WAFER EDGE CHARACTERIZATION BY SUCCESSIVE RADIUS MEASUREMENTS

• US 20090149115A1
• Filed: 09/03/2008
• Published: 06/11/2009
• Est. Priority Date: 09/24/2007
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Palou-Rivera, Ignacio, Karuppiah, Lakshmanan, Swedek, Boguslaw A.
• Granted Patent: US 8,337,278 B2
• Time in Patent Office: Days
• US Class Current: 451/5
• CPC Class Codes: B24B 37/042 operating processes therefor
• CPC Class Codes: B24B 49/02 according to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent B24B49/12 takes precedence
• CPC Class Codes: B24B 49/12 involving optical means

Abstract

Systems and methods for performing one or more measurements of a substrate at one or more radii along the substrate are described. Thickness measurements taken at various radii along the substrate can be averaged together to obtain an average value that reflects an overall substrate thickness. A more accurate measurement of the overall substrate thickness can be obtained by performing multiple measurements and averaging the measurements together. Using the average value, polishing can be adjusted to ensure that the substrate achieves a desired planarized thickness profile.

Claims

1. A system, comprising:

a polishing apparatus having one or more polishing stations for polishing of a substrate, the polishing stations operating with a plurality of polishing parameters;

an in-line monitoring system including

a substrate holder to hold the substrate at a location away from the polishing stations, and

a sensor to generate a signal based on a thickness of a layer of the substrate,

wherein the sensor and the substrate holder are configured to undergo relative motion to position the sensor at three or more angularly separated positions adjacent the substrate edge and generate measurements at the three or more angularly separated positions; and

a controller to receive the signal from the sensor and control at least one of the plurality of polishing parameters in response to the signal.

2. The system of claim 1, wherein the sensor and the substrate holder are configured to undergo relative motion to scan the sensor along three or more angularly separated radial segments of the substrate.

3. The system of claim 1, wherein the sensor and the substrate holder are configured to undergo relative motion to scan the sensor along between six and twenty angularly separated radial segments of the substrate.

4. The system of claim 1, wherein the sensor comprises an eddy current sensor.

5. The system of claim 1, wherein the sensor is stationary and the substrate holder is movable.

6. The system of claim 5, wherein the substrate holder comprises a robot.

7. The system of claim 1, further comprising a substrate support to hold the substrate at a location away from the polishing stations and the sensor.

8. The system of claim 7, wherein the substrate holder is operable to transfer the substrate from the substrate support to the sensor.

9. The system of claim 1, wherein the monitoring system includes a substrate edge detector.

10. The system of claim 9, wherein the monitoring system is configured to detect a first edge of the substrate and a second edge of the substrate as the substrate holder scans the sensor across the substrate.

11. The system of claim 15, wherein the substrate holder is configured to remove the substrate from the opening upon detection of the second substrate edge.

12. The system of claim 10, wherein the substrate holder is configured to rotate the substrate by an angle α

upon detection of the second substrate edge.

13. The system of claim 12, wherein the angle α

equals 360/N, where N is an integer greater than 2.

14. The system of claim 1, wherein the substrate holder is located in the polishing apparatus.

15. The system of claim 1, wherein the monitoring system includes an opening for receiving the substrate, wherein the sensor is positioned near the opening.

16. The system of claim 15, wherein the monitoring system includes a vertical position sensor to determine a vertical position of the substrate;

and

wherein the substrate holder is configured to adjust the vertical position based on a signal from the vertical position sensor to prevent the substrate from contacting the sensor.

17. The system of claim 16, wherein the monitoring system includes a horizontal position sensor to track a lateral location of the substrate.

18. The system of claim 17, wherein the substrate holder is configured to adjust the horizontal position based on a signal from the horizontal position sensor to prevent the substrate from contacting an inner wall of the opening.

19. The system of claim 17, wherein the monitoring system includes a plurality of horizontal position sensors spaced at fixed predetermined locations within the opening to track the lateral location of the substrate.

30. The system of claim 2, wherein the three or more angularly separated radial segments are evenly angularly spaced apart.

31. The system of claim 2, wherein the sensor is configured to generate measurements at a plurality of positions along each of the three or more angularly separated radial segments.

32. The system of claim 31, wherein the controller is configured to average the measurements for each of the radial segments to generate an averaged measurement for each of the radial segments and to control the polishing parameter based on the averaged measurement.

33. The system of claim 1, wherein the controller is configured to average measurements from each of a plurality of radial zones to generate an averaged measurement for each radial zone.

20. A chemical mechanical polishing system, comprising:

a polishing apparatus having one or more polishing stations for polishing of a substrate, the polishing stations operating with a plurality of polishing parameters;

a probe for receiving the substrate and scanning the substrate at one or more locations, the probe including;

an eddy current sensor to induce an eddy current at each location and generate a signal indicative of a film thickness for a corresponding location;

a vertical position sensor to determine a vertical distance between the vertical position sensor to the substrate to ensure that the substrate does not contact the eddy current sensor; and

a horizontal position sensor to track a lateral location of the substrate with respect to the probe, and

a controller to receive the signal and control at least one of the plurality of polishing parameters in response to the signal.

21. The system of claim 20, wherein each location is spaced apart by an angle α

, the system further comprising;

a robot operable to rotate the substrate by the angle α

22. The system of claim 20, wherein the horizontal position sensor detects a first substrate edge and a second substrate edge of the substrate, the second substrate edge being farther away from the probe than the first substrate edge, the system further comprising:

a robot operable to rotate the substrate from a first location to a second location upon detection of the second substrate edge.

23. A method comprising:

scanning a sensor across a substrate in an in-line monitoring system to position the sensor at three or more angularly separated discrete points adjacent an edge of the substrate;

generating a measurement signal associated with a thickness of the substrate at each of the three or more angularly separated discrete points; and

controlling a polishing parameter of a polishing apparatus based on the measurement signal.

24. The method of claim 34, further comprising:

detecting a first substrate edge and a second substrate edge of the substrate, the second substrate edge being farther away from the probe than the first substrate edge.

25. The method of claim 24, further comprising rotating the substrate from a first radial segment to a second radial segment after detecting the second substrate edge.

26. The method of claim 25, wherein rotating the substrate from the first radial segment to the second radial segment performed without removing the substrate from an opening of the sensor.

27. The method of claim 25, wherein rotating the substrate includes removing the substrate from an opening of the sensor, rotating the substrate after removing the substrate, and returning the substrate to the opening.

28. The method of claim 34, further comprising:

generating measurement signals associated with thicknesses of the substrate at a plurality of discrete points on each of the three or more angularly separated radial segments;

averaging the measurement signals generated for each of the radial segments to produce an averaged signal for each of the radial segments; and

controlling the polishing parameter based on the averaged signal.

29. The method of claim 25, wherein rotating the substrate includes rotating the substrate by an angle of 360/N degrees, where N is an integer greater than 2.

34. The method of claim 23, wherein scanning the substrate includes moving the sensor along three or more angularly separated radial segments of the substrate, and generating a measurement signal includes measuring the substrate at one or more positions on each of the three or more angularly separated radial segments.

35. The method of claim 34, wherein scanning the substrate includes moving the sensor along between six and twenty angularly separated radial segments of the substrate.

36. The method of claim 34, wherein the radial segments are evenly angularly spaced around the substrate.

37. The method of claim 23, further comprising averaging measurements from each of a plurality of radial zones to generate an averaged measurement for each radial zone.