Method of depositing material on a substrate

Abstract

A method of depositing a material on a substrate is provided, the method comprising: generating a plasma remote from one or more sputtering targets adapted for plasma sputtering, wherein at least one different region of the one or more targets comprises an alkali metal, an alkaline earth metal, an alkali metal-containing compound, an alkaline earth metal-containing compound, or a combination thereof; generating a sputtered material from the one or more targets using the plasma; and depositing the sputtered material on a substrate, the working distance between the target and the substrate being within + / - 50% of the theoretical mean free path of the system.

Description

TECHNICAL FIELD

[0001] The present invention relates to depositing material on a substrate. More particularly, but not exclusively, the present invention relates to a method of depositing material on a substrate. The present invention also relates to a method of determining an optimal working distance and / or an optimal working pressure for a remote plasma deposition system, a method of manufacturing a battery pack and a battery pack. BACKGROUND

[0002] The use of plasma deposition to deposit material is well known to those skilled in the art. In some cases, the control of such deposition can be difficult and it can be necessary to optimise the deposition conditions to ensure that the material deposited on the substrate has the required properties and / or structure.

[0003] The present invention seeks to alleviate the above problems. Alternatively or additionally, the present invention seeks to provide an improved method of depositing material. SUMMARY

[0004] The present disclosure relates to a method of depositing material by plasma sputtering techniques.

[0005] More particularly, the present disclosure relates to a method of depositing material by plasma sputtering techniques, wherein a plasma is generated remote from the material to be sputtered.

[0006] According to a first aspect of the present invention, there is provided a method of depositing material on a substrate, the method comprising:

[0007] generating a plasma remote from one or more plasma targets suitable for plasma sputtering, wherein at least one different region of the one or more targets comprises an alkali metal, an alkaline earth metal, an alkali metal containing compound, an alkaline earth metal containing compound or a combination thereof.

[0008] exposing the one or more plasma targets to the plasma, thereby sputtering material from the one or more targets,

[0009] depositing the sputtered material on the substrate, the working distance between the target and the substrate being in the range + / - 50% of the theoretical mean free path of the system.

[0010] Without wishing to be bound by theory, it is believed that the working distance has an effect on the "ad atom" energy of the sputtered material as it is deposited onto the substrate. In the case where the working distance is greater than the mean free path of the system, it is believed that the ions in the sputtered flux are more likely to collide before reaching the substrate, resulting in a relatively lower "ad atom" energy. Conversely, if the working distance is shorter than the mean free path of the system, then the "ad atom" energy is relatively higher.

[0011] The definition of the mean free path is the average distance between ion collisions in a plasma. The mean free path is calculated from the volume of interaction (which varies with working distance) and the number of molecules per unit volume (which varies with working pressure).

[0012] The working distance can optionally be from 50% of the theoretical mean free path of the system to 150% of the theoretical mean free path of the system, optionally from 70% of the theoretical mean free path of the system to 120% of the theoretical mean free path of the system, and optionally from 80% of the theoretical mean free path of the system to 100% of the theoretical mean free path of the system.

[0013] The working distance can optionally be at least 3.0 cm, optionally at least 4.0 cm, optionally at least 5.0 cm, optionally at least 6.0 cm, optionally at least 7.0 cm, and optionally at least 8.0 cm. The working distance can optionally be no more than 20 cm, optionally no more than 15 cm, optionally no more than 13 cm, optionally no more than 12.0 cm, optionally no more than 10.0 cm, and optionally no more than 9.0 cm. The working distance between the target and the substrate can optionally be from 3.0 cm to 20.0 cm, optionally from 4.0 cm to 15.0 cm, optionally from 5.0 cm to 13.0 cm, optionally from 6.0 cm to 12.0 cm, optionally from 7.0 cm to 10.0 cm, and optionally from 8.0 cm to 9.0 cm.

[0014] The working distance can be shorter than the mean free path of the sputtered material.

[0015] Without wishing to be bound by theory, at too short a working distance, the energy of the sputtered material can be high enough to deform or damage the substrate. The sputtered flux with so much energy can also lead to the formation of an undesirable high-energy oxide state due to plasma-induced induction in the sputtered flux. Preferably, the working distance will be longer than a lower limit defined by when substrate damage or / and formation of an undesirable oxide state is observed.

[0016] The working distance can be from 3.0 to 20.0 cm.

[0017] The working distance can be from 5.0 cm to 15 cm. Within this range, material can be deposited, a small amount of undesirable oxide formed in the film, and the ad atom energy remains relatively high.

[0018] The working distance can be from 6.0 cm to 14.0 cm. The working distance can be from 7.0 cm to 13.0 cm.

[0019] The working distance can be from 8.0 cm to 12 cm. Within this range, crystalline material forms with primary crystallite platelets, particularly for layered oxide materials.

[0020] The working distance can be from 8.0 cm to 9.0 cm. Within this range, a higher proportion of the crystalline material is in a layered oxide structure.

[0021] The working pressure can be defined as the chamber pressure prior to remote plasma initiation. The working pressure can be constant throughout the deposition process, or can fluctuate slightly as the target outgases or as the target ages throughout the deposition process.

[0022] The applicants have found that it is possible to form a crystalline film of the material directly on the substrate. By "directly" it is meant that the film forms a crystalline film without a substantial annealing step. This has proven to be true even for materials that form high energy crystal structures that otherwise require an annealing step. The method has proven to be effective for a wide range of substrate materials.

[0023] In a remote plasma system, the plasma is generated remotely from the plasma target. In traditional plasma deposition, the bias of the target is what generates and sustains the plasma. In a remote plasma deposition system, the plasma is generated elsewhere and then directed to the target through various electronic and / or magnetic fields. The bias of the target allows for control of the sputtering rate.

[0024] The deposited material can be crystalline. At least a portion and optionally all of the deposited material can have a hexagonal crystal structure. At least a portion and optionally all of the deposited material can have a crystalline "layered oxide" structure. Such a "layered oxide" structure is important in the manufacture of solid state batteries. The layered oxide structure makes it easier for alkali metal ions to be extracted from the crystal structure, resulting in faster charging, higher capacity solid state batteries.

[0025] The layered oxide framework can generally be defined by the formula ABO2, where A is generally an alkali metal ion, an alkaline earth metal ion, or a mixture, and B is generally one or more redox active transition metals, one or more transition metals, or a mixture thereof. Element metals in the so-called "post-transition metal" group, such as aluminum, can also be incorporated into the layered oxide framework.

[0026] The advantage of not requiring an annealing step to form the crystalline material is that a relatively low melting point substrate can be used. The substrate can include a polymer. The substrate can be flexible. The substrate can include polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). PEN and PET have considerable flexibility and relatively high tensile strength due to their semi-crystalline structure. The temperature of the substrate can not exceed 200 degrees at any point during the plasma deposition process.

[0027] The deposition can occur in a reactive atmosphere that includes oxygen.

[0028] The working pressure can optionally be at least 0.0005 mBar, optionally at least 0.00065 mBar, optionally at least 0.0010 mBar, optionally at least 0.0020 mBar, optionally at least 0.0030 mBar, optionally at least 0.0040 mBar, and optionally at least 0.0045 mBar. The working pressure can optionally be no more than 0.0100 mBar, optionally no more than 0.0090 mBar, optionally no more than 0.0080 mBar, optionally no more than 0.0070 mBar, and optionally no more than 0.0065 mBar. The working pressure can optionally be from 0.0005 mBar to 0.0100 mBar, optionally from 0.0020 mBar to 0.0090 mBar, optionally from 0.0030 mBar to 0.0080 mBar, optionally from 0.0040 mBar to 0.0070 mBar, and optionally from 0.0045 mBar to 0.0065 mBar.

[0029] The working pressure can be from 0.0010 mBar to 0.0065 mBar. Higher working pressures within this range can result in higher deposition rates. This is because higher working pressures result in more process ions (typically Ar+) bombarding the surface of the target, thus material is sputtered from the target at a higher rate.

[0030] When the working pressure is between 0.0010 mBar and 0.0065 mBar, the crystalline material formed can have a crystallite size (size of the crystalline platelets) of 8-65 nm. Generally, larger crystallite sizes result in a higher proportion of the thin film being ordered material, as a lower percentage of the thin film is comprised of disordered grain boundary material. This is important for thin film batteries as larger crystallite sizes generally result in thin film batteries having a higher usable capacity. The crystallite size within this range can be observed when the alkali metal containing material optionally comprises at least one of the following compounds (described here in non-specific stoichiometry): LiCoO, LiCoAlO, LiNiCoAlO, LiMnO, LiNiMnO, LiNiMnCoO, LiNiO, and LiNiCoO.

[0031] When the working distance is 8.0 to 9.0 cm, the range of available crystallite sizes can be narrower if a working pressure of 0.0010 mBar to 0.0065 mBar is used. The crystallite size can be 14 to 25 nm. This demonstrates that within these ranges of parameters, thin films can be formed with a narrow and predictable range of thin films. This can be important as it can make the deposition step more predictable and repeatable on an industrial scale.

[0032] Without wishing to be bound by theory, it is believed that the layered oxide structure requires a high activation energy to form. The working pressure is directly related to the energy in the system. Therefore, there can be a lower limit to the working pressure below which the desired layered oxide structure will not form. Preferably, the working pressure is above a lower limit defined by a pressure below which the desired layered oxide structure does not form, such that there is sufficient activation energy in the system to form the desired layered oxide structure. For example, in the case of an alkali metal containing compound that is LiCoO2, the characteristic X-ray diffraction peak of the layered oxide structure is shown at 19 degrees 2Theta (associated with the 003 plane). If the working pressure of the system is too low, the desired layered oxide structure can not form and the characteristic peak can not be present.

[0033] The working pressure can be at least 1.2e-3 mBar. Preferably, the working pressure is at least 4.6e-3 mBar.

[0034] At high working pressures, the energy in the system can be so high that the substrate begins to be damaged. The damage can be caused by the elevated temperature caused by the plasma. Preferably, the working pressure is below an upper limit, wherein the upper limit is defined by a pressure above which observable damage to the substrate occurs. Preferably, the working pressure is below 0.0065 mBar.

[0035] The alkali metal, if present, can optionally be one or more of lithium, sodium, potassium, cesium, and rubidium, optionally one or more of lithium, sodium, or potassium, optionally one or more of lithium or sodium, and optionally lithium. Lithium ions are sometimes used as a conductive species in solid state battery cathodes. The alkaline earth metal, if present, can optionally be one or more of magnesium, calcium, strontium, or barium, optionally one or more of magnesium, calcium, and barium, and optionally one or both of magnesium and calcium.

[0036] The one or more transition metals and / or the one or more redox active transition metals can be in Period 4 or Period 5 of the Periodic Table. The following statements refer to transition metals that can or can not be redox active. At least one and optionally each transition metal can optionally be selected from iron, cobalt, manganese, nickel, titanium, niobium, and vanadium.

[0037] The material deposited on the substrate can have the empirical formula A a M1 b M2 c O2, wherein A is an alkali metal (optionally lithium), M1 is one or more transition metals (optionally one or more of cobalt, nickel, niobium, vanadium, and manganese) (b is the sum of transition metals), M2 is aluminum, a is 0.5 to 1.5, and z is 0 to 0.5.

[0038] Optionally, a is 1, b is 1, and c is 0. Optionally, M1 is one of cobalt, nickel, vanadium, niobium, and manganese.

[0039] Optionally, a is greater than 1 and A is lithium. In this case, the materials are sometimes referred to as "lithium rich" materials. For example, such a lithium rich material can be where x = 0, 0.06, 0.12, 0.2, 0.3 and 0.4.

[0040] Another such material is where y has a value greater than 0.12 and equal to or less than 0.4.

[0041] Another such material is where x has a value equal to or greater than 0.175 and equal to or less than 0.325; and y has a value equal to or greater than 0.05 and equal to or less than 0.35.

[0042] is another such material, where x is equal to or greater than 0 and equal to or less than 0.4; y is equal to or greater than 0.1 and equal to or less than 0.4; z is equal to or greater than 0.02 and equal to or less than 0.3.

[0043] The alkali metal containing material can comprise lithium. The alkali metal containing material can comprise at least one of the following compounds (described here in non-specific stoichiometry): LiCoO, LiCoAlO, LiNiCoAlO, LiMnO, LiNiMnO, LiNiMnCoO, LiNiO and LiNiCoO.

[0044] The method can comprise moving the substrate and depositing sputtered material on the substrate, thereby forming material on the substrate. For example, if material is deposited on a first portion of the substrate, the substrate can be moved and material deposited on a second portion of the substrate.

[0045] This facilitates reasonably fast production of relatively large areas of material.

[0046] The substrate can comprise or be in the form of a sheet, optionally an elongate sheet. Such a sheet can be provided in the form of a roll or a stack. Preferably, the substrate is provided in the form of a roll. This facilitates simple and safe storage and handling of the substrate.

[0047] The substrate can be movably mounted to facilitate movement of the substrate (optionally in the form of a sheet). The substrate can be mounted in a roll-to-roll manner. The substrate upstream of the plasma deposition process is held on a roll or drum. The substrate downstream of the plasma deposition process is held on a roll or drum. This facilitates simple and fast handling of a flexible substrate. A shutter can be provided to allow a portion of the substrate to be exposed to the remotely generated plasma.

[0048] Using a roll-to-roll arrangement has many advantages. It facilitates a high material throughput and allows for deposition of large material areas on one large substrate, although a series of depositions are made on a first portion of the substrate, followed by a second portion of the substrate, and so on. One of the main advantages of a roll-to-roll process is that it allows for a large number of depositions to be made without breaking the vacuum. This saves both time and energy compared to systems where the chamber needs to be brought from vacuum back to atmospheric pressure in order to load a new substrate after deposition.

[0049] The upstream drum or roller for carrying the substrate can be located inside the processing chamber or outside the chamber. The downstream drum or roller for carrying the substrate can be located inside the chamber or outside the chamber.

[0050] The substrate can be provided in the form of discrete sheets that are processed and stored in a relatively flat sheet. The shape of the substrate can be planar when material is deposited on the substrate. This can be the case when the substrate is provided in the form of discrete sheets that are not transferred to or from a roller. The sheets can each be mounted on a carrier that has greater structural rigidity. This can allow the use of thinner substrates than would be the case if the substrate film was held on a roller. The substrate can be a sacrificial substrate. The substrate can be removed prior to the material layer. The substrate can be removed in part or in whole prior to integrating the crystalline layer or a portion thereof into an electronic product package, component, or other end product. For example, the crystalline material layer can be peeled from the substrate. There can be other intermediate material layers between the base substrate and the crystalline material. The layer can be peeled with the crystalline material or facilitate separation of the crystalline material from the base substrate. Laser-based peeling techniques can be used. The substrate can be removed by a process that utilizes laser ablation.

[0051] Similar techniques are described in the prior art. For example, KR20130029488 describes a method of manufacturing a battery including using a sacrificial substrate and laser radiation to harvest a battery layer. In other examples, another suitable processing scheme is used so long as it is capable of a high enough production throughput.

[0052] The substrate can optionally not exceed its temperature-corrected yield strength at any point as it passes between the upstream and downstream rollers or drums. This is important because roll-to-roll processing machines need to put the substrate under tension as it passes through various rollers, rollers, and drums feed. As the polymer warms up, its yield strength can start to decrease. If the polymer temperature rises too much, the polymer can start to deform as it passes through the roll-to-roll machine. This can cause distortion, jamming, and uneven deposition on the substrate.

[0053] The temperature of the substrate during deposition is optionally no more than 500°C, optionally no more than 300°C, optionally no more than 200°C, optionally no more than 150°C, optionally no more than 120°C, and optionally no more than 100°C. The method of the present invention can be performed at low temperatures, which facilitates the use of substrates and other materials that can not be usable at higher temperatures. Furthermore, it can be more difficult to handle substrates at higher temperatures.

[0054] The area measured on the surface opposite to the surface onto which the material is deposited is 1 cm 2 The maximum temperature reached by any given square substrate material at any given time and averaged over a period of 1 second is no more than 500°C, optionally no more than 300°C, optionally no more than 200°C, optionally no more than 150°C, optionally no more than 120°C and optionally no more than 100°C.

[0055] The thickness of the alkali metal containing compound deposited when the method is complete is optionally no more than 10 microns, optionally no more than 1.0 microns.

[0056] The thickness of the substrate is optionally no more than 1.6 microns. The thickness of the substrate provided is optionally less than 1.0 microns.

[0057] This is beneficial when designing solid state batteries for substrates that are as thin as possible. This allows the manufacture of batteries with higher energy density. Preferably, if thinner substrates become available that meet the necessary requirements of a relatively high temperature corrected yield strength and a high degradation point, then such substrates will be used in the method.

[0058] In the case where the alkali metal containing compound is LiCoO2, the crystals are optionally aligned with the (101) and (110) planes substantially parallel to the substrate. This is beneficial because it means that the ion channels of the thin film are oriented perpendicular to the substrate, making it easier for ions to intercalate and deintercalate from the battery. This improves the working capacity and charging speed of the battery.

[0059] The substrate optionally comprises a current collector layer. The current collector layer can comprise an inert metal. The current collector layer can be platinum. The current collector layer can be nickel. The current collector layer can be gold. The current collector layer can be platinum. The current collector layer can be aluminium. The current collector layer can have an improved structure to increase its surface area. The current collector layer can also act as an anode.

[0060] The deposition rate can be greater than The deposition rate can be greater than The deposition rate can be greater than

[0061] The method can comprise providing first and second targets. The target material of the first target and the second target can optionally be different. The orientation of the first and second targets relative to the substrate can be different to each other.

[0062] The method can include exposing the first target to the plasma and exposing the second target to the plasma, thereby sputtering material from the first target and the second target. The substrate can be exposed to the material sputtered from the first and second targets. The sputtering of material from the first target can produce a first plume corresponding to particle trajectories from the first target assembly onto the substrate. The sputtering of material from the second target can produce a second plume corresponding to particle trajectories from the second target assembly onto the substrate. The first and second plumes can converge at the substrate. The first and second targets can be configured such that more plasma energy can be received at one of the first and second targets than at the other of the first and second targets. This can be beneficial if more energy is required to sputter material of the first or second target than to sputter material of the other of the first or second target. For example, if the first target includes the element lithium and the second target material includes cobalt, the first and second targets can be configured such that the second target receives more plasma energy than the first target because cobalt requires more energy than lithium to sputter from a target.

[0063] The method can include containing and shaping the plasma using a magnetic field and / or an electrostatic field such that the shape of the electron density profile of the plasma is the same within an error range for any given cross section across most of the width of the plasma. The error range can optionally be up to 30%, optionally up to 20%, optionally up to 10% and optionally up to 5%.

[0064] The shape of the electron density profile of the plasma is optionally the same within an error range. This can be tested by visual inspection, the visible light being substantially the same along the width of the plasma. The plasma can be blanket-like. In this regard, the width and length of the visible plasma cloud can each be at least five times the thickness.

[0065] The generation of the plasma can be performed by at least one antenna extending in a direction parallel to the width of the substrate. The generation of the plasma can be performed using a pair of antennas separated by a distance L on opposite sides of the plasma, each antenna having a length W. The thickness of the plasma (defined as the maximum extent of the glow in the visible spectrum or the maximum distance measured in a direction perpendicular to L and W, covering 90% of the free electrons in the plasma).

[0066] The first or second target can be closer to the plasma than the other of the first and second targets. This arrangement can facilitate the first or second target receiving more plasma energy than the other of the first and second targets.

[0067] For any given cross-section taken across a substantial width of the plasma, the first or second target can form a different angle with the horizontal plane than the other of the first and second targets. Such an arrangement can facilitate the first or second target receiving more plasma energy than the other of the first and second targets.

[0068] One or both of the first and second targets can be planar.

[0069] For any given cross-section taken across a substantial width of the plasma, the target of the second target assembly presents substantially the same amount of material to the plasma as the target of the first target assembly.

[0070] One or more targets are optionally opposite the substrate. Such an arrangement is effective when the plasma is generated remotely.

[0071] The surface on which material is deposited can have a surface roughness of X S or less, where X S = 100 nm, the deposited layer can have a thickness of 0.01-10 μm and a surface roughness of no more than X1, where X1 is equal to the product of F and X S , where F is a factor in the range of 1-2.

[0072] X S may be no more than 10% of the substrate thickness. The product of the substrate thickness and X S may be no more than 10 5 nm 2 .

[0073] The substrate, optionally a polymeric substrate, can be provided with embedded particles, and of all the embedded particles within or on the polymeric material, the majority of the particles that contribute to the substrate surface roughness have a median size of 10% to 125% of Xs.

[0074] Alternatively, the substrate, optionally a polymeric substrate, can be provided with embedded particles, and of all the embedded particles within or on the polymeric material, the majority of the particles that contribute to the substrate surface roughness have a median size of no less than 150% of Xs.

[0075] The method can include the step of depositing material onto the surface using sputter deposition to form another layer having a thickness of from 0.01 to 10 μm and a surface roughness of no more than 150% of X S , the material composition of the crystalline layer being different from the material composition of the other layer.

[0076] The method can include sputtering material plasma from a first target comprising an alkali or alkaline earth metal onto a surface of a substrate or a surface supported by a substrate, at least a first plume corresponding to trajectories of particles from the first target onto the surface being present, and sputtering material plasma from a second target comprising a transition metal (e.g. cobalt) onto the surface, at least a second plume corresponding to trajectories of particles from the second target onto the surface being present, and wherein the first target is positioned non-parallel to the second target, the first plume and the second plume converging in a region proximate to the surface of the substrate or the surface supported by the substrate, and an optional crystalline layer is formed on the surface of the region.

[0077] More plasma energy can be received at the first target than at the second target.

[0078] The first target can face the substrate in a first direction, and the second target can face the substrate in a second direction, the first and second directions converging towards the substrate.

[0079] An imaginary line extending from a surface center of the first target parallel to the first direction can intersect in cross-section with an imaginary line extending from a surface center of the second target parallel to the second direction at a position closer to the substrate than to either target.

[0080] The position of intersection can be closer to the substrate than half the shortest distance from either target to the substrate.

[0081] The substrate and at least one of the first and second targets can be moved as the optional crystalline layer is formed on the surface.

[0082] The substrate can have a radius of curvature at the region where the first plume and the second plume converge, and the targets are arranged circumferentially around a center of the radius of curvature.

[0083] According to a second aspect of the invention, there is provided a method of determining an optimum working distance for a remote plasma deposition system configured to deposit a layered oxide material, wherein the method comprises:

[0084] selecting a range of working distances such that the theoretical mean free path of the system falls within said range,

[0085] for a plurality of test samples, for each respective sample, performing the method according to the first aspect of the invention at different working distances within the selected range,

[0086] performing X-ray diffraction on each test sample after deposition has occurred,

[0087] identifying samples in which a characteristic diffraction peak of a layered oxide structure is present,

[0088] From those samples, the sample is selected in which the (normalised) intensity of the characteristic peak is highest, and the working distance of the system is then selected to be the distance used during deposition of the test sample.

[0089] The test samples of the method can optionally be replaced by an average of a plurality of test samples, comprising a plurality of test samples in which the method of the first aspect of the application has been performed a plurality of times at the same working distance, and the average taken. The method can further comprise any standard error analysis techniques known to the person skilled in the art.

[0090] The method can optionally be performed a plurality of times, so that a range of optimal working distances for operating the system can be found.

[0091] According to a third aspect of the application, there is provided a method of determining an optimal working pressure range for a remote plasma deposition system for depositing a layered oxide material, wherein the method comprises:

[0092] selecting an initial range of working pressures, from 0.00065 mBar to 0.01 mBar (optionally between 0.001 mBar and 0.007 mBar),

[0093] for a plurality of test samples, for each respective sample, performing the method according to the first aspect of the application at different working pressures within the selected range,

[0094] performing X-ray diffraction on each test sample after deposition has occurred,

[0095] selecting the test sample deposited at the lowest working pressure from the group of test samples having characteristic X-ray diffraction peaks of the layered oxide material, and setting this working pressure as the lower limit of the range,

[0096] selecting the test sample deposited at the highest working pressure from the group of test samples which did not show observable signs of substrate damage, and setting this working pressure as the upper limit of the range.

[0097] The initial range of working pressures can be selected according to the selection of working pressures described above in relation to the method of the application. The test samples of the method can optionally be replaced by an average of a plurality of test samples, comprising a plurality of test samples in which the method of the first aspect of the application has been performed a plurality of times at the same working pressure, and the average taken. The method can further comprise any standard error analysis techniques known to the person skilled in the art.

[0098] The method can further comprise selecting an optimal working pressure for the system within the desired range. The optimal working pressure can be the working pressure within the range which results in the highest deposition rate.

[0099] It will of course be understood that features described with reference to one aspect of the application can be incorporated into other aspects of the application. BRIEF DESCRIPTION OF DRAWINGS

[0100] Embodiments of the application will now be described by way of example only and with reference to the accompanying schematic drawings, which can be briefly summarised as follows.

[0101] Figure 1a is a schematic side view of a plasma deposition chamber used according to the first example;

[0102] Figure 1b shows steps of a method of manufacturing a battery cathode according to the first example;

[0103] Figures 1c to 1h is a cross-sectional schematic view of various polymer substrate materials;

[0104] Figure 2a is a schematic side view of a plasma deposition chamber used according to the second example method;

[0105] Figure 2b is an X-ray diffraction (XRD) spectrum of a first sample of a battery cathode manufactured according to the method of the second example;

[0106] Figure 2c is a Raman spectrum of a battery cathode group from which the XRD data of Figure 2b was obtained;

[0107] Figure 2d is an XRD spectrum of a second sample of a battery cathode manufactured according to the method of the second example;

[0108] Figure 2e is a Raman spectrum of a battery cathode from which the XRD data of Figure 2d was obtained;

[0109] Figure 3a is a schematic side view of a plasma deposition chamber used in a method according to the third example;

[0110] Figure 3b is a plan view schematic of the plasma deposition chamber shown in Figure 3a ;

[0111] Figure 3c is another schematic side view of the plasma deposition chamber shown in Figure 3a and 3b ;

[0112] Figure 3d is a graph comparing sputter yields of cobalt and lithium as a function of energy;

[0113] Figure 3eis a schematic side view of a plasma deposition chamber used in the method according to the fourth example;

[0114] Figure 4a is a cross-sectional scanning electron micrograph of a battery cathode relating to a first sample prepared according to the method of the second example;

[0115] Figure 4b is a bird's eye view of a scanning electron micrograph of a battery cathode relating to a second sample prepared according to the method of the second example;

[0116] Figure 5a is a schematic cross-sectional view through a battery cathode relating to a first sample prepared using the method of the fifth example;

[0117] Figure 5b is a schematic cross-sectional view through a battery cathode relating to a second sample prepared using the method of the fifth example;

[0118] Figure 5c shows steps of a method of manufacturing a battery cathode half-cell according to the fifth example;

[0119] Figure 6 is a schematic diagram of an example of a method of manufacturing a battery cell according to the sixth example;

[0120] Figure 7a is a schematic diagram of an example of a method of manufacturing a solid state thin film battery according to the seventh example;

[0121] Figure 7b is a schematic cross-sectional view through a solid state thin film battery of a first sample according to the seventh example;

[0122] Figure 7c is a schematic cross-sectional view through a sample solid state thin film battery made from a second sample according to the seventh example;

[0123] Figure 8a is a schematic diagram of a method of determining an optimum working distance for a remote plasma deposition system configured for deposition of a layered oxide material according to the eighth example;

[0124] Figure 8b shows a plurality of X-ray diffraction spectra collected as part of the method; Figure 8a the characterisation technique is X-ray diffraction, the characterisation feature is a characteristic X-ray diffraction peak relating to a layered oxide structure;

[0125] Figure 9a is a micrograph of a sample film formed according to the first example of the invention;

[0126] Figure 9b is a micrograph of a sample film formed according to the first example of the invention; Figure 9aX-ray diffraction spectrum obtained for the film shown in the middle;

[0127] Figure 10a An example of a method according to the ninth example of determining an optimal working pressure for a remote plasma deposition system configured for depositing a layered oxide material is schematically represented;

[0128] Figure 10b Two X-ray diffraction spectra collected as part of the described method are shown, where the characterisation technique is X-ray diffraction and the characterisation feature is a characteristic X-ray diffraction peak associated with a layered oxide structure; Figure 10a

[0129] An example of steps of a method according to the tenth example of determining crystallite size of a layered oxide material is shown; Figure 11a

[0130] A graph showing how crystallite size is determined for a working distance of 16 cm at different working pressures according to the tenth example is shown, showing crystallite size for a plurality of films deposited according to the first example; Figure 11b

[0131] A graph showing how crystallite size is determined for a working distance of 8.5 cm at different working pressures according to the tenth example is shown, showing crystallite size for a plurality of films deposited according to the first example; Figure 11c

[0132] A schematic representation of a method of depositing a material on a substrate according to an eleventh example of the application is shown; Figure 12

[0133] A schematic representation of an example of a method of manufacturing a component for an electronic device according to a twelfth example is shown; Figure 13

[0134] A schematic representation of an example of a method of manufacturing a component for an electronic device according to a thirteenth example of the application is shown; Figure 14

[0135] A schematic representation of an example of a method of manufacturing a light emitting diode (LED) according to a fourteenth example of the application is shown; Figure 15

[0136] A schematic representation of an example of a method of manufacturing a permanent magnet according to a fifteenth example of the application is shown; and Figure 16

[0137] A schematic representation of an example of a method of manufacturing an electronic device comprising an indium tin oxide (ITO) layer according to a sixteenth example of the application is shown. Figure 17 DETAILED DESCRIPTION

[0138] Figure 1a ​is a schematic side view of a plasma deposition process apparatus used in a method of depositing (crystalline) material onto a substrate according to a first example. The method is generally indicated by reference numeral 1001 and is schematically illustrated in Figure 1b includes generating 1002 a plasma remote from one or more targets, exposing 1003 the one or more plasma targets to the plasma such that target material sputters from the one or more targets, and exposing 1004 a first portion of the substrate to the sputtered material such that the sputtered material is deposited on the first portion of the substrate, thereby forming a crystalline material on the first portion of the substrate. The method of depositing (crystalline) material onto a substrate can be performed as part of a method of manufacturing a battery cathode.

[0139] The crystalline material in this example takes the form of ABO2. In this example, the ABO2 material takes a layered oxide structure. In this example, the ABO2 material is LiCoO2. However, the method of this example has been proven to be suitable for a wide range of ABO2 materials. In other examples, the ABO2 material structure includes at least one of the following compounds (described here using non-specific stoichiometry): LiCoO, LiCoAlO, LiNiCoAlO, LiMnO, LiNiMnO, LiNiMnCoO, LiNiO and LiNiCoO. These materials are potential candidate materials for manufacturing battery cathodes. The skilled person will appreciate that the stoichiometry can vary.

[0140] In this example, the ABO2 material is LiCoO2 and is deposited as a layer of approximately 1 micron thick. In other examples, the ABO2 material is deposited as a layer of approximately 5 microns thick. In yet further examples, the ABO2 material is deposited as a layer of approximately 10 microns thick.

[0141] With reference to Figure 1a , the plasma deposition process apparatus is generally indicated by reference numeral 100 and includes a plasma target assembly 102 comprising a target 104, a remote plasma generator 106, a series of electromagnets 108 for confining a plasma generated by the remote plasma generator 106, a target power supply 110, a remote plasma source power supply 112 and a housing 114. The remote plasma generator 106 includes two pairs of radio frequency (RF) antennae 116. The housing 114 includes a vacuum outlet 120 which is connected to a series of vacuum pumps located outside the chamber such that a chamber 122 defined by the housing 114 can be evacuated. The housing 114 is also provided with a gas inlet 124 which can be connected to a gas source (not shown) to introduce one or more gases into the chamber 122. In other examples, the gas inlet 124 can be positioned on the surface of the target assembly 102. From Figure 1a It can be seen that the plasma is generated remote from the target 104.

[0142] In this example, the target 104 comprises the material LiCoO2. Briefly, the chamber 122 is evacuated until a sufficiently low pressure is reached. Power provided by the power supply 112 is used to power the remote plasma generator 106 to generate a plasma. Power is applied to the target 104 such that the plasma interacts with the target 104, causing LiCoO2to sputter from the target 104 onto the substrate 128. In this example, the substrate 128 comprises a polymer sheet which is introduced into the housing 114 via the inlet 130 and is removed from the housing 114 via the outlet 132. A powered roller 134 is used to help move the substrate 128. The LiCoO2is deposited on the substrate 128 as a crystalline (non-amorphous) material.

[0143] The apparatus 100 also comprises a shutter 136 for limiting deposition of sputtered material onto the substrate 128, and an input 138 for cooling the roller. The shutter 136 allows a portion of the substrate 128 to be exposed to the sputtered material.

[0144] As mentioned above, the power roller 134 is used to help move the substrate 128 into and out of the plasma deposition apparatus 100. The power roller 134 is part of a roll-to-roll substrate processing apparatus (not shown) that includes at least a first storage roller upstream of the plasma deposition apparatus 100 and a second storage roller downstream of the plasma deposition apparatus 100. Roll-to-roll substrate processing apparatuses are a convenient way to handle, store, and move thin, flexible substrates, such as the polymer substrates used in the present example. Such roll-to-roll systems have many other advantages. They allow for high material throughput and allow for deposition of large cathode areas on one substrate, although a series of depositions are made on a first portion of the substrate, followed by a second portion of the substrate, and so on. Furthermore, such roll-to-roll processing allows for a large amount of deposition to occur without breaking the vacuum. This saves both time and energy compared to systems where the chamber needs to be returned from vacuum to atmospheric pressure in order to load a new substrate after deposition. In other examples, a sheet-to-sheet processing is used instead of roll-to-roll processing, where the substrate is provided with a support. Alternatively, the substrate can be provided in the form of discrete sheets that are handled and stored in a relatively flat sheet. The substrate can be planar in shape when material is deposited on it. This can be the case when the substrate is provided in the form of discrete sheets that are not transferred to or from a roller. The sheets can each be mounted on a carrier that has greater structural rigidity. This can allow for the use of thinner substrates than would be the case if the substrate film was held on a roller. The substrate can be a sacrificial substrate. The substrate can be removed prior to the material layer. Part or all of the substrate can be removed prior to integrating the crystalline layer or a portion thereof into an electronic product package, component, or other end product. For example, the crystalline material layer can be peeled off from the substrate. There can be other intermediate material layers between the base substrate and the crystalline material. The layer can be peeled off with the crystalline material or facilitate separation of the crystalline material from the base substrate. Laser-based peeling techniques can be used. The substrate can be removed by a process that utilizes laser ablation.

[0145] Similar techniques are described in the prior art. For example, KR20130029488 describes a method of manufacturing a battery pack including using a sacrificial substrate and laser radiation to harvest a battery pack layer. In other examples, another suitable processing scheme is used as long as it is capable of a sufficiently high production throughput.

[0146] The polymer substrate 128 is under tension as it moves through the system, for example, it is under at least 0.001 N of tension during at least part of the processing. The polymer is sufficiently strong that it does not deform under tensile stress as it is fed through a roll-to-roll machine. In this example, the polymer is polyethylene terephthalate (PET) and the substrate 128 has a thickness of 1 micron or less, in examples the thickness is 0.9 microns. The substrate 128 is pre-coated with a current collector layer, which is made of an inert metal. In this example, the inert metal used as the current collector layer is platinum. The yield strength of the PET film is sufficiently strong that the substrate does not yield or plastically deform under the stresses of the roll-to-roll processing equipment. The inert metal used in other examples can alternatively be gold, iridium, copper, aluminium or nickel.

[0147] It is beneficial to use such a thin polymer substrate because this facilitates the manufacture of batteries with higher energy density. In other examples, a non-polymeric material is used, provided that it can be manufactured in a sufficiently thin and flexible manner to allow high battery density and ease of post-deposition handling.

[0148] However, the plasma deposition process and subsequent manufacturing processes face technical challenges that arise from the use of such thin layers.

[0149] Before the substrate 128 is so pre-coated, it has a surface roughness that is carefully designed so as to be (a) large enough to mitigate the adverse effects caused by electrostatic forces (for example, to increase the force required to unroll the thin polymer film from the drum to which it is fixed) and (b) small enough that the roughness does not cause problems when material is deposited onto the substrate. In this example, the surface roughness is designed to be about 50 nm. It should be noted that the product of the thickness of the substrate (0.9 microns) and the surface roughness is 4.5 x 10 4 nm 2 so in this example is less than 10 5 nm 2 and less than 5 x 10 4 nm 2 It has been found that the roughness required to facilitate handling of the thin film increases as the thickness decreases. In general, it has been found that the roughness required to improve handling of thinner substrates (i.e. less than 10 microns, in particular less than 1 micron) increases as the thickness of the substrate decreases.

[0150] Figure 1c A typical thin film polymer is shown (not to scale) that is about 1 micron thick and has embedded particles that provide the roughness. The roughness of the surface features provided by the particles is at least 90 nm and can be higher. This is too coarse for the particular example envisaged (although it can be acceptable for other examples).

[0151] Figure 1dOne way in which the desired roughness can be achieved is shown (not to scale). Spherical particles of polystyrene are embedded in the substrate material such that at least 90% of those particles that contribute to the substrate roughness protrude no more than half their volume from the local substrate surface. The particles have a diameter of about 90 nm. Thus, the majority of the embedded particles that contribute to the substrate surface roughness have a median size of about 180% of the substrate surface roughness. In other examples, the embedded spherical particles are made of a different material, such as silicon oxide.

[0152] Figure 1e An alternative way in which the desired roughness can be achieved is shown (not to scale). Spherical embedded particles of polystyrene are present on the surface of the substrate material such that at least 90% of those particles that contribute to the substrate roughness protrude more than half their volume from the local substrate surface. Figure 1e The particles used in the example are smaller than Figure 1d The particles used in the example.

[0153] For example Figure 1d and 1e Those examples in which the embedded particles are present can deposit high quality thin films as crystalline material on thin substrates in a manufacturing environment. The advantages of having embedded particles are retained, but by carefully controlling the position and size distribution of such particles, potential disadvantages can be avoided or reduced. Figures 1f to 1h A cross-section of the substrate shown in Figures 1c to 1e is shown schematically after forming a layer of crystalline material on the surface of the substrate. Figures 1f to 1h The intermediate layer of metal current collector is omitted in Figure 1c and 1f The roughness of the substrate shown in Figure 1f results in problems. The dominant protrusions caused by some of the embedded particles 152 result in shading and competing crystal growth, which is shown schematically by the contrasting shading 154 in Figure 1f . This competing crystal growth, which is aligned in mutually conflicting directions, can result in discontinuities in the layer, which can affect the performance of the final product. Furthermore, there is a surprising and profound effect on the likelihood of the deposited layer of material delaminating from the substrate. This can be a result of poor contact between the deposited layer and the substrate below, in areas close to any embedded particles that protrude from the mid-plane of the surface (shown schematically by the voids 156 in Figure 1g and 1h It can be seen that such problems do not arise. The surface roughness of the material deposited on the substrate is about 50 nm.

[0154] The roughness of the substrate can be measured with a profilometer. This instrument has a fixed stylus. The surface being measured is translated under the stylus, and the deflection of the stylus measures the surface profile, from which various roughness parameters are calculated.

[0155] Roughness can also be measured using a“non-contact” method. A suitable machine to measure roughness is the“Omniscan MicroXAM 5000B 3d”, which uses optical phase shift interferometry to measure surface profile.

[0156] Roughness Ra can be calculated using the following equation:

[0157]

[0158] where y is the deviation from a mathematically perfect smooth surface for n data points.

[0159] Surface roughness Sa in the x- and y-directions for region A can be calculated using the following equation:

[0160]

[0161] where Z is the deviation from a mathematically perfect smooth surface.

[0162] In this example, the average surface roughness is measured by a non-contact method.

[0163] The remotely generated plasma is generated by the power supplied to the antenna 116 by the power source 112. There is therefore a measurable power associated with the power used to generate the plasma. The plasma is accelerated by the electric bias on the target 104 to the target, and therefore a current associated with this. There is therefore a power associated with the bias on the target 104. In this example, the ratio of the power used to generate the plasma to the power associated with the bias on the target is greater than 1 : 1, and optionally greater than 1.0:1.0. Note that in this example, the ratio is calculated assuming a power efficiency of the plasma generation source of 50%. The power associated with the bias on the target is at least 1 Wcm -2 .

[0164] In a further example, the ratio of the power used to generate the plasma to the power associated with the bias on the target is greater than 1 : 1, and no more than 7:2, optionally 7.0:2.0. In a still further example, the power associated with the bias on the target is greater than 1 : 1 and no more than 3:2, optionally 3.0:2.0. In some examples, the power efficiency of the plasma generation source is taken to be 80%. In some examples, the power associated with the bias on the target is 10 Wcm -2 . In a still further example, the power associated with the bias on the target is 800 Wcm -2 . In a still further example, the power associated with the bias on the target is 800 Wcm -2 . In other examples, the efficiency of the plasma generation source can be different, and the power ratio can also be different.

[0165] When the LiCoO2 film is deposited on the substrate, it forms a crystalline film of LiCoO2. The crystalline structure formed on the substrate is in the space group Fd3m. This structure is a layered oxide structure. This structure has many advantages over the lower energy structure of LiCoO2 with the space group Fd3m, such as having a higher available capacity and a higher rate of charge and discharge. The crystalline LiCoO2 in the space group Fd3m is generally preferred for solid state battery applications. The crystalline LiCoO2 in the space group Fd3m is generally preferred for solid state battery applications.

[0166] The temperature of the substrate 128 throughout the plasma deposition process does not exceed the degradation point of the polymeric substrate 128. In addition, the temperature of the substrate is low enough throughout the deposition process that the temperature regulated yield stress of the polymeric substrate remains high enough that the polymeric substrate does not deform under the stresses applied by the roll-to-roll processing machine.

[0167] The general shape of the confined plasma made by the remote plasma generator 106 is shown by the dashed line B in FIG. 1. A series of electromagnets 108 are used to confine the plasma into the desired shape / volume. Figure 1a

[0168] It should be noted that while in this first example the substrate 128 is fed into the chamber at the inlet 130 and exits the chamber at the outlet 132, alternative arrangements are possible. For example, a roll or other reservoir upstream of the baffle 136 can be inside the processing chamber 122. A roll or other reservoir downstream of the baffle 136 can be inside the processing chamber 122 or can be stored outside of the processing chamber 122.

[0169] In addition, the device 112 that powers the plasma source can be RF, (direct current) DC, or pulsed DC type.

[0170] In this first example, the target assembly 102 includes only one target 104. The target is made of LiCoO2. It should be understood that alternative and / or multiple target assemblies can be used, for example, including different regions of elemental lithium, different regions of elemental cobalt, different regions of lithium oxide, different regions of cobalt oxide, different regions of LiCo alloys, different regions of LiCoO2, or any combination thereof. In other examples, the ABO2 material can not be LiCoO2. In these examples, the one or more target assemblies contain different A regions, different B regions, different regions of compounds containing A and / or B, and / or different regions containing ABO2.

[0171] For the avoidance of doubt, the target 104 of the target assembly 103 is used solely as a material source and not as a cathode when power is applied to it from an RF, DC, or pulsed DC power source.

[0172] ​​In this example, the system operates at a working pressure of 0.0050 mBar. The system has a theoretical mean free path of approximately 10 cm. The theoretical mean free path is the average distance between ion collisions in the plasma. The working distance between the target 104 and the substrate 128 is approximately 8.5 cm. Thus, this working distance is approximately 85% of the system's theoretical mean free path.

[0173] In this example, the working pressure is above a lower limit below which crystalline material in the layered oxide structure does not form; but below an upper limit above which observable damage to the substrate occurs. The working distance is shorter than an upper limit above which crystalline material in the layered oxide structure does not form, and longer than a lower limit below which the energy of deposition causes observable damage to the substrate, or forms an undesirable oxide state.

[0174] In this example, the average crystallite size of the crystallites formed on the film is approximately 20 nm. In other examples, the average crystallite size of the crystallites formed on the film is approximately 50 nm.

[0175] In an alternative example, the system operates at a working pressure of 0.0020 mBar. The system has a theoretical mean free path of approximately 12 cm. The working distance between the target 104 and the substrate 128 is approximately 9 cm. Thus, this working distance is approximately 75% of the system's theoretical mean free path.

[0176] In an alternative example, the system operates at a working pressure of 0.0065 mBar. The system has a theoretical mean free path of approximately 15 cm. The working distance between the target 104 and the substrate 128 is approximately 7.5 cm. Thus, this working distance is approximately 50% of the system's theoretical mean free path.

[0177] The second example method uses the apparatus shown in FIG. 2. The main differences between the apparatus of FIG. 1 and the apparatus of FIG. 2 will now be described. Figure 2a Figure 1a Figure 2a The main differences between the apparatus of FIG. 1 and the apparatus of FIG. 2 will now be described. Figure 2a Instead of the flexible substrate 128 presented in the first example, a non-flexible planar glass substrate 228 is used, as shown. Also, there are no baffles in this example. The glass substrate has a thickness on the order of millimeters. A single target 204 is used in this example. A thermal indicating label is affixed to the side of the glass slide opposite the side on which the cathode material is deposited. The thermal indicating label is configured to indicate whether the substrate 228 experienced a temperature of 270 °C or greater during the plasma deposition process. After deposition, the label indicates that the substrate did not experience a temperature of 270 °C or greater during the deposition process. The overall shape of the plasma is represented by the area enclosed by the dashed line B' in FIG. 2. Figure 2a

[0178] Table 1 shows the performance of the resulting example battery cathode produced according to the second example:

[0179] ​​​

[0180] Table 1 - Performance of LiCoO2cathode films in relation to deposition parameters

[0181] In the above Table 1, the elemental film composition was determined by X-ray photoelectron spectroscopy using a Thermo Fisher K-alpha spectrometer with a MAGCIS ion gun. The quoted composition was taken from a depth profile measured with the film at about 10 levels. The plasma source power is the electrical power supplied to generate the plasma. The sputtering power is the electrical power applied to the target 204. The process pressure is the pressure in the chamber. Film thickness and roughness measurements were made post-deposition using an Omniscan MicroXAM 5000b 3d optical profiler. Film thickness was measured post-deposition because the step height at the masked edge and roughness measurements were made from a sample area of approximately 400 microns x 500 microns.

[0182] Figure 2b X-ray diffraction (XRD) spectra of the battery cathode of sample 1 are shown. The structure of the thin films was characterized by X-ray diffraction using a diffractometer (Rigaku-Smartlab) with Cu K alpha radiation filtered with nickel The diffraction pattern was taken at room temperature in the range 10° < 2 theta < 80° using a fixed incidence angle of < 5°. Data was collected using a step scan with a resolution of 0.04° / step, a count time of 0.5 seconds / step. The peak at approximately 37° is related to the (101) plane of the crystal oriented substantially parallel to the substrate surface. The peak at approximately 66° is related to the crystal oriented such that the (110) plane is parallel to the substrate. The peak at approximately 55° is related to the glass substrate and should be ignored in order to determine the crystal structure of the LiCoO2.

[0183] The absence of additional reflections related to the Fd3m space group is an initial indication that the deposited LiCoO2is in the space group.

[0184] The peak related to the (003) plane is also apparently absent. This means that there are very few crystals oriented with the (003) plane parallel to the substrate surface. Fewer crystals oriented in this way is beneficial. A detailed explanation is beyond the scope of this application, but in simple terms, when a higher proportion of crystals are aligned such that the (101) and (110) planes are parallel to the substrate, the available capacity of the cathode increases, as opposed to being aligned such that the (003) plane is parallel to the substrate, because the apparent resistance to ion migration is lower. The crystals have formed such that the longitudinal axis of the crystal is perpendicular to the substrate. In other words, the crystals have formed in an epitaxial manner.

[0185] The applicants have found that if the ratio of the power used to generate the plasma to the power associated with the bias to the target is greater than 1 :1 then typically crystalline material is deposited. In sample 1 the ratio was 1800:500 (3.6:1) and in sample 2 the ratio was 1800:800 (9:4). Note that in this example the ratio is calculated assuming a power efficiency of the plasma generation source of 50%.

[0186] In a comparative example the experiment was repeated with a plasma source power of 1 kW and a power associated with the bias to the target of 1 kW. The material deposited was substantially amorphous. The performance of the film of the comparative example as a cathode was investigated by depositing an electrolyte (in this case LiPON) and an anode metal on top of the cathode layer, thereby fabricating a solid state battery. The charge and discharge characteristics of the battery were investigated and it was found that the battery had poor charge and discharge characteristics with a cathode specific capacity of around 10 mAh / g. When similar batteries were fabricated using crystalline LiCoO2(e.g. the batteries formed in sample 1 and sample 2) the charge and discharge characteristics were much better with a typical cathode specific capacity of around 120 mAh / g.

[0187] Figure 2c A Raman spectrum of the battery cathode of sample 1 is shown. The adhesive environment of the film was characterised by Raman spectroscopy. Raman spectra were collected using a JY Horiba LabRAM ARAMIS imaging confocal Raman microscope using a 532 nm excitation. Note that the strong sharp peak at 600 cm -1 may be considered anomalous. The strong feature peak observed at 487 cm -1 is well known in the art and is associated with the space group crystal structure of LiCoO2.

[0188] Figure 2d An XRD spectrum of the cathode of sample 2 is shown (collected in the same way as sample 1). The spectrum shown is similar to the spectrum shown in Figure 2b However, in Figure 2d the relative intensity of the peak at approximately 66° is much stronger than the peak at 37°. This indicates that for sample 2 there are a higher number of crystals with their (110) planes parallel to the substrate than there are crystals with their (101) planes parallel to the substrate. This is beneficial because it means that the ion channels of the thin film are oriented perpendicular to the substrate making it easier for ions to intercalate and de-intercalate from interstitial sites within the cathode crystal structure. This increases the available capacity and charge rate of the cathode. Figure 2e is a Raman spectrum of the cathode of sample 2; the same comments apply to Figure 2c as apply to Figure 2e .

[0189] Figures 3a to 3c ​An alternative example of an apparatus used in another example of a method for fabricating a layer of crystalline material on a surface using plasma sputtering according to the third example is shown. The apparatus and fabrication method employed are similar to that described with reference to the first example. Only the significant differences will now be described. Like parts are marked with reference numerals that share the same last two digits. For example, Figure 3a The rotating drum 334 in Figure 1a is the same as the rotating drum 134 in Figure 3a The apparatus of Figure 3 comprises a rotating drum 334 on which a polymeric substrate 328 is supported within an area defined by a process chamber 322 (the walls of the chamber are omitted for clarity). The target assembly 302 comprises a plurality of targets. There is provided a first target 304 composed of elemental lithium and a plurality of targets 303 composed of elemental cobalt (now referred to as second targets). The targets are all located at a working distance of about 10 cm from the substrate 328 (the working distance being the shortest separation between them). The surface of each target 303, 304 facing the drum 334 is flat (and planar). The radius of the drum 334 is significantly greater than the working distance (the size of the drum 334 shown in the figure is relatively small compared to the actual size for ease of illustration). The targets 303, 304 are arranged circumferentially around the circumference of the drum 334. The apparatus also comprises a baffle 336 for limiting the deposition of sputtered material on the substrate 328.

[0190] A plasma of argon ions and electrons is generated by two spaced-apart powered antennae 316. The plasma is confined and focused by a magnetic field controlled by two pairs of electromagnets 308, each pair being positioned close to one of the antennae 316 and the electric field generated by the system. The overall shape of the plasma (90% of the highest concentration of which is in Figure 3c illustrated in highly schematic fashion by the plasma cloud B" in The length and width of the plasma are controlled in part by the length of the antennae 316. The two pairs of antennae 316 are spaced apart by a distance comparable to the length of the plasma. The length and width of the plasma are in the same general direction as the length and width of the substrate, respectively.

[0191]

[0191] The plasma source is spaced apart from the targets and can therefore be considered to be a remotely generated plasma. The theoretical mean free path of the system (i.e. the average distance between collisions of ions in the plasma) is about 12 cm, which means that most particles travel from the target to the substrate without colliding with any argon ions in the plasma.

[0192] Figure 3ais a partial schematic cross-sectional view showing a portion of a substrate travelling on the drum 334 and also schematically showing the trajectories of particles travelling from the targets 303, 304 to the substrate. Thus, there is a first plume corresponding to the trajectories of particles from the first target 304 to the surface of the substrate 328 and a second plume corresponding to the trajectories of particles from the second target 303 to the surface of the substrate 328. The first plume is shown as a dotted area, each second plume is shown as a solid grey area. From Figure 3a It can be seen that the first and second plumes converge in a region close to the substrate. From Figure 3a It can also be seen from Figure 3a that the first target 304 faces the substrate in a first direction (in this example defined by an imaginary line extending from the centre of the surface of the target 304) and that the left-hand adjacent second target 303 faces the substrate in a second direction (in this example defined by an imaginary line extending from the centre of the surface of the target 303) as shown in Figure 1a The first and second directions converge towards the substrate and intersect just beyond the substrate (this position is about 3 cm beyond the substrate). Oxygen is supplied at a controlled rate through the inlet 325 into the processing chamber 322. The targets are stationary as the substrate moves with rotation of the drum. In other examples, an inert sputter gas is introduced through a gas inlet (not shown here but substantially the same as the structure shown in

[0193] If there are different lithium oxide and cobalt oxide regions in the targets 304, 303, the amount of oxygen introduced into the chamber can be reduced in some other examples and in some examples the oxygen content in such targets can be high enough that no additional oxygen needs to be introduced into the chamber 322 at all.

[0194] Figure 3b is a view from the drum towards the targets. Figure 3c is a cross-sectional view including a section of the first target 304, the second target 303 and the substrate 328 on the drum 334.

[0195] It can be seen in Figure 3c (cross-sectional view) that the first target 304 is angled relative to each second target 303.

[0196] In performing this method, the plasma generated is used to sputter material from the first target and from the second target onto the substrate.

[0197] As Figure 3dAs shown, the sputtering yield of the elemental lithium material is lower than cobalt, measured in the number of atoms produced per ion received at the surface at a given energy (less than half at 10 keV). Therefore, the magnitude of the (negative) potential applied to the first target is greater than the potential applied to the second target. The first target also has a slightly greater surface area exposed to the plasma than the total area of the second target. Therefore, the number of ionised Li atoms reaching the substrate per unit is substantially the same as the number of ionised Co atoms reaching the substrate per unit. There are also ionised oxygen atoms and electrons from the plasma. The high energy particles of the remote plasma allow the formation in situ at the substrate surface of a crystalline LiCoO2 material having a hexagonal crystal structure.

[0198] The number of high energy particles from the plasma received at the first target 304 (over the entire surface area of the target) is greater than the number of particles received at the second target 303 (the sum over the entire surface area of the two second targets).

[0199] Figure 3e A schematic cross-sectional view showing another example of an apparatus according to a fourth example is shown, similar to the apparatus shown in Figures 3a to 3c but where the targets are moved and arranged in pairs circumferentially around a drum 334. Each pair of targets (i.e. each assembly 302) is arranged to be tilted to face a position very close to a substrate on the drum. Each pair 302 comprises a first target 304 of elemental lithium and a second target 303 of elemental cobalt. The targets are both at a working distance of about 15 centimetres from the substrate, the working distance being the shortest separation between them. The theoretical mean free path of the system (i.e. the average distance between ion collisions in the plasma) is about 20 cm. For each pair of targets (302), in use, there is a first particle plume from the first target (304) and a second particle plume from the second target (303) which converge at a region close to the substrate. The centre of rotation of the main drum 334 is also the centre of rotation of the targets. The targets move at an angular velocity around the centre of rotation which is slower than the drum. As the targets move out of the plasma on a rotational basis, they can be replaced, allowing material to be deposited continuously on a moving substrate.

[0200] An example of a battery cathode manufactured according to the second example will now be described with reference to Figure 4a , 4b and 5a. The substrate 428, 528 comprises a current collector layer 429, 529, in this case a platinum layer, on which a LiCoO2 layer 442, 542 is deposited. In other examples, another inert metal is used as the current collector layer, for example gold, iridium, copper, aluminium or nickel. In yet further examples, the current collector layer can be carbon-based. In some examples, the current collector layer is surface-modified, and in some examples, the current collector layer comprises rod-like structures.

[0201] As Figure 4a (Figure 1a - cross-sectional view of a first sample deposited film) andFigure 4b The LiCoO2 film layers 442, 542 of both samples are polycrystalline in nature, as shown in the scanning electron microscope (SEM) images of FIGS. 44 and 45, respectively. Figure 4a 、 4b The battery cathode of FIG. 5a can also be fabricated according to the methods of the third or fourth examples.

[0202] A method of fabricating a cathode half-cell according to the fifth example will now be described with reference to Figure 5a the first sample, Figure 5b the second sample, and Figure 5c The method is generally described by reference number 3001, and includes depositing 3002 a battery cathode material 542 onto a substrate (which in this example includes a current collector layer 529), and depositing 3003 a battery electrolyte material 544 onto the battery cathode material 542. In this example, the material deposited for the electrolyte 544 is lithium phosphorous oxynitride (LiPON). In other examples, the material deposited is another suitable electrolyte material. In some samples of the fifth example of the invention (e.g. the second sample), the half-cell can include an electrode material 544, while in other samples of the fifth example (e.g. the first sample), the half-cell can not include an electrode material 544.

[0203] In this example, LiPON is deposited using a remotely generated plasma in substantially the same manner as the ABO2 materials in the first, second, third, or fourth examples. However, in this example, the target material used is Li3PO4, and the deposition occurs in an active nitrogen atmosphere. In other examples, the target assembly can include multiple targets with different regions of lithium and / or phosphorous containing compounds, elemental lithium, or lithium oxide. In other examples, the deposition additionally occurs in an active oxygen atmosphere.

[0204] A method of fabricating a solid state battery cell according to the sixth example will now be described with reference to Figure 6 The method is generally described by reference number 5001, and includes fabricating 5002 a cathode half-cell according to the fifth example (e.g. as described above with reference to Figure 5b and 5c The cathode half-cell is contacted 5003 with an anode. In this example, the anode is deposited by a convenient method, including remote plasma sputtering, magnetron sputtering, CVD, etc. In other examples, the anode is deposited by thermal evaporation, e-beam evaporation, pulsed laser deposition, or simple DC sputtering.

[0205] A method of fabricating a solid state battery cell according to the sixth example will now be described with reference to Figure 7aAn example of a method of manufacturing a solid state battery according to the seventh example will now be described. The method is generally indicated by reference numeral 6001 and comprises manufacturing 6002 a plurality of cathode half-cells of a solid state thin film battery, manufacturing 6003 a plurality of anode half-cells of a solid state thin film battery, and bringing the cathode and anode half-cells into contact 6004 with each other, thereby forming at least one battery. A battery so manufactured according to a first sample of the seventh example of the application is shown schematically in Figure 7b . Referring to Figure 7b , 628 and 628' are substrate materials, 629 and 629' are current collectors, 642 is a cathode material, in this case LiCoO2, and 644 is LiPON which acts as both electrolyte and anode.

[0206] Alternatively, in other examples, the current collector material acts as the anode material. Alternatively, in a second sample of the seventh example of the application, a further anode material can be deposited. This is shown schematically in Figure 7c . Referring to Figure 7c , 628 and 628' are substrate materials, 629 and 629' are current collectors, 642 is a cathode material, in this case LiCoO2, 644 is LiPON which acts as electrolyte, and 646 is a suitable anode material.

[0207] An example of a method of determining an optimum working distance for a remote plasma deposition system configured for depositing a layered oxide material according to an eighth example will now be described with reference to Figure 8a . The method is generally described by the numeral 7001 and comprises:

[0208] selecting 7002 a range of working distances, wherein the working distances within said range are + / - 50% of the theoretical mean free path of the system,

[0209] for a plurality of test samples, for each respective sample, performing 7003 the method of depositing a material according to the first example at different working distances within the selected range,

[0210] performing 7004 a characterisation technique which is capable of determining a characterising feature of the layered oxide structure on each test sample after deposition has occurred,

[0211] identifying 7005 the samples in which the characterising feature is present;

[0212] from those samples, selecting 7006 the sample in which the (normalised) intensity of the feature peak is highest, and subsequently selecting 7007 the working distance reached by the system during deposition of said test sample to.

[0213] In this eighth example, the characterisation technique used is X-ray diffraction and the characterising feature is a diffraction peak or series of diffraction peaks. Figure 8b ​A plurality of X-ray diffraction patterns of a film deposited at different working distances are shown. From top diffraction pattern to bottom diffraction pattern, the working distances are 5 cm (731), 8 cm (733), 12 cm (735), and 15 cm (737). As can be seen from the figure, the working distance of 8 cm shows the highest intensity peak 733 at 19 degrees 2theta (this is one of the peak positions 739 required for hexagonal LiCoO2, this particular peak is not present in the cubic or spinel structure of LiCoO2). Therefore, in this example, 8 cm is chosen as the working distance. In other examples, different characterization techniques than X-ray diffraction can be used. The intensity of the diffraction pattern 731 measured at a working distance of 5 cm has a lower intensity at 19 degrees 2theta than the intensity of the diffraction pattern 733 at a working distance of 8 cm. The diffraction patterns collected for working distances of 12 cm 735 and 15 cm 737 do not show the characteristic peak of hexagonal LiCoO2 at 19 degrees 2theta at all.

[0214] In some examples, the test sample of the method is replaced by an average of a plurality of test samples, including a plurality of test samples where the method of the first example has been performed a plurality of times at the same working distance and the average is taken. In some examples, the method can be performed a plurality of times so that a range of optimal working distances for the system can be found.

[0215] Figure 9a A sample formed according to the first example during execution of the method of the eighth example is shown, and a damaged substrate surface (with undesired oxide) formed due to the deposition when the working distance is too short is shown. In this example, the working distance is 5 cm and the material deposited is LiCoO2. As can be seen from the figure, no microcrystals are formed over the entire substrate surface, and deformation of the substrate can be seen. Furthermore, at this working distance, undesired cobalt oxide phase Co(II)O regions can be seen to be formed on the substrate. This is confirmed by the spectrum shown in Figure 9b which shows peaks associated with the Co(II)O phase (identified at two values of 2theta 843) detected in the diffraction pattern 831, which was obtained for the sample with a working distance of 5 cm, in addition to the hexagonal LCO peaks (identified at 5 values of 2theta 839). A structure refinement model 831' containing the hexagonal LiCoO2 and Co(II)O phases was obtained from the collected diffraction pattern 831. The difference between the diffraction pattern 831 and the refinement model 831' is shown by the difference line 841. Therefore, in the method of the eighth example, a too short working distance cannot be chosen as the optimal working distance.

[0216] Reference will now be made to Figure 10aAn example of a method of determining an optimal range of operating pressures for a remote plasma deposition system configured for depositing layered oxide material according to a ninth example is described. The method is generally described by numeral 8001, wherein the method comprises:

[0217] selecting 8002 an initial operating pressure range from 0.00065 mBar to 0.01 mBar (also 0.001 to 0.007 mBar can be selected),

[0218] for a plurality of test samples, for each respective sample, performing 8003 the method of depositing a material according to the first example at different operating pressures within the selected range,

[0219] performing 7004 a characterisation technique capable of determining a characterisation feature of the layered oxide structure on each test sample after deposition has occurred,

[0220] selecting 8005 the test sample deposited at the lowest operating pressure from the group of test samples exhibiting the characterisation feature of the layered oxide material and setting 8006 this operating pressure as the lower limit of the range,

[0221] selecting 8007 the test sample deposited at the highest operating pressure from the group of test samples not exhibiting observable signs of substrate damage and setting 8008 this operating pressure as the upper limit of the range.

[0222] In this ninth example, the characterisation technique used is X-ray diffraction and the characterisation feature is a feature comprising a characterisation X-ray diffraction peak of the layered oxide material. Figure 10b An example X-ray spectrum is shown, showing how this feature is not present below a certain operating pressure. In this example, the presence of the peak at 19 degrees 2theta in the pattern 947 of the sample deposited at 0.0046 mBar resulted in the formation of a hexagonal phase, whereas the pattern 945 of the sample deposited at 0.0012 mBar did not result in the formation of a hexagonal phase, as shown by the absence of the peak. In other examples, a characterisation technique other than X-ray diffraction can be used.

[0223] In a further example, the test samples of the method are replaced with an average of a plurality of test samples, comprising a plurality of test samples in which the method of the first example has been performed a plurality of times at the same operating pressure and an average taken.

[0224] In some examples, the method further comprises selecting an optimal operating pressure of the system within the desired range. In this example, the optimal operating pressure is the operating pressure within the range that results in the highest deposition rate.

[0225] Reference will now be made to Figure 11aThis describes an example of a method for determining the crystallite size for depositing layered oxide materials, according to the tenth example. The method is generally described by numeral 9001, wherein the method includes:

[0226] Select the initial range of the 9002 working pressure, from 0.00065 mBar to 0.01 mBar.

[0227] For multiple test samples, and for each corresponding sample, the method for depositing materials according to the first example is performed at different operating pressures within a selected range.

[0228] The 9004 characterization technique was performed, which is capable of determining the crystallite size of each film for each test sample after deposition has occurred.

[0229] For example, the selected working pressure range can be from 0.001 to 0.007 mBar.

[0230] Figure 11b This illustrates the range of crystallite sizes formed by multiple films deposited according to the first example at different working pressures between 0.001 mBar and 0.0065 mBar, for a working distance of 16 cm after performing the method of the tenth example within a given working pressure range. Figure 11c Compared to a relatively wide curve.

[0231] Figure 11c This illustrates the range of crystallite sizes formed by multiple films deposited according to the first example at different working pressures between 0.001 mBar and 0.0065 mBar, for a working distance of 8.5 cm after performing the tenth example method within a given working pressure range. Figure 11b Compared to a relatively narrow curve.

[0232] A narrow distribution of crystallite size is beneficial because it makes the crystallite size of films deposited on an industrial scale both predictable and reproducible.

[0233] Now refer to Figure 12 This describes an example of a method for depositing material on a substrate according to the eleventh example. The method is generally described by numeral 1101 and includes:

[0234] 1102 plasma is generated by moving away from a suitable plasma target for plasma sputtering.

[0235] One or more plasma targets are exposed to plasma, thereby generating sputtered material from one or more targets.

[0236] 1104 sputtered material is deposited on the first part of the substrate.

[0237] The method of depositing material on a substrate as described in the eleventh example includes all the features of the deposition of the first example, although in this example the target material can be any material. In this example, the target material is crystalline, however in other examples the deposited material can take a semi-crystalline form, or be amorphous.

[0238] A twelfth example is also presented, which relates to a method of manufacturing a component for an electronic device comprising a substrate, which will now be described with reference to Figure 13 which is generally described by the numeral 1201 and comprises depositing 1202 material onto a substrate using a method as described in the eleventh example. The method of the eleventh example in this example is performed multiple times 1203 to deposit multiple layers. In this example, at least some of the multiple layers can be semiconductor layers. In this example, the method is thus a method of manufacturing a semiconductor device, or a part thereof. In this example, adjacent layers are deposited using different parameters and / or target materials for depositing each layer, in order to produce an electronic device. In other examples, multiple layers of the multiple layers of material are deposited with substantially the same target material and parameters.

[0239] In this example, the substrate comprises one intermediate layer, which can optionally act as a current collecting layer. In other examples, there are more intermediate layers, which help with adhesion during the deposition steps. In some other examples, there are no intermediate layers. The deposition of the intermediate layer on the substrate is performed according to the method described in the eleventh example. In other examples, the deposition of the intermediate layer on the substrate is performed by another suitable deposition technique, such as sputtering, thermal evaporation, e-beam evaporation, pulsed laser deposition or other thin film deposition techniques.

[0240] In this example, the method comprises depositing a first semiconductor material layer. In this example, the first semiconductor layer is deposited on the intermediate material layer. In other examples, the first semiconductor layer is deposited directly on the substrate. In this example, the first semiconductor layer comprises silicon. In other examples, the first semiconductor layer comprises aluminium, and in some other examples, comprises gallium nitride. In examples where the semiconductor material layer is gallium nitride, the deposition occurs under a reactive nitrogen atmosphere. In this example, the first semiconductor material layer is n-type doped. In this example, this is achieved by sputtering a target comprising a phosphorous containing compound. In other examples, this is achieved by using a different dopant such as arsenic, antimony, bismuth or lithium. In some further examples, the semiconductor material layer is p-type doped, with a dopant such as boron, aluminium, gallium or indium. In further examples, the semiconductor material layer is not doped, and is an intrinsic semiconductor. In some of these examples, the dopant material is not introduced as a sputterable target, but is introduced as a gas after deposition, so that the dopant diffuses into the surface of the semiconductor layer.

[0241] In this example, the method includes depositing a second semiconductor material layer onto the first semiconductor material layer. In other examples, the second semiconductor material layer is deposited directly on the substrate or an intermediate layer, if present. In this example, the second semiconductor material layer is an intrinsic semiconductor. In this example, the second semiconductor material layer is gallium nitride. In further examples, the second semiconductor material layer is n-type doped with a dopant such as phosphorus, arsenic, antimony, bismuth, or lithium. In some further examples, the second semiconductor material layer is p-type doped with a dopant such as boron, aluminum, gallium, or indium. In some of these examples, the dopant material is not introduced as a sputterable target, but is introduced as a gas after deposition, so that the dopant diffuses into the surface of the semiconductor layer.

[0242] In this example, the method includes depositing a third semiconductor material layer. In this example, the third semiconductor layer is deposited on the second semiconductor material layer. In other examples, the third semiconductor layer is deposited directly on the first semiconductor layer, the second semiconductor layer, an intermediate layer, or the substrate. In this example, the third semiconductor layer includes silicon. In other examples, the third semiconductor layer includes aluminum, and in some other examples, gallium nitride. In some examples where the semiconductor material layer is gallium nitride, the deposition occurs under a reactive nitrogen atmosphere. In this example, the third semiconductor material layer is doped p-type. In this example, this is achieved by sputtering a target that includes a boron-containing compound. In other examples, this is achieved by using a different dopant such as aluminum, gallium, or indium. In some further examples, the third semiconductor material layer is n-type doped with a dopant such as phosphorus, arsenic, antimony, bismuth, or lithium. In further examples, the third semiconductor material layer is not doped, and is an intrinsic semiconductor. In some of these examples, the dopant material is not introduced as a sputterable target, but is introduced as a gas after deposition, so that the dopant diffuses into the surface of the semiconductor layer.

[0243] Accordingly, the method of this example can be used to form a p-n or p-i-n junction.

[0244] In this example, no further dopants are introduced into some of the semiconductor layers described thus far. In some examples, germanium is introduced as a dopant into the first, second, and / or third layers. The germanium changes the bandgap of the electronic device, and improves the mechanical properties of each semiconductor material layer. In some examples, nitrogen is introduced as a dopant in the first, second, and / or third material layers. The nitrogen is used to improve the mechanical properties of the formed semiconductor layers.

[0245] A thirteenth example is also presented, which relates to a method of manufacturing a yttrium aluminum garnet (YAG) crystalline layer, which will now be described with reference to Figure 14which is described. The method is generally described by numeral 1301 and comprises using a method as described in the eleventh example 1302, wherein the YAG is doped 1303 with at least one f-block transition metal.

[0246] In this example, the dopant material is a lanthanide.

[0247] In this example, the dopant material comprises neodymium. In other examples, the dopant material comprises chromium or cerium in addition to neodymium. In this example, the crystalline layer of the material contains 1.0 mole percent of neodymium. In some examples, the material further contains 0.5 mole percent of cerium.

[0248] In yet another example, the dopant material contains erbium. In this example, the dopant material is provided as a target and sputtered as described in the eleventh example. In this further example, the crystalline layer of the material contains 40 mole percent of erbium. In one example, the crystalline layer of the material contains 55% of erbium.

[0249] In yet another example, the dopant material contains ytterbium. In one of these examples, the crystalline layer of the material contains 15 mole percent of ytterbium.

[0250] In still further examples, the dopant material contains thulium. In further examples, the dopant material contains dysprosium. In further examples, the dopant material contains samarium. In further examples, the dopant material contains terbium.

[0251] In still further examples, the dopant material contains cerium. In some examples in which the dopant material contains cerium, the dopant material further contains gadolinium.

[0252] In some examples, instead of providing the dopant material as a distinct region of one or more targets, the dopant material is introduced at least partially after deposition of the crystalline material layer by providing the dopant material as a gas, allowing it to diffuse into the crystalline material layer.

[0253] According to a fourteenth example, a method of manufacturing a light emitting diode is presented, which will now be described with reference to Figure 15 which is described. The method is generally described by numeral 1401 and comprises performing a method according to the twelfth example 1402 and, after or in which, performing a method according to the thirteenth example 1403, in case the dopant used during the method of the thirteenth example contains cerium 1404. In this example, the cerium doped YAG layer is used as a scintillator in an LED.

[0254] The methods according to the twelfth and thirteenth examples can be performed within the same processing chamber.

[0255] According to a fifteenth example, a method of manufacturing a permanent magnet is presented, which will now be described with reference toFigure 16 This is described. The method is generally described by the number 1501 and comprises performing the method 1502 according to the eleventh example, wherein the different regions of the provided target or targets contain neodymium, iron, boron and dysprosium 1503 and the method comprises processing the film 1504 such that the layer of material becomes a permanent magnet.

[0256] In this example, the last layer of material contains 6.0 mole percent of dysprosium. In further examples, the mole percent of dysprosium is less than 6.0.

[0257] The high target utilization provided by the current method is beneficial when constructing electronic devices with rare elements such as dysprosium. Dysprosium has a limited abundance on earth, so a deposition system with a high target utilization can reduce material waste.

[0258] According to a sixteenth example, a method of manufacturing a layer of indium tin oxide (ITO) is presented, which will now be described with reference to Figure 17 This is described. The method is generally described by the number 1601 and comprises performing the method 1602 according to the eleventh example, wherein the provided target contains indium and tin 1603. The ITO layer is deposited in such a way that it forms a layer of transparent crystalline material directly on the deposition 1604 on the substrate. In other examples, a composite target is used, which contains indium and tin. In still further examples, the composite target contains oxides of indium and tin. The number of targets used can thus be different in other examples and a single target can be used.

[0259] In still further examples, the target can contain an oxide of indium or an oxide of tin. In further examples, the deposition process comprises providing oxygen such that the sputtered material from the target reacts with the oxygen to form indium tin oxide on the substrate.

[0260] According to a seventeenth example, which is not shown separately, a method of manufacturing a photovoltaic cell is presented. In this example, the method further comprises depositing ITO as described in the fifteenth example. In further examples, no ITO layer is deposited. In this example, the method further comprises depositing a layer of perovskite material between an n-type doped layer of semiconductor material and a p-type doped layer of semiconductor material. In this case, the layer of perovskite material is deposited as described by the method of the eleventh example. In further examples, it is deposited by another suitable means, such as physical vapor deposition or a wet chemical technique. In further examples, no layer of perovskite material is deposited.

[0261] In an alternative example, the method includes depositing a layer of copper indium gallium selenide according to the eleventh example. Copper, indium, gallium and selenide are provided as different regions of one or more targets. In this example, copper is provided as an elemental target and indium, gallium and selenide are provided as an oxide target. Other combinations of oxide, elemental, compound or composite targets are used in other examples. The number of targets used can therefore be different in other examples and a single target can be used.

[0262] In some examples, the method includes depositing a layer of cadmium sulfide according to the eleventh example. In this example, cadmium and sulfide are provided as different regions of a target in the form of an oxide. Other combinations of oxide, elemental, compound or composite targets are used in other examples. The number of targets used can therefore be different in other examples and a single target can be used.

[0263] In some examples, the method includes depositing a layer of cadmium telluride according to the eleventh example. In this example, cadmium and telluride are provided as different regions of an elemental target. In other examples, cadmium and tellurium are provided as different regions of one or more targets in the form of an element, an oxide, a composite or any combination thereof. The number of targets used can therefore be different in other examples and a single target can be used.

[0264] While the foregoing description has been described and illustrated with respect to particular examples, those skilled in the art will appreciate that numerous variations in the details of the present application can be made without departing from the true spirit and scope of the application. Only certain possible variations are described and illustrated, only as examples.

[0265] In the foregoing description, reference has been made to integers or elements having known, obvious or foreseeable equivalents. Such equivalents are incorporated herein as if separately set forth. The true scope of the present examples is determined by the appended claims, in conjunction with the description set forth herewith, and it is intended that the appended claims be construed to include any such equivalents. It will also be understood that the overall structure of the application or features described as preferred, advantageous, convenient or the like are optional in nature, and do not limit the scope of the independent claims. Furthermore, it should be understood that such optional integers or features, while potentially beneficial in some embodiments of the application, can not be desirable and can not be present in other embodiments.

Claims

1. A method of depositing a material on a substrate, the method comprising: generating a plasma away from a plurality of sputtering targets adapted for plasma sputtering, wherein at least a different region of the plurality of targets comprises an alkali metal, an alkaline earth metal, an alkali metal containing compound, an alkaline earth metal containing compound, or a combination thereof; confining the plasma to the plurality of targets; generating a sputtered material from the plurality of targets using the confined plasma; and depositing the sputtered material on the substrate, the working distance between the targets and substrate being in the range of + / - 50% of the theoretical mean free path of the system, moving the substrate on a drum, wherein the drum has a center of rotation and the plurality of targets move around the center of rotation at an angular velocity slower than the drum, wherein the plurality of targets comprises a first target and a second target, the first target being angled relative to the second target.

2. The method of claim 1, wherein, The working distance is shorter than the mean free path of the system.

3. The method of claim 1, wherein, The alkali metal containing compound or the alkaline earth metal containing compound forms a crystalline material in situ upon material deposition.

4. The method of claim 3, wherein, The alkali metal containing compound or the alkaline earth metal containing compound is in the form of a layered oxide material.

5. The method according to any of the preceding claims, wherein, The working distance is greater than a lower limit defined by a working distance at which the deposition energy would cause damage to the substrate or form an unfavorable oxide state of constituent elements of the alkali metal containing compound or the alkaline earth metal containing compound.

6. The method of any one of claims 1 to 4, wherein, The working distance is greater than 5 cm.

7. The method of claim 4, wherein, The working distance is higher than a lower limit defined by a working distance at which a layered oxide structure would not form.

8. The method of any one of claims 1 to 4, wherein, The working distance is between 8 cm and 9 cm.

9. The method of any one of claims 1 to 4, wherein, The process occurs within a deposition chamber, and a working pressure is defined as the chamber pressure prior to initiating a remote plasma, the working pressure being at a substantially constant value throughout the deposition process, the value being between 0.00065 mBar and le-2 mBar.

10. The method of claim 9, wherein, The sputtering is caused by ion bombardment of a sputtering gas, and wherein a flow rate of the sputtering gas into the chamber is at a substantially constant value throughout the deposition process, the value being between 5 and 100 seem.

11. The method of claim 9, wherein, The working pressure is lower than an upper limit defined by a working pressure at which damage or softening to the substrate occurs.

12. The method of claim 9, wherein, The working pressure is between 0.0010 mBar and 0.0065 mBar.

13. The method of claim 9, wherein, The working pressure is higher than a lower limit defined by a working pressure at which a layered oxide structure would not form.

14. The method of claim 9, wherein, The working pressure is higher than 4.5e-3 mBar.

15. The method of claim 3, wherein, The crystalline material has a crystallite size between 8 and 65 nm.

16. The method of claim 15, wherein, The range of the crystallite size does not exceed 2 standard deviations of the average crystallite size on the crystalline material.

17. The method of any one of claims 1 to 4, wherein, The step of depositing material onto the substrate using sputter deposition techniques is carried out at a temperature such that the maximum temperature reached by any given square centimetre of substrate material at any given time does not exceed 200 degrees Celsius, as measured on the surface opposite to the surface onto which the material is deposited and averaged over a period of 1 second. 2 The step of depositing material onto the substrate using sputter deposition techniques is carried out at a temperature such that the maximum temperature reached by any given square centimetre of substrate material at any given time does not exceed 200 degrees Celsius, as measured on the surface opposite to the surface onto which the material is deposited and averaged over a period of 1 second.

18. The method of any one of claims 1 to 4, wherein, The deposition rate is greater than 19. A method of determining an optimum working distance for a remote plasma deposition system configured to deposit a layered oxide material, wherein, The method comprises: selecting a range of working distances, wherein the working distances within the range are + / - 50% of the theoretical mean free path of the system; for a plurality of test samples, for each respective sample, performing the method of any of claims 4-18 at different working distances within the selected range, performing a characterization technique capable of determining a characterization property of a layered oxide structure on each test sample after deposition has occurred, identifying samples for which the characterization property exists; From these samples, the sample that most strongly exhibits the characterising feature is selected, and the working distance used during deposition of the test sample is then selected for the system.

20. The method of claim 19, wherein, The method is performed multiple times in order to determine the optimum working distance range for the system to operate at.

21. The method of claim 19, wherein, The test samples of the method comprise an average of a plurality of test samples.

22. A method of determining an optimum working distance for a remote plasma deposition system configured to deposit a layered oxide material, wherein, The method comprises: selecting a range of working distances, wherein the working distances within the range are + / - 50% of the theoretical mean free path of the system; performing the method of any of claims 4-18 at different working distances within the selected range for each respective sample for a plurality of test samples; performing an X-ray diffraction on each test sample after deposition has occurred; identifying the samples that exhibit the diffraction peak characteristic of the presence of a layered oxide structure; From those samples, the sample in which the (normalised) intensity of the characteristic peak is highest is selected, and the working distance used during deposition of the test sample is then selected for the system.

23. The method of claim 22, wherein, The method can optionally be performed multiple times, such that a range of optimum working distances for operating the system can be found.

24. The method of claim 22, wherein, The test samples of the method comprise an average of a plurality of test samples.

25. A method of determining an optimal range of operating pressure for a remote plasma deposition system configured to deposit a layered oxide material, wherein, The method comprises: selecting an initial range of working pressures, between 0.00065 mBar and 1.0e-2 mBar, performing the method of any of claims 4 to 18 at different working pressures within the selected range for each respective sample for a plurality of test samples, performing a characterisation technique on each test sample after deposition has occurred, selecting the test sample deposited at the lowest working pressure from the group of test samples that exhibit the characterisation features of the layered oxide material, and setting this working pressure as the lower limit of the range, selecting the test sample deposited at the highest working pressure from the group of test samples that do not exhibit observable signs of substrate damage, and setting this working pressure as the upper limit of the range.

26. The method of claim 25, wherein, The characterisation technique used comprises X-ray diffraction, and wherein the characterisation features comprise characterisation X-ray diffraction peaks of the layered oxide material.

27. The method of claim 25, wherein, The test samples of the method comprise an average of a plurality of test samples.

28. The method of claim 25, further comprising selecting an optimal operating pressure of the system within an optimal operating pressure range, wherein, The optimum working pressure is the working pressure within the optimum working pressure range that results in the highest deposition rate.

29. A method of manufacturing a battery pack, wherein, The method comprises the method of any of claims 1 to 28.

30. A battery comprising one or more layers of crystalline material formed by carrying out the method of any of claims 1 to 18.

31. A battery cathode comprising one or more layers of crystalline material formed by carrying out the method of any of claims 1 to 18.

32. A battery comprising a plurality of stacked cathode layers, a plurality of stacked electrolyte layers, and a plurality of stacked anode layers, wherein, At least three of the layers in the battery are made by carrying out the method of any of claims 1 to 18.

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