Finishing method for semiconductor wafers using a lubricating boundary layer

• US 6,541,381 B2
• Filed: 01/22/2001
• Issued: 04/01/2003
• Est. Priority Date: 11/06/1998
• Status: Expired due to Term

• Current Assignee: Semcon Tech LLC (IPNav)
• Original Assignee: Beaver Creek Concepts, Inc.
• Inventors: Molnar, Charles J
• Primary Examiner(s): Powell, William A.
• Application Number:
  US09/766,958
• Publication Number:
  US 20010027018A1
• Time in Patent Office: 799 Days
• Field of Search: 438/690, 438/691, 438/692, 438/693, 438/745, 156/345.LP, 156/345.12, 216/38, 216/88, 216/89, 216/91, 252/79.1, 451/41, 451/60, 451/63, 451/287
• US Class Current: 438/690
• CPC Class Codes: B24B 37/20 Lapping pads for working plane surfaces
• CPC Class Codes: B65H 2701/3772 Double-sided
• CPC Class Codes: H01L 21/3212 by chemical mechanical polishing [CMP]

Abstract

A method of using lubricating boundary layers for finishing semiconductor wafers is described. The lubricating boundary layer thickness is controlled to improve finishing and reduce unwanted surface defects. Differential lubricating boundary layer methods are described to differentially finish semiconductor wafers. Planarization and localized finishing can be improved using differential lubricating boundary layer methods of finishing.

Claims

1. A method of finishing of a semiconductor wafer surface being finished having uniform regions and a plurality of wafer die, each wafer die having a repeating pattern of unwanted raised regions, the method comprising the steps of:

providing a finishing element finishing surface;

positioning the semiconductor wafer surface being finished proximate to the finishing surface;

supplying an organic boundary lubricant to an interface between the semiconductor wafer surface being finished and the finishing element finishing surface;

applying an operative finishing motion in the interface between the semiconductor wafer surface being finished and the finishing element finishing surface; and

wherein

applying the operative finishing motion to the operative finishing interface forms an organic lubricating boundary layer of from 1 to 6 molecules thick which interacts with and adheres to the semiconductor wafer surface for at least a portion of the finishing cycle time.

2. The method of finishing of the semiconductor wafer surface being finished having uniform regions and the plurality of wafer die, each wafer die having the repeating pattern of unwanted raised regions according to claim 1 further comprising an additional step of controlling the thickness of the organic lubricating boundary layer by changing at least one process control parameter in situ based on feed back information from a control subsystem.

3. The method of finishing of the semiconductor wafer surface being finished having uniform regions and the plurality of wafer die, each wafer die having the repeating pattern of unwanted raised regions according to claim 1 wherein applying the operative finishing motion causes the unwanted raised regions to have a temperature of at least 7 degrees centigrade higher than that of the proximate low local regions.

4. The method according to claim 1 wherein applying the operative finishing motion comprises applying at least five times higher pressure to the unwanted raised regions when compared to the applied pressure in a lower region proximate to the unwanted raised regions.

5. The method according to claim 1 wherein the organic lubricating boundary layer interacts with and adheres to the uniform region of the semiconductor wafer surface by dipole-dipole interactions.

6. The method of finishing of the semiconductor wafer surface being finished having uniform regions and the plurality of wafer die, each wafer die having the repeating pattern of unwanted raised regions according to claim 1 wherein the unwanted raised regions have a finishing rate measured in angstroms per minute of at least 4 times faster than in a proximate low local region.

7. The method of finishing of the semiconductor wafer surface being finished having uniform regions and the plurality of wafer die, each wafer die having the repeating pattern of unwanted raised regions according to claim 1 wherein applying the operative finishing motion comprises:

applying a higher pressure to the unwanted raised regions compared to the pressure applied to regions below the unwanted raised regions causing less boundary layer lubrication and a higher temperature on the unwanted raised regions and the boundary layer lubrication to be greater and the temperature to be lower on a portion of the semiconductor wafer surface below the unwanted raised regions.

8. The method of finishing of the semiconductor wafer surface being finished having uniform regions and the plurality of wafer die, each wafer die having the repeating pattern of unwanted raised regions according to claim 7 wherein applying the higher pressure comprises applying at least five times higher pressure to the unwanted raised region when compared to the applied pressure in a lower region proximate to the unwanted raised regions.

9. The method of finishing of the semiconductor wafer surface being finished having uniform regions and the plurality of wafer die, each wafer die having the repeating pattern of unwanted raised regions according to claim 7 wherein applying the operative finishing motion causes the unwanted raised regions to have a temperature of at least 7 degrees centigrade higher than that of the proximate low local regions.

10. The method of finishing of the semiconductor wafer surface being finished having uniform regions and the plurality of wafer die, each wafer die having the repeating pattern of unwanted raised regions according to claim 7 wherein the unwanted raised regions have a finishing rate measured in angstroms per minute of at least 4 times faster than in a proximate low local region.

11. The method of finishing of the semiconductor wafer surface being finished having uniform regions and the plurality of wafer die, each wafer die having the repeating pattern of unwanted raised regions according to claim 7 wherein the finishing element finishing surface comprises an organic synthetic polymer having a flexural modulus of at least 20,000 psi when measured according to ASTM 790 B at 73 degrees Fahrenheit.

12. The method according to claim 1 wherein the organic boundary lubricating layer is capable of changing from a solid film to a different physical form in a temperature range in the interface between the semiconductor wafer surface being finished and the finishing element finishing surface.

13. A method of finishing of a semiconductor wafer surface being finished having uniform regions having a plurality of unwanted raised regions, the method comprising the steps of:

providing a finishing element finishing surface;

positioning the semiconductor wafer surface being finished proximate to the finishing surface;

supplying an organic boundary lubricant to an interface between the semiconductor wafer surface being finished and the finishing element finishing surface;

applying an operative finishing motion in the interface between the semiconductor wafer surface being finished and the finishing element finishing surface; and

wherein

applying the operative finishing motion forms an organic lubricating boundary layer having a thickness of at most 4 molecules on at least a portion of the semiconductor surface being finished and;

the operative finishing motion forms a friction in the interface between a uniform region of the semiconductor wafer surface and the finishing element finishing surface;

the organic boundary layer physically or chemically interacts with and adheres to a uniform region of the semiconductor wafer surface;

the friction formed between the uniform region of the semiconductor wafer surface and the finishing element finishing surface is determined by properties other than viscosity.

14. The method of finishing of the semiconductor wafer surface being finished having uniform regions having the plurality of unwanted raised regions according to claim 13 wherein the finishing element comprises a mixture of a plurality of organic synthetic polymers.

15. The method of finishing of the semiconductor wafer surface being finished having uniform regions having the plurality of unwanted raised regions according to claim 13 wherein applying the operative finishing motion comprises:

applying a higher pressure to the unwanted raised regions compared to the pressure applied to regions below the unwanted raised regions causing less boundary layer lubrication and a higher temperature on the unwanted raised regions and the boundary layer lubrication to be greater and the temperature to be lower on a portion of the semiconductor wafer surface below the unwanted raised regions.

16. The method of finishing of the semiconductor wafer surface being finished having uniform regions having the plurality of unwanted raised regions according to claim 15 wherein applying the higher pressure comprises applying at least five times higher pressure to the unwanted raised region when compared to the applied pressure in a lower region proximate to the unwanted raised regions.

17. The method of finishing of the semiconductor wafer surface being finished having uniform regions having the plurality of unwanted raised regions according to claim 15 wherein the unwanted raised regions have a finishing rate measured in angstroms per minute of at least 4 times faster than in a proximate low local region.

18. The method according to claim 15 wherein applying the operative finishing motion causes the unwanted raised regions to have a temperature of at least 7 degrees centigrade higher than that of the proximate low local regions.

19. The method of finishing of the semiconductor wafer surface being finished having uniform regions having the plurality of unwanted raised regions according to claim 15 wherein applying the higher pressure comprises applying at least five times higher pressure to the unwanted raised region when compared to the applied pressure in a lower region proximate to the unwanted raised regions.

20. The method according to claim 15 wherein applying the operative finishing motion causes the unwanted raised regions to have a temperature of from 7 to 45 degrees centigrade higher than that of the proximate low local regions.

21. A method of finishing of a semiconductor wafer surface being finished comprising the steps of:

providing a finishing element finishing surface;

providing an organic lubricant to an operative finishing interface;

applying an operative finishing motion in the operative finishing interface forming an organic lubricating boundary layer of from 1 to 6 molecules thick; and

controlling at least once the thickness of the organic lubricating boundary layer which changes the coefficient of friction in the operative finishing interface by changing at least one process control parameter in situ based on feed back information from a control subsystem during the finishing cycle time.

22. The method according to claim 21 further comprising an additional step of controlling the thickness of the organic lubricating boundary layer by changing at least one lubrication control parameter changes the tangential force of friction in at least two different regions in the operative finishing interface in response to an in situ control signal.

23. The method of finishing of the semiconductor wafer surface being finished according to claim 21 wherein the semiconductor wafer surface being finished has a plurality of unwanted raised regions and further comprising the additional step of applying a higher pressure to the plurality of unwanted raised regions with a finishing element having a flexural modulus of at least 20,000 psi when measured by ASTM 790 B at 73 degrees Fahrenheit as compared to the lower pressure applied to the lower regions proximate to the unwanted raised regions.

24. The method of finishing of the semiconductor wafer surface being finished according to claim 21 wherein the organic lubricating boundary layer is capable of changing from a solid film to a different physical form in the operative finishing interface temperature range.

25. The method of finishing of the semiconductor wafer surface being finished according to claim 21 wherein the control subsystem comprises a plurality of friction sensors.

26. The method of finishing of the semiconductor wafer surface being finished according to claim 21 wherein the control subsystem comprises a plurality of friction sensors and a workpiece sensor.

27. A method of finishing of a semiconductor wafer surface being finished comprising the steps of:

providing a finishing element finishing surface;

providing an organic lubricant to an operative finishing interface; and

applying an operative finishing motion in an operative finishing interface forming an organic lubricating boundary layer of from 1 to 4 molecules thick and wherein the organic lubricating boundary layer interacts with and adheres to the semiconductor wafer surface being finished.

28. The method of finishing of the semiconductor wafer surface being finished according to claim 27 wherein applying the operative finishing motion comprises forming the organic lubricating boundary layer in the operative finishing interface, reducing the wear on the finishing element finishing surface during finishing.

29. The method of finishing of the semiconductor wafer surface being finished according to claim 27, further comprising an additional step of controlling the thickness of the organic lubricating boundary layer by changing at least one control parameter in a manner that changes the tangential force of friction in at least one region of the semiconductor wafer surface in response to an in situ control signal.

30. The method of finishing of the semiconductor wafer surface being finished according to claim 27, wherein the semiconductor wafer surface being finished has a cut rate of from 100 to 25,000 Angstroms per minute on at least a portion of the semiconductor wafer surface being finished.

31. The method of finishing of the semiconductor wafer surface being finished according to claim 27, further comprising an additional step of changing the organic lubricating boundary layer a plurality of times during the finishing cycle time to change the coefficient of friction between the finishing element finishing surface and the semiconductor wafer surface being finished the plurality of times during the finishing cycle time.

32. The method of finishing of the semiconductor wafer surface being finished according to claim 27, wherein providing the organic lubricant comprises providing a plurality of organic lubricants.

33. The method of finishing of the semiconductor wafer surface being finished according to claim 27 wherein the organic lubricating boundary layer is capable of changing from a solid film to a liquid film in the temperature range from 20 to 100 degrees centigrade.

34. The method of finishing of the semiconductor wafer surface being finished according to claim 27 wherein the semiconductor wafer surface being finished comprises a conductive region and the organic lubricating boundary layer interacts with and adheres to the conductive region.

35. The method of finishing of the semiconductor wafer surface being finished according to claim 27 wherein the semiconductor wafer surface being finished comprises a nonconductive region and the organic lubricating boundary layer interacts with and adheres to the nonconductive region.

36. A method of finishing of a semiconductor wafer surface being finished comprising the steps of:

providing a finishing element finishing surface;

providing an organic lubricant to an operative finishing interface; and

applying an operative finishing motion in the operative finishing interface forming an organic lubricating boundary layer film that is capable of changing from a solid film to a different physical form in the operative finishing interface temperature range during a finishing cycle time and wherein the organic lubricating boundary layer interacts with and adheres to the semiconductor wafer surface being finished.

37. The method of finishing of the semiconductor wafer surface being finished according to claim 36, further comprising an additional step of changing the organic lubricating boundary layer film physical form by changing at least one lubrication control parameter in situ based on feed back information from a lubrication control subsystem having an energy change sensor.