Silicon germanium-on-insulator formation by thermal mixing
A layer of amorphous silicon is formed on a germanium-on-insulator substrate, or a layer of germanium is formed on a silicon-on-insulator substrate. An anneal is then performed which causes thermal mixing of silicon and germanium atoms within one of the aforementioned structures and subsequent formation of a silicon germanium-on-insulator material.
1. A method of forming a silicon germanium-on-insulator (SGOI) material, said method comprising:
forming a structure comprising, from bottom to top, a germanium-on-insulator substrate and an amorphous silicon layer, wherein the germanium-on-insulator substrate comprises a germanium layer located directly on a surface of an insulator layer, and wherein the amorphous silicon layer is located directly on a topmost surface of the germanium layer;
forming an opening extending through said amorphous silicon layer and said germanium layer of said germanium-on-insulator substrate;
forming a dielectric structure within said opening, wherein said dielectric structure has a topmost surface coplanar with a topmost surface of said amorphous silicon layer, and a sidewall surface that contacts a sidewall surface of the amorphous silicon layer, and a sidewall surface of the germanium layer; and
converting said structure into a silicon germanium-on-insulator material by annealing said structure containing said dielectric structure within an entirely inert ambient annealing environment, wherein during said annealing silicon atoms from said amorphous silicon layer diffuse into the germanium layer and intermix with germanium atoms in said germanium layer of said germanium-on-insulator substrate to form a silicon germanium layer directly on said surface of said insulator layer.
2. The method of claim 1 , wherein said inert ambient annealing environment comprises N 2 .
3. The method of claim 1 , wherein said silicon germanium layer has a germanium content from greater than 50 atomic percent germanium to 90 atomic percent germanium.
4. The method of claim 1 , wherein said amorphous silicon layer is completely consumed by said annealing.
5. The method of claim 1 , wherein said amorphous silicon layer is partially consumed by said annealing.
6. The method of claim 5 , further comprising removing an entirety of a remaining portion of said amorphous silicon layer.
7. The method of claim 1 , wherein said amorphous silicon layer prevents oxidation of said germanium layer during said annealing.
8. The method of claim 1 , wherein said annealing is performed in a same reactor chamber as used in providing said amorphous silicon layer.
9. The method of claim 1 , wherein said germanium layer is single crystalline.
10. The method of claim 1 , wherein said amorphous silicon layer is present on an entirety of a topmost surface of said germanium layer.
11. The method of claim 1 , wherein said amorphous silicon layer is a hydrogenated amorphous silicon layer.