Method and apparatus for depositing a material on a substrate by magnetron sputtering

Abstract

The invention relates to a method and an apparatus for depositing a material on a substrate by magnetron sputtering. The method involves providing an apparatus for magnetron sputtering, which contains at least one vacuum chamber, an electrical voltage source and a magnetron electrically conductively connected to the electrical voltage source. In the vacuum chamber, a crucible is provided which contains, in an interior, a solid material having a melting point which is lower than a melting point of the crucible, wherein the crucible is secured to the magnetron by way of a thermally insulating spacer. Furthermore, a substrate is provided in the vacuum chamber, the vacuum chamber is evacuated and the magnetron is supplied with an electrical power which is high enough to heat the solid material in the interior of the crucible to a temperature above the melting point of the solid material.

Description

[0001] Method and system for depositing a material onto a substrate via magnetron sputtering

[0002] A method and apparatus for depositing a material onto a substrate via magnetron sputtering are provided. The method includes a magnetron sputtering apparatus comprising at least a vacuum chamber, an electrical voltage source, and a magnetron electrically connected to the voltage source. A crucible containing a solid material with a melting point lower than that of the crucible is placed in the vacuum chamber. The crucible is mounted to the magnetron via a thermally insulating spacer. A substrate is placed in the vacuum chamber, which is then evacuated. The magnetron is supplied with sufficient electrical power to heat the solid material in the crucible to a temperature above its melting point.Various methods for producing layers from a material with a low melting point (e.g. lithium) are known in the prior art.

[0003] It is known to produce thin metallic layers (e.g., lithium layers) via vacuum deposition, for example using the PVD (Physical Vapor Deposition) process. Processing in a vacuum has the advantage that precise thin-film deposition can take place in a potentially inert environment.

[0004] Furthermore, cathode sputtering, a special form of PVD process also known as sputtering, is known in the prior art. This process is based on the atomic erosion of a surface in a vacuum, resulting from the bombardment of high-energy ions or atoms. In so-called magnetron sputtering, a magnetic field is also introduced into the vacuum, which improves the homogeneity of the layer deposition. However, the deposition rates in magnetron sputtering are limited and, depending on the given parameters and materials, typically range between 1 and 10 nm / s. Consequently, when depositing several micrometers of material, the process time is too long for many industrial applications.

[0005] It is known in the prior art to heat and melt a target made of a low-temperature melting material (e.g., a tin target) in magnetron sputtering to increase deposition rates through local evaporation processes and reduced sublimation energy on the target surface (Sasaki, K. et al., Appl. Phys. Express, 2018, 11:36201).

[0006] Furthermore, it is known to perform cathode sputtering with a liquid lithium target, which is melted to liquid lithium via a heating device at the target to increase the sputtering yield. In this process, a solid lithium target is heated to a temperature that melts the lithium using a separate heating device. Subsequently, ions are accelerated at an angle of 45° onto the liquid lithium via a colutron ion source, and the lithium is sputtered onto a substrate (Allain, JP et al., 2001, Journal of Nuclear Materials, 290-293:180-184).

[0007] The methods and systems known in the prior art have the disadvantage that they are complex, energy-intensive and costly, and the efficiency and homogeneity of the layer deposition could be improved.

[0008] Based on this, the object of the present invention was to provide a method and a system for depositing a material onto a substrate that overcomes at least one disadvantage of the prior art. In particular, the method and the system should make it possible to deposit a material onto a substrate via magnetron sputtering in a less complex (i.e., simpler), more energy-efficient, more cost-effective, more efficient, and / or more homogeneous manner.

[0009] The problem is solved by the method with the features of claim 1 and the system with the features of claim 9. The dependent claims describe advantageous further developments.

[0010] According to the invention, a method for depositing a material onto a substrate via magnetron sputtering is provided, comprising or consisting of the following steps: a) providing a magnetron sputtering apparatus comprising at least one vacuum chamber, an electrical voltage source, and a magnetron, wherein the magnetron is electrically connected to the electrical voltage source; b) providing a crucible in the vacuum chamber, wherein the crucible contains in an interior space of the crucible a solid material having a melting point lower than the melting point of the crucible; c) providing a substrate in the vacuum chamber; d) evacuating the vacuum chamber; and e) depositing the material onto the substrate in the vacuum chamber after evacuation of the vacuum chamber.wherein during step e) the magnetron is supplied with an electrical power by the electrical voltage source which is high enough to heat the solid material in the interior of the crucible to a temperature which corresponds at least to the melting point of the solid material, characterized in that in step b) the crucible is attached to the magnetron via a thermally insulating spacer.

[0011] The inventive method makes it possible to deposit a material onto a substrate in a simpler, more energy-saving, more cost-effective, more efficient and more homogeneous way.

[0012] A more homogeneous deposition results from the use of a system suitable for magnetron sputtering in the process. Furthermore, in the process according to the invention, the material in the crucible (e.g., lithium) is only liquefied once a vacuum has already been established in the vacuum chamber. This represents an additional advantage over processes in which the material in the crucible (e.g., lithium) is melted in an oxygen-containing atmosphere. In the latter case, there is a risk that oxide particles of the material (e.g., lithium oxide particles) will mix into the lower layers of the molten material and then be sputtered along with it during the sputtering process, which can impair the homogeneity of the deposited layers. This can be avoided with the process according to the invention; that is, layers can be sputtered that are more homogeneous with respect to their composition.exhibit fewer to no oxidized particles of the material used, e.g., fewer lithium oxide particles if lithium is used as the material).

[0013] A more efficient deposition is achieved with the method according to the invention by selecting the electrical power so high that the material in the crucible is in a molten state, i.e., a molten material is sputtered.

[0014] A simpler, more energy-efficient, and more cost-effective deposition process using the inventive method results, firstly, from the fact that the melting of the material in the crucible is caused by the electrical power applied to the magnetron, thus eliminating the need for a separate heating device to heat the crucible. Secondly, a simpler, more energy-efficient, and more cost-effective deposition process results from the fact that, in step b), the crucible is attached to the magnetron via a thermally insulating spacer, i.e., a thermally insulating spacer establishes a distance between the crucible and the magnetron. Heat conduction from the crucible to the magnetron is therefore only possible through the thermally insulating spacer. This ensures that the crucible is thermally insulated from the magnetron, thus minimizing heat loss from the crucible to the magnetron.The advantage of thermal insulation is particularly pronounced when a water-cooled magnetron is used in the process, as heat loss from the crucible to the magnetron can be especially high in this case. The thermal insulation provided by the spacer effectively prevents this, thereby minimizing the required heating energy input for generating and maintaining the molten material inside the crucible. This makes the process more energy-efficient, and therefore also more cost-effective and simpler.

[0015] The crucible can be attached to the magnetron via a thermally insulating spacer using a fastening element. This fastening element can be a screw.

[0016] The magnetron sputtering system provided in the process can include a vacuum pump, and the vacuum pump can be used in the process for evacuating the vacuum chamber, wherein the vacuum pump is preferably selected from the group consisting of rotary vane pump, oil diffusion pump, and combinations thereof.

[0017] Furthermore, the magnetron sputtering system provided in the method can include at least one generator for igniting a gas discharge, and the at least one generator can be used in the method for igniting a gas discharge, wherein the at least one generator is preferably selected from the group consisting of DC sputter generator, MF sputter generator, RF sputter generator and combinations thereof.

[0018] Furthermore, the magnetron sputtering system provided in the process can include water cooling for cooling the magnetron, and the water cooling system can be used to cool the magnetron. In addition, the magnetron sputtering system provided in the process can include a glove box upstream of the vacuum chamber, and the glove box is used to supply the crucible containing the solid material to the vacuum chamber, wherein the glove box is particularly preferably fluidically connected to a noble gas source, in particular an argon source, and is operated with noble gas, in particular argon.

[0019] Furthermore, the magnetron sputtering system provided in the process can include a detection device for detecting a layer thickness deposited on the substrate, and the detection device can be used to detect a layer thickness deposited on the substrate, wherein the detection device is particularly preferably a quartz crystal oscillator detection device.

[0020] Furthermore, the magnetron sputtering system provided in the process (in addition to a plasma generator for ionizing a working gas in the vacuum chamber) can include a (further) plasma source for removing an oxide layer from the solid material inside the crucible, and this plasma source can be used for removing an oxide layer from the solid material inside the crucible. It is advantageous to remove an oxide layer from the solid material inside the crucible before melting the solid material inside the crucible, as this prevents oxidized material from mixing with the melt during liquefaction and reaching the lower regions of the melt, which would lead to the deposition of more inhomogeneous layers (with respect to their material composition).It can then no longer be ruled out that the layers deposited on the substrate contain at least some oxide of the material.

[0021] In a preferred embodiment, the magnetron sputtering system provided in the method does not include a heating device suitable for heating the crucible. This embodiment allows for a particularly simple, energy-efficient, and cost-effective implementation of the method. The crucible provided in the method can have a melting point in the range of > 2000 °C, preferably > 2500 °C. The solid material inside the crucible can have a melting point in the range of < 1950 °C, preferably in the range of < 1800 °C, particularly preferably in the range of < 1600 °C, most preferably in the range of < 1500 °C, and optionally in the range of < 250 °C.

[0022] In a preferred embodiment, the crucible provided in the method does not react chemically or physically with the solid material in the crucible. A physical reaction refers, for example, to the intercalation of the material inside the crucible into the material of which the crucible is made (e.g., incorporation or alloying). A chemical reaction refers, for example, to a chemical change in the material of which the crucible is made (e.g., oxidation of the material of which the crucible is made).

[0023] Furthermore, the crucible provided in the process can be electrically conductive or electrically insulating. An electrically conductive crucible has the advantage that the electrical power supplied by the magnetron can be transferred electrically (i.e., directly) to the crucible, which can lead to accelerated heating of the crucible. This is not possible in the case of an electrically insulating crucible, but even in this case, the material inside the crucible can heat up to a temperature at least equal to its melting point. In magnetron sputtering, a low-pressure gas discharge is ignited, with the ions from this gas discharge being accelerated by an electric field toward the cathode and then toward the crucible. To maintain the electric field, the material inside the crucible must be electrically conductive and be, or become, electrically conductively connected to the magnetron.This connection can be made directly (i.e., without an intermediate component) and / or via the thermally insulating spacer, provided the spacer is also electrically conductive. The ions from the gas discharge, which are then accelerated towards the crucible and the material within it, are slowed down by the crucible and the material within it, resulting in heating of the crucible and the material within it. Furthermore, it is possible that the system includes an RF generator and that radio frequency electromagnetic radiation is irradiated onto the crucible (i.e., power is supplied via radio frequency).

[0024] Furthermore, the crucible provided in the process can contain a metal, preferably consisting of > 99 wt.% of a metal. The metal is particularly preferably selected from the group consisting of molybdenum, tungsten, tantalum, gold, chromium, stainless steel, titanium, and combinations thereof.

[0025] Apart from that, the crucible provided in the process may contain or consist of graphite.

[0026] Furthermore, the crucible provided in the process can contain or consist of a ceramic, the ceramic preferably being selected from the group consisting of BN, Al2O3, SiCh and combinations thereof.

[0027] The crucible provided in the process can contain a solid material inside that is either electrically conductive or electrically insulating. The advantage of an electrically conductive material is that electrical power applied to the magnetron can be transferred directly to the material via an electrical connection between the material and the magnetron, which can lead to greater heating of the material inside the crucible.

[0028] Furthermore, the crucible provided in the process can contain or consist of an alkali metal, wherein the alkali metal is preferably selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and combinations thereof. The alkali metal is particularly preferably selected from the group consisting of lithium, sodium, and combinations thereof.

[0029] Furthermore, the crucible provided in the process can contain or consist of a metal, wherein the metal is preferably selected from the group consisting of indium, tin, gallium and combinations thereof. In addition, the crucible provided in the process can contain or consist of a metalloid, wherein the metalloid is preferably silicon.

[0030] The substrate provided in the vacuum chamber in the process can contain or consist of a metallic battery conductor, wherein the metallic conductor is preferably selected from the group consisting of copper, nickel, aluminium, stainless steel and combinations thereof.

[0031] Furthermore, the substrate provided in the vacuum chamber during the process can contain or consist of a solid ion conductor of a battery.

[0032] Furthermore, the substrate provided in the vacuum chamber during the process can be arranged on a receiving device. The receiving device is particularly preferably connected to an electric motor for moving the receiving device. The receiving device most preferably includes or consists of a rotary table.

[0033] The process can include removing an oxide film from the surface of the solid material. It is advantageous if the oxide film is removed before the solid material is liquefied. This measure prevents the deposition of an oxide from the material onto the substrate.

[0034] This process step (removing an oxide film) can include removing the oxide film by depositing the material in the crucible onto a sacrificial substrate that is different from the substrate. For this purpose, the magnetron is operated at an electrical power that is set so low that the material in the crucible does not melt during deposition onto the sacrificial substrate.

[0035] Furthermore, this process step (removing an oxide film) can include removing the oxide film by applying plasma from a plasma source in the magnetron sputtering system. In this process, the crucible can be attached to the vacuum chamber magnetron via a thermally insulating spacer, which can be either electrically conductive or electrically insulating. An electrically conductive spacer has the advantage that it allows the electrical power supplied by the magnetron to be electrically transferred to the crucible and / or to the material inside the crucible. This can lead to faster heating of the material inside the crucible.

[0036] Furthermore, in this process, the crucible can be attached to the magnetron of the vacuum chamber via a thermally insulating spacer, which has a thermal conductivity in the range of < 135 W / mK, preferably < 100 W / mK, particularly preferably < 60 W / mK, most preferably < 40 W / mK, and especially < 20 W / mK. The lower the thermal conductivity of the spacer, the lower the heat losses from the crucible to the magnetron, and the more energy-efficient and cost-effective the process can be.

[0037] Furthermore, in this process, the crucible can be attached to the magnetron of the vacuum chamber via a thermally insulating spacer containing or consisting of a metal, wherein the metal is particularly preferably selected from the group consisting of brass, bronze, nickel silver, nickel, titanium, zinc, white metal, bismuth, stainless steel, and combinations thereof. These materials are cost-effective, have a very high melting point, very high electrical conductivity, and low thermal conductivity. The metal is most preferably stainless steel. Stainless steel has the additional advantage of high mechanical stability and a low tendency to oxidize (even at high temperatures).

[0038] Apart from that, in this process the crucible can be attached to the magnetron of the vacuum chamber via a thermally insulating spacer, which establishes a gap between the crucible and the magnetron.

[0039] In this process, the magnetron can be supplied with an electrical power in the range of > 1 W / cm². 2 Magnetron surface area, preferably > 1.5 W / cm² 2 Magnetron surface area, particularly preferred > 2 W / cm² 2 Magnetron surface area, especially preferred > 2.5 W / cm² 2 Magnetron surface, especially > 3 W / cm² 2 Magnetron surface area, optional > 3.5 W / cm² 2 Magnetron surface. The magnetron surface refers to the surface of the target (i.e., the surface of the cathode).

[0040] According to the invention, a system for depositing a material onto a substrate via magnetron sputtering is further provided, comprising or consisting of: a) a vacuum chamber; b) an electrical voltage source; c) a magnetron electrically connected to the electrical voltage source; d) a crucible containing a solid material with a melting point lower than the melting point of the crucible within an interior of the crucible; e) a control unit configured to supply the magnetron with sufficient electrical power during the deposition of the material in the interior of the crucible onto a substrate to heat the solid material to a temperature at least equal to the melting point of the solid material; characterized in that the magnetron has a thermally insulating spacer suitable for mounting the crucible.

[0041] With the system according to the invention, it is possible to deposit an electrically conductive material on a substrate in a simpler, more energy-saving, more cost-effective, more efficient and more homogeneous way.

[0042] The system may include a vacuum pump and the control unit may be configured to cause the vacuum pump to evacuate the vacuum chamber, wherein the vacuum pump is preferably selected from the group consisting of rotary vane pump, oil diffusion pump and combinations thereof.

[0043] Furthermore, the system can include at least one generator for initiating a gas discharge and the control unit can be configured to cause the at least one generator to initiate a gas discharge, wherein the at least one generator is preferably selected from the group consisting of DC sputter generator, MF sputter generator, RF sputter generator and combinations thereof.

[0044] In addition, the system can include water cooling for cooling the magnetron, and the control unit can be configured to initiate the water cooling for cooling the magnetron.

[0045] Furthermore, the system can include a glove box upstream of the vacuum chamber, and the glove box can be suitable for supplying the crucible containing the solid material to the vacuum chamber. The glove box is particularly preferably fluidically connected to the system via a noble gas source, especially an argon source, and the control unit is configured to cause the noble gas source to operate the glove box with noble gas, especially argon.

[0046] Furthermore, the system can include a detection device for detecting a layer thickness deposited on the substrate and the control unit can be configured to cause the detection device to detect a layer thickness deposited on the substrate, wherein the detection device is particularly preferably a quartz crystal oscillator detection device.

[0047] Furthermore, the system (in addition to a plasma generator for ionizing a working gas in the vacuum chamber) can contain a (further) plasma source for removing an oxide layer on the solid material inside the crucible, and the control unit can be configured to cause the plasma source to generate a plasma for removing an oxide layer on the solid material inside the crucible.

[0048] In a preferred embodiment, the system does not include a heating device suitable for heating the crucible.

[0049] The crucible of the system may (already) be attached to the magnetron via the thermally insulating spacer. The system may also include a fastening element that secures the crucible to the magnetron via the thermally insulating spacer. This fastening element may be a screw.

[0050] Furthermore, the crucible of the system can have a melting point in the range of > 2000 °C, preferably > 2500 °C. The solid material inside the crucible can have a melting point in the range of < 1950 °C, preferably in the range of < 1800 °C, particularly preferably in the range of < 1600 °C, most preferably in the range of < 1500 °C, optionally in the range of < 250 °C.

[0051] In a preferred embodiment, the crucible of the system does not react chemically or physically with the solid material inside the crucible.

[0052] The crucible of the system can be electrically conductive or electrically insulating.

[0053] Furthermore, the crucible of the apparatus can contain a metal, preferably consisting of > 99 wt.% of a metal. The metal is particularly preferably selected from the group consisting of molybdenum, tungsten, tantalum, gold, chromium, stainless steel, titanium, and combinations thereof.

[0054] Apart from that, the crucible of the apparatus may contain or consist of graphite.

[0055] Furthermore, the crucible of the apparatus may contain or consist of a ceramic, the ceramic preferably being selected from the group consisting of BN, Al2O3, SiO2 and combinations thereof.

[0056] The solid material contained in the crucible of the system can be electrically conductive or electrically charged.

[0057] Furthermore, the solid material contained in the crucible of the apparatus can contain or consist of an alkali metal, wherein the alkali metal is preferably selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and combinations thereof. The alkali metal is particularly preferably selected from the group consisting of lithium, sodium, and combinations thereof.

[0058] Furthermore, the solid material contained in the crucible of the apparatus may contain or consist of a metal, the metal preferably being selected from the group consisting of indium, tin, gallium and combinations thereof.

[0059] Apart from that, the solid material contained in the crucible of the system may contain or consist of a semimetal, preferably silicon.

[0060] The vacuum chamber of the system may (already) contain a substrate.

[0061] The substrate may contain or consist of a metallic battery conductor, wherein the metallic conductor is preferably selected from the group consisting of copper, nickel, aluminium, stainless steel and combinations thereof.

[0062] Furthermore, the substrate can contain a solid ion conductor of a battery or consist of it.

[0063] Furthermore, the substrate can be arranged on a receiving device for receiving the substrate, wherein the receiving device is particularly preferably connected to an electric motor of the system for moving the receiving device. The receiving device most preferably includes or consists of a rotary table.

[0064] The system can be configured to remove an oxide film from a surface of the solid material.

[0065] The control unit of the system can be configured to cause the system to remove the oxide film by depositing the material in the crucible onto a sacrificial substrate that is different from the substrate, whereby the magnetron is operated with an electrical power that is set so low that the material in the crucible does not melt during the deposition of the material onto the sacrificial substrate.

[0066] Furthermore, the control unit of the system can be configured to remove the oxide film by applying plasma from a plasma source of the system.

[0067] The thermally insulating spacer of the system can be electrically conductive or electrically insulating.

[0068] Furthermore, the thermally insulating spacer of the system can have a thermal conductivity in the range of < 135 W / mK, preferably < 100 W / mK, particularly preferably < 60 W / mK, most preferably < 40 W / mK, and in particular < 20 W / mK.

[0069] Furthermore, the thermally insulating spacer of the system can contain or consist of a metal, wherein the metal is particularly preferably selected from the group consisting of brass, bronze, nickel silver, nickel, titanium, zinc, white metal, bismuth, stainless steel and combinations thereof. The metal is most preferably stainless steel.

[0070] Furthermore, the thermally insulating spacer can create a gap between the crucible and the magnetron.

[0071] The control unit of the system can be configured to control the electrical voltage source so that the magnetron is supplied with an electrical power in the range of > 1 W / cm². 2 Magnetron surface area, preferably > 1.5 W / cm² 2 Magnetron surface area, particularly preferred > 2 W / cm² 2 Magnetron surface area, especially preferred > 2.5 W / cm² 2 Magnetron surface, especially > 3 W / cm² 2 Magnetron surface area, optional > 3.5 W / cm² 2 Magnetron surface, lies.

[0072] The system according to the invention can be configured to carry out the method according to the invention. In particular, the control unit of the system according to the invention can be configured to initiate the execution of the process steps of the method according to the invention.

[0073] The following figures and example will be used to explain the subject matter of the invention in more detail, without limiting it to the specific embodiments shown here.

[0074] Figure 1 schematically shows a part of a system according to the invention for depositing a material onto a substrate via magnetron sputtering. The system comprises a vacuum chamber 1, an electrical voltage source (not shown), a magnetron 2 electrically connected to the electrical voltage source, a crucible 3 containing a solid material 5 in an interior 4 of the crucible 3, and a control unit (not shown). The control unit is configured to supply the magnetron with sufficient electrical power during the deposition of the material 5 in the interior 4 of the crucible 3 onto a substrate (not shown) to heat the solid material 5 in the interior 4 of the crucible 3 to a temperature at least equal to its melting point. In the system according to the invention, the magnetron 2 has a thermally insulating stainless steel spacer 6 suitable for mounting the crucible 2.The thermally insulating spacer 6 is attached to the magnetron 2 and the crucible 3 via a screw 7 (also made of stainless steel).

[0075] Figure 2 shows the dependence of the deposition rate on the electrical power applied to the magnetron via the voltage source. It can be seen that, in the case of a crucible made of > 99 wt% molybdenum, lithium as the target in the crucible, and a thermally insulating stainless steel spacer, the sputtering rate initially increases approximately linearly from 50 W to 125 W. This is because, with the crucible, spacer, and water cooling of the magnetron used, the electrical power in this range is not high enough to heat the crucible to or above the melting point of lithium (i.e., > 180.5 °C) and maintain it at that temperature. The sputtering rate up to a power of 125 W thus behaves similarly to the sputtering rate in conventional processes where the lithium target does not melt.in which solid lithium is sputtered (see "MS" in Figure 2, which represents such a conventional method). However, if the electrical power applied to the magnetron in this process increases above 125 W (i.e., to, for example, 150 W, 175 W, or 200 W), the electrical power is high enough to melt the lithium in the crucible (see "HTS" in Figure 2, which represents a method according to the invention). This is not the case with conventional methods, since in these methods the crucible is not attached to the magnetron by a thermally insulating spacer, and the crucible therefore cools down too much during the process to raise its temperature above 180.5 °C (see "MS" in Figure 2). Due to the lithium being melted in the method according to the invention, the sputtering rate increases significantly, in this case to a maximum sputtering rate of 22.5 nm / s at 200 W of electrical power. Such a sputtering rate corresponds to approximately...This results in a sputtering rate 70 times higher than that achieved at an electrical power of 200 W for sputtering solid lithium. This enables highly efficient sputtering of lithium onto a substrate, making the process attractive for industrial implementation. Crucially, the process can also be carried out in a simpler, more energy-efficient, and more cost-effective manner than known methods for sputtering liquid lithium, since no separate heating of the crucible by a heating device is required. Furthermore, in the process according to the invention, heat losses to the magnetron are minimized by the thermally insulating spacer between the crucible and the magnetron, which has a particularly positive effect on the energy balance, especially with water-cooled magnetrons.

[0076] Example - Implementation of a method according to the invention

[0077] A magnetron sputtering system is provided, which includes at least a vacuum chamber, a vacuum pump, an electrical voltage source and a magnetron that is electrically connected to the electrical voltage source.

[0078] In this case, the system also includes a glove box, which is located upstream of the vacuum chamber and can be operated with argon. The glove box has the advantage of guaranteeing safe sample handling and preventing oxidation effects. Furthermore, the system in this case includes two vacuum pumps: a rotary vane pump and an oil diffusion pump, as well as two generators.

[0079] In addition, the system can include water cooling for cooling the magnetron.

[0080] Furthermore, a crucible made of 99 wt% molybdenum containing solid lithium metal is provided in the vacuum chamber of the system. Molybdenum has the advantage of a very high melting point (2623 °C), which prevents material failure of the crucible during the process. In addition, molybdenum does not react chemically or physically with the lithium in the crucible.

[0081] The crucible is attached to the magnetron of the system via a stainless steel spacer. In known methods, a spacer (in particular a layer) is used that is not thermally insulating (e.g., a layer of graphite). The thermally insulating spacer used according to the invention blocks heat dissipation from the crucible towards the magnetron, which is cooled here by the water cooling system. In short, the thermally insulating spacer used according to the invention contributes to the fact that the crucible can heat up efficiently via the electrical power applied to the magnetron by the electrical voltage source, thereby experiencing only very low heat losses (thermal insulation of the crucible).

[0082] A metallic battery conductor (e.g., a copper foil) serves as the substrate in the vacuum chamber of the system. The substrate is positioned on a rotating platform within the system. The rotating platform ensures substrate changes and guarantees that only pure lithium is deposited onto the substrate, i.e., the metallic conductor.

[0083] The system also includes a quartz crystal oscillator detection device for detecting the layer thickness deposited on the substrate, i.e., the metallic conductor. The quartz crystal oscillator detection device is placed in the system's vacuum chamber. Once the substrate, the crucible, and the quartz crystal oscillator detection device are in the system's vacuum chamber, the two vacuum pumps generate the appropriate base pressure for the process.

[0084] In this case, before the actual deposition of lithium onto the substrate, contaminants and oxidized lithium metal are removed by a preceding sputtering step (i.e., by deposition onto a sacrificial substrate, which is also located on the rotary table of the system and is different from the substrate), and only then does the actual deposition of pure lithium take place to produce a thin lithium layer on the substrate, i.e., the metallic conductor (i.e., to produce a lithium anode).

[0085] Subsequently, lithium is deposited onto the metallic substrate in the vacuum chamber. Before and during the deposition process, the magnetron of the system is supplied with sufficient electrical power from the voltage source to heat the material in the crucible to a temperature above 180.5 °C (the melting point of lithium). In this case, the electrical power is 175 W (see Figure 1).

[0086] Melting the lithium directly in the crucible allows for higher deposition rates, thus increasing the efficiency of the process while maintaining consistent quality and accuracy. Furthermore, this method is simpler, more energy-efficient, and more cost-effective than established methods that use a separate heating device to melt the lithium in the crucible (resulting in higher component and energy consumption) and whose crucibles, due to a lack of thermal insulation, transfer heat energy to the magnetron and thus lose it (also requiring higher energy consumption to keep the lithium in a molten state).

[0087] 1: Vacuum chamber;

[0088] 2: Magnetron; 3: Crucible;

[0089] 4: Interior of the crucible;

[0090] 5: Material;

[0091] 6: thermally insulating spacer; 7: screw.

Claims

Patent claims 1. A method for depositing a material onto a substrate by magnetron sputtering, comprising or consisting of the following steps: a) providing a magnetron sputtering apparatus comprising at least a vacuum chamber, an electrical voltage source, and a magnetron, wherein the magnetron is electrically connected to the electrical voltage source; b) providing a crucible in the vacuum chamber, wherein the crucible contains in an interior of the crucible a solid material having a melting point lower than the melting point of the crucible; c) providing a substrate in the vacuum chamber; d) evacuating the vacuum chamber; e) depositing the material onto the substrate in the vacuum chamber after evacuation of the vacuum chamber;wherein during step e) the magnetron is supplied with an electrical power by the electrical voltage source which is high enough to heat the solid material in the interior of the crucible to a temperature which corresponds at least to the melting point of the solid material, characterized in that in step b) the crucible is attached to the magnetron via a thermally insulating spacer.

2. Method according to the preceding claim, characterized in that the provided magnetron sputtering system further comprises i) includes a vacuum pump and the vacuum pump is used to evacuate the vacuum chamber, wherein the vacuum pump is preferably selected from the group consisting of rotary vane pumps, oil diffusion pumps and combinations thereof; and / or ii) includes at least one generator for igniting a gas discharge and the at least one generator is used to ignite a gas discharge, wherein the at least one generator is preferably selected from the group consisting of DC sputter generators, MF sputter generators, RF sputter generators and combinations thereof; and / or iii) includes a water cooling system for cooling the magnetron and the water cooling system is used to cool the magnetron;and / or iv) includes a glovebox upstream of the vacuum chamber and the glovebox is used to provide the crucible containing the solid material in the vacuum chamber, wherein the glovebox is particularly preferably fluidically connected to a noble gas source, in particular an argon source, and is operated with noble gas, in particular argon; and / or v) includes a detection device for detecting a layer thickness deposited on the substrate and the detection device is used to detect a layer thickness deposited on the substrate, wherein the detection device is particularly preferably a quartz crystal oscillator detection device; and / or vi) includes a plasma source for removing an oxide layer on the solid material in the interior of the crucible and the plasma source is used to remove an oxide layer on the solid material in the interior of the crucible;and / or vii) does not contain a heating device suitable for heating the crucible.; 3. A method according to any one of the preceding claims, characterized in that the provided crucible i) has a melting point in the range of > 2000 °C, preferably > 2500 °C; and / or ii) does not react chemically or physically with the solid material in the crucible; and / or iii) is electrically conductive or electrically insulating; and / or iv) contains a metal, preferably consisting of > 99 wt.% of a metal, wherein the metal is particularly preferably selected from the group consisting of molybdenum, tungsten, tantalum, gold, chromium, stainless steel, titanium and combinations thereof; and / or v) contains or consists of graphite; and / or vi) contains or consists of a ceramic, wherein the ceramic is preferably selected from the group consisting of BN, Al₂O₃, SiO₂ and combinations thereof.

4. A method according to any one of the preceding claims, characterized in that the crucible provided contains in its interior a solid material which i) is electrically conductive or electrically insulating; and / or ii) contains or consists of an alkali metal, wherein the alkali metal is preferably selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and combinations thereof, wherein the alkali metal is particularly preferably selected from the group consisting of lithium, sodium and combinations thereof; and / or iii) contains or consists of a metal, wherein the metal is preferably selected from the group consisting of indium, tin, gallium and combinations thereof; and / or iv) contains or consists of a metalloid, wherein the metalloid is preferably silicon.

5. A method according to any of the preceding claims, characterized in that the substrate provided in the vacuum chamber i) contains or consists of a metallic conductor of a battery, wherein the metallic conductor is preferably selected from the group consisting of copper, nickel, aluminum, stainless steel and combinations thereof; and / or ii) contains or consists of a solid ion conductor of a battery; and / or iii) is arranged on a receiving device for receiving the substrate, wherein the receiving device is particularly preferably connected to an electric motor for moving the receiving device, wherein the receiving device most preferably contains or consists of a rotary table.

6. A method according to any of the preceding claims, characterized in that the method comprises removing an oxide film from a surface of the solid material, wherein this step preferably comprises: i) removing the oxide film by depositing the material in the crucible onto a sacrificial substrate that is different from the substrate, wherein the magnetron is operated for this purpose with an electrical power that is set so low that no melting of the material in the crucible occurs during the deposition of the material onto the sacrificial substrate; and / or ii) removing the oxide film by applying plasma from a plasma source of the magnetron sputtering system.

7. A method according to any of the preceding claims, characterized in that the crucible is attached to the magnetron of the vacuum chamber via a thermally insulating spacer which is (i) electrically conductive or electrically insulating; and / or ii) has a thermal conductivity in the range of < 135 W / mK, preferably < 100 W / mK, particularly preferably < 60 W / mK, most preferably < 40 W / mK, particularly < 20 W / mK; and / or iii) contains or consists of a metal, wherein the metal is particularly preferably selected from the group consisting of brass, bronze, nickel silver, nickel, titanium, zinc, white metal, bismuth, stainless steel and combinations thereof, wherein the metal is most preferably stainless steel; and / or iv) establishes a gap between the crucible and the magnetron.

8. Method according to one of the preceding claims, characterized in that the magnetron is supplied with an electrical power in the range of > 1 W / cm² 2 Magnetron surface area, preferably > 1.5 W / cm² 2 Magnetron surface area, particularly preferred > 2 W / cm² 2 Magnetron surface area, especially preferred > 2.5 W / cm² 2 Magnetron surface, especially > 3 W / cm²2 Magnetron surface area, optional > 3.5 W / cm² 2 Magnetron surface, lies.

9. Apparatus for depositing a material onto a substrate by magnetron sputtering, comprising or consisting of: a) a vacuum chamber; b) an electrical voltage source; c) a magnetron electrically connected to the electrical voltage source; d) a crucible containing, within its interior, a solid material with a melting point lower than that of the crucible; e) a control unit configured to supply the magnetron with sufficient electrical power during the deposition of the material within the crucible onto a substrate to impart a solid material with a melting point lower than that of the crucible. to heat to a temperature that corresponds at least to the melting point of the solid material; characterized in that the magnetron has a thermally insulating spacer suitable for mounting the crucible.

10. System according to claim 9, characterized in that the system further comprises i) a vacuum pump and the control unit is configured to cause the vacuum pump to evacuate the vacuum chamber, wherein the vacuum pump is preferably selected from the group consisting of rotary vane pump, oil diffusion pump and combinations thereof; and / or ii) at least one generator for igniting a gas discharge and the control unit is configured to cause the at least one generator to ignite a gas discharge, wherein the at least one generator is preferably selected from the group consisting of DC sputter generator, MF sputter generator, RF sputter generator and combinations thereof; and / or iii) a water cooling system for cooling the magnetron and the control unit is configured to cause the water cooling system to cool the magnetron;and / or iv) includes a glove box upstream of the vacuum chamber and the glove box is suitable for providing the crucible with the solid material in the vacuum chamber, wherein the glove box is particularly preferably fluidically connected to a noble gas source, in particular an argon source, of the system and the control unit is configured to cause the noble gas source to operate the glove box with noble gas, in particular argon; and / or v) includes a detection device for detecting a layer thickness deposited on the substrate and the control unit is configured to cause the detection device to detect a layer thickness deposited on the substrate; to cause the substrate to deposit a layer thickness, wherein the detection device is particularly preferably a quartz crystal oscillator detection device; and / or vi) includes a plasma source for removing an oxide layer on the solid material inside the crucible and the control unit is configured to cause the plasma source to remove an oxide layer on the solid material inside the crucible; and / or vii) does not include a heating device suitable for heating the crucible.

11. Apparatus according to one of claims 9 or 10, characterized in that the crucible is attached to the magnetron via the thermally insulating spacer, wherein the crucible preferably i) has a melting point in the range of > 2000 °C, preferably > 2500 °C; and / or ii) does not react chemically or physically with the solid, electrically conductive material in the crucible; and / or iii) is electrically conductive or electrically insulating; and / or iv) contains a metal, preferably consisting of > 99 wt.% of a metal, wherein the metal is particularly preferably selected from the group consisting of molybdenum, tungsten, tantalum, gold, chromium, stainless steel, titanium and combinations thereof; and / or v) contains or consists of graphite; and / or vi) contains or consists of a ceramic, wherein the ceramic is preferably selected from the group consisting of BN, Al₂O₃, SiO₂ and combinations thereof.

12. Apparatus according to any one of claims 9 to 11, characterized in that the solid material contained in the crucible is i) electrically conductive or electrically insulating; and / or ii) contains or consists of an alkali metal, wherein the alkali metal is preferably selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and combinations thereof, wherein the alkali metal is particularly preferably selected from the group consisting of lithium, sodium and combinations thereof; and / or iii) contains or consists of a metal, wherein the metal is preferably selected from the group consisting of indium, tin, gallium and combinations thereof; and / or iv) contains or consists of a metalloid, wherein the metalloid is preferably silicon.

13. System according to any one of claims 9 to 12, characterized in that the vacuum chamber contains a substrate, wherein the substrate i) contains or consists of a metallic conductor of a battery, wherein the metallic conductor is preferably selected from the group consisting of copper, nickel, aluminum, stainless steel and combinations thereof; and / or ii) contains or consists of a solid ion conductor of a battery; and / or iii) is arranged on a receiving device for receiving the substrate, wherein the receiving device is particularly preferably connected to an electric motor of the system for moving the receiving device, wherein the receiving device most preferably contains or consists of a rotary table.

14. System according to any one of claims 9 to 13, characterized in that the system is configured to remove an oxide film from a surface of the solid material, wherein the control unit of the system is preferably configured to cause the system to i) to remove the oxide film by depositing the material in the crucible onto a sacrificial substrate that is different from the substrate, the magnetron being operated with an electrical power set so low that the material in the crucible does not melt during the deposition of the material onto the sacrificial substrate; and / or ii) to remove the oxide film by applying plasma from a plasma source of the system.

15. Apparatus according to any one of claims 9 to 14, characterized in that the thermally insulating spacer i) is electrically conductive or electrically insulating; and / or ii) has a thermal conductivity in the range of < 135 W / mK, preferably < 100 W / mK, particularly preferably < 60 W / mK, most preferably < 40 W / mK, in particular < 20 W / mK; and / or iii) contains or consists of a metal, wherein the metal is particularly preferably selected from the group consisting of brass, bronze, nickel silver, nickel, titanium, zinc, white metal, bismuth, stainless steel and combinations thereof, wherein the metal is most preferably stainless steel; and / or iv) establishes a gap between the crucible and the magnetron.

16. System according to any one of claims 9 to 15, characterized in that the control unit is configured to control the electrical voltage source such that the magnetron is supplied with an electrical power in a range of > 1 W / cm² 2 Magnetron surface area, preferably > 1.5 W / cm² 2 Magnetron surface area, particularly preferred > 2 W / cm² 2 Magnetron surface area, especially preferred > 2.5 W / cm² 2 Magnetron surface, especially > 3 W / cm² 2 Magnetron surface area, optional > 3.5 W / cm² 2 Magnetron surface, lies.

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