JP4498000B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply device having a function of suppressing or eliminating the occurrence of abnormal discharge in a load device such as a sputtering device that uses plasma in a vacuum, or a vacuum device such as an etching device or an electron beam evaporation device. Regarding improvements.

  Conventionally, a sputtering device connected to a DC power source provided with an inverter circuit, a rectifier that rectifies the output, and a filter that smoothes the output, or a vacuum such as an etching device or an electron beam evaporation device is used. In a load device such as a vacuum device, the impedance of the electrode of the load device decreases, or a conductive dust or the like shorts between the electrodes, causing a temporary abnormal discharge of plasma, or an electron beam In a vapor deposition apparatus, abnormal discharge may occur between a filament at a high potential and an electrode located around the filament.

In the sputtering apparatus, when an abnormal discharge occurs, there is a problem that a substrate material such as a liquid crystal during sputtering is given a defect, resulting in a decrease in product yield.
In addition, in the electron beam evaporation apparatus, the filament breaks due to the discharge energy.
As a countermeasure against these abnormal discharges in a vacuum device such as a sputtering device, when the abnormal discharge occurs, the vacuum device is short-circuited, and the energy of the filter capacitor and the filter inductor in the DC power supply is vacuumed. There is one that bypasses the apparatus and prevents damage to the substrate material such as liquid crystal being processed (see Patent Document 1).

By Figure 9, it will be described conventional power supply circuit for supplying an electric power to a load device, such as a vacuum device disclosed in Patent Document 1. In FIG. 9 , a DC power source 31 for converting AC power from the AC power source 30 into a desired DC voltage is not only a general DC-DC converter 31A but also a filter capacitor 31B and a filter inductor 31C at its output. The resistor 31D and the diode 31E are connected in parallel to the inductor 31C. The resistor 31D and the diode 31E constitute a circuit for consuming the energy of the filter inductor 31C. A crowbar switch 33 for short-circuiting the load device 32 when an abnormal discharge occurs and a current detector 34 for detecting a load current are provided between the DC power supply 31 and the load device 32 which is a vacuum device as described above. Further, a control circuit 35 for controlling an inverter circuit (not shown) in the DC-DC converter 31A of the DC power supply 31 and for turning on and off the crowbar switch 33 is provided. Note that the high voltage side of a vacuum device such as sputtering or electron beam evaporation has a negative polarity, and the positive electrode housing is normally grounded.

  In such a general DC power source, the filter inductor 31C has an inductance of several hundreds μH to several mH, and as the inductance increases, the electron beam or plasma discharge becomes more stable and shifts to abnormal discharge. Experience is known to be difficult. This is because it is difficult to shift from minute discharge to full-scale abnormal discharge due to the constant current action of the inductance.

  However, even in such a conventional power supply device, abnormal discharge may occur in the load device 32. In this case, since the current detected by the current detector 34 becomes an overcurrent state, the control circuit 35 turns off the DC-DC converter 31A of the DC power supply 31 and simultaneously turns on the crowbar switch 33 to load the load device. 32 is short-circuited. Along with this, the crowbar switch 33 bypasses the energy in the DC power source, the energy of the capacitor 31B, and the inductor 31C from the load device 32, so that the substrate in the load device 32 can be prevented from being damaged.

  However, in the conventional countermeasures against abnormal discharge of vacuum equipment, the top priority is to increase the production efficiency by minimizing the downtime. In order to increase the production efficiency by minimizing the downtime, a short time after the abnormal discharge disappears. In other words, when the current detected by the current detector 34 becomes almost the rated value, the crowbar switch 33 is suddenly turned off. Therefore, there is a high risk that a surge voltage including a rebound voltage of the inductance of the inductor 31C for the filter is applied to both ends of the crowbar switch 33 made of an IGBT (insulated gate bipolar transistor) or MOSFET and is destroyed. In order to prevent this, the resistor 31D and the diode 31E are connected in parallel with the inductor 31C, and the resistor 31D and the diode 31E consume the energy of the inductor 31C in a short time. The higher the resistance value of the resistor 31D, the shorter the energy disappearance time, but the overvoltage of the crowbar switch 33 increases. In addition, this high voltage may cause a transition to an abnormal discharge state again, which may not necessarily lead to an improvement in productivity.

  Further, if the resistance value of the resistor 31D is reduced, the surge voltage is reduced, but the constant current action of the filter inductor 31C is reduced, and the energy discharge time is lengthened, and the current duration of the diode 31E is increased. It becomes longer and requires a diode for high current. In other words, high-cost surge countermeasures are necessary, and power loss cannot be reduced despite a decrease in reliability.

  Further, the problem of driving the crowbar switch 33 in a vacuum apparatus such as sputtering will be described. When the first trigger of the vacuum apparatus, that is, a voltage about twice as large as the steady voltage is applied at the time of ignition, the crowbar switch If 33 is erroneously turned on, a side current larger than the planned side current at the time of steady state flows and there is a risk of breakage. In particular, a positive voltage change (so-called dV / dt) is also applied to the first trigger of the vacuum apparatus, that is, immediately after ignition or immediately after abnormal discharge, and there is a risk that the crowbar switch 33 composed of MOSFET and IGBT malfunctions.

Furthermore, there is another problem in the configuration in which the abnormal discharge caused by turning on the conventional crowbar switch 33 is extinguished. Even the crowbar switch 33 used in a power supply device having a relatively small power capacity has a large forward current and has a forward drop of 10 V or more. When the crowbar switch 33 is turned on, the normal abnormal discharge disappears as described above. However, the forward drop of the crowbar switch 33 causes the load 4 to be forward biased with a voltage of 10 V or more, and an arc of several volts, In the case of abnormal discharge, it becomes insufficient to extinguish the abnormal discharge. In a vacuum apparatus such as sputtering, there is a possibility of such low voltage abnormal discharge.
JP-A-8-311647

The present invention minimizes the withstand voltage of a short-circuiting semiconductor switch without adversely affecting the constant-current action of the inductor in a power supply device including a short-circuiting semiconductor switch for eliminating abnormal discharge in a vacuum device or the like. Therefore, one of the issues is how to turn off the short-circuiting semiconductor switch, and how quickly the residual voltage remaining after the short-circuiting semiconductor switch is turned on can be zeroed using the on-state of the shorting semiconductor switch. Or the other issue is whether to invert.

In order to solve the above problems, a first aspect of the present invention, a vacuum device, a DC power supply for supplying power to the vacuum device, an inductance of performing constant-current action of the current flowing in the vacuum device, in parallel with the vacuum device a semiconductor switch connected Ru shorted, and the abnormal discharge detection circuit that detects abnormal discharge of the vacuum device, the abnormal discharge from the detection circuit abnormal discharge detection signal by turning on the semiconductor switch the short, a drive circuit for turning off, A capacitor connected in series with the short-circuiting semiconductor switch; and a charging power source for charging the capacitor . When the abnormal discharge occurs or when the occurrence of the abnormal discharge is predicted, the short-circuiting semiconductor switch is turned on. the a power supply device for terminating said abnormal discharge by applying a reverse polarity voltage to the vacuum device from the capacitor, the capacitor is reversed A diode that prevents charging is connected in parallel with the capacitor in the same direction as the conduction direction of the short-circuiting semiconductor switch, and the voltage across the vacuum device is applied when the vacuum device is ignited. A voltage interlock circuit that does not turn on the short-circuit semiconductor switch when an upper limit value of a steady discharge voltage lower than the ignition voltage is exceeded , and a current that flows through the short-circuit semiconductor switch when the short-circuit semiconductor switch is on However, when the current drops to 10% or less of the rated current, the drive circuit turns off the short-circuiting semiconductor switch.

According to a second aspect of the present invention, in the power supply device described in the first aspect of the invention, after the shorting semiconductor switch is turned on, a current flowing through the shorting semiconductor switch is reduced to 10% or less of the rated current. The power supply device is characterized in that a predetermined time T until the time is obtained and set in a timer unit, and the short-circuiting semiconductor switch is turned off when the predetermined time T elapses.

According to a third aspect of the present invention, in the power supply apparatus according to the first aspect of the present invention, the power supply device further includes a current detector that detects a current flowing through the short-circuiting semiconductor switch, and the current detected by the current detector is a rated current of 10. The power supply device is characterized in that the short-circuiting semiconductor switch is turned off when the voltage drops to below%.

According to a fourth aspect of the present invention, in the power supply device according to any one of the first to third aspects, the shorting semiconductor switch is an IGBT or a FET, and a collector or drain and a gate of the IGBT or FET. to provide power supply apparatus, wherein a diode for preventing being coupled to said collector or drain series discharge of the capacitance between the.

According to a fifth aspect of the present invention, in the power supply device according to any one of the first to fourth aspects, the abnormal discharge detection circuit generates an abnormal discharge when the detection voltage of the load voltage decreases. Or when the load current flowing through the vacuum device increases above a set value, it is determined that an abnormal discharge has occurred, or when the load voltage falls below a set value, it is determined that an abnormal discharge has occurred. Or a combination thereof, or when the load current increases rapidly and the load voltage decreases rapidly, the rate of change (differential once) is larger than the set value. If it is determined that a discharge has occurred, or if the value obtained by differentiating the load current twice is larger than a set value, the occurrence of abnormal discharge is predicted by detecting the state immediately before the occurrence of abnormal discharge. Providing power supply device which is characterized in that either Luke.

According to the first aspect of the present invention, when the abnormal discharge occurs in the vacuum device, or as a short-circuit semiconductor switch which is turned on to short-circuit the vacuum device when to predict its occurrence, using a low inexpensive semiconductor switch breakdown voltage be able to. Further, since a high voltage is not generated when the short-circuiting semiconductor switch is turned off, it is possible to eliminate the risk of leading to abnormal discharge again. Further, even if a voltage higher than a set value such as an ignition voltage is applied, the short-circuiting semiconductor switch is not damaged or destroyed due to power loss. Further, according to the first invention, when the short-circuit semiconductor switch is turned on to extinguish the low voltage abnormal discharge, the reverse bias voltage is applied to the load device, and the current flowing through the load device is quickly made zero. can do. In addition, this can be realized with a simple circuit configuration.

According to the second aspect of the present invention, the predetermined time T for turning on the short-circuiting semiconductor switch only needs to be set in advance in the timer circuit, so that the circuit can be simplified and economically advantageous.
  According to the third aspect of the invention, since the diode or the IGBT or MOSFET used as the short-circuiting semiconductor switch prevents the electrostatic discharge between the collector and the drain and the gate, the power loss can be reduced and the malfunction is caused. Can also be prevented.

According to the fourth aspect of the invention, since the diode or the IGBT or MOSFET used as the short-circuiting semiconductor switch prevents the electrostatic discharge between the collector and the drain and the gate, the power loss can be reduced and the malfunction is caused. Can also be prevented.
According to the fifth aspect of the present invention, various abnormal discharge occurrence detection or prediction methods can be provided.

[Embodiment 1]
With reference to FIG. 1, a power supply apparatus 100 according to a first embodiment of the present invention will be described. In FIG. 1, a short circuit that acts as a crowbar switch as described above is provided between output terminals of a DC power source 2 such as a DC-DC converter that converts AC power from an AC power source 1 such as a commercial power source into desired DC power. The semiconductor switch 3 is connected. This short-circuiting semiconductor switch 3 is made of an IGBT or a MOSFET, and is the same as the conventional one. An abnormal discharge detection circuit 5 is connected between the DC power source 1 and a load device 4 such as the vacuum device.

  The abnormal discharge detection circuit 5 determines that an abnormal discharge has occurred when the polarity of the detection voltage of the load voltage is reversed, and detects abnormal discharge when the load current flowing through the load device exceeds a set current value. Judgment, or judgment that abnormal discharge occurs when the load voltage at both ends of the load device falls below the set voltage value, a combination of these, or the load current increases rapidly, and the load voltage decreases rapidly If the rate of change (differential once) is steeper than the set value, that is, if it is larger, the discharge current is determined to be abnormal discharge, and the value obtained by differentiating the load current twice is set. If it is larger than that, there is a case where the state immediately before the occurrence of the abnormal discharge is detected, that is, the occurrence of the abnormal discharge is predicted.

  When the abnormal discharge detection circuit 5 detects the abnormal discharge as described above, the abnormal discharge detection circuit 5 outputs an abnormal discharge detection signal to the drive circuit 6 of the shorting semiconductor switch 3. The drive circuit 6 includes a timer unit 7 and a drive signal generation unit 8. The timer unit 7 plays an important role in the first embodiment, and sends a timer signal to the drive signal generating unit 8 until a predetermined time T elapses after receiving the abnormal discharge detection signal. . The drive signal generator 8 sends an ON drive signal to the short-circuiting semiconductor switch 3 for the predetermined time T during which the timer signal is received from the timer unit 7 to turn it ON, and is turned OFF with the disappearance of the timer signal. A signal is sent to the shorting semiconductor switch 3 to turn it off.

  The predetermined time T is set as follows. As shown in FIG. 7, the DC power supply 1 is often provided with an inductor for a filter. Even when the inductor is not provided, the inductance of a transformer of a DC-DC converter (not shown) or leakage in a circuit is not provided. There are inductances and capances. When the short-circuit semiconductor switch 3 is turned on due to the occurrence of abnormal discharge, the energy stored in the inductance and capacitance of the DC power source 2 is circulated through the short-circuit semiconductor switch 3 and the DC power source 2. It is attenuated by the power consumption of the DC power supply circuit components and the short-circuit semiconductor switch 3.

If the short-circuit semiconductor switch 3 is turned off when the circulating current returns to the rated current value as in the prior art, the rated current value is applied to both ends of the short-circuit semiconductor switch 3 by the action of the inductance, although it returns to the rated current value. Since a voltage several times as large as the voltage is applied, in the present invention, the maximum time during which the current flowing through the short-circuiting semiconductor switch 3 falls to 10% or less of the rated current, preferably substantially to near zero is defined as the predetermined time T. To do. The predetermined time T is obtained in advance from various experiments and is several hundreds of μs. This predetermined time T is set in the timer unit 7 in advance. When an abnormal discharge occurs, the DC-DC converter (not shown) of the DC power supply 2 detects an overcurrent internally and is turned off after a predetermined time T has elapsed or before and after.
If the rated current is 10% or less, the surge voltage due to the inductance can be absorbed only by adding a simple small-capacity snubber circuit to the short-circuiting semiconductor switch 3.

  In the first embodiment, the short-circuiting semiconductor switch 3 is turned off after a lapse of a predetermined time T in which the circulating current flowing through the short-circuiting semiconductor switch 3 is reduced to 10% or less of the rated current, preferably substantially to near zero. Therefore, only about the rated voltage is applied to both ends of the short-circuiting semiconductor switch 3, and therefore it is necessary to use a short-circuiting semiconductor switch having a withstand voltage that is twice or several times higher than the rated voltage as in the prior art. There is no economic advantage. In addition, since an excessively high voltage is not generated when the short-circuiting semiconductor switch 3 is turned off as in the prior art, it is possible to eliminate a risk of reoccurring abnormal discharge.

  When the circulation current flowing through the short-circuiting semiconductor switch 3 is small, that is, when the power consumption of the closed circuit through which the circulating current flows is small, a resistor or a plurality of diodes may be connected in series to the closed circuit. Good. In the case of a diode, even if it is connected to the immediate side of the short-circuiting semiconductor switch 3, the voltage rise due to the circulating current is small because it is only the forward drop.

[Embodiment 2]
Next, a power supply apparatus 200 according to the second embodiment will be described with reference to FIG. 2, the same symbols as those used in FIG. 1 indicate members having the same names.
In the second embodiment, the current detector 9 that detects the circulating current flowing through the short-circuiting semiconductor switch 3, and the current value of the circulating current detected by the current detector 9 is 10% or less of the rated current, preferably substantially zero. And a determination circuit 10 for identifying whether or not the voltage has dropped to the vicinity. In this power supply device 200, the ON operation and the function of the short-circuiting semiconductor switch 3 are the same as those in the first embodiment, and thus the description thereof is omitted.

  The determination circuit 10 detects whether or not the current detection signal from the current detector 9 tends to decrease, compares the current detection signal with the set value, and the current detection signal decreases, that is, falls to the right. In this case, an open signal is sent to the drive circuit 6 when it becomes equal to or less than the set value. Here, the set value of the determination circuit 10 is a value corresponding to 10% or less of the rated current, that is, 1/10 or less of the rated current. When the drive circuit 6 receives the open signal from the determination circuit 10, it supplies an off drive signal to the short-circuiting semiconductor switch 3 to turn it off.

  Also in the second embodiment, when the circulating current that circulates between the short-circuiting semiconductor switch 3 and the DC power source 2 when an abnormal discharge occurs falls to a certain set value that is 10% or less of the rated current, Since the short-circuiting semiconductor switch 3 is turned off, an excessively large voltage is not applied to the short-circuiting semiconductor switch 3, and therefore, an IGBT or a MOSFET having a withstand voltage that is twice or several times higher than the rated voltage as in the prior art is used. There is no need and it is economically advantageous. Moreover, since an excessively high voltage is not generated at both ends of the short-circuiting semiconductor switch 3 as in the prior art, abnormal discharge does not occur again.

[Embodiment 3]
Next, a more specific configuration of the power supply apparatus 300 according to the third embodiment of the present invention will be described with reference to FIG. In FIG. 3 showing the power supply apparatus 300, the same symbols are used for the same symbols as those used in FIG. 1 and FIG.
This third embodiment pays attention to the low probability of occurrence of abnormal discharge such as arc discharge, and provides a power supply device capable of obtaining maximum reliability with minimum power loss and cost. is there.
The DC power source 2 includes a rectifying / smoothing circuit 2A that rectifies and smoothes the AC power source from the AC power source 1, a general inverter circuit 2B that converts a DC voltage into a high-frequency AC voltage, a boosting transformer 2C, a rectifying circuit 2D, and a filter. And a control circuit 2G for controlling the inverter circuit 2B.

  An IGBT is used as the short-circuiting semiconductor switch 3, and a diode 11 is connected in series with the collector terminal, which is one of the main terminals, to prevent discharge of the electrostatic charging voltage between the collector and the gate of the IGBT. ing. The function of the diode 11 will be described later with reference to FIG. 4 showing a specific example of the drive circuit 6.

  The drive circuit 6 includes the timer unit 7 and the insulation drive signal generation unit 8 'described in the first embodiment. In this power supply device 300, the load device 4 is a vacuum device such as a sputtering device, an etching device, an electron beam evaporation device, etc., and the output potential of the timer unit 7 is low, and the control terminal of the short-circuit semiconductor switch 3 is lower than that potential. Therefore, an insulated drive signal generator 8 ′ that can electrically insulate between the output of the timer unit 7 and the control terminal of the shorting semiconductor switch 3 is used. An example of the insulated drive signal generator 8 'will be described in detail later.

  The abnormal discharge detection circuit 5 is connected in parallel to a high voltage resistor 5A that constitutes a voltage detection circuit that detects the voltage of the load device when it is normal, and a voltage detection resistor 5B and a high voltage resistor 5A connected in series to the high voltage resistor 5A. And a determination circuit 5D that determines whether the detected voltage is normal or abnormal, and outputs an abnormality detection signal to the drive circuit 6 when it is abnormal. The determination circuit 5D determines that an abnormal discharge has occurred when the polarity of the detection voltage is reversed.

  Next, the operation of the power supply device 300 will be described. If the load device 4 is in a normal state, the polarity of the load voltage detection signal is not reversed, so the abnormal discharge detection circuit 5 does not output the abnormality detection signal, and therefore the drive circuit 6 does not turn on the short-circuit semiconductor switch 3. Further, no stop signal is given to the control circuit 2G. In this state, the control circuit 2G performs a normal control operation, and the inverter circuit 2B performs a normal operation to supply DC power to the load device 4. At this time, the detection capacitor 5C is charged to the polarity shown.

When a current is supplied from the DC power source 1 to the vacuum device as the load device 4, if an abnormal discharge such as arc discharge occurs in the vacuum device 4, the vacuum device 4 is in a low impedance state, and therefore the detection capacitor 5C The electric charges having the polarities shown in FIG.
This discharge current i flows through the resistor 5B in the direction indicated by the arrow, and reverses the polarity of the voltage across the resistor 5B. A positive voltage is generated in the resistor 5B as viewed from the ground. When the determination circuit 5D detects that the polarity of the detection voltage has been reversed, the determination circuit 5D determines that an abnormal discharge has occurred, and outputs an abnormal discharge detection signal to the timer unit 7 of the drive circuit 6.

This transient state will be described in more detail. When the abnormal discharge occurs, the detection delay of the abnormal discharge detection circuit, the delay of the off-time of the inverter circuit 2B, and the delay of the on-time of the short-circuit semiconductor switch 3, The DC power source 1 is short-circuited by the vacuum device 4 through the inductor 2F, and the current of the inductor 2F increases.
However, immediately after that, the short-circuit semiconductor switch 3 is turned on and the inverter circuit 2B is turned off. Therefore, most of the energy of the internal capacitor 2E of the DC power supply 1 and the energy of the inductor 2F are the same as those of the short-circuit semiconductor switch 3 and DC power supply 1. It circulates through the rectifier circuit 2D and is consumed by those circuit losses.

  Returning to the description, the timer unit 7 inputs a signal having a pulse width equal to the predetermined time T set in advance after receiving the abnormal discharge detection signal to the insulated drive signal generation unit 8 '. Since the predetermined time T is the same as that described in the first embodiment, the description thereof is omitted. When the insulation drive signal generation unit 8 ′ receives a signal having a pulse width equal to the predetermined time T from the timer unit 7, the insulation drive signal generation unit 8 ′ turns on the short-circuiting semiconductor switch 3 for the predetermined time T, and when the predetermined time T elapses, Switch 3 is turned off.

  On the other hand, the timer unit 7 receives this abnormal discharge detection signal and outputs a signal to the insulation drive signal generation unit 8 'after a lapse of the predetermined time T, and simultaneously gives a stop signal to the control circuit 2G. Upon receiving this stop signal, the control circuit 2G turns off the inverter circuit 2B and stops the supply of power. Here, it is desirable that the semi-short-circuit semiconductor switch 3 is turned off first and the inverter circuit 2B is turned on later, but the order of turning them on can be reversed.

As described above, when the predetermined time T elapses, the circulating current flowing through the closed circuit including the short-circuit semiconductor switch 3, the inductor 2F, and the rectifier circuit 2D of the DC power supply 2 is reduced to 10% or less of the rated current. Therefore, even if the short-circuiting semiconductor switch 3 is turned off when the predetermined time T has elapsed, an excessive voltage is not applied to the short-circuiting semiconductor switch 3, and a voltage of about the rated voltage is applied. Only. Therefore, it is possible to use a short-circuit semiconductor switch 3 such as an IGBT or FET having a lower withstand voltage than the conventional one.
In addition, since a high voltage is not generated between both ends of the short-circuiting semiconductor switch 3, abnormal discharge such as arc discharge does not immediately recur. Therefore, in this embodiment, paying attention to the low probability of occurrence of abnormal discharge such as arc discharge, it is possible to realize a power supply device capable of obtaining maximum reliability with minimum power loss and cost.

  Furthermore, in this embodiment, during the abnormal discharge of the load device 4, the energy of the inductance such as the inductor 2F is reduced within a predetermined time due to the loss of the inductance itself, the loss of the short-circuiting semiconductor switch 3, and the loss of the rectifier circuit 2D in the DC power supply. To consume. Since each of these parts originally has the ability to pass a rated current, it has the ability to sufficiently withstand short-time overcurrent that is several times less than the rated current. Usually, the predetermined time is several hundreds μs or less, and if the DC power supply is stopped for a predetermined time or more after an abnormal discharge, for example, 1 ms and then started up again in about 1 ms, the overload time ratio is about 10%, which is sufficiently thermal. Can withstand. In particular, since a resistor or a series circuit of a resistor and a diode is not connected in parallel to the inductor 2F as in the prior art, the number of parts is reduced, and the constant current action of the inductance during normal operation is not reduced, and stable plasma is obtained. Discharge can be realized.

  Furthermore, the diode 11 prevents the electrostatic capacitance between the collector and the gate of the IGBT from being discharged and charged due to the fluctuation of the collector voltage when the shorting semiconductor switch 3 is an IGBT or an FET. In order to describe the function of the diode 11 in detail, an example of an insulated drive signal generator 8 'that uses an IGBT as the shorting semiconductor switch 3 and drives the IGBT will be described with reference to FIG. In general, a general IGBT 3 used as a short-circuiting semiconductor switch has a capacitance C between a collector 3c and a gate 3g. The collector-gate capacitance C is as large as several nF. 3e is an emitter.

The insulation drive signal generator 8 ′ includes a signal insulation circuit 8′A composed of a pulse transformer or a photocoupler that electrically insulates between the timer part 7 and the insulation drive signal generator 8 ′, and a high-side NPN transistor 8 'B is roughly constituted by a low-side PNP transistor 8'C connected in series to this.
When a positive pulse signal having a width of the predetermined time T is applied from the timer unit 7 via the signal insulating circuit 8′A, the high-side NPN transistor 8′B is turned on and the low-side PNP transistor 8′C is The driving power supply voltage of 15 V is applied to the gate terminal of the IGBT 3 and the IGBT 3 is turned on.
Next, as the predetermined time T elapses, the pulse signal disappears, the NPN transistor 8'B is turned off, the PNP transistor 8'C is turned on, the voltage at the gate terminal of the IGBT 3 becomes 0V, and the IGBT 3 is turned off. .

  When the voltage of the collector 3c changes in the decreasing direction when the IGBT 3 is turned off without the diode 11, the charge of the electrostatic capacitance C between the collector and the gate is discharged, and the voltage decreases. In this state, the voltage of the collector 3c again increases (so-called dV / dt) in the increasing direction. If the voltage change is large, the charging current also increases, and a large charging current flows into the gate circuit through the capacitance C, which may be turned on by mistake. That is, the IGBT 3 that is a crowbar switch may be turned on when unnecessary, and if it is turned on erroneously at the ignition voltage of sputtering, an excessive current flows and there is a risk that the IGBT 3 or the like is damaged due to excessive power loss.

  However, in the third embodiment, since the diode 11 is connected in series to the collector 3c which is one main terminal of the IGBT 3 which is the crowbar switch, as shown in FIG. 5, the voltage of the collector 3c (shown by a solid line). Since the charge of the collector-gate capacitance C is not discharged by the diode 11 even if the voltage of the curve A) decreases, the collector-gate is not charged except when the charge voltage immediately after the IGBT 3 is turned on is low. The voltage of the inter-capacitance C (curve B indicated by the chain line) is maintained at a high level, and therefore no large charging current flows, so that the IGBT 3 does not malfunction. This further improves the reliability of the power supply apparatus 300.

[Embodiment 4]
Next, a power supply device 400 according to the fourth embodiment of the present invention will be described with reference to FIG. In FIG. 6, the same symbols as those used in FIG. 4 indicate the same members. The fourth embodiment shows an example of an effective circuit configuration of the abnormal discharge detection circuit 5.
The abnormal discharge detection circuit 5 is connected in series to the output terminal of the DC power supply 2 and is electromagnetically coupled to the primary winding n1 through which current flowing from the DC power supply 2 to the load device flows and the primary winding n1. An inductor 5G having a secondary winding n2, a diode 5H connected in series to the secondary winding n2, a resistor 5I to which a voltage substantially equal to the voltage across the secondary winding n2 is applied, and a reference voltage are generated. It comprises a reference voltage source 5J and a comparator 5K that compares the voltage of the resistor 5I with the reference voltage and outputs an H level signal when the voltage of the resistor 5I is higher than the reference voltage. The H level output signal of the comparator 5K is input to the timer unit 7 of the drive circuit 6. Here, the inductor 5G may be one in which a secondary winding is provided on the inductor 2F of the DC power source 2 in the power supply apparatus 300 according to the third embodiment, or an inductor provided separately from the inductor 2F. Alternatively, it may exhibit an inductance that stabilizes the load current.

  Next, the operation will be described. Assuming that the load device 4 is a vacuum device as described above, plasma discharge is generated in a steady state, and the load current flowing through the primary winding n1 of the inductor 5G is substantially constant in this steady plasma discharge. Therefore, no effective voltage is generated at both ends of the inductor 5G, that is, at both ends of the secondary winding n2. Therefore, the voltage of the resistor 5I is lower than the reference voltage of the reference voltage source 5J, and the comparator 5K does not output an output signal.

  When arc discharge, which is abnormal discharge, occurs in the load device 4, almost all of the output voltage of the DC power supply 2 is applied to the inductor 5G, and a voltage having a positive black dot appears in the primary winding n1 of the inductor 5G. . When the load device 4 is a sputtering device, the output voltage of the DC power supply 2 is generally about 400 V, and the turns ratio of the primary winding n1 and the secondary winding n2 of the inductor 5G is 40: 1. A voltage of about 10 V is generated in the secondary winding n2. This voltage is applied to the non-inverting (+) terminal of the resistor 5I and the comparator 5K through the diode 5H. The comparator 5K compares the voltage of about 10V applied to the non-inverting terminal with the reference voltage of about 5V applied from the reference voltage source 5J to the inverting (−) terminal, and outputs an H level indicating the occurrence of abnormal discharge. The signal is given to the timer unit 7 of the drive circuit 6.

  In the same manner as described above, the timer unit 7 gives a timer signal having a pulse width equal to the predetermined time T from the time when the H level output signal is received from the comparator 5K to the insulated drive signal generating unit 8 ′, thereby generating an insulated drive signal. The unit 8 ′ turns on the short-circuit semiconductor switch 3 such as an FET for the predetermined time T. At the same time, the timer signal is also given to the control circuit of the DC power source 2 as described above, and the DC power source 2 is turned off for the predetermined time T. When the timer signal disappears as the predetermined time T elapses, the short-circuiting semiconductor switch 3 is turned off again and the DC power supply 2 is turned on. Also in this embodiment, since the current flowing through the short-circuiting semiconductor switch 3 is reduced to 10% or less of the rated current when the short-circuiting semiconductor switch 3 is turned off, an excessive voltage is applied when the short-circuiting semiconductor switch 3 is turned off. There is no. The abnormal discharge detection circuit can be used for various devices and is a meaningful circuit.

[Embodiment 5]
Next, a power supply apparatus 500 according to the fifth embodiment of the present invention will be described with reference to FIG. In FIG. 7, the same symbols as those used in FIG. 4 indicate the same members. This power supply device 500 has a voltage interface between the timer unit 7 and the insulated drive signal generation unit 8 ′ that does not turn on the short-circuiting semiconductor switch 3 when the load voltage is higher than a predetermined set voltage value higher than the rated voltage. A lock circuit 12 is provided. The voltage interlock circuit 12 is, for example, a switching element (not shown) such as an FET connected in series between the timer unit 7 and the insulated drive signal generating unit 8 ′, or the timer unit 7 and the insulated drive signal generating unit. A switching element (not shown) connected between a connection point with the unit 8 ′ and the ground, and when the detection voltage of the load voltage is equal to or higher than a set voltage value, the switching element is turned off or on, and a timer The signal output from the unit 7 is cut off and not transmitted to the insulated drive signal generating unit 8 ′.
Therefore, when the detection voltage of the load voltage is equal to or higher than the set value, the insulated drive signal generator 8 ′ does not generate a drive signal due to the action of the voltage interlock circuit 12. The DC power source 2 includes a current detector 2H that detects a load current, and an overcurrent detection cutoff circuit 2I that stops the inverter circuit 2B when an overcurrent occurs in the control circuit 2G. Here, the current detector 2H may also serve as a current limiting resistor that performs current limiting.

  Next, the operation of the power supply apparatus 500 will be described with respect to differences from the power supply apparatus 300. When the load device 4 is normally discharged, the load voltage is at the rated voltage, and when an abnormal discharge occurs in the load device 4, the load voltage naturally falls below the rated voltage as is apparent from the above. Therefore, the voltage interlock circuit 12 transmits the signal from the timer unit 7 as it is to the insulated drive signal generation unit 8 ′. Therefore, the insulated drive signal generator 8 'supplies an on drive signal to the shorting semiconductor switch 3 during abnormal discharge, and turns on the shorting semiconductor switch 3 for a predetermined time T as described above. Therefore, at the time of normal discharge or abnormal discharge, there is no influence of the voltage interlock circuit 12 provided. Since this operation and effect are as described in the above embodiment, the description thereof is omitted.

  On the contrary, if the voltage of the load device 4 exceeds a set voltage higher than the rated voltage before the load device 4 is ignited, the voltage interlock circuit 12 turns off the switch element (not shown), The connection point between the timer unit 7 and the insulated drive signal generating unit 8 ′ is connected to the grounding point by disconnecting between the unit 7 and the insulated drive signal generating unit 8 ′ or by turning on the switch element (not shown). By short-circuiting, the signal from the timer unit 7 is prevented from being transmitted to the insulated drive signal generating unit 8 ′. Therefore, when the load voltage is equal to or higher than a predetermined set voltage value, the short-circuit semiconductor switch 3 is not turned on.

  This is important from the viewpoint of protection of the short-circuiting semiconductor switch 3. Since the power loss is determined by the product of the voltage applied to the short-circuit semiconductor switch 3 and the current flowing therethrough, if the short-circuit semiconductor switch 3 is turned on with a large voltage, the power loss becomes very large. It is necessary to use the short-circuit semiconductor switch 3 having a much larger amount of power than that at the time of rating. This is not suitable for the basic technical idea of the present invention.

  As an example, when the load device 4 is a vacuum device, if the short-circuit semiconductor switch 3 is erroneously turned on by an ignition voltage, for example, an ignition voltage of 1200 V, the IGBT or MOSFET that is the short-circuit semiconductor switch 3 is damaged. Therefore, when the voltage of the vacuum device and the load voltage are higher than the upper limit of the steady discharge voltage, for example, a voltage higher than 800V, the voltage interlock circuit 12 causes the insulated drive signal generator 8 'to output the ON drive signal. Is suppressed.

Further, in the power supply device 500, unlike the power supply device 300, it is not necessary to send an off signal from the timer unit 7 to the DC power source 1. Instead, when the current detection signal detected by the current detector 2H provided in the return circuit of the DC power supply 2 is larger than the set value and an overcurrent state occurs, the overcurrent cutoff circuit 2I of the control circuit 2G is activated. As a result, the control circuit 2G immediately stops the inverter circuit 2B, and puts the inverter circuit 2B in a stopped state for a period equal to or longer than the predetermined time T.
When the current detector 2H also serves as a current limiting resistor as described above, the energy of the filter capacitor 2E and the inductor 2F is consumed when the shorting semiconductor switch 3 is turned on. The current circulating through the semiconductor switch 3 and the DC power supply 2 is greatly attenuated, and the short-circuiting semiconductor switch 3 can be turned off in a short time.

  That is, in this power supply device 500, abnormal discharge can be eliminated without exchanging signals between the circuit on the short-circuiting semiconductor switch 3 side and the DC power supply 2, so that the DC power supply 2 can be used as an option of the DC power supply 2 later. There is an advantage that can be added. In addition, there is an advantage that it can be retrofitted to the DC power source 2 as necessary, such as a vacuum apparatus that is likely to cause abnormal discharge, or an application where abnormal discharge should be avoided as much as possible, such as a sputtering apparatus for liquid crystal. The DC power supply 2 itself can be provided with an abnormal discharge detection circuit similar to the abnormal discharge detection circuit 5 described above, and the abnormal discharge can be detected by the abnormal discharge detection circuit and the inverter circuit of the DC power supply 2 can be stopped.

[Embodiment 6]
Next, a power supply apparatus 600 according to the sixth embodiment of the present invention will be described with reference to FIG. 8, the same symbols as those used in FIG. 7 indicate the same members. As described in the above embodiment, when the abnormal discharge is detected by the abnormal discharge detection circuit 5 or when the occurrence of the abnormal discharge is predicted, the drive circuit 6 turns on the short-circuit semiconductor switch 3. However, since the short-circuit semiconductor switch 3 generally has a forward drop of several volts or more, the voltage at both ends of the load device 4 is the forward direction of the short-circuit semiconductor switch 3 even when the short-circuit semiconductor switch 3 is turned on. It does not drop to a voltage value equal to the sum of the drop and the forward drop of the diode 11, for example, 10V or less. Although the normal abnormal discharge disappears when the short-circuit semiconductor switch 3 is turned on, ions generated by the abnormal discharge remain immediately after that, so the load is still in a relatively low impedance state and 10 V There is a possibility that the low voltage abnormal discharge cannot be extinguished at a voltage of about a level. The purpose of the sixth embodiment is to quickly reverse the low voltage abnormal discharge voltage.

  In the power supply device 600 of the sixth embodiment, the capacitor 21 is connected in series to the anode side of the short-circuit semiconductor switch 3, and the diode 22 oriented in the same direction as the conduction direction of the short-circuit semiconductor switch 3 is connected in parallel with the capacitor 21. Connecting. A charging power source 24 is connected to both ends of the capacitor 21 via a protective resistor 23 connected as necessary. The charging power source 24 charges the capacitor 21 with the polarity shown in the drawing, that is, the polarity opposite to the polarity of the output voltage of the DC power source 2. The magnitude of the charging voltage is not limited to this, but is, for example, 10% or less of the steady discharge voltage of the load device 4. Usually, in a vacuum device, the plasma discharge voltage of the load device 4 is 200 to 800 V, so the output voltage of the charging power supply 24 is set to 20 to 80 V according to the plasma discharge voltage. The output voltage of the charging power supply 24 may be a fixed value or a voltage that is automatically changed according to the plasma discharge voltage. In this Embodiment 6, it is set to 50V.

  Here, the capacitor 21, the diode 22, the protective resistor 23, and the charging power source 24 constitute a load reverse bias power source that applies a reverse bias voltage to the load device 4. The charging power source 24 has a simple circuit configuration including a transformer that converts a commercial power source voltage into a desired voltage and a rectifier circuit that rectifies the AC voltage, although the detailed circuit configuration is not shown in the figure. Various configurations such as a configuration in which a separate winding (not shown) is provided in the transformer 2C and a rectifier circuit having a normal configuration for converting the AC voltage into a desired DC voltage is connected to the separate winding can be considered. Any charging circuit may be used.

  Next, the operation of the power supply apparatus 600 of this embodiment will be described. The operation of the power supply device 600 is the same as the operation of the power supply device 500 except for the operation of the load reverse bias power source. When the load device 4 is operating normally, the short-circuiting semiconductor switch 3 is in the OFF state as described above, and the capacitor 21 is charged to 50 V by the charging power source 24. If an abnormal discharge occurs in the load device 4 in this state, the abnormal discharge detection circuit 5 detects the occurrence of the abnormal discharge and sends an abnormal discharge detection signal to the drive circuit 6. Upon receiving the abnormal discharge detection signal, the drive circuit 6 immediately turns on the shorting semiconductor switch 3.

  As a result, a voltage obtained by adding a reverse polarity voltage (−50 V) to a voltage (for example, 10 V) equal to the sum of forward drops of the short-circuiting semiconductor switch 3 and the diode 11 at both ends of the load device 4, That is, a reverse polarity voltage of −40V is applied. By this reverse bias voltage, the abnormal discharge generated in the load device 4 can be terminated more quickly, and the minute current flowing after that can be made zero. If the current supply amount of the load reverse bias power supply is sufficiently large, the reverse bias voltage can be continuously applied to the load device 4 until the abnormal discharge is detected and the inverter circuit 2B is stopped. It can be quickly terminated. When all the electric charge of the capacitor 21 is discharged, if the energy of the inductance 2F still remains, the diode 22 becomes conductive and the load voltage of the load device 4 becomes almost several volts again. Further, the diode 22 does not charge the capacitor 21 in reverse to the illustrated polarity. In this case, the protective resistor 23 protects the charging power supply 24 from being directly short-circuited by the diode 22.

  When the current flowing through the load device 4 once becomes zero and the ions generated by the abnormal discharge disappear, the impedance of the load device 4 increases, so that a very small current does not flow again. Actually, the reverse voltage application time may be several μs to several tens of μs, which is the time until the ions generated by the abnormal discharge disappear and the load exhibits high impedance. . Since the capacitor 21 only needs to be charged during a time when no abnormal discharge occurs, the power capacity of the charging power source 24 can be minimized, and not only the miniaturization but also the economy is excellent.

  Specifically, the capacitance of the capacitor 21 may be appropriately selected according to the discharge current, and the reverse voltage may be maintained for several μs to several tens of μs. An example is shown. When the short-circuit current that flows when the short-circuiting semiconductor switch 3 is turned on is a triangular wave with a peak of 200 A, the capacitance C of the capacitor 21 is about 100 μF from the calculation formula. If the maximum arc occurrence frequency is 1/10 ms (the repetition frequency is 100 Hz), the power P required to reverse bias the load device 4 is about 12.5 W from the calculation formula. That is, according to the load reverse bias power source of this embodiment, it can be about 12.5 W, which is economical.

  It should be noted that the conventional apparatus for preventing abnormal discharge of plasma discharge is a reverse voltage pulse system that additionally includes a dedicated circuit that immediately applies a reverse voltage to the load device and immediately returns to the normal voltage polarity when an abnormal discharge is detected. In the case of this method, in order to immediately return to the normal voltage polarity, the surge voltage when the short-circuiting semiconductor switch is turned off increases, and a large-capacitance short-circuiting semiconductor switch is required. There was a drawback to become. However, according to the power supply device of the sixth embodiment, an abnormal discharge can be stopped quickly and completely with a small-capacity load reverse bias power source with a very simple configuration, so that there is a great economic advantage.

  Also in the first to fifth embodiments, the load reverse bias power source described in the sixth embodiment can be connected in series to the short-circuit switch. Although it is preferable to turn off the shorting switch as described above, it is not always necessary to limit the turning off of the shorting switch, and a reverse bias voltage is applied to the load device by using the turning on of the shorting switch. I can do it.

In the above embodiments, the IGBT or MOSFET that is the short-circuiting semiconductor switch 3 has been described as one, but a semiconductor switch in which a plurality of IGBTs or MOSFETs are connected in series according to the voltage of the load device is used. But of course. Moreover, you may use what connected resistance, a capacitor | condenser, etc. in parallel with IGBT or MOSFET as a semiconductor switch for a short circuit as needed. Furthermore, in the third and fifth embodiments, the inductor 2F has been described as a filter inductor for the DC power supply 2, but it may of course be an inductor separately connected to the output terminal of the DC power supply.

1 is a diagram illustrating a power supply device 100 according to a first embodiment of the present invention. It is a figure which shows the electric power supply apparatus 200 which is 2nd Embodiment which concerns on this invention. It is a figure which shows the electric power supply apparatus 300 which is 3rd Embodiment which concerns on this invention. It is a figure which shows an example of the drive circuit used for the electric power supply apparatus 300 which is embodiment of this invention. It is a figure for demonstrating operation | movement of the electric power supply apparatus 300 which is embodiment of this invention. It is a figure which shows the electric power supply apparatus 400 which is the 4th Embodiment of this invention. It is a figure which shows the electric power supply apparatus 500 which is the 5th Embodiment of this invention. It is a figure which shows the electric power supply apparatus 600 which is the 6th Embodiment of this invention. It is a figure which shows the example of the electric power supply apparatus provided with the conventional abnormal discharge suppression function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... AC power source 2 ... DC power source 2A ... Rectification / smoothing circuit 2B ... Inverter circuit 2C ... Transformer 2D ... Rectifier circuit 2E ... Capacitor 2F ... Inductor 2G ... Control circuit of inverter circuit 2B 2H ... Current detector 2I ... Overcurrent detection interruption Circuit 3 ... Semiconductor switch for short circuit 4 ... Load device 5 ... Abnormal discharge detection circuit 5A, 5B ... Resistor for detecting load voltage 5C ... Capacitor for detecting load voltage 5D ... Discriminating circuit 5G ... Primary winding n1 and secondary Inductor having winding n2 5J Reference voltage source 5K Comparator 6 Drive circuit of semiconductor switch 3 for short circuit 7 Timer unit (circuit)
8 ... Drive signal generator 8 '... Insulated drive signal generator (circuit)
DESCRIPTION OF SYMBOLS 9 ... Current detector of semiconductor switch 3 for short circuit 10 ... Determination circuit 11 ... Diode 12 ... Voltage interlock circuit 21 ... Capacitor 22 ... Diode 24 ... Power supply for charge

Claims (5)

A vacuum device;
A DC power supply for supplying power to the vacuum apparatus,
An inductance performing a constant current action of the current flowing through the vacuum device;
A semiconductor switch connected Ru short circuit in parallel with the vacuum device,
An abnormal discharge detection circuit for detecting an abnormal discharge of the vacuum device;
A drive circuit for turning on and off the short-circuiting semiconductor switch by an abnormal discharge detection signal from the abnormal discharge detection circuit;
A capacitor connected in series with the short-circuiting semiconductor switch;
A charging power source for charging the capacitor;
With
A power supply device that turns on the short-circuit semiconductor switch when the abnormal discharge occurs or predicts the occurrence of the abnormal discharge, and applies a reverse polarity voltage from the capacitor to the vacuum device to terminate the abnormal discharge. And
A diode that prevents the capacitor from being charged with a reverse polarity is connected in parallel with the capacitor in the same direction as the conduction direction of the short-circuiting semiconductor switch,
A voltage interlock circuit that does not turn on the short-circuit semiconductor switch when the voltage across the vacuum device exceeds the upper limit of the steady discharge voltage lower than the ignition voltage applied at the time of ignition of the vacuum device;
When the shorting semiconductor switch is in an ON state, the driving circuit turns off the shorting semiconductor switch when a current flowing through the shorting semiconductor switch is reduced to 10% or less of a rated current. Power supply device. The power supply device according to claim 1,
A predetermined time T from when the short-circuiting semiconductor switch is turned on until the current flowing through the short-circuiting semiconductor switch decreases to 10% or less of the rated current is determined in advance and set in the timer unit. A power supply device that turns off the short-circuiting semiconductor switch when time T elapses. The power supply device according to claim 1,
A current detector for detecting a current flowing through the short-circuiting semiconductor switch is provided, and the short-circuiting semiconductor switch is turned off when the current detected by the current detector drops to 10% or less of the rated current. A power supply device. In the electric power supply apparatus in any one of Claims 1 thru | or 3 ,
The semiconductor switch for short-circuit is an IGBT or FET, and wherein the diode for preventing a discharge of the capacitance between the said IGBT or FET collector or drain and gate connected to the collector or drain series Power supply device. The power supply device according to any one of claims 1 to 4 ,
The abnormal discharge detection circuit determines that an abnormal discharge has occurred when the detection voltage of the load voltage decreases,
Alternatively, when the load current flowing through the vacuum device increases above a set value, it is determined that abnormal discharge has occurred,
Alternatively, when the load voltage falls below a set value, it is determined that abnormal discharge has occurred, or a combination of these is determined,
Or, when the load current is rapidly increased and the load voltage is rapidly decreased, when the rate of change (differential once) is larger than a set value, it is determined that an abnormal discharge has occurred,
Furthermore, when the value obtained by differentiating the load current twice is larger than the set value, it is either one of detecting the state immediately before the occurrence of abnormal discharge and predicting the occurrence of abnormal discharge. A power supply device characterized by the above.

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