System and method for lithography process monitoring and control

• US 6,828,542 B2
• Filed: 03/18/2003
• Issued: 12/07/2004
• Est. Priority Date: 06/07/2002
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: Brion Technologies Incorporated (ASML Holding NV)
• Inventors: Ye, Jun, Chen, Xun, Pease, R. Fabian W.
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US10/390,806
• Publication Number:
  US 20030226951A1
• Time in Patent Office: 630 Days
• Field of Search: 250/208.1, 250/548, 250/559.4, 250/559.45, 356/399, 356/400, 356/401, 355/53, 355/55, 430/5, 430/21
• US Class Current: 250/208.1
• CPC Class Codes: G03F 7/70591 Testing optical components
• CPC Class Codes: G03F 7/7065 Defects, e.g. optical inspection of patterned layer for defects
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load

Abstract

In one aspect, the present invention is a technique of, and a system and sensor for measuring, inspecting, characterizing and/or evaluating optical lithographic equipment, methods, and/or materials used therewith, for example, photomasks. In one embodiment of this aspect of the invention, the system, sensor and/or technique measures, collects and/or detects an aerial image produced or generated by the interaction between the photomask and lithographic equipment. An image sensor unit may measure, collect, sense and/or detect the aerial image in situ—that is, the aerial image at the wafer plane produced, in part, by a production-type photomask (i.e., a wafer having integrated circuits formed during the integrated circuit fabrication process) and/or by associated lithographic equipment used, or to be used, to manufacture of integrated circuits.

Claims

1. An image sensor unit, for use with a highly precise moveable platform, the image sensor unit comprising:

a substrate having a wafer-shaped profile;

a sensor array, disposed on the wafer-shaped substrate, the sensor array including;

a plurality of sensor cells wherein each sensor cell includes an active area to sense light of a predetermined wavelength that is incident thereon; and

a film, disposed over the active areas of the plurality of sensor cells and comprised of a material that impedes passage of light of the predetermined wavelength, wherein the film includes a plurality of apertures which are arranged such that an aperture of the plurality of apertures overlies an active area of a corresponding sensor cell to expose a portion of the active area and wherein light of the predetermined wavelength is capable of being sensed by the portion of the active area that is exposed by the corresponding aperture.

2. The image sensor unit of claim 1 further including a transparent medium, having a predetermined refractive index, disposed on the sensor array.

3. The image sensor unit of claim 1 further including communications circuitry disposed on the substrate, wherein the communications circuitry is coupled to the sensor array.

4. The image sensor unit of claim 1 further including at least one battery, disposed on or within a cavity in the wafer-shaped substrate, to provide electrical power to the sensor array.

5. The image sensor unit of claim 1 wherein the film is disposed between the active areas of the sensor cells and a protective outer layer of the sensor array.

6. The image sensor unit of claim 1 further including communications circuitry, disposed on the substrate, to provide data to external circuitry using wireless techniques.

7. The image sensor unit of claim 6 wherein the communications circuitry provides data using wireless techniques during collection of image data by the sensor array.

8. The image sensor unit of claim 6 further including at least one battery disposed on or within a cavity in the wafer-shaped substrate wherein the battery provides electrical power to the sensor array and the communications circuitry.

9. The image sensor unit of claim 1 wherein the image sensor unit further includes:

data storage circuitry, coupled to the sensor array, to receive and store the data from the sensor array;

data compression circuitry, coupled to the data storage circuitry, to compress the data;

communications circuitry, coupled to the data compression circuitry, to provide data to external circuitry; and

at least one rechargeable battery, to provide electrical power to the data storage circuitry, the data compression circuitry and the communications circuitry.

10. An image sensor unit, for use with a highly precise moveable platform, the image sensor unit comprising:

a wafer-shaped substrate;

a sensor array, integrated into the substrate, the sensor array including;

a plurality of sensor cells wherein each sensor cell includes an active area to sense light of a predetermined wavelength that is incident thereon; and

a film, disposed over the active areas of the plurality of sensor cells and comprised of a material that impedes passage of light of the predetermined wavelength, wherein the film includes a plurality of apertures which are arranged such that an aperture of the plurality of apertures overlies an active area of a corresponding sensor cell to expose a portion of the active area of the corresponding sensor cell and wherein light of the predetermined wavelength is capable of being sensed by the portion of the active area that is exposed by the corresponding aperture.

11. The image sensor unit of claim 10 further including communications circuitry, disposed on the substrate, to provide data to external circuitry using wireless techniques.

12. The image sensor unit of claim 10 further including at least one battery disposed on or within a cavity in the wafer-shaped substrate wherein the battery provides electrical power to the sensor array.

13. The image sensor unit of claim 10 wherein the film is disposed between the active areas of the sensor cells and a protective outer layer of the sensor array.

14. The image sensor unit of claim 10 wherein the image sensor unit further includes:

data compression circuitry, coupled to the sensor array, to compress the data received from the sensor array;

communications circuitry, coupled to the data compression circuitry, to provide the compressed data to external circuitry; and

at least one rechargeable battery, to provide electrical power to the sensor array and the data compression circuitry.

15. The image sensor unit of claim 10 wherein the image sensor unit further includes:

data storage circuitry, coupled to the sensor array, to receive and store data from the sensor array;

data compression circuitry, coupled to the data storage circuitry, to compress the data;

communications circuitry, coupled to the data compression circuitry, to provide the compressed data to external circuitry; and

at least one rechargeable battery, to provide electrical power to the data storage circuitry, the data compression circuitry and the communications circuitry.

16. The image sensor unit of claim 10 wherein the sensor cells are charge coupled devices, CMOS devices or photodiodes.

17. The image sensor unit of claim 10 further including photon-conversion material, disposed over the sensor array and between the film and the plurality of sensors.

18. The image sensor unit of claim 17 wherein the photon-conversion material is disposed within the plurality of apertures of the film.

19. The image sensor unit of claim 17 wherein the photon-conversion material is disposed on the sensor array.

20. A system to collect image data which is representative of an aerial image of a mask that is projected on a wafer plane, the system comprising:

an optical system to produce the image of the mask on the wafer plane;

a moveable platform;

an image sensor unit, disposed on the moveable platform, to collect data which is representative of the aerial image of the mask, the image sensor includes;

a wafer-shaped substrate;

a sensor array, disposed on or in the wafer-shaped substrate, wherein the sensor array is capable of being located in the wafer plane, the sensor array includes;

a plurality of sensor cells wherein each sensor cell includes an active area to sense light of a predetermined wavelength that is incident thereon; and

a film, disposed over the active areas of the plurality of sensor cells and comprised of a material that impedes passage of light of the predetermined wavelength, wherein the film includes a plurality of apertures which are arranged such that an aperture of the plurality of apertures overlies an active area of a corresponding sensor cell to expose a portion of the active area of the corresponding sensor cell and wherein light of the predetermined wavelength is capable of being sensed by the portion of the active area that is exposed by the corresponding aperture.

21. The system of claim 20 further including communications circuitry, disposed on the substrate, to image data which is representative of the light sensed by the sensor cells to a data processing unit using wireless techniques.

22. The system of claim 21 wherein the communications circuitry provides the data during collection of the data by the image sensor unit.

23. The system of claim 21 further including at least one battery disposed on or within a cavity in the wafer-shaped substrate wherein the battery provides electrical power to the sensor array and the communications circuitry.

24. The system of claim 20 wherein the mask is a product-type mask.

25. The system of claim 20 wherein the aerial image produced on the wafer plane is the same or substantially the same image produced on a product wafer.

26. The system of claim 20 further including:

a data processing unit configured to receive the data which is representative of the aerial image; and

wherein the moveable platform moves in first and second directions to a plurality of discrete locations relative to the aerial image wherein at each discrete location, the sensor cells sample the light incident on the exposed portion of the active area and wherein the processing unit uses the data to generate an aerial image.

27. The system of claim 26 wherein the distance between the plurality of discrete locations in the first direction is less than or equal to the width or diameter of the apertures.

28. The system of claim 26 wherein the distance between the plurality of discrete locations in the second direction is less than or equal to the width or diameter of the apertures.

29. The system of claim 26 wherein the processing unit interleaves the image data to generate the aerial image.

30. The system of claim 26 wherein the image sensor unit collects data which is representative of the aerial image in a raster-type manner.

31. The system of claim 26 wherein the image sensor unit collects image data which is representative of the aerial image in a vector-type manner.

32. An image sensor unit which is capable of collecting image data which is representative of an aerial image of a mask that is projected on a wafer plane by a lithographic unit, the image sensor unit comprising:

a sensor array, disposed on or in the moveable platform of the lithographic unit, wherein the sensor array is capable of being located in the wafer plane, the sensor array includes;

a plurality of sensor cells wherein each sensor cell includes an active area to sense fight of a predetermined wavelength that is incident thereon; and

a film, disposed over the active areas of the plurality of sensor cells and comprised of a material that impedes passage of light of the predetermined wavelength, wherein the film includes a plurality of apertures which are arranged such that an aperture of the plurality of apertures overlies an active area of a corresponding sensor cell to expose a portion of the active area of the corresponding sensor cell and wherein light of the predetermined wavelength is capable of being sensed by the portion of the active area that is exposed by the corresponding aperture.

33. The image sensor unit of claim 32 wherein the mask is a product-type mask.

34. The image sensor unit of claim 33 wherein the aerial image produced on the wafer plane is the same or substantially the same image produced on a product wafer.

35. The image sensor unit of claim 32 wherein the sensor cells are charge coupled devices, CMOS devices or photodiodes.

36. The image sensor unit of claim 32 wherein the sensor array is capable of moving between a plurality of discrete locations, relative to the aerial image, in first and second directions while disposed on the moveable platform, and wherein the sensor cells sample the light incident on the exposed portion of the active area at each discrete location.

37. The image sensor unit of claim 32 wherein the distance between the plurality of discrete locations in the first direction is less than or equal to the width or diameter of the apertures.

38. The image sensor unit of claim 32 wherein the distance between the plurality of discrete locations in the second direction is less than or equal to the width or diameter of the apertures.

39. The image sensor unit of claim 32 wherein the image sensor unit collects data which is representative of the aerial image in a raster-type manner.

40. The image sensor unit of claim 32 wherein the image sensor unit collects image data which is representative of the aerial image in a vector-type manner.