WO2019096391A1

WO2019096391A1 - Method and apparatus for vapor depositing an insulation layer of metal oxide on a substrate

Info

Publication number: WO2019096391A1
Application number: PCT/EP2017/079469
Authority: WO
Inventors: Alexander Wolff
Original assignee: Applied Materials, Inc.
Priority date: 2017-11-16
Filing date: 2017-11-16
Publication date: 2019-05-23

Abstract

A method and apparatus for depositing an insulation layer of a metal oxide (e.g. AlOx) on a flexible substrate. The method comprises: vaporizing a metal, in particular aluminum, from a source material comprising the metal; introducing a gas flow comprising oxygen in a manner that an interaction of the oxygen with the source material is prevented; generating a metal oxide vapor by the interaction of the metal vapor with the oxygen; and directing the metal oxide vapor to the substrate.

Description

METHOD AND APPARATUS FOR VAPOR DEPOSITING AN INSULATION LAYER OF METAL OXIDE ON A SUBSTRATE

TECHNICAL FIELD

Embodiments of the present disclosure relate to a thin- film forming method and an apparatus for forming a thin film on a flexible substrate. Embodiments of the present disclosure particularly relate to a method of depositing an insulation layer of a metal oxide and a vapor deposition unit for vapor depositing an insulation layer of metal oxide, such as AlOx, on a flexible substrate, especially for use in battery applications.

BACKGROUND

Processing of flexible substrates, such as plastic films or foils, is in high demand in the production of battery systems as well as in other industries. Processing may consist of coating of a flexible substrate with a metal oxide, in particular aluminum oxide. Systems performing this task generally include a processing drum, e.g., a cylindrical roller, coupled to a processing system for transporting the substrate, and on which at least a portion of the substrate is processed.

Metal oxide layers can be evaporated with a reactive evaporation process, such as a thermal evaporation process. In this way, a source material comprising a metal such as aluminium is evaporated and a reactive gas such as oxygen is provided. This evaporation method can, for example, be used for depositing aluminum oxide, aluminum nitride, aluminum oxynitride, and similar materials on the substrate.

An apparatus and method for vapor deposition is normally designed in view of the process performance, efficiency and productivity, the lifetime of the evaporation apparatus, the process costs and the stability of the process, the quality of the coating, in particular the optical uniformity and the lack of splashes. However, there is still room for improvement in presently known methods and apparatuses for the vapor deposition of a metal oxide. In view of the above, it is an object to provide an improved method of vapor depositing and an improved vapor deposition unit to overcome at least some of the problems in the art. Another object is to provide vapor depositing an insulation layer of metal oxide on a substrate with an improved process performance and/or an improved efficiency of the evaporation process.

SUMMARY

According to an aspect of the present disclosure, a method of vapor depositing an insulation layer of a metal oxide, in particular an aluminum oxide, on a substrate is provided. The method includes vaporizing a metal, in particular aluminum, from a source material comprising the metal, introducing a gas flow comprising oxygen in a manner such that an interaction of the oxygen with the source material is prevented, generating a metal oxide vapor from the interaction of the metal vapor with the oxygen, and directing the metal oxide vapor to the substrate.

According to another aspect of the present disclosure, a vapor deposition unit for vapor depositing an insulation layer of metal oxide, in particular aluminum oxide, on a substrate is provided. The vapor deposition unit includes an evaporator for evaporating a source material, the material comprising a metal, in particular aluminum, so as to generate a metal vapor from the source material, and a reaction space comprising an inlet for introducing oxygen, the reaction space being configured to allow the metal vapor to react with the oxygen to generate a metal oxide vapor, wherein the inlet is positioned and/or shaped such that a reactive interaction of oxygen with the source material is prevented.

The method and the device of the present disclosure allow for depositing an insulation layer of metal oxide on a substrate with an improved process performance, an improved efficiency of the evaporation process, reduced process costs and an increased lifetime of the vapor deposition unit.

Further aspects, advantages and features of the present disclosure are apparent from the dependent claims, the description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to typical embodiments. The accompanying drawings relate to embodiments of the present disclosure and are described in the following:

Fig. la shows a schematic view of a vapor deposition unit for vapor depositing an insulation layer of metal oxide on a substrate according to embodiments described herein;

Fig. lb shows a sectional view along the line AA shown in Fig. la;

Fig. 2 shows a functional representation of a further vapor deposition unit according to embodiments described herein;

Fig. 3a shows a schematic view of a further vapor deposition unit according to embodiments described herein;

Fig. 3b shows a sectional view along the line BB shown in Fig. 3a; and

Fig. 4 shows a schematic view of an evaporation chamber of a further vapor deposition unit according to embodiments described herein.

DETAIFED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the various embodiments of the present disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to the same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation and is not meant as a limitation of the present disclosure. Features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations. It is noted here that a flexible substrate or web as used within the embodiments described herein can typically be characterized in that it is bendable. The term“web” may be synonymously used with the term“strip” or the term“flexible substrate”. For example, the web, as described in embodiments herein, may be a foil or another flexible substrate.

However, as described in more detail below, the benefits of embodiments described herein may also be provided for non-flexible substrates or carriers of other deposition systems. Yet, it is understood that particular benefit can be utilized for flexible substrates and applications for manufacturing devices on flexible substrates.

Fig. la shows a schematic view of an exemplary embodiment of a vapor deposition unit 10 for vapor depositing an insulation layer 16.5 of metal oxide on a substrate 17. Details explained with illustrative reference to Fig. 1 shall not be understood as limited to the elements of Fig. 1. Rather, those details may also be combined with further embodiments explained with illustrative reference to the other figures.

The term“vapor deposition unit” may synonymously be used as“evaporator unit” herein. The vapor deposition unit 10 as described herein may include:

an evaporator 16.1 for evaporating a source material 16.2. The material 16.2 includes a metal, in particular aluminum, so as to generate a metal vapor 16.4 from the source material 16.2, and

a reaction space 12.1 comprising an inlet 14 for introducing oxygen. The reaction space 12.1 is configured to allow the metal vapor 16.4 to react with the oxygen in an oxidation region spaced apart from the source material, to generate a metal oxide vapor in the oxidation region. In particular, the reaction space 12.1 is configured to allow the metal vapor 16.4 to react with the oxygen only in an oxidation region spaced apart from the source material.

The inlet 14 is positioned and/or shaped such that a reactive interaction of oxygen with the source material 16.2 is prevented.

The term“source material” can be understood as including the metal in solid or liquid form. Such a material may be the metal or a mixture of the metal with other materials, or a metal alloy comprising the metal. The term“reaction space” may be understood as a space surrounded by lateral walls constituting a processing space or chamber in which vacuum or near vacuum is present and in which processing of the metal vapor is performed, e.g. in which the metal vapor is generated, and/or moved to the substrate and/or oxidized.

The term“evaporator” may be understood as a device in a process used to turn the source material into a gaseous form, i.e. vapor. The source material can be turned first into a fluid form by a melting process and then turned into the gaseous form, or can be directly turned into the gaseous form.

The term“inlet” may be understood as a device allowing a directed and/or metered inflow or supply of gas flow into the reaction space or chamber.

The substrate 17 coated with the insulation layer 16.5 may constitute an electrical separator used in batteries and other arrangements in which electrodes have to be separated from each other while maintaining ion conductivity. In batteries, the separator electrically insulates the cathode from the anode. In addition, it is beneficial if the separator is permanently elastic and follows the movements in the system which stems not only from external loads but also from“breathing” of the electrodes as the ions are incorporated and discharged.

The functional relationships which are defined by a method of vapor depositing an insulation layer 16.5 of a metal oxide, in particular an aluminum oxide, on a substrate 17 may also be explained with exemplary reference to Fig. la. The method includes:

vaporizing a metal, in particular aluminum, from a source material 16.2 comprising the metal;

introducing a gas flow 14.4 comprising oxygen in such a manner that an interaction of the oxygen with the source material 16.2 is prevented;

generating a metal oxide vapor from the interaction of the metal vapor 16.4 with the oxygen; and

directing the metal oxide vapor to the substrate 17.

The vapor deposition process is in particular carried out under vacuum conditions. Vacuum as understood herein shall include pressure values of below lxlOE-2 mbar. As shown in Figs la, 2, 3a, 4, the flexible substrate 17 can be guided over a coating drum 18.1, which can optionally be a cooling drum. If applicable, the substrate 17 is cooled during processing in a depositing region within the reaction space 12.1.

According to embodiments described herein, the interaction of the oxygen with the source material (illustrated as 16.2 in Fig. la) can be prevented by exerting a force on the oxygen particles that is directed towards the substrate. In this way, the oxygen particles move towards the substrate instead of towards the source material. The force can be a combination selected from a group including: i) a force due to a difference in partial pressure of the metal vapor (illustrated as 16.4 in Fig. la) between the source material (illustrated as 16.2 in Fig. la) and the substrate 17, ii) an electric force, and iii) a magnetic force.

With regard to option i), the force is due to particles of metal vapor 16.4 moving toward the substrate 17 that may give a lift the gas particles, thus moving them along the same direction.

With regard to options ii), iii), the force is produced by ionizing the gas particles and surrounding them by an electric or electromagnetic field.

According to embodiments described herein, the interaction of the oxygen with the source material 16.2 can be prevented by generating the metal oxide vapor in an oxidation region spaced apart from the source material 16.2, in particular by generating the metal oxide vapor only in an oxidation region that is spaced apart from the source material 16.2. Herein, the oxidation region may extend to the substrate 17 and may be established in a safe distance to the source material 16.2.

According to embodiments described herein, the interaction of the oxygen with the source material 16.2 can be prevented by introducing the gas flow 14.4 into an inlet region closer to the substrate 17 than to the source material 16.2, in particular by a factor greater than 1.1 times, or 2 or 3 times, and/or less than 20 times closer to the substrate 17 than to the source material 16.2. With increasing proximity of the inlet region to the substrate 17, the magnitude ratio of the oxidation region to the evaporation region increases, as does the ratio of oxidation-active gas particles to those gas particles which enter the evaporation region or contaminate the source material 16.2. A further contribution to a low oxygen contamination of the evaporator source material is coming from the reduced evaporation area/zone. The higher evaporation pressure (metal vapor, e.g. Al vapor) prevents the oxygen flow (with the lower pressure) reaching the hot source surface and oxidizing and damaging the source.

The term“evaporation region” may be understood as a region of the reaction space or reaction chamber in which the metal vapor 16.4 is generated.

The term“inlet region” may be understood as a region of a reaction space or chamber in which the gas flow is introduced into the reaction space.

The term“oxidation region” may be understood as a region of the reaction space or chamber in which the metal vapor 16.4 is oxidized.

According to embodiments described herein, the interaction of the oxygen with the source material 16.2 can be prevented by introducing the gas flow 14.4 in a direction towards the substrate 17, in particular at a rate of 1 m/s to 100 m/s. In this way, a movement of the gas particles towards the substrate 17 can be established with respect to direction and strength in such a way that a counter-movement towards the source material 16.2 is substantially hindered. Especially, the gas flow 14.4 can be guided in a stream with a diameter greater than 1 mm and/or less than 10 cm.

According to embodiments described herein, the interaction of the oxygen with the source material 16.2 can be prevented by performing the movement of metal vapor particles toward the substrate 17 in a reaction space 12.1 that is formed tunnel-shaped and/or conically in an axial direction. In particular, the interaction can be prevented by providing a reaction space 12.1 having a lateral extent of a metal vapor entrance 12.5 that is smaller than a lateral extent of a metal vapor exit 12.6, especially by a factor of at least 1/10 times and/or at most 1/1.5 smaller than the lateral extent of the metal vapor exit 12.6. In this way, a reduced evaporation area/zone is enabled or provided, thus producing a higher evaporation pressure (metal vapor, e.g. Al vapor). Said pressure prevents the oxygen flow (with the lower pressure) coming to the hot source surface of the evaporator 16.1 and/or to the source material 16.2 and oxidizing and damaging the source material 16.2. The measures described may advantageously prevent the gas particles from approaching and contaminating the source material 16.2 or the metal vapor 16.4 in the evaporation region.

According to embodiments described herein, a force that is directed to the substrate 17 can be exerted on oxygen particles by ionizing the gas flow 14.4 so that the gas flow 14.4 includes ionized particles. In the presence of an electrical or electromagnetic field, an electrical field force is exerted on the ionized gas particles to move them to the substrate 17.

According to embodiments described herein, the particles of the gas flow 14.4 can be ionized by a laser beam and/or a high voltage. For this purpose, a laser or high voltage based ionizer can be placed at the entry of an inlet 14 designed for introducing the gas flow 14.4.

According to embodiments described herein, exerting a force directed to the substrate 17 on oxygen particles may imply exerting an electric force on the ionized metal vapor particles, thus moving the particles to the substrate 17. In other words, the particles of metal vapor 16.4 moving toward the substrate 17 may give the gas particles a lift, thus moving them along the same direction.

According to embodiments described herein, the metal oxide vapor can be directed to the substrate 17 by ionizing the metal vapor 16.4 so that the metal vapor 16.4 includes ionized particles. The movement of the metal oxide particles results from the fact that in the presence of an electrical or electromagnetic field, an electrical field force is exerted on the ionized metal vapor particles to move them to the substrate 17. The ionized metal vapor particles moving to the substrate 17 may also move along metal oxide particles in the same direction.

According to embodiments described herein, the metal oxide vapor can be directed to the substrate 17 by generating the ionized particles such that the metal vapor 16.4 and the gas flow 14.4 include oppositely charged ions.

According to embodiments described herein, directing the metal oxide vapor to the substrate can imply that the electric force acts on the ionized particles i) of the metal vapor 16.4 by moving and/or accelerating the particles to the substrate and ii) of the gas flow 14.4 by preventing the particles from approaching the source material 16.2. According to embodiments described herein, the metal oxide vapor can be directed to the substrate 17 by continuing a previously initiated movement of the metal vapor 16.4 after the oxidation.

According to embodiments described herein, the metal oxide vapor can be directed to the substrate 17 by carrying the particles of the metal oxide vapor by the gas flow 14.4 directed towards the substrate 17.

According to embodiments described herein, the metal vapor 16.4 can be generated by thermal evaporation or electron beam evaporation.

According to embodiments described herein, the metal vapor 16.4 can be generated by heating an evaporator 16.1 in which the metal has been introduced, in particular by electrically heating the evaporator 16.1.

According to embodiments described herein, the metal vapor 16.4 can be generated by feeding a metal wire 16.2 into the evaporator 16.1, in particular by rolling the metal wire 16.2 from a wire reel 16.3.

According to embodiments described herein, the evaporator 16.1 can be designed as a crucible configured for being operated under vacuum or almost vacuum conditions.

Alternatively, the evaporator 16.1 can include a plurality of crucibles spaced apart from each other, the source material 16.2 being fed to the crucible in form of a metal wire. The metal wire 16.2 can be unwound from a wire reel 16.3 and fed to the evaporator 16.1. Each crucible can be inductively heated. The inductively heated crucible may be configured for evaporating a metal in a vacuum or almost vacuum environment by RF induction-heating, in particular by MF induction-heating.

In further embodiments herein, the metal may be provided in crucibles that are exchangeable, such as, for example in one or more graphite vessels. Generally, the exchangeable crucible may include an insulating material that surrounds the crucible. One or more induction coils may be wrapped around the crucible and the insulating material and may in particular be water cooled. Advantageously, where exchangeable crucibles are used, no wire needs to be fed into the evaporation apparatus. The exchangeable crucibles may be pre- loaded with a metal and may be replaced or refilled periodically. Generally, providing the metal in batches has the advantage of accurately controlling the amount of metal being evaporated.

According to embodiments herein, the evaporator 16.1 can be designed as an electron beam evaporator 16.1 evaporating the metal from an anode-crucible. An electron beam generated by a thermoionic cathode can be directed to the evaporating metal in the crucible. This way, an ionized metal vapor 16.4 can be generated.

According to embodiments described herein, the evaporator 16.1 can be designed as a boat evaporator 16.1, which in particular is made of ceramic or titanium boride. The evaporator 16.1 can have an extent in a first lateral direction of at least 50 mm and/or at most 100 mm, in particular 75 mm, and an extent in a second lateral direction, perpendicular to the first lateral direction, of at least 50 cm and/or at most 150 cm, in particular about 100 cm. The second lateral direction typically corresponds to the substrate’s width. In embodiments in which the evaporator is a boat evaporator, only a single evaporator is used, thus enabling to achieve a large magnitude ratio of the lateral extent of the oxidation region to the lateral extent of the evaporation region (the lateral extent of the exit opening of the reaction space is substantially larger than the entrance opening of the reaction space). Such embodiments facilitate a layer deposition on the substrate 17 with an improved uniformity of the deposited layer 16.5.

According to embodiments described herein, the evaporator may include a plurality of boat evaporators 16.1, in particular a minimum of 2 and/or a maximum of 20 or 40 linear boat evaporators 16.1, arranged one behind the other along the first lateral direction.

According to alternative embodiments described herein, the evaporator 16.1 can be heatable by thermal, especially direct current, heating.

The vapor deposition unit 10 further includes a reaction space 12.1 with an inlet 14 for introducing oxygen. The reaction space 12.1 is configured to allow the metal vapor 16.4 to react with the oxygen to generate a metal oxide vapor. According to embodiments described herein, the reaction space 12.1 can be formed tunnel-shaped in the axial direction (i.e. in the direction between evaporator and substrate), wherein the reaction space 12.1 has an axial extent which is greater than a lateral extent (i.e. in the direction of the evaporator’s first lateral direction), wherein in particular the axial extent is greater than the lateral extent by a factor of at least 10, typically even at least 20.

A narrow shape of the tunnel (i.e. tunnel-shaped reaction space 12.1), a large distance between the substrate 17 and the source material 16.2, and a placement of the inlet 14 far from the source material 16.2 greatly reduce the likelihood that the reaction gas will go to the source material 16.2, thus substantially reducing the contamination rate of the source material.

The term“tunnel” may be understood as a tubular, elongated structure through a space, wherein the cross-section of the structure can be round, or rectangular, or square, or polygonal. Accordingly, a tunnel shaped reaction space may be understood as a space or chamber having a structure that is similar to a tunnel.

According to embodiments described herein, the reaction space 12.1 can be conically formed, the shape of the reaction space 12.1 resembling a truncated cone, in the axial direction.

According to embodiments described herein, the reaction space 12.1 can have a metal vapor 16.4 entrance 12.5 in a region of the evaporator 16.1, and a metal oxide vapor 16.4 exit 12.6 in a region of the substrate 17, a lateral extent of the metal vapor 16.4 entrance 12.5 being smaller than a lateral extent of the metal vapor 16.4 exit 12.6, in particular by a factor of at most 1/1.5 and/or of at least 1/10 times, in particular at least 1/2 times smaller.

The tunnel shaped design in combination with the axially conical design, wherein the reaction space 12.1 has a lateral extent that is in the evaporation region substantially smaller than in the depositing region, prevents the gas, especially the oxygen introduced in the reaction space 12.1 from moving to the evaporation region, thus averting a reactive interaction of oxygen with the source material 16.2. This effect advantageously allows for improving the process performance and the efficiency of the evaporation process, as well as increasing the lifetime of the evaporation plant and decreasing the process costs. The above specified design of the reaction space 12.1 also causes the metal oxide vapor to spread laterally uniformly upon movement to the substrate 17 so as to achieve uniform deposition on the substrate 17. This effect advantageously allows for improving an optical uniformity of the deposited layer 16.5.

The above specified design of the reaction space 12.1 further causes the partial pressure of the metal vapor 16.4 to increase, thus increasing the pressure difference between evaporator 16.1 and substrate 17. This effect increases the flow of metal vapor 16.4 from the evaporator 16.1 to the substrate 17. Since particles of metal vapor 16.4 or metal oxide vapor that are moved onto the substrate 17 may also move along gas particles, i.e. oxygen particles, in the same direction, an additional reduction in the amount of gas particles falling back on the evaporator 16.1 and causing undesirable oxidation of the source material 16.2 can be achieved.

According to embodiments described herein, ionizing the metal oxide may be performed, in particular by laser irradiation. If an electrical or electromagnetic field is applied in the interior of the reaction space 12.1, the field can exert a force on the ionized particles of metal oxide to move them to the substrate 17.

According to embodiments described herein, the tunnel as described herein may be formed by a wall that may be heated. For instance, as illustrated in particular in Fig. 3b, the tunnel may provide a wall interior 12.3 that can be heated, in particular via induction, radiation or direct-mounted heating. Heating the wall prevents particles of the metal vapor 16.4 or the metal oxide from settling on the tunnel wall. This effect advantageously allows for an increase in maintenance intervals and lifetime of the evaporation plant. The material of the wall may include carbon fiber or graphite or a metal alloy.

According to embodiments described herein, the inlet 14 can be positioned in a region of a wall 12.2 enclosing the reaction space 12.1 which is closer to the substrate 17 than to the evaporator 16.1, in particular by a factor of at least 1.5 times, particularly at least 2 times closer to the substrate 17 than to the evaporator 16.1.

According to embodiments described herein, the inlet 14 can be directed to the substrate 17, wherein in particular an ejection angle between a gas ejection direction of the inlet 14 and a longitudinal axis 12.7 of the reaction space 12.1 is less than 90°, especially less than 80°, in particular less than 70°. The longitudinal axis of the reaction space may be understood as the direction from the evaporator to the substrate.

According to embodiments described herein, the inlet 14 can have an essentially round or rectangular gas releasing opening, wherein the size, which depends on the amount of evaporated source material (Al), may be more than 5 cm² and/or less than 30 cm² in particular.

Both the position of the inlet 14 on the wall 12.2 of the reaction space 12.1 and the arrangement of the inlet 14 concerning the orientation of the inlet 14 to the substrate 17 prevent the gas, especially the oxygen introduced in the reaction space 12.1 from moving to the evaporation region, thus averting a reactive interaction of oxygen with the source material 16.2. This effect advantageously allows for improving the process performance and the efficiency of the evaporation process, as well as increasing the lifetime of the evaporation plant and decreasing the process costs.

According to embodiments described herein, the inlet 14 can be arranged on the wall 12.2 of the reaction space 12.1, in particular protruding the wall 12.2. This facilitates access to and maintenance of the inlet 14.

According to embodiments described herein, the inlet can include at least one inlet nozzle 14, wherein the number of nozzles depends on the amount of evaporated source material, the inlet including at least 5 or 10 or 20 inlet nozzles 14 in particular, which can especially be arranged uniformly about a longitudinal axis 12.7 of the reaction space 12.1, along a lateral circumference of the wall inside 12.3 of the reaction space 12.1. This facilitates a layer deposition on the substrate 17 with an improved uniformity of the deposited layer 16.5.

Further, the inlet nozzle 14 can be conical or cylindrical in the gas ejection direction. This allows for a fine and precise metering of the gas flowing into the reaction space 12.1. According to embodiments described herein, a hinge 18.7 can be integrated into the wall 12.2 of the reaction space (chamber) 12.1, thus facilitating system cleaning after the evaporation process.

Fig. lb shows a sectional view along the line AA shown in Fig. la. In this figure, an embodiment is shown according to which several inlets 14 are arranged on the wall 12.2 of the reaction space 12.1. In order to facilitate understanding of the sectional view, the inlets 14 are shown each in a vertical plan view and not in a section of their oblique position.

Fig. 2 shows a functional representation of a further vapor deposition unit 10 according to embodiments described herein. The embodiment shown here largely corresponds to the embodiment shown in FIGS la and lb. Details explained with illustrative reference to Fig. 2 shall not be understood as limited to the elements of Fig. 2. Rather, those details may also be combined with further embodiments explained with illustrative reference to the other figures.

According to the embodiment shown in Fig. 2, the vapor deposition unit 10 may include a control system 18.3. The control system 18.3 may be connected to one or more of the inline monitoring systems 18.2, inlet 14, plasma source 18.5 and power source 18.4. According to embodiments herein, the control system is configured to adjust at least one of: a power provided to the evaporation device, a power provided to the plasma source, an amount of reactive gas and an orientation of a gas flow 14.4 of the reactive gas introduced into the evaporation chamber by the gas introduction device in response to the monitoring signal of the inline monitoring device.

The inlet 14 may be arranged to provide a gas flow 14.4 of the reactive gas in a direction approximately parallel to an evaporation direction of the metal. According to embodiments herein, the orientation of the gas flow 14.4 provided by the inlet 14 may be adjusted depending on at least one of the uniformity and composition of the deposited layer 16.5. Providing the gas flow 14.4 parallel or at an acute angle to the evaporation direction of the metal may ensure a more efficient reaction between the reactive gas comprising oxygen and the evaporated metal 16.4 to form the layer 16.5 on the flexible substrate 17. Arranging the inlet 14 to introduce a reactive gas in a direction essentially parallel or at an acute angle to the evaporation direction 16.4 of the metal from the evaporator 16.1 may also help to better control the coating process by being able to more accurately control the amount of reactive gas, which interacts with the evaporated metal.

According to embodiments herein, the plasmal8.6 may be guided in a direction essentially perpendicular to the evaporation direction 16.4 of the metal, which may further help to prevent any splashing of the evaporating metal and may reduce the pinhole defects of the layer 16.5 (reactive coating) deposited on the flexible substrate 17. Due to the plasma 18.6, the reactive coating 16.5 can additionally be compacted and improved with regard to mechanical stability and electrical insulation. This makes it applicable to a wider range of substrates.

Fig. 3a shows a schematic view of a further vapor deposition unit 10 and Fig. 3b shows a sectional view along the line BB shown in Fig. 3a. According to embodiments described herein, the inlet 14 can include a gas orifice 14.1-14.3 protruding the wall 12.2, the orifice 14.1-14.3 being circumferentially formed about the longitudinal axis 12.7 of the reaction space 12.1, along a lateral circumference of the wall inside 12.3, for introducing the gas flow 14.4 into the reaction space 12.1. In more detail, according to a specific option, the inlet 14 may include one or more of the following: i) a gas entrance orifice 14.1 arranged peripherally and circumferentially on the wall outside 12.4 of the reaction space 12.1, ii) a gas exit orifice 14.2 arranged peripherally and circumferentially on the wall inside 12.3 of the reaction space

12.1, and iii) a gas guiding channel 14.3 connecting the gas entrance orifice 14.1 and the gas exit orifice 14.2. The described embodiments cause a uniform gas flow 14.4 into the reaction space 12.1, thus allowing a uniform distribution of the gas in the reaction space 12.1, which facilitates a layer deposition on the substrate 17 with an improved uniformity of the deposited layer 16.5.

According to embodiments illustrated by the figures of this disclosure, the inlet 14 can include a gas ionizer for ionizing the gas flow 14.4 or an ion source for generating an ionized gas flow 14.4, wherein the gas flow 14.4 includes ionized particles. If an electrical or electromagnetic field is applied in the interior of the reaction space 12.1, the field can exert a force on the ionized gas particles to move them to the substrate 17. In this way, the gas particles can be prevented from moving toward the evaporator 16.1 or the source material

16.2, thus preventing a reactive interaction of oxygen with the source material 16.2. Fig. 4 shows a schematic view of an evaporation chamber of a further vapor deposition unit 10. According to embodiments described herein, the vapor deposition unit 10 can include a steering element placed between the evaporator 16.1 and the inlet 14. The steering element can be configured for generating a force designed to act i) on the ionized particles of the metal vapor 16.4 by moving and/or accelerating the metal vapor 16.4 particles to the substrate 17 and ii) on the ionized particles of the gas flow 14.4 by preventing the gas particles from approaching the source material 16.2. Said force can originate from an adequately directed electric or electromagnetic field.

According to embodiments described herein, the evaporator 16.1 can be designed to generate an ionized metal vapor 16.4 comprising ionized particles. If an electrical or electromagnetic field is applied in the interior of the reaction space 12.1, the field can exert a force on the ionized particles of metal vapor 16.4 to move them to the substrate 17. This effect can increase the flow 14.4 of metal vapor 16.4 from the evaporator 16.1 to the substrate 17. Since particles of metal vapor 16.4 or metal oxide vapor that are moved onto the substrate 17 may also move along gas particles, i.e. oxygen particles, in the same direction, an additional reduction in the amount of gas particles falling back on the evaporator 16.1 and causing undesirable oxidation of the source material 16.2 can be achieved.

According to embodiments described herein, the particles of the metal vapor 16.4 and the particles of the gas flow 14.4 can be oppositely charged ions. If an adequately directed electrical or electromagnetic field is applied in the interior of the reaction space 12.1, the field can exert a force on the ionized particles of both gas and metal vapor 16.4 to move the ionized particles in the same direction, to the substrate 17.

The above-described electric force allows several effects to be achieved. Firstly, the gas particles can be prevented from moving toward the evaporator 16.1 or the source material 16.2, thus preventing a reactive interaction of oxygen with the source material 16.2. Secondly, both gas and metal vapor 16.4 move to the substrate 17 at a higher speed, which shortens process times and increases process speed. Thirdly, the local oxidation region of the metal vapor 16.4 is limited to a range between the gas inlet 14 and the substrate 17, the range being apart or even far away from the source material 16.2. As a result, the reaction space 12.1 is worn up in a limited range that is spaced from the source material 16.2, thus allowing an increase in maintenance intervals and lifetime of the evaporation plant, an increase in process performance and efficiency of the evaporation process and in productivity, and a decrease in process costs.

An adequately oriented electric field can be understood in that, due to the positively charged gas particles and negatively charged metal vapor particles, the electric field lines are directed toward the substrate 17, in particular substantially axially toward the substrate 17. In the case of negatively charged gas particles and positively charged metal vapor particles, the electric field lines are directed towards the source, substantially axially toward the source.

In more detail, according to a specific option, the steering element 20 can include i) an electrode with a centrally positioned aperture, or ii) a grid, or iii) metal plates which are parallel to each other, wherein a bias potential is applied to the steering element.

Alternatively, a coil system can be provided for producing an electromagnetic field in the reaction space 12.1.

The electric field produced within the reaction space 12.1 is capable of directing the ionized particles of gas and metal vapor 16.4 in a common direction toward the target. In addition, each of the steering elements i) to iii) is poled or electrically charged such that the ionized gas particles coming from the inlet 14 into the reaction space 12.1 are repelled by the steering element 20, thus being prevented from approaching and contaminating the source material 16.2 or the metal vapor 16.4 in the evaporation region.

Hence, the present disclosure allows for overcoming previous set-ups where a considerable portion of the gas flow is disadvantageously directed to the source material, so that the metal is already oxidized in a solid or molten state, before or immediately after evaporation. The metal oxide produced in this way occludes the evaporation region and constitutes a contamination of the source material or the evaporator. This has a variety of disadvantages:

- the process performance, the efficiency of the evaporation process and the productivity decrease,

- the lifetime of the evaporation plant decreases,

- the process costs increase,

- the coating process becomes restless and the process control becomes unstable,

- the optical uniformity of the coating deteriorates, - splashes affecting the barrier performance of the coating may occur.

If the oxygen concentration is increased to allow for depositing completely

stoichiometric AlOx layers, then the negative effects listed above become even worse.

Even though these problems may be particularly crucial for reactively depositing aluminum oxide, similar problems might occur for other deposition processes where metals or other materials are reactively deposited as oxides, nitrites or other forms. Typical further materials can be Bi, Zn, Sn, In and Ag.

This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the described subject-matter, including making and using any apparatus or system and performing any incorporated methods. Embodiments described herein provide an improved method and apparatus for producing a separator having a high porosity for good ionic conductivity, complex pore structure with no/reduced pinhole or through-hole defects to suppress shorts, excellent thermal and mechanical stability and can be produced at low cost. While various specific embodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. A method of vapor depositing an insulation layer of a metal oxide, in particular an aluminum oxide, on a substrate, the method comprising:

vaporizing a metal, in particular aluminum, from a source material comprising the metal;

introducing a gas flow comprising oxygen such that an interaction of the oxygen with the source material is prevented;

generating a metal oxide vapor from the interaction of the metal vapor with the oxygen; and

directing the metal oxide vapor to the substrate.

2. The method of claim 1, wherein the interaction of the oxygen with the source material is prevented by at least one of:

exerting on oxygen particles a force that is directed to the substrate, in particular a force due to a difference in partial pressure of the metal vapor between the source material and the substrate and/or an electric force and/or a magnetic force;

generating the metal oxide vapor in an oxidation region that is spaced apart from the source material;

introducing the gas flow into an inlet region that is closer to the substrate than to the source material, in particular by a factor of at least 1.5 closer to the substrate than to the source material;

introducing the gas flow in a direction facing the substrate, in particular at a rate of 1 m/s to 100 m/s and is especially guided in a stream with a diameter of 1 mm to 10 cm;

performing the movement of metal vapor particles toward the substrate in a reaction space that is formed tunnel-shaped and/or conically in an axial direction, in particular by providing a reaction space having a lateral extent of a metal vapor entrance that is smaller than a lateral extent of a metal vapor exit, especially by a factor of at least 1/10 times and/or at most 1/1.5 smaller than the lateral extent of the metal vapor exit.

3. The method of any of claims 1 or 2, wherein exerting on oxygen particles a force that is directed to the substrate comprises at least one of:

ionizing the gas flow so that the gas flow comprises ionized particles; ionizing the particles of the gas flow by a laser beam and/or a high voltage; exerting the electric force on the ionized metal vapor particles, thus moving the particles to the substrate.

4. The method of any of claims 1 to 3, wherein directing the metal oxide vapor to the substrate comprises at least one of:

ionizing the metal vapor so that the metal vapor comprises ionized particles;

generating the ionized particles such that the metal vapor and the gas flow comprise oppositely charged ions;

the electric force acts on the ionized particles i) of the metal vapor by moving and/or accelerating the particles to the substrate and ii) of the gas flow by preventing the particles from approaching the source material.

5. The method of any of claims 1 to 4, wherein directing the metal oxide vapor to the substrate comprises at least one of:

continuing a previously initiated movement of the metal vapor after the oxidation; carrying the particles of the metal oxide vapor through the gas flow directed towards the substrate.

6. The method of any of claims 1 to 5, wherein generating a metal oxide vapor comprises at least one of:

thermal evaporation or electron beam evaporation;

heating an evaporator in which the metal has been introduced, in particular by electrically heating the evaporator;

feeding a metal wire into the evaporator, in particular by rolling the metal wire from a roll.

7. A vapor deposition unit for vapor depositing an insulation layer of metal oxide, in particular aluminum oxide, on a substrate, the vapor deposition unit comprising:

an evaporator for evaporating a source material, the material comprising a metal, in particular aluminum, so as to generate a metal vapor from the source material;

a reaction space comprising an inlet for introducing oxygen, the reaction space being configured to allow the metal vapor to react with the oxygen in an oxidation region spaced apart from the source material, to generate a metal oxide vapor in the oxidation region, such that a reactive interaction of oxygen with the source material is prevented.

8. The vapor deposition unit according to claim 7, comprising at least one of the following features:

the inlet is positioned in a region of a wall enclosing the reaction space which is closer to the substrate than to the evaporator, in particular by a factor of at least 1.5 closer to the substrate than to the evaporator;

the inlet is directed to the substrate, wherein in particular an ejection angle between a gas ejection direction of the inlet and a longitudinal axis of the reaction space is less than 90°, especially in a range of 20° to 70°.

9. The vapor deposition unit according to any of claims 7 or 8, comprising at least one of the following features:

the reaction space is formed tunnel-shaped in the axial direction, wherein the reaction space has an axial extent which is greater than a lateral extent, wherein in particular the axial extent is greater than the lateral extent by a factor of at least 10, especially at least 20.

a wall inside is heated to prevent particles of the metal vapor or the metal oxide from settling on the wall inside;

the reaction space is conically formed in the axial direction;

the reaction space has a metal vapor entrance in a region of the evaporator, and a metal oxide vapor exit in a region of the substrate, a lateral extent of the metal vapor entrance being smaller than a lateral extent of the metal vapor exit, the lateral extent of the metal vapor entrance being in particular by a factor of at least 1.1 and/or at most 10 times smaller than the lateral extent of the metal vapor exit.

10. The vapor deposition unit according to any of claims 7 to 9, comprising at least one of the following features:

the inlet is arranged on the wall of the reaction space, in particular protruding the wall; the inlet comprises at least one inlet nozzle;

the inlet nozzle is conical or cylindrical in the gas ejection direction;

the inlet comprises at least 5 or 10 or 20 inlet nozzles, which are in particular arranged uniformly about a longitudinal axis of the reaction space, along a lateral circumference of the wall inside of the reaction space.

11. The vapor deposition unit according to any of claims 7 to 10, comprising at least one of the following features:

the inlet comprises a gas orifice protruding the wall, the orifice being circumferentially formed about the longitudinal axis of the reaction space, along a lateral circumference of the wall inside, for introducing the gas flow into the reaction space;

the inlet comprises i) a gas entrance orifice arranged peripherally and circumferentially on an outside of the wall of the reaction space, ii) a gas exit orifice arranged peripherally and circumferentially on the wall inside of the reaction space, and iii) a gas guiding channel connecting the gas entrance orifice and the gas exit orifice.

12. The vapor deposition unit according to any of claims 7 to 11, comprising at least one of the following features:

the inlet comprises a gas ionizer for ionizing the gas flow or an ion source for generating an ionized gas flow, wherein the gas flow comprises ionized particles;

the evaporator is designed to generate an ionized metal vapor comprising ionized particles.

13. The vapor deposition unit according to claim 12, wherein the particles of the metal vapor and the particles of the gas flow are oppositely charged ions.

14. The vapor deposition unit according to any of claims 7 to 13, comprising a steering element placed between the evaporator and the inlet, the steering element generating an electric force designed to act i) on the ionized particles of the metal vapor by moving and/or accelerating the metal vapor particles to the substrate and ii) on the ionized particles of the gas flow by preventing the gas particles from approaching the source material.

15. The vapor deposition unit according to claim 14, wherein the steering element comprises i) an electrode with a centrally positioned aperture, or ii) a grid, or iii) metal plates which are parallel to each other, wherein in cases i) to iii) a bias potential is applied to the steering element, or iv) a coil system for producing an electromagnetic field in the reaction space.