U.S. patent application number 11/586612 was filed with the patent office on 2007-08-09 for writing apparatuses and methods.
Invention is credited to Tomas Lock, Jarek Luberek, Torbjorn Sandstrom, Lars Stiblert.
Application Number | 20070182808 11/586612 |
Document ID | / |
Family ID | 37968057 |
Filed Date | 2007-08-09 |
United States Patent
Application |
20070182808 |
Kind Code |
A1 |
Stiblert; Lars ; et
al. |
August 9, 2007 |
Writing apparatuses and methods
Abstract
Patterns are written on workpieces, such as, glass sheets and/or
plastic sheets used in, for example, electronic display devices
such as LCDs. The workpiece may be larger than about 1500 mm may be
used. An optical writing head with a plurality of writing units may
be used. The workpiece and the writing head may be moved relative
to one another to provide oblique writing.
Inventors: |
Stiblert; Lars; (Goteborg,
SE) ; Sandstrom; Torbjorn; (Pixbo, SE) ;
Luberek; Jarek; (Molndal, SE) ; Lock; Tomas;
(Goteborg, SE) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 8910
RESTON
VA
20195
US
|
Family ID: |
37968057 |
Appl. No.: |
11/586612 |
Filed: |
October 26, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60730009 |
Oct 26, 2005 |
|
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60776919 |
Feb 28, 2006 |
|
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Current U.S.
Class: |
347/225 ;
347/224 |
Current CPC
Class: |
G02F 1/1303 20130101;
G03F 7/70366 20130101; H04N 1/06 20130101; G03F 7/70391 20130101;
H05K 3/0082 20130101; G03F 7/70783 20130101; G03F 7/70383 20130101;
H04N 1/0671 20130101; G03F 7/70425 20130101; G03F 7/24 20130101;
H04N 1/0607 20130101; G03F 7/704 20130101; G03F 7/70791 20130101;
G03F 7/70275 20130101; H05K 1/0393 20130101; B41J 2/442 20130101;
G02F 2203/12 20130101; H04N 1/0664 20130101; G03F 7/70358 20130101;
H04N 1/0628 20130101; G03F 7/70291 20130101 |
Class at
Publication: |
347/225 ;
347/224 |
International
Class: |
B41J 2/435 20060101
B41J002/435; B41J 2/47 20060101 B41J002/47; G01D 15/14 20060101
G01D015/14 |
Claims
1. An apparatus for patterning a workpiece, the apparatus
comprising: at least two optical writing units for patterning the
workpiece, the at least two optical writing units including
separate final lenses; a calibration sensor configured to detect
characteristics of the at least two optical writing units.
2. The apparatus of claim 1, wherein the calibration sensor detects
the characteristics of the optical writing units by scanning the at
least two optical writing units across the calibration sensor.
3. The apparatus of claim 1, further including, at least one
control unit for adjusting at least one parameter value associated
with at least one optical writing unit based on the detected
characteristics.
4. The apparatus of claim 3, wherein the at least one control unit
compares at least one detected characteristic to at least one set
parameter value and adjusts at least one parameter value based on
the comparison.
5. The apparatus of claim 3, wherein the at least one parameter is
a position of an optical writing unit.
6. The apparatus of claim 3, wherein the at least one parameter is
power of an optical writing unit.
7. The apparatus of claim 1, wherein the at least one parameter
value is a focus an optical writing unit.
8. The apparatus of claim 1, wherein the calibration sensor
includes at least two detectors, each of the at least two detectors
detecting one of the detected characteristics.
9. The apparatus of claim 1, wherein the at least two writing units
are single-point writing units.
10. The apparatus of claim 1, wherein the at least two writing
units are multi-point writing units.
11. The apparatus of claim 1, wherein the at least two writing
units are spatial light modulators.
12. The apparatus of claim 1, wherein the apparatus is a
cylindrical pattern generator.
13. An apparatus comprising: a cylindrical holder for holding at
least one workpiece; and a rotor scanner for patterning the at
least one workpiece, the at least one rotor scanner including at
least two writing units, the rotor scanner being configured to move
in an axial direction relative to the cylindrical holder and
configured to rotate on an axis, the axis of rotation being
substantially perpendicular to the axial movement of the
cylindrical holder.
14. The apparatus of claim 13, wherein the cylindrical holder holds
the at least one workpiece so as to at least partially enclose the
rotor scanner, and the at least rotor scanner creates a helical
pattern on the at least one workpiece by emitting electromagnetic
radiation in an outward radial direction.
15. The apparatus of claim 13, wherein the rotor scanner is
ring-shaped and configured to create a helical pattern on the at
least one workpiece by emitting electromagnetic radiation in an
inward radial direction.
16. The apparatus of claim 15, wherein the cylindrical holder
further includes air bearings for supporting the ring-shaped rotor
scanner.
17. The apparatus of claim 13, wherein the at least two writing
units are single-point lasers.
18. The apparatus of claim 13, wherein the at least two writing
units are multi-point lasers.
19. The apparatus of claim 13, wherein the at least two writing
units are spatial light modulators.
20. The pattern generator of claim 13, wherein the cylindrical
holder is stationary.
21. The apparatus of claim 13, wherein the at least two writing
units are arranged in at least one row on an outer portion of the
cylinder.
22. The apparatus of claim 13, wherein the at least two writing
units are arranged in at least one row on an inner portion of the
cylinder.
23. The apparatus of claim 13, wherein each of the at least two
optical writing units emits electromagnetic radiation in a
different radial direction.
24. A writing apparatus for patterning a workpiece, the writing
apparatus comprising: writing head including a plurality of writing
units, each writing unit configured to emit electromagnetic
radiation for patterning the workpiece; a detector for detecting
characteristics of a writing unit; and a control unit for adjusting
at least one parameter of at least two optical writing units based
on the detected characteristics.
25. The writing apparatus of claim 24, wherein the control unit is
further configured to determine correlation associated with at
least one of the optical writing units based on the detected
characteristics and a set parameter value and adjust the writing
head based on the correlation.
26. The writing apparatus of claim 25, wherein the control unit
determines the correlation by comparing each detected
characteristic with a corresponding set parameter value.
27. A method for calibrating an optical writing head, the method
comprising: detecting at least one characteristic of at least two
optical writing units included in the writing head; determining a
correlation between each of the at least one detected
characteristics and a corresponding set parameter value; and
adjusting at least one parameter value for each of the at least two
optical writing units based on the determined correlation.
28. The method of claim 27, wherein the determining further
includes, generating the correlation by comparing the at least one
detected characteristic with the corresponding set parameter
value.
29. The method of claim 27, wherein the correlation is a difference
between each of the at least one detected characteristic and a
corresponding set parameter value.
30. The method of claim 27, wherein each of the at least one
detected characteristics is one of a focus of electromagnetic
radiation emitted from the optical writing unit, power of
electromagnetic radiation emitted from the optical writing unit and
position of the optical writing unit.
Description
PRIORITY STATEMENT
[0001] This non-provisional U.S. patent application claims priority
to provisional U.S. patent application Ser. Nos. 60/730,009, filed
on Oct. 26, 2005 and 60/776,919, filed on Feb. 28, 2006, the entire
contents of both of which are incorporated by reference.
BACKGROUND
[0002] Conventional pattern generation systems for patterning large
workpieces also create the pattern in stripes, swaths or
rectangles. The boundaries between them, commonly referred to as
butting or stitching boundaries create undesirable artifacts that
may be visible in the final pattern. U.S. Pat. No. 5,495,279, the
entire contents of which are incorporated herein by reference,
illustrates a conventional method and apparatus for exposing
substrates.
[0003] Extremely high throughput, for example in the range of about
0.05 m.sup.2/s through about 0.2 m.sup.2/s, combined with the large
size of the workpieces, (e.g., in a range of about 5 m.sup.2
through 10 m.sup.2, and even 20 m.sup.2 or more), high optical
resolution (e.g., in the range of about 3 microns through about 5
microns, and even down to 1 micron) and a sensitivity to "Mura"
(visible striping or banding) defects creates a need to control
certain errors to 50 nm or better. Conventional pattern generators,
however, are unable to do so because merely scaling up conventional
pattern generation techniques fails to achieve the required error
control.
[0004] FIGS. 1D-1F illustrate example conventional pattern
generators as disclosed in U.S. Pat. No. 6,542,178, U.S. Patent
Publication No. 2004/0081499 and 2005/0104953, respectively, the
entire contents of each of which are incorporated herein by
reference.
[0005] FIG. 1D illustrates a drum plotter as disclosed in U.S. Pat.
No. 6,542,178. As shown in FIG. 1D, the drum plotter includes a
single writing unit writing optically on a rotating drum while
moving along the axis of the drum. In the drum plotter of FIG. 1D,
however, only the drum holding the workpiece, but not the single
writing unit, is capable of rotating. Moreover, the drum plotter of
FIG. 1D includes only a single exposure head, and each of the drum
and the single writing unit are only capable of a single type of
movement. That is, the drum is only capable of rotating, whereas
the single writing unit is only capable of linear translational
movement.
[0006] FIG. 1E illustrates an optical system as disclosed in U.S.
Patent Publication No. 2004/0081499 for thermal transfer printing
on glass substrates for LCD production. As shown in FIG. 1E, the
optical system also includes a single optical writing unit moving
along the axis of the rotating cylindrical workpiece holder. In the
optical system of FIG. 1E, however, only the cylindrical workpiece,
but not the single optical writing unit, is capable of rotating.
Moreover, the optical system of FIG. 1E includes only a single
exposure head, and each of the cylindrical workpiece and the single
optical writing unit are only capable of a single type of movement.
That is, the cylindrical workpiece is only capable of rotating,
whereas the single optical writing unit is only capable of linear
translational movement.
[0007] FIG. 1F illustrates a system writing optically on a rotating
drum using multiple light sources coupled with fibers to a single
writing unit and having the power of the light sources calibrated
against a single detector as disclosed in U.S. Patent Publication
No. 2005/0104953. As shown in FIG. 1F, the optical system also
includes a single writing unit moving along the axis of the
rotating rotating drum. In the optical system of FIG. 1F, as in the
optical systems of FIGS. 1D and 1E, only the cylindrical workpiece,
but not the single optical writing unit, is capable of rotating.
Moreover, the optical system of FIG. 1F includes only a single
exposure head, and each of the cylindrical workpiece and the single
optical writing unit are only capable of a single type of movement.
That is, the cylindrical workpiece is only capable of rotating,
whereas the single optical writing unit is only capable of linear
translational movement.
[0008] The optical system of FIG. 1F further includes a
photodetector for detecting the quantity of light emitted from the
single optical writing unit. This photo detector, however, only
detects quantity of light from the single optical writing unit.
[0009] Moreover, in each of FIGS. 1D-1F, the direction of rotation
is parallel with one axis of the pattern and workpiece, while being
perpendicular to the other axis of the pattern and workpiece.
[0010] FIG. 12A shows an example alignment of movements, produced
by pattern generators such as those discussed above. Referring to
FIG. 12A, three different coordinate systems are present. The first
is the coordinate system of the pattern. In this example the
patterns are display devices 1210, 1220, 1230 and 1240 formed on
the workpiece glass. The second coordinate system is that of the
writing mechanism 1260. In this example, the writing mechanism 1260
is an SLM. The third coordinate system is formed by the direction
1250 of movement of the writing mechanism 1260. In FIG. 12A, the
three coordinate systems are aligned with each other. Arrow 1250
indicates the rotation direction of the workpiece relative to the
pattern of the writing mechanism 1260. In the example shown in FIG.
12A, the rotation direction is parallel to a side of the writing
mechanism (e.g., an SLM chip).
[0011] Conventional art direct write machines exposing liquid
crystal display (LCD) workpieces using conventional pattern
generators have write times of about twenty-four hours (one day).
In these conventional pattern generators, writing width may be
increased to reduce write time. However, this may require a larger
number of optical channels and/or lenses, which may increase cost
and/or complexity of the pattern generator. The speed at which the
stage is moved may also be increased. However, controlling
mechanical motion and/or vibration may be more difficult as stage
speed increases. For example, an increase in speed and mass along
with a decrease in application time may result in greater
vibrations and/or resonances at higher frequencies in the
mechanical structures. In addition, control and/or mechanical
systems may not settle properly before writing a new stripe.
Moreover, increased speed, vibration and/or a number of optical
channels may increase cost and/or complexity of conventional
pattern generators.
SUMMARY OF THE INVENTION
[0012] Example embodiments describe mechanical, optical and/or
calibration methods and apparatuses, which may alone or in
combination simultaneously provide increased (e.g., high or
relatively high) throughput, resolution and/or image quality on
larger (e.g., large, very large or relatively large)
workpieces.
[0013] Example embodiments relate to methods and apparatuses for
patterning a workpiece, for example, an increased throughput and/or
higher precision pattern generator for patterning multiple types of
workpieces.
[0014] Example embodiments may be applied to other workpieces with
similar design and/or requirements, such as other types of displays
(e.g., OLED, SED, FED, "electronic paper" and the like). The
workpieces shown in the application are cut sheets, but may also be
continuous sheets of glass, plastic, metal, ceramic, etc. Some
example embodiments may also be used to process solar panels.
[0015] Example embodiments are discussed herein with respect to
standard photolithography, for example, exposure of a resist,
however, at least some example embodiments may also be applied to
patterning by laser ablation, thermal pattern transfer and/or other
light-induced surface modification.
[0016] In at least some examples embodiments, a conventional "scan
and retrace" method may be replaced by a rotating scan method,
according to example embodiments. In addition, or alternatively, a
pattern generator including a rotor scanner may replace a scan and
retrace pattern generator. The rotation of the rotor scanner
pattern generator, according to at least some example embodiments,
may have a higher constant speed than the scanning speed in the
conventional "scan and retrace" method. A plurality (e.g., at least
two) of optical writing units may be arranged, for example, on the
rim of a rotating disc or ring, and may emit a beam in a radial
direction.
[0017] In at least some examples embodiments, at least one of a
holder for holding a workpiece and at least one writing head may be
rotated. The at least one writing head may include a plurality of
exposure beams having a wavelength for exposing a layer of
electromagnetic radiation sensitive material covering at least a
portion of a surface of a workpiece, and may radiate in a radial
direction. At least one of the holder and the at least one writing
head may be moved translationally so that the at least one writing
head and the holder move relative to each other, and form a
trajectory of exposed area of the workpiece.
[0018] At least some example embodiments provide a pattern
generator including a holder adapted to hold at least one
workpiece. At least one writing head may include a plurality of
exposure beams having a wavelength for exposing a layer of
electromagnetic radiation sensitive material covering at least a
portion of a surface of the at least one workpiece. At least one of
the holder and the at least one writing head may be adapted to move
rotationally such that the holder and the at least one writing head
move relative to one another. At least one of the holder and the at
least one writing head may be adapted to move relative to one
another such that the holder and the at least one writing head move
translationally relative to each other such that a trajectory of
exposed area of the at least one workpiece may be formed.
[0019] In at least some examples embodiments, each optical writing
unit may write a single pixel, an array of non-interfering pixels,
or a combination thereof.
[0020] In at least some examples embodiments, one or more optical
writing units may include an SLM with at least between about 1000
to about 1,000,000 elements, inclusive.
[0021] According to at least some example embodiments, the
workpiece may be fixed, and the placement of a first pattern on the
workpiece may be measured. The written pattern may be adjusted to
match a distortion of the first pattern. The distortion of a first
pattern on the workpiece may be measured and the distortion of said
first pattern may be used to create a matching contiguous bitmap.
The pattern written on the workpiece may include display devices of
at least two different sizes. A pattern written on the workpiece
may have one display with larger area than a quarter of the glass
size.
[0022] In at least some examples embodiments, the rotating of the
at least one writing head may create a helical pattern or helical
shaped trajectories on the workpiece.
[0023] In at least some examples embodiments, the workpiece may be
wrapped at least partly around the writing head.
[0024] At least one example embodiment provides a method for
generating a pattern on a workpiece. The method may include
scanning at least one optical writing unit across a surface of a
workpiece creating a pixel grid, the pixel grid being arranged at
an angle relative to axes of features of the pattern, the angle
being different from 0, 45 or 90 degrees.
[0025] In at least some example embodiments, the scanning may
create at least two equidistant scan lines. The scanning is
performed in at least two directions.
[0026] At least one other example embodiment provides a writing
apparatus for generating a pattern on a workpiece. The apparatus
may include a writing head including at least one optical writing
unit configured to scan across a surface of a workpiece to create a
pixel grid, the pixel grid being arranged at an angle relative to
axes of features of the pattern, the angle being different from 0,
45 or 90 degrees. The writing head may be configured to create at
least two equidistant scan lines during scanning and/or may scan
the workpiece in at least two directions.
[0027] At least one other example embodiment provides a method for
generating a pattern on a workpiece. The method may include
rotating a rotor scanner having a plurality of optical writing
units, each of the optical writing units emitting electromagnetic
radiation, and
[0028] scanning, concurrently with the rotating of the rotor
scanner, the workpiece by moving at least one of the workpiece and
the at least one writing head in a direction perpendicular to a
plane of rotation of the rotor scanner.
[0029] In at least some example embodiments, the electromagnetic
radiation may be emitted in a radial direction relative to the
rotor scanner. In at least some example embodiments, the
electromagnetic radiation may be emitted in an axial direction
relative to the rotor scanner. The scanning of the workpiece may
include scanning the workpiece in a first direction to create a
pixel grid, the pixel grid being created at an angle relative to at
least one of the first direction and axes of the pixel grid, the
angle being different from 0, 45 and 90 degrees. The workpiece may
be scanned in a first direction to create a helical pattern on the
workpiece. The electromagnetic radiation may be emitted in a
direction parallel to at least one of a plane of rotation of the
rotor scanner and the scanning direction of the rotor scanner.
[0030] At least one other example embodiment provides a writing
apparatus for generating a pattern on a workpiece. The apparatus
may include a rotor scanner including a plurality of optical
writing units, each of the optical writing units emitting
electromagnetic radiation. The rotor scanner may be configured to
scan the workpiece by rotating the rotor scanner and moving at
least one of the workpiece and the at least one writing head in a
direction perpendicular to a plane of rotation of the rotor
scanner.
[0031] At least one other example embodiment provides a method for
patterning a workpiece. The method may include scanning a plurality
of optical writing units across a surface of the workpiece, each of
the plurality of optical writing units having a separate final
lens, and moving the workpiece and the plurality of optical writing
units relative to each other, the relative motion being a
combination of linear movement and circular motion in a direction
perpendicular to the linear motion.
[0032] At least one other example embodiment provides an apparatus
for patterning a workpiece. The apparatus may include at least two
optical writing units for patterning the workpiece, the at least
two optical writing units including separate final lenses and a
calibration sensor configured to detect characteristics of the at
least two optical writing units. The calibration sensor may detect
the characteristics of the optical writing units by scanning the at
least two optical writing units across the calibration sensor.
[0033] In at least some example embodiments, the apparatus may
further include at least one control unit for adjusting at least
one parameter value associated with at least one optical writing
unit based on the detected characteristics.
[0034] In at least some example embodiments, the at least one
control unit may compare at least one detected characteristic to at
least one set parameter value and adjusts at least one current
parameter value based on the comparison. The at least one parameter
may be a focus, position or power of an optical writing unit. The
calibration sensor may include at least two detectors, each of the
at least two detectors detecting one of the detected
characteristics.
[0035] The at least two writing units may be single-point writing
units, multi-point writing units or spatial light modulators. The
apparatus may be a cylindrical pattern generator.
[0036] At least one other example embodiment provides an apparatus
including a cylindrical holder for holding at least one workpiece,
and a rotor scanner for patterning the at least one workpiece. The
at least one rotor scanner may include at least two writing units
and may be configured to move in an axial direction relative to the
cylindrical holder and configured to rotate on an axis. The axis of
rotation may be substantially perpendicular to the axial movement
of the cylindrical holder.
[0037] In at least some example embodiments, the cylindrical holder
may hold the at least one workpiece so as to at least partially
enclose the rotor scanner, and the at least one rotor scanner may
create a helical pattern on the at least one workpiece by emitting
electromagnetic radiation in an outward radial direction.
[0038] In at least some example embodiments, the rotor scanner may
be ring-shaped and configured to create a helical pattern on the at
least one workpiece by emitting electromagnetic radiation in an
inward radial direction. The cylindrical holder may further include
air bearings for supporting the ring-shaped rotor scanner. In at
least some example embodiments, the cylindrical holder may be
stationary. The at least two writing units may be arranged in at
least one row on an outer portion or an inner portion of the
cylinder. Each of the at least two optical writing units may emit
electromagnetic radiation in a different radial direction.
[0039] At least one other example embodiment provides a writing
apparatus for patterning a workpiece. The writing apparatus may
include a writing head including a plurality of writing units, each
writing unit configured to emit electromagnetic radiation for
patterning the workpiece, a detector for detecting characteristics
of a writing unit and a control unit for adjusting the writing head
to compensate for errors determined based on the detected
characteristics.
[0040] In at least some example embodiments, the control unit may
be further configured to determine at least one correlation
associated with at least one of the optical writing units based on
the detected characteristics and adjust the writing head based on
the at least one correlation. The control unit may determine the
correlation based on a comparison of the at least one
characteristic and a corresponding set parameter value.
[0041] Another example embodiment provides a method for calibrating
an optical writing head. The method may include detecting at least
one characteristic of an optical writing unit included in the
writing head, determining a correlation between the at least one
detected characteristic and a corresponding set parameter value,
and adjusting the writing head based on the determined correlation.
The correlation may be generated by comparing the at least one
detected characteristic with the corresponding set parameter value.
The correlation may be a difference between the at least one
detected characteristic and a corresponding set parameter value.
The detected characteristic may be one of a focus of
electromagnetic radiation emitted from the optical writing unit,
power of electromagnetic radiation emitted from the optical writing
unit and position of the optical writing unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Example embodiments will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0043] FIG. 1A illustrates a rotor scanner with a single ring of
single-point writing units, according to an example embodiment;
[0044] FIG. 1B illustrates a simplified view of the single-ring,
single-point scanner writing sequentially lines from edge to edge
of the workpiece and the adjustments needed for each writing unit,
according to an example embodiment;
[0045] FIG. 1C shows an example embodiment of the rotor scanner
using spatial light modulators (SLMs) building the image from SLM
fields ("stamps") and the adjustments needed for each writing unit,
according to an example embodiment;
[0046] FIGS. 1D-1F illustrate conventional pattern generators;
[0047] FIG. 2 illustrates a writing apparatus, according to another
example embodiment;
[0048] FIG. 3 illustrates an arrangement of calibration sensors
between workpieces, according to an example embodiment;
[0049] FIG. 4 is a side-view of a calibration sensor, according to
an example embodiment;
[0050] FIG. 5 is a schematic representation of a calibration
sensor, according to an example embodiment;
[0051] FIG. 6 illustrates a combination optical writing unit and
optical measurement unit, according to an example embodiment;
[0052] FIGS. 7A-7C illustrate different implementations and
orientations of a disc-type writing apparatus, according to example
embodiments;
[0053] FIGS. 8A-8C illustrate different implementations and
orientations of a ring-type writing apparatus, according to another
example embodiment;
[0054] FIG. 9 illustrates a horizontal oriented cylindrical stage
or holder, according to an example embodiment;
[0055] FIG. 10 illustrates a flat workpiece, which may be written
using a writing apparatus, according to one or more example
embodiments;
[0056] FIGS. 11A-11K illustrate a plurality of different positions
of a writing head in relation to the direction of a rotor scanner
relative to the workpiece, according to at least one example
embodiment;
[0057] FIGS. 12A-12E illustrate an SLM arrangement and workpiece
arrangement relative to the rotational direction of the rotor
scanner;
[0058] FIG. 13 illustrates an auto focus arrangement, according to
an example embodiment;
[0059] FIG. 14 is a top-view of a calibration sensor, according to
an example embodiment;
[0060] FIG. 15 is a perspective view of a writing apparatus,
according to another example embodiment;
[0061] FIG. 16 illustrates a writing apparatus, according to
another example embodiment;
[0062] FIG. 17 is a top view of the writing apparatus 1520 shown in
FIG. 15;
[0063] FIG. 18 illustrates a writing apparatus, according to
another example embodiment;
[0064] FIG. 19A is a side view of a writing apparatus, according to
another example embodiment;
[0065] FIG. 19B is a top view of the writing apparatus shown in
FIG. 19A;
[0066] FIG. 20 illustrates a method for transformation of a
Cartesian grid into a bent coordinate system, according to an
example embodiment;
[0067] FIG. 21 shows a vacuum arrangement for holding the workpiece
on the cylinder;
[0068] FIG. 22 illustrates a writing apparatus, according to
another example embodiment;
[0069] FIG. 23 is a more detailed illustration of the pattern
generator shown in FIG. 16;
[0070] FIGS. 24A-E illustrate methods for continuous scanning in
the x and y directions, according to an example embodiment;
[0071] FIGS. 25-28 illustrate flatbed platforms, according to
example embodiments; and
[0072] FIG. 29 shows a diagram over the position of the stage and
the counter masses during scanning;
[0073] FIG. 30 illustrates a calibration system, according to
another example embodiment; and
[0074] FIG. 31 illustrates a calibration method, according to an
example embodiment.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0075] Example embodiments are described with reference to the
figures. These example embodiments are described to illustrate the
present invention, not to limit its scope, which is defined by the
claims. Those of ordinary skill in the art will recognize a variety
of equivalent variations on example embodiments described as
follows.
[0076] In at least some examples embodiments, a rotor scanner may
be in the form of a ring. In this example, each of a plurality of
optical writing units may be arranged and configured to emit
electromagnetic radiation in the form of at least one laser beam.
The laser beams may be emitted in at least two directions. In at
least some examples embodiments, the laser beams may be emitted in
at least two parallel directions. In at least some examples
embodiments, the laser beams may be emitted in a radial direction
inward toward a workpiece arranged on a cylindrical holder
positioned inside the ring-shaped rotor scanner.
[0077] In at least some examples embodiments, the rotor scanner may
be in the form of a disc. In this example, each of the plurality of
optical writing units may be arranged and configured to emit
electromagnetic radiation in the form of at least one laser beam in
a radial direction outward toward at least one workpiece arranged
so as to at least partly enclose the disc-shaped rotor scanner.
Alternatively, the disc-shaped rotor scanner may be
ring-shaped.
[0078] For the sake of clarity, a rotor scanner including optical
writing units arranged and configured to emit electromagnetic
radiation in the form of at least one laser beam in an outward
radial direction will be referred to hereinafter as a disc rotor
scanner, whereas the rotor scanner including optical writing units
arranged and configured to emit electromagnetic radiation in the
form of at least one laser beam in an inward radial direction will
be referred to herein as the ring rotor scanner. A rotor scanner
configured to emit electromagnetic radiation in the form of at
least one laser beam in an axial direction will be referred to
herein as an axial rotor scanner. Hereinafter, when discussing
aspects of example embodiments applicable to both the disc rotor
scanner and the ring rotor scanner, the disc rotor scanner and the
ring rotor scanner will be referred to collectively as a rotor
scanner.
[0079] The workpiece may be flexible (e.g., very flexible) and may
need a cylindrical support to have and maintain a desired radius.
The inner part of the workpiece may more easily assume a
cylindrical shape; however, at edges parallel to the cylinder axis,
a bending moment may be introduced to start bending the workpiece
at the proper bending radius. This bending moment may be on the
order of a few kg*cm, and may be introduced by a lengthwise clamp.
This clamp may also support the workpiece as workpiece is loaded
into the machine.
[0080] The workpiece may have a thickness tolerance of about +/-70
m and a variation of less than about 20 .mu.m over a length of
about 150 mm. This variation may disturb the focus position and may
be corrected in focus and/or in the shape of the workpiece. For
example, the shape from the rotor scanner may be measured, and the
shape of the workpiece may be corrected. The active workpiece shape
may be corrected only within the writing zone. In this example, the
corrector hardware may follow along with the rotor scanner
assembly, which may reduce the number of actuators. The use of a
corrector may use optics with a shorter depth of field.
[0081] The rotor scanner may be supported by bearing pads (e.g.,
air bearing pads) that may control the position of the axis of
rotation and/or the lengthwise position of the rotor scanner. The
positioning in the direction of rotation may be adjusted by timing
of the pattern. The dynamic positioning in the axis lengthwise
direction may, depending on the design, need active components to
move the image plane.
[0082] The rotor scanner position may be determined by several
different methods, according to example embodiments. For example,
in the ring rotor scanner marks on the periphery may be detected,
for example, optically, and the position of the rotor scanner may
be interpolated between these marks or positions. The air friction
may be reduced (e.g., to about 0.1 N), and the speed may be
increased. The time between markers may be shorter and/or the
possible deviations due to residual forces may decrease as this
"time between markers" squared. In example embodiments having a
vertical axis, internal accelerometers in the rotor scanner may be
mused to achieve a more accurate feedback signal. The feedback
signal may be used for velocity control. In example embodiments
having a horizontal axis, accelerometers may also be used; however,
in this case the accelerometers may need to be balanced such that
the direction of the forces of gravity is unseen. Although not
described herein, interferometry or any other suitable methods may
also be used.
[0083] Velocity differences of the scanner rotor may be measured
with, for example, internal rotation accelerometers and the
rotational accuracy may be improved. Angular position of the rotor
scanner may be measured using a plurality of markers (e.g., optical
markers) around an outer edge of the rotor scanner. A control
system may use the markers as an absolute measurement of position
of the rotor, and may interpolate the "in between position" by
time. The accuracy of the interpolation may be increased by using
internal rotational accelerometers.
[0084] The rotor may be balanced using distance sensors, a pressure
signal from a bearing pad, or any other suitable measuring device.
In example embodiments, the rotor scanner may be supported by
bearings, air bearings, air bearing pads, etc.
[0085] In at least some examples, transfer of data may be eased by
rendering the patterns such that they are streamed to the rotor
with little adjustment. In this example, the data may be rendered
in a predistorted manner, and stored so that each arc is
represented by a column of data in the memory. As the workpiece is
written, columns may be read (e.g., successively) from left to
right in a memory matrix and the data may be sent through to the
rotor scanner.
[0086] FIG. 1A shows a rotor scanner with a single ring of
single-point optical writing units, according to an example
embodiment. FIG. 1B shows a simplified view of the single-ring,
single-point scanner writing sequentially lines from edge to edge
of the workpiece, and the adjustments needed for each writing unit.
FIG. 1C shows an example embodiment of a rotor scanner using SLMs
to generate the image from SLM fields ("stamps") and the
adjustments needed for each writing unit.
[0087] Referring to FIG. 1A, the pattern generation apparatus may
include a rotor scanner 1. The rotor scanner 1 may be disc shaped
and may include at least one (e.g., a plurality of) writing head
10. Each of the write heads 10 may emit light in a radial
direction. A workpiece 20 may partly enclose the rotor scanner 1.
The rotor scanner 1 may be rotatable and may rotate at a constant
or substantially constant speed. A power slip ring may be placed at
the center. The slip ring may be a graphite/copper slip ring, an HF
transformer contactless slip ring, a frictionless slip ring, or any
other suitable slip ring. In example embodiments, an HF slip ring
may reduce (e.g., eliminate) dust common with ordinary slip
rings.
[0088] Still referring to FIG. 1A, a workpiece may be bent such
that the curvature of the workpiece has a radius larger (e.g.,
slightly larger) than that of the disc rotor scanner and/or such
that the focal spot of the optical system may be matched.
Alternatively, in example embodiments of the ring rotor scanner, a
workpiece may be bent such that the curvature of the workpiece has
a radius less than that of the ring rotor scanner and/or such that
the focal spot of the optical system may be matched. In example
embodiments in which the workpiece is bent or curved, the workpiece
may be, for example, a workpiece capable of bending to a desired
curvature, such as, a glass workpiece, a plastic workpiece,
etc.
[0089] In an example embodiment in which a workpiece is bent (e.g.,
wrapped) to a curvature spanning about 180.degree., the disc rotor
scanner may have a diameter of, for example, about 1.4 meters (m).
A smaller bend radius (e.g., a minimum bend radius) of about 1.3 m
may be used when the workpiece is wrapped about 180 degrees around
a disc write head. The cylindrical support for a glass wrapped
approximately 180 degrees may have a radius of between about 1 and
about 2 meters, inclusive.
[0090] In a system for writing one workpiece at a time the
workpiece may be bent to about or near 360.degree.. A workpiece
(e.g. glass, plastic, metal, ceramic, etc.) may be between about 2
and about 3 meters, inclusive, or up to about 6 meters and the
corresponding cylinder for a single glass may have a radius of
about 0.35 to about 0.6 meters, inclusive, and up to about 1 meter.
Bending a glass workpiece with a radius of about 1.3 meters may
produce a stress of around 31 MPa per mm workpiece thickness. With
workpiece thickness of about 0.7 mm the stress may be about 22 MPa,
and only a smaller fraction of the safe stress.
[0091] In another example, if the workpiece is wrapped to a
curvature spanning about 120.degree., the disc rotor scanner may
have a diameter of about 2.1 m. In this case it may be suitable to
employ a cylindrical support with a radius of about 2 to about 3 m,
inclusive. In these examples, the overall width of the pattern
generator may be smaller than that of conventional pattern
generators and/or writing apparatuses, for example, about 2 m wide.
The workpiece may be sectional (e.g., cut into sheets) or in a
continuous form, for example, for roll-to-roll processing of
displays and/or solar panels.
[0092] Referring back to FIG. 1A, the rotor scanner may rotate in a
counter-clockwise direction; however, alternatively the rotor
scanner may rotate in a clockwise direction. As shown in FIG. 1A,
while rotating, the rotor scanner 1 may be moved in an upward
vertical scan direction 50; however, it will be understood that the
rotor scanner may move in a downward direction or a horizontal
direction (e.g., to the right or to the left). A pattern to be
printed on the workpiece 20 may be determined by a modulation of
the writing heads 10. During operation (e.g., patterning or
writing), electromagnetic radiation from the writing heads 10 may
form a helical pattern 30 on the workpiece 20.
[0093] The lengthwise scan of the workpiece 20 may be accomplished
by moving the workpiece 20 and/or the rotor scanner 1. Because the
rotor scanner 1 may be thinner or substantially thinner than the
workpiece 20 and/or workpiece holder (not shown), the rotor scanner
1 may be moved and the workpiece 20 may be written without a need
for additional length. The non-rotating part of the rotor scanner
1, or bearing pads may perform the axial scan and/or carry other
(e.g., all other) functions.
[0094] A rotor scanner 1 may be supported by bearing pads (e.g.,
air bearing pads). In this example, the ring design may have
additional room for the bearing pads on the inner ring radius.
[0095] The rotor scanner 1 may be balanced (e.g., very accurately
balanced). Any residual unbalance may be more easily detected, for
example, by back-pressure variations in the bearing pressure pads
(e.g., air bearing pressure pads) or by other position sensors. An
automatic balancing system that may continuously balance the rotor
scanner may also be used. Disturbances to the rotor scanner 1 may
be a result of airflow between the rotor scanner and/or a rotor
scanner shield. If the air flow between the rotor scanner and the
rotor scanner shield is forced to be laminar, for example, by
choosing a suitably small gap (e.g., a few mm at 5 m/s), stability
of the operating conditions may be increased. The laminar flow may
introduce forces, for example, stationary forces. In example
embodiments, the power loss to friction may be reduced (e.g., to a
few watts), and the rotor scanner may be driven by any suitable
motor. For example, the friction at a 1 mm gap at 5 m/s may have a
loss of 0.5 W per m.sup.2. The bearing pads may have a smaller gap
and/or larger drag, which may be offset by the smaller area. The
motor may have a drive system having uniform, or substantially
uniform, torque while turning.
[0096] The number of optical writing units included in the disc
rotor scanner 1 may be based on write speed. In at least one
example embodiment, the writing units may be fed data from a data
channel with a higher (e.g., a very high) data rate, (e.g., about
200, 400, 500 or more Gbit/sec). Because the machine may be used
for production, the pattern may be the same or substantially the
same at all times. If the pattern is stored locally inside the
rotor scanner, the pattern may be loaded at a lower speed (e.g.,
through a conventional high speed link) while the rotor scanner is
stationary. The pattern may then reside (e.g., permanently reside)
in memory. This may avoid the rotating data joint.
[0097] As shown in FIGS. 1A and 1B, the optical writing units may
be, for example, single point laser diodes. The laser diodes may be
of any commercial available wavelength such as blue, red, violet,
etc. The power of a laser diode may be, for example, about 5 mW to
about 65 mW, inclusive for single mode, and about 5 mW to about 300
mW, inclusive for multimode diodes. An electro-optical efficiency
of a laser diode may be, for example, about 13%. The laser diodes
may act as an optical power source and a modulator, for example,
simultaneously. Alternatively, as shown in FIG. 1C, the optical
writing units may be SLMs.
[0098] The axis of rotation of the rotor scanner may be vertical,
horizontal, or any angle there between. The vertical axis
arrangement may have a constant, or substantially constant,
acceleration of the optical writing units at all times. The
horizontal axis arrangement may handle the workpiece more
efficiently and/or with less effort absent the need to counteract
forces of gravity.
[0099] FIGS. 7A-7C illustrate different implementations and
orientations of a writing apparatus, according to example
embodiments. The disc rotor scanner discussed below with regard to
FIGS. 7A-7C may be the same or substantially the same as the disc
rotor scanner 1 of FIG. 1. Therefore, a detailed discussion will be
omitted for the sake of brevity.
[0100] Referring to FIG. 7A, the writing apparatus 700 may include
a holder (e.g., a tubular holder) 710, a disc rotor scanner 730
and/or at least one optical writing unit 740. In at least some
examples embodiments, the disc rotor scanner 730 may include a
plurality of optical writing units 740.
[0101] The workpiece 720 may be arranged inside the workpiece
holder 710. A central axis of the formed holder 710 may be
arranged, for example, horizontally. The holder 710 may be kept at
a fixed position, while the disc rotor scanner 730 rotates and/or
moves in a direction parallel or substantially parallel to the
central axis. The optical writing units 740 may be arranged on an
outer edge of the disc rotor scanner in at least one row, but are
shown as including two rows in FIG. 7A. The optical writing units
740 may face an inner surface of the workpiece holder 710.
Alternatively a single row or greater than two rows of optical
writing units 740 may be used.
[0102] Referring to FIG. 7B, the central axis of the workpiece
holder 710 may be arranged vertically. The workpiece 720 may be
arranged inside the holder 710 as discussed above with regard to
FIG. 7A. The workpiece 720 may be fixed in the holder 710 by
forces, which may flatten, or substantially flatten the workpiece
720. Alternatively, the workpiece 720 may be fixed to the holder
710 by vacuum nozzles. In this example, the workpiece 720 may be
fixed in the holder 710 by removing the air between the workpiece
720 and the holder 710. The workpiece 720 and holder 710 may be
fixed while the disc rotor scanner 730 may rotate and/or move
vertically (e.g., upward and/or downward).
[0103] Referring to FIG. 7C, the writing apparatus of FIG. 7C may
be similar or substantially similar to the writing apparatus
discussed above with regard to FIG. 7B. However, in the writing
apparatus of FIG. 7C, the workpiece 720 and/or the holder 710 may
rotate while the disc rotor scanner 730 moves in a vertical
direction (e.g., upwards and/or downwards).
[0104] FIG. 2 illustrates a writing apparatus, according to yet
another example embodiment. As shown, the writing apparatus of FIG.
2 may be used to pattern a plurality of workpieces concurrently or
simultaneously. Although the writing apparatus of FIG. 2 will be
discussed with respect to patterning three workpieces 222A, 222B
and 222C, simultaneously, it will be understood that any number of
workpieces may be patterned concurrently. The rotor scanner 220 of
FIG. 2 may be the same or substantially the same as the rotor
scanner 1 of FIG. 1.
[0105] Referring to FIG. 2, the workpieces 222A, 222B and 222C, may
at least partially enclose or surround the rotor scanner 220. As
shown, openings 224, 226, and 228 may be left between each of the
workpieces 222A, 222B and 222C. At least one of a detector and a
calibration sensor (not shown, but described in more detail below)
may be positioned in each space between the workpieces. In at least
one example embodiment, the detector and/or calibration sensor may
monitor the position, focus and/or power of the rotor scanner 220.
Any misalignment of the rotor scanner 220 relative to a desired
position may be compensated, for example, using dose, modulation
delaying, timing, image distortion, or any other suitable
manner.
[0106] FIG. 3 illustrates a plurality of calibration sensors 310,
320 and 330 positioned in the openings 224, 226 and 228,
respectively. As shown in FIG. 3, three workpieces are held by the
writing apparatuses and three calibration sensors are used. In
accordance with example embodiments, the number of calibration
sensors may be correlated to the number of workpieces concurrently
arranged in the writing apparatus. In some example embodiments, the
number of calibration sensors may be equal to the number of
workpieces.
[0107] FIG. 4 is a top view of a portion of the writing apparatus
of FIG. 2 including a calibration sensor (e.g., a calibration eye),
according to an example embodiment. FIG. 14 is a side view
corresponding to the top view of FIG. 4.
[0108] Referring to FIGS. 4 and 14, the calibration sensor 400 may
detect position, power and/or may focus individual beams 410 of a
rotor scanner 430 based on characteristics of the electromagnetic
radiation emitted from the optical writing units (not shown) of the
rotor scanner 430. In at least some example embodiments, the
calibration sensor 400 may include an interferometer (not shown)
for measuring the position (e.g., the vertical position of the
rotor scanner if the pattern generation apparatus is oriented
vertically) of the rotor scanner 430. Interferometers are
well-known in the art, and therefore, a detailed discussion will be
omitted for the sake of brevity. The rotor scanner 430 may be the
same or substantially the same as the rotor scanners 1 and/or 220,
and thus, a detailed discussion will be omitted for the sake of
brevity.
[0109] If a single workpiece 420 is wrapped on the holder, the
calibration sensor 410 may be arranged between the edges of the
workpiece 420. In example embodiments, the workpiece 420 may be
wrapped onto a holder (e.g., a tubular shaped holder). The rotor
scanner 430 may rotate inside the wrapped workpiece 420. In at
least example embodiments, a distance between a scanner base 440
and the rotor scanner 430 may be measured using, for example, laser
interferometry or any other suitable technique.
[0110] FIG. 5 is a schematic representation of the calibration
sensor 400, according to example embodiments. The calibration
sensor 400 may include a lens assembly 510 through which
electromagnetic radiation, emitted from the optical writing units
of the rotor scanner may pass. The electromagnetic radiation may be
partially reflected by a beam splitter 520. A first portion of the
electromagnetic radiation may pass through the beam splitter 520
and irradiate a first quadrant detector 550. A second portion of
the electromagnetic radiation may be reflected by the beam splitter
520, be focused by a cylindrical lens 530 and impinge a focus
detector 550. The quadrant detector 550 may further include a
plurality of quadrant detectors A, B, C and D, collectively
referenced by 560. The focus detector 540 may include plurality of
quadrant detectors E, F, G and H, collectively referenced by
570.
[0111] In example embodiments, the quadrant detector 550 may
determine a Y-measure using the equation (A+C)-(B+D), the timing of
the rotor scanner using the equation (A+B)-(C+D) and the enable of
the rotor scanner using the equation (A+B+C+D). The focus detector
540 may determine the focus of the beams emitted by the writing
units using the equation (E+H)-(F+G). The focus detector 540 may be
any suitable device for measuring de-focus using, for example, an
astigmatic (on axis) optical system. The astigmatism is added using
the cylindrical lens 540. The cylindrical lens 540 adds power along
an axis perpendicular to the axis of rotation of the cylinder. The
axis of the cylinder may be tilted such that that the cylinder
passes through centers of, for example, detectors E and H.
[0112] Using the cylinder lens, an imaging system with two
different powers may be realized. In one direction (D1), where the
cylinder adds its power, and another direction (D2), where it does
not.
[0113] When the focus position matches the power of D1, a line
image passing through the center of detectors E and H (e.g., along
the axis of the cylinder) is produced. Conversely, if the focus
point position matches the power of D2, line image is produced
along the center of detectors F and G. Thus, the difference
(E+H)-(F+G) is proportional to a position of the focal point.
[0114] The calibration sensor of FIG. 5 may be used to calibrate
focus, power and/or position of the optical writing units. For
example, the focus detector 540 and the position detector 550 in
FIG. 5 may be used to calibrate a focus and position detector in
each optical writing unit. A focus and position detector and each
optical writing unit will be described in more detail with regard
to FIG. 6 below.
[0115] FIG. 6 illustrates an optical writing unit (e.g., a writing
laser diode), according to an example embodiment. The optical
writing unit 600 of FIG. 6 may be used as the optical writing units
740 of FIGS. 7A-7C and/or the optical writing units 840 of FIGS.
8A-8C.
[0116] Referring to FIG. 6, the optical writing unit 600 may
include a digital-to-analog converter (DAC, e.g., a high speed DAC)
610 for transforming pattern data into modulation signals for the
blue laser diode 660. The pattern data may be received via a data
channel (not shown). The data channel may be, for example, a
fiber-optic cable, a radio-frequency (RF) link passing through the
center of the HF transformer, or any other suitable data channel
capable of providing higher data rates, such as, 200 Gbits/s, 400
Gbits/s, 500 Gbits/s, etc.
[0117] The modulation signals generated by the DAC 610 may be
output to a power controller 620. The power controller 620 may
control the power of a blue laser 660 based on the modulation
signals from the DAC 610 and power control signals output by a
power detector 630. The blue laser 660 may emit electromagnetic
radiation (e.g., blue laser beam) for patterning the workpiece 665
based on power control signals output from the power controller
620. The blue laser output from the blue laser 660 may pass through
a lens assembly 670, which may make the beam telecentric. After
passing through the lens assembly 670, the telecentric blue laser
may be incident on a beam splitter 680. The beam splitter 680 may
direct a portion (e.g., a relatively small portion) toward the lens
assembly 650. The remaining portion of the blue laser beam may pass
through the beam splitter 680 and be focused on the workpiece by
the focus lens assembly 690.
[0118] The redirected portion of the blue laser beam may be focused
by the lens assembly 650, pass through red block 640 and be
incident on the power detector 630. The power detector 630 may
detect the power of the incident blue laser light, and output a
power control signal indicative of the detected laser power. The
red block 640 may block (e.g., reflect, absorb, etc.) all, or
substantially all, red laser light incident thereon.
[0119] A red laser diode 655 may also emit electromagnetic
radiation in the form of red laser beam. The red laser beam may be
used for positioning, focus control and/or determining shape of the
workpiece. In at least one example embodiment, the red laser beam
may pass through a telecentric lens assembly 645 and be incident on
a beam splitter 615. The telecentric lens assembly 645 may be the
same or substantially the same as the telecentric lens assembly 670
discussed above. Thus, for the sake of brevity, a detailed
discussion will be omitted. A beam splitter 615 may transmit the
red laser beam to the beam splitter 680, which may direct the red
laser beam onto the workpiece 665. The red laser beam may be
reflected by the workpiece 665 back toward the beam splitter 680,
which may relay the red laser beam toward the beam splitter 615.
The beam splitter 615 may direct the red laser light toward the
focus and position detector 685 via cylindrical lens 635 and/or
blue laser block 625. The blue laser block 625 may block (e.g.,
reflect, absorb, etc.) all, or substantially all, blue laser light
incident thereon.
[0120] The focus and position detector 685 may output positioning
signals to a focus Z servo 675. The focus Z servo 675 may receive
the positioning signals from the position detector 685 and
calibration data, and control the position of the lens assembly 690
via a data connection (e.g., a 1 kHz bandwidth data line). For
example, the focus Z servo 675 may move the lens assembly 690 in an
X-direction, Y-direction and/or Z-direction depending on the shape
of the signal from the focus and position detector 685. The control
loop signals may be supplemented by feed forward signals from a
control system (e.g., a computer or processor, not shown) to
correct for known distortions such as focus errors.
[0121] According to at least some example embodiments, a position
and/or form of the workpiece may be determined using laser diodes
having a wavelength not affecting the electromagnetic radiation
sensitive layer on top of the workpiece. In at least some examples,
blue laser diodes may affect the electromagnetic radiation
sensitive layer and red laser diodes may be used for measurement of
the position and form of the workpiece. Laser diodes exposing the
workpiece and laser diodes used for measurement and not affecting
the electromagnetic radiation sensitive layer may be arranged in
the writing head (rotor).
[0122] FIG. 13 is a more detailed illustration of an auto focus
arrangement of an optical writing unit for focusing and position
(or displacement) determination, according to an example
embodiment. Emitted electromagnetic radiation (e.g., a laser beam)
from a laser diode 1310 enters a lens assembly 1330, which
telecentrizes the beam. The telecentric beam may impinge on a beam
splitter 1340, which directs the beam toward a lens assembly 1350.
The lens assembly 1350 may focus the beam onto the workpiece 1370.
A cover glass 1360 may be arranged between the lens assembly 1350
and the workpiece 1370 to protect the lens assembly 1350. When the
beam impinges on the workpiece 1370, the beam may be reflected back
through the lens assembly 1350 to the beam splitter 1340. The beam
splitter 1340 may direct the reflected beam onto the detector 1320
for detecting the focus of the laser beam. The detector 1320 may
detect the focus of the laser beam in any suitable well-known
manner. Because methods for detecting focus of a laser are
well-known in the art, a detailed discussion will be omitted for
the sake of brevity. The lens assembly 1350 may be moved in any
direction based on the read out of the detector 1320.
[0123] Referring back to FIG. 6, each optical writing unit 600 may
have a set value for each of the power, position and focus
parameters. When the optical writing unit 600 passes the
calibration sensor of FIG. 5, the optical writing unit 600 obtains
data as to how each set parameter value correlates to a parameter
value (e.g., power, position and/or focus value) measured by the
calibration sensor. The error or difference between the set values
stored in the optical writing units 600 and the measured values is
sent to the writing head for adjustment, for example, to offset the
writing head's internal scale. This adjustment may be done, for
example, each time each optical writing unit passes a calibration
sensor. However, the adjustment may be performed less often.
[0124] According to example embodiments, the calibration of power,
focus and/or position (x,y, where x is done by time delay) may be
in different calibration sensors, so long as the calibration source
of each focus, power and position is common. That is, for example,
power, focus and/or position may be calibrated using a different
calibration sensor so long as each writing head uses the same
calibration sensor for focus, the same calibration sensor for
power, and the same calibration sensor for x position and the same
calibration sensor for y-position. Power may be measured in a
wavelength dependent manner to compensate for variation of
wavelength sensitivity of the resist.
[0125] FIG. 30 illustrates a calibration system, according to
another example embodiment. As shown, the calibration system may
include a detector 3100, a control unit 3102 and a writing head
3104. The detector 3100 may be, for example, a calibration sensor
(e.g., as discussed above with regard to FIG. 5) or any other
optical detector capable of detecting, for example, focus, power
and/or position of one or more optical writing units. The control
unit 3102 may be implemented, for example, in the form of software
executable on a computer or processor. The writing head 3104 may be
a writing head including a plurality of optical writing units, one
or more of which may be an optical writing unit as described above
with regard to FIG. 6. However, the writing head may be any writing
head capable of exposing a workpiece and/or generating a pattern on
a workpiece. Each of the detector 3100, the control unit 3102
and/or the writing head 3104 may be connected via a data channel.
The data channel may be, for example, a fiber-optic cable, a
radio-frequency (RF) link passing through the center of the HF
transformer, or any other suitable data channel. An example
operation of the calibration system of FIG. 30 will be described
with regard to FIG. 31.
[0126] FIG. 31 illustrates a calibration method, according to an
example embodiment. As discussed above, the method of FIG. 31 may
be performed, for example, by the calibration system of FIG. 30.
The method of FIG. 31 may also be performed by one or more
calibration sensors (e.g., 400 of FIG. 4) in connection with one or
more writing heads (e.g., 430 of FIG. 4). In these examples, the
control unit 3102 may correspond to, for example, the power control
unit 620 and the focus Z servo 675 of FIG. 6, and the detector 3100
may correspond to the quadrant detector 550 of FIG. 5, the focus
detector 540 of FIG. 5 and the power detector 630 of FIG. 6. In the
example embodiment shown in FIG. 30, the quadrant detector 550 of
FIG. 5, the focus detector 540 of FIG. 5 and the power detector 630
of FIG. 6 may be located at the detector 3100, and the power
control unit 620 and the focus Z servo 675 may be located at the
control unit 3102. Alternatively, however, other configurations are
possible.
[0127] Referring to FIG. 31, at S3110, when an optical writing unit
of the writing head 3104 passes the detector 3100 may detect at
least one characteristic of the optical writing unit. For example,
the detector 3100 may detect characteristics, such as, focus,
position and/or power of electromagnetic radiation (e.g., the laser
beam) emitted from the optical writing unit. The detector 3100 may
send the at least one detected characteristic to the control unit
3102.
[0128] At S3112, the control unit 3102 determines a correlation
between the detected characteristics and a corresponding set
parameter value. For example, a detected focus characteristic may
be compared with a set focus parameter value, a detected power
characteristic may be compared with a set power value and/or a
detected position characteristic may be compared with a set
position value. The set parameter values may be set, for example,
by a human operator, based on empirical data. In at least one
example embodiment, the correlation associated with each detected
characteristic and corresponding set parameter value may be an
error or difference between the set value and the measured
characteristic value. The set parameter values may be stored in a
memory at the control unit 3102. The memory may be any suitable
storage medium, such as, a flash memory or the like.
[0129] At S3114, the control unit 3104 may adjust the writing head
based on the determined correlation. For example, the determined
correlations may be used to offset the internal scale of the
writing head 3104.
[0130] Although only a single iteration of this method is shown in
FIG. 31, the operation described therein may be done, for example,
each time each optical writing unit passes a calibration sensor.
However, the adjustment may be performed less often.
[0131] FIGS. 8A-8C illustrate different implementations and
orientations of a ring-type writing apparatus, according to another
example embodiment.
[0132] Referring to FIG. 8A, the writing apparatus may include a
holder (e.g., a cylindrical stage or tube formed holder) 810, a
rotor scanner 830 and/or at least one optical writing units 840. A
workpiece 820 may be arranged on the outside of the holder 810. The
workpiece 820 may be fixed onto the holder 810 using, for example,
vacuum nozzles 850. The rotor scanner 830 may rotate outside the
workpiece holder 810 and optical writing units 840 may emit
radiation in a radial direction inward toward the central axis of
the holder 810. In example embodiments, the optical writing units
may be, for example, 840 may be, for example, single point laser
diodes, multi-point laser diodes or spatial light modulators
(SLMs). The laser diodes may be of any commercial available
wavelength such as blue, red, violet, etc. The power of a laser
diode may be, for example, about 5 mW to about 65 mW, inclusive,
for single mode, and about 5 mW to about 300 mW for multimode
diodes. An electro-optical efficiency of a laser diode may be, for
example, 13%. The laser diodes may act as an optical power source
and a modulator, for example, simultaneously. The spatial light
modulators (SLMs) 840 may be at least partially transmissive
spatial light modulators, and may create stamps or patterns 860 on
the workpiece 820. SLMs are well-known in the art, and thus, a
detailed discussion will be omitted for the sake of brevity. As
shown in FIG. 8A, the central axis of the workpiece holder 810 may
be oriented horizontally.
[0133] Still referring to FIG. 8A, in operation, the ring rotor
scanner 830 may rotate around the central axis of the holder 810
and move in an axial direction relative to the holder 810 and
parallel to the central axis of the holder 810. In addition, the
holder 810 may rotate around its central axis in a rotational
direction opposite to that of the ring rotor scanner 830.
[0134] FIG. 8B shows an example embodiment including a stationary
cylindrical holder 810 holding a wrapped workpiece 820, and a
rotating writing head 830. Referring to FIG. 8B, the workpiece
holder includes a slit 870 in which a calibration sensor 850 is
arranged. The calibration sensor 850 may be movable or fixed. The
writing head 830 includes a plurality of optical writing units 840
creating patterns 860 on the workpiece 820. An alignment camera 880
may capture an existing pattern on the workpiece 820 such that a
written pattern may be aligned with higher accuracy, thereby
increasing overlay precision.
[0135] FIG. 8C shows an example embodiment including a rotating
cylindrical holder 810 holding a wrapped workpiece 820, and a
stationary writing head 830. The writing head 830 may include a
plurality of optical writing units 840 creating patterns 860 on the
workpiece 820. The optical writing units 840 of FIG. 8C may be the
same or substantially the same as the optical writing units 840 of
FIG. 8A. As is the case with respect to FIG. 8B, the writing head
830 may include multiple writing units 840, although, for the sake
of clarity, only one writing unit 840 is illustrated.
[0136] FIG. 9 shows a horizontal orientation of a cylindrical stage
or holder 910, according to an example embodiment. When loaded
horizontally, a workpiece 920 may be kept in place by gravitational
force. The workpiece 920 may be held in place by a vacuum to ensure
that the surface follows the surface of the cylinder 910 closely.
The ends of the workpiece 920 may be fastened securely to the
cylinder by a latch 930. The latch 930 may be controlled to capture
or release the edge of the workpiece 920.
[0137] The workpiece may be pushed or pulled onto or into the
cylindrical support surface to assume the proper shape. In another
example, a vacuum clamp or any other suitable clamp may also be
used. The edges along the cylindrical part may bend locally away
from the center or curvature (e.g., similar to bending an eraser).
This bending may be restrained by a fixture system (e.g., a vacuum
fixture system).
[0138] FIG. 21 shows a vacuum arrangement for holding the workpiece
on the cylinder. As shown, vacuum and pressure devices may be
alternately arranged. A push-pull vacuum clamping system may be
used to counteract workpiece deformation in the x-y plane. As shown
in FIG. 21, the system may have pressure and vacuum holes spaced
closer together (e.g., on a millimeter scale). The vacuum holes may
hold the workpiece and reduce the deformation, and the pressure
pads may keep the workpiece away from the supporting surface. The
workpiece may not touch the support surface, and may be supported
at a few .mu.m (e.g., 1, 2, 10, 20, etc. .mu.m) away from the
support surface. This may allow the workpiece to more freely assume
natural shape in the plane of the workpiece. The vacuum arrangement
of FIG. 21 or an arrangement similar or substantially similar
thereto may be used in conjunction with each example embodiment
described herein.
[0139] FIG. 10 illustrates a workpiece 1020 in a flat state, as may
be patterned in at least some example embodiments.
[0140] FIGS. 11A-11K illustrate a plurality of (e.g., eleven)
different positions of a writing head in relation to the direction
of the rotor scanner relative to the glass. The arrow in FIG. 11
represents the scanning direction.
[0141] FIGS. 11A-11C show dense matrices of pixels, for example,
images of a rectangular spatial light modulator with the rows and
columns of the array aligned with the sides of the rectangle. FIG.
11A illustrates an SLM in which a pixel grid is parallel, or
substantially parallel, to the writing direction. FIG. 11B
illustrates an SLM pixel grid, which is tilted relative to the
writing direction. FIG. 11C illustrates an SLM pixel grid, which is
tilted relative to the writing direction, the tilt in FIG. 11C
being less than as compared to the tilt of the pixel grid axis in
FIG. 11B.
[0142] FIGS. 11D-11F show images of a dense matrix with the array
rotated relative to the SLM sides, for example, by 0.degree.,
45.degree. and a third angle. The third angle may be an angle other
than 0.degree., 45.degree. or 90.degree.. FIG. 11D illustrates an
SLM with a pixel grid slanted 45.degree. with respect to the
writing direction. In example embodiments, the pixel grid may not
be parallel with the edges of an outer edge of an SLM chip as in
FIG. 11A-11C.
[0143] In FIG. 11E the SLM chip is shown slanted such that one of
the axes in the pixel grid may be parallel, or substantially
parallel, to the writing direction.
[0144] In FIG. 11F the SLM chip may be slanted so that the neither
the outer edge of the SLM chip nor any one of the pixel grid axis
are parallel, or substantially parallel, to the writing direction.
The axes of the sides of the matrix of pixels (e.g., an SLM) and/or
the axes of the pixel grid may be rotated with respect to the axes
of movement during writing and/or the axes of the written pattern,
thus providing, at least four sets of coordinate directions as will
be described below with regard to FIGS. 12B-12D.
[0145] FIG. 11G shows a relatively sparse matrix skewed or rotated
so that the rows fall at different positions during scanning. In
example embodiments, the area may be filled in one or several
scans. In FIG. 11G a plurality of laser diodes (e.g., five lines
and/or five rows) slanted to the writing direction.
[0146] FIG. 11H shows relatively a sparse row of pixels, for
example, a plurality of (e.g., three) laser diodes may be arranged
orthogonal to the writing direction. If utilizing the example
embodiment shown in FIG. 11H, multiple passes may be required to
fill a desired area.
[0147] FIG. 11 shows a relatively dense row of pixels, for example,
an image of a one-dimensional SLM in which a plurality of (e.g.,
seventeen) laser diodes may orthogonal to the writing
direction.
[0148] FIGS. 11J and 11K show single rows with the pixels displaced
in the scanning direction. FIG. 11J illustrates a plurality of
(e.g., twelve) laser diodes in a row slanted to the writing
direction. FIG. 11K illustrates a line of a plurality of (e.g.,
seventeen) laser diodes slanted to the writing direction according
to an example embodiment.
[0149] A common problem with optically written patterns, as well as
with inkjet-printed ones is the formation of "Mura." The formation
of Mura refers to the formation of visible bands or patterns due to
the visibility of the fields or stripes and/or due to moire effects
between the pattern and the writing mechanism. "Mura" is an issue
for image devices (displays and cameras) but not for other
laser-written patterns such as PCBs and PCB masks.
[0150] At least some example embodiments provide a method for
assembling optical fields to a display pattern by repetition along
an x and a y axis. The fields may be, for example, SLM fields, an
SLM pixel pattern, or an array of pixels formed by another writing
mechanism such as an array of diodes.
[0151] As discussed above with regard to FIG. 12A, the arrangement
according to the conventional art is used in higher-precision
pattern generators and may produce acceptable levels of "Mura"
defects. However, example embodiments provide writing systems
having 10, 100, or even 1,000 times higher throughput than
conventional pattern generators, but with essentially the same or
substantially the same "Mura" reduction requirements. Higher speed,
larger pixels, multiple writing units and/or multiple writing
heads, may contribute to more geometrical errors in the written
pattern. As will be described in more detail with regard to FIG.
12B-12D, the pattern and the axes of the writing head may be
rotated relative to each other, such that a single pixel is not
repeatedly printed on the edge of adjacent pixels. Furthermore, the
axes between the movement system and the pixel grid created by the
writing units may be rotated relative to each other. The pattern
may be aligned with the movement axes, the pixel grid or neither.
The rotation may be an angle different from 0, 45 and
90.degree..
[0152] As discussed above with regard to FIG. 12A, the rotation
direction is parallel to a side of the SLM chip in the conventional
art.
[0153] FIGS. 12B-12E show example embodiments, which may suppress
the occurrence of Mura and/or weaken the effects of Moire in the
pattern. As shown, in example embodiments, the pattern may be
rotated relative to the axes of the writing mechanism and/or the
movement system (e.g., scanning direction of the SLM).
[0154] For example purposes, FIGS. 12B-12E will be described with
regard to an SLM pattern. However, similar principles apply to
other example embodiments, such as, any suitable writing unit.
[0155] In FIG. 12B, the workpiece may be wrapped onto the workpiece
holder, and may not be in parallel with the central axis of the
workpiece holder. The SLM, or more generally the writing unit, may
be arranged in the rotor scanner with an outer side of the SLM
chip, or more generally the axes between the pixels formed in the
pattern by the writing unit, in parallel, or substantially
parallel, with the scanning direction. For example, the scanning
direction and the SLM field are aligned, while the workpiece is
rotated relative to the scanning direction and the sides of the SLM
pattern. With this rotation of the workpiece, the effect of a
stitching artifact no longer accumulate along a single line of the
device but will pass from line to line, spreading the disturbance
to many lines. In addition, a Moire pattern, which is really an
intermodulation product between frequency components of the pattern
and the writing mechanism (e.g. display pixels and laser scanner
pixels), may be relocated to a higher frequency that is less
visible in the finished display.
[0156] In FIG. 12C the SLM chip, or a similar pixel map formed by
the writing units, may be arranged in the rotor scanner with at
least coordinate axes non-parallel to the rotational direction. The
workpieces may be arranged with an axis of symmetry in parallel to
the central axis of the workpiece holder.
[0157] In FIG. 12D all three coordinate systems are non-parallel to
each other. Together with FIG. 11 it is possible to define four
coordinate systems, which may be rotated relative to each other.
Two, three or four coordinate systems may be made oblique relative
to each other in order to reduce "Mura" effects, while all four
parallel defines the prior art.
[0158] In FIG. 12E, the workpiece is rotated, the writing SLM field
is rotated and intentional distortion is introduced.
[0159] An angle between the sides of the SLM pattern and the
workpiece for reducing Mura effects may be greater than or equal to
about 0.01 radians (e.g., between about 0.01 and about 0.05
radians, inclusive). The angle used, however, may depend on the
write mechanism, scale and/or type of the pattern. The angle may be
adjustable from one writing job to the next, or on the other hand,
fixed and built into the writing hardware.
[0160] FIGS. 24A-E illustrate methods for continuous scanning in
the x and y directions, according to an example embodiment.
[0161] FIG. 24A shows an array of pixels in the x-direction along
the tool axis. The array may move with a constant speed and after
the cylinder rotates one turn, the array stitches to the printed
pattern. If the array is not sufficiently dense, the scanning speed
may be reduced to, for example, half so that two turns are needed
to move the width of the array. The scanning speed may also be
reduced more or less depending on the density of the array. The
array may be parallel or not parallel to the tool axis.
[0162] FIG. 24B shows another method for patterning, according to
an example embodiment, in which the array is not parallel to the
tool axis.
[0163] In FIG. 24C, an array parallel to the y-axis of the
workpiece and perpendicular to the tool axis. In this example
embodiment, the surface of the workpiece is patterned by continuous
scanning in the x and y directions.
[0164] FIG. 24D shows an example embodiment in which an array is
less dense then those illustrated in FIGS. 24A-24C. In this
example, a second array is needed to fill voids in the less dense
array. The second array may be a physical array or the same array
in a later pass.
[0165] FIG. 24E shows two passes on top of each other. A first of
the two passes scans to the right, and a second of the two passes
scans to the left. The simultaneous scanning of x and y may provide
an oblique angle and the two passes may have opposite angles. This
may reduce visibility of resultant stripes. The two passes may be
written sequentially with the same pixel array, or with two pixel
arrays moving in opposite x-directions, for example,
simultaneously. The two pixel arrays may be two physical write
heads arranged on two different toolbars. The system shown in, for
example, FIG. 25 with continuous scanning in x and reciprocating
scanning in y may be used to write two passes in a single
operation.
[0166] As described above, the oblique writing is possible and
indeed natural for a writing system with cylindrical motion.
However, oblique writing is also beneficial in flat-bed writers,
such as will be described in more detail below.
[0167] FIG. 22 illustrates a writing apparatus, according to
another example embodiment. As shown, the writing apparatus may
include a rotor scanner 2200 for generating a pattern on a
workpiece 2202. The example embodiment shown in FIG. 22 may be
similar or substantially similar to the example embodiment shown
in, for example, FIGS. 1, 7A, 7B and/or 7C, however, the example
embodiment shown in FIG. 22 may further include a workpiece shape
controller 2204. The workpiece shape controller 2204 may scan in
the same direction as the rotor scanner 2200. In at least one
example embodiment, the workpiece shape controller may scan the
workpiece 2202 such that the workpiece shape controller 2204 and
the rotor scanner stay in constant horizontal alignment.
[0168] FIG. 15 is a perspective view of a writing apparatus,
according to another example embodiment. The rotor scanner of FIG.
15 may be used to pattern a flat workpiece, such as the workpiece
shown in FIG. 10.
[0169] Referring to FIG. 15, the rotor scanner 1520 may include a
plurality of optical writing units (not shown) arranged on a flat
portion (e.g., a top and/or bottom surface) of the rotor scanner
1520. The plurality of optical writing units may be arranged such
that they emit electromagnetic in an axial direction relative to
the rotor scanner 150. In at least one example embodiment, the
optical writing units may be arranged around the outer edge of the
bottom of the rotor scanner 1520. As shown, the rotor scanner 1520
may rotate and/or move along the surface of a workpiece 1510. The
width of the rotor scanner 1520 may cover the width of the
workpiece 1510. In example embodiments, the rotor scanner may scan
the workpiece in a varying direction, and may form a relatively
shallow and/or run across the workpiece at an angle such that the
arc is not tangent to 0, 45 or 90 degrees. This geometry may be
used with thicker and/or non-bendable masks.
[0170] FIG. 17 is a top view of writing apparatus shown in FIG. 15.
Referring to FIG. 17, the diameter D of the rotor scanner 1520 is
narrower than the width of the workpiece 1710. In example
embodiments, the rotor scanner may track or scan back and forth
over the workpiece 1710 so as to cover the entire workpiece 1710.
In example embodiments, the rotor scanner 1520 may write
continuously regardless of which direction the rotor scanner is
moving. In an alternative example embodiment, the rotor scanner may
write in a single direction.
[0171] FIG. 18 is a top view of a portion of a writing apparatus,
according to another example embodiment. The example embodiment of
FIG. 18 may be similar or substantially similar to the example
embodiment discussed above with regard to FIG. 17, however, the
example embodiment of FIG. 18 may include at least two rotor
scanners 1810 and 1815. In example embodiments, the rotor scanners
1810 and 1815 may pattern the same workpiece 1820, for example,
simultaneously.
[0172] FIG. 19A illustrates a side view of a rotor scanner
according to an example embodiment, and FIG. 19B illustrates a top
view of the rotor scanner shown in FIG. 19A. In the example
embodiment shown in FIGS. 19A and 19B, the diameter D of the rotor
scanner 1520 is greater than the width of the workpiece. The rotor
scanner of FIGS. 19A and 19B may track laser diodes at a side of a
workpiece in parallel with the workpiece motion. This tracking or
scanning illustrated in FIGS. 19A and 19B may result in a higher
dose at the sides of the workpiece than the dose in the middle of
the workpiece, given that the dose of the laser diodes is the same.
This may be compensated for by increasing the dose of the diodes
and/or pixels when patterning the center part of the workpiece.
[0173] FIG. 16 is a perspective view of a writing apparatus,
according to another example embodiment.
[0174] Referring to FIG. 16, the writing apparatus may include a
circular stage 1630 on which a workpiece 1610 may be fixed. A
writing head 1620 may be arranged so as to span at least the
diameter of the circular stage 1630. The writing head 1620 may
include a plurality of optical writing units (not shown) arranged
on a surface portion of the writing head, such that electromagnetic
radiation emitted by the optical writing heads impinges on the
workpiece 1610 during writing. In example operation, the circular
stage, and thus, the workpiece 1610 may rotate while the writing
head 1620 moves perpendicular to the rotational axis of the
circular stage 1610.
[0175] FIG. 23 is a more detailed illustration of the pattern
generator shown in FIG. 16.
[0176] FIG. 20 illustrates a non-Cartesian coordinate system in a
rotor scanner, according to an example embodiment. For example, the
coordinate system may be bent. In this example, a memory mapping
may be performed before, during or after patterning to transform
pixels in the Cartesian grid to pixels in the bent coordinate
system defined by the rotating pixels relative to the workpiece.
For each circle created by a single pixel in the writing head a
transformation may be made from a Cartesian grid into the bent
coordinate system
[0177] FIGS. 25-28 illustrate flatbed platforms, according to
example embodiments.
[0178] FIG. 25 illustrates a flatbed platform, according to an
example embodiment. The platform shown in FIG. 25 may be a
lightweight frame, shown for example purposes as a truss. However,
example embodiments may be built with thin walled tubes that may be
temperature controlled by fluid (e.g., air, water and/or gas)
flowing within the tubes. The frame may provide a more rigid
support for a stationary stage top. Writing heads (e.g., mechanical
units holding writing optics) may be arranged on mechanical support
structures, herein referred to as tool bars, near the surface of
the workpiece. At least one toolbar may extend across the stage.
Each of the toolbars may include one or more tools (e.g., writing
heads). The tools may be mounted or arranged in a similar or
substantially similar manner to that as described above with regard
to the cylindrical stage. The toolbars may have fixtures or tools
(e.g., which may be standardized). The number of toolbars and the
tools attached to each toolbar may be configured according to the
application and/or need for capacity.
[0179] FIG. 25 shows how toolbars 2501 access any point on the
workpiece 2503, and how the toolbars may be moved out of the way
for loading and unloading. The platform of FIG. 25 may include a
linear motor 2504 for driving the toolbar assembly 2506. The linear
motor may be attached to a rod 2502 extending between supports 2508
and 2510 standing separately on the floor. A freely moving counter
mass (not shown) may be used so that neither part of the linear
motor is connected to the ground. The linear motor may move the
toolbar assembly 2506 and the counter mass by applying a force
there between, while keeping a common, stationary center of
gravity.
[0180] A separate system including the motor applying a weak force
between the ground and the counter mass may keep the counter mass
centered within a range of movement.
[0181] The moving stage may slide on bearings (e.g., air bearings)
and may hold the workpiece using, for example, vacuum,
electrostatic force or any other suitable clamping mechanism. The
moving stage may more accurately monitor and/or control the
position of the stage relative to the coordinate system of the
machine. The platform of FIG. 25 may be suitable for many
processes, such as, metrology, patterning, etc.
[0182] FIG. 26 illustrates a flatbed platform, according to another
example embodiment. The example embodiment shown in FIG. 26 may be
similar or substantially similar to the flatbed platform of FIG.
25; however, the flatbed platform of FIG. 26 may include a
different number of toolbars (e.g., five toolbars) mounted in a
fixed position. In this example embodiment, the workpiece 2601
shuttles back and forth on a light-weight shuttle 2602.
[0183] Referring to FIG. 26, the stage may be relatively
lightweight similar or substantially similar to the shape of the
support. The stage may be driven by linear motor and the reaction
force from the motor is isolated from the support of the stage
either by separate connections to the ground or by a counter mass.
The stage may slide on bearings (e.g., air bearings) and may hold
the workpiece using vacuum, electrostatic force or any other
suitable clamping mechanism.
[0184] FIG. 27 illustrates another example embodiment in which the
workpiece 2701 passes under the tool bars and may be patterned in
passing. The workpiece may be in the form of cut sheets or a
roll-to-roll endless band. As discussed above, patterning may
involve exposure of photoresist, patterning of thermally sensitive
resists of films, any photoactivation of the surface, ablation,
thermal transfer or any similar processes using reaction to photon
energy and/or heat of a light beam. According to at least some
example embodiments, light refers to any electromagnetic radiation
with a wavelength from EUV (e.g., down to 5 nm) to IR (e.g., up to
20 microns).
[0185] FIG. 28 shows an example operation of a flatbed platform for
higher-speed patterning of workpieces, according to an example
embodiment. For example purposes, this example operation will be
described with regard to FIG. 26; however, other flatbed platforms,
according to example embodiments, may operate in similar or
substantially similar manners. The platform may have the same or
substantially the same type of lightweight board frame and a
floating lightweight stage, hereinafter referred to as a "shuttle,"
2804.
[0186] Referring to FIG. 28, in example operation, the shuttle 2804
may oscillate (e.g., bounce) between counter masses 2802 positioned
at each end of the support 2806. The counter masses 2802 may freely
move between position A and B via slides 2810, but may be affected
by the force of the linear motor. When the shuttle 2804 impacts or
hits against a counter mass 2802 the shuttle 2804 loses at least a
portion of kinetic energy. The force during the impact may be
controlled by spring constants of springs 2812 compressed during
the impact. At an end of each stroke, the shuttle 2804 impacts the
counter mass 2802. The counter masses 2802 may be joined by a fixed
rod 2814 or controlled individually by one or more linear
motors.
[0187] A linear motor may also be positioned, for example, under
the shuttle 2804 and may accelerate the shuttle 2804 toward a first
impact when the shuttle 2804 begins moving. The liner motor may
also be used to move and stop the shuttle at any position, and/or
maintain a constant or substantially constant speed during
scanning. The shuttle may operate at a constant speed, moving, for
example, to the left or to the right in FIG. 28. The stiffness of
the springs 2812 may be selected such that the maximum acceleration
is within a desired range, such that the workpiece does not slide
on the stage and such that excessive vibrations are not generated
in the stage.
[0188] In at least some example embodiments, the stage may be
comprised of, for example, a leaf spring with pads floating on the
support structure and other pads holding the workpiece. With a
flexible light-weight shuttle the shape of the stage may be
determined by the shape of the supporting surface.
[0189] FIG. 29 shows a diagram over the position of the stage and
the counter masses during scanning. FIG. 29 also shows the position
of the tool scanning at a constant speed in the direction
perpendicular to the paper. When the stage is scanning to the right
an oblique line is traced by the tool across the workpiece and
after the bounce and other oblique line is traced with a different
angle. With the proper relation between the tool width, the stage
speed, and the tool speed two contiguous passes may be written on
top of each other. Both passes may have stripes inclined to the
scanning axis of the stage which may reduce periodic defects in a
pattern as shown.
[0190] If the workpiece is about 2.8 m long, accelerating at about
10 g during bounce, and moving at a constant speed of about 6 m/s
otherwise, the average scanning speed including bounce-time is
approximately 5 m/s. Momentum may be transferred between the
counter masses 2802 and the stage, none of which are connected to
the supporting structure or to the floor. After the bounce counter
mass 2802 recedes with a speed significantly lower than the stage,
the linear motor may reduce the speed and reverse the velocity of
the counter mass until the next impact with the same counter
mass.
[0191] If the counter masses 2802 are connected by a rod, or
alternatively, if a single counter mass is arranged at the center
of the stage is used, the demands on the linear motor may be
reduced. In this example, bounces at each end reverse the velocity
of the counter mass(es), and the movement of the counter mass may
be similar or substantially similar to that of the stage, except
slower and with less range.
[0192] In one or more example embodiments, patterns may be written
on workpieces (e.g., glass sheets, plastic sheets, etc.) used in,
for example, electronic display devices such as LCDs. In these
example embodiments, a workpiece larger than about 1500 mm may be
used. An optical writing head (e.g., a rotor scanner) with a
plurality of writing units (e.g., greater than or equal to 5) may
be used. A data channel with a data rate (e.g., greater than or
equal to 100, 200, 400 Gbits/s, etc.) may provide data, and the
workpiece and the optical writing head (or rotor scanner) may be
rotated relative to one another in at least one direction. The
workpiece and the writing head may also be moved relative to one
another in a plane, for example, between 45 and 135 degrees
relative to the plane of rotation. For example, in at least one
example embodiment, the plane of rotation may be perpendicular to
the plane of movement.
[0193] Although example embodiments have been described with regard
to workpieces, it will be understood that workpieces may be used
interchangeably with workpiece. In addition, writing apparatuses,
according to example embodiments, may be used in conjunction with
conventional pattern generation systems.
[0194] According to at least some example embodiments, the written
pattern is not sub-divided into stripes. In at least some example
embodiments with non-interfering pixels (e.g., FIG. 1 and FIGS.
11G-11K) an image may be built from parallel lines extending from
one side of the workpiece to the other.
[0195] In some example embodiments, (e.g., FIG. 1), the lines may
be written from edge to edge and in sequence by the writing units.
Two adjacent lines may be written by two adjacent writing units
thereby reducing (e.g., minimizing ) the risk of the workpiece
and/or writing head moving by drift and/or mechanical movement from
one line to the next. The sequentially written edge-to-edge pattern
local errors may be reduced and "Mura" effects may be reduced.
[0196] In an example embodiment similar to FIG. 1, but including
more than one ring of writing units (e.g., FIG. 7A) or with an
arrangement of writing units or non-interfering pixels as shown,
for example, in FIG. 11G-11K the lines may not be sequentially
written. However, with multiple writing units distributed around
the perimeter of the cylinder, two adjacent lines may still be
written by writing units in proximity to one another on the
perimeter of the writing head (e.g., within 90.degree. from each
other and in relatively close time proximity). In addition,
multiple writing units distributed around the perimeter of the
cylinder may still limit the freedom for drift and/or vibration
between the lines.
[0197] In example embodiments using SLMs to form simultaneously
contiguous arrays of pixels (e.g., one-dimensional (1D or
two-dimensional (2D)) adjacent arrays may be written sequentially
and/or in close proximity in time, thereby reducing the stitching
areas between the pixel arrays (SLM stamps). Helical scanning with
multiple writing units, together with the calibration of writing
units against the same calibration sensor, may reduce mismatch
between the images from the writing units, whether the images are
single points, clusters of non-interfering pixels or dense areas of
pixels (SLM stamps).
[0198] As shown in FIG. 1B, lines traced by the writing units may
be oblique relative to the workpiece. This can be corrected if the
workpiece is rotated on its support. However, as described above,
obliqueness may be used to reduce "Mura" effects, and thus, an
increase in the obliqueness of the traced lines may be desirable. A
pixel pattern is defined by the scan lines and may be rotated
relative to the axes of the pattern, for example, the pixel pattern
of the display devices.
[0199] A third coordinate system is defined by the movement of the
writing head and the rotation/shuttle movement. If the oblique
angle between the pixel grid is changed by rotation of the
workpiece on the cylindrical support, all three coordinate systems
are rotated relative to each other. In other example embodiments
only two of the three coordinate systems are oblique to each
other.
[0200] FIG. 1C illustrates images created by an SLM during
scanning. As shown, the images in FIG. 1C are also rotated relative
to the workpiece. As discussed in relation to, for example, FIGS.
11A-11K and/or FIGS. 12A-12E, in this example embodiment, four
coordinate systems exist and two, three or all four may be rotated
relative to each other to reduce "Mura" effects in the written
pattern. Reduction of "mura" by rotation of the various coordinates
systems may be used while scanning either cylindrically or in a
flat-bed stage. In the circular stages shown in FIG. 15 and/or FIG.
16 the coordinate system of the movements rotate during the stroke
from edge-to-edge thus creating a local but non-constant rotation
between the coordinate systems.
[0201] The helical scanning may be implemented by rotating the
workpiece, the writing head, or both, and the workpiece can be
inside or outside of the writing head.
[0202] While example embodiments have been described with reference
to the example embodiments illustrated in the drawings, it is
understood that these example embodiments are intended in an
illustrative rather than in a limiting sense. It is contemplated
that modifications and combinations will readily occur to those
skilled in the art, which modifications and combinations will be
within the spirit of the present invention and the scope of the
following claims.
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