U.S. patent number RE45,511 [Application Number 12/764,557] was granted by the patent office on 2015-05-12 for method of using deformable mirror using piezoelectric actuators formed as an integrated circuit.
This patent grant is currently assigned to ASML Holding N.V.. The grantee listed for this patent is Pradeep K. Govil, Andrew Guzman. Invention is credited to Pradeep K. Govil, Andrew Guzman.
United States Patent |
RE45,511 |
Govil , et al. |
May 12, 2015 |
Method of using deformable mirror using piezoelectric actuators
formed as an integrated circuit
Abstract
A deformable optical device includes a reflection device having
a first reflecting surface and a second surface, an actuator (e.g.,
an integrated circuit piezoelectric actuator) having a support
device and moveable extensions extending therefrom, which are
coupled to the second surface, and electrodes coupled to
corresponding ones of the extensions. Wavefront aberrations are
detected and used to generate a control signal. The extensions are
moved based on the control signal. The movement deforms the
reflecting surface to correct the aberrations in the wavefront.
Inventors: |
Govil; Pradeep K. (Norwalk,
CT), Guzman; Andrew (Yarmouth, ME) |
Applicant: |
Name |
City |
State |
Country |
Type |
Govil; Pradeep K.
Guzman; Andrew |
Norwalk
Yarmouth |
CT
ME |
US
US |
|
|
Assignee: |
ASML Holding N.V. (Veldhoven,
NL)
|
Family
ID: |
34103691 |
Appl.
No.: |
12/764,557 |
Filed: |
April 21, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
10629798 |
May 29, 2007 |
7224504 |
|
|
Reissue of: |
11244006 |
Oct 6, 2005 |
7372614 |
May 13, 2008 |
|
|
Current U.S.
Class: |
359/290; 359/291;
359/846; 359/900; 359/849 |
Current CPC
Class: |
G02B
26/0825 (20130101); G02B 26/0841 (20130101); Y10S
359/90 (20130101) |
Current International
Class: |
G02B
26/00 (20060101); G02B 5/08 (20060101) |
Field of
Search: |
;359/290-291,846,849,900,191.4,200.8,224.1,224.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
63-36526 |
|
Feb 1988 |
|
JP |
|
9-298154 |
|
Nov 1997 |
|
JP |
|
2003-52181 |
|
Feb 2003 |
|
JP |
|
2003-90969 |
|
Mar 2003 |
|
JP |
|
2003-161874 |
|
Jun 2003 |
|
JP |
|
2003-534653 |
|
Nov 2003 |
|
JP |
|
WO 98/33096 |
|
Jul 1998 |
|
WO |
|
WO 98/33096 |
|
Jul 1998 |
|
WO |
|
WO 98/38597 |
|
Sep 1998 |
|
WO |
|
WO 98/38597 |
|
Sep 1998 |
|
WO |
|
WO 98/38597 |
|
Sep 1998 |
|
WO |
|
WO 01/090820 |
|
Nov 2001 |
|
WO |
|
Other References
Non-Final Rejection mailed Jul. 3, 2007 for U.S. Appl. No.
11/244,006, 6 pgs. cited by applicant .
Non-Final Rejection mailed Oct. 18, 2005 for U.S. Appl. No.
10/629,798, 6 pgs. cited by applicant .
Non-Final Rejection mailed Apr. 21, 2006 for U.S. Appl. No.
10/629,798, 6 pgs. cited by applicant .
Final Rejection mailed Oct. 19, 2006 for U.S. Appl. No. 10/629,798,
8 pgs. cited by applicant .
Bonaccini, D., et al., "Adaptive optics wavefront corrector using
addressable liquid crystal retarders: II," Proceedings of SPIE,
Active and Adaptive Optical Components, vol. 1543, 1991; pp.
133-143. cited by applicant .
Booth, M. J., et al., "Adaptive aberration correction in a confocal
microscope," Proceedings of the National Academy of Sciences
(PNAS), vol. 99, No. 9, Apr. 30, 2002; pp. 5788-5792. cited by
applicant .
Zhu, L., et al., "Wave-front generation of Zernike polynomial modes
with a micromachined membrane deformable mirror," Applied Optics,
vol. 38, No. 28, Oct. 1, 1999; pp. 6019-6026. cited by applicant
.
Notice of Allowance mailed Feb. 5, 2007 for U.S. Appl. No.
10/629,798, filed Jul. 30, 2003; 4 pages. cited by applicant .
Notice of Allowance mailed Oct. 22, 2007 for U.S. Appl. No.
11/244,006, filed Oct. 6, 2005; 4 pages. cited by applicant .
Notice of Allowance mailed Jan. 10, 2008 for U.S. Appl. No.
11/244,006, filed Oct. 6, 2005; 7 pages. cited by applicant .
Office Action and Translation of Office Action for Japanese Patent
Application No. 2004-219135 drafted on Oct. 30, 2007, 7 pages.
cited by applicant.
|
Primary Examiner: Phan; James
Attorney, Agent or Firm: Sterne, Kessler, Goldstein &
Fox P.L.L.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. application Ser. No.
10/629,798, filed Jul. 30, 2003, now U.S. Pat. No. 7,224,504, which
is incorporated by reference herein in its entirety.
Claims
What is claimed is:
1. A method comprising: detecting wavefront aberrations; generating
a control signal based on the detected aberration; moving
extensions of a piezoelectric actuator based on the control signal;
deforming a reflector based on the moving of the extensions to
correct the aberrations in the wavefront; measuring a change in
capacitance of the extensions; and verifying the deformation of the
reflector based on the measured change in capacitance.
2. The method of claim 1, wherein the moving and deforming steps
compensate for higher order values of the aberrations.
3. The method of claim 1, further comprising generating a Zernike
polynomial from the detecting step, wherein the moving and
deforming steps correct for aberrations corresponding to all orders
of the Zernike polynomial.
4. The method of claim 1, further comprising: providing a
deformable mirror for the reflector to correct the aberrations in
the wavefront.
5. The method of claim 1, further comprising: forming the
piezoelectric actuator in an integrated circuit.
.Iadd.6. The method of claim 1, wherein the extensions are coupled
approximately at an edge of the reflector..Iaddend.
.Iadd.7. The method of claim 1, wherein the moving controls
actuation of edge-positioned ones of the extensions to control
movement of the reflector..Iaddend.
.Iadd.8. A method comprising: providing an actuator in an
integrated circuit; detecting wavefront aberrations; generating a
control signal based on the detecting; moving extensions of the
actuator based on the control signal; deforming a reflector based
on the moving; measuring a movement of the extensions of the
actuator; and verifying the deformation of the reflector based on
the measured movement..Iaddend.
.Iadd.9. The method of claim 8, wherein the measuring a movement
further comprises: measuring a change in capacitance of the
extensions..Iaddend.
.Iadd.10. The method of claim 8, wherein the moving and the
deforming compensate for higher order values of the wavefront
aberrations..Iaddend.
.Iadd.11. The method of claim 8, further comprising: generating a
Zernike polynomial from the detecting, wherein the moving and the
deforming correct for wavefront aberrations corresponding to all
orders of the Zernike polynomial..Iaddend.
.Iadd.12. The method of claim 8, further comprising: correcting the
wavefront aberration using a deformable mirror of the
reflector..Iaddend.
.Iadd.13. The method of claim 8, wherein the extensions are coupled
approximately at an edge of the reflector..Iaddend.
.Iadd.14. The method of claim 8, wherein the moving controls
actuation of edge-positioned ones of the extensions to control
movement of the reflector..Iaddend.
.Iadd.15. The method of claim 8, wherein moving the extensions
comprises moving extensions that have various heights based on a
desired amount of decoupling between the extensions..Iaddend.
.Iadd.16. The method of claim 8, wherein the actuator is a
piezoelectric actuator..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to deformable optical devices.
2. Background Art
Light passing through an optical system can become distorted for
various reasons. A lens, mirror, coatings thereon, or other devices
in the optical system can: have imperfections, contaminants, or
defects on their surface or within their structure. These together
with thermal and other environmental factors including the ambient
properties are sources of error in the light beam. Wavefront
aberrations can lead to substantial degrading of the operation of
an apparatus having the optical system.
For example, in photolithography where the state of the art
requires nanometer level resolution, even small wavefront
aberrations in the light beam can cause substantial errors in
patterned devices. If these errors are outside of a tolerance
budget, the devices will fail. Thus, optical elements within the
photolithography systems must be manufactured to exacting
tolerances and their environment tightly controlled.
Since practical limits exist in manufacturing tolerances and
environmental control, some optical systems use deformable optics,
such as deformable mirrors, to help compensate for wavefront
aberrations. The deformable mirrors normally include an array of
discrete actuators coupled between the mirror and a support. A
measuring device (e.g., inline or offline) measures, either
continuously or at the beginning of a cycle, the wavefront
aberrations at one or more sections of the optical system. A
control signal is then generated and transmitted to the actuators,
which individually move an area of the deformable optic. The
wavefront of the light beam reflecting from the deformed surface is
adjusted to compensate for the aberration, and produce a
substantially ideal wavefront.
One problem with the conventional deformable optics is that they
use rather large actuators to move the optic. Based on the
actuator's size and the size of the deformable optic, only a
certain number of actuators (e.g., a certain density of actuators)
can be coupled to the deformable optic, which limits the amount of
fine correction. Density also directly correlates to the type of
aberration that can be corrected, i.e., a lower density only allows
for correction of lower order (e.g. lower spatial frequency)
aberrations. Typical deformable optics can correct for only low
order aberrations based on their low actuator density. However,
sometimes higher order (e.g. higher spatial frequency) aberrations
are necessary to correct. For example, sometimes wavefront
aberrations are characterized using Standard Zernike polynomials,
including higher orders. Conventional actuator densities cannot
adequately correct for higher order terms.
Therefore, a deformable optic is needed that can correct for higher
order terms of wavefront aberrations in an optical system.
BRIEF SUMMARY OF THE INVENTION
Embodiments of the present invention provide a deformable optical
system. The deformable optical system includes a reflection device
having a first reflecting surface and a second surface and an
integrated circuit actuator having a support device and moveable
extensions extending from the support surface and coupled to the
second surface. Electrodes are individually coupled to
corresponding ones of the extensions. A controller is coupled to
the electrodes and is configured to control the extensions via the
electrodes.
Other embodiments of the present invention provide a deformable
optical device. The deformable optical device includes a reflection
device having a first reflecting surface and a second surface, an
integrated circuit actuator having a support device and moveable
extensions extending therefrom, which are coupled to the second
surface, and electrodes coupled to corresponding ones of the
extensions.
Still other embodiments of the present invention provide a method.
The method includes detecting a wavefront aberration, generating a
control signal based on the detected aberration, moving extensions
of a integrated circuit piezoelectric actuator based on the control
signal, and deforming a reflector based on the moving of the
extensions to correct the aberrations in the wavefront.
Further embodiments, features, and advantages of the present
inventions, as well as the structure and operation of the various
embodiments of the present invention, are described in detail below
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES
The accompanying drawings, which are incorporated herein and form
part of the specification, illustrate the present invention and,
together with the description, further serve to explain the
principles of the invention and to enable a person skilled in the
relevant art(s) to make and use the invention.
FIG. 1 is a deformable optic system according to an embodiment of
the present invention.
FIG. 2 is a deformable optic system according to another embodiment
of the present invention.
FIG. 3 shows an exemplary actuator extension configuration
according to embodiments of the present invention.
The present invention is described with reference to the
accompanying drawings. In the drawings, like reference numbers can
indicate identical or functionally similar elements. Additionally,
the leftmost digit of a reference number usually identifies the
drawing in which the reference number first appears.
DETAILED DESCRIPTION OF THE INVENTION
Overview
While specific configurations and arrangements are discussed, it
should be understood that this is done for illustrative purposes
only. A person skilled in the pertinent art will recognize that
other configurations and arrangements can be used without departing
from the spirit and scope of the present invention. It will be
apparent to a person skilled in the pertinent art that this
invention can also be employed in a variety of other
applications.
Embodiments of the present invention provide a deformable optical
device having a reflective device coupled to an integrated circuit
actuator including a support device and moveable extensions formed
thereon. The integrated circuit actuator has a very high density of
extensions (e.g., actuation devices), which can be formed in any
pattern desired.
The high density of actuators is possibly because of using
integrated circuit technology to manufacture the actuator. For
example, the extensions can be on a micron scale and related
density, which was not possible in conventional actuators. Larger
scale (e.g. millimeter scale) extensions and related density are
possible also; therefore the use of integrated circuit technology
is applicable both within and outside of the realm of conventional
actuators. Furthermore, the scale of extensions and related density
are only limited by the state of the art of integrated circuit
technology and thus sub-micron level scales are also possible.
Having the high density of extensions allows the integrated circuit
actuator to individually (or in small groups to) deform very small
(e.g., micron level) areas of the reflective device, producing a
very fine tunable deformation. This, in turn, allows the deformable
mirror to correct for high order aberrations in a wavefront as well
as low order.
For example, an integrated circuit piezoelectric actuator having a
very high number of piezoelectric pins on a micron scale that
extend from a support can be formed, for example using lithography
techniques. Each pin on the actuator can be individually coupled
through individual control lines to a controller. The pins are
coupled to small areas of the reflective optic, so that very fine
adjustments can be made to the reflective surface of the reflective
optic. In one embodiment, there can be up to about 1 million
actuators per square millimeter, which is much denser than
conventional systems by several orders of magnitude. For example,
U.S. Pat. No. 4,944,580 to MacDonald et. al. shows a conventional
actuator element being about 0.2-0.3 inches on a side (e.g., 5 mm
on a side), which is about 0.04 per square millimeter. It is to be
appreciated that even more actuators may be manufactured per square
millimeter as technology advances, as would be obvious to one of
ordinary skill in the art. This is also contemplated within the
scope of the present invention.
Further, using integrated circuit technology to manufacture the
actuator elements allows for a substantial decrease in overall cost
and a substantial increase in the complexity of patterns that the
actuator elements can be formed in to interact with the deformable
optic.
Planar Actuator and Reflective Device
FIG. 1 shows a system 100 according to embodiments of the present
invention. One example of system 100 is a deformable optics system.
System 100 includes a deformable optics device 102 coupled to a
control system 104. Optionally, a measuring system 106 can also be
coupled to the control system 104. Measuring system 106 can be used
to detect a wavefront of light passing through system 100 to
determine wavefront aberrations. Controller 104 can then calculate
compensation values, and control signals based thereon can be used
to control deformable optics device 102.
For example, light passing through an optical system and/or a
reticle in a lithography system can be measured (either offline or
online), using measuring system 106, to detect wavefront
aberrations. A compensation value can be calculated, which is used
to generate control signals transmitted from control system 104 to
deformable optics device 102. Then, before the light is projected
onto a substrate for patterning, the light is reflected from
deformable optics device 102. Thus, the patterning light is
substantially corrected of aberrations, greatly improving the
performance of a patterned device.
Deformable optics device 102 includes a reflective device 110
(e.g., a mirror), an integrated circuit actuator 112 (e.g., an
integrated circuit set of piezoelectric actuators), and electrodes
114. Reflective device 110 includes a first reflective surface 116
and a second surface 118. Actuator 112 includes a support device
120 (e.g., a piezoelectric chuck, or the like) with extensions 122
(e.g., moveable extensions, such as piezoelectric pins, strips,
concentric rings, or other shapes) extending therefrom. Extensions
122 can be formed on support device 120 via lithography methods, or
the like, and can be on a micron scale (or any scale within the
realm of integrated circuit technology). In various embodiments,
extensions 122 can be formed from lead zirconate titanate (PZT),
zinc oxide (ZO), polyvinylidene fluoride (PVDF) polymer films, and
the like (hereinafter, the term piezoelectric and all possible
piezoelectric materials, for example PZT, ZO, PVDF, and the like,
will be referred to as "PZT").
An optional second support device 124 could be used to support
electrodes 114. Second support device 124 can include a connection
circuit (not shown) coupling controller 104 to electrodes 114.
Also, second support device 124 can be coupled to optional mounting
balls 126 (e.g., a ball grid array). In some embodiments, support
device 120 can have a conductive (e.g., nickel (Ni)) plated surface
128. Also, in some embodiments, electrodes 114 can be conductivly
(e.g, Ni) plated.
Using integrated circuit PZT technology for actuator 112 allows for
each individual actuator 122 (e.g., PZT pin) to be substantially
smaller compared to conventional discrete actuators. For example,
PZT pins 122 can be between about 1 to about 10 microns in width or
diameter, depending on their shape. This can result in a very high
density of PZT pins 122, which provides high resolution and
improved wavelength correction. For example, integrated circuit PZT
technology can allow for correction capability of one or a
combination of Standard Zernike higher order polynomial terms with
very little residual error. Also, by using the integrated circuit
PZT technique, high density can be achieved for virtually any
pattern of PZT pins 122.
Using piezoelectric technology allows for monitoring of movement of
each individual PZT pin 122 and each small area of reflective
surface 116 controlled by each PZT pin 122. This is because each
PZT pin 122 acts as a capacitance. A change in capacitance of PZT
pins 122 can be monitored, which indicates whether each individual
PZT pin 122 has expanded and/or contracted. Thus, system 100 can be
used to verify movement of reflective surface 116 based on
verifying movement of PZT pin 122. In some cases, a value of change
of capacitance can be equated to an actual distance moved of each
PZT pin 122, which can also be monitored.
A channel depth between each PZT pin 122 (e.g., height of each PZT
pin 122) can be adjusted during formation based on a desired amount
of decoupling between PZT pins 122 that is desired. For example, if
some parts of reflective surface 116 are best moved as larger
sections, while other parts are best moved as smaller sections, a
height of PZT pins in the various areas can be formed to reflect
this. The less height, the less decoupled, i.e., the more adjacent
PZT pins 122 are affected by adjacent pins. In contrast, the more
height, the more decoupled, i.e., very fine-tuning of reflective
surface 116 can result with very tall PZT pins 122.
Using integrated circuit PZT technology further allows for
formation of PZT pins 122 having variable spatial density (e.g., a
radial axis) and variable spatial patterns (radial, Cartesian,
asymmetric, etc.). This can lead to ever better wavefront
correction, particularly for higher order Zernike terms.
Curved Actuator and Deformable Optic Device
It is to be appreciated that deformable optics device 102 can be of
any shape, and not just planar, as would be known to a skilled
artisan.
For example, as shown in FIG. 2, a curved (e.g., an aspherical,
etc.) deformable optics device 202 can be used in a system 200
according to embodiments of the present invention. Deformable
optics device 202 can be coupled to a control system 204, which can
be coupled to a measuring system 206, as described above.
Deformable optics device 202 includes a reflective device 210
(e.g., a mirror), an actuator 212 (e.g., an integrated circuit set
of piezoelectric (PZT) actuators), and electrodes 214. Reflective
device 210 includes a first reflective surface 216 and a second
surface 218. Actuator 212 includes a support device 220 (e.g., a
PZT chuck, or the like) and extensions 222 (e.g., moveable
extensions, such as PZT pins) extending therefrom. Extensions 222
can be formed on support device 220 via lithography methods, or the
like.
An optional second support device 224 could be used to support
electrodes 214. Second support device 224 can include a connection
circuit coupled controller 204 to electrodes 214. Also, second
support device 224 can be coupled to optional mounting balls 126.
In some embodiments, support device 220 can have a nickel (Ni)
plated surface 228. Also, in some embodiments, electrodes 214 can
be Ni plated.
Example Actuator Extension Configuration
FIG. 3 shows an exemplary actuator extension configuration 300
according to embodiments of the present invention. Each asterisk
302 is located where an actuator element will interact with a
deformable optic (e.g., 102 or 202). This pattern includes a
variable density (e.g., spacing) and complex radial concentric
pattern. This is accomplished using the integrated circuit
actuators, which allows for variable density. Also, all actuators
can fall in a predefined plane (e.g., flat, curved, etc.) because
of using integrated circuit manufacturing technology. This type of
pattern was not available in conventional systems because of their
use of discrete actuators.
CONCLUSION
Example embodiments of the methods, circuits, and components of the
present invention have been described herein. As noted elsewhere,
these example embodiments have been described for illustrative
purposes only, and are not limiting. Other embodiments are possible
and are covered by the invention. Such embodiments will be apparent
to persons skilled in the relevant art(s) based on the teachings
contained herein. Thus, the breadth and scope of the present
invention should not be limited by any of the above-described
exemplary embodiments, but should be defined only in accordance
with the following claims and their equivalents.
* * * * *