JP2018093680A - Pulse power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse power supply device capable of supplying a high-power pulse, smoothly raising the pulse, and increasing a duty ratio.SOLUTION: A pulse power supply device 100 comprises: a first DC power supply 10; a first pulse generation circuit 30, SW1 that generates a first pulse voltage PV1 by first switching means SW1 connected with the first DC power supply; a second DC power supply 20; and a second pulse generation circuit 30, SW2 that generates a second pulse voltage PV2 by second switching means SW2 connected with the second DC power supply. An output voltage V1 of the first DC power supply is set to be higher than an output voltage V2 of the second DC power supply so that a voltage value V1 of the first pulse voltage becomes higher than a voltage value V2 of the second pulse voltage. The first switching means and the second switching means are controlled so that the second pulse voltage is superposed with a front part or a rear part of the first pulse voltage, or so that the second pulse voltage approaches the front part or the rear part of the first pulse voltage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pulse power supply device that can be suitably used for a film forming apparatus such as sputtering.

Conventionally, sputtering has been known as a method for forming various coatings on an object. Recently, high-power impulse magnetron sputtering (HiPIMS) has been developed (see Patent Document 1).
As shown in FIG. 6, this HiPIMS has a high density by instantaneously applying a pulse wave of a high voltage (power) V with a short pulse width W compared to a conventional pulse (broken line in FIG. 6) to the cathode. It has been attracting attention as the hardness, smoothness and adhesion of the coating are improved by high-density plasma (Patent Document 1).
Moreover, since HiPIMS has a low duty ratio, the cathode does not overheat and low temperature film formation is possible.

Japanese Patent No. 5647337

By the way, HIPIMS is one application example of a pulse power supply. By applying a large amount of power instantaneously, the plasma density is increased, the sputter particle reactivity is improved, and a hard film with high density and high surface smoothness is formed. It is a technology that aims to do. The definition of HIPIMS is that the ON time, which is the pulse addition time, is extremely small and the OFF time is long, so that power can be stored and discharged instantaneously, and the OFF time is long. The target is cooled to allow repeated discharge. The peak power of HIPIMS is about 500 to 2000 W / cm2, the average power is equivalent to that of normal pulses, and the duty ratio (ON time ratio in one cycle) is about 0.5 to 5%. The plasma density at the peak of HIPIMS is improved by about three orders of magnitude compared to normal sputtering.
In other words, the HIPIMS technology is characterized by a long OFF time and an extremely short ON time, which promotes ionization, improves adhesion as a coating film, and has high density even without substrate bias or substrate heating. In addition, coverage to a complicated shape substrate, good film formation in a groove, and the like are possible.

  However, since HIPIMS takes a long OFF time, the film formation time of the coating is limited and the film formation rate is reduced, which leads to an increase in production cost. In addition, since HIPIMS momentarily applies a large voltage, an arcing phenomenon occurs and normal sputtering tends to be difficult. Here, although the discharge start voltage is referred to as an ignition voltage, the ignition voltage is considerably higher than the sputtering voltage, which is a stable discharge state, and therefore tends to cause arcing. In HIPIMS, this ignition voltage is also higher than the conventional pulse voltage, so the frequency of arcing increases.

On the other hand, if a pulse for simply increasing the duty ratio is generated, the electric power supplied to the cathode becomes too high and the cathode may be overheated, and the pulse power supply for supplying the voltage pulse becomes expensive.
Therefore, an object of the present invention is to provide a pulse power supply device that can smoothly start up a pulse and increase a duty ratio while supplying a high-power pulse.

By the way, if the start-up of high-power pulses is smoothly supplied, the above-mentioned arcing frequency can be reduced. Therefore, the inventors of the present invention can reduce arcing and improve the film formation rate by configuring one pulse of ON time with a portion that rises smoothly first and a portion with high power thereafter. I found it possible.
That is, in order to make a steep pulse smooth, the pulses before and after the high voltage pulse are made lower in voltage, and the pulses are formed in a stepped manner. As a result, the area of the bottom of the waveform in one pulse increases, and the power of one pulse increases.

  In order to solve the above-described problems, a pulse power supply device according to the present invention includes a first DC power source and a first switching unit connected to the first DC power source. A first pulse generation circuit for generating a pulse voltage, a second DC power source, and a second switching means connected to the second DC power source generate a second pulse voltage consisting of a rectangular pulse at the frequency. And a second pulse generation circuit that generates the first pulse voltage so that a voltage value V1 of the first pulse voltage is higher than a voltage value V2 of the second pulse voltage. The output voltage V1 of the DC power supply is set higher than the output voltage V2 of the second DC power supply, and the second pulse voltage is superimposed before or after the first pulse voltage, or the first pulse voltage Before or after As the second pulse voltage are close to said first switching means and said second switching means is controlled.

According to this pulse power supply device, a high-power pulse can be supplied by the first pulse voltage that is higher than the second pulse voltage. In addition, since the second pulse voltage is supplied before or after the first pulse voltage, the ON time of the synthesized pulse voltage is lengthened and the duty ratio can be increased.
Since the second pulse voltage for increasing the duty ratio is lower in power (lower voltage) than the first pulse voltage, only the pulse width of the first pulse voltage is increased to increase the duty ratio. Compared with, the power of the pulse voltage supplied to the connection target of the pulse power supply device (for example, the cathode electrode and the ground electrode of the sputtering device of HiPIMS) becomes too high, and the cathode etc. is overheated or the pulse power supply device is expensive. Can be prevented.

The V2 is preferably 0.2 to 0.8 times the V1.
According to this pulse power supply device, it is possible to increase the duty ratio without excessively increasing the power of the pulse voltage while supplying high-power pulses.

  The pulse width W2 of the second pulse voltage may be 0.5 to 10 times the pulse width W1 of the first pulse voltage.

In the pulse power supply device of the present invention, a plurality of the second DC power supplies are provided, the second pulse voltages having different output voltages are generated by the second DC power supplies, and before the first pulse voltage. In addition, a plurality of the second pulse voltages are generated so that an output voltage sequentially increases toward the first pulse voltage, and / or a plurality of the second pulse voltages after the first pulse voltage. The first switching means and the second switching means may be controlled so that the pulse voltage is generated so that the output voltage sequentially decreases from the first pulse voltage side.
According to this pulse power supply device, the rise of the second pulse voltage before and after the first pulse voltage can be made smoother.

The first DC power supply and the second DC power supply may have the same configuration.
May be.
According to this pulse power supply device, the cost of the entire pulse power supply device can be reduced.

The first pulse voltage and the second pulse voltage are connected between the output terminals, and when the first pulse voltage and the second pulse voltage are turned off, they turn on and short-circuit between the output terminals. One switching means may be provided, and a waveform in which the first pulse voltage and the second pulse voltage are separated while the third switching means is on may be shown.
According to this pulse power supply device, the voltage between the output terminals after the output of the first pulse voltage and the second pulse voltage can be quickly reduced to 0, and a beautiful rectangular pulse can be obtained.

  According to the present invention, it is possible to smoothly start a pulse and increase the duty ratio while supplying a high-power pulse.

1 is a circuit diagram showing an overall configuration of a pulse power supply device according to an embodiment of the present invention. It is a wave form diagram which shows the waveform of the voltage pulse output from a pulse power supply device. It is a wave form diagram which shows another waveform of the voltage pulse output from a pulse power supply device. It is a wave form diagram which shows another waveform of the voltage pulse output from a pulse power supply device. It is a wave form diagram which shows another waveform of the voltage pulse output from a pulse power supply device. It is a wave form diagram which shows the waveform of the voltage pulse applied to the conventional HiPIMS.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an overall configuration of a pulse power supply device 100 according to an embodiment of the present invention, and FIG.

In FIG. 1, a pulse power supply device 100 includes a first DC power supply 10, a second DC power supply 20, a first switching means SW <b> 1 connected to the first DC power supply 10, and a second DC power supply 20. The second switching unit SW2, the third switching unit SW3, and the pulse control unit 30 that controls the on / off of the first switching unit SW1 to the third switching unit SW3.
For example, switching transistors can be used as the first switching means SW1 to the third switching means SW3. Examples of the switching transistor include field effect transistors such as MOS-FETs and bipolar transistors.

The first DC power supply 10 is a step-up switching regulator (DC-DC converter), and includes a power supply control unit 1 that controls the entire microcomputer, an input unit 3d to which AC power is input, and an input AC. A first DC voltage supply circuit 3 that converts electric power into DC power, a high-frequency transformer 7, and a second DC voltage supply circuit 9 are provided.
The first DC voltage supply circuit 3 includes a rectifier circuit 3a that rectifies AC power input from the input unit 3d and converts it to DC power, a reactor 3b that smoothes the DC voltage output from the rectifier circuit 3a, a capacitor 3c. The rectifier circuit 3a has six diodes. Two DC output lines of the first DC voltage supply circuit 3 are connected to both ends of the high-frequency transformer 7 via the bridge circuit 5.
Note that a current sensor 3e is connected to one of the DC output lines of the first DC voltage supply circuit 3 so that an overcurrent can be detected.

The bridge circuit 5 includes four switching transistors 5a to 5d, and the power supply control unit 1 controls on / off of the switching transistors 5a to 5d.
Then, by inverting the on / off timing of the switching transistors 5a and 5d and 5b and 5c, the DC output of the first DC voltage supply circuit 3 becomes a pulse voltage and is output to the high-frequency transformer 7.
This pulse current is boosted by the high frequency transformer 7 and input to the second DC voltage supply circuit 9.

The second DC voltage supply circuit 9 includes a rectifier circuit 9a that rectifies the pulse voltage input from the high-frequency transformer 7 and converts it into a DC voltage, a reactor 9b that smoothes the DC voltage output from the rectifier circuit 9a, and a capacitor 9c. The rectifier circuit 9a has four diodes. The DC output boosted by the first DC power supply 10 is output to the outside through the two output terminals 10P and 10N of the second DC voltage supply circuit 9. The output terminal 10P is on the plus side, and the output terminal 10N is on the 0V side.
Note that a current sensor 9e and a voltage dividing resistor 9f for voltage detection are connected to one of the DC output lines of the second DC voltage supply circuit 9, so that the current and voltage can be detected.

Since the second DC power supply 20 has the same configuration as the first DC power supply 10, the description thereof is omitted. The second DC power supply 20 outputs the input AC power to the outside as a boosted DC output via the output terminals 20P and 20N. The output terminal 20P is on the plus side, and the output terminal 20N is on the 0V side.
The output voltages of the first DC power supply 10 and the second DC power supply 20 are V1 and V2, respectively, and V1> V2. The output voltage of each DC power supply 10, 20 can be arbitrarily adjusted by a variable resistor (not shown) provided in the power supply control unit 1.

The output terminal 10P of the first DC power supply 10 is connected to the final output terminal P via the first switching means SW1. On the other hand, the output terminal 10N of the first DC power supply 10 is connected to the final output terminal N.
The final output terminals P and N are pulse voltage output terminals generated as described later, and are connected to the connection target of the pulse power supply device 100 (for example, the cathode electrode and the ground electrode of the sputtering device of HiPIMS), Supply pulse voltage.
Similarly, the output terminal 20P of the second DC power supply 20 is connected to the final output terminal P via the second switching means SW2. On the other hand, the output terminal 20N of the second DC power supply 20 is connected to the final output terminal N.

Then, the first switching means SW1 is turned on / off by the pulse control unit 30 (CPLD 33c), so that the DC output supplied from the first DC power supply 10 is converted into a pulse wave having the first pulse voltage as the final output terminal P. , N. Similarly, by turning on / off the second switching means SW2 by the pulse controller 30 (33c), the DC output supplied from the second DC power supply 20 is converted into a pulse wave having the second pulse voltage as a final output terminal. Output to P and N.
A capacitor 33a is connected between the output terminals 10P and 10N, and a capacitor 33d is connected between the output terminals 20P and 20N. Capacitors 33a and 33d are used to obtain a large current that is characteristic of HiPIMS by charging a current with the output voltage of DC power supplies 10 and 20 and outputting a high-voltage pulse waveform via SW1 and SW2, respectively. is there.
In addition, a current sensor 33g is connected to the output line of the final output terminal P, and current is detected in order to prevent the cathode from overheating due to overcurrent during abnormal discharge.

  A third switching means SW3 is connected between the output line on the final output terminal P side of the first switching means SW1 and the second switching means SW2 and the output line of the final output terminal N. Since the first pulse voltage and the second pulse voltage are high voltages, even if the first switching means SW1 and the second switching means SW2 are turned off, it takes a long time to discharge and the voltage drops very quickly. Hateful. For this reason, the falling edge of the pulse is not sharp and a beautiful rectangular pulse may not be obtained.

Therefore, as will be described in detail later, the final output terminals P and N are short-circuited by turning on the third switching means SW3 immediately after turning off the first switching means SW1 and the second switching means SW2. The voltage is quickly reduced to 0, and a beautiful rectangular pulse can be obtained.
Diodes 33b and 33e are connected between the first switching means SW1 and the final output terminal P and between the second switching means SW2 and the final output terminal P, respectively, and only toward the final output terminal P. A current flows. Further, a diode 33f is connected between the output line on the final output terminal P side and the second switching means SW2, so that a current flows only from the output line toward the second switching means SW2.

The first switching means SW1 and the pulse control unit 30 (33c) correspond to the “first pulse generation circuit” in the claims, and the second switching means SW2 and the pulse control unit 30 (33c) are claimed. This corresponds to the “second pulse generation circuit” in the range. In FIG. 1, the first pulse generation circuit and the second pulse generation circuit are collectively referred to as a pulse generation circuit 30.
In the present embodiment, only one third switching means SW3 is provided in the pulse power supply device 100, and both the first pulse voltage and the second pulse voltage are clean with this one third switching means SW3. The rectangular pulse is adjusted. Thereby, for example, compared with a case where switching means for short-circuiting the final output terminals P and N is provided for each of the “first pulse generation circuit” and the “second pulse generation circuit”, one common one is provided. Since it is only necessary to control on / off of the third switching means SW3, the accuracy of the timing of short-circuiting at the end of each of the first pulse voltage and the second pulse voltage is improved, and the control burden of the pulse control unit 30 (33c) is improved. Can be reduced.

FIG. 2 shows a waveform of a voltage pulse output from the pulse power supply device 100.
First, a second pulse generation circuit generates a second pulse voltage PV2 composed of a rectangular pulse having a voltage value V2 and a pulse width W2 at a predetermined frequency f (the reciprocal of the period T in FIG. 2) (FIG. 2 ( a)).
Next, simultaneously with turning off the second pulse voltage PV2, the third switching means SW3 is turned on to short-circuit the final output terminals P and N, and the second pulse voltage PV2 is quickly reduced to 0 ( FIG. 2 (a)). In FIG. 2A, the time T31 for turning on the third switching means SW3 varies depending on the pulse voltage, but is, for example, 5 to 10 μs.

Next, simultaneously with turning off the third switching means SW3, the first pulse generation circuit generates a first pulse voltage PV1 composed of a rectangular pulse having the voltage value V1 and the pulse width W1 at the frequency f (see FIG. FIG. 2 (b)).
Next, simultaneously with turning off the first pulse voltage PV1, the third switching means SW3 is turned on to short-circuit the final output terminals P and N, and the first pulse voltage PV1 is quickly reduced to 0 ( FIG. 2 (b)).

Next, at the same time as the third switching means SW3 is turned off, the second pulse voltage PV2 is generated at the frequency f by the second pulse generation circuit in the same manner as in FIG. 2A (FIG. 2C). )).
Next, simultaneously with turning off the second pulse voltage PV2, the third switching means SW3 is turned on to short-circuit the final output terminals P and N, and the second pulse voltage PV2 is quickly reduced to 0 ( FIG. 2 (c)). In FIG. 2C, the time T32 for turning on the third switching means SW3 is until the next time when the second pulse voltage PV2 in FIG. 2A is turned on, and FIG. , (B) is much longer than the ON time T31 of the third switching means SW3. Although T32 varies depending on the pulse voltage, it is, for example, 100 to 200 μs.

FIG. 2D shows a combined waveform of the second pulse voltage PV2 and the first pulse voltage PV1 generated as described above.
It can be seen that a composite waveform is generated in which the pulses are separated by the ON time of the third switching means SW3 in the order of the second pulse voltage PV2, the first pulse voltage PV1, and the second pulse voltage PV2.
As a result, a high-power pulse can be supplied by the first pulse voltage PV1, which is higher than the second pulse voltage PV2. Further, since the second pulse voltage PV2 is supplied in the vicinity of the first pulse voltage PV1 before or after (in this example, before and after), the on-time of the synthesized pulse voltage becomes longer and the duty ratio becomes higher. can do.
Since the second pulse voltage PV2 for increasing the duty ratio is lower in power (lower voltage) than the first pulse voltage PV1, only the pulse width of the first pulse voltage PV1 is increased to increase the duty ratio. Compared with the case of increasing the power, the pulse voltage power supplied to the connection target of the pulse power supply device 100 (for example, the cathode electrode and the ground electrode of the sputtering device of HiPIMS) becomes too high and the cathode and the like are overheated. It can prevent becoming expensive.

In the example of FIG. 2, since the first pulse voltage PV1 and the second pulse voltage PV2 are not superimposed, the voltage value V1 of the original first pulse voltage PV1 is set to “V1 after superposition” in the claims. Equivalent to.
From the viewpoint of increasing the duty ratio without supplying the power of the pulse voltage excessively while supplying a high-power pulse, the voltage value V2 is preferably 0.2 to 0.8 times V1. More preferably, it is 0.4 to 0.6 times.
Further, the pulse widths W1 and W2 are not particularly limited, but W2 is preferably 0.5 to 10 times W1, and more preferably 1 to 3 times.
Further, for example, W1 can be set to a duty ratio of about 1 to 5%, while W2 can be set to a duty ratio of 5 to 10% in order to improve the film formation rate. Further, the duty ratio of one pulse after superposition can be set to about 10 to 20%, for example.
Further, if the first DC power supply 10 and the second DC power supply 20 have the same configuration, the overall cost of the pulse power supply device 100 can be reduced.

As described above, when the third switching means SW3 is turned on and the final output terminals P and N are short-circuited, the fall of the first pulse voltage PV1 and the second pulse voltage PV2 becomes sharp, A beautiful rectangular pulse is obtained. In this case, the first pulse voltage PV1 and the second pulse voltage PV2 have a waveform separated by the on-time T31 of the third switching means SW3.
Here, it is possible to set the ON time T31 = 0. However, since the ON and OFF timings of SW1 and SW2 overlap, if these timings overlap and cross, the circuit components may be burdened. Therefore, it is preferable to provide the on time T31.

The above-described f (T), W1, W2, V1, V2, and T32 can be arbitrarily set by the user. f, W1, and W2 can be adjusted by, for example, a time rotary thumb rotary switch configured in the pulse controller 30 (33c).
T31 is automatically set (calculated) by the pulse controller 30 from f (T), W1, W2, and T32.
W1 and W2 are time intervals (JIS-C6802 (2005)) between the rising half-value point and the falling half-value point of the peak value of the pulse.

It goes without saying that the present invention is not limited to the above-described embodiment, but extends to various modifications and equivalents included in the spirit and scope of the present invention.
For example, as shown in FIG. 3, the second pulse voltage PV2 may be superimposed on the first pulse voltage PV1 (pulse superposition). As shown in the composite waveform of FIG. 3C, in this example, the first pulse voltage PV1 is completely overlapped with the second pulse voltage PV2, and the second pulse is applied before and after the first pulse voltage PV1. The voltage PV2 is interposed.
Note that the voltages PV1 and PV2 do not change even when pulses are superimposed.

  Further, as shown in FIG. 4, the first pulse voltage PV1 may be superimposed on a part of the second pulse voltage PV2. As shown in the composite waveform of FIG. 4C, in this example, the first pulse voltage PV1 is overlapped on the falling side of the second pulse voltage PV2, and the second pulse is input before the first pulse voltage PV1. The voltage PV2 is interposed.

Further, as shown in FIG. 5, before the first pulse voltage PV1, a plurality (multi-stage) of the second pulse voltage PV2 is applied so that the output voltage V2 sequentially increases toward the first pulse voltage PV1. In addition, after the first pulse voltage PV1, a plurality of (multistage) second pulse voltages PV2 are generated so that the output voltage V2 decreases sequentially from the first pulse voltage PV1 side, The pulse voltage PV1 may be superimposed or close. As shown in the synthesized waveform of FIG. 5C, in this example, the rise of the pulses before and after the first pulse voltage PV1 (second pulse voltage) can be made smoother.
Note that at least one second pulse voltage PV2 before and after the first pulse voltage PV1 may be plural (multistage).
In this case, it is necessary to provide a plurality of second DC power supplies and generate second pulse voltages having different output voltages from the second DC power supplies.

  In the above embodiment, the first pulse voltage PV1 and the second pulse voltage PV2 are pulse waves having the same polarity (+). However, both pulse voltages may have different polarities (+ and-), and the same. It is good also as polarity (-).

DESCRIPTION OF SYMBOLS 10 1st DC power supply 20 2nd DC power supply 30 Pulse control part SW1 1st switching means SW2 2nd switching means SW3 3rd switching means PV1 1st pulse voltage PV2 2nd pulse voltage 30, SW1 1st 1 pulse generating circuit 30, SW2 second pulse generating circuit 100 pulse power supply device

Claims (6)

A first DC power supply;
A first pulse generation circuit for generating a first pulse voltage composed of rectangular pulses at a predetermined frequency by first switching means connected to the first DC power supply;
A second DC power source;
A second pulse generating circuit for generating a second pulse voltage composed of a rectangular pulse at the frequency by a second switching means connected to the second DC power supply;
A pulse power supply device comprising:
The output voltage V1 of the first DC power supply is higher than the output voltage V2 of the second DC power supply so that the voltage value V1 of the first pulse voltage is higher than the voltage value V2 of the second pulse voltage. Set,
The first switching means and the second switching voltage so that the second pulse voltage is superimposed before or after the first pulse voltage, or the second pulse voltage is close to or before the first pulse voltage. A pulse power supply device in which the second switching means is controlled.   The pulse power supply device according to claim 1, wherein the V2 is 0.2 to 0.8 times the V1.   The pulse power supply device according to claim 1 or 2, wherein a pulse width W2 of the second pulse voltage is 0.5 to 10 times a pulse width W1 of the first pulse voltage. A plurality of the second DC power sources are provided, and the second pulse voltage having a different output voltage is generated in each second DC power source,
Prior to the first pulse voltage, a plurality of the second pulse voltages are generated such that an output voltage sequentially increases toward the first pulse voltage,
And / or after the first pulse voltage, the first switching means and the second switching voltage to generate a plurality of the second pulse voltages so that the output voltage sequentially decreases from the first pulse voltage side, and The pulse power supply device according to any one of claims 1 to 3, wherein the second switching means is controlled.   The pulse power supply device according to any one of claims 1 to 4, wherein the first DC power supply and the second DC power supply have the same configuration. The first pulse voltage and the second pulse voltage are connected between the output terminals, and when the first pulse voltage and the second pulse voltage are turned off, they turn on and short-circuit between the output terminals. 3 switching means,
6. The pulse power supply device according to claim 1, wherein the first pulse voltage and the second pulse voltage are separated while the third switching unit is on. 6.

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