Method for forming and planarizing adjacent regions of an integrated circuit

1. A method of forming and planarizing adjacent regions of an integrated circuit, the method comprising:

providing a first region of an integrated circuit and a second region of an integrated circuit, the second region having an initial height;

forming an array of features in the first region, the array having an edge, the edge comprising a boundary between the first region and the second region, forming the array comprising:

forming a pattern of mandrel lines over a substrate;

blanket depositing spacer material over and between the mandrel lines;

removing the portion of the spacer material that overlies the mandrel lines to form spacers on either side of each mandrel line; and

removing the mandrel lines while allowing the spacers to remain and form the array of features in the first region, the array of features having a feature height that is higher than the initial height of the second region;

blanket depositing a filler material on and between the features in the first region and on the second region;

blanket depositing a protective material on the filler material in both the first region and the second region; and

performing a two-step etch comprising:

in a first step, removing the protective material until the portion of the protective material that overlies the first region is completely removed and the portion of the protective material that overlies the second region is only partially removed; and

in a second step, removing the filler material to reduce the height of the first region down to a height of the portion of the protective material in the second region.

2. The method of claim 1 , wherein the second step further comprises continuing to remove the filler and protective materials until the materials have reached a third, planarized height.

3. The method of claim 2 , wherein the third height is at least as low as the feature height.

4. The method of claim 2 , wherein the third height is approximately the same as the feature height.

5. The method of claim 2 , wherein the second step further comprises stopping removal of the protective layer and the filler material when the protective material is completely removed in the second region.

6. The method of claim 1 , wherein blanket depositing the filler material is continued such that the height of the filler material is taller than the feature height, so that, during the two-step etch, the protective material is completely removed from the first region before the tops of the features are exposed.

7. The method of claim 6 , wherein the second etch continues to remove the filler material to reduce the height of the filler material in the first and second regions down to the feature height, exposing the tops of the features.

8. The method of claim 1 , further comprising performing an additional etch to removal additional material and further planarize.

9. The method of claim 8 , wherein the additional etch comprises a CMP process.

10. The method of claim 1 , further comprising patterning photoresist lines and reducing a width of the photoresist lines before transferring the photoresist pattern to a layer of expendable material to form the mandrel lines.

11. The method of claim 1 , wherein blanket depositing a protective material further comprises depositing the protective material such that the protective material is thinner in the first region and thicker in the first region.

12. The method of claim 1 , further comprising spinning the substrate while applying the protective material as a spin-on film.

13. The method of claim 1 , wherein the first step of the two-step etch uses a dry etch chemistry.

14. The method of claim 1 , wherein the first step of the two-step etch is a reactive ion etch.

15. The method of claim 1 , wherein the first step of the two-step etch is a CMP process.

16. The method of claim 1 , wherein the second step of the two-step etch is a fluorocarbon etch.