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 stack on a channel region of a semiconductor layer, the semiconductor layer on an insulator layer;
forming a spacer adjacent to the gate stack;
forming a crystalline source/drain region in a first cavity in the insulator layer, wherein the spacer is positioned on the source/drain region such that the spacer defines an L-shape and a bottommost edge of the L-shape is coplanar to a surface of the source/drain region;
forming an inter-level dielectric layer over the gate stack and a portion of the source/drain region; and
forming a conductive contact in a second cavity in the inter-level dielectric layer, the second cavity defined by the source/drain region and the spacer.
2. The method of claim 1 , wherein the first cavity in the insulator layer comprises an undercut region defined by the insulator layer and the semiconductor layer.
3. The method of claim 1 , wherein the semiconductor layer includes a doped semiconductor region.
4. The method of claim 1 , wherein the second cavity in the inter-level dielectric layer and the source/drain region expose a portion of the spacer.
5. The method of claim 1 , wherein the second cavity in the inter-level dielectric layer and the source/drain region expose a portion of the doped semiconductor region.
6. The method of claim 1 , wherein the conductive contact comprises dopants.
7. The method of claim 1 , wherein the spacer comprises a nitride.
8. The method of claim 1 , wherein the spacer includes an oxide.
9. A method for forming a semiconductor device, the method comprising:
forming a gate stack on a channel region of a semiconductor layer, the semiconductor layer on an insulator layer, the semiconductor layer comprising a doped semiconductor region;
forming a spacer adjacent to the gate stack;
forming a crystalline source/drain region in a first cavity in the insulator layer, wherein the spacer is positioned over the source/drain region;
forming an inter-level dielectric layer over the gate stack and a portion of the source/drain region;
forming a conductive contact in a second cavity in the inter-level dielectric layer and the source/drain region, the second cavity including an undercut region defined by the spacer, the doped semiconductor region, and the source/drain region.
10. The method of claim 9 , wherein the spacer defines an L-shape.
11. The method of claim 9 , wherein the first cavity is an undercut region defined by the insulator layer and the semiconductor layer.
12. The method of claim 9 , wherein the conductive contact includes dopants.
13. The method of claim 9 , wherein the spacer includes a nitride.
14. The method of claim 9 , wherein the spacer includes an oxide.