Iterative self-aligned patterning

1. A method for self-aligned patterning, the method comprising: providing a substrate; forming a patterned mandrel layer that includes a plurality of mandrel features, the patterned mandrel layer being formed on the substrate; depositing a first spacer layer over the mandrel layer, the first spacer layer comprising a first type of material; anisotropically etching the first spacer layer with a first etchant to leave a first set of spacers on sidewalls of the mandrel features; removing the mandrel layer; depositing a second spacer layer over remaining portions of the first set of spacers; and anisotropically etching the second spacer layer with a second etchant to form a second set of spacers on sidewalls of the first set of spacers, the second etchant being different than the first etchant, removing the first set of spacers of the first spacer layer.

2. The method of claim 1 , further comprising:

forming a third spacer layer over remaining portions of the second spacer layer, the third spacer layer comprising a same type of material as the first spacer layer.

3. The method of claim 1 , further comprising,

performing an etch process to remove a portion of the substrate exposed through the second spacer layer.

4. The method of claim 1 , further comprising:

forming a dielectric layer over the second spacer layer;

performing a Chemical Mechanical Polishing (CMP) process to expose the first spacer layer; and

removing the first spacer layer and the dielectric layer.

5. The method of claim 1 , wherein the first type of material comprises a dielectric material.

6. The method of claim 1 , wherein the dielectric material comprises at least one of: an oxide, silcon nitride (SiN), silicon oxynitride (SiON), silicon carbide (SiC), silicon carbon nitride (SiCN), or silicon oxycarbon nitride (SiOCN).

7. The method of claim 1 , wherein the second type of material comprises a conductive material.

8. The method of claim 1 , wherein the second type of material comprises at least one of: amorphous silicon or amorphous carbon.

9. The method of claim 1 , wherein a width of the mandrel, a width of the first spacer layer, and a width of the second spacer layer are selected to create a merge feature.

10. A method for iterative self-aligned patterning, the method comprising: providing a substrate; forming a patterned mandrel layer on the substrate; depositing a first spacer layer over the mandrel layer such that the first spacer layer conforms to the mandrel layer, the first spacer layer comprising a first type of material; performing a first anisotropic etching process to the first spacer layer using a first etchant, thereby leaving a first set of spacers on sidewalls of the mandrel layer; removing the mandrel layer; forming a second spacer layer over the first set of spacers such that the second spacer layer conforms to the first set of spacers, the second spacer layer comprising a second type of material different from the first type of material; and performing a second anisotropic etching process to the second spacer layer using a second etchant different from the first etchant, thereby forming a second set of spacers on sidewalls of the first set of spacers, removing the first set of spacers of the first spacer layer.

11. The method of claim 10 , further comprising, forming a dielectric layer over the second spacer layer such that the dielectric layer is formed between features of the second spacer layer and covers the features of the second spacer layer.

12. The method of claim 11 , further comprising, performing a planarizing process to expose the first spacer layer.

13. The method of claim 12 , further comprising, performing a dry etch process to remove the first spacer layer, the dry etch process being selective between the first type of material and the second type of material.

14. The method of claim 13 , further comprising, forming a third spacer layer such that the third spacer layer conforms to remaining portions of the second spacer layer, the third spacer layer comprising the first type of material.

15. The method of claim 14 , further comprising:

removing a portion of the third spacer layer to expose the second spacer layer; and

performing a dry etch process to remove the second spacer layer, the dry etch process being selective between the first type of material and the second type of material.

16. The method of claim 10 , wherein the first etchant selectively removes the first type of material while leaving the second type of material substantially intact and the second etchant selectively removes the second type of material while leaving the first type of material substantially intact.

17. A method for iterative self-aligned patterning, the method comprising:

providing a substrate;

forming a patterned mandrel layer on the substrate;

forming a first set of spacers on sidewalls of the mandrel layer, the first set of spacers comprising a first type of material;

removing the mandrel layer;

forming a second set of spacers on sidewalls of the first set of spacers, the second set of spacers comprising a second type of material;

removing the first set of spacers;

forming a third set of spacers on sidewalls of the second set of spacers, the third set of spacers comprising the first type of material; and

removing the second set of spacers.

18. The method of claim 17 , wherein the first type of material is a dielectric material and the first dry etch process utilizes a fluorine based gas.

19. The method of claim 17 , wherein the second type of material is a conductive material and the second dry etch process utilizes a chlorine based gas.