Electrically insulated fin structure(s) with alternative channel materials and fabrication methods
Semiconductor structures and fabrication methods are provided which includes, for instance, fabricating a semiconductor fin structure by: providing a fin structure extending above a substrate, the fin structure including a first fin portion, a second fin portion disposed over the first fin portion, and an interface between the first and the second fin portions, where the first fin portion and the second fin portion are lattice mismatched within the fin structure; and modifying, in part, the fin structure to obtain a modified fin structure, the modifying including selectively oxidizing the interface to form an isolation region within the modified fin structure, where the isolation region electrically insulates the first fin portion from the second fin portion, while maintaining structural stability of the modified fin structure.
1. A method comprising:
fabricating a semiconductor fin structure, the fabricating comprising:
providing a fin structure extending above a substrate, the fin structure including a first fin portion, a second fin portion disposed over the first fin portion, and an interface between the first and the second fin portions, wherein the first fin portion and the second fin portion are lattice mismatched within the fin structure; and
modifying, in part, the fin structure to obtain a modified fin structure, the modifying comprising disposing an oxide layer about the fin structure to mechanically stabilize the fin structure and selectively oxidizing the interface to form an isolation region within the modified fin structure, wherein the isolation region electrically insulates the first fin portion from the second fin portion, while maintaining structural stability of the modified fin structure, wherein the selectively oxidizing comprises selectively oxidizing the interface with a controlled oxidation process which extends oxidation into at least a portion of the first and the second fin portions forming the isolation region, and wherein the modifying comprises annealing the fin structure in the absence of oxygen process gas to selectively oxidize the interface to obtain the isolation region, wherein the oxide layer provides oxygen atoms to facilitate oxidizing of the interface.
2. The method of claim 1 , wherein the selectively oxidizing inhibits the oxidation of any remaining portions of the first and the second fin portions.
3. The method of claim 2 , wherein the selectively oxidizing comprises oxidizing the fin structure using an oxidizing time which facilitates selectively oxidizing the interface to a desired thickness, the oxidizing time being selected to inhibit oxidizing of the remaining portions of the first and the second fin portions.
4. The method of claim 3 , wherein the isolation region has a desired thickness within a range of about 5 to 15 nm.
5. The method of claim 4 , wherein the modifying comprises performing an oxidation process of the fin structure, in the presence of an oxygen process gas, to locally oxidize the interface within the fin structure, and form the isolation region within the modified fin structure.
6. The method of claim 2 , wherein the oxide layer facilitates oxidizing of the fin structure selectively at the interface, and inhibiting oxidizing of the remaining portions of the first fin portion or the second fin portion.
7. The method of claim 1 , wherein the first fin portion and the substrate comprise a silicon material, and the second fin portion comprises an intrinsically strained silicon germanium material with a specific atomic ratio of germanium to silicon disposed therein.
8. The method of claim 7 , wherein the specific atomic ratio of germanium to silicon of the intrinsically strained silicon germanium material is about 0.5 or more.
9. The method of claim 7 , wherein the selectively oxidizing comprises selecting the specific atomic ratio of germanium to silicon of the intrinsically strained silicon germanium material which facilitates determining an oxidizing time employed in the oxidizing of the interface.
10. The method of claim 1 , wherein the second fin portion comprises a material with a first lattice constant, and the first fin portion and the substrate comprise a material with a second lattice constant, the first and the second lattice constants being different lattice constants, and the second fin portion with the first lattice constant and the first fin portion with the second lattice constant induce an intrinsic strain within the second fin portion.
11. The method of claim 1 , wherein providing the fin structure comprises:
providing an intermediate fin structure extending above the substrate, the intermediate fin structure comprising a material of the first fin portion;
disposing the oxide layer about the intermediate fin structure;
etching at least a portion of the intermediate fin structure adjacent to the oxide layer to create a recessed fin structure above the substrate; and
epitaxially growing a material of the second fin portion over the recessed fin structure, and planarizing the material of the second fin portion to be substantially coplanar with a surface of the oxide layer, and thereby define, at least in part, the fin structure to be modified.
12. The method of claim 11 , wherein the material of the first fin portion comprises a silicon material, and the material of the second fin portion comprises an intrinsically strained silicon germanium material having a specific atomic ratio of germanium to silicon disposed therein, the specific atomic ratio of germanium to silicon being about 0.5 or more.