U.S. patent application number 13/564085 was filed with the patent office on 2012-11-22 for methods and systems for lithography alignment.
This patent application is currently assigned to TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD.. Invention is credited to Kuei Shun Chen, Hsueh-Hung Fu, Ching-Hua Hsieh, Hung Chang Hsieh, Hsiao-Tzu Lu, Shau-Lin Shue.
Application Number | 20120293782 13/564085 |
Document ID | / |
Family ID | 39775137 |
Filed Date | 2012-11-22 |
United States Patent
Application |
20120293782 |
Kind Code |
A1 |
Lu; Hsiao-Tzu ; et
al. |
November 22, 2012 |
Methods and Systems for Lithography Alignment
Abstract
Methods and systems for lithographically exposing a substrate
based on a curvature profile of the substrate.
Inventors: |
Lu; Hsiao-Tzu; (Hsinchu,
TW) ; Hsieh; Hung Chang; (Hsin-Chu City, TW) ;
Chen; Kuei Shun; (Hsin-Chu, TW) ; Fu; Hsueh-Hung;
(Hsinchu, TW) ; Hsieh; Ching-Hua; (Hsinchu,
TW) ; Shue; Shau-Lin; (Hsinchu, TW) |
Assignee: |
TAIWAN SEMICONDUCTOR MANUFACTURING
COMPANY, LTD.
Hsin-Chu
TW
|
Family ID: |
39775137 |
Appl. No.: |
13/564085 |
Filed: |
August 1, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11686142 |
Mar 14, 2007 |
8236579 |
|
|
13564085 |
|
|
|
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Current U.S.
Class: |
355/53 |
Current CPC
Class: |
H01L 21/67288 20130101;
G03F 7/70783 20130101; G03F 7/70358 20130101; G03F 7/70725
20130101 |
Class at
Publication: |
355/53 |
International
Class: |
G03B 27/42 20060101
G03B027/42 |
Claims
1-8. (canceled)
9. A system for processing a substrate, comprising: means for
determining a curvature profile of the substrate; and means for
lithographically exposing portions of the substrate based on the
curvature profile.
10. The system of claim 9 further comprising means for subjecting
the substrate to a heat treatment process before determining the
curvature profile of the substrate.
11. The system of claim 10 wherein the heat treatment process
comprises at least one of a rapid thermal anneal (RTA) process and
a flash anneal process.
12. The system of claim 10 wherein the heat treatment process
comprises a rapid thermal anneal (RTA) process and a flash anneal
process.
13. A scanner system, comprising: a reticle stage configured to
retain a reticle; a wafer stage configured to retain a wafer; a
projection unit interposing the reticle stage and the wafer stage;
and an illumination source configured to emit light through the
reticle and the projection unit and onto the wafer; wherein at
least one of the reticle stage and the wafer stage is configured to
be positionally adjusted to account for a curvature profile of the
wafer.
14. The scanner system of claim 13 further comprising a wafer
curvature profiler configured to determine the curvature profile of
the wafer.
15. The scanner system of claim 14 further comprising a conveyor
configured to transport the wafer from the wafer curvature profiler
to the wafer stage.
16. The scanner system of claim 15 wherein the wafer curvature
profiler is remotely located from the wafer stage.
17. A system comprising: a reticle stage configured to support a
reticle; a wafer stage configured to support a wafer; an
illumination source configured to emit light through the reticle
and onto the wafer; and a curvature profile module operable to
determine a curvature profile of the wafer prior to the
illumination source emitting light through the reticle and onto the
wafer.
18. The system of claim 17, further comprising a controller
operable to receive the determined curvature profile of the wafer
and to control movement of at least one the reticle stage and the
wafer stage to account for the determined curvature profile of the
wafer.
19. The system of claim 18, wherein the controller is operable to
control movement of both the reticle stage and the wafer stage to
account for the determined curvature profile of the wafer.
20. The system of claim 17, further comprising a fluid supply unit
operable to supply a fluid adjacent the wafer stage.
21. The system of claim 17, wherein the curvature profile module
includes a metrology tool operable to determine the curvature
profile of the wafer.
22. The system of claim 17, further comprising a conveyor operable
to transport the wafer from the wafer curvature module to the wafer
stage after determining the curvature profile of the wafer.
23. The system of claim 17, further comprising a projection unit
interposing the reticle stage and the wafer stage.
24. The system of claim 23, wherein the determined curvature
profile of the wafer correlates to an alignment mark shift for an
alignment mark on the wafer, the alignment mark shift representing
a positional change of the alignment mark from a first position to
a second position on the wafer as a result of applying a process to
the wafer.
25. The system of claim 24, wherein the process includes a heat
treatment process.
26. The system of claim 17, wherein the curvature profile module is
operable to determine the curvature profile of the entire
wafer.
27. The system of claim 17, wherein the curvature profile module is
operable to determining the curvature profile of the wafer locally
at a plurality of different portions of the wafer.
28. The system of claim 17, wherein the curvature profile module is
operable to determine the curvature profile of the wafer while the
wafer is supported by the wafer stage.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a divisional application of U.S.
patent application Ser. No. 11/686,142, filed Mar. 14, 2007, which
is incorporated herein by reference in its entirety.
BACKGROUND
[0002] Photolithography or optical lithography is a process used in
semiconductor device fabrication to transfer a pattern from a
photomask or reticle to the surface of a substrate. Often,
crystalline silicon in the form of a wafer is used as a choice of
substrate, although glass, sapphire and metal may alternatively or
additionally be used, among other materials.
[0003] A typical lithography procedure would begin by depositing a
layer of conductive metal or other material on the substrate. A
layer of photoresist is then formed over the metal layer. A
photomask is then placed between a source of illumination and the
wafer to selectively expose parts of the substrate to light. The
photoresist is then developed, by which areas of unhardened
photoresist undergo a chemical change. After a hard-bake,
subsequent chemical treatments etch away the portions of the metal
layer under the developed photoresist, and then etch away the
hardened photoresist, leaving the patterned metal layer.
[0004] A commonly used approach for photolithography is projection
lithography, in which a desired pattern is projected from the
photomask onto the wafer in a machine called a scanner. In a
scanner, light from a mercury arc lamp or excimer laser is focused
onto a "mask" or reticle containing the desired image. The light
passes through the mask and is then focused to produce the desired
image on the wafer through a reduction lens system. The reduction
of the system can vary depending on design, but is typically on the
order of 4.times.-5.times. in magnitude.
[0005] When the image is projected onto the wafer, the photoresist
material undergoes wavelength-specific radiation-sensitive chemical
reactions, which cause the regions exposed to light to be either
more or less acidic. If the exposed regions become more acidic, the
material is called a positive photoresist, while if it becomes less
susceptible it is a negative photoresist. The resist is then
developed by exposing it to an alkaline solution that removes
either the exposed (positive) photoresist or the unexposed
(negative) photoresist.
[0006] Lithography is used because it affords precise control over
the shape and size of the objects it creates, and because it can
create patterns over an entire surface simultaneously. However, the
process does have its pitfalls.
[0007] For example, an important process for enhancing device
performance in IC fabrication for technologies at 65 nm and beyond
is surface annealing. However, surface annealing processes can
cause the wafer to bend or bow as a result of stress disparities
between adjacent layers formed on the substrate and in the
substrate itself. The resulting wafer curvature can shift alignment
marks, making subsequent lithography alignment difficult and
inducing poor overlay performance.
[0008] Current scanner alignment correction includes translation,
rotation, non-orthogonality and expansion. However, these
corrections may not always be sufficient to correct for the wafer
curvature resulting from thermal processing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present disclosure is best understood from the following
detailed description when read with the accompanying figures. It is
emphasized that, in accordance with the standard practice in the
industry, various features are not drawn to scale. In fact, the
dimensions of the various features may be arbitrarily increased or
reduced for clarity of discussion.
[0010] FIGS. 1a-1c are sectional views of a partially completed
semiconductor apparatus in various stages of conventional
manufacture.
[0011] FIG. 2 is a chart depicting alignment mark shift that
conventionally results from three different annealing
processes.
[0012] FIG. 3 is a graph depicting overlay performance that
conventionally results from the different annealing processes.
[0013] FIG. 4 is a graphical depiction of wafer curvature according
to one or more aspects of the present disclosure.
[0014] FIG. 5 is a flow-chart diagram of at least a portion of a
method according to one or more aspects of the present
disclosure.
[0015] FIG. 6 is a schematic view of at least a portion of an
apparatus according to one or more aspects of the present
disclosure.
[0016] FIG. 7 is a schematic view of at least a portion of an
apparatus according to one or more aspects of the present
disclosure.
DETAILED DESCRIPTION
[0017] It is to be understood that the following disclosure
provides many different embodiments, or examples, for implementing
different features of various embodiments. Specific examples of
components and arrangements are described below to simplify the
present disclosure. These are, of course, merely examples and are
not intended to be limiting. In addition, the present disclosure
may repeat reference numerals and/or letters in the various
examples. This repetition is for the purpose of simplicity and
clarity and does not in itself dictate a relationship between the
various embodiments and/or configurations discussed. Moreover, the
formation of a first feature over or on a second feature in the
description that follows may include embodiments in which the first
and second features are formed in direct contact, and may also
include embodiments in which additional features may be formed
interposing the first and second features, such that the first and
second features may not be in direct contact.
[0018] Referring to FIG. 1a, illustrated is a sectional view of a
partially completed semiconductor apparatus 100 in an intermediate
stage of conventional manufacture. The apparatus 100 includes a
substrate or wafer 110 (the words "substrate" and "wafer" are used
interchangeably herein) and a material layer 120 formed thereon.
The material layer 120 may have a conductive or dielectric
composition and may be formed by one or more conventional or
future-developed manufacturing processes. In an exemplary
embodiment, the material layer 120 is a photoresist layer, either
prior to or after exposure.
[0019] Referring to FIG. 1b, illustrated is a sectional view of the
apparatus 100 shown in FIG. 1a in a subsequent stage of
manufacture, herein designated by reference numeral 100a. As shown
in FIG. 1b, an annealing process may give rise to tensile stress in
the substrate 110, which can cause the substrate 110 and the
material layer 120 to take on a generally concave shape.
[0020] Referring to FIG. 1c, illustrated is a sectional view of the
apparatus 100 shown in FIG. 1a in a subsequent stage of
manufacture, herein designated by reference numeral 100b. As shown
in FIG. 1c, the annealing process may alternatively give rise to
compressive stress in the substrate 110, which can cause the
substrate 110 and the material layer 120 to take on a generally
convex shape.
[0021] FIGS. 1b and 1c demonstrate that the substrate 110 may
experience wafer bowing or otherwise take on a non-planar profile
in response to undergoing one or more heat treatment processes.
However, the curvature profile may not be as uniform as in the
embodiments depicted in FIGS. 1b and 1c. For example, some portions
of the substrate 110 may have a convex curvature, while other
portions of the substrate 110 may simultaneously have a concave
curvature. Additionally, the amount of curvature may vary across
different portions of the substrate 110.
[0022] Referring to FIG. 2, illustrated is a chart depicting the
alignment mark shift that conventionally results from three
different annealing processes, which may be the result of wafer
curvature similar to that demonstrated by FIGS. 1b and 1c.
Annealing process A is a conventional rapid thermal anneal (RTA).
The alignment mark shift resulting from the RTA ranges between
about +8 nm and about -6 nm. Annealing process B comprises a
conventional RTA and a conventional flash anneal at a flash energy
of 25 J. The alignment mark shift resulting from the RTA and 25 J
flash anneal ranges between about +10 nm and about -10 nm.
Annealing process B comprises a conventional RTA and a conventional
flash anneal at a flash energy of 27 J. The alignment mark shift
resulting from the RTA and 27 J flash anneal ranges between about
+20 nm and about -18 nm.
[0023] Referring to FIG. 3, illustrated is a graph depicting the
photo misalignment or other overlay performance that conventionally
results from three different annealing processes, which may be the
result of wafer curvature similar to that demonstrated by FIGS. 1b
and 1c. The overlay performance may result from alignment mark
shift that conventionally results from the different annealing
processes. Annealing process A is a conventional RTA. The overlay
performance resulting from the RTA ranges between about +12 nm and
about -8 nm, or a range of about 20 nm. Annealing process B
comprises a conventional RTA and a conventional flash anneal at a
flash energy of 25 J. The overlay performance resulting from the
RTA and 25 J flash anneal ranges from more than +20 nm to almost
-20 nm, or a range of about 40 nm. Annealing process B comprises a
conventional RTA and a conventional flash anneal at a flash energy
of 27 J. The overlay performance resulting from the RTA and 27 J
flash anneal ranges from almost +50 nm to more than about -35 nm,
or a range of about 80 nm.
[0024] FIGS. 2 and 3 demonstrate that not only can annealing
processes cause wafer curvature that results in alignment mark
shift and poor overlay performance, but also that the amount of
alignment mark shift and/or decreased overlay performance can
change depending on the particular annealing process to which the
wafer is subjected. This disadvantage is multiplied where the wafer
is subjected to more than one annealing process.
[0025] Applicants have shown through experimentation that alignment
mark shift and poor overlay performance, such as depicted in FIGS.
2 and 3, can be strongly correlated to wafer curvature. This was an
unexpected result. For example, the alignment mark shift shown in
FIGS. 2 and 3 can be correlated to the wafer curvature shown in
FIG. 4. Consequently, wafer curvature can be taken into account as
a pre-process measurement to ensure precise process control. For
example, pre-process measurement of wafer curvature may be embedded
into scanner hardware and/or software, or otherwise utilized by the
scanner during operation.
[0026] FIG. 4 is an example, graphical depiction of the curvature
at a plurality of locations across the substrate. The wafer
curvature map of FIG. 4 shows both the quantitative curvature and
the curvature direction at various positions across a substrate,
such positions being indicated numerically along the horizontal and
vertical indices of the map. However, other representations of
wafer curvature within the scope of the present disclosure may be
purely textual or a combination of text and graphics.
[0027] The wafer curvature depicted in FIG. 4 may be determined by
an optical and/or mechanical profiler, such as the CGS-300
commercially available from Oraxion, Inc., the Flexus commercially
available from Brumley South, Inc., or the FX100 commercially
available from KLA-Tencor. However, other conventional or
future-developed metrology tools may alternatively or additionally
be employed to measure or otherwise determine wafer curvature
within the scope of the present disclosure. Additionally, the wafer
curvature may be measured globally across the entire wafer or
locally in different portions of the surface of the substrate.
[0028] Referring to FIG. 5, illustrated is a flow-chart diagram of
at least a portion of a method 500 according to one or more aspects
of the present disclosure. The method 500 includes a step 510
during which a substrate is heat treated. The heat treatment of
step 510 may be or include a conventional or other RTA process.
Additionally, or alternatively, the heat treatment of step 510 may
be or include a conventional or other flash anneal, such as a flash
anneal at a flash energy of 25 J or a flash anneal at a flash
energy of 27 J, among other heat treatment processes. The heat
treatment of step 510 may also include subjecting the substrate to
more than one heat treatment process. In any case, the heat treated
substrate resulting from step 510 may be bowed or otherwise
experience wafer curvature.
[0029] Accordingly, the method 500 also includes a step 520 during
which the wafer curvature is measured or otherwise determined, as
described above. Consequently, the wafer curvature determined
during step 520 may be subsequently utilized in step 530 to adjust
scanner operation and thereby take into account the wafer curvature
that would otherwise adversely affect alignment mark shift and
overlay performance. The scanner operation adjustment of step 530
may be performed by a dedicated module configured to adjust the
scanner operation parameters based on the wafer curvature
determined during step 520. Alternatively, or additionally, the
scanner operation adjustment of step 530 may be performed by the
scanner itself, such as where the adjustment capability is embedded
within the hardware and/or software of the scanner.
[0030] Moreover, the processing contemplated by step 530 is not
limited the scanner operation depicted in the example shown in FIG.
5. That is, the wafer curvature determined during step 520 may be
utilized to adjust a variety of lithographic and optical processing
operations, whether with a conventional or future-developed scanner
or other processing tools. Thus, wafer curvature can be measured
before any such lithography or other process and then fed forward
to the appropriate process tools, and such embodiments are within
the scope of the present disclosure.
[0031] Referring to FIG. 6, illustrated is a schematic view of at
least a portion of apparatus 600 demonstrating one or more aspects
of an environment in which one or more aspects of the present
disclosure may be implemented. The apparatus 600 may be, include,
or be included in a scanner or other lithography system according
to one or more aspects of the present disclosure.
[0032] The apparatus 600 comprises an illumination system 610, a
reticle stage 615 configured to hold a reticle 620, a projection
unit 625, and a stage unit 630. Among other possible components,
the illumination system 610 may include a light source, an
illuminance uniformity optical system (such as may include an
optical integrator or the like), a beam splitter, a relay lens, a
filter, and/or a reticle blind (none of which are shown). In
illumination system 610, an illumination or exposure light
illuminates through an exposure slit (such as may be set by the
reticle blind) and onto the reticle 620 where the circuit pattern
or the like is fabricated with substantially uniform illuminance.
The illumination or exposure light may comprise an ArF excimer
laser beam (e.g., wavelength of 193 nm), a far ultraviolet light
such as the KrF excimer laser beam (e.g., wavelength of 248 nm), or
bright lines in the ultraviolet region generated by an ultra
high-pressure mercury lamp (such as the g-line or the i-line),
among others. The illumination system 610 may also comprise a
fly-eye lens, a rod integrator (an internal reflection type
integrator), and/or a diffraction optical element, such as may be a
component of the optical integrator.
[0033] The reticle 620 is secured to the reticle stage 615 by
vacuum, for example. The reticle stage 615 may be drivable in an XY
plane perpendicular to the optical axis of the illumination system
610 by a reticle stage drive section, such as may comprise one or
more linear motors or other motion-inducing components. The reticle
stage 615 may be drivable in a predetermined scanning direction,
such as along the Y-axis shown in FIG. 6.
[0034] The position of the reticle stage 615 within its moving
plane may be detected periodically or at all times via a reticle
laser interferometer 635 via a movable minor 640, possibly at a
resolution of ranging between about 0.5 nm and about 1.0 nm. The
reticle stage 615 may comprise a movable minor that has a
reflection surface orthogonal to the Y-axis direction and another
movable minor that has a reflection surface orthogonal to an X-axis
direction, as well as a reticle Y interferometer and a reticle X
interferometer corresponding to such minors. However, in FIG. 6,
such an embodiment and others are schematically represented by
movable mirror 640 and reticle interferometer 635.
[0035] Information describing the position of the reticle stage 615
may be communicated from reticle interferometer 635 to a main
controller 645, such as via a stage control unit 650. The stage
control unit 650 may be configured to drive and/or control the
reticle stage 615 via the reticle stage drive section, based on the
positional information of the reticle stage 615 and in response to
instructions from the main controller 645.
[0036] The optical axis of the projection unit 625 may coincide
with the optical axis of the illumination system 610. The
projection unit 625 may comprise a barrel-shaped structure housing
a projection optical system that includes a plurality of lenses,
lens elements, and/or other optical elements which share the same
optical axis in the Z-axis direction and are held at a
predetermined positional relationship within the housing. For
example, a both-side telecentric dioptric system having a
predetermined projection magnification (e.g., 1/4.times. or
1/5.times.) may be employed. Accordingly, when exposure light from
the illumination system 610 illuminates the illumination area on
the reticle 620, the illumination light that passes through the
reticle 620 may the pass through the projection unit 625 and form a
reduced image of the circuit pattern within the illumination area
on the reticle 620 (a partial reduced image of the circuit pattern)
on the wafer or substrate 655, whose surface may be coated with a
resist and/or other photosensitive material.
[0037] The apparatus 600 may also comprise a liquid supply/drainage
unit 660, such that the apparatus 600 may be configured for use in
immersion lithography processing. The liquid supply/drainage unit
660 may be attached to the projection unit 625 so that it surrounds
the lower end of the projection unit 625.
[0038] The stage unit 630 may comprise a wafer stage 665, a wafer
holder 670 provided on the wafer stage 665, and a wafer stage drive
section 675 which is configured to drive the wafer stage 665 and
wafer holder 670. The wafer stage 665 comprises an XY stage 680,
such as may be driven in the XY direction by linear motors and/or
other components. The wafer stage 665 also comprises a Z stage 685,
such as may be mounted on the XY stage 680 and may be configured to
provide movement in the Z-axis direction and/or in an inclination
direction with respect to the XY plane (the rotational direction
around the X-axis (.OMEGA.X) and the rotational direction around
the Y-axis (.OMEGA.Y)), such as by a Z tilt drive mechanism. The XY
stage 680 may also be configured to be movable not only in the
scanning direction (the Y-axis direction) but also in a
non-scanning direction (the X-axis direction) perpendicular to the
scanning direction.
[0039] The XY stage 680 and the Z stage 685 may be collectively
referred to as a wafer stage. The position of wafer stage within
the XY plane, possibly including rotation around the Z-axis
(.OMEGA.Z) is detected periodically or at all times by a wafer
laser interferometer 690, such as via a movable mirror 695 provided
on the upper surface of the Z tilt stage 685, possibly at a
resolution ranging between about 0.5 nm and about 1 nm, for
example. Such configuration may also comprise a dual-minor,
dual-interferometer configuration as described above with regard to
the reticle stage 615.
[0040] Positional and/or velocity (speed) information regarding the
wafer stage may be communicated to the stage control unit 650, and
then to main controller 645. The stage control unit 650 may be
configured to control the wafer stage via the wafer stage drive
section 675 based on the positional and/or velocity information of
the wafer stage, such as in response to instructions from the main
controller 645.
[0041] The position and/or velocity of the wafer stage and/or the
reticle stage 615 may be configured to be adjusted based on a wafer
curvature profile. As described above with respect to FIG. 5, the
means for determining the wafer curvature profile may be integral
to the apparatus 600, or may be discrete apparatus separate from
the apparatus 600. In either case, the wafer curvature profile
information is fed to the apparatus 600 to be utilized during
operation of the apparatus 600. Accordingly, because the wafer
curvature profile is utilized to adjust the operational parameters
of the apparatus 600, alignment mark shift may be significantly
reduced or eliminated, and overlay performance may be improved.
Thus, the wafer curvature profile can be taken into account as a
pre-process measurement to ensure precise process control during
operation of the apparatus 600.
[0042] Referring to FIG. 7, illustrated is a schematic view of at
least a portion of an apparatus 700 according to one or more
aspects of the present disclosure. The apparatus 700 may be
substantially similar to the apparatus 600 shown in FIG. 6, except
as described below.
[0043] The apparatus 700 includes an illumination system 710, a
reticle stage 715, a projection unit 720 and a wafer stage 725,
which may be substantially similar to the illumination system 610,
the reticle stage 615, the projection unit 625 and the stage unit
630, respectively, shown in FIG. 6. The reticle stage 715 is
configured to retain a reticle 717, and the wafer stage 725 is
configured to retain a wafer 740. The reticle stage 715 and wafer
stage 725 may be drivable in X, Y and Z directions, collectively,
such as by means described above with respect to FIG. 6.
[0044] The apparatus 700 also includes a wafer curvature profiler
730 and a conveyor system 735. The waver curvature profiler 730 may
be integral or otherwise co-located with the other components of
the apparatus 700, or may alternatively be remotely located from
the other components of the apparatus 700. In either case, the
conveyor system 735 is configured to transport a wafer 740 from the
wafer curvature profiler 730 to the wafer stage 725 after
determining the curvature profile of the wafer 740. Consequently,
the curvature profile of the wafer 740 may be taken into account
during operation of the illumination system 710, reticle stage 715,
projection unit 720 and wafer stage 725.
[0045] For example, the illumination system 710, reticle stage 715,
projection unit 720 and wafer stage 725 may be components of a
scanner, stepper or other photolithography or optical lithography
system. The position and/or other operational aspect of the reticle
stage 715, projection unit 720 and/or wafer stage 725 may be
adjustable based the curvature profile of the wafer 740 as
determined by the profiler 730, such that the lithography process
can be adjusted to take into account the curvature profile of the
wafer 740. For example, where the curvature profile of the wafer
740 correlates to an alignment mark shift of a certain amount and
direction, the position of the reticle stage 715 and/or the wafer
stage 725 may be repositioned by the shift amount in an opposite
direction of the shift. However, other schemes for adjusting the
operation of the apparatus 700 based on the wafer curvature profile
are also within the scope of the present disclosure.
[0046] In view of all of the foregoing, it should be readily
apparent to those skilled in the art that the present disclosure
introduces a method of processing a substrate that includes
determining a curvature profile of the substrate and then
lithographically exposing portions of the substrate based on the
curvature profile. Such method may further include subjecting the
substrate to a heat treatment process before determining the
curvature profile of the substrate. The heat treatment process may
comprise a rapid thermal anneal (RTA) process and/or a flash anneal
process. Determining the wafer curvature profile may comprise
simultaneously determining the wafer curvature profile
substantially globally across the substrate, or determining wafer
curvature locally at a plurality of different portions of the
substrate. Lithographically exposing portions of the substrate may
utilize a scanner or other photolithography or optical lithography
apparatus.
[0047] A system for processing a substrate that is also introduced
in the present disclosure includes means for determining a
curvature profile of the substrate and means for lithographically
exposing portions of the substrate based on the curvature profile.
The system may further comprise means for subjecting the substrate
to a heat treatment process before determining the curvature
profile of the substrate. The heat treatment process may comprise a
rapid thermal anneal (RTA) process and/or a flash anneal
process.
[0048] A scanner system that is also introduced in the present
disclosure includes a reticle stage configured to retain a reticle,
a wafer stage configured to retain a wafer, a projection unit
interposing the reticle stage and the wafer stage, and an
illumination source configured to emit light through the reticle
and the projection unit and onto the wafer, wherein at least one of
the reticle stage and the wafer stage is configured to be
positionally adjusted to account for a curvature profile of the
wafer. The scanner system may further comprise a wafer curvature
profiler configured to determine the curvature profile of the
wafer, and/or a conveyor configured to transport the wafer from the
wafer curvature profiler to the wafer stage. The wafer curvature
profiler may be remotely located from the wafer stage.
[0049] The foregoing outlines features of several embodiments so
that those skilled in the art may better understand the aspects of
the present disclosure. Those skilled in the art should appreciate
that they may readily use the present disclosure as a basis for
designing or modifying other processes and structures for carrying
out the same purposes and/or achieving the same advantages of the
embodiments introduced herein. Those skilled in the art should also
realize that such equivalent constructions do not depart from the
spirit and scope of the present disclosure, and that they may make
various changes, substitutions and alterations herein without
departing from the spirit and scope of the present disclosure.
* * * * *