Method and apparatus for depositing chemically modified metal films

Abstract

The invention relates to a method comprising the steps of depositing a metal film on a surface of a substrate by sputtering from a metal target in a first atmosphere, and at least partially chemically modifying the deposited metal film and a surface of the metal target in a second atmosphere. The invention also relates to a substrate coated with a chemically modified metal film on its surface, and to an apparatus for carrying out the method of the invention.

Description

Technical Field

[0001] This invention relates to the field of thin film deposition. In particular, this invention relates to a method comprising the steps of: depositing a metal film on the surface of a substrate by sputtering from a metal target; and at least partially chemically modifying the deposited metal film and the surface of the metal target. The invention also relates to a substrate with a surface coated with a chemically modified metal film, and an apparatus for performing the method of the invention. Background Technology

[0002] Known methods and apparatus for depositing chemically modified metal films typically involve metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). These techniques are costly and / or require high growth temperatures, which can damage the substrate or previously deposited layers. Furthermore, achieving high doping levels using these established processes is often challenging. Known alternatives include reactive sputtering; however, it has been previously found to produce layers of lower quality compared to MOCVD and MBE. Summary of the Invention

[0003] One object of the present invention is to provide an improved method and apparatus for depositing chemically modified metal films, particularly semiconductor films, on a substrate. Another object is to provide an improved substrate having a coating surface.

[0004] These objectives are achieved by a method having the features of claim 1, an apparatus having the features of claim 34, and a substrate having the features of claims 31 to 33.

[0005] In a first aspect, the present invention relates to a method for depositing a chemically modified metal film on a substrate, wherein the method comprises the following steps: (a) Providing a substrate and a metal target in a vacuum chamber; (b) In a first atmosphere, a metal film is deposited on the surface of a substrate by sputtering metal from a metal target; and (c) Under a second atmosphere, the surfaces of the deposited metal film and the metal target are at least partially chemically modified using a reactive gas. The first atmosphere is optionally an atmosphere comprising at least 40 vol% inert gas; and The second atmosphere is an atmosphere that includes reactive gases.

[0006] Compared to MOCVD, MBE, and standard sputtering methods, this method represents an improved approach for depositing chemically modified metal films on substrates. Compared to existing methods, the method of the present invention can achieve, for example, higher layer quality (e.g., epitaxial layers), allows for lower processing temperatures, achieve high conductivity of the doped metal film, and improve the crystallinity and surface roughness of the sputtered metal film.

[0007] Suitable sputtering apparatus for carrying out the method of the present invention is known in the prior art, and specific examples will be described in more detail below.

[0008] The substrate to be coated can be any substrate suitable for sputter coating, such as sapphire or Si-based substrates.

[0009] Step (b) can be carried out using sputtering and thin film deposition techniques and parameters known to those skilled in the art. The ions causing sputtering can originate from known ion sources, including plasmas and particle accelerators (e.g., ion beam sputtering). The degree of ionization in the plasma can be further increased, for example, by using a cold cathode or a hot cathode (e.g., a hot filament cathode). The ions can be generated in a vacuum chamber in which a target and substrate are placed, or they can be generated in a separate chamber functionally connected to a vacuum chamber in which a metal target and substrate are placed. The sputtering ions are ions of a gaseous composition of a first atmosphere.

[0010] The metal target can be any metal target suitable for sputtering, and includes both liquid and solid metal targets. It is important to note that the terms liquid and solid do not refer to the physical state of the metal at room temperature, but rather to its physical state during the implementation of the current method (e.g., in a single step of the method), where the temperature of the metal target is adjustable. One or more metal targets can be used in the method of the present invention, for example, for co-sputtering. The metal target can be liquefied or solidified by adjusting its temperature (e.g., simultaneously with the execution of the method). Combinations of liquid and solid metal targets can be used, for example, for co-sputtering. The following is within the scope of the invention: the physical state of the metal target can be changed during the execution of the method, for example, the physical state can change with each method step, and / or the physical state can be adjusted (e.g., adjusted to solid) while positioning or repositioning the metal target (e.g., based on the position of the metal target relative to gravity) to avoid spillage or leakage of the metal target. If a liquid metal target is used, the target can be degassed before sputtering, for example, to avoid the formation of bubbles (especially those generated by filling the liquid target).

[0011] In step (b), a metal film is deposited on the surface of the substrate by sputtering metal from a metal target (which forms a metal film on the surface of the substrate) under a first atmosphere. The first atmosphere allows sputtering but, together with other process parameters such as sputtering power, sputtering duration, and / or temperature, does not, or at least substantially does not, cause chemical modification of the metal target, the metal sputtered from the metal target, and the metal deposited as a metal film on the substrate. In other words, the rate of metal accumulation on the substrate is higher than the rate at which said metal can or may undergo chemical modification. The term "at least substantially does not cause chemical modification" means that during step (b), at most trace amounts of metal react chemically with the gaseous components of the first atmosphere, for example, at most 1 mol% to 40 mol% or at most 10 mol%, 20 mol%, or 40 mol% of the atoms of the metal deposited during step (b) undergo chemical reaction. In one embodiment, these values ​​refer only to atoms deposited during step (b) and not to any atoms deposited in a previously performed step (b) or disposed on the substrate by any other means prior to step (b). Optionally, the term "at least substantially no chemical modification" means that during step (b), at most 1 mol% to 40 mol% or at most 10 mol%, 20 mol%, or 40 mol% of the surface atoms of the metal target react chemically with the gaseous components of the first atmosphere. Typically, the first atmosphere comprises an inert gas and may optionally contain other (gaseous) components in amounts such that, during method step (b), at selected process parameters (e.g., parameters detailed above and below), the chemical modification detailed above does not substantially occur. For example, the first atmosphere may consist of inert gases (e.g., Ar, Ne, Kr, and / or Xe). In alternative examples, in addition to inert gases, the first atmosphere may also include one or more (potentially) reactive gaseous components (such as, for example, N2, NH3, N2O, N2H4, methane, acetylene, propane, CO2, and / or H2S). Those skilled in the art will understand that during step (b), the process parameters are adjusted such that the optional, potentially reactive gas components in the first atmosphere do not substantially react with the metal target, the metal sputtered from the metal target, or the metal deposited as a metal film on the substrate during step (b) (the term "substantially unreactive" can include some degree of modification as described above in the context of chemical modification). Furthermore, for example, the reactive gas component can be used to reduce excess metal that may exceed optimal conditions. Such process parameters include, for example, the volume ratio of the potentially reactive gas components to the inert gas in the atmosphere, the sputtering power, the type of sputtering power (e.g., DC sputtering, including DC magnetron sputtering, pulsed DC sputtering, pulsed DC magnetron sputtering; RF sputtering; or a combination of DC and RF sputtering), the sputtering temperature, and / or the duration of step (b).

[0012] During step (b), one or more atomic monolayers of metal film may be formed, depending on the duration and process conditions that can be conventionally controlled by those skilled in the art. Step (b) may, for example, proceed until metal droplets are formed on the substrate (including this formation process). After the metal film is deposited during step (b), the surfaces of the metal film and the metal target undergo at least partial chemical modification during step (c) of this method. As used herein, the term "chemical modification" refers to a chemical reaction between at least a portion of the deposited metal film (which refers to those metal atoms deposited during the preceding step (b), optionally more than one monolayer or all of the monolayers (if more than one monolayer was deposited in the preceding step (b), optionally at least the surface of the metal film) and the surface of the metal target with other reactive gases contained in the second atmosphere. Those skilled in the art know of conditions suitable for reacting the deposited metal film and the surface of the metal target with reactive gases contained in the second atmosphere, for example, by ionizing the reactive gases (using, for example, plasma). Exemplary chemical reactions include nitriding, oxidation, carburization, and sulfidation. In the art, such chemical modifications are typically achieved through reactive sputtering, a process in which sputtered metal reacts with a reactive gas during a sputtering / deposition process. However, in the method of this invention, the sputtering / deposition process and the chemical modification process are separate. In other words, the current method comprises a two-step procedure, in which metal is sputtered and deposited in a first step (step (b)), followed by chemical modification of the metal in a second step (step (c)). Furthermore, in step (c) of this method, substantially similar to depositing a metal film, at least a portion of the surface of the metal target is chemically modified. This at least partial chemical modification of the surface of the metal target results in a reduction or even prevention of sputtering from the metal target during step (c), further facilitating the separation of the sputtering / deposition process from the chemical modification process.

[0013] It is important to note that, for ease of reading, for all aspects and embodiments disclosed herein, a chemically modified metal film (e.g., the metal film obtained from step (c) of this method) is referred to as a "chemically modified metal film." Of course, if the chemical modification of the metal film that leads to its chemical modification involves a reaction that will make the metal exhibit "non-metallic" properties (e.g., modifying Ga to GaN), the resulting chemically modified metal film may no longer possess metallic properties (e.g., GaN), but it is still referred to herein as a chemically modified metal film. In other words, the term "chemically modified metal film" simply means that the metal film has been chemically modified and does not imply that the chemically modified metal film is still a pure metal film or has metallic properties. For example, in all aspects and embodiments described herein, the chemically modified metal film on the substrate can be a semiconductor film.

[0014] In the context of this method, the term "deposited metal film that is at least partially chemically modified" means that the deposited metal film in step (b) is chemically modified to a desired degree, which may be selected by those skilled in the art, for example, based on the material properties to be obtained. Those skilled in the art also understand that if the metal film comprises more than one atomic monolayer, those atoms of the metal film deposited during the preceding step (b) that are not exposed to the reactive gas (i.e., metal atoms within the film layer or droplet) may also be chemically modified. Exemplary degrees of chemical modification include complete chemical modification of all metal atoms of the metal film deposited during the preceding step (b) to achieve the desired stoichiometry, optionally at least 60 mol%.

[0015] In the context of this method, the term "at least partially chemically modified surface of a metal target" means that the surface of a metal target is chemically modified with a reactive gas to a degree that significantly reduces sputtering of the target. For example, at least the surface regions of the metal target that were originally sputtering active (or sputtering active in step (b)) are chemically modified. This modification can be considered as "poisoning" the target. For example, "at least partially chemically modified surface of a metal target" and "significantly reduced sputtering from the target" mean that, compared to step (b), at least the entire sputtering-active surface of the target is chemically modified in step (c) and / or sputtering of the target is reduced by at least 50%, optionally at least 75% or 95%.

[0016] Step (c) can be implemented using sputtering and thin film deposition techniques and parameters known to those skilled in the art. The ions causing at least partial chemical modification of the deposited metal film and the surface of the metal target can originate from known ion sources, including plasmas and particle accelerators (e.g., ion beams). Ionization in the plasma can be further increased, for example, by using a cold cathode or a hot cathode (e.g., a hot filament cathode). The ions can be generated in a vacuum chamber in which the target and substrate are placed, or the ions can be generated in a separate chamber functionally connected to the vacuum chamber in which the target and substrate are placed. The ion source ionizes ions of a gaseous component of a second atmosphere and optionally does not have a separate gas source.

[0017] For example, when plasma is used in step (c) to generate ions in the second atmosphere, the partial chemical modification of the surface of the metal target can result in electrical insulation, which prevents current flow, and the ions in the plasma are substantially not accelerated toward the metal target. Furthermore, due to the at least partial chemical modification of the surface of the metal target, no mechanical baffle is required in this method to cover the metal target and / or substrate to avoid or reduce sputtering during chemical modification, e.g., until substantially all or at least the required amount of metal atoms on the surface of the deposited metal film are chemically modified. Therefore, in one example, this method does not involve using a mechanical baffle to cover the metal target and / or substrate, nor is it necessary to do so to avoid or reduce sputtering of the coating from the metal target and / or substrate. Optionally, the method may involve the use of a baffle, however, which is not necessary to avoid or reduce sputtering of the coating from the metal target and / or substrate, or the baffle is not activated and / or positioned (or is not always activated / positioned) (e.g., only activated / positioned once in two or more iterations of one method step) to cover the surface of the metal target and / or substrate, and / or to avoid or reduce sputtering of the coating from the metal target and / or substrate during the step of chemically modifying the deposited metal film and / or during free sputtering.

[0018] In one example, step (c) involves generating a plasma comprising a second atmosphere of reactive gas effectively approaching the surfaces of the metal film and the metal target to achieve chemical modification. For example, the power and apparatus used for sputtering in step (b) can be used for plasma generation in step (c), but the amount and type of power (i.e., these process parameters) can vary between steps (b) and (c).

[0019] The second atmosphere used in this invention comprises a reactive gas (such as, for example, N2, NH3, N2O, N2H4, methane, acetylene, propane, CO2, and / or H2S) that allows at least partial chemical modification of the surface of the deposited metal film and the metal target. The second atmosphere may also include, for example, an inert gas as defined above in the context of the first atmosphere. The volume ratio between the reactive and inert gases can be set by those skilled in the art, for example, according to process parameters such as, for example, the applied power, the type of power used for plasma generation (e.g., DC magnetron power, pulsed DC power, DC power with pulsed DC magnetron power, or RF power), temperature, and / or the duration of step (c). Depending on these process parameters, the first and second atmospheres may have the same chemical composition, and the aforementioned process parameters are used to achieve sputtering during step (b) or chemical modification during step (c).

[0020] If the first atmosphere differs from the second atmosphere, the atmosphere can be changed after step (b) and before step (c). The atmosphere change can be achieved by purging or gradual displacement of the atmosphere, for example, by adjusting the flow rates of different gases. In one example, the atmosphere change can occur seamlessly, or in the case of the plasma used for sputtering being extinguished, the atmosphere being stabilized during this process, and then the plasma being reignited to perform step (c). For example, the atmosphere in steps (b) and (c) can be generated by limiting the flow rates of the desired gases, for example, by limiting the flow rate of each gas to the range of 0 standard cubic centimeters per minute (sccm) to 150 sccm. For the purposes of this invention, the difference in gas flow rates is considered to produce a corresponding volume ratio (i.e., if the flow rate of gas A is 1 sccm and the flow rate of gas B is 50 sccm, then the volume ratio of gas A to gas B is 1:50). As an alternative to limiting the flow rates of the desired gases, gas pulses, for example, gas pulses from a gas storage tank, can also be introduced.

[0021] In this example, during steps (b) and (c), the first and second atmospheres are substantially the same near the substrate and near the metal target, respectively. In other words, the atmosphere difference in this example is not achieved by locally applying different atmospheres near the substrate and the metal target, but rather by simultaneously switching between the first and second atmospheres near the substrate and the metal target between steps (b) and (c). Therefore, in this example, both the substrate and the metal target are subjected to the same atmosphere: the first atmosphere in step (b) and the second atmosphere in step (c).

[0022] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the metal target is a liquid metal target, optionally a metal target in liquid form above about 30°C. As described above, the metal target can be liquefied or solidified by adjusting its temperature (e.g., while performing the method). For example, the metal target may be solid during steps (a), (b), and / or (c), and then liquefied after step (c) to remove at least partially chemically modified surfaces of the metal target by stirring or agitation (see below).

[0023] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or hereinafter, unless contradictory), the method is a method in which, after step (c), the method further includes step (d), in which, optionally, under a first atmosphere, at least partially, the chemically modified surface of the metal target is removed. At least partial removal of the chemically modified surface of the metal target can be achieved by free sputtering the metal target under suitable conditions known to those skilled in the art (e.g., using a first atmosphere and suitable sputtering conditions). Exemplary conditions for free sputtering include applying a concentration selected from 0.3 W / cm². 2 Up to 2.4W / cm 2 DC sputtering power density and / or 0.45 W / cm² 2 Up to 3.1 W / cm 2 RF sputtering power density.

[0024] If the target is liquid or liquefied (e.g., for the purpose of at least partially removing the chemically modified surface), stirring or agitating the liquid metal target (e.g., as an alternative to or supplement to free sputtering) can be used to partially remove the chemically modified surface of the metal target. In the context of this method, "at least partially remove" refers to the degree of removal of the chemically modified surface that is allowed to be sputtered from the metal target after the removal step. For example, "at least partially remove" means that the same degree of sputtering can be achieved after step (d) compared to step (b) performed prior to step (c), and / or means that at least 80% of the modified surface of the target is removed. If other methods (e.g., stirring or agitation) are used to at least partially remove the chemically modified surface of the metal target, it should be noted that these methods do not preclude the additional occurrence of free sputtering.

[0025] For example, it should also be noted that the method conditions in step (c) are selected such that, for the example of a liquid or liquefied target, no stirring or agitation is performed during step (c), or only a certain degree of stirring or agitation is performed, which does not significantly remove (see above) the chemically modified surface of the metal target, so that the sputtering of the target is still significantly reduced due to the chemically modified surface during step (c). For example, mechanical stirring or ultrasonic stirring can be turned off. Additionally or alternatively, during step (c), the sputtering power can be set or reduced to a level that does not cause significant agitation of the liquid metal target, so that the chemically modified surface remains intact, and the sputtering of the target is still significantly reduced during step (c). For example, the method according to the invention (which can be combined with any embodiment of the method mentioned above or below, unless contradictory) is a method in which, during step (c), the stirring of the liquid target is reduced or stopped.

[0026] In an embodiment of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the method is a method in which, after step (d), the method further includes repeating step (b) to deposit an additional metal film on the surface of the substrate by sputtering metal from a metal target in a third atmosphere, optionally a first atmosphere.

[0027] Repeating step (b) means depositing another metal film on the metal film deposited in the previous step (b). Repeating step (b) does not necessarily mean using the exact same process conditions as the previous (or subsequent) step (b). In other words, repeating step (b) can be considered as "step (b')," which requires different processing conditions, but still involves sputtering from a metal target to deposit another metal film on the previously deposited metal film on the substrate in the aforementioned step (b). Furthermore, the metal target in step (b') can be the same as or different from the metal target in step (b). The third atmosphere can be the same as or different from the first atmosphere. However, the functional limitations explained above regarding the first atmosphere also apply to the third atmosphere. For example, if a different metal target is used in step (b'), the third atmosphere can be changed compared to the first atmosphere.

[0028] For example, the repetition of step (b) (e.g., step (b')) can be performed in the same vacuum chamber as the previous step (b) or in a different vacuum chamber. Furthermore, if step (d) is performed as free sputtering, then step (d) can be performed simultaneously with the repetition of step (b), that is, step (d) is not performed before step (b) but simultaneously with it.

[0029] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless they contradict each other), the method includes repeating step (c) and optionally step (d).

[0030] In the context of this method, repeating step (c) means that an additional metal film in a subsequent step (b) (or step (b')) is chemically modified. Repeating step (c) does not necessarily mean using the exact same process conditions as a previous (or subsequent) step (c). In other words, repeating step (c) can be considered "step (c')" which requires different processing conditions but still results in at least partial chemical modification of the previously deposited metal film on the substrate and at least partial chemical modification of the surface of the metal target from the previous step (b). The second atmosphere used in repeating step (c) (or performing step (c')) may be the same as or different from the aforementioned second atmosphere. However, the functional limitations explained above regarding the second atmosphere also apply to the atmosphere used in repeating step (c) (or performing step (c')). For example, if a different metal target is used in step (b'), and / or if different chemical modifications are required to the deposited layer compared to the previous step (c), the second atmosphere can be changed compared to the previously used second atmosphere during the repetition of step (c) (or when performing step (c')).

[0031] For example, the repetition of step (c) (e.g., step (c')) can be performed in the same vacuum chamber as the previous step (c) or in a different vacuum chamber. If step (d) is repeated after step (c) is repeated (or if step (c') is performed), the definition given above for step (d) also applies to the repetition of step (d); however, at least the partial removal operation does not necessarily have to be performed in the same manner as the previous step (d) (e.g., by stirring instead of agitation or by free sputtering instead of stirring, etc.).

[0032] In an embodiment of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradicting each other), the method includes: repeating steps (b), (c), and (d) in the order of steps (b), (c), and (d) to deposit a plurality of metal films on the surface of a substrate and to chemically modify the plurality of metal films at least partially, wherein the steps are repeated 2 to 120 times; wherein step (d) is not performed after the last repetition of steps (b) and (c).

[0033] The explanation given above regarding the repetition of steps (b), (c), and (d) applies to repeating steps (b), (c), and (d) in the order of steps (b), (c), and (d).

[0034] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the thickness of the chemically modified metal film in step (c) is about 0.1 nm to 20 nm, optionally about 0.3 nm to 15 nm, optionally about 10 nm.

[0035] The thickness mentioned above refers to the thickness of the metal film after one iteration of steps (b) and (c). If steps (b), (c), and optionally (d) are repeated, a greater thickness, such as about 1 nm to about 1.5 μm, can be achieved by using multilayer metal films.

[0036] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the at least partially chemically modified metal film is an epitaxial film. The at least partially chemically modified film is the film obtained by step (c) of the method, or the film obtained by repeating steps (b), (c) and optionally repeating step (d) as described above.

[0037] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the sputtering in step (b) is: DC sputtering, optionally DC magnetron sputtering, pulsed DC sputtering or pulsed DC magnetron sputtering; RF sputtering; or a combination thereof. These conditions may also optionally apply to step (d).

[0038] As used herein, the terms “DC sputtering (...); RF sputtering; or a combination thereof” mean that DC or RF sputtering, or DC and RF sputtering, may be used.

[0039] For example, a substantially planar magnetic control system can be used, as described on pages 4 and 5 of WO 2020 / 083882 A1, the entire contents of which are incorporated herein by reference. Furthermore, the use of inductively coupled plasma (ICP) in step (b), for example, additionally or alternatively, is also within the scope of this invention.

[0040] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the sputtering power density is selected from 0.3 W / cm². 2 Up to 2.4W / cm 2 DC sputtering power density and / or 0.45 W / cm² 2 Up to 3.1 W / cm 2 RF sputtering power density.

[0041] Sputtering power density refers to the power density used for sputtering in step (b); expressed in cm⁻¹ 2The area measured in units refers to the area of ​​the surface of the metal target where metal sputtering occurs. For example, by adjusting the sputtering power and the type of sputtering power (e.g., DC, pulsed DC, optionally combined with magnetron sputtering, or RF), the reaction conditions can be controlled because the initial atmosphere containing the reactive gas will not significantly cause any chemical modification of the deposited metal film by the reactive gas.

[0042] In an embodiment of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradicting each other), the method is a method in which, in step (c), a plasma containing a reactive gas is generated between the target and the substrate, wherein the plasma containing the reactive gas is optionally a DC plasma, an RF plasma, or a mixture thereof.

[0043] Alternatively, a remote plasma (e.g., in a different vacuum chamber) can be used to generate ions of a reactive gas in a second atmosphere, which subsequently lead to at least partial chemical modification of the deposited metal film in step (c).

[0044] In an embodiment of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the method is as follows: wherein the power density used for plasma generation in step (c) is selected from 0.24 W / cm². 2 Up to 1.55W / cm 2 DC power density and / or 0.3W / cm² 2 Up to 1.55W / cm 2 RF power density.

[0045] In cm 2 The area measured in units refers to the surface area of ​​the metal target where metal sputtering occurs.

[0046] In an embodiment of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), step (d) is performed under the conditions of step (b), optionally as step (b), wherein the chemically modified surface of the metal target is at least partially removed by sputtering.

[0047] Sputtering for at least partial removal of chemically modified surfaces from metal targets is also known as free sputtering, and this sputtering can be carried out in conjunction with other methods for partial removal of chemically modified surfaces from metal targets.

[0048] In an embodiment of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), in step (d), the chemically modified surface of the liquid metal target is at least partially removed by stirring and / or agitating the liquid metal target.

[0049] As used herein, stirring or agitation means mixing liquid metal targets to the extent that the chemically modified surfaces of the liquid metal targets are at least partially removed, so that sputtering can occur from the liquid metal targets.

[0050] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless they contradict each other), stirring or agitation is carried out by mechanical stirring, ultrasonic agitation, application of a magnetic field, or a combination thereof.

[0051] Apparatus for stirring and / or agitating metal targets is disclosed in WO 2020 / 083882 A1 (the entire contents of which are incorporated herein by reference), specifically on pages 6 to 11 and 13 to 15, which includes magnetic field-based agitation (using a magnetron and / or additional agitation electrodes), ultrasonic agitation, and mechanical stirrers.

[0052] The magnetic field used for stirring can be used in conjunction with a current flowing through the liquid metal target, wherein the magnetic field is at least partially orthogonal to the current, resulting in a Lorentz force and stirring of the liquid metal target. The current can be superimposed on the sputtering voltage, or can be directly induced in the liquid metal target by the sputtering voltage, or a combination thereof, thereby generating the magnetic field via a magnetron system (e.g., also used for sputtering) or a magnetron system and an additional stirring magnet (e.g., a side magnet). Furthermore, in the sputtering process, the Lorentz force induced by the (e.g., plasma) current and magnetic field causes the liquid metal target material to move in a manner that prevents bubble formation and thus avoids the target material droplets from being ejected toward the substrate.

[0053] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless they contradict each other), a magnetic field is applied by means of a magnetic control system.

[0054] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), agitation is optionally carried out in a first atmosphere by applying a magnetic field and DC or RF plasma between the target and the substrate.

[0055] Alternatively, an agitation unit comprising an internal agitation electrode and an external agitation electrode, as disclosed on pages 14-15 of WO 2020 / 083882 A1, can be used. For Lorentz force agitation, for the purposes of this invention, it specifically includes...Figure 6 The apparatus and method described in Figures 7 and 8, and their description on pages 25 to 32 of WO 2020 / 083882 A1.

[0056] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the first and / or third atmosphere comprises at least 60 vol% of an inert gas, and / or the second atmosphere comprises at least 5 vol% of a reactive gas.

[0057] As described above, the vol% of a gas can be generated by limiting the flow rate of the corresponding gas. For the purposes of this invention, the difference in gas flow rate is considered to produce a corresponding volume ratio (i.e., if the flow rate of gas A is 40 sccm and the flow rate of gas B is 60 sccm, then the vol% of gas B is 60%).

[0058] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the first and / or third atmosphere is a gaseous atmosphere free of reactive gases, or a gaseous mixture of inert and reactive gases, wherein the volume ratio of the inert and reactive gases is less than 1:0.6 or less than 1:0.4, optionally less than 1:0.01 to about 1:0.6 or less than 1:0.01 to about 1:0.6; and / or The second atmosphere is a gaseous atmosphere composed of reactive gases, or a gaseous mixture of inert and reactive gases, wherein the volume ratio of the inert and reactive gases is about 1:0.6 or more, optionally about 1:0.6 to about 1:8, optionally about 1:3 to about 1:4.

[0059] A gas mixture of inert gas and reactive gas with a volume ratio of approximately 1:0.6 refers to a gas mixture where the ratio of inert gas to reactive gas is 1:0.6, wherein the gas ratio can be achieved by limiting the flow rates of the respective gases. For the purposes of this invention, the difference in gas flow rates is considered to produce the corresponding volume ratio (i.e., if the flow rate of the inert gas is 10 sccm and the flow rate of the reactive gas is 6 sccm, then the ratio of inert gas to reactive gas is 1:0.6).

[0060] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the inert gas is selected from the group consisting of Ar, Ne, Kr and Xe; and / or the reactive gas is a nitrogen-containing gas (optionally selected from the group consisting of N2, NH3, N2O and N2H4), or a gas selected from the group consisting of methane, acetylene, propane, O2, CO2 and H2S.

[0061] Inert gases, nitrogen-containing gases, and mixtures of methane, acetylene, propane, O2, CO2, and H2S are within the scope of this invention.

[0062] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless they contradict each other), the chemical modification is nitriding or oxidation.

[0063] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the chemical modification is nitriding; the reactive gas is a nitrogen-containing gas (optionally selected from the group consisting of N2, NH3 and N2H4).

[0064] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the metal target is a liquid metal target, wherein the liquid metal target is liquid metal, or an alloy formed of at least two metals, the melting point of which is below about 300°C, optionally below about 70°C, optionally below about 40°C.

[0065] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the metal target is a liquid metal target selected from the group consisting of: Ga, GaAs, GaIn, GaAl, InAl, TiGa, Hg, HgAg, HgAu, HgCu, HgIn, HgSn, and HgZn. Mixtures of these metals and alloys are included within the scope of the invention.

[0066] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), step (b) is performed for approximately 1 second to approximately 60 seconds, optionally approximately 3 seconds to approximately 15 seconds; and / or The execution time of step (c) is approximately 2 seconds to approximately 80 seconds, optionally approximately 5 seconds to approximately 35 seconds.

[0067] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), there is no interruption between steps (b) and (c) or an interruption of about 0.1 seconds to about 10 seconds, and / or there is no interruption between steps (c) and (b) (including step (d)) or an interruption of about 0.1 seconds to about 20 seconds. Process parameters (including atmosphere) may be changed during the interruption, or they may be changed seamlessly without interruption.

[0068] If plasma is generated during steps (b), (c), and / or (d), the plasma can be shut off during any optional interruption between steps.

[0069] In an embodiment of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), in step (b) and / or (c), the substrate is heated from a temperature of about room temperature to about 900°C, optionally from about 500°C to about 900°C, optionally from about 650°C to about 850°C.

[0070] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless they contradict each other), the substrate is selected from the group consisting of: sapphire, a substrate having a GaN surface, a substrate having an AlN surface, a substrate having an AlGaN surface, a substrate having an AlScN surface, a substrate having a Si surface, and a substrate having a SiC surface.

[0071] In embodiments of the method according to the invention (which may be combined with any embodiment of the method mentioned above or below, unless contradictory), the method further includes: doping a metal film (particularly a metal film composed of Ga and / or GaN) on the surface of a substrate with a dopant selected from the group consisting of: O, O2, Zr, Ti, F, Ge, germane (GeH4), isobutylgermane ((CH3)2CHCH2GeH3), Nb, S, Se, Mg, cyclopentadienylmagnesium (Cp2Mg), Be, Ca, Zn, Mn, Cd, C, and Fe.

[0072] In the context of this method, metal film doping is a step distinct from the step of at least partially chemically modifying the metal film. Methods for doping are known in the context of thin film deposition and sputtering, and suitable methods for introducing dopant into metal films can be conventionally applied by those skilled in the art. For example, doping can be performed in steps (b) and optionally (d) of this method (e.g., by co-sputtering from a suitable target). For other doping methods, such as introducing a dopant gas or by evaporating or sputtering the dopant from a separate source, doping can be performed in any of steps (b), (c), and / or (d), or in additional steps, such as after steps (b) or (c). If the dopant is a gas, it can be introduced as part of a first, second, and / or third atmosphere.

[0073] In an embodiment of the method according to the invention (which may be combined with any method embodiment mentioned above or below, unless contradictory), the method further includes: doping Si in a metal film on the surface by: Optionally, this is carried out in steps (b), (c), and / or (d) by introducing silane gas, SiH compound, SiH2Cl2 compound, SiHCl3 compound, SiH3Cl compound, SiCl4 compound, or a combination thereof; Si is thermally evaporated, optionally in steps (b), (c), and / or (d); and / or Sputtering from a Si-containing target, optionally in steps (b), (c) and / or (d), optionally involves placing the solid silicon component above the liquid metal target.

[0074] In the context of this method, doping (particularly Si doping) may be performed in one of the method steps (b), (c), and / or (d), or in an independent step between any of the foregoing steps of this method. Those skilled in the art can conventionally determine the appropriate time point or method step for doping, for example, depending on the type of dopant and the doping method (gaseous dopant, doping by evaporation or (co)sputtering).

[0075] On the other hand (which may be combined with any embodiment or aspect mentioned above or below, unless contradicting each other), the present invention relates to a substrate whose surface is coated with a chemically modified metal film obtained or obtainable by the methods disclosed herein, optionally coated with a metal nitride film, optionally wherein the thickness of the film is from about 1 nm to about 1.5 μm.

[0076] As explained in the context of this method, the chemically modified metal film on the surface of the substrate may comprise one or more layers of chemically modified metal films (each layer may vary in thickness, metal type, and type of chemical modification), wherein these layers are the result of repeating the method steps described above. For example, the chemically modified metal film is a semiconductor film.

[0077] According to another aspect (which may be combined with any embodiment or aspect mentioned above or below, unless contradictory), the present invention relates to a substrate whose surface is coated with a chemically modified metal film obtained or obtainable by the methods disclosed herein, optionally coated with a metal nitride film, wherein the resistivity of the film is at least 1000 Ωcm. The film with a resistivity of at least 1000 Ωcm is an undoped chemically modified metal film obtained by the method according to the invention, optionally a chemically modified metal film substantially free of Si, i.e., a film obtained or obtainable by the method of the invention, the method not including the step of doping the (chemically modified) metal film. As stated above, for ease of reading, the chemically modified metal film (e.g., the metal film obtained according to step (c) of the method) is referred to as a "chemically modified metal film". Specifically, when a substrate is coated with a chemically modified metal film with a resistivity of at least 1000 Ωcm, the chemical modification of the metal film makes the metal exhibit "non-metallic" properties. For example, Ga is modified to GaN, and the resulting chemically modified metal film no longer has metallic properties (e.g., GaN), but is still referred to herein as a chemically modified metal film. For example, the chemically modified metal film with a resistivity of at least 1000 Ωcm on the substrate can be a semiconductor film.

[0078] According to another aspect (which may be combined with any embodiment or aspect mentioned above or below, unless contradictory), the present invention relates to a substrate whose surface is coated with a chemically modified metal film obtained or available by the methods disclosed herein, optionally coated with a metal nitride film, wherein the resistivity of the film is less than about 10000 µΩcm, optionally less than 5000 µΩcm, optionally less than 1000 µΩcm, optionally less than 650 µΩcm, optionally less than 600 µΩcm, optionally less than 580 µΩcm. Films with resistivity less than about 10000 µΩcm are doped metal films (optionally metal films comprising Si) obtained by the methods according to the invention, i.e., films obtained or available by the methods according to the invention including the step of a doped metal film.

[0079] On the other hand (which may be combined with any embodiment or aspect mentioned above or below, unless contradictory), the present invention relates to an apparatus configured to perform the methods disclosed herein, wherein the apparatus includes a vacuum sputtering chamber comprising: -Substrate holder, - A container for receiving a metal target, optionally a liquid metal target. The container can be connected to or can be connected to a power source. - Vacuum port; and -Gas inlet, The device further includes a control unit configured to control and execute the steps described herein.

[0080] The apparatus of the present invention may be, for example, any known coating apparatus suitable for coating thin films by sputtering, which can be used in the context of this method for sputtering solid or liquid targets. Furthermore, the apparatus of the present invention includes a control unit configured (e.g., programmed by a computer program) to perform the method steps of this method.

[0081] In the device embodiments according to the invention (which may be combined with any device embodiments mentioned above or below, unless contradictory), the container is connected to or can be connected to the cathode of a DC power supply, the cathode of a pulsed DC power supply, an RF power supply, or a power supply providing a combination of DC power, pulsed DC power, and / or RF power.

[0082] The apparatus of the present invention may be the apparatus disclosed in WO 2020 / 083882 A1, the entire contents of which are incorporated herein by reference. Those skilled in the art will find that modifying the apparatus disclosed therein to also (or alternatively) adapt to solid metal targets is not difficult. However, by way of example only, the apparatus of the present invention and / or the apparatus used in the method does not include a baffle for covering the surface of the metal target and / or substrate, and / or for preventing or reducing sputtering of the coating from the metal target and / or substrate during the step of chemically modifying the deposited metal film and / or during free sputtering. Alternatively, the apparatus of the present invention and / or the apparatus used in the method may include a baffle, however, which is not activated and / or positioned to cover the surface of the metal target and / or substrate, and / or to prevent or reduce sputtering of the coating from the metal target and / or substrate during the step of chemically modifying the deposited metal film and / or during free sputtering, wherein, for example, a control unit controls the deactivation and / or positioning of the baffle.

[0083] The container for receiving the metal target (optionally, a liquid metal target) is shaped according to the properties of the metal target. For example, if a liquid target is used, the container can be a trough that is at least partially recessed in the peripheral region to compensate for the high surface tension of the liquid metal, thereby centering the liquid material and creating a large, flat target area. Alternatively, the bottom of the trough can be at least partially convex in the peripheral region to provide more material in the sputtering active region.

[0084] Furthermore, the device may include means for heating and / or cooling the metal target (e.g., changing its physical state from liquid to solid and vice versa). Such means may include a cooling and / or heating circulation system within a container (e.g., a tank), or a heating / cooling plate thermally connected to a container (e.g., a tank). Alternatively, heating may be provided by a radiant lamp or other radiant device (e.g., a carbon heater), by plasma, or by electron bombardment of the surface of the metal target.

[0085] In embodiments of the device according to the invention (which may be combined with any embodiment of the device mentioned above or below, unless contradictory), the substrate holder is connected to or may be connected to ground or a power supply, optionally a floating power supply.

[0086] The power supply that can be connected to or is connected to the substrate holder can be a DC or RF power supply.

[0087] In embodiments of the device according to the invention (which may be combined with any embodiment of the device mentioned above or below, unless contradictory), the device further includes an anode electrically isolated from the container, wherein the anode is optionally positioned circumferentially around the container and / or positioned in the central region of the container.

[0088] In embodiments of the device according to the invention (which may be combined with any embodiment of the device mentioned above or below, unless contradictory), the device includes means for stirring and / or agitating the liquid metal target in the container.

[0089] The apparatus for stirring or agitation may be those disclosed in WO 2020 / 083882 A1 (the entire contents of which are incorporated herein by reference), for example, those disclosed on pages 7 to 11.

[0090] In an embodiment of the device according to the invention (which may be combined with any embodiment of the device mentioned above or below, unless contradictory), the device includes a magnetic control system positioned on the side of the container opposite to the side that can receive a metal target (optionally, a liquid metal target).

[0091] In embodiments of the device according to the invention (which may be combined with any embodiment of the device mentioned above or below, unless contradictory), the magnetron system is configured to generate a magnetic field that has an axisymmetric or non-axisymmetric geometry relative to the axis perpendicular to the surface of the metal target in the container. Attached Figure Description

[0092] The embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. These descriptions are for illustrative purposes only and should not be construed as limiting.

[0093] Figures 1 to 3 A flowchart of an exemplary method according to the present invention is shown.

[0094] Figures 4 to 6 An exemplary device according to the present invention is shown. Detailed Implementation

[0095] Figure 1 A flowchart of an exemplary method according to the invention is shown, comprising one iteration of steps (b) and (c) and optionally including step (d). After providing the substrate and metal target in step (a), step (b) is performed (arrow I), followed by step (c) (arrow II). After the deposited metal film and the surface of the metal target are at least partially chemically modified with a reactive gas in a second atmosphere in step (c), the method can be terminated (arrow IIIa), and the coated substrate can be removed from the vacuum chamber. After step (c), the coated substrate can also be further processed (e.g., plasma etching or doping of the metal film) in the same or different vacuum chambers. Optionally, after step (c), step (d) (arrow IIIb) can be performed, and then the method can be terminated (arrow IV) to obtain a product (coated substrate) substantially the same as described with respect to arrow IIIa, including the possibility of further processing as described above.

[0096] Figure 2A flowchart of an exemplary method according to the present invention is shown, including at least one repetition of steps (b) and (c) and including step (d) as a separate step. Steps (a), (b), (c), and (d) are performed in the order of steps (a), (b), (c), and (d) (arrows I, II, and III). After step (d), step (b) is repeated under the same conditions as the previous step (b) or under different conditions (i.e., as disclosed above in step (b')), for example, including a third atmosphere different from the first atmosphere, a different metal target, and / or different sputtering power and power type. Thus, the same or different metal films can be deposited on previously deposited and chemically modified metal films. After repeating step (b), the method can be terminated without further chemical modification (chemical modification of the layer previously deposited in the first step (b)) (arrow Va), or step (c) can be repeated under the same or different conditions used in the first iteration of step (c) (arrow Vb). The repetition of step (c) can be considered as "step (c')," which requires different processing conditions but still results in at least partial chemical modification of the previously deposited metal film on the substrate and the surface of the metal target corresponding to the previous step (b). The second atmosphere used in repeating step (c) (or performing step (c')) can be the same as or different from the aforementioned second atmosphere. However, the functional limitations explained above regarding the second atmosphere also apply to the atmosphere used in repeating step (c) (or performing step (c')). For example, if a different metal target is used in step (b'), and / or if different chemical modifications are required on the deposited layer compared to the previous step (c), the second atmosphere used in repeating step (c) (or performing step (c')) can be changed compared to the previously used second atmosphere. After repeating step (c), the method can be terminated (arrow VIa). Optionally, step (d) (arrow VIb) can be repeated, optionally followed by subsequent steps (b) and / or (c). The explanation given above for the first repetition of steps (b) and (c) applies to the second and subsequent repetitions of these steps. By repeating steps (b) and / or (c) (and optional step (d)), additional layers of the (chemically modified) metal target are added to the layers obtained from the previous steps (b) and / or (c). Essentially, these steps can be repeated as needed, for example, until a certain film thickness or number of layers is achieved.

[0097] Figure 3A flowchart of an exemplary method according to the present invention is shown, comprising at least one repetition of steps (b) and (c), wherein step (d) is a part of step (b). For example, at least partial removal of the chemically modified surface of a metal target can be achieved in step (b) by free sputtering the metal target under appropriate conditions; and sputtering deposition occurs substantially simultaneously once at least a portion of the chemically modified surface of the metal target is available for sputtering. Exemplary conditions have been provided above, and are for... Figure 2 The interpretations made, after necessary modifications, also apply. Figure 3 .

[0098] Figure 4An exemplary apparatus according to the invention for carrying out the method of the invention is shown. The apparatus (1) includes a vacuum sputtering chamber (2) and a substrate holder (3) located within the vacuum sputtering chamber (which may optionally include means (16) for heating and / or cooling) and a container for receiving a metal target in liquid or solid form. The container may also include or be connected to heating and / or cooling means (not shown). The substrate holder (3) is configured to hold the substrate on a surface facing the container (4), and the container is configured to receive the metal target such that the metal target faces the substrate holder (3). The vacuum sputtering chamber (2) also includes a vacuum port (6) and a gas inlet (7), which (each or only one of the vacuum port (6) and the gas inlet (7)) may optionally include regulating valves (10) for regulating the gas flow rate and vacuum, respectively. The gas inlet is used to establish a first atmosphere, a second atmosphere, and optionally a third atmosphere in the vacuum chamber. The container is connected to or may be connected to a sputtering power source (5). The power source can be a cathode of a DC power source, a cathode of a pulsed DC power source, an RF power source, or a power source providing a combination of DC, pulsed DC, and / or RF power. Plasma (9) can be generated between the metal target on the container (4) and the substrate on the substrate holder (3). A magnetron control system (17) is typically used, and for all embodiments and figures disclosed herein, the magnetron control system (17) can be located outside the vacuum chamber and can include symmetrical or asymmetrical magnetron control systems. Typically, the magnetron control system is stationary and the container is configured to be rotatable. Optionally, the magnetron control system can be rotatable, and / or the container can be stationary. The apparatus also includes a control unit (8) for performing the method of the invention. The control unit is detachable from the apparatus and the vacuum sputtering chamber and is located outside the apparatus and the vacuum sputtering chamber. The control unit is connected, at least during operation of the method, to relevant components on the apparatus used to determine the parameters and steps of the method (such as an inlet valve or any other suitable gas control device, sputtering power source) and optionally to means for heating and cooling the substrate and / or the container. The vacuum chamber also includes a substrate port (not shown), which can be a load lock for a standalone system or a multi-chamber system operating at different pressure levels between a continuous process chamber and a transfer chamber. Exemplary devices of the present invention do not include mechanical baffles for covering the metal target and / or the target and for preventing or reducing sputtering from the metal target / substrate coating. Alternatively, devices of the present invention and / or devices used in the method may include baffles, however, which are not activated and / or positioned to cover the metal target and / or substrate surface, and / or to prevent or reduce sputtering from the metal target and / or substrate coating during the step of chemically modifying the deposited metal film and / or during free sputtering, wherein, for example, a control unit controls the deactivation and / or positioning of the baffle.

[0099] Figure 5 It shows that according to Figure 4 An exemplary device, which further includes the following components: A power supply (11) is connected to or can be connected to a substrate holder that forms conductive contact with the substrate to be inserted during the implementation of this method (the substrate holder may optionally include means for heating and / or cooling). The power supply (11) may alternatively be a grounded, DC or RF power supply or a floating power supply. An optional grounded anode (13) may be included, which is electrically isolated from the container (4) (and its power supply (5)) and may optionally be circumferentially positioned around the container. The circumferential positioning of the anode may enable the anode to serve as an external electrode for stirring a liquid metal target, while the container may act as an internal electrode. An optional anode shield (14) may be installed in a manner electrically isolated from the container at a darkroom distance, depending on the applied process pressure. The vacuum sputtering chamber also includes a magnet (12) disposed within a substantially planar magnetron system located on the opposite side of the container (4) or, for example, embedded in the opposite side of the container (4), or located at / in the bottom of the container (4) (e.g., below the liquid level of the liquid metal target). To generate a magnetic field, the magnetron system includes an external closed magnetic loop with a magnetic axis M... A The outer closed magnetic loop is positioned substantially perpendicular to the target surface and surrounds an inner magnet of opposite polarity, which is arranged in the central region of the target with its magnetic axis M. A The orientation is vertical. It should be noted that the polar orientation shown can be reversed. It should also be mentioned that the external magnet can be arranged with a slightly tilted magnetic axis M. A The magnetic axis is tilted toward or away from the central vertical axis (e.g., at an angle between 5° and 15°) to further design the overall magnetic field. The external magnet can be, for example, a toroidal magnet or smaller magnets arranged separately. If more than one internal magnet is used, the internal magnets can be arranged linearly; they can also be arranged again as closed loops (e.g., containing linear and / or curved sections) for rectangular or other elongated targets; or the internal magnets can be arranged as a central pole for square or circular targets; all these types of magnetic axes are substantially parallel, but their polarity is opposite to the magnetic axis M of the external magnet loop. A Conversely, the magnetic field of the magnetron interacts with the current flowing through the liquid metal target to generate a Lorentz force, thereby agitating the liquid metal target. Alternative methods of agitation are not shown in the figures, but may be included, for example, as disclosed in WO 2020 / 083882 A1, the entire contents of which are incorporated herein by reference. In this example, at least during the operation of the method, the control unit (8) is also connected to the power supply (11).

[0100] Figure 6 It shows that according to Figure 5An exemplary device wherein the container (4) includes a liquid metal target (15).

[0101] List of reference numerals in the attached diagram: 1 Equipment 2 Vacuum sputtering chamber 3. Substrate Holder 4 containers 5 Sputtering power supply 6 Vacuum ports 7 Gas Inlet 8 Control Unit 9. Plasma 10. Control valve 11 Power Supply 12 Magnets for magnetic control systems 13 Anode 14 Shielding components 15 Liquid metal target 16 Cooling / Heating Device 17. Magnetic Control System Examples of the present invention Embodiments of this method will be described in more detail in the following examples, wherein each example shall not be construed as limiting the scope of the invention.

[0102] In the following example, the coating equipment described above can be used, specifically a coating equipment commercially available from Evatec AG, such as the CLN200. In this equipment, the cathode consists of a container filled with liquid Ga. It can be supplied with DC and RF (13.56MHz) voltages by two independent generators. The anode can be arranged as needed, for example, as a grounded shield used as the anode. The magnetron is circular and slightly unbalanced, allowing the plasma to extend more towards the substrate.

[0103] Example 1 - General Process 1 In step (a), a substrate is provided, for example, in a device according to the invention or in a commercial device (e.g., the aforementioned device from Evatec AG), wherein the substrate is, for example, sapphire or a silicon wafer. Exemplary substrate sizes include substrates from 2 to 12 inches. The metal target is, for example, a liquid metal target or a Ga-containing target. Exemplary target sizes include diameters from 200 mm to 340 mm and 300 cm² for liquid targets. 3 Up to 10000cm 3 The volume. For step (b), apply 0.3 W / cm. 2 (Target area) up to 2.4W / cm² 2 DC power and / or 0.24W / cm 2 Up to 1.55W / cm2 The RF power is adjusted to generate a first atmosphere plasma between the target and the substrate at a substrate temperature of approximately 500°C to 900°C. The first atmosphere comprises an inert gas, for example, an inert gas of approximately 40 vol% or more, or 60 vol% or more. Depending on the desired layer thickness, a metal film is deposited on the substrate by sputtering, for example, over a period of approximately 1 s to 50 s. For step (c), the power is set to no DC power or 0.24 W / cm², regardless of interruption. 2 Up to 1.55W / cm 2 DC power, and / or set the power to no RF power or 0.3W / cm². 2 Up to 1.55W / cm 2 The RF power (target area) is applied, and the atmosphere is changed to a second atmosphere to generate a reactive gas plasma of the second atmosphere between the target and the substrate. If the process is interrupted between steps (b) and (c) (e.g., interrupted for about 1 to 15 seconds), the plasma can be shut off during that time. If there is no interruption, the atmosphere can be gradually changed. The second atmosphere optionally comprises at least 5 vol% of a reactive gas (optionally selected from N2, NH3, N2O, and N2H4) and may optionally correspond to the first atmosphere. During step (c), the substrate temperature is about 500°C to 900°C, and step (c) can be performed for about 1 to 50 seconds, depending on the rate and the desired degree of chemical modification. After step (c), an interruption or non-interruption as described above may occur, and optional step (d) may be performed. If step (d) is performed solely as a free sputtering of the surface of the metal target, then step (d) can be achieved by performing step (b), either as a separate step before repeating step (b), or not as a separate step but during the repeating of step (b) after step (c), wherein selected conditions are sufficient to allow free sputtering of at least the active surface region of the metal target used for sputtering. Additionally or alternatively, step (d) can be performed alone (e.g., by stirring and / or agitating the liquid metal target). Thereafter, steps (b) and (c), and optionally step (d), are repeated until the desired thickness (i.e., number of layers) of the deposited metal film is achieved.

[0104] Example 2 - General Process 2 In step (a), a substrate is provided, for example, in a device according to the invention or in a commercial device (e.g., the aforementioned device from Evatec AG), wherein the substrate is, for example, sapphire or a silicon wafer. Exemplary substrate sizes include substrates ranging from 2 to 6 inches. The metal target is a liquid metal target, optionally a liquid Ga target. Exemplary target sizes include 310 cm². 2 The area and depth are 1cm to 3cm. For step (b), apply 0.3W / cm.2 (Target area) up to 2.4W / cm² 2 DC power and 0.24W / cm 2 Up to 1.55W / cm 2 The RF power is used to generate a first atmosphere plasma between the target and the substrate at a substrate temperature of approximately 500°C to 900°C. The first atmosphere comprises an inert gas of approximately 40 vol% or more. For example, a gas flow rate of 25 sccm to 35 sccm of inert gas and 8 sccm to 15 sccm of reactive gas can be used to generate the first atmosphere. Depending on the desired layer thickness, a metal film is deposited on the substrate by sputtering, for example, over a period of approximately 1 s to 30 s. Regardless of interruption, for step (c), the power is set to: (I) no DC power and 0.3 W / cm 2 Up to 1.55W / cm 2 RF power, or (II) 0.24 W / cm 2 Up to 1.55W / cm 2 The DC power and no RF power (target area) are used. The first atmosphere is changed to a second atmosphere to generate a reactive gas plasma of the second atmosphere between the target and the substrate. If the process is interrupted between steps (b) and (c) (e.g., interrupted for about 1 to 15 seconds), the plasma can be shut off during that time. If there is no interruption, the atmosphere can be changed gradually. The second atmosphere optionally includes at least 5 vol% of a reactive gas (optionally selected from N2 and NH3) and can optionally correspond to the first atmosphere. For example, a gas flow rate of 0 sccm to 26 sccm of inert gas and 14 sccm to 45 sccm of reactive gas can be used to generate the first atmosphere. During step (c), the substrate temperature is about 500°C to 900°C, and step (c) can be performed for about 1 to 40 seconds, depending on the rate and the desired degree of chemical modification. After step (c), an interruption or non-interruption as described above can occur, and optional step (d) can be performed. If step (d) is performed solely as a free sputtering of the surface of the metal target, then step (d) can be achieved by performing step (b), either as a separate step before repeating step (b), or not as a separate step but during the repeating of step (b) after step (c), wherein selected conditions are sufficient to allow free sputtering of at least the active surface region of the metal target used for sputtering. Additionally or alternatively, step (d) can be performed alone (e.g., by stirring and / or agitating the liquid metal target). Thereafter, steps (b) and (c), and optionally step (d), are repeated until the desired thickness (i.e., number of layers) of the deposited metal film is achieved.

[0105] Example 3 - Deposition Example 1 In step (a), a single-sided polished sapphire substrate is provided in the aforementioned equipment from Evatec AG. The substrate size is 2 inches. The metal target has an area of ​​314 cm². 2 A liquid Ga target with a depth of 1.5 cm was used. In step (b), a DC power of 300 W and an RF power of 500 W were applied to generate a first atmosphere plasma between the target and the substrate at a substrate temperature of approximately 800 °C. The first atmosphere was provided by a gas flow rate of 30 sccm of Ar and 10 sccm of N2. Sputtering was performed for 5 s to obtain a metal film with a thickness of approximately 10 nm. After step (b) and without interruption (plasma on), the first atmosphere was changed to a second atmosphere by changing the gas flow rate to 5 sccm of Ar and 35 sccm of N2. The power was changed to 0 W of DC power and 500 W of RF power to maintain the second atmosphere plasma between the target and the substrate at a substrate temperature of approximately 800 °C. Step (c) was performed for 12 s to obtain more than 95% chemical modification. Subsequently, the plasma was turned off for 3 s, the atmosphere was changed back to the first atmosphere as described above, and step (b) was repeated as described above, followed by step (c). The cycles of steps (b) and (c) were repeated a total of 97 times to obtain a thickness of 1000 nm and a conductivity of 618 Ωcm.

[0106] Example 4 - Deposition Example 2 In step (a), a single-sided polished sapphire is provided in the aforementioned equipment from Evatec AG. The substrate size is 2 inches. The metal target has an area of ​​314 cm². 2 A liquid Ga target with a depth of 1.5 cm was used. In step (b), a DC power of 300 W and an RF power of 300 W were applied to generate a first atmosphere plasma between the target and the substrate at a substrate temperature of approximately 700 °C. The first atmosphere was obtained by using Ar with a gas flow rate of 32 sccm and N2 with a flow rate of 8 sccm. Sputtering was performed for 5 s to obtain a metal film of approximately 15 nm. After step (b), the plasma was interrupted for 5 s (plasma off), during which the first atmosphere was changed to a second atmosphere by first changing the gas flow rate to 5 sccm of Ar and 35 sccm of N2 and then to 0 sccm of Ar and 40 sccm of N2. The power was set to a DC power of 300 W and an RF power of 0 W to obtain a second atmosphere plasma between the target and the substrate at a substrate temperature of approximately 700 °C. Step (c) was performed for 10 s to obtain a chemical modification of more than 95%. Subsequently, the plasma was turned off for 5 s, the atmosphere was changed to the first atmosphere as described above, and step (b) was repeated as described above, followed by step (c). The cycles of steps (b) and (c) were repeated a total of 64 times to obtain a thickness of 990 nm.

[0107] Example 5 - Deposition Example 3 In step (a), an Al2O3 substrate is provided in the aforementioned equipment from Evatec AG. The substrate size is 2 inches. The metal target has an area of ​​314 cm². 2 A liquid Ga target with a depth of 1.5 cm was used. In step (b), a DC power of 500 W and an RF power of 500 W were applied to generate a first atmosphere plasma between the target and the substrate at a substrate temperature of approximately 700 °C. The first atmosphere was obtained by using Ar at a gas flow rate of 25.5 sccm and N2 at 14.5 sccm. Sputtering was performed for 10 s to obtain a metal film of approximately 18 nm. After step (b), the first atmosphere was replaced with a second atmosphere (the gas flow rate was maintained at 25.5 sccm for Ar and 14.5 sccm for N2) without interruption (plasma on). The power was changed to 0 W of DC power and 500 W of RF power to maintain the second atmosphere plasma between the target and the substrate at a substrate temperature of approximately 700 °C. Step (c) was performed for 10 s to obtain more than 90% chemical modification. Subsequently, all under the same gas flow conditions, without interruption (plasma on), step (b) was repeated as described above, followed by step (c). The cycles of steps (b) and (c) were repeated a total of 40 times to obtain a thickness of 750 nm and an improved surface roughness (Rq approximately 7 nm) compared to existing methods (Rq approximately 30 nm).

Claims

1. A method for depositing a chemically modified metal film on a substrate, wherein, The method includes the following steps: (a) Providing a substrate and a metal target in a vacuum chamber; (b) Depositing a metal film on the surface of the substrate by sputtering metal from the metal target under a first atmosphere; and (c) Under a second atmosphere, the deposited metal film and the surface of the metal target are at least partially chemically modified using a reactive gas. Optionally, the first atmosphere is an atmosphere comprising at least 40 vol% inert gas; and The second atmosphere is an atmosphere that includes the reactive gas.

2. The method according to claim 1, wherein, The metal target is a liquid metal target, optionally a metal target that is in a liquid state at a temperature above about 30°C.

3. The method according to claim 1 or 2, wherein, Following step (c), the method further includes step (d), in which, optionally, the chemically modified surface of the metal target is at least partially removed under the first atmosphere.

4. The method according to claim 3, wherein, After step (d), the method further includes repeating step (b) to deposit an additional metal film on the surface of the substrate by sputtering the metal from the metal target in a third atmosphere, optionally the first atmosphere.

5. The method according to claim 4, wherein, The method includes repeating step (c) and optionally repeating step (d).

6. The method according to claim 5, wherein, The method includes: repeating steps (b), (c), and (d) in the order of steps (b), (c), and (d) to deposit a plurality of metal films on the surface of the substrate and to chemically modify the plurality of metal films at least partially, optionally wherein these steps are repeated 2 to 120 times; optionally wherein step (d) is not performed after the last repetition of steps (b) and (c).

7. The method according to any one of claims 3 to 6, wherein, Step (d) is performed under the conditions of step (b), optionally as step (b), and wherein the chemically modified surface of the metal target is at least partially removed by sputtering.

8. The method according to any one of claims 3 to 6, wherein, In step (d), the chemically modified surface of the liquid metal target is at least partially removed by stirring and / or agitating the liquid metal target.

9. The method according to any one of claims 1 to 8, wherein, Chemical modification is achieved through nitriding or oxidation.

10. The method according to any one of claims 1 to 9, wherein, The method further includes doping the metal film on the surface of the substrate with a dopant selected from the group consisting of: O, O2, Zr, Ti, F, Ge, germane (GeH4), isobutylgermane ((CH3)2CHCH2GeH3), Nb, S, Se, Mg, cyclopentadienylmagnesium (Cp2Mg), Be, Ca, Zn, Mn, Cd, C, and Fe.

11. The method according to any one of claims 1 to 10, wherein, The method further includes doping Si into the metal film on the surface by: By introducing silane gas, SiH compounds, SiH2Cl2 compounds, SiHCl3 compounds, SiH3Cl compounds, SiCl4 compounds, or combinations thereof; Si is obtained by thermal evaporation; and / or Sputtering is performed from a Si-containing target, optionally by placing the solid silicon component above a liquid metal target.

12. A substrate having a surface coated with a chemically modified metal film obtained or obtainable by any one of claims 1 to 11, optionally coated with a metal nitride film, optionally wherein the thickness of the film is from about 1 nm to about 1.5 µm.

13. A substrate, the surface of which is coated with a chemically modified metal film obtained or obtainable by any one of claims 1 to 9, optionally coated with a metal nitride film, wherein, The resistivity of the membrane is at least 1000 Ωcm.

14. A substrate, the surface of which is coated with a chemically modified metal film obtained or obtainable by the method according to claim 10 or 11, optionally coated with a metal nitride film, wherein, The resistivity of the film is approximately 10000 μΩcm or less, optionally approximately 5000 μΩcm or less, optionally approximately 1000 μΩcm or less, optionally approximately 650 μΩcm or less, optionally approximately 600 μΩcm or less, optionally approximately 580 μΩcm or less.

15. An apparatus (1) configured to perform the method according to any one of claims 1 to 11, wherein, The device includes a vacuum sputtering chamber (2), which comprises: - Substrate holder (3). - Container (4), which is used to receive metal targets, optionally liquid metal targets, The container (4) is connected to or can be connected to a power source (5). -Vacuum port (6); and -Gas inlet (7). The device further includes a control unit (8) configured to control and execute the steps according to any one of claims 1 to 11.

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