Lithographic apparatus and device manufacturing method

1. An apparatus comprising:

at least two optical columns each capable of creating a pattern on a target portion of a substrate, each optical column having a self-emissive contrast device configured to emit a beam, and a projection system configured to project the beam onto the target portion;

for each optical column an actuator to move at least a part of the optical column with respect to the substrate; and

at least two optical sensor devices, each individually movable in respect of the optical columns and at least one of the optical sensor devices movable independently of another at least one of the optical sensor devices, wherein at least a first one of the optical sensor devices has a range of movement which enables the optical sensor device to move through a projection area of each of the optical columns to measure a beam of each of the optical columns and at least a second one of the optical sensor devices arranged to measure a beam of at least one of the optical columns.

2. The apparatus according to claim 1 , further comprising for each optical sensor device an optical sensor device actuator to move the optical sensor device, and a controller to drive the optical sensor device actuators, wherein the controller is arranged to drive the optical sensor device actuators to move at least the first one of the optical sensor devices through the projection area of each of the optical columns to measure a beam of each of the optical columns.

3. The apparatus according to claim 2 , wherein the controller is further arranged to drive the optical sensor device actuators to move the second optical sensor device through a projection area of a first one of the optical columns, and to move a third optical sensor device through a projection area of a second one of the optical columns.

4. The apparatus according to claim 3 , wherein each optical column comprises a plurality of self-emissive contrast devices and wherein the controller is arranged to drive the optical sensor device actuators to move the second and/or third optical sensor devices through the projection area of a corresponding optical column, and to successively measure beams of the optical column.

5. The apparatus according to claim 4 , wherein the controller is arranged to level a dose of the self-emissive contrast devices of the first one of the optical columns from the measurements by the second optical sensor device, and level a dose of the self-emissive contrast devices of the second one of the optical columns from the measurements by the third optical sensor device.

6. The apparatus according to claim 2 , wherein the controller is arranged to level a dose of the self-emissive contrast device of the first one of the optical columns in respect of the dose of the self-emissive contrast device of the second one of the optical columns from the measurement by the first optical sensor device.

7. The apparatus according to claim 2 , wherein for a single measurement operation with respect to the optical columns, the controller is configured to move at least the first and second optical sensor devices in a first direction a plurality of times and move at least the first and second optical sensor devices during or after each of the plurality of times in a second direction substantially orthogonal to the first direction to take measurements of the optical columns.

8. The apparatus according to claim 1 , wherein at least part of the optical column is rotatable in respect of the substrate, each optical column is configured to emit a plurality of beams forming a circle segment shape on the substrate, and the optical columns are arranged in a row or staggered row in a direction perpendicular to a scanning direction of the substrate.

9. The apparatus according to claim 1 , further comprising an assembly having at least the first and second optical sensor devices, wherein the assembly is movable in a first direction and at least the first and second optical sensor devices are movable in a second direction substantially orthogonal to the first direction with the respect to the assembly.

10. The apparatus according to claim 1 , wherein at least the first optical sensor device is spaced apart on the assembly from at least the second optical sensor device in the first direction.

11. A device manufacturing method, comprising:

creating a pattern on a target portion of a substrate using at least two optical columns, each optical column emitting a beam using a self-emissive contrast device and projecting the beam onto the target portion with a projection system;

moving at least a part of the optical columns with respect to the substrate;

moving a first optical sensor device in respect of the optical columns through a projection area of each of the optical columns to measure an optical parameter of the beam emitted by each of the optical columns; and

moving a second optical sensor device in respect of the optical columns and independently of the first optical sensor device, to measure an optical parameter of the beam emitted by at least one of the optical columns.

12. The method according to claim 11 , comprising moving the second optical sensor device through a projection area of a first one of the optical columns, and moving a third optical sensor device through a projection area of a second one of the optical columns.

13. The method according to claim 12 , wherein each optical column comprises a plurality of self-emissive contrast devices and comprising moving the second and/or third optical sensor device through the projection area of a corresponding optical column, and measuring beams of the optical column.

14. The method according to claim 13 , comprising leveling a dose of the self-emissive contrast devices of the first one of the optical columns from the measurements by the second optical sensor device, and leveling a dose of the self-emissive contrast devices of the second one of the optical columns from the measurements by the third optical sensor device.

15. The method according to claim 11 , comprising leveling a dose of the self-emissive contrast device of a first one of the optical columns in respect of the dose of the self-emissive contrast device of a second one of the optical columns from the measurement by the first optical sensor device.

16. The method according to claim 11 , wherein at least part of the optical column is rotatable in respect of the substrate, each optical column is configured to emit a plurality of beams forming a circle segment shape on the substrate, and the optical columns are arranged in a row or staggered row in a direction perpendicular to a scanning direction of the substrate.

17. The method according to claim 11 , wherein the moving the first optical sensor device comprises successively measuring by the first optical sensor device an optical parameter of the beam emitted by each of the optical columns.

18. The method according to claim 11 , wherein the first and second optical sensor devices are part of an assembly and moving the first and second optical sensor devices comprises moving the first and second optical sensor devices in a first direction with the respect to the assembly and the method further comprises moving the assembly in a second direction substantially orthogonal to the first direction.

19. The method according to claim 18 , wherein the first optical sensor device is spaced apart on the assembly from the second optical sensor device in the second direction.

20. The method according to claim 11 , wherein for a single measurement operation with respect to the optical columns, the operation comprises moving the first and second optical sensor devices in a first direction a plurality of times and moving the first and second optical sensor devices during or after each of the plurality of times in a second direction substantially orthogonal to the first direction to take measurements of the optical columns.