Aligning conductive vias with trenches
A method for forming conductive contacts on a wafer comprises forming a first hardmask, planarizing layer, second hardmask, and a layer of sacrificial mandrel material, and removing portions of the layer of sacrificial mandrel material to expose portions of the second hardmask and form a first and second sacrificial mandrel. Spacers are formed adjacent to the sacrificial mandrels. A filler material is deposited on the second hardmask, and a first mask is formed on the filler material. An exposed portion of the second sacrificial mandrel is removed to form a first cavity. The depth of the first cavity is increased. The first mask, portions of the first and second sacrificial mandrels, the filler material, portions of the second hardmask, the spacers, portions of the planarization layer and the first hardmask are removed. A second cavity is formed and the first and second cavities are filled with a conductive material.
1. A method for forming conductive contacts on a semiconductor wafer, the method comprising:
forming a hardmask on an insulator layer, a planarizing layer on the hardmask and a layer of sacrificial mandrel material on the planarizing layer;
removing portions of the layer of sacrificial mandrel material to expose portions of the planarizing layer and form a first sacrificial mandrel and a second sacrificial mandrel on the planarizing layer;
depositing a layer of spacer material over the planarizing layer, the first sacrificial mandrel and the second sacrificial mandrel;
depositing a first filler material over the layer of spacer material;
patterning a first mask over the filler material;
removing portions of the first filler material to expose a portion of the layer of spacer material over a portion of the first sacrificial mandrel and removing the mask;
removing a portion of the layer of spacer material and an exposed portion of the first sacrificial mandrel to form a first cavity that exposes a portion of the planarizing layer;
filling the first cavity with a second filler material;
patterning a second mask over the first filler material;
removing portions of the first filler material to form a second cavity that exposes portions of the layer of spacer material between the first cavity and the second sacrificial mandrel;
filling the second cavity with the second filler material;
patterning a third mask over a portion of the second sacrificial mandrel;
selectively removing exposed portions of the second filler material, a portion of the layer of spacer material, the planarizing layer and the hardmask to form a third cavity;
patterning a fourth mask over a portion of the second sacrificial mandrel;
removing an exposed portion of the second sacrificial mandrel, a portion of the planarizing layer and a portion of the hardmask to form a fourth cavity;
removing exposed portions of the insulator layer to increase a depth of the third cavity and a depth of the fourth cavity; and
filling the third cavity and the fourth cavity with a conductive material.
2. The method of claim 1 , further comprising prior to removing the exposed portions of the insulator layer to increase a depth of the first cavity and a depth of the second cavity, removing the first sacrificial mandrel and the second sacrificial mandrel.
3. The method of claim 2 , further comprising removing exposed portions of the planarizing layer and the hardmask after removing the exposed portions of the insulator layer to increase a depth of the first cavity and a depth of the second cavity.
4. The method of claim 3 , further comprising removing exposed portions of the insulator layer to form a fourth cavity.
5. The method of claim 4 , further comprising filling the fourth cavity with the conductive material while filling the first cavity and the second cavity with the conductive material.
6. The method of claim 1 , wherein the conductive material in the first cavity contacts an underlying conductive material.
7. The method of claim 1 , wherein the third cavity defines a conductive via and the second cavity defines a conductive via.
8. The method of claim 1 , wherein the sacrificial mandrel material, the spacer material, and the filler material are dissimilar materials.
9. The method of claim 1 , wherein the spacer material includes an oxide material.
10. The method of claim 1 , wherein the layer of sacrificial mandrel material includes a semiconductor material.
11. The method of claim 1 , wherein the filler material includes a flowable carbide material.
12. The method of claim 1 , wherein the spacer material includes silicon oxide.
13. The method of claim 1 , wherein the spacer material includes a dielectric nitride.
14. The method of claim 1 , wherein the spacer material includes silicon nitride.
15. The method of claim 1 , wherein the spacer material includes a dielectric oxynitride.
16. The method of claim 1 , wherein removing portions of the first filler material to form the second cavity includes a reactive ion etching process.
17. The method of claim 1 , wherein removing exposed portions of the insulator layer to increase a reactive ion etching process.
18. The method of claim 1 , wherein removing exposed portions of the insulator layer to increase a depth of the third cavity and a depth of the fourth cavity includes removing exposed portions of the insulator layer to form trenches in the insulator layer.
19. The method of claim 18 , wherein filling the third cavity and the fourth cavity with a conductive material includes filling the trenches with the conductive material.
20. The method of claim 19 , wherein the trenches define conductive lines.