U.S. patent application number 09/935833 was filed with the patent office on 2001-12-27 for method for improving thickness uniformity of deposited ozone-teos silicate glass layers.
Invention is credited to Iyer, Ravi.
Application Number | 20010055889 09/935833 |
Document ID | / |
Family ID | 25286011 |
Filed Date | 2001-12-27 |
United States Patent
Application |
20010055889 |
Kind Code |
A1 |
Iyer, Ravi |
December 27, 2001 |
Method for improving thickness uniformity of deposited ozone-TEOS
silicate glass layers
Abstract
A method for depositing highly conformal silicate glass layers
via chemical vapor deposition through the reaction of TEOS and
O.sub.3 comprises placing an in-process semiconductor wafer having
multiple surface constituents in a plasma-enhanced chemical vapor
deposition chamber. A "clean" silicate glass base layer
substantially free of carbon particle impurities on an upper
surface is formed in one of two ways. The first employs
plasma-enhanced chemical vapor deposition using TEOS and diatomic
oxygen gases as precursors to first deposit a "dirty" silicate
glass base layer having carbon particle impurities imbedded on an
upper surface thereof being transformed to a clean base layer by
subjecting it to a plasma treatment, using a mixture of a
diamagnetic oxygen-containing oxidant, such as ozone or hydrogen
peroxide, and diatomic oxygen gas into the chamber and striking an
RF plasma. The second way employs flowing hydrogen peroxide vapor
and at least one gaseous compound selected from the group
consisting of silane and disilane into the deposition chamber for
the formation of the clean base layer and depositing a subsequent
glass layer over the PECVD-deposited glass layer using chemical
vapor deposition and TEOS and ozone as precursor compounds.
Inventors: |
Iyer, Ravi; (Boise,
ID) |
Correspondence
Address: |
TRASK BRITT
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
25286011 |
Appl. No.: |
09/935833 |
Filed: |
August 23, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09935833 |
Aug 23, 2001 |
|
|
|
09548491 |
Apr 13, 2000 |
|
|
|
6297175 |
|
|
|
|
09548491 |
Apr 13, 2000 |
|
|
|
09222565 |
Dec 29, 1998 |
|
|
|
6107214 |
|
|
|
|
09222565 |
Dec 29, 1998 |
|
|
|
08841908 |
Apr 17, 1997 |
|
|
|
Current U.S.
Class: |
438/758 ;
257/E21.279; 427/255.393; 427/578 |
Current CPC
Class: |
C03C 17/02 20130101;
H01L 21/02304 20130101; H01L 21/76834 20130101; H01L 21/76826
20130101; H01L 21/02274 20130101; H01L 21/31612 20130101; C23C
16/56 20130101; H01L 21/02164 20130101; C23C 16/0245 20130101; C23C
16/401 20130101; H01L 21/0234 20130101; H01L 21/76837 20130101;
H01L 21/022 20130101; H01L 21/02126 20130101; C23C 16/0272
20130101; H01L 21/02271 20130101 |
Class at
Publication: |
438/758 ;
427/255.393; 427/578 |
International
Class: |
C23C 016/24; H01L
021/31 |
Claims
What is claimed is:
1. A method of depositing silicate glass on a substrate comprising:
placing a substrate within a plasma-enhanced chemical vapor
deposition chamber; providing a first gaseous mixture comprising
TEOS, oxygen, and at least one inert carrier gas to form a first
gaseous atmosphere in the plasma-enhanced chemical vapor deposition
chamber; generating a plasma surrounding the substrate in the
plasma-enhanced chemical vapor deposition chamber in the first
gaseous mixture comprising TEOS, oxygen, and at least one inert
carrier gas; depositing a silicate glass base layer on the
substrate, said silicate glass base layer having carbonaceous
impurities, at least some of said carbonaceous impurities being
exposed on an upper surface of said silicate glass base layer;
providing a second gaseous mixture comprising oxygen and hydrogen
peroxide to form a second gaseous atmosphere in the plasma-enhanced
chemical vapor deposition chamber; igniting a plasma in the second
gaseous atmosphere in the plasma-enhanced chemical vapor deposition
chamber; contacting at least the upper surface of said silicate
glass base layer with at least a portion of the plasma in the
second gaseous atmosphere in the plasma-enhanced chemical vapor
deposition chamber comprising oxygen and hydrogen peroxide to
convert a portion of the carbonaceous impurities on the upper
surface of said silicate glass base layer to a gas; preventing the
carbonaceous impurities converted to the gas from contacting said
silicate glass base layer by removing the carbonaceous impurities
from the plasma-enhanced chemical vapor deposition chamber;
depositing a final glass layer on said upper surface of said
silicate glass base layer by flowing a third gaseous atmosphere
comprising TEOS and ozone into the plasma-enhanced chemical vapor
deposition chamber.
2. The method of claim 1, wherein said second gaseous atmosphere is
removed from the plasma-enhanced chemical vapor deposition chamber
prior to the deposition of the final glass layer.
3. The method of claim 1, wherein a thickness of said silicate
glass base layer is within a range of about 100 to about 1000
.ANG..
4. The method of claim 1, wherein contacting said silicate glass
base layer is performed with a plasma generated with a power
density setting of about 0.7 to about 3.0 watts/cm.sup.2.
5. The method of claim 1, wherein contacting said silicate glass
base layer to the plasma lasts for a period of about 30 to about
360 seconds.
6. The method of claim 1, wherein said final glass layer is
deposited at a temperature within a range of about 300 to about
600.degree. C.
7. The method of claim 1, wherein said final glass layer is
deposited at pressures within a range of about 10 to about 760
torr.
8. The method of claim 1, wherein said substrate comprises at least
a portion of a semiconductor wafer having incomplete integrated
circuits constructed thereon.
9. The method of claim 1, wherein the depositing the silicate glass
base layer, the contacting the silicate glass base layer to the
plasma, and the depositing the final glass layer are all performed
in a chemical vapor deposition chamber equipped having a plasma
generator.
10. A method of depositing silicate glass on a wafer substrate
comprising: placing a wafer substrate within a chemical vapor
deposition chamber; providing a first gaseous mixture comprising
TEOS, oxygen, and at least one inert gas to form a first gaseous
atmosphere for the chemical vapor deposition chamber; generating a
plasma using the first gaseous mixture to surround the substrate in
the chemical vapor deposition chamber; depositing a silicate glass
base layer having an upper surface on the wafer substrate, said
silicate glass base layer having exposed carbonaceous impurities at
least on the upper surface thereof; providing a second gaseous
mixture comprising oxygen and hydrogen peroxide to form a second
gaseous atmosphere; igniting a plasma in the second gaseous
atmosphere; subjecting said silicate glass base layer to at least a
portion of the plasma ignited in the second gaseous atmosphere
containing the mixture of oxygen and hydrogen peroxide to convert
at least a portion of the exposed carbonaceous impurities to a gas;
removing at least a portion of the carbonaceous impurities
converted to the gas from contact with said silicate glass base
layer; depositing a final glass layer on said upper surface of said
silicate glass base layer by flowing a third gaseous atmosphere
comprising TEOS gas and ozone gas into the chemical vapor
deposition chamber.
11. The method of claim 10, wherein said second gaseous atmosphere
is removed from the chemical vapor deposition chamber prior to the
deposition of the final glass layer.
12. The method of claim 10, wherein a thickness of said silicate
glass base layer is within a range of about 100 .ANG. to about 1000
.ANG..
13. The method of claim 10, wherein the subjecting said silicate
glass base layer comprises generating a plasma at power density
setting of about 0.7 to about 3.0 watts/cm.sup.2.
14. The method of claim 10, wherein the subjecting said silicate
glass base layer to the plasma lasts for a period of about 30 to
about 360 seconds.
15. The method of claim 10, wherein said final glass layer is
deposited at a temperature within a range of about 300 to about
600.degree. C.
16. The method of claim 10, wherein said final glass layer is
deposited at pressures within a range of about 10 to about 760
torr.
17. The method of claim 10, wherein said wafer substrate comprises
at least a portion of a semiconductor wafer having incomplete
integrated circuits constructed thereon.
18. The method of claim 10, wherein the depositing the silicate
glass base layer, the subjecting the silicate glass base layer to
at least a portion of the plasma, and the depositing the final
glass layer are all performed in a chemical vapor deposition
chamber equipped with a plasma generator.
Description
BACKGROUND OF THE INVENTION
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
09/548,491, filed Apr. 13, 2000, pending, which is a continuation
of application Ser. No. 09/222,565, filed Dec. 29, 1998, now U.S.
Pat. No. 6,107,214, issued Aug. 22, 2000, which is a continuation
of application Ser. No. 08/841,908, filed Apr. 17, 1997,
pending.
[0002] 1. Field of the Invention
[0003] This invention relates to processes for depositing compounds
by means of chemical vapor deposition and, more particularly, to
processes for depositing silicon dioxide layers using ozone and
tetraethylorthosilane as precursor compounds.
[0004] 2. State of the Art
[0005] Doped and undoped silicon dioxides, which are commonly
referred to as silicate glasses, are widely used as dielectrics in
integrated circuits. Although silicon dioxide possesses a
tetrahedral matrix which will impart a crystalline structure to the
material under proper heating and cooling conditions, the silicon
dioxides used as dielectrics in integrated circuits are typically
amorphous materials. This application uses the term "silicate
glass" to refer to silicon dioxides deposited via chemical vapor
deposition (CVD), as the term encompasses materials containing not
just silicon dioxide, but dopants and other impurities as well.
[0006] Chemical vapor deposition of silicate glasses has become of
paramount importance in the manufacture of contemporary integrated
circuits. For example, silicate glass doped with both boron and
phosphorous is widely used as an interlevel dielectric and as a
getter material for mobile sodium ions.
[0007] Chemical vapor deposition (CVD) of silicate glasses by the
semiconductor industry is most commonly accomplished by reacting
tetraethylorthosilane (TEOS), silane or disilane with an oxidizer.
Silane is typically reacted with diatomic oxygen (O.sub.2) or
nitrous oxide (N.sub.2O) at a temperature of about 400.degree. C.
TEOS, on the other hand, is generally reacted with either O.sub.2
or ozone (O.sub.3). If a low reaction temperature is desirable, the
use of ozone permits a reduction in the reaction temperature to
about half that required for O.sub.2. For the sake of brevity,
glass layers deposited from the reaction of O.sub.3 and TEOS shall
be termed "ozone TEOS glasses". The reaction temperature may also
be reduced for the TEOS-O.sub.2 reaction by striking a plasma in
the deposition chamber. Glasses deposited via this plasma-enhanced
chemical vapor deposition (PECVD) method shall be referred to
hereinafter as PECVD-TEOS silicate glasses. The plasma generates
highly reactive oxygen radicals which can react with the TEOS
molecules and provide rapid deposition rates at much reduced
temperatures.
[0008] Silane is used for the deposition of silicate glasses when
substrate topography is minimal, as the deposited layers are
characterized by poor conformality and poor step coverage. Silicate
glasses deposited from the reaction of TEOS with O.sub.2 or O.sub.3
are being used with increasing frequency as interlevel dielectrics
because the deposited layers demonstrate remarkable conformality
that permits the filling of gaps as narrow as 0.25 .mu.m.
Unfortunately, the deposition rate of silicate glass formed by the
reaction of TEOS and O.sub.3 is highly surface dependent. A
particularly acute problem arises when the deposition is performed
on a surface having topographical features with non-uniform surface
characteristics. For example, the deposition rate is very slow on
PECVD-TEOS glass layers, considerably faster on silicon and on
aluminum alloys, and faster still on titanium nitride, which is
frequently used as an anti-reflective coating for laser reflow of
aluminum alloy layers. A correlation seems to exist between the
quality and relative deposition rate of ozone-TEOS glass layers.
For example, ozone TEOS glass layers that are deposited on
PECVD-TEOS glass layers have rough, porous surfaces and possess
high etch rates.
[0009] In U.S. Pat. No. 5,271,972 to K. Kwok et al., it is
suggested that the surface sensitivity of ozone-TEOS glass layers
deposited on PECVD-TEOS glass layers may be related to the presence
of a hydrophilic surface on the PECVD-TEOS glass layers. A
hydrophilic surface on the PECVD-TEOS glass layer may be
attributable to embedded elemental carbon particles which are
formed as the TEOS precursor gas is attached by oxygen radicals
generated by the plasma. As elemental carbon particles are
characteristically hydrophilic, they repel TEOS molecules, which
are characteristically hydrophobic, and interfere with their
absorption on the surface of the deposited layer. Thus, the poor
absorption rate of TEOS molecules on the surface of PECVD-TEOS
glass results in slowly deposited, poor-quality films. Experimental
evidence indicates that deposition rates are low for hydrophilic
surfaces and high for hydrophobic surfaces. For example, titanium
nitride, being highly hydrophobic, readily absorbs TEOS molecules
on its surface, which accelerates the deposition reaction.
[0010] Given the surface-dependent variation in deposition rates,
it is not uncommon for ozone-TEOS glass layers to build up rapidly
around aluminum conductor lines and much more slowly on PECVD glass
layers on which the conductor lines are fabricated, thereby forming
cavities of tear-drop cross section between adjacent conductor
lines. FIG. 1 is a cross-sectional view which depicts the
undesirable result obtained by conventionally depositing an
ozone-TEOS layer 11 over aluminum conductor lines 12 which overlie
an underlying PECVD-TEOS glass layer 113. Prior to patterning, the
aluminum conductor lines 12 were covered with a titanium nitride
layer which served as an anti-reflective coating during a laser
reflow operation. A titanium nitride layer remnant 14 is present on
the upper surface of each aluminum conductor line 12. A cavity 15
having a teardrop-shaped cross section has formed between each pair
of aluminum conductor lines 12. Cavities in an interlevel
dielectric layer are problematic primarily because they can trap
moisture when the deposited glass layer is subjected to a
planarizing chemical mechanical polishing step during a subsequent
fabrication step. The moisture, if not completely removed prior to
the deposition of subsequent layers, can corrode metal conductor
lines during normal use and operation of the part, or it may cause
an encapsulated integrated circuit device to rupture if the steam
generated as the device heats up is unable to escape the
package.
[0011] In U.S. Pat. No. 5,271,972, a technique is disclosed for
improving the film quality of ozone-TEOS glass layers deposited on
PECVD-TEOS glass layers. The method involves depositing the
underlying PECVD-TEOS layer using high pressure and a high
ozone-to-TEOS flow rate. For the last several seconds of the
plasma-enhanced deposition process, a stepwise reduction in reactor
power is carried out. It is claimed that this technique produces an
interstitial silicon dioxide layer at the surface of the PECVD-TEOS
layer which greatly reduces the surface sensitivity of subsequently
deposited ozone-TEOS oxide layers.
SUMMARY OF THE INVENTION
[0012] This invention provides an alternative method for depositing
highly conformal silicate glass layers via chemical vapor
deposition through the reaction of TEOS and O.sub.3 and for
minimizing surface effects of different materials on the deposition
process.
[0013] The entire method, which can be performed in a single
cluster tool or even in a single chamber, begins by placing an
in-process integrated circuit having multiple surface constituents
in a plasma-enhanced chemical vapor deposition chamber. A "clean"
silicate glass base layer that is substantially free of carbon
particle impurities on an upper surface thereof is then formed on
the wafer surface in one of two ways.
[0014] The first way of forming the clean base layer employs
plasma-enhanced chemical vapor deposition using TEOS and diatomic
oxygen gases as precursors to first deposit a "dirty" silicate
glass base layer having carbon particle impurities imbedded on the
upper surface. Glass layers deposited via PECVD by the reaction of
TEOS and O.sub.2 tend to have elemental carbon particles embedded
therein. As these particles may impart hydrophilic surface
characteristics to the deposited glass layer which may interfere
with the subsequent deposition of dense, high-quality ozone-TEOS
glass layers, the base glass layer is subjected to a plasma
treatment which involves flowing a mixture of an oxygen-containing
diamagnetic oxidant, such as ozone or hydrogen peroxide or a
combination of both, and diatomic oxygen gas into the chamber and
striking an RF plasma at a power of 50-350 watts for a period of
from 30-300 seconds. It is hypothesized that the plasma treatment
burns off the carbon particle impurities that are present on the
surface of the dirty silicate glass base layer, thereby reducing
the hydrophilic surface characteristics. The plasma treatment also
creates a high degree of surface uniformity on the PECVD-deposited
O.sub.2-TEOS glass layer.
[0015] The second way of forming the base layer involves flowing
hydrogen peroxide vapor and at least one gaseous compound selected
from the group consisting of silane and disilane into the
deposition chamber. As an optional step, the clean base layer
formed via this second method may be subjected to a plasma
treatment identical to that performed on the dirty PECVD-deposited
O.sub.2-TEOS glass layer. This optional plasma treatment step is
performed merely to improve surface uniformity, not reduce
hydrophilic surface characteristics.
[0016] Following the formation of the clean base layer, a final
glass layer is deposited over the PECVD-deposited glass layer using
chemical vapor deposition and TEOS and ozone as precursor
compounds.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] FIG. 1 is a cross-sectional view of a portion of an
in-process integrated circuit which has been subjected to a
conventional blanket deposition of ozone-TEOS silicate glass;
[0018] FIG. 2 is a cross-sectional view of a portion of an
in-process integrated circuit identical to that of FIG. 1 following
deposition of a base glass layer;
[0019] FIG. 3 is a cross-sectional view of the in-process circuit
portion of FIG. 2 following plasma treatment;
[0020] FIG. 4 is a cross-sectional view of the in-process circuit
portion of FIG. 3 following the deposition of a final ozone-TEOS
glass layer; and
[0021] FIG. 5 is a flow chart summarizing the various steps of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] This invention is embodied in a process for depositing
highly conformal silicate glass layers via chemical vapor
deposition through the reaction of tetraethylorthosilane (TEOS) and
O.sub.3. The entire process, which can be performed in a single
cluster tool or even in a single chamber, begins by placing an
in-process semiconductor wafer in a plasma-enhanced chemical vapor
deposition chamber. In a typical case, hundreds of integrated
circuits are undergoing simultaneous fabrication on the wafer, and
each integrated circuit has topography with multiple surface
constituents. FIG. 2 is a cross-sectional view which depicts a
small portion of an integrated circuit identical to that of FIG. 1.
A plurality of parallel aluminum conductor lines 12 overlies a
silicon dioxide layer 13. Each aluminum conductor line 12 is
covered with a titanium nitride layer 14 which served as an
anti-reflective coating during a laser reflow operation which
preceded masking and etching steps which formed the conductor
lines. Each of the different materials has different surface
characteristics which affect the rate of deposition for ozone-TEOS
glass layers.
[0023] In order to eliminate surface characteristics, a "clean"
silicate glass base layer is formed which completely covers all
existing topography. The base layer must be clean in the sense that
its upper surface is free of hydrophilic carbon particle impurities
which would interfere with the deposition of an ozone-TEOS final
glass layer. The clean base layer may be formed in one of two
ways.
[0024] Referring now to FIG. 2, the first way involves depositing a
"dirty" base silicate glass layer 21 on all constituent surfaces
via plasma-enhanced chemical vapor deposition (PECVD). The PECVD
deposition of the base silicate glass layer 21 is performed in a
deposition chamber in which a plasma is ignited formed from a
mixture of TEOS, oxygen and an inert carrier gas such as helium or
argon which transports TEOS molecules to the chamber.
[0025] Deposition of the PECVD base silicate glass layer 21 is
effected within a plasma deposition chamber at a pressure within a
range of about 1-50 tort (preferably within a range of about 1-10
tort), an oxygen flow rate of about 100-1000 sccm, a carrier gas
flow rate of about 100-1500 sccm, and with an RF power density of
about 0.7 watts/cm.sup.2 to about 3.0 watt/cm.sup.2. The deposition
temperature is maintained within a range of about 300 to
500.degree. C., with a preferred temperature of about 375.degree.
C. This process is described in greater detail in U.S. Pat. No.
4,872,947, which issued to Chang et al., and is assigned to Applied
Materials, Inc. This patent is incorporated herein by
reference.
[0026] A suitable CVD/PECVD reactor in which the present process
can be carried out in its entirety is also described in U.S. Pat.
No. 4,872,947. Silicate glass layers can be deposited using
standard high frequency RF power or a mixed frequency RF power.
[0027] The base silicate glass layer 21 is deposited to an average
thickness within a range of about 100 to 1000 .ANG.. The optimum
thickness is deemed to be approximately 500 .ANG.. Although the
deposition rate of plasma-enhanced chemical-vapor-deposited oxide
from TEOS and O.sub.2 is more even on different surfaces than it is
for ozone-TEOS oxide, it is essential that all surfaces are
completely covered.
[0028] An untreated TEOS silicate glass layer deposited via a
plasma-enhanced CVD process tends to have embedded elemental carbon
particles which are formed as the TEOS precursor gas is attacked by
oxygen radicals generated by the plasma. These carbon particles
apparently impart hydrophilic surface characteristics to an
untreated base silicate glass layer 21 which are most likely
responsible for the uneven deposition rates observed during
subsequent depositions of dense, high-quality PECVD ozone-TEOS
glass layers. In order to reduce or eliminate such interfering
surface characteristics, the dirty base silicate glass layer 21 is
subjected to a plasma treatment which involves flowing a mixture of
an oxygen-containing diamagnetic oxidant gas, such as ozone
(O.sub.3) or hydrogen peroxide (H.sub.2O.sub.2) or a combination of
both, and diatomic oxygen (O.sub.2) gas into the chamber and
striking an RF plasma. A mixture of 4 to 15 percent O.sub.3 or
H.sub.2O.sub.2 in O.sub.2 is admitted to the chamber at a flow rate
of about 2,400 standard cc/min. The plasma is sustained at a power
density setting of 0.25 watt/cm.sup.2 to about 3.0 watt/cm.sup.2
for a period of from 30-360 seconds. In order to prevent etching of
the deposited base silicate glass layer 21 and uncovering of
additional impurity sites, a remote-source plasma generator is
preferred over a parallel-plate reactor. The plasma treatment is
represented by FIG. 3, which depicts a plasma cloud 31 which
completely engulfs the in-process integrated circuit portion of
FIG. 2, thereby exposing all surfaces of the base silicate glass
layer 21 to the oxygen plasma. It is hypothesized that the plasma
treatment burns off impurities, such as the carbon particles, which
are present in the PECVD-deposited base silicate glass layer 21,
thereby reducing or eliminating the hydrophilic surface
characteristics. The plasma treatment creates a high degree of
surface uniformity on the PECVD-deposited base silicate glass layer
21.
[0029] Referring once again to FIG. 2, which may also be used to
represent the second method of forming a clean base silicate glass
layer 21 involves a non-plasma-enhanced chemical vapor deposition
effected by flowing hydrogen peroxide vapor and at least one
gaseous compound selected from the group consisting of silane and
disilane into the deposition chamber. A clean silicate glass base
layer having no imbedded carbon particle impurities is deposited.
The reaction of hydrogen peroxide vapor with either silane or
disilane is performed within a temperature range of about 0.degree.
C. to 40.degree. C., at a chamber pressure of less than about 10
torr, and at a flow rate maintained for silane or disilane within a
range of about 10 sccm to 1,000 sccm. The hydrogen peroxide is
introduced into the deposition chamber in combination with at least
one carrier gas selected from the group consisting of nitrogen and
the noble gases. The hydrogen peroxide is picked up by the carrier
gas in a bubbler apparatus, and the flow rate of the carrier gas
(with the hydrogen peroxide) into the deposition chamber is
maintained within a range of about 50 sccm to 1,000 sccm. In
addition, the hydrogen peroxide may be introduced into the
deposition chamber via liquid injection using a liquid-flow
controller in combination with a vaporizer.
[0030] As an optional step, the clean base layer formed via this
second method may be subjected to a plasma treatment identical to
that performed on the dirty PECVD-deposited O.sub.2-TEOS glass
layer. This optional plasma treatment step is performed merely to
improve surface uniformity, not reduce hydrophilic surface
characteristics.
[0031] Referring now to FIG. 4, an ozone-TEOS silicate glass layer
41 is deposited on top of the clean silicate glass base layer 42.
As the processes required for the formation of the silicate glass
base layer, the plasma treatment step, and the ozone-TEOS
deposition step share certain parameters in common, the same
chamber can be used for all process steps. For the plasma treatment
step, the TEOS flow and the concomitant carrier gas flow are
terminated, plasma generation continues, and ozone is added to the
still flowing O.sub.2 gas. For the ozone-TEOS deposition step, the
TEOS flow is resumed and the O.sub.2 and O.sub.3 ratios are
adjusted as necessary. The ozone-TEOS deposition step is
accomplished by flowing TEOS, oxygen and ozone gases into the
deposition chamber, which is maintained at a pressure greater than
10 torr, and, preferably, within a range of about 500 to 760 torr.
Substrate temperatures are maintained within a range of about
300-600.degree. C., and preferably at a temperature of about
400.degree. C. A dense, highly conformal ozone-TEOS silicate glass
layer 41 is deposited that rapidly fills in the remaining gaps
between the conductor lines 12. The ozone-TEOS silicate glass layer
41 demonstrates a high degree of conformality upon deposition.
Cavities present in ozone-TEOS silicate glass layers deposited
using conventional deposition methods are eliminated.
[0032] The present process is highly advantageous because
deposition of the PECVD base silicate glass layer 21, plasma
treatment of the base silicate glass layer 21, and deposition of
the ozone-TEOS silicate glass layer 41 can be performed in
sequence, in the same reaction chamber, requiring a minimum of
changes in the reactor, and without having to remove the substrate
from the reaction chamber between the various steps. Likewise, if
the base silicate glass layer is deposited using hydrogen peroxide
and silane or disilane as precursors, all steps may be performed
within the same reaction chamber without having to remove the
substrate from the chamber between the various steps.
[0033] FIG. 5 summarizes the various options of the process which
is the subject of this disclosure. The first major step, providing
a "clean" silicate glass base layer 51, can be performed in two
basic ways: the dirty deposition and cleaning route 52 using TEOS
and O.sub.2 as precursor gases for a PECVD deposition step 53
followed by a cleaning plasma treatment step 54 involving O.sub.2
and H.sub.2O.sub.2 and/or O.sub.3, or the CVD route 55 using silane
or disilane and H.sub.2O.sub.2 as precursor gases in a CVD
deposition step 56 and, optionally, the plasma surface treatment of
step 54. The final step 57 is CVD deposition of a final glass layer
using TEOS and O.sub.3 as precursor gases.
[0034] Various changes to the gas mixtures, temperature and
pressure of the reactions are contemplated and are meant to be
included herein. Although the ozone-TEOS glass deposition process
is described in terms of only a single embodiment, it will be
obvious to those having ordinary skill in the art of semiconductor
integrated circuit fabrication that changes and modifications may
be made thereto without departing from the scope and the spirit of
the invention as hereinafter claimed.
* * * * *