JP2007043760A - Vacuum equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To limit the temperature rise, while reducing the capacity of a reverse-voltage power supply by suppressing power loss accompanying turning off of a semiconductor switch element for applying a reverse voltage to a vacuum load. <P>SOLUTION: In the vacuum equipment where an output voltage, having a polarity reverse to that of a DC power supply 1, is applied from a reverse voltage power supply 4 to a vacuum load 3, when a semiconductor switch element 5 is turned on, a diode 8 and a capacitor 7 connected in series are astride, in parallel with the semiconductor switch element 5; one end of the primary winding of a pulse transformer 10 is connected between the diode 8 and the capacitor 7, while the other end thereof is connected between the semiconductor switch element 5 and the reverse voltage power supply 4, the secondary winding of the pulse transformer 10 is connected between the output terminals of the DC power supply 1 via a diode 12; and the energy of the capacitor 7 stored, when the semiconductor switch element 5 is turned off is fed back to the DC power supply 1 via the pulse transformer 10, when the semiconductor switch element 5 is turned on. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vacuum apparatus including an abnormal discharge prevention device that prevents or suppresses the occurrence of abnormal discharge in a vacuum load, such as a sputtering apparatus, an etching apparatus, a PVD apparatus, and an electron beam vapor deposition apparatus that use plasma generated in a vacuum. .

  Vacuum loads such as a sputtering apparatus, an etching apparatus, a PVD apparatus, and an electron beam evaporation apparatus that generate plasma in a vacuum and process or process using the plasma have been used in a wide range of fields. In such a vacuum load, it is already known that an abnormal discharge occurs when the impedance between the electrodes decreases for some reason or the electrodes are short-circuited by a conductive foreign matter. Yes. When such abnormal discharge occurs, there is a problem that a substrate material such as liquid crystal during sputtering is caused particularly in a sputtering apparatus, resulting in a decrease in product yield. In an electron beam evaporation apparatus, a filament is formed by discharge energy. There are problems such as disconnection. In order to solve such a problem, various abnormal discharge prevention circuits that prevent or suppress abnormal discharge have already been proposed. For example, a circuit configuration is relatively simple, and an effective abnormal discharge prevention circuit is applied to a vacuum load. By turning on the semiconductor switch elements connected in parallel periodically or when an abnormal discharge occurs, a pulse voltage of reverse polarity is applied to the vacuum load to prevent the abnormal discharge from occurring or Techniques for quickly extinguishing have also been proposed (see, for example, Patent Documents 1 to 3).

  Thus, in the case of a circuit configuration in which the semiconductor switch element is turned on for a short time periodically or when an abnormal discharge occurs, particularly when the semiconductor switch element is turned off, the current that has been flowing through the semiconductor switch element until then is reduced. It is known that if the semiconductor switch element is suddenly interrupted, a considerably high voltage is applied to the semiconductor switch element, and the power loss of the semiconductor switch element is greatly increased, and a circuit for preventing this is already proposed (for example, (See Patent Document 4). In Patent Document 4, as shown in FIG. 5, a capacitor C is connected in parallel to a semiconductor switch element 5 that is connected in parallel to each of a DC power source 1, an inductor 2, and a vacuum load 3 and is connected in series to a reverse voltage power source 4. In addition to connecting to the diode D, a discharging resistor R is connected in parallel, and surge energy caused by wiring inductance of the circuit generated when the semiconductor switch element 5 is turned off is bypassed to the capacitor C. The voltage at both ends is prevented from rising rapidly. Then, the charge charged in the capacitor C when the semiconductor switch element 5 is turned off is discharged through the discharging resistor R when the semiconductor switch element 5 is turned on next time, and the charge charged in the capacitor C is discharged into the discharge resistor. All of it is consumed by R and becomes heat. The semiconductor switch element 5 is turned on by the control circuit 6 and applies the reverse voltage of the reverse voltage power supply 4 to the vacuum load 3.

The vacuum apparatus of FIG. 5 will be further described as a conventional example. In order to prevent abnormal discharge from occurring, the control circuit 6 periodically turns on the semiconductor switch element 5 at a repetition frequency of 10 kHz, for example, with a constant time width. When the semiconductor switch element 5 is periodically turned on, a positive pulse voltage is applied to the vacuum load 3 from the reverse voltage power source 4 through the semiconductor switch element 5, and the negatively charged electric charge on the target causing abnormal discharge is moderated. It is summed up. Generally, the voltage of the reverse voltage power supply 4 is set to a magnitude of about 20% of the output voltage of the DC power supply 1. For example, when the output voltage of the DC power supply 1 is −500 V, the output voltage Vr of the reverse voltage power supply 4. Is about 100V. Therefore, assuming that the repetition frequency f at which the semiconductor switch element 5 is driven is 10 kHz, the capacitance c of the capacitor C is 0.1 μF, and the voltage increase generated when the semiconductor switch element 5 is turned off is 100 V, the voltage V of the capacitor Becomes about 700V. That is, although the voltage applied to the semiconductor switch element 5 can be suppressed to this level at most, the loss power PL under this assumption is PL = 0.5 × c × V ² × f = 0.5 × 0.1 × 10 ⁻⁶ × 700 ² × 10 × 10 ³ to 245W. The heat generated by this power loss can be processed by air cooling with a fan or the like, but it is not preferable from the viewpoint of environmental problems, and it also causes the temperature in the vacuum device to rise, so it is desirable to suppress it to the minimum. .

  The conventional vacuum apparatus will be described in more detail. In steady operation, a plasma current Ip continuously flows from the DC power source 1 through the inductor 2 to the vacuum load 3. When the semiconductor switch element 5 is turned on, the current flowing through the inductor 2 is commutated to the path side between the reverse voltage power supply 4 and the semiconductor switch element 5, and at the same time, a reverse voltage is applied to the vacuum load 3. At this time, the current flowing through the path between the reverse voltage power supply 4 and the semiconductor switch element 5 increases by ΔI, with the current value flowing through the inductor 2 until just before being the initial value. The current ΔI is E · T / L. Here, E is the sum of the output voltage V of the DC power supply 1 and the output voltage Vr of the reverse voltage power supply 4, and T is the ON time of the semiconductor switch element 5. However, since the current ΔI can be ignored if the inductance L of the inductor 2 is sufficiently large, the current flowing through the semiconductor switch element 5 can be approximated to the plasma current Ip.

In the case of a continuous repetitive pulse, if the pulse duty of the repetitive pulse is Du, the current Ir supplied by the reverse voltage power supply 4 is Ir × Du. This current Ir becomes a current that cannot be ignored by a high duty pulse or a large-capacity vacuum apparatus, and the capacity of the reverse voltage power supply 4 increases. For example, when the DC power source 1 has an output capacity of 50 kW (−500 V, 100 A), a plasma current is generated in a state where a reverse voltage pulse having a pulse width of 20 μm is applied at a repetition frequency of 10 kHz, the reverse voltage power source The output current Ir of 4 is from Ip × Du = 100 × 0.2 to 20 A, and the output capacity Pr of the reverse voltage power supply 4 is from Vr × Ir = 100 × 20 to 2000 W, which is very large power. Therefore, the capacity of the reverse voltage power source 4 increases as the vacuum load 3 increases in capacity. Accordingly, it can be seen that the power loss generated when the semiconductor switch element 5 is turned off also increases.
Japanese Patent Laid-Open No. 07-197258 Japanese Patent Laid-Open No. 08-311647 JP 2005-151612 A JP 2004007885 A

  As described above, in the vacuum apparatus provided with the abnormal discharge occurrence prevention function disclosed in Patent Document 4, in order to prevent the occurrence of abnormal discharge or to quickly extinguish the generated abnormal discharge. The reverse voltage source 4 applies the reverse voltage to the vacuum load 3 from the reverse voltage power source 4 or when the abnormal voltage discharge occurs, or turns on the semiconductor switch element 5 from the reverse voltage power source 4 to the vacuum load 3 when the abnormal discharge is predicted. In this case, a large voltage is applied to the semiconductor switch element 5 when the semiconductor switch element 5 is turned off. In order to reduce this, surge energy generated when the semiconductor switch element 5 is turned off is applied. Is once absorbed and stored in the capacitor C, and then discharged to the discharging resistor R when the semiconductor switch element 5 is turned on. However, in this case, the energy from the reverse voltage power supply 4 once stored in the capacitor C is consumed by the discharging resistor R as described above, and all of it becomes a power loss.

  In order to solve the problems of the conventional vacuum apparatus, the present invention temporarily stores energy from a reverse voltage power supply in a capacitor when the semiconductor switch element is turned off, and then turns on the reverse voltage power supply and the direct current when the semiconductor switch element is turned on. The main problem is to control the power loss, limit the temperature rise and reduce the capacity of the reverse voltage power supply by feeding back the energy stored in the capacitor to both or one of the power supplies. It is said.

  In order to solve the problems as described above, the invention 1 is directed to a DC power supply, an inductor connected in series between the output terminal of the DC power supply and a vacuum load, and a parallel connection across the vacuum load. A semiconductor switch element connected in series with each other and a reverse voltage power supply; and a control circuit for driving the semiconductor switch element to turn on and off; and when the semiconductor switch element is turned on, In a vacuum device that applies a voltage having a reverse polarity to the output voltage from the reverse voltage power supply to the vacuum load, a first diode and a capacitor connected in series with each other are connected in parallel across the semiconductor switch element, One end of the primary winding of the pulse transformer is connected between the first diode and the capacitor, and the other end is connected to the semiconductor switch element. Connected to a reverse voltage power supply, connected to the secondary winding of the pulse transformer via a second diode between the output terminals of the DC power supply, and charged to the capacitor when the semiconductor switch element was turned off A vacuum apparatus is provided in which the charged electric charge is fed back to the DC power source via the pulse transformer when the semiconductor switch element is turned on.

  In order to solve the above-described problems, the second aspect of the present invention includes a DC power supply, an inductor connected in series between the output terminal of the DC power supply and the vacuum load, and a parallel connection across the vacuum load. A semiconductor switch element connected in series with each other and a reverse voltage power supply; and a control circuit that drives the semiconductor switch element to turn on and off; and when the semiconductor switch element is turned on, In a vacuum device that applies a voltage having a reverse polarity to the output voltage from the reverse voltage power supply to the vacuum load, a first diode and a capacitor connected in series with each other are connected in parallel across the semiconductor switch element, One end of the primary winding of the pulse transformer is connected between the first diode and the capacitor, and the other end is connected to the semiconductor switch element. A secondary winding of the pulse transformer is connected via a third diode between the output terminals of the reverse voltage power supply and connected to the capacitor when the semiconductor switch element is turned off. Provided is a vacuum device characterized in that the charged electric charge is fed back to the reverse voltage power source via the pulse transformer when the semiconductor switch element is turned on.

  In order to solve the above-described problems, the invention 3 is directed to a DC power supply, an inductor connected in series between the output terminal of the DC power supply and a vacuum load, and a parallel connection across the vacuum load. A semiconductor switch element connected in series with each other and a reverse voltage power supply; and a control circuit for driving the semiconductor switch element to turn on and off; and when the semiconductor switch element is turned on, In a vacuum device that applies a voltage having a reverse polarity to the output voltage from the reverse voltage power supply to the vacuum load, a first diode and a capacitor connected in series with each other are connected in parallel across the semiconductor switch element, One end of the primary winding of the pulse transformer is connected between the first diode and the capacitor, and the other end is connected to the semiconductor switch element. The first secondary winding of the pulse transformer is connected via a second diode between the output terminals of the DC power supply, and the first secondary winding of the pulse transformer is connected between the output terminals of the reverse voltage power supply. A second secondary winding of the pulse transformer is connected via a diode 3, and the turn ratio between the second secondary winding and the first secondary winding is determined by the output of the reverse voltage power source. And the charge charged in the capacitor when the semiconductor switch element is turned off via the pulse transformer when the semiconductor switch element is turned on. Provided is a vacuum apparatus which is fed back to a reverse voltage power source and the DC power source.

  A fourth aspect of the present invention provides the method according to any one of the first to third aspects, wherein the one end between the other end of the primary winding of the pulse transformer and the positive output terminal of the reverse voltage power source is one side. And / or a fifth diode having the other polarity and a fifth diode having the other polarity are connected.

  A fifth aspect of the present invention is the method according to any one of the first to fourth aspects, wherein the capacitance of the capacitor resonates with an inductance exhibited by a primary winding of the pulse transformer, and 1 / of one cycle of the resonance. The vacuum device is characterized in that the capacitance and the inductance are selected such that 4 is shorter than the on-time width of the semiconductor switch element.

  A sixth aspect of the present invention provides the method according to any one of the first to fifth aspects, wherein the pulse transformer is excited by a current flowing through a primary winding when the semiconductor switch element is turned on to store magnetic energy. A vacuum apparatus is provided that is a flyback type pulse transformer that emits the magnetic energy when the semiconductor switch element is turned off.

  According to the first aspect of the present invention, the energy from the reverse voltage power source is temporarily stored in the capacitor when the semiconductor switch element is turned off, and the energy is fed back to the DC power source, so that the power loss can be reduced and the power efficiency can be reduced. Improvement of the environment, improvement of the environment, suppression of the temperature rise of the vacuum apparatus, etc. can be achieved.

  According to the second aspect of the present invention, the energy from the reverse voltage power supply is temporarily stored in the capacitor when the semiconductor switch element is turned off, and the energy is fed back to the reverse voltage power supply. Improvement of efficiency, improvement of environment, suppression of temperature rise of the vacuum device, reduction in capacity and size of the reverse voltage power supply, and the like can be achieved.

  According to the third aspect, in addition to the effects obtained in the first aspect and the second aspect, an increase in the voltage of the reverse voltage power supply accompanying the feedback of energy can be suppressed.

  According to the fourth aspect of the invention, in addition to the effects obtained in any one of the first to third aspects, the primary diode of the pulse transformer is provided from the reverse voltage power source by including the fourth diode. Since no current flows through the windings, the power discharged from the reverse voltage power supply can be reduced, and the capacity of the reverse voltage power supply can be further reduced. Further, by providing the fifth diode, a reset voltage of the pulse transformer can be ensured, and this vacuum apparatus can be operated stably.

  According to the fifth invention, in addition to the effects obtained in the first invention to the fourth invention, the energy can be more efficiently fed back to the DC power supply or the reverse voltage power supply. Improvement of the environment, improvement of the environment, suppression of the temperature rise of the vacuum apparatus, etc. can be achieved.

  According to the sixth aspect of the invention, in addition to the effects obtained in the first to fifth aspects of the invention, by using a flyback type pulse transformer, the energy charged in the capacitor is magnetically applied to the pulse transformer. It can be stored as energy and efficiently returned to the DC power source.

Embodiment 1
First, the vacuum apparatus 100 of Embodiment 1 for implementing this invention with FIG.1 and FIG.4 is demonstrated. FIG. 1 shows a circuit configuration of the vacuum apparatus 100, and FIG. In FIG. 1, the same symbols as those shown in FIG. 5 indicate members having the same names. The DC power source 1 is a DC power source suitable for a vacuum load 3 including a rectifier that rectifies AC power of a commercial three-phase AC power source or a single-phase AC power source (not shown), a smoothing filter circuit, and the like. The reverse voltage power supply 4 is a DC power supply that can apply a pulsed reverse voltage suitable for the vacuum load 3. In this embodiment, the capacitor 4 </ b> A and the capacitor 4 </ b> A connected in series to the semiconductor switch element 5 are charged to a desired voltage. DC diode power supply, that is, a charging circuit 4B, and a diode 4C connected in parallel to the capacitor 4A in the same direction as the polarity of the charging circuit 4B. The semiconductor switch element 5 is preferably a voltage-driven semiconductor element such as IGBT or MOSFET. Further, the semiconductor switch element 5 has a parasitic diode 5A.

  The capacitor 7 and the first diode 8 connected in series with each other and connected in parallel with the semiconductor switch element 5 correspond to the capacitor C and the diode D shown in FIG. A second diode 9 is connected in series between the positive output terminal of the reverse voltage power supply 4 and the positive terminal of the semiconductor switch element 5. One end of the primary winding N1 of the pulse transformer 10 is connected to a connection portion between the capacitor 7 and the diode 8, and the other end of the primary winding N1 is connected to the semiconductor switch element 5 and the second through the third diode 11. It is connected to the connection point with the diode 9. The secondary winding N2 of the pulse transformer 10 is connected to both ends of the DC power source 1 through the fourth diode 12. The black dots attached to the primary winding N1 and the secondary winding N2 of the pulse transformer 10 indicate polarity. As can be seen from the black dots, the pulse transformer 10 is of a flyback type. Although not necessarily required, a fifth diode 13 and a sixth diode 14 are connected in parallel with the capacitor 7 across the semiconductor switch element 5 and the second diode 9.

  Here, the operation of each diode will be briefly described. The first diode 8 prevents the electric charge charged in the capacitor 7 from flowing directly to the semiconductor switch element 5, and the electric charge charged in the capacitor 7 is changed to a pulse transformer. It is intended to be discharged through 10 primary windings N1. The second diode 9 is for preventing a current from flowing from the primary winding N1 of the pulse transformer 10 to the positive electrode of the reverse voltage power supply 4 and securing a reset voltage of the primary winding N1. The third diode 11 is for preventing current from flowing from the positive electrode of the reverse voltage power supply 4 to the primary winding N1 of the pulse transformer 10. The fourth diode 12 is a diode that discharges the energy accumulated in the pulse transformer 10 to the DC power supply 1. The fifth diode 13 is turned on when the voltage at the connection point a between the inductor 2, the vacuum load 3, and the semiconductor switch element 5 becomes higher than the voltage at the positive terminal of the reverse voltage power supply 4. The second diode 9 is protected. The sixth diode 14 prevents the capacitor 7 from being charged with a reverse polarity due to resonance. The diode 4C of the reverse voltage power supply 4 functions to prevent the capacitor 4A from being charged in the reverse direction when the capacitor 4A is completely discharged due to an accident or the like.

  Next, an operation related to charging or discharging of the capacitor 7 accompanying switching of the semiconductor switch element 5 will be described with reference to FIG. The operation of applying the reverse voltage from the reverse voltage power supply 4 to the vacuum load 3 when the semiconductor switch element 5 is turned on, and the operation of the capacitor 7 and the diode 8 when the semiconductor switch element 5 is turned off are shown in FIG. This is the same as the conventional example. For easy understanding of the description, it is assumed that various conditions such as the output voltage, output current, surge voltage, etc. of the DC power supply 1 and the reverse voltage power supply 4 are the same as those in the conventional example. In FIG. 4, when the semiconductor switch element 5 is turned off at time t0, the DC power source 1 supplies 500V and 100A, and the voltage of the vacuum load 3 is zero when the voltage of the inductor 2 is zero. As shown in FIG. 4 (A), it is at about −500V. As shown in FIG. 4B, the capacitor 7 is charged to approximately 700 V, which is the sum of the output voltage 500 V of the DC power supply 1, the output voltage 100 V of the reverse voltage power supply 4, and the surge voltage 100 V.

  When the semiconductor switch element 5 is turned on at time t1, the current Ip that has been flowing through the inductor 2 through the vacuum load 3 is commutated to the path between the reverse voltage power supply 4 and the semiconductor switch element 5, that is, the reverse voltage power supply 4 is the current Ip. Is supplied. At the same time, the charging energy of the capacitor 7 is discharged through the primary winding N1 of the pulse transformer 10, the diode 11, and the semiconductor switch element 5, and substantially all the charging voltage of the capacitor 7 is applied to the primary winding N1 of the pulse transformer 10. The charging energy of the capacitor 7 is stored as magnetic energy in the primary winding N1. This operation is accompanied by a resonance phenomenon between the inductance L1 of the primary winding N1 of the pulse transformer 10 and the capacitance C1 of the capacitor 7. As shown in FIG. 4C, if the peak of the resonance current between the inductance of the primary winding N1 and the capacitance of the capacitor 7 is during the ON period of the semiconductor switch element 5, the charging energy of the capacitor 7 is effectively reduced. This is preferable because it can be transmitted to the secondary winding N2 side of the pulse transformer 10. Therefore, the primary winding is set so that ¼ of one period Tr of the resonance frequency between the inductance L1 of the primary winding N1 and the capacitance C1 of the capacitor 7 is equal to or shorter than the ON time (for example, 20 μm) of the semiconductor switch element 5. If the inductance L1 of N1 and the capacitance C1 of the capacitor 7 are selected, the discharge current of the capacitor 7 reaches the peak value during the ON time of the semiconductor switch element 5, and at the same time, the voltage of the capacitor 7 becomes zero (time t2). When the voltage of the capacitor 7 becomes zero, the resonance current flows through the diode 14 at time t2.

  When the semiconductor switch element 5 is turned off at time t3, the voltage of the secondary winding N2 of the pulse transformer 10 becomes negative on the black dot side and positive on the non-black dot side, and the magnetic energy stored in the inductance of the primary winding N1 is 4 (D), the current is discharged from the secondary winding N2 to the DC power source 1 through the diode 12 as a current. When the diode 12 is turned on, the voltage of the secondary winding N2 of the pulse transformer 10 is clamped to the voltage of the DC power supply 1. Therefore, by appropriately setting the ratio of the primary winding N1 and the secondary winding N2 of the pulse transformer 10, the voltage of the primary winding N1 can also be clamped to a desired voltage. As described above, the energy charged in the capacitor 7 when the semiconductor switch element 5 is turned off is fed back to the DC power source 1 and does not cause heat loss. Further, the energy is fed back to the DC power source 1 side. The current flowing through the semiconductor switch element 5 can be reduced. In particular, the energy charged in the capacitor 7 can be efficiently fed back to the DC power supply 1 by selecting the inductance L1 of the primary winding N1 of the pulse transformer 10 and the capacitance C1 of the capacitor 7 as described above. it can.

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described with reference to FIG. The vacuum apparatus 200 according to the second embodiment is different from the vacuum apparatus 100 according to the first embodiment in that the magnetic energy stored in the inductance of the primary winding N1 of the pulse transformer 10 is fed back to the reverse voltage power source 4 as described above. Differences from the vacuum device 100 will be mainly described. In FIG. 2, the same symbols as those used in FIG. 1 indicate members having the same names. In the vacuum device 200, the secondary winding N <b> 2 of the pulse transformer 10 is connected across the reverse voltage power supply 4 via the diode 15. Therefore, the charge charged in the capacitor 7 through the diode 8 when the semiconductor switch element 5 is turned off passes through the primary winding N1 of the pulse transformer 10 and the diode 11 when the semiconductor switch element 5 is turned on next time. And is stored as magnetic energy in the inductance of the primary winding N1 of the pulse transformer 10. The operation so far is the same as that of the vacuum device 100.

  When the semiconductor switch element 5 is turned off, the voltage of the secondary winding N2 of the pulse transformer 10 is negative on the black dot side and positive on the non-black dot side, and the magnetic energy stored in the inductance of the primary winding N1 is secondary. The current is discharged from the winding N2 through the diode 15 as a current to the capacitor 4A of the reverse voltage power supply 4 to charge the capacitor 4A. That is, the energy charged in the capacitor 7 when the semiconductor switch element 5 is turned off is fed back to the capacitor 4A of the reverse voltage power source 4 and does not cause heat loss. Since it is the same as that of the first embodiment, it will not be described again. However, the inductance L1 of the primary winding N1 of the pulse transformer 10 and the capacitance C1 of the capacitor 7 are selected. In particular, the capacitor 7 is selected and the on-time of the semiconductor switch element 5 is selected. By making the discharge current of the capacitor 7 reach the peak value, the capacity of the reverse voltage power source 4 can be reduced. For example, if the output capacity of the reverse voltage power supply 4 in the vacuum apparatus 100 of Embodiment 1 is 2000 W and the charging energy of the capacitor 7 is 245 W from the above, 245 W is fed back to the reverse voltage power supply 4 in this vacuum apparatus 200. The reverse voltage power supply 4 may have an output capacity of 1755 W.

[Embodiment 3]
Next, Embodiment 3 of the present invention will be described with reference to FIG. In the vacuum device 300 according to the third embodiment, as described above, the magnetic energy stored in the inductance of the primary winding N1 of the pulse transformer 10 is returned to the reverse voltage power source 4 and the DC power source 1 in the vacuum device 100 and the vacuum device 200. And different. Differences from the vacuum devices 100 and 200 will be mainly described. In FIG. 3, the same symbols as those used in FIGS. 1 and 2 indicate members having the same names. In the vacuum apparatus 300, the pulse transformer 10 includes a first secondary winding N2a and a second secondary winding N2b. Similarly to the first embodiment, the first secondary winding N2a of the pulse transformer 10 is connected across the DC power supply 1 via the diode 12, and the second secondary winding N2b of the pulse transformer 10 is connected to the second embodiment. In the same manner as above, the connection is made across the reverse voltage power supply 4 via the diode 15. In this vacuum apparatus 300, the electric charge charged in the capacitor 7 is preferentially fed back to the reverse voltage power supply 4 as energy, and when the feedback energy is excessive, the excessive amount is fed back to the DC power supply 1 to generate a reverse voltage. It is characterized by preventing it from rising more than necessary.

  In general, in such a vacuum apparatus, when the load current is small, not only the output current of the DC power supply 1 is reduced, but also the output current of the reverse voltage power supply 4 is reduced. However, the energy charged in the capacitor 7 depends on the frequency as described in the conventional example using mathematical expressions, and does not decrease even at light loads. Therefore, when all the energy charged in the capacitor 7 is fed back to the reverse voltage power source 4 at light load, there is a risk that the reverse voltage will rise more than necessary. In order to solve this problem, in the vacuum apparatus 300, the pulse transformer 10 is provided with the first secondary winding N2a and the second secondary winding N2b, and the first secondary winding N2a and the second secondary winding N2b are provided. The turn ratio with the secondary winding N2b is set to a ratio larger than 5: 1 (20%) of the output voltage (eg, 100V) of the reverse voltage power supply 4 to the output voltage (eg, 500V) of the DC power supply 1, for example, 4 pairs By setting 1 (25%), the increase in the reverse voltage of the reverse voltage power supply 4 can be limited to ¼ of the output voltage of the DC power supply 1.

  The black spot side of the first secondary winding N2a and the second secondary winding N2b of the pulse transformer 10 is negative and the non-spot side is positive, and the magnetic energy stored in the inductance of the primary winding N1 is At the stage of being discharged through the first secondary winding N2a and the second secondary winding N2b, the voltages of the first secondary winding N2a and the second secondary winding N2b rise, When the voltage of the first secondary winding N2a exceeds the output voltage (for example, 100V) of the reverse voltage power supply 4, the diode 15 is turned on to charge the capacitor 4A of the reverse voltage power supply 4. Then, the voltages of the first secondary winding N2a and the second secondary winding N2b further rise, and the voltage of the second secondary winding N2b exceeds the output voltage (for example, 500V) of the DC power supply 1. When the diode 12 becomes conductive, the magnetic energy is also fed back from the second secondary winding N2b, and the voltage of the second secondary winding N2b is clamped to the output voltage of the DC power supply 1.

Therefore, as described above, since the turn ratio of the first secondary winding N2a and the second secondary winding N2b is 4 to 1, the voltage of the second secondary winding N2b is approximately 125 ( Since the voltage is limited to about 500/4) V, the voltage of the capacitor 4A of the reverse voltage power supply 4 is also limited to about 125 (500/4) V or less, and does not become excessive. The preferable turn ratio range between the first secondary winding N2a and the second secondary winding N2b is approximately the same as the ratio P between the output voltage of the DC power supply 1 and the output voltage of the reverse voltage power supply 4, or the ratio P Up to about 150%.
Accordingly, the voltage of the reverse voltage power supply 4 can be determined by appropriately setting the turns ratio of the first secondary winding N2a and the second secondary winding N2b of the pulse transformer 10 to not only 4 to 1. Can be limited to below the desired value. Also in the third embodiment, since a part of the charging power of the capacitor 4A of the reverse voltage power supply 4 can be supplied from the capacitor 7, the capacity of the reverse voltage power supply 4 can be reduced.

  In each of the above embodiments, the control circuit 6 turns on and off the semiconductor switch element 5 at a predetermined frequency and a predetermined pulse width. Such an abnormal discharge prevention method has a large power loss. Therefore, an abnormal discharge suppression method for detecting the occurrence of abnormal discharge and turning on the semiconductor switch element 5 by a predetermined pulse width only when the abnormal discharge is detected has already been proposed. It is clear that the present invention can be applied to a method as it is. Furthermore, a method for preventing the occurrence of abnormal discharge that does not cause abnormal discharge has been proposed by predicting the occurrence of abnormal discharge and turning on the semiconductor switch element 5 by a predetermined pulse width immediately before the occurrence of abnormal discharge. The present invention can also be applied to such an abnormal discharge generation prevention method.

  In the above embodiment, the semiconductor switch element 5 is described as a single semiconductor element. However, since the sputtering apparatus has a load voltage of several hundred volts, when the IGBT or MOSFET is used as the semiconductor switch element 5, For example, it can be realized by one element having a withstand voltage of 1200 V, but in the case of an electron beam apparatus, since the load voltage is about 10 kV, it can be realized by connecting a plurality of IGBTs or MOSFETs having a withstand voltage of 1200 V in series. In this case, capacitors may be connected in parallel to the respective IGBTs or MOSFETs, and the energy charged in these capacitors may be discharged through the primary winding of the pulse transformer 10.

It is a figure which shows the circuit structure of the 1st vacuum apparatus 100 which concerns on Embodiment 1 of this invention. It is a figure which shows the circuit structure of the 2nd vacuum apparatus 200 which concerns on Embodiment 2 of this invention. It is a figure which shows the circuit structure of the 3rd vacuum apparatus 300 which concerns on Embodiment 3 of this invention. It is a wave form diagram for demonstrating the 1st vacuum apparatus 100 which concerns on this invention. It is a figure for demonstrating the circuit structure of the conventional vacuum apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... DC power supply 2 ... Inductor 3 ... Vacuum load 4 ... Reverse voltage power supply 5 ... Semiconductor switch element 6 ... Control circuit 7 ... Capacitor 8 ... Diode 9 ...・ Diode 10 ・ ・ ・ Pulse transformer 11 ～ 15 ・ ・ ・ Diode

Claims (6)

DC power source, inductor connected in series between the output terminal of the DC power source and the vacuum load, and semiconductor switch connected in parallel across the vacuum load and connected in series to each other An element, a reverse voltage power supply, and a control circuit for driving the semiconductor switch element on and off, and when the semiconductor switch element is turned on, a voltage having a polarity opposite to the output voltage of the DC power supply is supplied from the reverse voltage power supply. In a vacuum apparatus for applying to the vacuum load,
A first diode and a capacitor connected in series with each other are connected in parallel across the semiconductor switch element,
One end of the primary winding of the pulse transformer is connected between the first diode and the capacitor, and the other end is connected between the semiconductor switch element and the reverse voltage power source,
A secondary winding of the pulse transformer is connected between the output terminals of the DC power source via a second diode;
A vacuum apparatus, wherein the charge charged in the capacitor when the semiconductor switch element is turned off is fed back to the DC power source via the pulse transformer when the semiconductor switch element is turned on. DC power source, inductor connected in series between the output terminal of the DC power source and the vacuum load, and semiconductor switch connected in parallel across the vacuum load and connected in series to each other An element, a reverse voltage power supply, and a control circuit for driving the semiconductor switch element on and off, and when the semiconductor switch element is turned on, a voltage having a polarity opposite to the output voltage of the DC power supply is supplied from the reverse voltage power supply. In a vacuum apparatus for applying to the vacuum load,
A first diode and a capacitor connected in series with each other are connected in parallel across the semiconductor switch element,
One end of the primary winding of the pulse transformer is connected between the first diode and the capacitor, and the other end is connected between the semiconductor switch element and the reverse voltage power source,
Connecting the secondary winding of the pulse transformer between the output terminals of the reverse voltage power source via a third diode;
A vacuum apparatus, wherein the charge charged in the capacitor when the semiconductor switch element is turned off is fed back to the reverse voltage power source via the pulse transformer when the semiconductor switch element is turned on. DC power source, inductor connected in series between the output terminal of the DC power source and the vacuum load, and semiconductor switch connected in parallel across the vacuum load and connected in series to each other An element, a reverse voltage power supply, and a control circuit for driving the semiconductor switch element on and off, and when the semiconductor switch element is turned on, a voltage having a polarity opposite to the output voltage of the DC power supply is supplied from the reverse voltage power supply. In a vacuum apparatus for applying to the vacuum load,
A first diode and a capacitor connected in series with each other are connected in parallel across the semiconductor switch element,
One end of the primary winding of the pulse transformer is connected between the first diode and the capacitor, and the other end is connected between the semiconductor switch element and the reverse voltage power source,
Connecting the first secondary winding of the pulse transformer between the output terminals of the DC power source via a second diode;
Connecting a second secondary winding of the pulse transformer between the output terminals of the reverse voltage power source via a third diode;
A turns ratio between the second secondary winding and the first secondary winding is made larger than a ratio of an output voltage of the reverse voltage power supply and an output voltage of the DC power supply;
The vacuum charged in the capacitor when the semiconductor switch element is turned off is fed back to the reverse voltage power source and the DC power source via the pulse transformer when the semiconductor switch element is turned on. apparatus. In any one of Claims 1 thru | or 3,
Between the other end of the primary winding of the pulse transformer and the positive output terminal of the reverse voltage power supply, both a fourth diode having one polarity and a fifth diode having the other polarity, or A vacuum apparatus characterized in that any one of them is connected. In any one of Claim 1 thru | or 4,
The capacitance of the capacitor causes resonance with the inductance exhibited by the primary winding of the pulse transformer, and the capacitance is set so that 1/4 of one period of the resonance is shorter than the on-time width of the semiconductor switch element. A vacuum apparatus, wherein the inductance is selected. In any one of Claims 1 thru | or 5,
The pulse transformer is a flyback type that is excited by a current flowing through a primary winding when the semiconductor switch element is turned on to accumulate magnetic energy, and that releases the magnetic energy when the semiconductor switch element is turned off. A vacuum device characterized by being a pulse transformer.

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