U.S. patent application number 11/394971 was filed with the patent office on 2006-08-17 for deposition methods and apparatuses providing surface activation.
Invention is credited to Guy T. Blalock, Garo J. Derderian, Terry L. Gilton, Gurtej S. Sandhu.
Application Number | 20060183322 11/394971 |
Document ID | / |
Family ID | 24617174 |
Filed Date | 2006-08-17 |
United States Patent
Application |
20060183322 |
Kind Code |
A1 |
Sandhu; Gurtej S. ; et
al. |
August 17, 2006 |
Deposition methods and apparatuses providing surface activation
Abstract
A deposition method includes, at a first temperature, contacting
a substrate with a surface activation agent and adsorbing a first
layer over the substrate. At a second temperature greater than the
first temperature, the first layer may be contacted with a first
precursor, chemisorbing a second layer at least one monolayer thick
over the substrate. The first layer may enhance a chemisorption
rate of the first precursor compared to the substrate without the
surface activation agent adsorbed thereon. One deposition apparatus
includes a deposition chamber with a precursor gas dispenser in a
contacting zone and a cooling gas dispenser in a cooling zone. A
substrate chuck moves by linear translational motion from the
contacting zone to the cooling zone. The substrate chuck includes a
substrate lift that positions a deposition substrate at an
elevation above a heated surface of the substrate chuck when
dispensing a cooling gas or surface activation agent. Another
deposition apparatus includes a cooling chamber with a cooled
substrate chuck and a contacting chamber with a heated substrate
chuck. The contacting chamber also has a precursor gas dispenser
and the heated substrate chuck includes a substrate lift. A robotic
substrate handler moves a substrate from the cooled substrate chuck
to the heated substrate chuck.
Inventors: |
Sandhu; Gurtej S.; (Boise,
ID) ; Derderian; Garo J.; (Boise, ID) ;
Blalock; Guy T.; (Boise, ID) ; Gilton; Terry L.;
(Boise, ID) |
Correspondence
Address: |
WELLS ST. JOHN P.S.
601 W. FIRST AVENUE, SUITE 1300
SPOKANE
WA
99201
US
|
Family ID: |
24617174 |
Appl. No.: |
11/394971 |
Filed: |
March 30, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09652533 |
Aug 31, 2000 |
|
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11394971 |
Mar 30, 2006 |
|
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Current U.S.
Class: |
438/654 ;
257/E21.101 |
Current CPC
Class: |
C23C 16/44 20130101;
C23C 16/45534 20130101; C23C 16/45544 20130101; C30B 25/18
20130101; C30B 25/02 20130101; C23C 16/45527 20130101 |
Class at
Publication: |
438/654 |
International
Class: |
H01L 21/44 20060101
H01L021/44 |
Claims
1-54. (canceled)
55. A deposition method comprising: at a first temperature,
contacting a substrate with a first gas containing a surface
activation agent and adsorbing the surface activation agent to form
a first layer over the substrate; and at a second temperature
greater than the first temperature, contacting the first layer with
second gas containing a first precursor and chemisorbing the first
precursor to form a second layer at least one monolayer thick over
the substrate.
56. The deposition method of claim 55 wherein the first layer
enhances a chemisorption rate of the first precursor compared to
the substrate without the surface activation agent adsorbed
thereon.
57. The deposition method of claim 55 wherein the surface
activation agent comprises a metal halide, metal organic, alcohol,
carboxylic acid, or amine.
58. The deposition method of claim 55 wherein the surface
activation agent comprises at least one of TiCl.sub.4, WF.sub.6,
hexamethyldisilazane, tetrakis(dimethylamido)titanium,
tetraethylorthosilicate, H.sub.2O, methanol, ethanol, isopropanol,
formic acid, acetic acid, oxalic acid, NH.sub.3, methylamine,
ethylamine, or dimethylamine.
59. The deposition method of claim 55 wherein the first temperature
is less than a chemisorption temperature of the surface activation
agent on the substrate.
60. The deposition method of claim 55 wherein the second layer is
chemisorbed on the first layer.
61. The deposition method of claim 55 further comprising
substantially displacing the first layer from over the substrate
while chemisorbing the second layer.
62. The deposition method of claim 55 wherein the surface
activation agent is the same as the first precursor.
63. The deposition method of claim 55 wherein the second layer
consists essentially of a monolayer.
64. The deposition method of claim 55 further comprising contacting
the second layer with a second precursor and chemisorbing a third
layer at least one monolayer thick on the second layer, forming a
chemisorption product of the first and second precursors comprising
a deposition material.
65. The deposition method of claim 64 wherein the chemisorption
product consists essentially of a monolayer of the deposition
material.
66. A deposition method comprising: at a first temperature,
contacting a substrate with a first gas containing a surface
activation agent and adsorbing the surface activation agent to form
a first layer over the substrate; at a second temperature greater
than the first temperature, contacting the first layer with second
gas containing a first precursor and chemisorbing the first
precursor to form a second layer at least one monolayer thick over
the substrate, the first layer enhancing a chemisorption rate of
the first precursor compared to an otherwise identical substrate
without the surface activation agent adsorbed thereon; and
contacting the second layer with third gas containing a second
precursor, chemisorbing a third layer at least one monolayer thick
on the second layer, and forming a chemisorption product of the
first and second precursors.
67. A deposition method comprising: at an initial temperature less
than a chemisorption temperature of a surface activation agent,
adsorbing the agent over a substrate; and at a deposition
temperature greater than the initial temperature, atomic layer
depositing a first species over the substrate from a precursor
gas.
68. The deposition method of claim 67 wherein the surface
activation agent enhances an atomic layer deposition rate of the
first species compared to the substrate without the surface
activation agent adsorbed thereon.
69. The deposition method of claim 67 wherein the surface
activation agent comprises a metal halide, metal organic, alcohol,
carboxylic acid, or amine.
70. The deposition method of claim 67 wherein the surface
activation agent comprises at least one of TiCl.sub.4, WF.sub.6,
hexamethyldisilazane, tetrakis(dimethylamido)titanium,
tetraethylorthosilicate, H.sub.2O, methanol, ethanol, isopropanol,
formic acid, acetic acid, oxalic acid, NH.sub.3, methylamine,
ethylamine, or dimethylamine.
71. The deposition method of claim 67 wherein the surface
activation agent is the same as the first species.
72. The deposition method of claim 67 further comprising
substantially displacing the surface activation agent from over the
substrate during the atomic layer depositing the first species.
73. The deposition method of claim 67 further comprising atomic
layer depositing a second species on the atomic layer deposited
first species, the deposited first and second species combined
comprising a deposition material.
74. A deposition method comprising: adsorbing a surface activation
agent over a substrate, during the adsorbing at least an outer
surface of the substrate being at a first temperature less than a
chemisorption temperature of the agent; altering a temperature of
at least a portion of the substrate; chemisorbing a monolayer of a
first compound over the substrate from a precursor gas, during the
first compound chemisorbing at least an outer surface of the
substrate being at a second temperature greater than the first
temperature, and substantially displacing the agent from over the
substrate; and chemisorbing a monolayer of a second compound on the
first compound monolayer.
75. The deposition method of claim 74 wherein the adsorbed surface
activation agent enhances a chemisorption rate of the first
compound compared to the substrate without the surface activation
agent adsorbed thereon.
76. The deposition method of claim 74 wherein the surface
activation agent comprises a metal halide, metal organic, alcohol,
carboxylic acid, or amine.
77. The deposition method of claim 74 wherein the surface
activation agent comprises at least one of TiCl.sub.4, WF.sub.6,
hexamethyidisilazane, tetrakis(dimethylamido)titanium,
tetraethylorthosilicate, H.sub.2O, methanol, ethanol, isopropanol,
formic acid, acetic acid, oxalic acid, NH.sub.3, methylamine,
ethylamine, or dimethylamine.
78. The deposition method of claim 74 wherein the surface
activation agent is the same as the first compound.
79. A deposition method comprising: contacting a bulk semiconductor
wafer with a cooling medium to establish at least an outer surface
of the wafer at an initial temperature; contacting the wafer with a
surface activation agent and adsorbing a first layer on the wafer,
the initial temperature being less than a chemisorption temperature
of the agent; placing the wafer on a heated wafer chuck and
establishing at least the outer surface of the wafer at a
deposition temperature greater than the initial temperature; and at
the deposition temperature, contacting the first layer with a
deposition precursor gas and chemisorbing a second layer at least
one monolayer thick over the wafer.
80. The deposition method of claim 79 wherein the contacting with
the cooling medium comprises elevating the wafer over the heated
wafer chuck and contacting the wafer with cooling gases and wherein
the placing the wafer comprises lowering the wafer onto the heated
wafer chuck.
81. The deposition method of claim 79 wherein the contacting with
the cooling medium comprises placing the wafer on a cooled wafer
chuck different from the heated wafer chuck.
82. The deposition method of claim 79 wherein the contacting with
the surface activation agent and deposition precursor comprises
moving the wafer within a single chamber of a deposition apparatus
from a first zone containing the surface activation agent to a
second zone containing the deposition precursor.
83. The deposition method of claim 82 wherein the moving is
accomplished by linear translational motion of the heated wafer
chuck.
84. The deposition method of claim 79 wherein the contacting with
the surface activation agent and deposition precursor comprises
moving the wafer from a cooled wafer chuck in a first chamber of a
multiple chamber deposition apparatus to a second chamber of the
apparatus wherein contacting with the agent and contacting with the
precursor may occur.
85. The deposition method of claim 84 wherein the moving is
accomplished by a robotic wafer handler.
86. The deposition method of claim 79 wherein the first layer
enhances a chemisorption rate of the deposition precursor compared
to the wafer without the surface activation agent adsorbed
thereon.
87. The deposition method of claim 79 wherein the surface
activation agent comprises a metal halide, metal organic, alcohol,
carboxylic acid, or amine.
88. The deposition method of claim 79 wherein the surface
activation agent comprises at least one of TiCl.sub.4, WF.sub.6,
hexamethyldisilazane, tetrakis(dimethylamido)titanium,
tetraethylorthosilicate, H.sub.2O, methanol, ethanol, isopropanol,
formic acid, acetic acid, oxalic acid, NH.sub.3, methylamine,
ethylamine, or dimethylamine.
89. The deposition method of claim 79 wherein the surface
activation agent is the same as the deposition precursor.
90. The deposition method of claim 79 wherein the second layer
consists essentially of a monolayer.
Description
TECHNICAL FIELD
[0001] This invention relates to deposition methods including
surface activation of a substrate and deposition apparatuses
providing surface activation of a substrate.
BACKGROUND OF THE INVENTION
[0002] Atomic layer deposition (ALD) is recognized as a deposition
technique that forms high quality materials with minimal defects
and tight statistical process control. Even so, it is equally
recognized that ALD can have limited application. In some
circumstances, the theoretically expected quality of an ALD layer
is not achieved.
[0003] It can be seen that a need exists for an ALD method that
forms a layer without introducing intolerable defects into the
material.
SUMMARY OF THE INVENTION
[0004] According to one aspect of the invention, a deposition
method includes, at a first temperature, contacting a substrate
with a surface activation agent and adsorbing a first layer over
the substrate. At a second temperature greater than the first
temperature, the first layer may be contacted with a first
precursor and a second layer may be chemisorbed at least one
monolayer thick over the substrate. As an example, the first layer
may enhance a chemisorption rate of the first precursor compared to
the substrate without the surface activation agent adsorbed
thereon. Also, the first temperature may be less than a
chemisorption temperature of the surface activation agent on the
substrate. The first and second temperatures may be those of at
least a portion of the substrate, those of an outermost surface of
the substrate, or, respectively, those of the surface activation
agent and first precursor. The second layer may be chemisorbed on
the first layer, or the method may include substantially displacing
the first layer from over the substrate during chemisorption of the
first layer on the substrate.
[0005] In another aspect of the invention, a deposition method
includes, at an initial temperature less than a chemisorption
temperature of a surface activation agent, adsorbing the agent over
a substrate. At a deposition temperature greater than the initial
temperature, a first species may be atomic layer deposited over the
substrate. As an example, the surface activation agent may enhance
an atomic layer deposition rate of the first species compared to
the substrate without the surface activation agent adsorbed
thereon. The method may further include atomic layer depositing a
second species on the atomic layer deposited first species, the
deposited first and second species combined comprising a deposition
material.
[0006] In a further aspect of the invention, a deposition method
includes adsorbing a surface activation agent over a substrate, at
least an outer surface of the substrate being at a first
temperature less than a chemisorption temperature of the agent. A
temperature of at least a portion of the substrate may then be
altered. A monolayer of a first compound may be chemisorbed over
the substrate, at least an outer surface of the substrate being at
a second temperature greater than the first temperature. The agent
may be substantially displaced from over the substrate and a
monolayer of a second compound may be chemisorbed on the first
compound monolayer.
[0007] A still further aspect of the invention includes a
deposition method of contacting a bulk semiconductor wafer with a
cooling medium to establish at least an outer surface of the wafer
at an initial temperature. The wafer may be contacted with a
surface activation agent, adsorbing a first layer on the wafer. The
initial temperature may be less than a chemisorption temperature of
the agent. The wafer may be placed on a heated wafer chuck,
establishing at least an outer surface of the wafer at a deposition
temperature greater than the initial temperature. The first layer
may be contacted with a deposition precursor, chemisorbing a second
layer at least one monolayer thick over the wafer. Examples of
contacting with a cooling medium include elevating the wafer over
the heated wafer chuck and contacting the wafer with cooling gases
as well as placing the wafer on a cooled wafer chuck different from
the heated wafer chuck.
[0008] Other aspects of the invention include deposition
apparatuses. One such apparatus includes a deposition chamber
having at least one precursor gas dispenser in each of at least one
contacting zone and at least one cooling gas dispenser in each of
at least one cooling zone. A substrate chuck moves by linear
translational motion from the at least one contacting zone to the
at least one cooling zone. The substrate chuck includes a substrate
lift that positions a deposition substrate at an elevation above
the heated surface of the substrate chuck when dispensing a cooling
gas in the at least one cooling zone and when dispensing a surface
activation agent in the at least one contacting zone. An exemplary
deposition chamber has two contacting zones and one cooling zone.
The substrate chuck moves from one contacting zone through the
cooling zone to another contacting zone. Contacting and cooling
zones may be established with at least one of an inert gas curtain
or suitable gas flow conditions. Also, the substrate lift may
comprise positioning pins of a substrate chuck.
[0009] Another deposition apparatus includes at least one cooling
chamber having a cooled substrate chuck and at least one contacting
chamber having a heated substrate chuck. The contacting chamber may
also have at least one precursor gas dispenser. The heated
substrate chuck may include a substrate lift that positions a
deposition substrate at an elevation above a heated surface of the
heated substrate chuck when dispensing a surface activation agent
in the contacting chamber. A robotic substrate handler may move a
substrate from the at least one cooled substrate chuck to the at
least one heated substrate chuck.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] S Preferred embodiments of the invention are described below
with reference to the following accompanying drawings.
[0011] FIGS. 1-4 are line charts respectively showing the timing
for contacting a substrate in an atomic layer deposition process
with a surface activation agent, precursor 1, precursor 2, and
purge gas.
[0012] FIG. 5 is a line chart showing the timing for altering
temperature during the contacting described in FIGS. 1-4.
[0013] FIG. 6 shows a diagrammatic view of a deposition apparatus
according to one aspect of the invention at a processing step
according to another aspect of the present invention.
[0014] FIG. 7 shows the deposition apparatus of FIG. 6 at a
processing step subsequent to that shown in FIG. 6.
[0015] FIG. 8 shows a diagrammatic view of an alternative
deposition apparatus according to a further aspect of the invention
at a processing step according to yet another aspect of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] This disclosure of the invention is submitted in furtherance
of the constitutional purposes of the U.S. Patent Laws "to promote
the progress of science and useful arts" (Article 1, Section
8).
[0017] Atomic layer deposition (ALD) involves formation of
successive atomic layers on a substrate. Such layers may comprise
an epitaxial, polycrystalline, amorphous, etc. material. ALD may
also be referred to as atomic layer epitaxy, atomic layer
processing, etc. Further, the invention may encompass other
deposition methods not traditionally referred to as ALD, for
example, chemical vapor deposition (CVD), but nevertheless
including the method steps described herein. The deposition methods
herein may be described in the context of formation on a
semiconductor wafer. However, the invention encompasses deposition
on a variety of substrates besides semiconductor substrates.
[0018] In the context of this document, the term "semiconductor
substrate" or "semiconductive substrate" is defined to mean any
construction comprising semiconductive material, including, but not
limited to, bulk semiconductive materials such as a semiconductive
wafer (either alone or in assemblies comprising other materials
thereon), and semiconductive material layers (either alone or in
assemblies comprising other materials). The term "substrate" refers
to any supporting structure, including, but not limited to, the
semiconductive substrates described above.
[0019] Described in summary, ALD includes exposing an initial
substrate to a first chemical species to accomplish chemisorption
of the species onto the substrate. Theoretically, the chemisorption
forms a monolayer that is uniformly one atom or molecule thick on
the entire exposed initial substrate. In other words, a saturated
monolayer. Practically, as further described below, chemisorption
might not occur on all portions of the substrate. Nevertheless,
such an imperfect monolayer is still a monolayer in the context of
this document. In many applications, merely a substantially
saturated monolayer may be suitable. A substantially saturated
monolayer is one that will still yield a deposited layer exhibiting
the quality and/or properties desired for such layer.
[0020] The first species is purged from over the substrate and a
second chemical species is provided to chemisorb onto the first
monolayer of the first species. The second species is then purged
and the steps are repeated with exposure of the second species
monolayer to the first species. In some cases, the two monolayers
may be of the same species. Also, a third species or more may be
successively chemisorbed and purged just as described for the first
and second species.
[0021] Purging may involve a variety of techniques including, but
not limited to, contacting the substrate and/or monolayer with a
carrier gas and/or lowering pressure to below the deposition
pressure to reduce the concentration of a species contacting the
substrate and/or chemisorbed species. Examples of carrier gases
include N.sub.2, Ar, He, Ne, Kr, Xe, etc. Purging may instead
include contacting the substrate and/or monolayer with any
substance that allows chemisorption byproducts to desorb and
reduces the concentration of a contacting species preparatory to
introducing another species. A suitable amount of purging can be
determined experimentally as known to those skilled in the art.
Purging time may be successively reduced to a purge time that
yields an increase in film growth rate. The increase in film growth
rate might be an indication of a change to a non-ALD process regime
and may be used to establish a purge time limit.
[0022] ALD is often described as a self-limiting process, in that a
finite 11 number of sites exist on a substrate to which the first
species may form chemical bonds. The second species might only bond
to the first species and thus may also be self-limiting. Once all
of the finite number of sites on a substrate are bonded with a
first species, the first species will often not bond to other of
the first species already bonded with the substrate. However,
process conditions can be varied in ALD to promote such bonding and
render ALD not self-limiting. Accordingly, ALD may also encompass a
species forming other than one monolayer at a time by stacking of a
species, forming a layer more than one atom or molecule thick. The
various aspects of the present invention described herein are
applicable to any circumstance where ALD may be desired. A few
examples of materials that may be deposited by ALD include silicon
nitride, zirconium oxide, tantalum oxide, aluminum oxide, and
others.
[0023] Often, traditional ALD occurs within an often-used range of
temperature and pressure and according to established purging
criteria to achieve the desired formation of an overall ALD layer
one monolayer at a time. Even so, ALD conditions can vary greatly
depending on the particular precursors, layer composition,
deposition equipment, and other factors according to criteria known
by those skilled in the art. Maintaining the traditional conditions
of temperature, pressure, and purging minimizes unwanted reactions
that may impact monolayer formation and quality of the resulting
overall ALD layer. Accordingly, operating outside the traditional
temperature and pressure ranges may risk formation of defective
monolayers.
[0024] The general technology of chemical vapor deposition (CVD)
includes a variety of more specific processes, including, but not
limited to, plasma enhanced CVD and others. CVD is commonly used to
form non-selectively a complete, deposited material on a substrate.
One characteristic of CVD is the simultaneous presence of multiple
species in the deposition chamber that react to form the deposited
material. Such condition is contrasted with the purging criteria
for traditional ALD wherein a substrate is contacted with a single
deposition species that chemisorbs to a substrate or previously
deposited species. An ALD process regime may provide a
simultaneously contacted plurality of species of a type or under
conditions such that ALD chemisorption, rather than CVD reaction
occurs. Instead of reacting together, the species may chemisorb to
a substrate or previously deposited species, providing a surface
onto which subsequent species may next chemisorb to form a complete
layer of desired material.
[0025] Under most CVD conditions, deposition occurs largely
independent of the composition or surface properties of an
underlying substrate. By contrast, chemisorption rate in ALD might
be influenced by the composition, crystalline structure, and other
properties of a substrate or chemisorbed species. Other process
conditions, for example, pressure and temperature, may also
influence chemisorption rate. Accordingly, observation indicates
that chemisorption might not occur appreciably on portions of a
substrate though it occurs at a suitable rate on other portions of
the same substrate. Such a condition may introduce intolerable
defects into a deposited material.
[0026] According to one aspect of the invention, a deposition
method may include, at a first temperature, contacting a substrate
with a surface activation agent and adsorbing a first layer over
the substrate. At a second temperature greater than the first
temperature, the first layer may be contacted with a first
precursor. A second layer may be chemisorbed at least one monolayer
thick over the substrate. Advantageously, the first layer may
enhance a chemisorption rate of the first precursor compared to the
substrate without the surface activation agent adsorbed thereon.
Enhancement of a chemisorption rate of the first precursor may
occur in a variety of ways. For example, where chemisorption of the
first precursor does not occur uniformly across the substrate, the
surface activation agent may provide chemisorption at substantially
the same rate, but uniformly across the substrate. Also, a surface
activation agent may increase chemisorption rate over regions of a
substrate where chemisorption normally would occur, but at a slower
rate. The observed effect of either enhancement will be to increase
the average chemisorption rate over all of the substrate.
[0027] Within the context of this document, "adsorption" refers to
surface retention of solid, liquid, or gas molecules, atoms, or
ions by a solid or liquid, as opposed to "absorption," the
penetration of substances into the bulk of the solid or liquid.
Further, in the context of this document, chemisorption refers to a
type of adsorption in which chemical bonds are formed between
solid, liquid, or gas molecules, atoms, or ions and a solid or
liquid surface. The chemical bonds may be weak chemical bonds.
[0028] It is a disadvantage of some deposition methods, for example
ALD, that nonuniform deposition may occur over regions of a
substrate where some difference in surface properties or
composition exists in the substrate. By adsorbing a first layer
including a surface activation agent over a substrate at a first
temperature less than a chemisorption temperature of the surface
activation agent on the substrate, more uniform formation of the
first layer may be established. The second layer including the
first precursor may be chemisorbed on the first layer.
Alternatively, the method may include substantially displacing the
first layer from over the substrate during the chemisorbing second
layer. In such a circumstance, the second layer may be chemisorbed
on the substrate. In substantially displacing the surface
activation agent, a negligible amount of surface activation agent
may remain on which the first precursor may or may not chemisorb.
However, substantially displacing the surface activation agent is
sufficient to establish a deposited material having the desired
properties. Adsorbing the first layer, but not chemisorbing the
first layer, may provide a more uniform layer of a surface
activation agent than would be established in chemisorption of the
same agent or material.
[0029] A variety of surface activation means may be utilized, for
example, 1s the surface activation agent may be the same as the
first precursor or the surface activation agent may be different
from any other precursors used in a deposition method. For example,
and preferably, the surface activation agent may be a metal halide,
a metal organic, an alcohol, a carboxylic acid, or an amine. Also
for example, and more preferably, the surface activation agent may
be at least one of TiCl.sub.4, WF.sub.6, hexamethyldisilazane,
tetrakis(dimethylamido)titanium, tetraethylorthosilicate, H.sub.2O,
methanol, ethanol, isopropanol, formic acid, acetic acid, oxalic
acid, NH.sub.3, methylamine, ethylamine, or dimethylamine.
Contacting of the substrate may comprise contacting a bulk
semiconductor wafer, or some other material formed over such a
wafer, wherein such contacting initiates formation of a new
material. Alternatively, contacting a substrate may include
contacting a previously chemisorbed layer of a deposition precursor
and adsorbing the surface activation agent on the previously
chemisorbed layer. That is, adsorbing a surface activation agent
may be advantageous both in initiating a deposition method as well
as continuing a deposition method after initiation.
[0030] A variety of processing conditions may also be suitable
according to various aspects of the invention. For example, at a
first temperature, when contacting a substrate with a surface
activation agent and, at a second temperature, contacting the
surface activation agent with a first precursor, the first and
second temperatures may be those of at least a portion of the
substrate. Also, the first and second temperatures may be those of
an outermost surface of the substrate. Still further, the first and
second temperatures may be, respectively, those of the surface
activation agent and the first precursor. Actual first and second
temperatures will depend largely on the individual properties of
the surface activation agent and the first precursor as well as a
desired deposition material.
[0031] Also, chemisorbing the second layer may be accomplished in a
variety of ways. The first precursor may consist essentially of a
single precursor species. Alternatively, as discussed above, a
plurality of species may be used as the first precursor. The second
layer chemisorbed from the first precursor may consist essentially
of a monolayer. Further, the method may include contacting the
second layer with a second precursor and chemisorbing at least one
monolayer thick on the second layer. A chemisorption product of the
first and second precursors may form a deposition material. The
chemisorption product may consist essentially of a monolayer of the
deposition material.
[0032] As another aspect of the invention, a deposition method may
include, at an initial temperature less than a chemisorption
temperature 11 of a surface activation agent, adsorbing the agent
over a substrate. At a deposition temperature greater than the
initial temperature, a first species may be atomic layer deposited
over the substrate. Similar surface activation agents to those
described above may be used. Such a surface activation agent may
enhance an atomic layer deposition rate of the first species
compared to the substrate without the surface activation agent
adsorbed thereon. The initial and deposition temperatures may be
those of at least a portion of the substrate, as well as other
substances, such as those described above. The method may further
include atomic layer depositing a second species on the atomic
layer deposited first species. The deposited first and second
species combined may comprise a deposition material.
[0033] As a further aspect of the invention, a deposition method
may include adsorbing a surface activation agent over a substrate.
At least an outer surface of the substrate may be at a first
temperature less than a chemisorption temperature of the agent. A
temperature of at least a portion of the substrate may then be
altered and a monolayer of a first compound may be chemisorbed over
the substrate. At least an outer surface of the substrate may be at
a second temperature greater than the first temperature. The
chemisorption may substantially displace the agent from over the
substrate. The method may further include chemisorbing a monolayer
of a second compound on the first compound monolayer. As before,
the adsorbed surface activation agent may advantageously enhance a
chemisorption rate of the first compound compared to the substrate
without the surface activation agent adsorbed thereon.
[0034] A still further aspect of the invention provides a
deposition method that includes contacting a bulk semiconductor
wafer with a cooling medium to establish at least an outer surface
of the wafer at an initial temperature. The wafer may be contacted
with a surface activation agent, adsorbing a first layer on the
wafer. The initial temperature may be less than a chemisorption
temperature of the agent. The wafer may be placed on a heated wafer
chuck and at least an outer surface of the wafer established at a
deposition temperature greater than the initial temperature. The
first layer may be contacted with a deposition precursor,
chemisorbing a second layer at least one monolayer thick over the
wafer. In keeping with the previous description, the first layer
may enhance a chemisorption rate of the deposition precursor
compared to the wafer without the surface activation agent adsorbed
thereon. Also, the surface activation agent may be the same as the
deposition precursor or, alternatively, different.
[0035] Contacting with the cooling medium may be accomplished in a
variety of ways. As one example, the wafer may be elevated over the
heated wafer chuck and contacted with cooling gases. Placing the
wafer on the heated wafer chuck may include lowering the wafer from
the position where the wafer was contacted with cooling gases.
Also, for example, contacting the wafer with a cooling medium may
include placing the wafer on a cooled wafer chuck different from
the heated wafer chuck.
[0036] Contacting the wafer with a surface activation agent and
deposition precursor may also be accomplished in a variety of ways.
For example, the wafer may be moved within a single chamber of a
deposition apparatus from a first zone containing a surface
activation agent to a second zone containing the deposition
precursor. The moving may be accomplished by linear translational
motion of the heated wafer chuck. Also for example, the wafer may
be moved from a cooled wafer chuck in a first chamber of a multiple
chamber deposition apparatus to a second chamber of the apparatus
wherein contacting with the agent and contacting with the precursor
may occur. The moving may be accomplished by a robotic wafer
handler.
[0037] Accordingly, other aspects of the invention include
deposition apparatuses that accomplish surface activation of a
substrate. One exemplary deposition apparatus includes a deposition
chamber having at least one precursor gas dispenser in each of at
least one contacting zone and at least one cooling gas dispenser in
each of at least one cooling zone. A substrate chuck moves by
linear translational motion from the at least one contacting zone
to the at least one cooling zone. The substrate chuck may include a
substrate lift that positions a deposition substrate at an
elevation above a heated surface of the substrate chuck. Such
positioning of a deposition substrate may occur when dispensing a
cooling gas in the at least one cooling zone and when dispensing a
surface activation agent in the at least one contacting zone.
[0038] FIGS. 6 and 7 show a deposition apparatus 2 with a
deposition chamber 4 having a contacting zone 20 and a contacting
zone 24 as well as a cooling zone 22. Precursor gas dispenser 6
supplies gases 6a and/or 6b to contacting zone 20. Precursor gas
dispenser 10 supplies gases 10a and/or 10b to contacting zone 24.
Cooling gas dispenser 8 supplies gas 8a to cooling zone 22. Zone
boundaries 18 isolate contacting zone 20 from cooling zone 22 and
contacting zone 24 from cooling zone 22.
[0039] Isolation of zones 20, 22, and 24 within deposition chamber
4 may be accomplished in a variety of ways. As one example,
contacting and cooling zones may be established with an inert gas
curtain as known to those skilled in the art. Nitrogen, Ar, and He
are examples of suitable inert gases. Also, such zones may be
established using suitable gas flow conditions as known to those
skilled in the art. For example, laminar flow conditions may be
suitable. The suitability of particular conditions may be
experimentally determined in any manner known to those skilled in
the art for a particular deposition chamber and combination of
gases and apparatuses inside the chamber that can affect gas
mixing. The gas flow conditions may minimize mixing of flowing
gases in contacting and cooling zones such that only negligible
mixing occurs of supplied gases in a region defined as a zone
boundary, for example, zone boundaries 18. Further, the cooling
zone may consist essentially of an inert gas curtain isolating two
contacting zones. For example, gas 8a may be a cooling gas as well
as an inert gas such that no separate inert gas curtain is desired
to isolate contacting zone 20 from cooling zone 22 and contacting
zone 24 from cooling zone 22.
[0040] FIG. 6 also shows a wafer chuck 12 having positioning pins
14 as a substrate lift upon which wafer 16 is placed. Positioning
pins 14 position wafer 16 at an elevation above wafer chuck 12.
Accordingly, when wafer chuck 12 is heated, wafer 16 will be
distanced from a heated surface of wafer chuck 12 for cooling of at
least an outer surface of wafer 16 by gas 8a.
[0041] As shown in FIG. 7, wafer chuck 12 may move by linear
translational motion from cooling zone 22 to contacting zone 20 and
positioning pins 14 may lower wafer 16 from the elevation above the
heated surface of wafer chuck 12. FIG. 7 shows wafer 16 completely
lowered so as to rest on wafer chuck 12, however, an intermediate
position between the positions shown in FIGS. 6 and 7 may also be
suitable. Gases 6a and/or 6b may be dispensed from precursor gas
dispenser 6 with wafer 16 in a lowered position to accomplish
chemisorption of a deposition precursor on wafer 16. Although not
shown, wafer chuck 12 may also move into contacting zone 24 without
lowering positioning pins 14 to accomplish adsorption of a surface
activation agent dispensed from precursor gas dispenser 10 at the
temperature established in cooling zone 22. Accordingly, substrate
chuck 12 may move from one contacting zone through cooling zone 22
to another contacting zone in performing a deposition method such
as the various methods described herein. Temperature, contacting of
surface activation agents and precursors, chemisorption, and
adsorption may be controlled as preferred accordingly to the
various aspects of the invention using the apparatus of FIGS. 6 and
7.
[0042] Similarly, such methods may also be practiced in a
deposition apparatus that includes at least one cooling chamber
having a cooled substrate chuck and at least one contacting chamber
having at least one precursor gas dispenser. The at least one
contacting chamber may also have a heated substrate chuck including
a substrate lift that positions a deposition substrate at an
elevation above a heated surface of the heated substrate chuck when
dispensing a surface activation agent in the contacting chamber. A
robotic substrate handler may be provided that moves a substrate
from the at least one cooled substrate chuck to the at least one
heated substrate chuck. One example of such an apparatus is shown
in FIG. 8.
[0043] Deposition apparatus 30 of FIG. 8 includes a contacting
chamber 40 and a cooling chamber 42. A heated wafer chuck 32
provided in contacting chamber 40 includes positioning pins 34
analogous to positioning pins 14 shown in FIGS. 6 and 7.
Positioning pins 34 are shown in FIG. 8 in a raised position. A gas
dispenser 38 supplies gases 38a and/or 38b to contacting chamber
40. Cooling chamber 42 includes a cooled wafer chuck 36. Although
not shown, a robotic wafer handler moves wafer 16 from cooled wafer
chuck 36 to heated wafer chuck 32.
[0044] When adsorbing a surface activation agent on wafer 16,
positioning pins 34 may operate as a substrate lift to elevate
wafer 16 above the heated surface of the substrate chuck.
Accordingly, adsorption at a temperature lower than that of heated
wafer chuck 32 may be accomplished. Positioning pins 34 may then
lower wafer 16 from the elevation above the heated surface to
increase temperature and accomplish chemisorption of a deposition
precursor in contacting chamber 40. Accordingly, both a surface
activation agent and a deposition precursor may be supplied from
gas dispenser 38 at appropriate times to accomplish adsorption and
chemisorption.
[0045] Turning to FIGS. 1-5, a process regime is described for ALD
that is within the scope of the present invention. FIGS. 1-4 show
the cyclic contacting and purging of a substrate with surface
activation agent (SAA), Precursor 1 (P1), and Precursor 2 (P2). As
shown in FIG. 1, a substrate is first contacted with SAA from Time
0 (T0) to Time 1 (T1). An optional purge of SAA that is not
adsorbed to a substrate may then occur from T1 to T2. Such purge is
optional depending on the particular SAA and P1 selected. For
example, if SAA and P1 are identical, then it is conceivable that
purging might not occur prior to chemisorption of P1. Adsorbed SAA
is then contacted with P1 from T2 to T3, chemisorbing P1 over the
substrate. As discussed above, P1 may chemisorb either to adsorbed
SAA, to the substrate after displacing SAA, or both. After purging
excess P1 from T3 to T4, chemisorbed P1 is contacted with P2 from
T4 to T5. After purging excess P2 from T5 to T6, the cycle begins
again. However, the cycle may begin by either contacting
chemisorbed P2 with SAA or P1 from T6 to T7. As also discussed
above, it may be desirable only to adsorb SAA as an initial layer
or to adsorb SAA at the beginning of more than one cycle of
chemisorbing deposition precursors. Accordingly, contacting SAA
from T6 to T7 is shown in dashed outline as an optional step and
contacting with P1 from T6 to T7 is shown in dash-dot outline also
indicating an optional step.
[0046] The cycle from T0 to T5 thus may form at least a monolayer
of a chemisorption product of P1 and P2. The purge from T5 to T6
prepares the chemisorption product of P1 and P2 to begin a new
cycle at T6. Notably, the time intervals from T0 to T1 to T2, etc.,
are shown as equal merely for graphical convenience. In practice,
such times may be individually determined according to the
knowledge of those skilled in the art considering the aspects and
advantages of the inventions described herein.
[0047] FIG. 5 shows altering the temperature, preferably substrate
temperature, as part of the described method. Temperature 1 (Temp1)
is maintained from T0 to T1 during contacting of SAA. Thereafter,
temperature is increased to Temp2 during purging from T1 to T2 and
maintained at Temp2 during contacting of P1, purging, and
contacting of P2 from T2 to T5. Depending on whether SAA or P1 will
be contacted from T6 to T7, temperature may be reduced from Temp2
to Temp1 from T5 to T6 or may remain at Temp2. Accordingly,
temperature remaining at Temp2 from T5 to T7 is shown in dash-dot
outline to correspond with contacting P1 and decreasing temperature
is shown in dashed outline to correspond with contacting SAA.
[0048] In keeping with the various aspects of the invention, other
scenarios of contacting surface activating agents and precursors
and altering temperatures are also conceivable, some of which are
expressly described herein. For example, since temperature changes
are involved, it is conceivable that a desired temperature might
not be established before starting contacting of a surface
activation agent or precursor. Rather, it may be suitable to
establish such temperature some time after the start of contacting.
Consideration may be made regarding whether the delay in
establishing a temperature is justified by an improvement in
adsorption or chemisorption efficiency. That is, if a desired
temperature for chemisorption is established before contacting,
then a difference in chemisorption efficiency might exist compared
to not establishing the temperature until after contacting begins.
Accordingly, a deposition method according to the various aspects
of the invention herein may be optimized for processing time and
efficiency depending on the priorities and objectives of a
particular process.
[0049] In compliance with the statute, the invention has been
described in language more or less specific as to structural and
methodical features. It is to be understood, however, that the
invention is not limited to the specific features shown and
described, since the means herein disclosed comprise preferred
forms of putting the invention into effect. The invention is,
therefore, claimed in any of its forms or modifications within the
proper scope of the appended claims appropriately interpreted in
accordance with the doctrine of equivalents.
* * * * *