Coating method for depositing a coating system on a substrate, and a substrate having a coating system

Abstract

The invention relates to a coating method for depositing a coating system (S) on a substrate (1), wherein at least one HiPIMS layer (HS) and one DCMS layer (DS) are deposited on the substrate (1) by means of magnetron sputtering. In the method, a process chamber (3) which can be evacuated, contains a sputtering gas (2, 21, 22), has an anode and a magnetron (4) formed as a cathode, comprising a magnetic field source (41) and a primary target (42) with a coating material (43), is provided. According to the invention, one and the same primary target (42) is used to deposit, in any order and alternately one after the other, the HiPIMS layer (HS) by means of an HiPIMS sputtering method in a HiPIMS mode using a sequence consisting of a plurality of HiPIMS discharge pulses (5) of high power density with a pulse duration (τ1) having at least one atomic layer of the coating material (43), and the DCMS layer (DS) by means of a pulsed and / or non-pulsed DCMS sputtering method in a DCMS mode using a DCMS discharge pulse (6) of low power density with a pulse duration (τ2) in order to form the DCMS layer (DS) from the coating material (43).

Description

[0001] Coating process for the deposition of a layer system on a

[0002] Substrate, as well as a substrate with a layer system

[0003] The invention relates to a coating method by means of magnetron sputtering, wherein a layer system is deposited on a substrate alternately in a HIPIMS mode and in a DCMS mode, as well as to a substrate with such a layer system according to the preamble of the independent claim of the respective category.

[0004] Magnetron sputtering (MS) is a PVD (physical vapor deposition) method that is now firmly established as a standard method in science and technology. It is used in various variations for coating substrates with thin layers. For example, it is used for the production of corrosion protection coatings, wear-resistant hard coatings for tools and machine parts of all kinds, thermoresistive coatings, decorative coatings, or optical coatings. It is also used very successfully for coating substrates in a wide variety of other applications.

[0005] During the sputtering process itself, a vapor of atoms or molecules is generated from a target containing a coating material in an evacuated process chamber, which is then deposited onto the substrate to be coated. The vapor itself is created by the atoms or molecules being knocked out of the target by an ionized working gas (sputtering gas), which is usually an inert gas, frequently a noble gas such as argon (Ar) or krypton (Kr). The ions of the working gas are generated by an electrical discharge, which leads to the production of electrons, which in turn ionize the gas. During MS, a magnetic field is also generated in the vicinity of the target, which forces the generated electrons into a type of electron cloud, resulting in a concentration of electrons in front of the surface of the target, enabling increased ionization of the sputtering gas.The target is at a lower electrical potential than the area where the electron cloud is positioned. This accelerates the positive ions toward the target, where they knock atoms or molecules of the coating material out of the target. The released atoms or molecules ultimately deposit on all surfaces within the process chamber, including the surface of the substrate to be coated.

[0006] Compared to other sputtering processes that operate without the assistance of a magnetic field, MS achieves relatively high ionization efficiencies due to the magnetic confinement of the electron cloud. This results in relatively low electrical power requirements while maintaining high sputtering rates. By appropriately selecting the magnetic field geometry, the electron loss perpendicular to the magnetic field lines can also be significantly reduced, minimizing their impact on the substrate and thus significantly reducing the heating of the substrate, especially of the coating growing on the substrate.

[0007] MS enables the use of a wide variety of available materials. In addition to metals and their alloys, less conductive materials and brittle materials such as Si, B, Ti, TiB2, SiC, B4C, M0S2, WS2, and many others can be sputtered.

[0008] The use of MS as a coating process is also excellently suited for reactive sputtering using reactive process gases such as C2H2, NH3, Ar, N2, O2, and their mixtures, as well as a variety of other reactive process gases. For the reactive deposition of, for example, nitride, carbide, or oxide layers and their mixtures, the appropriate reactive gas is added. During reactive sputtering, the sputtered atoms or molecules react with the reactive process gases, with the reaction products ultimately forming the coating on the substrate.

[0009] To date, a variety of variants of magnetron sputtering (MS) have been developed.

[0010] In conventional DC magnetron sputtering (DCMS), either DC voltages are used as sputter voltages on the target (unpulsed DCMS) or, in pulsed DCMS, the DC voltage is applied to the target in a sequence of separate individual pulses. Typically, time-integrated power densities of up to 20 W / cm 2 on the target, with typical current densities on the target usually below 0.1A / cm 2 lay.

[0011] Compared to other sputtering processes, DCMS enables high deposition rates for the buildup of coatings on the substrate. Since a low substrate temperature can be maintained during the deposition process, it is also possible to coat sensitive materials.

[0012] Advantageous properties of coatings produced by DCMS include high adhesion of the coatings to the substrate as well as low porosity and lower defect densities in the layers.

[0013] Furthermore, magnetically assisted DCMS causes only minimal radiation damage to the substrate being coated.

[0014] A major disadvantage of MS in general, and DCMS in particular, is the low target utilization, well known to those skilled in the art, and the resulting effect that the deposited layers often have uneven thicknesses. The reason for this is that, due to the low energy (temperature) of the electrons, the ionization of the sputtering gas is very localized, and the location of the ionization regions is thus mapped onto the target surface. This leads to uneven erosion or wear of the target (formation of sputtering trenches), which in turn means that only a limited portion of the target can be used until it is completely eroded.

[0015] There are limits to increasing the amount of ionized gas in DOMS. Of course, the amount of ionized sputter gas can be increased relatively easily by increasing the applied sputter voltage, but this significantly increases the likelihood of arcing and leads to the negative coating properties known to those skilled in the art. Likewise, increasing the sputter voltage is limited because thermal overheating of the target limits the applied power.

[0016] In addition, the layers produced by DOMS are often characterized by pronounced columnar growth due to the relatively low ionization of the sputtered material, which unfortunately often leads to a disadvantage in the functionality of the layers in many applications.

[0017] For this reason, traditional DC magnetron sputtering (DOMS) has been continuously developed and improved over the past years and decades. Significant progress has been achieved by operating the magnetron in pulsed mode with high currents or current densities, which leads to an improved layer structure in the form of denser layers, particularly due to improved ionization of the sputtered material. This can significantly suppress or even completely prevent columnar growth, for example.

[0018] Such pulsed magnetron sputtering processes with high currents or current densities are well known to those skilled in the art under the term "High Power Impulse Magnetron Sputtering," or HiPIMS for short. The current densities at the target in HiPIMS typically exceed those of conventional DCMS, i.e., they are often well above 0.1 A / cm 2 and up to a few A / cm 2, so that power densities of some 100W / cm 2 up to MW / cm 2 can be applied to the target for a short time. Compared to conventional DCMS, HiPIMS is characterized by a higher plasma density and thus a significantly higher ionization capacity of the working gas and the reactive gas, especially the proportion of ionized sputtered target atoms.

[0019] To illustrate the enormous improvement in ionization rates when using a HiPIMS sputtering process compared to a DCMS sputtering process, reference is made to the following numerical example.

[0020] Typically, in a HiPIMS or DCMS coating process, the process pressure in the process chamber is in a pressure range of approximately 10' 4 Torr to 10 -2 Torr (approx. 0.013 Pa to 1.3 Pa). In practice, a classic DCMS sputtering process has a maximum cathode current density in the range of Jmax < 0.1 A / cm 2, with discharge voltages in the range of approximately 0.3 kV to 0.6 kV. By appropriately selecting the cathode current density and discharge voltage, corresponding cathode power densities are usually in the range of less than 0.1 kW / cm 2 At a process pressure of, for example, 1 Pa in the process chamber, the particle number n is approximately 1 O 20 Atoms per m 3

[0021] From this number of atoms, approximately 10 16 up to a maximum of 10 18 of all gas neutral particles in the mixture of process gas and target material, i.e., only between 0.01% and a maximum of 1% of all neutral particles are ionized. This means that an ionization fraction of a maximum of approximately 1% is achieved. Of this, only approximately 1% to approximately 3% consist of ionized target atoms. In a HiPIMS sputtering process, however, a much higher maximum cathode current density in the range of Jmax <10 A / cm 2, with discharge voltages in the range of approximately 0.5 kV to 1.5 kV. By appropriately selecting the cathode current density and discharge voltage, corresponding cathode power densities in a HiPIMS process are usually in the range of approximately 1 kW / cm 2 up to approx. 3kW / cm 2 As already mentioned above, at a process pressure of, for example, 1 Pa in the process chamber, the particle number n is approximately 1O 20 Atoms per m 3 From this number of atoms, approximately 3'10 19 up to approx. 9'10 19 of all gas neutral particles in the mixture of process gas and target material, i.e., an enormous proportion of between approximately 30% and 90% of all neutral particles are ionized. This means that an enormous ionization fraction of between approximately 30% and 90% is achieved. Of these, the ionized target atoms can constitute a volume fraction of up to 90%.

[0022] All sputtering techniques have an inherent power limit, which is determined by the coolability of the target and the target material itself. If the temperature at the target surface cannot be dissipated quickly enough, the target material melts. With conventional DCMS, the upper limit of power densities on the target is generally in the range of 50 W / cm² or less. 2 . Often, this maximum load limit in continuous DCMS operation is even at a maximum of 20W / cm 2 To further increase the power without overheating the target, the discharge must be pulsed. The increasing energy input and the associated temperature development on the target surface can be compensated by reducing the duty cycle. For this purpose, the sputter frequencies and pulse lengths are varied in the high-power range.

[0023] The high degree of ionization of the sputtered target atoms when using a HiPIMS process offers improved control of the layer growth and layer structure. Furthermore, by applying an electrical substrate bias voltage, the energy of the incoming ions can be controlled and the latter can be specifically directed. Targeted ion bombardment using sputter gas ions (e.g., Ar) and, in particular, the ions of the sputtered target material can exert a significant influence on the structure and layer properties, as well as crystal orientation, grain size, density, and mechanical layer stress. The high degree of ionization enables improved layer quality through higher density and hardness, improved layer adhesion, and reduced roughness.

[0024] Key features of HiPIMS are peak currents and peak power densities that are up to several orders of magnitude higher than their average power density.

[0025] The advantages of coatings produced using HiPIMS include, in particular, a denser layer morphology. This can lead to higher hardness in certain coating systems, such as AITiN coatings, but also to a lower Young's modulus.

[0026] While comparable TiAIN or AITiN coatings produced using DCMS typically have a hardness of up to 27 GPa and a Young's modulus of up to 400 GPa, the hardness of coatings produced using HiPIMS can easily reach up to 35 GPa with a Young's modulus of up to 500 GPa. The ratio of hardness to Young's modulus is a measure of the toughness properties of the coating. High hardness with a relatively low Young's modulus is advantageous for many applications. The process according to the invention allows for optimization by combining both coating types.

[0027] Another very important advantage of HiPIMS layers is their extremely high thermal stability, which results, among other things, from the denser layer structure.

[0028] In addition, the use of HiPIMS can improve layer adhesion in

[0029] Compared to layers produced using the DCMS process, HiPIMS layers are particularly advantageous for use, for example, in the coating of cutting tools, which can thus be produced with significantly increased cutting parameters and are characterized by far lower tool wear during operation.

[0030] However, the expert is also confronted with some disadvantages of the HiPIMS method, which are briefly outlined below, although the following list is not intended to be exhaustive.

[0031] It is not uncommon for increased residual stresses (internal stresses) to be observed in HiPIMS coatings during some coating processes, which can lead to mechanical defects such as cracks, bulging or flaking of the layer.

[0032] Furthermore, the deposition rate and thus the rate of layer growth (coating rate) is significantly reduced in HiPIMS processes compared to DCMS processes, both in reactive and non-reactive processes. Thus, the deposition rates and thus the coating rates in HiPIMS can be reduced by up to 70% compared to DCMS.

[0033] A primary reason for the lower deposition rates of HiPIMS discharge compared to DCMS discharge at the same applied energy is the ion backflow effect. This is primarily caused by the spatial plasma potential distribution during the high-voltage pulse pulling a portion of the positively charged ions of the sputtered target material back to the negatively biased surface. This results in self-sputtering of the target. This is also referred to as re-deposition. Unfortunately, this negative effect is a characteristic of the HiPIMS sputtering process. Finally, the problem of arcing, which is well known to those skilled in the art, is significantly higher in HiPIMS processes than in DCMS processes. Arcing refers to unwanted discharges that can be observed, for example, on sputtering targets. These discharges are local, temporary cathodic vacuum arc discharges.Arcing leads in particular to uneven coating, especially due to the formation of unwanted particles that negatively influence the coatings.

[0034] Last but not least, the energy consumption per slice volume with HiPIMS is significantly higher than when using a DCMS process.

[0035] In addition to the application of pure HiPIMS processes or the application of pure DCMS processes, so-called hybrid processes are also known in the state of the art, which use one or more identical or different magnetrons or sputter sources in different variants to use HiPIMS processes and DCMS processes to form coatings on a substrate simultaneously in one and the same process step.

[0036] The idea is to combine the advantages of HiPIMS and DCMS coating processes. A recent overview of such coating techniques can be found, for example, in VO Oskirko et al., in Vacuum 181 (2020) 109670.

[0037] While the use of such hybrid coating processes can at least partially mitigate some of the disadvantages described above, such hybrid processes have, among other things, significant process-related disadvantages or impose limitations on the coating processes, which in turn completely or partially negate the advantages of such processes.

[0038] For example, in hybrid processes where HiPMS and DCMS processes are used simultaneously, the gas pressure in the process chamber or the bias voltage on the target can be optimized either only for the HiPMS portion of the hybrid process or only for the DCMS portion of the hybrid process. Alternatively, compromises must be sought for these or other process parameters, which then do not lead to sufficiently optimal coating results.

[0039] Especially with regard to reactive coating processes using reactive process gases, such hybrid processes lead to massive, unavoidable limitations in process design. For example, in these hybrid processes, the reactive gases used, their mixtures, partial pressures (flows), etc., cannot be optimally adapted to the HiPIMS process and the DCMS process simultaneously, as both processes are applied simultaneously and changes to these process parameters of the gas flows can ultimately only be made very slowly. This fundamentally precludes a simultaneous optimal parameter selection for the HiPIMS process and the DCMS process with the known hybrid processes, both with regard to the layer properties, the layer thickness of the individual layers, which develops depending on the loading and rotation, and the deposition rates.

[0040] The expert knows that the coating rates BR in both the HiPIMS and the DCMS process are sensitively dependent on the magnetic field strength MFS of the magnetic field in front of the target as well as on the pulse frequencies of the HiPIMS or DCMS pulse sequences, as can be seen for example in Fig. 4 (JW Bradley et al 2015 J. Phys. D Appl.

[0041] Phys. 48 215202) should be recalled again. The key point here is that the dependence of the deposition rate BR on the magnetic field strength MFS of the magnetic field is exactly opposite in HiPIMS and DCMS processes, as can be clearly seen in Fig. 4.

[0042] While in DCMS processes the coating rate BR increases with increasing

[0043] As the magnetic field strength MFS of the magnetic field increases, the deposition rate BR in HiPIMS processes decreases with increasing magnetic field strength MFS of the magnetic field. Note that in Fig. 4, the magnetic field strength MFS of the magnetic field increases to the left.

[0044] This naturally leads to the fact that in the known hybrid processes, the magnetic field strength MFS of the magnetic field can only be optimally adapted to the HiPMS process or only to the DCMS process, or that a compromise must be made regarding the magnetic field strength MFS of the magnetic field, so that the magnetic field strength MFS of the magnetic field cannot be optimally selected for the HiPMS process or for the DCMS process.

[0045] The object of the invention is therefore to provide an improved coating method for producing a multi-layer system by means of magnetron sputtering and, as a result, a substrate with an improved layer system, wherein all advantages of the HiPIMS and those of the DCMS method can be optimally realized simultaneously, without having to accept the disadvantages of the known hybrid methods.

[0046] The subject matter of the invention that solves these problems is characterized by the features of the respective independent claims. The dependent claims relate to particularly advantageous embodiments of the invention.

[0047] The invention thus relates to a coating method for depositing a layer system on a substrate, wherein at least one HiPIMS layer and one DCMS layer are deposited on the substrate by magnetron sputtering. An evacuable process chamber containing a sputtering gas is provided, with an anode and a magnetron configured as a cathode, comprising a magnetic field source, and a primary target with a coating material.According to the invention, with one and the same primary target, the HiPIMS layer is deposited from the coating material in any order and one after the other by a HiPIMS sputtering process in a HiPIMS mode using a sequence consisting of a plurality of HiPIMS discharge pulses of high power density with a pulse duration of at least one atomic layer, and the DCMS layer is deposited from the coating material by a pulsed and / or unpulsed DCMS sputtering process in a DCMS mode using a DCMS discharge pulse of low power density with a pulse duration to form the DCMS layer.

[0048] The present invention makes it possible for the first time to successfully combine the HiPIMS sputtering process and the DCMS sputtering process in a single coating process in such a way that for the first time essentially all the advantages of the DCMS sputtering process and essentially all the advantages of the HiPIMS sputtering process for the formation of layer systems on a substrate can be exploited simultaneously, without having to make compromises in the coating parameters in favor of or disadvantage of the HiPIMS sputtering process or the DCMS sputtering process.

[0049] A coating process according to the invention therefore has practically all the advantages of DCMS sputtering, such as high coating rates, ensuring a low substrate temperature for coating sensitive materials, high adhesion of the coatings to the substrate, low porosity and lower defect densities in the layers, with simultaneously low radiation damage to the substrate to be coated due to the magnetic field of the magnetron, as well as lower energy consumption.

[0050] At the same time, a coating process according to the invention also demonstrates all the advantages of the known HiPIMS sputtering processes. These include, for example, a high degree of ionization of the sputtering gases and the sputtered target atoms, which ensures improved control of the layer growth and layer structure. Targeted ion bombardment using sputtering gas ions (e.g., Ar) and, in particular, the ions of the sputtered target material can exert a significantly positive influence on the structure and layer properties, as well as crystal orientation, grain size, density, and mechanical layer stress. The high degree of ionization in HiPIMS sputtering enables a significant improvement in layer quality through higher density and hardness, even further improved layer adhesion, and reduced roughness.

[0051] Further advantages of coatings produced using HiPIMS include a denser layer morphology and a less columnar layer growth pattern. This can lead to greater hardness in certain coating systems, such as AITiN coatings. Another very important advantage of HiPIMS coatings is their extremely high thermal stability, which results, among other things, from the denser layer structure.

[0052] Not only can all of these advantages of HiPIMS sputtering and DCMS sputtering processes be successfully combined for the first time using the coating process according to the invention, but the known disadvantages of both HiPIMS sputtering and DCMS sputtering processes can also be significantly reduced or completely avoided. This is particularly true with regard to the hybrid sputtering processes known from the prior art, which, as already described, have attempted, with rather limited success and at the expense of significant disadvantages, to combine the advantages of HiPIMS sputtering and DCMS sputtering by performing a HiPIMS sputtering process and a DCMS sputtering process simultaneously or in a temporally superimposed manner.

[0053] For example, increased residual stresses (internal stresses) are often observed in pure HiPIMS layer systems, which can lead to mechanical defects such as cracks, warping, or flaking of the layer. This risk is significantly reduced or almost completely eliminated by the inventive deposition of pure HiPIMS and DCMS layers deposited alternately directly on top of one another.

[0054] The problem of the relatively low deposition rate and thus the rate of layer growth (coating rate) in pure HiPIMS processes is significantly reduced with respect to the entire layer system. This applies to both reactive and non-reactive processes. Thus, depending on the process control and the ratio of the layer thicknesses of HiPIMS sublayers to DCMS sublayers of a layer system according to the invention, the deposition rates in a process according to the invention, and thus the coating rates compared to coatings deposited, for example, solely using a HiPIMS sputtering process, can be easily increased by 15% or 50%, or up to 90% or more.

[0055] As already mentioned, a primary reason for the lower deposition rates of pure HiPIMS discharge compared to DCMS discharge at the same input energy is the ion backflow effect. This is primarily caused by a portion of the positively charged ions of the sputtered target material being drawn back to the negatively biased target due to the spatial plasma potential distribution during the high-voltage pulse. This results in self-sputtering of the target. This is also referred to as re-deposition. This negative effect is known to be an inherent characteristic of the HiPIMS sputtering process and, of course, cannot be avoided per se even in a corresponding sub-step of a HiPIMS sputtering process within the framework of a coating process according to the invention.

[0056] However, in a coating process according to the invention, this significant disadvantage of the HiPIMS sputtering process is at least partially exploited. As already explained, a significant disadvantage of magnetron sputtering in general, and of pulsed or unpulsed DCMS in particular, is the low target utilization and the associated effect that the deposited layers often have uneven thicknesses. The reason for this is that the ionization of the sputtering gas occurs in a very localized manner, and the location of the ionization regions is thus mapped onto the target surface, leading to uneven erosion or wear of the target (formation of sputtering trenches), which in turn means that only a limited portion of the target can be used until it is completely eroded.

[0057] Here, the above-described, inherently negative re-deposition effect of the HiPIMS sputtering process suddenly has a surprisingly positive effect in a HiPIMS step following a DCMS step thanks to the present invention. The re-deposition effect caused by the "backflow" of the sputtered target ions in the HiPIMS process step results in previously sputtered target ions returning to the target, redepositing on the target surface, and thus at least partially restoring the target surface "damaged" by the previously performed DCMS sputtering, or at least partially healing it, so to speak, by at least partially repairing the erosion damage caused by the DCMS sputtering through the renewed deposition of target ions that have fallen back onto the target surface.As a result, with a coating process according to the invention, not only are the targets usable for a much longer time than with a pure DCMS sputtering process, but the DCMS partial layers are also more uniform when using a coating process according to the invention, i.e., they have, among other things, a significantly more uniform thickness than when using a known pure DCMS sputtering process. This naturally affects not only the isolated DCMS layers of a layer system according to the invention, but also improves the properties of the layer system according to the invention as a whole, e.g., with regard to the adhesion of the partial layers, resistance to chipping, hardness, temperature resistance, etc.

[0058] With a coating process according to the invention, the known and above-described problem of "arcing" in HiPIMS processes is also significantly reduced with regard to the formation of the coating system overall. This is due, if only, to the fact that the HiPIMS process steps are applied only during a portion of the entire coating process, i.e., not over the entire coating duration.

[0059] In particular, in comparison to the known hybrid processes in which at least partially HiPIMS pulses and DCMS pulses are applied to the target simultaneously, which can lead to arcing being induced by the mixed HiPIMS discharge pulses even during the DCMS coating phases, which are in themselves rather unproblematic with regard to arcing, the coating process according to the invention shows significantly better properties and leads to significantly improved properties of the layer systems according to the invention.

[0060] It should be expressly noted that the coating method according to the invention should not be confused with the hybrid coating methods discussed above. The coating method of the present invention has significant advantages, particularly compared to the known hybrid methods from the prior art, in which HiPIMS sputtering methods and DCMS sputtering methods are carried out simultaneously or overlapping in time, that fundamentally cannot be achieved with the known hybrid methods. Furthermore, such known hybrid methods have significant process-related disadvantages or impose limitations on the coating processes that can be essentially completely avoided by the present invention.For example, as already described, in known hybrid processes in which HiPMS and DCMS processes are used simultaneously, i.e., in a mixed manner, the gas pressure in the process chamber, the bias voltage on the target, or the magnetic field strength at the target can be optimized either only for the HiPMS portion of the hybrid process or only for the DCMS portion of the hybrid process. Alternatively, compromises must be sought for these or other process parameters, which then do not lead to sufficiently optimal coating results.

[0061] However, in a coating process according to the invention, it is easily possible to optimally select process parameters such as the gas pressure in the process chamber and / or the bias voltage on the target and / or the magnetic field strength on the target separately for both the HiPIMS process step and the DCMS process step, even though according to the invention the HiPIMS layer and the DCMS layer are produced with one and the same primary target, because in a process according to the invention, in contrast to the known hydride processes, the HiPIMS sputtering process and the DCMS sputtering process are decoupled from one another in terms of time and are carried out alternately one after the other.

[0062] This is a significant advantage of the inventive method, especially with regard to reactive coating processes using reactive process gases, compared to known hybrid processes, in which HiPIMS and DCMS processes are carried out simultaneously or superimposed. Unlike known hybrid processes, in a coating process according to the invention, the reactive gases used, their mixtures, partial pressures, flows, etc., can be optimally adapted to the HiPIMS process and the DCMS process separately, even if the change in these process parameters is rather slow, since the two different sputtering processes are not applied simultaneously, but rather sequentially, decoupled from each other.Another significant advantage of the method according to the invention compared to known hybrid methods arises from the fact that, as already mentioned, the coating rates in both HiPIMS and DCMS processes are sensitively dependent on the magnetic field strength in front of the target. The key point here is that the dependence of the coating rate on the magnetic field strength is exactly the opposite in HiPIMS and DCMS processes, as already clearly demonstrated in Fig. 4.

[0063] While in DCMS processes the coating rate increases with increasing magnetic field strength MFS of the magnetic field, in HiPIMS processes the coating rate decreases with increasing magnetic field strength MFS of the magnetic field.

[0064] In contrast to known hybrid processes, when using a process according to the invention, the magnetic field strength of the magnetic field in front of the magnetron can be easily and optimally adapted to both the HiPIMS process and the DCMS process separately, without having to compromise on the magnetic field strength, as is the case with known hybrid processes. Typical magnetic field strengths are, for example, in the range of approximately 50 Gauss to approximately WOOGauss. In practice, magnetic field strengths in the range of approximately 50 Gauss to 600 Gauss are advantageously selected for the HiPIMS process, whereas typical magnetic field strengths for the DCMS process are often in the range of approximately 300 Gauss to WOOGauss.

[0065] Of course, this is because, according to the invention, the two different sputtering processes HiPIMS and DCMS are not applied simultaneously, but one after the other, decoupled from each other in time.

[0066] Last but not least, the consumption of electrical energy per deposited layer volume is also significantly reduced in a coating process according to the invention, at least in comparison to a known pure HiPIMS sputtering process.

[0067] In the following, essential embodiments and process parameters are reported in a very general and schematic manner which have proven to be advantageous for carrying out coating processes according to the invention and for producing corresponding substrates.

[0068] Preferably, in HiPIMS mode in a method according to the invention, the maximum power density of the HiPIMS discharge pulse on the primary target is in a range of 0.05 kW / cm 2 and 10kW / cm 2 , preferably 0.1 kW / cm 2 and 5kW / cm 2 , in particular 0.2kW / cm 2 up to 3kW / cm 2 , particularly preferably at approx. 0.4kW / cm 2 or 2kW / cm 2, wherein in HiPIMS mode in the sequence of HiPIMS discharge pulses the pulse duration of the HiPIMS discharge pulse is selected between 5ps and 20ms, preferably between 20ps and 10ms, in particular between approximately 50ps and 5ms and / or in HiPIMS mode a HiPIMS death time in the sequence of HiPIMS discharge pulses between two consecutive HiPIMS discharge pulses is selected between 100ps and 500ms, preferably between 250ps and 250ms, in particular between approximately 500ps and 150ms, and / or wherein a HiPIMS duty cycle of a sequence of HiPIMS discharge pulse and HiPIMS death time is selected between 0.5% and 20%, preferably between 1% and 10%, particularly preferably between approximately 2% to 6% of the duration of the sequence of HiPIMS discharge pulse and HiPIMS death time are selected.

[0069] In a specific embodiment of the present invention, it is possible for the pulse duration of the HiPIMS discharge pulse and / or the duration of the HiPIMS dead time and / or the HiPIMS duty cycle to be varied during the deposition of the layer system according to a predeterminable scheme in a sequence of HiPIMS discharge pulses and HiPIMS dead time. This procedure can be advantageously used, for example, to optimize the layer properties or to produce sublayers with varying layer properties such as adhesion strength, hardness, residual stresses, thermal resistance, elastic modulus, and other varying or different properties. This may also potentially produce the gradient layers according to the invention, which will be mentioned later.

[0070] In DCMS mode, however, the power density of the DCMS discharge pulse on the primary target is preferably in the range of 1W / cm 2 and 50W / cm 2, preferably between 2W / cm 2 and 30W / cm 2 , particularly preferably of approx. 5W / cm 2 up to 25W / cm 2 selected, and / or in the pulsed and / or unpulsed DCMS mode, the pulse duration of the DCMS discharge pulse is advantageously but not necessarily selected between 1 ps and 10 ms, preferably between 5 ps and 500 ps, ​​in particular at approximately 20 ps or 200 ps, ​​wherein in the pulsed DCMS mode, a DCMS dead time in a sequence of DCMS discharge pulses between two consecutive DCMS discharge pulses is in practice frequently selected between 0.5 ps and 10 ms, preferably between 2 ps and 300 ps, ​​in particular at approximately 5 ps to 100 ps, ​​and / or wherein a DCMS duty cycle of a sequence of DCMS discharge pulse and DCMS dead time is between 30% and 99%, preferably between 50% and 97%, particularly preferably at approximately 75% or 95% of the duration of the sequence of DCMS discharge pulse and DCMS death time is selected.

[0071] In a further specific embodiment of the invention, in a sequence of DCMS discharge pulses and DCMS dead time, the pulse duration of the DCMS discharge pulse and / or the duration of the HiPIMS dead time and / or the HiPIMS duty cycle can be varied according to a predeterminable scheme during the deposition of the layer system. Such manipulation of the parameters of the DCMS pulse sequences can also be advantageously used to optimize the layer properties of a layer system according to the invention or to produce sublayers with varying layer properties such as adhesion strength, hardness, residual stresses, thermal resistance, elastic modulus, and other varying or different properties. This may also potentially produce the gradient layers according to the invention mentioned later.

[0072] In practice, the HiPIMS discharge pulse of high power density and / or DCMS discharge pulse of low power density is a rectangular and / or a triangular and / or a needle-shaped discharge pulse, in particular a bipolar discharge pulse or a bipolar sequence of discharge pulses, as are known per se and are schematically illustrated, for example, in Figs. 3a to 3f.

[0073] As already indicated, in a coating method according to the invention, the HiPIMS layer in HiPIMS mode and / or the DCMS layer in DCMS mode can each be deposited by means of a reactive and / or a non-reactive sputtering method, wherein the HiPIMS layer in HiPIMS mode is deposited using an HP process gas and the DCMS layer in DCMS mode is deposited using a DC process gas different from the HP process gas, and / or wherein a mixture of a plurality of different reactive gases is preferably used as the HP process gas and / or as the DC process gas.

[0074] In a particularly preferred embodiment of a reactive sputtering method according to the invention, a composition of the HP process gas during the deposition of the HiPIMS layer in HiPIMS mode and / or a composition of the DC process gas during the deposition of the DCMS layer in DCMS mode can be varied according to a predeterminable scheme, e.g., but not only, in order to form a gradient layer with regard to its chemical composition or to optimize the layer properties or to produce partial layers with varying layer properties such as adhesion strength, hardness, residual stresses, thermal resistance, elastic modulus and other varying or different properties.

[0075] For the same or other reasons, which depend on the desired properties of the layer system to be produced, a partial pressure of the HP process gas can be varied during the deposition of the HiPIMS layer in HiPIMS mode and / or a partial pressure of the DC process gas can be varied during the deposition of the DCMS layer in DCMS mode.

[0076] Likewise, for the same or other reasons depending on the desired properties of the layer system to be produced, an HP bias voltage of the substrate can be selected during the deposition of the HiPIMS layer in HiPIMS mode that is different from a DC bias voltage during the deposition of the DCMS layer in DCMS mode and / or during the deposition of the HiPIMS layer in HiPIMS mode, the HP bias voltage can be varied and / or during the deposition of the DCMS layer in DCMS mode, the DC bias voltage of the substrate can also be advantageously varied.

[0077] As already described above, a magnetic field strength of the magnetic field source during the pulsed and / or unpulsed DCMS sputtering process can be particularly advantageously selected to be different from a magnetic field strength of the magnetic field source during the HiPIMS sputtering process.

[0078] This can be done, for example, by means of a mechanical adjustment device, for example by means of a stepper motor or other mechanical adjustment units known per se to those skilled in the art, which can change or adjust a position and / or orientation of the magnetic field source in relation to the magnetron or in relation to the primary target, so that the magnetic field strength at the location or in the vicinity of the magnetron or the primary target can be variably set to a predetermined value. Of course, it is also possible, alternatively or in addition to the mechanical adjustment device described above, that the magnetic field strength is changed or adjusted in a manner known per se by varying a current through an electromagnetic coil, which can be provided in the vicinity of the magnetron and / or the primary target, so that the magnetic field strength at the location or in the vicinity of the magnetron orof the primary target can be variably set to a predefined value.

[0079] In principle, in addition to the previously mentioned possibilities, other measures known to those skilled in the art can also be taken to change the magnetic field strength at the location of the magnetron or at the location of the primary target during a coating step. For example, to produce a gradient layer and / or to optimally adjust the magnetic field strength at the magnetron and / or the primary target for the HiPIMS sputtering process and / or the DCMS sputtering process.

[0080] And of course, it is also possible that if there is another magnetron in the coating chamber, the strength of a magnetic field on the other magnetron can also be adjusted as described above.

[0081] As already mentioned several times, in specific embodiments of the present invention, the HiPIMS layer and / or the DCMS layer can be deposited as a gradient layer as described, which can be particularly advantageous depending on the application, as the person skilled in the art knows.

[0082] The gradient layer can be formed, among other things, by varying the chemical composition of the HP process gas and / or by varying the chemical composition of the DC process gas, or by other measures known per se. Since, in addition to the described sequences of HiPIMS and DCMS layers deposited directly on top of one another according to the invention, other types of partial layers can also be provided in layer systems according to the invention that are complex in terms of layer structure and layer construction, a plurality of identical or different magnetrons with primary targets, in particular comprising different coating materials, can be provided in a process chamber for implementing the invention, and / or at least one further magnetron with a target with a further coating material can be provided in the process chamber.

[0083] A process time for producing the HiPIMS layer and / or the DCMS layer produced in an unpulsed and / or pulsed DCMS sputtering process is, for example, in the range from 0.5s to 10,000s, preferably 1s to 5,000s, in particular from approximately 5s to 2,500s, wherein a ratio of the proportions of the sum of the layer thicknesses of the HiPIMS layers divided by the sum of the layer thicknesses of the DCMS layers produced in an unpulsed and / or pulsed DCMS sputtering process within the overall layer is, for example, in a range from 0.02 to 50, preferably in a range from 0.05 to 25, in particular in a range from 0.1 to 9.

[0084] In this case, a thickness of the individual layer, which can be varied in a layer thickness, in a layer system comprising the HiPIMS layers and the DCMS layers produced in an unpulsed and / or pulsed DCMS sputtering process can be in a range from 1 nm to 5000 nm, preferably in a range from 2 nm to 500 nm, in particular in a range from 5 nm to 250 nm.

[0085] Two specific embodiments of layer systems will be described below, one of which was deposited using a non-reactive sputtering method according to the invention, and another of which was deposited using a reactive sputtering method according to the invention. In these two specific embodiments, layer systems according to the invention made of TiB and AITiN, respectively, were deposited using a rectangular primary target with a length of approximately 10 mm.

[0086] 70cm and a width of approx. 7.5cm.

[0087] Example 1 (non-reactive process)

[0088] A non-reactive coating process according to the invention was used as an example for the deposition of TiB2 hard material layers, which is explained below as representative of all other non-reactive coating processes, including for metals and their alloys, silicon and others.

[0089] For all coating processes according to the invention, a target power of approximately 4.5 kW was selected for the bonded TiB2 target mounted on the magnetron. The flow of argon used as sputtering gas was 120 sccm. A negative bias voltage of 125 V was applied to the substrate holder. The coating time was 2 hours. In the process according to the invention, a modulated layer consisting of a single HiPIMS layer with a deposition time of 4 minutes plus a single pulsed DCMS layer with a deposition time of 2 minutes was deposited within the 2 hours. This resulted in an alternating layer structure, as shown generally and exemplarily in Fig. 2c, whereby, depending on the process, either the HiPIMS layer or the DCMS layer was applied directly to the substrate. The most important deposition parameters and the results are summarized below in Table 1.

[0090] The pulsed DCMS process, which is not part of the HiPIMS discharges, is characterized by typical values ​​for this process. The maximum current density of 0.017 mA / cm 2 at the target, which is constant throughout the entire pulse, corresponds to a power of 8.5 W / cm 2 The HiPIMS process is characterized by typical peak values. The maximum current density of 0.48 A / cm 2 is 30 times larger than in the pulsed DCMS process, the peak power density is about 350W / cm 2 The absolute peak power is 189 kW. The layer sequence of pulsed DCMS and HiPIMS resulting from a layer rate of 0.67 m / h results in a double layer thickness of approximately 66 nm.

[0091] The distribution within the bilayer results from the deposition rates in the pure HiPIMS process and the pure pulsed DCMS process. A single HiPIMS layer has a thickness of approximately 36 nm, and a single pulsed DCMS layer has a thickness of approximately 30 nm.

[0092] Table 1: Process parameters for the deposition of a TiB2 layer system.

[0093] The coating rates were determined using a method well known to those skilled in the art using spherical grinding. Hardness was measured with a Berkovich diamond at a load of 30 mN, and residual stresses were determined using the bending method in a conventional manner.

[0094] The process according to the invention demonstrates a significant increase in the coating rate compared to the pure HiPIMS process, approaching the rate of the pulsed DCMS process. A reduction in the residual stress state compared to the HiPIMS process was also achieved without a significant loss of hardness.

[0095] Example 2 (reactive process)

[0096] A reactive coating process for the deposition of AITiN hard coatings was implemented, which is representative of all other possible reactive processes with different reactive gases. For all coatings, a target power of 10 kW was selected for targets with compositions of 55 at% AI and 45 at%. The argon flow used as sputter gas was 120 sccm. A stepped bias voltage of 40 V, 80 V, and 120 V was applied to the substrate holder for one-third of the total coating time. The coating time for the HiPIMS was

[0097] Process and the DCMS process 2h. In the process according to the invention, a modulated layer consisting of a HiPIMS single layer of the

[0098] Deposition time of 4 min plus a pulsed DCMS single layer of the

[0099] Separation time of 2 m in 13 layers. The most important

[0100] Separation parameters and results are shown in Table 2.

[0101] Table 2: Process parameters for the deposition of an AITiN layer system.

[0102] The coating rates were determined using a method well known to those skilled in the art, using spherical grinding, as in Example 1. Hardness was measured with a Berkovich diamond at a load of 30 mN, and residual stresses were determined using the bending method in a conventional manner.

[0103] The pulsed DCMS process, which is not part of the HiPIMS discharges, is characterized by typical values ​​for this process. The maximum current density of 0.034 mA / cm 2 , which is constant throughout the entire pulse (power 10kW), corresponds to a power density of 19W / cm 2 The HiPIMS process is characterized by typical peak values ​​in the pulse. The maximum current density of 1.43 A / cm 2is 42 times larger than in the pulsed DCMS process, the peak power density is about 1180W / cm 2The absolute peak power is 618 kW. The individual layer thicknesses within a double layer of HiPIMS-DCMS were 135 nm for the HiPIMS single layer and 145 nm for the DCMS single layer. This demonstrated that the lower nitrogen flow of 45 sccm in the inventive process enabled a thicker layer to be deposited compared to the pure HiPIMS layer, which is deposited at 60 sccm. Theoretically, this results in 85 nm for the pure HiPIMS layer. In a process according to the invention, however, 135 nm was achieved. This is due to the reduced nitrogen flow. Sputtering then occurs more in the metallic mode. Substoichiometric layers are formed. These are visible as rings in a lighter color compared to the stoichiometric DCMS single layers in the images of cross-sections of the sample.The process according to the invention demonstrates a significant increase in the deposition rate compared to the pure HiPIMS process, approaching the rate of the pulsed DCMS process. A reduction in the residual stress state compared to the HiPIMS process was achieved. The higher rate is essentially due to the modulation of HiPIMS individual layers with DCMS individual layers and the modified reactive gas flow in the HiPIMS process.

[0104] The two illustrated examples—non-reactive and reactive processes—can of course also be combined. One example would be the Cr / CrN system. The Cr layers could be deposited non-reactively using HiPIMS to achieve a particularly high density for corrosion protection, while the hard CrN could be deposited using DCMS to provide wear protection, or vice versa, depending on the desired property profile.

[0105] It is advantageous to vary the reactive gases at least temporarily during the coating process for different layers. For example, this allows layer architectures to be realized that contain a gradient with at least one element of the reactive gas or mixture, so that, for example, starting with CrN, the addition of O2 initially produces CrNO, followed by CrO as the top layer.

[0106] In the following, the invention is explained in more detail with reference to the schematic drawing and further very specific embodiments.

[0107] They show in schematic representation:

[0108] Fig. 1 shows a coating device known per se with process chamber, DC power supply and gas supply;

[0109] Fig. 2a shows a sequence of HiPIMS discharge pulses for deposition of the HiPIMS layer according to Fig. 2c;

[0110] Fig. 2b shows a sequence of DCMS discharge pulses for depositing the DCMS layer according to Fig. 2c;

[0111] Fig. 2c shows a simple embodiment of a layer system according to the invention produced with the pulse sequences according to Fig. 2a and Fig. 2b;

[0112] Fig. 3a schematically shows a rectangular HiPIMS or DCMS discharge pulse;

[0113] Fig. 3b schematically shows a triangular HiPIMS or DCMS discharge pulse;

[0114] Fig. 3c schematically shows a needle-shaped HiPIMS or DCMS discharge pulse;

[0115] Fig. 3d schematically shows a rectangular HiPIMS or DCMS discharge pulse according to Fig. 3a with preparation pulse;

[0116] Fig. 3e schematically shows a triangular HiPIMS or DCMS discharge pulse according to Fig. 3b with a positive rectangular pulse;

[0117] Fig. 3f schematically shows a bipolar pulse sequence with needle-shaped discharge pulses; Fig. 4 shows the deposition rate as a function of the magnetic field strength and the pulse frequency.

[0118] For a better understanding of the invention, a coating device B known per se with a process chamber 3, a first power supply unit 7 comprising a DC power supply 71 and a pulse unit 72, and a second power supply unit 8, in the specific embodiment according to Fig. 1 comprising a DC power supply 81 and a pulse unit 82, is schematically described below with reference to Fig. 1. At least the first power supply unit 7 must be designed and operable in such a way that the method according to the invention can be carried out by means of the magnetron 4, as will be explained in more detail below. The second power supply unit 8 can either be identical to the first power supply unit 7 or be different from the power supply unit 7, depending on which specific sputtering process is to be carried out with the magnetron 400.

[0119] At this point, it should be expressly mentioned that in order to carry out a coating method according to the invention according to claim 1, for example in order to form a layer system S according to the invention according to Fig. 2c by means of pulse sequences according to Fig. 2a and 2b, the second magnetron 400 with second power supply unit is not required and can therefore also be omitted, or can be operated with the same parameters as the first magnetron.

[0120] In the present specific example of a coating device B, the first power supply unit 7 is electrically connected to the magnetron 4, comprising a magnetic field source 41 and a primary target 42 with a coating material 43.

[0121] In the present specific embodiment of Fig. 1, the magnetic field source 41 is designed such that a magnetic field strength MFS of the magnetic field source 41 during the pulsed and / or unpulsed DCMS sputtering process can be selected to be different from a magnetic field strength MFS of the magnetic field source 41 during the HiPIMS sputtering process.

[0122] This can be done, for example, by means of a mechanical adjustment device, which can be done, for example, by means of a stepper motor or other mechanical adjustment units known per se to those skilled in the art, for example by changing or adjusting a position and / or orientation of the magnetic field source 41 in relation to the magnetron 4 or in relation to the primary target 42, so that the magnetic field strength MFS at the location or in the vicinity of the magnetron 4 or the primary target 42 can be variably set to a predetermined value. Typical magnetic field strengths MFS are, for example, in the range from approximately 50 Gauss to approximately WOOGauss. In practice, magnetic field strengths MFS in the range from approximately 50 Gauss to 600 Gauss are advantageously selected for the HiPIMS process, whereas typical magnetic field strengths MFS in the DCMS process are often in the range from approximately 300 Gauss to WOOGauss.

[0123] Of course, it is also possible that, alternatively or in addition to the previously described mechanical adjustment device, the magnetic field strength MFS can be changed or adjusted in a manner known per se by varying a current through the electromagnetic coil via an electromagnetic coil, which can be provided in the vicinity of the magnetron 4 and / or the primary target 42, so that the magnetic field strength MFS at the location or in the vicinity of the magnetron 4 or the primary target 42 can be variably adjusted to a predetermined value.

[0124] In principle, in addition to the previously mentioned possibilities, other measures known to those skilled in the art can also be taken to change the magnetic field strength MFS at the location of the magnetron 4 or at the location of the primary target 42 during a coating step. For example, to produce a gradient layer and / or to optimally adjust the magnetic field strength MFS at the magnetron 4 and / or at the primary target 42 for the implementation of the HiPIMS sputtering process and / or the DCMS sputtering process.

[0125] And of course, it is also possible that with another magnetron 400, if available, the strength of a magnetic field on the other magnetron 400 can also be adjusted as described above.

[0126] For the deposition of a HiPIMS layer HS, the first power supply unit 7 in the operating state can provide a sequence consisting of a plurality of HiPIMS discharge pulses 5 of high power density with pulse duration TI to the magnetron 4 for carrying out a HiPIMS sputtering process in a HiPIMS mode.

[0127] To deposit a DCMS layer DS on the substrate 1, the first power supply unit 7 can alternatively also be operated in a different operating state for performing a pulsed and / or unpulsed DCMS sputtering process in a DCMS mode. The first power supply unit 7 is then operated such that the magnetron 4 is operated with one or a plurality of low-power-density DCMS discharge pulses 6 with a pulse duration T2 to form the DCMS layer. An unpulsed DCMS can also be selected.

[0128] The second power supply unit 8 is electrically connected to the magnetron 400, which comprises a magnetic field source 401 and a primary target 402 with a coating material 403. In the operating state, the second power supply unit 8 can supply the second magnetron 400 with electrical energy for performing a sputtering process in a manner well known to those skilled in the art.

[0129] In principle, it is possible for the second magnetron 400 to be operated by means of the second power supply unit 8, as described above, in the same way as the first magnetron 4. However, it is also possible to operate the magnetron 400 according to any other known sputtering method, with or without the support of a magnetic field source 401.

[0130] The coating device B is shown in Fig. 1 in a HiPIMS mode, since only the first power supply unit 7 is in operation and provides exclusively a sequence of HiPIMS discharge pulses 5 to the magnetron 4 or the primary target 42, while the power supply unit 8 is not in operation.

[0131] The substrates 1 to be coated are advantageously provided here, but in certain special cases not absolutely necessary, in a manner known per se to the person skilled in the art on a rotating substrate holder 9, so that a uniform coating of the substrates 1 can be ensured.

[0132] The rotating substrate holder 9 is advantageously, but also fundamentally not necessary, connected to an electrical bias voltage supply 10 so that the rotating substrate holder 9 can be electrically biased to a predeterminable bias voltage.

[0133] In addition, identical or different sputter gases 2, 21, 22, or predeterminable mixtures thereof, can be supplied to the process chamber in a known manner. Sputter gas 21 is used in the HiPIMS sputtering process, while sputter gas 22 is used to carry out the DCMS sputtering process.

[0134] Since the coating device B of Fig. 1 is currently operated in a HiPIMS mode, the process chamber 3 is flooded with the sputter gas 21.

[0135] Examples of commonly used sputtering gases include noble gases such as argon or krypton or other well-known sputtering gases.

[0136] If the layer system S is to be deposited on the substrate 1 using a reactive sputtering process, which is the case in the specific example shown in Fig. 1, the same or different process gases HPG, DCG, or predeterminable mixtures thereof can optionally be supplied to the process chamber in a known manner. The process gas HPG is used in the HiPIMS sputtering process, while the process gas DCG is used to carry out the DCMS sputtering process.

[0137] Since the coating device B of Fig. 1 is currently operated in a HiPIMS mode, the process chamber 3 is flooded with the process gas HPG.

[0138] Examples of frequently used process gases include reactive gases such as C2H2, Ar, N2, O2 or other reactive gases known to those skilled in the art.

[0139] In principle, the magnetron 4 and the second magnetron 400 can comprise identical or different coating materials 43, 403. Furthermore, the coating device B according to Fig. 1 has a high-vacuum pumping system, which is not shown here for reasons of clarity. Particularly advantageous, but not necessary, can additionally be provided with a known radiant heater (also not shown here) for heating the substrates to be coated, as well as a likewise known AEGD (Arc Enhanced Glow Discharge) module for ion cleaning the substrates.

[0140] The exemplary embodiment according to Fig. 2c of a very simple layer system S according to the invention was deposited by means of a coating device B according to Fig. 1 in a first process step in a HiPIMS sputtering process using the primary target 42 by depositing the HiPIMS layer HS made of coating material 43 directly onto the substrate 1 using a sequence consisting of a plurality of HiPIMS discharge pulses 5 of high power density with pulse duration T1 according to Fig. 2a. In a second process step, the DCMS layer DS made of the same coating material 43 was then deposited on the HiPIMS layer using one and the same primary target 42 in a pulsed DCMS sputtering process in a DCMS mode using a sequence of a plurality of DCMS discharge pulses 6 of low power density with pulse duration T2 according to Fig. 2b.

[0141] The HiPIMS discharge pulses 5 of the sequence shown in Fig. 2a are rectangular HiPIMS discharge pulses 5 with a pulse duration TI of 5 ms each. Thus, the DCMS duty cycle DUD of the individual DCMS discharge pulses 6 was 5 ms. The HiPIMS discharge pulses 5 were applied to the primary target 42 at intervals of 150 ms, i.e., at intervals of a HiPIMS death time Ti of 150 ms. Thus, the HiPIMS duty cycle DUH of the sequence of HiPIMS discharge pulse 5 and HiPIMS death time Ti is approximately 3.2%. Thus, the HiPMS layer HS of Fig. 2c was deposited with a large number of atomic layers within 60s, which of course corresponds to the total duration of the sequence of HiPIMS discharge pulses 5 of high power density with pulse duration TI according to Fig. 2a.A partial sequence consisting of a HiPIMS duty cycle DUH of a single HiPIMS discharge pulse 5 and a HiPIMS dead time Ti thus totaled 155 ms, meaning that almost 400 individual HiPIMS discharge pulses 5 were used in the total coating time of 60 s, corresponding to a pulse frequency of approximately 6 Hz. The total duty cycle of the total coating time of approximately 60 s also accounts for approximately 3.2%, since the pulse duration TI of the HiPIMS discharge pulses 5 and also the HiPIMS dead time Ti were not changed during the entire coating process, which would of course be possible in principle and is also practiced in specific methods according to the invention. This means that to form the entire HiPIMS layer HS of Fig. 3c, the HiPIMS discharge pulses 5 were only switched on for approximately 3.2% of the total coating time of the HiPIMS layer HS.

[0142] The primary target 42 was a circular primary target 42 with a rather small area of ​​approximately 30cm 2area. The applied rectangular sputter voltage of the HiPIMS discharge pulses 5 was approximately 600V and the current of approximately 30A of the individual pulses was also rectangular, so that a pulse power of 18kW was achieved for each HiPIMS discharge pulse 5, which on the primary target 42 corresponds to a pulse power of 600W / cm 2 corresponds, as can easily be calculated.

[0143] As already mentioned, the DCMS layer DS was then deposited onto the HiPIMS layer HS from the coating material 43 directly onto the HiPIMS layer HS in a DCMS sputtering process in a DCMS mode using a sequence consisting of a plurality of DCMS discharge pulses 6 of low power density with pulse duration T2 according to Fig. 2b.

[0144] The low-power-density DCMS discharge pulses 6 of the sequence of discharge pulses 6 according to Fig. 2b are rectangular DCMS discharge pulses 6 with a pulse duration T2 of 10 Ops each. Thus, the DCMS duty cycle DUD of the individual DCMS discharge pulses 6 was 100 ps, ​​and the DCMS discharge pulses 6 were applied at a spacing of 10 ps, ​​i.e., at a spacing of a DCMS dead time T2 of 10 ps, ​​to the primary target 42. Thus, the DCMS duty cycle DUD of the sequence of DCMS discharge pulse 5 and DCMS dead time Ti is approximately 90%. Thus, the DCMS layer DS of Fig. 2c was also deposited within 60 s, as can be seen in Fig. 2b, which of course corresponds to the total duration of the sequence of 6 low-power-density DCMS discharge pulses with pulse duration T2 shown in Fig. 2b. A subsequence consisting of a duty cycle and a DCMS dead time T2 thus totaled 110 ps, ​​resulting in approximately 550 ps in the total coating time of 60 s.000 individual DCMS discharge pulses 6 were used, corresponding to a pulse frequency of approximately 9 kHz, so that the total duty cycle of the total coating duration of approximately 60 s also accounts for approximately 90%, since the pulse duration T2 of the DCMS discharge pulses 6 and also the DCMS dead time T2 were not changed during the entire coating process, which would of course be possible in principle and is also practiced in specific methods according to the invention. This means that to form the entire DCMS layer DS of Fig. 2c, the DCMS discharge pulses 6 were switched on for approximately 90% of the total coating duration of the DCMS layer DS.

[0145] As already mentioned, a circular primary target 42 with a rather small area of ​​approximately 30cm 2area. The applied rectangular sputtering voltage of the DCMS discharge pulses 6 was approximately 500V and the current of approximately 1.3A of the individual pulses was also rectangular, so that a pulse power of approximately 600W was achieved for each DCMS discharge pulse 6, which on the primary target 42 corresponds to a pulse power of 20W / cm 2 corresponds, as can easily be calculated.

[0146] It should be noted that, as can be seen from Fig. 1, according to the present invention, preferably, but of course not absolutely necessary, one and the same power supply unit 7 can be used when switching between the HiPIMS discharge pulses 5 and the DCMS discharge pulses 6, unlike the case in the prior art, where different power supply units must be used for the HiPIMS process and the DCMS process, which can be read about, for example, in VO Oskirko et al. In Vacuum 181 (2020) 109670. When carrying out a method according to the invention, this can be done, for example, in that the power supply unit 7 comprises a capacitor bank known per se for generating the high power density HiPIMS discharge pulses 5, which is then simply bypassed when switching to the DCMS mode by establishing a direct connection of the DC power supply to the magnetron by switching.As a result, the method according to the invention not only allows layer systems S to be produced with better properties than those known from the prior art, but also the apparatus structure for carrying out a method according to the invention can be significantly simplified.

[0147] It goes without saying that the primary target 42 does not necessarily have to be circular, but can, in principle, have any suitable geometry. Thus, layer systems S according to the invention, including those according to Fig. 2c, were produced, for example, with rectangular primary targets 42.

[0148] In a specific embodiment of a coating method according to the invention, the HiPIMS discharge pulses 5 and / or the DCMS discharge pulses 6 applied to the rectangular primary target 42 were triangular or needle-shaped discharge pulses 5, 6 with pulse durations ranging from a few ps to several hundred milliseconds or even up to seconds, for example, when the DCMS layer DS is to be deposited in an unpulsed DCMS mode. The specific pulse duration to be selected is, as the person skilled in the art knows, determined by the type of discharge pulse (HiPIMS or DCMS discharge pulse) and depends on the coating material 43 and the desired layer properties, such as hardness and elastic modulus. Yield strength, adhesion strength, thermal stability of the layers to be produced, etc. Typical values ​​for HiPIMS discharge pulses 5 are: pulse duration of the HiPIMS discharge pulse 5 e.g. 80ps, dead time Ti between two HiPIMS discharge pulses 5 e.g. 1500ps, pulse frequency 63 Hz, duty cycle approx. 5%.Typical values ​​for DCMS discharge pulses 6 are: pulse duration of the DCMS discharge pulse 6 e.g. 1500ps, dead time T2 between two DCMS discharge pulses 6 e.g. 80ps, pulse frequency e.g. 630 Hz, duty cycle approx. 95%.

[0149] The person skilled in the art will readily understand that the schematically illustrated coating according to Fig. 2c can also be produced with a different coating device B, e.g. a less complex coating device B without a second magnetron 400, in particular without a second power supply unit 8 and possibly even without a bias power supply 10, and in the case of a non-reactive sputtering process also without the use of reactive gases RG, RG1, RG2.

[0150] Furthermore, it goes without saying that in practice a layer system S according to the invention can often comprise a plurality of sequences of identical or different HiPIMS layers HS and DCMS layers DS deposited directly on top of one another, and that further, different layer types deposited by a different sputtering process can also be provided between, below or above a sequence of HiPIMS and DCMS layer sequences deposited directly on top of one another.

[0151] And of course, depending on the requirements or application, the sequence of depositing the HiPIMS layers HS and DCMS layers DS can also be reversed from the schematic shown in Fig. 2c. It is therefore entirely possible for a sequence of different layers to be deposited first, followed by the HiPIMS layer HS on top of the DCMS layer DS.

[0152] At this point, it should be noted that when reference is made to "pulse shapes" in this application, such as rectangular, needle-shaped, or triangular pulses, this refers to the temporal shape of the current of the discharge pulses. The applied voltage is generally always rectangular, but in special cases it can, of course, have any other suitable shape. For clarity, this will be briefly explained using Fig. 3a to Fig. 3f.

[0153] Figs. 3a to 3f schematically illustrate some selected possible pulse shapes of current and voltage, which in practice are of particular importance for the formation of HiPIMS discharge pulses 5, but can of course also be used for the formation of DCMS discharge pulses 6 and can be advantageously employed in the implementation of the methods according to the invention. In the diagrams of Figs. 3a to 3f, the negative target voltage U and the target current I are plotted upwards on the ordinate, while time is plotted on the abscissa. The solid line U p represents schematically the time course of the voltage and the dashed line l p schematically the time course of the current of the HiPIMS discharge pulses 5 and the DCMS discharge pulses 6. In Fig. 3a, both the voltage U p as well as the current l pof the discharge pulse 5, 6 has a rectangular shape, which is why such pulses are referred to as rectangular discharge pulses. Fig. 3b shows a typical triangular pulse. The current l p of the discharge pulse 5, 6 increases in the form of a ramp linearly with time t, while the voltage U p has a rectangular shape. Fig. 3c shows two consecutive needle-shaped discharge pulses 5, 6. The current l p As a function of time t, the voltage rises rapidly in the form of a sharp needle to a peak value and then drops abruptly to zero. The time course of the voltage U pis again rectangular. Fig. 3d shows a schematic representation of a rectangular discharge pulse according to Fig. 3a, which is preceded by a likewise rectangular preparation pulse or pre-ionization pulse, with which a pre-ionization of the neutral particles of the sputter gas 2, 21, 22 and / or the reactive gases RG, RG1, RG2 can be achieved before the actual sputter discharge pulse 5, 6. Fig. 3e shows a further special pulse shape, in which a first triangular discharge pulse 5, 6 according to Fig. 3b is followed by an oppositely polarized rectangular pulse with a positive voltage. Finally, Fig. 3f shows a so-called bipolar pulse sequence in which an oppositely polarized needle-shaped pulse with a positive voltage follows between two needle-shaped discharge pulses 5, 6 according to Fig. 3c.

[0154] All of these pulse shapes and also combinations and variants thereof, along with other pulse shapes known per se, which cannot all be presented in detail here for reasons of clarity, can be advantageously used within the framework of a coating method according to the invention, and the person skilled in the art understands which pulse shapes he has to select in order to produce a layer system S according to the invention with the desired properties.

[0155] The person skilled in the art will readily understand that all general and specific embodiments discussed within the scope of this application can also be suitably combined with one another depending on the application and requirement, and that other possible embodiments, which cannot all be presented within the scope of this application for reasons of space, are also encompassed by the invention.

Claims

1. Coating method for the deposition of a layer system (S) on a substrate (1), wherein at least one HiPIMS layer (HS) and one DCMS layer (DS) are deposited on the substrate (1) by means of magnetron sputtering, and an evacuable process chamber (3) containing a sputtering gas (2, 21, 22) with an anode and a magnetron (4) designed as a cathode, comprising a magnetic field source (41) and a primary target (42) with a coating material (43) is provided, characterized in that with one and the same primary target (42) in any order and alternately one after the other, the HiPIMS layer (HS) is deposited by a HiPIMS sputtering process in a HiPIMS mode by means of a sequence consisting of a plurality of HiPIMS discharge pulses (5) of high power density with pulse duration (T1) with at least one atomic layer from the coating material (43), and the DCMS layer (DS) is deposited by a pulsed and / or unpulsed DCMS sputtering process in a DCMS mode by means of a DCMS discharge pulse (6) of low power density with pulse duration (T2) to form the DCMS layer (DS) from the coating material (43) is deposited.

2. Coating method according to claim 1, wherein in HiPIMS mode the power density of the HiPIMS discharge pulse (5) on the primary target (42) is in a range of 0.05kW / cm 2 and 10kW / cm 2 , preferably 0.1 kW / cm 2 and 5kW / kW / cm 2 , in particular 0.2 kW / cm 2 up to 3 kW / cm 2, particularly preferably at approx. 0.4 kW / cm 2 or 2 kW / cm 2 is selected, and / or wherein in HiPIMS mode in the sequence of HiPIMS discharge pulses (5) the pulse duration (TI) of the HiPIMS discharge pulse (5) is selected between 5ps and 20ms, preferably between 20ps and 10ms, in particular at approximately 50ps to 5ms.

3. Coating method according to one of the preceding claims, wherein in HiPIMS mode a HiPIMS death time (Ti) in the sequence of HiPIMS discharge pulses (5) between two consecutive HiPIMS discharge pulses (5) is selected between 100ps and 500ms, preferably between 250ps and 250ms, in particular between approximately 500ps and 150ms, and / or wherein a HiPIMS duty cycle (DUH) of a sequence of HiPIMS discharge pulse (5) and HiPIMS death time (T1) is selected between 0.5% and 20%, preferably between 1% and 10%, particularly preferably between approximately 2% to 6% of the duration of the sequence of HiPIMS discharge pulse (5) and HiPIMS death time (T1) and / or wherein in a sequence of HiPIMS Discharge pulses (5) and HiPIMS death time (Ti), the pulse duration (TI) of the HiPIMS discharge pulse (5) and / or the duration of the HiPIMS death time (Ti) and / or the HiPIMS duty cycle (DUH) is changed during the deposition of the layer system (S) according to a predeterminable scheme.

4. Coating method according to one of the preceding claims, wherein in DCMS mode the power density of the DCMS discharge pulse (6) on the primary target (42) is in a range of 1W / cm 2 and 50W / cm 2 , preferably between 2W / cm 2 and 30W / cm 2 , particularly preferably of approx. 5W / cm 2 up to 25W / cm 2 is selected, and / or wherein in the pulsed and / or unpulsed DCMS mode the pulse duration (12) of the DCMS discharge pulse (6) is selected between 1 ps and 10 ms, preferably between 5 ps and 500 ps, ​​in particular at approximately 20 ps or 200 ps.

5. Coating method according to one of the preceding claims, wherein in the pulsed DCMS mode a DCMS dead time (T2) in a sequence of DCMS discharge pulses (6) between two consecutive DCMS discharge pulses (6) is selected between 0.5ps and 10ms, preferably between 2ps and 300ps, in particular at approximately 5ps to 100ps, and / or wherein a DCMS duty cycle (DUD) of a sequence of DCMS discharge pulse (5) and DCMS dead time (T2) is selected between 30% and 99%, preferably between 50% and 97%, particularly preferably at approximately 75% or 95% of the duration of the sequence of DCMS discharge pulse (5) and DCMS death time (T2) is selected, and / or wherein in a sequence of DCMS discharge pulses (6) and DCMS death time (T2) the pulse duration (12) of the DCMS discharge pulse (6) and / or the duration of the HiPIMS death time (T2) and / or the HiPIMS duty cycle (DUH) is changed during the deposition of the layer system (S) according to a predeterminable scheme. Coating method according to one of the preceding claims, wherein the HiPIMS discharge pulse (5) of high power density and / or DCMS discharge pulse (6) of low power density is a rectangular and / or a triangular and / or a needle-shaped discharge pulse (5, 6), in particular a bipolar discharge pulse (5, 6) or a bipolar sequence of discharge pulses (5, 6).Coating method according to one of the preceding claims, wherein the HiPIMS layer (HS) is deposited in HiPIMS mode using an HP process gas (HPG) and the DCMS layer (DS) is deposited in DCMS mode using a DC process gas (DCG) different from the HP process gas (HPG), wherein a mixture of a plurality of different reactive gases (RG, RG1, RG2) is preferably used as the HP process gas (HPG) and / or as the DC process gas (DCG), and / or wherein during the deposition of the HiPIMS layer (HS) in HiPIMS mode, a composition of the HP process gas (HPG) and / or during the deposition of the DCMS layer (DS) in DCMS mode, a composition of the DC process gas (DCG) is varied, and / or wherein during the deposition of the HiPIMS layer (HS) in HiPIMS mode, a partial pressure of the HP process gas (HPG) and / or during the deposition of the DCMS layer (DS) in DCMS mode a partial pressure of the DC process gas (DCG) is varied.

8. Coating method according to one of the preceding claims, wherein during the deposition of the HiPIMS layer (HS) in HiPIMS mode, an HP bias voltage (HPV) of the substrate (1) is selected to be different from a DC bias voltage (DCV) during the deposition of the DCMS layer (DS) in DCMS mode and / or wherein during the deposition of the HiPIMS layer (HS) in HiPIMS mode, the HP bias voltage (HPV) is varied and / or during the deposition of the DCMS layer (DS) in DCMS mode, the DC bias voltage (DCV) of the substrate (1) is varied.

9. Coating method according to one of the preceding claims, wherein a magnetic field strength (MFS) of the magnetic field source (41) during the pulsed and / or unpulsed DCMS sputtering method is selected to be different from a magnetic field strength (MFS) of the magnetic field source (41) during the HiPIMS sputtering method.

10. Coating method according to one of the preceding claims, wherein a process time for producing the HiPIMS layer (HS) and / or the DCMS layer (DS) produced in an unpulsed and / or pulsed DCMS sputtering method is in the range from 0.5 s to 10,000 s, preferably 1 s to 5,000 s, in particular from approximately 5 s to 2,500 s and / or wherein a ratio of the proportions of the sum of the layer thicknesses of the HiPIMS layers (HS) divided by the sum of the layer thicknesses of the DCMS layers (DS) produced in an unpulsed and / or pulsed DCMS sputtering method within the overall layer is in a range from 0.02 to 50, preferably in a range from 0.05 to 25, in particular in a range from 0.1 to 9 and / or wherein a thickness of the individual layers variable in a layer thickness in a layer system (S) comprising the HiPIMS layers (HS) and the DCMS layers (DS) produced in an unpulsed and / or pulsed DCMS sputtering process is in a range from 1 nm to 5000 nm, preferably in a range from 2 nm to 500 nm, in particular in a range from 5 nm to 250 nm.

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