Method and apparatus for applying coatings

Abstract

The present invention relates to a method and apparatus (10) and coating (60) for applying a layer (64) to a body (60, 62). The body (60, 62) is placed in a vacuum chamber (12) and supplied with a process gas. A plasma is generated by applying a cathode voltage (V P The plasma is generated in a vacuum chamber (12) by applying a voltage (VB) to the cathode (30) to sputter the target (32). A bias voltage (VB) is applied to the bodies (60, 62) to accelerate the charge carriers of the plasma towards the bodies (60, 62) and deposit them on their surfaces. The bias voltage (VB) is adjusted to achieve the desired properties of the coating (64) in a controlled manner. B ) varies over the coating duration (D). In the layer 64 of the body 60, 62, the material of the layer 64 includes a proportion of a noble gas, and the concentration of the noble gas in the layer 64 varies across the layer thickness.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for applying a layer to a body. Place In particular, the present invention relates to coatings produced by cathode sputtering. [Background technology]

[0002] It is known to apply surface coatings to bodies or parts of bodies in order to improve their mechanical or chemical properties. In particular, in the case of tools or parts that are subject to wear, it is known to apply coatings to functional surfaces. In particular, hard material layers are known as coatings.

[0003] In addition to CVD methods, PVD coating methods, especially cathode sputtering methods, are known for producing thin coatings.

[0004] WO 2014 / 063676 A1 describes a component with a coating consisting of chromium, nitrogen, and carbon, which is applied by PVD by cathodic arc deposition. A noble gas is introduced into the vacuum chamber, and ion etching is first carried out using a bias voltage of -800 to -1200 V. The bias voltage is then set to a lower value and the layer is applied (deposited). Argon can be used as the noble gas, and neon has lower internal stresses than embedded argon.

[0005] WO 2013 / 045454 A2 describes a method and apparatus for coating a substrate. Magnetron cathodes equipped with sputtering targets are arranged in a vacuum chamber. Some of the cathodes are HIPIMS cathodes, i.e., they are operated with power in the form of voltage pulses from a HIPIMS power supply. A bias voltage is applied to the substrate to be coated, which in a preferred embodiment has a pulse synchronized with the voltage pulse at the cathode so as to be applied during at least a portion of the period characterized by a large number of metal ions generated by the HIPIMS pulse at the cathode. Thus, a smaller amount of process gas, e.g., argon, is embedded in the layer compared to pulses applied due to longer or continuous DC bias.

[0006] US2008 / 0135401A1 describes a method for producing a coating on a substrate using a magnetron cathode with a current of 0.1 to 10 A / cm. 2 An apparatus for sputtering a target at a current density between 0.1 and 0.2 is described. The apparatus includes a power supply connected to a magnetron and a capacitor connected to the power supply. A first switch connects the power supply to the magnetron to charge the magnetron in coordination with a first pulse. A bias device is connected to the substrate to set a substrate bias. The bias is applied, for example, as RF power in a pulsed mode and synchronized with the HIPIMS pulse. A synchronizer synchronizes the frequency and time delay of the first pulse.

[0007] EP3457428A1 describes a method and apparatus for processing semiconductor substrates. A pulse synchronization controller is connected between a pulsed RF bias generator and a HIPIMS generator. A first timing signal is sent from the pulse synchronization controller to the pulsed RF bias generator and the HIPIMS generator. A sputtering target and an RF electrode on a substrate carrier are energized based on the first timing signal and de-energized at the end of the timing signal. A second timing signal is sent from the pulse synchronization controller to the pulsed RF bias generator, and the electrode is energized and de-energized without energizing the target based on the second timing signal. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication WO2014 / 063676A1 [Patent Document 2] International Publication WO2013 / 045454A2 [Patent Document 3] U.S. Patent Application Publication US2008 / 0135401A1 [Patent Document 4] European Patent Application Publication EP3457428A1 Summary of the Invention [Problem to be solved by the invention]

[0009] The object is in particular to provide a method and an apparatus for applying a layer to a body, by which desired layer properties can be achieved in a controlled manner. Place The purpose is to provide. [Means for solving the problem]

[0010] This object is achieved by the method according to claim 1, and Claim 14 The device described in Place The dependent claims refer to advantageous embodiments of the invention.

[0011] The inventors started from the observation that when producing layers by cathode sputtering while applying a pulsed voltage to the cathode, the layer composition can be determined differently depending on the time course of the bias voltage. Depending on whether the bias voltage is applied as a DC voltage or as a pulsed voltage, and in the case of a pulsed voltage, as a function of its temporal synchronization with the pulse at the cathode, the components present in the plasma at different times can be selected in a controlled manner and used to form the layer. In particular, when the time course of gas ions present in the plasma differs from that of metal ions, as in the HIPIMS method, the ratio of gas ions to metal ions can be set in a controlled manner by the time course of the bias voltage.

[0012] In contrast to known teachings of achieving a desired composition of a layer by an appropriate time course of bias voltage that remains the same over the duration of the coating, the inventors propose achieving different compositions of the layer over the thickness of the layer in a controlled manner through variation of the time course of bias voltage over the duration of the coating. This is because, contrary to the previous understanding that gas ions in a layer are generally undesirable and should always be minimized, the inventors have recognized that depending on the desired application of the body, the layer structure, the general layer properties, the type of substrate, etc., the proportion of gas ions in certain regions of the layer, e.g., in this case the interface region of the layer surface, or the intermediate region of the layer, can actually be advantageous, as long as that proportion can vary with the thickness of the layer and can be set in a controlled manner.

[0013] The gas ions under consideration are primarily ions of noble gases, in particular argon, which are used as process gases in vacuum chambers.

[0014] It has thus been shown that a relatively high proportion of argon results in layers with very high hardness and high internal stresses, i.e., hard and brittle layers, whereas layers without or with a low proportion of argon are relatively ductile. Surprisingly, it has been shown that in some applications, such as hard machining, layers with high internal stresses at least at the layer surface achieve particularly good results, such as high cutting performance. On the other hand, layer proportions that are rather ductile due to a low proportion of argon have very favorable properties, for example in the interface region, for example to achieve good adhesion to the substrate, or in the region of the layer surface, depending on the intended use of the body, for example as a tool, for example with regard to tribological properties and run-in behavior.

[0015] The method according to the invention for applying (depositing) a layer on a body, in order to allow controlled setting of the desired layer formation and the resulting properties, comprises placing the body in a vacuum chamber, supplying a process gas, such as a noble gas, preferably argon, and activating one or more cathodes to generate a plasma and sputter at least one target. The cathode is preferably a magnetron cathode, in particular an unbalanced magnetron, and is provided with a target material, preferably made of one or more metals, which material is sputtered in such a way that the plasma contains gas ions and metal ions (magnetron sputtering).

[0016] According to the invention, at least one cathode is operated not with a constant voltage but with a pulsed cathode voltage having cathode pulses spaced apart in time. Preferably, one or more cathodes are operated according to the HIPIMS method (High Power Impulse Magnetron Sputtering), in which short cathode pulses of high voltage are applied to achieve very high peak powers. Here, the HIPIMS method is understood to mean operation in particular within the parameter ranges described below as part of possible exemplary embodiments.

[0017] During at least a portion of the coating duration, a bias voltage is applied to the body to be coated so that the charge carriers of the plasma are accelerated towards the body and deposited as a layer on its surface. The method according to the invention is characterized in that the time course of the bias voltage is varied during the coating duration.

[0018] The time course of the bias voltage can be, in the case of a DC voltage, at least partially (in sections) a constant time course or a variable time course, in particular a pulsed time course. The variation of the time course during the coating duration is , ren In the case of a periodic time course that varies continuously over time, the change in frequency or phase position According to the present invention, the change in time course can be Different at various times or intervals during the coating duration duration and / or As explained, the composition of the layer can be affected by the time course of the bias voltage. While, for example, with a constant bias voltage, all ions in the plasma are uniformly accelerated toward the body, with a pulsed bias voltage, the bias pulse is synchronized in time with the cathode pulse, i.e., applied at the same frequency and with a fixed phase relationship, so that ion species present in the plasma at a selected time can be selected and accelerated toward the item (object) depending on the duration and temporal position of the pulse.

[0019] Thus, a bias voltage having a time course that varies over the duration of the coating can have a pulsed curve in sections or throughout, and the synchronization with the cathode pulse can vary over the duration of the coating. Similarly, the bias voltage time course can be a DC voltage curve in one or more temporal sections, while in other sections a pulsed time course can be applied.

[0020] According to the present invention,The time course of the bias voltage is pulsed during at least a portion of the coating duration, i.e., the bias voltage comprises bias pulses that are synchronous with the cathode pulses, i.e., applied at the same (or respective, or multiple) frequency and fixed phase relationship. The pulses are preferably DC voltage pulses, i.e., an at least essentially constant bias voltage is preferably applied during the pulse duration. The time relative to the cathode pulses at which the bias pulses are effective can therefore be characterized by their respective pulse durations and their temporal positions relative to the cathode pulses (i.e., the time difference between the start of each of the pulses before or after the start of the cathode pulse, which time difference can also be zero). Variation of the time course of the bias voltage during the coating duration according to the invention Is, Ka Varying the duration and / or synchronization (i.e., time difference, for example) of the bias pulse relative to the sword pulse Influenced in this way , where the change in duration and / or synchronization can be abrupt or continuous, for example in the form of a ramp curve.

[0021] In either case, varying the bias voltage over time results in different conditions for layer growth at different times or intervals during the coating duration, such that the layer growth progresses, resulting in a layer with varying structure and / or composition across its thickness. Thus, it is possible to achieve particularly suitable properties in various regions of the layer, such as good adhesion to the substrate, a hard or smooth surface, etc.

[0022] The apparatus according to the present invention is suitable for carrying out the method according to the present invention. It comprises a vacuum chamber with a body carrier, a process gas supply source, and a cathode with a target. The cathode is connected to a cathode power supply, and the body or its carrier is connected to a controllable bias power supply, respectively. The cathode voltage with the cathode pulse is generated by a cathode power supply, preferably a HIPIMS power supply, and the bias voltage is generated by a bias power supply. Here, a controller is provided, which can control the bias power supply so that the time course of the bias voltage changes during the coating duration.

[0023] The controller may in particular be a programmable controller, which preferably controls, in addition to the bias power supply, other functions of the coating apparatus, in particular the supply of various cathodes and process and / or reactive gases in a time-dependent manner according to a coating program.

[0024] Ko The coated body can be produced, for example, by the method according to the invention and / or the device according to the invention. The body comprises a substrate, which can be, for example, a base body, made of steel, in particular HSS or CrMo steel, carbide, ceramic material, or cBN (cubic boron nitride). The substrate can be, for example, a tool, in particular for machining, such as a drill, a milling cutter, an indexable insert, a punching or stamping tool, etc.

[0025] A layer of layer material applied by cathode sputtering is disposed on the surface of the substrate. The layer material according to the present invention comprises at least one element from a first group, which includes aluminum (Al), silicon (Si), yttrium (Y), and elements from groups 4-6 of the periodic table according to IUPAC (1988), and at least one element from a second group, which includes nitrogen (N), oxygen (O), carbon (C), and boron (B). The selection of elements from the first and second groups can be referred to as a material system. A preferred material system comprises primarily nitrogen and one or more elements from the first group, in particular titanium (Ti), aluminum (Al), silicon (Si), and / or chromium (Cr). Here, the material system is indicated by adding a hyphen to each element, without indicating chemical bonds. Particularly preferred layer systems are aluminum titanium nitride (Al-Ti-N), titanium nitride (Ti-N), titanium aluminum silicon nitride (Ti-Al-Si-N), titanium aluminum chromium silicon nitride (Ti-Al-Cr-Si-N), titanium boride (TiB2), titanium carbonitride (Ti-CN), titanium aluminum carbonitride (Al-Ti-CN), chromium nitride (Cr-N), zirconium nitride (Zr-N), and titanium carbide (Ti-C). The indicated elements of each material system are preferably listed in order of their relative atomic weights.

[0026] The layer material also contains a proportion (portion) of a noble gas, preferably argon, where in the body according to the invention the concentration of the noble gas in the layer varies across the thickness of the layer, i.e. different concentrations of the noble gas in the layer occur at different positions of the layer depending on the distance of each possible position of the layer from the layer surface or the respective substrate.

[0027] The noble gas is the process gas used when applying layers by cathode sputtering, preferably argon. As mentioned above, it is possible to control the proportion of the process gas in the layer, in particular by appropriately selecting the time course of the bias voltage, so that the desired concentration profile can be set in a controlled manner across the layer thickness.

[0028] Advantageous developments of the method according to the invention relate in particular to the type of variation of the time course of the bias voltage. Advantageously, as explained, the dependence of the proportion of process gas in the layer on the time course of the bias voltage can be achieved by appropriate application. By varying the time course during the coating duration, a desired proportion of process gas in the layer that varies over the thickness of the layer can be achieved in this way.

[0029] The method according to the present invention, and Apparatus according to the present invention for, Various embodiments are possible. Thus, the bias voltage preferably has a pulse-shaped time course during at least the first time interval within the coating duration, i.e., it includes voltage pulses, referred to herein as "bias pulses." The bias pulses are preferably synchronized with the cathode pulses, i.e., have the same frequency (or one frequency is a multiple of the other, which represents synchronization). While synchronization is also possible, in which the bias pulse and the cathode pulse always start at the same time, and the bias pulse introduction times are also possible, the bias pulses preferably occur with a delay time relative to the cathode pulse, i.e., their beginning occurs after the beginning of the cathode pulse. The delay time is, for example, in the range of 5-150 μs and is selected in each case depending on the desired ions. The duration of the bias pulse is, for example, in the range of 30-150 μs, preferably 50-100 μs.

[0030] During the coating duration, further time intervals, which may occur before or after the first time interval, may have a time gap therebetween, and in this case, the bias voltage preferably has a time course that deviates from that of the first time interval. This may be, for example, a pulse curve similar to that of the first time interval, but with a different phase relationship, particularly a different delay time. Similarly, the deviating time course in the other time interval may also be a constant DC voltage (DC bias). The DC bias voltage accelerates all ions in the plasma without exception toward the substrate, and, by appropriate synchronization with the cathode, forms a coating with a relatively high proportion of process gas compared to a pulsed bias voltage. Pulsing allows for a more selective selection of ions, which may, for example, allow a higher proportion of metal ions to be selected in a controlled manner.

[0031] According to an advantageous embodiment, the time course of the bias voltage during the first time interval includes a bias pulse that is synchronized with the cathode pulse and occurs after a first delay time relative to the cathode pulse, and during the second time interval, the bias pulse that is synchronized with the cathode pulse occurs after a second delay time that is offset from the first delay time. Here, the second time interval preferably follows the first time interval in time and can either directly follow it in time or there can be a time gap between the time intervals. The first time interval can be the beginning of the coating duration.

[0032] The time intervals can be short, for example, a few minutes, or can be long, up to several hours. For example, the duration of the first and / or second time intervals can be selected so that the layer grows only a small amount, for example, 0.1 μm, during the time intervals. However, embodiments in which the layer grows up to 3 μm during the first and / or second time intervals are also possible. To achieve individual layer thicknesses in the nano-range, i.e., 5-100 nm, preferably 5-50 nm, the time intervals can be very short, for example, 20-360 seconds, preferably 20-180 seconds. To achieve individual layer thicknesses in the micro-range, i.e., 0.5-10 μm, preferably 0.5-2 μm, the time intervals can be selected, for example, in the range of 50-1200 minutes, preferably 50-360 minutes.

[0033] For example, one of the delay times can be in the range of 30-80 μs, such that a relatively high proportion of metal ions and a relatively low proportion of gas ions are present in the plasma, while another delay time can be selected, such as 0-20 μs or 90 μs or more, such that a relatively high proportion of gas ions are present in the plasma. For example, the delay time in a first time interval early in the coating duration can be shorter so that a greater proportion of metal ions are used to form the layer, while the delay time in a second time interval later in the coating duration can be longer so that a greater proportion of gas ions are incorporated into the layer.

[0034] Therefore, preferably, a synchronized bias pulse having a delay time relative to the cathode pulse is generated during at least one time section or during the entire coating duration, where the delay time is varied, which may occur abruptly (abruptly) in steps or may occur (more or less) continuously.

[0035] To form a transition layer with gradually changing layer properties, the change in delay time during the transition time interval can involve a section or the entire coating duration, for example, stepwise or continuously from a first value to a second value, where the first value is higher or lower than the first value. The course can be linear, for example in the form of a ramp, but deviations are also possible. The length of the transition time interval during which the change occurs can be selected so that the layer grows to 0.5 μm-20 μm.

[0036] In another preferred embodiment, the variation can oscillate stepwise or continuously between two values ​​over the duration of one section or the entire coating period, thereby forming, for example, a multilayer structure, preferably comprising more than two individual layers, within the layer. Here, the delay time can assume a first value during the first switching subinterval and a second value deviating from it during the second switching subinterval. During the switching time interval, the first and second switching subintervals can follow each other one or more times. Thus, the duration of the first and / or second switching subintervals, respectively, can be selected so that the layer grows by 5 nm-2 μm during that time. Preferred examples are individual layer thicknesses of, for example, 5-100, preferably 5-50 nm, for nanolayer structures, and individual layer thicknesses in the range of, for example, 0.1-2 μm, for multilayer structures, with a total of 6-40 individual layers within the layer.

[0037] A further preferred embodiment relates to an apparatus according to the invention. The apparatus thus preferably comprises one or more HIPIMS cathodes, i.e., cathodes connected to a HIPIMS power supply. The HIPIMS power supply preferably comprises a capacitor for supplying power for the HIPIMS pulses and a charging device for the capacitor. The power supply is preferably power-regulated (stabilized). Targets of different compositions can be attached to multiple cathodes arranged in a vacuum chamber. It is therefore possible to deposit layers of different compositions one on top of the other in a continuous process, without interrupting the vacuum, by switching the associated power supplies on or off (or increasing or decreasing the power, respectively). This is preferably done via a controller.

[0038] In the following, embodiments will be described with reference to the drawings. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a schematic diagram of a coating system with an electrical circuit. [Figure 2] FIG. 10 is a diagram showing the time progression of a cathode pulse and a bias pulse. [Figure 3] FIG. 1 is a diagram showing the amount and type of ions in the plasma in a time series starting from the trigger of the cathode pulse. [Figure 4a] FIG. 4 shows the temporal superposition of various time courses of bias voltage with the number and type of ions in the plasma in FIG. 3. [Figure 4b] FIG. 4 shows the temporal superposition of various time courses of bias voltage with the number and type of ions in the plasma in FIG. 3. [Figure 4c] FIG. 4 shows the temporal superposition of various time courses of bias voltage with the number and type of ions in the plasma in FIG. 3. [Figure 4d] FIG. 4 shows the temporal superposition of various time courses of bias voltage with the number and type of ions in the plasma in FIG. 3. [Figure 5] 1 shows an exemplary embodiment of a coating in a schematic representation of the surface area of ​​a coated body. [Figure 6a] FIG. 1 illustrates a first exemplary embodiment of a coating as a time progression diagram. [Figure 6b] FIG. 1 shows a first exemplary embodiment of a coating in a schematic representation of the surface area of ​​a coated body. [Figure 7a] FIG. 10 illustrates a second exemplary embodiment of a coating as a time progression diagram. [Figure 7b] FIG. 2 shows a second exemplary embodiment of a coating in a schematic representation of the surface area of ​​a coated body. [Figure 8a] FIG. 10 illustrates a third exemplary embodiment of a coating as a time progression diagram. [Figure 8b] FIG. 10 shows a third exemplary embodiment of a coating in a schematic representation of the surface area of ​​a coated body. [Figure 9a] FIG. 10 illustrates a fourth exemplary embodiment of a coating as a time progression diagram. [Figure 9b] FIG. 10 shows a fourth exemplary embodiment of a coating in a schematic representation of the surface area of ​​a coated body. [Figure 10a] FIG. 10 illustrates a fifth exemplary embodiment of a coating as a time progression diagram. [Figure 10b] FIG. 5 shows a fifth exemplary embodiment of a coating in a schematic representation of the surface area of ​​a coated body. [Figure 11a] FIG. 10 illustrates a sixth exemplary embodiment of a coating as a time progression diagram. [Figure 11b] FIG. 6 shows a sixth exemplary embodiment of a coating in a schematic representation of the surface area of ​​a coated body. [Figure 12] 1A-1C illustrate exemplary embodiments of a tool having a coating. DETAILED DESCRIPTION OF THE INVENTION

[0040] 1 shows a schematic diagram of a coating system 10. The coating system 10 includes a vacuum chamber 12 equipped with a vacuum system 14, shown here schematically, which is capable of creating a vacuum inside the vacuum chamber 12. The vacuum chamber 12 also has a process gas supply 16 and a reactive gas supply 18, which allow a process gas, in a preferred embodiment argon, and a reactive gas, such as nitrogen, to be introduced into the vacuum chamber 12.

[0041] A rotating substrate table 20 with a planetary rotating substrate carrier 22 is arranged in the vacuum chamber 12. Substrates 60, i.e., base bodies, e.g., tools (see FIG. 12), to be coated are respectively placed on the substrate carrier 22 and are brought into electrical contact with the substrate carrier 22 and the substrate table 20.

[0042] Also disposed within the vacuum chamber 10 are magnetron cathodes 30, 34 and an anode 28. 30, Each of the sputtering chambers 32, 36 includes an unbalanced magnet system (not shown) and a planar sputtering target.

[0043] The magnetron cathodes 30 , 34 , the substrate table 20 , and the anode 28 are each connected to the external electrical circuitry of the coating system 10 from outside the vacuum chamber 12 by electrical feedthroughs through the walls of the vacuum chamber 12 .

[0044] In the illustrated embodiment, the magnetron cathode 34 is wired as a DC cathode, i.e., connected to a DC power supply 44 that supplies it with a DC voltage relative to the anode 28. The anode 28 is connected to an anode power supply 46 that supplies it with a DC voltage relative to the conductive walls of the vacuum chamber 12. The magnetron cathode 30 is wired as a HIPIMS cathode, i.e., connected to a pulsed voltage V PThe substrate table 20 is electrically connected to a HIPIMS power supply 40 which applies a bias voltage V B is connected to a bias power supply 42 which supplies

[0045] The coating system 10 is equipped with a controller 48, which controls the bias power supply 42 and the HIPIMS power supply 40 as described in detail below. The controller 48 also controls the entire process, i.e., the vacuum system, the rotational drive of the substrate table 20, the supply of process and reactive gases, and all other power supplies 44, 46. The controller is programmable, i.e., it has a memory for a coating program, in which the procedures and method steps described below are specified.

[0046] It should be noted that the illustrated electrical circuitry and matching of electrodes with the coating system 10 should be understood to be purely exemplary. In alternative embodiments, for example, the HIPIMS cathode 30 can be connected to the anode 28, or, for example, the anode 28 can be omitted and the chamber wall can be wired as all cathodes and the anode of the substrate table 20. Multiple DC cathodes 34 can be provided, or none can be provided at all. In addition to the HIPIMS cathode 30, additional HIPIMS cathodes can be provided within the vacuum chamber 12, each connected to its own HIPIMS power supply. Targets 32, 36 of the same or different composition can be attached to the cathodes 30, 34.

[0047] The HIPIMS power supply 40 supplies power to the HIPIMS cathode 30 according to the HIPIMS method, i.e., a supply voltage V P , current I P , and the instantaneous power has a short and very high pulse-shaped time course.

[0048] As an example, the period duration T of such a periodic time course is shown in Figure 2. The voltage V applied to the HIPIMS cathode 30 P is a negative voltage. The time course is P The period includes a substantially rectangular voltage pulse 50 of period duration T. For the remainder of the period, no voltage is applied.

[0049] As an example, preferred parameters for the HIPIMS method are set out below: Voltage V P is applied periodically, for example at a frequency of 100-10,000 Hz, preferably 500-4000 Hz, and therefore the period duration T is preferably in the range of 250-2000 μs. P is preferably small, for example less than 200 μs, preferably 40-100 μs. Preferably, the duty cycle T P / T is in the range of 1%-35%, preferably 10-30%, particularly preferably 20-28%. The operation of the HIPIMS cathode 30 is preferably carried out in a power-regulated manner, for example at values ​​of 3-20 kW per HIPIMS cathode, preferably 10-16 kW per cathode. The peak current occurring during the pulse is preferably 0.4-2 A / cm with respect to the front surface of the target 32. 2 , and more preferably 0.5-0.8 A / cm 2 is.

[0050] When the coating system 10 is operated to apply (deposit) a coating 64 to a functional area 62 of a substrate 60, as shown by way of example in FIG. 12 for a milling cutter 66, the substrate 60 to be coated is placed on the substrate carrier 22 in the vacuum chamber 12. A vacuum is created in the vacuum chamber 12. After optional preparation steps (e.g., heating, surface treatment of the substrate 60 by ion etching, sputter cleaning of the cathodes 30, 34, etc.), a plasma is generated by operating one or more HIPIMS cathodes 30 (and, optionally, one or more DC cathodes 34 simultaneously) while sputtering the targets 32, 36. Constituents of the plasma deposit on the surface of the substrate 60 to form a layer 64, where positively charged ions of the plasma are deposited by a negative bias voltage V B The beam is accelerated toward the substrate surface by the

[0051] FIG. 3 shows, as an example, time-resolved ion measurements in the plasma after a cathode pulse 50 is initiated at t=0 μs for a HIPIMS cathode 30 equipped with a target 32 ​​made of titanium and aluminum, while supplying argon as the process gas. As shown, the plasma contains various species of metal and gas ions, but here the different species exhibit time courses that deviate from each other. Thus, the number of argon ions increases relatively rapidly to a local maximum at approximately 35 μs, then decreases, and increases significantly again later in the course starting at approximately 90 μs. Metal ions increase somewhat more slowly, reaching a near maximum in the range of t=50-60 μs, and then decreasing again.

[0052] As shown schematically, three time sections 54, 56, 58 can be defined, with a first time section 54 (approximately 0-40 μs) in which gas ions predominate, followed by a second time section 56 (approximately 40-100 μs) in which metal ions predominate, followed by a third time section 58 (from approximately 100 μs) in which gas ions are significantly more prevalent.

[0053] The positive gas and metal ions in the plasma are driven by a negative bias voltage V B 60 toward the surface of the substrate 60 and become part of the coating 64 deposited thereon. B For a continuous DC voltage of , all ions are selected for layer formation without exception. In Figure 4d, this is shown by the bias voltage V B All three time sections 54, 56, 58 in which is applied constantly are shown as examples, shown cross-hatched.

[0054] Instead of DC bias, the bias voltage V B is the voltage V at the HIPIMS cathode 30 P The bias voltage V can be applied in pulsed time course in synchronization with the time course of the B Such a pulse time course is shown by way of example in Figure 2. The bias voltage V B is the bias pulse duration T between cathode pulses 50 B In this case, the bias pulse 52 has a delay time T D The time is delayed by

[0055] By appropriately selecting the time synchronization between the cathode pulse 50 and the bias pulse 52, i.e., in particular the bias pulse duration T B and delay time T D By appropriately selecting , it is possible to select among the gases and metal ions present in the plasma at different times.

[0056] For example, the bias pulse duration T B is about 60 μs and the delay time T D The effect of presetting the time course of the bias pulse 52, where V is about 40 μs, is shown in FIG. 4a. That is, the bias pulse 52 is synchronized with the second time section 56, where the metal ions dominate. BBy presetting such a time course, a coating 64 with a very low percentage of argon is produced.

[0057] Using a HIPIMS target 32 ​​made of titanium, silicon, and aluminum, nitrogen was supplied as the reactive gas for depositing a coating 64 formed in the Ti-Al-Si-N material system, and the bias voltage V B In an experiment with a time course of 0.03 at% (atomic percent) argon was obtained in the coating 64. The coating 64 had an internal stress of -1.6 GPa and a hardness of 26 GPa.

[0058] In comparison, with the application of a DC bias (FIG. 4d) and otherwise identical configuration and process control, the argon fraction in coating 64 was 0.12 at %, with an internal stress of −5.3 GPa and a hardness of 30 GPa.

[0059] bias voltage V B As another example of the possible time course of the bias pulse duration T B is about 60 μs and the delay time T D shows a time course of about 100 μs, whereby the bias pulse 52 is synchronized with the third time section 58 where the gas ions predominate. B By presetting this time course, a coating 64 with a high percentage of argon is produced.

[0060] As another example, Figure 4c shows a bias pulse duration T B is about 100 μs, and the delay time T D is about 20μs, and the bias voltage V B The time course of the bias voltage V BBy presetting this time course, a coating 64 having a moderate percentage of argon is produced.

[0061] Therefore, the bias voltage V B By presetting the time course, it is possible to influence the layer composition, in particular the argon percentage, in a controlled manner to a value between a minimum percentage (Figure 4a) and a maximum percentage (Figure 4b).

[0062] As a result, the properties of the layer, in particular the internal stress of the coating 64 and its hardness, are significantly affected.

[0063] Coating system 10 applies coatings 64 to each of substrates 60. These coatings grow over an ongoing coating duration D, each having a thickness S beginning at the surface of substrate 60. Controller 48 controls both HIPIMS power supply 40 and bias power supply 42 during coating duration D, thereby applying offset bias voltages V at various time intervals during coating duration D. B This results in a variation in the composition of the coating 64 over the layer thickness S, i.e., a different proportion of argon depending on the time course set in each case.

[0064] In the bias pulse 52 (FIG. 2) synchronized with the cathode pulse 50, the time course is a delay time T D and bias pulse duration T B As an example, the bias pulse duration T B can now be set to a fixed value, for example 60 μs, but the delay time T D varies depending on the coating duration D.

[0065] An exemplary embodiment is described below with reference to Figure 5. In this embodiment, the bias voltage V BA two layer coating 64 is deposited on the substrate 62 by a single change of synchronization.

[0066] coating 64 To provide this, first the body 60 to be coated, formed of a substrate material 62, for example a 6 mm diameter double-blade ball end mill formed of carbide (WC / Co) with a cobalt content of 6 at %, is placed on the substrate carrier 22 in the vacuum chamber 12.

[0067] The coating system 10 includes a substrate table 20 and a Four Two HIPIMS cathodes 30 are attached to the cathodes 30. Two cathodes 30 are arranged adjacent to each other and each has a target 32 ​​made of a titanium aluminum material (e.g., 60 at% Ti, 40 at% Al), and the remaining two have targets 32 made of a titanium silicon material (e.g., 80 at% Ti, 20 at% Si).

[0068] A vacuum is generated by operating the vacuum system 14. The interior of the vacuum chamber 12 is heated. The surface of the substrate 60 is cleaned by gas ion etching while the cathodes 30, 34 are activated. The targets 32, 36 are prepared by sputter cleaning.

[0069] At the start of coating, first, a first layer 80a is deposited on the substrate 60 for a first time interval. For this purpose, two cathodes 30 with Al-Ti targets are operated with a cathode power of 12 kW each, while the remaining two cathodes 30 with Ti-Si targets are not operated initially. The power is supplied in the form of HIPIMS cathode pulses 50 with a frequency of 4000 Hz and a pulse length of 70 μs. This applies a bias voltage V B A bias voltage V B is a 60V bias pulse 52 and a 40µs bias pulse duration T Band cathodic pulse 50 synchronized with a 40 μs delay time T D occurs with.

[0070] The first layer 80a is deposited at a layer rate of about 1 μm / h to reach a thickness of 1.5 μm after a first time interval duration of 1.5 hours. D is a 40 μs pulse bias voltage V B This allows for a controlled selection of metal ions to form coating 64, while only a small number of argon ions are present, which initially increase in the time curve after each pulse (FIG. 4a). The argon content of coating 64 in first layer 80a is 0.03 at% or less, resulting in an internal stress of -1.6 GPa or less.

[0071] Subsequently, during a second time interval, a second layer 80b is deposited on the first layer 80a to a thickness of 1.5 μm. To this end, in a further execution of the coating program, the controller 48 controls the power supplies of the two cathodes 30 with Ti-Si targets so that they are operated with a cathode power of 12 kW each, while the remaining two cathodes 30 with Al-Ti targets are not operated. The HIPIMS parameters of the power supplies during the second time interval are the same as those during the first time interval, i.e., a frequency of 4000 Hz and a pulse length of 70 μs.

[0072] However, at the transition from the first time interval to the second time interval, the bias voltage V B The time course of is changed so that during the second time interval, the voltage is applied as a continuous DC voltage rather than a pulsed time course, so that argon ions are incorporated into the coating 64 to a greater extent.

[0073] The second layer 80b is deposited at a layer rate of about 1 μm / h to reach a thickness of 1.5 μm after the duration of the second time interval of 1.5 hours. BThus, the argon content of the coating 64 in the second layer 80b is at least 0.12 at % to produce an internal stress of at least 5.3 GPa.

[0074] As a result, layer 64 is bi-layered, with the first layer 80a having low internal stress and high ductility, resulting in very good layer adhesion, while the outer second layer 80b provides a high degree of adhesion to the coated body. 60 This ensures a hard and smooth surface. Ball end mills coated in this way are suitable for milling high carbon steels above HRC60 without emulsion.

[0075] In the following, further individual exemplary embodiments are presented in which coatings 164, 264, 364, 464, 564, 664 are produced on a substrate 62, and the composition and properties of the coating are varied over time during the coating duration, particularly with respect to the bias voltage V B In the following description, all further details of the coating procedure, such as fitting of targets and specific parameters and time durations, are not mentioned, as it is concerned with showing a main embodiment that can be applied to different material systems with different parameters.

[0076] 6a and 6b show a first exemplary embodiment of a coated body 166 having a two-layer coating 164. FIG.

[0077] When depositing the coating 164, the bias voltage V B is applied in each case in a pulsed time course with the bias pulse 52 synchronized with the cathode pulse 50. However, as shown in FIG. 6a, the synchronization is varied throughout the coating duration D. That is, the delay time T D is initially 40 μs in the first time interval 170a and then 110 μs in the second time interval 170b.

[0078] FIG. 6b shows a schematic cross-sectional view of a corresponding coated body 166 with a coating 164 formed on a substrate 62. The coating 164 includes a first layer 180a with a low percentage of argon on the substrate 62 and a second layer 180b with a higher percentage of argon on top of the first layer 180a. Because of the low percentage of argon, the first layer 180a is fairly ductile and has low internal stress, and therefore can function as a good adhesive to the substrate 62. The second outer layer 180b has a high percentage of argon and therefore has a high hardness. Such layers have been shown to be particularly suitable for tools used in demanding machining applications, such as drill and milling tools, including end mills, ball end mills, and indexable inserts.

[0079] 7a and 7b show a second exemplary embodiment with a process control that is essentially the opposite of the first exemplary embodiment. In the second exemplary embodiment, the delay time T D is changed from an initial 110 μs in a first time interval 270a to 40 μs in a subsequent second time interval 270b. The resulting coating 264 on the coated body 260 has a first layer 280a with a high argon percentage and a second layer 280b with a low argon percentage.

[0080] Such a coating 264 may be particularly advantageous for coated bodies 260 provided for tribological applications. 280a The first layer 280b acts as a hard base layer with internal stresses. The second layer 280b acts as the top layer on top of that and has good break-in properties due to its high ductility. Potential applications include thread cutting taps, forming taps, drills, punches, etc. Chin There are punching and stamping tools.

[0081] 8a and 8b schematically illustrate a third exemplary embodiment, which employs a delay time T that is stepped over a coating duration D in three time intervals 370a, 370b, and 370c. D In this case, the delay time T D increases stepwise, as in the first exemplary embodiment. The resulting coating 364 on the coated body 360 has a first layer 380a with a low percentage of argon, a second layer 380b with a medium percentage of argon, and a third outer layer 380c with a high percentage of argon.

[0082] 9a and 9b show a fourth exemplary embodiment, in which the delay time T D Thus, the argon percentage does not change stepwise over the coating duration, but rather gradually, for example in the form of a linearly increasing ramp. The resulting coating 464 of the coated body 460 therefore exhibits an argon content that increases in the direction from the substrate 62 toward the surface. The coating 464 therefore has low internal stress in the interface region with the substrate 62, promoting adhesion. In the surface region, the coating 464 has a high hardness, which is particularly advantageous for tools in machining applications.

[0083] 10a and 10b show a fifth exemplary embodiment having the opposite process control to the fourth exemplary embodiment, i.e., the delay time T D And the argon content in the coating 564 of the coated body 560 becomes constantly lower over the coating duration D, here in the form of a linearly decreasing ramp.

[0084] Figures 11a and 11b show Sixth 1 shows an exemplary embodiment, where the delay time T D changes rapidly in a first time interval 670a and a second time interval 670b, which are repeated one after the other, during the coating duration D. In the first time interval 670a, a delay time TD is 40 μs, and in the second time interval 670b, the delay time T D is 110μs.

[0085] As a result, the resulting coating 664 of the coated body 660 has alternating succession of first layers 680a with low argon content and second layers 680b with high argon content in the layer thickness direction S. The layer deposited directly on the substrate 62 in the interface region is the first layer 680a, which has low internal stress to promote adhesion. The outermost layer in the surface region is the second layer 680b, which has high hardness.

[0086] The thickness of layers 680a, 680b is predetermined by the duration of time intervals 670a, 670b at a constant layer rate. By selecting the time duration of time intervals 670a, 670b and the number of switches accordingly, it is possible to produce, for example, a multilayer coating 664 in which individual layers 680a, 680b are, for example, 0.1-2 μm thick. Similarly, a nanolayer coating 664 in which individual layers 680a, 680b are, for example, 5-50 nm thick can be produced by switching time intervals 670a, 670b more rapidly.

[0087] Table 1 below shows other exemplary embodiments of the coating.

[0088] [Table 1] TIFF0007789696000002.tif183170

[0089] The coatings according to Example 1 can be applied to tools such as milling cutters, drills, indexable inserts (replaceable inserts) or the like, made of steel, stainless steel or CrMo steel as substrate material, as standard layers with little internal stress in the interface region and high internal stress towards the surface.

[0090] In Example 2, they are layers (especially smooth layers) for special applications with little internal stress in the interface region and high internal stress towards the surface. They can be applied to tools such as milling cutters, drills, indexable inserts (replaceable inserts) for machining aluminum, titanium or non-ferrous metals. Potential applications are demanding machining applications for special materials where material buildup must be avoided, i.e., smooth layers are required.

[0091] According to Example 3, the argon content is high at the beginning of deposition and decreases toward the surface. Such layers can be used, for example, for threading taps, forming taps, drills, or punching and stamping tools. For example, steel, stainless steel, or CrMo steel can serve as the substrate material. These layers are characterized by a hard base layer with high internal stress and a soft top layer with good running-in properties and low internal stress. Possible applications for tools with such layers are, in particular, tribological applications.

[0092] In Example 4, the argon content gradually increases toward the surface of the coating, resulting in a smooth and visually appealing coating. Such layers can be used on all types of machining tools and all types of substrate materials. Potential applications include, for example, decorative applications. A colored top layer can be applied in a separate process.

[0093] The layers according to Examples 5, 6, and 7 provide, on the one hand, a modified composition of each subsequent layer, and, on the other hand, a modified argon content. This can be achieved, for example, by attaching targets made of different materials to various HIMIPS magnetron cathodes in a vacuum chamber and controlling them separately from each other. For example, in Example 5, the change from the first to the second layer can be achieved by turning off the power to the first cathode, which is equipped with an Ai-Ti target, and simultaneously turning on the power to the second cathode, which is equipped with a Ti-C target. The switching on and off of the correspondingly attached cathodes can be performed suddenly or gradually, in the form of a short ramp.

[0094] In Example 6, an Al-Ti target is attached to the first cathode and a Ti-C target is attached to the second cathode, with switching between the two cathodes occurring when the layer is changed.

[0095] In Example 7, a Ti—C target is attached to the second cathode, and the supply of nitrogen as a reactive gas is turned off at the start of the deposition of the second layer.

[0096] In all three Examples 5, 6, and 7, the argon content decreases rapidly at the beginning of the second layer. The layers thus produced can be applied to tools such as threading taps, forming taps, drills, punching and stamping tools made from substrate materials such as steel, stainless steel, or CrMo steel. Applications include, for example, tribological applications, where it is desirable for the produced layers to have a hard base layer with internal stresses and a softer top layer with good break-in properties and low internal stresses.

[0097] The layer according to Example 8 can be used for the same types of tools, substrate materials, and applications as those according to Examples 5, 6, and 7. In contrast to the abrupt, stepwise decrease in argon content over the duration of the coating, according to Example 8, the argon content decreases gradually, i.e., in the form of a ramp.

[0098] The layers according to Examples 9, 10, and 11 also provide for a modified composition of the layer, which is achieved by different mounting of the target and cathode with correspondingly altered electrical control. The layers can be applied to tools such as end mills, ball end mills, drills, or indexable inserts (replaceable inserts), made of substrate materials such as high-carbon steel, Ni-based alloys, titanium alloys, or stainless steel. Possible applications of the resulting layers, which are hard and smooth (characteristics of the second layer as a functional layer with a high argon content) and have good adhesion (characteristics of the first layer acting as an adhesive with a low argon content), are particularly demanding machining applications.

[0099] Examples 12, 13, and 14 can be used as decorative layers on any type of functional layer, or as layers for better wear detection. Therefore, such layers can be applied in combination with other layers, for example, as a top finish. Machining tools of any type can be considered as substrates made of, for example, steel, cast iron, CrMo steel, or stainless steel. The lower layer serves as the functional layer, and the upper layer serves as a decorative color layer, for example, gold, which allows for better wear detection.

[0100] Example 5, with its graded argon content, illustrates the same application and substrate alternative as Examples 12, 13, and 14. The aforementioned variation with a second layer of carbon (C) produces a gray top layer, which allows for easy visual wear detection.

[0101] In the multilayered layer according to Example 16 and the nanolayered layer according to Example 17, layers with a high argon content (i.e., high hardness, high internal stress) alternate with layers with a low argon content. This alternating layering prevents crack formation and reduces the internal stress of the entire system. Such layers can be applied to all types of machining tools and substrate materials such as steel, especially stainless steel, high-carbon steel, CrMo, Ni-based alloys, titanium alloys, etc.

[0102] In summary, the present invention can be implemented by a variety of coating methods, coating apparatuses, and resulting coated bodies, each with specific advantages for various applications. The embodiments detailed herein each represent examples and should be understood as illustrative, not limiting. Various modifications and alternatives to the illustrated embodiments are possible. For example, the aforementioned embodiments can be implemented with a wide variety of layer materials, i.e., with offset target mounting, with various reactive gases, or without reactive gases. The advantage always remains that by controlling and setting the properties of the various layer regions, the resulting coating can be optimized for each application.

Claims

1. A method of applying a layer (64) to a body (60), comprising the steps of: placing the body (60) in a vacuum chamber (12); Supplying a process gas into the vacuum chamber (12); A periodic cathode voltage (V) is applied with a cathode pulse (50) of period duration (T). Ｐ ) to activate at least one cathode (30) to generate a plasma in the vacuum chamber (12) and sputter a target (32); A bias voltage (V) is applied to the body (60) so that the charge carriers of the plasma are accelerated towards the body (60) and deposited on its surface during the coating duration (D). Ｂ ) is applied, The bias voltage (V Ｂ ) the time course of the coating duration (D) includes a bias pulse (52) during at least a portion of the coating duration (D), the bias pulse (52) being synchronized with the cathodic pulse (50) within the period duration (T); The bias voltage (V Ｂ ) is varied during the coating duration (D) by varying the duration and / or synchronization of the bias pulse (52) with respect to the cathode pulse (50) between a plurality of the period durations (T); A method characterized by:

2. The proportion of process gas in the layer (64) is controlled by the bias voltage (V Ｂ ) depending on the time course of The change in the time course during the coating duration (D) changes the proportion of process gas in the layer (64).

2. The method of claim 1 .

3. The bias pulse (52) occurs at the same frequency as the cathode pulse (50).

2. The method of claim 1 .

4. The bias voltage (V Ｂ ) the time course includes a bias pulse (52) during at least a first time interval; The bias voltage (V Ｂ ) is a DC voltage at least in another time interval; 4. A method according to any one of claims 1 to 3.

5. The bias voltage (V Ｂ ) includes a bias pulse (52) in at least a first time interval (170a, 270a, 370a); The bias pulse (52) is synchronized with the cathode pulse (50); The bias pulse (52) is delayed by a time (T Ｄ ) occurs later, 5. A method according to any one of claims 1 to 4.

6. During the first time interval (170a, 270a, 370a), the bias pulse (52) is delayed by a first time delay (T) relative to the cathode pulse (50). Ｄ ) occurs later, The bias voltage (V Ｂ The time course of the cathode pulse (50) is synchronized with the cathode pulse (50) at least during a second time interval (170b, 270b, 370b) and has a second delay time (T) relative to the cathode pulse (50). Ｄ ) a bias pulse (52) occurring with a delay of The first and second delay times (T Ｄ ) are different, 6. The method of claim 5.

7. the durations of the first time interval (170a, 270a, 370a) and the second time interval (170b, 270b, 370b) are selected such that during each of them the layer grows by at least 0.1 μm; 7. The method of claim 6.

8. the first time interval (170a, 270a, 370a) is before the second time interval (170b, 270b, 370b) within the coating duration (D); The delay time (T Ｄ ) is shorter than in the second time interval (170b, 270b, 370b); 8. The method according to claim 6 or 7.

9. the first time interval (170a, 270a, 370a) is the beginning of the coating duration (D); 9. The method of claim 8.

10. The delay time (T Ｄ ) changes stepwise or continuously from a first value to a second value during a transition time interval; 10. The method according to any one of claims 5 to 9.

11. the duration of the transition time interval is selected so that the layer grows by 0.5 μm-20 μm during that time; 11. The method of claim 10.

12. In the first switching subinterval (670a), the delay time (T Ｄ ) has a first value, and in the second switching subinterval (670b), the delay time (T Ｄ ) has a second value, In the switching time interval, first and second switching subintervals (670a, 670b) alternate; 12. A method according to any one of claims 5 to 11.

13. the duration of the first and / or second switching subintervals is selected such that the layer grows by 5-500 nm during this time, respectively; 13. The method of claim 12.

14. The cathode (30) is operated by applying the cathode pulse (50) according to the HIPIMS method, and the process gas is argon.

14. The method according to any one of claims 1 to 13.

15. 1. An apparatus for applying a layer to a body, comprising: a vacuum chamber (12) comprising a carrier (22) for said body (60), a process gas supply (16), and at least one cathode (30) having a target (32); During the coating duration (D), the cathode (30) is supplied with a periodic cathode voltage (V) in a cathode pulse (50) of periodic duration (T). Ｐ a pulsed cathode power supply (40) for supplying A bias voltage (V Ｂ a controllable bias power supply (42) for applying a The bias voltage (V Ｂ a controller (48) for controlling the bias power supply (42) such that the time course of the coating duration (D) includes a bias pulse (52) during at least a portion of the coating duration (D), the bias pulse (52) being synchronized with the cathode pulse (50) within the period duration (T); The bias voltage (V Ｂ ) is varied during the coating duration (D) by varying the duration and / or synchronization of the bias pulse (52) with respect to the cathode pulse (50) between a plurality of the period durations (T); An apparatus characterized in that

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