Gas manifold

Abstract

A gas manifold for material deposition is described. The gas manifold comprises a first chamber extending in a first direction and having a first width in a second direction perpendicular to the first direction, one or more inlets coupled to the first chamber for pressurising the first chamber, an output channel extending in the first direction and having a second width in the second direction at an exterior opening, the output channel coupled to the first chamber along the length of the output channel via a first constriction having a minimum width along a third direction, perpendicular to the first direction and second direction, which is equal to a third width. The first width is greater than the third width and the second width is greater than the third width.

Description

[0001] Gas Manifold

[0002] Field of the Invention

[0003] This invention relates to the field of gas manifolds for material deposition, including atomic layer deposition (ALD) and / or chemical vapour deposition (CVD). The invention also relates to systems including the gas manifolds, and methods of using the gas manifolds and / or systems including the gas manifolds.

[0004] Background

[0005] Atomic layer deposition (ALD) is a thin film growth technique based on the sequential exposure of a substrate to self-limiting surface half-reactions (see reference 1 hereinafter). ALD is currently being used commercially by the semiconductor industry to form metal / high-k gate oxide stacks for field effect transistors, capacitors for dynamic random access memory devices, as well as in the thin-film magnetic head industry to form gap dielectrics. Recently, ALD has raised interest from new application areas, such as photovoltaics and organic electronics. A limitation of ALD is the growth speed and the batch processing nature due to vacuum operations.

[0006] Spatial ALD (SALD) is a variation of ALD in which precursors are continuously supplied in different locations and kept apart by an inert gas region or zone, allowing for a continuous deposition process. However, a drawback of SALD is that the film uniformity on a large scale is limited compared to conventional ALD (reference 3). Therefore, there is a need for an SALD technique which increases the uniformity of film.

[0007] In the case of precursor intermixing in the gas phase between the manifold and substrate, the surface reaction is no longer self-limiting, and film growth can occur via CVD, and the growth per cycle is longer limited to one monolayer. This variation of SALD is called atmospheric pressure chemical vapour deposition (AP-CVD). Higher growth rate can be achieved in this mode of operation while maintaining the film quality.

[0008] References

[0009] 1. S. George, Chem. Rev. 110, 111 (2010), and references therein.

[0010] 2. J. Vac. Sci. Technol. A, Vol. 30, No. 1, Jan / Feb 2012

[0011] 3. D. Munoz-Rojas, H. Sun, D. C. Iza, J. Weickert, L. Chen, H. Wang, L. Schmidt- Mende and J. L. MacManus-Driscoll, Progress in Photovoltaics: Research and Applications, 2013, 21, 393-400

[0012] 4. Mater. Horiz., 2014, 1, 314 DOI: 10.1039 / c3mh00136a 5. US8398770B2

[0013] 6. EP2980271A1

[0014] 7. EP3004417B1

[0015] 8. EP2834391A1 9. NL2025783B1

[0016] 10. US20220243326A1

[0017] Summary

[0018] According to a first aspect of the invention there is provided a gas manifold for material deposition. The gas manifold comprises a first chamber extending in a first direction and having a first width in a second direction perpendicular to the first direction, one or more inlets coupled to the first chamber for pressurising the first chamber. The gas manifold further comprises an output channel extending in the first direction and having a second width in the second direction at an exterior opening, the output channel coupled to the first chamber along the length (along the first direction) of the output channel via a first constriction, wherein moving between the first chamber and the output channel along a third direction perpendicular to the first and second directions, the constriction has a minimum width in the second direction which is equal to a third width. The first width is greater than the third width and the second width is greater than the third width.

[0019] The output channel and the first chamber may be coupled along a line extending along the first direction.

[0020] The gas manifold may comprise two or more inlets spaced along the first direction.

[0021] The first constriction may have a profile in a plane perpendicular to the first direction such that the third width occurs at a point along the third direction.

[0022] In other words, the first constriction may have a sharp or "knife-edge" profile. This corresponds to the constriction being as sharp as possible in practical circumstances, for example less than 100 microns along the third direction.

[0023] The first constriction may have a profile in a plane perpendicular to the first direction such that the third width corresponds to a region extending along the third direction for a first constriction length. The constriction length (along the third direction) may be greater than or equal to 100 microns.

[0024] A first transition between the first chamber and the first constriction may have a stepprofile in a plane perpendicular to the first direction.

[0025] The first transition may include, or take the form of, two or more step-changes in width along the second direction. A first transition between the first chamber and the first constriction may have a first tapering profile in a plane perpendicular to the first direction.

[0026] The first tapering profile may be linear along the third direction. The first tapering profile may be curved. The curved first tapering profile may be sigmoid shaped. The curved first tapering profile may have a gradient (i.e. rate of change of width in the second direction with respect to the third direction) which is monotonic.

[0027] A second transition between the first constriction and the output channel may have a step-profile in a plane perpendicular to the first direction.

[0028] The second transition may include, or take the form of, two or more step-changes in width along the second direction.

[0029] A second transition between the first constriction and the output channel may have a second tapering profile in a plane perpendicular to the first direction.

[0030] The second tapering profile may be linear along the third direction. The first tapering profile may be curved. The curved second tapering profile may be sigmoid shaped. The curved second tapering profile may have a gradient (i.e., rate of change of width in the second direction with respect to the third direction) which is monotonic. The curved second tapering profile may have a gradient having a sign opposite to the curved first tapering profile.

[0031] The output channel may have a fourth width between the first constriction and the exterior opening, and wherein the output channel may comprise a third transition along the third direction between the fourth width and the second width.

[0032] The third transition may have a profile in a plane perpendicular to the first direction which may take any form described hereinbefore in relation to the first and / or second transitions.

[0033] The third width may vary with position along the first direction.

[0034] The third width may be a function of distance along the first direction from the closest inlet of the one or more inlets. The variation of the third width along the first direction may be configured to compensate for a pressure drop between the corresponding position at the entrance to the constriction and the closest inlet of the one or more inlets.

[0035] The gas manifold may be configured such that the third width may be varied in use.

[0036] For example, using means known in the field of spectroscopy for provision or manually or automatically adjustable aperture widths. Aperture widths utilised in spectroscopy span the range of third widths relevant to the present disclosure.

[0037] The first width may be greater than the second width.

[0038] The first width may be two times, three times, four times or five times the width of the second width. The first width is preferably no more than 10 times the second width.

[0039] The third width may be between 50 microns and 900 microns. The range between 50 microns and 900 microns may include the endpoints. The third width remains less than the second width.

[0040] The second width may be between 100 microns and 5000 microns. The range between 100 microns and 5000 microns may include the endpoints. The second width may be between 100 microns and 1000 microns. The range between 100 microns and 1000 microns may include the endpoints.

[0041] The gas manifold of any one of claims may be configured such that in response to pressurising the first chamber to a first excess pressure relative to a pressure at the exterior opening, a pressure drop between the first chamber and an entrance to the output channel is at least 30% of the first excess pressure. Such configuration may be obtained, for example, using the ratios of the first width, second width and third width.

[0042] The entrance to the output channel may be the exit from the first constriction, in a direction along a flow path directed from the inlet(s) to the exterior opening via the first chamber and output channel.

[0043] The first excess pressure may be at least 5 Pa. The pressure drop between the first chamber and the entrance to the output channel may be at least 40% of the first pressure. The pressure drop between the first chamber and the entrance to the output channel may be at least 50% of the first pressure. The pressure drop between the first chamber and the entrance to the output channel may be at least 60% of the first pressure. The pressure drop between the first chamber and the entrance to the output channel may be at least 70% of the first pressure. The pressure drop between the first chamber and the entrance to the output channel may be at least 80% of the first pressure.

[0044] The third width may be less than or equal to 10% of the first width. The third width may less than or equal to 5% of the first width. The third width may less than or equal to 4% of the first width. The third width may less than or equal to 3% of the first width. The third width may less than or equal to 2% of the first width. The third width may less than or equal to 1% of the first width.

[0045] The first chamber may extend for a distance in the first direction which is at least 20 times the first width. The first chamber may extend for a distance in the first direction which is at least 50 times the first width.

[0046] In this way, the first chamber may be substantially prismatic, with the exception of any local disturbances associated with the inlet(s) and / or any variations in the width of the first constriction.

[0047] The output channel may extend for a distance in the first direction which is at least 20 times the second width. The output channel may extend for a distance in the first direction which is at least 50 times the second width. In this way, the output may be substantially prismatic, with the exception of any local disturbances associated with variations in the width of the first constriction

[0048] The first constriction may extend in the first direction for the length of the output channel along the first direction.

[0049] The gas manifold may be configured such that, in response to connecting the one or more inlets to a pressurised gas source, a pressure differential is produced across the constriction such that a flow of gas from the pressurised gas source out of the exterior opening is substantially uniform along the first direction. Substantially uniform may mean that, across the exterior opening, a standard deviation of gas velocity is less or equal to 10% of an average of gas velocity. Substantially uniform may mean that, across the exterior opening, a standard deviation of gas velocity is less or equal to 8% of an average of gas velocity. Substantially uniform may mean that, across the exterior opening, a standard deviation of gas velocity is less or equal to 5% of an average of gas velocity.

[0050] The configuration of the gas manifold for substantial uniformity of the flow of gas out of the exterior opening results from the constriction generating a sufficiently large pressure drop that pressure within the first chamber is substantially uniform. In other words, mass flows of gas entering the first chamber via separate inlets (in a case where there are at least two inlets) will not meaningfully mix inside the first chamber. Consequently, it should be borne in mind that the relative dimensions of the first chamber, output channel and constriction are fundamentally unsuitable for mixing of different gases, so that if a mixture of feedstocks is required, mixing needs to be completed to whatever extent is required before entering the first chamber.

[0051] Each inlet may have an inlet width between 3 mm and 5mm, inclusive of endpoints.

[0052] The gas manifold may further comprise a second chamber disposed between the output channel and the first constriction, the second chamber extending in the first direction and having a fifth width in the second direction. The output channel may be coupled to the second chamber via a second constriction having a minimum width along the third direction which is equal to a sixth width. The fifth width may be greater than the sixth width and the second width may be greater than the sixth width.

[0053] In other words, when the second chamber is included, gas entering the first chamber through an inlet passes in order through the first chamber, the first constriction, the second chamber, the second constriction and the outlet channel before flowing out of the exterior opening.

[0054] The second chamber and / or the second constriction may include any features described herein in relation to the first chamber and / or the first constriction. Definitions and / or dimensions applicable to the first chamber and / or the first constriction (of features thereof), may be equally applicable to the second chamber and / or the second constriction. When the second chamber is included, the entrance to the output channel may be the exit from the second constriction, in the direction along the flow path directed from the inlet(s) to the exterior opening via the first chamber and output channel.

[0055] The gas manifold may be configured such that, in response to connecting the one or more inlets to a pressurised gas source, pressure differentials produced across the first and second constrictions are such that a flow of gas from the pressurised gas source out of the exterior opening is substantially uniform along the first direction.

[0056] A flow path between the one or more inlets and the exterior opening may additionally include a third chamber and third constriction, a fourth chamber and fourth constriction, and so forth. The number of chambers and constrictions to use will depend on a balance between available space and a desired degree of uniformity along the first direction of gas flow exiting the exterior opening.

[0057] The successive chamber and / or constriction may include any features described herein in relation to the first chamber and / or the first constriction. Definitions and / or dimensions applicable to the first chamber and / or the first constriction (of features thereof), may be equally applicable to each successive chamber and / or constriction. The entrance to the output channel may be the exit from the final constriction along the flow path directed from the inlet(s) to the exterior opening via the first chamber and output channel.

[0058] The gas manifold may be configured such that, in response to connecting the one or more inlets to a pressurised gas source, pressure differentials produced across each constriction (first, second, third and so forth) are such that a flow of gas from the pressurised gas source out of the exterior opening is substantially uniform along the first direction.

[0059] The gas manifold may further comprise a third chamber disposed between the first and second chambers.

[0060] The gas manifold may further comprise a third transition section disposed between the first and second chambers and / or between the third and second chambers. The third transition section may be tapered.

[0061] According to a second aspect of the invention, there is provided a gas manifold for material deposition comprising one or more inlets connected to an exterior opening extending for a length in a first direction and having a width in a second direction perpendicular to the first direction, wherein the length is five or more times larger than the width. The exterior opening is coupled to the one or more inlets via one or more constrictions configured to develop a pressure differential in response to connecting the one or more inlets to a pressurised gas source, such that a flow of gas from the pressurised gas source out of the exterior opening is substantially uniform along the first direction.

[0062] The gas manifold of the second aspect may include features corresponding to any features of the gas manifold of the first aspect, and vice versa. Definitions applicable to the gas manifold of the first aspect (and / or features thereof) may be equally applicable to the gas manifold of the second aspect (and / or features thereof), and vice versa.

[0063] Substantially uniform may mean that, across the exterior opening, a standard deviation of gas velocity is less or equal to 10% of an average of gas velocity. Substantially uniform may mean that, across the exterior opening, a standard deviation of gas velocity is less or equal to 8% of an average of gas velocity. Substantially uniform may mean that, across the exterior opening, a standard deviation of gas velocity is less or equal to 5% of an average of gas velocity.

[0064] According to a third aspect of the invention, there is provided a material deposition system comprising two or more gas manifolds, each gas manifold according to either the first or second aspect of the invention, wherein the two or more gas manifolds are arranged in a sequence along a processing direction. For each gas manifold, the second direction of that gas manifold is arranged parallel to the processing direction and the one or more inlets of that gas manifold are coupled to a pressurised gas source or to a vacuum source.

[0065] The two or more gas manifolds may be identical. The two of more gas manifolds may differ beyond the common essential features of the gas manifold according to the first aspect. When a manifold has the respective inlets coupled to a vacuum source, the respective outlet slot may sometimes be referred to as an "exhaust channel".

[0066] Whilst each gas manifold is connected to either a pressurised gas source or a vacuum source, different gas manifolds may be connected to different types of source. For example, in a sequence of first to fifth gas manifolds, the first, third and fifth gas manifolds may be connected to the same (or different) vacuum source(s), the second gas manifold may be connected to a first feedstock source for a first atomic layer deposition (ALD) half-reaction, and the fourth gas manifold may be connected to a second feedstock source for a second ALD half-reaction.

[0067] Alternatively, for example when extraction of carrier gas and unreacted feedstock molecules does not require high uniformity, extraction need not be applied using the gas manifolds. Instead the two or more gas manifolds may be interleaved with suitable vacuum sources.

[0068] The material deposition system may be configurable for material deposition onto a substrate in an atomic layer deposition growth regime.

[0069] The material deposition system may be configurable for material deposition onto a substrate in chemical vapour deposition growth regime.

[0070] The material deposition system may be configured for ALD or chemical vapour deposition (CVD) by controlling one or more of:

[0071] • The pressure(s) of gas sources and / or vacuum sources;

[0072] • The spacing of the exterior openings from the substrate; and

[0073] • The spacing between output channels of the two or more manifolds.

[0074] The material deposition system may be configured to deposit one or more different metal oxides. The metal oxides may include, without being limited to, aluminium oxide(s), hafnium oxide(s), titanium oxide(s), zinc oxide(s), tin oxide(s) and so forth. The metal oxides may include ternary oxides including, without being limited to, aluminium doped zinc oxide (AZO), strontium titanate SrTiOs, barium titanate BaTiOs, and so forth. Metal oxides may be stoichiometric or non-stoichiometric. Metal oxides may be crystalline, amorphous or a mixture. Two or more different oxides may be deposited as a blend, mixture or alloy within a single layer. The material deposition system may be configured to deposit a multi-layer coating including, or taking the form of, two or more layers having different compositions, thicknesses, structures etc, the two or more layers formed sequentially on the substrate as is moves relative to the two or more gas manifolds along the processing direction. The material deposition system may be configured to deposit one or more different nitrides, for example silicon nitride, III-V semiconductors gallium nitride.

[0075] Any suitable carrier gasses may used, including but not limited to argon, nitrogen, or any other inert gas or mixture of inert gasses. Any gas which is not reactive relative to a metal precursor may be used as a carrier gas for that metal precursor. Any suitable oxidant may be used, including but not limited to oxygen, ozone, water, ammonia, halogens, halogenated molecules and so forth. According to a fourth aspect of the invention, there is provided a method comprising depositing one or more material layers using one or more gas manifolds according to the first or second aspect, or a material deposition system according to the third aspect. The one or more material layers may form part of a solar panel.

[0076] Brief Description of the Drawings

[0077] Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

[0078] Figure 1A is a schematic of the substrate location for conventional atomic layer deposition over time;

[0079] Figure IB is a schematic of the substrate location for spatial atomic layer deposition over time;

[0080] Figure 2 is a schematic of a prior art spatial atomic layer deposition system;

[0081] Figures 3A and 3B are graphs of normalised flow rates across the first axis of the manifold;

[0082] Figures 4A to 4C is a schematic of a gas manifold for material deposition on a substrate illustrating different flow profiles;

[0083] Figure 5 is a cross section along second and third axes of a first example manifold flow channel;

[0084] Figure 6 is a side view of the plane defined by the first and third axes of an example gas manifold

[0085] Figure 7 is a bottom view of the plane defined by the first and second axes of an example manifold;

[0086] Figure 8 is a top view of the of the plane defined by the first and second axes of an example manifold;

[0087] Figure 9 is cross section along second and third axes of a second example gas manifold for atomic layer deposition;

[0088] Figure 10 is a cross section along second and third axes of a third example gas manifold for atomic layer deposition;

[0089] Figure 11 is a cross section along second and third axes of a fourth example gas manifold for atomic layer deposition;

[0090] Figure 12 is a cross section along second and third axes of a fifth example gas manifold for atomic layer deposition;

[0091] Figure 13 is a cross section along second and third axes of a sixth example gas manifold for atomic layer deposition;

[0092] Figure 14 is a cross section along second and third axes of a seventh example gas manifold for atomic layer deposition;

[0093] Figure 15A is a first example cross section along the first and second axes of the first constriction section of an example gas manifold for atomic layer deposition;

[0094] Figure 15B is a graph of the width of the first example first constriction section along the first axis;

[0095] Figure 16A is a second example cross section along the first and second axes of the first constriction section of an example gas manifold for atomic layer deposition; Figure 16B is a graph of the width of the second example first constriction section along the first axis;

[0096] Figure 17 is cross section along second and third axes of an example of a multi-stage gas manifold for atomic layer deposition;

[0097] Figure 18 is a cross section along second and third axes of a manifold comprising multiple flow paths at first and second levels; and

[0098] Figure 19 presents a comparison of computational fluid-dynamics results from a conventional flow path and an example of an improved flow path according to the present specification.

[0099] Detailed description

[0100] In the following, the same or similar parts are denoted using the same or similar reference numerals.

[0101] Referring to Figures 1A and IB, atomic layer deposition (ALD) is a thin film growth technique based on the sequential exposure of a substrate to self-limiting surface halfreactions followed by a purge of the material being deposited, whereas spatial atomic layer deposition (SALD) is a technique which allows for the self-limiting surface half reactions to happen without the need of a vacuum as a purge. The difference between conventional temporal ALD and spatial ALD lies in the manner that the precursors are delivered to the substrate. This has the effect of speeding up the deposition by up to two orders of magnitude.

[0102] Referring in particular to Figure 1A, in conventional temporal ALD the precursors are dosed into a chamber sequentially, separated in time by a purge step, for example, by applying a vacuum to the chamber. For example, Figure 1A is a schematic graph indicating the substrate location on the vertical-axis, and time on the horizontal-axis. The substrate location 1 is shown as being in the same position over time. The substrate is exposed to a first precursor 2, then the substrate is exposed to a purge step 3. The substrate is next exposed to a second precursor 4, followed again by a purge step 3. The process may then be repeated, starting with the substrate being again exposed to the first precursor 2, until a desired layer thickness has been built up. Thus, in the conventional ALD, the precursors are dosed into a chamber sequentially, separated in time by the purge step 3.

[0103] Referring in particular to Figure IB, a schematic graph having the same axes as in Figure 1A but showing that the substrate location 1 moves along the vertical-axis over time between three distinct and spatially separated zones. The first zone is a half reaction zone 6 for a first precursor 2, the substrate location 1 then moves through an inert gas zone 7, and then onto a half reaction zone 8 for a second precursor 4. Therefore, in spatial ALD, the precursors 2, 4 are supplied continuously, but in different physical locations. Thus, there are at least two zones 6, 8 where, in the presence of a substrate, a half-reaction can take place. If the substrate is present in the second half-reaction zone 6 for a sufficiently long period of time, a saturated monolayer will form from the first precursor 2. When the substrate is moved to the first half-reaction zone 8, the ALD cycle (reaction) is completed to form one ALD monolayer.

[0104] Alternatively, in spatial atomic layer deposition (SALD), the substrate position 1 could be fixed, and the gas supplies of the precursors 2, 4, 7 could be moved, or a combination of the two. To obtain thicker films, this sequence can be repeated for the desired number of cycles.

[0105] Referring also to Figure 2, spatial ALD can have the drawback of limited film uniformity, particularly on a large scale, compared to conventional ALD (see for example, reference 4). This is because when the substrate aspect ratio, i.e., the ratio between width of the half reaction zones 6, 8 along the illustrated y-axis and length along the illustrated x axis, becomes high, for example more than 3: 1, or more than 4: 1, the gas flow across the gas channel exiting the manifold becomes increasingly inhomogeneous. For example, a known system 10 for performing SALD from reference 3 may comprise a head (or manifold) 11 comprising several channels to expose a substrate 12 to various precursor gases 2, 4, or an inert gas 3. Each alternate channel is an inert gas channel 13 for exposing the substrate to an inert gas. First precursor channels 14 for delivering the first precursor to the substrate 12 and second precursor channels 15 for delivering the second precursor to the substrate 12 are alternately interleaved between the inert channels 13. The system works by moving the substrate 12 relative to the head 11, first exposing the substrate 12 to a first precursor 2, then to an inert gas 3, and then to a second precursor 4. In this way, an ALD monolayer 16 is formed. The close distance of the substrate 12 to the head 11 and the inert gas channels 13 interleaved between the precursor channels 14, 15 prevents the different precursors from mixing. With such a system, the time taken for the edges of the monolayer 16 (at the extremes of the substrate along the illustrated x-axis) to reach the self-limited thickness becomes rate limiting. Improved Manifold

[0106] The present specification concerns novel manifold designs, using which greater uniformity of gas flow across the gas channel may be achieved.

[0107] A variety of manifold designs exist, but improve the gas uniformity across the channel (for example, see references 5 to 10). As silicon technology improves, the demand for larger deposition tools has also increased. For example, current wafter sizes may be up to 12 inches (30.48 cm) in diameter. Ensuring a homogenous gas flow across the 12-inch (30.48 cm) gas manifold is desirable for improving the throughput of ALD processes.

[0108] Referring to Figure 3A, ideally, the flow profile of gas exiting a manifold is even across the length (in a first direction, x-axis as illustrated herein) of the outlet of the manifold, that is, that the gas exits the manifold at the same rate across the width of the outlet. In a prior art spatial atomic layer deposition system where there is a single inlet in the centre of the manifold, the flow profile of gas exiting the outlet shows a greater normalised flow rate at the centre of the outlet than at the edges (paraboliclike dashed line), whereas the flow profile of the present invention (again, with a single inlet in the centre of the manifold) achieves a constant flow rate across the majority of the outlet of the manifold, with the normalised flow rate dropping slightly towards the edges of the outlet (solid line). Referring to Figure 3B, where there are two inlets towards the edges of the manifold, flow profiles for a prior art spatial atomic layer deposition system show two peaks of normalised flow rate concentrated around where the two inlets are located (dashed line), whereas for the present invention, the flow profile is much more even across the width along the x-axis, with only a slight reduction in normalised flow rate towards the middle and extreme edges of the outlet of the manifold of the system (solid line).

[0109] Manifolds according to the present specification are not limited to self-limiting ALD processes, and may also be employed within chemical vapour deposition (CVD) regimes, where they may provide the effect of improving the uniformity of a deposited film.

[0110] Referring also to Figures 4A-C, a system 20 for improving the uniformity of the depositing layers of precursor 2, 4 on a substrate 22 comprises a gas manifold 21. The gas manifold 21 has at least one gas flow path 23. The substrate 22 can be moved relative to the manifold 21 along at least a first axis (e.g., the y-axis as illustrated). The manifold 21 comprises a simple homogeniser (not shown) where the gas flow across the channel 23 can be uniform with a single gas inlet with high substrate 22 aspect ratios, even beyond 12 inches (30.48 cm), where coatings by SALD for large planar objects can also be achieved. First, second and third example systems 20i, 20z, 2O3 illustrate three different flow profiles of gas through a gas flow path 23i, 232, 23s of a manifold 21i, 212, 213 and onto a substrate 22i, 222, 223. Referring in particular to Figure 4A, the first example system 20i illustrates an ideal flow profile of gas flowing through the gas flow path 23i, where the gas meets the substrate 22i at the same time along the x-axis (first direction). Such uniformity of gas flow is difficult to achieve. Referring in particular to Figure 4B, the gas flow profile typically achieved by the prior art results in gas towards the middle of the length (x-axis) of the outflow of the gas flow path 232 reaching the substrate 222 before the gas towards the edges of the outflow of the gas flow path 232. In the prior art, the gas reaches the substrate

[0111] 222 significantly later towards the edges relative to the middle of the gas flow path 232. Referring in particular to Figure 4C, the gas flow profile of what can be achieved using the present invention is illustrated, showing that the gas meets the substrate

[0112] 223 at the same time across the majority of the length (x-axis, first direction) of the outflow from the gas flow path 23s, with only gas right at the edges of the gas path (x-axis) arriving at the substrate 223 slightly later.

[0113] Referring also to Figure 5, a cross section along the plane defined by the second and third axes (y-z in the illustration) of a gas flow path (also referred to as a gas flow channel) 23 through a manifold 21 provides first example design. Since the flowrate, f, exiting the gas channel 23 at a certain point along the horizontal channel 23, x (first direction), is a function of delta pressure, P, from inlet 27 to the outlet 28: flowrate(x) oc AP = Pin(et(x) - Poutlet(x)

[0114] (1) To allow uniform flow across Poutiet (the exterior opening 28 of the gas flow path 23), it is desirable if AP is the same at every point of x. To achieve this, the gas manifold 21 for material deposition comprises a first chamber 30 which extends in a first direction (the x-axis in this illustration) and has a first width (also referred to as first chamber width), wi, in a second direction (the y-axis in this illustration) perpendicular to the first direction. The manifold 21 comprises one or more inlets 27 coupled to the first chamber 30 for pressurising the first chamber 30. The inlet(s) 27 have a width, wm, in the second direction y (and are often circular). The manifold 21 comprises an output channel 31 extending in the first direction x and having a second width (also referred to as the output channel width), W2, in the second direction y at an exterior opening 28. The output channel 31 is coupled to the first chamber 30 along the length (parallel to the first direction x) of the output channel 31 via a first constriction 32. Moving between the first chamber and the output channel through the first constriction 32 along a third direction (z-axis in this illustration), a width of the first constriction 32 along the second axis y has a minimum, third width W3. The third direction z is perpendicular to both the first x and second y directions (forming an orthogonal set). The first width, wi, is greater than the third width, W3, and the second width, W2, is greater than the third width, W3. The output channel 31 and the first chamber 30 may be coupled along a line extending along the first direction. The manifold 21 has a top surface 33 nearest the inlet 27 and a bottom surface 34 nearest the output channel 31.

[0115] Referring also to Figure 6, a side view of the manifold 21 along the first x and third z axes shows an inlet 27 of the manifold 21 which allows gas to move in to a high- pressure (Pi) first chamber 30 where the pressure is equalized in the first chamber 30 and the output channel across the horizontal. The pressure (P2) at the outlet 28 can be atmospheric pressure. Since the pressure in the high-pressure first chamber 30 is not completely homogeneous, small variations across the horizontal will exist, e.g., the horizontal variation in pressure is ±a Pa. Thus, the flowrate variation would be:

[0116] (2 Thus, the higher the pressure Pi, the smaller flowrate variation. However, when Pi is high, AP is also high, and consequently the flowrate is high, leading to a high gas exit velocity, v, which can be undesirable because velocity, v, within specific ranges is desirable to operate in a SALD growth regime.

[0117] The gas velocity in a channel is defined as the "flow flux", where it is calculated as the total gas flow through a channel divided by the cross-sectional area perpendicular to direction of the flow.

[0118] V =Q / A

[0119] Where Q is the gas flow rate (i.e., m3s-1) and A is the cross-sectional area of channel (i.e. m2), giving the velocity, v (i.e. ms1). Since A is the total channel extension (along the first axis x and defined by the deposition area, i . e. , 12 inches (30.48 cm)), multiplied by the width of the first constriction, W3. The first constriction width W3 would therefore be the only variable. Preferably, the width of the first constriction, W3, should be quite small to mimic the ideal SALD flow pattern where the gas exists as two-dimensional planes (for example, see Figure 2), reducing or preventing mixing of the precursor gases 2, 3. Thus, ideally, the gas has a laminar flow profile 35 exiting the exterior opening 28.

[0120] Referring to Figure 6, a bottom view of the gas manifold 21 defined by the first and second axes shows four exterior openings 28, one for each channel, spaced along the second axis. Each exterior opening 28 is a high aspect ratio slit. Referring to Figure 8, a top view of the gas manifold 21 again defined by the first and second axes shows four inlets 27, one for each channel 23, spaced apart along the second axis, and optionally, second and third inlets 27z, 273 spaced apart along the first axis, such that a single channel 23 may have one, two or three inlets 27. Each channel 23 may have any suitable number of inlets 27 however.

[0121] Referring to Figures 5 to 8, the gas manifold 21 uses a simple constriction design to create the high-pressure first chamber 30 to allow the pressure to equilibrate with the inlet 27 and results in a AP. The first channel 30 is then expanded to decrease the gas exit velocity to the desired velocity. The first constriction width, W3, can also be adjusted, either dynamically in use or in manufacture, to control the overall gas flowrate while maintaining a high pressure Pi in the first chamber 30. In this way, only one gas inlet 27 is needed for each channel 23, and the design is sufficient even at very high aspect ratios. For example, very large surfaces can be used, e.g., windows (500 microns x 12 inches). There may be a plurality of inlets for each channel, for example, there may be a second inlet 272, and / or a third inlet 273. The inlets 27 may be spaced apart along the first direction (x-axis) or second direction (y-axis).

[0122] Following the gas constriction, the gas expands and slows down before exiting the manifold 21 (in accordance with Equation (3)). The gas velocity profile across the channel slit width is likely to be turbulent where ideally it should be as laminar as possible. Further downstream treatment is needed to convert the gas from turbulent to laminar.

[0123] Referring again to Figure 4, ideally, the gas has a laminar flow profile exiting the manifold before the gas hits the substrate in order to minimise any spatial variation of the across the output channel width W2, as the same as minimising the gas velocity profile across the horizontal of the manifold 21 across 12 inches (30.48 cm). The first flow profile on the left-hand side of Figure 4 shows the ideal flow profile exiting the gas manifold 21, where the gas "hits" the substrate 22 at the same time across the output channel width W2. The centre flow profile of Figure 4 shows parabolic flow profile, where the gas in the middle of the slit "hits" the substrate 22 first followed by the sides, which less desirable as it may introduce spatial variation of the film macroscopically. The right-hand side flow profile of Figure 4 is a profile that is a compromise between the ideal and the less desirable, which could be achievable, where the majority of the gas "hits" the substrate 22 at the same time across the output channel width W2, with only the edges of the flow profile arriving later.

[0124] After the gas leaves the first constriction 32, a "rough" material (e.g., the wall of at least a portion of the output channel may comprise a rough texture, i.e., not be completely smooth) may be used in the downstream channel to aid the conversion of turbulent flow to laminar flow 35 while minimising the distance the gas needs to travel (to avoid a large manifold). This stage of the flow will shape the gas flow similar to the centre flow profile in Figure 4. Following, a "smooth" material with low gas friction should be used in the second part to uniformise the flow pattern and minimise drag at the walls, shaping the gas flow closer to the third gas profile in Figure 4.

[0125] The manifold 21 may be made from any suitable solid material that can withstand pressures of, for example five bar (500 kPa). For example, many metals would be suitable, as would suitable polymers, plastics, and resins. Preferably, the manifold 21 will have anti-corrosive properties, and / or an anti-corrosive coating. Specific materials or coatings can be chosen to have a high gas sheer or a low gas sheer to give addition control over fluid dynamics e.g., high sheer leads to higher AP and more turbulent flow. The manifold can be 3D printed, machined, moulded, cast, or manufactured using any other suitable technique using the chosen material. Various appropriate mechanical adjustments may be performed during the manufacturing process.

[0126] The curvature of the output channel 31 walls (in the z-y plane as illustrate in Figure 5) may vary, for example by being adjusted before or during manufacturing, depending on the degree of flow control desired. The exterior opening 28 slit width can also be varied, again before or during manufacture, for further flow control. Will change on depending on the effect.

[0127] Referring also to Figure 9, a cross section along the plane defined by the second and third axes of a gas flow path or gas channel 23 through a second example manifold 21 is similar to that of Figure 5, but where the output channel width W2 is narrower than that shown in Figure 5. The input width wm is also greater than in the manifold 21 of Figure 5. Preferably, gas flow exiting the manifold 21 via the exterior opening 28 in as close to "planar flow" or "laminar flow" as possible. To achieve this, the first constriction width W3 can be made smaller than W2, where the higher the ratio of W2 / W3, the better the effect of gas expansion, allowing for greater uniformity of the gas flow. However, if the first constriction width W3 is too small, the manifold 21 may be more difficult to fabricate and manufacture. However, a large W2 / W3 and W1 / W3 ratio could lead to a higher degree of turbulent flow. Thus, it is important to select the appropriate size of the first constriction width W3. In addition, the length Li of the output channel 31 along the third direction (z-axis) is a determining factor in how long the gas takes to become laminar before exiting the manifold 21. This can be calculated based fluid mechanics such as Reynold Number: n Re = - PVL1

[0128] R

[0129] (3) The gas manifold 21 may have a first constriction 32 with a profile in a plane perpendicular to the first direction (x-axis) such that the third width W3 occurs at a point along the third direction. In other words, the first constriction 32 may have a sharp or "knife-edge" profile. For example, the first constriction 32 may be as narrow or as sharp as possible in practical circumstances, for example less than 100 microns along the third direction.

[0130] The first width wi of the first chamber 30 of the gas manifold 21 may be greater than the second width W2, that is, the output channel width. The first width wi may be two times, three times, four times or five times the width of the second width W2. The first width wi is preferably no more than 10 times the second width W2.

[0131] The manifold 21 may have a range of suitable dimensions. For example, the output channel width W2 may be between around 1 and 2 mm. The third width W3 (that is, the first constriction width), may be between 50 microns and 900 microns inclusive of endpoints. The third W3 width remains less than the second width W2.

[0132] The second width W2 may be between 100 microns and 1000 microns inclusive of end points. Each inlet may have an inlet width wm of be between 3 mm and 5 mm, inclusive of endpoints. Referring to Figure 10, a cross section along the plane defined by the second and third axes of a gas flow path or gas channel 23 through a third example manifold 21 is similar to the first and second example gas manifolds 21 in Figures 5 and 9. The gas manifold 21 may include a more gradual constriction and expansion of the gas from the first chamber 30 to the output channel 31, which can improve gas flow behaviour downstream as well as improving the gas flow uniformity across the exterior opening 28 to further compensate any pressure variation in the first chamber 30. The length L3 (along the third direction, z) between the first chamber 30 and the first constriction section 32 can be varied accordingly for performance and minimizing space consumption.

[0133] The first constriction 32 may have a profile in a plane perpendicular to the first direction such that the third width W3 corresponds to a region extending along the third direction for a first constriction length L2 (along the third direction, z) which may be greater than or equal to 100 microns. The length Li (along the third direction, z) of the output channel 31 may also be greater than or equal to 200 microns. In this example, a first transition section 36 from the first chamber 30 and the first constriction 32 may be tapered in a plane perpendicular to the first direction, instead of stepped. The tapering may have any suitable profile, for example, the taper may be linear, curved, or be sigmoid shaped. The tapering profile may have a monotonic gradient, that is, the rate of change of width in the second direction with respect to the third direction may be monotonic. There may be a second transition section 37 from the first constriction 32 to the output channel 31 which may have a reverse profile from that of the first transition section, i.e., a mirror image. Alternatively, the second transition section 37 may have a different tapering or stepped profile to the first transition section 36.

[0134] Referring to Figure 11, a cross section along the plane defined by the second and third axes of a gas flow path or gas channel 23 through a fourth example manifold 21 similar to the first to third examples. However, in the fourth example, the first chamber 30 has a greater width W2, making the chamber an elliptical shape. This has the effect of increasing the W2 / W3 ratio, which can lead to better gas uniformizing effects by the potential increase in gas pressure variation across the first chamber width W2, while decreasing the horizontal gas pressure variation across the manifold 21. The fourth example also includes an extended constriction length L2 (along the third direction, z), where a high gas friction material can be used to convert the gas into laminar flow, before expanding into the output channel 31 along the output channel length Li (along the third direction, z) with low gas friction for improved gas profile. The first constriction 32 in the fourth example has a profile in a plane perpendicular to the first direction such that the third width, W3, corresponds to a region extending along the third direction for a first constriction length, L2 (along the third direction, z). The first constriction length, L2 (along the third direction, z), may be greater than or equal to 100 microns.

[0135] Again, as with the second example manifold 21, the first transition between the first chamber 30 and the first constriction 32 may have a step-profile in a plane perpendicular to the first direction, and the first transition may include, or take the form of, two or more step-changes in width along the second direction.

[0136] Referring to Figure 12, a cross section along the plane defined by the second and third axes of a gas flow path or gas channel 23 through a fifth example manifold 21 is similar to the first to fourth example gas manifolds 21. The fifth example manifold 21 includes a more gradual gas expansion process in the second transition section 37, with a linear tapering. The length (along the third direction, z) of the second transition section can be varied to produce the closest to laminar flow possible. As with the second example manifold 21 the first transition section 36 may have a stepprofile in a plane perpendicular to the first direction and may include a plurality of steps. Again, the first transition section 36 may include, or take the form of, two or more step-changes in width along the second direction.

[0137] As with the fourth example, the first constriction 32 may have a profile in a plane perpendicular to the first direction such that the third width W3 corresponds to a region extending along the third direction for a first constriction length (not shown, along the third direction, z), which may be greater than or equal to 100 microns.

[0138] Referring to Figure 13, a cross section along the plane defined by the second and third axes of a gas flow path or gas channel 23 through a sixth example manifold 21 is similar to the first to fifth example gas manifolds 21. The sixth example gas manifold includes a second transition 27 which has a step-profile in a plane perpendicular to the first direction between the first constriction 32 and the output channel 31. In other words, there is a step-profile expansion with rectangular edges at the second transition section 37 from the first constriction 32 to the output channel 31 which can achieve better flow characteristics for the gas and is easier to manufacture. Furthermore, the first transition section 36 includes a step contraction with edges close to 90° from the first chamber 30 to the first constriction 32. Again, the second transition may include, or take the form of, two or more step-changes in width along the second direction.

[0139] Referring to Figure 14, a cross section along the plane defined by the second and third axes of a gas flow path or gas channel 23 through a seventh example manifold 21 is also similar to the first to sixth gas manifolds 21. Again, the first constriction 32 has a profile in a plane perpendicular to the first direction such that the third width, W3, corresponds to a region extending along the third direction for a first constriction length L2 (along the third direction, z). As with the previous examples, the constriction length L2 (along the third direction, z) may be greater than or equal to 100 microns. The first transition length L3 (along the third direction, z) may also be greater than or equal to 100 microns.

[0140] In the seventh example, the gas manifold 21 may have a first transition 36 between the first chamber 30 and the first constriction 32 which has a tapering profile in a plane perpendicular to the first direction. The first tapering profile may be linear or curved along the third direction. If the profile of the first tapering profile is curved, the profile may be sigmoid shaped, or may have a gradient (i.e. , rate of change of width in the second direction with respect to the third direction) which is monotonic.

[0141] In the seventh example, the output channel 31 has a second width W4 along a portion of the output channel length Li (along the third direction, z) between the exterior opening 28 with an output channel width W2, and the second transition section 37. There is an output channel transition section 38 between the second output channel width W4 and the first output channel width W2 at the exterior opening 28. The output channel transition section may have a profile in a plane perpendicular to the first direction which takes any form described hereinbefore in relation to the first and / or second transitions section 36, 37, for example, it may be stepped, it may be tapered, the tapering may be curved, sigmoidal or have a gradient which is monotonic.

[0142] The seventh example manifold 21 may allow the same constriction and expansion concept described for the previous examples to be applied to reverse gas flow with a vacuum. This will ensure a high vacuum in the first chamber 30, thus allowing uniform suction across the first axis of the manifold 21. The output channel transition section 38 may allow for higher or more uniform suction of the surrounding gas. Depending on the suction required, the length Ls (along the third direction, z) of the output channel transition section 38 and the output channel width W2 may be varied accordingly for optimal suction. Referring to Figure 15A, a cross section along the plane defined by the first and second axes of an example of the gas manifold 21 where the constriction section 32 defines a first constriction width W3 which varies with position along the first direction (x-axis). In this example, the first construction width W3 is greater towards the edges of the manifold 21 than in the centre of the manifold 21. The first constriction width W3 may be a function of distance along the first direction from the closest inlet 27 of the one or more inlets 27. Referring now to Figure 15B, a graph of the first constriction width W3 over the distance along the first axis illustrates the variation. The variation of the first constriction width W3 along the first direction may be configured to compensate for a pressure drop between the corresponding position at the entrance to the constriction and the closest inlet of the one or more inlets. The first constriction width W3 may be varied in use, for example using suitable means known in the field of spectroscopy for providing manually or automatically adjustable aperture widths. Aperture widths utilised in spectroscopy span the range of first constriction widths relevant to the present disclosure.

[0143] Referring to Figure 16A, a cross section along the plane defined by the first and second axes of an example of the gas manifold 21 where the constriction section 32 defines a first constriction width W3 which varies with position along the first direction (x-axis), but in this example, there are two inlets 27, and the first constriction width W3 is narrowest at those inlets and increases towards the edges and the centre of the manifold 21. Referring to Figure 16B, a graph of the first constriction width W3 over the distance along the first axis illustrates the variation.

[0144] Referring to Figure 17, a multi-stage gas constriction and expansion can be used to further improve the horizontal gas uniformity. A cross section along the plane defined by the second and third axes of a gas flow path or gas channel 23 through of a multistage manifold 21 illustrates the design. The multi-stage manifold 21 includes a second chamber 40 arranged between the output channel 31 and a second constriction 42. The second chamber 40 extends in the first direction (x-axis) and has a second chamber width, ws, in the second direction (y-axis). The output channel 31 is coupled or attached to the second chamber 40 via the second constriction 42. The second constriction 42 has a minimum width, we, along the third direction. The second chamber width ws is greater or equal to the second constriction width we. The output channel width W2 is also greater or equal to the second constriction width we. In other words, when the second chamber 40 is included, gas entering the first chamber 30 through an inlet 27 passes in order through the first chamber 40, the first constriction 32, the second chamber 40, the second constriction 42 and the outlet channel 31 before flowing out of the exterior opening 28.

[0145] The second chamber 40 and / or the second constriction 42 may include any of the features described herein in relation to the first chamber 30 and / or the first constriction 32. Definitions and / or dimensions applicable to the first chamber 30 and / or the first constriction 32 (of features thereof), may be equally applicable to the second chamber 40 and / or the second constriction 42.

[0146] A flow path between the one or more inlets 27 and the exterior opening 28 may additionally include a third chamber 50 and third constriction 52 which has a third constriction width w? along the third direction, a fourth chamber (not shown) and fourth constriction (not shown), and so forth. There may be a transition section 54 between the additional chambers (e.g., the third chamber 50), and the adjacent constriction (e.g., third constriction 52) having a length L? (along the third direction, z). The transition section 54 may be tapered from the chamber 50 to the constriction 52 and have straight or curved walls. The number of chambers and constrictions to use will depend on a balance between available space and a desired degree of uniformity along the first direction of gas flow exiting the exterior opening 28.

[0147] Any of the features in the example manifolds 21 described above are interchangeable with those in other examples.

[0148] In another example, the gas manifold 21 suitable for material deposition includes one or more inlets 27 connected to an exterior opening 28 extending for a length in a first direction (x-axis) and having a width, W2, in a second direction (y-axis) perpendicular to the first direction. In this example, the length (along the first direction, x) is five or more times larger than the width W2 of the exterior opening 28. The exterior opening 28 is coupled or attached to one or more of the inlets 27 via one or more constrictions 32, 42, 52. The constrictions are arranged to develop a pressure differential in response to connecting the one or more inlets 27 to a pressurised gas source. This has the effect of allowing a flow of gas from the pressurised gas source out of the exterior opening 28 that is substantially uniform along the first direction. In this context, substantially uniform may mean that, across the exterior opening 28, a standard deviation of gas velocity is less or equal to 10%, 8%, or 5% of an average of gas velocity.

[0149] Two or more gas manifold 21 described earlier may be used together. For example, a material deposition system may include a plurality of these gas manifolds 21 arranged in a sequence along a processing direction. For each gas manifold, the second direction of that gas manifold 21 is arranged parallel to the processing direction. Additionally, the one or more inlets 27 of that gas manifold 21 are coupled to a pressurised gas source or to a vacuum source. The flow paths 23 of the gas manifolds 21 of such a system may be identical, or they may differ, for example there may be a gas flow path 23 of the first example and a gas flow path 23 of the fourth example. When a manifold 21 has the respective inlets 27 coupled to a vacuum source, the respective outlet slot 28 may sometimes be referred to as an "exhaust channel".

[0150] Whilst each gas manifold 21 is connected to either a pressurised gas source or a vacuum source, different gas manifolds 21 (or different gas flow paths 23 of the same gas manifold 21) may be connected to different types of sources. For example, in a sequence of first to fifth gas manifolds 21, the first, third and fifth gas manifolds 21 (or first, third and fifth gas flow paths 23) may be connected to the same (or different) vacuum source(s), the second gas manifold 21 (or second gas flow path 23) may be connected to a first feedstock source for a first atomic layer deposition (ALD) half-reaction, and the fourth gas manifold 21 (or forth gas flow path 23) may be connected to a second feedstock source for a second ALD half-reaction.

[0151] Alternatively, for example when extraction of carrier gas and unreacted feedstock molecules does not require high uniformity, extraction need not be applied using the gas manifolds 21, instead the two or more gas manifolds 21 may be interleaved with suitable vacuum sources.

[0152] Referring to Figure 18, a single manifold 21 may have a plurality of gas flow paths 23. The first chambers 30 of the flow paths 23 may be arranged in such a way that maximises the number of exterior openings 28 for a given manifold 21. The lengths (along the third direction, z) of each output channel 31 may vary to allow for the different positions of the first chambers 30 in the vertical axis (z-axis). The respective inlets 27 (not shown in Figure 18 for clarity) may likewise be arranged along the vertical axis (z-axis) at or close to the position of the first chambers 30. First constructions 32 are arranged between the first chambers 30 and their respective output channels 31.

[0153] The material deposition system 20 may be configurable for material deposition onto a substrate in an atomic layer deposition growth regime or a vapour deposition growth (e.g., chemical vapour growth) regime. For example the system 20 may be configured by controlling one or more of:

[0154] • The pressure(s) of gas sources and / or vacuum sources;

[0155] • The spacing of the exterior openings from the substrate; and

[0156] • The spacing between output channels 31 of the two or more manifolds 21. For example, the spacing may be between 0.5 mm and 5 mm.

[0157] Additionally, the system 20 can be used to deposit one or more different metal oxides. For example, the metal oxides may include, without being limited to, aluminium oxide(s), hafnium oxide(s), titanium oxide(s), zinc oxide(s), tin oxide(s) and so forth. The metal oxides may include ternary oxides including, without being limited to, aluminium doped zinc oxide (AZO), strontium titanate SrTiOs, barium titanate BaTiOs, and so forth. Metal oxides may be stoichiometric or non-stoichiometric. Metal oxides may be crystalline, amorphous or a mixture of crystalline and amorphous. Two or more different oxides may be deposited as a blend, mixture or alloy within a single layer. The material deposition system may be configured to deposit a multi-layer coating including, or taking the form of, two or more layers having different compositions, thicknesses, structures etc, the two or more layers formed sequentially on the substrate as is moves relative to the two or more gas manifolds along the processing direction.

[0158] Any suitable carrier gasses may be used, including but not limited to argon, nitrogen, or any other inert gas or mixture of inert gasses. Any gas which is not reactive relative to a metal precursor may be used as a carrier gas for that metal precursor.

[0159] Any suitable oxidant may be used, including but not limited to oxygen, ozone, water, ammonia, halogens, halogenated molecules and so forth.

[0160] Referring also to Figure 19, a comparison of computational fluid-dynamics simulations performed for a conventional, straight-walled gas flow path (dashed line), and for an improved flow path 23 including a first chamber 30 and output channel 31 (solid line). The improved flow path 23 modelled had a profile substantially as illustrated for the flow paths 23 shown in Figure 18.

[0161] To examine the flow inside any manifold design, a highly parallelised numerical framework can be used that employs a domain-decomposition strategy. The numerical technique consists of solving the transient incompressible three-dimensional (3D) Navier-Stokes (NS) equation with LES (large eddy simulation) using a constant Smagorinsky-Lilly turbulence model. The parallelization of the code is based on an algebraic domain decomposition technique. The code may be written in any suitable computing language (for example, Fortran 2008) and communications may be managed by data exchange across adjacent subdomains via the Message Passing Interface (MPI) protocol. The value of wl, w2 and w3 may be 3 mm, 0.5 mm and 0.25 mm, respectively.

[0162] It may be observed that the improved design of gas flow path 23 according to the present specification (solid line) exhibits significantly improved uniformity compared to the conventional flow path (dashed line) lacking the first chamber 30 and constriction 32.

[0163] Modifications

[0164] It will be appreciated that various modifications may be made to the embodiments hereinbefore described. Such modifications may involve equivalent and other features which are already known in the art of gas manifolds for material deposition, systems including such gas manifolds and / or methods of using either, and which may be used instead of or in addition to features already described herein. Features of one embodiment may be replaced or supplemented by features of another embodiment.

[0165] The above designs and examples can be combined in any way to achieve most optimal system.

[0166] Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel features or any novel combination of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention. The applicants hereby give notice that new claims may be formulated to such features and / or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

Claims

Claims1. A gas manifold for material deposition comprising at least one flow path, the at least one flow path comprising : a first chamber extending in a first direction and having a first width in a second direction perpendicular to the first direction; one or more inlets coupled to the first chamber for pressurising the first chamber; an output channel extending in the first direction and having a second width in the second direction at an exterior opening, the output channel coupled to the first chamber along the length of the output channel via a first constriction, wherein moving between the first chamber and the output channel along a third direction perpendicular to the first and second directions, the constriction has a minimum width in the second direction which is equal to a third width; wherein the first width is greater than the third width and the second width is greater than the third width.

2. The gas manifold of claim 1, comprising two or more inlets spaced along the first direction.

3. The gas manifold of claims 1 or 2, and wherein the first constriction has a profile in a plane perpendicular to the first direction such that the third width occurs at a point along the third direction.

4. The gas manifold of claims 1 or 2, wherein the first constriction has a profile in a plane perpendicular to the first direction such that the third width corresponds to a region extending along the third direction for a first constriction length.

5. The gas manifold of any one of claims 1 to 4, wherein a first transition between the first chamber and the first constriction has a step-profile in a plane perpendicular to the first direction.

6. The gas manifold of any one of claims 1 to 4, wherein a first transition between the first chamber and the first constriction has a first tapering profile in a plane perpendicular to the first direction.

7. The gas manifold of any one of claims 1 to 6, wherein a second transition between the first constriction and the output channel has a step-profile in a plane perpendicular to the first direction.

8. The gas manifold of any one of claims 1 to 6, wherein a second transition between the first constriction and the output channel has a second tapering profile in a plane perpendicular to the first direction.

9. The gas manifold of any one of claims 1 to 8, wherein the output channel has a fourth width between the first constriction and the exterior opening, and wherein the output channel comprises a third transition along the third direction between the fourth width and the second width.

10. The gas manifold of any one of claims 1 to 9, wherein the third width varies with position along the first direction.

11. The gas manifold of any one of claims 1 to 10, wherein the gas manifold is configured such that the third width may be varied in use.

12. The gas manifold of any one of claims 1 to 11, wherein the first width is greater than the second width.

13. The gas manifold of any one of claims 1 to 12, wherein the third width is between 50 microns and 900 microns.

14. The gas manifold of any one of claims 1 to 13, wherein the second width is between 100 microns and 5000 microns.

15. The gas manifold of any one of claims 1 to 14, configured such that in response to pressurising the first chamber to a first excess pressure relative to a pressure at the exterior opening, a pressure drop between the first chamber and an entrance to the output channel is at least 30% of the first excess pressure.

16. The gas manifold of any one of claims 1 to 15, wherein the third width is less than or equal to 10% of the first width.

17. The gas manifold of any one of claims 1 to 16, wherein the first chamber extends for a distance in the first direction which is at least 20 times the first width.

18. The gas manifold of any one of claims 1 to 17, wherein the output channel extends for a distance in the first direction which is at least 20 times the second width.

19. The gas manifold of any one of claim 1 to 18, configured such that, in response to connecting the one or more inlets to a pressurised gas source, a pressure differential is produced across the first constriction such that a flow of gas from the pressurised gas source out of the exterior opening is substantially uniform along the first direction.

20. The gas manifold of any one of claims 1 to 19, further comprising: a second chamber disposed between the output channel and the first constriction, the second chamber extending in the first direction and having a fifth width in the second direction; wherein the output channel is coupled to the second chamber via a second constriction having a minimum width along the third direction which is equal to a sixth width; wherein the fifth width is greater than the sixth width and the second width is greater than the sixth width.

21. The gas manifold of claim 20, further comprising : a third chamber disposed between the first and second chambers.

22. The gas manifold of claim 21, further comprising : a third transition section disposed between the first and second chambers and / or between the third and second chambers.

23. The gas manifold of claim 22 wherein the third transition section is tapered.

24. A gas manifold for material deposition comprising one or more inlets connected to an exterior opening extending for a length in a first direction and having a width in a second direction perpendicular to the first direction, wherein the length is five or more times larger than the width; wherein the exterior opening is coupled to the one or more inlets via one or more constrictions configured to develop a pressure differential in response to connecting the one or more inlets to a pressurised gas source, such that a flow of gas from the pressurised gas source out of the exterior opening is substantially uniform along the first direction.

25. A material deposition system comprising two or more gas manifolds, each gas manifold according to any one of claims 1 to 24, wherein the two or more gas manifolds are arranged in a sequence along a processing direction; wherein for each gas manifold : the second direction of that gas manifold is arranged parallel to the processing direction; and the one or more inlets of that gas manifold are coupled to a pressurised gas source or to a vacuum source.

26. The material deposition system of claim 25, wherein the material deposition system is configurable for material deposition onto a substrate in an atomic layer deposition growth regime.

27. The material deposition system of claims 25 or 26, wherein the material deposition system is configurable for material deposition onto a substrate in chemical vapour deposition growth regime.

28. The material deposition system of any one of claims 25 to 27, configured to deposit one or more different metal oxides.

29. A method comprising depositing one or more material layers using one or more gas manifolds according to any one or claims 1 to 24 or a material deposition system according to any one of claims 25 to 28.

30. The method of claim 29, wherein the one or more material layers form part of a solar panel.

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