U.S. patent application number 09/865923 was filed with the patent office on 2001-10-04 for method for patterning semiconductor devices on a silicon substrate using oxynitride film.
This patent application is currently assigned to VANGUARD INTERNATIONAL SEMICONDUCTOR CORPORATION. Invention is credited to Wang, Pin-Ting, Yao, Liang-Gi.
Application Number | 20010027021 09/865923 |
Document ID | / |
Family ID | 23399699 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010027021 |
Kind Code |
A1 |
Yao, Liang-Gi ; et
al. |
October 4, 2001 |
Method for patterning semiconductor devices on a silicon substrate
using oxynitride film
Abstract
A method for fabricating and patterning semiconductor devices
with a resolution down to 0.12 .mu.m on a substrate structure. The
method begins by providing a substrate structure comprising various
layers of oxide and/or nitride formed over either monocrystalline
silicon or polycrystalline silicon. A silicon oxynitride layer is
formed on the substrate structure. Key characteristics of the
oxynitride layer include: a refractive index of between about 1.85
and 2.35 at a wavelength of 248 nm, an extinction coefficient of
between 0.45 and 0.75 at a wavelength of 248 nm, and a thickness of
between about 130 Angstroms and 850 Angstroms. A photoresist layer
is formed over the silicon oxynitride layer and exposed at a
wavelength of between about 245 nm and 250 nm; whereby during
exposure at a wavelength of between 245 nm 250 nm, the silicon
oxynitride layer provides a phase-cancel effect.
Inventors: |
Yao, Liang-Gi; (Taipei,
TW) ; Wang, Pin-Ting; (Taichung, TW) |
Correspondence
Address: |
George O. Saile
20 McIntosh Drive
Poughkeepsie
NY
12603
US
|
Assignee: |
VANGUARD INTERNATIONAL
SEMICONDUCTOR CORPORATION
|
Family ID: |
23399699 |
Appl. No.: |
09/865923 |
Filed: |
May 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09865923 |
May 29, 2001 |
|
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09356006 |
Jul 16, 1999 |
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6258734 |
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Current U.S.
Class: |
438/694 ;
257/E21.257; 257/E21.267; 438/702; 438/706; 438/714 |
Current CPC
Class: |
H01L 21/02271 20130101;
H01L 21/31144 20130101; G03F 7/091 20130101; H01L 21/02211
20130101; H01L 21/0214 20130101; G03F 1/26 20130101; H01L 21/3143
20130101; H01L 21/02247 20130101 |
Class at
Publication: |
438/694 ;
438/702; 438/706; 438/714 |
International
Class: |
H01L 021/311; H01L
021/302; H01L 021/461 |
Claims
What is claimed is:
1. A method of patterning semiconductor devices with a resolution
down to 0.12 .mu.m on a substrate structure comprising the steps
of: a. forming an oxide layer over a monocrystalline silicon
substrate structure; b. forming a nitride layer on said oxide
layer; said nitride layer having a refractive index of between 2.28
and 2.32 at a wavelength of 248 nm; c. forming a silicon oxynitride
layer on said nitride layer; said silicon oxynitride layer having a
refractive index of between about 1.85 and 2.35 at a wavelength of
248 nm, an extinction coefficient of between 0.45 and 0.75 at a
wavelength of 248 nm, and a thickness of between about 130
Angstroms and 850 Angstroms; d. forming a photoresist layer over
said silicon oxynitride layer; and e. exposing said photoresist at
a wavelength of between about 245 nm and 250 nm; whereby during
exposure at a wavelength of between 245 nm 250 nm, said silicon
oxynitride layer provides a phase-cancel effect.
2. The method of claim 1 wherein said nitride layer has a thickness
of between about 1000 Angstroms and 2500 Angstroms and said oxide
layer has a thickness of between about 50 Angstroms and 300
Angstroms.
3. The method of claim 1 which further includes etching said
oxynitride layer, said nitride layer and said oxide layer to form a
contact opening.
4. The method of claim 1 wherein said photoresist layer has a
thickness of between about 3000 Angstroms and 8000 Angstroms.
5. The method of claim 1 wherein said oxide layer is formed using a
LPCVD process; said nitride layer is formed using LPCVD; and said
silicon oxynitride layer is formed by reacting silane, nitric oxide
and helium in a plasma at temperatures between about 200.degree. C.
and 550.degree. C., at a pressure of between about 3 torr and 8
torr, and at a power of between about 120 watts and 200 watts.
6. A method of patterning semiconductor devices with a resolution
down to 0.12 .mu.m on a substrate structure comprising the steps
of: a. forming an oxide layer on a silicon layer overlying a
substrate structure; said oxide layer being composed of silicon
glass; b. forming a silicon oxynitride layer on said oxide layer;
said silicon oxynitride layer having a refractive index of between
about 1.85 and 2.35 at a wavelength of 248 nm, an extinction
coefficient of between 0.45 and 0.75 at a wavelength of 248 nm, and
a thickness of between about 130 Angstroms and 850 Angstroms; c.
forming a photoresist layer over said silicon oxynitride layer; and
d. exposing said photoresist layer at a wavelength of between about
245 nm and 250 nm; whereby during exposure at a wavelength of
between 245 nm and 250 nm, said silicon oxynitride layer provides a
phase-cancel effect.
7. The method of claim 6 wherein said oxide layer is composed of
undoped silicon glass, has a thickness of between about 1000
Angstroms and 5000 Angstroms, has a refractive index of between
about 1.4 and 1.65, and is formed using an O.sub.3-TEOS
process.
8. The method of claim 6 wherein said oxide layer is composed of
boron doped silicon glass and has a thickness of between about 1000
Angstroms and 5000 Angstroms, has a refractive index of between
about 1.4 and 1.65, and is formed using an O.sub.3-TEOS
process.
9. The method of claim 6 wherein said oxide layer is composed of
boron and phosphorous doped silicon glass and has a thickness of
between about 1000 Angstroms and 5000 Angstroms, has a refractive
index of between about 1.4 and 1.65, and is formed using an
O.sub.3-TEOS process.
10. The method of claim 6 which further includes etching said
oxynitride layer and said oxide layer to form a contact opening and
removing said photoresist layer.
11. The method of claim 6 wherein said photoresist layer has a
thickness of between about 3000 Angstroms and 8000 Angstroms.
12. The method of claim 6 wherein said silicon oxynitride layer is
formed by reacting silane, nitric oxide and helium in a plasma at
temperatures between about 200.degree. C. and 550.degree. C., at a
pressure of between about 3 torr and 8 torr, and at a power of
between about 120 watts and 200 watts.
13. A method of patterning semiconductor devices with a resolution
down to 0.12 .mu.m on a substrate structure comprising the steps
of: a. forming a nitride layer on a silicon layer of a substrate
structure; said nitride layer having a refractive index of between
2.28 and 2.32 at a wavelength of 248; b. forming a silicon
oxynitride layer on said nitride layer; said silicon oxynitride
layer having a refractive index of between about 1.85 and 2.35 at a
wavelength of 248 nm, an extinction coefficient of between 0.45 and
0.75 at a wavelength of 248 nm, and a thickness of between about
130 Angstroms and 850 Angstroms; c. forming a photoresist layer
over said silicon oxynitride layer; and d. exposing said
photoresist at a wavelength of between about 245 nm and 250 nm;
whereby during exposure at a wavelength of between 245 nm and 250
nm, said silicon oxynitride layer provides a phase-cancel
effect.
14. The method of claim 13 wherein said nitride layer has a
thickness of between about 1000 Angstroms and 2500 Angstroms.
15. The method of claim 13 which further includes forming a
dielectric layer over said silicon oxynitride layer and planarizing
said dielectric layer prior to forming said photoresist layer; and
etching said dielectric layer, said oxynitride layer and said
nitride layer to form a contact opening after exposing said
photoresist layer.
16. The method of claim 13 wherein said photoresist layer has a
thickness of between about 3000 Angstroms and 8000 Angstroms.
17. The method of claim 13 wherein said nitride layer is formed
using a LPCVD process and said silicon oxynitride layer is formed
by reacting silane, nitric oxide and helium in a plasma at
temperatures between about 200.degree. C. and 550.degree. C., at a
pressure of between about 3 torr and 8 torr, and at a power of
between about 120 watts and 200 watts.
Description
BACKGROUND OF INVENTION
[0001] 1) Field of the Invention
[0002] This invention relates generally to fabrication of
semiconductor devices and more particularly to patterning
semiconductor devices with resolution down to 0.12 .mu.m on a
silicon substrate using oxynitride film.
[0003] 2) Description of the Prior Art
[0004] The semiconductor industry's continuing drive toward
semiconductor devices with ever decreasing geometries coupled with
the reflective property of monocrystalline silicon and
polycrystalline silicon (polysilicon, poly) have led to increasing
photolithographic patterning problems. Unwanted reflections from
the underlying monocrystalline silicon or polycrystalline silicon
during the photolithographic patterning process cause the resulting
photoresist patterns to be distorted. Diffraction of the light
waves used to expose the photoresist during patterning also causes
distortion of the resulting patterns.
[0005] Organic and inorganic bottom anti-reflective coatings have
been attempted on both monocrystalline silicon and polycrystalline
silicon to absorb reflected energy and prevent pattern distortion.
However, different film thicknesses due to surface topography after
coating will cause etching issues, photoresist loss and poor after
etch inspection (AEI) dimensions.
[0006] Phase-shifting masks have been used to compensate for
diffraction and enhance the resolution of photolithographic
patterns. A phase shift layer is used to cover one of a pair of
adjacent apertures of the pattern mask during exposure. The phase
shifting layer reverses the sign of the electric field of its
aperture. The distortions of the electric field from adjacent
appertures caused by diffraction cancel because they have opposite
signs. The phase change is a function of wavelength and thickness
of the transparent phase shifting layer. However, phase shifting
masks do not prevent distortion from reflections.
[0007] The importance of overcoming the various deficiencies noted
above is evidenced by the extensive technological development
directed to the subject, as documented by the relevant patent and
technical literature. The closest and apparently more relevant
technical developments in the patent literature can be gleaned by
considering the following patents.
[0008] U.S. Pat. No. 5,600,165 (Tsukamoto et al.) shows a SiON
layer as a bottom ARC over several different structures, including
polysilicon, oxide, and silicides.
[0009] U.S. Pat. No. 5,639,687 (Roman et al.) shows a Si-rich SiON
ARC layer in which thickness (t) is determined as a function of
wavelength (.lambda.) and refractive index (n) using the formula
t=.lambda./4n.
[0010] U.S. Pat. No. 5,252,515 (Tsai et al.) teaches a process for
forming SiON ARC layer with refractive index (n) of between 1.5 and
2.1 by controlling the silane flow rate.
[0011] U.S. Pat. No. 4,717,631 (Kaganowicz et al.) shows a SiON
passivation layer having a refractive index (n) of between 1.55 and
1.75 at a wavelength (.lambda.) of 632.8 nm.
SUMMARY OF THE INVENTION
[0012] It is an object of the present invention to provide a method
of patterning semiconductor devices on a silicon substrate using
oxynitride films.
[0013] It is another object of the present invention to provide a
method of patterning semiconductor devices with a resolution down
to 0.12 .mu.m on monocrystalline silicon or polycrystalline
silicon.
[0014] It is yet another object of the present invention to provide
a method of patterning semiconductor devices using both patterned
structure and optical properties of oxynitride to acheive
resolution down to 0.12 .mu.m.
[0015] To accomplish the above objectives, the present invention
provides a method for fabricating and patterning semiconductor
devices with a resolution down to 0.12 .mu.m on a substrate
structure (10). The method begins by providing a substrate
structure comprising various layers of oxide and/or nitride formed
over either monocrystalline silicon or polycrystalline silicon. A
silicon oxynitride layer (16) is formed on the substrate structure
(10). Key characteristics of the oxynitride layer include: a
refractive index of between about 1.85 and 2.35 at a wavelength of
248 nm, an extinction coefficient of between 0.45 and 0.75 at a
wavelength of 248 nm, and a thickness of between about 130
Angstroms and 850 Angstroms. A photoresist layer (20) is formed
over the silicon oxynitride layer (16) and exposed at a wavelength
of between about 245 nm and 250 nm; whereby during exposure at a
wavelength of between 245 nm and 250 nm, the silicon oxynitride
layer (16) provides a phase-cancel effect, and acts as an inorganic
anti-reflective coating, absorbing reflected light energy.
[0016] The present invention provides considerable improvement over
the prior art. The absorptive properties of the oxynitride layer
(20) reduce the amount of reflected energy, thereby reducung
pattern distortion. A key advantage of the present invention is
that during exposure, the silicon oxynitride layer (16) also
provides a phase-cancel effect. The reflected light is out of phase
with and cancels the diffracted light energy, further reducing
pattern distortion.
[0017] The present invention achieves these benefits in the context
of known process technology. However, a further understanding of
the nature and advantages of the present invention may be realized
by reference to the latter portions of the specification and
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The features and advantages of a semiconductor device
according to the present invention and further details of a process
of fabricating such a semiconductor device in accordance with the
present invention will be more clearly understood from the
following description taken in conjunction with the accompanying
drawings in which like reference numerals designate similar or
corresponding elements, regions and portions and in which:
[0019] FIG. 1 is a sectional view of a device fabricated according
the first embodiment of the invention.
[0020] FIG. 2 is a sectional view of a device fabricated according
the second embodiment of the invention.
[0021] FIG. 3 is a sectional view of a device fabricated according
the third embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention will be described in detail with
reference to the accompanying drawings.
[0023] Substrate structure as used herein means a monocrystalline
silicon structure suitable for manufacturing semiconductor devices
which can have one or more processing steps already performed
thereon. Silicon layer as used herein means either a
monocrystalline layer or a polycrystalline layer formed over a
substrate structure unless otherwise stated.
[0024] First Embodiment
[0025] In the first embodiment, a silicon oxynitride layer (16) is
formed over a monocrystalline silicon substrate structure (10), an
oxide layer (12) and a nitride layer (14) and patterned with a
resolution of down to 0.12 .mu.m.
[0026] The process begins by forming an oxide layer (12) on a
monocrystalline silicon substrate structure (10). The oxide layer
(12) is preferably formed using a LPCVD process. The oxide layer
preferably has a thickness of between about 50 Angstroms and 300
Angstroms.
[0027] A nitride layer (14) is formed on the oxide layer (12). The
nitride layer is preferably formed using LPCVD and has a thickness
of between about 1000 Angstroms and 2500 Angstroms. The nitride
layer has a refractive index of between 2.28 and 2.32 and an
extinction coefficient of between about 0.015 and 0.025 at a
wavelength of 248 nanometers.
[0028] A silicon oxynitride layer (16) is formed on the nitride
layer (14). The silicon oxynitride layer (16) has a refractive
index of between about 1.85 and 2.35 and an extinction coefficient
of between 0.45 and 0.75 at a wavelength of 248 nanometers. The
silicon oxynitride layer preferably has a thickness of between
about 130 Angstroms and 850 Angstroms.
[0029] The silicon oxynitride layer (16) can be formed using a
plasma enhanced chemical vapor deposition (PECVD) process at a
temperature of between about 200.degree. C. and 550.degree. C., at
a pressure of between about 3 torr and 8 torr, and at a power of
between about 120 Watts and 200 Watts. The silicon oxynitride layer
(16) is preferably formed in a plasma deposition chamber such as an
Applied Materials Centura or PE5000 using silane at a flow rate of
between about 30 sccm and 80 sccm, nitric oxide at a flow rate of
between about 50 sccm and 130 sccm, and helium at a flow rate of
between about 1500 sccm and 2500 sccm. It should be understood that
the flow rates and power can be scaled up or down depending upon
chamber size provided the ratios are maintained.
[0030] A photoresist layer (20) is formed over the silicon
oxynitride layer (16). The photoresist layer (20) has a thickness
of between about 3000 Angstroms and 8000 Angstroms.
[0031] The photoresist layer (20) is exposed to light energy at a
wavelength of between about 245 nanometers and 250 nanometers. The
absorptive properties of the oxynitride layer (20) reduce the
amount of reflected energy, thereby reducung pattern distortion. A
key advantage of the present invention is that during exposure, the
silicon oxynitride layer (16) also provides a phase-cancel effect.
The reflected light is out of phase with and cancels the diffracted
light energy, further reducing pattern distortion.
[0032] The photoresist layer (20) is developed to form an opening
(25). In a preferred embodiment, the oxynitride layer (16), the
nitride layer (14) and the oxide layer (12) are patterned through
the opening (25) to form a contact opening.
[0033] Second Embodiment
[0034] In the second embodiment, a silicon oxynitride layer (16) is
formed on an oxide layer (12B) overlying a monocrystalline or
polycrystalline silicon layer (11), either with or without a
tungsten silicide top layer, and overlying a substrate structure
(10), and patterned with a resolution of down to 0.12 .mu.m.
[0035] The method begins by forming an oxide layer (12B) on a
silicon layer (11) overlying a substrate structure (10). The oxide
layer (12B) is preferably composed of a silicon glass such as
undoped silicon glass (USG), boron and phosphorous doped silicon
glass (BPSG) or phosphorous doped silicon glass (PSG) as are known
in the art. The oxide layer (12B) of the second embodiment
preferably has a thickness of between about 1000 Angstroms and 5000
Angstroms, a refractive index (n) of between about 1.4 and 1.65,
and an extinction coefficient (k) of between about 0 and 0.1. The
oxide layer (12B) is preferably formed using an O.sub.3-TEOS
process as is known in the art. In a preferred embodiment, the
silicon layer (11) overlies a first oxide layer (12A), which
overlies the substrate structure (10).
[0036] A silicon oxynitride layer (16) is formed on the oxide layer
(12B). The silicon oxynitride layer (16) has a refractive index of
between about 1.85 and 2.35 and an extinction coefficient of
between 0.45 and 0.75 at a wavelength of 248 nanometers. The
silicon oxynitride layer preferably has a thickness of between
about 130 Angstroms and 850 Angstroms.
[0037] The silicon oxynitride layer (16) is preferably formed by
reacting silane, nitric oxide and helium in a plasma at
temperatures between about 200.degree. C. and 550.degree. C., at a
pressure of between about 3 torr and 8 torr, and at a power of
between about 120 watts and 200 watts.
[0038] A photoresist layer (20) is formed over the silicon
oxynitride layer (16). The photoresist layer (20) has a thickness
of between about 3000 Angstroms and 8000 Angstroms.
[0039] The photoresist layer (20) is exposed to light energy at a
wavelength of between about 245 nanometers and 250 nanometers and
developed to form openings (25) in the photoresist layer (20).
[0040] In a preferred embodiment, the oxynitride layer (16), the
nitride layer (14) and the oxide layer (12B) are patterned through
the openings (25) to form a contact opening.
[0041] Third Embodiment
[0042] In the third embodiment, a silicon oxynitride layer (16) is
formed over a nitride layer (14) and a monocrystalline or
polycrystalline silicon layer (11), either with or without a
tungsten silicide top layer, on a substrate structure (10), and
patterned with a resolution of down to 0.12 .mu.m.
[0043] The method begins by forming a nitride layer (14) on a
silicon layer (11) of a substrate. The nitride layer is formed
using a LPCVD process and having a refractive index of between 2.28
and 2.32 and an extinction coefficient (k) of between about 0.015
and 0.025 at a wavelength of 248 nanometers.
[0044] A silicon oxynitride layer (16) is formed on the nitride
layer (14). The silicon oxynitride layer (16) has a refractive
index of between about 1.85 and 2.35 and an extinction coefficient
of between 0.45 and 0.75 at a wavelength of 248 nanometers. The
silicon oxynitride layer preferably has a thickness of between
about 130 Angstroms and 850 Angstroms.
[0045] The silicon oxynitride layer (16) is preferably formed by
reacting silane, nitric oxide and helium in a plasma at
temperatures between about 200.degree. C. and 550.degree. C., at a
pressure of between about 3 torr and 8 torr, and at a power of
between about 120 watts and 200 watts.
[0046] A dielectric layer (18) is formed over the oxynitride layer
(16) and planarized. the dielectric layer (18) is preferably
composed of doped or undoped silicon glass as is known in the
art.
[0047] A photoresist layer (20) is formed over the silicon
oxynitride layer (16). The photoresist layer (20) has a thickness
of between about 3000 Angstroms and 5000 Angstroms. The photoresist
layer (20) is exposed to light energy at a wavelength of between
about 245 nanometers and 250 nanometers and developed.
[0048] In a preferred embodiment, the dielectric layer (18), the
oxynitride layer (16), and the nitride layer (14) are patterned
through the openings to form a contact opening.
[0049] While the invention has been particularly shown and
described with reference to the preferred embodiments thereof, it
will be understood by those skilled in the art that various changes
in form and details may be made without departing from the spirit
and scope of the invention.
* * * * *