T-shaped contacts for semiconductor device
A transistor, planar or non-planar (e.g., FinFET), includes T-shaped contacts to the source, drain and gate. The top portion of the T-shaped contact is wider than the bottom portion, the bottom portion complying with design rule limits. A conductor-material filled trench through a multi-layer etching stack above the transistor provides the top portions of the T-shaped contacts. Tapered spacers along inner sidewalls of the top contact portion prior to filling allow for etching a narrower bottom trench down to the gate, and to the source/drain for silicidation prior to filling.
1. A method, comprising:
providing a starting semiconductor structure, the structure comprising a semiconductor substrate, an active layer with one or more active regions, at least one gate over a portion of the active layer, and a layer of filler material on both sides of the at least one gate;
creating a multi-layer etching stack over the starting structure, the multi-layer etching stack comprising a dielectric layer between top and bottom hard mask layers, wherein only the dielectric layer and bottom hard mask layers are used as etch stops; and
creating T-shaped contacts thru the multi-layer etching stack to the one or more active regions and the at least one gate, wherein each T-shaped contact uses a single fill of bulk conductive material.
2. The method of claim 1 , wherein creating the T-shaped contacts comprises:
creating T-shaped trenches to the one or more active regions and the at least one gate;
creating silicide on the at least one raised structure; and
filling the T-shaped trenches with at least one conductive material.
3. The method of claim 2 , wherein creating the T-shaped trenches comprises:
creating top portions of the T-shaped trenches; and
creating bottom portions of the T-shaped trenches, wherein the top portions are wider than the bottom portions.
4. The method of claim 3 , wherein the at least one gate comprises at least two gates, and wherein a width of the top portions of the T-shaped trenches for the one or more active regions have a width of from about half to about two-thirds of a gate pitch for the at least two gates.
5. The method of claim 3 , wherein the at least one gate comprises at least two gates, and wherein a width of the top portions of the T-shaped trenches for the at least two gates have a width of from about half to about three-fourths of a gate pitch for the at least two gates.
6. The method of claim 1 , wherein creating top portions of the T-shaped trenches comprises:
etching the top hard mask layer and stopping on the dielectric layer; and
etching the top and bottom dielectric layers and stopping on the bottom hard mask layer.
7. The method of claim 6 , wherein surrounding the at least one gate is a gate cap and spacers, and wherein creating the bottom potions of the T-shaped trenches comprises:
creating tapered spacers along inner sidewalls of the top portions of the T-shaped trenches;
etching through the bottom hard mask layer;
removing the tapered spacers;
etching through the layer of filler material to the one or more active regions prior to creating the silicide; and
etching through the gate cap to the gate.
8. The method of claim 1 , wherein the starting structure comprises a starting non-planar semiconductor structure, the non-planar structure further comprising at least one raised semiconductor structure coupled to substrate with an isolation material on both sides thereof, wherein the active layer is situated at a top portion of the at least one raised structure, and wherein the at least one gate surrounds the portion of the active layer.
9. The method of claim 8 , wherein creating the T-shaped contacts comprises:
creating T-shaped trenches to the one or more active regions and the at least one gate;
creating silicide on the at least one raised structure; and
filling the T-shaped trenches with at least one conductive material.
10. The method of claim 9 , wherein creating the T-shaped trenches comprises:
creating top portions of the T-shaped trenches; and
creating bottom portions of the T-shaped trenches, wherein the top portions are wider than the bottom portions.
11. The method of claim 10 , wherein creating the multi-layer etching stack comprises:
creating a bottom hard mask layer over the starting structure;
creating a layer of one or more dielectric materials over the bottom hard mask layer; and
creating a top hard mask layer over the dielectric layer.
12. The method of claim 11 , wherein creating the top portions of the T-shaped trenches comprises:
etching the top hard mask layer and stopping on the dielectric layer; and
etching the top and bottom dielectric layers and stopping on the bottom hard mask layer.
13. The method of claim 12 , wherein surrounding the at least one gate is a gate cap and spacers, and wherein creating the bottom potions of the T-shaped trenches comprises:
creating tapered spacers along inner sidewalls of the top portions of the T-shaped trenches;
etching through the bottom hard mask layer;
removing the tapered spacers;
etching through the layer of filler material to the one or more active regions prior to creating the silicide; and
etching through the gate cap to the gate.
14. The method of claim 10 , wherein the at least one gate comprises at least two gates, and wherein a width of the top portions of the T-shaped trenches for the one or more active regions have a width of from about half to about two-thirds of a gate pitch for the at least two gates.
15. The method of claim 10 , wherein the at least one gate comprises at least two gates, and wherein a width of the top portions of the T-shaped trenches for the at least two gates have a width of from about half to about three-fourths of a gate pitch for the at least two gates.