FIELD OF THE INVENTION
The present invention generally relates to atomic layer deposition (ALD) type of
techniques.
BACKGROUND OF THE INVENTION
This section illustrates useful background information without admission of any
technique described herein representative of the state of the art.
Atomic Layer Deposition (ALD) is a special chemical deposition method based on
sequential introduction of at least two reactive precursor species to at least one
substrate in a reaction space. The 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.
An ALD deposition cycle consists of four sequential steps: pulse A, purge A, pulse
B, and purge B. Pulse A consists of metal precursor vapor and pulse B of nonmetal
precursor vapor. Inactive gas, such as nitrogen or argon, and a vacuum
pump are 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 of desired thickness.
Precursor species form through chemisorption a chemical bond to reactive sites of
substrate surface. No more than a molecular monolayer of a solid material forms
on the surface during one precursor pulse. The growth process is thus selfterminating
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 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 react with the adsorbed species of the first precursor
molecules, thereby forming the desired thin film material. 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 has grown to a desired thickness.
Thin films grown by ALD are dense, pinhole free and have uniform thickness. For
example, in an experiment aluminum oxide has been grown by ALD from
trimethylaluminum (CH3)3AI, also referred to as TMA, and water resulting in only
about 1% non-uniformity over a substrate wafer.
SUMMARY
According to a first example aspect of the invention there is provided a method,
comprising:
performing an atomic layer deposition sequence comprising at least one
deposition cycle, each cycle producing a monolayer of deposited material, the
deposition cycle comprising introducing at least a first precursor species and a
second precursor species to a substrate surface in a reaction chamber, wherein
both of said first and second precursor species are present in gas phase in said
reaction chamber simultaneously.
In certain example embodiments, the deposition cycle comprises an activation
period and a regeneration period, and in the method:
during the activation period, the second precursor species reacts with the first
precursor species adsorbed to the substrate surface in a preceding regeneration
period; and
during a subsequent regeneration period, the first precursor species reacts with
the second precursor species adsorbed to the surface in the activation period.
A deposition cycle may be considered to begin with the regeneration period or with
the activation period. The first deposition cycle may begin with a regeneration
period during which the first precursor reacts with the substrate surface. The
activation period then immediately follows the regeneration period. The
regeneration period produces half a monolayer of deposited material. And, the
activation period produces the remaining half of a monolayer of deposited
material.
The first and second precursor species may be selected so that they are inert with
respect to each other in gas phase in normal process conditions, i.e., in the
processing temperature without activation. They can be present in a same volume
within the reaction chamber (mixed with each other). In certain example
embodiments, the second precursor species is inert towards the adsorbed first
precursor species without activation whereas the first precursor species is
reactive, also without activation, with the second precursor species adsorbed to
the surface.
In certain example embodiments, alternately the second precursor species reacts
with the adsorbed species of the first precursor and the first precursor species
reacts with the adsorbed species of the second precursor by chemisorption.
The reactions may be sequential self-saturating surface reactions.
In certain example embodiment, one of the first or second precursor species is
excited by photon energy during the activation period. In certain example
embodiments, the periods of activation and regeneration alternate, wherein
activation (or excitation) occurs only during the activation period. The activation
may be implemented by photons emitted by a photon source, such as an UV lamp,
a LED lamp, a xenon lamp, an X-ray source, a laser source, or an infrared source.
In certain example embodiments, the method comprises exciting the first precursor
species adsorbed to the substrate surface, whereby the adsorbed first precursor
species reacts on the surface with the second precursor species which is in gas
phase.
In certain example embodiments, alternatively, the method comprises exciting
second precursor species in gas phase, whereby the excited second precursor
species reacts on the surface with the adsorbed first precursor species.
In certain example embodiments, the first precursor species reacts during the
regeneration period, without activation (i.e., without excitation), with the second
precursor species adsorbed to the surface.
The first precursor can be a metal precursor and the second precursor a nonmetal
precursor.
Then, for example, the non-metal precursor in gas phase can be excited by photon
energy in the proximity of the substrate surface, or the metal precursor adsorbed
to the surface can be excited during the activation period.
In certain other embodiments, both precursor species are non-metal precursor
species. Examples of coating materials are, for example, metals, oxides, and
nitrides.
In certain example embodiments, the deposition cycles are performed by skipping
purge periods, i.e., without performing purge periods.
In certain example embodiments, the number of precursor species is more than
two. In these embodiments, one of the precursors may be reactive with the surface
without excitation the other precursors being inert towards surface reactions
without excitation.
The method in accordance with the first example aspect and its embodiment can
be used for a plurality of different applications, for example, for coating any
applicable stationary or a moving substrate. The substrate may be, for example, a
plate-like object, such as silicon wafer, a glass plate, a metal foil. The substrate
may be a substrate web, a strand or a strip. The substrate may be a thin flexible
glass substrate. It may be a polymer. It may be a fibrous web of paper, board or
nanocellulose. It may be a solar cell, an OLED display, a printed circuit board
component or generally a component of electronics. The method can be used for
low temperature passivation of heat sensitive applications.
According to a second example aspect of the invention there is provided an
apparatus, comprising:
a reaction chamber;
at least one in-feed line; and
a control system configured to control the apparatus to perform an atomic layer
deposition sequence comprising at least one deposition cycle in the reaction
chamber, each cycle producing a monolayer of deposited material, the deposition
cycle comprising introducing at least a first precursor species and a second
precursor species via said at least one in-feed line to a substrate surface in the
reaction chamber, wherein
the control system is further configured to control that precursor vapor of both of
said first and second precursor species is present in gas phase in said reaction
chamber simultaneously.
In certain example embodiments, the deposition cycle comprises an activation
period and a regeneration period, and the apparatus is configured to cause:
during the activation period, the second precursor species to react with the first
precursor species adsorbed to the substrate surface in a preceding regeneration
period; and
during a subsequent regeneration period, the first precursor species to react with
the second precursor species adsorbed to the surface in the activation period.
In certain example embodiments, the apparatus comprises a photon source to
excite one of the first or second precursor species by photon energy during the
activation period.
In certain example embodiments, the apparatus is configured to cause:
exciting the first precursor species adsorbed to the substrate surface, whereby the
adsorbed first precursor species reacts on the surface with the second precursor
species which is in gas phase.
In certain example embodiments, the apparatus is configured to cause:
exciting the second precursor species in gas phase, whereby the excited second
precursor species reacts on the surface with the adsorbed first precursor species.
In certain example embodiments, the reactions are sequential self-saturating
surface reactions.
In certain example embodiments, the first precursor is a metal precursor and the
second precursor a non-metal precursor.
In certain example embodiments, the control system is configured control that the
deposition cycles are performed without performing purge periods.
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 an example timing diagram in accordance with an
example embodiment;
Fig. 2 shows an example timing diagram in accordance with another
example embodiment;
Fig. 3 shows a side view of an example apparatus in accordance with
an example embodiment;
Fig. 4 shows loading and unloading in the apparatus of Fig. 3;
Fig. 5 shows a top view of the apparatus of Figs. 3 and 4;
Fig. 6 shows a further example of sources and in-feed lines in a
deposition apparatus;
Fig. 7 shows different modulation methods in accordance with an
example embodiment;
Fig. 8 shows a further example embodiment;
Fig. 9 shows an example shader in accordance with an example
embodiment;
Fig. 0 shows an example shader nozzle in accordance with an example
embodiment;
Fig. 11 shows a side view of an example apparatus in accordance with
another example embodiment; and
Fig. 12 shows a rough block diagram of a deposition apparatus control
system in accordance with an example embodiment.
DETAILED DESCRIPTION
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. 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. The
following presents a deviation to the basic deposition cycle thinking.
Fig. 1 shows an example timing diagram of a method in accordance with an
example embodiment. An atomic layer deposition sequence comprising at least
one deposition cycle is performed where each cycle produces a monolayer of
deposited material. The deposition cycle comprises introducing a first precursor
species and a second precursor species to a substrate surface in a reaction
chamber, wherein both of said first and second precursor species are present in
gas phase in said reaction chamber simultaneously.
In this example, the first precursor species is a metal precursor and the second
precursor species is a non-metal precursor. The first and second precursor
species are inactive with respect to each other in gas phase.
The method comprises alternating an activation period (from time instant ti to t.2)
and a regeneration period (from time instant t.2 to t.3). As demonstrated in Fig. 1,
during the activation period the metal precursor flow to the reaction chamber is off.
The substrate surface has been saturated by the metal precursor species in a
previous regeneration period. The non-metal precursor flow to the reaction
chamber is on. However, the non-metal precursor has been selected so that it
does not react with the metal precursor on the substrate surface without additional
excitation (additional meaning herein energy additional to the thermal energy
prevailing in the reaction chamber).
The non-metal precursor species in the proximity of the substrate surface is
excited by exposing it to photon energy during the activation period. This gives the
non-metal precursor species the additional energy required to react with the metal
precursor species adsorbed to the substrate surface. As a result, the substrate
surface becomes saturated by the non-metal precursor species.
Alternatively, the metal precursor species on the substrate surface is excited by
exposing it to photon energy during the activation period. This gives the additional
energy required to the reaction between metal precursor species adsorbed to the
substrate surface and the gas phase non-metal precursor species. As a result, the
substrate surface becomes saturated by the non-metal precursor species.
The alternative which is desired to be used for excitation may be selected by
adjusting the wavelength of the photons (i.e., light/radiation).
During the immediately following regeneration phase, both the non-metal
precursor flow and metal precursor flow are on and the photon exposure is off.
Both the first precursor vapor (metal precursor) and the second precursor vapor
(non-metal precursor) are present in gas phase in the reaction chamber
simultaneously. The photon exposure can be switched off by a shader.
The metal precursor species reacts with the non-metal precursor species which
were adsorbed to the surface in the activation period. Although present, the nonmetal
precursor species do not react with the substrate surface since the photon
exposure is off. As a result, the substrate surface becomes saturated by the metal
precursor species.
These deposition cycles are repeated to achieve a desired thickness.
Conventional purge periods can be skipped therefore achieving a faster ALD
growth rate.
During the regeneration period, an inactive gas flow is used as a carrier gas flow
for the metal precursor. However, the inactive gas flow to the reaction chamber
can be on also during the activation period.
The reaction mechanism during both the activation period and regeneration period
is chemisorption. The reactions may be self-saturating surface reactions.
The inactive gas used as carrier gas is either the same gas or different gas than
the non-metal precursor source gas. In certain example embodiments, as shown
in Fig. 2, the same gas (herein denoted as second processing gas) is used as both
carrier gas and as non-metal precursor source gas. The flow of the second
processing gas into the reaction chamber is kept on during the whole deposition
cycle. In these embodiments, the second processing gas functions as carrier gas
during the regeneration period and as non-metal precursor source gas during the
activation period. Both the first precursor species (metal precursor) and the
second precursor species (non-metal precursor) are present in gas phase in the
reaction chamber simultaneously. In an example embodiment, trimethylaluminium
(TMA, (CH3)3AI) is used as the metal precursor and oxygen (O2) as the second
processing gas. Then during the activation period, oxygen is excited to oxygen
radicals O* , and surface reactions take place between O* radicals and adsorbed
TMA to form the desired coating material, aluminium oxide (AI2O3). In certain other
embodiments, both precursor species are non-metal precursor species. Examples
of coating materials are, for example, metals, oxides, and nitrides.
Fig. 3 shows a side view of an example apparatus in accordance with an example
embodiment. The apparatus can be an atomic layer deposition reactor. The
apparatus comprises a reaction chamber 2 10 which is surrounded by an outer
chamber 220. The reaction chamber 2 10 can optionally have walls which define
an expansion space widening downwards as depicted in Fig. 3 . The intermediate
space between the outer chamber 220 and the reaction chamber 2 10 is
pressurized by conveying inactive gas to the space so that there is a slight
overpressure compared to the interior of the reaction chamber 2 10 .
A substrate holder 202 supports a substrate 201 in the reaction chamber 2 10 . The
substrate 201 can be loaded into and unloaded from the reaction chamber 2 10 (as
depicted by arrow 231 ) via a substrate transfer chamber 230 attached to the outer
chamber 220. The reaction chamber 2 10 comprises a movable structure, such as
a door 2 15, and the loading and unloading is performed the door 215 in an open
position as depicted in Fig. 4 . Alternatively, the movable structure can be formed
by two (or more) nested sub-parts or ring-like members which fit within each other,
one of said sub-parts or ring-like members being vertically movable to enable
loading and unloading via an aperture thus formed.
Returning back to Fig. 3, the apparatus comprises at least one precursor vapor infeed
line 2 11 to convey precursor vapor to the reaction chamber 210. The
apparatus further comprises a vacuum pump 2 13 in an evacuation line 2 12 for
maintaining an outgoing flow from the reaction chamber 2 10 .
The apparatus comprises a photon source 240 above the substrate surface. The
photon source 240 can be an UV lamp, a LED lamp or, for example, an X-ray
source, a laser source, or an infrared source. It provides photon exposure by
emitting photons 241 . The photon source 240 in an example embodiment operates
in a flashing manner. Photons 241 are emitted during the activation period, and
photons 241 are not emitted during the regeneration period. As a result the photon
exposure is on during the activation period and off during the regeneration period.
In an alternative embodiment, the photon source 240 is on all the time (and emits
photons 241 ) . In such an embodiment, photon exposure can be controlled by a
shader (mask) applied between the photon source 240 and substrate surface. Fig.
4 shows such an example shader 250. The photon exposure is provided to the
areas on the substrate surface which see the photon source 240 behind the
shader 250. The activation period and the resulting deposition (material growth)
thus occurs only on these areas. The shader 250 can be stationary leading to
selective deposition only on certain areas on the surface (if the shader 250 is
stationary, photon exposure can be switched on and off, e.g., by flashing the
photon source 240). Or, it can be movable (as depicted by arrow 251 ) to shift the
exposed area on the substrate surface (or to shade the substrate area altogether
during the regeneration period in an embodiment).
Fig. 5 shows a top view of the apparatus of Figs. 3 and 4 compatible with the
method shown in Fig. 1. The non-metal precursor species flows into the reaction
chamber 2 10 via the infeed-line 2 11 and the metal precursor species together with
inactive carrier gas via the in-feed line 2 11' .
The apparatus comprises an inactive gas source 40, a metal precursor source 4 1
and a non-metal precursor source 42. The inactive gas source 40 is in fluid
communication with the input of an inactive gas line valve 50. A first output of
valve 50 leads into the intermediate space between the outer chamber 220 and
the reaction chamber 2 10 where inactive gas is released to the intermediate space
via a gas release point 44. A second output of valve 50 is in fluid communication
with the input of a carrier gas input valve 54. A first output of valve 54 is in fluid
communication with a carrier gas input of the metal precursor source 4 1. A second
output of valve 54 is in fluid communication with a second input of a metal
precursor line valve 5 1. The metal precursor source 4 1 is in fluid communication
with a first input of valve 5 1. The output of valve 5 1 continues as the in-feed line
2 11' . The non-metal precursor source is in fluid communication with the input of a
non-metal precursor line valve 52. The output of valve 52 continues as the in-feed
line 2 11.
During the activation phase, the first input of the metal precursor line valve 5 1 is
closed. Accordingly, the metal precursor species does not flow into the reaction
chamber 2 10 . The non-metal precursor line valve 52 is open allowing the nonmetal
precursor species to flow into the reaction chamber 2 10 via in-feed line 2 11.
A route from the inactive gas source 40 to the reaction chamber 2 10 via in-feed
line 2 11' is kept open or closed depending on the implementation. The non-metal
precursor species in the proximity of the substrate surface on the area which see
the photon source 240 (i.e., which are not in the shade of the shader 250) is
excited. Alternatively, the metal precursor species on the substrate surface is
excited. In both alternatives the excitation enables the reaction between the
adsorbed metal precursor species and the gas phase non-metal precursor
species. As a result, the substrate surface on said area becomes saturated by the
non-metal precursor species. If desired, it can be arranged by the shader 250, that
the whole substrate surface or only part of it becomes saturated.
During the regeneration phase, the first input and the output of the metal precursor
line valve 5 1 are open allowing the metal precursor species to flow into the
reaction chamber 2 10 via in-feed line 2 11' . The non-metal precursor line valve 52
is open allowing the non-metal precursor species to flow into the reaction chamber
2 10 via in-feed line 2 11. The photon exposure is switched off by the shader 250,
or by not sending photons in the embodiment that uses the flashing photon
source. The metal precursor species reacts with the non-metal precursor species
which were adsorbed to the surface in the activation period. As a result, the
substrate surface becomes saturated by the metal precursor species on the area
of the adsorbed non-metal precursor species.
As the non-metal precursor species is always present in the reaction chamber 2 10
the following activation period may commence immediately when the photon
exposure is, again, switched on. In an example embodiment, the photon source
240 is always on and the photon exposure on the substrate surface is adjusted
merely by moving the shader 250.
Fig. 6 shows a further example of sources and in-feed lines in a deposition
apparatus compatible with the method shown in Fig. 2 . The apparatus may be of
the type shown in Figs. 3 and 4 . The apparatus comprises a metal precursor
source 4 1 and a second processing gas source 40. The second processing gas
functions as inactive (shield) gas, carrier gas and second precursor gas (here:
non-metal precursor) depending on the deposition cycle phase.
The second processing gas source 40 is in fluid communication with the input of
an inactive gas line valve 50. A first output of valve 50 leads as a shield gas line
into an intermediate space between an outer chamber 220 and a reaction
chamber 2 10 of the apparatus. The second processing gas in the property of
inactive shield gas is released to the intermediate space via a gas release point
44. A second output of valve 50 is in fluid communication with the input of a carrier
gas input valve 54. A first output of valve 54 is in fluid communication with a carrier
gas input of the metal precursor source 4 1 . A second output of valve 54 is in fluid
communication with a second input of a metal precursor line valve 5 1. The metal
precursor source 4 1 is in fluid communication with a first input of valve 5 1. The
output of valve 5 1 continues as a reaction chamber in-feed line 2 11' towards the
reaction chamber 2 10 . The gas/vapor flowing in the in-feed line 2 11' is released to
the reaction chamber 2 10 via a gas release point 14.
During the activation phase, the first input of the metal precursor line valve 5 1 is
closed. Accordingly, the metal precursor species does not flow into the reaction
chamber 2 10 . A route from the second processing gas source 40 to the reaction
chamber 2 10 via in-feed line 2 11' is kept open allowing second processing gas in
the property of non-metal precursor to flow into the reaction chamber 2 10 . The
route can be formed via valves 50, 54 and 5 1. The non-metal precursor species in
the proximity of the substrate surface on the area which see the photon source
240 (i.e., which are not in the shade of the shader 250, if applied) is excited.
Alternatively, the metal precursor species on the substrate surface is excited. In
both alternatives the excitation enables the reaction between the adsorbed metal
precursor species and the gas phase non-metal precursor species. As a result, the
substrate surface on said area becomes saturated by the non-metal precursor
species. If desired, it can be arranged by the shader 250, that the whole substrate
surface or only part of it becomes saturated.
During the regeneration phase, the first input and the output of the metal precursor
line valve 5 1 are open allowing the metal precursor species together with the
second processing gas in the property of carrier gas to flow into the reaction
chamber 2 10 via in-feed line 2 11' . The photon exposure is switched off by the
shader 250, or by not sending photons in the embodiment that uses a flashing
photon source. The metal precursor species reacts with the non-metal precursor
species which were adsorbed to the surface in the activation period. As a result,
the substrate surface becomes saturated by the metal precursor species on the
area of the adsorbed non-metal precursor species.
The shield gas line is kept open or closed depending on implementation. In certain
example embodiments, the shield gas line is kept open during the whole
deposition cycle/sequence allowing second processing gas in the property of
inactive shield gas to enter the intermediate space via the gas release point 44.
The alternation of the photon exposure and shade on the substrate surface is
defined as modulation. The modulation can be effected in various ways. This is
illustrated in Fig. 7 which shows different modulation methods. In a first method, a
shader 750 is moved above the substrate surface as depicted by arrow 751 . In a
second method, the photon source 740 is moved as depicted by arrow 752. In a
third method, the substrate 701 is moved as depicted by arrow 753. In the event of
a substrate on a substrate holder 702, the substrate holder 702 can be moved. A
further method is any combination of the first, second and third modulation
method. In a yet further method, a flashing light/source is used alone or in
combination with the other methods.
Fig. 8 shows a further example embodiment. The apparatus comprises a photon
source 840 at a distance from a substrate 801 that is supported by a substrate
holder 802. The apparatus comprises a patterned shader/mask 850 and a lens
855 between the photon source 840 and the substrate 801 . The activation and
regeneration periods are performed as in the foregoing embodiments. The growth
occurs only at the areas on the substrate surface at which the pattern produced by
the mask 850 is focused by the lens 855. In this way, the apparatus functions as
an ALD printer. In a further example embodiment, the substrate 801 and/or the
mask 850 is moved to achieve modulation as described in the foregoing.
In a yet further embodiment, selective deposition is achieved with a focused or
well-defined light source, such as a laser source. In such an embodiment, the
shader/mask 250 (750, 850) can be omitted, if desired, and a laser source is
provided in the place of the photon source 240. Otherwise the growth method is
similar to the method described in the foregoing. Accordingly, the laser source is
configured to provide photon exposure on a (well-defined) selected area. The laser
source may emit for example a laser pulse (a laser beam). The photon exposure is
provided to the selected area on the substrate surface which see the laser, and
accordingly the growth on the activation period occurs only on said selected area.
The regeneration period will follow. The laser beam can be shifted if growth is
required in other areas. When the laser beam is shifted further growth will then
occur on the new area which see the beam. The embodiment can be implemented
with or without a shader.
Fig. 9 shows an example shader (or shader grid) in accordance with an example
embodiment. The shader 950 comprises a shader frame 951 with solid portions
through which the emitted photons cannot penetrate and windows 952 through
which the emitted photons can penetrate. The form of the windows 952 depends
on the implementation. The windows 952 may be formed by glass or other
material through which the photons can penetrate.
Fig. 10 further shows an example shader nozzle in accordance with an example
embodiment. The shader nozzle 1050 can be used both as a shader and as a
precursor in-feed nozzle in a reaction chamber. It can be placed above a substrate
in between the substrate and a photon source. The shader nozzle 1050 comprises
a shader frame 1051 with solid portions through which the emitted photons cannot
penetrate and windows 1052 through which the emitted photons can penetrate.
The form of the windows 1052 depends on the implementation. A precursor infeed
line 10 11' is attached to the shader nozzle 1050. The in-feed line 10 '
branches to individual lateral flow channels 1071 which extend throughout the
shader frame 1051 along the solid portions. The flow channels 1071 have a
plurality of apertures (not shown) on their lower surface to guide precursor vapor
and/or other processing gas downwards towards the substrate surface.
Fig. 11 shows a side view of an example apparatus in accordance with another
embodiment. The apparatus is a processing apparatus or atomic layer deposition
module suitable for continuous deposition as a part of a processing line.
The apparatus comprises a reaction chamber 1110 which is surrounded by an
outer chamber 1120. An intermediate space between the outer chamber 1120 and
the reaction chamber 1110 is pressurized by conveying inactive shield gas to the
space so that there is a slight overpressure compared to the interior of the reaction
chamber 1110 .
A first transfer chamber 1130 is attached to a side of the outer chamber 1120, and
a second transfer chamber 1130' is attached to an opposite side of the outer
chamber 1120. The reaction chamber 1110 positioned within the outer chamber
comprises an input port 116 1 on its first side and an output port 116 1' on an
opposite side. The input port 1161 and the output port 116 1' may be formed as a
slit in a respective reaction chamber wall.
A substrate web 1101 to be coated is driven continuously through the first transfer
chamber 1130 into the outer chamber 1120, therefrom through the input port 116 1
into the reaction chamber 1110 for deposition, and therefrom through the output
port 116 1' into an opposite part of the outer chamber 1120, and through the
second transfer chamber 1130' to a subsequent phase of the processing line. In
an alternative embodiment, the substrate web 110 1 is a web supporting a set of
substrates 1101 ' (to be coated) travelling on it. In yet an alternative embodiment,
the substrate is a strand or a strip.
The apparatus comprises a non-metal precursor in-feed line to convey non-metal
precursor vapor to the reaction chamber 1110 . A release point 1111 of non-metal
precursor vapor is arranged on a side of the reaction chamber. The apparatus
further comprises a metal precursor in-feed line to convey metal precursor vapor
to the reaction chamber 1110 . In Fig. 11, the metal precursor in-feed line is
attached to a shader nozzle 1150 of the type described in the foregoing with
reference to Fig. 10 . The shader nozzle 1150 comprises laterally spreading flow
channels 1171 which have a plurality of apertures on their lower surface to guide
metal precursor vapor downwards towards the substrate surface.
The apparatus comprises a photon source 1140 above the substrate surface to
provide photon exposure. The shader nozzle 1150 is applied between the photon
source 1140 and the substrate surface. The shader nozzle 1150 comprises one or
more windows through which the emitted photons 1141 can pass. The form and
size of the window(s) depend on the implementation. The photon exposure is
provided to the areas on the substrate surface which see the photon source 1140
behind the shader nozzle 1150. The shader nozzle 1150 can be movable.
The apparatus further comprises a vacuum pump (not shown) in an evacuation
line 1112 for maintaining an outgoing flow from the reaction chamber 1110 .
The apparatus comprises an inactive gas source, a metal precursor source and a
non-metal precursor source. The sources are not shown in Fig. 9. However, a
corresponding arrangement with regard to valves etc. as described in the
foregoing with reference to Fig. 5 can be implemented.
Alternatively, if the apparatus operates in accordance with the method described
with reference to Fig. 2, the apparatus comprises the metal precursor source and
a second processing gas source. A corresponding arrangement with regard to
valves etc. as described in the foregoing with reference to Fig. 6 can be
implemented. The gas release point 1111 as well as the related in-feed line can be
omitted in this alternative, if both precursors are fed via the shader nozzle 1150.
When the substrate 110 1 or 110 1' moves forward different areas of the substrate
see the photon source 1140. An atomic layer deposition cycle described in the
foregoing with reference to Figs. 1 and 5 (alternatively Figs. 2 and 6) is performed.
Accordingly, during an activation phase, the metal precursor species is prevented
from flowing into the reaction chamber 1110 . The metal precursor input of metal
precursor line valve (Figs. 5 and 6; first input of valve 5 1) is closed. The non-metal
precursor species is allowed to flow into the reaction chamber 1110 . The nonmetal
precursor line in open (Figs. 5; the non-metal precursor line valve 52 is
open) or a route from the second processing gas source (Fig. 6; route via valves
50, 54 and 5 1) in the alternative embodiment is open.
The non-metal precursor species in the proximity of the substrate surface on the
areas which see the photon source 1140 (i.e., which are not in the shade of the
shader nozzle 1150) is excited. Alternatively, the metal precursor species on the
substrate surface is excited. In both alternatives the excitation enables the reaction
between the adsorbed metal precursor species and the gas phase non-metal
precursor species. As a result, the substrate surface on said areas becomes
saturated by the non-metal precursor species.
During a regeneration phase, the metal precursor in-feed line is open allowing the
metal precursor species to flow into the reaction chamber via the shader nozzle
1150. Furthermore, the non-metal precursor is also fed into the reaction chamber
1110 via the non-metal precursor in-feed line (or in the alternative embodiment as
carrier gas via the shader nozzle 1150). The metal precursor species reacts with
the non-metal precursor species which were adsorbed to the surface in the
activation period. As a result, the substrate surface becomes saturated by the
metal precursor species on the area of the adsorbed non-metal precursor species.
These deposition cycles are repeated to achieve a desired thickness.
Conventional purge periods can be skipped.
The features of the embodiments described with reference to Figs. 1- 10 can be
applied to the continuous deposition embodiment of Fig. 11 in which the substrate
or substrate web was coated on its way through the reaction chamber. For
example, instead of using the shader nozzle, a shader without gas in-feed
functionality can be used. In those embodiments, the gas in-feed onto the
substrate can be from the side. Furthermore, the continuous deposition
embodiment can be performed, for example, without any shader using a flashing
photon source as described in the foregoing, or with a shader and a flashing
photon source. Furthermore, the features of the continuous deposition
embodiment can be used in the embodiments presented previously in the
description. For example, the shader nozzle can be used in the other presented
embodiments. Certain example embodiments are implemented without including
any transfer chamber(s) for loading and/or unloading. Furthermore, certain
example embodiments are implemented without including an outer chamber
around the reaction chamber. The track formed by the substrate or support web in
the continuous deposition embodiment need not be straight, but a track formed in
the form of a repeated pattern can be implemented. The direction of propagation
of the web can be turned, for example by rolls, a plurality of times to form said
repeated pattern. Furthermore, the reaction chamber form can deviate from the
example form presented in the Figures. In one continuous deposition embodiment,
the web moves continuously at constant speed. In certain other embodiments, the
web is periodically moved (e.g., in a stop and go fashion) through the reaction
chamber.
In accordance with certain example embodiments, the precursor vapor and
inactive gas in-feed lines of the apparatuses described in the preceding are
implemented by the required pipings and their controlling elements.
The in-feed line controlling elements comprise flow and timing controlling
elements. In an example embodiment, a metal precursor in-feed valve and mass
(or volume) flow controller in a metal precursor in-feed line control the timing and
flow of metal precursor vapor into the reaction chamber. Correspondingly, a nonmetal
precursor in-feed valve and mass (or volume) flow controller in the nonmetal
precursor in-feed line control the timing and flow of the non-metal precursor
vapor into the reaction chamber. Finally, an inactive gas line valve and mass (or
volume) flow controller control the timing and flow of inactive gas. In an example in
which inactive gas is used as carrier gas, there may different controlling elements
as shown with reference to Fig. 6.
In an example embodiment, the in-feed line controlling elements form part of a
computer controlled system. A computer program stored into a memory of the
system comprises instructions, which upon execution by at least one processor of
the system cause the coating apparatus, or deposition reactor, to operate as
instructed. The instructions may be in the form of computer-readable program
code. Fig. 12 shows a rough block diagram of a deposition apparatus control
system 1200 in accordance with an example embodiment. In a basic system setup
process parameters are programmed with the aid of software and instructions are
executed with a human machine interface (HMI) terminal 1206 and downloaded
via a communication bus 1204, such as Ethernet bus or similar, to a control box
1202 (control unit). In an embodiment, the control box 1202 comprises a general
purpose programmable logic control (PLC) unit. The control box 1202 comprises
at least one microprocessor for executing control box software comprising
program code stored in a memory, dynamic and static memories, I/O modules,
AID and D/A converters and power relays. The control box 1202 sends electrical
power to pneumatic controllers of appropriate valves, and controls mass flow
controllers of the apparatus. The control box controls the operation of the photon
source, and the vacuum pump. The control box further controls any motion
devices needed to move either the substrate(s) and/or any movable shaders. The
control box 1202 receives information from appropriate sensors, and generally
controls the overall operation of the apparatus. In certain example embodiments,
the control box 1202 controls the in-feed of precursor species into the reaction
chamber such that both metal precursor species and non-metal species are
present in gas phase in the reaction chamber simultaneously. The control box
1202 may measure and relay probe readings from the apparatus to the HMI
terminal 1206. A dotted line 12 16 indicates an interface line between reactor parts
of the apparatus and the control box 1202.
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 new type of a deposition cycle by which a
faster atomic layer deposition rate can be achieved (fast atomic layer deposition).
Another technical effect is lower required processing temperature due to photon
exposure. Another technical effect is simplified chemical usage by using a second
processing gas as both a precursor and carrier gas.
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.
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.
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. It is to be noted that a metal precursor species
has been used as an example for the first precursor species, and a non-metal
precursor species as an example for the second precursor species. However, this
must not be considered limiting. The first precursor can alternatively be a nonmetal
precursor. Both precursors can be, for example, non-metal precursors, etc..
The choice of precursors is only dependent on the particular implementation
and/or the desired coating material.
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:
performing an atomic layer deposition sequence comprising at least one
deposition cycle, each cycle producing a monolayer of deposited material, the
deposition cycle comprising introducing at least a first precursor species and a
second precursor species to a substrate surface in a reaction chamber,
wherein both of said first and second precursor species are present in gas
phase in said reaction chamber simultaneously.
2 . The method of claim 1, wherein the deposition cycle comprises an activation
period and a regeneration period, and in the method:
during the activation period, the second precursor species reacts with the
first precursor species adsorbed to the substrate surface in a preceding
regeneration period; and
during a subsequent regeneration period, the first precursor species reacts
with the second precursor species adsorbed to the surface in the activation
period.
3 . The method of claim 2, wherein one of the first or second precursor species is
excited by photon energy during the activation period.
4 . The method of claim 3, comprising:
exciting the first precursor species adsorbed to the substrate surface,
whereby the adsorbed first precursor species reacts on the surface with the
second precursor species which is in gas phase.
5 . The method of claim 3, comprising:
exciting the second precursor species in gas phase, whereby the excited
second precursor species reacts on the surface with the adsorbed first
precursor species.
6 . The method of any preceding claim 2-5, wherein the reactions are sequential
self-saturating surface reactions.
7 . The method of any preceding claim, wherein the first precursor is a metal
precursor and the second precursor a non-metal precursor.
8 . The method of any preceding claim, wherein the deposition cycles are
performed without performing purge periods.
9 . An apparatus, comprising:
a reaction chamber;
at least one in-feed line; and
a control system configured to control the apparatus to perform an atomic
layer deposition sequence comprising at least one deposition cycle in the
reaction chamber, each cycle producing a monolayer of deposited material,
the deposition cycle comprising introducing at least a first precursor species
and a second precursor species via said at least one in-feed line to a substrate
surface in the reaction chamber, wherein
the control system is further configured to control that precursor vapor of
both of said first and second precursor species is present in gas phase in said
reaction chamber simultaneously.
10 . The apparatus of claim 9, wherein the deposition cycle comprises an
activation period and a regeneration period, and the apparatus is configured to
cause:
during the activation period, the second precursor species to react with the
first precursor species adsorbed to the substrate surface in a preceding
regeneration period; and
during a subsequent regeneration period, the first precursor species to react
with the second precursor species adsorbed to the surface in the activation
period.
11. The apparatus of claim 10, wherein the apparatus comprises a photon source
to excite one of the first or second precursor species by photon energy during
the activation period.
12 . The apparatus of claim 11, wherein the apparatus is configured to cause:
exciting the first precursor species adsorbed to the substrate surface,
whereby the adsorbed first precursor species reacts on the surface with the
second precursor species which is in gas phase.
13 . The apparatus of claim 11, wherein the apparatus is configured to cause:
exciting the second precursor species in gas phase, whereby the excited
second precursor species reacts on the surface with the adsorbed first
precursor species.
14. The apparatus of any preceding claim 10-1 3, wherein the reactions are
sequential self-saturating surface reactions.
15 . The apparatus of any preceding claim 9-14, wherein the first precursor is a
metal precursor and the second precursor a non-metal precursor.
16 . The apparatus of any preceding claim 9-1 5, wherein the control system is
configured control that the deposition cycles are performed without performing
purge periods.