The present invention generally relates to atomic layer deposition (ALD). More
particularly, the invention relates to providing protective coating by means of ALD.
BACKGROUND OF THE INVENTION
Atomic Layer Epitaxy (ALE) method was invented by Dr. Tuomo Suntola in the
early 1970's. Another generic name for the method is Atomic Layer Deposition
(ALD) and it is nowadays used instead of ALE. ALD is a special chemical
deposition method based on the sequential introduction of at least two reactive
precursor species to at least one substrate.
Thin films grown by ALD are dense, pinhole free and have uniform thickness. For
example, in an experiment aluminum oxide has been grown by thermal ALD from
trimethylaluminum (CH3)3AI, also referred to as TMA, and water resulting in only
about 1% non-uniformity over a substrate wafer.
One interesting application of ALD technique is providing protective coatings on
surfaces.
SUMMARY
According to a first example aspect of the invention there is provided a method for
protecting a target pump interior, the method comprising:
providing a target pump inlet with an inlet manifold and a target pump outlet with
an exhaust manifold; and
exposing the target pump interior to sequential self-saturating surface reactions by
sequential inlet of reactive gases via the inlet manifold into the target pump interior
and outlet of reaction residue via the exhaust manifold while the target pump is
kept running.
The sequential self-saturating surface reactions (according to ALD) produce the
desired protective coating within the pump interior. Accordingly, the target pump
interior may be coated by using ALD so that all surfaces within the target pump
which see the reactive gases end up coated. The target pump may be running
during the whole coating process.
In certain example embodiments, the method comprises attaching the inlet
manifold to the target pump inlet and attaching the exhaust manifold to target
pump outlet.
In certain example embodiments, the reactive gases and inactive purge gas enter
the target pump interior via the inlet manifold. In certain example embodiments,
reaction residue and purge gas exit the target pump interior via the exhaust
manifold.
The target pump interior may be used as the reaction chamber for ALD reactions.
The desired process temperature for ALD reactions may be obtained simply by
keeping the target pump running. Additional heating may not be needed.
Accordingly, in certain example embodiments, the method comprises providing a
required processing temperature by keeping the target pump running without using
other heating means.
In certain example embodiments, the inlet manifold comprises ALD reactor in-feed
equipment. In certain example embodiments, the in-feed equipment comprises infeed
line(s) and at least the desired precursor and inactive gas flow controlling
elements, such as valve(s), mass flow controller(s) or similar, and their control
system.
The control system may be implemented for example by software in a laptop
computer or similar. Accordingly, in certain example embodiments, the inlet
manifold comprises one or more in-feed lines with their controlling elements
controlled by a computer-implemented control system. Suitable replaceable
precursor and inactive gas sources may be attached to the in-feed equipment.
In certain example embodiments, the exhaust manifold comprises a vacuum
pump. In certain example embodiments, the method comprises pumping reaction
residue and purge gas from the target pump interior by a vacuum pump attached
to the exhaust manifold. The vacuum pump may provide one or more of the
following effects: It may be configured to pump reaction residue from the target
pump interior via the target pump outlet. It may be used to pump the target pump
interior into vacuum.
In certain example embodiments, the target pump is a vacuum pump. In certain
example embodiments, the sequential self-saturating surface reactions are
performed within a temperature range extending from ambient temperature to
150°C, i.e., the ALD processing temperature is within this range. In certain
example embodiments, the ALD processing temperature is within the range of
120°C - 150°C. In certain example embodiments, the processing temperature is
achieved by running the target pump itself. In certain other example embodiments,
the target pump is instead or additionally heated before and/or during ALD
processing by a separate heater.
In certain example embodiments, as mentioned in the foregoing, the type of the
target pump is a vacuum pump. In other embodiments, the target pump is of
another type. In yet other embodiments, the term pump is construed broadly
covering also compressors, the interior of which is coated by the disclosed
method.
In certain example embodiments, the method comprises forming a flow channel
via target pumps placed in a row, and providing simultaneous protection of the
interiors of the target pumps by using the flow channel. In certain example
embodiments, the method comprises forming the flow channel by attaching the
exhaust manifold of a previous pump to a pump inlet of the following pump in the
row.
According to a second example aspect of the invention there is provided an
apparatus for protecting a target pump interior, comprising:
an inlet manifold designed to be attached to a target pump inlet; and
an exhaust manifold designed to be attached to a target pump outlet, the
apparatus, when being used, carrying out the method of the first example aspect
or the third example aspect.
Accordingly, the apparatus, when being used, in certain example embodiments is
configured to expose the target pump interior to sequential self-saturating surface
reactions by sequential inlet of reactive gases via the inlet manifold into the target
pump interior and outlet of reaction residue via the exhaust manifold (while the
target pump is kept running or kept off).
In certain example embodiments, the inlet manifold comprises precursor vapor
and purge gas in-feed lines and their controlling elements.
In certain example embodiments, the exhaust manifold comprises a vacuum
pump.
In certain example embodiments, the apparatus is mobile. The protecting
apparatus comprising the inlet manifold and the exhaust manifold may be mobile
so that it can be moved to meet the user's needs. In certain example
embodiments, the inlet manifold and exhaust manifold are separate devices
designed to work together in a target pump interior protecting method. In certain
example embodiments, the inlet manifold comprises a target pump-specific
attachment part to attach to target pump inlet. Accordingly, in certain example
embodiments, the inlet manifold comprises a target pump-specific attachment part
configured to attach the inlet manifold into the target pump inlet. In certain
example embodiments, the exhaust manifold comprises a target pump-specific
attachment part to attach to target pump outlet.
According to a third example aspect of the invention there is provided a method for
protecting a target pump interior, the method comprising:
providing a target pump inlet with an inlet manifold and a target pump outlet with
an exhaust manifold; and
exposing the target pump interior to sequential self-saturating surface reactions by
sequential inlet of reactive gases via the inlet manifold into the target pump interior
and outlet of reaction residue via the exhaust manifold while the target pump is not
running.
The target pump not running means the target pump being "off'. In certain
example embodiments, the sequential self-saturating surface reactions are
performed at ambient temperature. In certain other example embodiments, the
sequential self-saturating surface reactions are performed at an elevated
temperature (i.e., temperature higher than the ambient temperature). In certain
example embodiments, the sequential self-saturating surface reactions are
performed within a temperature range extending from ambient temperature to
150°C. In certain example embodiments, the target pump is heated before and/or
during ALD processing by a separate heater. The embodiments described in
connection with the first aspect and their combinations apply also to the third
aspect, and vice versa.
Different non-binding example aspects and embodiments of the present invention
have been illustrated in the foregoing. The above embodiments are used merely to
explain selected aspects or steps that may be utilized in implementations of the
present invention. Some embodiments may be presented only with reference to
certain example aspects of the invention. It should be appreciated that
corresponding embodiments may apply to other example aspects as well. Any
appropriate combinations of the embodiments may be formed.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example only, with reference to the
accompanying drawings, in which:
Fig. 1 shows a schematic view of an apparatus and its use in
accordance with an example embodiment, and
Fig. 2 shows a method in accordance with an example embodiment.
DETAILED DESCRIPTION
In the following description, Atomic Layer Deposition (ALD) technology is used as
an example. The basics of an ALD growth mechanism are known to a skilled
person. As mentioned in the introductory portion of this patent application, ALD is
a special chemical deposition method based on the sequential introduction of at
least two reactive precursor species to at least one substrate. The at least one
substrate is exposed to temporally separated precursor pulses in the reaction
chamber to deposit material on the substrate surfaces by sequential self-saturating
surface reactions. In the context of this application, the term ALD comprises all
applicable ALD based techniques and any equivalent or closely related
technologies, such as, for example MLD (Molecular Layer Deposition) technique.
A basic ALD deposition cycle consists of four sequential steps: pulse A, purge A,
pulse B and purge B. Pulse A consists of a first precursor vapor and pulse B of
another precursor vapor. Inactive gas and a vacuum pump are typically used for
purging gaseous reaction by-products and the residual reactant molecules from
the reaction space during purge A and purge B. A deposition sequence comprises
at least one deposition cycle. Deposition cycles are repeated until the deposition
sequence has produced a thin film or coating of desired thickness. Deposition
cycles can also be more complex. For example, the cycles can include three or
more reactant vapor pulses separated by purging steps. All these deposition
cycles form a timed deposition sequence that is controlled by a logic unit or a
microprocessor.
In certain example embodiments as described in the following, there is provided a
method and apparatus for protecting a pump's (hereinafter referred to as target
pump) interior with a protective coating. The target pump itself forms a reaction
chamber, and there is no separate substrate, but the surfaces of the target pump
interior form a substrate (substrate here meaning the material on which a process
is conducted). All these surfaces can be coated by an ALD process in which
precursor vapors are sequentially inlet via an inlet manifold into the target pump
interior. The reaction residue is outlet from the target pump interior via an exhaust
manifold. The target pump is kept running during the deposition process. The
desired process temperature for ALD reactions within the target pump may be
obtained simply by keeping the target pump running. In other embodiments, the
target pump is "off. In all embodiments, the target pump can be optionally heated
before and/or during ALD processing by a heater.
Fig. 1 shows the method and related apparatus in certain example embodiments.
The apparatus used to protect the interior of a target pump 10 comprises an inlet
manifold 20 and an exhaust manifold 30. The apparatus may be a mobile
apparatus. A mobile apparatus may be conveniently moved into the proximity of
pumps to be protected, if needed.
The inlet manifold 20 is configured to be attached to the target pump inlet 11. Fig.
1 shows the inlet manifold 20 attached by a first attachment part 24 to the target
pump inlet 11. The first attachment part 24 may be a target pump-specific part.
The exhaust manifold 30 is configured to be attached to the target pump outlet 14.
Fig. 1 shows the exhaust manifold 30 attached by a second attachment part 3 1 to
the target pump outlet 14. The second attachment part 3 1 may be a target pumpspecific
part.
The inlet manifold 20 comprises ALD reactor in-feed equipment 70. The in-feed
equipment 70 comprises the required in-feed lines and their controlling elements.
Attached to the first attachment part 24 in Fig. 1 is a first precursor vapor in-feed
line 4 1, a second precursor in-feed line 42 and a purge gas in-feed line 43. The
first precursor in-feed line 4 1 originates from a first precursor source 2 1, the
second precursor in-feed line 42 from a second precursor source 22, and the
purge gas in-feed line 43 from a purge/inactive gas source 23.
The in-feed line controlling elements comprise flow and timing controlling
elements. A first precursor in-feed valve 6 1 and mass flow controller 5 1 in the first
precursor in-feed line 4 1 control the timing and flow of first precursor pulses.
Correspondingly, a second precursor in-feed valve 62 and mass flow controller 52
in the second precursor in-feed line 42 control the timing and flow of second
precursor pulses. Finally, a purge gas in-feed valve 63 and mass flow controller 53
control the timing and flow of purge gas.
In the embodiment shown in Fig. 1, the operation of the in-feed equipment 70 is
controlled by a control system. Fig. 1 shows a control connection 72 between the
in-feed equipment 70 and a control system 7 1. The control system 7 1 may be
implemented for example by software in a laptop computer or similar.
In certain example embodiments, the ALD process within the target pump interior
is performed in a vacuum. The exhaust manifold 30 optionally comprises a
vacuum pump 33. In certain example embodiments, the vacuum pump 33 is
located in the end of an exhaust line 32 which is attached into the target pump
outlet 14. The vacuum pump 33 can be optionally controlled by the control system
7 1 via an optional electrical connection 73 (which is between the control system 7 1
and the vacuum pump 33). Depending on the type of the target pump, the vacuum
pump 33 pumps the whole interior of the target pump 10 or at least a part of it into
vacuum. The target pump 10 can comprise different pressure regions. In Fig. 1,
the volumes 12 and 13 depict such regions. The arrow 15 depicts the flow
direction within the target pump 10, that is, from target pump inlet 11 via the target
pump interior (via volume 12 and then 13, if applicable) to the target pump outlet
14. If the target pump 10, too, is a vacuum pump, the volume 12 in Fig. 1 may be
considered as a vacuum pressure region and the volume 13 as an ambient
pressure region of the target pump 10 . When the target (vacuum) pump 10 is
running, the volume 12 stays in vacuum. The exhaust line vacuum pump 33 is
then used to pump also the volume 13 into a vacuum.
Further referring to Fig. 1, it should be noted that in other embodiments, the inlet
manifold and exhaust manifold 1 may be arranged differently. Instead of separate
in-feed lines at least part of the in-feed lines may be in common. The valve types
may vary. The flow controlling element locations may vary, etc. For example,
three-way valves may be used instead of two-way valves, immediately reflecting
changes in in-feed line routing. Concerning the precursor sources and purge gas,
their selection depends on the implementation and desired coating. The target
pump can be heated by an optional heater 16. The operation of the heater can be
optionally controlled be the control system 7 1 over a connection.
Applicable pump materials are, for example, metals, such as steel and aluminum,
but the materials are not limited to these materials. Applicable coatings are, for
example, metal oxides, such as aluminum oxide, titanium oxide, tantalum oxide,
and tungsten carbide, and their combinations, but the coatings are not limited to
these materials. Applicable ALD processing temperatures are ambient
temperature - 150 °C in certain example embodiments, although other ranges are
also applicable. In certain example embodiments, the type of the target pump is a
vacuum pump. In other embodiments, the target pump is of another type. In yet
other embodiments, the term pump is construed broadly covering also
compressors, the interior of which is coated by the disclosed method.
Fig. 2 shows method steps in accordance with what has been disclosed in Fig. 1.
First, a mobile pump protecting apparatus is carried next to the target pump 10 to
be protected, or the target pump 10 is moved next to the either mobile or fixed
pump protecting apparatus. The inlet manifold 20 is attached to target pump inlet
11 (step 8 1) and the exhaust manifold 30 to target pump outlet 14 (step 82). The
target pump 10 is optionally turned on (step 83). The target pump interior is
exposed to sequential introduction of precursor vapors, separated by purge steps,
in accordance with ALD. The reaction residue and purge gas is pumped into the
vacuum pump 33 (step 84). In the deposition process, a conformal protective
coating is obtained. The pump is turned off (step 85), and the inlet manifold 20 is
detached from target pump inlet 11 (step 86) and the exhaust manifold 30 from
target pump outlet 14 (step 87).
In further example embodiments, there is provided pump chain for protecting the
pump interiors of the pumps forming the chain. In these embodiments, the inlet
manifold is attached to a first target pump inlet similarly as shown in the previous
embodiments. A first end of a first exhaust manifold is attached to the first target
pump outlet and the opposite end of the exhaust manifold to a second target pump
inlet. A first end of a second exhaust manifold is attached to the second target
pump outlet and the opposite end to a third target pump inlet, and so on. By this
arrangement, a plurality of pumps arranged in a chain can be protected
simultaneously by one ALD processing. The gases enter the first target pump
interior via the inlet manifold, and the further target pump interiors via the exhaust
manifold of the previous pump, until they end up into a vacuum pump placed in the
end of the chain. Accordingly, a flow channel is formed via target pumps placed in
a row, and simultaneous protection of the interiors of the target pumps is provided
by using the flow channel. The target pumps can be vacuum pumps, themselves,
or any other applicable pumps.
Without limiting the scope and interpretation of the patent claims, certain technical
effects of one or more of the example embodiments disclosed herein are listed in
the following: A technical effect is protecting pump interior by a conformal
protective coating. Another technical effect is protecting a ready-made
(assembled) pump including its sealing surfaces. If the protection would be
performed separately for each pump part before assembly, this would make the
parts vulnerable to scratches during assembly. Another technical effect is using
the target pump itself to provide heating of the target pump interior, by keeping the
target pump running during the deposition process.
It should be noted the some of the functions or method steps discussed in the
preceding may be performed in a different order and/or concurrently with each
other. Furthermore, one or more of the above-described functions or method steps
may be optional or may be combined.
The foregoing description has provided by way of non-limiting examples of
particular implementations and embodiments of the invention a full and informative
description of the best mode presently contemplated by the inventors for carrying
out the invention. It is however clear to a person skilled in the art that the invention
is not restricted to details of the embodiments presented above, but that it can be
implemented in other embodiments using equivalent means without deviating from
the characteristics of the invention.
Furthermore, some of the features of the above-disclosed embodiments of this
invention may be used to advantage without the corresponding use of other
features. As such, the foregoing description should be considered as merely
illustrative of the principles of the present invention, and not in limitation thereof.
Hence, the scope of the invention is only restricted by the appended patent claims.

Claims
1. A method for protecting a target pump interior, the method comprising:
providing a target pump inlet with an inlet manifold and a target pump outlet
with an exhaust manifold; and
exposing the target pump interior to sequential self-saturating surface
reactions by sequential inlet of reactive gases via the inlet manifold into the
target pump interior and outlet of reaction residue via the exhaust manifold
while the target pump is kept running.
2 . The method of claim 1, comprising attaching the inlet manifold to the target
pump inlet and attaching the exhaust manifold to target pump outlet.
3 . The method of claim 1 or 2, comprising pumping reaction residue and purge
gas from the target pump interior by a vacuum pump attached to the exhaust
manifold.
4 . The method of any preceding claim, comprising providing a required
processing temperature by keeping the target pump running without using
other heating means.
5 . The method of any preceding claim, wherein the inlet manifold comprises one
or more in-feed lines with their controlling elements controlled by a computerimplemented
control system.
6 . The method of any preceding claim, comprising forming a flow channel via
target pumps placed in a row, and providing simultaneous protection of the
interiors of the target pumps by using the flow channel.
7 . The method of claim 6, comprising forming the flow channel by attaching the
exhaust manifold of a previous pump to a pump inlet of the following pump in
the row.
8 . The method of any preceding claim, comprising exposing the target pump
interior to sequential self-saturating surface reactions within a temperature
range extending from ambient temperature to 150°C.
The method of any preceding claim, wherein the target pump is a vacuum
pump.
10 . The method for protecting a target pump interior, the method comprising:
providing a target pump inlet with an inlet manifold and a target pump outlet
with an exhaust manifold; and
exposing the target pump interior to sequential self-saturating surface
reactions by sequential inlet of reactive gases via the inlet manifold into the
target pump interior and outlet of reaction residue via the exhaust manifold
while the target pump is not running.
11. An apparatus for protecting a target pump interior, comprising:
an inlet manifold designed to be attached to a target pump inlet; and
an exhaust manifold designed to be attached to a target pump outlet, the
apparatus, when being used, carrying out the method as defined in any of the
claims 1- 10 .
12 . The apparatus of claim 11, wherein the apparatus, when being used, is
configured to expose the target pump interior to sequential self-saturating
surface reactions by sequential inlet of reactive gases via the inlet manifold
into the target pump interior and outlet of reaction residue via the exhaust
manifold while the target pump is kept running.
13 . The apparatus of claim 11 or 12, wherein the inlet manifold comprises
precursor vapor and purge gas in-feed lines and their controlling elements.
14. The apparatus of any preceding claim 11- 13, wherein the exhaust manifold
comprises a vacuum pump.
15 . The apparatus of any preceding claim 11-14, wherein the inlet manifold
comprises a target pump-specific attachment part configured to attach the inlet
manifold into the target pump inlet.
16 . The apparatus of any preceding claim 11- 15, wherein the apparatus is mobile.