High-power generator and method for supplying high-power pulses

Abstract

A high power (HP) generator (10) and a method for delivering pulsed high power at high voltage and / or current values ​​to a capacitive load, in particular a plasma process, comprising: a plurality of low power (LP) generators (14, 16, 18), each including an energy storage component (C1, L1), wherein, during use, the energy storage component (C1, L1) is charged to a predetermined value associated with the energy storage component; Each provides, when in use, at its output an LP generator value that corresponds to the value of the energy storage components (C1, C2, Cn, L1, L2, Ln) incorporated in the respective LP generator (14, 16, 18) Multiple LP generators (14, 16, 18) and - a coupling (20), the LP generators (14, 16, 18) being electrically connected such that a coupling value at an output of the coupling (20) can be obtained which corresponds to an output value of the HP generator (10) and which is higher than the LP generator value at the output of one of the LP generators (14, 16, 18) during at least a plurality of states of the HP generator (10) in use; - a control unit (22) configured to select the contribution of the LP generators (14, 16, 18) to the output value of the HP generator (10) during the power delivery of the HP generator (10) in order to produce a rise and / or a decay of a pulse at the output of the coupling (20); Including, The control unit (22) furthermore determines the contribution of the LP generators (14, 16, 18) according to the following characteristics: The output of the coupling (20) and / or the output of the HP generator (10) is a stepped waveform, particularly at the rising and / or falling edges of a pulse and / or during that pulse. The method is configured to select one or some combination of the above to be achieved.

Description

[Technical Field]

[0001] The present invention relates to a high power (HP) generator configured to deliver pulsed high power of high voltage value and / or high current to a capacitive load, in particular to a plasma process. The present invention also relates to a method for supplying high power pulses to a plasma process. [Background technology]

[0002] A capacitive load refers to a load having a capacitive portion, meaning that a voltage rise across the load indicates a high current characteristic. The capacitive portion in this case may be at least 100 pF, preferably 200 pF or more, for example, about 500 pF. This may be a load in a plasma process, for example, in a plasma processing application.

[0003] Some plasma processing applications, such as etching and film deposition, require the supply of high-voltage (HV), high-frequency (HF) rectangular asymmetric pulsed voltages, which often exceed the voltage handling capabilities of individual semiconductor switches, especially when high-frequency operation is required. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 10,474,184B2 [Patent Document 2] U.S. Patent No. 10,607,813 B2 [Patent Document 3] U.S. Patent Application Publication No. 202001186794A1 [Patent Document 4] U.S. Patent No. 9,287,086B2

[0005] Summary of the Invention The object of the present invention is to provide a high power generator and a method for supplying high power pulses to a plasma, which allows for the supply of rapidly varying power (pulses) to a plasma process.

[0006] According to a first aspect, the present invention relates to a high power (HP) generator configured to deliver high power of high voltage and / or current values ​​to a load, in particular a plasma process, comprising: Some low power (LP) generators, each including an energy storage component, wherein during use the energy storage component is charged to a predetermined value associated with the energy storage component; Each provides an LP generator value, when in use, at its output that corresponds to the value of the energy storage component built into the respective LP generator. Several low-power generators, a coupling, the LP generators being electrically connected in such a way that a coupling value at the output of the coupling can be obtained which corresponds to an output value of the HP generators and which, in use, is higher than the LP generator value at the output of one of the LP generators in at least some states of the HP generators; a control unit configured to select the contribution of the LP generator to the output value of the HP generator during the power delivery of the HP generator in order to produce a rise and / or decay of pulses at the output of the coupling; Includes:

[0007] According to one embodiment, the output of the coupling and / or the output of the HP generator (10) is, in use, a stepped waveform, in particular a true stepped waveform with no continuous slope.

[0008] According to one embodiment, the LP generators are activated sequentially during a pulse. This means that not all LP generators are activated at once at the beginning of the pulse. For example, if the pulse length is 0.5 μs to 2 μs, a first LP generator or a stack of several LP generators is activated at the beginning of the pulse. After a few tens or hundreds of nanometers, one or several additional LP generators are activated, thereby causing a pulse at the output of the HP generator to rise. Then, after a few more tens or hundreds of nanometers, the next LP generator or stack of LP generators is activated, causing the pulse to rise further. As the pulse decays, one or more of the LP generators are similarly deactivated in a stepwise fashion. "Activating one or several LP generators" means that the control unit selects these LP generators to contribute to the output value of the HP generator during power delivery from the HP generator. In other words, the control unit can be configured to select the contribution of each LP generator to the output value of the HP generator multiple times during a pulse at the output of the HP generator.

[0009] According to one embodiment, the coupling comprises five or more electrically connected LP generators, in particular six or more LP generators, preferably ten or more, most preferably fifteen or more LP generators, such a large number of LP generators makes it possible to provide a true stepped waveform without a continuous gradient.

[0010] In one embodiment, the control unit is configured to select the contribution of the LP generator such that at least one amplitude step is less than 500V and / or such that a generator with a continuous gradient output is not required.

[0011] Such a solution eliminates the need for a generator that produces a continuous gradient, making the HP generator more efficient.

[0012] In one embodiment, the coupling and control unit is configured to connect the LP generator by switching only.

[0013] In one embodiment, the control unit may be configured to select the contribution of the LP generator to the output value of the HP generator to form a step line pulse waveform at the rising and / or falling edge of the pulse.

[0014] In one embodiment, the number of LP generators is sufficiently large to produce, at the output of the coupling, pulses having voltage rise and / or fall values ​​equal to or greater than the sum of the values ​​of the LP generators, and a step line pulse waveform in which the value of one step corresponds to a value equal to or greater than the value of one or more of the LP generators.

[0015] According to one embodiment, charging energy for the LP generators is provided through a transformer having a primary winding and a secondary winding for each LP generator, the secondary windings connected to a rectifier, and each rectifier connected to the energy storage component of the corresponding LP generator. The rectifier may include at least one semiconductor device, such as a diode. The rectifier may include four diodes connected as a bridge rectifier. The rectifier and / or the transformer may be part of the generator.

[0016] Some, and in particular each LP generator may have a transformer associated with it.

[0017] Each of the transformers corresponding to several, in particular one, LP generators may have its own magnetic core.

[0018] Each transformer corresponding to several, in particular one, LP generators may include a balance winding, preferably two balance windings.

[0019] This allows the AC supply current to flow freely around the transformer, providing charge to the loaded stage, i.e., the LP generator connected to the load, and preventing overcharging of the unloaded stage, i.e., the LP generator that is not connected to a load and therefore not contributing to the HP generator's output. The same concept can be used to power a driver circuit.

[0020] One balance winding of one transformer may be connected to the balance winding of another transformer.

[0021] Thus, the transformers corresponding to several, in particular one, LP generators may be connected in an open chain configuration.

[0022] Some of the primary windings, in particular the primary windings of the transformers corresponding to one LP generator, may be connected in series, which may mean that one wire is guided through all the transformers in series that are adapted to receive the AC supply current.

[0023] High voltages and currents can be efficiently and effectively separated if each transformer has its own magnetic core and the only shared element is the primary winding which can be made from one common wire.

[0024] Each transformer corresponding to several, particularly one, LP generators, also called "stages", may be implemented as a ring-core transformer.

[0025] In one embodiment, a balancing circuit including components that allow current to flow only in one direction, particularly diodes or components that behave like diodes, is connected between the two LP generators. For example, the negative outputs of some, particularly the energy storage components of each LP generator, particularly the capacitors, are connected to the same potential as the preceding LP generator with such a balancing circuit. This allows a switch in parallel with the load to be operated so that, when the value of the energy storage component of the lower LP generator exceeds that of the higher LP generator, charge from the energy storage component of the lower LP generator is transferred to the energy storage component of the higher LP generator. "Activated" means "switched to an on state" or "switched to a low impedance at its output." "Switch in parallel with the load" refers to a switching element that, when activated, serves to disconnect the corresponding LP generator from its neighboring connected LP generators. In Figures 2a, 2b, 4, and 5, these are switching element S1. In Figure 3, these are switching element S2. "Connecting switch" refers to a switching element that, when activated, serves to connect the corresponding LP generator. In Figures 2a, 2b, 4, and 5, these are switching element S2. In Figure 3, these are switching element S1. The energy storage components of the highest LP generators accumulate excess charge from the entire stack. Therefore, these highest LP generators can advantageously be controlled in a way that provides more power to the load than the other LP generators to remove the excess charge.

[0026] In one embodiment, a damping circuit may be positioned between some, particularly all, of the LP generators in an open chain configuration. Open chain configuration means that such a damping circuit is positioned between each LP generator and its neighboring, higher LP generator, rather than between the highest and lowest. The damping circuit may include a resistor and / or an inductor if the energy storage component is a capacitor. The damping circuit may include a resistor and / or a capacitor if the energy storage component is an inductor. The damping circuit between the LP generators may be preferably positioned in series with the balancing circuit. The damping circuit may be used to eliminate oscillations on parasitic components in the charge handling path.

[0027] The entire HP generator can be directly liquid cooled. This can be done by immersion dielectric cooling, and the LP generator in particular is immersed in the dielectric cooling liquid. All components of the HP generator, including the transformer, can be immersed in the dielectric cooling liquid, which provides high cooling capacity while reducing clearance and creepage requirements. This allows for better utilization of the safe operating area of ​​all components, resulting in further miniaturization and lower parasitic inductance and capacitance. This leads to a smaller overall HP generator and improved efficiency.

[0028] Some, in particular all, of the LP generator and the control unit may be at least partially located in one housing, together with at least the switching unit. The couplings may be located in the same housing. The transformer and rectifier may be located in the housing. The housing may be waterproof. A dielectric cooling liquid may flow within the housing, thereby improving cooling and isolation. Distances may be reduced. This allows shorter wire lengths to be used, which reduces the inherent inductance and thus allows for faster switching functions. Temperature differences between different switches and other components and / or couplings of the LP generator may be reduced by this type of series liquid arrangement, thus allowing for improved balance.

[0029] In one embodiment, the control unit can be configured to sequentially select the LP generator contribution among multiple LP generators. In particular, each pulse sequence can start with a different LP generator, so that after n pulses, all n LP generators are equally loaded. This leads to better load distribution among the LP generator stacks and therefore better power loss balance among the switching elements.

[0030] In one embodiment, the control unit may include a switching unit having a current boost capability of at least 10 A / μs. Such a high current boost capability allows for sufficiently fast charging of capacitive loads.

[0031] In one embodiment, the control unit may include a switching unit having a voltage withstand capability of about 0.5 kV or greater at a voltage change rate of 15 kV / μs or greater, thereby enabling extreme pulses with very well-defined voltage transitions, a highly desirable feature for many applications such as plasma processing, particularly semiconductor plasma processing.

[0032] In one embodiment, the control unit can be configured to select the contribution of the LP generators (14, 16, 18) in such a way as to reduce voltage overshoot at the output of the HP generators and / or at a particular point in the load, particularly at the substrate of the plasma process, for example by having a first step in the output of the HP generators be only a fraction, particularly half, of the value of a second step which may be full.

[0033] In one embodiment, at least one, preferably some, and most preferably all, of the LP generators include a LP generator value limiting circuit, such as a voltage limiting circuit or a current limiting circuit. This can be an additional switching element with an additional resistor, or an electrically controllable variable impedance with a power dissipation element. By using such a circuit, the HP generator becomes much more reliable.

[0034] In one embodiment, the control unit is configured to select the contribution of the LP generator via a galvanically isolated, in particular, optical fiber connection or magnetic coupling. Several, preferably each, of the LP generators can be selected by the control unit through control of the switching unit. The connection between the output of the data processor and the switching unit can be realized by optical fiber or magnetic coupling. This serves to effectively switch all LP generators quickly and without delay, for example, to form pulses with sharp voltage edges. Several switching elements of one switching unit can be connected by one galvanically isolated connection. Several LP generators with corresponding switching units can be grouped together, which can be configured in such a way that the group is always activated or deactivated only together. It is then possible to use only one galvanically isolated connection for such a group. Reducing the number of galvanically isolated connections reduces costs and makes the HP generator more reliable because there are fewer parts at risk of failure. Advantageously, each switch has its own galvanically isolated connection. However, several transmitters can be controlled by one control signal if grouped together. This reduces the number of I / O ports required.

[0035] In one embodiment, the voltages on all LP generators, also called "stages," are equal even if their loads are unbalanced. Also, primary-secondary isolation (ground-to-HV) is easily achieved by locating the primary path near the center of the ring-core transformer and keeping the secondary windings near the core, away from the primary windings. A balance winding can be placed near the secondary windings, since here only inter-stage voltage isolation needs to be provided.

[0036] "The control unit is configured to select the contribution of the LP generator to the output value of the HP generator" is to be understood as the capability and configuration of the circuitry of the HP generator in combination with the programming of the control unit to enable the HP generator to select a selection of LP generators with respective LP generator values ​​to provide a contribution to the output value of the HP generator.

[0037] The control unit may include, for example, a data processor embodied as an embedded microprocessor having a program memory embodied, for example, as a non-volatile data memory, and a data memory embodied, for example, as a volatile data memory. Such a control unit typically includes data interfaces for incoming data, e.g., measurement data, control input data, and the like, as well as outgoing data, e.g., control signals, information signals, warning signals, and the like. Such a control unit typically includes data calculations, data comparison functions, and similar circuitry that allows it to calculate new data from input data, make decisions regarding the input and / or calculated data, output relevant data signals for controlling other electrical circuitry of the HP generator, etc.

[0038] The output of the coupling can be the output of the HP generator. However, it is also possible that some small additional voltage or current shaping components are connected between the output of the coupling and the output of the HP generator. These small additional voltage or current shaping components can be filters or small voltage, current or power sources with amounts much smaller than the output values ​​of the coupling.

[0039] "HP generator state" means the different states that an HP generator can assume during use depending on the operation of different LP generators and / or switching units and / or switching elements within the HP generator.

[0040] High power means 10 kW or more during pulsed operation. High voltage means 4 kV or more. High current means 10 A or more. The HP generator can be configured to affect the voltage and / or charge carrier movement within the plasma and / or between the plasma potential and the substrate during the plasma process. The energy storage component can be a capacitor or inductor and / or other energy storage component. This should be understood as an energy storage component configured to store an amount of energy that may be a reasonable portion of the output energy of one pulse of the HP generator, i.e., at least 1 / 200, preferably at least 1 / 100, and even more preferably at least 1 / 50 of the energy of one pulse of the HP generator. Continuously charging the energy storage component includes charging a capacitor to a predetermined voltage value or an inductor to a predetermined current value. The electrical connection of the coupled LP generators can be series, parallel, or a combination of both. The coupling value can be voltage, current, or power. The control unit can identify which of the LP generators contributes to the output power of the HP generator. The control unit may be configured to control the at least two LP generators such that they contribute to the output of the HP generator, i.e. such that the output values ​​of the at least two LP generators are added to form the HP output value.

[0041] The main advantage is that the energy storage component is charged independently of the state of the control unit. This means that there are no limitations on the duty cycle of the generated output values, especially the output pulses, their width, and consequently the average output power. A second advantage is that each LP generator has its own energy storage component, which protects the switches in the control unit against overvoltage or overcurrent, respectively. A third advantage is that all components are relatively cheap, being low-power components.

[0042] The control unit may include switching units, one associated with each LP generator. Each switching unit may include one or two transistors, particularly MOSFETs. MOSFETs provide high switching capabilities and can be used with currents of 50 A or more, allowing switching to voltages of 500 V or more. If MOSFETs are used, an anti-parallel diode may be provided for each MOSFET, particularly in parallel with each MOSFET. The MOSFETs may be silicon carbide (SIC) or gallium nitride (GaN)-based MOSFETs, suitable for high-speed switching voltages of 500 V or more with fast voltage rise and fall times (15 kV / μs or more), as well as high currents (50 A or more) with fast current rise and fall times (10 A / μs or more).

[0043] Each switching unit may include a half-bridge circuit including two switching elements connected in series. One transistor may be configured to connect two of the LP generators in such a way that, when closed, both values ​​of the LP generators affect the value at the output of the coupling. In particular, the output values ​​of both LP generators may be added. The other transistor may be configured to short-circuit the load when activated, i.e., when the transistor is closed, i.e., conductive.

[0044] The half-bridge circuit can be clamped by its storage component, e.g. a capacitor. This means that the storage component is connected directly in parallel to the half-bridge. This configuration protects both switches from overvoltages up to the voltage of the capacitor. The storage component can also be an inductor. This configuration then protects both switches from overcurrents up to the current in the inductor. To prevent faults related to overvoltages or overcurrents, respectively, it is sufficient to maintain individual safe voltages / currents on all LP generators. Therefore, each LP generator keeps its operating level within its own level. This results in a self-maintaining safe state.

[0045] The control unit may include a driver, which may be configured to drive a switching unit, in particular a transistor, in particular a MOSFET, and the control unit, in particular the switching unit, may be part of the respective LP generator.

[0046] At least six, preferably ten or more, preferably fifteen or more LP generators may be coupled in one coupling. At least two LP generators may provide equal LP generator values. Preferably, most, or even all, of the LP generators provide equal values. It is also possible for at least two LP generators to provide different LP generator values, and in particular all LP generators may provide different values. One LP generator may provide an LP generator value that is half the LP generator value of another LP generator.

[0047] A capacitor can be provided as an energy storage component in parallel with the switching units, especially the half bridges. This allows the output value of the coupling to be stabilized. Each LP generator can have its own capacitor charged to an appropriate voltage level. Activating one switch of the associated switching unit connects the load, e.g., a plasma process, to the capacitor. Activating the other switch of the switching unit short-circuits the load. The output of the entire HP generator can become a true dynamic voltage source during each pulse, allowing for very large output currents and the required fast voltage transitions.

[0048] An inverter including a full bridge circuit and preferably a buck converter may be connected to the primary winding, thereby enabling efficient power delivery to the LP generator.

[0049] In yet another aspect, the present invention relates to a method of supplying high power pulses of different amplitudes provided by a high power (HP) generator to a plasma process, comprising: a. continuously charging an energy storage component of each of a plurality of low power (LP) generators to a predetermined value; b. selectively combining output values ​​of at least some of the LP generators by controlling the contribution of the LP generators to the output of the HP generators to obtain desired output values ​​of the HP generators corresponding to pulses having a desired amplitude; Includes:

[0050] By using many LP generators, each containing an energy storage component, in conjunction with a coupling, it is possible to select how many LP generators contribute to generating the output pulse. This solution is relatively safe, universal, and inexpensive. It is safe because each LP generator can be configured to protect its associated switch from powers higher than the power value of its energy storage component. This solution is universal because it allows the amplitude of the output pulse to be rapidly changed with a resolution equal to the number of low-power generators. It is inexpensive because many low-power generators and low-voltage switches can be used, which is usually cheaper than one HP generator and high-power pulse unit.

[0051] In one embodiment, the LP generators, also referred to as "stages," can be controlled individually or in groups. Control signals can be provided to the drivers of the switching units, preferably by optical fiber, although other means can be used. Not only can all switches of a switching unit be controlled separately from one main control board, but one signal can control an entire stage (e.g., control signals for the connecting switches of a switching unit can be provided from the main control board, signals for the load parallel switches of a switching unit can be generated on the connecting switch driver board), one signal can control multiple switches / stages in a collective control, etc. The total output power is the sum of the power powers of only the activated / selected LP generators. The total power power can be varied from pulse to pulse by activating or selecting a different number of LP generators per pulse.

[0052] In one embodiment, the output value of the LP generators, i.e., the LP generator value, can be dynamically stabilized. Each LP generator can have its own capacitor charged to the appropriate voltage level. Activating one switch connects the load to the capacitor. Activating the other switch shorts the load. The output of the entire HP generator becomes a true dynamic generator during each pulse, allowing for very large output currents and the fast voltage transitions required.

[0053] A two-step transition can be realized instead of a one-step output value transition. Connecting a low-impedance voltage source to a capacitive load through any connector impedance inevitably generates current and voltage oscillations. The load peak voltage reaches twice the applied voltage level. Resistive damping circuits consume a large amount of power. By applying a two-step transition, the power loss can be significantly reduced. This is possible with the presented topology. The two-step transition results in a nearly rectangular voltage waveform, lower overshoot, and significantly reduced power loss.

[0054] Several stages, also called "LP generators", can be activated sequentially during a continuous output pulse. Activating an LP generator means activating the corresponding connected switching element. To compensate for the decaying wafer voltage, the output voltage can be increased in several steps. At each step, its voltage is added to the total output voltage value. If the voltages of all stages are equal, the resolution of each step is 1 / n times the voltage of the entire stack of LP generators. A separate stack can be built to handle the compensation function. This can be controlled separately, resulting in a much finer step resolution, which in turn leads to a more stable wafer voltage and a better ion energy distribution.

[0055] Other features and advantages of the present invention can be obtained from the following detailed description of embodiments of the invention based on the drawings of the figures showing the details essential to the invention, and from the patent claims. The features shown therein should not necessarily be understood to be to scale, but are shown in such a way that the particular features according to the invention are clearly visible. The various features can be implemented individually or in any combination in the various embodiments of the invention.

[0056] Examples of the invention in various stages of use are shown in the diagrams and are explained in more detail in the following description. [Brief explanation of the drawings]

[0057] [Figure 1] Pulse sequences of different amplitudes are shown. [Figure 2a] 1 shows a first embodiment of an HP generator. [Figure 2b] 2 shows a second embodiment of the HP generator. [Figure 3] 1 shows a first embodiment of a part of an HP generator for generating a positive voltage pulse. [Figure 4] 1 shows a second embodiment of a part of an HP generator for generating a positive voltage pulse. [Figure 5]1 illustrates an embodiment of an HP generator having a power supply for powering an LP generator. [Figure 6] 1 shows an embodiment of an HP generator with a balance and damping circuit. [Figure 7] Wave shaping and power loss in one-step and two-step transitions are shown. [Figure 8] 1 shows the waveforms resulting from sequential actuation of the LP generator. [Figure 9] 1 shows the results of a periodic control signal sequence through an LP generator. [Figure 10] 1 illustrates a plasma processing system having a plasma chamber. [Figure 11] 1 shows an alternative embodiment of an HP generator. [Figure 12] 1 shows an alternative embodiment of an HP generator. [Figure 13] 1 shows an alternative embodiment of an HP generator. [Figure 14] 1 shows an alternative embodiment of an HP generator. [Figure 15] 1 shows an example of an LP generator value limiting circuit. [Figure 16] 1 shows an embodiment of an HP generator with a balancing circuit. [Figure 17] 1 shows an embodiment of an HP generator with liquid cooling. [Figure 18a] 1 illustrates an embodiment of an HP generator with a galvanically isolated driver. [Figure 18b] 1 illustrates an embodiment of an HP generator with a galvanically isolated driver. DETAILED DESCRIPTION OF THE INVENTION

[0058] Figure 1 shows the sequence of pulses 1 required by the plasma application. It can be seen that the amplitude of pulse 1 must be constant for several pulses, but can have an amplitude variation from pulse 1 to pulse 1a.

[0059] FIG. 2a shows a first embodiment of a high-power (HP) generator 10 suitable for generating high-power pulses. The HP generator has a positive output 32 and a negative output 12. The HP generator 10 includes a plurality of low-power (LP) generators 14, 16, 18, each of which includes an energy storage component C1, C2, Cn, implemented in this case as a capacitor. During use, the energy storage component C1 is continuously charged to a predetermined value associated with the energy storage component C1 to maintain constant the energy stored therein. During use, each LP generator 14, 16, 18 provides at its output an LP generator value corresponding to the value of the energy storage component C1 incorporated within the respective LP generator 14, 16, 18. The LP generators 14, 16, 18 are electrically connected within a coupling 20, such that at the output of the coupling 20, a coupling value corresponding to the output value of the HP generator 10 can be obtained, which is higher than the LP generator value at the output of one of the LP generators 14, 16, 18. The control unit 22 is configured to select the contributions of the LP generators 14, 16, 18 to the output value of the HP generator 10 during power delivery of the HP generator 10. For clarity, only three LP generators are shown. In practice, many more LP generators, typically six or more, even ten or more, and especially fifteen or more, would be used to produce a step-type transition in the output that may be as smooth as required for the load.

[0060] The control unit 22 includes switching units 24, 26, 28 associated with each LP generator 14, 16, 18. Each of the switching units 24, 26, 28 includes a switching element S1, S2. In the embodiment shown, the switching elements S1, S2 are connected in series, thus implementing a half-bridge. The switching units 24, 26, 28, and therefore the switching elements S1, S2, are driven by a driver 30 of the control unit 22.

[0061] The positive output 32 of the HP generator is connected to earth, also referred to as ground potential PE. All LP generators are connected to a power supply 34, which includes a transformer, a rectifier and an inverter connected to the power grid and which itself includes a full bridge and a buck converter, as will be explained in more detail below.

[0062] FIG. 2b largely corresponds to FIG. 2a. Therefore, like elements are numbered likewise. The difference between FIG. 2a and FIG. 2b is that in FIG. 2b, the energy storage components are implemented as inductances L1, L2, and Ln. Therefore, the electrical connections / wiring within the coupling 20 are slightly different. In general, the energy stored in an inductor becomes a current source. Therefore, the energy storage component is connected in parallel with other current sources, leading to current amplification.

[0063] In both Figures 2a and 2b, a ground potential, also referred to as earth potential PE, can be connected to one of the outputs of one of the LP generators 14, 16, 18. This makes it possible to generate voltage signals with positive and negative voltages relative to ground, as shown for example in Figure 10 of (Patent Document 1) or Figure 21 of (Patent Document 2). The ground potential can also be connected to the positive output 32 or the negative output 12. In Figures 2a and 2b, it is connected to the positive output 32 by way of example.

[0064] FIG. 3 shows a simplified embodiment of a portion of an HP generator 10 with multiple LP generators 14, 16, and 18. To generate high-voltage pulses, it is advantageous to construct a push-pull switch. This means that the switching unit should have at least two switching elements S1 and S2: a "push" (switching element S1), which is used to charge the plasma reactor capacitance, and a "pull" (S2), which is used to discharge the plasma reactor capacitance. To generate pulses with different amplitudes while being able to rapidly change the amplitude between pulses (as shown in FIGS. 1, 7, and 8), it is necessary to combine the outputs of two or more LP generators 14, 16, and 18. The LP generator values ​​of the LP generators 14, 16, and 18, in this case the voltage amplitudes, can be the same or different. In FIG. 3, a ground potential, also referred to as the earth potential PE, is connected to the negative output of the LP generator 18.

[0065] In some situations, if none of the switching elements S1, S2 is switched on (during a transition between two operating states) and the LP generators 14, 16, 18 are connected in series with the load (e.g., a plasma reactor), the switching elements S1, S2 may be destroyed by overvoltage. For this reason, it is advantageous to add diodes D1, D2 in parallel with all switching elements S1, S2 to protect them from voltages higher than the voltage stored in their respective energy storage components. This is especially true when the switching elements S1, S2 are implemented as MOSFETs. If the switching elements are implemented as unipolar transistors, as MOSFETs typically are, the diodes are already part of the transistor or are an integral part of the transistor die. In terms of integrated circuits, a die is a small block of semiconductor material on which a functional circuit is built. These diodes can then be used, eliminating the need to add them separately.

[0066] A ground potential can be generated at the output of the HP generator (the load is short-circuited to the ground potential PE). This state is achieved by switching on the switching element S2 when the ground potential is connected to the negative output 12 or the positive output 32 of the HP generator. In this state, the switching element S1 is opened (switched off). To generate a (voltage) pulse to the load, an appropriate number of switching elements S1 must be switched on. The LP generators 14, 16, 18 can provide the same or different LP generator values, in this case voltage amplitudes. By switching on several switching elements S1, the associated LP generators, e.g., LP generators 14, 16, are connected in series and the amplitude of the voltage pulse to the load is equal to the LP generator value, e.g., the sum of their output voltages.

[0067] The complementary switching element S2 associated with the LP generators 14,16 should be switched off to avoid a short circuit within the LP generators 14,16.

[0068] The switching element S1 associated with the LP generator 18 (or another LP generator) should be switched off, and the switching element S2 can be switched on or off (current flows through the diode D2 anyway).

[0069] The configuration of switching elements that are switched on and off can be changed quickly, which leads to a fast change in the amplitude of the pulses generated at the output of the HP generator 10. The number of LP generators 14, 16, 18 supplying the load can be quickly changed to any feasible number (0 to n).

[0070] Figure 4 differs from Figure 3 only in the wiring, i.e., the interconnection of the LP generators 14, 16, 18 and the connection point between the load and PE. However, the same result as in Figure 3 can be achieved, i.e., voltage pulses of different amplitudes can be realized by selecting the LP generators 14, 16, 18 that contribute to the output voltage pulse by appropriately driving the switching elements S1, S2. In Figure 4, ground potential, also referred to as earth potential PE, is connected to the negative output of the HP generator 10.

[0071] Figure 5 shows the power supply of the LP generators 14, 16, and 18 in more detail. The energy storage components C1, C2, and Cn of the LP generators 14, 16, and 18 are continuously charged by the transformers T1, T2, and Tn and their associated rectifiers X1, X2, and Xn, respectively. It is much easier and cheaper if all the transformers T1, T2, and Tn have their own magnetic cores, and the only common element is the primary windings P1 and P2, which can be fabricated from a single common wire. To ensure the same voltage regardless of the load, a balance winding BW is added. The balance winding BW equalizes the magnetic flux in each transformer T1, T2, and Tn. If the number of wires in the secondary windings SW1, SW2, and SWn is the same, the voltage on the energy storage component C1 will be the same. The charging voltage of the energy storage component C1 can be varied by changing the number of turns in the secondary windings SW1, SW2, and SWn. In that way it can be ensured that the individual energy storage components C1 are charged to different voltages.

[0072] The balance windings BW in the transformers T1, T2, Tn work in this way: if the magnetic flux in adjacent transformers T1, T2, Tn is the same, both windings BW have the same voltage, and therefore no current flows between them. If for some reason the magnetic flux in one core is different (i.e., higher) than the next core, the induced voltages in the different transformers T1, T2, Tn will be different, and therefore some current will start flowing between their windings BW. This current will cause the transformer T1, T2, Tn with the higher magnetic flux to be more loaded, and the magnetic flux in the next transformer will increase due to this current. By equalizing the magnetic flux in the magnetic cores, the induced voltages will be equal. The balance winding BW should have the same number of turns in both connected transformers using the flux equalization method.

[0073] The primary windings P1, P2, Pn are connected to an inverter 40, which is connected to a power grid 42. The inverter 40 is part of the power supply 34 and includes a full bridge 44 and a buck converter 46 upstream of the full bridge 44, which is connected to a rectifier 48.

[0074] FIG. 6 shows an HP generator 10 similar to that shown in FIG. 2a, in which a balancing circuit—specifically, a diode D or a diode-like component—that allows current to flow in only one direction is connected between the two LP generators 14, 16, and 18. The switching units 24, 26, and 28 include half-bridge switching elements. These switching elements are shown as transistors, more precisely, bipolar transistors. For faster switching times, a more preferred transistor type would be a MOSFET, specifically a SiC or GaN-based MOSFET. In this embodiment, the negative terminal of each LP generator 14, 16, and 18, also referred to as a stage, is connected to the same potential as the diode D or the preceding LP generator 14, 16, and 18 with its diode-containing circuit. This allows the energy stored in the lower-stage energy storage component to be transferred to the higher-stage energy storage component when the switching elements are activated if the voltage of the lower-stage energy storage component exceeds that of the higher-stage energy storage component. The charge in the highest stage 14 accumulates excess charge from the entire stack. The highest stage 14 is therefore controlled to provide the most power to the load in order to eliminate excess charge. The use of a diode D or a circuit including a diode results in better voltage distribution along the LP generator stack. A damping circuit 50, particularly in series with the balancing circuit, here diode D, can be used to eliminate oscillations on parasitic components in the charge handling path. The damping circuit may particularly include an inductor L and / or a resistor R connected in parallel as shown in FIG. 6.

[0075] Connecting a low-impedance voltage source, such as a capacitive voltage source, with a capacitive load due to any connector inductance inevitably generates current and voltage oscillations. The load peak voltage can then reach twice the applied voltage level. This can damage the load and is highly undesirable. Resistive snubber circuits are often used to attenuate the peak voltage. These lossy circuits consume a large amount of power and therefore generate a large amount of heat, which is also highly undesirable. By applying a two-step transition, this overshoot can be controlled, reduced, or even avoided. The energy dissipated in the lossy circuits can be dramatically reduced or even avoided. Energy-consuming components can then be made much smaller or even completely avoided. Power losses can be significantly reduced. This is possible with the proposed topology, as shown in Figure 7. Waveform 70 shows a one-step transition from 0 kV to 10 kV at the output of coupling 20, triggering all 15 stages in a single instant. This results in a voltage overshoot, as can be seen in waveform 74. As shown by waveform 71, a gradual transition, e.g., from 0 V to 5.5 kV in a first step by activating only eight of the 15 stages, and then from 5.5 kV to 10 kV in a second step by activating the remaining 15 stages after, e.g., several tens or hundreds of nanoseconds, yields much better results. The resulting waveform 73 has a much lower overshoot peak voltage, and the voltage rise is slower, but still fast enough for the process. As can be seen from waveform 73, the two-step transition results in a nearly rectangular output waveform with less overshoot and therefore little power dissipation, whereas the one-step transition leads to waveform 74, which exhibits voltage overshoot and, therefore, significant power loss 75. The same overshoot peak and subsequent decay can be seen in the descending slopes, e.g., after 1 μs and 3.5 μs.

[0076] 8 shows the stepwise increase in amplitude of pulses 80 by sequentially activating LP generators 14, 16, 18 to contribute to the HP output signal. Waveform 81 shows the voltage at the output of the HP generators, and waveform 82 shows the voltage on the wafer in the plasma chamber.

[0077] Figure 9 shows the results of cycling a control signal sequence through an LP generator stack containing 15 LP generators #01 through #015. This diagram, like Figure 8, shows a timeline t on the horizontal axis. The vertical axis shows the activation of 15 switching elements corresponding to 15 LP generators #01 through #15. The shaded area 92 is where the connected switching elements are activated. The open area 91 is where the switching elements in parallel with the load are activated. Therefore, there are no pulses at the output during time frames without shaded areas. In the first column, LP generators #01 through #06 are switched along with their corresponding connected switching elements. In the second column, LP generators #01 through #10 are switched along with their corresponding connected switching elements. In the third column, LP generators #01 through #11 are switched along with their corresponding connected switching elements. In the fourth column, LP generators #01 through #12 are switched along with their corresponding connected switching elements, and so on. In this way, the pulse has the shape of a stepped waveform. In the ninth column, the pulse ends and all connected switching elements are deactivated. Then, in the tenth column, the next pulse begins, this time using LP generators #02 to #07 instead of LP generators #01 to #06. In this example, all LP generators have the same output value, but the output value at the output of coupling 20 is the same as it was for the first pulse. The advantage is that each pulse sequence starts on a different LP generator stack, so that all 15 LP generators and their corresponding switching elements are equally loaded after 15 pulses. This allows for better load distribution between the LP generator stacks and therefore a better balance of power losses between the switching elements.

[0078] FIG. 10 shows a plasma processing system having a plasma chamber 100 in which a plasma 101 is generated within a plasma space. Such or similar systems are shown and described, for example, in U.S. Pat. No. 6,277,499, U.S. Pat. No. 6,277,499, or U.S. Pat. No. 6,277,499. An upper electrode 103 may be positioned within the plasma chamber. Gas inlets and outlets, particularly gas supply pipes 104, may be installed from the outside to the inside of the plasma chamber 100 and connected to the electrode 103. A substrate 102, particularly a semiconductor wafer, may be placed within the plasma chamber 100 on a support 105 including a substrate holder. During use, the substrate 102 may be treated with the plasma 101, for example, in processes such as etching, ashing, or deposition, particularly by atomic layer deposition. Etching processes can be very difficult when the ratio of the diameter of the etching hole to the length of the hole is very low, e.g., <1 / 100, as is often necessary for deep etching. A conductive electrode 106 may be installed in the plasma chamber 100, particularly near the substrate 102, for example, around the periphery of the substrate 102. The conductive electrode 106 may be an edge ring, which may also be called a focus ring. The conductive electrode 106 may be connected to a first power supply 114 via a first connecting line 115. The first power supply 114 may be a DC pulsed power supply, in which case the pulses may have different lengths, amplitudes, and waveforms, as shown, for example, in FIGS. 11 and 14 of U.S. Patent No. 5,627,497 or in FIG. 2 of U.S. Patent No. 5,627,497. By controlling the first power supply 114, the conductive electrode 106 may additionally or alternatively be used as an ion energy and / or ion acceleration direction control means, as also described in U.S. Patent No. 5,627,497 or U.S. Patent No. 5,627,497. A first radio frequency (RF) power supply 118 may be electrically connected to the support 105 via a first power supply rod 119, a first matching unit 116, and a first connecting unit 117. A second radio frequency (RF) power source 108 may be electrically connected to the upper electrode 103 via a second power supply rod 109 and a second matching unit 110 and a second connecting unit 111. The electrode 107 may be positioned in or near the support 105 and is electrically connected to a second power source 112 via a second connecting line 113.The second power supply 112 may be a DC pulsed power supply, where the pulses may have different lengths, amplitudes, and waveforms, as shown, for example, in Figures 11 and 14 of U.S. Patent No. 5,629,663 or Figure 2 of U.S. Patent No. 5,629,663. The substrate 102 may be secured to the support 105 via an electrode 107, which may function as an electrostatic chuck. Through control of the second power supply 112, the electrode 107 may additionally or alternatively be used as a means for controlling ion energy and / or ion acceleration direction, as also described in U.S. Patent No. 5,629,663 or U.S. Patent No. 5,629,663.

[0079] Some plasma processing applications, such as etching and film deposition, require high-voltage (HV), high-frequency (HF) rectangular asymmetric pulse voltage supplies. In many cases, the voltage values ​​significantly exceed the voltage handling capabilities of individual semiconductor switches, especially when high-frequency operation is required.

[0080] Some plasma applications require not only pulsed operation but also pulse-to-pulse amplitude variation. Some plasma applications require the power supply to deliver high peak currents to obtain short voltage transition times. Most plasma applications present a load, which includes capacitive components. Significant power losses are associated with the charging and discharging of the capacitance of this load with each pulse. Some plasma applications require pulse shaping, as shown, for example, in Figures 11 and 14 of U.S. Pat. No. 5,629,499 or Figure 2 of U.S. Pat. No. 5,629,499.

[0081] Therefore, a series connection of such switches is one possible solution. Series connections require voltage balancing means, which are not easily realized in HF operation.

[0082] Figure 11 shows an alternative embodiment of the HP generator stack shown in Figure 5. The difference between the HP generators shown in Figures 5 and 11 is that in Figure 11 the primary windings P1, P2, ... Pn are connected in parallel to the transformers T1, T2, ... Tn and no balance winding BW is provided.

[0083] Figure 12 shows another alternative embodiment of the HP generator shown in Figure 5. The difference between the HP generators shown in Figures 5 and 12 is that in Figure 12 all transformers T1, T2, Tn of Figure 5 are integrated into one main transformer T1 with only one core. Only one primary winding P is required and no balance winding Bw is provided.

[0084] Figure 13 shows another alternative embodiment of the HP generator shown in Figure 5. The difference between the HP generators shown in Figures 5 and 13 is that in Figure 13 the primary windings P1, P2, ... Pn are connected in parallel with the transformers T1, T2, ... Tn. Balance windings are shown, but are not absolutely necessary in such a configuration.

[0085] Figure 14 shows an alternative embodiment of the HP generator shown in Figure 5. The difference between the HP generators shown in Figures 5 and 14 is that in Figure 14, the primary winding P1 is connected only to the transformer T1. The balance winding BW is used to transport energy from the transformer T1 to T2 and from the transformer T2 to the subsequent transformer.

[0086] FIG. 15 shows an example of an LP generator value limiting circuit 151. This LP generator value limiting circuit 151 is a voltage limiting circuit. It can be connected in parallel at its terminals 152a, 152b to one, some, or all of the LP generators 14, 16, 18. It can also be connected in parallel at its terminals 152a, 152b to one, some, or all of the switching units 24, 26, 28. This LP generator value limiting circuit 151 includes a series circuit of a diode D15 and a capacitor C15, and clamps any overvoltage present at its terminals 152, 153 to the voltage to which capacitor C15 is charged. The voltage of capacitor C15 is controlled by a discharge circuit 153. The discharge circuit 153 includes a transistor T15, in this case a MOSFET, and a resistor R15, in this case a power resistor, configured for highly efficient cooling. Transistor T15 can be switched on or off and is therefore controlled in pulse mode. Therefore, transistor T15 does not dissipate much energy into heat and remains very cool. When transistor T15 is switched on, the capacitor is discharged and a discharge current flows through resistor R15, dissipating the energy into heat. Most of the heat is generated in resistor R15, which is easier and less expensive to keep cool than transistor T15. Transistor T15 is controlled by a voltage control circuit 154 via its control input G15. Voltage control circuit 154 includes a series connection of a first high-voltage Zener diode 155, a current-limiting resistor 156, and a second low-voltage Zener diode 158. The junction of current-limiting resistor 156 and second low-voltage Zener diode 158 is connected to the control input G15 of transistor T15. Voltage control circuit 154 may further include a driver 157. Driver 157 may have its input connected to the junction between current-limiting resistor 156 and second low-voltage Zener diode 158. The driver 157 may have its output connected to the control input G15 of the transistor T15. A voltage divider 159 may be connected between the output of the driver 157 and the control input G15 of the transistor T15.

[0087] The driver has hysteresis at its input and can therefore be implemented as a Schmitt trigger. It generates a pulse signal to drive the discharge transistor T15 at a frequency of approximately 2-20 kHz. In this configuration, more than 90% of the power is dissipated in resistor R15. This keeps the transistor cool enough to operate reliably over long periods of time.

[0088] FIG. 16 shows an embodiment of an HP generator 10 in which a balancing circuit including components that allow current to flow in only one direction, specifically diodes or components that behave like diodes, is connected between the two LP generators 14, 16, and 18. The balancing circuit, specifically diode D, is connected between the two negative outputs of the LP generators 14, 16, and 18. This activates switching element S1, allowing energy to be transferred from the lower-stage energy storage components to the higher-stage energy storage components when the voltage of the lower-stage energy storage components exceeds that of the higher-stage energy storage components. The charge in the highest stage 14 accumulates excess charge from the entire stack. Therefore, the highest stage 14 should be controlled to provide the most power to the load to eliminate excess charge. The use of diode D or a circuit including a diode improves voltage distribution along the LP generator stack.

[0089] 17 shows an embodiment of an HP generator 10 with liquid cooling capabilities. All electronic components of the HP generator 10, such as the LP generators 14, 16, and 18, switching units 24, 26, and 28, transformers T1, T2, and Tn, and inverter 40, are located within a waterproof housing 171. A liquid reservoir 174 is located near the housing. A liquid pump 173 is located between the housing and reservoir 174 to circulate the liquid 171 between the housing and reservoir 174 as a closed liquid loop. The reservoir is in thermal contact with a heat exchanger 175 to transfer heat from the closed cooling liquid loop to the environment.

[0090] 18a and 18b show an embodiment of the HP generator 10 having a galvanically isolated connection 181 between the driver 30 and the switching elements S1, S2.

[0091] Therefore, the control unit 22 is configured here to select the contributions of the LP generators 14, 16, 18 so that they are galvanically isolated, in particular by optical fiber connection or magnetic coupling. The connection between the output of the data processor and the switching units 24, 26, 28 can be realized by optical fiber or by magnetic coupling. This serves to switch all LP generators 14, 16, 18 efficiently, quickly, and without delay, for example to form pulses with sharp edges in the voltage. Several switching elements S1, S2 of one switching unit 24, 26, 28 can be connected by one galvanically isolated connection. Several LP generators 14, 16, 18, together with the corresponding switching units 24, 26, 28, can be grouped together, which can be configured in such a way that the group is always activated or deactivated together. Then, for such a group, only one galvanically isolated connection 181 can be used. Galvanic isolation (transmitter and receiver) can be used for each switch. Groups of transmitters can be controlled simultaneously, reducing the number of control signals required. Reducing the number of galvanically isolated connections 181 reduces costs and makes the HP generator 10 more reliable because there are fewer parts at risk of failure. [Explanation of symbols]

[0092] 1 pulse 10 High Power (HP) Generator 12 HP generator negative output 14, 16, 18 Low Power (LP) Generators 20 Coupling 22 Control Unit 24, 26, 28 Switching Units 30 Drivers 32 HP generator positive output 34 Power supply 40 inverter 42 Power grid 44 Full Bridge 46 Buck Converter 48 Rectifier 50 Damping circuit 70 waveforms 71 Waveform 73 Waveform 74 Waveform 75 Power loss 80 pulses 81 Waveform 82 Waveform 91 areas 92 areas 100 Plasma Chamber 101 Plasma 102 Circuit Board 103 Electrode 104 Gas supply pipe 105 Support 106 Conductive electrode 107 Electrode 108 Power supply 109 Second Power Supply Rod 110 Second Matching Unit 111 Second connection unit 112 Second Power Source 113 Second connecting line 114 First Power Source 115 First connecting line 116 First Matching Unit 117 First Connection Unit 118 Power supply 119 First Power Supply Rod 151 LP generator value limiting circuit 152 edge 152a end 152b end 153 Discharge circuit 154 Voltage control circuit 155 First high voltage Zener diode 156 Current limiting resistor 157 Drivers 158 Second low voltage Zener diode 159 Voltage Divider 171 Waterproof Housing 173 Liquid Pump 174 reservoir 175 Heat exchanger 181 connections BW Balance winding C1, C2, Cn capacitors D1, D2 diodes L1, L2, Ln inductors P1, P2, Pn primary windings PE Earth potential R resistor S1, S2 switching elements SW1, SW2, SWn Secondary winding T1, T2, Tn transformers X1, X2, Xn rectifier

Claims

1. A high power (HP) generator (10) configured to deliver pulsed high power at high voltage and / or current values ​​to a capacitive load, in particular a plasma process, comprising: several low power (LP) generators (14, 16, 18), each LP generator (14, 16, 18) includes an energy storage component (C1, L1), and in use, said energy storage component (C1, L1) is charged to a predetermined value for said energy storage component; Each LP generator (14, 16, 18), when in use, provides at its output an LP generator value corresponding to the value of the energy storage components (C1, C2, Cn, L1, L2, Ln) incorporated in the respective LP generator (14, 16, 18). Several LP generators (14, 16, 18); a coupling (20) to which the LP generators (14, 16, 18) are electrically connected in such a way that a coupling value at the output of the coupling (20) can be obtained that corresponds to an output value of the HP generator (10) and that is higher than the LP generator value at the output of one of the LP generators (14, 16, 18) in at least some states of the HP generator (10) during use; a control unit (22) configured to select the contribution of LP generators (14, 16, 18) to the output value of the HP generator (10) during power delivery of the HP generator (10) in order to produce a rise and / or decay of pulses at the output of the coupling (20), and to control the at least two LP generators (14, 16, 18) in use so that they contribute to the output of the HP generator (10) and the output values ​​of the at least two LP generators (14, 16, 18) are added together to form an HP output value; Including, Said control unit (22) furthermore determines the contribution of said LP generators (14, 16, 18) according to the following characteristics: the output of the coupling (20) and / or the output of the HP generator (10) is a stepped waveform, in particular at the rising and / or falling edges of the pulses and / or during the pulses; the LP generators (14, 16, 18) are activated sequentially during one pulse; at least one amplitude step is less than 1 kV, in particular less than 500 V; - the LP generators (14, 16, 18) are connected by switching only; configured to select in such a way that one or a combination of High Power (HP) Generator (10).

2. A high power (HP) generator (10) configured to deliver pulsed high power having a high voltage value and / or a high current value to a capacitive load, in particular a plasma process, comprising: several low power (LP) generators (14, 16, 18), each LP generator (14, 16, 18) includes an energy storage component (C1, L1), and in use, said energy storage component (C1, L1) is charged to a predetermined value for said energy storage component; Each LP generator (14, 16, 18), when in use, provides at its output an LP generator value corresponding to the value of the energy storage components (C1, C2, Cn, L1, L2, Ln) incorporated in the respective LP generator (14, 16, 18). Several LP generators (14, 16, 18); a coupling (20) to which the LP generators (14, 16, 18) are electrically connected in such a way that a coupling value at the output of the coupling (20) can be obtained that corresponds to an output value of the HP generator (10) and that is higher than the LP generator value at the output of one of the LP generators (14, 16, 18) in at least some states of the HP generator (10) during use; a control unit (22) configured to select the contribution of LP generators (14, 16, 18) to the output value of the HP generator (10) during power delivery of the HP generator (10) in order to produce a rise and / or decay of pulses at the output of the coupling (20), and to control the at least two LP generators (14, 16, 18) in use so that they contribute to the output of the HP generator (10) and the output values ​​of the at least two LP generators (14, 16, 18) are added together to form an HP output value; Including, - said coupling (20) comprises five or more electrically connected LP generators (14, 16, 18), in particular at least six, in particular ten or more, preferably fifteen or more LP generators (14, 16, 18) being combined in one coupling (20); and / or the number of LP generators (14, 16, 18) at the output of the coupling (20), pulses with voltage rise and / or fall equal to or higher than the sum of the values ​​of several of the LP generators (14, 16, 18); and A step line pulse waveform whose step value corresponds to a value equal to or higher than the value of one or more of said LP generators (14, 16, 18). There are enough of them to form High Power (HP) Generator (10).

3. the charging energy of the LP generators (14, 16, 18) is supplied on transformers (T1, T2, ... Tn) having primary windings (P1, P2, ... Pn) and secondary windings (SW1, SW2, ... SWn) for each LP generator (14, 16, 18), the secondary windings (SW1, SW2, ... SWn) being connected to rectifiers (X1, X2, ... Xn), each rectifier (X1, X2, ... Xn) being connected to the energy storage components (C1, C2, Cn, L1, L2, Ln) of the corresponding LP generator (14, 16, 18); 3. The HP generator according to claim 1 or 2.

4. the charging energy of said LP generators (14, 16, 18) is provided on transformers (T1, T2, ... Tn) having a primary winding (P1, P2, ... Pn) and a secondary winding (SW1, SW2, ... SWn) for each LP generator (14, 16, 18), some of said primary windings (P1, P2, ... Pn), in particular each primary winding corresponding to an LP generator of the transformer, being connected in series; 3. The HP generator according to claim 1 or 2.

5. 3. HP generator according to claim 1 or 2, wherein the charging energy of the LP generators (14, 16, 18) is supplied over transformers (T1, T2, ... Tn), each transformer corresponding to several, in particular one, LP generators, may comprise a balance winding (BW), preferably two balance windings, and preferably one balance winding (BW) of one transformer (T1) may be connected to a balance winding of a different transformer (T2).

6. 3. A HP generator according to claim 1 or 2, wherein a balancing circuit including a component that allows current to flow in only one direction, in particular a diode D or a component that behaves like a diode, is connected between the two LP generators.

7. 3. The HP generator according to claim 1 or 2, wherein a damping circuit (50) is positioned in an open chain configuration between some, in particular all, of the LP generators (14, 16, 18), in particular the damping circuit (50) comprising a resistor (R) and / or an inductor (L).

8. 3. The HP generator according to claim 1 or 2, which is at least partially directly liquid cooled, in particular by an immersion dielectric cooling liquid, in particular the LP generator (14, 16, 18) being immersed in the dielectric cooling liquid.

9. 3. The HP generator according to claim 1 or 2, wherein the control unit (22) is configured to sequentially select the contributions of the LP generators (14, 16, 18) through the LP generators (14, 16, 18), in particular each pulse sequence can start with a different LP generator (14, 16, 18).

10. The control unit (22) has the following features: a. A current boost capability of at least 10 A / μs; b. Ability to withstand voltages of approximately 0.5 kV or more with a voltage change rate of 15 kV / μs or more 3. The HP generator according to claim 1 or 2, comprising a switching unit (24, 26, 28) having one or a combination of:

11. 3. The HP generator according to claim 1 or 2, wherein the control unit (22) is configured to select the contribution of the LP generator (14, 16, 18) in such a way as to reduce voltage overshoots at the output of the HP generator (10) and / or at specific locations on the load, in particular at a substrate in a plasma process.

12. 3. The HP generator according to claim 1 or 2, wherein at least one, preferably several, most preferably all, of the LP generators (14, 16, 18) comprises a LP generator value limiting circuit (151), e.g. a voltage limiting circuit or a current limiting circuit.

13. 3. The HP generator according to claim 1 or 2, wherein the control unit (22) is configured to select the contribution of the LP generators (14, 16, 18) so that they are galvanically isolated, in particular via an optical fiber connection or a magnetic coupling.

14. 4. The HP generator of claim 3, wherein an inverter (40) including a full bridge circuit (44) and a buck converter (46) is connected to the primary windings (P1, P2, . . . Pn).

15. 1. A method for supplying a plasma process with high power pulses of different amplitudes provided by a high power (HP) generator (10), comprising: a. continuously charging the energy storage components (C1, L1) of a plurality of low power generators (14, 16, 18) to a predetermined value, respectively; b. By controlling the LP generators (14, 16, 18), c. The following characteristics: d) the output of the coupling (20) and / or the output of the HP generator (10) is a stepped waveform, especially at the rising and / or falling edges of the pulses and / or during the pulses; e. The LP generators (14, 16, 18) are operated sequentially during one pulse; f. At least one amplitude step is less than 1 kV, in particular less than 500 V; g. The LP generators (14, 16, 18) are connected by switching only; selectively combining output values ​​of at least some of the LP generators (14, 16, 18) to obtain a desired output value of the HP generator (10) corresponding to a pulse having a desired amplitude, and controlling the LP generators (14, 16, 18) such that, in use, at least two LP generators (14, 16, 18) contribute to the output of the HP generator (10), and the output values ​​of the at least two LP generators (14, 16, 18) are added to form an HP output value; A method comprising:

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