WO2016050685A1

WO2016050685A1 - Method for operating an mf power generator, and an mf power generator

Info

Publication number: WO2016050685A1
Application number: PCT/EP2015/072239
Authority: WO
Inventors: Peter Wiedemuth
Original assignee: TRUMPF Hüttinger GmbH + Co. KG
Priority date: 2014-10-02
Filing date: 2015-09-28
Publication date: 2016-04-07
Also published as: DE102014220094A1

Abstract

A method for operating an MF power generator (1, 100) in which an output signal (102, 105, 107, 111, 114, 116) is controlled in closed-loop or open-loop mode is characterized in that the output signal (102, 105, 107, 111, 114, 116) is controlled in closed-loop or open-loop mode according to a predefined target value curve (101, 104, 106, 110, 113, 115), the target value curve influencing the output signal in its progression within one, in particular within a plurality of, particularly preferably within each half-wave.

Description

Method for operating an MF power generator and

MF power generator

The invention relates to a method for operating a MF power generator in which an output signal is regulated or controlled. Furthermore, the invention relates to a MF power generator with a DC source that feeds a DC link capacitor.

"DC" is a common abbreviation for "Direct Current" and is used for DC and / or DC. A DC source, in the sense of the present invention, can be a DC voltage source or a DC source. "MF" is a common abbreviation for "medium frequency". For the purposes of the present invention, "MF" is understood as meaning a frequency in the range between 1 kHz and 100 kHz, in particular in the range between 10 kHz and 70 kHz Act output power. Previously known power generators for plasma processes have a control dynamics for the output signal in the range of a few 100 ps down to the ms range. Due to this relatively sluggish control dynamics instabilities can occur, which lead to reduced deposition rate or interruptions in the plasma process. A control or regulation of the output signal to produce optimal process results is not possible with known MF power generators.

The object of the present invention is therefore to further develop a method for operating an MF power generator and to provide an MF power generator with which the waveform of the output signal can be controlled and / or controlled to achieve optimum process results.

This object is achieved according to the invention by a method for operating a MF power generator, in which an output signal, such. Output voltage, output current and / or output power is controlled or controlled, wherein the output signal is controlled or controlled in each case to a predetermined setpoint curve.

For the output signal thus not only a single setpoint is specified, but a setpoint curve. This means that the setpoint changes. In particular, it can be provided according to the invention that the desired value for the output signal changes within a half, in particular within, more preferably within each period of the output signal. In particular, a desired value curve can influence the output signal in its course within one, in particular within, more preferably within each half-wave. Previously, only a setpoint for a mean, a peak or an effective value was specified. Thus, the output signal within a half-wave was not consciously influenced. According to the invention By specifying a setpoint curve almost any waveforms are actively generated, ie they are no longer exclusively dependent on the source impedance of the generator, eg MF sine or bipolar pulse and the load, eg plasma impedance. It is thus not controlled or controlled to a constant setpoint. By controlling the output signal according to predetermined setpoint curves, it is possible to achieve optimal process results. In particular, the setpoint curve may change within a period of the MF frequency of the output signal and in particular affect the output signal within that period of the MF frequency. Thus, optimal control of the output waveform for single and dual magnetron plasma processes to achieve high Abscheidraten is possible. Furthermore, a free parametrizability of frequency, pulse shape, symmetry and amplitude for high flexibility in the application for different processes is possible. The many times higher control dynamics compared to known MF power generators enables better process stability. Ares in the plasma process can be very flexible depending on the specific requirements. Thus, a very low or programmable Arcenergie be set. The freely controllable waveform of the output signal allows both a pulse soft start and high-current pulse superpositions. Thus, the method of operating a MF power generator is suitable for use in plasma processes.

The regulation or control can be done with a control or control signal having a higher frequency than the output signal. Here by a control or regulation of the amplitude of the output signal with high dynamics is possible.

In particular, the control or control signal may have a frequency greater than 0.5 MHz, in particular greater than 1 MHz. That's the rule or control signal has a higher frequency than the output signal, it is possible, regardless of the frequency of the output signal set a low pulse or Umpolfrequenz for the unipolar or bipolar plasma excitation.

In order to achieve the advantages according to the invention, the amplitude of the output signal can be regulated or controlled. Amplitude here means the waveform shape changing over time within a period. It does not mean a value averaged over one or more periods, nor an RMS value, nor a value approximated over several vertices.

The high dynamics of the control or regulation can be achieved by modulating the output signal within a half-wave of the output signal.

The output signal can be generated by two switching stages, wherein the switching stages are operated at different frequencies. In this case, a load side arranged switching stage can be operated with the output of an upstream switching stage as an input, wherein the control or control signal of the upstream switching stage has a higher frequency than the control or control signal of the load closer switching stage.

The scope of the invention also includes an MF power generator with a DC source, in particular a DC voltage source, which feeds a DC circuit capacitor and at least one switching stage, which is driven by a signal having a higher frequency than the output signal of the power generator. The DC source can generate a constant or variable output voltage as well as a grid potential. have tentialtrennung. The switching stage may be a full-bridge fed with current, which serves to change the polarity.

It may be provided a second switching stage, which is operated at a higher frequency than the first switching stage. For example, the first switching stage may be formed as a full bridge with at least one switching element in each bridge branch and the second switching stage as a buck converter. The buck converter can be operated at a higher frequency than the full bridge. In particular, the buck converter can be driven with a frequency greater than 0.5 MHz, in particular greater than 1 MHz.

The first switching stage may be arranged downstream of the second switching stage. The second switching stage can supply the first switching stage with a power that is voltage, current or power-controlled.

Furthermore, an output filter group can be provided. The output filter group is used to avoid electromagnetic interference and to adapt to the Zuleitungsinduktivität a plasma chamber.

In one embodiment of the MF power generator, only a single switching stage may be provided which is driven at a high frequency. At the output of the switching stage, a filter, in particular an inductance may be provided to produce an output signal of a desired frequency. The filter or the inductance serves to smooth the output signal, ie to filter out the higher-frequency components. The higher frequency of the reference signal can be reduced with this filter or inductance so far that it makes up less than 1% of the output signal in the output signal. Such a filter also has the advantage that the power supply behaves like a power source. In addition, the current increase in case of errors in the load, z. B. at Ares in the plasma, to be limited. This protects the power supply and the load.

There may be provided a control or regulation for generating a control or regulating signal for the first and / or second switching stage taking into account a stored in the control or regulation predetermined setpoint curve.

Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which shows details essential to the invention and from the claims. The features shown there are not necessarily to scale and presented in such a way that the features of the invention can be made clearly visible. The various features may be implemented individually for themselves or for a plurality of combinations in variants of the invention.

In the schematic drawing embodiments of the invention are illustrated and explained in more detail in the following description.

Show it :

1 shows a first embodiment of an MF power generator with two switching stages.

FIG. 2 shows a further embodiment of an MF power generator with only one switching stage; FIG.

Fig. 3a shows representations of output signals for different to 3c setpoint curves obtained with a MF power generator according to Fig. 1; Fig. 4a representations of output signals for different to 4c setpoint curves, which were obtained with an MF power generator according to the figure 2.

FIG. 1 shows an MF power generator 1, which has a DC source 2, which feeds a DC link capacitor C1. The DC source 2 can be connected to a mains voltage supply, not shown here. The DC source 2 has no direct connection to ground 9. However, it has a reference to ground 9, which results mainly from parasitic capacitances. These parasitic capacitances are indicated by the capacitor 8. Connected to the intermediate circuit voltage provided by the intermediate circuit capacitor C 1 is a switching stage 3 designed as a step-down converter in the present exemplary embodiment. The switching stage 3 comprises a switching element 4, a diode 5 and an inductor 6. The switching element 4 is controlled by a controller and / or controller 7.

The switching stage 3 is followed by a further switching stage 10, which is formed in the embodiment as a full bridge with four switching elements 11, 12, 13, 14. Each switching element 11-14 is connected in parallel with a respective diode D1-D4. Thus, each bridge branch of the full bridge 10 has a switching element 11-14. The switching elements 11-14 are also controlled by the controller and / or controller 7. The control of the switching elements 4, 11 - 14 by the control and / or control 7 is carried out such that the output signal at the point 15 to a setpoint curve, which is stored in the control and / or control 7, is regulated or controlled. In this case, the switching element 4 is driven at a higher frequency than the switching elements 11 - 14. The frequency of the output signal at position 15 preferably corresponds to the frequency of the drive signals, each representing a control signal, the switching elements 11-14.

Between the MF power generator 1 and a load, which is designed here as a plasma load and for the clarification of a plasma chamber 16 is shown schematically, an output filter group 17 is provided to avoid electromagnetic interference and the

Impedance matching.

If the control and / or control 7 is designed as a control, there is a control to a setpoint curve (closed-loop control). For this purpose, current, voltage, power can be measured as actual values at the point 15 by means of measuring sensors 18, which are connected to the control and / or control 7. If the control and / or control 7 is designed as a controller, the output signal is controlled to a setpoint curve (open-loop control).

FIG. 2 shows an alternative embodiment of an MF power generator 100. Elements corresponding to those of FIG. 1 are identified by the same reference number. In contrast to the embodiment according to FIG. 1, the embodiment according to FIG. 2 has only one switching stage 10. In particular, it has no buck converter. As a result of the regulation and / or control 7, only the switching stage O designed as a full bridge is thus activated. In this case, the one or more control signals representing control or control signals, the switching elements 11 - 14 have a higher frequency than the output signal at the point 15. This is achieved in that before the point 15, ie at the output of the MF power generator 100th .

Inductors 20, 21 are provided. The switching elements 4, 11-14 may be designed as a MOSFET. The diodes D1-D4 may be intrinsic diodes of the switching elements 11-14. The switching element 4 of the switching stage 3 may also have an intrinsic diode (not shown). Each switching element can be designed as a SiC transistor, for example as a SiC JFET or as a GaN power switch. These are particularly suitable for driving in the frequency range greater than 0.5 MHz, in particular greater than 1 MHz.

In the figure 3a, a setpoint curve 101 is shown. The corresponding output signal generated by the MF power generator 1 according to FIG. 1 at the point 15 is identified by the reference numeral 102. The output signal 102 was generated by the switching stage 3 was driven with a control or control signal having a higher frequency than the one or more driving signals of the switching elements 11-14 of the designed in this embodiment as a full bridge switching stage 10th

In the figure 3b a sinusoidal setpoint curve 104 is shown. The reference numeral 105 shows the output signal at the point 15 of the MF power generator 1, which arises when the setpoint curve 104 is controlled and / or controlled.

In the figure 3c a sawtooth setpoint curve 106 is shown. The associated output signal at the location 15 generated by the MF power generator 1 is designated 107.

FIG. 4a shows a setpoint curve 110. For this setpoint curve 110, the output signal 111 was generated with the MF power generator according to FIG. The high-frequency oscillations (the ripple) at the point 112 are obtained since the control signal has a higher frequency than the output signal 111. The high-frequency oscillation Conditions should actually be adequately damped by the inductors 20, 21. In this case, however, the inductances have not been sufficiently designed so that the high-frequency oscillations can be recognized.

FIG. 4b shows a nominal value curve 113. With the MF power generator 100 according to FIG. 2, the corresponding output signal 114 was generated at location 15.

Correspondingly, output signal 116 was generated at setpoint 15 for setpoint curve 115 of FIG. 4c with MF power generator 100 according to FIG.

In FIGS. 3a-3c and 4a to 4c, voltages are shown by way of example as output signals (102, 105, 107, 111, 114, 116). The tip at point 103 shows the ignition voltage needed to ignite the plasma. It can also be seen in the output signals (105, 107, 114) in FIGS. 3b, 3c, 4b, 4c. It can look like it is shown, but it can look different depending on the load connected.

Claims

claims

Method for operating a MF power generator (1, 100), in which an output signal (102, 105, 107, 111, 114, 116) is regulated or controlled, characterized in that the output signal (102, 105, 107, 111, 114, 116) is controlled or controlled to a predetermined desired value curve (101, 104, 106, 110, 113, 115), wherein the reference value curve (101, 104, 106, 110, 113, 115) controls the output signal (102, 105 , 107, 111, 114, 116) in its course within one, in particular within, more preferably within each half-wave.

2. The method according to any one of the preceding claims, characterized in that the control or control is carried out with a control or control signal having a higher frequency than the output signal (102, 105, 107, 111, 114, 116).

3. The method according to claim 2, characterized in that the control signal has a frequency greater than 0.5 MHz, in particular greater than 1MHz.

4. The method according to any one of the preceding claims, characterized in that the amplitude of the output signal (102, 105, 107, 111, 114, 116) is regulated or controlled.

5. The method according to any one of the preceding claims, characterized in that a modulation of the output signal (102, 105, 107, 111, 114, 116) within a half-wave of the output signal (102, 105, 107, 111, 114, 116) takes place.

6. The method according to any one of the preceding claims, characterized in that the output signal (102, 105, 107) by two switching stages (3, 10) is generated, wherein the switching stages (3, 10) are operated at different frequencies.

7. MF power generator with a DC source (2), which feeds an intermediate circuit capacitor (Cl), and at least one switching stage (3, 10), which is driven by a signal having a higher frequency than the output signal ( 102, 105, 107, 111, 114, 116) of the MF power generator (1, 100).

8. MF power generator according to claim 7, characterized in that a second switching stage (10) is provided, which is operated at a higher frequency than the first switching stage (3).

9. MF power generator according to one of the preceding claims 7 or 8, characterized in that the first switching stage (10) are formed as a full bridge with at least one switching element (11 - 14) in each bridge branch and the second switching stage (3) as a buck converter ,

10. MF power generator according to one of the preceding claims 7 to 9, characterized in that an output filter group (17) is provided.

11. MF power generator according to one of the preceding claims 7 to 10, characterized in that a control or regulation (7) for generating a control or regulating signal for the first and / or second switching stage (3, 10) taking into account a in the Control or regulation (7) stored predetermined setpoint curve (101, 104, 106, 110, 113, 115), wherein the Setpoint curve (101, 104, 106, 110, 113, 115) can influence the output signal (102, 105, 107, 111, 114, 116) in its course within one, in particular within, more preferably within each half-wave.