Fabricating contacts of a CMOS structure
The invention relates to a method comprising providing a substrate with a channel layer, forming a gate stack structure on the channel layer and forming a raised source and a raised drain on the channel layer. The method further comprises depositing in a non-conformal way an oxide layer above the gate stack structure, the raised source and the raised drain. A first void above the raised source and a second void above the raised drain gate are created adjacent to vertical edges of the gate stack structure. The method further comprises etching the oxide layer for a predefined etching time, thereby removing the oxide layer above the raised source and the raised drain, while keeping it at least partly on the channel layer. Contacts are formed to the raised source and the raised drain. The invention also concerns a corresponding computer program product.
1. A semiconductor device comprising:
a substrate with a channel layer;
a gate stack structure disposed on the channel layer;
a raised source and a raised drain disposed on the channel layer;
an oxide layer disposed on one or more portions of the semiconductor device;
a self-aligned contact disposed on the raised source and the raised drain; and
a first dummy gate stack structure adjacent to the raised source and a second dummy gate stack structure adjacent to the raised drain.
2. A semiconductor device as claimed in claim 1 , wherein the gate stack structure comprises:
a gate dielectric layer;
a gate metal layer;
a gate cap layer deposited on the gate metal layer; and
sidewall spacers.
3. A semiconductor device as claimed in claim 2 , wherein the gate dielectric layer is formed as a high-k dielectric layer selected from the group consisting of: HfO 2 , HfON, HfSiON, ZrO 2 , ZrON, HfO 2 , HfON, ZrO 2 , ZrON, LaO 3 , La—Al—O, La—Lu—O, SiN and SiON.
4. A semiconductor device as claimed in claim 1 , further comprising:
a liner on one or more portions of the semiconductor device, the gate stack structure, the raised source and the raised drain.
5. A semiconductor device as claimed in claim 4 , wherein the liner comprises a material selected from the group consisting of: Al 2 O 3 , HfO 2 , ZrO 2 , AlON, SiO 2 , Si 3 N 4 and Hf.
6. A semiconductor device as claimed in claim 4 , wherein the liner includes one or more removed portions above the raised source and the raised drain.
7. A semiconductor device as claimed in claim 1 , wherein the self-aligned contact comprises a metal layer.
8. A semiconductor device as claimed in claim 1 , wherein the substrate is a bulk substrate of a semiconductor material.
9. A semiconductor device as claimed in claim 1 , wherein the substrate is a semiconductor-on-insulator substrate comprising a base substrate layer, an insulating layer and the channel layer on the insulating layer.
10. A device as claimed in claim 1 , wherein the channel layer is comprised of one of: Si x Ge 1-x where x=0 to 1; In x Ga 1-x As where x=0 to 1; InP; InGaSb and further alloyed combinations of (In, Ga) (As, Sb, P).
11. A semiconductor device as claimed in claim 10 , wherein the faceted side portions are angled with an angle from 30 degree to 80 degree relative to a bottom surface of the raised source and the raised drain.
12. A semiconductor device as claimed in claim 1 , wherein the raised source and the raised drain comprises:
a first raised source part and a first raised drain part, the first raised source part and the first raised drain part having a first thickness and being arranged adjacent to the gate stack structure; and
a second raised source part and a second raised drain part, the second raised source part and the second raised drain part having a second thickness, wherein the second thickness is greater than the first thickness.
13. A semiconductor device as claimed in claim 1 , wherein the raised source and the raised drain comprises:
a faceted shape, wherein the raised source and the raised drain each comprise a faceted side portion adjacent to the gate stack structure.
14. A semiconductor device as claimed in claim 1 , wherein the self-aligned contact borders a dummy gate stack structure, the gate stack structure, and the raised source or the raised drain.
15. A semiconductor device as claimed in claim 1 , wherein the self-aligned contact comprises:
a first self-aligned contact that borders the first dummy gate stack structure, the gate stack structure and the raised source; and
a second self-aligned contact that borders the second dummy gate stack structure, the gate stack structure and the raised drain.