EXPOSURE APPARATUS AND METHODS

• US 20110292363A1
• Filed: 07/30/2009
• Published: 12/01/2011
• Est. Priority Date: 07/30/2008
• Status: Active Grant

• Current Assignee: University of Durham, University of Sheffield
• Original Assignee: University of Durham, University of Sheffield
• Inventors: Toriz-Garcia, Jose Juan De Jesus, Curry, Richard Ian, Ivey, Peter Anthony, McWilliam, Richard Peter, Purvis, Alan, Seed, Nicholas Luke, Williams, Gavin Lewis
• Granted Patent: US 9,046,874 B2
• Time in Patent Office: Days
• US Class Current: 355/55
• CPC Class Codes: G03F 7/70158 Diffractive optical elements
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/703 Non-planar pattern areas or non-planar masks, e.g. curved masks or substrates
• CPC Class Codes: G03F 7/70408 Interferometric lithography; Holographic lithography; Self-imaging lithography, e.g. utilizing the Talbot effect
• CPC Class Codes: G03F 7/70416 2.5D lithography
• CPC Class Codes: G03H 1/0005 Adaptation of holography to specific applications holographic optical element G02B5/32; holographic scanner G02B26/106; recognition using holographic mask G06V10/88; holographic memories G11B7/0065, G11C13/042
• CPC Class Codes: G03H 1/0443 Digital holography, i.e. recording holograms with digital recording means holobject computation G03H1/0866
• CPC Class Codes: G03H 1/08 Synthesising holograms, i.e. holograms synthesized from objects or objects from hologramsusing electric digital computers G06F; G06T
• CPC Class Codes: G03H 1/22 Processes or apparatus for obtaining an optical image from holograms G03H1/26 - G03H1/34 take precedence
• CPC Class Codes: G03H 1/2294 Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 2001/0038 analogue or digital holobjects
• CPC Class Codes: G03H 2001/005 in microscopy, e.g. digital holographic microscope [DHM]
• CPC Class Codes: G03H 2001/0088 for video-holography, i.e. integrating hologram acquisition, transmission and display
• CPC Class Codes: G03H 2001/0094 for patterning or machining using the holobject as input light distribution
• CPC Class Codes: G03H 2001/2215 Plane screen
• CPC Class Codes: G03H 2001/2221 Screen having complex surface, e.g. a structured object
• CPC Class Codes: G03H 2001/264 One hologram being a HOE
• CPC Class Codes: G03H 2225/32 Phase only

Abstract

A light beam collimated by illumination optics (4) from a radiation source (6) illuminates the surface of a wave front modulator (8) such as an Spatial Light Modulator (SLM) or Computer Generated Hologram photomask (CGH). The resulting wave travels via projection optics (10) to the substrate (12), passing through a projection lens assembly (14). The SLM (8) is programmed or CGH configured with a modulation pattern that is determined by the substrate (12) topography and desired pattern. The substrate topography is provided by Digital Holography (DH) surface profilometery performed by a DH microscope (18), which provides geometrical or topographical input to the CGH calculation routines (16). An arrangement for vertical or sloping surface patterning has a grating (22) superimposed onto the CGH pattern (24) to generate +1 and −1 orders. The SLM or CGH may be configured: using Fresnel patterns to provide an extended depth of field of the projected wave front; by encoding line segments of the desired pattern as cylindrical lines; by calculating inverse propagation between non-planar topography of the substrate and the SLM or CGH (using a Rayleigh-Sommerfield diffraction formula); and/or using iteration to determine a restricted encoding in the configuration of the SLM or CGH.

Claims

1. An exposure apparatus for projecting radiation corresponding to a pattern onto a substrate, the exposure apparatus comprising:

a wave front control means configured to alter a wave front of the radiation;

configuration means for configuring the wave front control means based on the pattern and a topography of the substrate; and

a projection means for projecting the altered wave front onto a substrate.

2. An exposure apparatus according to claim 1, wherein the configuration means is operable to configure the wave front control means using Fresnel patterns to provide an extended depth of field of the projected altered wave front.

3. An exposure apparatus according to claim 1, wherein the configuration means is operable to configure the wave front control means by encoding line segments of the pattern as cylindrical lines.

4. An exposure apparatus according to claim 1, wherein the projection means comprises a phase grating arranged with the wave front control means to transform the focal plane of the altered wave front for projection on to a vertical or sloping side wall of the substrate.

5. An exposure apparatus according to claim 4, wherein the phase grating is curved to transform the focal plane of the altered wave front for projection on to the inside of a curved hole of the substrate.

6. An exposure apparatus according to claim 1, wherein the configuration means is operable to configure the wave front control means by calculating inverse propagation between non-planar topography of the substrate and the wave front control means.

7. An exposure apparatus according to claim 6, wherein the configuration means is operable to calculate the inverse propagation using a Rayleigh-Sommerfield diffraction formula.

8. An exposure apparatus according to claim 6, wherein the configuration means is operable to calculate the inverse propagation using iteration to determine a restricted encoding in the configuration of the wave front control means.

9. An exposure apparatus according to claim 1, further comprising a radiation source means for providing the wave front configuration means with partially coherent radiation to be altered.

10. An exposure apparatus according to claim 1, further comprising a substrate profiling means for determining the topography of the substrate.

11. An exposure apparatus according to claim 10, wherein the substrate profiling means comprises a digital holography inspection apparatus.

12. A method of projecting radiation corresponding to a pattern onto a substrate, the method comprising the steps:

altering a wave front of the radiation;

configuring the altering based on the pattern and a topography of the substrate; and

projecting the altered wave front onto a substrate.

13. A method according to claim 12, wherein the step of configuring uses Fresnel patterns to provide an extended depth of field of the projected altered wave front.

14. A method according to claim 12, wherein the step of configuring comprises encoding line segments of the pattern as cylindrical lines.

15. A method according to claim 12, wherein the step of projecting comprises using a phase grating to transform the focal plane of the altered wave front for projection on to a vertical or sloping side wall of the substrate.

16. A method according to claim 15, wherein the phase grating is curved to transform the focal plane of the altered wave front for projection on to the inside of a curved hole of the substrate.

17. A method according to claim 12, wherein the step of configuring comprises calculating inverse propagation between non-planar topography of the substrate and a wave front control means used to perform the step of altering.

18. A method according to claim 17, wherein the step of calculating the inverse propagation comprises using a Rayleigh-Sommerfield diffraction formula.

19. A method according to claim 17, wherein the step of calculating the inverse propagation comprises using iteration to determine a restricted encoding in the step of configuring.

20. A method according to claim 12, further comprising the step of providing the step of altering with partially coherent radiation to be altered.

21. A method according to claim 12, further comprising the step of determining the topography of the substrate.

22. A method according to claim 21, wherein the step of determining the topography of the substrate comprises using digital holography inspection.

23. A reticle for use in projecting radiation corresponding to a pattern onto a substrate, the reticle comprising a wave front control means configured to alter a wave front of the radiation based on the pattern and a topography of the substrate.

24. An exposure apparatus for projecting radiation corresponding to a pattern onto a substrate, the exposure apparatus comprising:

a wave front control means configured to alter a wave front of the radiation;

a projection means for projecting the altered radiation onto a substrate; and

configuration means for configuring the wave front control means using Fresnel patterns to provide an extended depth of field of the projected altered wave front.

25. A method of projecting radiation corresponding to a pattern onto a substrate, the method comprising the steps:

altering a wave front of the radiation;

projecting the altered radiation onto a substrate; and

configuring the altering using Fresnel patterns to provide an extended depth of field of the projected altered wave front.

26. A reticle for use in projecting radiation corresponding to a pattern onto a substrate, the reticle comprising a wave front control means configured to alter a wave front of the radiation using Fresnel patterns to provide an extended depth of field of the projected altered wave front.

27. An exposure apparatus for projecting radiation corresponding to a pattern onto a substrate, the exposure apparatus comprising:

a wave front control means configured to alter a wave front of the radiation;

a projection means for projecting the altered radiation onto a substrate; and

configuration means for configuring the wave front control means by encoding line segments as cylindrical lines to provide an extended depth of field of the projected altered wave front.

28. A method of projecting radiation corresponding to a pattern onto a substrate, the method comprising the steps:

altering a wave front of the radiation;

projecting the altered radiation onto a substrate; and

configuring the altering by encoding line segments as cylindrical lines to provide an extended depth of field of the projected altered wave front.

29. A reticle for use in projecting radiation corresponding to a pattern onto a substrate, the reticle comprising a wave front control means configured to alter a wave front of the radiation by encoding line segments as cylindrical lines to provide an extended depth of field of the projected altered wave front.