U.S. patent application number 14/855195 was filed with the patent office on 2016-01-07 for enhanced deposition of layer on substrate using radicals.
The applicant listed for this patent is Veeco ALD Inc.. Invention is credited to Sang In Lee.
Application Number | 20160002783 14/855195 |
Document ID | / |
Family ID | 46652960 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160002783 |
Kind Code |
A1 |
Lee; Sang In |
January 7, 2016 |
ENHANCED DEPOSITION OF LAYER ON SUBSTRATE USING RADICALS
Abstract
Embodiments relate to using radicals to at different stages of
deposition processes. The radicals may be generated by applying
voltage across electrodes in a reactor remote from a substrate. The
radicals are injected onto the substrate at different stages of
molecular layer deposition (MLD), atomic layer deposition (ALD),
and chemical vapor deposition (CVD) to improve characteristics of
the deposited layer, enable depositing of material otherwise not
feasible and/or increase the rate of deposition. Gas used for
generating the radicals may include inert gas and other gases. The
radicals may disassociate precursors, activate the surface of a
deposited layer or cause cross-linking between deposited
molecules.
Inventors: |
Lee; Sang In; (Los Altos
Hills, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Veeco ALD Inc. |
Fremont |
CA |
US |
|
|
Family ID: |
46652960 |
Appl. No.: |
14/855195 |
Filed: |
September 15, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13397590 |
Feb 15, 2012 |
9163310 |
|
|
14855195 |
|
|
|
|
61444651 |
Feb 18, 2011 |
|
|
|
61511333 |
Jul 25, 2011 |
|
|
|
Current U.S.
Class: |
427/569 ;
427/255.28; 427/255.391; 427/255.394; 427/578; 427/579 |
Current CPC
Class: |
B05D 1/36 20130101; C23C
16/45553 20130101; C23C 16/345 20130101; B05D 1/38 20130101; C23C
16/45534 20130101; C23C 16/45517 20130101; C23C 16/513 20130101;
B05D 1/60 20130101; B05D 1/62 20130101 |
International
Class: |
C23C 16/455 20060101
C23C016/455; C23C 16/34 20060101 C23C016/34; C23C 16/513 20060101
C23C016/513 |
Claims
1. A method of performing atomic layer deposition, comprising:
generating radicals of a gas or a mixture of gases; injecting the
generated radicals onto a surface of a substrate to increase a
number of nucleation sites on the substrate by placing the surface
of the substrate in a reactive state; injecting a first source
precursor onto the surface of the substrate placed in the reactive
state, adsorption of the first source precursor on the substrate
facilitated by increase in the number of nucleation sites; and
injecting a first reactant precursor onto the substrate injected
with the first source precursor to deposit a layer on the surface
of the substrate.
2. The method of claim 1, wherein the gas or mixture of gases
comprise inert gas.
3. The method of claim 2, wherein the inert gas is Argon.
4. The method of claim 1, further comprising: injecting the
generated radicals onto the surface of the substrate deposited with
the layer; injecting a second source precursor onto the surface of
the substrate deposited with the layer; and injecting a second
reactant precursor onto the surface of the substrate deposited with
the layer to deposit another layer.
5. The method of claim 4, wherein the second source precursor is a
same material as the first source precursor, and the second
reactant precursor is a same material as the first reactant
precursor.
6. The method of claim 1, wherein the source precursor is one
selected from a group consisting of SiH.sub.4, TiCl.sub.4,
SiCl.sub.2H.sub.2, HfCl.sub.4, WF.sub.6, and metal-organic
compounds.
7. The method of claim 1, wherein the source precursor is one
selected from a group consisting of SiH.sub.4, TiCl.sub.4,
SiCl.sub.2H.sub.2, HfCl.sub.4, WF.sub.6, and metal-organic
compounds.
8. The method of claim 1, wherein the radicals are generated at a
location remote from the substrate.
9. A method of performing chemical vapor deposition, comprising:
generating radicals of a gas or a mixture of gases; injecting the
generated radicals onto a surface of a substrate to increase a
number of nucleation sites on the substrate by placing the surface
of the substrate in a reactive state; injecting source precursor
into a reaction zone; generate radicals of reactant precursor by
generating plasma of the reactant precursor; injecting the
generated radicals into the reaction zone to cause reaction between
the generated radicals and the injected source precursor; and
moving the surface of the substrate injected with the generated
radicals into the reaction zone to deposit a layer on the surface
of the substrate.
10. The method of claim 9, wherein the source precursor is one
selected from a group consisting of SiH.sub.4, TiCl.sub.4,
SiCl.sub.2H.sub.2, HfCl.sub.4, WF.sub.6, and a metal-organic
compound.
11. The method of claim 10, wherein the metal-organic compound is
one selected from a group consisting of Trimethylaluminum
[(CH.sub.3).sub.3Al], Tris-dimethylaminosilane
[(CH.sub.3).sub.2NSiH], and Tetrakis(ethylmethylamino)silicon
[{(CH.sub.3)(C.sub.2H.sub.5)N}.sub.4Si].
12. The method of claim 9, wherein the generated radicals comprise
N* and the deposited layer comprises SiN.
13. The method of claim 9, wherein the gas or mixture of gases
comprise inert gas.
14. The method of claim 13, wherein the inert gas is Argon.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of U.S.
patent application Ser. No. 13/397,590 filed on Feb. 15, 2012,
which claims priority under 35 U.S.C. .sctn.119(e) to U.S.
Provisional Patent Application No. 61/444,651 filed on Feb. 18,
2011 and U.S. Provisional Patent Application No. 61/511,333 filed
on Jul. 25, 2011, which are incorporated by reference herein in
their entirety.
BACKGROUND
[0002] 1. Field of Art
[0003] The disclosure relates to depositing one or more layers of
materials on a substrate by using radicals generated by a remote
plasma device.
[0004] 2. Description of the Related Art
[0005] Various chemical processes are used to deposit one or more
layers of material on a substrate. Such chemical processes include
chemical vapor deposition (CVD), atomic layer deposition (ALD) and
molecular layer deposition (MLD). CVD is the most common method for
depositing a layer of material on a substrate. In CVD, reactive gas
precursors are mixed and then delivered to a reaction chamber where
a layer of material is deposited after the mixed gas comes into
contact with the substrate.
[0006] ALD is another way of depositing material on a substrate.
ALD uses the bonding force of a chemisorbed molecule that is
different from the bonding force of a physisorbed molecule. In ALD,
source precursor is absorbed into the surface of a substrate and
then purged with an inert gas. As a result, physisorbed molecules
of the source precursor (bonded by the Van der Waals force) are
desorbed from the substrate. However, chemisorbed molecules of the
source precursor are covalently bonded, and hence, these molecules
are strongly adsorbed in the substrate and not desorbed from the
substrate. The chemisorbed molecules of the source precursor
(adsorbed on the substrate) react with and/or are replaced by
molecules of reactant precursor. Then, the excessive precursor or
physisorbed molecules are removed by injecting the purge gas and/or
pumping the chamber, obtaining a final atomic layer.
[0007] MLD is a thin film deposition method similar to ALD but in
MLD, molecules are deposited onto the substrate as a unit to form
polymeric films on a substrate. In MLD, a molecular fragment is
deposited during each reaction cycle. The precursors for MLD have
typically been homobifunctional reactants. MLD method is used
generally for growing organic polymers such as polyamides on the
substrate. The precursors for MLD and ALD may also be used to grow
hybrid organic-inorganic polymers such as Alucone (i.e., aluminum
alkoxide polymer having carbon-containing backbones obtained by
reacting trimethylaluminum (TMA: Al(CH.sub.3).sub.3) and ethylene
glycol) or Zircone (hybrid organic-inorganic systems based on the
reaction between zirconium precursor (such as zirconium t-butoxide
Zr[OC(CH.sub.3).sub.3)].sub.4, or tetrakis(dimethylamido)zieconium
Zr[N(CH.sub.3).sub.2].sub.4) with diol (such as ethylene
glycol)).
[0008] Each of these deposition processes are subject to various
limitations. Such limitations include, for example, (i) the
deposition rate, (ii) restrictions on the precursor materials that
can be used, and (iii) inconstancies in the deposited layer.
SUMMARY
[0009] Embodiments relate to performing molecular layer deposition
using radicals to place the deposited layer in a reactive state to
perform a subsequent deposition process. A first source precursor
including a compound (e.g., metal-organic compound) is injected
onto a substrate. A reactant precursor including an organic
compound is injected on the subject injected with the first source
precursor to deposit a layer on the substrate. Radicals of a gas or
a mixture of gases are generated and injected onto the substrate to
place the deposited layer in a reactive state.
[0010] In one embodiment, the substrate is injected with a second
source precursor where the deposited layer on the substrate is
placed in the reactive state before being injected with the second
source precursor. The absorption of the second source precursor on
the deposited layer is facilitated by an increased number of
nucleation sites on the deposited layer generated by placing the
deposited layer in the reactive state.
[0011] In one embodiment, a purge gas is injected onto the
substrate after injecting the first precursor and before injecting
the reactant precursor to remove physisorbed first source precursor
from the substrate.
[0012] In one embodiment, a physisorbed layer deposited on the
substrate is removed by the gas or the mixture of gases reverted to
an inactive state from the radicals.
[0013] In one embodiment, a first reactant precursor is injected
onto the substrate previously injected with the first source
precursor. Further, radicals of gas or a mixture of gases are
generated and injected onto the substrate previously injected with
the first reactant precursor. Processes may be repeated for a
predetermined number of times to deposit a hybrid organic-inorganic
polymer on the substrate.
[0014] In one embodiment, a second source precursor is injected
onto the substrate previously injected with the first reactant
precursor. Further, radicals of gas or a mixture of gases are
generated and injected onto the substrate previously injected with
the second source precursor. Processes may be repeated for a
predetermined number of times to deposit a hybrid organic-inorganic
polymer on the substrate.
[0015] In one embodiment, a second reactant precursor is injected
onto the substrate previously injected with the second source
precursor. Further, radicals of gas or a mixture of gases are
generated and injected onto the substrate previously injected with
the second reactant precursor. Processes may be repeated for a
predetermined number of times to deposit a hybrid organic-inorganic
polymer on the substrate.
[0016] In one embodiment, the first source precursor and the second
source precursor are metal-containing precursor such as
trimethylaluminum (TMA) or Hexamethyldisilazane
{(CH.sub.3).sub.3Si}.sub.2NH, the first reactant precursor is diol
(e.g., ethylene glycol), and the second reactant precursor is
aromatic hydrocarbon (e.g., as toluene and aniline).
[0017] In one embodiment, the first source precursor is TMA or
zirconium t-butoxide and the first reactant precursor is ethylene
glycol. The ethylene glycol reacts with the radicals and then TMA.
By reacting with the radicals, carbon links in the ethylene glycol
are broken up, facilitating subsequent reaction with TMA.
[0018] In one embodiment, the radicals are generated at a location
remote from the substrate by generating plasma. In this way, the
generate plasma does not negatively affect devices previously
formed on the substrate.
[0019] In one embodiment, the deposited layer is a hybrid
organic-inorganic layer. More specifically, the deposited layer is
polymeric atomic layer (e.g., alucone) where carbon atoms in a
plurality of molecules are cross-linked.
[0020] Embodiments also relate to a method of performing a
molecular layer deposition by injecting aromatic hydrocarbon as
source precursor onto a surface of a substrate, breaking
hydrocarbon rings on the surface of the substrate by injecting
radicals of inert gas onto the surface of the substrate. By
breaking the hydrocarbon rings, the surface of the substrate is
rendered reactive. The aromatic hydrocarbon may again be injected
onto the reactive surface. The process may be repeated to form a
polymeric layer on the substrate.
[0021] In one embodiment, purge gas is injected after injecting the
aromatic hydrocarbon on the surface of the substrate to remove
physisorbed aromatic hydrocarbon from the surface of the
substrate.
[0022] In one embodiment, physisorbed source precursor is removed
from the substrate by inert gas reverted from the radicals.
[0023] In one embodiment, the aromatic hydrocarbon is aromatic
hydrocarbon comprises one or more of toluene, aniline and
derivatives of benzene.
[0024] In one embodiment, the substrate moves below an injector
configured to inject the aromatic hydrocarbon and a radical reactor
configured to inject radicals of the inert gas.
[0025] In one embodiment, the radicals are generated at a location
remote from the surface of the substrate.
[0026] Embodiments also relate to a method of performing atomic
layer deposition (ALD) using radicals to disassociate reactant
precursor molecules. Radicals are generated and injected onto the
substrate. The radicals come into contact with the reactant
precursor molecules and disassociate the reactant precursor
molecules. The disassociated molecules are more easily absorbed on
the substrate compared to the inactive reactant precursor
molecules. A reactant precursor is injected onto the substrate with
the radicals to deposit a layer of material on the substrate.
[0027] In one embodiment, physisorbed source precursor are removed
from the substrate by inert gas reverted from the radicals.
[0028] In one embodiment, purge gas is injected onto the substrate
deposited with the layer to remove physisorbed material from the
substrate.
[0029] In one embodiment, the source precursor for the atomic layer
deposition may be one or more of SiH.sub.4, TiCl.sub.4,
SiCl.sub.2H.sub.2, AlCl.sub.3, WF.sub.6, Trimethylaluminum
[(CH.sub.3).sub.3Al], Tris(dimethylamino)silane
[(CH.sub.3).sub.2NSiH], and Tetrakis(ethylmethylamino)zirconium
[{(CH.sub.3)(C.sub.2H.sub.5)N}.sub.4Zr].
[0030] In one embodiment, the reactant precursor for the atomic
layer deposition may include NH.sub.3.
[0031] Embodiments also relate to a method of performing chemical
vapor deposition (CVD) using radicals. A source precursor is
injected into a reaction zone. Radicals or reactant precursor are
generated and injected into the reaction zone to cause reaction
between the generated radicals and the injected source precursor. A
portion of a substrate is moved into the reaction zone to deposit a
layer on the portion of the substrate.
[0032] In one embodiment, the source precursor for the chemical
vapor deposition includes one or more of SiH.sub.4, TiCl.sub.4,
SiCl.sub.2H.sub.2, AlCl.sub.3, WF.sub.6, and a metal-organic
compound. The metal organic compound may be one of
Trimethylaluminum [(CH.sub.3).sub.3Al], Tris(dimethylamino)silane
[{(CH.sub.3).sub.2N}.sub.3SiH], Tetrakis(ethylmethylamino)silicon
[{(CH.sub.3)(C.sub.2H.sub.5)N}.sub.4Si], and Hexamethyldisilazane
{(CH.sub.3).sub.3Si}.sub.2NH.
[0033] In one embodiment, the generated radicals for the chemical
vapor deposition includes N*.
[0034] In one embodiment, the deposited layer formed by the
chemical vapor deposition includes SiN. In one embodiment, the
source precursor is injected by a gas injector. The radicals are
generated by a radical reactor, and the reaction zone is a portion
shared by the gas injector and the radical reactor to discharge gas
or radicals from the gas injector and the radical reactor.
BRIEF DESCRIPTION OF DRAWINGS
[0035] Figure (FIG. 1 is a cross sectional diagram of a linear
deposition device, according to one embodiment.
[0036] FIG. 2 is a perspective view of a linear deposition device,
according to one embodiment.
[0037] FIG. 3 is a perspective view of a rotating deposition
device, according to one embodiment.
[0038] FIG. 4 is a perspective view of reactors in a deposition
device, according to one embodiment.
[0039] FIG. 5 is a cross sectional diagram illustrating the
reactors taken along line A-B of FIG. 4, according to one
embodiment.
[0040] FIGS. 6A through 6F are diagrams illustrating molecules
deposited on a substrate during a molecular layer deposition (MLD)
process, according to one embodiment.
[0041] FIGS. 6G through 6K are diagrams illustrating molecules
deposited on a substrate during a MLD process, according to another
embodiment.
[0042] FIG. 7A is a flowchart illustrating a process of performing
MLD, according to one embodiment.
[0043] FIG. 7B is a flowchart illustrating a process of performing
MLD, according to another embodiment.
[0044] FIG. 8 is a cross sectional diagram illustrating reactors
for performing enhanced atomic layer deposition (ALD), according to
one embodiment.
[0045] FIG. 9 is a flowchart illustrating a process of performing
enhanced ALD, according to one embodiment.
[0046] FIG. 10 is a flowchart illustrating a process of performing
chemical vapor deposition (CVD), according to one embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
[0047] Embodiments are described herein with reference to the
accompanying drawings. Principles disclosed herein may, however, be
embodied in many different forms and should not be construed as
being limited to the embodiments set forth herein. In the
description, details of well-known features and techniques may be
omitted to avoid unnecessarily obscuring the features of the
embodiments.
[0048] In the drawings, like reference numerals in the drawings
denote like elements. The shape, size and regions, and the like, of
the drawing may be exaggerated for clarity.
[0049] Embodiments relate to using radicals at different stages of
deposition processes. The radicals may be generated by applying
voltage across electrodes in a reactor remote from a substrate. The
radicals are injected onto the substrate at different stages of
molecular layer deposition (MLD), atomic layer deposition (ALD),
and chemical vapor deposition (CVD) to improve characteristics of
the deposited layer, enable depositing of material otherwise not
feasible and/or increase the rate of deposition. Gas used for
generating the radicals may include inert gas and other gases. The
radicals may disassociate precursors, activate the surface of a
deposited layer or generate cross-linking between deposited
molecules.
Example Apparatus for Performing Deposition
[0050] Figure (FIG. 1 is a cross sectional diagram of a linear
deposition device 100, according to one embodiment. FIG. 2 is a
perspective view of the linear deposition device 100 (without
chamber walls to facilitate explanation), according to one
embodiment. The linear deposition device 100 may include, among
other components, a support pillar 118, the process chamber 110 and
one or more reactors 136. The reactors 136 may include one or more
of injectors and radical reactors for performing MLD, ALD and/or
CVD. Each of the injectors injects source precursors, reactant
precursors, purge gases or a combination of these materials onto
the substrate 120. The gap between the injector and the substrate
120 may be 0.5 mm to 1.5 mm.
[0051] The process chamber enclosed by walls may be maintained in a
vacuum state to prevent contaminants from affecting the deposition
process. The process chamber 110 contains a susceptor 128 which
receives a substrate 120. The susceptor 128 is placed on a support
plate 124 for a sliding movement. The support plate 124 may include
a temperature controller (e.g., a heater or a cooler) to control
the temperature of the substrate 120. The linear deposition device
100 may also include lift pins (not shown) that facilitate loading
of the substrate 120 onto the susceptor 128 or dismounting of the
substrate 120 from the susceptor 128.
[0052] In one embodiment, the susceptor 128 is secured to brackets
210 that move across an extended bar 138 with screws formed
thereon. The brackets 210 have corresponding screws formed in their
holes receiving the extended bar 138. The extended bar 138 is
secured to a spindle of a motor 114, and hence, the extended bar
138 rotates as the spindle of the motor 114 rotates. The rotation
of the extended bar 138 causes the brackets 210 (and therefore the
susceptor 128) to make a linear movement on the support plate 124.
By controlling the speed and rotation direction of the motor 114,
the speed and the direction of the linear movement of the susceptor
128 can be controlled. The use of a motor 114 and the extended bar
138 is merely an example of a mechanism for moving the susceptor
128. Various other ways of moving the susceptor 128 (e.g., use of
gears and pinion or a linear motor at the bottom, top or side of
the susceptor 128). Moreover, instead of moving the susceptor 128,
the susceptor 128 may remain stationary and the reactors 136 may be
moved.
[0053] FIG. 3 is a perspective view of a rotating deposition device
300, according to one embodiment. Instead of using the linear
deposition device 100 of FIG. 1, the rotating deposition device 300
may be used to perform the deposition process according to another
embodiment. The rotating deposition device 300 may include, among
other components, reactors 320, 334, 364, 368, a susceptor 318, and
a container 324 enclosing these components. A reactor (e.g., 320)
of the rotating deposition device 300 corresponds to a reactor 136
of the linear deposition device 100, as described above with
reference to FIG. 1. The susceptor 318 secures the substrates 314
in place. The reactors 320, 334, 364, 368 may be placed with a gap
of 0.5 mm to 1.5 mm from the substrates 314 and the susceptor 318.
Either the susceptor 318 or the reactors 320, 334, 364, 368 rotate
to subject the substrates 314 to different processes.
[0054] One or more of the reactors 320, 334, 364, 368 are connected
to gas pipes (not shown) to provide source precursor, reactor
precursor, purge gas and/or other materials. The materials provided
by the gas pipes may be (i) injected onto the substrate 314
directly by the reactors 320, 334, 364, 368, (ii) after mixing in a
chamber inside the reactors 320, 334, 364, 368, or (iii) after
conversion into radicals by plasma generated within the reactors
320, 334, 364, 368. After the materials are injected onto the
substrate 314, the redundant materials may be exhausted through
outlets 330, 338. The interior of the rotating deposition device
300 may also be maintained in a vacuum state.
[0055] Although following example embodiments are described
primarily with reference to the reactors 136 in the linear
deposition device 100, the same principle and operation can be
applied to the rotating deposition device 300 or other types of
deposition device.
[0056] FIG. 4 is a perspective view of reactors 136A through 136D
(collectively referred to as the "reactors 136") in the deposition
device 100 of FIG. 1, according to one embodiment. In FIG. 4, the
reactors 136A through 136D are placed in tandem adjacent to each
other. In other embodiments, the reactors 136A through 136D may be
placed with a distance from each other. As the susceptor 128
mounting the substrate 120 moves from the left to the right, for
example, the substrate 120 is sequentially injected with materials
or radicals by the reactors 136A through 136D to form a deposition
layer on the substrate 120. Instead of moving the substrate 120,
the reactors 136A through 136D may move from the right to the left
while injecting the source precursor materials or the radicals on
the substrate 120.
[0057] In one or more embodiments, the reactors 136A, 136B, 136C
are gas injectors that inject precursor material, purge gas or a
combination thereof onto the substrate 120. Each of the reactors
136A, 136B, 136C is connected to pipes 412, 416, 420 to receive
precursors, purge gas or a combination thereof from sources (e.g.,
canisters). Valves and other pipes (refer to FIG. 5) may be
installed between the pipes 412, 416, 420 and the sources to
control the gas and the amount thereof provided to the gas
injectors 136A, 136B, 136C. Excess precursor and purge gas
molecules are exhausted via exhaust portions 440, 448.
[0058] The reactor 136D may be a radical reactor that generates
radicals of gas or a gas mixture received from one or more sources.
The radicals of gas or gas mixture may function as purge gas,
reactant precursor, surface treating agent, or a combination
thereof on the substrate 120. The gas or gas mixtures are injected
into the reactor 136D via pipe 428, and are converted into radicals
within the reactor 136D by applying voltage across electrodes
(e.g., electrode 422 and body of the reactor 136C) and generating
plasma within a plasma chamber. The electrode 422 is connected via
a line 432 to a supply voltage source and the body of the reactor
136, which forms a coaxial capacitive-type plasma reactor, is
grounded or connected to the supply voltage source via a conductive
line (not shown). The generated radicals are injected onto the
substrate 120, and remaining radicals and/or gas reverted to an
inactive state from the radicals are discharged from the reactor
136D via the exhaust portion 448. By exposing the substrate 120 to
the radicals, the surface of the substrate maintained reactive
until the next precursor is injected onto the surface of the
substrate.
[0059] FIG. 5 is a cross sectional diagram illustrating the
reactors 136A through 136D taken along line A-B of FIG. 4,
according to one embodiment. The injector 136A includes a body 502
formed with a gas channel 530, perforations (slits or holes) 532, a
reaction chamber 518, a constriction zone 534A, and part of an
exhaust portion 440. The gas channel 530 is connected to the pipe
412 to convey source precursor into the reaction chamber 518 via
the perforations 532. The region of the substrate 120 below the
reaction chamber 518 comes into contact with the source precursor
and absorbs source precursor molecules on its surface. The excess
source precursor (i.e., source precursor remaining after the source
precursor is absorbed on the substrate 120) passes through the
constriction zone 534A, and are discharged via the exhaust portion
440. The exhaust portion 440 is connected to an exhaust pipe (not
shown).
[0060] The pipe 412 (supplying gas to the injector 136A) is
connected to a valve V.sub.1A that controls supply of gas or
mixture of gases supplied via valves V.sub.2A and V.sub.3A. Each of
the valves V.sub.1B and V.sub.1C may be connected to a separate gas
source. The gas or mixture of gases may include carrier gas such as
Ar.
[0061] While the source precursor molecules pass the constriction
zones 534 physisorbed source precursor molecules are at least
partially removed from the region of the substrate 120 below the
constriction zone 534 due to higher flow rate of the source
precursor molecules and the carrier gas (e.g., Ar).
[0062] In one or more embodiments, the injector 136B injects purge
gas onto the substrate 120 to remove physisorbed source precursor
molecules from the substrate 120. By injecting purge gas onto the
substrate, only chemisorbed source precursor molecules remain on
the substrate 120. The injector 136B has a similar structure as the
injector 136A. That is, the injector 136B includes a body 506
formed with a gas channel 538, perforations (slits or holes) 542, a
reaction chamber 522, a constriction zone 534B, and part of the
exhaust portion 440. The gas channel 538 is connected to the pipe
416 to convey the purge gas into the reaction chamber 522 via the
perforations 542. The purge gas is injected onto the region of the
substrate 120 below the reaction chamber 522 and removes
physisorbed source precursor from the surface of the substrate 120.
The purge gas may be Argon or other inert gas. The purge gas and
the removed source precursor molecules are discharged via the
exhaust portion 440.
[0063] The pipe 416 (supplying gas to the injector 136B) is
connected to a valve V.sub.1B that controls supply of gas or
mixture of gases supplied via valves V.sub.2B and V.sub.3B. Each of
the valves V.sub.2B and V.sub.3B may be connected to a separate gas
source (e.g., a canister).
[0064] In one or more embodiments, the injector 136C injects
reactant precursor onto the substrate 120 to cause substitution of
the source precursor or reaction of the source precursor in the
substrate 120. The injector 136C has a similar structure as the
injector 136A. That is, the injector 136C includes a body 510
formed with a gas channel 544, perforations (slits or holes) 546, a
reaction chamber 526, a constriction zone 534C, and part of the
exhaust portion 448. The gas channel 544 is connected to the pipe
420 to convey the reactant precursor into the reaction chamber 526
via the perforations 546. The reactant precursor is injected onto
the region of the substrate 120 below the reaction chamber 526. The
excess reactant precursor is discharged via the exhaust portion
448.
[0065] The pipe 420 (supplying gas to the injector 136C) is
connected to a valve V.sub.1C that controls supply of gas or
mixture of gases supplied via valves V.sub.2C and V.sub.3C. Each of
the valves V.sub.2C and V.sub.3C may be connected to a separate gas
source (e.g., a canister).
[0066] The radical reactor 136D has a similar structure as the
injectors 136A, 136B, 136C except that the radical reactor 136D
further includes a plasma generator. The plasma generator includes
an inner electrode 422 and an outer electrode 548 surrounding a
plasma chamber 566 (the outer electrode 548 may be part of a
conductive body 514). The body 514 is formed with, among others, a
gas channel 562, perforations (slits or holes) 560, a plasma
chamber 566, an injector slit 568, a reaction chamber 530 and part
of the exhaust portion 448. A gas or a mixture of gases is injected
via the pipe 428, channel 562 and perforations 560 into the plasma
chamber 566. By applying a voltage difference between the inner
electrode 422 and the outer electrode 548, plasma is generated in
the plasma chamber 566. As a result of the plasma, radicals of the
gas or the mixture of gases are generated within the plasma chamber
566. The generated radicals are injected into the reaction chamber
530 via the injector slit 568. The region of the substrate 120
below the reaction chamber 526 comes into contact with the
radicals, and is thereby treated to have a reactive surface.
[0067] The plasma generator including the inner electrode 422, the
outer electrode 548 and the plasma chamber 566 are advantageously
located away from the substrate 120. By locating the plasma
generator away from the substrate 120, plasma generated by the
plasma generator does not affect or damage devices already formed
on the substrate 120. However, radicals generally have a limited
lifespan. Hence, if distance H of the plasma chamber 566 from the
substrate 120 is too large, most of the generated radicals revert
to an inactive state before reaching the substrate 120. Therefore,
distance H may be set to a value below a threshold. In one
embodiment, distance H is less than 8 cm.
[0068] In one embodiment, inert gas (e.g., Ar) is injected into the
radical reactor 136D alone or in combination with other gases. The
radicals react with the deposited layer and cause the surface of
the deposited layer to have a reactive surface, as described below
in detail with reference to FIGS. 6E and 6F. Some of the radicals
revert back to an inactive state and function as a purge gas,
removing excess reactant precursor molecules from the surface of
the substrate 120.
[0069] The pipe 428 (supplying gas to the radical reactor 136D) is
connected to a valve V.sub.1D that controls supply of gas or
mixture of gases supplied via valves V.sub.2D and V.sub.3D. Each of
the valves V.sub.2D and V.sub.3D may be connected to a gas
source.
[0070] The reactor modules 136A through 136D and their arrangement
as illustrated in FIG. 5 are merely illustrative. In other
embodiment, more than one radical reactor may be used. For example,
the injector 136B may be replaced with a radical reactor (similar
to the radical reactor 136D).
Example of Performing Molecule Layer Deposition
[0071] Molecular layer deposition (MLD) enables deposition of
hybrid organic-inorganic polymer on a substrate. Method of
performing MLD includes injecting source precursor or metal
molecules onto the substrate. Conventional method of performing MLD
results in a hybrid organic-inorganic polymer layer with lower
density, and generally needs nucleation sites on the substrate or
device to have source precursor molecules absorbed in the
substrate.
[0072] A conventional way of depositing a hybrid organic-inorganic
polymer on a substrate is, for example, by using Trimethylaluminium
(TMA) as the source precursor and ethylene glycol as the reactant
precursor. By depositing the substrate to the TMA, AlCH.sub.3 as
illustrated in FIG. 6A is formed on the substrate. Then ethylene
glycol is injected onto the substrate, forming a layer of a hybrid
organic-inorganic layer on the substrate, as illustrated in FIG.
6B. A stable hydroxide (OH) group is formed at the surface of the
deposited layer. The hydroxide group is not reactive, and hence,
the types of subsequent source precursor molecules that can be
subsequently deposited are limited. Moreover, the carbon atoms are
not cross-linked between the molecules in FIG. 6B, rendering the
deposited layer to have low strength and low melting
temperature.
[0073] Embodiments relate to performing radical bombardment on the
substrate previously deposited with a layer. By subjecting the
deposited layer of the substrate to the radicals, the deposited
layer can be placed in a reactive state where further precursor
molecules can be deposited in a subsequent process. Further,
embodiments relate to exposing either source precursor or reactant
precursor to the surface of the substrate previously exposed by
radicals or to cross-link molecules in the layer deposited on the
substrate. The resulting molecular layer may be used as a
replacement for organic layers that are used in high temperature or
layers that require low moisture permeability.
[0074] Taking an example of depositing a layer of alucone on the
substrate 120, the substrate 120 is injected with
Trimethylaluminium (TMA) as the source precursor and ethylene
glycol as the reactant precursor. Using the reactors as described
in FIGS. 4 and 5, the injector 136A injects the TMA onto the
substrate 120. The substrate 120 is moved to the right and then
injected with a purge gas (e.g., Argon) by the injector 136B to
remove physisorbed TMA from the surface of the substrate 120. FIG.
6A is a diagram illustrating AlCH.sub.3 absorbed on the surface of
the substrate 120 after injecting the purge gas by the injector
136B, according to one embodiment.
[0075] Then the ethylene glycol is injected onto the substrate by
the injector 136C. The ethylene glycol is injected into the
reaction chamber 526 and then exhausted via a constriction zone
534C and an exhaust zone 525 (connected to the exhaust portion
448).
[0076] The radical reactor 136D may be supplied with inert gas
(e.g., Argon) or a mixture of inert gas and other gases (e.g.,
H.sub.2) to generate the radicals. In one embodiment, the radical
reactor 136D generates H* radicals and Ar* radicals that are
injected onto the substrate 120. The mixture ratio of Ar and
H.sub.2 gas for generating the radicals may be in the range of 10:1
to 1:10. The radicals travel to the constriction zone 534C and the
exhaust zone 525, react with ethylene glycol and deposit a layer as
shown in FIGS. 6C and 6D. Specifically, the radicals break C--C
bonds in ethylene glycol, and enable the compound to combine with
AlCH.sub.3 formed on the substrate 120. As a result of combining
AlCH.sub.3 with ethylene glycol, the deposited layer has
cross-linking 616 between the molecules (see FIGS. 6C and 6D). The
cross-linking 616 enhances the characteristics (e.g., higher
strength and higher melting point) of the polymer layer due to
strong bonding between the molecules.
[0077] The substrate 120 is further moved to the right so that the
portion of the substrate 120 deposited with the layer of FIGS. 6C
and 6D is placed below the reaction chamber 530. As the substrate
120 is bombarded with Ar* radicals and/or H* radicals, the bonds
between carbon atoms and/or hydrogen atoms are broken, as shown in
FIGS. 6E and 6F. Therefore, the oxygen atoms 612 and broken bonds
of carbons become reactive, thereby facilitating absorption of or
linking with subsequent precursor molecules injected onto the
substrate 120. Due to the reactive oxygen atoms 612 and carbon
atoms, source precursor that otherwise does not react with the
deposited layer can now be deposited effectively in a subsequent
step, thereby increasing the deposition rate as well as increasing
the variety of materials that can be incorporated into an organic
polymer-metal interlaced structure.
[0078] For example, TMA may again be injected onto the substrate to
link Aluminum molecules to the oxygen atoms 612. Other metal or
chemical compounds may be deposited instead of Aluminum molecules.
The substrate 120 may then undergo subsequent steps (e.g.,
injection of purge gas, the reactant precursor, and then radicals)
to deposit another layer of hybrid polymer on the substrate 120.
The steps may be repeated to obtain a hybrid polymer layer of a
desired thickness.
[0079] In one embodiment, aromatic hydrocarbon precursors (e.g.,
mono-substituted benzene derivative including toluene and aniline)
may also be used as a reactant precursor for depositing a layer on
a substrate. These aromatic hydrocarbon precursors may
advantageously provide more cross-linking because of higher number
of carbon atoms and bonds. When aromatic hydrocarbon precursors are
used as the reactant precursor, the radicals break up the
hydrocarbon rings, generating a carbon group having no terminated
(or occupied) atoms. The carbon group facilitates absorption of
source precursor molecules subsequently injected onto the substrate
120. Due to the large number of potential carbon atoms without
terminated (or occupied) atoms created by breaking up of the
benzene ring, the number of nucleation sites on the deposited layer
for the attachment of subsequent source precursor molecules is
increased significantly.
[0080] FIG. 7A is a flowchart illustrating a process of performing
MLD, according to one embodiment. First source precursor molecules
(e.g., TMA molecules) are injected 706 onto the substrate 120 by
the injector 136A. The substrate is then moved below the injector
136B and then injected with purge gas to remove 710 excess source
precursor molecules (i.e., physisorbed source precursor molecules)
from the substrate 120. Then, the reactant precursor molecules
(e.g., ethylene glycol molecules) are injected 714 onto the
substrate 120 to deposit a hybrid organic-inorganic polymer layer
on the substrate 120. The reactant precursor molecules may react
with radicals and then the source precursor to form a layer of
molecular layer on the substrate 120.
[0081] Subsequently, plasma of gas is generated 718 in the radical
reactor 136C. The gas includes, among other gases, inert gas such
as Argon. The generated radicals are then injected 722 onto the
surface of the substrate 120 to place molecules in the deposited
layer in a reactive state for linking with subsequent material
injected onto the substrate 120. The radicals reverted to an
inactive state may function as a purge gas that removes physisorbed
reactant precursor molecules from the surface of the substrate
120.
[0082] It is then determined 730 whether the deposited layer is of
a desired thickness. If not, the process returns to injecting 706
the source precursor molecules onto the surface of the substrate
and repeats the subsequent processes. If the desired thickness of
deposited layer is obtained, the process terminates.
[0083] In another embodiment, nucleation sites are generated on the
substrate before performing the steps of FIG. 7A. First, TMA is
injected onto the substrate as the source precursor. Subsequently,
ethylene glycol is injected onto the substrate as the reactant
precursor to form a layer as illustrated in FIG. 6B. Then, the
substrate is injected with radicals (or active species) to convert
a stable hydroxide (OH) group into reactive oxygen group or carbon
group having no terminated (or occupied) atoms. The deposited
material with reactive oxygen and/or carbon atoms function as
nucleation sites onto which TMA and ethylene glycol can be injected
to form a hybrid organic-inorganic polymer layer.
[0084] The bonding between the interface of each monomer is strong,
and therefore, multiple layers of hybrid polymer formed by
embodiments have superior characteristics (e.g., higher melting
point and strength) compared to hybrid polymer formed by
conventional methods. Hence, the hybrid polymer formed according to
the embodiment may be used in high temperature. Further, the hybrid
polymer formed according to the embodiment may exhibit a higher
contact angle, meaning that the hybrid polymer is hydrophobic.
Therefore, the deposited hybrid polymer may be used as a layer for
preventing infiltration of moisture.
[0085] In another embodiment, aromatic hydrocarbon molecules may be
used as precursor in a MLD process to deposit polymer on the
substrate. The benzene ring of aromatic hydrocarbon (e.g., toluene
and aniline) absorbed on the substrate may be broken by radicals,
rendering the surface of the substrate to become reactive by have
carbon group with no terminated (or occupied) atoms. The same
aromatic hydrocarbon or another precursor material may be injected
onto the reactive surface to form a organic or hybrid polymer on
the substrate. In the following example, toluene is used as the
source precursor but a different aromatic hydrocarbon may be used
to deposit polymer on the substrate.
[0086] FIGS. 6G through 6K are diagrams illustrating depositing of
a polymeric layer using toluene as source precursor of an MLD
process, according to one embodiment. FIG. 7B is a flowchart
illustrating the process of depositing the polymeric layer,
according to one embodiment. As shown in FIG. 6B, a substrate 120
with a hydroxylated surface is provided. The substrate with the
hydroxylated surface moves from the left to the right as shown in
FIG. 5. First, the substrate with the hydroxylated surface is
injected with purge gas (e.g., Ar gas) by the first injector 136A
to remove any excess molecules remaining on the substrate.
[0087] Then the substrate 120 moves to the right in FIG. 5 and is
injected 740 with aromatic hydrocarbon (e.g., mono-substituted
benzene derivatives including toluene and aniline, and derivatives
of benzene) or aliphatic compound containing single hydroxyl groups
or single amine groups by the injector 136B. As a result,
by-product CH.sub.4 and a layer of material as shown in FIG. 6H is
deposited on the substrate 120. The substrate 120 with toluene
absorbed on its surface as illustrated in FIG. 6H is stable and no
further chemical absorption is likely to occur unless the surface
is rendered reactive.
[0088] The substrate 120 may then be injected 744 with a purge gas
(e.g., Ar gas) by the injector 136C to remove any physisorbed
toluene from the surface of the substrate 120. Subsequently, the
radical reactor 136D generates 748 and injects 752 radicals of
inert gas (e.g., Ar*) onto the surface of the substrate as reactant
precursor. The radicals break the hydrocarbon rings of the material
absorbed on the substrate, and causes the surface to have a monomer
molecular layer and become reactive due to carbon group with no
terminated (or occupied) atoms as illustrated in FIG. 6I.
[0089] It is then determined if the thickness of the layer
deposited on the substrate 120 is of a desired thickness 758. If
the thickness is sufficient, the process terminates. However, if
the thickness is insufficient, the substrate 120 reverts to its
original location and is again injected with the purge gas by the
injector 136A to remove any redundant material from the surface of
the substrate 120. Subsequently, the injector 136B again injects
744 toluene molecules onto the substrate as the substrate moves to
the right as shown in FIG. 5. As a result, toluene molecules are
attached to the monomer molecular layer as illustrated in FIG. 6J.
The injector 136C injects purge gas to remove 744 the redundant
toluene molecules from the surface of the substrate 120.
[0090] Subsequently, the radicals are again injected 748 onto the
substrate by the radical reactor 136D to break hydrocarbon rings of
the absorbed toluene molecules, creating a polymeric layer on the
substrate 120 as illustrated in FIG. 6K. The process may be
repeated for a number of times to deposit a polymer of a desired
thickness.
[0091] In other embodiment, a different aromatic hydrocarbon or
material may be used as the source precursor at one or more
iteration of the process to deposit a hybrid polymer instead of
injecting the same aromatic hydrocarbon as the source
precursor.
Enhanced Atomic Layer Deposition Using Radicals
[0092] Embodiments relate to an enhanced ALD process where source
precursor molecules are exposed to radicals of inert gas to
disassociate the source precursor molecules before or after
exposing a substrate to the source precursor molecules. By
disassociating the source precursor molecules, the source precursor
molecules are activated into a high energy state, which facilitates
the absorption of the source precursor molecules onto the surface
of the substrate. The radicals may then revert to an inactive
state. The reverted inert gas also functions as a purge gas that
removes physisorbed source precursor molecules from the surface of
the substrate, obviating the need for a separate purge process.
[0093] FIG. 8 is a cross sectional diagram illustrating reactors
for performing enhanced atomic layer deposition (ALD), according to
one embodiment. The reactor includes an injectors 136A, 136G and
radical reactors 136E, 136F. The injector 136A, 136G inject
material onto the surface of the substrate 120. The radical
reactors generate plasma for generating radicals injected onto the
surface of the substrate 120. In one embodiment, the injectors
136A, 136G and the radical reactors 136E, 136F are arranged so that
the substrate 120 is exposed to the material injected by the
injector 136A, then exposed to the radicals generated by the
radical reactors 136E, 136F and then finally to the material
injected by the injector 136G.
[0094] The injector 136A is connected to a pipe 412 for receiving
gas passing through valves V.sub.1A, V.sub.2A and V.sub.3A. The
structure of injector 136A of FIG. 8 is the same as the structure
of injector 136A described above with reference to FIG. 5, and
therefore, the explanation thereof is omitted herein for the sake
of brevity.
[0095] In one embodiment, source precursor gas is injected onto the
substrate 120 by the injector 136A. The source precursor gas for
enhanced ALD may include, among other precursors, inorganic
compounds such as SiH4, TiCl4, SiCl2H2, HfCl4, WF6, and
metal-organic compounds such as Tris-dimethylaminosilane
[(CH.sub.3).sub.2NSiH], and Tetrakis(ethylmethylamino)silicon
[{(CH.sub.3)(C.sub.2H.sub.5)N}.sub.4Si]. These inorganic compounds
and organic compounds are not easily absorbed into a substrate, and
hence, generally results in a slow deposition rate and a layer with
poor properties.
[0096] The radical reactor 136E generates radicals of gas or a gas
mixture received from one or more sources. The gas or gas mixture
injected into the radical reactor 136E include inert gas (e.g.,
Argon). The structure of the radical reactor 136E is substantially
identical to the structure of radical reactor 136D described above
with reference to FIG. 5, and therefore, the detailed description
thereof is omitted herein for the sake of brevity. The gas or gas
mixtures are injected into the radical reactor 136E via valves
V.sub.1E, V.sub.2E, V.sub.3E, and are converted into radicals
within the radical reactor 136E by applying voltage across an inner
electrode 826 and a conductive body 810. The radicals generated in
the radical reactor 136E are injected onto the substrate 120, and
remaining radicals and/or gas reverted to inactive state are
discharged from the radical reactors 136E, 136F via exhaust
portions 811, 812.
[0097] By exposing the source precursor molecules to the radicals
generated by the radical reactor 136E, the source precursor
molecules are disassociated. The disassociation of the source
precursor molecules is advantageous since the disassociated source
precursor molecules can be absorbed onto the surface of the
substrate 120 more easily, resulting in increase in the deposition
rate.
[0098] After the radicals disassociate the source precursors on the
surface of the substrate 120, the radicals revert to an inert
state. The reverted purge gas passes through the constriction zone
834, performing the purge operation of removing excess source
precursor molecules from the surface of the substrate 120.
[0099] In one embodiment, as the substrate 120 moves to the right
side, the radical reactor 136F injects reactant precursor onto the
substrate 150. The radical reactor 136F has a similar structure as
the radical reactor 136E but uses a different gas. The radical
reactor 136F may include, among other components, an inner
electrode 844 and an outer electrode 850 (implemented as a body 814
of the radical reactor 136F). The radicals react with the source
precursor molecules absorbed in the substrate 120 or replace the
source precursor molecules to form a layer.
[0100] In one embodiment, the radical reactor 136F produces N*
radical (for example, using NH.sub.3 as the reactant precursor). As
a result of reaction with the source precursor molecules or
replacement of the source precursor molecules, a SiN is formed on
the substrate 120.
[0101] Excess radicals or gas reverted from the radicals are
discharged via an exhaust portion 812.
[0102] The injector 136G has a channel 862 and holes or slit 864
for conveying the purge gas to a reaction chamber 842. Purge gas is
injected into the injector 136G via the channel 862 and holes or
slit 864. As the purge gas moves into the reaction chamber 842 and
then through a constriction zone 836, the purge gas removes the
excess reactant precursor from the substrate 120. The purge gas is
the discharged via the exhaust portion 812.
[0103] FIG. 9 is a flowchart illustrating a process of performing
enhanced ALD, according to one embodiment. The injector 136A
injects 906 source precursor molecules onto the surface of
substrate 120.
[0104] Plasma of inert gas (e.g., Ar) is generated 910 by the
radical reactor 136E. The radicals generated are injected 914 onto
the surface of the surface previously exposed to the source
precursor molecules. The radicals disassociate the source precursor
molecules and facilitate absorption of the dissociated molecules in
the substrate 120. At least part of the radicals revert to an inert
state and removes 918 excess source precursor molecules from the
substrate 120.
[0105] The reactant precursor molecules are then injected 922 by
the radical reactor 136F onto the surface of the substrate 120. The
injector 136G removes 924 excess reactant precursor molecules by
injecting purge gas onto the surface of the substrate 120.
[0106] If it is determined 928 that the thickness of deposited
layer is not sufficient or a predetermined number of repetition has
not yet been reached, then the process returns to injecting 906 the
source precursor molecules onto the surface of the substrate and
repeats the subsequent steps. Conversely, if it is determined 928
that the thickness of deposited layer is sufficient or a
predetermined number of predetermined iteration has been reached,
the process terminates.
[0107] The source precursors, the reactant precursors and the layer
deposited on the substrate are merely examples. Various other
source precursors may be disassociated by using the radicals of
inert gas. Further, layers other than SiN may be formed on the
substrate.
Enhanced Chemical Vapor Deposition Using Radicals
[0108] The same principle is not limited to ALD but can also be
applied to chemical vapor deposition (CVD). CVD differs from ALD in
that the precursors are created by mixing materials at a location
away from the substrate (not on the substrate) and then exposing
the substrate to the precursors. The injector 136A and the radical
reactor 136E of FIG. 8 may be used for performing CVD on the
substrate 120 (the radical reactors 136F and the injector 136G are
not used in this example).
[0109] To perform CVD, the source precursor is injected into the
injector 136A, passes through the reaction chamber 518 and the
constriction zone 832 into the exhaust portion 811. The source
precursor may include inorganic compounds such as SiH.sub.4,
TiCl.sub.4, SiCl.sub.2H.sub.2, HfCl.sub.4, WF.sub.6, and
metal-organic compounds such as Trimethylaluminum
[(CH.sub.3).sub.3Al], Tris-dimethylaminosilane
[(CH.sub.3).sub.2NSiH], and Tetrakis(ethylmethylamino)silicon
[{(CH.sub.3)(C.sub.2H.sub.5)N}.sub.4Si].
[0110] Reactant precursor (e.g., O.sub.2, O.sub.3, H.sub.2O,
N.sub.2, NH.sub.3, N.sub.2O, H.sub.2 and CH.sub.4) is injected into
the remote plasma generator 136E. The radicals (e.g., O* radicals,
N* radicals, C* radicals and H* radicals) of the reactant precursor
are generated at the radical reactor 136E by applying voltage
across the electrode 826 and the body 810. The generated radicals
then enter the constriction zone 834 and then discharge via the
exhaust portion 811. The radicals and the source precursor
materials interact in the exhaust portion 811 and deposit a layer
(e.g., SiON and AlON) on the substrate 120 in the exhaust portion
811.
[0111] FIG. 10 is a flowchart illustrating a process of performing
chemical vapor deposition (CVD), according to one embodiment.
First, source precursor molecules are injected 1000 into a reacting
zone (e.g., exhaust portion 811) by the injector 136A. The radical
reactor 136E generates 1010 plasma of reactant precursor. The
radicals generated at the radical reactor 136E are then injected
1014 into the reacting zone. The radicals of the reactant precursor
molecules and the source precursor molecules react in the reacting
zone. As the substrate moves 518 moves into the reacting zone, a
layer of material is deposited on the substrate.
[0112] The enhanced CVD process may be iterated for a number of
passes through the reactors to obtain a deposit layer of a desired
thickness.
[0113] Note that either in the ALD or CVD processes described, the
radicals are generated at a location (specifically, within the
plasma chamber) that is located away from the substrate. The plasma
for generating the radicals does not interact with the substrate,
and hence, the plasma does not damage the substrate or any device
formed on the substrate.
[0114] Although the present invention has been described above with
respect to several embodiments, various modifications can be made
within the scope of the present invention. Accordingly, the
disclosure of the present invention is intended to be illustrative,
but not limiting, of the scope of the invention, which is set forth
in the following claims.
* * * * *