Apparatus for optical inspection of wafers during polishing

• US 20020051135A1
• Filed: 07/05/2001
• Published: 05/02/2002
• Est. Priority Date: 05/23/1995
• Status: Active Grant

• Current Assignee: Nova Measuring Instruments Limited (Honeywell International Inc.)
• Original Assignee: Nova Measuring Instruments Limited (Honeywell International Inc.)
• Inventors: Finarov, Moshe
• Granted Patent: US 6,752,689 B2
• Time in Patent Office: Days
• US Class Current: 356/630
• CPC Class Codes: B24B 37/005 Control means for lapping machines or devices
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 49/12 involving optical means
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/6838 with gripping and holding devices using a vacuum; Bernoulli devices
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 22/20 Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps

Abstract

An optical system is disclosed for the inspection of wafers during polishing which also includes a measurement system for measuring the thickness of the wafers top layer. The optical system views the wafer through a window and includes a gripping system, which places the wafer in a predetermined viewing location while maintaining the patterned surface completely under water. The optical system also includes a pull-down unit for pulling the measurement system slightly below the horizontal prior to the measurement and returns the measuring system to the horizontal afterwards.

Claims

1. An optical measurement station for use with a processing machine for processing a semiconductor wafer, the measurement station comprising an optical measuring unit;

and a holding unit for receiving the wafer after being processed and holding the processed wafer in a measuring position during measurements, wherein a configuration of said measurement station is such that it is installable within the processing machine.

2. The measurement station according to claim 1, wherein the measurements are applied to the wafer while in an exit station of said processing machine.

3. The measurement station according to claim 1, wherein said measuring unit comprises a spectrophotometer-based optical system.

4. The measurement station according to claim 1, wherein said measuring unit is operable to measure a thickness of at least a top layer of the wafer.

5. The measurement station according to claim 1, wherein said measuring unit is operable to carry out optical inspection of the process wafer

6. The measurement station according to claim 3, wherein said measuring unit further comprises an optical imaging system operable to locate measurements by performing pattern recognition.

7. The measurement station according to claim 6, wherein said imaging system comprises a charge coupled device.

8. The measurement station according to claim 1, wherein the measuring unit comprises an optical system including focusing optics for focusing illuminating light onto the wafer and collecting light reflected from the illuminated wafer, and a beam splitter.

9. The measurement station according to claim 6, wherein the optical system comprises a focusing optics for focusing illuminating light onto the wafer and collecting light reflected from the illuminated wafer;

a beam splitter; and

a pin hole mirror.

10. The measurement station according to claim 1, and also comprising a support assembly for supporting the processed wafer to be received by the holding unit.

11. The measurement station according to claim 1, wherein the measuring and holding unit are separated by a window through which at least a part of the wafer being held is viewable to enable optical measurements.

12. The measurement station according to claim 1, wherein said holding unit comprises an assembly movable along an axis perpendicular to the wafer'"'"'s surface, thereby enabling said holding of the wafer in the measuring position.

13. The measurement station according to claim 1, wherein said optical measuring unit has at least one dimension in a plane by which it is applied to the wafer smaller than that of the wafer'"'"'s surface.

14. The measurement station according to claim 1, having at least one dimension in a plane by which it is applied to the wafer about that of the wafer'"'"'s surface.

17. The processing machine according to claim 16, further comprising an exit station for receiving the processed wafer, said optical measurement station being located within said exit station.

18. The processing machine according to claim 16, wherein said processing tool is a polisher.

19. The processing machine according to claim 16, and also comprising a robot for supplying the processed wafer to the measurement station.

20. The processing machine according to claim 16, wherein said measuring unit comprises a spectrophotometer-based optical system.

21. The processing machine according to claim 16, wherein said measuring unit is operable to measure a thickness of at least a top layer of the wafer.

22. The processing machine according to claim 20, wherein said measuring unit further comprises an optical imaging system operable to locate measurements by performing pattern recognition.

23. The processing machine according to claim 16, wherein the measuring unit comprises an optical system including focusing optics for focusing illuminating light onto the wafer and collecting light reflected from the illuminated wafer;

and a beam splitter.

24. The processing machine according to claim 22, wherein the optical system comprises a focusing optics for focusing illuminating light onto the wafer and collecting light reflected from the illuminated wafer;

a beam splitter; and

a pin hole mirror.

25. The processing machine according to claim 22, wherein said imaging system comprises a charge coupled device.

26. The processing machine according to claim 16, and also comprising a support assembly for supporting the processed wafer to be received by the holding unit.

27. The processing machine according to claim 16, wherein the measuring and holding unit are separated by a window through which at least a part of the wafer being held is viewable to enable optical measurements.

28. The processing machine according to claim 16, wherein said holding unit comprises an assembly movable along an axis perpendicular to the wafer'"'"'s surface, thereby enabling said holding of the wafer in the measuring position.

29. The processing machine according to claim 16, wherein said optical measuring unit has at least one dimension in a plane by which it is applied to the wafer smaller than that of the wafer'"'"'s surface.

30. The processing machine according to claim 16, wherein said measurement station has at least one dimension in a plane by which it is applied to the wafer about that of the wafer'"'"'s surface.

15. An optical measurement station for use with a processing machine for processing a semiconductor wafer, the measurement station comprising an optical measuring unit;

and a holding unit for receiving the wafer after being processed and holding the processed wafer in a measuring position during measurements, wherein said measurement station at least one dimension in a plane by which it is to be applied to the wafer about of the wafer'"'"'s surface, the measurement being installable within the processing machine.

16. A processing machine for processing a semiconductor wafer, the processing machine comprising a processing tool to be applied to the wafer, and an optical measurement station, the optical measurement station comprising an optical measuring unit;

and a holding unit for receiving the wafer after being processed and holding the processed wafer in a measuring position during measurements.

31. A processing machine for processing a semiconductor wafer, the processing machine comprising a processing tool to be applied to the wafer, and an optical inspection station, the optical inspection station comprising an optical system;

and a holding unit for receiving the wafer after being processed and holding the processed wafer in an inspection position.

32. A method for processing a semiconductor wafer by a processing machine, the method comprising the steps of:

applying a processing tool of said processing machine to the wafer, thereby performing said processing;

supplying the processed wafer to an exit station of said processing machine; and

applying optical measurements to the processed wafer while in the exit station

33. A method for processing a semiconductor wafer by a processing machine, the method comprising the steps of:

applying a processing tool of said processing machine to the wafer, thereby performing said processing;

supplying the processed wafer to an exit station of said processing machine; and

applying optical inspection to the processed wafer while in the exit station.