In situ technique for monitoring and controlling a process of chemical-mechanical-polishing via a radiative communication link

• US 6,010,538 A
• Filed: 01/11/1996
• Issued: 01/04/2000
• Est. Priority Date: 01/11/1996
• Status: Expired due to Term

• Current Assignee: LumaSense Technologies Holdings, Inc. (Advanced Energy Industries, Inc. (China))
• Original Assignee: Luxtron Corp. (Advanced Energy Industries, Inc. (China))
• Inventors: Jensen, Earl M., Glenn, Daniel E., Hausman, Frank J., Zhou, Lin Jun, Sun, Mei H., Litvak, Herbert E., Tzeng, Huey M.
• Primary Examiner(s): CODD, BERNARD P
• Application Number:
  US08/585,164
• Time in Patent Office: 1,454 Days
• Field of Search: 156/345 LC, 156/345 L, 156/345 LP, 156/626.1, 356/357, 451/6, 451/41, 451/287, 451/288, 216/84, 216/88, 216/91, 438/8, 438/14, 438/692
• US Class Current: 156/345.13
• 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: B24B 49/12 involving optical means
• CPC Class Codes: G05B 19/4065 Monitoring tool breakage, life or condition

Abstract

In an apparatus for removing material from an article, such as an exposed surface of an intermediate integrated circuit structure, by planarizing, polishing, etching or the like, a sensor is mechanically coupled to a moving carrier of the article for directing through the article to its first side an electromagnetic radiation beam having a wavelength band to which the structure is substantially transparent. The beam is detected after interacting with the article, such as being reflected from its exposed surface, and resulting information of the state of the processing of the exposed surface is transmitted from the moving carrier to a stationary receiver by radiation without the use of any physical transmission media such as wires or optical fibers. Multiple sensors mounted on the moving article carrier provide information of the uniformity of the processing across the exposed article surface. The radiation signal received by the stationary receiver is used to monitor or control the processing, such as by determining an endpoint thereof.

Claims

1. In an apparatus for processing an article by chemical-mechanical-polishing wherein the article is contacted by a moving element, a system for monitoring said processing, comprising:

means including a detector carried by said moving element for receiving a first radiation signal from said article and generate a local signal providing information of the state of the processing of the article by chemical-mechanical-polishing,

means carried by said moving element for generating from said local signal a second radiation signal that is transmitted without use of physical transmission media connected thereto, said second radiation signal containing the information of the state of the processing of the article by chemical-mechanical-polishing, and

means separated from the moving element for receiving said second radiation signal in order to determine the state of the processing of the article by chemical-mechanical-polishing.

2. The monitoring system of claim 1 wherein the moving element is adapted to hold a substrate carrying a partially formed integrated circuit structure.

3. The monitoring system of claim 1, additionally comprising means for directing against said article a beam of optical radiation that forms the radiation signal received from the article by the detector, and wherein said radiation signal transmitting means includes means for directing optical radiation toward the receiving means.

4. The monitoring system of claim 3 wherein the radiation beam directing means includes means for reflecting, from a surface layer being processed on the article, the optical radiation.

5. The monitoring system of claim 1 wherein said receiving means includes means for determining an endpoint of the processing from said radiation signal.

6. The monitoring system of claim 1 wherein said radiation signal receiving means is arranged so as not to move with either the article or the moving element.

7. In an apparatus for processing a front side of an article, wherein the apparatus includes a moving carrier that holds a backside of the article across a given surface, a system for monitoring the processing, comprising:

means mounted to said carrier and moving therewith for directing interrogating radiation to said surface and receiving a portion of said radiation by reflection when an article is held thereat, said radiation containing information of the state of the processing of the front side of the article,

means mounted to said carrier and receiving said article reflected radiation for generating a wireless radiation signal therefrom and transmitting the wireless radiation signal without use of physical transmission media connected to the carrier, said wireless radiation signal carrying said information from the reflected radiation of the state of the processing of the front side of the article, and

means positioned off of said carrier and receiving said wireless radiation signal for determining the state of the processing of the front side of the article.

8. The monitoring system of claim 7 which comprises an article held by the carrier with its backside across said surface, and wherein the interrogating radiation of said radiation directing and receiving means passes through the article to a front side thereof in a manner to obtain radiation reflected from the article front side that contains information of the state of the processing of the article front side.

9. The monitoring system of claim 8 wherein said article is a semiconductor wafer.

10. The monitoring system of claim 9 wherein the apparatus is characterized by processing a surface of the wafer by chemical-mechanical-polishing.

11. The monitoring system of claim 9 wherein said article is a flat panel display.

12. The monitoring system of claim 11 wherein the apparatus is characterized by processing a surface of the flat panel display by chemical-mechanical-polishing.

13. The monitoring system of claim 7 wherein the radiation directing means includes means for directing a beam of optical radiation to said surface, and the wireless signal transmitting means includes means for directing another beam of optical radiation toward the state determining means.

14. The monitoring system of claim 7 wherein said state determining means includes means for determining an endpoint of the processing from said wireless radiation signal.

15. The monitoring system of claim 7 wherein said interrogating radiation directing and receiving means includes means for directing two or more beams of interrogating radiation against two or more spaced apart regions of the surface and independently receiving a portion of said radiation from said spaced apart regions by reflection, whereby the processing is independently monitored at said spaced apart regions.

16. The monitoring system of claim 7 wherein said interrogating radiation directing and receiving means includes:

a source of said interrogating radiation and a photodetector mounted to the carrier in a position removed from a surface against which said article is held,

an opening extending into the carrier from its said surface against which the article is held,

a first optical fiber extending from the radiation source and through the carrier opening in a manner to illuminate the backside of the article from an end of the first optical fiber, and

a second optical fiber extending from the photodetector and through the carrier opening in a manner to receive radiation reflected from the article through an end of the second optical fiber.

17. The monitoring system of claim 16 wherein said interrogating radiation directing and receiving means additionally includes a removable sealing device fit into the carrier opening against said one end of the first and second optical fibers.

18. The monitoring system of claim 7 wherein the state determining means includes means for determining a breakthrough in an opaque reflective layer being removed from the article by the processing in advance of the breakthrough occurring.

19. The monitoring system of claim 18 wherein the state determining means additionally includes means for calculating a rate of change of the radiation reflected from the opaque reflective layer and for identifying a characteristic of the derivative that is representative of the reflected radiation changing in intensity level.

20. The monitoring system of claim 18 wherein the state determining means additionally includes means for calculating a mathematical logarithm of the radiation reflected from the opaque reflective layer and for identifying a characteristic of the logarithm that is representative of the reflected radiation changing in intensity level.

21. The monitoring system of claim 18 wherein the state determining means additionally includes means for detecting a drop in the magnitude of the reflected radiation in excess of a predetermined amount.

22. The monitoring system of claim 18 wherein the state determining means additionally includes means for determining an extent of uniformity of the removal of material across the front side of the article.

23. The monitoring system of claim 18 which additionally comprises means responsive to the advance determination of the breakthrough for controlling operation of the processing apparatus.

24. The monitoring system of claim 7 wherein the state determining means includes means for monitoring a signal resulting from an interference between interrogating radiation reflected from the front side of the article being processed and a surface within the article that is not being processed.

25. The monitoring system of claim 24 wherein the signal monitoring means includes means for fitting a curve to the interference signal.

26. The monitoring system of claim 25 wherein the signal monitoring means additionally includes means for repetitively calculating a rate at which material has been removed from the front side of the article.

27. The monitoring system of claim 26 wherein the signal monitoring means additionally includes means for repetitively calculating an amount of material that has been removed from the front side of the article.

28. The monitoring system of claim 24 wherein the signal monitoring means additionally includes means for determining an extent of uniformity of the removal of material across the front side of the article.

29. The monitoring system of claim 24 wherein the signal monitoring means includes means for repetitively calculating the state of the processing of the article and using the results of the calculations to control operation of the processing apparatus.

30. The monitoring system of claim 7 wherein the state determining means includes means for determining a breakthrough in a transparent layer being removed from the article by the processing in advance of the breakthrough occurring.

31. The monitoring system of claim 7 wherein the wireless signal transmitting means includes means for directing a radio frequency signal toward the state determining means.

32. The monitoring system of any one of claims 7-15, wherein the processing apparatus is characterized by processing a front side of an article by removing material therefrom, and the means for determining the state of the processing includes means for determining the state of material removal from the front side of the article.

33. In an apparatus for chemical-mechanical-polishing a film on a substrate contacted by a moving element, a system for monitoring a thickness of the film during the chemical-mechanical-polishing, comprising:

at least one sensor attached to the moving element and which provides at least one local signal with information of the film thickness during the chemical-mechanical-polishing of the film,

a controller positioned outside of the processing chamber to detect the film thickness information of said at least one local signal, and

a communication link of said information between the sensor and controller including a radiation signal formed from said at least one local signal and having a portion of the communication link without any physical transmission media carrying the radiation signal containing the information of the film thickness being monitored.

34. The apparatus of claim 33, wherein the moving element is adapted to hold a backside of a semiconductor wafer with the film being processed on an exposed front side of the wafer.

35. The apparatus of claim 34, wherein the sensor optically communicates through the backside of the wafer held by the moving element to obtain the film thickness information.

36. The apparatus of claim 33, wherein the moving element is adapted to hold a backside of a flat panel display with the film being processed on an exposed front side of the flat panel display.

37. The apparatus of claim 36, wherein the sensor optically communicates through the backside of the flat panel display held by the moving element to obtain the film thickness information.

38. The apparatus of claim 33, wherein said at least one sensor includes two or more sensors positioned at spaced apart locations across the moving element to provide respective two or more local signals with information of the film thickness being monitored at said locations, and the controller detects these film thicknesses from said information.

39. The apparatus of claim 33, additionally comprising means responsive to the detected film thickness information of the controller for controlling operation of the chemical-mechanical-polishing apparatus.

40. The apparatus of claim 33, wherein the communication link portion without any physical transmission media carrying the signal includes a transmitter of optical radiation.

41. A system for monitoring chemical-mechanical-processing of a front side of an article in an apparatus that includes a carrier with a given surface to hold a backside of the article thereagainst and a motor source that moves the carrier given surface with respect to an abrasive media with which the front side of an article is placed in contact when the article is held by the given surface, said system comprising:

a source of radiation mounted to said carrier that directs interrogating radiation through said carrier to said given surface and through an article held thereby,

a detector mounted to said carrier to receive a portion of said radiation reflected from an area of the front side of an article held by said given surface, thereby to obtain information of the state of chemical-mechanical-processing taking place on the article front side,

a transmitter that is mounted to said carrier and receives a signal from the detector to generate a wireless radiation signal therefrom that carries said information, and

a receiver separated from said carrier and receiving said wireless radiation signal without use of any physical transmission media therebetween that determines the state of the chemical-mechanical-processing of the front side of the article.

42. The monitoring system of claim 41, wherein the radiation source includes a first optical fiber extending through the carrier, and the detector includes a second optical fiber extending through the carrier.

43. A system for monitoring chemical-mechanical-processing of an article in an apparatus that includes a carrier with a given surface to hold a backside of the article thereagainst and a motor source that moves the carrier given surface with respect to an abrasive media with which the article is placed in contact when the article is held by the given surface, said system comprising:

a source of radiation mounted to said carrier that directs interrogating radiation through said carrier to said given surface and onto an article held thereby in at least first and second areas thereof,

first detector mounted to said carrier to receive a portion of said radiation reflected from the first area of the article held by said given surface, thereby to obtain information of the state of chemical-mechanical-processing taking place in the first area of the article,

a second detector mounted to said carrier to receive a portion of said radiation reflected from the second area of the article held by said given surface, thereby to obtain information of the state of chemical-mechanical-processing taking place in the second area of the article,

a transmitter that is mounted to said carrier and receives signals from the first and second detectors to generate a wireless radiation signal therefrom that carries the information of the states of chemical-mechanical-processing taking place in the first and second areas of the article, and

a receiver separated from said carrier and receiving said wireless radiation signal without use of any physical transmission media therebetween that determines the state of the chemical-mechanical-processing of the first and second areas of the article.

44. The monitoring system of claim 43, wherein the radiation source includes a first optical fiber extending through the carrier to the first area and a second optical fiber extending through the carrier to the second area, and the first detector includes a third optical fiber extending through the carrier to the first area, and the second detector includes a fourth optical fiber extending through the carrier to the second area.