Generating an array of spots on inclined surfaces

1. A system for generating an array of focused spots comprising:

an illumination source, the illumination source configured to generate a beam of illumination;

a diffractive optical element, the illumination source positioned so as to illuminate the diffractive optical element at normal incidence at an off-axis position with the beam of illumination propagating parallel to an optical axis of the diffractive optical element, the diffractive optical element configured to split the beam of illumination into a plurality of diffracted beams; and

a focusing lens, the focusing lens positioned adjacent to the diffractive optical element along the optical axis, the focusing lens configured to focus at least some of the plurality of diffracted beams onto a surface of a wafer into a plurality of elongated spots positioned along a radial direction of the wafer, wherein a direction of elongation of at least some of the plurality of elongated spots is aligned along the radial direction, wherein the focusing lens and the diffractive optical element are arranged to cause at least some of the plurality of diffracted beams from the diffractive optical element to impinge onto the surface of the wafer at an oblique illumination angle relative to the surface of the wafer.

2. The system of claim 1 , wherein the oblique illumination angle ranges from 45 degrees to 85 degrees.

3. The system of claim 1 , wherein the plurality of spots along the optical axis includes a one dimensional spot array.

4. The system of claim 1 , wherein the plurality of spots are positioned in a radial direction, the radial direction parallel to a stage motion direction of the system.

5. The system of claim 4 , wherein an incident plane of the at least some of the plurality of beams is parallel to the radial direction.

6. The system of claim 1 , wherein the diffractive optical element includes a diffractive optical element having concentric circles of grating grooves, a grating pitch of the grating grooves a function of a radius of the diffractive optical element.

7. The system of claim 1 , wherein the surface includes a surface of a silicon wafer.

8. The system of claim 1 , wherein illumination source comprises:

a laser.

9. A method for generating an array of focused spots comprising:

inputting a beam from an illumination source at normal incidence to a diffractive optical element in an off-axis position, the beam propagating parallel to an optical axis of the diffractive optical element;

splitting the beam into a plurality of beams via the diffractive optical element; and

focusing, with a focusing lens positioned adjacent to the diffractive optical element along the optical axis, at least some of the plurality of beams onto a surface of a wafer to create a plurality of elongated spots positioned along a radial direction of the wafer, wherein a direction of elongation of at least some of the plurality of elongated spots is aligned along the radial direction, the at least some of the plurality of beams focused on the surface at an oblique illumination angle relative to the surface of the wafer.

10. The method of claim 9 , wherein the oblique illumination angle ranges from 45 degrees to 85 degrees.

11. The method of claim 9 , wherein the plurality of spots along the optical axis includes a one dimensional spot array.

12. The method of claim 9 , wherein the plurality of spots are positioned in a radial direction, the radial direction parallel to a stage motion direction of the system.

13. The method of claim 12 , wherein an incident plane of the at least some of the plurality of beams is parallel to the radial direction.

14. The method of claim 9 , wherein the diffractive optical element includes a diffractive optical element having concentric circles of grating grooves, a grating pitch of the grating grooves a function of a radius of the diffractive optical element.

15. The method of claim 9 , wherein the surface includes a surface of a silicon wafer.

16. A system for generating an array of focused spots comprising:

an illumination source configured to generate a beam of illumination;

the diffractive optical element, the illumination source positioned so as to illuminate the diffractive optical element at normal incidence at an off-axis position with the beam of illumination propagating parallel to an optical axis of the diffractive optical element, the diffractive optical element configured to split the beam into a plurality of diffracted beams; and

a focusing lens, the focusing lens positioned adjacent to the diffractive optical element along the optical axis, the focusing lens configured to focus at least some of the plurality of diffracted beams onto a surface of a wafer into a plurality of elongated spots positioned along a radial direction of the wafer, wherein a direction of elongation of at least some of the plurality of elongated spots is aligned along the radial direction, the at least some of the plurality of diffracted beams focused on the surface of the wafer at an oblique illumination angle relative to the surface of the wafer,

wherein the plurality of spots are positioned along the radial direction, the radial direction parallel to a stage motion direction of the system, wherein an incident plane of the at least some of the plurality of diffracted beams is along the radial direction.

17. The system of claim 16 , wherein the oblique illumination angle ranges from 45 degrees to 85 degrees.

18. The system of claim 16 , wherein the plurality of spots along the optical axis includes a one dimensional spot array.

19. The system of claim 16 , wherein the diffractive optical element includes a diffractive optical element having concentric circles of grating grooves, a grating pitch of the grating grooves a function of a radius of the diffractive optical element.

20. The system of claim 16 , wherein the surface includes a surface of a silicon wafer.