U.S. patent application number 16/195537 was filed with the patent office on 2021-12-02 for plasma polymerization coating apparatus and process.
The applicant listed for this patent is Jiangsu Favored Nanotechnology Co., LTD. Invention is credited to Jian Zong.
Application Number | 20210371979 16/195537 |
Document ID | / |
Family ID | 1000005968521 |
Filed Date | 2021-12-02 |
United States Patent
Application |
20210371979 |
Kind Code |
A9 |
Zong; Jian |
December 2, 2021 |
PLASMA POLYMERIZATION COATING APPARATUS AND PROCESS
Abstract
Introduced here is a plasma polymerization apparatus. Example
embodiments include a reaction chamber in a shape substantially
symmetrical to a central axis. Some examples further include a
rotation rack in the reaction chamber. The rotation rack may be
operable to rotate relative to the reaction chamber about the
central axis of the reaction chamber. Examples may further include
reactive species discharge mechanisms positioned around a perimeter
of the reaction chamber and configured to disperse reactive species
into the reaction chamber in a substantially symmetrical manner
from the outer perimeter of the reaction chamber toward the central
axis of the reaction chamber, such that the reactive species form a
polymeric coating on surfaces of the one or more substrates during
said dispersion of the reactive species, and a collecting tube
positioned along the central axis of the reaction chamber and
having an air pressure lower than the reaction chamber.
Inventors: |
Zong; Jian; (Wuxi City,
CN) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Jiangsu Favored Nanotechnology Co., LTD |
Wuxi City |
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CN |
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Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20190085447 A1 |
March 21, 2019 |
|
|
Family ID: |
1000005968521 |
Appl. No.: |
16/195537 |
Filed: |
November 19, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/CN2017/112918 |
Nov 24, 2017 |
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16195537 |
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15890476 |
Feb 7, 2018 |
10424465 |
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PCT/CN2017/112918 |
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PCT/CN2017/081773 |
Apr 25, 2017 |
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15890476 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/4584 20130101;
H01J 2237/20214 20130101; B05D 1/62 20130101; C23C 16/0227
20130101; H01J 37/3244 20130101; H01J 2237/3323 20130101; H01J
37/32715 20130101; B05D 1/60 20130101; H01J 37/32082 20130101; C23C
16/52 20130101; H01J 37/32541 20130101 |
International
Class: |
C23C 16/458 20060101
C23C016/458; H01J 37/32 20060101 H01J037/32; C23C 16/52 20060101
C23C016/52; C23C 16/02 20060101 C23C016/02; B05D 1/00 20060101
B05D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2016 |
CN |
201611076904.8 |
Nov 30, 2016 |
CN |
201611076982.8 |
Claims
1. A reaction chamber apparatus for performing plasma
polymerization on the surface of one or more substrates, the
apparatus comprising: a primary rotation rack operably coupled to a
primary rotation shaft and configured to rotate along a central
axis, the primary rotation rack including one or more arms
extending from the primary rotation shaft and away from the central
axis; a secondary rotation rack operably coupled to a secondary
rotation shaft and configured to rotate on a secondary axis that is
distal from the central axis, the secondary rotation shaft coupled
to an arm of the one or more arms extending from the primary
rotation shaft; one or more substrate platforms configured to carry
the one or more substrates that are to receive the plasma
polymerization coating, each substrate platform located on the
secondary rotation rack; and a controller configured to transmit a
rotation rate control signal to a rotation motor to rotate the
primary rotation shaft and primary rotation rack at a controlled
rotation rate.
2. The apparatus of claim 1, further comprising: a dispersal
mechanism positioned around a perimeter of the reaction chamber and
configured to disperse reactive species into the reaction chamber
in a substantially even manner.
3. The apparatus of claim 2, wherein the dispersal mechanism is
configured to disperse reactive species toward the central axis of
the reaction chamber, such that the reactive species form a
polymeric coating on surfaces of the one or more substrates.
4. The apparatus of claim 3, wherein the dispersal mechanism is
communicatively coupled to the controller to receive a dispersal
control signal from the controller to control the dispersal rate of
the reactive species in a substantially even manner on the one or
more substrates.
5. The apparatus of claim 4, wherein the dispersal control signal
controls the dispersal rate of the reactive species by regulating
the applied electrical power to the dispersal mechanism and/or by
regulating the rate of gas that enters the dispersal mechanism for
polymerization.
6. The apparatus of claim 5, wherein the controller transmits the
dispersal rate control signal to adjust the dispersal rate to
account for the density decrease in the reactive species within the
reaction chamber resulting from the deposition of the reactive
species on to the one or more substrates and the density increase
within the reactive species in the reaction chamber resulting from
the reactive species converging toward the center of the chamber
such that the density of reactive species across the reaction
chamber is uniform.
7. The apparatus of claim 2, wherein the dispersal mechanism
includes a discharge cavity and a metal grid configured to create a
pressure differential between the discharge cavity and the reaction
chamber, the metal grid further configured to reduce or prevent gas
backflow from the reaction chamber to the discharge cavity.
8. The apparatus of claim 7, further comprising: a pulse power
source coupled to the metal grid, the pulse power source configured
to provide a positive electrical charge to the metal grid in
pulses, wherein plasma in the discharge cavity is blocked from
entering the reaction chamber during a pulse-off period, and the
plasma in the discharge cavity is passed through to the reaction
chamber during a pulse-on period.
9. The apparatus of claim 8, wherein the pulse power source
receives a pulse control signal from the controller, the pulse
control signal regulating the power and frequency of the positive
electrical charge.
10. The apparatus of claim 1, further comprising: a collecting tube
positioned along the central axis of the reaction chamber and
operable to have an air pressure lower than the reaction chamber to
collect excess reactive species in the atmosphere of the reaction
chamber at a controlled exhaust rate.
11. The apparatus of claim 10, wherein the collecting tube is
communicatively coupled the controller to receive an exhaust rate
control signal from the controller to control the exhaust rate of
the reactive species.
12. The apparatus of claim 11, wherein the controller transmits the
exhaust rate control signal to adjust the exhaust rate to account
for the density decrease in the reactive species within the
reaction chamber resulting from the deposition of the reactive
species on to the one or more substrates and the density increase
within the reactive species in the reaction chamber resulting from
the reactive species converging toward the center of the chamber
such that the density of reactive species across the reaction
chamber is uniform.
13. The apparatus of claim 1, wherein the primary rotation rack
includes one or more rack layer, each rack layer holding a
plurality of substrate platforms from the one or more substrate
platforms.
14. The apparatus of claim 1, wherein the rotation of the primary
rotation rack along the central axis and the rotation of the
secondary rotation rack along the secondary axis provides the same
rate of spatial movement for each of the one or more substrates
during the coating process in order to achieve uniform coating.
15. The apparatus of claim 1, further comprising: A radio frequency
power supply coupled to a porous electrode, the radio frequency
power supply configured to provide an electrical charge to the
porous electrodes to produce a treatment plasma to remove
impurities from the surface of the one or more substrates, the
radio frequency power supply coupled to the controller to receive a
radio frequency control signal that controls the power output to
the porous electrodes.
16. A reactive species discharge method, comprising: positioning a
substrate on a substrate platform in a reaction chamber;
evacuating, by a vacuum pump, the atmosphere of the reaction
chamber via an air exhaust port in a collecting tube positioned
along a central axis of the reaction chamber; rotating, by a
rotation motor, a primary rotation rack operably coupled to a
primary rotation shaft and configured to rotate along the central
axis; discharging, via an inlet valve, a carrier gas to a discharge
cavity, wherein the carrier gas facilitates a reaction between the
substrate and the reactive species; discharging, via a feeding
port, monomer vapor into the reaction chamber; creating, by a using
the carrier gas, the reactive species by polymerizing the monomer
vapor in the reaction chamber; and depositing, the reactive species
onto the surface of the substrate to form a polymer coating.
17. The reactive species discharge method of claim 16, further
comprising: rotating a secondary rotation rack located on an arm
extending from the primary rotation rack, the secondary rotation
rack rotating on a secondary axis different from the central
axis.
18. The reactive species discharge method of claim 16, further
comprising: collecting, via the collecting tube, excess reactive
species in the atmosphere of the reaction chamber by reducing the
air pressure at the collecting tube to be lower than the air
pressure of the reaction chamber.
19. The reactive species discharge method of claim 16, wherein the
discharge cavity is positioned around a perimeter of the reaction
chamber and configured to disperse the reactive species into the
reaction chamber in a substantially even manner.
20. The reactive species discharge method of claim 16, further
comprising: generating, by an electrode coupled to a radio
frequency power source, a treatment plasma to remove impurities
from the surface of the one or more substrates prior to discharging
the reactive species to the reaction chamber and/or after the
reactive species is deposited on the surface of the substrate.
21. The reactive species discharge method of claim 16, further
comprising: configuring, by a controller, the rotation rate by the
rotation motor to provide the same rate of spatial movement for
each of the one or more substrates during the coating process in
order to achieve uniform coating.
22. The reactive species discharge method of claim 16, further
comprising: configuring, by a controller, the exhaust rate of the
vacuum pump to account for the density decrease in the reactive
species within the reaction chamber resulting from the deposition
of the reactive species on to the substrate and the density
increase within the reactive species in the reaction chamber
resulting from the reactive species converging toward the center of
the chamber such that the density of the reactive species across
the reaction chamber is uniform.
23. The reactive species discharge method of claim 16, further
comprising: configuring, by a controller, the polymerization of the
monomer vapor by regulating the applied electrical power to the
dispersal mechanism and/or by regulating the rate of gas that
enters the dispersal mechanism for polymerization.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part (CIP) of Patent
Cooperation Treaty (PCT) Patent Application No. PCT/CN2017/112918,
filed Nov. 24, 2017, which claims priority to Chinese Invention
Patent Application No. 201611076982.8, filed Nov. 30, 2016, all of
which are incorporated herein by reference in their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to plasma polymerization
technologies and, more specifically, to a plasma polymerization
coating apparatus and process.
TECHNICAL BACKGROUND
[0003] The plasma polymerization coating treatment is an important
surface treatment technique because of its advantages over other
conventional techniques. For example, in plasma polymerization
coating, polymers can be directly attached to a desired surface
where molecular chains grow. This reduces the overall number of
steps necessary for coating the surface to be treated. Other
advantages include the availability of a wider selection of
monomers, as compared to conventional chemical polymerization
techniques.
[0004] However, due to various shortcomings in existing designs of
conventional plasma coating equipment, conventional plasma
polymerization treatment often suffers from production limitations,
resulting in small batch size, low efficiency, high cost, and poor
batch uniformity.
BRIEF DESCRIPTION OF DRAWINGS
[0005] One or more embodiments of the present disclosure are
illustrated by way of example and not limitation in the figures of
the accompanying drawings, in which like references indicate
similar elements. These drawings are not necessarily drawn to
scale.
[0006] FIG. 1 is a schematic front sectional view of the structure
of an example plasma polymerization coating apparatus with
planetary rotation axles arranged on the rotation rack, according
to one or more embodiments of the present disclosure.
[0007] FIG. 2 is a schematic top view of the structure of the
example apparatus shown in FIG. 1, according to one or more
embodiments of the present disclosure.
[0008] FIG. 3 is a flow diagram that illustrates a method for
plasma polymerization.
[0009] FIG. 4 is a block diagram illustrating an example of a
processing system in which at least some operations described
herein can be implemented.
DETAILED DESCRIPTION
[0010] Certain specific embodiments of the present disclosure will
be described in detail below in reference to the related technical
solutions and accompanying drawings. In the following description,
numerous specific details are set forth to provide a thorough
understanding of the presently disclosed technology. In other
embodiments, the techniques described here can be practiced without
these specific details. In other instances, well-known features,
such as specific fabrication techniques, are not described in
detail in order to avoid unnecessarily obscuring the present
technology. References in this description to "an embodiment," "one
embodiment," or the like mean that a particular feature, structure,
material, or characteristic being described is included in at least
one embodiment of the present disclosure. Thus, the instances of
such phrases in this specification do not necessarily all refer to
the same embodiment. On the other hand, such references are not
necessarily mutually exclusive. Furthermore, the particular
features, structures, materials, or characteristics can be combined
in any suitable manner in one or more embodiments. Also, it is to
be understood that the various embodiments shown in the figures are
merely illustrative representations and are not necessarily drawn
to scale.
[0011] As previously mentioned, plasma polymerization coating is
capable of producing results with highly desirable characteristics
and can perform well in certain applications, such as hydrophobic
film coating. However, since the polymer coating tends to be very
thin, it can be difficult to achieve the desired uniformity of the
coating.
[0012] To perform plasma polymerization coating, a substrate to be
treated can be first placed in a vacuum chamber, and then carrier
gas and gaseous organic monomer are dispersed into the vacuum
chamber. The gaseous organic monomer is turned into a plasma state
by discharging electrical power to the monomer to produce various
types of reactive species. Next, additional reactions between the
reactive species and the monomer, or between the reactive species
themselves, take place and form a polymer film on the substrate's
surface. In certain applications such as hydrophobic or oleophobic
film coating, plasma polymerization coating is capable of producing
results with highly desirable characteristics.
[0013] Conventional plasma coating devices are typically equipped
with a rectangular vacuum chamber, and as a result, during the
coating process, the positions of the substrate-carrying platforms
and the substrate placed thereon are typically fixed within the
conventional vacuum chamber. Because different substrates in the
same batch are in different positions in the vacuum chamber, they
are at varying distances from the electrodes, monomer/carrier gas
outlet, vacuum gas outlet, etc. Accordingly, it is inevitable that
the thickness of the coats applied to each substrate vary based on
the different locations of each substrate within the chamber.
Hence, in order to reduce the variation in uniformity within the
same batch, currently available plasma coating devices typically
adopt a vacuum chamber with a small volume and are treated in
small-quantity batches. This method greatly reduces processing
efficiency and increases the cost. Even so, it may still not
produce a satisfactory batch uniformity that meets a client's
requirement. With the rapid expansion of polymer coating
applications, demands for such processing are increasing
rapidly.
[0014] Accordingly, disclosed here are plasma coating apparatus and
techniques that address the technical problems in the existing
plasma coating processes, such as small batch size, low efficiency,
high cost, and poor batch uniformity.
[0015] In the following description, numerous specific details are
set forth such as examples of specific components, circuits, and
processes to provide a thorough understanding of the present
disclosure. Also, in the following description and for purposes of
explanation, specific nomenclature is set forth to provide a
thorough understanding of the present embodiments. However, it will
be apparent to one skilled in the art that these specific details
may not be required to practice the present embodiments. In other
instances, well-known circuits and devices are shown in block
diagram form to avoid obscuring the present disclosure.
[0016] The term "coupled" as used herein means connected directly
to or connected through one or more intervening components or
circuits. Any of the signals provided over various buses described
herein may be time-multiplexed with other signals and provided over
one or more common buses. Additionally, the interconnection between
circuit elements or software blocks may be shown as buses or as
single signal lines. Each of the buses may alternatively be a
single signal line, and each of the single signal lines may
alternatively be buses, and a single line or bus might represent
any one or more of a myriad of physical or logical mechanisms for
communication (e.g., a network) between components. The present
embodiments are not to be construed as limited to specific examples
described herein but rather to include within their scope all
embodiments defined by the appended claims.
Plasma Polymerization Coating Apparatus
[0017] Shown in FIGS. 1 and 2 is a plasma polymerization coating
device 100 according to one or more embodiments of the present
disclosure for applying a plasma polymerization coating to
substrates 115. In an example embodiment, the plasma polymerization
coating apparatus includes vacuum chamber 101, porous electrode
102, radio frequency power source 103, discharge cavity 104, metal
grid 105, pulse power source 106, discharge source 107, discharge
power source 108, carrier gas pipe 109, monomer vapor pipe 110,
tail gas collecting tube 111, rotation rack 112, planetary rotation
shafts 113, planetary rotation platforms 114, substrates 115 to be
treated, vacuum pump 116, controller 117, and rotary motor 118.
Vacuum Chamber
[0018] Vacuum chamber 101 functions as a container where
polymerized plasma may be applied to substrates 115. For purposes
of the present disclosure, the term "vacuum chamber" means a
chamber having a lower gas pressure than what is outside of the
chamber (e.g., as a result of having vacuum pump 116 pumping gas
out of the chamber); the term does not necessarily mean that the
chamber is exhausted to a vacuum state. For the purposes of
discussion herein, vacuum chamber 101 may also be referred to as a
"reaction chamber;" it is a chamber where one or more chemical
reactions described herein (e.g., for implementing the disclosed
plasma coating techniques) take place. In some examples, during the
coating process, vacuum chamber 101 can be first exhausted of gas
to a base pressure around 5 mTorr and then filled with the carrier
gas. After filling vacuum chamber 101 with carrier gas, the air
pressure in the vacuum chamber 101 may rise to around tens of
mTorr. The volume of vacuum chamber 101 may vary depending on the
application, for example, between 50-3000 liters. Examples of the
chamber material may include aluminum alloy or stainless steel.
[0019] Vacuum chamber 101 has a chamber body inner wall along the
perimeter of vacuum chamber 101. The inner wall of vacuum chamber
101 may be characterized by a circular top view cross section with
the same diameter as other top view cross sections, or a polygon
with the same edge length as other top view cross sections. Some
embodiments of said polygon have at least six edges.
[0020] The top cover and the bottom cover of vacuum chamber 101 may
be a flat plate or an arched structure, such as a spherical
segment, a regular polygon, or an oval. In some embodiments, the
structure matches the top view cross section of the chamber body
inner wall of vacuum chamber 101.
Porous Electrodes
[0021] In some embodiments, porous electrode 102 can generate
plasma for pre-treating the surface of the substrate to be coated
by polymerization in subsequent steps. In particular, high
electricity power (e.g., over 600 watts) are continuously
discharged through porous electrode 102 to produce a strong plasma.
The resulting plasma can be used for at least two purposes: (1)
cleaning organic impurities on the substrate surface, such as water
and oil stains, as well as (2) activating organic substrate to form
dangling bonds to facilitate coating deposition and enhance the
binding force between the substrate and the coating. In some
embodiments, this surface plasma pre-treatment via porous electrode
102 is optional.
[0022] In some embodiments, the porous electrode 102 may form a
cylindrical shape or at least divided into two sections of
cylindrical shape, and the porous electrode 102 can be coaxial with
the vacuum chamber 101. The porous electrode 102 can be covered by
holes, and the size of a hole can range between 2 to 30 mm. The
space between holes can range from 2 to 30 mm.
[0023] Porous electrode 102 is installed in vacuum chamber 101 near
or proximal to the inner wall of vacuum chamber 101. Porous
electrode 102 form a porous arched structure within a distance from
the inner wall of vacuum chamber 101. In some embodiments, the
distance from porous electrode 102 to the inner wall of vacuum
chamber 101 can range between 1 to 6 cm.
[0024] The reaction chamber of the plasma polymerization coating
apparatus includes a radio frequency power supply coupled to a
porous electrode. In some embodiments, the radio frequency power
supply is configured to provide an electrical charge to the porous
electrodes to produce a treatment plasma to remove impurities from
the surface of the one or more substrates. The radio frequency
power supply can be coupled to the controller to receive a radio
frequency control signal that controls the power output to the
porous electrodes.
[0025] For example, porous electrode 102 may be connected with a
radio frequency (e.g., high frequency) power source 103. When power
from radio frequency power source 103 is applied to porous
electrode 102, plasma is generated for removing impurities from the
surface of substrates 115. The power of radio frequency power
source 103 may be configured to be between 15-1500 watts. Note
that, in some embodiments, the plasma generated during power
discharge can be used for substrate surface cleaning and
pretreatment. According to some embodiments, the gas that is used
to produce plasma for cleaning (e.g., pretreating the surface of
the substrate) contains oxygen.
[0026] As mentioned above, radio frequency power source 103 is
applied to porous electrode 102 to generate a plasma for removing
impurities from the surface of substrates 115. In one or more
embodiments, radio frequency power source 103 is used for driving
the electrical discharge even when and if the electrodes are
covered by dielectric coatings; in comparison, direct current (DC)
power sources or low frequency power sources (e.g., under 50 Hz) do
not have this advantage. The applicable high frequency may range
from tens of kHz to several GHz. Typical high frequencies include
40 kHz, 13.56 MHz and 2.45 GHz, etc. The choice of the frequency
may depend on the technical requirement or specification, the
existing products' material characteristics, and the cost. It is
noted that a person having ordinary skill in the art of dielectric
coating should be able to select a suitably high frequency to
perform the coating of a specific material.
[0027] Additionally, because electrodes of radio frequency power
source 103 alternates in polarity, the electrodes are identified as
the driving electrodes and the grounding electrodes instead of the
cathode and anode electrodes. In one or more embodiments of the
disclosed apparatus, porous electrode 102, which connects to the
output of the radio frequency power source 103, is the driving
electrode. In at least some of these embodiments, the wall of
vacuum chamber 101 can act as the grounding electrode.
Additionally, or alternatively, tail gas collecting tube 111 can
also act as the grounding electrode.
Discharge Cavity
[0028] The reaction chamber of the plasma polymerization coating
apparatus includes a dispersal mechanism positioned around a
perimeter of the reaction chamber. In some embodiments, the
reaction chamber is configured to disperse reactive species into
the reaction chamber in a substantially even manner. The dispersal
mechanism can be configured to disperse reactive species toward the
central axis of the reaction chamber, such that the reactive
species form a polymeric coating on surfaces of the one or more
substrates. The dispersal mechanism includes a discharge cavity 104
and a metal grid 105 configured to create a pressure differential
between the discharge cavity and the reaction chamber. The metal
grid 105 may also be configured to reduce or prevent gas backflow
from the reaction chamber to the discharge cavity.
[0029] Discharge cavity 104 is connected to vacuum chamber 101.
Discharge cavity 104 includes discharge source 107 coupled to a
discharge power source 108 to produce plasma for polymerization.
One end of discharge source 107 can be connected to a discharge
power source 108 and with a carrier gas pipe 109. The other end of
the carrier gas pipe 109 is connected to a carrier gas source.
Monomer vapor pipe 110 can be connected to vacuum chamber 101, and
an outlet thereof can be located in front of discharge cavity 104.
The other end of monomer vapor pipe 110 can be connected to a
monomer vapor source.
[0030] In some embodiments, discharge cavity 104 may form a
cylindrical shape, and can be made from materials including, for
example, aluminum, carbon steel, or stainless-steel material. The
diameter of discharge cavity 104 can range from 5 to 20 cm, the
depth from 3 to 15 cm, and the distance between two neighboring
discharge cavities from 7 to 40 cm. The axes of discharge cavity
104 may be orthogonal to the axis of the vacuum chamber 101 to
provide the largest opening area to the plasma to travel to the
vacuum chamber 101. In alternate embodiments, under the pressure of
several Pascal in the process, free diffusion dominates the plasma
propagation, so the orientation of the discharge cavity has little
importance.
[0031] No specific requirement for the size ratio between the
discharge cavity and the vacuum chamber; rather, it is determined
by practice. For example, a single, relatively large discharge
cavity 104 allows for dispersal of a greater volume of carrier
gas-based plasma. However, a single discharge cavity provides for
carrier gas-based plasma from a single direction into the vacuum
chamber 101 and thus does not provide adequate uniformity of the
polymerization coating. Conversely, the number and distribution of
the discharge cavities is determined by the desired coating
uniformity. Smaller discharge cavities 104 that are uniformly
distributed provide greater uniformity of the applied coating.
However, too many small discharge cavities present technical
limitations and increased costs. The final design should be
optimized to provide a balance of uniformity, technical
limitations, and cost.
[0032] Discharge cavity 104 is provided with carrier gas pipe 109
that injects carrier gas. The carrier gas gets ionized in discharge
cavity 104 and becomes plasma (i.e., a mixture of positive ions and
electrons produced by ionization). The carrier gas transfers energy
to the monomer vapor to activate the monomer vapor to a high-energy
state (i.e., the monomer vapor become activated species). In some
embodiments, the carrier gas may even cause some chemical bonds of
the monomer to break and form reactive particles such as free
radicals.
[0033] When the carrier gas encounters an electrical discharge from
discharge power source 108 at discharge source 107, the carrier gas
form a plasma. During the coating process, discharge cavity 104
discharge at a relatively low power to generate weak plasma. The
weak plasma is intermittently released into vacuum chamber 101 by
metal grid 105 to initiate monomer polymerization and deposition on
the surface of the substrate to form a polymerization coating.
Depending on the embodiment, discharge source 107 can be a lamp
filament, an electrode, an induction coil, or a microwave antenna.
Discharge source 107 can have discharge power ranging from 2 to 500
W.
[0034] Depending on the embodiment, the porous electrode 102 and
discharge cavity 104 are independent of each other, and they can be
operated either together or separately. In some embodiments, during
the polymeric coating process, the porous electrode 102 is used for
(1) pre-treatment of the samples and (2) post-cleaning of the
chamber. That is to say, in these embodiments, the porous electrode
102 do not operate during coating process. On the other hand,
according to one or more embodiments, discharge cavity 104 is
mainly used for coating. Additionally, or alternatively, discharge
cavity 104 can also be used for post-cleaning of the cavities
themselves.
[0035] For purposes of the disclosure here, the term "strong
plasma" is associated with higher power relative to the plasma and
discharge power of discharge cavity 104. The typical discharge
power for strong plasma can be several hundred watts, and the
plasma density is between 10.sup.9-10.sup.10 /cm.sup.3. The term
"weak plasma" with lower power relative to the plasma and discharge
power of the porous electrode 102. Typical discharge power for weak
plasma can be several watts to tens of watts, and the plasma
density is between 10.sup.7-10.sup.8 /cm.sup.3. Example materials
for the monomer containing acrylate, such as ethoxylated
trimethylolpropane triacrylate, or perfluorocyclohexyl methyl
acrylate.
Metal Grid
[0036] Under a general vacuum condition, a pressure gradient may
exist along the way from the gas inlet to the exhaust exit, even if
no mesh exists. This can be measured by vacuum meters at different
positions of the vacuum chamber 101. Therefore, the strategic
placement of the metal grid 105, such as introduced here, can
increase the pressure difference between discharge cavity 104 and
the main vacuum chamber 101 by hindering the carrier gas flow.
Generally speaking, the pressure difference may increase with the
number of layers, the mesh number, and transmissivity of the grid.
In some embodiments, each layer may have different characteristics.
For example, one layer may have smaller openings while another
layer has larger openings. Additionally, there may be a preferred
order for the gates (e.g., the carrier gas-based plasma moves
through a gate with larger openings before moving through a gate
with smaller openings).
[0037] In some embodiments, the number of layers of metal grid 105
can range from 2 to 6. Metal grid 105 can be made of materials
including, for example, stainless steel or nickel. Metal grid 105
ranges from 100 to 1,000 mesh, and the transmissivity can range
from 25% to 40%. Metal grid 105 increases the pressure differential
to reduce or to prevent backflow of carrier gas from vacuum chamber
101 to discharge cavity 104. In some embodiments, at least two
layers of metal grid 105 are provided at the connecting positions
of the discharge cavities and the inner walls of vacuum chamber
101. Metal grid 105 is insulated from the inner wall of vacuum
chamber 101.
[0038] Metal grid 105 is arranged at the connecting positions of
the discharge cavities and the inner walls of vacuum chamber 101.
In some embodiments, at least two discharge cavities 104 are
provided on an outer wall of the vacuum chamber 101 in a sealed
manner. In some examples, the porous electrode 102 and the
discharge cavities are able to discharge together or separately
according to the needs of the specific processes.
[0039] In one or more embodiments, a pulse power source 106 is
coupled to the metal grid 105. The pulse power source 106 can be
configured to provide a positive electrical charge to the metal
grid 105 in pulses, wherein plasma in the discharge cavity is
blocked from entering the reaction chamber during a pulse-off
period. The plasma in the discharge cavity can be passed through to
the reaction chamber during a pulse-on period.
[0040] As a result, when power is applied, the plasma generated in
discharge cavity 104 is released into vacuum chamber 101. For
example, the plasma is blocked (at least partially) by metal grid
105 within discharge cavity 104 during a period of pulse-off (i.e.,
when no power is applied to metal grid 105), and the plasma can
pass through metal grid 105 during a period of pulse-on (i.e., when
power is applied to metal grid 105) into vacuum chamber 101. In
some embodiments, pulse power source 106 outputs a positive pulse
with the following parameters: peak is from 20 to 140 V, pulse
width is from 2 .mu.s to 1 ms, and repeat frequency is from 20 Hz
to 10 kHz.
[0041] Similarly, the metal grid 105 can place a hindering effect
on the reverse-diffusion of the monomer vapor from the vacuum
chamber 101 to discharge cavity 104. Moreover, since the pressure
in the discharge cavity 104 can be higher than that in the vacuum
chamber 101, the monomer vapor may not easily move from the vacuum
chamber 101 to the discharge cavity 104 through reverse-diffusion,
thereby preventing the monomer vapor from being excessively
decomposed and destructed by the continuously discharged plasma in
the discharge cavity 104. In some embodiments, the metal grid 105
can help create a pressure differential, so as to reduce or to
prevent the carrier gas from backflowing.
Monomer Vapor Pipe
[0042] Monomer vapor pipe 110 can be connected to vacuum chamber
101, and an outlet can be located adjacent to discharge cavity 104.
The other end of monomer vapor pipe 110 is connected to a monomer
vapor source. The distance between the outlet of monomer vapor pipe
110 and discharge cavity 104 can range from 1 to 10 cm. In one
embodiment, the monomer vapor pipe 110 is directly connected to
vacuum chamber 101 rather than within discharge cavity 104. This is
to avoid the monomer vapor from being exposed to strong electrical
charges from the discharge cavity 104.
[0043] In some embodiments, the monomer vapor is not discharged by
the porous electrode 102; in these embodiments, the porous
electrode 102 may be designed to only operate during the
pre-treatment period when no monomer vapor is fed in into vacuum
chamber 101. However, during the coating period, the monomer vapor
may be partly discharged in and out of discharge cavity 104.
Discharge of the monomer vapor may be undesirable because it may
lead to excess breakdown of the monomer molecules. Thus, the
monomer vapor pipe 110 is designed directly connected to vacuum
chamber 101 to avoid the monomer vapor from being strongly
discharged in discharge cavity 104 when passing through it. Rather,
the carrier gas-based plasma is intermittently released from the
discharge cavities to activate the monomer vapor with minimized
discharge of it.
Tail Gas Collecting Tube
[0044] The reaction chamber of the plasma polymerization coating
apparatus includes a collecting tube positioned along the central
axis of the reaction chamber. In some embodiments, the reaction
chamber is operable to have an air pressure lower than the reaction
chamber to collect excess reactive species in the atmosphere of the
reaction chamber at a controlled exhaust rate. For example, in some
embodiments, tail gas collecting tube 111 is vertically positioned
through the center of vacuum chamber 101. One end of the tail gas
collection tube 111 is connected to vacuum pump 116 and holes are
distributed along the wall of tail gas collection tube 111. Gas and
plasma in vacuum chamber 101 enters the tail gas collection tube
111 via the holes on the tail gas collection tube 111, and then is
discharged from vacuum chamber 101 by vacuum pump 116. The power of
vacuum pump 116 may range between 3-50 kW, and the pumping rate may
range between 600-1200 m.sup.3/h. The inner diameter of tail gas
collecting tube 111 can range from 25 to 100 mm. In some
embodiments, holes can be evenly provided on the wall of tail gas
collecting tube 111. The hole size can range from 2 to 30 mm, and
the space between holes can range from 2 to 100 mm.
Rotation Rack
[0045] The reaction chamber of the plasma polymerization coating
apparatus includes a primary rotation rack operably coupled to a
primary rotation shaft and configured to rotate along a central
axis. The primary rotation rack includes one or more arms extending
from the primary rotation shaft and away from the central axis. The
primary rotation rack may include one or more rack layer, each rack
layer holding a plurality of substrate platforms from the one or
more substrate platforms.
[0046] The primary rotation rack may be a rotation rack 112 for
moving a substrate to be treated within vacuum chamber 101. A
rotation rack 112 may be coaxial with the central axis of vacuum
chamber 101 and rotate along the central axis using a rotary motor
118. The power of rotary motor 118 may be between 30-3000 W. In
some embodiments, the primary rotation shaft may be coupled or
otherwise integrated with tail gas collection tube 111. In yet
other embodiments, the tail gas collection tube 111 may also
function as the primary rotation shaft.
[0047] The reaction chamber of the plasma polymerization coating
apparatus also includes a secondary rotation rack operably coupled
to a secondary rotation shaft. The reaction chamber is configured
to rotate on a secondary axis that is distal from the central axis,
wherein the secondary rotation shaft is coupled to an arm of the
one or more arms extending from the primary rotation shaft. The
rotation of the primary rotation rack along the central axis and
the rotation of the secondary rotation rack along the secondary
axis can provide the same rate of spatial movement for each of the
one or more substrates during the coating process in order to
achieve uniform coating.
[0048] The secondary rotation rack can be one of the planetary
rotary shafts 113 that is secured on rotation rack 112. The
planetary rotary shafts 113 may support planetary rotation racks
114 that rotate along a secondary axis which is coaxial with
planetary rotary shafts 113. Additionally, the planetary rotary
shafts 113 may be distal to the central axis of vacuum chamber 101.
In some embodiments, the number of the planetary rotary shafts 113
may be between 2 to 8, and the number of the planetary rotation
platforms 114 may be between 1 to 10.
[0049] The reaction chamber of the plasma polymerization coating
apparatus also includes one or more substrate platforms configured
to carry the one or more substrates that are to receive the plasma
polymerization coating. Each substrate platform can be located on
the secondary rotation rack. The substrate platforms may be
planetary rotation platforms 114. Planetary rotation platforms 114
allow for placement of substrates 115 to be treated such that the
substrates 115 are in continuous movement along vacuum chamber 101.
The planetary rotation platforms 114 are secured along planetary
rotary shafts 113, wherein each planetary rotation platforms 114
rotates around their own planetary rotation axes while the
planetary rotation axes rotate around the central axis of vacuum
chamber 101. The continuous movement allows for uniform plasma
polymerization treatment on the surface of substrates 115.
[0050] Note that, even though there is no particular directional
requirement for the rotation of planetary rotation shafts 113
versus the rotation of rotation rack 112, overall the rotations
should be suitably tuned and adjusted (e.g., for the sake of
rotational balance and stability) such that substantially all
samples can experience the same spatial movement during the coating
process in order to achieve uniform coating. Similarly, there is no
particular limitation on the rotational speed; however, it is
apparent that an overly fast rotational speed is unfavorable
because of the unnecessary power consumption, part wear, as well as
instability of the platform.
Polymerization Controller
[0051] The reaction chamber of the plasma polymerization coating
apparatus also includes a controller configured to transmit a
rotation rate control signal to a rotation motor to rotate the
primary rotation shaft and primary rotation rack at a controlled
rotation rate. The controller may be implemented as controller 117
for providing control signals to various components of the
planetary rotary rack device. Such control signals allow the device
to regulate the plasma polymerization process applied to substrates
115.
[0052] Controller 117 may transmit a rotation rate signal to rotary
motor 118. The rotation rate signal indicates the rotational speed
that rotary motor 118 should operate. Regulating the rotational
speed may determine the rate that substrates 115 traverse vacuum
chamber 101. For example, a faster rotational speed may allow the
substrate to traverse vacuum chamber 101 relatively quickly.
Therefore, any imbalance of the concentration of plasma in the
vacuum chamber 101 would be negated because substrates 115 would be
rapidly exposed to both ends of the plasma concentration
gradient.
[0053] The dispersal mechanism is communicatively coupled to the
controller 117 to receive a dispersal control signal from the
controller to control the dispersal rate of the reactive species in
a substantially even manner on the one or more substrates. The
dispersal control signal controls the dispersal rate of the
reactive species by regulating the applied electrical power to the
dispersal mechanism and/or by regulating the rate of gas that
enters the dispersal mechanism for polymerization. In some
embodiments, the dispersal rate control signal adjusts the
dispersal rate to account for the density decrease in the reactive
species within the reaction chamber resulting from the deposition
of the reactive species on to the one or more substrates and the
density increase within the reactive species in the reaction
chamber resulting from the reactive species converging toward the
center of the chamber such that the density of reactive species
across the reaction chamber is uniform.
[0054] Specifically, controller 117 may transmit a dispersal
control signal to discharge power source 108 to indicate the power
that should be applied to discharge source 107. Regulating the
power applied to discharge source 107 allows for control of the
rate in which plasma is generated in discharge cavity 104.
Therefore, a change in the power to discharge source 107 may affect
a change in the density of plasma as well as the properties of the
plasma in vacuum chamber 101 and ultimately the thickness of the
plasma applied to substrates 115.
[0055] In some embodiments, the pulse power source receives a pulse
control signal from the controller, the pulse control signal
regulating the power and frequency of the positive electrical
charge. Specifically, controller 117 may transmit a pulse control
signal to pulse power source 106. The pulse control signal
indicates the power to be applied by pulse power source 106 to
metal grid 105. Specifically, pulse power source 106 applies a
positive electrical pulse bias on metal grid 105, thus allowing the
plasma generated in discharge cavity 104 to be intermittently
released into vacuum chamber 101. For example, the plasma can be
blocked by metal grid 105 within the discharge cavity 104 during a
period of pulse-off, and the plasma can pass through metal grid 105
during a period of pulse-on into the vacuum chamber 101. Using this
mechanism, the pulse control signal controls the duration and
frequency in which plasma is allowed to enter from discharge cavity
104 to vacuum chamber 101.
[0056] Controller 117 may transmit a radio frequency power control
signal to radio frequency power source 103. The radio frequency
power signal indicates to radio frequency power source 103 when to
apply power to porous electrode 102 to generate plasma for removing
impurities from substrates 115. For example, controller 117 may
transmit a radio frequency power control signal to power on radio
frequency power source 103 at the start of a plasma polymerization
process to pre-treat substrates 115 or after the plasma has been
applied to the substrate for post-treatment of substrates 115 and
vacuum chamber 101.
[0057] Controller 117 also transmits various control signals for
regulating the introduction and evacuation of gases into the
planetary rotary rack device. For example, controller 117 transmits
a carrier gas control signal to carrier gas pipe 109. This control
signal indicates the rate in which carrier gases should be
introduced into discharge cavity 104. Controller 117 also transmits
a monomer vapor control signal to monomer vapor pipe 110. The
monomer vapor control signal indicates the rate in which monomer
vapor gases are introduced into vacuum chamber 101.
[0058] In some embodiments, a collecting tube is communicatively
coupled the controller to receive an exhaust rate control signal
from the controller to control the exhaust rate of the reactive
species. For example, controller 117 provides a tail gas control
signal to tail gas collection tube 111. This signal controls the
rate in which the atmosphere is evacuated from vacuum chamber 101.
In some embodiments, the controller transmits the exhaust rate
control signal to adjust the rate the reactive species is exhausted
from the reaction chamber. The exhaust rate is controlled to
account for two factors contributing to the density of the reactive
species within the reaction chamber: (1) the density decrease in
the reactive species within the reaction chamber resulting from the
deposition of the reactive species on to the one or more substrates
and (2) the density increase within the reactive species in the
reaction chamber resulting from the reactive species converging
toward the center of the chamber such that the density of reactive
species across the reaction chamber is uniform.
[0059] Controller 117 may be microcontrollers, general-purpose
processors, or may be application-specific integrated circuitry
that provides arithmetic and control functions to implement the
techniques disclosed herein. The processor(s) may include a cache
memory (not shown for simplicity) as well as other memories (e.g.,
a main memory, and/or non-volatile memory such as a hard-disk drive
or solid-state drive. In some examples, cache memory is implemented
using SRAM, main memory is implemented using DRAM, and non-volatile
memory is implemented using Flash memory or one or more magnetic
disk drives. According to some embodiments, the memories may
include one or more memory chips or modules, and the processor(s)
on Controller 117 may execute a plurality of instructions or
program codes that are stored in its memory.
[0060] FIG. 2 is a schematic top view of the structure of the
plasma polymerization coating device 100 shown in FIG. 1, according
to one or more embodiments of the present disclosure.
[0061] Overall, the present disclosure has various beneficial
effects. First, the device employs a central axis symmetrical
vacuum chamber 101 structure to maintain the uniformity of space
polymerization reactive material density. The vacuum chamber 101
adopts a mechanism in which the gas is fed via the side wall,
transported radially, and discharged along the direction of central
axis.
[0062] In one or more embodiments, the carrier gas pipe 109 is
provided in each discharge cavity 104 and with an outlet. A carrier
gas can enter the discharge cavities via carrier gas pipe 109, and
then diffuse into the vacuum chamber 101 via the multilayer metal
grid 105. The monomer vapor pipe 110 is provided with an outlet in
front of discharge cavity 104 in the vacuum chamber 101. A monomer
vapor gas enters the vacuum chamber 101 via monomer vapor pipe 110.
In addition, a tail gas collection tube 111 is coaxially provided
the vacuum chamber 101 along the axis of the vacuum chamber 101.
The tail gas collection tube vertically penetrates through the
vacuum chamber 101. One end of the tail gas collection tube 111 is
connected to vacuum pump 116, and holes are evenly distributed on
the wall of the tube. A tail gas enters the tail gas collection
tube via the holes on the tail gas collection tube, and then is
discharged from the vacuum chamber 101 by vacuum pump 116.
[0063] In the foregoing approach, in which the gas is fed via the
side wall, transported radially, and discharged along the direction
of central axis, the gas transport process takes place in a
convergent manner, which can facilitate an increased stability of
reactive species concentration in the space polymerization
reaction, and a more evenly distribution of reactive species. In
one embodiment, the process starts by generating polymerization
reaction reactive species when the monomer vapor comes into contact
with the carrier gas-based plasma in the vicinity of discharge
cavity 104. Activated by the carrier gas, the generated
polymerization reactive species are radially dispersed towards the
axis of the vacuum chamber 101. As substrates 115 are rotated
within vacuum chamber 101, the amount of the polymerization
reaction reactive species gradually decreases due to continuous
consumption. Simultaneously, the polymerization reaction reactive
species also gradually converge, which can compensate for the
foregoing decrease in the amount of the polymerization reaction
reactive species. In this way, the concentration of the
polymerization reaction reactive species can remain stable. The
bulk density of the reactive species in the vacuum chamber 101 can
remain unchanged, and thus the batch treatment can enjoy good
uniformity.
[0064] In other words, the reactive species discharge mechanisms
and the collecting tube can be collectively configured in a way
such that, a density decrease in the reactive species due to
consumption of the reactive species can be substantially equal to a
density increase in the reactive species due to the reactive
species converging toward the collecting tube. Therefore, the
coordinated operation of the reactive specifies discharge mechanism
and tail gas collecting tube 111 can provide uniform density of the
reactive species across vacuum chamber 101 and onto substrates 115.
Specifically, in some implementations, a discharge rate of the
discharge mechanism can be adjusted (e.g., via controlling the
applied electrical power and/or an amount of gas) together with an
exhaust rate of the collecting tube (e.g., via adjusting the power
of vacuum pump) such that a substantially uniform density of the
reactive species across the vacuum chamber 101 can be achieved. In
many embodiments, the aforesaid collective adjustment of the
discharge mechanism and the collecting tube corresponds to the
shape of the cross section of the inner side wall of a given vacuum
chamber 101. That is to say, in these embodiments, the combination
of the discharge rate of the discharge mechanism and the exhaust
rate of the collecting tube is preferably tailored to match the
particular shape (e.g., a circle, or a polygon) of the given vacuum
chamber 101 so as to achieve the substantially uniform density of
the reactive species.
[0065] As compared to conventional coating devices and technology,
the difference in substrate coating thickness of the same batch
treatment in the conventional coating devices can be greater than
30%, while the difference in substrate coating thickness of the
same batch treatment in the disclosed devices can be smaller than
10%.
[0066] Second, the device also employs rotation rack 112 to
significantly improve the uniformity of each substrate coating. In
one or more embodiments, the vacuum chamber 101 is provided with
rotation rack 112. The substrate platforms 114 on rotation rack 112
are able to rotate or make planetary rotation movement in the
vacuum chamber 101. In particular, the disclosed planetary rotary
movement mechanism provides that the substrate platforms 114 each
rotate around their own planetary rotation axes while making a
coaxial revolutionary movement along the substrate platform and
around the central axis of the vacuum chamber 101. A substrate to
be treated can be placed on a substrate platform. The introduced
planetary rotary movement allows the spatial position and
orientation of each substrate treated to change continuously during
the process of the treatment, such that all of the spatial
positions of different substrates in the process of coating
treatment can be substantially the same, thereby eliminating the
difference in coating due to different spatial positions of
different substrates in the existing technology. In this way, the
treatments of different substrate become the same, and accordingly,
the introduced techniques may achieve the same coating effects and
better uniformity for substrates of different locations in the same
batch.
[0067] Third, the device is able to greatly increase the volume of
the vacuum chamber 101, and significantly improve the treatment
efficiency. Due to the improvements in the structures of vacuum
chamber 101 and rotation rack 112, coating film thickness
uniformity can be greatly improved for the treatment in the same
batch. In addition, the vacuum chamber 101 volume can be expanded
by 5 to 6 times. Accordingly, the batch treatment quantity and
treatment efficiency have been greatly increased.
[0068] In conclusion, the device according to the present
disclosure can effectively protect the monomer vapor from being
decomposed and destructed so as to obtain a polymer coating of very
good quality.
Plasma Polymerization Coating Method
[0069] One aspect of the techniques disclosed herein includes a
reactive species discharge method. In one embodiment, the method
begins by positioning a substrate on a substrate platform located
in a reaction chamber. The atmosphere of the reaction chamber is
evacuated by a vacuum pump via an air exhaust port of a collecting
tube positioned along a central axis of the reaction chamber. The
method proceeds by rotating, by a rotation motor, a primary
rotation rack coupled to a primary rotation shaft. In some
embodiments, the primary rotation rack is configured to rotate
along the central axis. Then, a carrier gas is discharged to a
discharge cavity via an inlet valve. The carrier gas can facilitate
a reaction between the substrate and the reactive species. The
method continues by discharging, monomer vapor into the reaction
chamber using a feeding port. The method creates, the reactive
species by polymerizing the monomer vapor in the reaction chamber
using carrier gas. The method then deposits the reactive species
onto the surface of the substrate to form a polymer coating.
[0070] FIG. 3 is a flowchart illustrating an exemplary reactive
species discharge method 300. Method 300 controls and coordinates
the various components of the plasma polymerization coating device
100 (e.g., controller 117, FIG. 1).
[0071] In step 301, substrates 115 are placed within the reaction
chamber. In some embodiments, substrates 115 are placed on
substrate platforms 114 as depicted in FIGS. 1 and 2. The placement
of substrates 115 on substrate platforms 114 facilitates the
movement of the substrates 115 across vacuum chamber 101 during the
plasma polymerization coating process. By traveling around the
different areas of the vacuum chamber 101, the negative effects of
plasma density variations are reduced or eliminated to allow for a
more even plasma coating on the substrate.
[0072] In step 302, controller 117 transmits control signals to
vacuum pump 116 to evacuate the atmosphere within vacuum chamber
101. This process ensures that the atmosphere does not interfere
with the plasma polymerization process and facilitates plasma
polymerization processes that require a vacuum. In some examples,
vacuum pump 116 is coupled to tail gas collecting tube 111 to
create a negative atmospheric pressure in tail gas collecting tube
111 relative to the atmospheric pressure of vacuum chamber 101. The
negative atmospheric pressure creates a flow of gases out of vacuum
chamber 101. Controller 117 may transmit control signals to vacuum
pump 116 to control the timing, power, and other operational
parameters used for evacuating the atmosphere.
[0073] In step 303, the method includes the step of configuring, by
a controller, the rotation rate of the rotation motor to provide
the same rate of spatial movement for each of the one or more
substrates during the coating process in order to achieve uniform
coating. Specifically, controller 117 transmits control signals to
rotation rack 112 containing substrates 115 for plasma
polymerization coating. Upon receiving the control signals,
rotation rack 112 can rotate to cause the substrates 115 to rotate
within vacuum chamber 101 in accordance with various embodiments of
the invention. In some embodiments, rotation rack 112 contains
planetary rotation shafts 113 and substrate platforms 114 for
holding substrates 115 undergoing the plasma polymerization
process. The rotation motor 118 generates the rotation motion of
rotation rack 112. Controller 117 may transmit control signals to
rotary motor 118 that control the timing, duration, and rate of the
rotation.
[0074] In step 304, the reactive species discharge method includes
the step of rotating a secondary rotation rack located on an arm
extending from the primary rotation rack. In some embodiments, the
secondary rotation rack rotates on a secondary axis different from
the central axis. Specifically, controller 117 transmits control
signals to planetary rotation shaft 113. The control signals cause
planetary rotation shaft 113 to independently rotate along a
secondary axis in accordance with various embodiments of the
invention. The additional rotation provides for a wider range of
movement of substrates 115 within vacuum chamber 101. This allows
for additional mitigation of negative effects caused by plasma
density variations by further changing the position and orientation
of each substrate 115 to be treated.
[0075] In step 305, controller 117 transmits control signals to
carrier gas pipe 109 to cause it to introduce carrier gas into
discharge cavity 104 to activate the monomer vapor. When the
carrier gas is introduced into discharge cavity 104, an electrical
charge is applied by discharge power source 108 to discharge source
107. Due to the electrical charge, the carrier gas gets ionized in
discharge cavity 104 and become plasma (i.e., a mixture of positive
ions and electrons produced by ionization). In some embodiments,
the carrier gas is continually introduced into discharge cavity 104
and becomes plasma throughout the polymerization process until step
309. Controller 117 may transmit control signals that control the
timing and amount of carrier gas that is introduced into discharge
cavity 104 as well as the timing and power applied by discharge
power source 108 to discharge source 107.
[0076] In step 306, the method includes the step of generating, by
an electrode coupled to a radio frequency power source, a treatment
plasma to remove impurities from the surface of the one or more
substrates prior to discharging the reactive species to the
reaction chamber. A treatment plasma may also be generated after
the reactive species is deposited on the surface of the substrate.
Specifically, controller 117 transmits control signals to radio
frequency power source 103 to generate an electrical charge that
generates plasma in vacuum chamber 101. The plasma is generated to
remove impurities from substrates 115 undergoing plasma
polymerization. Additionally, the plasma may activate the surface
of substrate 115 to allow binding between the surface of substrate
115 and the plasma to form the polymerization plasma coating. In
some embodiments, a carrier gas may be introduced from carrier gas
pipe 109 to propagate the plasma throughout vacuum chamber 101.
Controller 117 may transmit control signals that control the
timing, power, and other operational parameters to radio frequency
power source 103 to porous electrode 102. In some examples,
continuous flow of carrier gas may occur during this step.
[0077] In step 307, a reactive species is generated for application
to the surface of substrates 115 undergoing plasma polymerization.
A reactive species is generated by activating the monomer vapor. A
controller configures the polymerization of the monomer vapor by
regulating the applied electrical power to the dispersal mechanism
and/or by regulating the rate of gas that enters the dispersal
mechanism for polymerization. In one embodiment, controller 117
transmits control signals to monomer vapor pipe 110 to introduce
monomer vapor into vacuum chamber 101. Controller 117 also
transmits control signals to discharge power source 108 to regulate
the timing and amount of power to apply to discharge source 107.
When power is applied from discharge power source 108 to discharge
source 108, the carrier gas in discharge cavity 104 becomes plasma.
This provides a mechanism to control when the discharge cavity 104
produces the plasma.
[0078] Additionally, controller 117 may provide control signals to
pulse power source 106 to regulate the power applied to metal grid
105. Metal grid 105 is coupled to pulse power source 106 and
arranged at the connecting positions of the discharge cavities and
the inner walls of vacuum chamber 101. Metal grid 105 regulates the
flow of the plasma generated in step 305 that enters vacuum chamber
101 and the backflow of carrier gas into discharge cavity 104. In
some embodiments, controller 117 may provide control signals that
control the timing and amount of carrier gas that is introduced
into discharge cavity 104.
[0079] Specifically, when power is applied to metal grid 105,
plasma can pass through metal grid 105, and when power is not
applied to metal grid 105, plasma is blocked from passing through
the metal grid 105. When the plasma travels through metal grid 105
into vacuum chamber 101, the plasma transfers energy to the monomer
vapor to activate the monomer vapor to a high-energy state (i.e.,
the monomer vapor become activated species). In some embodiments,
the carrier vapor may even cause some chemical bonds of the monomer
to break and form reactive particles such as free radicals. Also,
in some examples, continuous flow of carrier gas may occur during
this step.
[0080] In step 308, the reactive species created in step 307 is
deposited to the surface of substrates 115 undergoing plasma
polymerization. Specifically, the polymerization reaction reactive
species is generated from monomer vapor when the monomer vapor
comes into contact with the plasma released in step 307 from
discharge cavity 104. Activated by the carrier gas plasma, the
generated polymerization reactive species are radially dispersed
towards the axis of the vacuum chamber 101 and onto substrates 115.
In some embodiments, after the reactive species is introduced to
the vacuum chamber 101, the vacuum chamber 101 will have a
combination of ionized species, free electrons, free radicals,
excited molecules or atoms, and unchanged gas.
[0081] In step 309, the reactive species discharge method includes
the step of collecting excess reactive species in the atmosphere of
the reaction chamber by reducing the air pressure at the collecting
tube to be lower than the air pressure of the reaction chamber. The
exhaust rate of the vacuum pump is configured to account for: (1)
the density decrease in the reactive species within the reaction
chamber resulting from the deposition of the reactive species on to
the substrate and (2) the density increase within the reactive
species in the reaction chamber resulting from the reactive species
converging toward the center of the chamber such that the density
of the reactive species across the reaction chamber is uniform.
Specifically, controller 117 transmits control signals to vacuum
pump 116 to evacuate excess gas, plasma, and reactive species from
the atmosphere of vacuum chamber 101. Vacuum pump 116 is coupled to
tail gas collecting tube 111 to create a negative atmospheric
pressure in tail gas collecting tube 111 relative to the
atmospheric pressure of vacuum chamber 101. The negative
atmospheric pressure creates a flow of gases out of vacuum chamber
101.
[0082] In some embodiments, step 306 (i.e., the pretreatment step)
should be longer than one planetary rotation cycle, so that all the
substrate samples have traveled to the closest point to the porous
electrode to accept plasma. For example, step 306 may require
between 1-30 minutes. In comparison, step 308 is determined by the
film thickness required. In general, step 308 should take longer
than the other steps. For example, step 306 may require between
20-300 minutes. Finally, step 309 should be executed until excess
monomers are exhausted from the chamber. For example, step 309 may
require between 1-10 minutes.
Processing System
[0083] FIG. 4 is a block diagram illustrating an example of a
processing system 400 in which at least some operations described
herein can be implemented. For example, some components of the
processing system 400 may be implemented in a controller device
(e.g., controller 117 of FIGS. 1 and 2).
[0084] The processing system 400 may include one or more central
processing units ("processors") 402, main memory 406, non-volatile
memory 410, network adapter 412 (e.g., network interface), video
display 418, input/output devices 420, control device 422 (e.g.,
keyboard and pointing devices), drive unit 424 including a storage
medium 426, and signal generation device 430 that are
communicatively connected to a bus 416. The bus 416 is illustrated
as an abstraction that represents one or more physical buses and/or
point-to-point connections that are connected by appropriate
bridges, adapters, or controllers. The bus 416, therefore, can
include a system bus, a Peripheral Component Interconnect (PCI) bus
or PCI-Express bus, a HyperTransport or industry standard
architecture (ISA) bus, a small computer system interface (SCSI)
bus, a universal serial bus (USB), IIC (I2C) bus, or an Institute
of Electrical and Electronics Engineers (IEEE) standard 1394 bus
(also referred to as "Firewire").
[0085] The processing system 400 may share a similar computer
processor architecture as that of a desktop computer, tablet
computer, personal digital assistant (PDA), mobile phone, game
console, music player, wearable electronic device (e.g., a watch or
fitness tracker), network-connected ("smart") device (e.g., a
television or home assistant device), virtual/augmented reality
systems (e.g., a head-mounted display), or another electronic
device capable of executing a set of instructions (sequential or
otherwise) that specify action(s) to be taken by the processing
system 400.
[0086] While the main memory 406, non-volatile memory 410, and
storage medium 426 (also called a "machine-readable medium") are
shown to be a single medium, the term "machine-readable medium" and
"storage medium" should be taken to include a single medium or
multiple media (e.g., a centralized/distributed database and/or
associated caches and servers) that store one or more sets of
instructions 428. The term "machine-readable medium" and "storage
medium" shall also be taken to include any medium that is capable
of storing, encoding, or carrying a set of instructions for
execution by the processing system 400.
[0087] In general, the routines executed to implement the
embodiments of the disclosure may be implemented as part of an
operating system or a specific application, component, program,
object, module, or sequence of instructions (collectively referred
to as "computer programs"). The computer programs typically
comprise one or more instructions (e.g., instructions 404, 408,
428) set at various times in various memory and storage devices in
a computing device. When read and executed by the one or more
processors 402, the instruction(s) cause the processing system 400
to perform operations to execute elements involving the various
aspects of the disclosure.
[0088] Moreover, while embodiments have been described in the
context of fully functioning computing devices, those skilled in
the art will appreciate that the various embodiments are capable of
being distributed as a program product in a variety of forms. The
disclosure applies regardless of the particular type of machine or
computer-readable media used to actually effect the
distribution.
[0089] Further examples of machine-readable storage media,
machine-readable media, or computer-readable media include
recordable-type media such as volatile and non-volatile memory
devices 410, floppy and other removable disks, hard disk drives,
optical disks (e.g., Compact Disk Read-Only Memory (CD-ROMS),
Digital Versatile Disks (DVDs)), and transmission-type media such
as digital and analog communication links.
[0090] The network adapter 412 enables the processing system 400 to
mediate data in a network 414 with an entity that is external to
the processing system 400 through any communication protocol
supported by the processing system 400 and the external entity. The
network adapter 412 can include a network adaptor card, a wireless
network interface card, a router, an access point, a wireless
router, a switch, a multilayer switch, a protocol converter, a
gateway, a bridge, bridge router, a hub, a digital media receiver,
and/or a repeater.
[0091] The network adapter 412 may include a firewall that governs
and/or manages permission to access/proxy data in a computer
network and tracks varying levels of trust between different
machines and/or applications. The firewall can be any number of
modules having any combination of hardware and/or software
components able to enforce a predetermined set of access rights
between a particular set of machines and applications, machines and
machines, and/or applications and applications (e.g., to regulate
the flow of traffic and resource sharing between these entities).
The firewall may additionally manage and/or have access to an
access control list that details permissions including the access
and operation rights of an object by an individual, a machine,
and/or an application, and the circumstances under which the
permission rights stand.
[0092] The foregoing description of various embodiments of the
claimed subject matter has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the claimed subject matter to the precise forms
disclosed. Many modifications and variations will be apparent to
one skilled in the art. Embodiments were chosen and described in
order to best describe the principles of the invention and its
practical applications, thereby enabling those skilled in the
relevant art to understand the claimed subject matter, the various
embodiments, and the various modifications that are suited to the
particular uses contemplated.
[0093] Although the Detailed Description describes certain
embodiments and the best mode contemplated, the technology can be
practiced in many ways no matter how detailed the Detailed
Description appears. Embodiments may vary considerably in their
implementation details, while still being encompassed by the
specification. Particular terminology used when describing certain
features or aspects of various embodiments should not be taken to
imply that the terminology is being redefined herein to be
restricted to any specific characteristics, features, or aspects of
the technology with which that terminology is associated. In
general, the terms used in the following claims should not be
construed to limit the technology to the specific embodiments
disclosed in the specification, unless those terms are explicitly
defined herein. Accordingly, the actual scope of the technology
encompasses not only the disclosed embodiments, but also all
equivalent ways of practicing or implementing the embodiments.
[0094] The language used in the specification has been principally
selected for readability and instructional purposes. It may not
have been selected to delineate or circumscribe the subject matter.
It is therefore intended that the scope of the technology be
limited not by this Detailed Description, but rather by any claims
that issue on an application based hereon. Accordingly, the
disclosure of various embodiments is intended to be illustrative,
but not limiting, of the scope of the technology as set forth in
the following claims.
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