Layer stacks and procedures

Abstract

According to various embodiments, a method may comprise: determining a specification representing a target state (200S) of a spatial distribution of an optical density of a layer stack (200) or a requirement (S(a*)) for a resulting spectral property (a*) of the layer stack (200), based on a comparison of a prediction (V(a*)) about an actual state of the spectral property (a*) of the layer stack (200) with the actual state (I(a*)) of the spectral property (a*), wherein the prediction (V(a*)) is based on a model of the layer stack (200) which implements a link between the specification and the spectral property (a*) of the layer stack (200); and controlling an actuator configured to influence at least one layer formation process of a plurality of layer formation processes used to form the layer stack (200) based on the specification.

Description

[0001] Various embodiments relate to a layer stack and a method.

[0002] In general, the optical properties of a transparent substrate, such as a pane of glass, a film, or similar, can be modified by means of a coating. Traditionally, window panes, for example, are provided with a coating that is intended to reflect infrared light as much as possible while at the same time exhibiting a certain aesthetic or optical transparency. The balance between transparency and reflective properties of a coated pane of glass, for example, results in complex parameter relationships, particularly when a layer stack with several layers arranged one above the other is used. In addition to the optical material properties, the angular dependence of the optical properties and the dispersion relations must also be taken into account. For this reason, a large number of layer stacks have already been developed that are adapted to their specific application.

[0003] Increasing demands for cost reduction, e.g., through simplified manufacturing processes, faster availability, and cheaper materials, as well as requirements for quality assurance, chemical and mechanical robustness, and optical performance of the layer stacks, can often only be partially met by conventional layer systems. In particular, higher optical performance requires higher costs due to the increased effort required for quality assurance.

[0004] In a manufacturing chain, a series of simulations can be carried out based on the desired optical properties in order to calculate a layer stack (also referred to as a multi-layer system or, more simply, a layer system) within the specifications that comes as close as possible to the desired optical properties (also referred to as layer planning). These simulations are often based on a model that parameterizes the properties of the individual layers and, based on this, calculates the optical properties of the entire layer stack. The parameters of the layer stack calculated in this way, such as the chemical composition of the layers, their number, their refractive index, their sequence, their thickness, their optical density, etc., can then be varied until the calculated optical properties and the desired optical properties correspond as closely as possible.The result is the parameters of the individual layers to be produced, such as their chemical composition, their refractive index, their optical density, and their thickness.

[0005] Traditionally, this result serves as a reference variable for producing the layer stack. Thus, the coating system is typically configured according to this result when producing the desired layer stack.

[0006] As a rule, the production of the layer stack is subject to various disturbances, so that its optical properties deviate from the desired optical properties. For quality assurance purposes, optical measurements of the produced layer stack can be carried out in order to compare its optical properties with the desired optical properties. If these properties deviate too greatly, the production process can be influenced in order to compensate for the influence of the disturbances on the production of the layer stack. For this purpose, analogous to layer planning, the parameters of the individual layers to be produced can be varied using an adjustment calculation until the calculated optical properties and the measured optical properties correspond as closely as possible. The result then provides information about the condition of the produced layer stack (e.g.The parameters of the individual layers, such as their thickness, can be saved (also known as layer verification). Comparing these results can provide insights into how to influence the production of the layer stack.

[0007] Against this background, it has been recognized, according to various embodiments, that this conventional approach is insufficient to meet high requirements regarding the optical properties, e.g., the tolerances thereof. Thus, it has been recognized that even if the layer planning and layer verification essentially match, deviations from the desired optical properties occur that cannot be further reduced using this conventional approach to layer planning and layer verification, so that the requirements regarding some spectral properties of the layer stack (e.g., one or more than one color value) are not met.

[0008] In this context, it has been recognized according to various embodiments that the conventional procedure of shift planning and shift checking is limited, among other things, by the fact that all available degrees of freedom are exhausted when shift planning and shift checking essentially agree, so that no degree of freedom is available to carry out further adaptation (e.g. optimization).

[0009] According to various embodiments, aspects of a method that address the above dilemma and a resulting layer stack are provided. The method can be used for various purposes, such as coating a transparent substrate (such as a glass pane, films, etc.).

[0010] It was clearly recognized that the requirements for one or more of such desired spectral properties and / or a uniformity of the spatial distribution of the desired spectral property(ies) over the entire layer stack are of greater importance than other properties of the layer stack, such as a uniformity of the spatial distribution of layer thicknesses of the individual layers of the layer stack.

[0011] Various embodiments relate to a method that makes it possible to produce a layer stack that meets even high requirements for one or more desired spectral properties. For example, the method makes it possible to form a layer stack on a substrate such that the layer stack essentially has the desired spectral property in several regions above the substrate.

[0012] The following refers to various aspects related to the layer stack, including: - a model of the layer stack (also called a linkage model) which implements a link between several properties of the layer stack, for example between the spatial distribution of an optical density of the layer stack (e.g. expressed as layer thickness and / or spatial distribution of the refractive index) and one or more than one spectral property of the layer stack; - an output of the model (also called a prediction), e.g. comprising information that the model outputs; - a prediction of the target state (also called reference state); - an input of the model (also called a requirement) e.g. comprising information that is fed to the model; - a desired property of the layer stack (also called a reference requirement); - a requirement for one or more than one property of the layer stack (also referred to as the desired state of the parameter), according to which one or more than one layer formation process can be influenced (e.g. regulated and / or controlled); - the desired state of the layer stack, which is a function of the desired state of one or more than one property of the layer stack or is at least linked to it; - one or more than one sensory detectable property of the layer stack (also referred to as the actual state of the property); - the actual state of the layer stack, which is a function of the actual state of one or more than one property of the layer stack or is at least linked to it; - Information (e.g. a prediction) about the structure of the layer stack (also called a layer structure model), e.g. about a spatial distribution of the optical density of the layer stack.

[0013] Clearly, the method according to various embodiments (in contrast to the conventional procedure) allows a comparison to be made between the prediction of the actual state of a spectral property of the layer stack and the actual state of the spectral property and a result thereof (also referred to as comparison result) to be taken into account (see Fig. 11 and Fig. 12) when influencing (e.g., controlling and / or regulating) the layer formation process. For example, the model's operation can be corrected based on the comparison result. For example, the model's input and / or output can be corrected based on the comparison result. For example, the target state according to which the layer formation process is influenced (e.g., controlling and / or regulating) can be corrected based on the comparison result. The comparison result clearly represents a deviation between the prediction and reality and thus a model inaccuracy, which is compensated for.

[0014] Various examples are described below which relate to what is described herein and shown in the figures.

[0015] Example 1 is a method comprising: determining an indication (e.g. a physical (layer) structure) that represents a desired state of a spatial distribution of an optical density of a layer stack or a requirement for (at least) one resulting spectral property of the layer stack, based on a comparison (e.g. result thereof) of a prediction about an actual state of the (at least one) spectral property of the layer stack with the (e.g.sensor-detected) actual state of the (at least one) spectral property, wherein the prediction is based on a model of the layer stack which implements a link between the indication and the (at least one) spectral property of the layer stack; and controlling an actuator which is configured to influence at least one layer formation process (also referred to as a coating process) of a plurality of layer formation processes used to form the layer stack (by means of which, for example, the layer stack (e.g. on a first substrate) is or was formed) based on the indication; wherein preferably an additional layer stack (e.g. on a second substrate) is formed by means of the plurality of layer formation processes based on a result of the control of the actuator.

[0016] Example 2 is a method comprising: determining a prediction about an actual state of a layer stack, which prediction comprises a prediction about an actual state of a spatial distribution of an optical density of the layer stack and a prediction about an actual state of a spectral property of the layer stack, wherein the prediction about the actual state of the layer stack is based on the actual state of the layer stack and on a model of the layer stack that implements a link between the spatial distribution and the spectral property of the layer stack; determining a correction model based on a comparison (e.g. result thereof) of the prediction about the actual state of the layer stack with the (e.g.sensor-detected) actual state of the spectral property; determining an indication that represents a desired state of the spatial distribution of the optical density of the layer stack or a requirement for the resulting spectral property of the layer stack, based on the correction model and on the prediction of the actual state of the layer stack; controlling an actuator that is configured to influence at least one layer formation process (also referred to as a coating process) of a plurality of layer formation processes used to form the layer stack based on the indication.

[0017] Example 3 is configured according to example 1 or 2, wherein the spectral property corresponds to (e.g., represents or is represented by) at least one coordinate in a color space and / or at least one color value.

[0018] Example 4 is configured according to Example 3, wherein the color space is based on a color model (e.g., color appearance model).

[0019] Example 5 is configured according to Example 4, wherein the color space according to the color model (e.g., color appearance model) is one of the following color spaces: the CIELAB color space, the RLAB color space, the LLAB color space, a CIECAM color space (e.g., the CIECAM02 color space, the CIECAM16 color space, etc.), the IPT color space, the CAM02 UCS color space, the CAM16 UCS color space, the ICtCp color space, the Jzazbz color space, the SRLAB2 color space, the OKLAB color space, etc.

[0020] Example 6 is configured according to any one of Examples 1 to 5, wherein a result of the comparison represents a deviation between the prediction about the actual state of the spectral property and the actual state of the spectral property.

[0021] Example 7 is configured according to any one of Examples 1 to 6, further comprising: determining a correction for an output and / or input of the model based on the comparison; wherein the determination of the indication is based on the correction.

[0022] Example 8 is configured according to any one of Examples 1 to 7, further comprising: determining the requirement for the spectral property based on the comparison and on a user input representing a reference requirement for the spectral property and / or for the spatial distribution of the optical density of the layer stack; wherein the indication, if it represents the desired state of the spatial distribution of the optical density of the layer stack, is determined based on the requirement.

[0023] Example 9 is configured according to Example 8, wherein the indication is further based on a spatial reference distribution of the optical density of the layer stack, which is determined by means of the model and based on the user input.

[0024] Example 10 is configured according to any one of examples 1 to 9, further comprising: determining the prediction about the actual state of the spectral property of the layer stack, preferably by means of a variation calculation (e.g., implemented by means of the model) (e.g., adjustment calculation) based on a (e.g., the) reference distribution of the optical density of the layer stack and / or a (e.g., the) reference requirement for the spectral property and / or for the spatial distribution of the optical density of the layer stack.

[0025] Example 11 is configured according to any one of Examples 1 to 10, if in combination with Example 1, wherein the determination of the indication is based on a prediction of an actual state of the spatial distribution of the optical density of the layer stack, which is determined by means of the model, preferably based on the actual state of the spectral property.

[0026] Example 12 is configured according to Example 11, wherein the determination of the information is carried out by means of a variational calculus (e.g., an adjustment calculation) (e.g., implemented by means of the model) based on the prediction of the actual state of the spatial distribution of the optical density and / or the spectral property and optionally based on the requirement.

[0027] Example 13 is configured according to any one of Examples 2 to 12, if in combination with Example 2, wherein the determination of the correction model is carried out by means of a variational calculus (e.g. adjustment calculation) (e.g. implemented by means of the model) which is based on the prediction of the actual state of the spatial distribution of the optical density and / or the spectral property and optionally based on the requirement.

[0028] Example 14 is configured according to Example 13, wherein the variation calculation (e.g. adjustment calculation) is based on a spatial reference distribution of the optical density of the layer stack, which is determined by means of the model, and / or a reference requirement for the spectral property and / or for the spatial distribution of the optical density of the layer stack.

[0029] Example 15 is configured according to any one of examples 1 to 14, further comprising: determining at least one layer of the layer stack whose geometry (e.g., layer thickness) influences the spectral property; wherein: the variational calculus is applied (e.g., only) to the geometry of the at least one layer and / or leaves the remaining layers of the layer stack invariant; and / or the at least one layer is formed by means of the at least one layer formation process.

[0030] Example 16 is configured according to Example 15, further comprising: selecting the at least one layer formation process (e.g., as a set layer formation process) based on a result of determining the at least one layer of the layer stack whose geometry (e.g., layer thickness) influences the spectral property.

[0031] Example 17 is configured according to any one of Examples 1 to 13, if in combination with Example 11, wherein the determination of the prediction about the actual state of the spatial distribution of the optical density of the layer stack is carried out by means of a variational calculus (e.g. adjustment calculation) (e.g. implemented by means of the model) which is based on a spatial reference distribution of the optical density of the layer stack, which is determined by means of the model, and / or a reference requirement for the spectral property and / or for the spatial distribution of the optical density of the layer stack.

[0032] Example 18 is configured according to any one of examples 13, 14, or 17, wherein the calculus of variations (e.g., implemented by means of the model) is applied (e.g., only) to the geometry of one or more layers of the layer stack and / or leaves the remaining layers of the layer stack invariant.

[0033] Example 19 is configured according to any one of examples 1 to 18, wherein the spatial distribution of the optical density of the layer stack comprises information about: a geometry (e.g., specified as layer thickness) of one or more than one layer of the layer stack; and / or an optical density (e.g., specified as refractive index) of one or more than one layer of the layer stack.

[0034] Example 20 is configured according to any one of Examples 1 to 19, wherein the layer stack comprises a plurality of layers, each layer being formed by a layer formation process of the plurality of layer formation processes.

[0035] Example 21 is configured according to any one of Examples 1 to 20, further comprising: determining the current state of the spectral property based on (eg, using) an optical response (eg, an optical spectrum) of the layer stack.

[0036] Example 22 is configured according to any one of Examples 1 to 21, wherein the at least one coating process is a chemical vapor deposition process or a physical vapor deposition process.

[0037] Example 23 is a computer program configured, when executed by a processor, to cause the processor to perform the method of any one of Examples 1 to 22.

[0038] Example 24 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 22.

[0039] Example 25 is a control device comprising: one or more processors configured to perform the method of any of Examples 1 to 22; and one or more memory having data representing the model.

[0040] Example 26 is a vacuum coating arrangement comprising: the control device according to Example 25; a plurality of coating devices for performing the plurality of coating processes; and the actuator (which is coupled to or integrated into one or more coating devices of the plurality of coating devices, e.g., at least the coating device configured to perform the actuating layer formation process); wherein preferably each coating device of the plurality of coating devices is configured to perform at least one coating process of the plurality of coating processes.

[0041] In Example 27, the vacuum coating assembly according to Example 26 may optionally further comprise: a vacuum chamber in which the plurality of coating devices are arranged.

[0042] In Example 28, the vacuum coating arrangement according to Example 26 or 27 may optionally further comprise: a sensor arrangement (e.g., comprising a light source and an optical sensor) for detecting an optical response (e.g., an optical spectrum) of the layer stack; wherein the actual state of the spectral property and / or the prediction of the actual state of the spectral property and / or the prediction of the actual state of the spatial distribution of the optical density is determined based on (e.g., using) the optical response.

[0043] Example 29 is a system comprising: the vacuum deposition arrangement according to example 27 or 28; and a sensor arrangement (e.g., comprising a light source and an optical sensor) for detecting an optical response (e.g., an optical spectrum) of the layer stack; wherein the actual state of the spectral property and / or the prediction of the actual state of the spectral property and / or the prediction of the actual state of the spatial distribution of the optical density is determined based on (e.g., using) the optical response.

[0044] Example 30 is a layer stack comprising: a first region (or first surface) and a second region (or second surface); and a plurality of layers arranged one above the other along a direction, of which one or more than one (e.g., each) layer is dielectric (e.g., oxide and / or nitride) and / or at least partially transparent; wherein the first region and the second region substantially coincide in an actual state of a spectral property of the layer stack; wherein the first region and the second region differ from each other in an actual state of a layer thickness of at least a first layer of the plurality of layers along the direction; wherein the first region and the second region preferably substantially coincide in the actual state of the layer thickness of one or more than one second layer of the plurality of layers along the direction.

[0045] Example 31 is a layer stack comprising: a first region (or first surface) and a second region (or second surface) which are spaced apart from one another along a path (which is, for example, perpendicular to a transport direction along which the layer stack is moved, for example relative to one or more than one coating device by means of which the layer stack is formed); and a plurality of layers arranged one above the other along a direction arranged transversely to the path, of which one or more than one (e.g., each) layer is dielectric (e.g., oxide and / or nitride) and / or at least partially transparent; wherein a spatially distributed spectral property of the layer stack along the path has a variance of less than a reference value, e.g., is substantially invariant; wherein a layer thickness of at least one (i.e.,one or more than one) first layer of the plurality of layers along the path has a variance of more than the reference value; wherein preferably a layer thickness of at least a second layer of the plurality of layers along the path has a variance of less than the reference value.

[0046] It shows Fig. 1 shows an exemplary vacuum coating arrangement for forming a layer stack according to various embodiments in a schematic top view or side view; Fig. 2 a schematic view of an actual state of a layer stack according to various embodiments; Fig. 3 is a schematic view of a prediction of the actual state and an actual optical response of the layer stack according to various embodiments; Fig. 4 shows a schematic view of a reference state of the layer stack and an optical reference response of the layer stack according to various embodiments; Fig. 5 a schematic view of the reference state of the layer stack as input and the prediction of the actual state of the layer stack as output of a variational calculus according to various embodiments; Fig. 6 is a schematic view of a desired state and a desired optical response of the layer stack according to various embodiments; Fig. 7A and Fig. 7B each shows an illustration for determining the desired state of the layer stack according to various embodiments; Fig. 8A and Fig. 8B each shows a coating system that can be controlled or regulated according to the desired state described herein, in a schematic side view or cross-sectional view according to various embodiments; Fig. 9 shows a schematic flow diagram for controlling coating processes according to various embodiments; Fig. 10 shows a schematic representation of a layer stack with a homogeneous distribution of spectral properties according to various embodiments; Fig. 11 a schematic representation of the conventional procedure; and Fig. 12 a schematic representation of an exemplary implementation of the method according to various embodiments.

[0047] 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.

[0048] In 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.

[0049] According to various embodiments, the term "coupled" or "coupling" can be understood in the sense of a (e.g., mechanical, hydrostatic, thermal, and / or electrical), e.g., direct or indirect, connection and / or interaction. For example, several elements can be coupled to one another along an interaction chain, along which the interaction can be exchanged, e.g., a fluid (then also referred to as fluidically coupled). For example, two coupled elements can exchange an interaction with one another, e.g., a mechanical, hydrostatic, thermal, and / or electrical interaction. A coupling of several vacuum components (e.g., valves, pumps, chambers, etc.) to one another can include fluidically coupled ones. According to various embodiments, "coupled" can be understood in the sense of a mechanical (e.g., physical) coupling, e.g.,by means of direct physical contact. A clutch can be configured to transmit a mechanical interaction (e.g., force, torque, etc.).

[0050] In the context of vacuum components (e.g., a pump, a chamber, a line, a valve, etc.), the term "coupled" or "coupling" can be understood in the sense of a connection to a common vacuum system. The components of the vacuum system can be configured to exchange a gas with each other via the coupling, whereby the coupling can be gas-separated from an external part of the vacuum system.

[0051] The actual state of an entity (e.g. a layer stack, a device, a system or an operation or 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 influencing of 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 control, whereby a change in state is additionally counteracted by disturbances.For this purpose, the actual state (or at least a prediction thereof) is compared with the desired state (or at least a prediction thereof) and the entity is influenced in such a way, e.g. by means of an actuator, 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 brought about by the so-called control loop (also referred to as feedback). In other words, this can be understood to mean that, alternatively or in addition to the control (or actuation), a closed-loop control can be used, or alternatively or in addition to the control, a closed-loop control can be used.

[0052] The state of a controllable entity, such as a controllable device (e.g. a coating device) or a controllable process (e.g. coating), can be specified as a point (also called the operating point or operating point) in a space (also called the state space) spanned by the variable parameters of the entity (also called operating parameters). The state of the entity is thus a function of the value of one or more operating parameters, which thus represents the state of the entity. The actual state can be determined based on a measurement (e.g. using a measuring element) of one or more operating parameters (then also called the controlled variable).

[0053] The term "control device" can be understood as any type of logic-implementing entity, which may, for example, comprise circuitry and / or a processor capable of executing software stored in a storage medium, firmware, or a combination thereof, and issuing instructions based thereon. The control device can, for example, be configured using code segments (e.g., software) to control the operation of a system (e.g., its operating point), e.g., a machine or a system, e.g., at least its kinematic chain.

[0054] 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 (e.g. a model can be implemented) by one or more specific functions carried out by the processor.

[0055] Control can be understood as the intentional influencing of a system. The current state of the system (also referred to as the actual state) can be changed according to a specification (also referred to as the target state). The parameters explained here (also referred to as target parameters) of the target state can, for example, be implemented using code segments or be stored on a storage medium in some other way. Regulation can be understood as control, whereby a change in the state of the system is additionally counteracted by disturbances. Illustratively, the control system can have a forward-facing control path and thus clearly implement a sequential control that converts an input variable (e.g. the specification) into an output variable. However, the control path can also be part of a control loop, so that a closed-loop control is implemented.For control purposes, corresponding actuators of the system can be activated, which influence the actual state of the system. Examples of actuators include: a coating device (for forming a layer of a layer stack), a drive device (e.g., for providing torque), a valve (e.g., for controlling pressure), and a switch (e.g., for closing a discharge path).

[0056] If reference is made herein to a target parameter, a target state (e.g. of a layer stack, a spectral property, etc.) or a target optical response (e.g. a target optical spectrum), this or these can be implemented by means of code segments, which can be stored, for example, in a data memory of the control device. The code segments can be stored in the data memory in a suitable manner, for example as a list (e.g. table), series of values, as an algorithm, etc. A data memory (more generally also referred to as a storage medium) can, for example, be a non-transitory data memory. The data memory can, 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 can, for example, be an erasable programmable read-only memory (also referred to as EPROM). The random access memory can be a non-volatile random access memory (also referred to as NVRAM). For example, the data memory can store one or more of the following: the code segments implementing the method, the model or at least its parameters, and one or more indications of a difference between two subprocesses of the coating process.

[0057] The term “actuator” (e.g. having an actuator) can be understood as a transducer that is configured to influence a state, a process (e.g. a coating process) or a device in response to actuation of the actuator. The actuator can convert a control signal supplied to it (by means of which the actuation takes place) into mechanical movements or changes in physical quantities such as pressure or temperature. An electromechanical (also referred to as electromotive) actuator can, for example, be configured to convert electrical power into mechanical power (e.g. through movement) in response to the actuation. An electrothermal actuator can, for example, be configured to convert electrical power into thermal power in response to the actuation.An electrothermal actuator can, for example, be configured to convert electrical power into thermal power in response to the control. An electrical actuator can, for example, be configured to convert electrical energy into electrical energy (e.g., of a specific voltage, current, and / or power) in response to the control.

[0058] An actuator can be configured to influence the actual state (also referred to as the operating point) of the process (e.g., a coating 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 each other. The controlled variable (e.g., pressure) can then be a function of one or more manipulated variables (e.g., voltage).

[0059] For example, the actuator can change an electrical voltage as a manipulated variable, which is used to generate a material flow, so that a coating rate or layer thickness is changed as a controlled variable. For example, the actuator can change a gas flow rate as a manipulated variable, so that a pressure is changed as a controlled variable.

[0060] Examples of components of an actuator include: a coating device, a valve (e.g. a pump arrangement and / or gas supply device), a motor (e.g. a valve or a pump), a circuit (e.g. for controlling the coating device) or the like. The pump arrangement can, for example, be configured to pump out one or more gases according to the control and thus remove them from the coating process. The gas supply device can, for example, be configured to supply one or more gases to the coating process according to the control (also referred to as gas supply). The supplied gas can have a gas inflow rate (i.e. gas inflow per time). The gas inflow can, for example, be a standard volume flow supplied to the coating process.

[0061] 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. What has been described here can apply analogously to the controlled 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. Modern actuators, for example, are provided as a complex assembly comprising an actuator and its own control device (also referred to as an actuator control device). The actuator control device can be configured to receive the control value as input using the control signal and to control the actuator according to the control value.The generation and transmission of the control variable then takes place within the actuator, so that the manipulated variable is fed to the actuator. Less complex actuators can only process the control variable as a control signal, so the control variable is fed to them for control.

[0062] More generally, an actuator can be controlled using a control signal, where the control signal can represent the manipulated variable or its control value and / or the controlled variable or its control value. Alternatively or additionally, the control signal can contain instructions that specify how the manipulated variable or its control value is to be changed (e.g., its relative change).

[0063] It should be understood that the actuator does not necessarily have to be controlled electrically. The description here can apply analogously to other types of control. For example, this can also be done by human intervention (e.g., manual operation of the actuator and / or the control device).

[0064] Control performed by the control device can be carried out according to an operating sequence. This operating sequence can be stored in the data memory in a suitable manner, for example, as an algorithm or otherwise using code segments. An operating sequence is understood herein to be a specification according to which one or more actuators configured to influence at least one coating process are controlled. The operating sequence can specify one or more target parameters according to which a layer is formed by means of the at least one coating process. Examples of such parameters include: a target layer thickness, a target coating rate, a target gas pressure, etc.

[0065] A sensor (also referred to as a detector) can be understood as a transducer which is set up to detect a property of its environment (e.g. qualitative or quantitative) corresponding to the sensor type as a measured variable, e.g. a physical property, a chemical property and / or a material condition. The measured variable is the physical variable (then also referred to as the controlled variable) to which the measurement by means of the sensor applies. Each sensor can be part of a measuring chain which has a corresponding infrastructure (e.g. processor, storage medium and / or bus system and the like). The measuring chain can be set up to control the corresponding sensor, to process its detected measured variable as an input variable and, based thereon, to provide an electrical signal as an output variable which represents the detected input variable. For example, the output variable can indicate the measured value.The measuring chain can be or will be implemented, for example, by means of a so-called control device.

[0066] According to various embodiments, a quantity can be understood as a physical quantity (e.g., a radiated power) that represents (e.g., describes and / or correlates with) a quantitatively measurable property of a physical entity (e.g., an object, a process, or a state). Its value (quantity value) can optionally depend on the time t and / or the location P, for example, the composition of reflected and / or transmitted electromagnetic radiation. Optionally, the physical quantity, e.g., an electric field, can exhibit an anisotropy with respect to physical space and / or time, i.e., the quantity value depends on the measurement direction and / or measurement sequence. For example, a signal strength can generally represent an electrical quantity of a signal (e.g., a measurement signal), e.g., its current, voltage, amplitude, power, equivalence, peak value, etc.

[0067] In general, different (physical) quantities can be used to represent the same property of a physical entity (e.g., an object, process, or state). The different physical quantities can be related to one another (e.g., by means of merely invariant quantities and / or quantities inherent in the entity) (e.g., right-unique and / or left-unique), so that they can be converted into one another taking into account the connection (e.g., a function or dependency between them). For example, momentum and kinetic energy are a function of mass and velocity, i.e., they are linked to one another by means of mass and velocity, and can, for example, if the mass is known, both represent the velocity and / or each other. In other words, the interconnected (physical) quantities can be converted into one another, i.e., they also represent one another.The quantities representing each other can, for example, be of the same type, e.g. kinematic, mechanical, geometric, thermodynamic, electrical, magnetic, radiometric (e.g. photometric, e.g. optical), etc.

[0068] The expression that an element, a parameter, etc. "represents" another element, another parameter, etc. can be understood to mean that these are linked to each other, e.g. the element or the parameter is a (e.g. unique, e.g. one-to-one) function of the other element or parameter.

[0069] A model can be understood as a data-based (e.g., digital and / or virtual) representation of an original, e.g., a physical object (e.g., a layer stack) or a process (e.g., a control process or a process sequence). To create the model (so-called model building, i.e., the mapping of the original to the model), the original can be abstracted, parameterized, and / or simplified. The model can, for example, implement physical properties (e.g., geometry, volume, composition, etc.), spectral properties (e.g., reflection, transmission, wavelength dependence, etc.), and / or logical information (links, sequence, couplings, interrelationships, dependencies, etc.) about the original.The linking model can be implemented, for example, using one or more algorithms configured to convert an input of the linking model into an output of the linking model. The layer structure model can be implemented, for example, using a mapping series (e.g., a table, matrix, or similar) that references the individual layers of the layer stack and assigns specific properties (e.g., order, thickness, and / or refractive index) to them.

[0070] Exemplary implementations of the linking model include: OptiLayer Thin Film Software, FilmWizard, Essential Macleod. The linking model can, for example, be based on physical relationships (e.g., using Fresnel formulas), e.g., be configured to calculate one or more output variables based on these. Exemplary implementations of the linking model are configured to map information about a layer stack structure to its spectral properties and / or to vary the information about a layer stack structure based on a requirement for the spectral properties (e.g., using a compensation calculation).

[0071] Fig. 1 illustrates a vacuum coating arrangement 100 according to various embodiments in a schematic top view or side view (where direction 103 is, for example, a transport direction).

[0072] The vacuum coating arrangement 100 can have a vacuum chamber 102. A vacuum chamber 102 can be provided, for example, by means of a chamber housing in which one or more vacuum chambers can be provided. The chamber housing can be coupled, for example, to a pump arrangement, e.g., a vacuum pump arrangement, for providing a negative pressure or a vacuum (vacuum chamber housing), and can be configured so that it can withstand the effects of air pressure in the pumped-out state. The pump arrangement (comprising at least one vacuum pump, e.g., a high-vacuum pump, e.g., a turbomolecular pump) can make it possible to pump out a portion of the gas from the interior of the vacuum chamber 102. The or each vacuum chamber 102 can optionally have a chamber lid that seals the interior of the vacuum chamber 102 in a vacuum-tight manner. The chamber housing, e.g.,a vacuum chamber 102 provided therein may be arranged such that a negative pressure (ie a pressure less than atmospheric pressure) can be provided therein, e.g. a vacuum (ie a pressure of less than 0.3 bar), e.g. a pressure in a range of approximately 10 mbar to approximately 1 mbar (in other words rough vacuum) or less, e.g. a pressure in a range of approximately 1 mbar to approximately 10. -3 mbar (in other words fine vacuum) or less, e.g. a pressure in a range of approximately 10 -3 mbar to approximately 10 -7 mbar (in other words high vacuum) or less, e.g. a pressure less than high vacuum, e.g. less than about 10 -7 mbar. Atmospheric pressure (e.g., 1 bar) can be the pressure acting on the chamber housing from the outside.

[0073] The vacuum coating arrangement 100 may comprise a plurality of coating devices 104(n = 1 to N) (where "N" may be any integer greater than or equal to two), each coating device providing a coating process (also referred to as a layer formation process) of a plurality of coating processes. Each coating process of the plurality of coating processes may form at least one layer of a layer stack. Therefore, a coating process may also be referred to as a layer formation process. Here, a coating device 104(n) may be any suitable type of coating device capable of forming a layer. According to various embodiments, a coating device 104(n) may be configured to perform a chemical vapor deposition process and / or a physical vapor deposition process.For example, a coating apparatus 104(n) may include a magnetron (a planar magnetron or a tubular magnetron). For example, a coating apparatus 104(n) may include an electron beam evaporator. For example, a coating apparatus 104(n) may be configured to perform a spray coating or a spray coating process. For example, a coating apparatus 104(n) may include a nozzle tube evaporator for providing one or more evaporation sources. It is understood that these are exemplary embodiments of a coating apparatus 104(n) and that it may also include or be any other type of apparatus for performing a chemical vapor deposition process and / or a physical vapor deposition process.

[0074] The gas pressure used to operate the plurality of coating devices 104(n = 1 to N) (also referred to as operating pressure) and / or the gas or gas mixture supplied to the coating device 104(n) (also referred to as operating gas) can be highly application-dependent. For example, the operating pressure can be in a range of approximately 10 -4 mbar (millibar) to approximately 5·10 -4mbar. For example, the working gas may comprise one or more of the following gases: oxygen (e.g. molecular oxygen, i.e. O2), nitrogen (e.g. molecular nitrogen, i.e. N2), hydrogen (e.g. molecular hydrogen, i.e. H2), one or more hydrocarbon compounds, or a gas mixture thereof. The working gas may comprise the working gas (e.g. an inert gas) and / or a reactive gas. The reactive gas may, for example, comprise hydrogen. According to various embodiments, the reactive gas may comprise at least one of the following: hydrogen, water (gaseous, e.g. water vapor), oxygen, nitrogen, hydrogen sulfide, methane, gaseous hydrocarbons, fluorine, chlorine, or another gaseous material. Alternatively or additionally, the working gas may comprise or be formed from an inert gas, such as a noble gas, e.g. argon.The reactive gas may have a higher chemical reactivity than the working gas, e.g. with respect to the coating material.

[0075] A coating device 104(n) may include a target. The target may generally include or consist of a coating material.

[0076] During operation of the vacuum coating arrangement 100, a layer of a layer stack can be formed over or on one (or more than one) substrate 110 by means of each coating device 104(n) of the plurality of coating devices 104(n = 1 to N). For this purpose, the vacuum coating arrangement 100 can have a substrate holder 108 configured to hold the one or more substrates 110. The substrate holder 108 can be arranged in the vacuum chamber 102. In some embodiments, the substrate holder 108 can be configured to be stationary. In other embodiments, the substrate holder 108 can be configured to be movable. For example, the vacuum coating arrangement 100 can be a continuous system having a transport system for transporting the substrate 110 (see Fig. 8A and Fig. 8B), e.g. along the transport direction.

[0077] According to various embodiments, one or each substrate (e.g., a substrate material) may comprise or be formed from a film and / or a glass plate. For example, a (e.g., flexible) low-emission laminate may comprise two transparent films; and a layer system according to various embodiments between the two films. For example, a rigid or flexible carrier (e.g., comprising glass or metal and / or in the form of a plate, film, a strip, e.g., a metal strip, and / or a wafer) may be used as a substrate and may be or be coated with the layer stack (e.g., a low-emission multilayer system) by means of vacuum-assisted coating.

[0078] According to various embodiments, the 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 cover 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 cover layer arrangement, wherein the cover 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.

[0079] According to various embodiments, a layer stack with a transmission coefficient (also referred to as transmittance) for light of greater than approximately 70% is provided, e.g., for a pane (e.g., windshield) of an automobile. The provided transmittance of more than 70% for the low-emission multilayer system can, for example, be related to a specific wavelength range (also referred to as the transmission range) 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 cutoff wavelength, or to 550 nm.

[0080] An optical response (e.g., an optical spectrum) can be related to optical radiation. Optical radiation can generally be understood to mean ultraviolet radiation (10 nm-380 nm), infrared radiation (1 mm-780 nm), and / or the visible radiation lying between these (380 nm-780 nm), i.e., electromagnetic radiation with a wavelength in a range from approximately 10 nm (nanometers) to approximately 1 mm (millimeters), e.g., with a wavelength in a range from approximately 300 nm to approximately 850 nm. In other words, the optical response can refer to electromagnetic radiation with a wavelength in a range from approximately 10 nm to approximately 1 mm, e.g., with a wavelength in a range from approximately 300 nm to approximately 850 nm. The optical radiation can be brought into interaction with the coated substrate such that the coated substrate at least partially absorbs, reflects, and / or transmits the optical radiation.For this purpose, the coated substrate can be irradiated with optical radiation. The interaction of the coated substrate with the optical radiation can be recorded. Examples of the interaction of the coated substrate with the optical radiation (also referred to as the optical response) include: optical radiation reflected by the coated substrate, optical radiation transmitted by the coated substrate, and / or optical radiation absorbed by the coated substrate.

[0081] Optionally, the layer stack and / or the substrate can be transparent. In the context of this description, the term “transparent” (e.g., translucent) can be understood to mean that a structure (e.g., a substrate or 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 structure or material can, for example, be translucent (partially translucent). In other words, the transmittance within the transmission range can be greater (e.g., at least twice, three times, five times, or ten times as great) than the reflectance and / or absorption, e.g., their sum.

[0082] The transmission coefficient (also referred to as transmittance) can describe the proportion of electromagnetic radiation (e.g. visible light) that passes through the structure (e.g. the layer system) or the material. The reflectance (also referred to as reflection coefficient) can describe the proportion of the incident electromagnetic radiation that is reflected (e.g. re-emitted) by the structure or material. The reflectance can take into account directly reflected radiation (illustratively reflected back), diffusely reflected radiation and / or re-emitted radiation. The absorbance (also referred to as absorption coefficient) can describe the proportion of the incident electromagnetic radiation that is absorbed (i.e. taken up and / or absorbed) by the structure or material, e.g. by converting it into heat.

[0083] A transparent structure or material 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%.

[0084] Depending on the application of a coating (e.g. having one or more than one layer stack), its transmittance (T), absorbance (A), reflectance (R) and / or emissivity can be adjusted so that, for example, visible light is transmitted and / or infrared radiation (IR radiation) is reflected and / or hardly emitted. In other words, the coating can be designed as an optical filter or optical reflector. In thermal equilibrium (i.e. the spatial and / or temporal temperature difference ΔT essentially disappears), the absorption and emission of electromagnetic radiation can at least partially (e.g. essentially) cancel each other out, so that the technical design of the coating can be simplified by optimizing the considered parameters for transmittance (filter) and reflectance (reflector).In other words, a body in thermal equilibrium absorbs and emits radiation. The radiation (i.e., emission) of long-wave (e.g., in the infrared spectral range) thermal radiation (more generally, the emitted radiation) at T=0 (or transmittance at least substantially equal to zero) for a glazing (glass, for example, is not transparent in the IR spectrum) can be proportional to the absorption (A=1-R). In contrast, a low-emission multilayer system provided herein (e.g., an IRR coating) can result in a high reflectance (R) in the IR spectral range (infrared spectral range), which in turn means a low absorbance and thus low radiation (low-E).

[0085] In general, the transmittance can depend on the wavelength of the electromagnetic radiation, depending on the optical properties of the structure or material. For example, the structure or material can be transparent to one or more wavelength ranges while being non-transparent (also called 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. Another aspect of the optical properties of the structure or material is the emissivity, which describes how much electromagnetic radiation is emitted compared to an ideal thermal radiator, i.e., a blackbody, at the same temperature.

[0086] According to various embodiments, a dielectric material or a dielectric structure (e.g. layer) can be understood as electrically insulating, e.g. an electrical conductivity of less than 10 -6 Siemens / meter. The dielectric material or dielectric structure may, for example, comprise or be formed from an oxide and / or nitride ceramic (e.g., as a metal compound).

[0087] "Oxidous," as used herein, can be understood as meaning that the material or structure comprises or can be formed from an oxygen compound (e.g., a metal oxide). "Nitridic" can be understood as meaning that the material or structure comprises or can be formed from a nitrogen compound (e.g., a metal nitride). The dielectric material or dielectric structure can be transparent.

[0088] For example, the coating material of a coating device may comprise or be formed from at least one of the following materials: a metal; a transition metal, an oxide (e.g., a metal oxide or a transition metal oxide); a dielectric; a polymer (e.g., a carbon-based polymer or a silicon-based polymer); an oxynitride; a nitride; a carbide; a ceramic; a semimetal (e.g., carbon); a perovskite; a glass or glass-like material (e.g., a sulfidic glass); a semiconductor; a semiconductor oxide; a semiorganic material, and / or an organic material.

[0089] The control device 112 can be configured to control each of the plurality of coating devices 104 (n = 1 to N) to regulate the coating process of each coating device 104(n). According to various embodiments, the control device 112 can be configured to regulate each coating process according to target parameters. In this case, each coating process can be regulated such that a deviation between a prediction about the actual state of the layer stack and the target state of the layer stack is reduced.

[0090] Various embodiments relate to a method for determining the target state of the layer stack. The control device 112 can be configured to determine an indication representing this target state and to control or regulate the plurality of coating devices 104 (n = 1 to N) based on the indication.

[0091] When determining the target state of the layer stack, the actual state of one or more spectral properties can be taken into account. This allows for the production of a layer stack that has this one or more (targeted) spectral properties.

[0092] A spectral property can be any property (e.g., a parameter) that can be determined from the optical response (e.g., an optical spectrum) of a layer stack. Illustratively, the spectral property can be a function of the optical response.

[0093] The determination of the target state of the layer stack is explained herein using an easily understandable color value a* of the CIELAB color space as an exemplary spectral property. The description can apply to any other and / or additional spectral property. It is also understood that, for ease of understanding, the determination of the target state of the layer stack is described using a single spectral property (namely, the color value a*), and that the target state can also be determined accordingly for multiple spectral properties.

[0094] For example, the one or more spectral properties may comprise, in addition to or alternatively to the color value a* of the CIELAB color space: a spectral property that is not a color value of a color space (e.g., an emissivity), another color value of the CIELAB color space (e.g., b* or L*), or a color value of another color space (e.g., a red-green-blue (RGB) color space (e.g., the standard RGB (sRGB) color space, the Adobe RGB color space, etc.), CMYK (cyan-magenta-yellow-key) color space, a color space according to a color appearance model, etc.).

[0095] In general, a color can be represented using coordinates in a corresponding color space. The simplest case is a binary color space, where the value of one bit (e.g., for a black and white value) is specified per pixel. In a more complex color space, such as a grayscale color model, the colors of the color space are identified along with their intensity level, e.g., by specifying several steps between black and white (also called gray values) per pixel. However, the color space can also be defined by several (e.g., two or more) primary colors, such as red, green, and blue.

[0096] A color space may generally be based on a color model. The color model may be a mathematical description that maps a color into the color space. According to various embodiments, at least one spectral property of the one or more spectral properties may be a color value of a color space based on a color appearance model.

[0097] A color appearance model can be based on a perceptual psychological model with a distance measure between colors or hues that mimics human perception. A color appearance model can be a mathematical model that attempts to describe the perceptual aspects of human color vision (e.g., viewing conditions under which the appearance of a color does not correspond to the corresponding physical measurement of the stimulus source).

[0098] A color space according to a color appearance model can, for example, be one of the following color spaces: the CIELAB color space, the RLAB color space, the LLAB color space, a CIECAM color space (e.g., the CIECAM02 color space, the CIECAM16 color space, etc.), the IPT color space, the CAM02-UCS color space, the CAM16-UCS color space, the ICtCp color space, the Jzazbz color space, the SRLAB2 color space, the OKLAB color space, etc.

[0099] According to various embodiments, a (manufactured) layer stack 200 may include a plurality of layers 204 (n = 1 to N). The layer stack 200 may, for example, have been manufactured using the plurality of coating devices 104 (n = 1 to N) of the vacuum coating arrangement 100. The layer stack 200 may have an actual state 200I.

[0100] It is understood that when reference is made herein to the layer stack 200, this also includes the layer system comprising the layer stack 200 and the substrate 110. For example, it is understood that the substrate 110 may also have a corresponding influence on the optical properties of the layer system (and thus on the optical response) and may be considered in the conditions described herein.

[0101] The determination of the target state 200S of the layer stack is described below using the layer stack 200 as an example, with four layers (i.e., N = 4), a first layer 204(1), a second layer 204(2), a third layer 204(3), and a fourth layer 204(4). It is understood that this is for illustrative purposes using an exemplary layer stack, and that the layer stack 200 may also have any other number of layers (N equals two or more).

[0102] A state (e.g., an actual state, a reference state, a desired state) of the layer stack 200 may comprise a state of a spatial distribution of an optical density of the layer stack 200, a state of one or more spectral properties (i.e., in the present illustrative example, the color value a*), etc. The state of the spatial distribution of the optical density of the layer stack 200 may comprise or represent a physical layer structure of the layer stack 200. For example, the state of the spatial distribution of the optical density of the layer stack 200 may comprise a layer thickness 206(n) for each layer 204(n) of the plurality of layers 204(n = 1 to N). Thus, as in Fig. 2, the actual state 200I of the layer stack 200 may have a first layer thickness 206(1) of the first layer 204(1), a second layer thickness 206(2) of the second layer 204(2), a third layer thickness 206(3) of the third layer 204(3) and a fourth layer thickness 206(4) of the fourth layer 204(4).

[0103] A state (e.g., an actual state, a reference state, a desired state) of the layer stack 200 can have a desired state of the layer (short: desired layer state) for each layer 204(n) of the layer stack 200.

[0104] For ease of understanding, reference is made below to the layer thickness 206(n) of the layers 204(n = 1 to N) when determining the desired state. For example, the indication for controlling the plurality of coating devices 104(n = 1 to N) can be determined based on a deviation of the actual layer thicknesses from the desired layer thicknesses of the layers. It is understood that this is for illustrative purposes and that a state of the layer stack can also have other or additional parameters (and be taken into account when determining the indication).

[0105] According to various embodiments, a prediction 200V may be made about the actual state of the layer stack 200. With reference to Fig. 3, the prediction 200V about the actual state of the layer stack 200 may include, for each layer 204(n), a prediction about its layer thickness (also referred to as predicted layer thickness) 206(n)V. A prediction 200V about the actual state of the layer stack 200 may be a simulation of the layer stack according to a model.

[0106] According to various embodiments, a layer sequence of the layers of the layer stack 200 may be provided.

[0107] According to various embodiments, an optical response 302 of the layer stack 200 may be detected. In some embodiments, the optical response 302 may be detected ex-situ (i.e., outside the vacuum chamber 102, after the layer stack 200 has been formed). In other embodiments, the optical response 302 may be detected in-situ (i.e., within the vacuum chamber 102, e.g., without interrupting the vacuum) (see, for example, embodiments 800A and 800B of the vacuum coating apparatus 100). The detected optical response 302 may also be referred to as the actual optical response.

[0108] It is understood that an optical response described herein may, for example, be a spectrum consisting of several (separately acquired) sub-spectra.

[0109] The prediction 200V about the actual state of the layer stack 200 may include a prediction about the optical response (also referred to as predicted optical response) 304, or the controller 112 may be configured to determine the prediction about the optical response based on (e.g., using) the prediction 200V about the actual state of the layer stack 200.

[0110] According to various embodiments, the prediction 200V about the actual state of the layer stack 200 can be determined using a model. The control device 112 can have one or more memories containing data representing the model.

[0111] The model can, for example, implement a variational calculus in which the parameters of the predicted layer stack, such as the chemical composition of the layers, their optical density, their refractive index, their layer thickness, etc., are varied until the (calculated) predicted optical response 304 and the detected optical response 302 correspond as closely as possible. Illustratively, the optical response 302 of the layer stack 200 can be fitted. Consequently, a deviation between the detected optical response 302 and a (simulated) optical response can be reduced until they correspond as closely as possible. For example, the mean square deviation, MSE, can be reduced (e.g., minimized), where MSE:=1M∑λ(SF(λ,d1,d2,d3,d4)−SI(λ))2, where: λ is the (light) wavelength, S I the one or more than one detected optical (actual) response 302 is (e.g. the actual optical spectrum), S Fis the one or more than one simulated optical response, d1 is the layer thickness of the first layer 204(1) of the simulated layer stack, d2 is the layer thickness of the second layer 204(2) of the simulated layer stack, d3 is the layer thickness of the third layer 204(3) of the simulated layer stack, d4 is the layer thickness of the fourth layer 204(4) of the simulated layer stack, and M is the number of (one or more) optical responses.

[0112] The parameters of the layers of the layer stack can be stored accordingly in the model. The model can generally implement a link between a state of the layer stack and its optical response. The one or more spectral properties can, for example, be determined based on this optical response. Consequently, the model can implement a mathematical description of the link between the state of the layer stack and its optical response. The state of the layer stack and thus its optical response can therefore be a function of the parameters of the layer stack. The model can therefore be based on a physical description of the layer stack and its parameters. Consequently, the model can be a white-box model.Simulations can be carried out based on the model, which parameterizes the properties of the individual layers and calculates the optical properties of the entire layer stack based on this.

[0113] According to various embodiments, the model may provide a mapping function between the deviation Δa* and the change in at least one control parameter for each coating process of the plurality of coating processes.

[0114] The data for implementing the model and the data for parameterizing the layers of the layer stack can be stored in a data memory of the control device 112. These data can, for example, comprise a wavelength dependence of the refractive index, n(λ), and / or a wavelength dependence of the absorption coefficient, k(λ), for each of the plurality of layers 204 (n = 1 to N) and for the substrate 110. The data can also comprise a sequence of the layers of the layer stack 200. Optionally, the data can comprise at least one limit value (d max,l and / or d min,l ) which must be observed when varying the layer thicknesses.

[0115] Furthermore, the data may contain additional information for simulating an optical response, such as an angle of incidence of the optical radiation, a wavelength grid, etc.

[0116] When reference is made herein to a process implemented by means of the model, it is understood that different models may also be used, wherein each model may execute at least one process described herein that is based on (e.g., using) the model (e.g., by implementation by means of the controller 112).

[0117] It is understood that a prediction (e.g., a simulation) of a layer stack can also be considered a type of (layer) model (or layer structure model), since a simulation models a state (e.g., optical modeling). However, the model referred to herein as a "model" is considered a mathematical description of optical parameters and relationships between layers of the layer stack.

[0118] In the following, the determination of the target state is described using a (single) optical response for ease of understanding. It is understood that the calculations can also be carried out accordingly for multiple optical responses. An optical response can, for example, be one (or more than one) optical spectrum (or data that can be represented as an optical spectrum). For example, an optical spectrum can specify an optical parameter, P, such as a reflectance or a transmittance (e.g., in percent) as a function of a wavelength (λ) of incident light. Also, multiple optical responses (e.g., optical spectra) can be acquired from different regions of the layer stack and / or multiple optical responses can be acquired from the same region.

[0119] The prediction 200V about the actual state of the layer stack 200 can include a prediction about one or more spectral properties (in this example, the color value a*). For example, the control device 112 can be configured to determine the prediction V(a*) about the color value a* based on the predicted optical response 304.

[0120] The control device 112 can be configured to determine the actual state I(a*) of the color value a* based on the detected optical response 302. For example, the actual state I(a*) of the color value a* can be determined according to ISO 11664-4. This may require a wavelength range of 380 nm to 780 nm for the optical responses (e.g., spectra) to be detected.

[0121] As explained herein, the prediction V(a*) about the color value a* (also called predicted color value) may deviate from the actual state I(a*) of the color value a*.

[0122] In some embodiments, the control device 112 may be configured to perform the variation calculation for determining the prediction 200V about the actual state of the layer stack 200 based on (e.g., using) the model starting from a reference state 200R of the layer stack 200. This may reduce the computational effort required to determine the prediction 200V.

[0123] With reference to Fig. 4, the reference state 200R of the layer stack 200 (in the simplified view for easier understanding) may have a reference layer thickness 206(n)R for each layer 204(n). The reference state 200R of the layer stack 200 may further have a reference state R(a*) of the color value a*.

[0124] According to various embodiments, the reference state R(a*) of the color value a* can be a reference requirement for the color value a*. The reference state 200R of the layer stack 200 can have an optical reference response 402 of the layer stack 200, or the control device 112 can be configured to determine the optical reference response 402 based on (e.g., using) the reference state 200R. This reference requirement R(a*)) for the color value a* can be a desired or targeted color value, i.e., a target color value, which the produced layer stack is intended to have. According to various embodiments, the coating processes are controlled with the goal of achieving this target color value.

[0125] As in Fig. 5, the variation calculation for determining the prediction 200V about the actual state of the layer stack 200 can be carried out starting from a reference state 200R of the layer stack 200.

[0126] A variation calculation described herein (e.g., implemented by means of the model) can be carried out in such a way that the parameters (e.g., chemical composition, optical density, layer thickness, refractive index, etc.) of one layer or several (e.g., all) layers of the plurality of layers 204 (n = 1 to N) are varied. In some embodiments, the parameters of all layers can be varied. In other embodiments, at least one layer can not be varied (i.e., be invariant). An example of this is described in Fig. 5, in which, within the framework of the calculus of variations, the parameters of the first layer 204(1), the second layer 204(2) and the fourth layer 204(4) are varied (“var.”) and the parameters of the third layer 204(3) remain invariant.

[0127] For example, a layer can remain invariant if its thickness is smaller than a threshold, and the layer's influence on the optical spectrum is therefore smaller than a threshold. In this case, one or more assumptions can be made about the layer.

[0128] A variation of the layer thickness of a layer (carried out as part of a variation calculus) can also be referred to as a variation of the geometry of the layer.

[0129] According to various embodiments, the control device 112 can be configured to determine a target state 200S of the layer stack based on a comparison of the predicted color value V(a*) with the actual state I(a*) of the color value a* (in short: actual color value I(a*)). The control device 112 can be configured to determine a deviation, Δa*, (e.g., a difference) between the predicted color value V(a*) and the actual color value I(a*). According to various embodiments, the control device 112 can be configured to determine the target state 200S of the layer stack based on the deviation Δa* and optionally further based on the reference state R(a*) of the color value a* (i.e., the reference requirement for the color value a*). The deviation Δa* can also be referred to as a correction.

[0130] According to various embodiments, the control device 112 can be configured to determine the target state 200S of the layer stack 200 such that a resulting optical target response 602 of the layer stack 200 represents a target state S(a*) of the color value a* (short: target color value), which essentially corresponds to a deviation (e.g., a difference) between the reference state R(a*) of the color value a* (i.e., the reference requirement for the color value a*) and the deviation Δa*. The target state of the one or more spectral properties (e.g., the target state S(a*) of the color value a*) can also be referred to as a requirement for the one or more spectral properties (e.g., as a requirement for the color value).

[0131] Illustratively, it is considered that an actually measured color value (I(a*)) deviates from the predicted color value (V(a*)), even though the predicted optical response 304 is a "good" fit of the measured optical response of the layer stack 200. This may be due to the model not fully reflecting reality and / or data stored in the model not being entirely accurate. For example, disturbances within the vacuum chamber 102 (e.g., water in the vacuum chamber) may be the cause of the deviation. The deviation may also be due to the fact that the recorded optical distributions are too wavy and / or are unfavorably superimposed.

[0132] To achieve the target color value (R(a*)), the nominal color value (according to which the coating processes are controlled) is adjusted by this deviation (Δa*) of the actually measured color value (I(a*)) from the predicted color value (V(a*)). Assuming that the layer stack produced according to this nominal color value also has this deviation (Δa*), the actual color value of the layer stack produced in this way will essentially correspond to the target color value. For example, the target color value can be R(a*) = 5. If an actual color value I(a*) = 3.5 is then measured and the predicted actual color value V(a*) = 3.0, the deviation between these is Δa* = I(a*) - V(a*) = 3.5 - 3.0 = 0.5. The target color value is then determined as S(a*) = R(a*) - Δa* = 5 - 0.5 = 4.5. At least one coating process can then be controlled according to this target color value. Illustratively, at least one coating process can be controlled according to a desired color value.

[0133] According to various embodiments, the control device 112 can be configured to perform a variational calculation based on the model (e.g., using the model) (or another model) to determine the target layer stack 200S such that it has the target color value S(a*). In some embodiments, this variational calculation can be performed based on the prediction 200V about the actual state of the layer stack 200.

[0134] Fig. 7A and Fig. 7B each show an illustration for determining the target state 200S of the layer stack 200 (short: target layer stack) according to various embodiments. As described herein, either the model (also referred to as the first model) or another model (also referred to as the second model) can be used for this purpose.

[0135] If the first model is used, it can, for example, be configured to receive the detected optical response 302 and further at least one of the reference requirement R(a*) or the reference layer stack 200R as input, perform one or more of the work steps described herein, and then output the desired state 200S of the layer stack 200. Multiple submodels can also be used, each outputting individual work results and making them available to another submodel as input. For example, the control device 112 can implement a computer program that uses the model and into which the reference requirement R(a*) can be input (via user input).

[0136] In some embodiments, for example, the first model may output the prediction 200V about the actual state of the layer stack 200, and the second model may be configured to receive the prediction 200V about the actual state of the layer stack 200, the deviation Δa* (or the values ​​by which the deviation can be determined), and further at least one of the reference requirement R(a*) or the reference layer stack 200R as input, and then output the desired state 200S of the layer stack 200.

[0137] According to various embodiments, the (first or second) model (implemented by means of the control device 112) can perform a variational calculation based on the predicted layer stack 200V, in which the parameters of the layer stack, such as the chemical composition of the layers, their refractive index, their layer thickness, etc., are varied until the layer stack essentially has the target color value S(a*). In the variational calculation, one layer or several (e.g., all) layers of the plurality of layers 204 (n = 1 to N) can be varied. In some embodiments, the parameters of all layers can be varied. In other embodiments, at least one layer can not be varied (i.e., be invariant). For example, (see Fig. 7A) at least the layer remains invariant which already remained invariant when determining the predicted layer stack 200V (in the present example the third layer 204(3)).

[0138] Performing the variation calculation based on the predicted layer stack 200V is advantageous, for example, in that the target layer state of at least one layer can be determined even if there is a permanent deviation from the reference layer state. This also allows other systematic deviations between the detected optical response 302 and the predicted optical response 304 to be compensated.

[0139] The control device 112 can be configured to determine at least one layer 204(n*) of the layer stack 200 that influences the one or more spectral properties (i.e., in this example, the color value a*). In some embodiments, the model can be configured to receive information (e.g., provided by a user) as input that indicates this at least one layer 204(n*). In other embodiments, the control device 112 can be configured (optionally using the model) to determine the at least one layer 204(n*). For example, the layers of the layer stack 200 can be varied one after the other, and it can be determined which layer influences the color value a*. According to various embodiments, the at least one layer 204(n*) can be a layer of the plurality of layers.

[0140] In some embodiments, multiple layers of layer stack 200 may influence the one or more spectral properties, but the at least one layer 204(n*) may include only a subset (i.e., not all) of the multiple layers. For example, the at least one layer 204(n*) may be provided by a user, and the user may desire or require that at least one of the multiple layers not be varied, even though its parameters influence the one or more spectral properties.

[0141] The color correction method described herein allows for consideration of interactions between different layers, since, for example, each layer may affect several of one or more spectral properties.

[0142] Data provided by a user may also be referred to as user input.

[0143] According to various embodiments, the control device 112 can be configured to perform the variation calculation such that only the parameters of the are varied and the remaining layers are left invariant. According to various embodiments, the control device 112 can be configured to determine the target state 200S of the layer stack 200 such that the target layer state of the at least one layer (i.e., the target state of the at least one layer specified according to the target layer stack 200S) corresponds to the state according to the result of this variation calculation. The control device 112 can be configured to determine the reference layer state of the remaining (invariant) layers (i.e., the reference state of the remaining layers specified according to the reference layer stack 200E) as the target layer state of the remaining layers.

[0144] Illustratively, the target layer state of at least one layer can be determined dynamically to achieve the desired target color value. This can also be referred to as dynamic color correction. In the variational calculus, in which the parameters of at least one layer are varied, the mean square deviation (MSE) of the color value a* (as an optimization criterion) can be used in addition to or as an alternative to the MSE of the optical responses.

[0145] With reference to Fig. 7B, the fourth layer 204(4) may be the at least one layer 204(n*). The control device 112 may vary the parameters of the fourth layer 204(4) until the color value a* of the layer stack thus determined substantially corresponds to the target color value S(a*). The control device 112 may then (in the simplified example) use the layer thickness of the layer stack 200 thus determined as the target layer thickness 206(4)S. For the remaining, non-varied layers, the control device 112 may use the reference layer thickness 206(n)R as the target layer thickness 206(4)S.

[0146] Illustratively, for layers that do not influence the one or more spectral properties, the reference layer state can serve as the target layer state, and for at least one layer that influences the one or more spectral properties, another target layer state can be determined such that a layer stack produced according to the target state (i.e., the target layer states) essentially has a (previously defined) target value for each of the one or more spectral properties.

[0147] Consequently, for each measurement point at which one or more than one optical response 302 is detected, the following algorithm, for example, can be performed: 1. Model the reference layer stack with the (e.g. given) reference thicknesses (d R,l ). 2. Starting from the reference layer stack, determine the fit for the one or more detected optical responses 302. This results in the prediction 200V about the actual state of the layer stack and thus about the actual layer thicknesses (d F,l ). For invariant (i.e., not varied in the calculus of variations) layers (l ∉ M F ) is the F,l = d R,l . 3. Determine the fit deviation MSE. If MSE > limit: Mark the result as "unreliable" and end the analysis here. Otherwise, continue. 4. If the color correction function is turned off, enter l := d F,l - d R,l as an error to be corrected. Otherwise: 5. Calculate the color value a* for each of the one or more optical responses 302 (C M,i ) and the predicted optical response 304 according to the fit (C F,i ). 6. Based on the prediction 200V for the actual state of the layer stack 200, determine an adjustment to the target color value. This results in the new layer thicknesses d C,L . For layers not used for color correction (l ∉ M C ) is the C,l = d F,l . Enter the error to be corrected as l back: el={dF,l−dC,lif l∈MldF,l−dR,lelse.

[0148] It has been recognized that even when optimizing according to the target color value, an inherent deviation between the actual color value, I(a*), and the predicted color value, V(a*), may remain. Therefore, according to various embodiments, an inherent deviation Δ'a* can be taken into account when determining the target color value S(a*) according to: S(a*)=R(a*)−Δa*−Δ′a*=R(a*)−I(a*)+V(a*)−Δ′a*.

[0149] Viewed differently, the reference state R(a*) of the color value a* can also be adjusted according to the inherent deviation. In the terminology of the above exemplary algorithm, the inherent deviation C R',i be given by C R',i := C R,i + C F,i - C M,i . If the difference between the predicted reference state of the color value and the actual color value remains constant, the result is C F,i = C R',i and C M,i = C R,i . The optimization criterion of the mean square deviation of the color value, MSE C , can then be described as MSE C = Σ i [C i (S(λ, d l : l ∈ M C )) - C R',i ] 2 .

[0150] According to various embodiments, at least one (e.g., lower and / or upper) limit value can be taken into account in the variation calculation for color correction. This can, for example, prevent the target layer thickness of the at least one layer from differing too greatly from the reference layer thickness. The limit value, CTRL, can be taken into account for the at least one layer, l, according to d R,l ·(1 - CTRL) ≤ d C,l ≤ d R,l · (1 + CTRL).

[0151] If the number of degrees of freedom corresponds to the number of controlled spectral properties of one or more than one spectral property, then (if existing) an unambiguous result can be determined. If the number of controlled spectral properties is greater than the number of degrees of freedom, then the system is overdetermined. If the number of controlled spectral properties is less than the number of degrees of freedom, then the system is underdetermined. According to various embodiments, the model can be capable of handling underdetermination and / or overdetermination. To this end, the model can, for example, implement corresponding algorithms. Examples of such algorithms include: a least squares algorithm, an algorithm based on singular value decomposition (SVD), a Levenberg-Marquardt algorithm, and a trust region reflective algorithm.

[0152] Fig. 8A and Fig. 8B each show configurations 800A, 800B of a coating system (e.g., as a configuration of the vacuum coating arrangement 100) in a schematic side view or cross-sectional view according to various embodiments.

[0153] The coating system 800A, 800B can comprise the plurality of coating devices 104 (n = 1 to N). The coating system 800A, 800B can comprise a plurality of coating regions 806 (n = 1 to N), in each of which a coating process of the plurality of coating processes takes place. Optionally, the coating regions 806 (n = 1 to N) can be gas-separated from one another, e.g., by means of chamber walls, bulkheads, flow resistances, constrictions, or the like.

[0154] Furthermore, the coating system 800A, 800B can have a transport device 804 for transporting the at least one substrate 110 along a transport path 111p or in a transport direction 111p through the at least one vacuum chamber 102, e.g. through the plurality of coating regions 806 (n = 1 to N).

[0155] The control device 112 can be configured to control and / or regulate the coating processes. For example, the control device 112 can be configured such that the process atmosphere within the vacuum chamber 102 can be set or regulated, e.g., during the coating process. For example, the parameters of the process atmosphere can be used as control parameters, e.g., the process pressure, the process temperature, the chemical composition of the process gas, and / or their spatial and / or temporal distribution.

[0156] According to various embodiments, the coating system 800A, 800B may include a gas supply 808. A process gas may be supplied to the vacuum chamber 102 by means of the gas supply 808 to form a process atmosphere in the vacuum chamber 102.

[0157] For example, the gas supply 808 and / or a vacuum pump arrangement 810 can be controlled and / or regulated by means of the control device 112. For example, the parameters of the gas supply 808 and / or the vacuum pump arrangement 810 can be used as control parameters, e.g., gas inflow, gas outflow, and / or the spatial distribution of the gas inflow or gas outflow.

[0158] According to various embodiments, the transport device 804 of the coating system 800A can have an unwinding roller 814 for unwinding a strip-shaped substrate 110 toward the coating regions 806 (n = 1 to N). Furthermore, the transport device 804 of the coating system 800A can have a take-up roller 816 for winding the strip-shaped substrate 110, which is transported from the direction of the coating regions 806 (n = 1 to N).

[0159] A strip-shaped substrate 110 (strip substrate) can comprise or be formed from a film, a nonwoven, a strip, and / or a woven fabric. For example, a strip-shaped substrate 110 can comprise or be formed from a metal strip, a metal foil, a plastic strip (polymer strip), and / or a plastic film (polymer film). According to various embodiments, the strip substrate 110 can comprise or be formed from any material, e.g., a metal, a semimetal, a polymer, a glass, or any other material that can be processed with a correspondingly low material thickness and / or as fibers using rolls 802 or rollers 802. Clearly, a strip substrate can be any substrate 110 that can be wound onto and / or unwound from a roll 814, 816 and / or processed, for example, from roll to roll.Depending on the material, a tape substrate 110 may have a thickness in a range from about a few micrometers (e.g., from about 1 µm) to about a few millimeters (e.g., up to about 10 mm).

[0160] According to various embodiments, the substrate transport device 804 of the coating system 800A can have a plurality of transport rollers 802 which define a (e.g., singly or multiply curved) transport path 111p (or a correspondingly singly or multiply curved transport surface 111f), along which the strip-shaped substrate 110 is transported between the unwinding roller 814 and the winding roller 816 past the coating regions 806 (n = 1 to N).

[0161] Another design of the coating system is in Fig. 8B. Here, the transport device 804 of the coating system 800B can have a plurality of transport rollers 802 configured to transport a plate-shaped substrate 110. The plate-shaped substrate 110 can be transported, for example, resting on the transport rollers 802 and / or inserted into a substrate carrier 818.

[0162] According to various embodiments, the transport device 804 may include a transport drive 820, which may be coupled to at least some of the plurality of transport rollers 802 and optionally to the unwind roller 814 and the take-up roller 816. For example, the transport drive 820 may be coupled to the rollers 802, 814, 816 by means of chains, belts, or gears. The transport rollers 802 and the transport drive 820 may be part of the substrate transport device 804.

[0163] Optionally, the control device 112 can be configured to control and / or regulate the transport device 804 (e.g., its transport drive 820). For example, the parameters of the transport device 804 can be used as control parameters, e.g., a transport speed, a substrate position, a substrate flow rate, etc. It is understood that these parameters, such as the transport speed, can influence the production of the layer stack and therefore be part of the information determined (according to the target layer stack).

[0164] Furthermore, the control device 112 can be configured to control and / or regulate the formation of a layer stack (e.g., the layer stack 200). For example, the parameters of each coating device of the plurality of coating devices 104 (n = 1 to N) and / or their power supply can be used as control parameters, e.g., a consumed electrical power, an applied electrical voltage, a consumed electrical current, and / or an emission rate.

[0165] According to various embodiments, a coating device 104(n) can be configured to coat the at least one (ie, exactly one or more than one) substrate 110, which is transported, for example, through the coating region of the coating device 104(n). For example, the coating device can be configured to provide a gaseous coating material (material vapor) and / or liquid coating material, which can be deposited, for example, on the at least one substrate 110 to form a layer.

[0166] Furthermore, the coating system 800A, 800B can comprise a sensor arrangement 822 (providing the measuring element) configured to detect (at least) one optical response (e.g., an optical spectrum) of the coated at least one substrate 110. This can be, for example, the (detected) optical response 302 described herein. The sensor arrangement 822 can comprise one or more than one optical sensor (e.g., spectrometer or spectrophotometer), e.g., one or more than one optoelectronic sensor.

[0167] The sensor arrangement 822 (e.g., a spectrometer arrangement) can be configured to provide the differentiation of the wavelengths of the radiation to be analyzed. For example, this can be achieved by means of a directional deflection of the radiation to be analyzed (e.g., by means of refraction and / or diffraction). For this purpose, the sensor arrangement 822 can, for example, comprise at least one prism and / or an optical grating. Alternatively or additionally, frequency components can be detected in an interferometer using Fourier analysis (e.g., an FTIR spectrometer).

[0168] Optionally, the sensor arrangement 822 may comprise one or more than one optical radiation source configured to emit optical radiation (also referred to as reference radiation), e.g., visible light, in the direction of the transport path 111p. The or each radiation source may, for example, comprise or be formed from an optoelectronic radiation emitter (e.g., a solid-state emitter such as a light-emitting diode, a spontaneous or stimulated radiation emitter), a gas discharge emitter (e.g., a fluorescent lamp), and / or a Planckian radiation emitter (e.g., having an incandescent filament).

[0169] At least one or each radiation source of the sensor arrangement 822 and at least one or each optical sensor of the sensor arrangement 822 can be arranged on opposite sides of the transport path 111p (e.g., for determining a transmission spectrum). Alternatively or additionally, at least one or each radiation source of the sensor arrangement 822 and at least one or each optical sensor of the sensor arrangement 822 can be arranged on the same side of the transport path 111p (e.g., for determining a reflection spectrum).

[0170] The sensor arrangement 822 can be arranged inside and / or outside the vacuum chamber 102. For example, the sensor arrangement 822 can include at least one optical sensor inside and at least one optical sensor outside the vacuum chamber 102.

[0171] The control device 112 may be configured to regulate the coating processes according to the target state of the layer stack 200 described herein. For example, the control device 112 may regulate each coating process according to the target layer state of the layer to be formed by the corresponding coating process.

[0172] For example, the control device 112 may be configured to determine, for each layer 204(n) of the layer stack 200, a layer thickness deviation between the predicted layer thickness 206(n)V and the target layer thickness (according to the target state) and to control the coating processes based on (e.g., using) the layer thickness deviations of the plurality of layers 204(n = 1 to N).

[0173] Fig. 9 shows a schematic flowchart 900 for controlling the coating processes according to various embodiments.

[0174] The control device 112 can be configured to implement the model 906 described herein. As described herein, the data representing the model 906 can be stored in the data memory of the control device 112. Furthermore, information 908 can be stored in the data memory, which indicates the reference requirement R(a*) and / or the reference state 200R of the shift state to be established. This information 906 can be provided, for example, by a user.

[0175] The control device 112 may be configured to detect optical response 302 of the coated substrate 110 detected by the sensor arrangement 822.

[0176] The control device 112 can be configured to determine (based on the optical response 302) the desired state of the layer stack 200 as explained herein and, based on this desired state of the layer stack 200, determine the information for regulating the coating processes. This information (also referred to as a control signal) can, for example, comprise one or more control parameters, R. In other embodiments, the information can comprise the desired state, and the control device 112 can be configured to determine the one or more control parameters, R, based on the information. For example, the information can comprise: a spatial distribution of the optical density of the layer stack, a geometry of the layers of the layer stack, and / or the optical densities of the layers of the layer stack, etc.

[0177] The one or more control parameters can generally be a parameter that defines the operating point of the at least one coating process. For example, the operating point of the or each coating process can be defined by multiple control parameters. For example, the at least one control parameter can include at least one of the following parameters: a transport speed (of the substrate), a coating rate, a gas flow, an electrical voltage, an electrical current, an electrical power, a temperature, a chemical gas composition, a spatial distribution of the gas supplied to the coating process, a process pressure, a gas partial pressure.

[0178] For communication with the sensor arrangement 822 and the plurality of coating devices, the control device 112 may have corresponding interfaces 904.

[0179] The control device 112 (e.g., its controller) can, for example, comprise a PI controller (also referred to as a proportional-integral controller). A PI controller can comprise a P element (proportional element) and an I element (integral element), which are coupled to one another. Alternatively or in addition to the PI controller, other controller types can be used, e.g., a P controller (comprising only the P element), an I controller (comprising only the I element), a D element (comprising only a differentiator element), a PD controller, a PD2 element with conjugate complex zeros, and / or a PID controller.

[0180] The optical response 302 can have multiple partial responses (e.g., partial spectra). For example, the sensor array 822 can be configured to provide multiple (e.g., three, four, five, six, seven, eight, nine, ten, or more than ten) detection regions, of which the sensor array 822 can detect a partial response (e.g., a partial spectrum) in each detection region. For example, the partial spectrum of a layer region of the layer stack 200 can be detected in each detection region.

[0181] As in Fig. As shown in Figure 9, the control of the coating processes can be designed as a control circuit (or control loop).

[0182] A schematic representation of aspects of an exemplary implementation 1200 of the method according to various embodiments is shown in Fig. 12, where the target state of the layer thickness distribution can optionally be based on the prediction of this. For comparison, Fig. 11 a schematic representation of the conventional procedure 1100.

[0183] Clearly, according to the method described herein, a layer stack can be formed on the substrate 110 which has a substantially homogeneous spatial distribution of one or more spectral properties.

[0184] Such a layer stack 1004 is exemplified in Fig. 10. The layer stack 1004 may have a first region 1002(1) and a second region 1002(2) (different from the first region). According to the method described herein, a uniformity of one or more than one (targeted) spectral property can be ensured at the expense of a uniformity of the layer thicknesses of the layers of the layer stack. Clearly, the uniformity of one or more than one (targeted) spectral property may be of greater importance than the uniformity of the layer thicknesses.

[0185] For example, the layer stack 1004 may have a different layer thickness distribution of the layers in the first region 1002(1) than in the second region 1002(2). However, the actual state of one or more spectral properties (e.g., the actual state I(a*) of the color value a*) may be substantially the same in the first region 1002(1) and the second region 1002(2).

[0186] According to various embodiments, the layer stack 1004 may (due to the rules described herein) exhibit invariance of the one or more spectral properties along a path 1006 between the first region 1002(1) and the second region 1002(2).

[0187] The invariance of a property can be understood as the fact that the variance of the property is smaller than a reference value by a mean. Similarly, a property can be understood as varying if its variance is greater than or equal to the reference value. The reference value can, for example, represent a variation around the mean of approximately 10%, approximately 5%, etc.

[0188] According to various embodiments, the layer thickness 206(n*)I of the at least one layer 204(n*) may vary along the path 1006 between the first region 1002(1) and the second region 1002(2) (i.e., its variance may be greater than or equal to the reference value). For example, the layer thickness 206(n*)I of the at least one layer 204(n*) may be distorted along the path 1006.

[0189] This may be due to the fact that the target layer state of at least one layer is determined dynamically in order to achieve the desired target color value at the expense of the uniformity of the layer thickness distribution, which is why the layer thickness distribution may be uneven, i.e. distorted.

Claims

[1] Method comprising: • Determining an indication that represents a desired state of a spatial distribution of an optical density of a layer stack (200) or a requirement (S(a*)) for a resulting spectral property (a*) of the layer stack (200), based on a comparison of a prediction (V(a*)) about an actual state of the spectral property (a*) of the layer stack (200) with the actual state (I(a*)) of the spectral property (a*), wherein the prediction (V(a*)) is based on a model of the layer stack (200) that implements a link between the indication and the spectral property (a*) of the layer stack (200); and • Controlling an actuator configured to influence at least one layer formation process of a plurality of layer formation processes used to form the layer stack (200) based on the indication. [2] Method according to claim 1, wherein the spectral property (a*) corresponds to at least one coordinate in a color space and / or at least one color value; wherein preferably the color space is one of the following color spaces: the CIELAB color space, the RLAB color space, the LLAB color space, a CIECAM color space, the IPT color space, the CAM02-UCS color space, the CAM16-UCS color space, the ICtCp color space, the Jzazbz color space, the SRLAB2 color space, or the Oklab color space. [3] The method according to claim 1 or 2, further comprising: Determining a correction (Δa*) for an output and / or input of the model based on the comparison; where the determination of the value is based on the correction (Δa*). [4] Method according to one of claims 1 to 3, further comprising: Determining the requirement (S(a*)) for the spectral property (a*) based on the comparison and on a user input representing a reference requirement (R(a*)) for the spectral property (a*) and / or for the spatial distribution of the optical density of the layer stack (200); where the information, if it represents the desired state of the spatial distribution of the optical density of the layer stack, is determined based on the requirement (S(a*)). [5] Method according to claim 4, • wherein the indication is further based on a spatial reference distribution of the optical density of the layer stack (200), which is determined by means of the model and based on the user input. [6] Method according to one of claims 1 to 5, further comprising: • Determining the prediction (V(a*)) about the actual state of the spectral property (a*) of the layer stack, preferably (200) by means of a variation calculation based on a reference distribution of the optical density of the layer stack (200) and / or a reference requirement (R(a*)) for the spectral property (a*) and / or for the spatial distribution of the optical density of the layer stack (200). [7] Method according to one of claims 1 to 6, wherein the determination of the information is based on a prediction (200V) about an actual state of the spatial distribution of the optical density of the layer stack (200), which is determined by means of the model, preferably based on the actual state (I(a*)) of the spectral property (a*); wherein the information is preferably determined by means of a variational calculation based on the prediction of the actual state of the spatial distribution of the optical density and / or the spectral property (a*) and optionally based on the requirement (S(a*)). [8] Method according to claims 6 and 7, wherein the variational calculation is applied to the geometry of the at least one layer (204(n*)) and leaves the remaining layers of the layer stack (200) invariant. [9] Method according to one of claims 1 to 8, further comprising: • Determining at least one layer (204(n*)) of the layer stack (200) whose geometry influences the spectral property (a*); and • Selecting the at least one layer formation process based on a result of determining the at least one layer (204(n*)) of the layer stack (200) whose geometry influences the spectral property (a*). [10] Method according to one of claims 1 to 9, further comprising: • Determining the actual state (I(a*)) of the spectral property (a*) based on an optical response (302) of the layer stack (200). [11] A computer program arranged, when executed by a processor, to cause the processor to perform the method according to any one of claims 1 to 10. [12] A computer-readable medium storing instructions arranged, when executed by a processor, to cause the processor to perform the method according to any one of claims 1 to 10. [13] Control device (112), comprising: • one or more than one processor configured to carry out the method according to any one of claims 1 to 10; and • one or more than one storage containing data representing the model. [14] Vacuum coating arrangement (100), comprising: • the control device (112) according to claim 13; • a plurality of coating devices (104) for performing the plurality of coating processes; and • the actuator. [15] Layer stack, comprising: • a first region (1002(1)) and a second region (1002(2)) which are spaced apart from each other along a path (1006); and • a plurality of layers (204) arranged one above the other along a direction transverse to the path (1006), of which one or more than one layer is dielectric and / or at least partially transparent; • wherein a spatially distributed spectral property (a*) of the layer stack (200) along the path (1006) has a variance of less than a reference value; • wherein a layer thickness (206) of at least a first layer (204(n*)) of the plurality of layers along the path (1006) has a variance of more than the reference value; • wherein preferably a layer thickness (206) of one or more than one second layer of the plurality of layers along the path (1006) has a variance of less than the reference value.

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