U.S. patent application number 10/453227 was filed with the patent office on 2003-12-04 for method and apparatus for processing semiconductor substrates with hydroxyl radicals.
This patent application is currently assigned to Applied Materials Inc.. Invention is credited to Campana, Francimar, Chandran, Shankar, Chen, Chen-an, Nemani, Srinivas D., Pokharna, Himanshu, Xia, Li-Qun, Yieh, Ellie.
Application Number | 20030221621 10/453227 |
Document ID | / |
Family ID | 24223973 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030221621 |
Kind Code |
A1 |
Pokharna, Himanshu ; et
al. |
December 4, 2003 |
Method and apparatus for processing semiconductor substrates with
hydroxyl radicals
Abstract
A method and apparatus for processing semiconductor substrates
by reacting hydroxyl radicals with a precursor to cause the
precursor to decompose and form a film which deposits on a
substrate. Hydroxyl radicals, which are produced in a hydroxyl-ion
producing apparatus outside of a chemical vapor deposition reactor,
are mixed with a precursor to form a hydroxyl ions-precursor
mixture. The hydroxyl ions-precursor mixture is introduced into the
chemical vapor deposition reactor.
Inventors: |
Pokharna, Himanshu; (Santa
Clara, CA) ; Chandran, Shankar; (Milpitas, CA)
; Nemani, Srinivas D.; (San Jose, CA) ; Chen,
Chen-an; (Milpitas, CA) ; Campana, Francimar;
(Milpitas, CA) ; Yieh, Ellie; (Milbrae, CA)
; Xia, Li-Qun; (Santa Clara, CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Applied Materials Inc.
Santa Clara
CA
|
Family ID: |
24223973 |
Appl. No.: |
10/453227 |
Filed: |
June 2, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10453227 |
Jun 2, 2003 |
|
|
|
09557079 |
Apr 21, 2000 |
|
|
|
6596343 |
|
|
|
|
Current U.S.
Class: |
118/722 ;
118/50.1; 118/715 |
Current CPC
Class: |
C30B 25/02 20130101;
C23C 16/452 20130101; C30B 29/06 20130101; C23C 16/40 20130101 |
Class at
Publication: |
118/722 ;
118/715; 118/50.1 |
International
Class: |
C23C 016/00; C23C
014/00 |
Claims
What is claimed is:
1. A method for depositing a layer on a substrate in a chemical
vapor deposition reaction zone comprising: introducing a precursor
into a chemical vapor deposition reaction zone containing a
substrate; and introducing hydroxyl radicals into the chemical
vapor deposition reaction zone for reacting with the precursor to
form a deposition layer on the substrate.
2. The method of claim 1 wherein said precursor comprises
silane.
3. The method of claim 1 wherein said precursor comprises
silicon.
4. The method of claim 1 wherein said precursor comprises an
organometallic compound.
5. The method of claim 1 wherein said precursor comprises a
silicon-containing gas.
6. The method of claim 1 wherein said introducing hydroxyl radicals
into the chemical vapor deposition reaction zone comprises
introducing hydroxyl radicals as a gas phase into said chemical
vapor deposition zone.
7. The method of claim 6 wherein said gas phase comprises a
temperature ranging from about 100.degree. C. to about 150.degree.
C.
8. The method of claim 1 additionally comprising admixing, prior to
said introducing the precursor, an inert gas with the precursor for
delivering the precursor into the chemical vapor deposition
reaction zone.
9. The method of claim 8 wherein said inert gas is selected from
the group consisting of nitrogen, helium, argon, neon, krypton,
xenon and radon, and mixtures thereof.
10. The method of claim 6 wherein said gas phase comprises at least
about 10% by volume of said hydroxyl radicals.
11. The method of claim 6 wherein said gas phase consists
essentially of at least about 10% by volume of said hydroxyl
radicals.
12. The method of claim 6 where said gas phase consists of at least
about 10% by volume of said hydroxyl radicals.
13. The method of claim 1 additionally comprising producing said
hydroxyl radicals prior to said introducing hydroxyl radicals into
the chemical vapor deposition reaction zone.
14. The method of claim 1 wherein said introducing hydroxyl
radicals additional comprises introducing hydroxyl radicals at a
pressure ranging from about 100 Torrance to about 200 Torrance.
15. The method of claim 1 wherein said reacting with said precursor
comprises decomposing said precursor to form said deposition
layer.
16. A method for forming a deposition layer in a chemical vapor
deposition reactor comprising the step of: a) producing hydroxyl
radicals; b) admixing the produced hydroxyl radicals with a
precursor to produce a hydroxyl radicals-precursor mixture; and c)
introducing the hydroxyl radicals-precursor mixture of step (b)
into the chemical vapor deposition reactor to form a deposition
layer.
17. The method claim 16 wherein said producing hydroxyl radicals of
step (a) comprises introducing a water-containing agent and ozone
into a hydroxyl radical-producing reactor; and directing
ultraviolet radiation into said hydroxyl radical-producing reactor
to cause oxygen atoms to form from the ozone and react with the
water-containing agent to produce hydroxyl radicals.
18. The method of claim 17 wherein said water-containing agent
comprises water.
19. The method of claim 16 additional comprising removing, prior to
said admixing of step (b), hydroxyl radicals from the hydroxyl
radical-producing reactor.
20. The method of claim 16 wherein said admixing of hydroxyl
radicals with said precursor causes said hydroxyl radicals to react
with said precursor.
21. The method of claim 16 wherein said hydroxyl radicals and said
precursor are reacting as said hydroxyl radicals-precursor mixture
is being introduced into said chemical vapor deposition
reactor.
22. A chemical vapor deposition reactor for forming deposition
films comprising: a chemical vapor deposition reactor chamber; a
source of hydroxyl ion gas coupled to said chemical vapor
deposition reactor chamber and including hydroxyl ion gas flowing
into said chemical vapor deposition reactor chamber; a pedestal
disposed in said reactor chamber for supporting substrates in said
reactor chamber; a processing power source; a processing
gas-introducing assembly engaged to said reactor chamber for
introducing a processing gas into said reactor chamber; and a
processing power-transmitting member disposed in proximity to said
reactor chamber and connected to said processing power source for
transmitting power into the reactor interior for forming deposition
films.
23. The chemical vapor depositions reactor of claim 20 wherein said
source of hydroxyl ion gas comprises a hydroxyl-ion producing
reactor having at least one inlet port; a source of water coupled
to said at lease one inlet port; a source of ozone gas coupled to
said at least one inlet port; and a source of ultraviolet radiation
oriented to direct ultraviolet radiation into the hydroxyl-ion
producing reactor.
24. A chamber assembly for decomposing a precursor with hydroxyl
radicals comprising: a processing chamber having a support for a
substrate and at least one port for receiving at least one gas; a
source of precursor gas coupled to the at least one port for
flowing precursor gas into the processing chamber; and a source of
hydroxyl radical gas coupled to the at least one port for flowing
hydroxyl radical gas into the processing chamber to cause said
precursor gas to decompose.
25. A reactor for processing substrates comprising a reactor
chamber; a hydroxyl-ion producing assembly coupled to said reactor
chamber for producing hydroxyl ions and introducing the hydroxyl
ions into the reactor chamber; a pedestal disposed in said reactor
chamber for supporting substrates in said reactor chamber; a
processing power source; a processing gas-introducing assembly
engaged to said reactor chamber for introducing a processing gas
into said reactor chamber; and a processing power-transmitting
member disposed in proximity to said reactor chamber and connected
to said processing power source for transmitting power into the
reactor interior.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] The present invention relates generally to improved methods
and apparatuses for depositing films on partially fabricated
integrated circuits (ICs). More specifically, the present invention
relates to improved methods and apparatuses for accelerating the
deposition of certain materials from precursors, such as
organometallic compounds.
[0003] 2. Description of the Prior Art
[0004] In integrated circuit fabrication, various materials are
deposited on a substrate at various stages in the fabrication
process. By way of example, metallization layers may be produced by
processing (e.g., etching, chemical or physical vapor deposition,
etc.) layers (e.g., metal layers) on a silicon wafer or substrate.
By further way of example, dielectric layers may be formed between
metallization layers to enable the formation of multi-level
connections to devices, to produce field oxide regions used to
isolate semiconductor active devices, to produce passivation layers
used to protect entire IC chips during packaging, and to form masks
used in subsequent etching processes.
[0005] There are many well-known techniques used for depositing
materials. such as silicon dioxide (SiO.sub.2). Such techniques
often include the use of a precursor (e.g., organometallic
compounds) reactants, such as tetraethylorthosilicate "TEOS"
Si(OC.sub.2H.sub.5).sub.4. Such materials are introduced into a
chemical vapor deposition (CVD) reactor chamber to break down and
decompose to form films and by-products, such as SiO.sub.2 films
and Si and organic by-products. TEOS is in a liquid state at room
temperatures and must be heated in an external vaporizing
apparatus, or otherwise converted to the gas phase, before being
introduced into a CVD reactor chamber.
[0006] Although forming films from such precursors as TEOS is
popular because generally good step coverage is provided and the
required deposition temperatures are relatively low, precursors
including TEOS are very expensive. Therefore, there is a need to
utilize a high percentage of precursors in producing films (as
opposed to being pumped out of the CVD reaction chamber as unused
reactant).
[0007] At least three chemical vapor deposition processes are now
commonly used in industry. These include plasma enhanced chemical
vapor deposition (PECVD), low pressure chemical vapor deposition
(LPCVD), and atmospheric pressure chemical vapor deposition
(APCVD). To formulate a SiO.sub.2 layer in any of these three
chemical vapor deposition processes, oxygen and ozone are typically
employed, especially if TEOS is the precursor. While the
introduction of oxygen and ozone promotes TEOS decomposition, it
has been found that TEOS decomposition reaction is still slow and a
relatively high fraction of the TEOS introduced into a CVD chamber
does not completely and fully react with the oxygen and ozone and
is therefore wasted. Also, because TEOS decomposes at a slow rate,
it has been found that the slow rate of decomposition causes
certain structural defects (e.g., voids) resulting from the
deposition of TEOS SiO.sub.2 films over gaps between vertical
structures.
[0008] U.S. Pat. No. 5,710,079 to Sukharev attempts to solve these
problems by providing a method and apparatus for facilitating the
decomposition of organometallic compounds in chemical vapor
deposition reactors in order to deposit films. In one embodiment
for the method in U.S. Pat. No. 5,710,079, the method generally
includes: (1) introducing an organometallic compound (e.g., TEOS)
and ozone molecules to a chemical vapor deposition reactor; (2)
directing ultraviolet radiation into the chemical vapor deposition
reactor to increase the rate at which oxygen atoms are formed from
the ozone molecules present in the chemical vapor deposition
reactor; and (3) decomposing the organometallic compound to form a
deposition layer (e.g., a silicon dioxide layer). The
organometallic compound is taught as decomposing at an accelerated
rate due in part to an increased concentration of hydroxyl radicals
present in the chemical vapor deposition reactor. The hydroxyl
radicals are produced from a reaction of oxygen atoms with
moisture. The water vapor and/or hydrogen peroxide is introduced to
the chemical vapor deposition reactor to ensure that a high
concentration of hydroxyl radicals are present.
[0009] In one embodiment for the apparatus in U.S. Pat. No.
5,710,079, an apparatus for depositing a dielectric layer on a
substrate is disclosed. The apparatus is preferably suited for
decomposing organometallic compounds such as TEOS with the aid of
hydroxyl radicals. The apparatus generally includes: (1) a chemical
vapor deposition reactor having a support for a substrate, and at
least one inlet port for receiving gases; (2) a source of ozone gas
coupled to the at least one inlet port; (3) a source of the
organometallic compound coupled to the at least one inlet port; and
(4) a source of ultraviolet radiation oriented to direct
ultraviolet radiation into the chemical vapor deposition
reactor.
[0010] The deficiencies with the method and apparatus disclosed in
U.S. Pat. No. 5,710,079 is that the CVD reactor chamber must be
adapted to produce hydroxyl radicals in situ before the hydroxyl
radicals commence to react with and decompose the organometallic
compounds. This delays the formation of SiO.sub.2 films and causes
inefficiencies. Also, the CVD reactor chamber must be built with a
radiation transmission window such that ultraviolet light may be
transmitted into the CVD reactor chamber in order to decompose
ozone molecules to produce atomic oxygen which reacts with water to
produce the hydroxyl radicals.
[0011] Therefore, what is needed and what has been invented is an
improved method and apparatus for processing semiconductor
substrates without the foregoing deficiencies and which includes
depositing films on partially fabricated integrated circuits. What
is further needed and what has been invented is an improved method
and apparatus for forming a deposition layer, such as a SiO.sub.2
film, in a chemical vapor deposition reactor.
SUMMARY OF THE INVENTION
[0012] The present invention broadly provides a method for
depositing a layer on a substrate in a chemical vapor deposition
reaction zone comprising introducing a precursor into a chemical
vapor deposition reaction zone containing a substrate, and
introducing hydroxyl radicals into the chemical vapor deposition
reaction zone for reacting with the precursor to form a deposition
layer on the substrate. The precursor may be selected from the
group consisting of silane, silicon, an organometallic compound,
and a silicon-containing gas. The introduction of hydroxyl radicals
into the chemical vapor deposition reaction zone comprises
introducing hydroxyl radicals as a gas phase into the chemical
vapor deposition zone. The gas phase preferably comprises at least
about 10% by volume of the hydroxyl radicals, and the temperature
of the gas phase preferably ranges from about 100.degree. C. to
about 150.degree. C. An inert gas is typically employed as a
carrier for the precursor. The inert gas may be any suitable inert
gas, but is preferably selected from the group consisting of
nitrogen, helium, argon, neon, krypton, xenon and radon, and
mixtures thereof. The method for depositing a layer additionally
comprises producing the hydroxyl radicals prior to the introducing
hydroxyl radicals into the chemical vapor deposition reaction zone.
Preferably hydroxyl radicals are introduced at a pressure ranging
from about 100 Torrance to about 200 Torrance. Reacting the
precursor with the hydroxyl radicals preferably decomposes the
precursor to form the deposition layer.
[0013] The present invention further broadly provides a method for
forming a deposition layer in a chemical vapor deposition reactor
comprising the steps of (a) producing hydroxyl radicals; (b)
admixing the produced hydroxyl radicals with a precursor to produce
a hydroxyl radicals-precursor mixture; and (c) introducing the
hydroxyl radicals-precursor mixture of step (b) into the chemical
vapor deposition reactor to form a deposition layer. The producing
of hydroxyl radicals in step (a) preferably comprises introducing a
water-containing agent (e.g., water) and ozone into a hydroxyl
radical-producing reactor; and directing ultraviolet radiation into
the hydroxyl radical-producing reactor to cause oxygen atoms to
form from the ozone and react with the water-containing agent to
produce hydroxyl radicals. The method additional comprises
removing, prior to the admixing of step (b), hydroxyl radicals from
the hydroxyl radical-producing reactor. The admixing of hydroxyl
radicals with the precursor causes the hydroxyl radicals to react
with the precursor. Preferably, the hydroxyl radicals and the
precursor are reacting as the hydroxyl radicals-precursor mixture
is being introduced into the chemical vapor deposition reactor.
[0014] The present invention also broadly provides a chemical vapor
deposition reactor for forming deposition films comprising a
chemical vapor deposition reactor chamber; a source of hydroxyl ion
gas coupled to the chemical vapor deposition reactor chamber and
including hydroxyl ion gas flowing or introducing into the chemical
vapor deposition reactor chamber; and a pedestal disposed in the
reactor chamber for supporting substrates in the reactor chamber.
The chemical vapor deposition reactor also comprises a processing
power source; a processing gas-introducing assembly engaged to the
reactor chamber for introducing a processing gas into said reactor
chamber; and a processing power-transmitting member disposed in
proximity to the reactor chamber and connected to the processing
power source for transmitting power into the reactor interior for
forming deposition films. The source of hydroxyl ion gas comprises
a hydroxyl-ion producing reactor having at least one inlet port; a
source of water coupled to the at least one inlet port; a source of
ozone gas also coupled to the at least one inlet port; and a source
of ultraviolet radiation oriented to direct ultraviolet radiation
into the hydroxyl-ion producing reactor.
[0015] The present invention further also broadly provides a
chamber assembly for decomposing a precursor with hydroxyl radicals
comprising a process chamber having a support for a substrate and
at least one port for receiving at least one gas; a source of
precursor gas coupled to the at least one port for flowing
precursor gas into the processing chamber; a source of hydroxyl
radical gas coupled to the at least one port for flowing or
introducing hydroxyl radical gas into the processing chamber to
cause the precursor gas to decompose. Further provided in
accordance with the present invention is a reactor for processing
substrates comprising a reactor chamber; a hydroxyl-ion producing
assembly coupled to the reactor chamber for producing hydroxyl ions
and introducing the hydroxyl ions into the reactor chamber; and a
pedestal disposed in the reactor chamber for supporting substrates
in the reactor chamber. The reactor also comprises a processing
power source; a processing gas-introducing assembly engaged to the
reactor chamber for introducing a processing gas into the reactor
chamber; and a processing power-transmitting member disposed in
proximity to the reactor chamber and connected to the processing
power source for transmitting power into the reactor interior.
[0016] These provisions, together with the various ancillary
provisions and features which will become apparent to those skilled
in the art as the following description proceeds, are attained by
these novel apparatuses and methods, a preferred embodiment thereof
shown with reference to the accompanying drawings, by way of
example only, wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a diagrammatic illustration of one embodiment of
the invention wherein an hydroxyl ions producing apparatus is in
communication with a chemical vapor deposition reaction chamber
such that produced hydroxyl radicals may be mixed with a precursor
prior to being introduced into the chemical vapor deposition
reaction chamber; and
[0018] FIG. 2 is a diagrammatic illustration of another embodiment
of the invention wherein an hydroxyl ions producing apparatus is in
communication with a chemical vapor deposition reaction chamber
such that produced hydroxyl ions may be directly introduced into
the chemical vapor deposition reaction chamber without being
premixed with the precursor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] Embodiments of the present invention provide for methods and
apparatuses for depositing one or more layers of one or more
materials on the surface(s) of semiconductor substrates or devices.
The deposited layers are formed from decomposing in a reactor a
suitable precursor, such as an organometallic compound or an
organometalloid. The reactor may be any suitable reactor, but is
preferably a chemical vapor deposition (CVD) reactor. The one or
more materials that are deposited on the semiconductor substrate
may be any material or matter that can be produced under
appropriate conditions by decomposing, or otherwise breaking down,
a precursor with the assistance of hydroxyl radicals or ions, which
react with the precursor to cause the decomposition of same. The
one or more materials include, but are not limited to,
semiconductors, dielectrics, and metals employed in manufacturing
integrated circuits and other semiconductor devices.
[0020] For purposes of illustrating various preferred embodiments
of the present invention, the precursor will be TEOS,
tetraethylorthosilicate Si(OC.sub.2H.sub.5).sub.4, as a suitable
organometallic compound which, when coming in contact with hydroxyl
radicals, decomposes or breaks down into SiO.sub.2, the material
which deposits and/or forms as a deposited material or layer on a
semiconductor substrate. TEOS is employed in the gaseous state;
thus, a suitable heater (not shown) heats the TEOS at a suitable
temperature, such as a temperature ranging from about 20.degree. C.
to about 100.degree. C., to change liquid TEOS into vapor or
gaseous TEOS. While TEOS will be used as the precursor to
illustrate preferred embodiments of the present invention, it is to
be understood that the spirit and scope of the present invention
include other precursors such as, by way of illustration only,
trimethylsilane (TMS), BPTEOS, TEB, TMOP, OMCTS, HMDS, TMCTS,
TRIES, etc. These precursors, as well as others which are all
within the spirit and scope of the present invention, may be
employed to deposit and/or form on a semiconductor substrate films
or layers of such materials as titanium (Ti), tantalum (Ta),
tungsten (W), silicides, and so forth. Obviously, the type and
chemical composition of the material deposited and/or formed on the
semiconductor substrate depends on the chemical composition of the
precursor. Thus, the material deposited is dictated by the
precursor selected. As was previously indicated, if SiO.sub.2 is to
be the deposited material, then TEOS would be an acceptable
precursor for being decomposed by reacting with hydroxyl
radicals.
[0021] It is to be also understood that while the processing of the
semiconductor substrate will be in a CVD reactor for purposes of
illustrating embodiments of the present invention, the spirit and
scope of the present invention would include other types of
reactors and other forms of processing substrates, such as by way
of example only, plasma processing, physical vapor deposition, etc.
Other types of reactors within the spirit and scope of the present
invention include inductively coupled plasma reactors, such as
those disclosed in U.S. Pat. No. 5,753,044, assigned to assignee of
the present invention and fully incorporated herein by reference
thereto as if repeated verbatim immediately hereafter. An
inductively coupled plasma has a plasma ion density greater than
about 10.sup.9/cm.sup.3, preferably greater than about
10.sup.11/cm.sup.3. During plasma processing, processing power
(e.g., RF power, magnetron power, microwave power, etc.) passes
through a dielectric member, which includes a dielectric window of
a nonconductive material such as a ceramic dome, etc., and becomes
coupled to a plasma of the processing gas. If the plasma process is
plasma depositing, metals (e.g., platinum, copper, aluminum,
titanium, ruthenium, iridium, etc.), as well as other materials
such as dielectrics, may be respectively deposited on a substrate.
Thus, the spirit and scope of the present invention would include
any type of processing of a semiconductor substrate and any type
reactor or reaction zone for processing a semiconductor substrate,
all readily discernible to those possessing the ordinary skill in
the art.
[0022] In accordance with an embodiment of the present invention,
the precursor and hydroxyl radicals or ions are introduced into a
CVD reactor, preferably in a gaseous state. The precursor and
hydroxyl radicals may be admixed before being introduced into the
CVD reactor; or alternatively, the precursor and the hydroxyl
radicals may be independently introduced into the CVD reactor and
then admixed within the CVD reactor itself. When the hydroxyl
radicals come in contact with the precursor (e.g., a processing
gas), the hydroxyl radicals react with and/or cause decomposition
of the precursor, resulting in the deposition rate of the
depositing material accelerating, especially since the
concentration of the hydroxyl radicals is instantly increased
within the CVD reactor because hydroxyl radicals are being
introduced into the CVD reactor in a pure, free state. Hydroxyl
radicals also cause acceleration of the decomposition or break down
of the precursor. It is believed that by initially producing the
hydroxyl radicals outside of a CVD reactor, instead of producing
the hydroxyl radicals within a CVD reactor as disclosed in U.S.
Pat. No. 5,710,079, and subsequently introducing the hydroxyl
radicals into the CVD reactor, the reaction and/or decomposition of
the precursor is faster than if the hydroxyl radicals had been
produced within the CVD reactor as disclosed in U.S. Pat. No.
5,710,079. It is also believed that the same would hold true with
respect to accelerating the deposition rate of depositing material.
Thus, the fact that hydroxyl radicals are already formed when
introduced into the CVD reactor enables the precursor within the
reactor chamber to immediately come in contact with and react with
the hydroxyl radicals as opposed to the precursor waiting in the
CVD reactor for the hydroxyl radicals to initially form (as
disclosed in U.S. Pat. No. 5,710,079) and then subsequently
commencing a reaction with the hydroxyl radicals for decomposing
the precursor to produce material that deposits on the
semiconductor substrate. In the embodiment where the hydroxyl
radicals and the precursor are mixed together before passing into
the CVD reactor, the reaction of the precursor with the hydroxyl
radicals immediately commences. Thus, reaction of the precursor
with the hydroxyl radicals, and decomposition of the precursor, are
all taking place as the precursor and the hydroxyl radicals are
passing into the CVD reactor. When the precursor is an
organometallic compound, the hydroxyl radicals also combine with
carbon atoms originating from the organometallic precursor, thus
reducing carbon contamination within the CVD reactor.
[0023] In a preferred embodiment of the invention, hydroxyl
radicals or ions are produced, obtained, or otherwise provided. The
hydroxyl radicals or ions may be produced, obtained, or otherwise
provided in any suitable manner, all of which would fall within the
spirit and scope of the present invention. Preferably, the hydroxyl
radicals are produced in a suitable hydroxyl-ion producing reactor
or assembly to provide a source of hydroxyl radicals. Water
(H.sub.2O) and/or steam and ozone (O.sub.3) are respectively
introduced into a suitable hydroxyl-ion producing reactor.
Subsequently, ultra-violet radiation is introduced into or provided
to the reactor to cause the ozone to decompose into oxygen and
atomic oxygen (O*) in .sup.1D state which reacts with the water
molecules to generate hydroxyl radicals (OH.sup.-) in a gas-phase.
Typically, unreacted water (or unreacted steam), oxygen and some
ozone are also in the reactor. Alternatively, or in addition to,
hydrogen peroxide (H.sub.2O.sub.2), preferably gaseous hydrogen
peroxide, may be introduced into the hydroxyl-ion producing reactor
where ultra-violet radiation photolyzes and/or decomposes the
hydrogen peroxide into an independent or an additional gas-phase
source of hydroxyl radicals. The hydroxyl-ion producing reactor
would be equipped with a suitable transmission window for receiving
and allowing passage of ultraviolet rays into the hydroxyl-ion
producing reactor from an external source, such as a mercury arc
lamp. After the hydroxyl-radicals have been produced, they, along
with unreacted water (or unreacted steam), oxygen and traces of
ozone, flow and are introduced into a reactor which is being
simultaneously supplied with gaseous TEOS, preferably with the aid
of a noble or inert gas such as nitrogen, argon, helium, neon,
krypton, xenon, radon, and mixtures thereof. The gaseous hydroxyl
radicals contact and react with the gaseous TEOS such that the TEOS
decomposes and breaks down to various components, one of which is
SiO.sub.2 that deposits on a semiconductor substrate. As previously
indicated and for one embodiment of the invention, gaseous hydroxyl
radicals and gaseous TEOS (i.e., a precursor) are mixed together
immediately before they enter the CVD reactor. This causes the
hydroxyl radicals to immediately start reacting with the TEOS
outside of the CVD reactor, enabling decomposition of TEOS into
SiO.sub.2 and other components as TEOS enters the CVD reactor.
Also, TEOS and hydroxyl radicals continue to react with each other
as they are entering the CVD reactor, causing SiO.sub.2 to
essentially immediately start depositing on the semiconductor
substrate. As further previously indicated and for another
embodiment of the invention, gaseous hydroxyl radicals and gaseous
TEOS come in contact with each other essentially immediately after
entering the CVD reactor, causing in the CVD reactor the
essentially immediate hydroxyl ion-TEOS reaction and concomitant
TEOS decomposition along with subsequent SiO.sub.2 deposition. The
formation and deposition of SiO.sub.2 may be conducted at any
suitable pressure and temperature, such as by way of example only,
at atmospheric pressure in a chemical vapor deposition (APCVD)
process, or at subatmospheric pressure in a chemical vapor
deposition (SACVD) process, all readily known to those possessing
ordinary skill in the art.
[0024] As previously indicated, the deposition rate of the silicon
dioxide film increases due to the accelerated rate at which TEOS is
decomposed by the hydroxyl radicals. As also previously indicated
above, the increased rate at which TEOS decomposes is generally
correlated to the increased amount of hydroxyl radicals (*OH) being
produced and coming into contact with the TEOS. When ozone
(O.sub.3) is exposed to ultraviolet radiation in a hydroxyl-ion
producing reactor, the rate at which ozone decomposes to form
oxygen (O.sub.2) molecules and atomic oxygen (i.e., oxygen radicals
"O*") is increased. Because atomic oxygen rapidly reacts with
gaseous water present in the hydroxyl-ion producing reactor to
produce hydroxyl radicals, an increased concentration of hydroxyl
radicals can be produced in the hydroxyl-ion producing reactor. For
one embodiment of the invention when free hydroxyl radicals are
introduced into the CVD reactor for immediate contact with TEOS,
the rate at which TEOS decomposes is beneficially increased, and
the rate at which silicon dioxide films are formed is also
beneficially increased. For another embodiment of the invention
when free hydroxyl radicals are mixed with TEOS immediately before
entering the CVD reactor, the rate at which TEOS decomposes and the
rate SiO.sub.2 deposits are also beneficially increased, especially
since TEOS is decomposing as it is entering the CVD reactor. By
increasing the rate at which TEOS decomposes into SiO.sub.2, a
larger percentage of TEOS will actually be consumed and converted
into silicon dioxide films as opposed to being removed from the CVD
reactor unused. As previously indicated, a reduction in carbon
contamination will occur due to the increased amount of hydroxyl
radicals reacting with TEOS and being introduced into the CVD
reactor. It should be appreciated that less carbon contamination
will beneficially generate SiO.sub.2 dielectric layers, as well as
other layers, with improved reliability.
[0025] Referring now to FIG. 1, there is seen a schematic diagram
of an exemplary hydrogen-ion producing reactor, generally
illustrated as 10, communicating with a CVD apparatus, generally
illustrated as 30, through a conduit 12 having a flow control valve
13. In one embodiment of the present invention, water (H.sub.2O)
and/or steam and ozone (O.sub.3) are introduced into reactor
chamber 14 through lines 16 and 18, respectively. Reactor chamber
14 is preferably at a pressure ranging from about 2 Torr to about
400 Torr, more preferably from about 80 Torr to about 200 Torr,
most preferably from about 100 Torr to about 150 Torr. The reactor
chamber 14 is preferably at a temperature ranging from about
50.degree. C. to about 250.degree. C., more preferably from about
100.degree. C. to about 200.degree. C., most preferably from about
150.degree. C. to about 160.degree. C. A radiation transmission
window 22 is coupled to reactor chamber 14 such that a suitable
radiation source may transmit radiation into reactor chamber 14 in
order to enhance the decomposition rate of the injected ozone
molecules. By way of example only, radiation transmission window 22
may be a quartz window suitable to transmit ultraviolet radiation
into reactor chamber 14. In one embodiment, radiation may be
introduced directly from a mercury arc lamp 24 at radiation
transmission window 22. It should be appreciated that any suitable
radiation source or configuration may be substituted for mercury
arc lamp 24. By further way of example only, a radiation source may
have a wavelength radiation spectrum containing a wavelength line
ranging from about 200 nm to about 300 nm, preferably about a
wavelength line containing about 254 nm line corresponding to
strong ozone absorption.
[0026] After ozone and water have entered reactor chamber 14,
mercury arc lamp 24 is activated such that ultraviolet radiation
having an approximate wavelength of 254 nm is directed at the
ozone/water mixture in the reactor chamber 14. In this manner, the
water rich gas phase ozone molecules are caused to decompose and
form oxygen molecules and atomic oxygen (O*) in .sup.1D state. As
described above, since atomic oxygen is highly reactive with water
molecules, a high percentage of hydroxyl radicals will be
generated. The following are the chemical mechanisms involved in
this embodiment of the present invention: 1
[0027] Stated alternatively, hydroxyl radicals are produced via the
ultraviolet photolysis of ozone to produce electronically excited
singlet oxygen atoms:
O.sub.3+hv(.lambda.<310).fwdarw.O(.sup.1D)+O.sub.2
[0028] The primary fate of the singlet oxygen atoms is collistional
deactivation to the triplet ground state:
O.sub.3(.sup.1D)M.fwdarw.O+M
[0029] where M is the cold reactor wall, as stated in the
Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 17, p.
953-994, Fourth Edition published by John Wiley & Sons (New
York, 1996), incorporated herein by reference thereto.
[0030] The ultraviolet photolysis of O.sub.3.H.sub.2O clusters also
provide a source of hydroxyl radicals and/or hydrogen peroxide:
O.sub.3.H.sub.2O+hv.fwdarw.2 OH+O.sub.2 (R1)
O.sub.3.H.sub.2O+hv.fwdarw.H.sub.2O.sub.2+O.sub.2 (R2)
[0031] Reaction 1 (R1) is energetically possible for wavelengths of
light shorter than 665 nm, while reaction 2 (R2) is exothermic even
without the absorption of light. For the absorption of 600 nm
light, the ground state O atoms produced in the ultraviolet
photolysis of ozone have up to 22.2 kcal mol.sup.-1 of
translational energy to overcome the activation barriers necessary
to abstract a hydrogen atom from water or to insert into the water
molecule to form H.sub.2O.sub.2. Since the O atoms would be
produced in the presence of a water molecule, reactions R1 and R2
may be preferential over other reactions, such as combination with
O.sub.2 to reform ozone. Also, hydrogen peroxide (H.sub.2O.sub.2)
produced by reaction R2 above, or otherwise provided for reactor
chamber 14, breaks down or decomposes in the presence of
ultraviolet light into hydroxyl ions, and thus may provide an
additional gas-phase source of hydroxyl radicals:
H.sub.2O.sub.2+hv.fwdarw.2 OH
[0032] Therefore, in another embodiment of the present invention,
hydrogen peroxide (preferably gaseous H.sub.2O.sub.2) solely, or
hydrogen peroxide in combination with ozone and/or water and/or
water vapor or steam, is introduced into the reactor chamber 14 via
conduit or line 28. As previously indicated, hydrogen peroxide
reduces to hydroxyl radicals when contacted by ultraviolet
radiation. When a sufficient quantity of hydroxyl radicals has been
produced in the reactor chamber 14, valve 13 is opened and hydroxyl
radicals in a gas phase flow out of the reactor chamber 14 and into
conduit 12. The hydroxyl radical gas phase comprises a temperature
ranging from about 80.degree. C. to about 175.degree. C., more
preferably from about 100.degree. C. to about 150.degree. C. The
hydroxyl radical gas phase also comprises a pressure ranging from
about 2 Torr to about 400 Torr, preferably from about 50 Torr, to
about 250 Torr, more preferably from about 100 Torr to about 150
Torr.
[0033] In one embodiment of the invention as best shown in FIG. 1,
a precursor (e.g., TEOS) in a gas phase, along with an inert
carrier gas, such as nitrogen, argon and helium (or any other
suitable inert carrier gas such as krypton, radon, and xenon), is
flowed through conduit 29 and into conduit 12 where the hydroxyl
radicals immediately start reacting with the precursor within
conduit 12 before the mixture of precursor and hydroxyl radicals
(along with inert carrier gas, unreacted water, oxygen and ozone)
is introduced into the CVD apparatus 30. As the mixture of
precursor and hydroxyl radicals passes into the CVD apparatus 30,
the hydroxyl radicals are reacting with the precursor, causing
essentially instantaneous decomposition of the precursor as it
enters the CVD apparatus 30. In another embodiment of the invention
as best illustrated in FIG. 2, the precursor (e.g., TEOS) flows
from conduit 29 into a conduit 32 which communicates with the CVD
apparatus 30 in order to cause the gaseous precursor to come in
contact with the gaseous hydroxyl radicals flowing out of conduit
12 in the CVD apparatus 30 such that the reaction of the precursor
and the hydroxyl radicals, as well as decomposition of the
precursor, commences immediately within the CVD apparatus 30. In
FIG. 2, the produced hydroxyl radicals (along with unreacted water,
oxygen and ozone) flow directly into the CVD apparatus 30.
[0034] CVD apparatus 30 includes an enclosure assembly 36 housing a
vacuum chamber 38 with a gas reaction area 40. A gas distribution
plate 42 is provided above the gas reaction area 40 for dispersing
reactive gases through perforated holes in plate 42 to a wafer (not
shown) that rests on a vertically movable heater 44 (also referred
to as wafer support pedestal or susceptor). CVD apparatus 30
further includes a heater/lift assembly 46 for heating the wafer
supported on heater 44. Heater/lift assembly 46 also can be
controllably moved between a lower loading/off-loading position and
an upper processing position indicated by dotted line 48 which is
closely adjacent to plate 42, as shown in FIG. 1. A center board
(not shown) includes sensors for providing information on the
position of the wafer. Heater 44 includes resistively-heated
components enclosed in a ceramic, preferably aluminum nitride or
anodized aluminum. In an exemplary embodiment, all surfaces of
heater 44 exposed to vacuum chamber 38 are made of a ceramic
material, such as aluminum oxide (Al.sub.2O.sub.3 or alumina) or
aluminum nitride. When heater 44 and the wafer are in processing
position 48, they are surrounded by a chamber liner 50 along the
inside walls 52 of CVD apparatus 30 and by an annular pumping
channel 54, formed by chamber liner 56 and a top portion of vacuum
chamber 38. The surface of chamber liner 50 preferably comprises a
ceramic material, such a alumina or aluminum nitride, which serves
to lower the temperature gradient between resistively-heated heater
44 (high temperature) and chamber walls 52, which are at a much
lower temperature relative to heater 44.
[0035] After gaseous hydroxyl radicals (along with unreacted
water/steam, oxygen and ozone) are formed in reactor chamber 14,
valve 13 is subsequently opened causing the formed gaseous hydroxyl
radicals (along with unreacted water/steam, oxygen and ozone) to
either flow directly into the CVD apparatus 30 via conduit 12 as
best shown in FIG. 2, or to be admixed within conduit 29 with
gaseous TEOS (i.e., the precursor), along with its associated inert
carrier gas (e.g., nitrogen or argon), flowing into conduit 12 via
conduit 29. The formed gaseous hydroxyl radicals along with
unreacted water/steam, oxygen and ozone comprise at least about 10%
by volume hydroxyl radicals, preferably from about 10% by volume to
about 30% by volume hydroxyl radicals, more preferably from about
15% by volume to about 25% by volume hydroxyl radicals, most
preferably from about 17% by volume to about 23% by volume (e.g.,
about 20% by volume) hydroxyl radicals. Because the hydroxyl
radicals have a short half-life (e.g., from about 2 secs. to about
14 secs.), once the hydroxyl radicals are produced in the reactor
chamber 14, they are subsequently delivered into the CVD apparatus
30 of FIG. 2 for the embodiment of the invention of FIG. 2, within
about 30 secs. after formation, preferably within a time period
ranging from about 1 sec. to about 30 secs. after formation, more
preferably within a time period ranging from about 2 secs. to about
20 secs. after formation, most preferably within a time period
ranging from about 2 secs. to about 8 secs. after formation. For
the embodiment of the invention of FIG. 1, the hydroxyl radicals
are subsequently delivered into contact with TEOS (i.e., the
precursor) within conduit 12 within about 30 secs. after formation,
preferably into contact with TEOS within a time period ranging from
about 1 sec. to about 30 secs. after formation, more preferably
into contact with TEOS within a time period ranging from about 2
secs. to about 12 secs. after formation, most preferably into
contact with TEOS within a time period ranging from about 2 secs.
to about 8 secs after formation.
[0036] The hydroxyl radical gas (along with associated unreacted
water/steam, oxygen, and ozone) is flowed out of reactor chamber
14, and gaseous TEOS (along with inert carrier gas) is flowed
through conduit 29 at rates such that a stoichiometric amount of
hydroxyl radical gas is available to react with TEOS gas.
Preferably, when gaseous TEOS (along with inert gas) comes into
contact with and mixes with gaseous hydroxyl radicals (along with
unreacted water/steam, oxygen and ozone), either in conduit 12 for
the embodiment of the invention of FIG. 1 or within the CVD
apparatus 30 for the embodiment of the invention of FIG. 2, the
resulting mixture comprises, or consists of, or consists
essentially of, from about 50% to about 95% by volume TEOS (along
with inert gas) and from about 5% by volume to about 50% by volume
hydroxyl radicals (along with unreacted water/steam, oxygen and
ozone), preferably from about 55% to about 90% by volume TEOS
(along with inert gas) and from about 10% to about 45% by volume
hydroxyl radicals (along with unreacted water/steam, oxygen and
ozone), more preferably from about 60% to about 85% by volume TEOS
(along with inert gas) and from about 15% to about 40% by volume
hydroxyl radicals (along with unreacted water/steam, oxygen and
ozone), most preferably from about 65% to about 80% by volume TEOS
(along with inert gas) and from about 20% to about 35% by volume
hydroxyl radicals (along with unreacted water/steam, oxygen and
ozone).
[0037] More specifically, when gaseous TEOS (along with inert gas)
comes into contact with and mixes with gaseous hydroxyl radicals
(along with unreacted water/steam, oxygen and ozone) either for the
embodiment of the invention of FIG. 1 or for the embodiment of the
invention of FIG. 2, the resulting mixture comprises, or consists
of, or consists essentially of, from about 5% to about 15% by
volume TEOS gas, from about 30% to about 50% by volume inert gas,
from about 5% to about 15% by volume hydroxyl radical gas, from
about 0% to about 20% by volume of a water-containing agent (e.g.,
water), from about 10% to about 30% by volume oxygen, from about 0%
to about 5% by volume ozone; more preferably from about 10% to
about 15% by volume TEOS gas, from about 30% to about 40% by volume
inert gas, from about 10% to about 15% by volume hydroxyl radical
gas, from about 0% to about 10% by volume of a water-containing
agent (e.g., water), from about 10% to about 30% by volume oxygen,
from about 0% to about 10% by volume ozone; most preferably from
about 12% to about 15% by volume TEOS gas, from about 40% to about
45% by volume inert gas, from about 12% to about 15% by volume
hydroxyl radical gas, from about 0% to about 8% by volume of a
water-containing agent (e.g., water), from about 15% to about 20%
by volume oxygen, from about 0% to about 5% by volume ozone.
[0038] After gaseous TEOS (along with inert carrier gas) and
hydroxyl radicals (along with unreacted water/steam, oxygen and
ozone) are mixed together, either for the embodiment of the
invention of FIG. 1 or for the embodiment of the invention or of
FIG. 2, the mixture is delivered to plate 42. During deposition
processing, gas supplied to plate 42 is vented toward the wafer
surface (as indicated by arrows 60), where it may be uniformly
distributed radially across the wafer surface, typically in a
laminar flow. Purging gas may be delivered into vacuum chamber 38
from an inlet port or tube (not shown) through the bottom wall of
enclosure assembly 36. The purging gas flows upward past heater 44
and to an annular pumping channel 54. An exhaust system then
exhausts the gas (as indicated by arrows 64) into the annular
pumping channel 54 and through an exhaust line 68 by a vacuum pump
system (not shown). Exhaust gases and residues are preferably
released from annular pumping channel 54 through exhaust line 68 at
a rate controlled by a throttle valve system 70. As indicated
earlier, thermal CVD processes supply reactive gases to the
substrate surface where heat-induced chemical reactions
(homogeneous or heterogeneous) take place to produce a desired
film. In CVD apparatus 30 heat is distributed by resistively-heated
heater 44 that is capable of reaching temperatures as high as about
400-800.degree. C. Such heat distribution provides uniform, rapid
thermal heating of the wafer for effecting deposition, reflow
and/or drive-in, cleaning, and/or seasoning/gettering steps in a
multiple-step process in situ in vacuum chamber 38. Alternatively,
a controlled plasma may be formed adjacent to the wafer by RF
energy applied to gas distribution plate 42 from an RF power supply
(not shown). In embodiments additionally having a lower RF
electrode, the RF power supply can supply either single frequency
RF power to plate 42 or mixed frequency RF power to plate 42 and
the lower RF electrode to enhance the decomposition of reactive
species introduced into process chamber 38. In a plasma process,
some of the components of vapor deposition apparatus 30 would have
to be modified to accommodate the RF energy.
[0039] Thus, by the practice of an embodiment of the present
invention, there is broadly provided a method for depositing a
layer on a substrate in a chemical vapor deposition reaction zone
comprising introducing a precursor, (e.g. TEOS) into a chemical
vapor deposition reaction zone containing a substrate, and
introducing hydroxyl radical in a gas phase into the chemical vapor
deposition reaction zone for reacting with the precursor to form a
deposition layer on the substrate. The hydroxyl radical gas phase
preferably comprises at least about 10% by volume hydroxyl
radicals, and the temperature of the gas phase preferably ranges
from about 100.degree. C. to about 150.degree. C. An inert gas is
typically employed as a carrier gas for the precursor. The method
for depositing a layer additionally comprises producing the
hydroxyl radicals prior to the introducing hydroxyl radicals into
the chemical vapor deposition reaction zone. Preferably, hydroxyl
radicals are introduced at a pressure ranging from about 100
Torrance to about 200 Torrance.
[0040] By the further practice of an embodiment of the present
invention there is further broadly provided a method for forming a
deposition layer in a chemical vapor deposition reactor comprising
the steps of (a) producing hydroxyl radicals; (b) admixing the
produced hydroxyl radicals with a precursor (e.g. a processing gas
such as an organometallic processing gas) to produce a hydroxyl
radicals-precursor mixture; and (c) introducing the hydroxyl
radicals-precursor mixture into the chemical vapor deposition
reactor to form a deposition layer. The producing of hydroxyl
radicals preferably comprises introducing a water-containing agent
(e.g., water) and ozone into a hydroxyl radical-producing reactor;
and directing ultraviolet radiation into the hydroxyl
radical-producing reactor to cause oxygen atoms to form from the
ozone and react with the water-containing agent to produce hydroxyl
radicals. The method additional comprises removing, prior to the
admixing step (b), hydroxyl radicals from the hydroxyl
radical-producing reactor. The admixing of hydroxyl radicals with
the precursor causes the hydroxyl radicals to react with the
precursor. Preferably, the hydroxyl radicals and the precursor are
reacting as the hydroxyl radicals-precursor mixture is being
introduced into the chemical vapor deposition reactor.
[0041] By the still further practice of an embodiment of the
present invention there is also broadly provided, a chemical vapor
deposition reactor, including a CVD reactor chamber, for forming
deposition films comprising a chemical vapor deposition reactor
chamber; and a source of hydroxyl ion gas coupled to the chemical
vapor deposition reactor chamber and including hydroxyl ion gas
flowing or introducing into the chemical vapor deposition reactor
chamber. A pedestal is disposed in the reactor chamber for
supporting substrates in the reactor chamber. The chemical vapor
deposition reactor also comprises a processing power source; a
processing gas-introducing assembly engaged to the reactor chamber
for introducing a processing gas into the reactor chamber; and a
processing power-transmitting member disposed in proximity to the
reactor chamber and connected to the processing power source for
transmitting power into the reactor interior for forming deposition
films. The source of hydroxyl ion gas comprises a hydroxyl-ion
producing reactor having at least one inlet port; a source of water
coupled to the at least one inlet port; a source of ozone gas also
coupled to the at least one inlet port; and a source of ultraviolet
radiation oriented to direct ultraviolet radiation into the
hydroxyl-ion producing reactor.
[0042] Thus, while the present invention has been described herein
with reference to particular embodiments thereof, a latitude of
modification, various changes and substitutions are intended in the
foregoing disclosure, and it will be appreciated that in some
instances some features of the invention will be employed without a
corresponding use of other features without departing from the
scope and spirit of the invention as set forth. Therefore, many
modifications may be made to adapt a particular situation or
material to the essential scope and spirit of the present
invention. It is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments and equivalents falling within the scope of the
appended claims.
* * * * *