ATOMIC LAYER DEPOSITION METHOD AND APPARATUSES
FIELD OF THE INVENTION
The present invention generally relates to deposition reactors. More particularly,
but not exclusively, the invention relates to such deposition reactors in which
material is deposited on surfaces by sequential self-saturating surface reactions.
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 at 250 - 300 °C
resulting in only about 1% non-uniformity over a substrate wafer.
Typical ALD reactors are quite complex apparatuses. Accordingly, there is an
ongoing need to produce solutions that would simplify either the apparatuses
themselves or their use.
SUMMARY
According to a first example aspect of the invention there is provided a method
comprising:
operating an atomic layer deposition reactor configured to deposit material on at
least one substrate by sequential self-saturating surface reactions; and
using dry air in the reactor as purge gas.
In certain example embodiments, dry air flows (or is configured to flow) along a
purge gas in-feed line. In certain example embodiments, dry air as purge gas flows
from an inactive gas source via a purge gas in-feed line into a reaction chamber.
In certain example embodiments, the method comprises:
using dry air as carrier gas.
In certain example embodiments, dry air flows (or is configured to flow) along a
precursor vapor in-feed line. In certain example embodiments, this may occur
during ALD processing. In certain example embodiments, dry air as carrier gas
flows from an inactive gas source via a precursor source into a reaction chamber.
In certain example embodiments, dry air as carrier gas is used to increase the
pressure in the precursor source. In certain other embodiments, dry air as carrier
gas flows from an inactive gas source via a precursor vapor in-feed line into a
reaction chamber without passing the precursor source. The flow route may be
designed based on whether the vapor pressure of the precursor vapor in itself is
high enough, or whether the pressure should be increased by an inactive gas flow
to the precursor source.
A single dry air source or a plurality of dry air sources may be used. Dry air (or
dried air) in this context means air with no moisture residue. Dry air may be
compressed gas. It may be used to carry precursor from a precursor source into a
reaction chamber.
In certain example embodiments, the method comprises:
having dry air to flow into a reaction chamber of the reactor during the whole
deposition sequence. A deposition sequence is formed of one or more consecutive
deposition cycles, each cycle consisting of at least a first precursor exposure
period (pulse A) followed by a first purge step (purge A) followed by a second
precursor exposure period (pulse B) followed by a second purge step (purge B).
In certain example embodiments, reaction chamber heating is implemented at
least in part via conducting heated dry air into the reaction chamber. This may
occur during an initial purge and/or during deposition ALD processing (deposition).
Accordingly, in certain example embodiments, the method comprises:
using dry air in heating a reaction chamber of the reactor.
In certain example embodiments, the method comprises:
heating the dry air downstream a purge gas in-feed valve.
In certain example embodiments, the method comprises:
providing a feedback connection of heat from an outlet part of the reactor to a
purge gas in-feed line heater.
In certain example embodiments, the outlet part comprises a heat exchanger. The
outlet part may be an outlet part of the reaction chamber of the reactor. The outlet
part may be a gas outlet part.
In certain example embodiments, the method comprises:
operating said atomic layer deposition reactor in ambient pressure.
In such embodiments, a vacuum pump is not needed.
In certain example embodiments, the method comprises:
using an ejector attached to an outlet part of the reactor to reduce operating
pressure in the reactor.
An ejector can be used instead of a vacuum pump when it is required to operate
below the ambient pressure but a vacuum is not needed. The outlet part may be a
reactor chamber lid. The ejector may be a vacuum ejector attached to the lid or to
exhaust channel.
The inlet of gases into the reaction chamber may be on the bottom side of the
reaction chamber and the outlet of reaction residue may be on the top side of the
reaction chamber. Alternatively, the inlet of gases into the reaction chamber may
be on the top side of the reaction chamber and the outlet of reaction residue may
be on the bottom side of the reaction chamber
In certain example embodiments, the reaction chamber is lightweight. A pressure
vessel as a reaction chamber is not needed.
According to a second example aspect of the invention there is provided an
apparatus comprising:
an atomic layer deposition reaction chamber configured to deposit material on at
least one substrate by sequential self-saturating surface reactions; and
a dry air in-feed line from a dry air source to feed dry air as purge gas into a
reaction chamber of the reactor.
The apparatus may be an atomic layer deposition (ALD) reactor.
In certain example embodiments, the apparatus comprises:
a precursor in-feed line from a dry air source via a precursor source into the
reaction chamber to carry precursor vapor into the reaction chamber.
In certain example embodiments, the apparatus comprises a heater configured to
heat the dry air. In certain example embodiments, the apparatus comprises said
heater downstream a purge gas in-feed valve.
In certain example embodiments, the apparatus comprises a feedback connection
of heat from an outlet part of the reactor to a purge gas in-feed line heater. In
certain example embodiments, the outlet part comprises a heat exchanger. The
outlet part may be an outlet part of the reaction chamber of the reactor. The outlet
part may be a gas outlet part.
In certain example embodiments, the reactor is a lightweight reactor configured to
operate in ambient pressure or close to the ambient pressure. The lightweight
reactor may be without a vacuum pump. Close to the ambient pressure means
that the pressure may be a reduced pressure, but not a vacuum pressure. In these
embodiments, the reactor may have thin walls. In certain example embodiments,
atomic layer deposition is carried out without a vacuum pump. Also, in certain
example embodiments, atomic layer deposition is carried out without a pressure
vessel. Accordingly, the lightweight (light-structured) reactor in certain example
embodiments is implemented with a lightweight (light-structured) reaction chamber
without a pressure vessel.
In certain example embodiments, the apparatus comprises:
an ejector attached to an outlet part of the reactor to reduce operating pressure in
the reactor.
An ejector can be used instead of a vacuum pump when it is required to operate
below the ambient pressure but a vacuum is not needed. The outlet part may be a
reactor chamber lid. The ejector may be a vacuum ejector attached to the lid or to
exhaust channel.
According to a third example aspect of the invention there is provided a production
line comprising the apparatus of the second aspect as a part of the production line.
According to a fourth example aspect of the invention there is provided an
apparatus comprising:
means for operating an atomic layer deposition reactor configured to deposit
material on at least one substrate by sequential self-saturating surface reactions;
and
means for using dry air in the reactor as purge gas.
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:
shows a deposition reactor and loading method in accordance
with an example embodiment;
shows the deposition reactor of Fig. 1 in operation during a purge
step;
shows the deposition reactor of Fig. 1 in operation during a first
precursor exposure period;
shows the deposition reactor of Fig. 1 in operation during a
second precursor exposure period;
shows a loading arrangement in accordance with an example
embodiment;
shows a deposition reaction in accordance with another example
embodiment;
a deposition reaction in accordance with yet another example
embodiment;
shows yet another example embodiment;
more closely shows certain details of a deposition reactor in
accordance with certain example embodiments; and
shows the deposition reactor as a part of a production line in
accordance with certain example embodiments.
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 substrate, or a
batch of substrates in many cases, is located within a reaction space. The reaction
space is typically heated. The basic growth mechanism of ALD relies on the bond
strength differences between chemical adsorption (chemisorption) and physical
adsorption (physisorption). ALD utilizes chemisorption and eliminates
physisorption during the deposition process. During chemisorption a strong
chemical bond is formed between atom(s) of a solid phase surface and a molecule
that is arriving from the gas phase. Bonding by physisorption is much weaker
because only van der Waals forces are involved. Physisorption bonds are easily
broken by thermal energy when the local temperature is above the condensation
temperature of the molecules.
The reaction space of an ALD reactor comprises all the typically heated surfaces
that can be exposed alternately and sequentially to each of the ALD precursor
used for the deposition of thin films or coatings. A basic ALD deposition cycle
consists of four sequential steps: pulse A, purge A, pulse B and purge B. Pulse A
typically consists of metal precursor vapor and pulse B of non-metal precursor
vapor, especially nitrogen or oxygen precursor vapor. Inactive gas, such as
nitrogen or argon, 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.
In a typical ALD process, precursor species form through chemisorption a
chemical bond to reactive sites of the heated surfaces. Conditions are typically
arranged in such a way that no more than a molecular monolayer of a solid
material forms on the surfaces during one precursor pulse. The growth process is
thus self-terminating or saturative. For example, the first precursor can include
ligands that remain attached to the adsorbed species and saturate the surface,
which prevents further chemisorption. Reaction space temperature is maintained
above condensation temperatures and below thermal decomposition temperatures
of the utilized precursors such that the precursor molecule species chemisorb on
the substrate(s) essentially intact. Essentially intact means that volatile ligands
may come off the precursor molecule when the precursor molecules species
chemisorb on the surface. The surface becomes essentially saturated with the first
type of reactive sites, i.e. adsorbed species of the first precursor molecules. This
chemisorption step is typically followed by a first purge step (purge A) wherein the
excess first precursor and possible reaction by-products are removed from the
reaction space. Second precursor vapor is then introduced into the reaction space.
Second precursor molecules typically react with the adsorbed species of the first
precursor molecules, thereby forming the desired thin film material or coating. This
growth terminates once the entire amount of the adsorbed first precursor has been
consumed and the surface has essentially been saturated with the second type of
reactive sites. The excess of second precursor vapor and possible reaction by
product vapors are then removed by a second purge step (purge B). The cycle is
then repeated until the film or coating has grown to a 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.
Fig. 1 shows a deposition reactor and loading method in accordance with an
example embodiment. The deposition reactor comprises a reactor chamber 110
that forms a space for accommodating a substrate holder 130 carrying at least one
substrate 135. Said at least one substrate can actually be a batch of substrates. In
the embodiment shown in Fig. 1, the at least one substrate 135 is vertically placed
in the substrate holder 130. The substrate holder 130, in this embodiment,
comprises a first flow restrictor 13 1 on its bottom side and a second (optional) flow
restrictor 132 on its top side. The second flow restrictor 132 is typically coarser
than the first flow restrictor 13 1 . Alternatively, one or both of the flow restrictors
13 1, 132 may be separate from the substrate holder 130. The reaction chamber
110 is closed by a reaction chamber lid 120 on the top side of the reaction
chamber 110 . Attached to the lid 120 is an exhaust valve 125.
The deposition reactor comprises precursor vapor in-feed lines 10 1 and 102 in the
bottom section of the deposition reactor. A first precursor vapor in-feed line 101
travels from an inactive carrier gas source 141 via a first precursor source 142
(here: TMA) and through a first precursor in-feed valve 143 into the bottom section
of the reaction chamber 110 . The first precursor in-feed valve 143 is controlled by
an actuator 144. Similarly, a second precursor vapor in-feed line 102 travels from
an inactive carrier gas source 15 1 via a second precursor source 152 (here: H2O)
and through a second precursor in-feed valve 153 into the bottom section of the
reaction chamber 110 . The second precursor in-feed valve 153 is controlled by an
actuator 154. The inactive carrier gas sources 141 , 15 1 may be implemented by a
single source or separate sources. In the embodiment shown in Fig. 1, nitrogen is
used as the inactive carrier gas. However, in the event that precursor sources that
have high vapor pressure are used, carrier gas does not have to be used at all in
some instances. Alternatively, in those cases, the route of carrier gas may be such
that carrier gas flows via the precursor vapor in-feed line in question, but passes
the precursor source in question.
The deposition reactor further comprises a purge gas in-feed line 105 in the
bottom section of the deposition reactor. The purge gas in-feed line 105 travels
from a purge gas source 162 through a purge gas valve 163 into the bottom
section of the reaction chamber 110 . The purge gas valve 163 is controlled by an
actuator 164. In the embodiment shown in Fig. 1, compressed gas, such as dry air
(or dried air) is used as purge gas. Herein, the expressions dry air and dried air
mean air without any moisture residue.
The reaction chamber 110 is loaded with a least one substrate by lowering the
substrate holder 130 into the reaction chamber 110 from the top side of the
deposition reactor. After deposition, the reaction chamber 110 is unloaded in the
opposite direction, that is, by raising the substrate holder 110 out of the reaction
chamber 110 . For the loading and unloading purpose, the lid 120 to the reaction
chamber has been moved aside.
As mentioned in the preceding, a deposition sequence is formed of one or more
consecutive deposition cycles, each cycle consisting of at least a first precursor
exposure period (pulse A) followed by a first purge step (purge A) followed by a
second precursor exposure period (pulse B) followed by a second purge step
(purge B). After loading, but before the commencement of the deposition
sequence, the reaction chamber 110 is also initially purged.
Fig. 2 shows the deposition reactor of Fig. 1 in operation during such a purge
phase, that is, during the initial purge or during purge A or purge B.
In this example embodiment, as mentioned in the preceding, compressed gas
such as dry air, is used as a purge gas. The purge gas valve 163 is kept open so
that the purge gas flows from the purge gas source 162 via the purge gas in-feed
line 105 into the reaction chamber 110 . The purge gas enters the reaction
chamber 110 at an expansion volume 17 1 upstream the first flow restrictor 13 1 .
Due to the flow restrictor 13 1, the purge gas spreads laterally in the expansion
volume 17 1. The pressure in the expansion volume 17 1 is higher than the
pressure in the substrate area, that is, volume 172. The purge gas flows through
the flow restrictor 13 1 into the substrate area. The pressure in a lid volume 173
downstream the second flow restrictor 132 is lower than the pressure in the
substrate area 172 so the purge gas flows from the substrate area 172 through the
second flow restrictor 132 into the lid volume 173. From the lid volume 173, the
purge gas flows via the exhaust valve 125 to an exhaust channel. During purge A
and B the purpose of purging is to push away gaseous reaction by-products and
residual reactant molecules. During initial purge the purpose is typically to push
away residual humidity/moisture and any impurities.
In an example embodiment, the purge gas is used to heat the reaction chamber
110 . The heating by the purge gas can be in operation during the initial purge, or
during both the initial purge and the deposition sequence depending on the
circumstances. Provided that the compressed gas, such as dry air, used to heat
the reaction chamber 110 is inactive with regard the used precursors and used
carrier gas (if any), the heating by the purge gas can be in use during the
precursor exposure periods (pulse A and pulse B).
In a heating embodiment, the purge gas is heated in the purge gas in-feed line
105. The heated purge gas enters the reaction chamber 110 and heats the
reaction chamber 110, and especially the said at least one substrate 135. The
used heat transfer method therefore is generally convection, and forced
convection in more detail.
Dry air (or dried air) meaning air without any moisture residue can be easily
provided, for example, by a conventional clean dry air producing apparatus (clean
dry air source) known as such. Such an apparatus can be used as the purge gas
source 162.
Fig. 3 shows the deposition reactor of Fig. 1 in operation during pulse A where the
precursor used (first precursor) is trimethylaluminium TMA. In this embodiment,
nitrogen N2 is used as inactive carrier gas. The inactive carried gas flows via the
first precursor source 142 carrying precursor vapor into the reaction chamber 110.
Before entering the substrate area 172, the precursor vapor spreads laterally in
the expansion volume 17 1. The first precursor in-feed valve 143 is kept open and
the second precursor in-feed valve 153 closed.
Simultaneously, the heated inactive purge gas flows into the reaction chamber 110
via the purge gas line 105 through the opened purge gas valve 163 heating the
reaction chamber 110 .
Fig. 4 shows the deposition reactor of Fig. 1 in operation during pulse B where the
precursor used (second precursor) is water H2O. In this embodiment, nitrogen N2
is used as inactive carrier gas. The inactive carried gas flows via the second
precursor source 152 carrying precursor vapor into the reaction chamber 110.
Before entering the substrate area 172, the precursor vapor spreads laterally in
the expansion volume 17 1. The second precursor in-feed valve 153 is kept open
and the first precursor in-feed valve 143 closed.
Simultaneously, the heated inactive purge gas flows into the reaction chamber 110
via the purge gas line 105 through the opened purge gas valve 163 heating the
reaction chamber 110 .
Fig. 5 shows a loading arrangement in accordance with an example embodiment.
In this embodiment, the reaction chamber 110 has doors in its sides, and the
substrate holder 130 is loaded from a side and unloaded from another side, for
example the opposite side. The reaction chamber lid 120 need not be removable.
In certain example embodiments, the deposition sequence in the deposition
reactor may be carried out in ambient pressure (typically room pressure), or in a
pressure close to one standard atmosphere ( 1 atm). In these embodiments, a
vacuum pump or similar is not needed in the exhaust channel. Also, any vacuum
chamber is not needed to accommodate the reaction chamber 110 . A pressure
vessel can be omitted. A lightweight reactor chamber 110 can be used. The walls
of the reaction chamber 110 can be thin, made for example of sheet metal. The
walls may be passivated before use by coating them with a passive layer. The
ALD method may be used. In fact, the interior surface of the reaction chamber 110
can be passivated beforehand (before deposition sequences on substrates are
carried out) using the deposition reactor itself with suitable precursors.
In case it is required to operate below the ambient pressure, the deposition reactor
can be provided with a vacuum ejector known as such. Fig. 6 shows such a
vacuum ejector 685 attached into the exhaust channel of the deposition reactor. In
the vacuum ejector 685, suitable inactive motive gas is inlet into the ejector
generating a low pressure zone sucking gas and small particles from the reaction
chamber 110 thereby reducing the pressure in the reaction chamber 110.
Fig. 7 shows a deposition reaction in accordance with yet another example
embodiment. In this embodiment, the same gas that is used as the purge gas in
the purge gas line 105 is also used as the inactive carrier gas. During operation,
the compressed gas, such as dry air, alternately flows from the source 141 via the
first precursor source 142 into the reaction chamber 110 and from the source 15 1
via the second precursor source 152 into the reaction chamber 110 carrying
precursor vapor with it. In addition, the inactive purge gas flows via the purge gas
in-feed line 105 into the reaction chamber 110 . Alternatively, the route of carrier
gas may be such that carrier gas flows via the precursor vapor in-feed line in
question, but passes the precursor source in question. In an example
embodiment, the inactive carrier gas flows from the inactive gas source in question
via the precursor vapor in-feed line in question into the reaction chamber 110
without actually flowing through the precursor source in question. The gas sources
141 , 15 1 and 162 may be implemented by a single source or separate sources.
Fig. 8 shows a deposition reaction in accordance with yet another example
embodiment. This embodiment is suitable especially for situations in which the
purge gas of in the in-feed line 105 cannot be allowed to enter the reaction
chamber 110 during the deposition sequence (for example if the purge gas is not
inactive with regard to the used precursors). In this embodiment, the purge gas infeed
line 105 is open during the initial purge. During the initial purge, heated purge
gas flows from the purge gas in-feed line 105 into the reaction chamber 110 for
heating the reaction chamber 110 . After the initial purge, the purge gas valve 163
is closed and it remains closed during the whole deposition sequence.
Fig. 9 more closely shows certain details of a deposition reactor in accordance
with certain example embodiments. In Fig. 9 there is shown a reaction chamber
heater (or heaters) 902, a heat exchanger 905, a purge gas in-feed line heater (or
heaters) 901 , and a feedback connection of heat 950.
The reaction chamber heater 902 located around the reaction chamber 110
provides the reaction chamber 110 with heat when desired. The heater 902 may
be an electrical heater or similar. The used heat transfer method is mainly
radiation.
The purge gas in-feed line heater 901 heats, in the in-feed line 105, the purge gas
which, in turn, heats the reaction chamber 110 . The used heat transfer method is
forced convection as described in the foregoing. The location of the gas in-feed
line heater 901 in the in-feed line 105 is downstream the purge gas valve 163 in
Fig. 9 . Alternatively, the location of the purge gas in-feed line heater 901 may be
upstream the purge gas valve 163 closer to the purge gas source 162.
The heat exchanger 905 attached to the top part or lid 120 of the reaction chamber
or to the exhaust channel can be used to implement the feedback connection 950.
In certain embodiments, heat energy collected from the exhaust gases is used in
heating the purge gas by the heater 901 and/or the heat energy can be exploited
in the heater 902.
In each of the presented embodiments, the reaction chamber lid 120 or the
exhaust channel of the deposition reactor can comprise a gas scrubber. Such a
gas scrubber comprises active material which absorbs such gases, compounds
and/or particles which are not expected to exit from the deposition reactor.
In certain embodiments, the precursor sources 142, 152 may be heated. In their
structure the sources 142, 152 may be flow-through sources. The flow restrictors
13 1, 132, especially the coarser, that is, second flow restrictor 132 may be
optional in certain embodiments. If during the deposition sequence the growth
mechanism is slow, in certain embodiments the exhaust valve 125 can be closed
during pulse A and B, while otherwise opened, in order to reduce precursor
consumption. In certain embodiments, the deposition reactor is implemented
upside down compared to the embodiments presented herein.
Fig. 10 shows the deposition reactor as a part of a production line, the ALD reactor
thus being an in-line ALD reactor (or reactor module). A deposition reactor similar
to the ALD reactor presented in the preceding can be used in a production line.
The example embodiment of Fig. 10 shows three adjacent modules or machines in
a production line. At least one substrate or a substrate holder or cassette or similar
carrying said at least one substrate is received from a module or machine 1010
preceding the ALD reactor module 1020 via an input port or door 1021 . The at
least one substrate is ALD processed in the ALD reactor module 1020 and sent to
a following module or machine 1030 via an output port or door 1022 for further
processing. The output port or door 1022 may reside at the opposite side of the
ALD reactor module than the input port or door 1021 .
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 a simpler and more economical deposition
reactor structure. Another technical effect is heating or pre-heating the reaction
chamber and substrate surfaces by forced convection. Yet another technical effect
is the use of dry air as both purge and carrier gas during an ALD deposition
sequence. Yet another technical feature is ALD processing in ambient pressure or
slightly below the ambient pressure, thereby enabling the ALD reactor / ALD
reactor module to be conveniently used in a production line.
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 comprising:
operating an atomic layer deposition reactor configured to deposit material
on at least one substrate by sequential self-saturating surface reactions; and
using dry air in the reactor as purge gas.
2 . The method of claim 1, comprising:
using dry air as carrier gas.
3 . The method of claim 1 or 2, comprising:
having dry air to flow into a reaction chamber of the reactor during the
whole deposition sequence.
4 . The method of any preceding claim, comprising:
using dry air in heating a reaction chamber of the reactor.
5 . The method of any preceding claim, comprising:
heating the dry air downstream a purge gas in-feed valve.
6 . The method of any preceding claim, comprising:
providing a feedback connection of heat from an outlet part of the reactor to
a purge gas in-feed line heater.
7 . The method of any preceding claim, comprising:
operating said atomic layer deposition reactor in ambient pressure to
deposit material on at least one substrate by sequential self-saturating surface
reactions.
8 . The method of any preceding claim 1-6, comprising:
using an ejector attached to an outlet part of the reactor to reduce operating
pressure in the reactor.
9 . An apparatus comprising:
an atomic layer deposition reaction chamber configured to deposit material
on at least one substrate by sequential self-saturating surface reactions; and
a dry air in-feed line from a dry air source to feed dry air as purge gas into a
reaction chamber of the reactor.
10 . The apparatus of claim 9, comprising:
a precursor in-feed line from a dry air source via a precursor source into the
reaction chamber to carry precursor vapor into the reaction chamber.
11. The apparatus of claim 9 or 10, comprising:
a heater configured to heat the dry air.
12 . The apparatus of claim 11, comprising:
said heater downstream a purge gas in-feed valve.
13 . The apparatus of any preceding claim 9-1 2, comprising:
a feedback connection of heat from an outlet part of the reactor to a purge
gas in-feed line heater.
14. The apparatus of any preceding claim 9-1 3, wherein the reactor is a
lightweight reactor configured to operate in ambient pressure or close to the
ambient pressure.
15 . The apparatus of any preceding claim 9-14, comprising:
an ejector attached to an outlet part of the reactor to reduce operating
pressure in the reactor.
16 . A production line comprising the apparatus of any preceding claim 9-1 5 as a
part of the production line.
17 . An apparatus comprising:
means for operating an atomic layer deposition reactor configured to
deposit material on at least one substrate by sequential self-saturating surface
reactions; and
means for using dry air in the reactor as purge gas.