Dual isolation fin and method of making
A method of making a dual isolation fin comprises applying a mask to a substrate and etching the exposed areas of the substrate to form a mandrel; forming a dielectric layer on the surface of the substrate and adjacent to the mandrel; forming a first epitaxially formed material on the exposed portions of the mandrel; forming a second epitaxially formed material on the first epitaxially formed material; forming a first isolation layer on the dielectric layer and adjacent to the second epitaxially formed material; removing the mask and mandrel after forming the first isolation layer; removing the first epitaxially formed material after removing the mask and mandrel; and forming a second isolation layer.
1. A method of making a dual isolation fin comprising:
applying a mask to portions of a substrate and etching exposed areas of the substrate to form a mandrel;
forming a dielectric layer disposed on a surface of the substrate and adjacent to the mandrel;
forming a first epitaxially formed material on an exposed portion of the mandrel;
forming a second epitaxially formed material on the first epitaxially formed material;
forming a first isolation layer on the dielectric layer and adjacent to the second epitaxially formed material;
removing the mask and mandrel after forming the first isolation layer to form an open area of the substrate;
removing the first epitaxially formed material after removing the mask and mandrel; and
forming a second isolation layer in the open area of the substrate.
2. The method of claim 1 , wherein the substrate comprises silicon.
3. The method of claim 1 , wherein the mandrel has a height of 50 to 200 nanometers.
4. The method of claim 1 , wherein the dielectric layer has a thickness of 30 to 100 nanometers.
5. The method of claim 1 , wherein the first epitaxially formed material has a lattice constant intermediate to the second epitaxially formed material lattice constant and the mandrel lattice constant.
6. The method of claim 1 , wherein the second epitaxially formed material has a thickness less than or equal to 30 nanometers.
7. The method of claim 1 , wherein the second epitaxially formed material has a thickness of 3 to 10 nanometers.
8. The method of claim 1 , wherein the first isolation layer has a thickness less than a height of the second epitaxially formed material.
9. The method of claim 1 , wherein the first isolation layer has a thickness equal to a height of the second epitaxially formed material.
10. The method of claim 1 , wherein the first isolation layer and the dielectric layer comprise a same material.
11. A method of making a dual isolation fin comprising:
applying a mask to portions of a substrate comprising silicon and etching exposed areas of the substrate to form a mandrel;
forming a dielectric layer disposed on a surface of the substrate and adjacent to the mandrel;
forming a first epitaxially formed material comprising a first III-V material on exposed portions of the mandrel;
forming a second epitaxially formed material comprising a second III-V material on the first epitaxially formed material;
forming a first isolation layer on top of the dielectric layer and adjacent to the second epitaxially formed material;
removing the mask and mandrel after forming the first isolation layer to form an open area of the substrate;
removing the first epitaxially formed material after removing the mask and mandrel; and
forming a second isolation layer in the open area of the substrate wherein the first III-V material has a lattice constant greater than a lattice constant of silicon and less than a lattice constant of the second III-V material.
12. The method of claim 11 , wherein the mandrel has a height of 50 to 200 nanometers.
13. The method of claim 11 , wherein the dielectric layer has a thickness of 30 to 100 nanometers.
14. The method of claim 11 , wherein the second epitaxially formed material has a thickness of 3 to 10 nanometers.
15. The method of claim 11 , wherein the second epitaxially formed material has a thickness less than or equal to 30 nanometers.
16. The method of claim 11 , wherein the first isolation layer and the dielectric layer comprise a same material.