U.S. patent application number 11/001165 was filed with the patent office on 2006-06-01 for tri-tone trim mask for an alternating phase-shift exposure system.
This patent application is currently assigned to Texas Instruments Incorporated. Invention is credited to Thomas J. Aton.
Application Number | 20060115742 11/001165 |
Document ID | / |
Family ID | 36565697 |
Filed Date | 2006-06-01 |
United States Patent
Application |
20060115742 |
Kind Code |
A1 |
Aton; Thomas J. |
June 1, 2006 |
Tri-tone trim mask for an alternating phase-shift exposure
system
Abstract
A photolithographic trim mask includes a transparent region, an
attenuated phase-shift region, and an opaque region. The
transparent region substantially transmits received light. The
attenuated phase-shift region attenuates and shifts the phase of
the received light. The phase-shifted attenuated light patterns a
coarse line region of a wafer. The opaque region substantially
prevents received light from exposing a fine line region of the
wafer.
Inventors: |
Aton; Thomas J.; (Dallas,
TX) |
Correspondence
Address: |
TEXAS INSTRUMENTS INCORPORATED
P O BOX 655474, M/S 3999
DALLAS
TX
75265
US
|
Assignee: |
Texas Instruments
Incorporated
|
Family ID: |
36565697 |
Appl. No.: |
11/001165 |
Filed: |
December 1, 2004 |
Current U.S.
Class: |
430/5 ; 430/322;
430/323; 430/324 |
Current CPC
Class: |
G03F 1/30 20130101; G03F
1/70 20130101; G03F 1/32 20130101 |
Class at
Publication: |
430/005 ;
430/322; 430/324; 430/323 |
International
Class: |
G03F 1/00 20060101
G03F001/00; G03C 5/00 20060101 G03C005/00 |
Claims
1. A photolithographic trim mask for patterning, comprising: a
transparent region comprising a substantially transparent material
and operable to substantially transmit received light; an
attenuated phase-shift region comprising an attenuated phase-shift
material and operable to: attenuate received light; and shift the
phase of the received light, the phase-shifted attenuated light
operable to pattern a coarse line region of a wafer; and an opaque
region comprising an opaque material and operable to substantially
prevent received light from exposing a fine line region of the
wafer.
2. The mask of claim 1, wherein the attenuated phase-shift region
is further operable to shift the phase of the received light by
approximately one hundred eighty degrees.
3. The mask of claim 1, wherein the attenuated phase-shift material
comprises molybdenum silicide.
4. The mask of claim 1, wherein: the coarse line region further
comprises an interconnect region; and the fine line region further
comprises a gate region.
5. A photolithographic mask system for patterning, comprising: a
trim mask comprising: a transparent region comprising a
substantially transparent material and operable to substantially
transmit received light; an attenuated phase-shift region
comprising an attenuated phase-shift material and operable to:
attenuate received light; and shift the phase of the received
light, the phase-shifted attenuated light operable to pattern a
coarse line region of a wafer; and an opaque region comprising an
opaque material and operable to substantially prevent received
light from exposing a fine line region of the wafer; and an
alternating phase-shift mask operable to pattern the fine line
region.
6. The mask system of claim 5, wherein the attenuated phase-shift
region is further operable to shift the phase of the received light
by approximately one hundred eighty degrees.
7. The mask system of claim 5, wherein the attenuated phase-shift
material comprises molybdenum silicide.
8. The mask system of claim 5, wherein: the coarse line region
further comprises an interconnect region; and the fine line region
further comprises a gate region.
9. A photolithographic trim mask for patterning, comprising: a
substrate comprising a substantially transparent material operable
to substantially transmit received light; an attenuated phase-shift
layer disposed outwardly from the substrate, the attenuated
phase-shift layer comprising an attenuated phase-shift material
operable to: attenuate received light; and shift the phase of the
received light; an opaque layer disposed outwardly from the
substrate, the opaque layer comprising an opaque material operable
to substantially block received light, the attenuated phase-shift
layer and the opaque layer patterned to form an attenuated
phase-shift region and an opaque region, the attenuated phase-shift
region operable to pattern a coarse line region of a wafer, the
opaque region operable to substantially prevent received light from
exposing a fine line region of the wafer.
10. The mask of claim 9, wherein the attenuated phase-shift
material is further operable to shift the phase of the received
light by approximately one hundred eighty degrees.
11. The mask of claim 9, wherein the attenuated phase-shift
material comprises molybdenum silicide.
12. The mask of claim 9, wherein: the coarse line region further
comprises an interconnect region; and the fine line region further
comprises a gate region.
13. A method of making a photolithographic trim mask, comprising:
depositing an attenuated phase-shift layer outwardly from a
substrate, the substrate comprising a substantially transparent
material, the attenuated phase-shift layer comprising an attenuated
phase-shift material; depositing an opaque layer outwardly from the
attenuated phase-shift layer, the opaque layer comprising a
substantially opaque material; patterning the attenuated
phase-shift layer and the opaque layer to yield one or more
transparent regions, a transparent region operable to substantially
transmit light; and patterning the opaque layer to yield one or
more opaque regions and one or more attenuated phase-shift regions,
an attenuated phase-shift region operable to attenuate received
light and to shift the phase of the received light, an opaque
region operable to substantially prevent light from exposing a fine
line region of a wafer.
14. A method of making a photolithographic trim mask, comprising:
depositing an opaque layer outwardly from a substrate, the
substrate comprising a substantially transparent material, the
opaque layer comprising a substantially opaque material; patterning
the opaque layer to yield one or more opaque regions, an opaque
region operable to substantially prevent light from exposing a fine
line region of a wafer; depositing an attenuated phase-shift layer
outwardly from the opaque layer, the attenuated phase-shift layer
comprising an attenuated phase-shift material; and patterning the
opaque layer to yield one or more transparent regions and one or
more attenuated phase-shift regions, a transparent region operable
to substantially transmit light, an attenuated phase-shift region
operable to attenuate received light and to shift the phase of the
received light, an opaque region operable to substantially prevent
light from exposing a fine line region of a wafer.
15. A method for patterning, comprising: exposing a semiconductor
wafer using a trim mask comprising: a transparent region comprising
a substantially transparent material and operable to substantially
transmit received light; an attenuated phase-shift region
comprising an attenuated phase-shift material and operable to:
attenuate received light; and shift the phase of the received
light, the phase-shifted attenuated light operable to pattern a
coarse line region of the wafer; and an opaque region comprising an
opaque material and operable to substantially prevent received
light from exposing a fine line region of the wafer; and exposing
the wafer using an alternating phase-shift mask to pattern the fine
line region of the wafer.
16. A system of making a photolithographic trim mask, comprising:
means for depositing an attenuated phase-shift layer outwardly from
a substrate, the substrate comprising a substantially transparent
material, the attenuated phase-shift layer comprising an attenuated
phase-shift material; means for depositing an opaque layer
outwardly from the attenuated phase-shift layer, the opaque layer
comprising a substantially opaque material; means for patterning
the attenuated phase-shift layer and the opaque layer to yield one
or more transparent regions, a transparent region operable to
substantially transmit light; and means for patterning the opaque
layer to yield one or more opaque regions and one or more
attenuated phase-shift regions, an attenuated phase-shift region
operable to attenuate received light and to shift the phase of the
received light, an opaque region operable to substantially prevent
light from exposing a fine line region of a wafer.
17. A photolithographic mask system for patterning, comprising: a
trim mask comprising: a transparent region comprising a
substantially transparent material and operable to substantially
transmit received light; an attenuated phase-shift region
comprising an attenuated phase-shift material and operable to:
attenuate received light; and shift the phase of the received light
by approximately one hundred eighty degrees, the phase-shifted
attenuated light operable to pattern coarse line of a wafer, the
coarse line region further comprising a field region, the
attenuated phase-shift material comprising molybdenum silicide; and
an opaque region comprising an opaque material and operable to
substantially prevent received light from exposing a fine line
region of the wafer, the fine line region further comprising a gate
region; and an alternating phase-shift mask operable to pattern the
fine line region.
Description
TECHNICAL FIELD
[0001] This invention relates generally to the field of
photolithography and more specifically to a tri-tone trim mask for
an alternating phase-shift exposure system.
BACKGROUND
[0002] A photolithographic mask may be used to pattern an object
such as a semiconductor wafer of an integrated circuit. The mask
may be positioned between a light source and the object. Light from
the light source is selectively transmitted, blocked, or otherwise
affected by the mask to define a pattern on the object. A mask such
as an embedded attenuated phase-shift mask includes attenuated
phase-shift regions. An attenuated phase-shift region transmits a
small percentage of light and shifts the phase of transmitted
light. Light passing through an attenuated phase-shift region may
destructively interfere with light passing through an adjacent
transparent region, which may allow for higher resolution pattern
definition in certain situations. Embedded attenuated phase-shift
masks, however, do not provide for high resolution pattern
definition in other situations. It is generally desirable to have
high resolution pattern definition in a variety of situations.
SUMMARY OF THE DISCLOSURE
[0003] In accordance with the present invention, disadvantages and
problems associated with previous techniques for providing a
photolithographic mask may be reduced or eliminated.
[0004] According to one embodiment of the present invention, a
photolithographic trim mask for patterning a wafer includes a
transparent region, an attenuated phase-shift region, and an opaque
region. The transparent region substantially transmits received
light. The attenuated phase-shift region transmits a portion of
received light and shifts the phase of the transmitted light. The
shifted light patterns a coarse line region of a pattern. The
opaque region substantially prevents received light from exposing a
fine line region of the pattern, where the fine line region is to
be patterned by a separate alternating phase-shift mask.
[0005] Certain embodiments of the invention may provide one or more
technical advantages. A technical advantage of one embodiment may
be that a trim mask may include attenuated phase-shift, opaque, and
transparent regions. An attenuated phase-shift region may be used
to pattern a coarse line region of a pattern. The attenuated
phase-shift region may provide for higher precision patterning of
the coarse line region than an opaque region can provide. A fine
line region of the pattern may be left unexposed by an opaque
region during one exposure, and patterned by an alternating
phase-shift mask during a next exposure. The opaque region may
protect the fine line region from exposure to light, which may
allow for effective exposure of the fine line region by the
phase-shift mask.
[0006] Certain embodiments of the invention may include none, some,
or all of the above technical advantages. One or more other
technical advantages may be readily apparent to one skilled in the
art from the figures, descriptions, and claims included herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] For a more complete understanding of the present invention
and its features and advantages, reference is now made to the
following description, taken in conjunction with the accompanying
drawings, in which:
[0008] FIG. 1A is a diagram illustrating an example mask;
[0009] FIGS. 1B and 1C are diagrams illustrating an example trim
mask of the mask of FIG. 1;
[0010] FIG. 1D is a diagram illustrating an example alternating
phase-shift mask of the mask of FIG. 1;
[0011] FIG. 2A through 2E illustrate an example mask at different
phases of an etching process:
[0012] FIG. 2A illustrates a cross-sectional sample of an example
mask;
[0013] FIG. 2B illustrates the mask of FIG. 2A after an etch
process;
[0014] FIG. 2C illustrates the mask of FIG. 2B during the formation
of a resist layer;
[0015] FIG. 2D illustrates the mask of FIG. 2C after selective
removal of exposed resist layer;
[0016] FIG. 2E illustrates the mask of FIG. 2D after removal of the
remaining resist layer;
[0017] FIGS. 3A and 3B illustrate a cross-sectional view of the
exposure of a wafer using an example trim mask and an example
alternating phase-shift mask:
[0018] FIG. 3A illustrates the exposure of the wafer by the example
trim mask; and
[0019] FIG. 3B illustrates the exposure of the wafer by the example
alternating phase-shift mask.
DETAILED DESCRIPTION OF THE DRAWINGS
[0020] Embodiments of the present invention and its advantages are
best understood by referring to FIGS. 1A through 3B of the
drawings, like numerals being used for like and corresponding parts
of the various drawings.
[0021] FIG. 1A is a diagram illustrating an example mask set 10. A
mask set may refer to one or more photolithographic masks that may
be used to pattern an object such as a semiconductor wafer. Mask
set 10 may be positioned between a light source and the object.
Light from the light source is selectively transmitted, blocked,
phase shifted, or otherwise affected by mask set 10 to pattern the
object. For example, a pattern may be defined on a resist layer of
a wafer to generate features of an integrated circuit. The size and
shape of mask set 10 determine the size and shape of the pattern.
Mask set 10 may be of any appropriate size or shape for creating a
pattern of any suitable size or shape on the object.
[0022] According to one embodiment, mask set 10 may be used to
pattern a gate pattern of a circuit such as a CMOS integrated
circuit. A pattern may include fine line regions, where the pattern
is narrow or requires very precise patterning, and coarse line
regions, where the pattern is wide or requires significantly less
precise patterning. An example of a fine line region includes a
gate or transistor region of a CMOS integrated circuit. A narrow
width, precisely controlled polysilicon layer is patterned to
partially cover the active or diffusion regions of a semiconductor
substrate to form a gate. An example of a coarse line region
includes an interconnect region. The interconnect regions at least
partially connect the transistor regions to the external world.
Other examples of fine line and coarse line patterning include fine
interconnects coupled with coarse power bussing on a metal layer of
an integrated circuit.
[0023] According to the illustrated embodiment, mask set 10
includes a trim mask 20 and an alternating phase-shift mask 22.
Trim mask 20 and alternating phase-shift mask 22 may each be used
to condition the light as part of the patterning process. For
example, trim mask 20 may be used to condition the light during a
first exposure, and alternating phase-shift mask 22 may be used to
condition the light during a second exposure.
[0024] According to one embodiment, trim mask 20 may include
regions that are substantially transparent, regions characterized
as attenuated phase-shift regions, and regions that are
substantially opaque. Trim mask 20 and alternating phase-shift mask
22 are described in more detail with reference to FIGS. 1B and
1C.
[0025] According to a known technique, a alternating phase/trim
mask set includes an alternating phase mask and a bi-tone trim
mask. A bi-tone trim mask typically has transparent and opaque
regions. During a first exposure, the transparent regions pattern
the coarse line regions, and the opaque regions shield the fine
line regions. During a second exposure, the fine line regions are
patterned by the phase mask. In certain situations, however, the
bi-tone trim mask cannot pattern the coarse line regions with
sufficient resolution. According to another known technique, the
bi-tone trim mask may include phase-shift mask regions and
transparent regions. The phase-shift mask regions of the trim mask,
however, do not sufficiently shield the fine line regions,
significantly reducing the contrast and resolution of the fine line
regions.
[0026] FIG. 1B is a diagram illustrating example trim mask 20 of
mask set 10 of FIG. 1. Trim mask 20 includes a transparent region
30, an attenuated phase-shift region 32, and an opaque region 34.
Regions 30, 32, and 34 may have any suitable size or shape.
Transparent region 30 transmits substantially all light from the
light source. Typically, transparent region 30 transmits light to
allow for removal of a resist layer on a wafer. Transparent region
30 may comprise any suitable substantially transparent material
operable to substantially transmit light, such as quartz. The
transparent material may form a substrate for trim mask 20.
[0027] Attenuated phase-shift region 32 acts to transmit only a
portion of the received light to the object. When suitably
illuminated, attenuated phase-shift region 32 shifts the phase of
the transmitted light by an amount suitable to produce destructive
interference with other light diffracted around the edges of the
attenuated phase-shift region 32.
[0028] Attenuated phase-shift region 32 may comprise any suitable
attenuated phase-shift material. An attenuated phase-shift material
may refer to a material that transmits approximately two to fifteen
percent of received light, and shifts the phase of the transmitted
light by, for example, approximately 180.degree.. As an example, an
attenuated phase-shift material may transmit less than ten percent
of the light such as less than eight, six, four, or three percent
of the light. An attenuated phase-shift material may comprise
molybdenum silicide (MoSiOxNy), a chromium-based material, or other
suitable material, depending on the wavelength of the patterning
light. Attenuated phase-shift region 32 may be formed by an
attenuated phase-shift layer comprising an attenuated phase-shift
material. The attenuated phase-shift layer may be disposed
outwardly from the substrate of trim mask 20.
[0029] The phase of light passing through attenuated phase-shift
region 32 may be shifted by an amount, typically approximately
180.degree., with respect to the phase of light passing through
transparent region 30. The light passing through attenuated
phase-shift region 32 may destructively interfere with light
passing through an adjacent transparent region 30. The interference
may provide for higher resolution pattern definition or higher
contrast pattern resolution.
[0030] Opaque region 34 blocks substantially most or all light to
prevent the light from reaching the object. Typically, opaque
region 34 blocks light in order to leave the resist layer on a
wafer unexposed. Opaque region 34 may comprise any suitable opaque
material operable to substantially block the transmission of light,
for example, chromium. Opaque region 34 may be formed by an opaque
layer comprising an opaque material. The opaque layer may be
disposed outwardly from the substrate of trim mask 20.
[0031] Opaque region 34 may include other layers, for example, an
attenuated phase-shift layer. For example, the opaque layer may be
disposed between an attenuated phase shift layer and a transparent
substrate, or may be disposed outwardly from an attenuated
phase-shift layer that is disposed outwardly from a transparent
substrate. Opaque region may comprise any suitable arrangement of
layers, with or without the addition of an attenuated phase-shift
layer, that blocks substantially most or all direct transmission of
light.
[0032] Opaque region 34 is designed to shield fine line regions
from the trim mask exposure so that only phase-shift mask 22
substantially exposes these regions, so the size and shape of
opaque region 34 may correspond to the size and shape of
phase-shift mask 22. A boundary 36 between attenuated phase-shift
region 32 and opaque region 34 may be placed such that attenuated
phase-shift region 32 and phase-shift mask 22 pattern the same
regions. Boundary 36, however, may be placed at any suitable
location.
[0033] FIG. 1C is a diagram illustrating another example from mask
50 of mask set 10 of FIG. 1. Trim mask 50 includes tabs 42 and
wings 44. Tabs 42 extend from the opaque regions to protect end
projections of the fine line regions. Tabs 42 may be opaque,
attenuated, or a combination of opaque and attenuated. Wings 44 are
extensions that widen the opaque region to shield the fine line
regions. Wings 44 may be fully opaque, partially opaque, or any
suitable combination of opaque and attenuated. A boundary 36
between the opaque and attenuated regions may be placed at the base
38 of a wing 44. Boundary 36 may be placed at any suitable distance
40 along an extension that joins a fine line region with a coarse
line region. Phase-shift mask 22 may be used to pattern trim mask
20 as described with reference to FIGS. 2A through 2C.
[0034] FIG. 1D is a diagram illustrating an example alternating
phase-shift mask 22 that includes zero phase regions 26 and pi
phase regions 28. Phase-shift mask 22 selectively alters the phase
of light to create controlled destructive interference that may
improve resolution and depth of focus. Light passing through zero
phase regions 26 is 180.degree. out of phase from light passing
through pi phase regions 28. Light passing through a zero phase
region 26 and an adjacent pi phase region 28 destructively
interfere. Zero phase regions 26 and pi phase regions 28 may be
created by etching a substrate, such as a quartz substrate, to a
precise depth to create the appropriate phase shift. The depth
depends on the wavelength of the light.
[0035] Modifications, additions, or omissions may be made to mask
set 10 without departing from the scope of the invention. As used
in this document, "each" refers to each member of a set or each
member of a subset of a set.
[0036] FIGS. 2A through 2E illustrate an example mask 50 at
different phases of an etching process. FIG. 2A illustrates a
cross-sectional sample of mask 50 during an initial phase. Mask 50
may include one or more layers deposited outwardly from an outward
surface of a substrate 60. For example, an attenuated phase-shift
layer 64 may be deposited outwardly from the outer surface of
substrate 60, and an opaque layer 68 may be deposited outwardly
from the outer surface of attenuated phase-shift layer 64. Any
suitable order of layers, however, may be used. One or more passes
of a photoresist layer 70 may be deposited outwardly from either of
the layers and patterned in order to selectively produce the
regions of transparent, opaque, and attenuated regions.
[0037] According to one embodiment, substrate 60 may comprise any
suitable transparent material such as quartz. Substrate 60 may have
any suitable thickness. Attenuated phase-shift layer 64 may
comprise any suitable attenuated phase-shift material operable to
block most light and to shift the phase of the light approximately
180.degree.. For example, attenuated phase-shift layer may comprise
molybdenum silicide. Attenuated phase-shift layer 64 may have any
suitable thickness. Opaque layer 68 may comprise any suitable
opaque material operable to substantially block light. For example,
opaque layer 68 may comprise chromium. Opaque layer 68 may have any
suitable thickness.
[0038] Photoresist layer 70 may comprise any suitable material such
as a resin that is initially insoluble in a developer but becomes
soluble when it exposed to light or another energy source.
Photoresist layer 70, however, may comprise a material that becomes
insoluble when exposed. Photoresist layer 70 may have any suitable
thickness. After deposition, resist layer 70 may be cured using any
suitable technique such as baking. Portions of photoresist layer 70
exposed to light may undergo wavelength-specific,
radiation-sensitive chemical reaction to create of the mask pattern
of mask 50. Portions of photoresist layer 70 may also be exposed by
elections, protons, or other charged or uncharged particles.
[0039] Layers may be formed outwardly from substrate 60 using any
suitable method. For example, layers may be deposited using
conventional oxidation or deposition techniques such as chemical
vapor deposition or physical vapor deposition techniques.
[0040] FIG. 2B illustrates mask 50 after an etch process. Mask 50
may be etched using any suitable process such as a dry etching
technique, a wet etching technique, or both. As an example, if
attenuated phase-shift layer 64 comprises molybdenum silicide,
layer 64 may be dry etched in an reacting ion etching system. As
another example, if attenuated phase-shift layer 64 comprises
chromium, attenuated phase-shift layer 64 may be wet etched.
Photoresist layer 70 may also be removed.
[0041] FIG. 2C illustrates mask 50 during the formation of resist
layer 72. Resist layer 72 may be deposited outwardly from opaque
layer 68 in any suitable manner. Resist layer 72 is etched to
define an opaque region 80 and an attenuated phase-shift region 82.
Exposure may be by photons, electrons, protons, or other energy
transfer. Exposed regions may retain resist to protect underlying
region or cause resist to disappear exposing underlying
regions.
[0042] FIG. 2D illustrates mask 50 after removal of exposed resist
layer 72. The exposed resist layer 72 may be removed by any
suitable process. Exposed opaque layer 68 may be removed using any
suitable etching process to form attenuated phase-shift region
82.
[0043] FIG. 2E illustrates sample 50 after removal of the remaining
resist layer 72 to yield opaque region 80. The remaining resist
layer 72 may be removed by any suitable process.
[0044] Modifications, additions, or omissions may be made to the
method without departing from the scope of the invention. The
method may include more, fewer, or other steps. Additionally, steps
may be performed in any suitable order without departing from the
scope of the invention. For example, attenuated phase-shift layer
6A may be deposited outwardly from opaque layer 68. As another
example, any suitable exposure process may be used.
[0045] As an example, another embodiment of the method exposes,
develops the resist, and then etches into a hard mask. A hard mask
may refer to a layer of silicon dioxide on silicon nitride. Then,
the method strips the resist, recoats, exposes, develops the
resist, and then etches the hard mask. Finally, the hard mask
finished pattern is transferred to a lower layer of the wafer, and
the hard mask is removed.
[0046] FIGS. 3A and 3B illustrate a cross-sectional view of the
exposure of a wafer 104 through lenses 130 using a trim mask 100
and an alternating phase-shift mask 102. Referring to FIG. 3A, trim
mask 100 is disposed between a light source 106 and wafer 104.
According to the illustrated embodiment, wafer 104 includes a
substrate 110, a fine line region 112, and an coarse line region
114. Substrate 110 may comprise any suitable material used in
integrated devices, for example, silicon. Fine line region 112 may,
for example, be disposed outwardly from substrate 110. Fine line
region 112 may refer to a region of wafer 104 that includes a
feature such as a gate. Coarse line region 114 is disposed
outwardly from substrate 110. A coarse line region may refer to a
region that does not include any active features, and may include a
field or interconnect regions.
[0047] Mask 100 includes an opaque region 122, a clear region 124,
and an attenuated phase-shift region 126. Opaque region 122 is
disposed outwardly from substrate 120, and substantially prevents
light from reaching wafer 104. Clear region 124 is disposed
outwardly from substrate 120, and substantially transmits light.
Attenuated phase-shift region 126 is disposed outwardly from
substrate 120. Attenuated phase-shift region 126 transmits less
than twelve percent of light from light source 106, and selectively
shifts the phase of the transmitted light.
[0048] According to one embodiment of operation, light emitted from
light source 106 travels to clear region 122, opaque region 124,
and attenuated phase-shift region 126 of trim mask 110. Clear
region 122 and opaque region 124 selectively transmits and blocks,
respectively, the light that patterns fine line region 112 of wafer
104. Clear region 122 and attenuated phase-shift region 126
selectively transmits and attenuates and phase shifts,
respectively, the light that patterns coarse line region 114 of
wafer 104.
[0049] Referring to FIG. 3B, phase-shift mask 102 is disposed
between light source 106 and wafer 104. Light emitted from light
source 106 travels through phase-shift mask 102. Phase-shift mask
102 selectively modifies light 130 that patterns the fine line
region 112 of wafer 104. Light source 106 for the phase exposure
need not be the same as for the trim exposure.
[0050] Modifications, additions, or omissions may be made to the
method without departing from the scope of the invention. The
method may include more, fewer, or other steps. Additionally, steps
may be performed in any suitable order without departing from the
scope of the invention.
[0051] Certain embodiments of the invention may provide one or more
technical advantages. A technical advantage of one embodiment may
be that a trim mask may include attenuated phase-shift, opaque, and
transparent regions. An attenuated phase-shift region may be used
to substantially pattern a coarse line region. The attenuated
phase-shift region may provide for higher precision patterning of
the coarse line region than an opaque region can provide. A fine
line region may be shielded from exposure by an opaque region
during one exposure, and patterned by an alternating phase-shift
mask during a next exposure. The opaque region may protect the fine
line region from exposure to light, which may allow for effective
exposure of the fine-line region by the phase-shift mask.
[0052] While this disclosure has been described in terms of certain
embodiments and generally associated methods, alterations and
permutations of the embodiments and methods will be apparent to
those skilled in the art. Accordingly, the above description of
example embodiments does not constrain this disclosure. Other
changes, substitutions, and alterations are also possible without
departing from the spirit and scope of this disclosure, as defined
by the following claims.
* * * * *