Methods for clearing alignment markers useable in semiconductor lithography

• US 20050250291A1
• Filed: 05/06/2004
• Published: 11/10/2005
• Est. Priority Date: 05/06/2004
• Status: Abandoned Application

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Baluswamy, Pary, Benson, Peter
• Application Number:
  US10/840,324
• Publication Number:
  US 20050250291A1
• Time in Patent Office: Days
• US Class Current: 438/401
• CPC Class Codes: G03F 9/708 Mark formation
• CPC Class Codes: G03F 9/7084 Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels
• CPC Class Codes: H01L 2223/5442 comprising non digital, non alphanumeric information, e.g. symbols
• CPC Class Codes: H01L 2223/54453 for use prior to dicing
• CPC Class Codes: H01L 2223/5446 Located in scribe lines
• CPC Class Codes: H01L 23/544 Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps test patterns for characterising or monitoring manufacturing processes H01L22/00
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

Disclosed herein are methods for removing overlying materials on a substrate which otherwise might optically obscure an underlying photolithography alignment marker. According to the disclosed techniques, laser radiation is used to remove the material (e.g., a metal) in an area which overlies the alignment marker (e.g., formed in polysilicon). Such removal can comprise the use of laser ablation or laser-assisted etching. The substrate is placed on a motor-controlled chuck in a laser removal chamber, and the areas are automatically moved underneath the laser radiation to removal the material. Alternatively, a stencil having holes corresponding to the areas can be placed over the substrate to mitigate the need to move the substrate to the areas with precision. After clearance of the area, photoresist can then be applied to the material with the alignment marker now visible though the removed area, and the now-visible alignment marker can be used to pattern the photoresist to align the material with the alignment marker (and hence, other active structures formed of the same material as the alignment marker).

Claims

1. A method for processing and using an alignment marker on a substrate, comprising:

forming at least one alignment marker on the substrate;

forming a material on the substrate and overlying the at least one alignment marker;

removing the material overlying the at least one alignment marker using radiation;

forming a photoresist over the structure resulting from the proceeding steps; and

assessing the position of at least one alignment marker to pattern the photoresist in alignment with the alignment marker.

2. The method of claim 1, wherein the radiation comprises radiation from a laser.

3. The method of claim 2, wherein the laser radiation removes the material by ablation.

4. The method of claim 2, wherein removing the material further comprises exposing the material to an etchant gas, and wherein the laser radiation interacts with the etchant gas to remove the material.

5. The method of claim 1, wherein assessing the position of the alignment marker comprises an optical assessment.

6. The method of claim 1, further comprising removing the patterned photoresist and etching the material using non-patterned photoresist as a mask.

7. The method of claim 1, wherein patterning the photoresist comprises aligning the assessed position of the alignment marker with a mask.

8. The method of claim 1, wherein the alignment marker is formed in a layer on the substrate.

9. The method of claim 1, wherein the material is opaque.

10. The method of claim 1, wherein removing the material comprises masking the radiation with a stencil offset from the substrate by a distance.

11. The method of claim 1, wherein removing the material overlying the at least one alignment marker comprises removing only the material overlying the at least one alignment marker.

12. A method for processing and using an alignment marker on a substrate, comprising:

forming at least one alignment marker on the substrate;

forming a material on the substrate and overlying the at least one alignment marker;

removing the material overlying the at least one alignment marker without using a photoresist;

forming a photoresist over the structure resulting from the proceeding steps; and

assessing the position of at least one alignment marker to pattern the photoresist in alignment with the alignment marker.

13. The method of claim 12, wherein the removing the material comprises the use of laser radiation.

14. The method of claim 13, wherein the laser radiation removes the material by ablation.

15. The method of claim 13, wherein removing the material further comprises exposing the material to an etchant gas, and wherein the laser radiation interacts with the etchant gas to remove the material.

16. The method of claim 12, wherein assessing the position of the alignment marker comprises an optical assessment.

17. The method of claim 12, further comprising removing the patterned photoresist and etching the material using non-patterned photoresist as a mask.

18. The method of claim 12, wherein patterning the photoresist comprises aligning the assessed position of the alignment marker with a mask.

19. The method of claim 12, wherein the alignment marker is formed in a layer on the substrate.

20. The method of claim 12, wherein the material is opaque.

21. The method of claim 12, wherein removing the material comprises use of a stencil offset from the substrate by a distance.

22. The method of claim 12, wherein removing the material overlying the at least one alignment marker comprises removing only the material overlying the at least one alignment marker.

23. A method for processing and using an alignment marker on a substrate, comprising:

forming at least one alignment marker on the substrate;

forming a material on the substrate and overlying the at least one alignment marker;

removing the material overlying the at least one alignment marker using radiation; and

using the at least one alignment marker to align the substrate.

24. The method of claim 23, wherein the radiation comprises radiation from a laser.

25. The method of claim 24, wherein the laser radiation removes the material by ablation.

26. The method of claim 24, wherein removing the material further comprises exposing the material to an etchant gas, and wherein the laser radiation interacts with the etchant gas to remove the material.

27. The method of claim 23, wherein the alignment marker is formed in a layer on the substrate.

28. The method of claim 23, wherein the material is opaque.

29. The method of claim 23, wherein removing the material comprises masking the radiation with a stencil offset from the substrate by a distance.

30. The method of claim 23, wherein removing the material overlying the at least one alignment marker comprises removing only the material overlying the at least one alignment marker.

31. A method for processing and using an alignment marker on a substrate, comprising:

forming at least one alignment marker on the substrate;

forming a material on the substrate and overlying the at least one alignment marker;

removing the material overlying the at least one alignment marker without using a photoresist; and

using the at least one alignment marker to align the substrate.

32. The method of claim 31, wherein the removing the material comprises the use of laser radiation.

33. The method of claim 32, wherein the laser radiation removes the material by ablation.

34. The method of claim 32, wherein removing the material further comprises exposing the material to an etchant gas, and wherein the laser radiation interacts with the etchant gas to remove the material.

35. The method of claim 31, wherein the alignment marker is formed in a layer on the substrate.

36. The method of claim 31, wherein the material is opaque.

37. The method of claim 31, wherein removing the material comprises use of a stencil offset from the substrate by a distance.

38. The method of claim 31, wherein removing the material overlying the at least one alignment marker comprises removing only the material overlying the at least one alignment marker.

39. A method for processing and using an alignment marker on a substrate, comprising:

forming at least one alignment marker on the substrate;

forming a material on the substrate and overlying the at least one alignment marker;

removing the material overlying the at least one alignment marker using radiation;

forming a photoresist over the structure resulting from the proceeding steps;

using the at least one alignment marker to align the substrate with a mask;

patterning the photoresist using the mask;

removing the patterned photoresist to expose portions of the material; and

etching the exposed portions of the material.

40. The method of claim 39, wherein the radiation comprises radiation from a laser.

41. The method of claim 40, wherein the laser radiation removes the material by ablation.

42. The method of claim 40, wherein removing the material further comprises exposing the material to an etchant gas, and wherein the laser radiation interacts with the etchant gas to remove the material.

43. The method of claim 39, wherein the alignment marker is formed in a layer on the substrate.

44. The method of claim 39, wherein the material is opaque.

45. The method of claim 39, wherein removing the material comprises masking the radiation with a stencil offset from the substrate by a distance.

46. The method of claim 39, wherein removing the material overlying the at least one alignment marker comprises removing only the material overlying the at least one alignment marker.

47. A method for processing and using an alignment marker on a substrate, comprising:

forming at least one alignment marker on the substrate;

forming a material on the substrate and overlying the at least one alignment marker;

removing the material overlying the at least one alignment marker without using a photoresist;

forming a photoresist over the structure resulting from the proceeding steps;

using the at least one alignment marker to align the substrate with a mask;

patterning the photoresist using the mask;

removing the patterned photoresist to expose portions of the material; and

etching the exposed portions of the material.

48. The method of claim 47, wherein the removing the material comprises the use of laser radiation.

49. The method of claim 48, wherein the laser radiation removes the material by ablation.

50. The method of claim 48, wherein removing the material further comprises exposing the material to an etchant gas, and wherein the laser radiation interacts with the etchant gas to remove the material.

51. The method of claim 47, wherein the alignment marker is formed in a layer on the substrate.

52. The method of claim 47, wherein the material is opaque.

53. The method of claim 47, wherein removing the material comprises use of a stencil offset from the substrate by a distance.

54. The method of claim 47, wherein removing the material overlying the at least one alignment marker comprises removing only the material overlying the at least one alignment marker.