Conductive contacts in semiconductor on insulator substrate
A semiconductor device includes a gate stack arranged on a channel region of a semiconductor layer and a semiconductor layer arranged on an insulator layer. A crystalline source/drain region is arranged in a cavity in the insulator layer, and a spacer is arranged adjacent to the gate stack, the spacer arranged over the source/drain region. A second insulator layer is arranged on the spacer and the gate stack, and a conductive contact is arranged in the source/drain region.
1. A method for forming a semiconductor device, the method comprising:
forming a gate sack on a semiconductor layer;
depositing a first layer of spacer material over the gate stack and exposed portions of the semiconductor layer;
depositing a second spacer layer over the first layer of spacer material;
removing portions of the second spacer layer to expose portions of the first layer of spacer material;
removing portions of the first layer of spacer material to form a spacer adjacent to the gate stack such that a portion of the second spacer layer is arranged on a region of the spacer;
removing an exposed portion of the semiconductor layer to expose portions of an insulator layer;
etching to remove portions of the insulator layer to form a cavity beneath the semiconductor layer and the spacer;
epitaxially growing a source/drain region from exposed portions of the semiconductor layer to fill the cavity with the source/drain region;
depositing another insulator layer on the source/drain region and the gate stack;
removing portions of the another insulator layer to form a second cavity that exposes portions of the spacer and the source/drain region;
removing portions of the source/drain region in the second cavity; and
depositing a conductive material in the second cavity.
2. The method of claim 1 , further comprising performing an annealing process to drive dopants from the grown source/drain region into a portion of the semiconductor layer after growing the source/drain region.
3. The method of claim 1 , wherein the layer of spacer material includes a nitride material.
4. The method of claim 1 , wherein the removing portions of the source/drain region includes performing an anisotropic etching process.
5. The method of claim 1 , wherein the insulator layer includes an oxide material.
6. The method of claim 1 , wherein the source/drain region includes a crystalline semiconductor material.
7. The method of claim 1 , wherein the gate stack is a high-k metal gate stack.
8. The method of claim 1 , wherein the removing portions of the layer of spacer material to form a spacer includes an anisotropic etching process.
9. The method of claim 1 , wherein the conductive material includes a conductive metal.
10. A method for forming a semiconductor device, the method comprising:
forming a gate sack on a semiconductor layer;
depositing a layer of spacer material over the gate stack and exposed portions of the semiconductor layer;
depositing a second spacer layer over the layer of spacer material;
removing portions of the second spacer layer to expose portions of the layer of spacer material;
removing portions of the layer of spacer material to form a spacer adjacent to the gate stack such that a portion of the second spacer layer is arranged on a region of the spacer;
removing an exposed portion of the semiconductor layer to expose portions of an insulator layer;
etching to remove portions of the insulator layer to form a cavity beneath the semiconductor layer and the spacer;
epitaxially growing a source/drain region from exposed portions of the semiconductor layer to fill the cavity with the source/drain region;
depositing another insulator layer on the source/drain region and the gate stack;
removing portions of the another insulator layer to form a second cavity that exposes portions of the spacer and the source/drain region;
removing portions of the source/drain region in the second cavity using an isotropic etching process; and
depositing a conductive material in the second cavity.
11. The method of claim 10 , further comprising performing an annealing process to drive dopants from the grown source/drain region into a portion of the semiconductor layer after growing the source/drain region.
12. The method of claim 10 , wherein the layer of spacer material includes a nitride material.
13. The method of claim 10 , wherein the insulator layer includes an oxide material.
14. The method of claim 10 , wherein the source/drain region includes a crystalline semiconductor material.
15. The method of claim 10 , wherein the gate stack is a high-k metal gate stack.
16. The method of claim 10 , wherein the removing portions of the layer of spacer material to form a spacer includes an anisotropic etching process.
17. The method of claim 10 , wherein the conductive material includes a conductive metal.