Method, control device, computer program and storage medium

Abstract

According to various embodiments, a method (150) can comprise: determining (101) an actual state of a result of a two-sided coating process, by means of which a first layer stack is formed on a front side of a substrate and a second layer stack is formed on a rear side of the substrate, on the basis of: a model, which implements a link between the result and a spectral response of the result, and an actual state of the spectral response, an indication of the difference between a first sub-process of the coating process, by means of which the first layer stack is formed, and a simultaneous second sub-process of the coating process, by means of which the second layer stack is formed, and controlling (103) the coating process on the basis of the actual state of the result.

Description

[0001] Description

[0002] Method, control device, computer program and storage medium

[0003] Various embodiments relate to a method, a computer program, a control device and a storage medium.

[0004] In general, a substrate, for example a glass substrate, a metal substrate and / or a polymer substrate, can be processed, e.g. coated using a coating process, so that the chemical and / or physical (e.g. optical) properties of the substrate can be changed. By means of the coating process (e.g. by means of chemical and / or physical vapor deposition), a layer stack can be formed, for example, in order to specifically adjust the optical properties of the resulting result, for example its optical spectrum. For example, a vacuum coating system can be used to deposit one or more than one stack of multiple layers (also referred to as layer stacks) by means of the coating process, the optical interaction of which should fulfill requirements for a reflection or transmission characteristic or a color impression.One application of this is, for example, the coating of optical components such as lenses, prisms or mirrors.

[0005] In general, such a coating process can be controlled, for example, using an optical measurement taken at regular intervals on the time-dependent actual state of the coating process result. However, the complexity of such control increases significantly with the number of interacting layers, so computer-implemented models are used to monitor the progress of the coating process based on optical measurements (also referred to as monitoring).

[0006] According to various embodiments, it has been recognized that the options for monitoring the coating process are limited in various application cases, including when the substrate is to be coated on both sides, for example with layer stacks of similar structure, if possible simultaneously, and / or made of transparent material. In particular, with a layer stack made of transparent material, a reflection measurement as an optical measurement is more difficult because the optical measurement covers both layer stacks, which is also the case, for example, with a transmission measurement. Clearly, with increasing similarities between the layer stacks, the risk increases that they will be difficult to distinguish from one another based on the optical measurement, so that the coating process is controlled on an inaccurate basis and, as a result, high demands on the result can only rarely be met.For example, the layer thicknesses determined using optical measurement can no longer be clearly assigned to the respective stack, making reliable control impossible. In this context, it was clearly recognized that this risk can be reduced if, in addition to the optical measurement, one or more differences between the layer stacks are taken into account. This consideration clearly improves the data basis (e.g., through additional boundary conditions) for the control. A particular challenge, however, arises when these layer stacks have a uniform target structure, both are recorded by the optical measurement, and are to be formed simultaneously (e.g., with a temporal overlap).In this case, it was recognized that a usable difference between the layer stacks can be created by ensuring that their actual state differs from each other at the time or at any time the optical measurement is taken. This can be achieved, for example, by forming the two layer stacks at different speeds or at different times. Such an approach maximizes the temporal overlap between the formation of the two layer stacks, so that the coating of the substrate takes less time overall and is therefore more cost-effective.

[0007] According to various embodiments, a method, a computer program, a control device and a storage medium are provided which enable one or more of the following:

[0008] - that both sides of the substrate can be coated simultaneously, which increases the throughput of the coating process and thus its cost-effectiveness, without the need for retooling;

[0009] - that high demands on the result are not only achieved when the layer stacks are deposited one after the other;

[0010] - that a high calibration effort is avoided, since higher fluctuations of the sub-processes, which occur anyway in reality, can be accepted in order to stimulate this difference;

[0011] - that additional sensors are not necessarily required (e.g. for reflection measurement) to improve the data basis.

[0012] It shows

[0013] Figure 1 shows a processing arrangement according to various embodiments in a schematic side view or cross-sectional view;

[0014] Figures 2A and B each show the processing arrangement according to various embodiments in a schematic side view or cross-sectional view;

[0015] Figures 3A and B each show the result of the coating process according to various embodiments in a schematic side view or cross-sectional view; Figures 4A and B each show a spectral response according to various embodiments in a schematic diagram;

[0016] Figures 5A to C each show a spectral response according to various embodiments in a schematic diagram;

[0017] Figures 6A and B each show the coating process according to various embodiments in different schematic diagrams; and

[0018] Figure 7 shows a vacuum arrangement according to various embodiments in a schematic plan view or cross-sectional view.

[0019] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology such as "top," "bottom," "front," "back," "fore," "rear," etc., will be used with reference to the orientation of the described figure(s). Since components of embodiments can be positioned in a number of different orientations, the directional terminology is for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention.It is understood that the features of the various exemplary embodiments described herein may be combined with one another unless specifically stated otherwise. The following detailed description is therefore not to be construed in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0020] Throughout this description, the terms "connected," "attached," and "coupled" are used to describe both a direct and an indirect connection (e.g., resistive and / or electrically conductive, e.g., an electrically conductive connection), a direct or indirect connection, and a direct or indirect coupling. In the figures, identical or similar elements are provided with identical reference numerals where appropriate.

[0021] The actual state of an entity (e.g., a device, a system, or a process) can be understood as the actual or sensorily detectable state of the entity. The desired state of the entity can be understood as the desired state, i.e., a specification. Control can be understood as an intentional influence on the current state (also referred to as the actual state) of the entity. The current state can be changed according to the specification (also referred to as the desired state), e.g., by changing one or more operating parameters (then also referred to as manipulated variables) of the entity, e.g., by means of an actuator. Regulation can be understood as controlling, whereby a change in state is additionally counteracted by disturbances. For this purpose, the actual state is compared with the desired state, and the entity is influenced in such a way, e.g.,by means of an actuator, so that the deviation of the actual state from the desired state is minimized. In contrast to pure forward-directed sequential control, the control thus implements a continuous influence of the output variable on the input variable, which is effected by the so-called control loop (also referred to as feedback). In other words, this can be understood as meaning that, alternatively or in addition to open-loop control (or actuation), closed-loop control can be used, or, alternatively or in addition to open-loop control, closed-loop control can be used.

[0022] The state of a controllable device (e.g., a coating device) or a controllable process (e.g., the coating process) can be specified as a point (also referred to as the working point or operating point) in a space (also referred to as the state space) spanned by the variable parameters of the device or process (also referred to as operating parameters). The state of the device or process is thus a function of the respective value of one or more operating parameters, which thus represents the state of the device or process. The actual state can be determined based on a measurement (e.g., using a measuring element) of one or more operating parameters (then also referred to as a controlled variable). Examples of an operating parameter of a process (e.g.,of the coating process or a sub-process thereof) include: a time at which the process is started or continued; a time at which the process is interrupted or ended; a period of time for which the process is interrupted or carried out; a speed at which the process is carried out; a temperature to which the process is exposed; a pressure to which the process is exposed. The rate can, for example, be expressed as a rate (change per time), e.g. as a coating rate (e.g. specified as the increase in layer thickness on the substrate per time) and / or as an emission rate (e.g. measured as the increase in layer thickness on a rate sensor per time). In relation to a sputtering device, the emission rate is also referred to as the atomization rate.

[0023] The state of the system can thus represent the state of each coating process in the system, and vice versa. The actual state of each process (e.g., the coating process or each sub-process thereof) can be detected using a measuring element (e.g., having one or more sensors). One or more sensors can be used for each controlled variable, each sensor configured to detect a variable (also referred to as a measured variable) that represents the controlled variable or that is the controlled variable.

[0024] A sensor (also called a detector) can be understood as a transducer that is set up to record a property of its environment (e.g. qualitatively or quantitatively) corresponding to the sensor type as a measurand, e.g. a physical property, a chemical property and / or a material condition. The measurand is the physical quantity (then also called the controlled variable) to which the measurement by the sensor applies. Depending on the complexity of the environment to be measured by the sensor, the sensor can be set up to distinguish between two or more discrete states of the measurand (also called a measuring switch), or to record the measurand quantitatively. An example of a recorded measurand is a gas inflow rate (e.g. recorded as a flow rate), the actual state of which can be converted into a measured value by the sensor.

[0025] Each sensor can be part of a measurement chain that has a corresponding infrastructure (e.g., a processor, storage medium, and / or bus system, etc.). The measurement chain can be configured to control the corresponding sensor, process its detected measurement value as an input value, and, based on this, provide an electrical signal as an output value that represents the detected input value. For example, the output value can indicate the measured value. The measurement chain can be implemented, for example, by means of a so-called control device.

[0026] In the following, reference is made, among other things, to reactive processes in which a chemical reaction takes place. For example, one or more than one process (e.g.

[0027] Coating process or sub-process thereof) may comprise a reactive sputtering process which is provided with one or more than one reactive gas (e.g. a number of m reactive gases) which forms a chemical bond with the coating material (also referred to as target material), which (then also referred to as layer-forming material) is deposited on a substrate (where, for example, m=1, m>1 or m>2). It can be understood that the coating process does not necessarily have to be reactive. The quantities which represent materials involved in the chemical reaction in a reactive coating process may, in a non-reactive coating process, represent corresponding other materials which are not involved in a chemical reaction. Accordingly, what is described for the reactive coating process can apply analogously to a non-reactive coating process and vice versa.

[0028] According to various embodiments, reference is made to physical vapor deposition (PVD) as an exemplary coating process, e.g., comprising a sputtering process. It can be understood that what is described for PVD can apply analogously to chemical vapor deposition (CVD). In contrast to CVD, in PVD a solid material is first converted into the gas phase (also referred to as the gaseous phase or vapor), and a layer is formed by means of this gas phase. In PVD, the gas phase of the target material can optionally be chemically reacted with a reactive gas to form a chemical compound, which is incorporated into the layer or forms it. During the chemical reaction in PVD, two or more materials are thus combined to form the chemical compound.

[0029] In chemical vapor deposition, a gaseous starting compound (also called precursor or reactant) is split into at least two reaction products, of which at least one reaction product is incorporated into the layer. Optionally, one reaction product is removed from the coating process as excess (e.g., using a pump). Optionally, CVD can be performed using a plasma, in which the splitting of the precursor occurs.

[0030] A plasma can be formed using a so-called working gas (also referred to as a plasma-forming gas). According to various embodiments, the working gas can comprise a gaseous material that is inert, in other words, that participates in few or no chemical reactions. A working gas can, for example, be defined by the target material used and be adapted to it. For example, a working gas can comprise a gas or a gas mixture that does not react with the target material to form a solid. The working gas can, for example, comprise a noble gas (e.g., helium, neon, argon, krypton, xenon, radon) or several noble gases. The plasma can be formed from the working gas, which, for example, essentially causes the sputtering of the target material. If a reactive gas is used, this can have a higher chemical reactivity than the working gas, e.g.,with respect to the target material. In other words, the atomized target material can react more quickly with the reactive gas (if present) (i.e., form more reaction product per unit time) than with the working gas (e.g., if it reacts chemically with the working gas at all). The reactive gas and the working gas can be supplied together or separately as a process gas (e.g., as a gas mixture), for example, by means of the gas supply device.

[0031] The reactive gas can comprise a gaseous material that reacts with the target material (e.g. with the sputtered target material) and / or can be incorporated into the deposited layer by means of a chemical reaction. If, for example, a target material is used that can form a nitride (e.g. aluminum nitride), or if a nitride of the target material is to be deposited, the reactive gas can comprise nitrogen or be formed from it. If, for example, a target material is used that can form an oxide (e.g. aluminum oxide), or if an oxide of the target material is to be deposited, the reactive gas can comprise oxygen or be formed from it. The reactive gas can, for example, comprise a gas mixture (reactive gas mixture) of several gases or be formed from them, which react with the target material and / or the deposited layer, e.g. oxygen and nitrogen, e.g. when an oxynitride (e.g.Aluminum oxynitride) is to be deposited. The reactive gas mixture may, for example, comprise predominantly (i.e., more than 50%) oxygen, e.g., for depositing an oxide or oxynitride. Examples of the reactive gas include: molecular oxygen, molecular nitrogen, nitric oxide, carbon oxide, hydrogen sulfide, methane, gaseous hydrocarbon, molecular fluorine, molecular chlorine, ozone, or another gaseous material.

[0032] In an exemplary implementation, the device can, for example, comprise a vacuum-assisted coating (e.g., forming the individual layers of the layer stack) using an electrical discharge (also referred to as plasma). For this purpose, a plasma-forming (e.g., inert) gas can be ionized using a cathode, whereby a material to be deposited (also referred to as target) of the cathode can be atomized (also referred to as sputtering) using the plasma thus formed. The atomized material can then be brought to a substrate on which it can be deposited and form a layer (also referred to as coating). Modifications of cathode sputtering include sputtering using a magnetron, so-called magnetron sputtering, e.g., reactive magnetron sputtering, or non-reactive magnetron sputtering.The formation of the plasma can be assisted by means of a magnetic field, which can influence the ionization rate of the plasma-forming gas. The magnetic field can be generated by means of a magnet system, whereby the magnetic field can be used to form a plasma channel in which the plasma can form. For sputtering, the coating material can be arranged as a solid (also referred to as a target) between the plasma channel and the magnet system so that the target can be penetrated by the magnetic field and the plasma channel can form on the target. The plasma-forming gas (e.g. argon) can, together with an optional reactive gas, form a process gas in which sputtering takes place. Reactive magnetron sputtering can be carried out using the reactive gas.

[0033] In the following, reference is made to a method which comprises controlling a coating process, which can be done, for example, by controlling one or more actuators (also referred to as control intervention). In this context, reference is also made to a control device or code segments. The control device (also referred to as a regulating device) can be configured to implement one or more of the methods described herein. For this purpose, the control device can have a processor which is configured to implement the respective method. For example, the processor can be configured to output corresponding instructions for controlling. Alternatively or additionally, the processor can be configured to receive and process corresponding instructions and signals.The instructions received by the processor can be implemented, for example, using code segments stored on a non-transitory data memory. For example, the code segments can include at least one instruction and / or one or more specifications that, when executed by the processor, cause the processor to perform one of the methods.

[0034] The term "control device" can be understood as any type of logic-implementing entity, which can, for example, comprise a processor (and, for example, corresponding circuitry) that can, for example, execute software stored in a storage medium, in firmware, or in a combination thereof, and issue instructions based thereon. The control device can, for example, be configured using code segments (e.g., software). The control device can, for example, comprise or be formed from a programmable logic controller (PLC).

[0035] According to various embodiments, a data storage device (more generally also referred to as a storage medium) may be a non-transitory data storage device. The data storage device may, for example, comprise or be formed from a hard disk and / or at least one semiconductor memory (such as read-only memory, random access memory, and / or flash memory). The read-only memory may, for example, be an erasable programmable read-only memory (also referred to as EPROM). The random access memory may be a non-volatile random access memory (also referred to as NVRAM - "non-volatile random access memory"). For example, one or more of the following may be stored in the data storage device: the code segments implementing the method, a model or at least parameters thereof, one or more indications of a difference between two sub-processes of the coating process.

[0036] The term "processor" can be understood as any type of entity that allows the processing of data or signals. The data or signals can, for example, be processed according to at least one (i.e., one or more) specific function performed by the processor. A processor can include or be formed from an analog circuit, a digital circuit, a mixed-signal circuit, a logic circuit, a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), an integrated circuit, or any combination thereof.Any other type of implementation of the respective functions, which are described in more detail below, can also be understood as a processor or logic circuit, for example virtual processors (or a virtual machine) or a plurality of decentralized processors, which are connected to one another, for example by means of a network, are spatially distributed in any way and / or have any share in the implementation of the respective functions (e.g. distribution of the computing load among the processors). The same generally applies to differently implemented logic for implementing the respective functions. It is understood that one or more of the method steps described in detail herein can be carried out (e.g. realized) by a processor, by one or more specific functions carried out by the processor.

[0037] The term "actuator" (e.g., having an actuator) can be understood as a transducer configured to influence a state, a process (e.g., a coating process), or a device in response to the actuation of the actuator. The actuator can convert a control signal supplied to it (by means of which the actuation occurs) into mechanical movements or changes in physical quantities such as pressure or temperature. An electromechanical actuator, for example, can be configured to convert electrical energy into mechanical energy (e.g., through movement) in response to the actuation.

[0038] An actuator can be set up to influence the actual state (also referred to as the operating point) of the process (e.g. its manipulated variable), which is supplied by the actuator. The influence can be direct or indirect. For example, the manipulated variable and the controlled variable can differ from one another. The controlled variable (e.g. pressure) can then be a function of one or more than one manipulated variable (e.g. gas inflow). For example, the actuator can change an electrical voltage as the manipulated variable by means of which a plasma is supplied, so that as a result a coating rate, an atomization rate or a layer thickness is changed as a controlled variable. For example, the actuator can change an inflow rate of a gas as the manipulated variable, so that as a result a pressure is changed as a controlled variable.For example, the actuator can change the inflow rate of a working gas as a control variable, resulting in a change in the atomization rate or layer thickness as a control variable. For example, the actuator can change the inflow rate of a reactive gas as a control variable, resulting in a change in the chemical composition of the plasma or a coating as a control variable.

[0039] With regard to the control of an actuator, reference is made, among other things, to the more easily understood manipulated variable or its control value, which is influenced by the actuator. The description can apply analogously to the control variable or its control value, which are fed to the actuator for control, and vice versa. The actuator acts as a converter, converting a control signal into the manipulated variable or its control value, so that the control value is a function of the control value.

[0040] According to various embodiments, the provided control and / or regulation can be used to stabilize the optical product properties (color, transmission, reflection), e.g. by adjusting the layer thicknesses.

[0041] According to various embodiments, one or each substrate may comprise or be formed from a film and / or a glass plate.

[0042] For example, one of the layer stacks may comprise or be formed from an optical anti-reflection multilayer system. The anti-reflection multilayer system may comprise: a plurality of transparent and / or dielectric materials that differ from one another in their refractive index; a stack of a plurality of multilayer groups that optionally differ from one another in their total layer thickness, each multilayer group comprising a plurality of layers, a first layer comprising or consisting of a first material of the plurality of materials, and a second layer comprising or consisting of a second material of the plurality of materials.

[0043] For example, a layer stack may comprise or be formed from an optical low-emission multilayer system. The low-emission multilayer system may comprise: a dielectric base layer arrangement (e.g. comprising one or more layers) and a dielectric cap layer arrangement (e.g. comprising one or more layers); a functional layer arrangement (e.g. comprising one or more layers) which has a metallic functional layer and is arranged between the base layer arrangement and the cap layer arrangement, wherein the cap layer arrangement optionally comprises at least one protective layer. The protective layer may, for example, comprise a semimetal (e.g. silicon) and / or a non-metal (e.g. nitrogen), a nitride thereof and / or an oxide thereof. In some embodiments, the metallic functional layer may be omitted.

[0044] According to various embodiments, an object (e.g., the substrate, a material, the layer stack, and / or each layer thereof) may be translucent. In the context of this description, the term “translucent” (e.g., transparent or at least translucent) may be understood to mean that the object (e.g., a substrate, a layer, or a material) has a transmittance such that a large portion of the electromagnetic radiation (e.g., light) incident on it passes through it, e.g., more than is absorbed and / or reflected by it. A translucent object may, for example, be translucent (partially translucent). In other words, the transmittance within the transmission range may be greater (e.g., at least twice, three times, five times, or ten times greater) than the reflectance and / or the absorbance, e.g., their sum.

[0045] The transmission coefficient (also called transmittance) can describe the proportion of electromagnetic radiation (e.g. visible light) that passes through the object (e.g. the substrate). The reflectance (also called reflection coefficient) can describe the proportion of incident electromagnetic radiation that is reflected (e.g. re-emitted) by the object. The reflectance can take into account specularly reflected radiation (illustratively reflected back), diffusely reflected radiation and / or re-emitted radiation. The absorptivity (also called absorption coefficient) can describe the proportion of incident electromagnetic radiation that is absorbed (i.e. taken up and / or absorbed) by the object, e.g. by converting it into heat.

[0046] A transparent object (e.g., the substrate, a material, the layer stack, and / or each layer thereof) may have a transmittance (transmission coefficient) that is greater than approximately 50%, e.g., greater than approximately 60%, e.g., greater than approximately 70%, e.g., greater than approximately 80%, e.g., greater than approximately 90%. For example, the transmittance may be in a range between approximately 70% and approximately 99%.

[0047] In general, the transmittance can depend on the wavelength of the electromagnetic radiation, depending on the optical properties of the object. For example, the layer stack can be transparent to one or more wavelength ranges while being non-transparent (also referred to as opaque), i.e., filtering out, one or more additional wavelength ranges. The one or more filtered-out wavelength ranges can be absorbed and / or reflected.

[0048] According to various embodiments, such information about optical properties (e.g.

[0049] Transmittance, reflectance and / or absorption) may be related to a specific wavelength range (also called passband) of electromagnetic radiation, e.g. to that of visible light (i.e. a wavelength range from approximately 380 nm to approximately 780 nm) or to a cut-off wavelength or to 550 nm.

[0050] According to various embodiments, a dielectric object (e.g. material or structure, e.g. layer) can be understood as electrically insulating, e.g. having an electrical conductivity of less than 10' 6Siemens / meter. The dielectric object can, for example, comprise or be formed from an oxidic and / or nitridic ceramic (e.g., as a metal compound). Oxidic can be understood as meaning that the object comprises an oxygen compound (e.g., a metal oxide) or can be formed from it. Nitridic can be understood as meaning that the object comprises a nitrogen compound (e.g., a metal nitride) or can be formed from it. The dielectric object can, for example, be transparent.

[0051] In the context of this description, a metal (also referred to as metallic material) can comprise (or be formed from) at least one metallic element (i.e. one or more metallic elements), e.g. at least one element from the following group of elements: copper (Cu), iron (Fe), titanium (Ti), nickel (Ni), silver (Ag), chromium (Cr), platinum (Pt), gold (Au), magnesium (Mg), aluminium (Al), zirconium (Zr), tantalum (Ta), molybdenum (Mo), tungsten (W), vanadium (V), barium (Ba), indium (In), calcium (Ca), hafnium (Hf) and / or samarium (Sm).

[0052] To perform a two-sided coating process in which the formation of the individual layers is controlled by an optical monitoring system, it may be necessary to deposit the individual layers (also referred to as single layers) one after the other. This is because, especially when the resulting layer stacks on the front and back are identical, the layer thicknesses of the individual layers cannot be clearly determined. Simultaneous coating is then only possible with a timer or by determining the rate using quartz crystals as a rate sensor. This is not sufficient for the requirements of precision optics.

[0053] According to various embodiments, it is achieved that a virtually simultaneous (simultaneous) coating of both sides is possible, independent of the coating system (also referred to as two-sided coating), controlled by optical monitoring. Simultaneous coating can be understood as meaning that the proportion of the total coating process time for which the substrate is coated on only one side is smaller than the proportion of the total coating process time (or 50% thereof, 25% thereof, or 10% thereof) for which the substrate is coated on both sides. The total time of a two-sided coating process is thus shorter than if the same result is achieved using one-sided coating.

[0054] By skillfully selecting the working parameters of the coating process (also referred to as coating parameters), such as the start time of the coating process or sub-processes, sufficient information is provided to determine the layer thicknesses and coating rates in-situ (e.g., without interrupting the vacuum) from an optical spectrum, even when the same layer system (e.g., transparent layers) is deposited on the front and back sides. This will be discussed in more detail below.

[0055] Fig.1 illustrates a processing arrangement 100 according to various embodiments in a schematic side view or cross-sectional view, which has a control device 102 and a vacuum arrangement 104.

[0056] The control device 102 may include at least one (e.g., one or more than one) processor configured to perform the method 150. For example, the control device 102 may be configured to execute code segments (e.g., implementing instructions) that cause the processor to perform the method 150. For example, the code segments may be stored locally on a computer-readable medium of the control device 102, or provided, at least in part, via a cloud. In this regard, it may be understood that what is described for the control device 102 may apply analogously to computer-assisted implementations of the method of a different type, which, for example, do not necessarily require a control device 102 and / or a computer-readable medium.

[0057] The vacuum arrangement 104 may comprise: a vacuum chamber 802, a transport device 112 for transporting a substrate along a transport path in the vacuum chamber 802, a coating device 106 for performing a coating process which is configured for two-sided coating of the substrate (then also referred to as a two-sided coating process), and a measuring element 108.

[0058] An exemplary implementation of the transport device 112 comprises a substrate carrier 110 (also referred to as carrier) arranged in the vacuum chamber 802 and an actuator 112g which is configured to be controlled in response thereto to supply the substrate carrier 110 with a mechanical force by means of which it can be moved (e.g. rotated).

[0059] An exemplary implementation of the substrate carrier 110 comprises one or more than one (e.g., plate-shaped) carrier having one or more than one substrate carrying region 110a, 110b, each substrate carrying region being penetrated by a through-opening and having a support surface extending into the through-opening on which a substrate can rest.

[0060] The or an alternative exemplary implementation of the substrate carrier 110 is rotatably mounted so that the transport path runs along a curved (e.g., self-contained) path. For example, the substrate carrier 110 can perform several revolutions during the coating process, e.g., per layer of the layer stack, or alternatively, several pendulum movements. The method comprises, in 101, determining an actual state of a result of the two-sided coating process (also referred to as coating result), and in 103, controlling the coating process and, based on the actual state of the coating result, optionally in 105, controlling a measuring element 108 for detecting an actual state of a spectral response of the coating result, and optionally in 107, initializing the model (e.g., based on the process difference).

[0061] The coating process can be configured to form two layer stacks (also referred to as coatings), of which a first layer stack is formed on a first side of the substrate by means of a first sub-process, and a second layer stack is formed on a second side of the substrate opposite the first side by means of a second sub-process. To simplify the distinction between the two sides of the substrate and corresponding terms, reference is made to "front side" and "back side" in this regard. It should be understood that this is only exemplary (for example, it is not intended to indicate a preference) and can be interchanged by analogy.

[0062] The desired state of the coating result (e.g., the result at the end of the coating process) comprises: the substrate 250, the first layer stack 302 (also referred to as front-side coating) on ​​the front side of the substrate 250, and the second layer stack 304 (also referred to as back-side coating) on ​​the back side of the substrate 250. It can be understood that the actual state of the coating result may differ from the desired state of the coating result, for example, in one or more than one layer (e.g., per layer stack).

[0063] For ease of understanding, reference is made herein and in particular below, inter alia, to the description of a single layer stack. It can then be understood that what is described here can apply analogously to each of the two layer stacks, for example if they are intended to satisfy an identical requirement, but this does not necessarily have to be the case. Examples of a requirement that at least one (one or each) of the two layer stacks can satisfy include: the spatial sequence of layers of different chemical composition; a chemical composition of one or more layers; a number of layers of different chemical composition; a total thickness; the spectral response.

[0064] The coating device 106 has, e.g., per layer stack of the two layer stacks, at least one (one or more than one) coating material source 106a, 106b, which is configured to carry out the sub-process for forming the layer stack. The transport path can be arranged between two coating material sources 106a, 106b. The at least one coating material source 106a, 106b can have, e.g., per layer of the layer stack, one coating material source. Reference is made herein, by way of example, to two coating material sources per layer stack, i.e., two first coating material sources for forming the front-side coating and two second coating material sources for forming the back-side coating. It can be understood that what has been described here can apply analogously to any different number of coating material sources per layer stack.In general, the number of coating material sources per layer stack can depend on how many layers with different properties are to be formed per layer stack.

[0065] An exemplary implementation of the at least one coating material source 106a, 106b has, e.g. per layer of the layer stack, a sputtering device (and optionally an ion source) as the coating material source 106a, 106b.

[0066] An exemplary implementation of the measuring element is configured to detect a transmission spectrum as a spectral response. For this purpose, the measuring element comprises a source of optical radiation (e.g., a light source) and one or more sensors, between which the transport path runs. It should be understood that what is described for the transmission spectrum can apply analogously to spectra of other types, for example, a reflection spectrum and / or a spectrum determined by ellipsometry (e.g., by means of an ellipsometer).

[0067] The determination of the actual state can be based on a model that implements a link between the coating result (e.g., its state, e.g., its desired state or actual state) and a spectral response (e.g., an estimate thereof) of the result. For example, the model can comprise an algorithm by means of which the state of the coating result and the spectral response can be mapped to one another. Implementations of this can be found, for example, in so-called design software for optical coatings, such as the "OptiLayer" software from OptiLayer GmbH (as of January 2023). This offers, for example, the possibility of simulating the spectral response of a layer stack based on a model of the layer stack that takes into account the individual layers, their sequence, thickness, and optical density.Alternative or additional implementations are explained in DE 10 2018 101 173 and DE 10 2020 124 934.

[0068] Determining 101 the actual state can also be based on an indication of a difference (also referred to as a process difference) between the first sub-process of the coating process (also referred to as the front-side process), by means of which the front-side coating is formed, and a second sub-process of the coating process (also referred to as the back-side process), which takes place simultaneously, and by means of which the back-side coating is formed. The process difference will be discussed in more detail later.

[0069] In an exemplary implementation, the method 150 comprises: determining 101 an actual state of a structure of a multilayer system (as a result of the coating process) comprising a substrate, a first layer stack on a front side of the substrate and a second layer stack on a back side of the substrate, based on: a model which links the structure of the multilayer system to a spectral response (e.g.Transmission spectrum) of the multi-layer system, the sensor-detected actual state of the spectral response, and an indication indicating a difference in an operating point between a first sub-process of the coating process, by means of which the first layer stack is formed, and a second sub-process of the coating process, which takes place simultaneously therewith and by means of which the second layer stack is formed (with which these are initiated, for example); and controlling 105 the first sub-process and / or the second sub-process based on the actual state of the multi-layer system.

[0070] 2A and 2B each illustrate the processing arrangement 100 according to various embodiments 200a, 200b in a schematic side view or cross-sectional view, depicting the substrate 250 and the transport path 111. Furthermore, an exemplary implementation of the coating device 106 is depicted, in which it has two first coating material sources 106a, 116a for forming the front-side coating and two second coating material sources 106b, 116b for forming the back-side coating. Arranged above and below the transport path 111 are a coating material source 106a, 106b configured as a silicon oxide source and a coating material source 116a, 116b configured as a niobium oxide source.

[0071] In the context of a dielectric coating material (e.g., an oxide, a nitride, and / or an oxynitride), it can be understood that the coating material source can be configured to provide a dielectric coating material as a layer-forming material, or can also be configured to emit a metallic coating material which is subsequently converted into the dielectric layer-forming material (e.g., by means of a chemical reaction), for example, after the metallic coating material has been deposited on the substrate.

[0072] Furthermore, the transport path 111 can extend through one or more than one measuring area 282 of the processing arrangement, each measuring area having a light source 202 and a sensor 212 of the measuring element 108.

[0073] Also shown is a spectrometer 262 as an exemplary part of the measuring chain, for example implemented by means of the control device.

[0074] Fig.3A and Fig.3B each illustrate the result of the coating process (also referred to as coating result) according to various embodiments 300a, 300b in a schematic side view or cross-sectional view.

[0075] Each of the two layer stacks 302, 304, between which the substrate 250 is arranged, can comprise a plurality of layers, of which adjacent layers differ from one another in one or more of the following: their layer thickness, their chemical composition, and / or their optical refractive index. Alternatively or additionally, adjacent layers of the plurality of layers can be identical in that they are optically transmissive (e.g., transparent or translucent) and / or dielectric (e.g., made of a material with this property).

[0076] According to embodiments 300b, each of the layer stacks comprises one or more than one multilayer group (e.g., a stack thereof), each multilayer group comprising a first layer and an adjacent second layer disposed between the first layer and the substrate 250, which differ from each other in one or more than one of the following: in their layer thickness 362 (referred to herein as d1, d2, . . . , d4), in their chemical composition 364, and / or in their optical refractive index.

[0077] As an example, the first layer comprises silicon oxide and the second layer comprises niobium oxide, both of which are optically transparent and dielectric. However, it should be understood that the first layer and the second layer may each comprise any suitable material to meet the optical properties required.

[0078] Fig. 4A and Fig. 4B each illustrate various spectral responses according to various embodiments 400a, 400b in a schematic diagram in which the transmission coefficient T is plotted against the wavelength A (in nanometers). The spectral responses shown can, for example, be determined as an actual state by sensory means (i.e., using a sensor) or as a desired state by means of the model, for example, if they are intended to serve as a specification for the optical properties of the coating result in the form of the desired state.

[0079] Fig. 5A to Fig. 5C each illustrate a spectral response according to various embodiments 500a, 500b, 500c in a schematic diagram for various actual states of the coating result, shown here at times t1, t2, and t3 over the course of the coating process. The spectral responses shown can, for example, be recorded sensorily (i.e., by means of a sensor) as an actual state, for example as the temporal development of the spectral response during the construction of a layer stack, or can be determined as a target state using the model, for example if they are intended to serve as a specification for the optical properties of the coating result in the form of the target state.

[0080] The spectral response according to embodiments 500a substantially corresponds to that of the substrate, which may be the case when the coating process has just begun. The spectral response according to embodiments 500b corresponds to that of a partially completed layer stack. The spectral response according to embodiments 500c corresponds to the completed layer stack. Fig. 6A and Fig. 6B illustrate the coating process according to various embodiments in various schematic diagrams 600a, 600b, in which the coating process is depicted over time t and a comparison of the front-side process 601 to the back-side process 603 is depicted.The coating process can be carried out according to a cycle Z, which has a first phase 615 (also referred to as start phase), a second phase 611 (also referred to as two-side coating phase) and a third phase 613 (also referred to as final phase), for example in which the substrate is transported (e.g. continuously).

[0081] Each cycle is assigned a layer of the layer stack, which is formed in the cycle by means of the front-side process 601 and the back-side process 603 from a layer-forming material. For example, the layer-forming material is provided at the transport path and / or in a coating region through which the substrate is moved along the transport path (e.g., by means of a pendulum motion or rotational movement of the substrate carrier). In general, immediately consecutive cycles can differ from one another in the layer-forming material by means of which the layer of the layer stack assigned to them is formed.

[0082] In the following, a k-th (1 <k, z.B. 2<k, z.B. 3<k) Zyklus Bezug genommen, wobei das hierfür Beschriebene in Analogie für den (k+1 )-ten Zyklus (insofern vorhanden) und / oder den (k-1 )-ten Zyklus (insofern vorhanden) gelten kann. Der k-te Zyklus kann eingerichtet sein, die k-te Schicht des Schichtstapels aus dem k-ten Schichtbildungsmaterial (z.B. Nioboxid) zu bilden, beispielsweise mittels der k-ten Beschichtungsmaterialquelle 106a der Beschichtungsvorrichtung. Die k-te Beschichtungsmaterialquelle 106a ist eingerichtet, das k-te Schichtbildungsmaterial (z.B. Nioboxid) an dem Transportpfad und / oder in einem Beschichtungsbereich, durch den das Substrat entlang des Transportpfads hindurch bewegt (z.B. mittels einer Pendelbewegung oder Drehbewegung des Substratträgers) wird, bereitzustellen. Beispielsweise kann sich das k-te Schichtbildungsmaterial unterscheiden von dem (k+1 )-ten Schichtbildungsmaterial (z.B.silicon oxide), if present, and / or the (k-1 )th layer-forming material (e.g. silicon oxide), if present, and / or correspond to the (k+z)th layer-forming material (2=z or 3=z).

[0083] In the two-side coating phase 611 of the k-th cycle, the front-side process 601 and the back-side process 603 can be carried out (operation state = ON), e.g., simultaneously and / or for the same duration, by means of which the k-th layer forming material is provided.

[0084] In the completion phase 613 of the k-th cycle, which, for example, adjoins the two-side coating phase 611 and / or the subsequent (k+1)-th cycle, the front-side process 601 can be interrupted with a time delay before the back-side process 603 (operating state = OFF). This completes the formation of the k-th layer of the front-side coating before the formation of the k-th layer of the back-side coating. For example, the interruption of the front-side process 601 can occur by a time period te (also referred to as the completion time difference) before the interruption of the back-side process 603. The completion time difference t2 can, for example, be the duration of the completion phase 613.

[0085] In the start phase 615 of the k-th cycle, which, for example, adjoins the two-side coating phase 611 and / or the previous (k-1)-th cycle, the back-side process 603 can be started (e.g., continued) with a time delay after the front-side process 601 (operating state = ON). For example, the start (e.g., continuation) of the back-side process 603 can occur by a time period Δt (also referred to as the reference time difference) before the start (e.g., continuation) of the front-side process 601. The reference time difference Δt can, for example, be the duration of the start phase 615.

[0086] For example, several consecutively performed cycles may coincide in the reference time difference Δt. Alternatively or additionally, several consecutively performed cycles may differ from each other in the layer formation material and / or the duration of the first phase 611.

[0087] Diagram 600b shows the layer thickness as a function of time t, for the exemplary case where the layer formation rate r1 of the front-side process 601 is equal to the layer formation rate r2 of the back-side process 603, which may not necessarily be the case. As shown, the actual layer thickness of the layer formed by the front-side process 601 increases as a function of time t and the layer formation rate until it reaches the target layer thickness d1 at the end of the two-side coating phase 611. This occurs for the back-side process 603 at the end of the final phase 613.

[0088] If the front-side process 601 and the back-side process 603 provide the same layer formation rate (also referred to as coating rate), the completion time difference te can be equal to the reference time difference Δt, but this need not necessarily be the case (in which case it is also referred to as the layer formation difference). If the layer formation rate r1 of the front-side process 601 is greater than the layer formation rate r2 of the back-side process 603, the completion time difference te can be greater than the reference time difference Δt.

[0089] The completion time difference can be based, for example, on the actual state of the coating result determined in 101, for example, a comparison thereof with a corresponding target state. For example, determining 101 the actual state of the coating result can reveal that the back-side process 603 has progressed further than intended and is therefore interrupted at the same time as the front-side process 601 (tu = 0). For example, determining 101 the actual state of the coating result can reveal that the layer thickness of the layer formed by the front-side process 601 is smaller than intended and is therefore interrupted at the same time as the back-side process 603.In an exemplary implementation 1, the reference time difference Δt is used as a process difference, which may, for example, be greater than 1% (or 5% or 10%) of the duration of the two-side coating phase and / or in a range of approximately more than 1 second (s) and / or less than approximately 20 s, e.g., in a range of approximately 5 s to approximately 10 s. Alternatively or additionally, the reference time difference Δt may be greater than the duration required for several (e.g., more than 10 or more than 50 or more than 100) revolutions of the substrate carrier.

[0090] In an exemplary implementation 2, for example, configured according to implementation 1, the completion time difference is used as a process difference, which may, for example, be greater than 1% (or than 5% or than 10%) of the duration of the two-side coating phase and / or in a range of approximately more than 1 second (s) and / or less than approximately 20 s, e.g., in a range of approximately 5 s to approximately 10 s.

[0091] In an exemplary implementation 3, which is configured, for example, according to implementation 1 or 2, the layer formation difference is used as a process difference, which may, for example, include the layer formation rate r1 of the front-side process 601 and the layer formation rate r2 of the back-side process 603 differing from each other by more than 1% (or 5% or 10%).

[0092] More generally, the process difference may provide a difference 620 (also referred to as a layer thickness difference) between the actual layer thickness of the layer formed by the front-side process 601 and the actual layer thickness of the layer formed by the back-side process 603. The layer thickness difference 620 may, for example, be present for each cycle and / or at least in (e.g., at the end of) the two-side coating phase 611. The layer thickness difference 620 is generally a function of the layer formation difference and the reference time difference Δt.

[0093] The greater the layer thickness difference and / or the earlier the layer thickness difference in the start phase 615 fulfills a criterion (e.g., exceeds a threshold value), the better the actual states of the front-side coating and the back-side coating can be distinguished from each other using the model.

[0094] For example, the layer thickness difference (at least in the starting phase 615) can be greater than 2.5nm, 5nm or 10nm and / or meet the criterion if, for example, the variance of the determined coating rate is <5%, <2% or <1%.

[0095] In an exemplary implementation, the following occurs (e.g., per cycle or at least several times per first phase): Determining the time-dependent actual state of the coating result using the model based on the actual state of the spectral response of the coating result, comparing the actual state of the coating result with a (e.g., time-independent) target state of the coating result, and controlling the coating process based on the result of the comparison.

[0096] Fig. 7 illustrates a vacuum arrangement 104 according to various embodiments 700 in a schematic plan view or cross-sectional view, in which the vacuum arrangement 104 further comprises a reaction device 702 (e.g., ion source) configured to oxidize the coating material emitted by the coating material sources 106a, 116a to form the layer-forming material. The components 106a, 116a, 702 shown here, arranged above the transport path 111, can additionally be arranged below the transport path 111 by analogy with the same type.

[0097] Arranged above and below the transport path 111 is a coating material source 106a, 106b configured as a silicon oxide source, which is provided by means of a Si target (e.g., as part of a sputtering device) and the reaction device 702. Furthermore, arranged above and below the transport path 111 is a coating material source 116a, 116b configured as a niobium oxide source, which is provided by means of an NbOx target (e.g., as part of a sputtering device) and the reaction device 702.

[0098] It can be further understood that the model may be based on one or more of the following information: a sensor-detected emission rate of the front-side process and / or the back-side process; a sensor-detected layer formation rate of the front-side process and / or the back-side process; an operating point (e.g., operating state) of the front-side process and / or the back-side process.

[0099] In general, the emission rate and the stratification rate can be linked, for example, via a plant-specific and / or material-specific factor that can be determined in advance. In rare cases, the emission rate and the stratification rate may be identical, for example, if the emission rate is measured at the location of the transport path.

[0100] For example, determining the actual state of the coating result (e.g., using the model) can be based on information about which subprocess of the coating process is interrupted. Then, for example, the layer stack formed by this subprocess can be set as invariant, for example, according to the actual state determined at the time the subprocess was interrupted. More generally, the model parameters of a layer stack can be set as variable if coating material is also added to it.

[0101] It can be understood that, alternatively or in addition to the operating state explained above, any other operating parameter can be changed according to a specification to implement the process difference. For example, the rate at which the film-forming material is emitted (also referred to as the emission rate) can be changed as a working parameter according to the specification. For example, a shutter by which the film-forming material is blocked (also referred to as the emission rate) can be moved as a working parameter according to the specification.

[0102] In an exemplary implementation, the stratification difference (e.g., sensory) is determined and the model is initialized based on the process difference, which includes the reference time difference and the stratification difference. For example, the actual result determined by the model is based on the stratification rate of each sub-process and the reference time difference.

[0103] In an exemplary working example, the coating of the front and back sides is started with a slight time offset of approximately 5 s to 10 s, for example, either the front or back side first. The coating parameters are selected as follows:

[0104] • The coating rate on the side where coating is started first is set to be greater than or equal to the coating rate on the other side.

[0105] • The time offset (reference time difference) is set in such a way that the layer thickness of the front layer, as long as it is sputtered, is greater than that of the back layer.

[0106] • During the coating process, optical spectra are continuously recorded using a broadband spectrometer and assigned a time stamp. The current layer thicknesses (also known as actual layer thicknesses) at the time of the recording are fitted from the recorded spectra using a model. The following applies: o For the first fits (also known as a compensation calculation), the thickness resulting from the projected coating rate and the time is used as the starting point. The current coating rate (also known as the actual coating rate) is then calculated from the fitted thicknesses. This serves as the basis for further calculations and for determining the switch-off time. o As long as coating is in progress on both sides, the two layer thicknesses are fitted simultaneously. The ranges for the possible layer thickness are limited during the fit.The maximum permissible thickness of the back coating is set to be smaller than the minimum permissible thickness of the front coating. If only one side of the coating is running, only that side is fitted. The last determined value is used for the coating thickness of the other side.

[0107] This makes double-sided coating possible almost simultaneously with control by an optical monitoring system, even when the coating systems on the front and back are identical. Even with a completely symmetrical arrangement of the coating components for the front and back, only one sensor is required for a broadband spectrum. As a result, the system's throughput can be increased. Simultaneous sputtering on a substrate also reduces substrate deflection, since the same layer stress is generated on both the front and back. Various examples are described below, which relate to those described previously and those illustrated in the figures.

[0108] Example 1 is a (e.g., computer-implemented) method comprising: determining an actual state of a result (also referred to as actual result) of a two-sided coating process by means of which a first layer stack is formed on a front side of a substrate and a second layer stack is formed on a back side of the substrate, based on: a model which defines a link (e.g., mapping) between the result (e.g., a state thereof) and a spectral response (e.g.,a state thereof) of the result, and an actual state of the spectral response (also referred to as actual spectral response), an indication of a difference between a first sub-process of the coating process, by means of which the first layer stack is formed, and a second sub-process of the coating process taking place at the same time, by means of which the second layer stack is formed, controlling the coating process and based on the actual state of the result.

[0109] Example 2 is the method according to Example 1, wherein the control of the coating process takes place according to a specification which preferably represents a desired state of the result (also referred to as desired result), for example wherein the control of the coating process is based on a comparison of the specification with the actual state of the result (e.g. on a result of the comparison).

[0110] Example 3 is the method according to Example 2, wherein the first layer stack and the second layer stack have a uniform structure according to the target state.

[0111] Example 4 is the method according to example 2 or 3, wherein the first layer stack and the second layer stack according to the desired state match in one or more than one of the following: a spatial sequence of layers of different chemical composition; a chemical composition of one or more than one layer; a number of layers of different chemical composition; a total thickness; a spectral response.

[0112] Example 5 is the method according to any one of examples 1 to 4, further comprising: controlling a measuring element for detecting the actual state of the spectral response.

[0113] Example 6 is the method according to any one of examples 1 to 5, wherein the difference between a first sub-process and the second sub-process causes a difference between the first layer stack and the second layer stack with regard to: a rate (e.g., layer formation rate) at which the layer thickness thereof changes; and / or a point in time at which the layer thickness thereof reaches a target state (also referred to as target layer thickness). Example 7 is the method according to any one of examples 1 to 6, wherein the difference between a first sub-process and the second sub-process comprises: a difference in the point in time at which an operating point (e.g., an operating state) is changed according to a specification; and / or a difference in a rate (emission rate) at which a coating material is provided therefrom (e.g., emitted, e.g., emitted towards the substrate).

[0114] Example 8 is the method according to any one of examples 1 to 7, wherein the controlling comprises starting, interrupting, continuing, and / or terminating the first sub-process and the second sub-process with a time offset from one another; wherein the time offset is preferably based on the actual state of the result and / or wherein the difference between a first sub-process is preferably based on or comprises the time offset.

[0115] Example 9 is the method according to any one of examples 1 to 8, wherein the controlling comprises controlling one or more than one actuator which is configured to influence the coating process in response to being controlled, of which, for example, a first actuator is configured to influence the first sub-process in response to being controlled and / or of which, for example, a second actuator is configured to influence the second sub-process in response to being controlled.

[0116] Example 10 is the method according to any one of examples 1 to 9, wherein determining the actual state of the result comprises setting the model at least partially invariant with respect to the first layer stack when the first coating process is interrupted; and / or with respect to the second layer stack when the second coating process is interrupted.

[0117] Example 11 is the method according to any one of Examples 1 to 10, wherein the spectral response comprises a transmission spectrum; and / or wherein the spectral response is determined by ellipsometry.

[0118] Example 12 is the method of any one of Examples 1 to 11, wherein the model is initialized based on the indication.

[0119] Example 13 is the method according to any one of Examples 1 to 12, wherein the first layer stack and the second layer stack each consist of or at least comprise one or more than one dielectric and / or optically transmissive (e.g., transparent or translucent) material (also referred to as layer-forming material).

[0120] Example 14 is the method according to any one of Examples 1 to 13, wherein the first layer stack and the second layer stack each consist of or at least comprise one or more than one ceramic. Example 15 is the method according to any one of Examples 1 to 14, wherein the coating process is controlled according to a cycle which: has a first phase in which the second sub-process is started (e.g. continued) at a time offset after the first sub-process; has a second phase in which the first sub-process and the second sub-process are carried out simultaneously, preferably in a corresponding manner in a coating material provided thereby; has a third phase in which the first sub-process is interrupted (e.g. ended) at a time offset before the second sub-process, wherein the cycle comprises changing the coating material provided by the first sub-process and the second sub-process.

[0121] Example 16 is a computer program (computer program product) comprising instructions stored on a computer-readable medium that, when executed by a processor, is configured to cause the processor to perform the method according to any one of Examples 1 to 15.

[0122] Example 17 is a computer-readable medium storing instructions configured, when executed by a processor, to cause the processor to perform the method of any of Examples 1 to 15.

[0123] Example 18 is a control device comprising one or more than one processor configured to perform the method of any of Examples 1 to 15.

[0124] Example 15 is a processing arrangement, comprising: the control device according to Example 14; at least one (i.e., one or more than one) first coating material source configured to carry out the first sub-process; at least one (i.e., one or more than one) second coating material source configured to carry out the second sub-process; wherein the control device is configured to control the at least one first coating material source and the at least one second coating material source (to control the coating process) based on the actual state of the result; optionally further comprising: a transport device for transporting the substrate along a transport path arranged between the at least one first coating material source and the at least one second coating material source; and / or a vacuum chamber in which the transport path is arranged.

Claims

Patent claims 1. Method (150), comprising: Determining (101) an actual state of a result of a two-sided coating process by means of which a first layer stack is formed on a front side of a substrate and a second layer stack is formed on a back side of the substrate, based on: • a model that implements a link between the result and a spectral response of the result, and • an actual state of the spectral response, • an indication of a difference between a first sub-process of the coating process, by means of which the first layer stack is formed, and a second sub-process of the coating process, which takes place at the same time and by means of which the second layer stack is formed, Controlling (103) the coating process based on the actual state of the result.

2. Method (150) according to claim 1, wherein the control of the coating process takes place according to a specification which preferably represents a desired state of the result.

3. The method (150) according to claim 2, wherein the first layer stack and the second layer stack have a uniform structure according to the desired state.

4. The method (150) according to claim 2 or 3, wherein the first layer stack and the second layer stack according to the target state agree in one or more than one of the following: • a spatial sequence of layers of different chemical composition; • a chemical composition of one or more than one layer; • a number of layers of different chemical composition; • a total thickness; • a spectral response.

5. The method (150) according to any one of claims 1 to 4, wherein the difference between a first sub-process and the second sub-process causes a difference between the first layer stack and the second layer stack with respect to: • a rate at which the layer thickness thereof changes; and / or • a point in time at which the layer thickness reaches a target state.

6. The method (150) according to any one of claims 1 to 5, wherein the difference between a first sub-process and the second sub-process comprises: • a difference in the time at which a working parameter is changed according to a specification; and / or • a difference in a rate at which coating material is delivered.

7. Method (150) according to one of claims 1 to 6, • wherein the controlling comprises starting, interrupting, continuing and / or ending the first sub-process and the second sub-process with a time offset from one another; • where the time offset is preferably based on the actual state of the result.

8. The method (150) according to any one of claims 1 to 7, wherein the spectral response comprises a transmission spectrum or a reflection spectrum; and / or wherein the spectral response is determined by means of ellipsometry.

9. The method (150) according to any one of claims 1 to 8, wherein the control of the coating process is carried out according to a cycle which: • has a first phase in which the second sub-process begins at a later time after the first sub-process; • has a second phase in which the first sub-process and the second sub-process are carried out simultaneously, preferably in a coating material provided by means of it; • has a third phase in which the first sub-process is interrupted at a later time before the second sub-process.

10. A computer program comprising instructions stored on a computer-readable medium which, when executed by a processor, is arranged to cause the processor to perform the method (150) according to any one of claims 1 to 9.

11. A computer-readable medium storing instructions configured, when executed by a processor, to cause the processor to perform the method (150) according to any one of claims 1 to 9, 12. Control device (102) comprising one or more than one processor configured to perform the method (150) according to any one of claims 1 to 9.

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