Method of and system for exposing a target

1. A method of exposing a field on a target by means of a plurality of charged particle beamlets, the method comprising:

providing a target to be exposed, the target comprising the field;

generating a plurality of charged particle beamlets, the beamlets being generated by one or more aperture arrays having apertures arranged in a plurality of groups, each group generating a plurality of the beamlets;

blanking selected ones of the plurality of beamlets to define positions of exposing or not exposing the target by respective beamlets;

creating relative movement in a first direction between the plurality of beamlets and the target;

deflecting the groups of beamlets in a second direction simultaneously with the relative movement in the first direction such that each unblanked beamlet exposes a plurality of parallel scan lines on the target;

wherein the relative movement in the first direction, the deflection of the plurality of beamlets in the second direction, and the arrangement of the apertures in the one or more apertures arrays, are such that the distance between adjacent parallel scan lines exposed by the unblanked beamlets of each group of beamlets is smaller than a pitch between beamlets from adjacent apertures of the aperture array which generated the group of beamlets.

2. The method of claim 1 , wherein the field on the target is divided into a plurality of stripes, and wherein at least a portion of beamlets in one of the groups of beamlets exposes a portion of a first stripe of the field and a portion of beamlets in the same group of beamlets also exposes a portion of a second stripe of the field adjacent to the first stripe.

3. The method of claim 1 , wherein the scan lines of the beamlets each comprise a pattern section within a first stripe and an overscan section within an adjoining stripe.

4. The method of claim 1 , wherein the relative movement in the first direction between the plurality of beamlets and the target is generated by moving the target in the first direction.

5. The method of claim 1 , wherein at least one of the aperture arrays for generating the charged particle beamlets comprises apertures arranged in rows, each aperture in a row being offset with respect to an adjacent aperture, the offset being in a direction perpendicular to the first direction.

6. The method of claim 5 , wherein the offset between adjacent apertures in the row of the at least one aperture array, the relative movement in the first direction, and the deflection of the plurality of beamlets in the second direction result in the distance between adjacent parallel scan lines exposed by the beamlets being smaller than a pitch between adjacent apertures of the aperture array.

7. The method of claim 1 , wherein the distance between subsequent scan lines exposed by the same beamlet within the array of beamlets is smaller than the projected size of the array in the first direction.

8. The method of claim 1 , wherein the method further comprises defining positions of exposing or not exposing the target by respective beamlets, the exposure or non-exposure in dependence of a blanking or a non blanking of each individual beamlet.

9. The method of claim 8 , wherein the positions of exposing or not exposing the target comprise a virtual grid having a first axis oriented in line with the first direction of movement, and a second axis being oriented transverse thereto.

10. The method of claim 1 , wherein a projection pitch Pproj,X in the first direction between the scan lines is equal to or smaller than a beamlet spot size as projected on the target.

11. The method of claim 1 , wherein scan lines of one or more beamlets from a second scan are interleaved with scan lines of one or more beamlets from a first scan.

12. A charged particle multi-beamlet system for exposing a field on a target using a plurality of charged particle beamlets, the system comprising:

one or more aperture arrays for generating the plurality of charged particle beamlets, the apertures arranged in a plurality of groups, each group of apertures generating a plurality of the beamlets;

a moveable substrate support member for supporting the target to be exposed and moving the substrate in a first direction;

a deflector array for deflecting the groups of beamlets in a second direction, the deflector array comprising a plurality of deflectors, each deflector arranged to deflect a corresponding group of the beamlets;

a control unit for controlling movement of the substrate support member in the first direction and deflection of the groups of beamlets in the second direction to scan the beamlets on the surface of the target;

wherein the movement of the substrate support member and deflection of the groups of beamlets is such that, in combination with the arrangement of the apertures in the one or more apertures arrays, the distance between adjacent parallel scan lines exposed by the beamlets of each group of beamlets is smaller than a pitch between beamlets from adjacent apertures of the aperture array which generated the group of beamlets.

13. The system of claim 12 , wherein the control unit is configured to control movement of the substrate support member and deflection of the groups of beamlets so that at least a portion of a group of the beamlets exposes a portion of a first stripe of the field and a portion of the group of beamlets also exposes a portion of a second stripe of the field adjacent to the first stripe.

14. The system of claim 12 , wherein the control unit is configured to control movement of the substrate support member and deflection of the groups of beamlets so that the scan lines of the beamlets each comprise a pattern section within a first stripe and an overscan section within an adjoining stripe.

15. The system of claim 12 , wherein at least one of the aperture arrays for generating the charged particle beamlets comprises apertures arranged in rows, each aperture in a row being offset with respect to an adjacent aperture, the offset being in a direction perpendicular to the first direction.

16. The system of claim 15 , wherein the offset between adjacent apertures in the row of the at least one aperture array, the relative movement in the first direction, and the deflection of the plurality of beamlets in the second direction result in the distance between adjacent parallel scan lines exposed by the beamlets being smaller than a pitch between adjacent apertures of the aperture array.

17. The system of claim 12 , wherein the distance between subsequent scan lines exposed by the same beamlet within the array of beamlets is smaller than the projected size of the array in the first direction.

18. The system of claim 12 , further comprising a beamlet blanker array for controllably blanking individual beamlets of the plurality of beamlets for exposing or not exposing the target by respective beamlets at defined positions.

19. The system of claim 12 , wherein scan lines of one or more beamlets from a second scan are interleaved with scan lines of one or more beamlets from a first scan.

20. The system of claim 12 , further comprising an array of projection lens systems for projecting the groups of beamlets on to the surface of the target, each projection lens system corresponding with a group of beamlets.