Lithographic apparatus, device manufacturing methods, mask and method of characterizing a mask and/or pellicle

• US 20050140949A1
• Filed: 04/30/2004
• Published: 06/30/2005
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Dominique Wehrens, Martijn Gerard, Jansen, Albert Johannes Maria, Uitterdijk, Tammo, Baggen, Marcel Koenraad Marie, Boom, Herman, Bruls, Richard Joseph, Hofmans, Gerardus Carolus Johannus, Pongers, Willem Richard, Luijten, Carlo Cornelis Maria, Cicilia, Orlando Serapio, Demarteau, Marcel Johannes Louis Marie, Van Dijck, Hendrikus Alphonsus Ludovicus, Jasper, Johannes Christiaan Maria
• Granted Patent: US 7,379,154 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• CPC Class Codes: G03F 1/62 Pellicles, e.g. pellicle assemblies, e.g. having membrane on support frame; Preparation thereof
• CPC Class Codes: G03F 1/64 characterised by the frames, e.g. structure or material, including bonding means therefor
• CPC Class Codes: G03F 1/82 Auxiliary processes, e.g. cleaning or inspecting
• CPC Class Codes: G03F 7/70258 Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system
• CPC Class Codes: G03F 7/70308 Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift
• CPC Class Codes: G03F 7/70983 Optical system protection, e.g. pellicles or removable covers for protection of mask

Abstract

A thick pellicle is allowed to have a non-flat shape and its shape is characterized to calculate corrections to be applied in exposures to compensate for the optical effects of the pellicle. The pellicle may be mounted so as to adopt a one-dimensional shape under the influence of gravity to make the compensation easier.

Claims

1. A lithographic projection apparatus comprising:

an illumination system for supplying a projection beam of radiation;

a support structure for supporting a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern;

a substrate table for holding a substrate;

a projection system for projecting the patterned beam onto a target portion of the substrate;

a layer, substantially transparent to said projection beam but having a refractive

index different than the surrounding medium, in the optical path of said projection beam between said patterning device and said substrate;

a storage device adapted to store information relating to the physical and/or optical characteristics of said layer; and

a controller adapted to control at least one of said projection system, said radiation system, said substrate table and said support structure in response to information stored in said storage device to compensate for imaging aberrations caused by said layer other than a displacement of an apparent mask position along an optical axis of the apparatus.

2. Apparatus according to claim 1, wherein said patterning device is a mask, said support structure is a mask table and said layer is a pellicle mounted in spaced relation thereto.

3. Apparatus according to claim 2, further comprising an interface for receiving said information in conjunction with the loading of a mask into the apparatus.

4. Apparatus according to claim 2, further comprising a sensor for measuring one or more characteristics selected for the group consisting of physical and optical characteristics of a pellicle fixed to said mask supported by said mask table and wherein said controller is further adapted to control at least one of the sensor and the mask table to characterize the pellicle to generate said information to be stored in said storage device.

5. Apparatus according to claim 4, wherein said sensor is a transmission image sensor.

6. Apparatus according to claim 4, wherein said sensor is a white light interferometer.

7. Apparatus according to claim 2, further comprising a spoiler attached to one of said mask stage, said mask, said pellicle and a frame, mounting said pellicle to said mask, wherein said spoiler is shaped to reduce Bernoulli effects that would otherwise distort said pellicle when said mask moves during an exposure.

8. Apparatus according to claim 2, further comprising a purge gas supply system adapted to supply purge gas to a vicinity of said mask such that the flow of purge gas is parallel to and in the same sense as movement of said mask during a scanned exposure.

9. Apparatus according to claim 2, wherein said storage device stores information relating to the dependency of image aberration on the velocity of movement of said mask during a scanned exposure.

10. Apparatus according to claim 1 wherein said patterning device is a programmable patterning device and said layer is a window in a box containing said programmable patterning device.

11. Apparatus according to claim 1, wherein said layer is a liquid film between said projection system and said substrate.

12. A mask having a pellicle fixed to a frame in spaced relation thereto, wherein said pellicle is fixed to said frame such that in use, it adopts a shape that introduces distortions that are substantially compensatable for by adjustment of available system parameters of a lithographic apparatus with which the mask is to be used.

13. A mask according to claim 12 wherein said pellicle is fixed to said frame along two parallel edges and compliantly mounted along the other edges such that said pellicle adopts a substantially one-dimensional shape when in the orientation in which it will be used for exposures in a lithographic projection apparatus.

14. A mask according to claim 13 wherein said pellicle is fixed to said frame at said two parallel edges at an angle equal to that that would be adopted were the pellicle allowed to bow freely under gravity.

15. A mask according to claim 13 wherein said pellicle is fixed to said frame at both of said parallel edges at an angle of 0°

.

16. A method of attaching a pellicle to a mask, comprising:

measuring the shape of said pellicle;

determining an optimum position of said pellicle relative to said mask; and

attaching said pellicle to said mask substantially at said optimum position.

17. A method comprising:

loading a mask into a lithographic projection apparatus;

illuminating the mask with exposure radiation;

projecting an aerial image of the illuminated mask; and

measuring a plane of best focus of the images of a plurality of alignment marks using an image sensor;

wherein said plurality of alignment marks are spaced apart in the scanning direction or the direction of the illumination field of the lithographic apparatus.

18. A method as in claim 17, wherein the mask further has a pellicle fixed in spaced rotation thereto.

19. A device manufacturing method comprising:

patterning a projection beam of radiation with a pattern in its cross-section using a mask having a pellicle or fixed relation thereto;

projecting the patterned beam of radiation onto a target portion of a layer of radiation-sensitive material on a substrate; and

prior to an exposure characterizing a shape of the mask by the method of;

measuring the shape of said pellicle;

determining an optimum position of said pellicle relative to said mask;

attaching said pellicle to said mask substantially at said optimum position; and

correcting exposure parameters based on the characterizing.

20. A device manufacturing method comprising:

patterning a projection beam of radiation with a pattern in its cross-section using a mask having a pellicle or fixed relation thereto;

projecting the patterned beam of radiation onto a target portion of a layer of radiation-sensitive material on a substrate; and

prior to an exposure characterizing a shape of the mask by the method of;

measuring the shape of said pellicle;

determining an optimum position of said pellicle relative to said mask;

attaching said pellicle to said mask substantially at said optimum position; and

correcting parameters pertaining to at least one of a radiation system, a projection system, a position of the mask and a position of the substrate to compensate for aberrations other than a shift in apparent position of the mask in the direction of the optical axis of said projection system caused by said pellicle, said corrections having been determined from information relating to physical and/or optical characteristics of said pellicle.