Method and apparatus for endpoint detection

• US 20040005769A1
• Filed: 07/03/2002
• Published: 01/08/2004
• Est. Priority Date: 07/03/2002
• Status: Abandoned Application

• Current Assignee: Cabot Microelectronics Corporation (Entegris Incorporated)
• Original Assignee: Cabot Microelectronics Corporation (Entegris Incorporated)
• Inventors: Mikolas, David G.
• Application Number:
  US10/190,243
• Publication Number:
  US 20040005769A1
• Time in Patent Office: Days
• US Class Current: 438/612
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 49/04 involving measurement of the workpiece at the place of grinding during grinding operation
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: H01L 21/31053 involving a dielectric removal step

Abstract

This invention relates to methods of detecting a planarization endpoint in chemical mechanical planarization of a substrate wherein a detectable target is located at the endpoint and then detected during the CMP planarization. The invention also relates to layered substrates that contain a detectable target located between a first layer of material and a second layer of material. The invention also relates to methods of chemical mechanical planarization of a substrate.

Claims

1. A method for endpoint detection in chemical mechanical planarization of a substrate having a first layer of material and a second layer of material, wherein the second layer of material has an exposed surface that is planarized by a method comprising:

(a) placing a target at or near a location between the first layer of material and the second layer of material;

(b) planarizing the second layer of material to remove at least a portion of material from the second layer;

(c) detecting the target; and

(d) adjusting said planarizing step in response to detecting the target.

2. The method of claim 1 wherein the target is at least one periodic grating.

3. The method of claim 2 wherein the periodic grating is placed by patterning the periodic grating into said first layer of material and depositing onto said first layer said second layer.

4. The method of claim 1 wherein the first layer of material and the second layer of material are independently selected from the group consisting of metal, dielectric material and adhesive material.

5. The method of claim 2 wherein the first layer of material is a dielectric material and the second layer of material is a dielectric material.

6. The method of claim 5 wherein the first layer of material and the second layer of material have similar indices of refraction.

7. The method of claim 5 wherein the first layer of material and the second layer of material have different planarization properties.

8. The method of claim 1 wherein the target is a fluorescent compound.

9. The method of claim 8 wherein said fluorescent compound contains a trivalent lanthanide.

10. The method of claim 9 wherein said lanthanide is Eu³⁺ or Er³⁺.

11. The method of claim 8 wherein said detection step comprises detecting a change in the level of fluorescence from the substrate.

12. The method of claim 2 wherein the periodic grating has a feature size of about 0.3 to about 1.55 microns.

13. A method of chemical mechanical planarization of a wafer, comprising:

(a) placing the wafer in contact with a polishing substrate,

wherein the wafer comprises a first layer of material, a second layer of material and a target placed at or near a location between the first layer of material and the second layer of material;

(b) applying pressure against the backside of the substrate;

(c) causing relative motion between the wafer and the polishing substrate;

(d) depositing a polishing composition onto the polishing substrate;

(e) planarizing the wafer by removing material from the second layer; and

(f) adjusting the planarization step in response to detecting the target.

14. The method of claim 13 wherein the polishing substrate is a polishing pad.

15. The method of claim 14 wherein the polishing is a fixed abrasive polishing pad.

16. The method of claim 13 wherein the polishing composition includes abrasive particles.

17. The method of claim 13 wherein the target is at least one periodic grating.

18. The method of claim 17 wherein the periodic grating is placed by patterning the periodic grating into said first layer of material and depositing onto said first layer said second layer.

19. The method of claim 17 wherein the first layer of material is a dielectric material and the second layer of material is a dielectric material.

20. The method of claim 19 wherein the first layer of material and the second layer of material have similar indices of refraction.

21. The method of claim 19 wherein the first layer of material and the second layer of material have different planarization properties.

22. The method of claim 13 wherein the target is a fluorescent compound.

23. The method of claim 22 wherein the fluorescent compound is a trivalent lanthanide.

24. The method of claim 22 wherein the fluorescent compound is detected in step (f) by detecting the absence of fluorescence from the substrate.

25. The method of claim 17 wherein the grating has a feature size of about 0.3 to about 1.55 microns.

26. A substrate comprising a first layer of material, a second layer of material and a target placed at or near a location between the first layer of material and the second layer of material.

27. The substrate of claim 26 wherein the target is at least one periodic grating.

28. The substrate of claim 27 wherein the periodic grating is placed by patterning a periodic grating into said first layer of material and depositing onto said first layer said second layer.

29. The substrate of claim 27 wherein the first layer of material is a dielectric material and the second layer of material is a dielectric material.

30. The substrate of claim 29 wherein the first layer of material and the second layer of material have similar indices of refraction.

31. The substrate of claim 29 wherein the first layer of material and the second layer of material have different planarization properties.

32. The substrate of claim 26 wherein the target is a fluorescent compound.

33. The substrate of claim 26 wherein the fluorescent compound contains a trivalent lanthanide.

34. The substrate of claim 33 wherein said lanthanide is Eu³⁺ +or Er³⁺.

35. The substrate of claim 27 wherein the grating has a feature size of about 0.3 to about 1.55 microns.

36. A method of detecting an event during chemical mechanical planarization of a substrate having a lower layer of material and an upper layer of material, comprising:

placing a first target having a first distinguishable characteristic at or near a first event on the substrate, wherein the first target is encoded for the first event;

placing a second target having a second distinguishable characteristic at or near a second event on the substrate, wherein the second target is encoded for the second event;

planarizing the upper layer of material to remove at least a portion of material from the upper layer;

observing the first or second target; and

adjusting the planarization step in response to observing the first or second target.

37. The method of claim 36 wherein said observation step comprises passing the first and second targets through a field of view of an optical detection system, wherein the optical detection system is tuned to distinguish the first and second targets based on the distinguishable characteristic of the targets.

38. The method of claim 37 wherein the first target is a periodic grating and the second target is a periodic grating.

39. The method of claim 38 wherein the distinguishable characteristic of the first grating is pitch size and the distinguishable characteristic of the second grating is pitch size.

40. The method of claim 39 wherein the pitch size of the first grating is different from the pitch size of the second grating.

41. The method of claim 40 wherein the pitch size of the first grating is in the range of about 0.5 to 3 microns and the pitch size of the second grating is in the range of about 0.5 to 3 microns.

42. The method of claim 38 wherein the distinguishable characteristic of the first grating is orientation and the distinguishable characteristic of the second grating is orientation.

43. The method of claim 42 wherein the orientation of the first grating is different from the orientation of the second grating.

44. The method of claim 43 wherein the first grating is rotated by about 90 degrees relative to the second grating.

45. The method of claim 36 wherein the first event is a region of high pattern density.

46. The method of claim 36 wherein the second event is a region of low pattern density.