Sidewall image transfer (SIT) technologies

1. A structure fabrication method, comprising:

providing a structure which comprises (a) a to-be-etched layer, (b) a memory region on the to-be-etched layer, (c) a positioning region on the memory region such that the memory region is sandwiched between the to-be-etched layer and the positioning region, (d) and a capping region on the positioning region such that the positioning region is sandwiched between the memory region and the capping region;

indenting the positioning region so as to undercut the capping region;

forming a conformal protective layer on exposed-to-ambient surfaces of the structure after said indenting is performed;

removing portions of the conformal protective layer so as to expose the capping region to the surrounding ambient without exposing the memory region to the surrounding ambient;

removing the capping region, after said removing the portions of the conformal protective layer is performed, so as to expose the positioning region to the surrounding ambient;

removing the positioning region, after said removing the capping region is performed, so as to expose the memory region to the surrounding ambient; and

directionally etching the memory region with remaining portions of the conformal protection layer serving as a blocking mask for said directionally etching the memory region, after said removing the positioning region is performed.

2. The method of claim 1 , wherein the positioning region comprises an oxide material.

3. The method of claim 1 , wherein the capping region does not comprise a photoresist material.

4. The method of claim 1 , further comprising directionally etching the to-be-etched layer with the etched memory region serving as a blocking mask for said directionally etching the to-be-etched layer, after said directionally etching the memory region is performed.

5. The method of claim 1 ,

wherein the positioning region comprises an oxide material, and

wherein said indenting the positioning region comprises performing a chemical oxide removal process to the structure.

6. The method of claim 5 , wherein said performing the chemical oxide removal process to the structure comprises exposing the structure to a gaseous mixture comprising HF.

7. The method of claim 1 , wherein said forming the conformal protective layer comprises performing a chemical vapor deposition of a material on the exposed-to-ambient surfaces of the structure.

8. The method of claim 1 , wherein said removing the portions of the conformal protective layer comprises directionally etching the conformal protective layer.

9. The method of claim 8 , wherein the conformal protective layer comprises tungsten.

10. The method of claim 1 , wherein said directionally etching the memory region is a reactive ion etching process.

11. A structure fabrication method, comprising:

providing a structure which comprises (a) a to-be-etched layer, (b) a memory layer on the to-be-etched layer, (c) a positioning layer on the memory layer such that the memory layer is sandwiched between the to-be-etched layer and the positioning layer, (d) and a capping region on the positioning layer such that the positioning layer is sandwiched between the memory layer and the capping region;

directionally etching the positioning layer and the memory layer with the capping region serving as a blocking mask for said directionally etching the positioning layer and the memory layer, wherein what remain of the positioning layer and the memory layer as a result of said directionally etching the positioning layer and the memory layer comprise a positioning region and a memory region, respectively;

indenting the positioning region so as to undercut the capping region; forming a conformal protective layer on exposed-to-ambient surfaces of the structure after said indenting is performed;

removing portions of the conformal protective layer so as to expose the capping region to the surrounding ambient without exposing the memory region to the surrounding ambient;

removing the capping region, after said removing the portions of the conformal protective layer is performed, so as to expose the positioning region to the surrounding ambient;

removing the positioning region, after said removing the capping region is performed, so as to expose the memory region to the surrounding ambient; and

directionally etching the memory region with remaining portions of the conformal protection layer serving as a blocking mask for said directionally etching the memory region, after said removing the positioning region is performed.

12. The method of claim 11 , wherein the positioning region comprises an oxide material.

13. The method of claim 12 , wherein the oxide material comprises silicon dioxide.

14. The method of claim 11 , further comprising directionally etching the to-be-etched layer with the etched memory region serving as a blocking mask for said directionally etching the to-be-etched layer, after said directionally etching the memory region is performed.

15. The method of claim 11 ,

wherein the positioning region comprises an oxide material, and

wherein said indenting the positioning region comprises performing a chemical oxide removal process to the structure.

16. A structure fabrication method, comprising:

providing a structure which comprises (a) a to-be-etched layer, (b) a memory region on the to-be-etched layer, (c) a positioning region on the memory region such that the memory region is sandwiched between the to-be-etched layer and the positioning region, (d) and a capping region on the positioning region such that the positioning region is sandwiched between the memory region and the capping region;

indenting the positioning region so as to undercut the capping region;

forming a protective layer on exposed-to-ambient surfaces of the structure after said indenting is performed;

removing portions of the protective layer so as to expose the capping region to the surrounding ambient without exposing the memory region to the surrounding ambient;

removing the capping region, after said removing the portions of the protective layer is performed, so as to expose the positioning region to the surrounding ambient;

removing the positioning region, after said removing the capping region is performed, so as to expose the memory region to the surrounding ambient; and

directionally etching the memory region with remaining portions of the protection layer serving as a blocking mask for said directionally etching the memory region, after said removing the positioning region is performed.

17. The method of claim 16 , wherein the positioning region comprises an oxide material.

18. The method of claim 17 , wherein the oxide material comprises silicon dioxide.

19. The method of claim 16 ,

wherein the positioning region comprises an oxide material, and

wherein said indenting the positioning region comprises performing a chemical oxide removal process to the structure.

20. The method of claim 16 , wherein said forming the protective layer comprises spin-applying an organic material on exposed-to-ambient surfaces of the structure.

21. A structure fabrication method, comprising:

providing a structure which comprises (a) a to-be-etched layer, (b) a memory region on the to-be-etched layer, (c) a positioning region on the memory region such that the memory region is sandwiched between the to-be-etched layer and the positioning region;

indenting the positioning region such that a first memory portion of the memory region becomes not directly beneath the indented positioning region as a result of said indenting, while a second memory portion of the memory region remains directly beneath the indented positioning region;

selectively growing a protective region onto exposed-to-ambient surfaces of the first memory portion of the memory region but not onto exposed-to-ambient surfaces of the positioning region; removing the positioning region, after said selectively growing is performed, so as to expose the second memory portion of the memory region to the surrounding ambient; and

directionally etching the second memory portion of the memory region with the protective region serving as a blocking mask, after said removing the positioning region is performed.

22. The method of claim 21 , wherein the positioning region comprises an oxide material.

23. The method of claim 22 , wherein the oxide material comprises silicon dioxide.

24. The method of claim 21 ,

wherein the positioning region comprises an oxide material, and

wherein said indenting the positioning region comprises performing a chemical oxide removal process to the structure.

25. The method of claim 24 , wherein said performing the chemical oxide removal process to the structure comprises exposing the structure to a gaseous mixture comprising HF.

26. The method of claim 21 , wherein said selectively growing the protective region comprises selectively growing germanium onto the exposed-to-ambient surfaces of the first memory portion, but not onto the exposed-to-ambient surfaces of the positioning region.

27. The method of claim 26 , wherein the memory region comprises polysilicon, and wherein the positioning region comprises an oxide material.

28. The method of claim 21 , wherein said selectively growing the protective region comprises growing materials onto exposed-to-ambient surfaces of the to-be-etched layer.

29. The method of claim 21 , wherein said selectively growing the protective region does not comprise growing materials onto exposed-to-ambient surfaces of the to-be-etched layer.

30. The method of claim 1 , wherein said directionally etching the memory region forms the first memory portion from the memory region.