RF generator for a plasma generating system, such a plasma generating system and a method for operating the RF generator

Abstract

The invention relates to an RF generator (1) comprising a signal generating unit (4) and a waveform generating device (3). The signal generating unit is designed to generate an RF signal from a waveform (8, 9, 10) and to use a starting waveform (8) in a starting period (21), the starting waveform comprising starting target values (11) for a plurality of different power levels (12). The signal generating unit is designed to use an end waveform (10) in an end period (23), the end waveform comprising end target values (15) for a plurality of different power levels (16). The waveform generating device is designed to generate at least one intermediate waveform (9, 9a, 9b, 9c) on the basis of the starting target values and the end target values, the at least one intermediate waveform comprising intermediate target values (13) for a plurality of different power levels (14). The signal generating unit is designed to use the at least one intermediate waveform in an intermediate period (22).

Description

[0001] RF generator for a plasma production system, such a plasma production system and a method for operating the RF generator

[0002] The invention relates to an RF generator for a plasma generation system, such a plasma generation system and a method for operating the RF generator.

[0003] An RF generator, as used here, refers to an electrical power converter that converts electrical power of any frequency into a high frequency (RF). RF, in this context, refers to frequencies greater than or equal to 100 kHz, and specifically greater than or equal to 1 MHz. Various terms are used for such RF generators.

[0004] Such RF generators are described, for example, in one of the following documents: US 8,129,653 B2, there referred to as "plasma supply device",

[0005] US 7,452,443 B, there referred to as "vacuum plasma generator", or

[0006] US 10,354,839 B, there referred to as "power converter".

[0007] Surface treatment of workpieces using plasma and gas lasers are industrial processes in which, particularly in a plasma chamber, a plasma is generated with direct current or with a high-frequency alternating signal with a working frequency in the range of a few tens of kHz to the GHz range.

[0008] The plasma chamber is connected to a high-frequency generator (HF generator) via additional electronic components such as coils, capacitors, cables, or transformers. These additional components can be resonant circuits, filters, or impedance matching circuits. Plasma processes represent a highly variable load for an HF generator, depending on the conditions within the plasma chamber. In particular, the properties of the workpiece, electrodes, and gas conditions play a role.

[0009] RF generators have a limited operating range with respect to the impedance of the connected electrical load. If the load impedance deviates from a permissible range, the required energy / power cannot be delivered to the consumer. Damage to the RF generator is also possible.

[0010] For this reason, an impedance matching circuit, also called a "matchbox", is often used, which transforms the impedance of the load to a nominal impedance of the generator output.

[0011] The technical requirements for the RF generator are constantly increasing. The purpose of the RF generator is to transfer RF energy into the plasma chamber. This RF energy is used to ionize gases in the chamber, thus generating the plasma. Furthermore, the RF energy helps to stabilize the plasma and control its density and temperature. By adjusting the RF power, different plasma states can be achieved, which are required for various applications. In semiconductor manufacturing and materials processing, plasma chambers are often used for sputtering processes. In this process, ions from the plasma are directed onto a target, also called the "target material," causing atoms to be knocked out of the target and deposited onto a substrate. The RF generator enables control of the energy input into the plasma and thus control of the sputtering process.In CVD (Chemical Vapor Deposition) processes, reactive gases are introduced into the plasma chamber. The energy of the RF generator helps to decompose these gases and form reactive particles, which then deposit onto a substrate and form solid layers. The energy of the plasma can also be used to clean surfaces of contaminants, as the reactive particles in the plasma react with and remove the contaminants on the surface. The RF generator is therefore a crucial instrument for generating and controlling plasma in a plasma chamber and enables a wide variety of industrial and scientific processes.

[0012] In the past, RF generators were operated to produce an RF signal with a constant frequency and amplitude (CW signal). However, the demands placed on RF generators have increased, and they are now expected to generate various pulse patterns and arbitrary waveform signals. This is particularly relevant for modern etching applications with large aspect ratios, where process parameters are frequently changed during operation. This can cause plasma instability, leading to poorer process results.

[0013] The object of the present invention is therefore to create an RF generator for a plasma generation system with which the plasma is to be kept in a more stable state.

[0014] The problem is solved by the RF generator for a plasma generation system according to claim 1 and by the plasma generation system according to claim 23. Claim 24 describes a method for operating the RF generator. Claims 2 to 22 describe advantageous embodiments of the RF generator.

[0015] The RF generator described here is intended for use in a plasma generation system. The RF generator comprises a signal generation unit and a waveform generation unit. The waveform generation unit is designed to generate waveforms and transmit them to the signal generation unit. A waveform preferably refers to the amplitude profile of an RF signal. The RF signal is then amplitude-modulated with the waveform. The waveform exhibits lower frequency components than the unmodulated RF signal. The waveform can also be referred to as an "envelope." A waveform generation unit is an electronic unit that has an output which, during operation, carries a signal for controlling other components, such as the signal generator and / or the signal generation unit. A waveform generation unit can also have a control input, for example, a signal from a computer or a computer.The waveform generator has an electrical input for receiving data, e.g., from an operating unit and / or central control device. The waveform generator can output an analog and / or digital signal, from which the signal generator and / or signal generation unit produces a desired signal. The signal generation unit is designed to generate an RF signal, depending on the waveform used, which includes setpoint data for different power levels, and to output it at a terminal. A corresponding plasma can then be generated from the RF signal. The signal generation unit is designed to use a start waveform within a start period comprising several pulse periods, wherein the start waveform includes start setpoints for several different power levels.The start waveform can contain the start setpoints for the different power levels for several or all pulse periods. Alternatively, the start waveform contains the start setpoints for exactly one pulse period, with the start waveform being reused for each pulse period within the start period. The signal generation unit is configured to use an end waveform in an end period that comprises several pulse periods, with the end waveform containing end setpoints for several different power levels. The end waveform can contain the end setpoints for the different power levels for several or all pulse periods. Alternatively, the end waveform contains the end setpoints for exactly one pulse period, with the end waveform being reused for each pulse period within the end period.The waveform generation device is configured to generate at least one intermediate waveform based on the start setpoints of the start waveform and the end setpoints of the end waveform, wherein the at least one intermediate waveform includes intermediate setpoints for several different power levels. The signal generation unit is configured to use the at least one intermediate waveform and output a corresponding RF signal according to the at least one intermediate waveform during an intermediate period comprising one or more pulse periods and arranged between the start period and the end period. It is particularly advantageous that the transition between the start waveform and the end waveform does not occur abruptly, but that one or more intermediate waveforms are used to "smooth" this transition.This gradual modification of the setpoint curves prevents the formation of instabilities in the plasma caused by an overly abrupt transition in the RF signal. This allows the process parameters to be continuously adjusted during operation. It has been found that this method improves plasma stability.

[0016] A power level can be a constant value of a signal, such as power. However, a power level can also be a continuously changing value of a signal, such as power.

[0017] The transition from the initial waveform to the intermediate waveform can be initiated after a specific time or upon the presence of a signal, such as a trigger signal set by the user or received by an external device. Until then, the initial waveform can be continuously repeated in a loop. During the transition, i.e., the intermediate period, the initial waveform is transformed into the final waveform. This transformation, also known as "morphing," can encompass a varying number of pulse periods within the intermediate period, depending on the magnitude of the difference between the initial and final waveforms. This allows for particularly stable plasma operation. In one aspect of the development, the initial and final waveforms differ in the magnitude of at least one of the different power levels.For example, the start and end waveforms can comprise ten different power levels, such as power plateaus, with the amplitude of at least one power level differing from that of at least one other power level. The jump in the amplitude of the corresponding power level from the start waveform to the amplitude of the corresponding power level in the end waveform is mitigated by the amplitude of the corresponding power level in at least one intermediate waveform. The differing power level can be higher or lower in the end waveform than the corresponding power level in the start waveform. In this way, the plasma can be kept particularly stable.

[0018] Additionally or alternatively, the number of power levels in the initial waveform can differ from the number of power levels in the final waveform. The intermediate waveform attempts to mitigate this jump and, for example, successively introduces or removes additional power levels over several pulse periods in the intermediate timeframe. In this way, the plasma can be kept particularly stable.

[0019] Additionally or alternatively, the duration of at least one of the power stages in the start waveform can differ from the duration of the corresponding power stage in the end waveform. If a power stage in the start waveform has a duration of, for example, 1 ms and in the end waveform a duration of, for example, 3 ms, then the power stage in the intermediate waveform can have a duration of, for example, 2 ms. This reduces the size of the jump between the duration of the power stage in the start waveform and the duration of its corresponding power stage in the end waveform. In this way, the plasma can be kept particularly stable.

[0020] In one aspect of the development, the waveform generation device is designed to compare the respective power level of the start waveform with the respective power level of the end waveform, which is located at the same position in the respective waveform or occurs at the same time in the respective waveform, for any differences. For example, if there are ten different power levels in the start waveform and ten different power levels in the end waveform, the first power level of the start waveform and the first power level of the end waveform are compared for differences, such as amplitude or duration. The same applies to the respective second, third, etc., power levels. In this way, the plasma can be kept particularly stable.

[0021] In one aspect of the development, the waveform generation unit is an integral part of the RF generator. Theoretically, it would be conceivable to implement the waveform generation unit's functionality via an external operating unit and / or central control device. However, it has been found that this approach cannot achieve the required response speeds. Therefore, such functionality has previously been considered of little use. Integrating this functionality into the RF generator now allows for sufficiently fast response times if an intermediate waveform is specified for the transition from the start waveform to the final waveform. This enables particularly stable plasma flow.

[0022] In one aspect of the development, the same applies if the number of power levels differs between the initial waveform and the final waveform. The waveform generation device is designed to determine at which position or time at least one additional power level was added, or at which position or time a power level was removed. This is done particularly by considering the additional power levels, which preferably have not all changed from the initial waveform to the final waveform.If, for example, the starting waveform comprises ten power levels and the final waveform nine power levels, and if power levels one to six and eight to ten of the starting waveform correspond to power levels one to nine of the final waveform, then the waveform generation device can detect that the seventh power level of the starting waveform no longer appears in the final waveform. The respective intermediate waveforms can include the seventh power level, for example, with an increasingly shorter time interval between the first and last intermediate waveforms, so that the "disappearance" of the seventh power level is gradual. In this way, the plasma can be kept particularly stable.

[0023] In one aspect of the development process, each power stage remains constant. This means that the power output at that stage does not change over time, for example, always remaining at 600 W. The level of each power stage is also characterized by a corresponding start, intermediate, or final setpoint. This allows the plasma to be kept particularly stable.

[0024] In one aspect of the development, the waveform generation device is designed to correlate the start and end waveforms to determine any differences. Various algorithms, such as cross-correlation, can be used for this purpose. The result is the identification of power levels in the start and end waveforms that differ from their corresponding power levels (e.g., same position or time within the waveform) in amplitude or duration. The occurrence of newly added or removed power levels between the start and end waveforms can also be reliably detected in this way. This allows for particularly stable plasma flow.

[0025] In one aspect of the development, the waveform generation device includes an AI module, which is designed to generate at least one intermediate waveform based on the start and end waveforms. The current plasma process can also be fed to the AI ​​module. This allows the plasma to be kept particularly stable. The AI ​​module is an interacting unit of software and hardware, e.g., computer components, processing units, memory, and input / output devices, designed to achieve and / or utilize results according to at least one of the routines of so-called artificial intelligence (AI). Such routines can include, for example:

[0026] - Supervised Learning

[0027] - Unsupervised Learning

[0028] - Reinforcement Learning

[0029] - Deep Learning

[0030] - Transfer Learning,

[0031] - Generative Adversarial Networks (GANs).

[0032] Supervised learning describes a method in which models are provided with training data consisting of input-output pairs. In this way, the models can learn the relationship between inputs and outputs.

[0033] Unsupervised learning is an approach in which models learn independently from a data pool without being provided with predefined categories or labels. Methods such as clustering and dimensionality reduction are used. In reinforcement learning, models acquire the ability to make decisions by performing actions and receiving feedback in the form of rewards or penalties.

[0034] Deep learning is a machine learning method based on artificial neural networks with numerous layers. This technology makes it possible to recognize complex patterns and hierarchies in data.

[0035] Transfer learning uses models that have already been trained on large datasets to quickly master similar but new tasks. This approach significantly accelerates the training process and allows models to be adapted with less data.

[0036] Generative Adversarial Networks (GANs) are a method in which two neural networks compete against each other. While one of the networks creates artificial data, the other network's task is to evaluate the authenticity of this data.

[0037] In one aspect of the development, the waveform generation device is designed to adopt those power levels from the start waveform or those power levels from the end waveform for the at least one intermediate waveform that are identical in both the start and end waveforms. For example, if the third power level in the start waveform is identical with respect to the level of the corresponding start setpoint to the corresponding, for example, also third, power level in the end waveform with respect to the level of the corresponding end setpoint, then this power level is also used in the at least one intermediate waveform with the same level of the corresponding intermediate setpoint.For example, if the starting setpoint for the third power stage in the starting waveform is 600 W, and the final setpoint of the corresponding (e.g., third) power stage in the final waveform is also 600 W, then the corresponding (e.g., third) power stage of the intermediate waveform is also set to 600 W with respect to its intermediate setpoint. The term "identical" also includes minor deviations of preferably no more than two percent, and in particular no more than one percent. In this way, the plasma can be kept particularly stable.

[0038] In one aspect of the development, the waveform generation device is designed to generate an intermediate waveform for each pulse period within the interval. Preferably, each intermediate waveform differs from the preceding and subsequent intermediate waveforms. The difference can lie in the magnitude of the intermediate setpoint for the respective power level, for example, an increase from 600 W to 650 W. The difference can also lie in the duration of a power level, for example, from 1 ms to 1.5 ms. The difference can also lie in the number of power levels, for example, from ten power levels in one intermediate waveform to eleven power levels in the adjacent intermediate waveform. In this way, the plasma can be kept particularly stable.

[0039] In one aspect of the development, the number of intermediate waveforms can be specified by the user. Additionally or alternatively, the number of intermediate waveforms depends on the number of pulse periods of the intermediate period, specifically on the duration of the transition from the start period to the end period. Additionally or alternatively, the number of intermediate waveforms depends on the magnitude of the difference between the start waveform and the end waveform, specifically on the difference in the setpoint values ​​and / or the duration of the power levels and / or the number of power levels. A small difference preferably results in a shorter intermediate period, and a larger difference preferably results in a longer intermediate period. For example, the difference in the setpoint values ​​for each individual power level between the start waveform and the end waveform can be summed up.This summed amount can then determine the number of pulse periods in the intermediate period and thus its duration. Alternatively, the greatest difference between the initial setpoint of a power stage in the initial waveform and the final setpoint of the corresponding power stage in the final waveform can be used to determine the number of pulse periods in the intermediate period. Similarly, the greatest difference between the duration of a power stage in the initial waveform and the duration of the corresponding power stage in the final waveform can be used to determine the number of pulse periods in the intermediate period. Finally, the difference between the summed durations of all power stages in the initial waveform and the summed durations of all power stages in the final waveform can be used as a criterion for determining the number of pulse periods required in the intermediate period.In this way, the plasma can be kept particularly stable.

[0040] In one aspect of the development, the waveform generation device is designed to generate a first set of intermediate waveforms when the difference between a power level in the start waveform and a corresponding power level in the end waveform exceeds a first threshold. Furthermore, the waveform generation device is designed to generate a second set of intermediate waveforms when the difference between a power level in the start waveform and a corresponding power level in the end waveform is less than a second threshold. The first threshold is higher than the second, and the first set of intermediate waveforms is higher than the second. This ensures that the transition from the start waveform to the end waveform is not too abrupt. In this way, the plasma can be kept particularly stable.

[0041] In one aspect of the development, the waveform generation device is designed to generate at least one intermediate waveform such that at least one intermediate setpoint for a power stage of the at least one intermediate waveform lies between a start setpoint of the corresponding power stage in the start waveform and a final setpoint of the corresponding power stage in the final waveform. If four intermediate waveforms are used, the intermediate setpoint for a power stage of the first intermediate waveform can be, for example, 600 W. The intermediate setpoint for a power stage of the second intermediate waveform can be, for example, 700 W. The intermediate setpoint for a power stage of the third intermediate waveform can be, for example, 800 W. The intermediate setpoint for a power stage of the fourth, i.e., last, intermediate waveform can be, for example, 800 W. This ensures a linear transition from the start waveform to the final waveform.It can also proceed exponentially, asymptotically, or according to a quadratic form. In this way, the plasma can be kept particularly stable.

[0042] In one aspect of the development, the intermediate setpoint for the power stage of at least one intermediate waveform lies midway between the starting setpoint of the corresponding power stage in the starting waveform and the final setpoint of the corresponding power stage in the final waveform. For example, if the starting setpoint of a power stage in the starting waveform is 500 W and the final setpoint of the corresponding power stage in the final waveform is 1000 W, then the intermediate setpoint for a power stage of at least one intermediate waveform would be 750 W. This allows the plasma to be kept particularly stable.

[0043] In one aspect of the development, at least two successive intermediate waveforms are identical.

[0044] In one aspect of the development, the waveform generation device is designed to generate multiple intermediate waveforms such that the intermediate setpoint of a first intermediate waveform for a power stage is closer to the start setpoint of the corresponding power stage of the start waveform than to the end setpoint of the corresponding power stage of the end waveform. For example, if the start setpoint is 500 W and the end setpoint is 1000 W, the intermediate setpoint of the first intermediate waveform is closer to 500 W than to 1000 W. It can be, for example, 600 W or 700 W, but not 800 W.Furthermore, the waveform generation device is designed to generate several intermediate waveforms such that the intermediate setpoint of the last intermediate waveform for a power stage is closer to the final setpoint of the corresponding power stage of the final waveform than to the starting setpoint of the corresponding power stage of the starting waveform. For example, if the starting setpoint is 500 W and the final setpoint is 1000 W, the intermediate setpoint of the last intermediate waveform is closer to 1000 W than to 500 W. It can be, for example, 700 W or 900 W, but not 400 W. In this way, the plasma can be kept particularly stable.

[0045] In one aspect of the development, a transition occurs from the intermediate setpoint of at least one power stage of the first intermediate waveform to the intermediate setpoint of at least the same power stage of the last intermediate waveform, with a multitude of further intermediate waveforms in between, linearly, exponentially, or quadratically. In this way, the plasma can be kept particularly stable.

[0046] In one aspect of the development, the waveform generation device is designed to generate multiple intermediate waveforms such that the number of intermediate setpoints increases or decreases from a first intermediate waveform to a final intermediate waveform by adding or removing further intermediate setpoints. Preferably, this increase or decrease occurs uniformly across the various intermediate waveforms. In this way, the plasma can be kept particularly stable.

[0047] In one aspect of the development, the waveform generation device is designed to generate at least one intermediate waveform such that the length of at least one power stage of this intermediate waveform lies between the length of the corresponding power stage in the start waveform and the length of the corresponding power stage in the final waveform. For example, if the first power stage of the start waveform has a length of 1 ms and the first power stage of the final waveform has a length of 3 ms, the length of the first power stage for the intermediate waveform can be set to 2 ms. The same applies if multiple intermediate waveforms are used.For example, if there are three intermediate waveforms, the first power stage of the first intermediate waveform might have a duration of, say, 1.5 ms, whereas the first power stage of the second intermediate waveform might have a duration of, say, 2 ms, while the first power stage of the third and final intermediate waveform might have a duration of, say, 2.5 ms. This significantly smooths the transition from the first power stage of the starting waveform to the first power stage of the final waveform. In this way, the plasma can be kept particularly stable.

[0048] In one aspect of the development, the waveform generation device is designed to increase the duration of a power stage in at least one intermediate waveform compared to the duration of the corresponding power stage in the initial waveform by adding at least one additional intermediate setpoint value, which defines the power stage of the at least one intermediate waveform. This is because, for example, a power controller, to which the corresponding setpoint values ​​are fed, reads the setpoints at a specific clock rate and regulates the RF signal accordingly. If the power controller reads a new setpoint value every millisecond, for example, and each power stage is defined by a setpoint value, the duration of the power stage would double if a second setpoint value for the power stage were added.If a power stage is defined by four setpoints and another setpoint is added, the power stage lasts 5 ms instead of 4 ms. The same applies when a setpoint is reduced. In this case, the waveform generation device is configured to reduce the duration of a power stage in at least one intermediate waveform compared to the duration of the corresponding power stage in the start waveform by removing at least one intermediate setpoint that defines the power stage of that intermediate waveform. The RF signal is preferably controlled significantly faster than the clock rate at which new setpoints are read. Preferably, each setpoint for the same power stage is identical. This allows the plasma to be kept particularly stable.

[0049] In one aspect of the development, the waveform generation device is designed to arrange the intermediate setpoints of all power stages within the intermediate waveform in such a way that the intermediate setpoints are spaced equally in time within the intermediate waveform as the start setpoints of all power stages in the start waveform or as the end setpoints of all power stages in the end waveform. In this case, the power controller would receive the corresponding setpoint value at the point in time at which it is located within the respective waveform. If the setpoints are all spaced equally in time, the power controller will always receive a new setpoint at the same interval, to which it will subsequently regulate the RF signal.If a new intermediate setpoint is added to an intermediate waveform, or if a previous intermediate setpoint is removed, the waveform generation device is configured to arrange the subsequent intermediate setpoints in the intermediate waveform such that they are all equidistant from each other, and preferably also equidistant from each other as the start setpoints in the start waveform and / or as the end setpoints in the end waveform. This ensures that the plasma remains particularly stable.

[0050] In one aspect of the development, the initial setpoint values ​​of the initial waveform are evenly distributed over time. Each performance level is defined by at least one initial setpoint value.

[0051] Additionally or alternatively, each power stage of the start waveform is initiated with a start setpoint. The power controller, which receives this start setpoint, regulates the RF signal to the corresponding start setpoint. In this case, the power stage has a constant power output. Alternatively, each power stage of the start waveform is initiated and terminated with a start setpoint. The power controller preferably receives both start setpoints of a power stage and is configured to interpolate the power between the two start setpoints, in particular linearly, exponentially, or using a quadratic function. If both start setpoints are identical, the power stage has a constant power output. In this way, the plasma can be kept particularly stable.

[0052] In one aspect of the development, the final setpoint values ​​of the final waveform are evenly distributed over time. Each performance level is defined by at least one final setpoint value.

[0053] Additionally or alternatively, each power stage of the final waveform is introduced with a final setpoint. The power controller, which receives this final setpoint, regulates the RF signal to the corresponding final setpoint. In this case, the power stage has a constant power output. Alternatively, each power stage of the final waveform is introduced and terminated with a final setpoint. The power controller preferably receives both final setpoints of a power stage and is configured to interpolate the power between the two final setpoints, in particular linearly, exponentially, or using a quadratic function. If both final setpoints are identical, the power stage has a constant power output.

[0054] In one aspect of the development, the intermediate setpoints of at least one intermediate waveform are evenly distributed over time. Each performance level is defined by at least one intermediate setpoint.

[0055] Additionally or alternatively, each power stage of at least one intermediate waveform is introduced with an intermediate setpoint. The power controller, which receives this intermediate setpoint, regulates the RF signal to the corresponding intermediate setpoint. In this case, the power stage has a constant power output. Alternatively, each power stage of at least one intermediate waveform is introduced and terminated with an intermediate setpoint. The power controller preferably receives both intermediate setpoints of a power stage and is configured to interpolate the power between the two intermediate setpoints, in particular linearly, exponentially, or using a quadratic function. If both intermediate setpoints are identical, the power stage has a constant power output. In this way, the plasma can be kept particularly stable.

[0056] In one aspect of the development, all power levels of the initial waveform are defined by the same number of initial setpoints. Additionally or alternatively, all power levels of at least one intermediate waveform are defined by the same number of intermediate setpoints. Additionally or alternatively, all power levels of at least one final waveform are defined by the same number of final setpoints. This allows the plasma to be kept particularly stable.

[0057] In one aspect of the development, the signal generation unit includes a power controller, which is configured to regulate the output power of the RF signal to the start setpoints of the corresponding power stages of the start waveform, to the end setpoints of the corresponding power stages of the end waveform, and to the intermediate setpoints of the corresponding power stages of at least one intermediate waveform. In this way, the plasma can be kept particularly stable.

[0058] In one aspect of the design, the power controller is configured to maintain or interpolate the output power between two initial setpoints of the corresponding power stages of the initial waveform. The power controller is also configured to maintain or interpolate the output power between two final setpoints of the corresponding power stages of the final waveform. Furthermore, the power controller is configured to maintain or interpolate the output power between two intermediate setpoints of the corresponding power stages of at least one intermediate waveform. Interpolation can be linear, exponential, or quadratic. This allows for particularly stable plasma operation.

[0059] In one aspect of the development, the signal generation unit is designed to change the clock rate at which the power controller reads the start, intermediate, and / or final setpoints. This can cause a corresponding waveform to last longer or shorter, thus distorting it. If the only difference between the start and end waveforms is that each power stage in the end waveform lasts twice as long as the corresponding power stage in the start waveform, then the clock rate at which the power controller reads the setpoints can be changed.If the power controller reads a start setpoint of the start waveform every 1 ms and a final setpoint of the final waveform every 3 ms, the power controller can be configured to read a corresponding intermediate setpoint of the intermediate waveform every 2 ms for at least one intermediate waveform. The amplitudes for the corresponding power levels in the start waveform, the intermediate waveform, and the final waveform can remain unchanged, as only the duration of the respective power level is adjusted by changing the clock rate of the power controller. The control speed, i.e., the time the power controller needs to set the corresponding setpoint, can remain unchanged. In this way, the plasma can be kept particularly stable.

[0060] One aspect of the design incorporates a ring buffer. The waveform generation unit is configured to load the start waveform into the ring buffer for each pulse period of the start waveform. Additionally or alternatively, the waveform generation unit is configured to load the end waveform into the ring buffer for each pulse period of the end waveform. Additionally or alternatively, the waveform generation unit is configured to load at least one intermediate waveform corresponding to each pulse period into the ring buffer. This allows the required waveforms to be provided quickly and efficiently. Supplying the current waveforms via external interfaces, such as a PLC, would be too slow for the desired operation of the RF generator.

[0061] Additionally or alternatively, the signal generation unit is configured to load the start waveform from the ring buffer for each pulse period of the start waveform. Additionally or alternatively, the signal generation unit is configured to load the end waveform from the ring buffer for each pulse period of the end waveform. Additionally or alternatively, the signal generation unit is configured to load at least one intermediate waveform belonging to each pulse period from the ring buffer. By using a ring buffer, the waveform generation device can directly load a portion of the new waveform into the ring buffer, while the signal generation unit simultaneously loads a portion of the previous waveform from the ring buffer and generates the corresponding RF signal from it. In this way, the plasma can be kept particularly stable.

[0062] In one aspect of the development, the waveform generation device is designed to display a temporal sequence of the start waveform, at least one intermediate waveform, and the final waveform on the visualization device for the user. This allows the user to verify, in particular, whether the corresponding intermediate waveform represents a smooth transition between the start and final waveforms. In this way, the plasma can be kept particularly stable.

[0063] One aspect of the development includes an input device designed to receive user input. Specifically, the waveform generation unit is configured to determine the number of intermediate waveforms based on this input. Additionally or alternatively, the input can specify the differences in power levels between each intermediate waveform and the next. Additionally or alternatively, the duration of each power level for each intermediate waveform can also be specified. Additionally or alternatively, the input can specify the function used to transition each intermediate waveform to the next. For example, linear, exponential, and / or quadratic functions could be selected. This allows for particularly stable plasma operation.

[0064] In one aspect of the development, the waveform generator, signal generation unit, power controller, and ring buffer are integrated, for example, into a common signal processor, specifically a common programmable logic device (PLD), particularly a so-called "field-programmable gate array" (FPGA). This allows for particularly stable plasma operation. The memory can also be located externally from the processor or PLD and connected to it via data transmission.

[0065] In one aspect of the development, the signal generation unit includes an amplifier unit. An amplifier unit is an electronic amplifier unit designed to amplify an electrical input signal with a first power level to produce an electrical output signal with a second, higher power level. Such an amplifier unit can include one or more transistors to amplify the input signal. It can also include other electronic components, such as capacitors, resistors, inductors, diodes, transformers, filters, and resonant elements. It can be at least partially integrated into a circuit (IC). This allows the plasma to be kept particularly stable.

[0066] In one aspect of the development, the signal generation unit is designed to generate the RF signal output by the RF generator by providing an amplifier unit with a corresponding RF signal to be amplified, according to the appropriate waveform, and / or by varying the supply voltage and / or current of the amplifier unit so that the amplifier unit outputs the desired RF signal. This allows the plasma to be kept particularly stable.

[0067] In one aspect of the development, the signal generation unit includes a signal generator. This allows the plasma to be kept particularly stable. A signal generator is an electronic unit with an output that can output an electrical signal during operation. This can be a small signal, meaning a signal with a power of less than 1 W and / or a voltage of less than 10 V. The signal can have any waveform. Such a signal generator can, for example, include a digital-to-analog converter (DAC). This is designed to convert a sequence of digital values ​​into an analog signal that is applied to the output. Such a signal generator can also include other electronic components, such as capacitors, resistors, inductors, diodes, transformers, filters, and resonant elements. It can be at least partially integrated into a circuit (IC).It can be arranged together with the amplifier unit in an integrated circuit.

[0068] In one aspect of the development, the signal generation unit includes a power supply unit. This allows the plasma to be kept particularly stable. The power supply unit is an electronic unit with an output that, during operation, provides electrical power to supply other components, such as the amplifier unit or the signal generator.

[0069] The power supply unit can, for example, include a voltage source.

[0070] The supply unit can, for example, include a power source.

[0071] Such a power supply unit may contain other electronic components, such as capacitors, resistors, inductors, diodes, transformers, filters, and resonant elements. It may be at least partially integrated into a circuit (IC).

[0072] In one aspect of the development, the signal generation unit includes a power regulator. This allows for particularly stable plasma operation. A power regulator is an electronic unit with an output that carries a signal during operation to control other components. A power regulator may also have an electrical input for receiving an electrical measurement signal. The power regulator is designed to drive the signal generator, the amplifier unit, and / or the power supply unit in such a way that the desired RF signal is output at the amplifier unit. The plasma generation system described here can be configured, for example, as follows: It includes an RF generator as described above. Furthermore, an impedance matching device with an input and an output connection may be provided.The input terminal of the impedance matching device is connectable to the output terminal of the RF generator, preferably via a first cable connection. The output terminal of the impedance matching device is connectable to a load, in particular an electrode in a plasma chamber, preferably via a second cable connection. A control device is also provided. Furthermore, a first measuring unit and / or a second measuring unit is provided, wherein the first measuring unit is arranged between the RF generator and the impedance matching device and is configured to determine the power and / or complex values ​​for the current and voltage of the generated RF signal, preferably on the first cable connection.Additionally or alternatively, the second measuring unit is arranged between the impedance matching device and the load and is configured to determine power and / or complex values ​​for a current and voltage of the RF signal, preferably on the second cable connection. The control device is configured to use measurement results from the first measuring unit and / or the second measuring unit and / or the generated RF signal to control the impedance matching device such that it adjusts the impedance at the output terminal to a predetermined value.

[0073] The plasma generation system described here can also be configured as follows, for example: It comprises an RF generator as described above, but no additional impedance matching device. The impedance matching can then be integrated into the RF generator. This allows the RF generator to be connected directly to a load, in particular an electrode in a plasma chamber, preferably via a second cable connection. A measuring unit can also be provided, which can be arranged at the output of the RF generator and is configured to determine power and / or complex values ​​for current and voltage of the generated RF signal. A control device can also be provided, which is configured to control the impedance matching in the RF generator based on measurement results from the measuring unit and / or the generated RF signal, such that it sets the impedance at the output terminal to a predetermined value.

[0074] The method described here can be used to generate an RF signal, particularly with an RF generator. In a first step, the RF signal is generated from a start waveform within a start time period, which comprises several pulse periods and includes start setpoints for several different power levels. In a second step, the RF signal is generated from an end waveform within a final time period, which also comprises several pulse periods and includes final setpoints for several different power levels.In an intermediate process step, at least one intermediate waveform is generated based on the start setpoints of the start waveform and the end setpoints of the end waveform. The waveform generation device is specifically configured to generate at least one intermediate waveform based on these setpoints. This intermediate waveform includes intermediate setpoints for several different power levels. In a further intermediate process step, the RF signal is generated from the intermediate waveform within an intermediate time period. This intermediate time period comprises one or more pulse periods and is positioned between the start period and the end period.

[0075] The following describes the development purely by way of example, with reference to the drawings. Figure 1 shows an embodiment of the plasma generation system with a

[0076] RF generator;

[0077] Figure 2: another embodiment of the plasma generation system with the RF generator;

[0078] Figure 3: an embodiment of how the waveforms are generated from which the RF generator produces the desired RF signal;

[0079] Figure 4A: a transition from a starting waveform through several intermediate waveforms to a final waveform;

[0080] Figure 4B: a temporal sequence of several start waveforms through several intermediate waveforms to several final waveforms;

[0081] Figures 5A, 5B, 5C: a first, second and third intermediate waveform, with the duration of the intermediate waveforms increasing;

[0082] Figures 6A, 6B, 6C: a first, second and third intermediate waveform, with an additional power stage inserted; and

[0083] Figure 7: an embodiment of the method for generating an RF-

[0084] Signals with the RF generator;

[0085] Figures 8A, 8B, 8C: a first, second, and third intermediate waveform with continuously changing power levels. Figure 1 shows a plasma generation system 100 comprising an RF generator 1, a central control device 50, an impedance matching circuit 60, and a load, which can also be referred to as a load 70, in particular in the form of a plasma chamber. The RF generator 1 is configured to provide an RF signal, in particular in the form of a pulsed high-frequency signal, with a nominal power PNent and a frequency fo, and to output it at an output terminal 2. The impedance matching circuit 60 comprises an input terminal 60a, wherein the RF generator 1 is connected at its output terminal 2 to the input terminal 60a via a first cable connection 61. The impedance matching circuit 60 further comprises an output terminal 60b.The output terminal 60b is connected to at least one consumer 70 via a second cable connection 62. The first and / or second cable connection 61, 62 can comprise one or more cables, for example, connected in series and / or parallel. Coaxial cables are preferably used.

[0086] The consumer 70, i.e., the plasma chamber, comprises at least one electrode 71 for generating a plasma 72. The electrode 71 is connected to the output terminal 60b of the impedance matching circuit 60. In this embodiment, a camera system 73 is also arranged in the plasma chamber, which is configured to observe the plasma 72.

[0087] The central control device 50 is preferably a processor and / or FPGA and / or microcontroller and / or ASIC programmed according to its suitability or configuration. The central control device 50 may also include a storage device, among other things.

[0088] The central control device 50 is configured to control the RF generator 1, in particular to activate or deactivate it. Additionally or alternatively, the central control device 50 is also configured to change the power and / or frequency of the RF signal by appropriately controlling the RF generator 1. Additionally or alternatively, the central control device 50 is configured to change the waveform of the high-frequency signal by appropriately controlling the RF generator 1. This can include, for example: the type of high-frequency signal, the modulation of the RF signal, pulse durations, and pulse repetition rate. The central control device 50 is also configured to input an arbitrary waveform into the RF generator 1, which it generates and outputs at its output terminal 2.

[0089] The central control device 50 is preferably also configured to control the impedance matching circuit 60. In particular, the central control device 50 is configured to change the transformation ratio within the impedance matching circuit 60 and / or to specify an impedance at the output terminal 60b. Additionally or alternatively, the central control device 50 is configured to specify the impedance at the input terminal 60a, which acts on the RF generator 1.

[0090] The plasma generation system 100 also includes a first measuring unit 80. The first measuring unit 80 is preferably arranged between the RF generator 1 and the impedance matching circuit 60. The first measuring unit 80 is configured, for example, to measure power transmitted from the RF generator 1 towards the impedance matching circuit 60 and power reflected back towards the RF generator 1. Alternatively, the first measuring unit 80 can also be configured to measure the impedance at the input terminal 60a of the impedance matching circuit 60.

[0091] For this purpose, the first measuring unit 80 includes, for example, a directional coupler unit.

[0092] The first measuring unit 80 can measure the power of a forward and reversed high-frequency signal on the first cable connection 61 via the directional coupler unit in order to calculate the respective power or impedance at the input terminal 60a. The first measuring unit 80 can alternatively also include a current sensor and a voltage sensor. The central control device 50 is configured to calculate the respective power or impedance at the input terminal 60a, to which the RF generator 1 is connected with its output, based on the measurement result of the directional coupler unit or the current and voltage sensors.

[0093] The plasma generation system 100 preferably also includes a second measuring unit 81. The second measuring unit 81 is preferably arranged between the impedance matching circuit 60 and the load 70. The second measuring unit 81 is configured, for example, to measure the power transmitted from the impedance matching circuit 60 to the load 70 and to measure the power reflected back towards the impedance matching circuit 60. Alternatively, the second measuring unit 81 can also be configured to measure the impedance at the output terminal 60b of the impedance matching circuit 60.

[0094] For this purpose, the second measuring unit 81 includes, for example, a directional coupler unit. Using the directional coupler unit, the second measuring unit 81 can measure the power of a forward and reverse high-frequency signal on the second cable connection 62 in order to calculate the respective power or impedance at the output terminal 60b. Alternatively, the second measuring unit 81 can also include a current sensor and a voltage sensor. The central control device 50 is configured to calculate the respective power or impedance at the output terminal 60b, to which the load 70 is connected with its input, based on the measurement result of the directional coupler unit or the current and voltage sensors. Naturally, the first measuring unit 80 and / or the second measuring unit 81 can also be arranged within the impedance matching circuit 60.The first measuring unit 80 is located at the input terminal 60a and the second measuring unit 81 at the output terminal 60b.

[0095] The plasma generation system 100 preferably includes an operating unit 90. The operating unit 90 may have a visualization device 20. The visualization device 20 is preferably a screen, in particular a touchscreen. In addition to a screen, the operating unit 90 may also include input devices such as a keyboard and / or mouse. The operating unit 90 may also be a web server that provides data and receives user input. The central control device 50 is configured to receive input from the operating unit 90.

[0096] The central control device 50 is preferably configured to receive setpoint specifications, for example for the power of the high-frequency signal, from the operating unit 90. Additionally or alternatively, the frequency and / or waveform of the high-frequency signal and / or the pulse rate and / or the pulse duration of the high-frequency signal can be received from the operating unit 90. A desired impedance at the output terminal 60b of the impedance matching circuit 60 can also be received via the operating unit 90. From this, corresponding control variables for the RF generator 1 and control data for the impedance matching circuit 60 can be generated and transmitted to it.

[0097] Preferably, the control unit 90 is directly connected to the RF generator 1. The RF generator 1 comprises a waveform generation unit 3 and a signal generation unit 4, which is shown as a dotted line in Figure 1. The signal generation unit 4 comprises an amplifier unit 5, a power controller 27, a signal generator 6, and a power supply unit 7. The amplifier unit 5 can have one or more power amplifiers. The power controller 27 is configured to control the signal generator 6, the amplifier unit 5, and / or the power supply unit 7 such that the desired RF signal is output at the end of the amplifier unit 5.

[0098] The signal generator 6 is configured to generate an RF signal to be amplified and to feed it to the amplifier unit 5. The amplifier unit 5 is configured to amplify the RF signal to be amplified and to output it at the output terminal 2 of the RF generator 1. The power supply unit 7 is configured to supply the amplifier unit 5 with electrical energy. As described, the RF generator 1 is configured to generate a pulsed RF signal or an RF signal with an arbitrary waveform. To ensure that the RF signal follows the specified parameters, the power supply unit 7 can modulate the supply current and / or the supply voltage of the amplifier unit 5 accordingly, for example, by applying pulse patterns.

[0099] A multitude of waveforms are fed to the signal generation unit 4. These waveforms consist of a start waveform 8, at least one intermediate waveform 9, and at least one final waveform 10. In this case, there is a first intermediate waveform 9a, a second intermediate waveform 9b, and a third and thus final intermediate waveform 9c. The signal generation unit 4 is configured to generate the RF signal, depending on the waveform 8, 9, or 10 used, which contains setpoint data for different power levels, and to output it at the output terminal 2. The first intermediate waveform 9a is more similar to the start waveform 8 than to the final waveform 10, and the third, in this case final, intermediate waveform 9c is more similar to the final waveform 10 than to the start waveform 8.However, the first intermediate waveform 9a differs from the start waveform 8, and the third, in this case last, intermediate waveform 9c differs from the final waveform 10.

[0100] Figure 2 shows another embodiment of the plasma generation system 100 with the RF generator 1. In contrast to Figure 1, the central control device 50 is arranged in the RF generator 1 and, in particular, in the waveform generation unit 3. Accordingly, the first and second measuring units 80, 81 are connected to the RF generator 1.

[0101] Figure 3 shows an embodiment of how the RF generator 1 can be controlled via the control unit 90 so that it outputs an RF signal according to the corresponding waveforms. The start waveform 8 and the end waveform 10 are supplied to the waveform generation unit 3, or the start waveform 8 and the end waveform 10 are stored in a memory which the waveform generation unit 3 accesses.

[0102] The start waveform 8 comprises start setpoints 11, which define different power levels 12. The start setpoints 11 define a power Pi and are spaced apart from each other on a time axis t. The power of the start setpoints 11 corresponds to the output power of the RF signal. In this embodiment, the first start setpoint 11 is higher than the second start setpoint 11. The respective power levels 12 have a constant power over time.

[0103] The final waveform 10 comprises final setpoints 15, which define different power levels 16. The final setpoints 15 define a power Pi and are spaced apart from each other on a time axis t. The power of the final setpoints 15 corresponds to the output power of the RF signal. In this embodiment, the first final setpoint 15 is lower than the second final setpoint 15. The respective power levels 16 have a constant power over time.

[0104] In this embodiment, the waveform generation device 3 comprises a memory, in particular a ring buffer 17, and a processing unit 18. The processing unit 18 is preferably configured for signal processing, in particular a processor unit, microprocessor unit and / or digital signal processing unit, and may optionally include a K-module 19. The memory, in particular the ring buffer 17, may also be arranged in the signal generation unit 4 or as a separate element within the RF generator 1 between the waveform generation device 3 and the signal generation unit 4.

[0105] The waveform generation device 3 is configured to generate at least one intermediate waveform 9 based on the start setpoints 11 of the start waveform 8 and the end setpoints 15 of the end waveform 10, wherein the at least one intermediate waveform 9 comprises intermediate setpoints 13 for several different power levels 14. The intermediate waveform 9 is generated, in particular, based on differences between the start waveform 8 and the end waveform 10. These differences can be determined by the waveform generation device 3.

[0106] The diagram shows that the first intermediate setpoint 13 is lower than the first start setpoint 11, and that the second intermediate setpoint 13 is higher than the second start setpoint 11. The first power level 14 of the intermediate waveform 9 decreases, and the second power level 14 of the intermediate waveform 9 increases. Thus, the intermediate waveform 9 represents an average of the start waveform 8 and the final waveform 10. In this embodiment, for clarity, there is only one intermediate waveform 9. However, as mentioned earlier, there can be any number of intermediate waveforms 9. The waveform generation device 3 is preferably configured to display a temporal sequence of the start waveform 8, the at least one intermediate waveform 9, and the final waveform 10 on a visualization device for a user. The user sees the entire transition from start waveform 8 to end waveform 10.The user can preferably also configure or select how the respective setpoints 11, 13, 15 transition from the initial waveform 8, through at least one intermediate waveform 9, to the final waveform 10. The transition can thus be described according to a linear, exponential, or quadratic function. The user can preferably also manually adjust the amplitude of the individual setpoints 11, 13, 15 within the respective waveforms 8, 9, 10.

[0107] Also shown is a visualization device 20. This can be, for example, a screen, a projection, a display, or a comparable device. The waveform generation device is configured to display a temporal sequence of the start waveform 8, at least one intermediate waveform 9, 9a, 9b, 9c, and the final waveform 10 on the visualization device 20 for a user.

[0108] Figure 4A shows a transition from a start waveform 8 through several intermediate waveforms 9, 9a, 9b, 9c to a final waveform 10. In this case, there are three intermediate waveforms 9, 9a, 9b, 9c. The intermediate setpoints 13 of the different intermediate waveforms 9, 9a, 9b, 9c are further apart where the corresponding start and final setpoints 11, 15 are also further apart. Because the RF generator 1 outputs not only the start waveform 8 and the final waveform 10, but also the three intermediate waveforms 9, 9a, 9b, 9c, the transition from the start waveform 8 to the final waveform 10 is not so abrupt. This results in a more stable plasma 72. In the embodiment shown in Figure 4A, the duration of the start waveform 8 and the end waveform 10 does not change.Furthermore, the number of power levels between start waveform 8 and end waveform 10 does not change. Only the values ​​of the corresponding setpoints 11 and 15 change.

[0109] Figure 4B shows a temporal sequence of several start waveforms 8 through several intermediate waveforms 9, 9a, 9b, 9c to several final waveforms 10. In this embodiment, the start waveform 8 is periodically repeated by the RF generator 1 over several pulse periods, in this case over three pulse periods. This occurs within a start period 21. Within the start period 21, only the start waveform 8 is output. The waveform generation unit 3 is configured in this case to write only the start waveform 8 to the ring buffer 17, while the signal generation unit 4 is configured to successively load this start waveform 8 from the ring buffer 17 for each pulse period and generate a corresponding RF signal from it. It would also be conceivable that the signal generation unit 4 loads the start waveform 8 only once from the ring buffer 17 and periodically "plays it back".

[0110] After the start period 21, an intermediate period 22 follows. During this intermediate period 22, which in this case comprises several pulse periods, the RF signal is generated according to the intermediate waveforms 9. Preferably, the intermediate period 22 comprises as many pulse periods as there are intermediate waveforms 9. In this case, there are three intermediate waveforms 9a, 9b, 9c, so there are also three pulse periods. The waveform generation device 3 is configured to write the respective intermediate waveforms 9a, 9b, 9c belonging to the corresponding pulse period into the ring buffer 17. The signal generation unit 4 is configured to successively load the respective intermediate waveforms 9a, 9b, 9c from the ring buffer 17 for each pulse period and then generate the corresponding RF signal from them. It is also conceivable that the same intermediate waveform 9, 9a, 9b, 9c is present over several pulse periods.

[0111] Subsequently, after the RF signal has been generated according to the third, and therefore last, intermediate waveform 9c, the final waveform 10 is periodically output by the RF generator 1 over several pulse periods, in this case over three pulse periods. This occurs within a final time period 23. Within this final time period 23, only the final waveform 10 is output. In this case, the waveform generation unit 3 is configured to write only the final waveform 10 to the ring buffer 17, while the signal generation unit 4 is configured to successively load this final waveform 10 from the ring buffer 17 for each pulse period and generate a corresponding RF signal from it. It would also be conceivable that the signal generation unit 4 loads the final waveform 10 only once from the ring buffer 17 and periodically "plays it back".

[0112] Figures 5A, 5B, and 5C show a first, second, and third (here, the last) intermediate waveform 9a, 9b, 9c, with the duration of the intermediate waveforms 9 increasing from the first intermediate waveform 9a to the third, i.e., last, intermediate waveform 9c. The duration of each intermediate waveform 9a, 9b, 9c can be modified by various means. For example, the waveform generation device 3 can be configured to increase the duration of a power stage 14 of at least one intermediate waveform 9a, 9b, 9c compared to the duration of the corresponding power stage 12 in the start waveform 8 by adding at least one additional intermediate setpoint 13, which defines the power stage 14 of the at least one intermediate waveform 9a, 9b, 9c. In this case, the signal generation unit 4 would read in such an additional intermediate setpoint 13 and feed it to the power controller located there.The corresponding intermediate setpoints 13 are supplied periodically, so that the duration of each intermediate waveform 9a, 9b, 9c increases accordingly with each additional intermediate setpoint 13. Alternatively, the duration that describes how often a corresponding intermediate setpoint 13 is passed to the power controller of the signal generation unit 4 can be increased. This also lengthens the individual intermediate waveforms 9a, 9b, 9c relative to each other. The above would also apply if the duration of each intermediate waveform 9a, 9b, 9c were to decrease from the first intermediate waveform 9a to the third and, in this case, last intermediate waveform 9c.

[0113] Figures 6A, 6B, and 6C show a first, second, and third, here the last, intermediate waveform 9a, 9b, 9c, wherein an additional power level 14a is inserted into intermediate waveform 9. Preferably, the amplitude of this additional power level 14a differs only minimally from the preceding and / or subsequent power level 14 at the beginning. In other words, the amplitude of this additional power level 14a, which is defined by at least one corresponding additional intermediate setpoint 13a, increases successively from the first intermediate waveform 9a to the third, in this case last, intermediate waveform 9c. Additionally or alternatively, the duration of this additional power level 14a is initially shorter and increases successively from the first intermediate waveform 9a to the third, in this case last, intermediate waveform 9c.This additional power stage 14a can be inserted into an existing power stage 14, as shown in Figure 6B, or between two existing power stages 14.

[0114] Figure 7 shows a method used to generate an RF signal with the RF generator 1. In a first process step Si, the RF signal is generated from a start waveform 8 in a start period 21, wherein the start period 21 comprises several pulse periods and wherein the start waveform 8 includes start setpoints 11 for several different power levels 12. In a second process step S2, the RF signal is generated from an end waveform 10 in an end period 23, wherein the end period 23 comprises several pulse periods and wherein the end waveform 10 includes end setpoints 15 for several different power levels 16.In a first intermediate process step Sia, at least one intermediate waveform 9 is generated based on the start setpoints 11 of the start waveform 8 and the end setpoints 15 of the end waveform 10, wherein the waveform generation device 3 is configured to generate at least one intermediate waveform 9 based on the start setpoints 11 of the start waveform 8 and the end setpoints 15 of the end waveform 10, wherein the at least one intermediate waveform 9 includes intermediate setpoints 13 for several different power levels 14. In a second intermediate process step Sib, the RF signal is generated from the at least one intermediate waveform 9 in an intermediate period 22, wherein the intermediate period 22 comprises one or more pulse periods and wherein the intermediate period 22 is arranged between the start period 21 and the end period 23.

[0115] Figures 8A, 8B, and 8C show a first, second, and third intermediate waveform, here the last intermediate waveform 9a, 9b, 9c, whereby, in contrast to the first, second, and third intermediate waveforms 9a, 9b, 9c of Figures 6A, 6B, 6C, the power levels 14 change continuously and are not fixed levels. Furthermore, an arbitrary curve of a power level 16 is also shown, which adapts from a first, through a second, to a third, here the last intermediate waveform 9a, 9b, 9c.

[0116] The development is not limited to the described embodiments. Within the scope of the development, all described and / or drawn features can be combined with one another as desired, unless otherwise specified.

Claims

Claims 1. RF generator (1) for a plasma generation system (100) comprising a signal generation unit (4) and a waveform generation device (3), wherein the waveform generation device (3) is configured to transmit waveforms (8, 9, 10) to the signal generation unit (4), wherein the signal generation unit (4) is configured to generate an RF signal depending on the waveform (8, 9, 10) used, which includes setpoint data (11, 13, 15) for different power levels (12, 14, 16), and to output it at an output terminal (2), wherein a plasma (72) can be generated from the RF signal, having the following features: - the signal generation unit (4) is configured to use a start waveform (8) in a start time period (21) which includes several pulse periods, wherein the start waveform (8) includes start setpoints (11) for several different power levels (12); - the signal generation unit (4) is configured to use an end waveform (10) in an end time period (23) which includes several pulse periods, wherein the end waveform (10) includes end setpoints (15) for several different power levels (16); - the waveform generation device (3) is configured to generate at least one intermediate waveform (9, 9a, 9b, 9c) based on the start setpoints (11) of the start waveform (8) and the end setpoints (15) of the end waveform (10), wherein the at least one intermediate waveform (9, 9a, 9b, 9c) includes intermediate setpoints (13) for several different power levels (14); - the signal generation unit (4) is configured to use at least one intermediate waveform (9, 9a, 9b, 9c) in an intermediate period (22) which comprises one or more pulse periods and is arranged between the start period (21) and the end period (23).

2. RF generator (1) according to claim 1, characterized by the following features: - the start waveform (8) and the end waveform (10) differ in at least one of the following: a) in the amplitude of at least one of the power levels (12, 16), b) in the number of power levels (12, 16), c) in the duration of at least one of the power levels (12, 16).

3. RF generator (1) according to claim 2, characterized by the following feature: - the waveform generation device (3) is designed to compare the respective power stage (12) of the start waveform (8) with the respective power stage (16) of the end waveform (10), which are arranged at the same position in the respective waveform (8, 10) or occur at the same time in the respective waveform (8, 10), for any difference.

4. RF generator (1) according to claim 2 or 3, characterized by the following feature: - the waveform generation device (3) is designed to correlate the start waveform (8) and the end waveform (10) with each other in order to determine a difference.

5. RF generator (1) according to one of the preceding claims, characterized by the following feature: - the waveform generation device (3) is configured to select those power levels (12) from the start waveform (8) or those power levels (16) from the end waveform (10) for the corresponding power level (14) of the at least one intermediate waveform (9, 9a, 9b, 9c) to adopt which are identical in the start waveform (8) and in the end waveform (10).

6. RF generator (1) according to one of the preceding claims, characterized by the following feature: - the waveform generation device (3) is designed to generate an intermediate waveform (9, 9a, 9b, 9c) for each pulse period in the intermediate time period (22).

7. RF generator (1) according to one of the preceding claims, characterized by at least one of the following features: - the number of intermediate waveforms (9, 9a, 9b, 9c): a) can be specified by a user; b) depends on the number of pulse periods of the intermediate time period (22); c) depends on the magnitude of the difference between the start waveform (8) and the end waveform (10).

8. RF generator (1) according to claim 7, characterized by the following features: - the waveform generation device (3) is designed to generate a first number of intermediate waveforms (9, 9a, 9b, 9c) when there is a difference between a power stage (12) in the start waveform (8) and a corresponding power stage (16) in the end waveform (10) that is greater than a first threshold value; - the waveform generation device (3) is designed to generate a second number of intermediate waveforms (9, 9a, 9b, 9c) when there is a difference between a power level (12) in the start waveform (8) and a corresponding power level (16) in the end waveform (10) that is smaller than a second threshold value; The first threshold is greater than the second threshold, and the first number is greater than the second number.

9. RF generator (1) according to one of the preceding claims, characterized by the following feature: - the waveform generation device (3) is designed to generate at least one intermediate waveform (9, 9a, 9b, 9c) such that at least one intermediate setpoint (13) for a power stage (14) of the at least one intermediate waveform (9, a9, 9b, 9c) lies between a start setpoint (11) of the corresponding power stage (12) in the start waveform (8) and a final setpoint (15) of the corresponding power stage (16) in the final waveform (10).

10. RF generator (1 ) according to claim 9, characterized by the following feature: - the intermediate setpoint (13) for the power level (14) of at least one intermediate waveform (9, 9a, 9b, 9c) lies in the middle between the start setpoint (11) of the corresponding power level (12) of the start waveform (8) and the final setpoint (15) of the corresponding power level (16) in the final waveform (10).

11. RF generator (1) according to one of the preceding claims, characterized by the following features: - the waveform generation device (3) is configured to generate several intermediate waveforms (9, 9a, 9b, 9c) such that: a) an intermediate setpoint (13) of a first intermediate waveform (9a) for a power stage (14) is closer to a start setpoint (11) of the corresponding power stage (12) of the start waveform (8) than to a final setpoint (15) for the corresponding power stage (16) of the final waveform (10); and b) an intermediate setpoint (13) of a last intermediate waveform (9c) for a power level (14) is closer to a final setpoint (15) of the corresponding power level (16) of the final waveform (10) than to a start setpoint (11) for the corresponding power level (12) of the start waveform (8).

12. RF generator (1) according to claim 11, characterized by the following feature: - a transition from the intermediate setpoint (13) of at least one power level (14) of the first intermediate waveform (9a) to the intermediate setpoint (13) of at least one corresponding power level (14) of the last intermediate waveform (9c), with one or more further intermediate waveforms (9b) in between, proceeds linearly, exponentially or quadratically.

13. RF generator (1 ) according to one of the preceding claims, characterized by the following features: - the waveform generation device (3) is configured to generate several intermediate waveforms (9, 9a, 9b, 9c) such that the number of intermediate setpoints (13) increases or decreases by adding or removing at least one further intermediate setpoint (13a) from a first intermediate waveform (9a) to a last intermediate waveform (9c).

14. RF generator (1 ) according to one of the preceding claims, characterized by the following feature: - the waveform generation device (3) is configured to generate at least one intermediate waveform (9, 9a, 9b, 9c) such that at least one length for a power stage (14) of the at least one intermediate waveform (9, 9a, 9b, 9c) is between a length of the corresponding power stage (12) in the start waveform (8) and a length of the The corresponding power level (16) is located in the final waveform (10).

15. RF generator (1 ) according to claim 14, characterized by the following feature: - the waveform generation device (3) is configured to increase the length for a power stage (14) of the at least one intermediate waveform (9, 9a, 9b, 9c) compared to a length of the corresponding power stage (12) in the start waveform (8) by adding at least one additional intermediate setpoint, by which the power stage (14) of the at least one intermediate waveform (9, 9a, 9b, 9c) is defined; and / or - the waveform generation device (3) is configured to reduce the length for a power stage (14) of the at least one intermediate waveform (9, 9a, 9b, 9c) compared to a length of the corresponding power stage (12) in the start waveform (8) by removing at least one intermediate setpoint (13) by which the power stage (14) of the at least one intermediate waveform (9, 9a, 9b, 9c) is defined.

16. RF generator (1 ) according to claim 15, characterized by the following feature: - the waveform generation device (3) is designed to arrange the intermediate setpoints (13) of all power stages (14) of the intermediate waveform (9, 9a, 9b, 9c) such that the intermediate setpoints (13) are spaced equally apart in time in the intermediate waveform (9, 9a, 9b, 9c) as the start setpoints (11) of all power stages (12) in the start waveform (8) and / or as the final setpoints (15) of all power stages (16) in the final waveform (10).

17. RF generator (1 ) according to one of the preceding claims, characterized by the following features: - the start setpoints (11) of the start waveform (8) are evenly distributed across the start waveform (8); and / or each power stage (12) of the start waveform (8) is initiated with a start setpoint (11); or each power stage (12) of the start waveform (8) is initiated and terminated with a start setpoint (11); and / or - the final setpoints (15) of the final waveform (10) are evenly distributed across the final waveform (10); and / or each power stage (16) of the final waveform (10) is introduced with a final setpoint (15); or each power stage (16) of the final waveform (10) is introduced and ended with a final setpoint (15); and / or - the intermediate setpoints (13) of the at least one intermediate waveform (9, 9a, 9b, 9c) are evenly distributed over the at least one intermediate waveform (9, 9a, 9b, 9c); and / or each power stage (14) of the at least one intermediate waveform (9, 9a, 9b, 9c) is introduced with an intermediate setpoint (13); or each power stage (14) of the intermediate waveform (9, 9a, 9b, 9c) is introduced with an intermediate setpoint (13) and terminated with an intermediate setpoint (13).

18. RF generator (1 ) according to one of the preceding claims, characterized by the following features: - the signal generation unit (4) comprises a power controller, wherein the power controller is configured to adjust the output power of the RF signal to the: a) Start setpoints (11) of the corresponding power levels (12) of the start waveform (8); b) End setpoints (15) of the corresponding power levels (16) of the end waveform (10); c) Intermediate setpoints (13) of the corresponding power levels (14) of at least one intermediate waveform (9, 9a, 9b, 9c); to be controlled.

19. RF generator (1 ) according to claim 18, characterized by the following features: - the power controller is designed to keep the output power constant or to interpolate it between two start setpoint values ​​(11) of the corresponding power levels (12) of the start waveform (8); - the power controller is designed to keep the output power constant or to interpolate it between two final setpoint values ​​(15) of the corresponding power stages (16) of the final waveform (10); - the power controller is designed to keep the output power constant or to interpolate it between two intermediate setpoints (13) of the corresponding power levels (14) of at least one intermediate waveform (9, 9a, 9b, 9c).

20. RF generator (1 ) according to claim 18 or 19, characterized by the following features: - the signal generation unit (4) is designed to change the clock rate at which the power controller reads the start setpoints (11), intermediate setpoints (13) and / or final setpoints (15).

21. RF generator (1) according to one of the preceding claims, characterized by the following features: - a ring buffer (17) is provided, wherein: a) the waveform generation device (3) is configured to load the start waveform (8) into the ring buffer (17) for each pulse period of the start waveform (8); and / or the waveform generation device (3) is configured to load the end waveform (10) into the ring buffer (17) for each pulse period of the end waveform (10); and / or the waveform generation device (3) is configured to load at least one intermediate waveform (9, 9a, 9b, 9c) belonging to the pulse period of the intermediate waveform (9) into the ring buffer (17) for each pulse period of the intermediate waveform (9); and / or b) the signal generation unit (4) is configured to load the start waveform (8) from the ring buffer (17) for each pulse period of the start waveform (8); and / or the signal generation unit (4) is configured to load the final waveform (10) from the ring buffer (17) for each pulse period of the final waveform (10);and / or the signal generation unit (4) is configured to load at least one intermediate waveform (9, 9a, 9b, 9c) belonging to the pulse period of the intermediate waveform (9) from the ring buffer (17).

22. RF generator (1 ) according to one of the preceding claims, characterized by the following features: - the waveform generation device (3) is designed to display a temporal sequence of the start waveform (8), the at least one intermediate waveform (9, 9a, 9b, 9c) and the final waveform (10) on the visualization device (20) for a user.

23. Plasma generation system (100) with an RF generator (1) according to one of the preceding claims, characterized by the following features: - an impedance matching device (60) with an input terminal (60a) and an output terminal (60b) is provided; - the input terminal (60a) of the impedance matching device (60) can be connected to the output terminal (2) of the RF generator (1) via a first cable connection (61), in particular connected; - the output terminal (60b) of the impedance matching device (60) can be connected to a load (70), in particular an electrode (71) in a plasma chamber, via a second cable connection (62); - a control device (50) is provided; - a first measuring unit (80) and / or a second measuring unit (81) is provided, wherein: a) the first measuring unit (80) is arranged between RF generator (1) and impedance matching device (60) and is configured to determine power and / or complex values ​​for current and voltage of the generated RF signal on the first cable connection (61); and / or b) the second measuring unit (81) is arranged between impedance matching device (60) and the load (70) and is configured to determine power and / or complex values ​​for current and voltage of the RF signal on the second cable connection (62); - the control device (50) is designed to control the impedance matching device (60) on the basis of measurement results from the first measuring unit (80) and / or second measuring unit (81) and / or on the basis of the generated RF signal in such a way that it sets the impedance at the output terminal (60b) to a predetermined value.

24. Method for generating an RF signal with an RF generator (1), in particular according to one of claims 1 to 22, for a plasma generation system (100) to generate a plasma (72) from the RF signal, using the following process steps: - Generation (Si) of the RF signal from a start waveform (8) in a start period (21) wherein the start period (21) includes several pulse periods and wherein the start waveform (8) includes start setpoints (11) for several different power levels (12); - Generation (S2) of the RF signal from an end waveform (10) in an end time period (23), wherein the end time period (23) comprises several pulse periods and wherein the end waveform (10) comprises end setpoints (15) for several different power levels (16); - Generating (Sia) at least one intermediate waveform (9, 9a, 9b, 9c) based on the start setpoints (11) of the start waveform (8) and the end setpoints (15) of the end waveform (10), wherein in particular the waveform generation device (13) is configured to generate at least one intermediate waveform (9, 9a, 9b, 9c) based on the start setpoints (11) of the start waveform (8) and the end setpoints (15) of the end waveform (10), wherein the at least one intermediate waveform (9, 9a, 9b, 9c) includes intermediate setpoints (13) for several different power levels (14); - Generation (Sib) of the RF signal from the at least one intermediate waveform (9, 9a, 9b, 9c) in an intermediate period (22), wherein the intermediate period (22) comprises one or more pulse periods and wherein the intermediate period (22) is positioned between the start period (21) and the end period (23).

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