U.S. patent application number 09/819872 was filed with the patent office on 2001-09-06 for method of reducing defects in anti-reflective coatings and semiconductor structures fabricated thereby.
Invention is credited to Yin, Zhiping.
Application Number | 20010019164 09/819872 |
Document ID | / |
Family ID | 22252202 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010019164 |
Kind Code |
A1 |
Yin, Zhiping |
September 6, 2001 |
Method of reducing defects in anti-reflective coatings and
semiconductor structures fabricated thereby
Abstract
A method for fabricating a substantially smooth-surfaced
anti-reflective coating on a semiconductor device structure
including generating a plasma from an inert gas in a process
chamber in which the anti-reflective coating is to be deposited.
The anti-reflective coating may include silicon, oxygen and
nitrogen, and is preferably of the general formula
Si.sub.xO.sub.yN.sub.z, where x equals 0.40 to 0.65, y equals 0.02
to 0.56 and z equals 0.05 to 0.33. Preferably, x+y+z equals one.
The method may also include fabricating a silicon nitride layer
over the anti-reflective coating. A semiconductor device which
includes a silicon nitride layer over the anti-reflective coating
has a density of less than about 40,000 particles or surface
roughness features in the silicon nitride of about 120-150
nanometers dimension per eight inch wafer. Accordingly, a mask that
is subsequently formed over the silicon nitride layer has a
substantially uniform thickness and is substantially
distortion-free.
Inventors: |
Yin, Zhiping; (Boise,
ID) |
Correspondence
Address: |
TRASK BRITT
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
22252202 |
Appl. No.: |
09/819872 |
Filed: |
March 28, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09819872 |
Mar 28, 2001 |
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09538555 |
Mar 29, 2000 |
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6225671 |
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09538555 |
Mar 29, 2000 |
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09271621 |
Mar 17, 1999 |
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6144083 |
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09271621 |
Mar 17, 1999 |
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09095477 |
Jun 10, 1998 |
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Current U.S.
Class: |
257/437 ;
257/640; 257/649; 257/E21.029; 257/E21.269; 257/E23.167 |
Current CPC
Class: |
H01L 21/0217 20130101;
H01L 21/0214 20130101; H01L 21/022 20130101; H01L 21/02274
20130101; Y10S 438/905 20130101; H01L 23/5329 20130101; H01L
21/0276 20130101; H01L 2924/0002 20130101; H01L 21/3145 20130101;
H01L 2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
257/437 ;
257/640; 257/649 |
International
Class: |
H01L 031/0232 |
Claims
What is claimed is:
1. A feature of a semiconductor device structure, comprising: a
first layer comprising anti-reflective material; and a second layer
comprising silicon nitride, located over said first layer, and
including surface roughness features of less than about 120
nanometers.
2. The feature of claim 1, wherein said anti-reflective material
comprises silicon atoms and nitrogen atoms.
3. The feature of claim 2, wherein said anti-reflective material
further comprises oxygen atoms.
4. The feature of claim 1, wherein said anti-reflective material
comprises Si.sub.xO.sub.yN.sub.z, where x equals about 0.40 to
about 0.65 times the sum of x, y, and z, y equals about 0.02 to
about 0.56 times the sum of x, y, and z, and z equals about 0.05 to
about 0.33 times the sum of x, y, and z.
5. The feature of claim 1, wherein a surface of said first layer is
substantially free of at least one of measurable particulates and
surface roughness.
6. The feature of claim 1, wherein said second layer includes less
than about 40,000 of at least one of particles and surface
roughness features of at least about 120 nm dimension in an area
equivalent to a surface of an 8 inch diameter wafer.
7. The feature of claim 1, wherein said second layer is formed on
said first layer.
8. A feature of a semiconductor device structure, comprising: a
first layer comprising anti-reflective material; and a second layer
comprising silicon nitride, located over said first layer, and
including a density of less than about 40,000 of at least one of
particles and surface roughness features of at least about 120
nanometers size in an area approximately equivalent to a surface
area of an 8 inch diameter wafer.
9. The feature of claim 8, wherein said anti-reflective material
comprises silicon atoms and nitrogen atoms.
10. The feature of claim 9, wherein said anti-reflective material
further comprises oxygen atoms.
11. The feature of claim 8, wherein said anti-reflective material
comprises Si.sub.xO.sub.yN.sub.z, where x equals about 0.40 to
about 0.65 times the sum of x, y, and z, y equals about 0.02 to
about 0.56 times the sum of x, y, and z, and z equals about 0.05 to
about 0.33 times the sum of x, y, and z.
12. The feature of claim 8, wherein said second layer is formed on
said first layer.
13. A semiconductor device structure, comprising: a first layer
comprising anti-reflective material; a second layer comprising
silicon nitride, located over said first layer, and including less
than about 40,000 of at least one of particles and surface
roughness features of at least about 120 nanometers size in an area
approximately equivalent to a surface area of an 8 inch diameter
wafer; and a mask layer having a substantially uniform thickness
formed over said second layer.
14. The semiconductor device structure of claim 13, wherein said
first layer has a substantially smooth surface.
15. The semiconductor device structure of claim 13, wherein said
anti-reflective material comprises silicon atoms and nitrogen
atoms.
16. The semiconductor device structure of claim 15, wherein said
anti-reflective material further comprises oxygen atoms.
17. The semiconductor device structure of claim 13, wherein said
anti-reflective material comprises Si.sub.xO.sub.yN.sub.z, where x
equals about 0.40 to about 0.65 times the sum of x, y, and z, y
equals about 0.02 to about 0.56 times the sum of x, y, and z, and z
equals about 0.05 to about 0.33 times the sum of x, y, and z.
18. The semiconductor device structure of claim 13, wherein said
second layer is disposed between said first layer and said mask
layer.
19. The semiconductor device structure of claim 13, wherein said
second layer is formed on said first layer.
20. The semiconductor device structure of claim 13, wherein said
mask layer is formed on said second layer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
09/538,555, filed Mar. 29, 2000, pending, which is a continuation
of application Ser. No. 09/271,621, filed Mar. 17, 1999, now U.S.
Pat. No. 6,144,083, which issued on Nov. 7, 2000, which is a
divisional of application Ser. No. 09/095,477, filed Jun. 10, 1998,
pending.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of disposing an
anti-reflective coating (ARC), such as a dielectric anti-reflective
coating (DARC), on a semiconductor device structure. Particularly,
the present invention relates to a process for reducing the
occurrence of particles or roughness on an exposed surface of an
ARC or a DARC. More particularly, the present invention relates to
a process which reduces the incidence of in-film particles and
interfacial irregularities between an ARC or DARC layer and an
adjacent, overlying silicon nitride layer.
[0004] 2. Background of Related Art
[0005] Photolithography processes that have been conventionally
employed in the manufacture of semiconductor devices typically
include disposing a photoresist material over a layer of a
semiconductor device structure, such as a wafer or bulk
semiconductor material, that is to be patterned, positioning a
diffraction grating over the layer of photoresist material,
positioning a mask or reticle between the diffraction grating and
the layer of photoresist material, and directing electromagnetic
radiation, or "light," of some wavelength through openings in the
diffraction grating and the mask or reticle in order to "expose"
and fix portions of the photoresist beneath the diffraction grating
and thereby define an etch mask from the photoresist. Many
materials, such as polysilicon, aluminum and metal silicides, that
are employed to fabricate structures of semiconductor devices are,
however, highly light reflective.
[0006] The reflection of light by an underlying layer of material
distorts the mask image that is defined from the layer of
photoresist material, thereby distorting the structures that are to
be defined through the mask image. Exemplary types of photomask
distortion that may occur include exposure variations in the
thickness of the layer of the photoresist material, which degrade
the resolution of the structure to be patterned through the mask
and are typically referred to as "standing waves;" pattern
dimension variations, or "multiple interferences," caused by
variations in the thickness of the layer of photoresist material,
which deteriorate the dimensional precision of the structure; and
"halation," which is caused by variations in the underlying layer,
such as unevenness thereof, which cause light to be reflected into
portions of the layer of photoresist material that were intended to
be shielded, thereby exposing these portions of the photoresist
material layer to light. The magnitude of each of these distortions
of the layer of photoresist material depends on the intensity of
the light reflected from the underlying layer. As the intensity of
reflected light is reduced, the magnitude of standing waves,
multiple interferences and halation are also reduced.
[0007] Due to the ever-decreasing geometries of state-of-the-art
very large scale integration (VLSI) and ultra large scale
integration (ULSI) semiconductor devices, and because of the
relatively small dimensional tolerances and high dimensional
resolution that are desired of the various structures of such
devices, techniques have been developed to reduce the intensity of
light that is reflected by the layer of material to be
patterned.
[0008] One type of anti-reflective technique includes the
deposition of a film of photoabsorptive material, such as an
anti-reflective coating (ARC) or a dielectric anti-reflective
coating (DARC), over a layer of material to be patterned by etching
prior to disposing a photoresist material over the semiconductor
device structure. As portions of the layer of photoresist material
are exposed to light, the light passes therethrough and some of the
light is absorbed by the ARC or DARC film, thereby reducing the
intensity of light that is reflected back into the photoresist, and
decreasing the incidence and magnitude of standing waves, multiple
interferences, halation, or other distortions of the resultant
mask.
[0009] An exemplary ARC is a polymer film that may be disposed on
the substrate layer by spin-on techniques. Other anti-reflective
materials, such as the silicon-rich silicon nitride DARC disclosed
in U.S. Pat. No. 5,378,659, which issued to Roman et al. on Jan. 3,
1995; and 5,539,249, which issued to Roman et al. on Jul. 23, 1996;
and the silicon, oxygen and nitrogen DARC materials disclosed in
U.S. Pat. No. 5,698,352, which issued to Ogawa et al. on Dec. 16,
1997, may be deposited by known processes, such as chemical vapor
deposition (CVD) or plasma-enhanced CVD (PECVD).
[0010] The plasmas that are employed to fabricate layers of
materials on semiconductor device structures may cause particulate
contamination of PECVD process chambers. These contaminant
particles may be subsequently disposed upon the surfaces of the
exposed layers of a semiconductor device structure that is being
processed within the process chamber.
[0011] Some PECVD-fabricated DARC films, however, typically have
surface roughness features or particles of a size of less than
about 120 nanometers (nm) dimension on the surfaces thereof. These
rough surfaces or particles may act as "seeds" for the growth of
larger particles when silicon nitride is subsequently disposed on
the DARC film. Thus, when silicon nitride films or structures are
subsequently fabricated over PECVD-fabricated DARC films which
include silicon, oxygen and nitrogen, seed particles or surface
roughness features on the DARC film are known to enhance increased
growth of silicon nitride thereover during fabrication of a silicon
nitride layer on the DARC film, which may create non-uniformities
or particles of about 120-150 nm dimension in the silicon nitride
layer, which are referred to as "in-film" particles, at an
incidence of about 40,000 or more per eight inch semiconductor
wafer. Such in-film particles are undesirable because they may
cause structural deformities or other problems in semiconductor
device structures of ever-decreasing dimensions.
[0012] After such a DARC film has been deposited on a semiconductor
device structure and prior to removal of the semiconductor device
structure and insertion of one or more subsequent semiconductor
device structures into the process chamber, the process chamber is
cleaned, which typically includes purging the chamber with an inert
gas, such as helium. An undesirable number of particles or surface
roughness features which may act as seeds for in-film particles of
about 120-150 nm dimension may, however, remain present on DARC
films that are fabricated in a chamber cleaned with such a helium
purge.
[0013] Alternatively, semiconductor wafers or other semiconductor
device structures may be heated prior to DARC film fabrication
thereon in order to reduce the occurrence of particles or surface
roughness of less than about 120 nm. Such preheating, however, is
undesirable in that the wafer throughput is limited, thereby
raising production costs, as more chambers are required to achieve
the same level of throughput that may be achieved without such
preheating.
[0014] U.S. Pat. Nos. 5,637,190 (the '"190 patent"), which issued
to Liao on Jun. 10, 1997; and 5,700,741 (the '"741 patent"), which
issued to Liao on Dec. 23, 1997, disclose exemplary processes for
removing contaminants from a reaction chamber by a plasma-assisted
purge. The '741 patent discloses a plasma purge process which
includes performing a plasma-assisted process on one or more layers
of a semiconductor device structure and employing a radio frequency
plasma to polarize and dilute any contaminants that remain in the
process chamber while the semiconductor device structure remains in
the process chamber, thereby decreasing the likelihood that any
contaminant particles will contaminate the semiconductor device
structure. The purging radio frequency plasma is generated at a
lower power than the previously-employed process plasma in order to
polarize any contaminants in the process chamber. The pressure
within the process chamber is increased during the purge to dilute
any contaminants that remain in the process chamber. The purge gas
includes an oxidizing purge gas component, and may also include a
non-oxidizing component. Subsequently, the plasma purge may be
repeated, but at a lower radio frequency power and an increased
process chamber pressure.
[0015] The '190 patent discloses a similar process that employs a
plasma including both oxidizing and non-oxidizing components. The
plasma of the '190 patent, however, chemically and physically
etches any contaminants remaining in the process chamber, as well
as polarizing and diluting the contaminants. The plasma power and
process chamber pressure requirements of the '190 patent are
similar to those of the '741 patent.
[0016] Although the '190 and '741 patents discuss processes which
decrease the amount of contamination in a process chamber following
fabrication or definition of silicon oxide layers of a
semiconductor device, neither of them disclose use of the purge
process to reduce surface roughness or particles on the surface of
DARC films that include silicon, oxygen and nitrogen or the
formation of in-film particles in a silicon nitride overlayer.
Moreover, the processes disclosed in those patents employ oxidizing
purge gases, which may not be useful for reducing or eliminating
the occurrence of particles or a rough surface on a DARC film that
includes silicon, oxygen and nitrogen. Neither the '190 patent nor
the '741 patent addresses the removal of contaminants from a
process chamber after a deposition operation, removal of the coated
semiconductor device structure or other structures and prior to
disposing another semiconductor device structure in the process
chamber or to fabricating a DARC film thereon by PECVD techniques
to reduce or eliminate the incidence of particles or an unduly
rough surface on the DARC film.
[0017] Thus, a plasma purge process which employs a substantially
inert gas is needed to reduce or eliminate the incidence of
particles or magnitude of surface roughness features on the surface
of PECVD-fabricated DARC films that include silicon, oxygen and
nitrogen. A plasma purge process is also needed which may be
employed prior to disposing a semiconductor device structure into a
PECVD process chamber for processing.
SUMMARY OF THE INVENTION
[0018] The present invention addresses the foregoing needs.
[0019] The DARC film fabrication method of the present invention
includes purging a PECVD process chamber with an inert gas radio
frequency plasma (e.g., a helium radio frequency plasma), disposing
a semiconductor device structure, such as a silicon, gallium
arsenide or indium phosphide wafer, or other semiconductor
structures, such as silicon on glass (SOG), silicon on Hs insulator
(SOI), or silicon on sapphire (SOS), in the PECVD process chamber
and fabricating a IDARC film on the semiconductor device structure.
Inert gases that are useful in the radio frequency purge plasma
include, without limitation, nitrogen (N), those gases that are
typically referred to as "noble gases" (e.g., helium (He), argon
(Ar), xenon (Xe), etc.), and combinations of inert gases.
[0020] The DARC film that is fabricated on the semiconductor device
structure preferably includes silicon, nitrogen, and oxygen, and is
deposited onto the semiconductor device structure by known PECVD
processes. The DARC film may also include hydrogen. Following the
fabrication of the DARC film, the semiconductor device structure
may be removed from the PECVD process chamber. The radio frequency
plasma purge process of the present invention is then conducted
prior to fabricating a DARC film on one or more other semiconductor
device structures to be subsequently inserted in the chamber.
Alternatively, the inventive inert gas radio frequency plasma purge
process may be employed after the DARC film has been deposited onto
the surface of the semiconductor device structure and prior to
removal of the semiconductor device structure from the process
chamber. The inventive inert gas radio frequency plasma purge
process may also be employed during deposition of a DARC film on
the semiconductor device structure. A DARC film that is fabricated
in accordance with the inventive method has a smooth surface
relative to conventionally fabricated DARC films that include
silicon, oxygen and nitrogen, and has a reduced number or is
substantially free of small (e.g., sub-120 nm) particles or surface
roughness features.
[0021] After a DARC film has been fabricated on a semiconductor
device structure in accordance with the inventive method, and the
semiconductor device structure removed from the PECVD process
chamber, a silicon nitride (Si.sub.3N.sub.4) layer or structure may
be fabricated over the DARC film by processes that are known in the
art. Due to the reduction in the amount or size of surface
roughness features or particles on a silicon, oxygen and
nitrogen-including DARC film that is fabricated in accordance with
the present invention, fewer or smaller particles are formed in the
silicon nitride layer than those formed in many
conventionally-fabricated silicon nitride layers that overlie DARC
films. Thus, significantly less "seeding," which may result in the
formation of undesirably large quantities or magnitudes of in-film
particles and non-uniformnities on the surface of the layer of the
silicon nitride, occurs. Accordingly, a semiconductor device
structure including silicon nitride that is disposed upon a DARC
that includes silicon, oxygen and nitrogen, and has an imperfection
density of less than about 40,000 particles of about 120-150 nm
dimension per eight inch diameter semiconductor wafer is also
within the scope of the present invention. The semiconductor device
structure of the present invention may be substantially free of
such in-film particles.
[0022] The DARC film fabrication method of the present invention
may also include disposing a photoresist over the silicon nitride
layer, disposing a diffraction grating between the semiconductor
device structure and an electromagnetic radiation source, and
directing electromagnetic radiation of a specified wavelength range
through the diffraction grating to expose selected areas of the
photoresist in order to define a mask therefrom. As is known in the
art, the silicon nitride layer and DARC film absorb a significant
amount of the electromagnetic radiation (light) that passes through
the photoresist. Some of the electromagnetic radiation is, however,
reflected back into the photoresist. Accordingly, the reduction or
elimination of in-film particles reduces the reflection of
electromagnetic radiation in a non-perpendicular direction to the
surface of the silicon nitride layer and, consequently, reduces the
exposure of shielded areas of the photoresist to the
electromagnetic radiation, which may also decrease the degree of
distortion in the resultant mask. Thus, a semiconductor device
structure including a mask, which has a substantially uniform
thickness and openings of substantially desired dimensions and
resolution, that is disposed over silicon nitride that overlies a
DARC including silicon and nitrogen is also within the scope of the
present invention.
[0023] The present invention also includes a process for reducing
or eliminating contaminants from a process chamber in which a
plasma may be generated, such as a PECVD chamber, a plasma-assisted
etch chamber, other types of CVD chambers, or other chambers in
which plasma-assisted semiconductor device fabrication associated
processes are performed. The process for reducing or eliminating
contaminants includes generating radio frequency plasma of inert
gas or mixture of inert gases in the process chamber prior to
conducting a plasma-assisted process therein.
[0024] Other advantages of the present invention will become
apparent to those of skill in the art through a consideration of
the ensuing description, the accompanying drawings, and the
appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0025] FIG. 1 is a schematic representation of a PECVD process
chamber in which a DARC film may be fabricated upon a semiconductor
device structure;
[0026] FIG. 1a is a schematic representation of another PECVD
process chamber in which a DARC film may be fabricated upon a
semiconductor device structure;
[0027] FIG. 2 is a schematic representation of a PECVD process
chamber, illustrating the radio frequency plasma purge process of
the present invention;
[0028] FIG. 3 is a schematic representation of DARC film
fabrication upon a semiconductor device structure in accordance
with the present invention;
[0029] FIG. 4 is a cross section of a semiconductor device which
includes a conventionally fabricated DARC film thereon, a silicon
nitride layer over the DARC film, and in film particles between the
DARC film and silicon nitride layer;
[0030] FIG. 5 is a cross section of a semiconductor device which
has been fabricated in accordance with the method of the present
invention, and which is substantially free of in-film particles
between the silicon nitride layer and DARC film thereof;
[0031] FIG. 6 is a schematic representation of a process for
forming a mask, which may be employed over a semiconductor device
structure that includes a DARC film that has been deposited in
accordance with the method of the present invention; and
[0032] FIG. 7 is a cross section of the semiconductor device of
FIG. 5, including a mask over the silicon nitride layer
thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0033] With reference to FIG. 1, a process chamber 10 of a PECVD
reactor is illustrated, in which a DARC film including silicon,
oxygen and nitrogen is deposited upon a semiconductor device
structure. PECVD process chamber 10 includes a source 11 and a
wafer support 12, which is also referred to as a susceptor.
Preferably, wafer support 12 heats a wafer or other semiconductor
device structure 14 disposed thereon from beneath by electrical
resistance. Stated another way, an active surface 16 of
semiconductor device structure 14, upon which material layers or
structures (e.g., DARC films) will be deposited, is heated through
the semiconductor device structure by wafer support 12. Exemplary
electrical resistance-heated PECVD process chambers in which the
DARC film fabrication method and the radio frequency plasma purge
process of the present invention may be conducted include, without
limitation, the process chamber of a Price DX2 PECVD reactor and
the process chambers of other single-wafer and parallel plate
electrical resistance-heated PECVD reactors known in the art.
Alternatively, with reference to FIG. 1a, PECVD process chamber 10'
may include a lamp 13, such as a halogen heat-generating lamp,
which heats an active surface 16 of a semiconductor device
structure 14 from above.
[0034] Referring now to FIG. 2, the radio frequency plasma purge
process of the present invention is schematically illustrated.
Prior to positioning any semiconductor device structures 14 (see
FIG. 1) into PECVD process chamber 10, a radio frequency purge
plasma 18 is generated within the PECVD process chamber 10 to
remove any residual DARC materials or other contaminants therefrom.
Radio frequency purge plasma 18 comprises a plasma generated from
an inert gas, such as nitrogen, a so-called "noble gas" (e.g., He,
Ar, Xe, etc.), or any combination of inert gases. Radio frequency
purge plasma 18 preferably comprises a helium plasma.
[0035] With reference again to FIG. 1, semiconductor device
structure 14 is positioned within PECVD process chamber 10 with a
back side 17 of semiconductor device structure 14 positioned
adjacent wafer support 12, and active surface 16 facing source 11
of the process chamber. In this orientation, known reactants may be
introduced into PECVD process chamber 10 to form a DARC film that
includes silicon, oxygen and nitrogen upon active surface 16 of
semiconductor device structure 14.
[0036] Turning to FIG. 3, reactants 20 are introduced into PECVD
process chamber 10 and a radio frequency reactant plasma 22 is
generated between source 11 and active surface 16 in order to
effect the deposition of a DARC film 24 on active surface 16. When
the material of DARC film 24 comprises Si.sub.xO.sub.yN.sub.z,
where x equals 0.40 to 0.65, y equals 0.02 to 0.56 and z equals
0.05 to 0.33, known reactants, such as a mixture of SiH.sub.4,
N.sub.2O and He or a mixture of SiH.sub.4,O.sub.2 and N.sub.2, may
be employed. Preferably, x+y+z equals one. The material of DARC
film 24 may also include hydrogen. An exemplary DARC film 24 may
have the general formula Si.sub.0.50O.sub.0.37N.sub.0.13H. A buffer
gas such as Ar may also be introduced into PECVD process chamber 10
with reactants 20. Preferably, known process parameters, including,
without limitation, the relative amounts of each of reactants 20
and any buffer gases, the process chamber pressure and temperature,
and the amount of power that is employed to generate radio
frequency reactant plasma 22, are employed to fabricate DARC film
24.
[0037] Referring again to FIG. 2, an inert gas radio frequency
purge plasma 18 is generated in PECVD process chamber 10 following
the deposition of a DARC film 24 upon a semiconductor device
structure 14 (see FIG. 3), and preferably prior to the insertion of
another semiconductor device structure into the process chamber.
Preferably, purge plasma 18 is generated after a semiconductor
device structure 14 carrying a DARC film 24 has been removed from
PECVD process chamber 10. Purge plasma 18 may, however, be
generated while DARC film 24-carrying semiconductor device
structure 14 remains in PECVD process chamber 10. Purge plasma 18
may also be generated during the fabrication of DARC film 24 on
semiconductor device structure 14. Alternatively, purge plasma 18
may be generated after another semiconductor device structure has
been placed in PECVD process chamber 10, and prior to the
deposition of a DARC film thereon.
[0038] FIG. 4 illustrates a semiconductor device structure 40 which
carries a conventionally deposited DARC film 42 of
Si.sub.xO.sub.yN.sub.z:H and a silicon nitride layer 46 disposed
upon the DARC film 42. The semiconductor device structure 40 of
FIG. 4 includes "particles" or surface roughness features on DARC
film 42, which act as seeds for particles that form in silicon
nitride layer 46, which are also referred to as in-film particles
44. As discussed previously, in-film particles 44 typically have a
size of about 120-150 nm and a density on semiconductor device
structure 40 of about 40,000 or more per eight inch diameter
wafer.
[0039] In contrast, FIG. 5 illustrates a semiconductor device
structure 14 of the present invention, which includes a silicon
nitride layer 26, which is also referred to as an "overlayer," that
is fabricated on DARC film 24 by known processes, such as LPCVD,
CVD or PECVD processes. As FIG. 5 depicts, the number of about
120-150 nm dimension particles in silicon nitride layer 26 is
substantially reduced. Silicon nitride layer 26 may be
substantially free of particles or surface roughness features in
the about 120-150 nm size range.
[0040] Referring now to FIG. 6, in order to pattern a structure
from a material layer 23 of semiconductor device structure 14 that
underlies DARC film 24, a mask 28 (see FIG. 7) may be formed over
silicon nitride layer 26 by known techniques. For example, known
photoresist material 30 may be disposed over silicon nitride layer
26 by a known technique, such as spin-on processes. Exemplary
photoresist materials 30 include positive photoresists, such as
those that include a novolac resin, a diazonaphthaquinone, and a
solvent (e.g., n-butyl alcohol or xylene), and negative photoresist
materials, such as those that include a cyclized synthetic rubber
resin, bis-arylazide, and an aromatic solvent.
[0041] A diffraction grating 32 is then disposed between
photoresist material 30 and an electromagnetic radiation source 34.
A reticle 31 or mask is disposed between diffraction grating 32 and
the layer of photoresist material 30. Electromagnetic radiation 36,
or light, of a specified wavelength range is emitted from source 34
and directed toward and through diffraction grating 32, toward
reticle 31, and through transparent portions, or "openings" 33, of
reticle 31 to certain exposed regions 38 of photoresist material
30. Preferably, electromagnetic radiation 36 is directed
substantially perpendicularly to the surface of silicon nitride
layer 26.
[0042] Referring now to FIG. 7, as is known in the art, as regions
38 are exposed to electromagnetic radiation 36, various features 29
of mask 28 are defined. Due to the substantial reduction in the
number or size of particles and surface roughness features in
silicon nitride layer 26, the silicon nitride layer has a
substantially smooth surface, and any electromagnetic radiation 36
that is reflected by silicon nitride layer 26 or DARC film 24
passes back into photoresist material 30 in a direction
substantially perpendicular to the surface of silicon nitride layer
26. Accordingly, features 29 of mask 28 have substantially the
desired dimensions and resolution. Moreover, the thickness of mask
28 is substantially uniform.
[0043] Silicon nitride layer 26 may then be patterned by known
processes, such as anisotropic or isotropic etching, to form a hard
mask therefrom. DARC film 24 and one or more layers 23 of
semiconductor device structure 14 that underlie DARC film 24 may
then be patterned by known processes to define semiconductor device
features of substantially desired dimensions and resolution
therefrom. Alternatively, silicon nitride layer 26, DARC film 24,
and one or more layers 23 of semiconductor device structure 14 that
underlie DARC film 24 may be patterned through mask 28 at the same
time by known processes to define semiconductor device features of
substantially desired dimensions and resolution therefrom.
[0044] With reference again to FIG. 3, other processes for
depositing a DARC film 24 of Si.sub.xO.sub.yN.sub.z:H upon a
semiconductor device structure 14 that are known in the art, such
as CVD, electron cyclotron resonance (ECR) PECVD, and bias ECR
PECVD processes, may also be employed in accordance with the DARC
film fabrication method of the present invention. Similarly, the
inert gas radio frequency plasma purge process of the present
invention may be employed to remove contaminants from the process
chambers of other types of reactors, such as CVD, ECR PECVD, and
bias ECR PECVD reactors.
[0045] Although the foregoing description includes many specifics,
these should not be construed as limiting the scope of the present
invention, but merely as providing illustrations of some of the
presently preferred embodiments. Similarly, other embodiments of
the invention may also be devised which do not depart from the
spirit or scope of the present invention. The scope of the present
invention is, therefore, indicated and limited only by the appended
claims and their legal equivalents, rather than by the foregoing
description. All additions, deletions and modifications to the
invention as disclosed herein which fall within the meaning and
scope of the claims are to be embraced thereby.
* * * * *