Lithographic Apparatus and Device Manufacturing Method Using Pupil Filling By Telecentricity Control

• US 20080309898A1
• Filed: 06/14/2007
• Published: 12/18/2008
• Est. Priority Date: 06/14/2007
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Baselmans, Johannes Jacobus Matheus
• Granted Patent: US 8,692,974 B2
• Time in Patent Office: Days
• US Class Current: 355/52
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/706 Aberration measurement
• 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 method of measuring aberration present in a lithographic apparatus comprising the following steps. Modulating a radiation beam using a reflective patterning device. Projecting the radiation beam using a projection system. Detecting the projected radiation using a sensor. Measuring aberration via interference in the detected radiation beam. The radiation beam is tilted away from the optical axis of the projection system prior to entering the projection system.

Claims

1. A method of measuring aberration present in a lithographic apparatus, comprising:

modulating a radiation beam using a reflective patterning device;

projecting the modulated radiation beam using a projection system;

detecting the projected radiation beam using a sensor; and

measuring an aberration via interference in the detected radiation beam;

wherein the modulated radiation beam is tilted away from an optical axis of the projection system prior to entering the projection system.

2. The method of claim 1, wherein the modulated radiation beam is tilted such that the modulated radiation beam overlaps an edge of an entrance pupil of the projection system.

3. The method of claim 1, wherein aberration is measured with the modulated radiation beam tilted in a first direction, and is then subsequently measured with the modulated radiation beam tilted in a second direction.

4. The method of claim 3, wherein aberration is subsequently measured with the modulated radiation beam tilted in one or more additional directions.

5. The method of claim 3, wherein if two different aberration measurements are obtained for a given location of the lithography apparatus, an average of the measurements is determined.

6. The method of claim 1, wherein the modulated radiation beam is tilted by tilting the reflective patterning device.

7. The method of claim 1, wherein the radiation beam is tilted by an optical component prior to being incident upon the reflective patterning device.

8. The method of claim 7, wherein the optical component forms part of an illumination system of the lithographic apparatus.

9. The method of claim 1, wherein the reflective patterning device is a reflective mask or an array of individually controllable elements.

10. A lithographic apparatus, comprising:

a reflective patterning device configured to modulate a beam of radiation;

a projection system configured to project the modulated beam of radiation; and

a sensor arranged to detect interference in the radiation projected by the projection system;

wherein the reflective patterning device is configured to be rotatable transverse to its optical axis, the rotation being arranged to tilt the modulated radiation beam away from an optical axis of the projection system prior to entering the projection system.

11. The lithographic apparatus of claim 10, wherein the range of rotational movement of the reflective patterning device is sufficient that the modulated radiation beam overlaps an edge of an entrance pupil of the projection system.

12. The lithographic apparatus of claim 10, wherein the range of rotational movement of the reflective patterning device is sufficient that the modulated radiation beam is moved to a plurality of different positions at the entrance pupil of the projection system, such that the combination of different positions fills the entrance pupil of the projection system.

13. The lithographic apparatus of claim 10, wherein the reflective patterning device is a reflective mask or an array of individually controllable elements.

14. A lithographic apparatus, comprising:

a reflective patterning device configured to modulate a beam of radiation;

a projection system configured to project the modulated beam of radiation; and

a sensor arranged to detect interference in the radiation projected by the projection system;

wherein the lithographic apparatus further comprises a moveable optical component arranged to tilt the radiation beam away from an optical axis, prior to the radiation beam being incident upon the reflective patterning device.

15. The lithographic apparatus of claim 14, wherein the optical component is a rotatable mirror.

16. The lithographic apparatus of claim 14, wherein the moveable optical component forms part of an illumination system of the lithographic apparatus.

17. The lithographic apparatus of claim 14, wherein the range of movement of the optical component is sufficient that the radiation beam overlaps an edge of an entrance pupil of the projection system.

18. The lithographic apparatus of claim 14, wherein the range of rotational movement of the optical component is sufficient that the radiation beam is moved to a plurality of different positions at the entrance pupil of the projection system, such that the combination of different positions fills the entrance pupil of the projection system.

19. A method of measuring transmission of a projection system of a lithographic apparatus as a function of angle, comprising:

reflecting a radiation beam using a reflective patterning device;

projecting the reflected radiation beam using a projection system; and

measuring the intensity of projected radiation using a sensor;

wherein a first intensity measurement is obtained with the reflected radiation beam tilted in a first direction, away from an optical axis of the projection system, prior to entering the projection system, and

a second intensity measurement is obtained with the reflected radiation beam tilted in a second direction, away from the optical axis of the projection system, prior to entering the projection system.

20. The method of claim 19, wherein an apodization of the projection system or a numerical aperture of the projection system is measured.