U.S. patent application number 16/433990 was filed with the patent office on 2019-12-12 for enhanced anodization for processing equipment.
The applicant listed for this patent is Applied Materials Inc.. Invention is credited to Cheng-Hsuan CHOU, David FENWICK, Xiao-Ming HE, Chidambara A. RAMALINGAM, Michael R. RICE, Jennifer Y. SUN, Xiaowei WU.
Application Number | 20190376202 16/433990 |
Document ID | / |
Family ID | 68764674 |
Filed Date | 2019-12-12 |
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United States Patent
Application |
20190376202 |
Kind Code |
A1 |
HE; Xiao-Ming ; et
al. |
December 12, 2019 |
ENHANCED ANODIZATION FOR PROCESSING EQUIPMENT
Abstract
An enhanced anodization method includes forming a porous
anodization layer comprising columns of anodization layer material
with pores between adjacent columns. The method further includes
sealing the porous layer by forming a sealing layer at a top of the
porous layer. The sealing layer may be formed by using a hybrid
sealing process that combines, in any order, two or more of
de-ionized (DI) water seal, Ni sealing, and, PTFE sealing.
Alternatively, the sealing layer is formed by conformally coating
the columns in the porous layer with one or more layers of a
coating material. Further, the coating material may be
surface-fluorinated to improve plasma resistance.
Inventors: |
HE; Xiao-Ming; (Fremont,
CA) ; SUN; Jennifer Y.; (Mountain View, CA) ;
FENWICK; David; (Los Altos, CA) ; CHOU;
Cheng-Hsuan; (Santa Clara, CA) ; WU; Xiaowei;
(San Jose, CA) ; RAMALINGAM; Chidambara A.;
(Fremont, CA) ; RICE; Michael R.; (Pleasanton,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
68764674 |
Appl. No.: |
16/433990 |
Filed: |
June 6, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62683379 |
Jun 11, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 11/18 20130101;
C25D 11/06 20130101; C25D 11/20 20130101; C25D 11/246 20130101 |
International
Class: |
C25D 11/24 20060101
C25D011/24; C25D 11/20 20060101 C25D011/20 |
Claims
1. A method of manufacturing a chamber component for a processing
chamber, the method comprising: providing a metallic article,
wherein the metallic article is a part of the chamber component;
anodizing the metallic article by forming an anodization layer on
the metallic article, wherein the anodization layer comprises a
barrier layer adjacent to an external surface of the metallic
article and a porous layer on top of the barrier layer, the porous
layer comprising columns of anodization layer material with pores
between adjacent columns; and sealing the porous layer by forming a
sealing layer at a top of the porous layer, wherein the sealing
layer is formed using a hybrid sealing process that comprises
combining, in any order, two or more of the following sealing
processes: a first sealing process comprising sealing with
de-ionized (DI) water steam; a second sealing process comprising
sealing with nickel plating; and a third sealing process comprising
sealing with polytetrafluoroethylene (PTFE).
2. The method of claim 1, wherein the first sealing process forms
hydrated metallic oxide.
3. The method of claim 1, wherein performing the second sealing
process comprises immersing the metallic article in a nickel
acetate solution.
4. The method of claim 1, wherein performing the third sealing
process comprises spraying, dipping or brushing a thermosetting
resin containing PTFE onto the anodized metallic article.
5. A method of manufacturing a chamber component for a processing
chamber, the method comprising: providing a metallic article,
wherein the metallic article is a part of the chamber component;
anodizing the metallic article by forming an anodization layer on
the metallic article, wherein the anodization layer comprises a
barrier layer adjacent to an external surface of the metallic
article and a porous layer on top of the barrier layer, the porous
layer comprising columns of anodization layer material with pores
between adjacent columns; and sealing the porous layer by forming a
sealing layer at a top of the porous layer, wherein the sealing
layer is formed by conformally coating the columns in the porous
layer with one or more layers of a coating material.
6. The method of claim 5, wherein sealing the porous layer further
comprises: annealing the one or more layers of the coating material
to form a surface alloy of the coating material.
7. The method of claim 5, wherein the one or more layers of the
coating material are deposited using one or more of the following
processes: atomic layer deposition (ALD), physical vapor deposition
(PVD), chemical vapor deposition (CVD), plasma enhanced chemical
vapor deposition (PECVD), plasma enhanced physical vapor deposition
(PEPVD), and wet chemical deposition.
8. The method of claim 7, wherein a thickness of the sealing layer
is selected such that the one or more layers of the coating
material fully fill the pores between adjacent columns.
9. The method of claim 7, wherein a thickness of the sealing layer
is selected such that the one or more layers of the coating
material partially fill the pores between adjacent columns.
10. The method of claim 9, wherein a pore size for the pores
between the coated columns of the porous layer is in the range of
5-60 nm.
11. The method of claim 5, wherein the coating material comprises
an oxide, the method further comprising: conducting in-situ
fluorination to replace at least a portion of oxygen molecules of
the oxide with fluorine molecules and convert at least a surface of
the coating from the oxide into a fluoride or an oxy-fluoride.
12. The method of claim 11, wherein the coating material is
Al.sub.2O.sub.3 or Y.sub.2O.sub.3, and the surface of the coating
is converted to AlF.sub.3/AlOF or YF.sub.3/YOF after in-situ
fluorination.
13. The method of claim 12, wherein performing the in-situ
fluorination comprises: immersing the article in a mixed acid
solution containing HF, NH.sub.4F, and H.sub.2O.sub.2 in
predetermined volumetric ratio.
14. The method of claim 12, wherein performing the in-situ
fluorination comprises: irradiating the article with a
fluorine-containing plasma.
15. A chamber component for a processing chamber, comprising: a
metallic article that is a part of the chamber component; an
anodization layer formed on the metallic article, wherein the
anodization layer comprises a barrier layer adjacent to an external
surface of the metallic article and a porous layer on top of the
barrier layer, the porous layer comprising columns of anodization
layer material with pores between adjacent columns; and a hybrid
sealing layer formed at a top of the porous layer, wherein the
hybrid sealing layer comprises, in any order, two or more of the
following layers: a hydrated metallic oxide layer; a plated nickel
layer; and a polytetrafluoroethylene (PTFE) layer.
16. A chamber component for a processing chamber, comprising: a
metallic article that is a part of the chamber component; an
anodization layer formed on the metallic article, wherein the
anodization layer comprises a barrier layer adjacent to an external
surface of the metallic article and a porous layer on top of the
barrier layer, the porous layer comprising columns of anodization
layer material with pores between adjacent columns; and a sealing
layer formed at a top of the porous layer, wherein the sealing
layer comprises one or more layers of a coating material
conformally deposited onto the columns in the porous layer.
17. The chamber component of claim 16, wherein the thickness of the
sealing layer is selected such that the one or more layers of the
coating material fully fill the pores between adjacent columns.
18. The chamber component of claim 16, wherein the thickness of the
sealing layer is selected such that the one or more layers of the
coating material partially fill the pores between adjacent
columns.
19. The chamber component of claim 17, wherein a pore size for the
pores between the coated columns of the porous layer is in the
range of 5-60 nm.
20. The chamber component of claim 16, wherein the sealing layer
further comprises: a fluorinated outer surface layer over the one
or more layers of the coating material.
Description
RELATED APPLICATION
[0001] This application is related to and claims the benefit of
U.S. Provisional Patent Application No. 62/683,379, filed on Jun.
11, 2018, the entirety of which is incorporated herein by
reference.
TECHNICAL FIELD
[0002] Embodiments of the present disclosure relate, in general, to
anodized metallic articles and to a process for applying a sealing
layer to an anodized article.
BACKGROUND
[0003] In the semiconductor industry, devices are fabricated by a
number of manufacturing processes producing structures of an
ever-decreasing size. Some manufacturing processes such as plasma
etch may generate particles and metal contamination from the
processing chamber that adversely affect a substrate that is being
processed, contributing to device defects. As device geometries
shrink, susceptibility to these defects increases, and particle and
metal contamination requirements become more stringent.
Accordingly, as device geometries shrink, allowable levels of
particle defects and metal contamination may be reduced
significantly. Degradation of processing chamber components may
also destabilize the plasma within the processing chamber.
Therefore, plasma resistant chamber components are
advantageous.
SUMMARY
[0004] Methods of manufacturing a chamber component for a
processing chamber using an enhanced anodization processes are
disclosed. The processing chamber may be used inside a plasma
generator source (including a remote plasma source (RPS)) and/or
other chambers used for plasma etching or other processes. An
anodization process is enhanced by combining anodization with
innovating sealing techniques. An enhanced anodization method
includes first anodizing a metallic article by forming an
anodization layer on the metallic article. The metallic article may
be a chamber component or a part of a chamber component. The
anodization layer comprises a barrier layer adjacent to an external
surface of the metallic article and a porous anodization layer on
top of the barrier layer. The porous anodization layer comprises
columns of anodization layer material with pores between adjacent
columns. The method further includes sealing the porous anodization
layer by forming a sealing layer at a top of the porous anodization
layer.
[0005] In one embodiment, the sealing layer is formed using a
hybrid sealing process that comprises combining, in any order, two
or more different sealing processes. The sealing processes include
sealing with de-ionized (DI) water steam, sealing with nickel
plating, and sealing with polytetrafluoroethylene (PTFE).
[0006] In another embodiment, the sealing layer is formed by
conformally coating the columns in the porous anodization layer
with one or more layers of a coating material. The coating material
may be an oxide. In-situ fluorination may be conducted to replace
at least a portion of oxygen molecules of the oxide with fluorine
molecules and convert at least a surface of the conformal coating
from the oxide into a fluoride or an oxy-fluoride.
[0007] Also disclosed is a chamber component for a processing
chamber, the chamber component having a metallic article that is
anodized and sealed according to the methods disclosed here.
[0008] The thickness of the sealing layer is selected such that the
one or more layers of the coating material fully or partially fill
the pores between adjacent columns. When partially filled, a pore
size for the pores between the coated columns of the porous layer
may be in the range of 5-60 nm.
[0009] The resulting anodized and sealed metallic articles show
superior stability against plasma erosion as compared to metallic
articles manufactured using conventional anodization and sealing
techniques. Additionally, the resulting anodized and sealed
metallic articles have been shown to introduce minimal
contamination to semiconductor wafers being processed in a
processing chamber that contains the metallic articles that have
been anodized and sealed in accordance with embodiments of the
present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present disclosure is illustrated by way of example, and
not by way of limitation, in the figures of the accompanying
drawings in which like references indicate similar elements. It
should be noted that different references to "an" or "one"
embodiment in this disclosure are not necessarily to the same
embodiment, and such references mean at least one.
[0011] FIG. 1A illustrates an anodized chamber component for use in
a semiconductor manufacturing chamber, in accordance with one
embodiment of the present disclosure.
[0012] FIG. 1B illustrates an anodized and hybridly sealed chamber
component for use in a semiconductor manufacturing chamber, in
accordance with one embodiment of the present disclosure.
[0013] FIG. 1C illustrates an anodized and hybridly sealed chamber
component for use in a semiconductor manufacturing chamber, in
accordance with another embodiment of the present disclosure.
[0014] FIG. 2 illustrates an exemplary architecture of a
manufacturing system, in accordance with one embodiment of the
present disclosure.
[0015] FIG. 3A illustrates a schematic cross-sectional side view of
an anodized article where the sealing layer completely fills the
pores, in accordance with embodiments of the present
disclosure.
[0016] FIG. 3B illustrates a schematic cross-sectional side view of
an anodized article where the sealing layer partially fills the
pores, in accordance with embodiments of the present
disclosure.
[0017] FIG. 4A illustrates a schematic cross-sectional side view of
an anodized article showing a fluorinated outer surface of the
sealing layer that completely fills the pores, in accordance with
embodiments of the present disclosure.
[0018] FIG. 4B illustrates a schematic cross-sectional side view of
an anodized article showing a fluorinated outer surface of the
sealing layer that partially fills the pores, in accordance with
embodiments of the present disclosure.
[0019] FIG. 5 is a flow chart showing a process for manufacturing
an anodized and sealed article, in accordance with embodiments of
the present disclosure.
[0020] FIG. 6 is a flow chart showing a process for manufacturing
an anodized article where the anodization layer is coated with one
or more sealing layers of a coating material, in accordance with
embodiments of the present disclosure.
[0021] FIG. 7 shows a properties associated with various hybrid
sealing and advanced coating and sealing processes in a tabular
format, in accordance with embodiments of the present
disclosure.
[0022] FIG. 8 illustrates impedance enhancement results
corresponding to various hybrid sealing and advanced coating and
sealing processes.
DETAILED DESCRIPTION OF EMBODIMENTS
[0023] Embodiments of the disclosure are directed to a process for
anodizing an article (e.g., a component of a processing chamber for
use in semiconductor manufacturing) to form a porous anodization
layer and sealing the porous anodization layer fully or partially.
Embodiments are additionally directed to an article created using
an enhanced anodization and sealing process. For example, the
article may be a showerhead, a heater, a cathode sleeve, a sleeve
liner door, a cathode base, a chamber liner, an electrostatic chuck
base, etc. of a chamber for processing equipment such as an etcher,
a cleaner, a furnace, and so forth. For another example, the
article may be a block-like chamber that contains the cylinder
channel conducting the plasma flowing inside a plasma generation
source, such as inside RPS. In one embodiment, the chamber is for a
plasma etcher or plasma cleaner. In one embodiment, these articles
can be formed of an aluminum alloy (e.g., Al 6061), another alloy,
a metal, a metal oxide, or any other suitable material (e.g., a
conductive material).
[0024] Due to impurities in the metals used to manufacture
semiconductor chamber components (e.g., Al 6061), these components
may not meet some semiconductor manufacturing specifications. For
example, metal contamination specifications for device nodes having
sizes of less than 90 nm may be stringent. These impurities can
leach out of typical coated or anodized articles during plasma
processing of a wafer and increase contamination levels. An
anodization layer may have a porous outer layer comprising high
aspect ratio columns. The porous layer may be sealed at the top.
According to embodiments, parameters and/or techniques for
anodization of these components (e.g., a thickness of an
anodization layer) as well as for sealing a produced anodization
layer may be optimized to reduce metal contamination from the
article. Performance properties of the article may include a
relatively long lifespan (as compared to other articles that have
undergone a traditional anodization process and a traditional
sealing process), and a low on-wafer metal contamination, according
to embodiments.
[0025] Embodiments described herein may cause reduced on wafer
metal contamination when used in a process chamber for plasma rich
processes. However, it should be understood that the anodized and
sealed articles discussed herein may also provide reduced metal
contamination when used in process chambers for other processes
such as non-plasma etchers, non-plasma cleaners, chemical vapor
deposition (CVD) chambers, physical vapor deposition (PVD)
chambers, selective removal process (SRP) chambers, and so
forth.
[0026] Though anodization is used to maintain the process
stability, the anodization surface often induces particles and
metal contamination while the anodization parts are irradiated
using fluorine or chlorine-containing plasma. Quality of
anodization becomes worse with an increase in ion bombardment
energy. The porous columnar portion of the anodized surface usually
has some micro-cracks. Plasma erosion roughens the anodized surface
and enlarges the cracks, shortening the anodized part's service
life and introducing particle and metal contamination in the plasma
process. The present disclosure improves the anodization process by
creating a smooth and dense anodization surface with reduced
micro-cracks. This improvement is enabled by modifying the
anodization process with hybrid sealing and coating processes,
leading to enhancing the plasma erosion resistance and reducing
particle contamination.
[0027] FIG. 1A illustrates a cross-sectional view of a chamber
component 100A for use in a manufacturing chamber (e.g., in a
semiconductor manufacturing chamber), in accordance with one
embodiment of the present disclosure. The chamber component 100
includes an article 102 and an anodization layer 103 on the
article. The anodization layer 103 comprises a buffer layer 104 and
a porous layer 106 comprising vertical columns 110 of the
anodization layer material with pores 112 of diameter D in between
the columns 110. The chamber component 100A is shown for
representational purposes and is not necessarily to scale.
[0028] The article 102 may be manufactured of an aluminum alloy
(e.g., 6061 Al). However, the article 102 can also be formed of any
other suitable material, such as other metals or metal alloys.
Examples of other suitable materials include, but are not limited
to, stainless steel, titanium, titanium alloy, yttrium, yttrium
alloy, magnesium, magnesium alloy etc. According to embodiments,
the article 102 can be a showerhead, a cathode sleeve, a sleeve
liner door, a cathode base, a chamber liner, an electrostatic chuck
base, etc. of a chamber for processing equipment such as an etcher,
a cleaner, a furnace, and so forth. According to embodiments, the
article 102 can be the block with the cylinder channel conducting
the plasma flowing inside the plasma generation source, such as
inside the RPS.
[0029] The article 102 is anodized to form the anodization layer
103 on a surface of the article 102, where pores 112 are formed
between anodization columns 110. The anodization layer may be an
oxide, such as Al.sub.2O.sub.3, Y.sub.2O.sub.3, etc. For example,
if the article 102 is aluminum or an aluminum alloy, then the
anodization layer may be Al.sub.2O.sub.3. If the article 102 is
yttrium or a yttrium alloy, then the anodization layer may be
Y.sub.2O.sub.3. If the article is magnesium or a magnesium alloy,
then the anodization layer may be MgO. The anodization layer 103
can be formed to have a certain thickness. In embodiments, the
thickness of the anodization layer may be 0.2-75 um, and mostly
25-75.mu.m. In embodiments, the pores in the porous layer 106 of
the anodization layer 103 have diameter D. Diameter D may be 10-100
nm, and mostly 15-80 nm. The thickness of the porous layer 106 and
diameter D of the pores results in an aspect ratio of the
anodization column 110 height to the pore diameter being in a range
from about 10 to 1 (10:1) to about 2000 to 1 (2000:1) in
embodiments. A typical height to width ratio for individual columns
110 may be greater than 300:1 in embodiments.
[0030] A post-anodization process is sealing the anodized layer by
forming one or more sealing layer 114, 115 at the top of the porous
layer 106, as shown in the modified (i.e. anodized and sealed)
chamber component 100B in FIG. 1B. Sealing can be performed by
using a combination of deionized water (DI) or steam, nickel
plating (e.g., using nickel acetate), and/or application of
polytetrafluoroethylene (PTFE), and/or or other sealing methods
discussed below.
[0031] As shown, a multi-layer sealing layer comprising a first
sealing layer 115 and a second sealing layer 114 is created in
embodiments. The first sealing layer 115 may be nickel hydroxide if
nickel acetate sealing is used, may be hydrated aluminum oxide
(boehmit) if water or steam sealing is used, may be PTFE if
application of PTFE is used, and so on. The second sealing layer
114 may likewise be nickel hydroxide if nickel acetate sealing is
used, may be hydrated aluminum oxide (boehmit) if water or steam
sealing is used, may be PTFE if application of PTFE is used, and so
on. Other possible sealing techniques that may be used for the
first and/or second sealing layers 114, 115 include sealing using
nickel fluoride and sealing using potassium dichromate.
[0032] Different sealing techniques are used to produce the first
sealing layer 115 and the second sealing layer 114. Accordingly,
the multi-layer sealing layer includes layers of at least two
different materials. Notably, the resultant sealing layer is a
multi-layer (or hybrid) sealing layer that includes advantageous
properties of two different types of sealants. For example, a
hybrid sealing layer may combine the desirable properties of high
breakdown voltage, designed surface smoothness and reduced surface
defect density.
[0033] FIG. 1C shows that the sealing layer at the top of columns
110 may not be continuous as shown in FIG. 1B. Instead, in some
embodiments, a first sealing layer 116 and a second sealing layer
117 may be formed at the top portions of each of the columns 110,
narrowing the hollow space in pores 112 towards the top, but not
completely closing the pores 112.
[0034] FIG. 2 illustrates an exemplary architecture of a
manufacturing system 200 for manufacturing a chamber component
(e.g., chamber component 100A of FIG. 1A). The manufacturing system
200 may be a system for manufacturing an article for use in
semiconductor manufacturing. In one embodiment, the manufacturing
system 200 includes processing equipment 201 connected to an
equipment automation layer 215. The processing equipment 201 may
include a block 203 that prepares a metallic article for
anodization and sealing, an anodizer block 204 that forms an
anodization layer, and a sealing block 205 that performs sealing on
the anodization layer. The manufacturing system 200 may further
include one or more computing devices 220 connected to the
equipment automation layer 215. In alternative embodiments, the
manufacturing system 200 may include more or fewer components. For
example, the manufacturing system 200 may include manually operated
(e.g., off-line) processing equipment 201 without the equipment
automation layer 215 or the computing device 220.
[0035] The block 203 can adjust a surface roughness of an article
prior to any layers or coatings being formed. For example, the
block 203 may adjust a surface roughness of the article to be in a
range from about 15 micro-inches to about 300 micro-inches (e.g.,
about 120 micro-inches). In other embodiments, the surface
roughness of the article may be increased by grinding or bead
blasting, or may be decreased by sanding or polishing. However, the
surface roughness of the article may already be suitable, so
surface roughness adjustment can be optional.
[0036] In one embodiment, anodizer 204 is a system configured to
form an anodization layer on the metallic article. For example, the
article (e.g., a conductive article) may be immersed in an
anodization bath, e.g., including sulfuric acid, oxalic acid,
phosphoric acid, or a mixture of these acids. An electrical current
is applied to the article such that the article becomes an anode.
The anodization layer then forms on the metallic article.
[0037] In one embodiment, after anodization, the article can be
baked in a heating apparatus (e.g., an oven) for certain period
(e.g., 2 hours to 12 hours) at a certain temperature (e.g., 60
degrees C. to 150 degrees C.) to remove residual moisture from the
article and/or the anodization layer.
[0038] The block 205 is a system configured to seal the anodized
surface, according to the various methods described below. Block
205 may be an atomic layer deposition (ALD) system, a physical
vapor deposition (PVD) system, a chemical vapor deposition (CVD)
system, a plasma enhanced chemical vapor deposition (PECVD) system,
a plasma enhanced physical vapor deposition (PEPVD) system, or a
wet chemical deposition system (such as a sol gel system or a
slurry printing system). For DI sealing, block 205 may include a
steam generator. For nickel sealing, block 205 may include a
plating bath containing nickel acetate solution. For PTFE sealing,
block 205 may include a system for spraying, dipping or brushing a
PTFE-containing thermosetting resin.
[0039] The equipment automation layer 215 may interconnect some or
all of the manufacturing machines 201 with computing devices 220,
with other manufacturing machines, with metrology tools and/or
other devices. The equipment automation layer 215 may include a
network (e.g., a location area network (LAN)), routers, gateways,
servers, data stores, and so on. Manufacturing machines 201 may
connect to the equipment automation layer 215 via a SEMI Equipment
Communications Standard/Generic Equipment Model (SECS/GEM)
interface, via an Ethernet interface, and/or via other interfaces.
In one embodiment, the equipment automation layer 215 enables
process data (e.g., data collected by manufacturing machines 201
during a process run) to be stored in a data store (not shown). In
an alternative embodiment, the computing device 220 connects
directly to one or more of the manufacturing machines 201.
[0040] In one embodiment, some or all manufacturing machines 201
include a programmable controller that can load, store and execute
process recipes. The programmable controller may control
temperature settings, gas and/or vacuum settings, time settings,
etc. of manufacturing machines 201. The programmable controller may
include a main memory (e.g., read-only memory (ROM), flash memory,
dynamic random access memory (DRAM), static random access memory
(SRAM), etc.), and/or a secondary memory (e.g., a data storage
device such as a disk drive). The main memory and/or secondary
memory may store instructions for performing heat treatment
processes described herein.
[0041] The programmable controller may also include a processing
device coupled to the main memory and/or secondary memory (e.g.,
via a bus) to execute the instructions. The processing device may
be a general-purpose processing device such as a microprocessor,
central processing unit, or the like. The processing device may
also be a special-purpose processing device such as an application
specific integrated circuit (ASIC), a field programmable gate array
(FPGA), a digital signal processor (DSP), network processor, or the
like. In one embodiment, programmable controller is a programmable
logic controller (PLC).
[0042] The parameters of the various possible sealing processes are
now discussed in greater detail.
[0043] One of the possible sealing techniques is sealing the
anodization layer with DI water at high temperature, the technique
being known as DI sealing (or DI water sealing, or DI steam
sealing). In DI sealing, an anodized part is immersed into
deionized water (e.g., hot DI water at about 96-100.degree. C.) or
steam to form hydrated aluminum oxide (boehmit) in columnar pores
of the anodization layer. The hydrated aluminum oxide swells the
columns at least near a surface of the porous layer of the
anodization layer, reducing a surface porosity of the porous layer.
For example, the sealing layer 114 or sealing layer 115 in FIG. 1B
may be a hydrated aluminum oxide layer. DI sealing is performed to
close or seal the columnar structure (e.g., the pores) of the
anodization layer. The sealing layer 114 may be formed at the top,
leaving some hollow space 112 underneath the sealing layer.
[0044] Without a high quality sealing, the anodization layer may be
highly absorbent of dirt, grease, oils and stains. Typically, DI
sealing is performed to give high corrosion resistance. Typically,
DI water sealing rate is about 2 to 3 minutes per micrometer of
oxide coating. Therefore, for a hard anodization (e.g., HA (III))
with 2 to 2.5 mils thickness of the anodization layer, the water
sealing time would be around 1.0 hour to 4.0 hours. The time
variation is highly dependent on the temperature of the water or
steam. A higher temperature is correlated to faster sealing. To
maintain a uniform temperature throughout the entire tank used to
perform the DI water or steam sealing, a small amount of air
agitation may be used. The pH of the solution is in the range of
5.5-6.5 and may be adjusted with ammonia and/or other agents for an
optimal seal. DI water sealing quality is usually controlled by the
control of pH value and the sealing temperature. By clogging up the
pores on the surface, the anodized aluminum sealed with DI water
has the advantages of stronger structural integrity, enhanced
dielectric strength, high purity semiconductor processing, etc. For
example, for a 62.5 .mu.m (2.5 mil) thickness of anodization layer
on aluminum, post DI water sealing, the roughness is less than less
than 0.8 .mu.m (32 .mu.-inch), 5% HCl corrosion time (a measure of
structural integrity) is 2.5-3.0 hours, and dielectric strength is
30-32V/.mu.m (750-800 V/mil).
[0045] An alternative to DI sealing is post-anodization nickel
plating for sealing the anodization layer. Ni sealing, also called
nickel acetate sealing, comprises immersing the anodized aluminum
in a boiling nickel acetate solution. Hydrolysis occurs, which
causes nickel hydroxide to precipitate into the pores of the porous
layer of the anodization layer. As a result of the nickel acetate
sealing, nickel ions (e.g., nickel hydroxide) are incorporated into
the pores of the porous layer. The nickel ions (e.g., nickel
hydroxide) then block or fill the mouths of these pores.
[0046] Ni sealing may be performed at a temperature of
93-99.degree. C. (200-210.degree. F.). The sealing time can be
adjusted. For example, in a range of 10-80 minutes for hard
anodized (e.g., HA (III)) parts that have 2 mils or 2.5 mils (50
.mu.m to 62.5 .mu.m) thick anodization structure, the sealing time
is in the range of 10-80 minutes, which is equal to 2-3 minutes per
0.10 mil (approximately 2.5 .mu.m) of oxide coating thickness. The
chemical formulation of the Ni sealing solution may comprise nickel
acetate in the range of 4-5 g/l, some specialty dispersant in the
range of 2-3 g/l, benzoic acid in the range of 1-2 g/l and high
purity DI water. The pH value of the Ni sealing solution is in the
range of 5-7, which can be adjusted by adding diluted ammonium
hydroxide. However, the sealing quality is usually controlled by
controlling the nickel acetate concentration and the sealing
temperature. Before sealing, a thorough rinse is recommended to
remove any foreign substances. The article should be thoroughly
rinsed immediately after nickel plating before it is dried. Ni
sealing can make the smooth anodization surface with superior acid
resistance. For example, for a 62.5 .mu.m (2.5 mil) thickness of
anodization layer on aluminum, post Ni acetate sealing, 5% HCl
corrosion time (a measure of structural integrity) is 2.5-3.0
hours. The roughness is less than less than 0.8 um (32 .mu.-inch),
i.e. comparable to DI water sealing. But the dielectric strength is
20-22V/.mu.m (500-550 V/mil), i.e. less than what is achievable by
DI water sealing.
[0047] Another technique for Ni sealing is performed using nickel
fluoride. This process is a cold sealing process that may be used
as an alternative to hot sealing methods. For Ni sealing using
nickel fluoride, fluoride nickel is introduced to the anodized
aluminum. The fluoride ions enter into the pores, which act as the
place for an exchange mechanism. Once in the pores, the fluoride
ions cause a shift in pH, which causes nickel ions to precipitate.
Nickel hydroxide is then formed, which blocks the mouth of the
pores, effectively sealing the porous layer. Water from the
atmosphere may then diffuse into the nickel hydroxide, causing the
pores to become effectively blocked.
[0048] When used in the plasma generator chamber, the anodized Al
surface sealed by DI water or Ni acetate reacts with
fluorine-containing plasma (e.g., NF3 generated plasma), forming
AlF3 deposition on the anodized surface and then induces AlF3 or
AlF0-based particle contamination after some length of service
time. For example, chamber particle count may reach more than 100,
compared to the desired particle control specification (<15
particles at size <26 nm on wafer), when service time exceeds
100RF hours. This unstable anodization surface adversely impacts
the chamber process performance and reduces production yield.
[0049] A third sealing process is PTFE (commercially known as
teflon) sealing. PTFE sealing comprises spraying, dipping, or
brushing a thermosetting resin containing PTFE to the unsealed
surface of the porous layer of the anodization layer (anodized
surface). The article can then be cured at 165-185.degree. C. for
around 1 hour, to form a PTFE-film-sealed anodization surface. The
sealed PTFE thickness depends on the desired use of the anodized
sealed article. Thicker PTFE coating can be achieved by a
multi-cycle sealing process. Teflon sealing forms an anodized
sealed surface with high smoothness, high dielectric strength and
strong acid resistance. However, a disadvantage is that the surface
of the PTFE coating is relatively soft and easy to be damaged by
any mechanical friction during handling and/or assembly.
[0050] Depending on the sealing process time and temperature, the
electrical current, and sealing materials, the resultant
anodization surface could be rough or smooth, and may have some
structural cracks around the corners of the metallic article and/or
abnormality at other geometric locations. The surface roughness and
defect density directly affect the measurable properties of the
anodization layer, such as the dielectric strength (indicated by
breakdown voltage, V.sub.bd) and acid solution resistance of the
anodized surface. Acid solution resistance is measured by 5% HCl
bubble testing for various durations. The variation on the V.sub.bd
and the bubble test time can indicate the durability of the
anodization layer in the plasma environment. For instance, a DI
water steam sealed cellular Al.sub.2O.sub.3 anodization layer
exhibits high dielectric strength but rough surface finish with
increased numbers of micro-cracks. This leads to a short bubble
test time and possibly increases particle contamination risk during
later processing in plasma rich environments. In contrast, a Ni
plating sealed cellular Al.sub.2O.sub.3 layer demonstrates a very
smooth and dense anodized surface, but relatively low dielectric
strength. This may cause the anodized surface to be easily eroded
by plasma through physical bombardment (as V.sub.bd is low) and may
induce metal contamination. A dense and smooth anodized surface can
be achieved using the PTFE sealing process. However, the resulting
anodized surface after PTFE sealing is soft and easily damaged
during handling, processing and assembling.
[0051] With the selection and the combination of different sealing
processes and different orders of those sealing processes, the
anodized and sealed surface can be designed to have desired surface
smoothness, reduced surface defect density and increased dielectric
strength.
[0052] In one embodiment, DI water steam sealing and Ni sealing are
combined to seal the anodization layer without reducing anodization
layer thickness. The sealed anodization layer comprising a
multi-layer seal maintains high dielectric strength and high
hardness compared to when only DI water sealing is used. At the
same time, smoothness of the surface improves compared to when only
DI water sealing is used. Order of DI water sealing and Ni sealing
may be interchanged. In one embodiment, DI water/steam sealing is
performed first, followed by Ni sealing. Alternatively, Ni sealing
is performed first, followed by DI water/steam sealing. Depending
on the plasma environment conditions, the final sealing process may
be chosen to be either Ni plating or DI water steam sealing,
depending on whether surface smoothness or dielectric strength of
the outermost layer is more desirable. In addition, the properties
such as the dielectric strength and the final surface smoothness of
the anodized structure can be tailored by adjusting process time,
temperature and other conditions in each sealing process.
[0053] In one embodiment, a dense and smooth anodization with high
dielectric strength can be achieved by the anodization followed by
hybridization of DI water steam sealing and the PTFE sealing
processes. In one embodiment, DI water/steam sealing is performed
first, followed by PTFE sealing. Alternatively, PTFE sealing is
performed first, followed by DI water/steam sealing. Compared to Ni
plating, both water steam sealing and the PTFE sealing help to
increase dielectric strength because of the improved dense and
smooth surface. By preventing dielectric breakdown of the process
chamber components, a stable plasma can be maintained during the
plasma process, improving semiconductor wafer yield.
[0054] In one embodiment, Ni sealing is performed first, followed
by PTFE sealing. Alternatively, PTFE sealing is performed first,
followed by Ni sealing.
[0055] This disclosure encompasses any permutation or combination
of the above three sealing processes, i.e. DI sealing, Ni sealing
and PTFE sealing, to form a hybrid multi-layer sealing layer that
results in an enhanced anodized surface for processing chamber
components.
[0056] In an alternative implementation, a hybrid sealing process
may involve deposition of a coating material and/or surface
alloying to cover and protect the anodized surface after performing
one or more of DI sealing, Ni sealing and/or PTFE sealing.
Alternatively, sealing may be performed by depositing a conformal
layer over the pores of the porous layer of the anodization layer.
The coating material may be referred to as an "advanced coating"
material. The coating material may be an oxide, an oxy-fluoride or
a fluoride. Possible examples include, but are not limited to,
Al.sub.2O.sub.3, AlF.sub.3, Y.sub.2O.sub.3, Y--O--F (e.g.,
Y.sub.5O.sub.4F.sub.7), Er.sub.2O.sub.3, YF.sub.3,
Y.sub.3Al.sub.5O.sub.12 (YAG), Er.sub.3Al.sub.5O.sub.12 (EAG),
Y.sub.4Al.sub.2O.sub.9 (YAM), YAlO.sub.3 (YAP),
Er.sub.4Al.sub.2O.sub.9 (EAM), ErAlO.sub.3 (EAP), a solid solution
of Y.sub.2O.sub.3--ZrO.sub.2, a ceramic compound comprising
Y.sub.4Al.sub.2O.sub.9 and a solid-solution of
Y.sub.2O.sub.3--ZrO.sub.2, and their combinations.
[0057] With reference to the solid-solution of
Y.sub.2O.sub.3--ZrO.sub.2, the coating material may include
Y.sub.2O.sub.3 at a concentration of 10-90 molar ratio (mol %) and
ZrO.sub.2 at a concentration of 10-90 mol %. In some examples, the
solid-solution of Y.sub.2O.sub.3--ZrO.sub.2 may include 10-20 mol %
Y.sub.2O.sub.3 and 80-90 mol % ZrO.sub.2, may include 20-30 mol %
Y.sub.2O.sub.3 and 70-80 mol % ZrO.sub.2, may include 30-40 mol %
Y.sub.2O.sub.3 and 60-70 mol % ZrO.sub.2, may include 40-50 mol %
Y.sub.2O.sub.3 and 50-60 mol % ZrO.sub.2, may include 60-70 mol %
Y.sub.2O.sub.3 and 30-40 mol % ZrO.sub.2, may include 70-80 mol %
Y.sub.2O.sub.3 and 20-30 mol % ZrO.sub.2, may include 80-90 mol %
Y.sub.2O.sub.3 and 10-20 mol % ZrO.sub.2, and so on.
[0058] With reference to the ceramic compound comprising
Y.sub.4Al.sub.2O.sub.9 and a solid-solution of
Y.sub.2O.sub.3--ZrO.sub.2, in one embodiment the ceramic compound
includes 62.93 molar ratio (mol %) Y.sub.2O.sub.3, 23.23 mol %
ZrO.sub.2 and 13.94 mol % Al.sub.2O.sub.3. In another embodiment,
the ceramic compound can include Y.sub.2O.sub.3 in a range of 50-75
mol %, ZrO.sub.2 in a range of 10-30 mol % and Al.sub.2O.sub.3 in a
range of 10-30 mol %. In another embodiment, the ceramic compound
can include Y.sub.2O.sub.3 in a range of 40-100 mol %, ZrO.sub.2 in
a range of 0.1-60 mol % and Al.sub.2O.sub.3 in a range of 0.1-10
mol %. In another embodiment, the ceramic compound can include
Y.sub.2O.sub.3 in a range of 40-60 mol %, ZrO.sub.2 in a range of
35-50 mol % and Al.sub.2O.sub.3 in a range of 10-20 mol %. In
another embodiment, the ceramic compound can include Y.sub.2O.sub.3
in a range of 40-50 mol %, ZrO.sub.2 in a range of 20-40 mol % and
Al.sub.2O.sub.3 in a range of 20-40 mol %. In another embodiment,
the ceramic compound can include Y.sub.2O.sub.3 in a range of 80-90
mol %, ZrO.sub.2 in a range of 0.1-20 mol % and Al.sub.2O.sub.3 in
a range of 10-20 mol %. In another embodiment, the ceramic compound
can include Y.sub.2O.sub.3 in a range of 60-80 mol %, ZrO.sub.2 in
a range of 0.1-10 mol % and Al.sub.2O.sub.3 in a range of 20-40 mol
%. In another embodiment, the ceramic compound can include
Y.sub.2O.sub.3 in a range of 40-60 mol %, ZrO.sub.2 in a range of
0.1-20 mol % and Al.sub.2O.sub.3 in a range of 30-40 mol %. In
other embodiments, other distributions may also be used for the
ceramic compound.
[0059] Any of the aforementioned ceramic coatings may include trace
amounts of other materials such as ZrO.sub.2, Al.sub.2O.sub.3,
SiO.sub.2, B.sub.2O.sub.3, Er.sub.2O.sub.3, Nd.sub.2O.sub.3,
Nb.sub.2O.sub.5, CeO.sub.2, Sm.sub.2O.sub.3, Yb.sub.2O.sub.3, or
other oxides.
[0060] A conventional sealing process may be replaced by the
non-line-of-sight deposition of one of the aforementioned coating
materials directly onto the un-sealed anodization layer, to seal
the anodized porous columnar structure. The coating material
ideally should have thermal expansion coefficient close to the
underlying anodization layer to reduce the possibility of thermally
induced stress. The advanced coating material should also have high
stability against plasma erosion, and ideally would not generate
deposition by-products (such as AlF.sub.3, AlOF, etc. in fluorine
and/or chlorine-containing plasma environments).
[0061] The sealing layer should be formed using deposition
processes that allow conformal coverage onto the anodization layer
columns, i.e. there should be uniform and controllable thickness
even within the pores between the columns. One example approach is
the deposition of one or more layers of coating material using
atomic layer deposition process (ALD).
[0062] ALD is one of the suitable methods for forming a
multi-component coating composition on a chamber component for a
processing chamber. The method may include depositing a first film
layer (e.g., an oxide or a fluoride) onto a surface of a chamber
component. The first film layer is grown from at least two
precursors. The method further includes depositing a second film
layer of an additional oxide or an additional fluoride onto the
surface of the chamber component. The second film layer may be
grown from at least two additional precursors using the atomic
layer deposition process. In some embodiments, additional layers
may be deposited too.
[0063] The various components may be arranged in different layers
of the multi-component coating. In some embodiments, after
processing (such as annealing) the multiple layers of the
multi-component coating may interdiffuse to form a homogenous or
approximately homogenous coating that includes the constituent
materials of the different layers. For example, the multiple
components from the different layers may form a solid state phase
of a first film layer and a second film layer.
[0064] Persons skilled in the art would appreciate that ALD is
merely an example process for coating deposition and does not limit
the scope of the disclosure. Other processes, such as physical
vapor deposition (PVD), chemical vapor deposition (CVD), plasma
enhanced chemical vapor deposition (PECVD), plasma enhanced
physical vapor deposition (PEPVD), and wet chemical depositions
(sol gel, slurry printing, etc.) may be used too.
[0065] In one embodiment, thickness of the advanced coating is
controlled, so that the pores are fully filled between the columns
110. FIG. 3A shows an advanced coating layer 314A (comprising one
or more layers of a single material, or more than one layers of
more than one material) that overfills the pores and builds
additional thickness at the top of the columns 110 of the
anodization layer 103. The pores have diameters in the range of
25-60 nm in embodiments. The advanced coating results in a dense
and pore-free solid structure 300A, which can be either crystalline
or amorphous.
[0066] In another embodiment, thickness of the advanced coating is
controlled, so that the pores are partially filled between the
columns 110, as shown in FIG. 3B. In this embodiment, the advanced
coating layer 314B conformally covers the columns, leaving a pore
gap 316 between the columns. The pore size may be reduced to the
range of 5-60 nm due to the additional thickness of the advanced
coating layer 314B onto the columns 110. This is known as an open
column structure. One of the advantages of an open column structure
300B is that it can adapt to temperature variation better than a
solidly sealed structure 300A shown in FIG. 3A or a hybridly sealed
structure 100B shown in FIG. 1B. Specifically, the gap between the
coated columns of the porous layer of the anodization layer leaves
space for the columns to expand without introducing additional
stress to the anodization layer.
[0067] As described above, the anodization layer columns sealed
with one or more layers of advanced coating materials greatly
reduce plasma erosion and undesired by-product formation during
plasma processes. In order further to reduce the risk of the
process drift induced by the formation of by-products, such as AlF3
from an Al2O3 coating, or YF3/YOF from the Y2O3 coating, in one
embodiment, the present disclosure describes in-situ fluorination
over the advanced coating surface. Fluorination can be conducted
through a wet chemical reaction process, a relative
high-temperature heating process in the presence of fluorine,
and/or an in-situ plasma irradiation process using a
fluorine-containing plasma in a plasma processing chamber. The
fluorination process creates a dense and smooth surface of a metal
fluoride or a metal oxyfluoride (e.g., with YF3, YOF, AlF3, AlOF,
etc.), depending on the plasma process chemistry and the
composition of the underlying advanced coating material. For
example, Y2O3 converts to YxOyFz or YF3, a solid solution of
Y2O3-ZrO2 converts to Y--Zr--O--F (e.g., YaZrbOcFd) or YxZyFz, and
so on. In general, when the advanced coating material has an oxide
layer, conducting in-situ fluorination replaces at least a portion
of oxygen molecules of the oxide with fluorine molecules and
converts at least a surface of the coating from the oxide into a
fluoride or an oxy-fluoride.
[0068] In an example implementation of a first method for forming a
Y--O--F layer or coating, a yttrium-containing coating (e.g., a
Y2O3 coating or Y2O3-ZrO2 solid solution coating) is deposited on a
surface of a chamber component for a first processing chamber.
Alternatively a MxOy coating may be deposited, where M is a metal
such as Al or a rare earth metal. The chamber component is heated
to an elevated temperature of about 150-1000.degree. C. (e.g.,
150-500.degree. C.). The chamber component is exposed to a fluorine
source such as HF, NF3, NF3 plasma, F2, F radicals, etc. at the
elevated temperature for a duration of time. As a result, at least
a surface of the yttrium-containing oxide coating is converted into
a Y--O--F layer or other yttrium-based oxy-fluoride layer or
coating. In some instances, an entirety of the yttrium-containing
oxide coating is converted to Y--O--F or other yttrium containing
oxy-fluoride. Alternatively, at least a surface of the MxOy coating
is converted to a M-O--F layer.
[0069] In an example implementation of a second method for forming
a Y--O--F layer or coating, atomic layer deposition (ALD), chemical
vapor deposition (CVD), ion assisted deposition (IAD) or any other
suitable method is performed to deposit a YF3 coating having a
thickness of about 10 nm to about 10 microns onto a surface of a
chamber component for a processing chamber. The chamber component
is heated to an elevated temperature of about 150-1500.degree. C.
The chamber component is exposed to an oxygen source at the
elevated temperature for a duration of about 12-24 hours. As a
result, the YF3 coating is converted into a Y--O--F coating.
[0070] In an example implementation of a third method for forming a
M-O--F layer or coating, a substrate is loaded into a processing
chamber, the processing chamber comprising one or more chamber
components that include a metal oxide coating. A fluorine-based
plasma from a remote plasma source is introduced into the
processing chamber. The metal oxide coating is reacted with the
fluorine-based plasma to form a temporary M-O--F layer or metal
fluoride layer over the metal oxide coating. A process that
utilizes a corrosive gas is then performed on the substrate. The
process removes or adds to the temporary M-O--F layer or metal
fluoride layer, but the temporary M-O--F layer or metal fluoride
layer protects the metal oxide coating from the corrosive gas.
[0071] FIG. 4A shows a pore-free structure 400A where a fluorinated
outer surface layer 418A is formed on the advanced coating layer
414A that seals the anodization layer columns 110 by completely
filling up the pores (as in FIG. 3A). FIG. 4B shows an open
structure 400B where a fluorinated outer surface layer 418B is
formed on the advanced coating layer 414B that seals the
anodization layer columns 110 by partially filling up the pores (as
in FIG. 3B), still leaving a gap 416 between the columns 110, but
with altered diameter of the pore due to the addition of the
fluorinated layer 418B. Persons skilled in the art will appreciate
that since there is chemical reaction involved in fluorination that
changes surface characteristics of the advanced coating layer
underneath, the pore size alternation may reduce the pore size (for
example, conversion from Y2O3 to Y--O--F or YF3 may cause a volume
expansion and reduce the pore size), but that is not always the
case. As in case of the open structure 300B, the open structure
400B also have advantageous thermal properties, because the pores
help in adapt to temperature variation without causing significant
thermal stress in the sealed structure. Further to enhance the
anodization surface performance, in some embodiments, the sealed
anodized components may be heated or annealed to stabilize the
coating or coated structure.
[0072] The advanced coating protected anodized structure may slow
down plasma erosion and reduce the metal and particle contamination
of an article due to the smooth and defect-free surface. This
improves the plasma process stability and durability. The advanced
coating sealed anodized articles with or without surface
fluorination can also be used in processing chambers that perform
PVD, CVD and/or plasma etching processes.
[0073] Surface fluorination through acid immersion may be performed
using mixed acid solutions containing HF, NH4F, and H2O2 in
predetermined volumetric ratio based on the underlying coating
layer properties (e.g., what coating material is used, how many
layers are used, what thickness is used etc.) and the desired
properties of the fluorinated outer surface (e.g., porosity area,
fluorinated layer thickness etc.). Using the methods of sealing
disclosed here, the size of the pores post-coating can be adjusted
in the range of 5-60 nm, depending on the actual application in
different chamber systems and chamber processes used. This range of
pore size can be achieved either post-fluorination or
pre-fluorination.
[0074] FIG. 5 is a flowchart showing a method 500 for manufacturing
an anodized sealed article, in accordance with embodiments of the
present disclosure. The operations of method 500 may be performed
by various manufacturing machines, as set forth in FIG. 2.
[0075] At block 501, an article is provided. For example, the
article can be a conductive article formed of an aluminum alloy
(e.g., Al 6061) or another metallic article or article that
contains a metallic part. The article can be a shower head, a
cathode sleeve, a sleeve liner door, a cathode base, a chamber
liner, an electrostatic chuck base, etc., for use in a processing
chamber. Though not shown specifically, the article may be cleaned
and its roughness may be altered in order to prepare the article
for subsequent anodization.
[0076] At block 503, the article is anodized to form an anodization
layer (e.g., formed of Al.sub.2O3), according to one embodiment.
The anodization layer has a porous layer at the top, as discussed
above. In one embodiment, the article can be baked after
anodization, as described above, to remove residual moisture from
pores of the anodization layer.
[0077] At block 505, a hybrid sealing layer is formed at the top of
the porous layer by performing a hybrid sealing process. The hybrid
sealing process comprises performing a first sealing process at
block 515 to partially seal the pores of a porous layer of an
anodization layer and performing a second sealing process at block
518 to further seal the pores of the porous layer. The first
sealing process and the second sealing process each comprise one of
DI water sealing (block 507), Ni sealing (block 509), and PTFE
sealing (block 511). These three sealing processes may be performed
in any order to produce target plasma resistant properties and/or
other properties of the sealed anodized article.
[0078] FIG. 6 is a flowchart showing an alternative method 600 for
manufacturing an anodized sealed article, in accordance with
embodiments of the present disclosure. The operations of method 600
may be performed by various manufacturing machines, as set forth in
FIG. 2.
[0079] Blocks 601 and 603 are similar to blocks 501 and 503 in
flowchart 500. In block 605, the porous anodization layer is coated
with a coating material. If multiple layers of coating are desired,
then the operation of block 605 may be repeated until all layers
are deposited. Multiple layers of the same coating material or
multiple layers of different coating materials may be deposited in
block 605. The operation of block 605 may be coextensive with the
operation of decision block 607. If it is desired to completely
fill the pores, then the thickness is controlled (block 609) so
that no gap remains between columns, and optionally additional
thickness is built at the top of the columns. The thickness may be
controlled by repeating the operations of block 605 and depositing
additional layers of the coating material (or materials) until a
target thickness is reached. If it is desired to partially fill the
pores to result in an open structure (as shown in FIGS. 3B and 4B),
then the thickness is controlled (block 611) so that a finite gap
remains between columns. The thickness may be controlled by
repeating the operations of block 605 and depositing additional
layers of the coating material (or materials) until a target
thickness is reached.
[0080] Finally, an optional in-situ fluorination process may be
added (block 613) to fluorinate the outer surface of the coating
material used to seal the porous anodization layer.
[0081] In one embodiment, prior to performing the operations of
block 605, one or more of DI sealing, Ni sealing or PTFE sealing
are performed.
[0082] The resulting anodized sealed article produced by the
methods of flowcharts 500 and 600 demonstrate superior resistance
against plasma erosion. Therefore, less contaminants are introduced
in the wafers during processing, as well as the service life of the
article is prolonged.
[0083] FIG. 7 shows a properties associated with various hybrid
sealing and advanced coating and sealing processes in a tabular
format, in accordance with embodiments of the present disclosure.
Persons skilled in the art would appreciate that these processes
are merely examples processes encompassed by this disclosure, while
many other processes are within the scope of this disclosure. The
specific processes shown in the table are: a first process
comprising DI-only sealing (row 1), a second process comprising
Ni-only sealing (row 2), a third process (hybrid sealing process)
comprising DI sealing for half the regular time period of DI-only
sealing followed by Ni sealing for half the regular time period of
Ni-only sealing (row 3), a fourth process (another hybrid sealing
process) comprising Ni sealing for half the regular time period of
Ni-only sealing followed by DI sealing for half the regular time
period of DI-only sealing (row 4), a fifth process (yet another
hybrid sealing process) comprising DI sealing for half the regular
time period of DI-only sealing followed by Ni sealing for the
entire regular time period of Ni-only sealing (row 5), a sixth
process (yet another hybrid sealing process) comprising Ni sealing
for half the regular time period of Ni-only sealing followed by DI
sealing for the entire regular time period of DI-only sealing (row
6), a seventh process (yet another hybrid sealing process)
comprising DI sealing for the entire regular time period of DI-only
sealing followed by Ni sealing for half of the regular time period
of Ni-only sealing (row 7), an eighth process using an advanced
Al.sub.2O.sub.3 coating to enhance the sealing function (row 8),
and a ninth process using an advanced
Y.sub.2O.sub.3/Al.sub.2O.sub.3 coating to enhance the sealing
function (row 9).
[0084] Combination of Ni and DI water sealing improves the sealing
by increasing the breakdown voltage (V.sub.bd), and resistance to
acids (e.g., HCl acid), as well as increases electrical resistance.
The surface roughness R.sub.a and total resistivity R are tabulated
in the last two columns corresponding to each process. It is noted
that advanced newton single or double coatings enhances the
smoothness of the anodized surface while enhancing the breakdown
voltage, acid resistance and electrical resistance.
[0085] FIG. 8 illustrates impedance enhancement results
corresponding to various hybrid sealing and advanced coating and
sealing processes. The plots in FIG. 8 show potentiostatic
electrochemical impedance spectroscopy (EIS) results for articles
that have been coated and sealed according to various processes
disclosed herein. Specifically, the y-axis is the impedance
(Z.sub.mod) for an area and the x-axis is the frequency in Hz. As
shown, bare Al has the lowest impedance value. Al with an
anodization layer has impedance values that are generally
acceptable. The hybrid sealing comprising DI water sealing and Ni
plating sealing slightly increases the impedance of the formed
anodization layer, though it has been observed that at temperature
beyond 120.degree. C. (e.g., at 150.degree. C.), anodization layer
impedance drops. Advanced single coating (e.g., 2 .mu.m
Al.sub.2O.sub.3) or advanced double coating (e.g., 1 .mu.m
Y.sub.2O.sub.3/2 .mu.m Al.sub.2O.sub.3)-based sealing greatly
increases the impedance even at much higher temperature than
120.degree. C. (e.g., in the range of 350.degree. C.), and the
coating remains stable.
[0086] The preceding description sets forth numerous specific
details such as examples of specific systems, components, methods,
and so forth, in order to provide a good understanding of several
embodiments of the present disclosure. It will be apparent to one
skilled in the art, however, that at least some embodiments of the
present disclosure may be practiced without these specific details.
In other instances, well-known components or methods are not
described in detail or are presented in simple block diagram format
in order to avoid unnecessarily obscuring the present disclosure.
Thus, the specific details set forth are merely exemplary.
Particular implementations may vary from these exemplary details
and still be contemplated to be within the scope of the present
disclosure.
[0087] Reference throughout this specification to "one embodiment"
or "an embodiment" means that a particular feature, structure, or
characteristic described in connection with the embodiment is
included in at least one embodiment. Thus, the appearances of the
phrase "in one embodiment" or "in an embodiment" in various places
throughout this specification are not necessarily all referring to
the same embodiment. In addition, the term "or" is intended to mean
an inclusive "or" rather than an exclusive "or."
[0088] Although the operations of the methods herein are shown and
described in a particular order, the order of the operations of
each method may be altered so that certain operations may be
performed in an inverse order or so that certain operation may be
performed, at least in part, concurrently with other operations. In
another embodiment, instructions or sub-operations of distinct
operations may be in an intermittent and/or alternating manner.
[0089] It is to be understood that the above description is
intended to be illustrative, and not restrictive. Many other
embodiments will be apparent to those of skill in the art upon
reading and understanding the above description. The scope of the
disclosure should, therefore, be determined with reference to the
appended claims, along with the full scope of equivalents to which
such claims are entitled.
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