U.S. patent application number 14/800625 was filed with the patent office on 2017-01-19 for systems and methods for inspecting an object.
The applicant listed for this patent is Applied Materials Israel, Ltd.. Invention is credited to Ido Almog, Ido Dolev, Haim Feldman.
Application Number | 20170016834 14/800625 |
Document ID | / |
Family ID | 57682331 |
Filed Date | 2017-01-19 |
United States Patent
Application |
20170016834 |
Kind Code |
A1 |
Feldman; Haim ; et
al. |
January 19, 2017 |
SYSTEMS AND METHODS FOR INSPECTING AN OBJECT
Abstract
A system, including an illumination module that comprises (a) a
first traveling lens acousto-optic device; (b) a light source for
illuminating the first traveling lens to provide an input beam that
propagates along a first direction; (c) illumination optics for
outputting an output beam that scans the object at a second
direction; a detection unit; and a collection module for collecting
a collected beam from the object, wherein the collected beam
propagates along a third direction; and optically manipulating the
collected beam to provide a counter-scan beam is directed towards
the detection unit and has a focal point that is positioned at a
same location regardless of the propagation of the collected beam
along the third direction.
Inventors: |
Feldman; Haim; (Nof-Ayalon,
IL) ; Dolev; Ido; (Rehovot, IL) ; Almog;
Ido; (Rehovot, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials Israel, Ltd. |
Rehovot |
|
IL |
|
|
Family ID: |
57682331 |
Appl. No.: |
14/800625 |
Filed: |
July 15, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 26/124 20130101;
G01N 2021/95676 20130101; G01N 21/956 20130101; G02B 26/123
20130101; G01N 21/9501 20130101; G03F 1/84 20130101 |
International
Class: |
G01N 21/95 20060101
G01N021/95; G02B 26/12 20060101 G02B026/12 |
Claims
1. A system for inspecting an object, the system comprising: an
illumination module that comprises (a) a first traveling lens
acousto-optic device that is configured to generate a first
traveling lens that propagates through an active region of the
first traveling lens acousto-optic device; (b) a light source that
is configured to illuminate the first traveling lens to provide an
input beam that propagates along a first direction; (c)
illumination optics that are configured to receive the input beam
and to output, in response to the input beam, an output beam that
scans the object along a second direction; a detection unit; and a
collection module that is configured to (a) collect a collected
beam from the object, wherein the collected beam propagates along a
third direction; and (b) optically manipulate the collected beam to
provide a counter-scan beam that is directed towards the detection
unit and has a focal point that is positioned at a same location
regardless of the propagation of the collected beam along the third
direction.
2. The system according to claim 1 wherein the collection module is
configured to counter-scan the collected beam to provide the
counter-scan beam.
3. The system according to claim 1 wherein the collection module
comprises a second traveling lens acousto-optic device that is
configured to generate a second traveling lens that propagates
through an active region of the second traveling lens acousto-optic
device along a fourth direction.
4. The system according to claim 3 wherein the illumination module
comprises a first scan lens and the collection module comprises a
mirror, a second scan lens and an aperture; and wherein the mirror,
the second scan lens and the aperture are positioned between the
second traveling lens acousto-optic device and the detection
unit.
5. The system according to claim 4 wherein the traveling lens
propagates through the active region in synchronization with the
propagation of the collected beam along the third direction.
6. The system according to claim 5 wherein an output beam of the
second traveling lens acousto-optic device impinges on the mirror
and is directed by the mirror towards the second scan lens to
provide a mirror output beam that propagates along a fifth
direction while maintaining a fixed angle in relation to the second
scan lens; and wherein the second scan lens is configured to
receive the mirror output beam to provide the counter-scan
beam.
7. The system according to claim 6 wherein the illumination module
comprises a telescope lens, a beam splitter and an objective lens;
wherein the collection module comprises the beam splitter, the
objective lens and a tube lens; wherein the telescope lens is
positioned between the beam splitter and the first scan lens; and
wherein the tube lens is positioned between the beam splitter and
the second traveling lens acousto-optic device.
8. The system according to claim 1, wherein the collection module
optically manipulates the collected beam to provide an intermediate
beam that rotates counterclockwise; and wherein the collection
module comprises detection unit optics and a rotating polygon
mirror that is configured to rotate in a clockwise direction in
synchronicity with the counterclockwise rotation of the
intermediate beam and to reflect, during multiple points in time,
towards the detection unit optics the output beam.
9. The system according 8 wherein the illumination module comprises
a first scan lens, a telescope lens, a beam splitter and an
objective lens; wherein the collection module comprises the beam
splitter, the objective lens, a second scan lens and an aperture;
and wherein the beam splitter directs the intermediate beam towards
the rotating polygon mirror.
10. The system according to claim 1, wherein the collection module
optically manipulates the collected beam to provide an intermediate
beam that rotates counterclockwise; and wherein the collection
module comprises detection unit optics and a rotating polygon
mirror that is configured to rotate in a clockwise direction in
synchronicity with the counterclockwise rotation of the
intermediate beam and to reflect, during multiple points in time,
towards the detection unit optics the output beam.
11. The system according 10 wherein the illumination module
comprises a first scan lens, a telescope lens, a beam splitter and
an objective lens; wherein the collection module comprises the beam
splitter, the objective lens, a second scan lens and an aperture;
and wherein the beam splitter directs the intermediate beam towards
the rotating polygon mirror.
12. The system according to claim 1, wherein the first traveling
lens acousto-optic device is configured to generate a set of first
traveling lenses that propagates through the active region of the
first traveling lens acousto-optic device; wherein the light source
is configured to illuminate the set of first traveling lenses to
provide a set of input beams that propagates along the first
direction; wherein the illumination optics are configured to
receive the set of input beams and to output, in response to the
set of input beams, a set of output beams that scans the object
along the second direction ; wherein the collection module is
configured to (a) collect a set of collected beams from the object,
wherein the set of collected beams propagates along a third
direction; and (b) optically manipulate the collected beams to
provide a set of counter-scan beams that is directed towards the
detection unit; and wherein each counter-scan beam of the set of
counter-scan beams has a focal point that is positioned at a same
location regardless of the propagation of the set of collected
beams along the third direction.
13. The system according to claim 12 wherein the collection module
comprises a second traveling lens acousto-optic device that is
configured to generate a set of second traveling lenses that
propagates through the active region of the second traveling lens
acousto-optic device along the fourth direction.
14. The system according to claim 12, wherein the third direction
is clockwise; wherein the collection module comprises detection
unit optics and a rotating polygon mirror that is configured to
rotate in a counterclockwise direction in synchronicity with the
clockwise propagation of the set of collected beams and to reflect,
during multiple points in time, towards the detection unit optics
the set of output beams.
15. A method for inspecting an object, the method comprises:
generating, by a first traveling lens acousto-optic device, a
traveling lens that propagates through an active region of the
traveling lens acousto-optic device; illuminating, by an
illumination unit, the traveling lens to provide an input beam that
propagates along a first direction; converting the input beam into
an output beam that scans the object at a second direction;
collecting a collected beam from the object, wherein the collected
beam propagates along a third direction; optically manipulating the
collected beam to provide a counter -scan beam that is directed
towards the detection unit and has a focal point that is positioned
at a same location regardless of the propagation of the collected
beam along the third direction; and detecting the counter-scan beam
by the detection unit.
Description
BACKGROUND OF THE INVENTION
[0001] A variety of systems are used for automated inspection of
semiconductor wafers, in order to detect defects, particles and/or
patterns on the wafer surface as part of a quality assurance
process in semiconductor manufacturing processes. It is a goal of
current inspection systems to have high resolution and high
contrast imaging in order to provide the reliability and accuracy
demanded in sub-micron semiconductor manufacturing processes.
However, it is also important to have a high-speed process that
permits a large volume throughput so that the quality and assurance
processes do not become a bottleneck in the wafer production
process. Accordingly, the optical inspection systems must use
shorter wave lengths, higher numerical aperture optics and high
density image capture technology in order to enable the processing
of data from such systems at sufficiently high rates that will
satisfy the desired product throughput requirements.
[0002] A conventional imaging architecture that is used in wafer
inspection systems at this time utilizes multi spot scanning laser
for high-speed imaging. However, the data rates achievable by such
architectures are limited by the physical constraints that arise
due to limitations in the speed and quality of the single laser
beam, the applicable optical system and related detection devices.
For example, the single laser acting as a point light source is
focused as a spot onto the object under inspection and is scanned
across the surface of the object, which may be stationary or moved
on a stage mechanism in coordination with the scan. The reflected
light from the object is then imaged onto a detector, which
generates pixel data from the scanning process.
[0003] The detector may be a photo multiplier detector (PMT) or a
CCD array, whose individual elements are positioned to receive the
reflected light as the beam is scanned and be read our serially, in
a conventional fashion. While a high resolution may be obtained
from such point source illumination, the requirement to scan each
point in the field in order to construct a viewable image subjects
the system to a limitation on its throughput.
[0004] The detector has to image the entire scan path of the spot
and may collect stray light or other noises. The scanning of the
single laser beam may be accomplished by a rotating mirror system,
as seen in U.S. Pat. No. 5,065,008 or an acousto-optic cell.
However, these single spot scanning architecture necessarily have a
limited speed and are possibly subject to scan aberrations, low
illumination brightness and potential thermal damage to the object
when high brightness laser sources are used. The high data rates
required to inspect the submicron structures of current
semiconductor products cannot be achieved, even when a stage-type
scanning system is used that moves the object relative to a fixed
illumination and image location while a synchronized scanning
pattern is produced by moving the single point of light over an
area at the fixed location.
[0005] One way to increase the throughput of the inspection is to
scan the object with a rectangular grid of beams, wherein the scan
axis is parallel to the columns of the grid.
[0006] When the object is scanned with multiple beams the detector
may also suffer from cross talk between the multiple beams.
[0007] Accordingly, there is a need for an object scanning system
that will improve object throughput, while maintaining or even
improving the reliability and accuracy of the data collected during
the scan of an object, whether in a stationary or stage-type
system.
SUMMARY
[0008] According to an embodiment of the invention there may be
provided a system for inspecting an object, the system may include
an illumination module that may include (a) a first traveling lens
acousto-optic device that may be configured to generate a first
traveling lens that propagates through an active region of the
first traveling lens acousto-optic device; (b) a light source that
that may be configured to illuminate the first traveling lens to
provide an input beam that propagates along a first direction; (c)
illumination optics that may be configured to receive the input
beam and to output, in response to the input beam, an output beam
that scans the object at a second direction; a detection unit; and
a collection module that may be configured to (a) collect a
collected beam from the object, the collected beam propagates along
a third direction; and (b) optically manipulate the collected beam
to provide a counter-scan beam is directed towards the detection
unit and has a focal point that is positioned at a same location
regardless of the propagation of the collected beam along the third
direction.
[0009] The collection module may be configured to counter-scan the
collected beam to provide the output beam.
[0010] The collection module may include a second traveling lens
acousto-optic device that may be configured to generate a second
traveling lens that propagates through an active region of the
second traveling lens acousto-optic device along a fourth
direction.
[0011] The illumination module may include a first scan lens and
the collection module may include a mirror, and a second scan lens
and an aperture; and the mirror, the second scan lens and the
aperture are positioned between the second traveling lens
acousto-optic device and the detection unit.
[0012] The traveling lens may propagate through the active region
in synchronization with the propagation of the collected beam along
the third direction.
[0013] An output beam of the second traveling lens acousto-optic
device may impinge on the mirror and may be directed by the mirror
towards the second scan lens to provide a mirror output beam that
propagates along a fifth direction while maintaining a fixed angle
in relation to the second scan lens; and the second scan lens may
be configured to receive the mirror output beam to provide the
counter-scan beam.
[0014] The illumination module may include a telescope lens, a beam
splitter and an objective lens; the collection module may include
the beam splitter, the objective lens and a tube lens; the
telescope lens is positioned between the beam splitter and the
first scan lens; and the tube lens is positioned between the beam
splitter and the second traveling lens acousto-optic device.
[0015] The collection module may optically manipulates the
collected beam to provide an intermediate beam that rotates
counterclockwise; and the collection module may include detection
unit optics and a rotating polygon mirror that may be configured to
rotate in a clockwise direction in synchronicity with the
counterclockwise rotation of the intermediate beam and to reflect,
during multiple points in time, and towards the detection unit
optics the output beam.
[0016] The illumination module may include a first scan lens, a
telescope lens, a beam splitter and an objective lens; the
collection module may include the beam splitter, the objective
lens, a second scan lens and an aperture; and the beam splitter
directs the intermediate beam towards the rotating polygon
mirror.
[0017] The collection module may optically manipulate the collected
beam to provide an intermediate beam that rotates counterclockwise;
and the collection module may include detection unit optics and a
rotating polygon mirror that may be configured to rotate in a
clockwise direction in synchronicity with the counterclockwise
rotation of the intermediate beam and to reflect, during multiple
points in time, and towards the detection unit optics the output
beam.
[0018] The illumination module may include a first scan lens, a
telescope lens, a beam splitter and an objective lens; the
collection module may include the beam splitter, the objective
lens, a second scan lens and an aperture; and the beam splitter
directs the intermediate beam towards the rotating polygon
mirror.
[0019] The traveling lens acousto-optic device may be configured to
generate a set of first traveling lenses that propagates through
the active region of the first traveling lens acousto-optic device;
the light source may be configured to illuminate the set of first
traveling lenses to provide a set of input beams that propagates
along the first direction; the illumination optics may be
configured to receive the set of input beams and to output, in
response to the set of input beams, a set of output beams that
scans the object along the second direction ; the collection module
may be configured to (a) collect a set of collected beam from the
object, the set of collected beam propagates along a third
direction; and (b) optically manipulate the collected beam to
provide a set of counter-scan beams that is directed towards the
detection unit; and each counter-scan beam of the set of
counter-scan beams has a focal point that is positioned at a same
location regardless of the propagation of the set of collected
beams along the third direction.
[0020] The collection module may include a second traveling lens
acousto-optic device that may be configured to generate a set of
second traveling lenses that propagates through the active region
of the second traveling lens acousto-optic device along the fourth
direction.
[0021] The illumination module may include a first scan lens and
the collection module may include a mirror, a set of second scan
lenses and a set of apertures, the mirror, the set of second scan
lenses and the set of apertures are positioned between the second
traveling lens acousto-optic device and the detection unit; the
detection unit may include a set of detectors; and each detector is
associated with a second scan lens and an aperture.
[0022] The third direction may be counterclockwise. The collection
module may include detection unit optics and a rotating polygon
mirror that may be configured to rotate in a clockwise direction in
synchronicity with the counterclockwise propagation of the set of
collected beams and to reflect, during multiple points in time, and
towards the detection unit optics the set of output beams.
[0023] The third direction may be clockwise. The collection module
may include detection unit optics and a rotating polygon mirror
that may be configured to rotate in a counterclockwise direction in
synchronicity with the clockwise propagation of the set of
collected beams and to reflect, during multiple points in time, and
towards the detection unit optics the set of output beams.
[0024] According to an embodiment of the invention there may be
provided a method for inspecting an object, the method may include
generating, by a first traveling lens acousto-optic device, a
traveling lens that propagates through an active region of the
traveling lens acousto-optic device; illuminating, by an
illumination unit, the traveling lens to provide an input beam that
propagates along a first direction; converting the input beam an
output beam that scans the object at a second direction; collecting
a collected beam from the object, the collected beam propagates
along a third direction; optically manipulating the collected beam
to provide a counter-scan beam that is directed towards the
detection unit and has a focal point that is positioned at a same
location regardless of the propagation of the collected beam along
the third direction; and detecting the counter-scan beam by the
detection unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The subject matter regarded as the invention is particularly
pointed out and distinctly claimed in the concluding portion of the
specification. The invention, however, both as to organization and
method of operation, together with objects, features, and
advantages thereof, may best be understood by reference to the
following detailed description when read with the accompanying
drawings in which:
[0026] FIG. 1 illustrates a system and an object according to an
embodiment of the invention;
[0027] FIG. 2 illustrates a system and an object according to an
embodiment of the invention;
[0028] FIG. 2 illustrates beams and masking units according to
various embodiments of the invention;
[0029] FIG. 3 illustrates a system and an object according to an
embodiment of the invention;
[0030] FIG. 4 illustrates a system and an object according to an
embodiment of the invention;
[0031] FIG. 5 illustrates a system and an object according to an
embodiment of the invention;
[0032] FIG. 6 illustrates a method according to an embodiment of
the invention;
[0033] FIG. 7 illustrates a step of a method according to an
embodiment of the invention;
[0034] FIG. 8 illustrates a step of a method according to an
embodiment of the invention; and
[0035] FIG. 9 illustrates a method according to an embodiment of
the invention.
[0036] It will be appreciated that for simplicity and clarity of
illustration, elements shown in the figures have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements may be exaggerated relative to other elements for clarity.
Further, where considered appropriate, reference numerals may be
repeated among the figures to indicate corresponding or analogous
elements.
DETAILED DESCRIPTION OF THE DRAWINGS
[0037] In the following detailed description, numerous specific
details are set forth in order to provide a thorough understanding
of the invention. However, it will be understood by those skilled
in the art that the present invention may be practiced without
these specific details. In other instances, well-known methods,
procedures, and components have not been described in detail so as
not to obscure the present invention.
[0038] The subject matter regarded as the invention is particularly
pointed out and distinctly claimed in the concluding portion of the
specification. The invention, however, both as to organization and
method of operation, together with objects, features, and
advantages thereof, may best be understood by reference to the
following detailed description when read with the accompanying
drawings.
[0039] It will be appreciated that for simplicity and clarity of
illustration, elements shown in the figures have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements may be exaggerated relative to other elements for clarity.
Further, where considered appropriate, reference numerals may be
repeated among the figures to indicate corresponding or analogous
elements.
[0040] Because the illustrated embodiments of the present invention
may for the most part, be implemented using electronic components
and circuits known to those skilled in the art, details will not be
explained in any greater extent than that considered necessary as
illustrated above, for the understanding and appreciation of the
underlying concepts of the present invention and in order not to
obfuscate or distract from the teachings of the present
invention.
[0041] Any reference in the specification to a method should be
applied mutatis mutandis to a system capable of executing the
method and should be applied mutatis mutandis to a non-transitory
computer readable medium that stores instructions that once
executed by a computer result in the execution of the method.
[0042] Any reference in the specification to a system should be
applied mutatis mutandis to a method that may be executed by the
system and should be applied mutatis mutandis to a non-transitory
computer readable medium that stores instructions that may be
executed by the system.
[0043] Any reference in the specification to a non-transitory
computer readable medium should be applied mutatis mutandis to a
system capable of executing the instructions stored in the
non-transitory computer readable medium and should be applied
mutatis mutandis to method that may be executed by a computer that
reads the instructions stored in the non-transitory computer
readable medium.
[0044] The following detailed description is of exemplary
embodiments of the invention but the invention is not limited
thereto, as modifications and supplemental structures may be added,
as would be apparent to those skilled in the art. In particular,
but without limitation, while an exemplary embodiment may be
disclosed with regard to the inspection of a subject surface by
detecting reflected light using a light source and detecting unit
that are disposed on a common side of an object (a "reflective
system"), it would be readily apparent to one skilled in the art
that the teachings are readily adaptable to the inspection of an
object by detecting transmitted light with a detecting unit that is
on a side of an object opposite to that of the light source (a
"transmissive system").
[0045] While the reflective system and the transmissive system
differ, for one example by the absence of a beam splitter in the
transmissive system, the principles of the present invention are
applicable to both types of systems. As would be understood by one
skilled in the art, both types of systems may be utilized
separately or together in the inspection of an object, in
accordance with the present invention.
[0046] FIG. 1 illustrates system 100 and object 10 according to an
embodiment of the invention.
[0047] Without limitation and only by example, object 10 may be any
semiconductor product having multiple semiconductor devices
thereon, at any of several steps of manufacture, or may be a mask,
reticule or the like used in a manufacturing process, where such
object must be inspected for defects, foreign objects or pattern
accuracy. It is desirable in such systems to identify with high
accuracy and reliability the size, location and type of structure,
defect or object that appears on the object surface. It also is
desirable to undertake such identification at high speed, in order
to minimize the delay in the manufacturing process that is provided
to the inspection and quality assurance steps.
[0048] System 100 is illustrated as including an illumination
module 110, collection module 130, detection unit 124 that includes
detector 124(1), image processor 132, mechanical stage 150 and
controller 136.
[0049] Illumination module 110 includes first traveling lens
acousto-optic device 107, light source 104 and illumination optics
112.
[0050] First traveling lens acousto-optic device 107 is configured
to generate a first traveling lens 109(1) that propagates through
an active region of the first traveling lens acousto-optic
device.
[0051] The traveling lens acousto-optic device 107 can resemble the
traveling lens of acousto-optic device illustrated in U.S. Pat.
Nos. 6,809,808, 7,053,395, 6,943,898, 6,853,475, 7528940, and
7,002,695--all being incorporated herein by reference.
[0052] The Bragg cell 108 may include a single crystal that is
effective to generate one or more traveling lenses in response to
one or more radio frequency chirps.
[0053] The single crystal in the device may be composed of a
material that is compatible with a ultraviolet (UV) light source,
preferably having an acousto-optic medium made of Al3O2, GaAs or
TeO.sub.2 glass, although other known materials having UV
compatibility, may be used. The crystal may have an anti-reflective
coating on each major side that rated at less than 0.5% for both
sides. The traveling lens acousto-optic device may operate in a
longitudinal acoustic mode at a wavelength of 266 nm and at a
center frequency of 200 MHz with a bandwidth of 130 MHz. RF power
may be less than 3.0 watts. The active aperture of the device may
be 1.0 mm "H" by 60 mm "L" in one exemplary embodiment.
[0054] First traveling lens acousto-optic device 107 includes
transducer 106 and Bragg cell 108 that acts as the active region of
the traveling lens acousto-optic device.
[0055] Light source 104 is configured to illuminate the first
traveling lens to provide an input beam 22 that propagates along a
first direction.
[0056] Illumination optics 112 is configured to receive the input
beam and to output, in response to the input beam, an output beam
52 that scans the object at a second direction.
[0057] Collection module 130 is configured to (a) collect a
collected beam from the object, wherein the collected beam
propagates along a third direction; (b) optically manipulate the
collected beam to provide a counter-scan beam is directed towards
the detection unit and has a focal point that is positioned at a
same location regardless of the propagation of the collected beam
along the third direction.
[0058] The phrase "optically manipulate" may include using one or
more optical components to change an optical parameter (such as an
optical path) of an optical beam.
[0059] In FIG. 1 the collected beam overlaps with output beam 52
and the second direction equals the third direction. It is noted
that the collected beam may be oriented to the output beam 52 and
that the second direction may differ from the third direction.
[0060] The propagation of the collected beam along the third
direction may cause the counter-scan beam 92 to changes its angle
in relation to the detection unit 124 but does not change the
location of the focal plane of the counter-scan beam. In other
words--the position of the counter-scan beam 92 on the detector
remains the same.
[0061] It is noted that although FIG. 1 illustrates a single input
beam, a single output beam and a single counter-scan beam, system
100 may be configured to generate a set of input beams, a set of
output beams and a set of counter-scan beams. Each set may include
two or more beams. Using a set of multiple output beams increases
the throughput of system 100.
[0062] FIG. 2 illustrates system 101 and object 10 according to an
embodiment of the invention.
[0063] System 101 is illustrated as including an illumination
module 110, collection module 130, detection unit 124, image
processor 132 and controller 136.
[0064] Illumination module 110 includes first traveling lens
acousto-optic device 107, light source 104 and illumination optics
112.
[0065] Light source 104 includes laser 102 and beam expander 103.
Laser 102 may be replaced by another radiation source.
[0066] Illumination optics 112 includes scan lens 114 that is
followed by telescope lens 116. Telescope lens 116 is followed by
beam splitter 118. Beam splitter 118 is followed by objective lens
120.
[0067] Collection module 130 includes objective lens 120, beam
splitter 118, tube lens 122, second traveling lens acousto-optic
device 127, mirror 134, a set of second scan lenses 138, a set of
apertures 142 and a detection unit 124 that includes a set of
detectors that includes detectors 124(1), 124(2) and 124(3).
[0068] Second traveling lens acousto-optic device 127 includes
transducer 126 and Bragg cell 128 that acts as the active region of
the traveling lens acousto-optic device.
[0069] Second traveling lens acousto-optic device 127 is configured
to generate a set of second traveling lenses 129(1), 129(2) and
129(3) that propagate through an active region of the second
traveling lens acousto-optic device.
[0070] A set of input beams includes input beams 21, 22 and 23 that
exit from first traveling lens acousto-optic device 107 and impinge
on scan lens 114.
[0071] Scan lens 114 outputs a set of first intermediate beams
includes first intermediate beams 31, 32 and 33 that impinge on
telescope lens 116.
[0072] Telescope lens 116 outputs a set of second intermediate
beams that includes second intermediate beams 41, 42 and 43 that
pass through beam splitter 118 and impinge on objective lens
120.
[0073] Objective lens 120 outputs a set of output beams that
includes output beams 51, 52 and 53 that may scan the object
10.
[0074] Objective lens 120 collects a set of collected beams (in
FIG. 2 the set of output beams overlap output beams) that include
collected beams that impinge on beam splitter 118 and are directed
as a set of third intermediate beams on tube lens 122. The set of
third intermediate beams includes third intermediate beams 61, 62
and 63.
[0075] Tube lens 122 outputs a set of fourth intermediate beams
that includes fourth intermediate beams 71, 72 and 73 that
illuminate the set of second traveling lenses to provide a set of
fifth intermediate beams that includes fifth intermediate beams 81,
82 and 83.
[0076] Fifth intermediate beams 81, 82 and 83 impinge on mirror 134
that outputs a set of sixth intermediate beams that includes sixth
intermediate beams 81', 82' and 83'. The orientation of sixth
intermediate beams 81', 82' and 83' does not change.
[0077] Sixth intermediate beams 81', 82' and 83' impinge on the set
of second scan lenses 138.
[0078] The set of second scan lenses 138 outputs a set of
counter-scan beams that include counter-scan beams 91, 92 and 92
onto detection unit 124.
[0079] FIG. 3 illustrates system 101, object 10 and propagation
directions of various beams and traveling lenses according to an
embodiment of the invention.
[0080] Various sets of beams propagate from optical component of
the system 101 to the other. FIG. 3 illustrates the changes in the
paths of the sets of beam over time--due to the propagation of the
set of first traveling lenses within first traveling lens
acousto-optic device 107.
[0081] In FIG. 3 it is assumed that first traveling lenses 109(1),
109(2) and 109(3) and input beams 21, 22 and 23 propagate along a
first direction 201--to the right.
[0082] First intermediate beams 31, 32 and 33 of the set of first
intermediate beams rotate clockwise 202.
[0083] Second intermediate beams 41, 42 and 43 of the set of second
intermediate beams rotate clockwise 203.
[0084] Output beams 51, 52 and 52 and collected beams (overlap
output beams 51, 52 and 53) propagate along second direction
204--to the right.
[0085] Third intermediate beams 61, 62 and 63 rotate clockwise
205.
[0086] Fourth intermediate beams 71, 72 and 73 propagate along a
fourth direction 206--downwards.
[0087] Set of second traveling lenses 129(1), 129(2) and 129(3)
propagate downwards 207.
[0088] Fifth intermediate beams 81, 82 and 83 propagate along a
fifth direction 208--to the right.
[0089] Counter-scan beams 91, 92 and 92 rotate clockwise 209 but
the focal point of counter-scan beams 91, 92 and 93 does not
move.
[0090] FIG. 4 illustrates system 105 and object 10 according to an
embodiment of the invention.
[0091] System 105 is illustrated as including an illumination
module 110, collection module 130, detection unit 124, image
processor 132 and controller 136.
[0092] Illumination module 110 includes first traveling lens
acousto-optic device 107, light source 104 and illumination optics
112.
[0093] Light source 104 includes laser 102 and beam expander 103.
Laser 102 may be replaced by another radiation source.
[0094] Illumination optics 112 includes scan lens 114 that is
followed by telescope lens 116. Telescope lens 116 is followed by
beam splitter 118. Beam splitter 118 is followed by objective lens
120.
[0095] Collection module 130 includes objective lens 120, beam
splitter 118, rotating polygon mirror 160, a set of second scan
lenses 138, a set of apertures 142 and a detection unit 124 that
includes a set of detectors that includes detectors 124(1), 124(2)
and 124(3).
[0096] A set of input beams includes input beams 21, 22 and 23 that
exit from first traveling lens acousto-optic device 107 and impinge
on scan lens 114.
[0097] Scan lens 114 outputs a set of first intermediate beams
includes first intermediate beams 31, 32 and 33 that impinge on
telescope lens 116.
[0098] Telescope lens 116 outputs a set of second intermediate
beams that includes second intermediate beams 41, 42 and 43 that
pass through beam splitter 118 and impinge on objective lens
120.
[0099] Objective lens 120 outputs a set of output beams that
includes output beams 51, 52 and 53 that may scan the object
10.
[0100] Objective lens 120 collects a set of collected beams (in
FIG. 2 the set of output beams overlap output beams) that include
collected beams that impinge on beam splitter 118 and are directed
as a set of third intermediate beams that includes third
intermediate beams 61, 62 and 62 onto rotating polygon mirror
160.
[0101] The third intermediate beams 61, 62 and 63 rotate clockwise
as a result of the propagation of the set of first traveling lenses
within first traveling lens acousto-optic device 107.
[0102] Rotating polygon mirror 160 (especially the facets of the
rotating polygon mirror) rotates in an opposite direction (for
example counterclockwise) to the direction of rotation of third
intermediate beams 61, 62 and 63 and in synchronization with the
rotation of third intermediate beams 61, 62 and 63--thereby
countering the rotation of third intermediate beams 61, 62 and
63.
[0103] The rotating polygon mirror 160 (especially the facets of
the rotating polygon mirror) reflects towards the set of second
scan lenses 138 a set of rotating polygon mirror output beams that
includes rotating polygon mirror output beams 81'', 82'' and
83''.
[0104] When the facets of the rotating polygon mirror 160 reflect
the third intermediate beams 61, 62 and 63--the rotating polygon
mirror output beams 81'', 82'' and 83'' are stationary.
[0105] The system 105 may ignore the rotating polygon mirror output
beams 81'', 82'' and 83'' that are reflected by the edges of the
rotating polygon mirror 160.
[0106] The rotating polygon mirror 160 is illustrates as including
four facets. It is noted that the rotating polygon mirror 160 may
include more facets than four. For example--the rotating polygon
mirror 160 may have 20 facets, 30 facets and even more. An increase
in the number of facets of the rotating polygon mirror 160
increases the stability of the rotating polygon mirror output beams
81'', 82'' and 83''.
[0107] The set of second scan lenses 138 outputs a set of
counter-scan beams that includes counter-scan beams 91, 92 and 92
onto the detection unit 124.
[0108] FIG. 5 illustrates system 105, object 10 and propagation
directions of various beams and traveling lenses according to an
embodiment of the invention.
[0109] Various sets of beams propagate from optical component of
the system 101 to the other. FIG. 5 illustrates the changes in the
paths of the sets of beam over time--due to the propagation of the
set of first traveling lenses within first traveling lens
acousto-optic device 107.
[0110] In FIG. 5 it is assumed that first traveling lenses 109(1),
109(2) and 109(3) and input beams 21, 22 and 23 propagate along a
first direction 201--to the right.
[0111] First intermediate beams 31, 32 and 33 of the set of first
intermediate beams rotate clockwise 202.
[0112] Second intermediate beams 41, 42 and 43 of the set of second
intermediate beams rotate clockwise 203.
[0113] Output beams 51, 52 and 52 and collected beams (overlap
output beams 51, 52 and 53) propagate along second direction
204--to the right.
[0114] Third intermediate beams 61, 62 and 63 rotate clockwise
205.
[0115] Rotating polygon mirror output beams 81'', 82'' and 83'' are
static (when reflected by the facets of the rotating polygon mirror
160).
[0116] Counter-scan beams 91, 92 and 92 are static.
[0117] FIG. 6 is a flow chart illustrating method 200 for
inspecting an object according to an embodiment of the present
invention.
[0118] Method 200 may be executed by system 100 of FIG. 1, system
101 of FIG. 2 and system 105 of FIG. 4.
[0119] It is noted that various steps of method 200 at least
partially overlap and that their order as illustrated in FIG. 6 is
not mandatory.
[0120] Method 200 may start by steps 210 and 215.
[0121] Step 210 may include introducing a mechanical movement
between the object and optics along a mechanical movement
direction. Step 210 may be executed in parallel to steps 215, 220,
230, 240, 250 and 260.
[0122] Step 215 may include generating, by a first traveling lens
acousto-optic device, a traveling lens that propagates through an
active region of the traveling lens acousto-optic device.
[0123] Step 215 may be followed by step 220 of illuminating, by an
illumination unit, the traveling lens to provide an input beam that
propagates along a first direction.
[0124] Step 220 may be followed by step 230 of converting the input
beam an output beam that scans the object at a second direction.
The second direction may be oriented to the mechanical movement
direction or may be parallel to the mechanical movement
direction.
[0125] Step 230 may be followed by step 240 of collecting a
collected beam from the object, wherein the collected beam
propagates along a third direction.
[0126] Step 240 may be followed by step 250 of optically
manipulating the collected beam to provide a counter-scan beam that
is directed towards the detection unit and has a focal point that
is positioned at a same location regardless of the propagation of
the collected beam along the third direction.
[0127] Step 250 may be followed by step 260 of detecting the
counter-scan beam by the detection unit.
[0128] FIG. 7 illustrates step 250 of method 200 according to an
embodiment of the invention.
[0129] Step 250 may include a sequence of steps 251, 252, 252, 254
and 255.
[0130] Step 251 may include directing, by a beam splitter, the
collected beam to provide a third intermediate beam that impinges
on a tube lens.
[0131] Step 252 may include outputting, by the tube lens, a fourth
intermediate beam that propagates along a fourth direction.
[0132] Step 253 may include illuminating, by the fourth
intermediate beam, a second traveling lens that propagates in
synchronicity with the fourth intermediate beam to provide a fourth
intermediate beam.
[0133] Step 254 may include reflecting the fourth intermediate
beam, by a mirror, towards a second scan lens.
[0134] Step 255 may include outputting from the second scan lens
the counter-scan beam.
[0135] FIG. 8 illustrates step 250 of method 200 according to an
embodiment of the invention.
[0136] Step 250 may include a sequence of steps 256, 257 and
258.
[0137] Step 256 may include directing, by a beam splitter, the
collected beam to provide a third intermediate beam that impinges
on a rotating polygon mirror. While the third intermediate rotates
along a first rotation direction the rotating polygon mirror
rotates at a same rotational rate but along an opposite rotation
direction thereby countering the rotation of the third intermediate
beam.
[0138] For example--when the first rotation direction is clockwise
the second rotation direction is counterclockwise. Yet for another
example--when the first rotation direction is counterclockwise the
second rotation direction is clockwise
[0139] Step 257 may include reflecting, by facets of the rotating
polygon mirror, the third intermediate beam to provide a rotating
polygon mirror output beam that is static when reflected by the
facets of rotating polygon mirror.
[0140] Step 258 includes outputting from the second scan lens the
counter-scan beam.
[0141] FIG. 9 is a flow chart illustrating method 200' for
inspecting an object according to an embodiment of the present
invention.
[0142] Method 200' may be executed by system 100 of FIG. 1, system
101 of FIG. 2 and system 105 of FIG. 4.
[0143] It is noted that various steps of method 200 at least
partially overlap and that their order as illustrated in FIG. 9 is
not mandatory.
[0144] Method 200' may start by steps 210' and 215'.
[0145] Step 210' may include introducing a mechanical movement
between the object and optics along a mechanical movement
direction. Step 210' may be executed in parallel to steps 215',
220', 230', 240', 250' and 260.
[0146] Step 215' may include generating, by a first traveling lens
acousto-optic device, a set of traveling lenses that propagates
through an active region of the traveling lens acousto-optic
device.
[0147] Step 215' may be followed by step 220' of illuminating, by
an illumination unit, the set of traveling lenses to provide a set
of input beams that propagates along a first direction.
[0148] Step 220' may be followed by step 230' of converting the set
of input beams to a set of output beams that scans the object at a
second direction. The second direction may be oriented to the
mechanical movement direction or may be parallel to the mechanical
movement direction.
[0149] Step 230' may be followed by step 240' of collecting a set
of collected beams from the object, wherein the set of collected
beams propagates along a third direction.
[0150] Step 240' may be followed by step 250' of optically
manipulating the set of collected beams to provide a set of
counter-scan beams that is directed towards the detection unit and
wherein each one of the set of counter-scan beams has a focal point
that is positioned at a same location regardless of the propagation
of the set of collected beams along the third direction.
[0151] Step 250' may be followed by step 260' of detecting the set
of counter-scan beams by the detection unit.
[0152] In method 200 and method 200' the detection of the set of
counter scan beams may be followed by generating detection signals
by the detection unit and executing at least one step out of
storing the detection signals, processing the detection signals to
provide an inspection result and transmitting the detection
signals.
[0153] In the foregoing specification, the invention has been
described with reference to specific examples of embodiments of the
invention. It will, however, be evident that various modifications
and changes may be made therein without departing from the broader
spirit and scope of the invention as set forth in the appended
claims.
[0154] Moreover, the terms "front," "back," "top," "bottom ,"
"over," "under" and the like in the description and in the claims,
if any, are used for descriptive purposes and not necessarily for
describing permanent relative positions. It is understood that the
terms so used are interchangeable under appropriate circumstances
such that the embodiments of the invention described herein are,
for example, capable of operation in other orientations than those
illustrated or otherwise described herein.
[0155] The connections as discussed herein may be any type of
connection suitable to transfer signals from or to the respective
nodes, units or devices, for example via intermediate devices.
Accordingly, unless implied or stated otherwise, the connections
may for example be direct connections or indirect connections. The
connections may be illustrated or described in reference to being a
single connection, a plurality of connections, unidirectional
connections, or bidirectional connections. However, different
embodiments may vary the implementation of the connections. For
example, separate unidirectional connections may be used rather
than bidirectional connections and vice versa. Also, plurality of
connections may be replaced with a single connection that transfers
multiple signals serially or in a time multiplexed manner.
Likewise, single connections carrying multiple signals may be
separated out into various different connections carrying subsets
of these signals. Therefore, many options exist for transferring
signals.
[0156] Although specific conductivity types or polarity of
potentials have been described in the examples, it will be
appreciated that conductivity types and polarities of potentials
may be reversed.
[0157] Each signal described herein may be designed as positive or
negative logic. In the case of a negative logic signal, the signal
is active low where the logically true state corresponds to a logic
level zero. In the case of a positive logic signal, the signal is
active high where the logically true state corresponds to a logic
level one. Note that any of the signals described herein may be
designed as either negative or positive logic signals. Therefore,
in alternate embodiments, those signals described as positive logic
signals may be implemented as negative logic signals, and those
signals described as negative logic signals may be implemented as
positive logic signals.
[0158] Furthermore, the terms "assert" or "set" and "negate" (or
"deassert" or "clear") are used herein when referring to the
rendering of a signal, status bit, or similar apparatus into its
logically true or logically false state, respectively. If the
logically true state is a logic level one, the logically false
state is a logic level zero. And if the logically true state is a
logic level zero, the logically false state is a logic level
one.
[0159] Those skilled in the art will recognize that the boundaries
between logic blocks are merely illustrative and that alternative
embodiments may merge logic blocks or circuit elements or impose an
alternate decomposition of functionality upon various logic blocks
or circuit elements. Thus, it is to be understood that the
architectures depicted herein are merely exemplary, and that in
fact many other architectures may be implemented which achieve the
same functionality.
[0160] Any arrangement of components to achieve the same
functionality is effectively "associated" such that the desired
functionality is achieved. Hence, any two components herein
combined to achieve a particular functionality may be seen as
"associated with" each other such that the desired functionality is
achieved, irrespective of architectures or intermedial components.
Likewise, any two components so associated can also be viewed as
being "operably connected," or "operably coupled," to each other to
achieve the desired functionality.
[0161] Furthermore, those skilled in the art will recognize that
boundaries between the above described operations merely
illustrative. The multiple operations may be combined into a single
operation, a single operation may be distributed in additional
operations and operations may be executed at least partially
overlapping in time. Moreover, alternative embodiments may include
multiple instances of a particular operation, and the order of
operations may be altered in various other embodiments.
[0162] Also for example, in one embodiment, the illustrated
examples may be implemented as circuitry located on a single
integrated circuit or within a same device. Alternatively, the
examples may be implemented as any number of separate integrated
circuits or separate devices interconnected with each other in a
suitable manner.
[0163] However, other modifications, variations and alternatives
are also possible. The specifications and drawings are,
accordingly, to be regarded in an illustrative rather than in a
restrictive sense.
[0164] In the claims, any reference signs placed between
parentheses shall not be construed as limiting the claim. The word
`comprising` does not exclude the presence of other elements or
steps then those listed in a claim. Furthermore, the terms "a" or
"an," as used herein, are defined as one or more than one. Also,
the use of introductory phrases such as "at least one" and "one or
more" in the claims should not be construed to imply that the
introduction of another claim element by the indefinite articles
"a" or "an" limits any particular claim containing such introduced
claim element to inventions containing only one such element, even
when the same claim includes the introductory phrases "one or more"
or "at least one" and indefinite articles such as "a" or "an." The
same holds true for the use of definite articles. Unless stated
otherwise, terms such as "first" and "second" are used to
arbitrarily distinguish between the elements such terms describe.
Thus, these terms are not necessarily intended to indicate temporal
or other prioritization of such elements The mere fact that certain
measures are recited in mutually different claims does not indicate
that a combination of these measures cannot be used to
advantage.
[0165] While certain features of the invention have been
illustrated and described herein, many modifications,
substitutions, changes, and equivalents will now occur to those of
ordinary skill in the art. It is, therefore, to be understood that
the appended claims are intended to cover all such modifications
and changes as fall within the true spirit of the invention.
* * * * *