System and method for lithography process monitoring and control

• US 6,969,837 B2
• Filed: 06/09/2004
• Issued: 11/29/2005
• 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:
  US10/863,915
• Publication Number:
  US 20040222354A1
• Time in Patent Office: 538 Days
• Field of Search: 250/208.1, 250/548, 250/559.4, 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

A system and sensor for measuring, inspecting, characterizing, evaluating and/or controlling optical lithographic equipment and/or materials used therewith, for example, photomasks. In one embodiment, the system and sensor measures, collects and/or detects an aerial image (or portion thereof) 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 therein/thereon) and/or by associated lithographic equipment used, or to be used, to manufacture of integrated circuits. A processing unit, coupled to the image sensor unit, may generate image data which is representative of the aerial image by interleaving the intensity of light sampled by each sensor cell at the plurality of location of the platform.

Claims

1. A system to collect image data which is representative of an aerial image of a mask used in the manufacture of integrated circuits, wherein the image of the mask is produced by an optical system having a platform moveable between a plurality of locations in a first direction and a plurality of locations in a second direction, the system comprising:

an image sensor unit disposed on or within the moveable platform, the image sensor unit includes;

a sensor array, located in a wafer plane of the optical system, including a plurality of sensor cells wherein each sensor cell includes an active area to sample the intensity of light of a predetermined wavelength that is incident thereon; and

a film, disposed over selected portions of the active areas of the plurality of sensor cells, to increase the spatial resolution of each sensor cell wherein the film is comprised of a material that impedes passage of light of the predetermined wavelength; and

a processing unit, coupled to the image sensor unit, to generate image data which is representative of the aerial image, wherein the processing unit generates the aerial image of the mask by interleaving the intensity of light sampled by each sensor cell at the plurality of location of the platform.

2. The system of claim 1 wherein the image sensor unit further includes a substrate having a wafer-shaped profile, wherein the sensor array is disposed on or in the substrate.

3. The system of claim 1 wherein the processing unit generates a first data set using the intensity of light sampled by each sensor cell when the platform is positioned at a first location relative to the aerial image.

4. The system of claim 3 wherein the processing unit generates a second data set using the intensity of light sampled by each sensor cell when the platform is positioned at a second location relative to the aerial image.

5. The system of claim 4 wherein the first location and the second location are adjacent locations along an axis in the first direction and wherein the distance between the first location and the second location is less than the distance between the two opposing edges of each exposed active area of each sensor cell of the sensor array, wherein the opposing edges are transverse to the axis.

6. The system of claim 4 wherein the first location and the second location are adjacent locations along an axis in the first direction and wherein the distance between the first location and the second location is less than the diameter of the exposed active area of each sensor cell.

7. The image sensor unit of claim 1 further including:

a substrate having a wafer-shaped profile, wherein the sensor array is disposed on or in the substrate; and

at least one battery, disposed on, in, or within a cavity in the substrate, to provide electrical power to the sensor array.

8. The image sensor unit of claim 7 further including communications circuitry, disposed on the substrate, to provide data to external circuitry using wireless communication.

9. The image sensor unit of claim 8 wherein the communications circuitry provides data using wireless communication during collection of data by the image sensor unit.

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

a data storage device, coupled to the sensor array, to receive and store data which is representative of the intensity of light sampled by the sensor cells; and

at least one rechargeable battery to provide electrical power to the data storage device and the sensor array.

11. The system 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 and includes a plurality of apertures which are arranged such that one aperture of the plurality of apertures overlies a corresponding 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.

12. The system of claim 11 wherein the distance between adjacent locations along an axis in the first direction is less than the distance between the two opposing sides of each aperture of the plurality of apertures, wherein the opposing sides are transverse to the axis.

13. The system of claim 11 wherein the distance between adjacent locations along an axis in a first direction is less than the diameters of the apertures in the film.

14. A system to collect image data which is representative of an aerial image of a mask used in the manufacture of integrated circuits, wherein the image of the mask is produced by an optical system having a platform moveable between a plurality of locations, the system comprising:

an image sensor unit disposed on or within the moveable platform, the image sensor unit includes;

a sensor array located in a wafer plane of the optical system, wherein the sensor array includes a plurality of sensor cells wherein each sensor cell includes an active area to sample the intensity of light of a predetermined wavelength that is incident thereon; and

a film, disposed over selected portions of the active areas of the plurality of sensor cells to enhance the spatial resolution of each sensor cell wherein the film is comprised of a material that impedes passage of light of the predetermined wavelength; and

a processing unit, coupled to the image sensor unit, to generate image data which is representative of a portion of the aerial image of the mask wherein the portion of the aerial image includes a plurality of non-contiguous sub-images, and wherein the processing unit generates each sub-image using the intensity of light sampled by one or more sensor cells when the platform is positioned at a plurality of locations relative to the aerial image.

15. The system of claim 14 wherein the film is disposed between the active areas of the sensor cells and a protective outer layer of the sensor array and includes a plurality of apertures which are arranged such that one aperture of the plurality of apertures overlies a corresponding 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.

16. The system of claim 15 wherein the processing unit generates each sub-image using the intensity of light sampled by a given sensor cell at a plurality of adjacent locations along a first axis.

17. The system of claim 16 wherein the image sensor unit further includes a wafer-shaped substrate, wherein the sensor array is integrated in, or disposed on the substrate.

18. The system of claim 17 wherein the distance between adjacent locations of the plurality of locations along the first axis is less than the distance between the two opposing sides of a plurality of the plurality of apertures in the film, wherein the opposing sides are transverse to the first axis.

19. The system of claim 17 wherein the distance between adjacent locations of the plurality of locations along the first axis is less than the diameters of the apertures of the plurality of apertures in the film.

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

data storage circuitry, coupled to the sensor array, to receive and store data which is representative of the intensity of light sampled by each sensor cell; and

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

21. A system to collect image data which is representative of an aerial image of a mask used in the manufacture of integrated circuits, wherein the image of the mask is produced by an optical system having a platform moveable between a plurality of locations, the system comprising:

an image sensor unit disposed on or within the moveable platform, the image sensor unit includes;

a sensor array, wherein the sensor array includes a plurality of sensor cells wherein each sensor cell includes an active area to sample the intensity of 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 one aperture of the plurality of apertures overlies an associated 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 associated aperture; and

a processing unit, coupled to the image sensor unit, to generate image data which is representative of at least a portion of the aerial image of the mask, wherein the processing unit generates the portion of the aerial image of the mask by interleaving the intensity of light sampled by the sensor cells at the plurality of locations of the platform.

22. The system of claim 21 wherein the processing unit generates:

a first data set using the intensity of light sampled by the sensor cells when the platform is positioned at a first location relative to the aerial image; and

a second data set using the intensity of light sampled by the sensor cells when the platform is positioned at a second location relative to the aerial image, wherein the first location and the second location are locations on a first axis.

23. The system of claim 22 wherein the first location and the second location are adjacent locations along the first axis and wherein the distance between the first location and the second location is less than the distance between the two opposing sides of each aperture of the plurality of apertures in the film, wherein the opposing sides are transverse to the first axis.

24. The system of claim 22 wherein the first location and the second location are adjacent locations along the first axis and wherein the distance between the first location and the second location is less than the diameters of apertures of the plurality of apertures in the film.

25. The system of claim 22 wherein the processing unit generates:

a third data set using the intensity of light sampled by sensor cells when the platform is positioned at a third location relative to the aerial image; and

a fourth data set using the intensity of light sampled by sensor cells when the platform is positioned at a fourth location relative to the aerial image.

26. The system of claim 25 wherein the second location and the third location are adjacent locations along a second axis and wherein the distance between the second location and the third location is less than the distance between two other opposing sides of each aperture of the plurality of apertures in the film, wherein the two other opposing sides are transverse to the second axis.

27. The system of claim 25 wherein the third location and the fourth location are adjacent locations along a third axis and wherein the distance between the third location and the fourth location is less than the distance between the two other opposing sides of each aperture of the plurality of apertures in the film, wherein the two other opposing sides are transverse to the third axis.

28. The system of claim 25 wherein the second location and the third location are adjacent locations along a second axis and wherein the distance between the second location and the third location is less than the diameters of the apertures of the plurality of apertures in the film.

29. The system of claim 25 wherein the third location and the fourth location are adjacent locations along a third axis and wherein the distance between the third location and the fourth location is less than the diameters of the apertures of the plurality of apertures in the film.

30. The system of claim 21 wherein the film is disposed between the active areas of the sensor cells and a protective outer layer of the sensor array.