Dummy gate interconnect for semiconductor device
A method of forming a semiconductor device comprising a dummy gate interconnect includes forming a dummy gate on a substrate, the dummy gate comprising a dummy gate metal layer located on the substrate, and a dummy gate polysilicon layer located on the dummy gate metal layer; forming an active gate on the substrate, the active gate comprising an active gate metal layer located on the substrate, and an active gate polysilicon layer located on the active gate metal layer; and etching the dummy gate polysilicon layer to remove at least a portion of the dummy gate polysilicon layer to form the dummy gate interconnect, wherein the active gate polysilicon layer is not etched during the etching of the dummy gate polysilicon layer.
1. A method of forming a semiconductor device comprising a dummy gate interconnect, comprising:
forming a dummy gate on a substrate, the dummy gate comprising a dummy gate metal layer located directly on top of the substrate, and a dummy gate polysilicon layer located on the dummy gate metal layer;
forming an active gate on the substrate, the active gate comprising an active gate metal layer located on the substrate, and an active gate polysilicon layer located on the active gate metal layer; and
etching the dummy gate polysilicon layer to remove at least a portion of the dummy gate polysilicon layer to form the dummy gate interconnect, wherein the active gate polysilicon layer is not etched during the etching of the dummy gate polysilicon layer, and wherein the dummy gate metal layer comprises a conductor of the dummy gate interconnect.
2. The method of claim 1 , wherein forming the dummy gate on the substrate further comprises forming a dummy gate cap on top of the dummy gate polysilicon layer; and
wherein forming the active gate on the substrate further comprises forming an active gate cap on top of the active gate polysilicon layer.
3. The method of claim 2 , wherein the dummy gate cap and the active gate cap each comprise nitride.
4. The method of claim 2 , further comprising, before etching the dummy gate polysilicon layer:
removing the active gate cap;
siliciding a portion of the active gate polysilicon layer to form an active gate silicide;
forming source/drain silicide in source/drain regions located on either side of the active gate in the substrate simultaneously with forming the active gate silicide;
forming a protective layer over the substrate, wherein the active gate silicide and the dummy gate cap are not covered by the protective layer;
forming a mask over the active gate silicide after forming the protective layer; and
removing the dummy gate cap;
wherein the active gate silicide is protected by the mask and the substrate is protected by the protective layer during the etching of the dummy gate polysilicon layer.
5. The method of claim 1 , wherein the active gate polysilicon layer and the dummy gate polysilicon layer each further comprise respective etch stop layers comprising titanium nitride (TiN), wherein the dummy gate polysilicon layer is partially removed by the etching of the dummy gate polysilicon layer such that a remaining portion of the dummy gate polysilicon layer is located under the etch stop layer after the etching of the dummy polysilicon layer, and wherein the portion of dummy gate polysilicon layer that is removed by the etching of the dummy gate polysilicon layer is determined by a location of the respective etch stop layer in the dummy gate polysilicon layer.
6. The method of claim 1 , wherein the portion of dummy gate polysilicon layer that is removed by the etching of the dummy gate polysilicon layer is determined by an etch time of the etching of the dummy gate polysilicon layer.
7. The method of claim 1 , wherein all of the dummy gate polysilicon layer is removed by the etching of the dummy gate polysilicon layer.
8. The method of claim 1 , wherein the dummy gate interconnect does not comprise an active device of the semiconductor device, and wherein the dummy gate metal layer that comprises the dummy gate interconnect transmits a signal between a first active device and a second active device in the semiconductor device.
9. The method of claim 2 , further comprising removing the dummy gate cap from the dummy gate before etching the dummy gate polysilicon layer, and wherein the active gate cap protects the active gate polysilicon layer during the etching of the dummy gate polysilicon layer.
10. The method of claim 9 , further comprising forming a protective layer over the substrate before etching the dummy gate polysilicon layer, wherein the active gate cap and the dummy gate polysilicon layer are not covered by the protective layer, and wherein the protective layer protects the substrate during the etching of the dummy gate polysilicon layer.
11. The method of claim 10 , wherein the protective layer comprises one of a polymer material, oxide, and glass.
12. The method of claim 10 , wherein forming the protective layer comprises:
forming an initial layer of a protective layer material over the semiconductor device; and
etching the initial layer to form the protective layer, such that the active gate cap and the dummy gate polysilicon layer are exposed by etching of the initial layer to form the protective layer.
13. The method of claim 10 , wherein forming the protective layer comprises:
spin-coating a protective layer material on the substrate to form the protective layer, wherein the protective layer has a thickness that is less than a height of the active gate cap and the dummy gate polysilicon layer.
14. The method of claim 10 , further comprising:
removing the active gate cap after etching the dummy gate polysilicon layer;
siliciding a portion of the active gate polysilicon layer to form an active gate silicide; and
siliciding a remaining portion of the dummy gate polysilicon layer to form a conductor silicide simultaneously with forming the active gate silicide, wherein the remaining portion of the dummy gate polysilicon layer is fully consumed by the siliciding such that the conductor silicide is in direct contact with the dummy gate metal layer.
15. The method of claim 14 , further comprising:
removing the protective layer before forming the active gate silicide; and
forming source/drain silicide in source/drain regions located on either side of the active gate in the substrate simultaneously with forming the active gate silicide.
16. The method of claim 1 , further comprising:
forming a protective layer over the semiconductor device before etching the dummy gate polysilicon layer, wherein the protective layer covers the active gate and the dummy gate, and wherein the protective layer comprises a conformal etch stop material comprising one of oxide and nitride;
removing the protective layer from the dummy gate; and
etching the dummy gate polysilicon layer, wherein the protective layer protects the active gate polysilicon layer and the substrate during the etching of the dummy gate polysilicon layer.
17. The method of claim 16 , further comprising:
removing the protective layer from the semiconductor device after etching the dummy gate polysilicon layer;
siliciding a portion of the active gate polysilicon layer to form an active gate silicide;
siliciding a remaining portion of the dummy gate polysilicon layer to form a conductor silicide simultaneously with forming the active gate silicide, wherein the remaining portion of the dummy gate polysilicon layer is fully consumed by the siliciding such that the conductor silicide is in direct contact with the dummy gate metal layer; and
forming source/drain silicide in source/drain regions located on either side of the active gate in the substrate simultaneously with forming the active gate silicide.