the channel region being disposed therebetween.
2. The device of claim 1 , wherein the first semiconductor material comprises silicon.
3. The device of claim 1 , wherein the substrate comprises:
(a) a silicon wafer;
(b) an insulating layer disposed thereon; and
(c) a strained semiconductor layer disposed on the insulating layer.
4. The device of claim 3 , wherein the strained semiconductor layer comprises silicon or germanium.
5. The device of claim 1 , wherein the substrate comprises:
(a) a silicon wafer;
(b) a compositionally uniform relaxed Si 1-x Ge x layer deposited thereon; and
(c) a strained silicon layer deposited on the relaxed Si 1-x Ge x layer.
6. The device of claim 1 , further comprising a lattice-mismatched layer disposed between at least a portion of the substrate and the dislocation-blocking mask, the lattice-mismatched layer comprising the second semiconductor material and being at least partially relaxed.
7. The device of claim 1 , wherein at least one of the second semiconductor material and the third semiconductor material is selected from the group consisting of a group II, a group III, a group IV, a group V, and a group VI element, and a combination thereof.
8. The device of claim 1 , wherein the first portion of the regrowth region comprises silicon germanium, and the second portion of the regrowth region comprises a layer of strained germanium.
9. The device of claim 1 , wherein the first portion of the regrowth region comprises indium phosphide, and the second portion of the regrowth region comprises a layer of indium gallium arsenide disposed over a layer of indium aluminum arsenide.
10. The device of claim 1 , wherein a width of the opening is less than 1 micrometer.
11. The device of claim 1 , wherein a portion of the sidewall meets the surface of the substrate at an orientation angle to a selected crystallographic direction of the first semiconductor material.
12. A semiconductor device formed over a substrate having a surface and including a first semiconductor material, the device comprising:
(a) a dislocation-blocking mask disposed over the substrate, the mask having an opening extending to the surface of the substrate and defined by at least one sidewall, a ratio of a height of the opening to a width of the opening being greater than 0.5, a length of the opening being greater than the width and the height, the width being perpendicular to the length, the width and length being adjacent to the surface of the substrate, the height being normal to the surface of the substrate; and
(b) a regrowth region formed in the opening, the regrowth region including:
i. a first portion comprising a second semiconductor material and disposed proximal to the surface of the substrate, dislocation defects in the regrowth region terminating in the first portion; and
ii. a second portion disposed above the first portion, the second portion comprising a third semiconductor material, the second portion being substantially exhausted of dislocation defects; and
(c) a device disposed at least in a portion of the regrowth region.
13. The semiconductor device of claim 12 , wherein the device comprises a transistor with a source region, a drain region, and a channel region disposed in the second portion of the regrowth region, the channel region being disposed between the source region and the drain region.
14. The semiconductor device of claim 12 , wherein the device is a transistor comprising a strained channel region disposed in the second portion.
15. The semiconductor device of claim 12 , wherein the device is a finFET comprising a fin, the fin comprising the second portion.
16. The semiconductor device of claim 12 , wherein the device is an optical device, the optical device comprising a p-i-n junction in the regrowth region.
17. The semiconductor device of claim 12 , wherein the opening in the mask extends to a recess in the surface of the substrate, the regrowth region being disposed in the recess.
18. The semiconductor device of claim 12 , wherein the regrowth region extends over a top surface of the mask.
19. The semiconductor device of claim 12 , wherein the substrate comprises a layer of the second semiconductor material along the surface of the substrate.
20. The semiconductor device of claim 12 , wherein the second portion is in an upper portion of the opening, the upper portion of the opening having a larger width than the width of the opening adjacent the surface of the substrate.