COMPOSITIONS AND METHODS FOR SUBSTANTIALLY EQUALIZING RATES AT WHICH MATERIAL IS REMOVED OVER AN AREA OF A STRUCTURE OR FILM THAT INCLUDES RECESSES OR CREVICES

• US 20090042401A1
• Filed: 08/06/2007
• Published: 02/12/2009
• Est. Priority Date: 08/06/2007
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Sinha, Nishant, Greeley, J. Neil
• Granted Patent: US 8,153,019 B2
• Time in Patent Office: Days
• US Class Current: 438/754
• CPC Class Codes: C09K 13/06 with organic material
• CPC Class Codes: C09K 13/08 containing a fluorine compound
• CPC Class Codes: H01L 21/31055 the removal being a chemical etching step, e.g. dry etching etching per se H01L21/311
• CPC Class Codes: H01L 21/31111 by chemical means

Abstract

Methods for preventing isotropic removal of materials at corners formed by seams, keyholes, and other anomalies in films or other structures include use of etch blockers to cover or coat such corners. This covering or coating prevents exposure of the corners to isotropic etch solutions and cleaning solutions and, thus, higher material removal rates at the corners than at smoother areas of the structure or film from which material is removed. Solutions, including wet etchants and cleaning solutions, that include at least one type of etch blocker are also disclosed, as are systems for preventing higher rates of material removal at corners formed by seams, crevices, or recesses in a film or other structure. Semiconductor device structures in which etch blockers are located so as to prevent isotropic etchants from removing material from corners of seams, crevices, or recesses in a surface of a film or other structure at undesirably high rates are also disclosed.

Claims

1. A method for isotropic etching, comprising:

exposing a film or other structure that includes at least anomaly at an exposed surface of the film or other structure to a wet etchant that includes at least one etch blocker; and

generating pressure waves in the wet etchant to remove the at least one etch blocker from the exposed surface while allowing the at least one etch blocker to remain within the at least one seam, crevice, or recess.

2. The method of claim 1, comprising exposing a film or other structure comprising tungsten to the wet etchant.

3. The method of claim 1, comprising exposing a film or other structure comprising polysilicon to the wet etchant.

4. The method of claim 1, wherein exposing comprises exposing a film that has been conformally deposited so as to fill at least one contact hole or trench and that includes a seam located over the at least one contact hole or trench to the wet etchant.

5. The method of claim 4, wherein exposing comprises exposing a film comprising titanium nitride to the wet etchant.

6. The method of claim 1, wherein exposing the film or other structure includes the at least one etch blocker preventing at least one corner of the at least one anomaly from being substantially exposed to an etch solution of the wet etchant.

7. The method of claim 6, wherein preventing includes covering the at least one corner with the at least one etch blocker.

8. The method of claim 6, wherein preventing includes adsorption of the at least one etch blocker to the at least one corner or to a location of the structure or film adjacent to the at least one corner.

9. The method of claim 1, wherein exposing comprises exposing the film or other structure to a wet etchant in which the etch blocker comprises a surfactant.

10. The method of claim 9, wherein exposing comprises exposing the film or other structure to a wet etchant that includes at least one anionic surfactant.

11. The method of claim 9, wherein exposing comprises exposing the film or other structure to a wet etchant that includes at least one cationic surfactant.

12. The method of claim 9, wherein exposing comprises exposing the film or other structure to a wet etchant that includes at least one nonionic surfactant or at least one amphoteric surfactant.

13. The method of claim 9, further comprising:

selecting the surfactant included with the wet etchant based at least in part upon an isoelectric point of a material to be removed with the wet etchant.

14. A wet etchant comprising:

an etch solution; and

at least one etch blocker configured to be retained within seams, crevices, or recesses opening onto an exposed surface of a film or other structure to prevent the etch solution from isotropically removing material from corners of the seams, crevices, or recesses.

15. The wet etchant of claim 14, wherein the etch solution comprises at least one of a buffered oxide etchant, hydrofluoric acid, and isopropanol.

16. The wet etchant of claim 14, wherein the at least one etch blocker has a particle size that prevents the etch solution from contacting the corners.

17. The wet etchant of claim 14, wherein the at least one etch blocker is configured to adsorb to the corners to prevent etch solution from contacting the corners.

18. The wet etchant of claim 14, wherein an ionic strength of the etch solution enables the etch blocker to adsorb to the structure or film.

19. The wet etchant of claim 14, wherein the at least one etch blocker comprises a surfactant.

20. The wet etchant of claim 19, wherein the surfactant comprises at least one of a nonionic surfactant, anionic surfactant, a cationic surfactant, and an amphoteric surfactant.

21. The wet etchant of claim 19, wherein the surfactant comprises at least one of a fluorosurfactant, cetyl trimethylammonium bromide, and C₁₄H₂₂O (C₂H₄O)_n.

22. A semiconductor device structure, comprising:

a structure or film including at least one exposed surface and at least one seam, crevice, or recess opening thereonto;

an etch blocker disposed in the at least one seam, crevice, or recess in a substantially higher concentration than on the at least one exposed surface.

23. The semiconductor device structure of claim 22, further comprising:

an etch solution disposed on the at least one exposed surface, wherein the etch blocker is positioned to prevent the etch solution from contacting a corner of the at least one seam, crevice, or recess or preventing the etch solution from entering the at least one seam, crevice, or recess.

24. A material removal system, comprising:

a substrate holder configured to retain a fabrication substrate for contact of at least one structure or feature of a substrate to a wet etchant comprising an etch solution and etch blocker disposed over an exposed surface of the fabrication substrate; and

apparatus for generating pressure waves in wet etchant over the at least one structure or feature.

25. The material removal system of claim 24, wherein the apparatus for generating pressure waves is configured to sonically generate pressure waves in the wet etchant or to induce cavitation in the wet etchant.

26. The material removal system of claim 24, wherein the apparatus for generating pressure waves is configured to apply force to the exposed surface of the fabrication substrate or to generate a high velocity on the exposed surface.

27. The material removal system of claim 24, wherein the apparatus for generating pressure waves is configured to direct the pressure waves in a direction substantially parallel to a plane in which the substrate holder is configured to retain the substrate.

28. A method for fabricating a semiconductor device structure, comprising:

exposing a film or structure that includes at least one anomaly to a wet etchant that includes at least one etch blocker; and

generating pressure waves across a surface of the film or structure.

29. The method of claim 28, wherein generating pressure waves includes removing etch blocker from smooth surfaces of the film or structure.

30. A method for fabricating a semiconductor device structure, comprising:

applying an etchant mixture including an isotropic etchant and an etch blocker to an exposed surface of a structure or film from which material is to be removed, the etchant and etch blocker interacting with one another such that the etch blocker non-specifically adsorbs to all areas of the exposed surface and enables the isotropic etchant to remove material at all areas of the exposed surface, including regions in which at least one crevice or recess is located, at substantially the same rate.

31. The method of claim 30, wherein applying the etchant mixture comprises applying an etchant mixture in which the etch blocker comprises a non-ionic material.

32. The method of claim 30, wherein applying the etchant mixture comprises applying an etchant mixture including at least one of a non-ionic surfactant and a surface active polymer.

33. The method of claim 30, wherein applying the etchant mixture comprises applying an etchant mixture in which the isotropic etchant comprises a buffered oxide etchant.

34. The method of claim 30, wherein applying the etchant mixture comprises applying an etchant mixture including at most about one percent, by volume, of the etch blocker.

35. The method of claim 30, wherein applying the etchant mixture comprises applying an etchant mixture including at most about twenty percent, by volume, of the etch blocker.