JP2010251161A - Power supply for vacuum load - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply for a vacuum load that prevents abnormal discharge from repeating, by speedily extinguishing it when abnormal discharge is generated. <P>SOLUTION: This power supply for a vacuum load includes a dc power supply, parallel-connected to the vacuum load to impress an ac voltage on the vacuum load; an abnormal discharge arc-extinguishing circuit parallel-connected to the vacuum load to impress a dc reverse voltage on the vacuum load; and a control circuit to control the dc reverse voltage of the abnormal discharge arc-extinguishing circuit by detecting abnormal discharge in the vacuum load. The abnormal discharge arc-extinguishing circuit includes a reverse voltage dc voltage source that impresses a dc reverse voltage having a reverse code on the vacuum load. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vacuum load power source including an abnormal discharge arc extinguishing circuit that quickly extinguishes occurrence of abnormal discharge in a vacuum load.

  For example, the power source for the vacuum load applies a DC voltage to a vacuum load used in a sputtering apparatus, an etching apparatus, an electron beam evaporation apparatus, a PVD apparatus, a CVD apparatus, etc. that processes or processes using plasma generated in a vacuum. To do.

  The abnormal discharge generated in the vacuum load is generated by a decrease in impedance between the electrodes or a short circuit. When such abnormal discharge occurs, for example, in a sputtering apparatus, a defect is caused in the substrate material, resulting in a decrease in product yield.

  In order to solve this problem, an abnormal discharge arc extinguishing circuit that prevents or suppresses abnormal discharge has been proposed. For example, as a relatively simple and effective circuit for extinguishing abnormal discharge, there is also a technology for applying a DC reverse voltage to a vacuum load from a reverse voltage DC voltage source periodically or for a short time when an abnormal discharge occurs. It has been proposed (see, for example, Patent Document 1). This is to cut off the output current by applying a DC reverse voltage to the vacuum load and extinguish the abnormal discharge. The higher the value of the DC reverse voltage, the faster the discharge current can be cut off. .

JP 2008-123772 A

  However, in order to shorten the time to extinguish, if the reverse voltage is increased and the output current is cut off and the abnormal discharge is extinguished, if a high DC reverse voltage is continuously applied to the vacuum load, the discharge current will be reversed. Abnormal discharge such as flowing may occur again.

  Therefore, in the present invention, when an abnormal discharge occurs, by applying a high reverse voltage for a predetermined time, the abnormal discharge is quickly extinguished and the interruption time of the output current is shortened, so that the abnormal discharge is not repeated. An object of the present invention is to provide a power source for a vacuum load.

  To achieve the above object, the vacuum load power supply of the present invention superimposes the DC reverse voltage charged in the overdrive capacitor on the DC reverse voltage from the reverse voltage DC voltage source when an abnormal discharge occurs. The configuration is such that it is applied to a vacuum load.

  Specifically, the power source for a vacuum load of the present invention is connected in parallel to a vacuum load, a DC power source for applying a DC voltage to the vacuum load, and a DC voltage of the DC power source connected in parallel to the vacuum load. And an abnormal discharge arc extinguishing circuit that applies a reverse DC voltage having the opposite sign to the vacuum load, and a control circuit that detects an abnormal discharge in the vacuum load and controls the DC reverse voltage of the abnormal discharge arc extinguishing circuit The abnormal load arc extinguishing circuit is applied to the vacuum load from the DC power source and an inductance connected in series between the DC power source and the vacuum load. A reverse voltage direct current voltage source that applies a direct current reverse voltage having a sign opposite to that of the direct current voltage to the vacuum load, and a direct current reverse voltage having the same sign as the direct current reverse voltage from the reverse voltage direct current voltage source is superimposed on the vacuum load. Apply overdrive to A capacitor and a switching element that is turned on and off by the control of the control circuit are connected in series with a capacitor and a DC reverse voltage applied from the reverse voltage DC voltage source and the overdrive capacitor. And

  According to this configuration, the vacuum load power supply can quickly extinguish the abnormal discharge and shorten the output current interruption time. In addition, the occurrence of abnormal discharge can be suppressed. And when a switch element turns on, the electric current which flows into a vacuum load or a switch element can be restrict | limited.

  In the vacuum load power source of the present invention, energy from the commutation diode for preventing reverse charging, the overdrive charging switch element that is turned on / off by the control of the charging control circuit, and the reverse voltage DC voltage source is stored. A charging inductance for charging the stored energy to the overdrive capacitor, and an anode side of the commutation diode is connected to one end of the overdrive charging switch element and one end of the charging inductance, and the commutation The cathode side of the diode is at the connection point between the switch element and the overdrive capacitor, and the other end of the charging inductance is at the connection point between the overdrive capacitor and the reverse voltage DC voltage source. The other end of the switch element is the reverse voltage DC voltage Wherein the further comprising a respective connection point of the DC power source connected to the overdrive capacitor charger with.

  According to this configuration, when an abnormal discharge occurs, the vacuum load power source can quickly extinguish the arc by quickly operating the abnormal discharge extinguishing circuit.

  The vacuum load power supply of the present invention is connected in parallel to the vacuum load and applies a DC voltage to the vacuum load, connected in parallel to the vacuum load, and the DC voltage and sign of the DC power supply are An abnormal discharge arc extinguishing circuit for applying a reverse DC reverse voltage to the vacuum load; detecting an abnormal discharge in the vacuum load; a DC voltage of the DC power supply; and a DC reverse voltage of the abnormal discharge arc extinguishing circuit A control circuit for controlling the vacuum load, wherein the abnormal discharge arc extinguishing circuit applies a DC reverse voltage having a sign opposite to a DC voltage applied to the vacuum load from the DC power supply. An overdrive capacitor to be applied to a load, and a switch element that is turned on / off by the control of the control circuit are connected in series with a DC reverse voltage applied from the overdrive capacitor. And wherein the door.

  According to this configuration, the vacuum load power supply can quickly extinguish the abnormal discharge and shorten the output current interruption time. In addition, the occurrence of abnormal discharge can be suppressed. Furthermore, since a reverse voltage DC voltage source is not required, the circuit configuration is small and simple.

  Moreover, it is desirable that the overdrive capacitor used in the vacuum load power source of the present invention has a capacity to discharge all the charged charges while the switch element is on.

  According to this configuration, the overdrive capacitor can quickly extinguish the abnormal discharge and shorten the output current interruption time by discharging the charged charge.

  The control circuit used for the vacuum load power source of the present invention is a control circuit for detecting a voltage fluctuation in the vacuum load that is a predetermined value or more and controlling a DC reverse voltage of the abnormal discharge arc extinguishing circuit. But you can.

  According to this configuration, the control circuit can detect abnormal discharge in the vacuum load if the voltage fluctuation value in the vacuum load exceeds a predetermined range. The above configurations can be combined as much as possible.

  According to the present invention, when an abnormal discharge occurs, by applying a high reverse voltage for a predetermined time, the abnormal discharge is quickly extinguished and the interruption time of the output current is shortened, and the abnormal discharge is not repeated. A power supply for a vacuum load can be provided.

It is a figure shown about the power supply for vacuum loads which concerns on 1st embodiment of this invention. FIG. 3 is a detailed view of an overdrive capacitor charger provided in the vacuum load power source according to the first embodiment of the present invention. It is a figure which shows operation | movement of the power supply for vacuum loads which concerns on 1st embodiment of this invention, (a) is the output voltage applied to a vacuum load, (b) is the output current which flows into a vacuum load, (c) is The voltage at the connection point between the switch element and the overdrive capacitor, (d) shows the gate signal of the switch element. It is a figure shown about the power supply for vacuum loads which concerns on 2nd embodiment of this invention. It is a figure which shows operation | movement of the power supply for vacuum loads which concerns on 2nd embodiment of this invention, (a) is the output voltage applied to a vacuum load, (b) is the output current which flows into a vacuum load, (c) is The voltage at the connection point between the switch element and the overdrive capacitor, (d) shows the gate signal of the switch element.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(First embodiment)
FIG. 1 is a diagram showing a vacuum load power source according to the first embodiment of the present invention. The power source for a vacuum load according to the first embodiment of the present invention is connected in parallel to the vacuum load 12 and connected to the vacuum load 12 in parallel with the DC power source 10 that applies a DC voltage to the vacuum load 12. An abnormal discharge extinguishing circuit 24 that applies a DC reverse voltage having a sign opposite to that of the DC voltage 10 to the vacuum load 12 through the switch element 20; and an abnormal discharge extinguishing circuit 24 that detects an abnormal discharge in the vacuum load 12; And a control circuit 42 for controlling the DC reverse voltage through the switch element 20 of the first power supply, and the abnormal discharge arc extinguishing circuit 24 is connected in series between the DC power supply 10 and the vacuum load 12. A current limiting inductance 30, a reverse voltage direct current voltage source 11 for applying a direct current reverse voltage having a sign opposite to that of the direct current voltage applied from the direct current power source 10 to the vacuum load 12, and the reverse voltage direct current voltage source 1. The overdrive capacitor 22 that further superimposes the direct current reverse voltage having the same sign on the direct current reverse voltage from, and is applied to the vacuum load 12, and the direct current reverse voltage applied from the reverse voltage direct current voltage source 11 and the overdrive capacitor 22 The switch element 20 that is turned on and off by the control of the control circuit 42 is connected in series.

  In FIG. 1, a current limiting inductance 30 and a cable impedance 50 are connected between a vacuum load 12 and a DC power supply 10. The DC power source 10 is a negative output DC power source that generates DC voltage by constant power or constant current control, the reverse voltage DC voltage source 11 is a reverse voltage DC power source that generates DC reverse voltage, and the vacuum load 12 is DC For example, a sputtering apparatus that forms a thin film or the like using plasma generated by applying a DC voltage from a power supply 10 in a vacuum state. The overdrive capacitor 22 performs discharge for quickly extinguishing the abnormal discharge. The switch element 20 is a switch for connecting or blocking a series circuit of the reverse voltage DC voltage source 11 and the overdrive capacitor 22 to a vacuum load.

  The overdrive capacitor charger 21 charges the overdrive capacitor 22. The bypass diode 23 prevents reverse charging of the overdrive capacitor 22. The current limiting inductance 30 limits the current flowing from the DC power supply 10 to the switch element 20 when the switch element 20 is turned on. The cable impedance 50 is generated along with the output cable when the output cable is connected, and is shown as an inductance in FIGS. 1, 2, and 4. The control circuit 42 detects abnormal discharge and sends a gate signal to the switch element 20. The abnormal discharge arc extinguishing circuit 24 includes a current limiting inductance 30, a reverse voltage DC voltage source 11, a switching element 20, an overdrive capacitor charger 21, an overdrive capacitor 22, a bypass diode 23, and a control circuit 42. The

  The vacuum load 12 should just maintain the vacuum state and can install the object which forms a thin film etc. in an inside. As an apparatus using plasma in the vacuum load 12, for example, a sputtering apparatus, an etching apparatus, an electron beam evaporation apparatus, a PVD (Physical Vapor Deposition) apparatus, a CVD (Chemical Vapor Deposition): chemical vapor deposition method. ) Equipment.

  A sputtering device is a device for manufacturing thin films for semiconductors, liquid crystals, plasma displays, and optical discs that require high-quality thin films. In the vacuum load 12, a metal to be formed into a thin film is set as a target, and a high voltage is applied. This is an apparatus for depositing a thin film by colliding with a rare gas element (such as argon) or nitrogen that has been ionized in such a manner to blow off atoms on the surface of the target to reach the substrate.

  The etching apparatus is an apparatus that is used in fields such as thin film fabrication and material processing, and performs an etching operation for digging fine holes using plasma by utilizing the fact that plasma generated in the vacuum load 12 can be controlled at the atomic level. .

  An electron beam vapor deposition apparatus is a kind of vapor deposition apparatus, in which a vapor deposition material is heated within a vacuum load 12 using an electron beam, vaporized or sublimated, and adhered to the surface of a substrate placed at a distant position to form a thin film. It is the vapor deposition apparatus which forms a film.

  A PVD device is a device that uses a metal thin film forming method for forming a three-dimensional structure such as a transistor. In a vacuum, a high-energy atom such as argon or its ions is struck against a metal disk such as aluminum in a vacuum. This is an apparatus for forming a thin film by blowing off atoms and depositing metal atoms in layers on the surface of the material.

  The CVD apparatus is an apparatus for producing thin film silicon used for, for example, a solar cell panel. For the purpose of activating a chemical reaction, the inside of the vacuum load 12 is depressurized to generate plasma, and the target is formed on a heated substrate material. In this apparatus, a raw material gas containing a thin film component is supplied, and a film is deposited by a chemical reaction on the substrate surface or in the gas phase.

  The switch element 20 may be of any type as long as it has a function of connection and disconnection. For example, a semiconductor switch element using a semiconductor element such as a voltage-driven IGBT (insulated gate bipolar transistor), MOSFET (field effect transistor), or thyristor can be applied. The overdrive capacitor 22 may be of any type as long as it can be charged and discharged. For example, a plastic film capacitor, a ceramic capacitor, an electrolytic capacitor, etc. can be applied. The bypass diode 23 may be of any type as long as it has a function of bypassing the overdrive capacitor 22 and causing a reverse current to flow from the reverse voltage DC voltage source 11 to the switch element 20.

  The current limiting inductance 30 receives the added voltage from the DC power source 10 and the reverse voltage DC voltage source 11 when the switch element 20 is turned on, absorbs the flowing current as magnetic energy, and the vacuum load 12 or the switch element. The current flowing to 20 is limited. The current limiting inductance 30 may be a coil wound with an electric wire. For example, there are an air core coil, a core coil, and a toroidal coil. The control circuit 42 only needs to be configured to detect abnormal discharge in the vacuum load 12 based on the output voltage and to turn on and off the switch element 20 with a drive signal having a predetermined pulse time. Further, the control circuit 42 may detect abnormal discharge from an increase in current of the vacuum load 12.

  Details of the abnormal discharge arc extinguishing circuit 24 will be described. The reverse voltage DC voltage source 11 has a polarity opposite to that of the DC power source 10 and generates a DC reverse voltage of 10% to 25% of the plasma voltage of the vacuum load 12. For example, when the plasma voltage is −400V, a DC reverse voltage of + 100V is generated. Here, the plasma voltage is a voltage in the vacuum load 12 in a plasma state. The overdrive capacitor 22 quickly extinguishes the abnormal discharge in cooperation with the DC reverse voltage output from the reverse voltage DC voltage source 11. The control circuit 42 detects the abnormal discharge of the vacuum load 12 and turns on the switch element 20 at a constant pulse time. The switch element 20 connects a series circuit of the reverse voltage DC voltage source 11 and the overdrive capacitor 22 in parallel to the vacuum load 12. The overdrive capacitor charger 21 charges the overdrive capacitor 22 to a set voltage.

  For example, when the plasma voltage of the vacuum load 12 is −400 V and the DC reverse voltage is +100 V, the overdrive capacitor 22 is charged to +100 V. The bypass diode 23 has a function of preventing the overdrive capacitor 22 from being reversely charged by the reverse voltage DC voltage source 11 when the switch element 20 is turned on and all charges of the overdrive capacitor 22 are discharged. The current limiting inductance 30 limits the current flowing from the DC power supply 10 to the switch element 20 when the switch element 20 is turned on.

  FIG. 2 is a detailed view of the overdrive capacitor charger 21 provided in the vacuum load power source according to the first embodiment of the present invention. Energy from the overdrive charging switch element 31 and the reverse voltage DC voltage source 11 that are turned on and off by the control of the commutation diode 33 and the charging control circuit 40 is accumulated, and the accumulated energy is charged in the overdrive capacitor 22. The commutation diode 33 has an anode side connected to one end of the overdrive charging switch element 31 and one end of the charging inductance 32, and a cathode side of the commutation diode 33 is connected to the switching element 20 and the overdrive. At the connection point with the capacitor 22, the other end of the charging inductance 32 is at the connection point between the overdrive capacitor 22 and the reverse voltage DC voltage source 11, and the other end of the overdrive charge switch element 31 is at the reverse voltage DC voltage source. 11 and the connection point between the DC power supply 10 and They are respectively connected. The description of the elements described in FIG. 1 is omitted.

  The overdrive charging switch element 31 connects the reverse voltage DC voltage source 11 to the charging inductance 32. The overdrive charging switch element 31 is switching-controlled at several kHz to 100 kHz when the voltage of the overdrive capacitor 22 falls below a set value, and energy is supplied to the charging inductance 32 when the overdrive charging switch element 31 is turned on. And the overdrive capacitor 22 is charged through the commutation diode 33 when it is off. The overdrive charging switch element 31 has a function of connection and disconnection, and any type can be used as long as it can be turned on and off at about several kHz to 100 kHz. The charging inductance 32 accumulates energy from the reverse voltage DC voltage source 11 and charges the accumulated energy to the overdrive capacitor 22 through the commutation diode 33. It is sufficient that the voltage from the reverse voltage DC voltage source 11 is received and the flowing current can be absorbed as magnetic energy. For example, a coil wound with an electric wire may be used. For example, there are an air core coil, a core coil, and a toroidal coil. The commutation diode 33 may be of any type as long as it has a function of preventing reverse current. For example, a PN diode can be applied.

  The commutation diode 33 commutates the current flowing from the reverse voltage DC voltage source 11 through the charging inductance 32 to the overdrive charging switch element 31 to the overdrive capacitor 22 when the overdrive charging switch element 31 is turned off. To charge. The charging control circuit 40 detects the charging voltage of the overdrive capacitor 22 and periodically turns on and off the overdrive charging switch element 31 to charge the overdrive capacitor 22 to the set voltage. Turns on and off when the charging voltage reaches the set voltage.

(Normal operation)
Hereinafter, the normal operation of the vacuum load power source according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3. In FIG. 1, a DC power supply 10 applies a negative DC voltage to generate plasma in a vacuum load 12. The overdrive capacitor 22 and the reverse voltage DC voltage source 11 constituting the abnormal discharge extinguishing circuit 24 are disconnected from the vacuum load 12 by the switch element 20 until an abnormal discharge occurs and is detected by the control circuit 42. The For this reason, the negative DC voltage of the DC power supply 10 is applied to the vacuum load 12 during normal operation.

  In FIG. 2, while the overdrive capacitor 22 and the reverse voltage DC voltage source 11 constituting the abnormal discharge extinguishing circuit 24 are disconnected from the vacuum load 12 by the switch element 20, the overdrive capacitor 22 is overloaded. The drive capacitor charger 21 is charged to a predetermined voltage.

  The operation of the overdrive capacitor charger 21 will be described. First, the charging control circuit 40 turns on the overdrive charging switch element 31. When the overdrive charging switch element 31 is turned on, a current flows from the reverse voltage DC voltage source 11 to the charging inductance 32, and magnetic energy is accumulated in the charging inductance 32. Next, the charging control circuit 40 turns off the overdrive charging switch element 31. When the overdrive charging switch element 31 is turned off, the charging inductance 32 and the commutation diode 33 are connected in series to the overdrive capacitor 22, and the energy accumulated in the charging inductance 32 is passed through the commutation diode 33. The overdrive capacitor 22 is charged.

  The accumulation of energy performed by the charging inductance 32 and the charging of the accumulated energy to the overdrive capacitor 22 are performed by repeatedly turning on and off the overdrive charging switch element 31. Switching control of the overdrive charging switch element 31 is continued until the overdrive capacitor 22 reaches a predetermined voltage. In this manner, the charging switch 33 can efficiently charge the overdrive capacitor 22 by interlocking with the charging control circuit 40.

  As shown in FIG. 2, the overdrive capacitor charger 21 uses the reverse voltage of the reverse voltage DC voltage source 11 as an input voltage. That is, the reverse voltage DC voltage source 11 not only applies a DC reverse voltage for extinguishing the abnormal discharge to the vacuum load 12 but also serves to charge the overdrive capacitor 22. This eliminates the need for a separate power source for charging the overdrive capacitor 22.

FIG. 3 shows the operation of the vacuum load power source according to the first embodiment of the present invention. 3A shows a change in voltage actually applied to the vacuum load 12, FIG. 3B shows a change in current flowing in the vacuum load 12, and FIG. FIG. 3D shows a gate signal of the switch element 20. FIG. t ₁ at the time of previous normal operation, occurs normal negative plasma voltage _{V p} is the vacuum load 12 (FIG. 3 (a)), flows normal plasma current _{I p} (Figure 3 (b)). Here, the plasma current is a current in the vacuum load 12 in a plasma state. The voltage at the connection point of the switching element 20 and the overdrive capacitor 22 is set to a voltage value of the sum of the charge voltage V _c of the DC reverse voltage V _b and the overdrive capacitor 22 of the reverse-voltage DC voltage source 11 V _b + V _c (FIG. 3C).

(When abnormal discharge occurs)
Hereinafter, the operation when an abnormal discharge occurs in the vacuum load power source according to the first embodiment of the present invention will be described with reference to FIG. When abnormal discharge time point t ₁ is generated, the voltage of the vacuum load 12 is lowered to the abnormal discharge voltage _{V a} (Figure 3 (a)). The control circuit 42 that has detected the abnormal discharge supplies a gate signal to the switch element 20 to turn on the switch element 20 (FIG. 3D). When the switch element 20 is turned on, the voltage value V _b + V _c of the sum of the DC reverse voltage V _b from the reverse voltage DC voltage source 11 and the charging voltage V _c of the overdrive capacitor 22 is output to the abnormal discharge arc extinguishing circuit 24. Occurs (FIG. 3C). This sum voltage value V _b + V _c is applied to the vacuum load 12 through the impedance 50 of the cable. At this time, the voltage difference between the sum voltage value V _b + V _c and the abnormal discharge voltage V _a is added to the cable impedance 50, and the current flowing through the cable impedance 50 is reduced (FIG. 3B). Current vacuum load 12 is reduced and becomes zero at t ₂ time, the abnormal discharge is extinguished.

When the discharge from the overdrive capacitor 22 is completed (t ₂ point in FIG. 3), only the DC reverse voltage V _b from reverse voltage the DC voltage source 11 is a few .mu.s (time t ₃ from t ₂ point in FIG. 3) Applied through the bypass diode 23. Abnormal discharge extinction time (t ₂ time from time point t ₁ in FIG. 3), although the reverse voltage higher shortens larger applied, abnormal discharge from t ₂ time after disappearance t to ₃ times, a high DC reverse voltage long If the voltage is continuously applied over a period of time, abnormal discharge is regenerated. In the present embodiment, at the initial stage of abnormal discharge, the DC reverse voltage is a voltage value V _b + V _c which is the sum of the DC reverse voltage V _b from the reverse voltage DC voltage source 11 and the charging voltage V _c of the overdrive capacitor 22. the case, the charge voltage V _c of the overdrive capacitor 22 at the end of the abnormal discharge is zero. Accordingly, at t ₃ time from t ₂ time, because they are not DC reverse voltage only only applied from the reverse-voltage DC voltage source 11, abnormal discharge in the vacuum load 12 is neutralized tends atmosphere occurs, abnormal discharge reoccurrence Can be suppressed.

After t ₃ , the switch element 20 is turned off by the control circuit 42, the abnormal discharge arc extinguishing circuit 24 is disconnected from the vacuum load 12, and the DC voltage of the DC power supply 10 is applied to the vacuum load 12. At this time, the voltage value applied to the vacuum load 12 is the value of the DC voltage from the DC power supply 10. The overdrive capacitor 22 is charged again to the set voltage by the overdrive capacitor charger 21 to prepare for the opportunity to extinguish the next abnormal discharge.

The capacity of the overdrive capacitor 22 may be a capacity that can discharge 100% of the total charge amount before the abnormal discharge is extinguished and the output current is cut off. By adjusting the capacity of the overdrive capacitor 22 in this manner, the reverse DC voltage is not continuously applied to the vacuum load 12 over a long period of time, so that the possibility of reoccurrence of abnormal discharge can be suppressed. . In Figure 3, the abnormal discharge is charging voltage V _c of the overdrive capacitor 22 at time t ₂ being extinguishing is zero, the time when the charging voltage V _c of the overdrive capacitor 22 becomes zero, It may be before or after the time _{t 2.}

  By making the DC reverse voltage due to the discharge from the overdrive capacitor 22 variable according to the output current or the output power, the output current or the output power of the abnormal discharge can be cut off more efficiently. For example, the plasma injection set power of the DC power supply 10 or the output current, that is, a voltage proportional to the plasma current can be used. Here, the plasma injection setting power is an output setting when the DC power source is operated by constant power control. Note that the value of the DC reverse voltage to be applied can extinguish the abnormal discharge with, for example, a value of about 20% of the DC voltage applied from the DC power supply 10 to the vacuum load 12.

  Here, as a condition for the control circuit 42 to detect abnormal discharge, a case where the voltage drop rate of the output voltage from the vacuum load 12 exceeds a predetermined value is considered. For example, this is a case where the fluctuation range of the DC voltage applied to the vacuum load 12 is 100 V / μs or more. Another possible condition is that the output voltage drops below a predetermined value. For example, the DC voltage applied to the vacuum load 12 may be considered when the output voltage drops from the normal voltage 400V to 50V or less. Another possible condition is that the output current value exceeds a predetermined value. For example, this is a case where the value of the output current applied to the vacuum load 12 becomes 1.1 times or more of the rating. In any case, it is appropriate to set according to the usage environment of the vacuum load 12.

Specific components will be described. When the output current is I, the charging voltage of the overdrive capacitor 22 is E, and the target output current convergence time, that is, the abnormal discharge extinction time is T, the capacity C of the overdrive capacitor 22 can be calculated by the following equation. it can.

  For example, if the output current I = 200 A, the target output current convergence time, that is, the abnormal discharge extinction time T = 10 μs, and the charging voltage E of the overdrive capacitor 22 is 200 V, the capacitance C of the overdrive capacitor 22 is 10 μF. Calculated.

  In this embodiment, when an abnormal discharge occurs, the DC reverse voltage from the overdrive capacitor 22 is superimposed on the DC reverse voltage from the reverse voltage DC voltage source 11 to quickly extinguish the abnormal discharge. The interruption time of the output current is shortened, and after the discharge from the overdrive capacitor 22 is completed, the occurrence of abnormal discharge can be suppressed by the DC reverse voltage from the reverse voltage DC voltage source 11.

(Second embodiment)
Hereinafter, another aspect of the present invention will be described. FIG. 4 is a diagram showing a vacuum load power source according to the second embodiment of the present invention. A DC power supply 10 that is connected in parallel to the vacuum load 12 and applies a DC voltage to the vacuum load 12, and a DC reverse voltage that is connected in parallel to the vacuum load 12 and has the opposite sign to the DC voltage of the DC power supply 10 is applied to the vacuum load 12. The abnormal discharge extinguishing circuit 24 to be applied to the control, and the control for detecting the abnormal discharge in the vacuum load 12 and controlling the DC voltage of the DC power source 10 and the DC reverse voltage of the abnormal discharge arc extinguishing circuit 24 through the switch element 20. The abnormal load arc extinguishing circuit 24 applies a DC reverse voltage having a sign opposite to that of the DC voltage applied to the vacuum load 12 from the DC power supply 10 to the vacuum load 12. The overdrive capacitor 22 and the switch element 20 that is turned on / off by the control of the control circuit 42 are connected in series. Constructed.

  The abnormal discharge extinguishing circuit 24 includes a switch element 20, an overdrive capacitor charger 21, an overdrive capacitor 22, a bypass diode 23, and a control circuit 42. The abnormal discharge extinction circuit in the first embodiment is used. The arc circuit 24 is different from the arc circuit 24 in that the reverse voltage DC voltage source 11 is not provided. In addition, the control circuit 42 according to the second embodiment detects the abnormal discharge of the vacuum load 12 and turns off the DC power supply 10 while the switch element 20 is turned on for a certain pulse time. The operation is different from the embodiment. The functions of the other components are the same as those in the first embodiment, and the description of the elements described in the first embodiment is omitted.

(Normal operation)
Hereafter, the operation | movement at the time of normal operation | movement of the power supply for vacuum loads which concerns on 2nd embodiment of this invention is demonstrated using FIG.4 and FIG.5. In FIG. 4, the DC power supply 10 applies a DC voltage to generate plasma in the vacuum load 12. The abnormal discharge arc extinguishing circuit 24 is disconnected from the vacuum load 12 by the switch element 20 until an abnormal discharge occurs and is detected by the control circuit 42. Further, in FIG. 5 (a), the time t ₁ earlier normal operation, i.e., when the switch element 20 is off, the vacuum load 12, the normal negative polarity equal to the DC voltage of the DC power supply 10 plasma voltage V _p Is applied.

  Since the switch element 20 constituting the abnormal discharge arc extinguishing circuit 24 is off, the overdrive capacitor 22 is charged by the overdrive capacitor charger 21 while being disconnected from the vacuum load 12. The power supply capacity of the overdrive capacitor charger 21 may be small if the occurrence of abnormal discharge is small. This is because when no abnormal discharge occurs, charging can be performed over time even if the power supply capacity of the overdrive capacitor charger 21 is small.

(When abnormal discharge occurs)
Hereinafter, the operation of the vacuum load power supply according to the second embodiment of the present invention when an abnormal discharge occurs will be described with reference to FIGS. 4 and 5. 5A shows the output voltage applied to the vacuum load 12, FIG. 5B shows the output current flowing through the vacuum load 12, and FIG. 5C shows the voltage at the connection point between the switch element 20 and the overdrive capacitor 22. FIG. 5D shows the gate signal of the switch element 20, respectively. When abnormal discharge time point t ₁ is generated, the voltage of the vacuum load 12 is lowered to the abnormal discharge voltage _{V a} (Figure 5 (a)). The control circuit 42 gives a gate signal to the switch element 20 (FIG. 5 (d)). In FIG. 4, the gate signal turns on the switch element 20, and simultaneously turns off the DC power supply 10 while the switch element 20 is on. When the switch element 20 is turned on, the charging voltage V _c of the overdrive capacitor 22 is generated at the output (FIG. 5C). This voltage is applied to the vacuum load 12 through the impedance 50 of the cable. At this time, the difference voltage between the charging voltage V _c of the overdrive capacitor 22 and the abnormal discharge voltage V _a is added to the cable impedance 50, and the current flowing through the cable impedance 50 is reduced. Then, the current of the vacuum load 12 decreased (FIG. 5 (b)), becomes zero at t ₂ time, the abnormal discharge is extinguished.

When the discharge from the overdrive capacitor 22 is completed (t ₂ point in FIG. 5), several tens of .mu.s, the value of the DC reverse voltage applied to the vacuum load 12 is zero (t from t ₂ point in FIG. 5 ₃ time). From t ₂ time after the abnormal discharge extinction until t ₃ point, continuing to apply for a long time continued high DC reverse voltage, lead to the re-generating an abnormal discharge. However, in the present embodiment, even after the discharge from the overdrive capacitor 22 has abnormal discharge extinguishing complete finished, the output of the DC power source 10 from the left to (t ₂ point in FIG off t ₃ time points), it is possible to suppress the re-occurrence of abnormal discharge.

After t ₃ , the switch element 20 is turned off by the control circuit 42, and the abnormal discharge arc extinguishing circuit 24 is disconnected from the vacuum load 12. At the same time, the DC power supply 10 is turned on and a DC voltage is applied to the vacuum load 12. At this time, the voltage value applied to the vacuum load 12 is the value of the DC voltage from the DC power supply 10. The overdrive capacitor 22 is charged by the overdrive capacitor charger 21 to prepare for the opportunity to extinguish the next abnormal discharge.

  The overdrive capacitor 22 can apply a DC reverse voltage to the vacuum load 12 by discharging the charged charge. In this embodiment, when the abnormal discharge occurs, the DC power supply 10 is turned off, so that only the discharge from the overdrive capacitor 22 is performed and the DC reverse voltage is evacuated without the need for the separate reverse voltage DC voltage source 11. It can be applied to the load 12. Note that the abnormal discharge can be extinguished even when the value of the DC reverse voltage applied is, for example, about 20% of the DC voltage applied from the DC power supply 10 to the vacuum load 12. Further, in the present embodiment, the DC power source 10 and the vacuum load 12 in FIG. 1 are not required because the DC power source 10 is turned off while the reverse voltage DC voltage source 11 is not required and the switch element 20 is turned on. The current limiting inductance 30 for limiting the current is not required.

The capacity of the overdrive capacitor 22 may be a capacity that can discharge 100% of the total charge amount before the abnormal discharge is extinguished and the output current is cut off. Here, the voltage value of the overdrive capacitor 22 is gradually lowered by discharge from time point t _1, the discharge is completed at t ₂ time. Therefore, the voltage applied to the vacuum load 12 becomes zero. By adjusting the capacity of the overdrive capacitor 22 in this manner, the reverse DC voltage is not continuously applied to the vacuum load 12 over a long period of time, so that the possibility of reoccurrence of abnormal discharge can be suppressed. . The capacity of the overdrive capacitor 22 is set by values such as output current, output cable inductance 50, abnormal discharge extinction time, and the like, and can be calculated by the same method as in the first embodiment.

  Similar to the first embodiment, the DC reverse voltage due to the discharge from the overdrive capacitor 22 is made variable according to the output current or output power, so that the output current or output power of abnormal discharge can be more efficiently increased. Can be blocked. For example, the voltage may be proportional to the plasma injection setting power of the DC power supply 10.

  Here, as a condition for the control circuit 42 to detect abnormal discharge, a case where the voltage drop rate of the output voltage from the vacuum load 12 exceeds a predetermined value is considered. For example, this is a case where the fluctuation range of the DC voltage applied to the vacuum load 12 is 100 V / μs or more. Another possible condition is that the output voltage drops below a predetermined value. For example, the DC voltage applied to the vacuum load 12 may be considered when the output voltage drops from the normal voltage 400V to 50V or less. Another possible condition is that the output current value exceeds a predetermined value. For example, this is a case where the value of the output current applied to the vacuum load 12 becomes 1.1 times or more of the rating. In any case, it is appropriate to set according to the usage environment of the vacuum load 12.

  In this embodiment, when an abnormal discharge occurs, the DC power supply 10 is turned off and the DC reverse voltage from the overdrive capacitor 22 is discharged, so that the abnormal discharge is extinguished quickly and the output current is cut off. After the discharge from the overdrive capacitor 22 is completed, the occurrence of abnormal discharge can be suppressed by keeping the DC power supply 10 off. Further, in order to ensure the charging time of the overdrive capacitor 22, the configuration is suitable when the switch element 20 has a long on / off interval, that is, when there is little chance of extinguishing the abnormal discharge.

  The power source for vacuum load of the present invention can be applied to, for example, a sputtering apparatus, an etching apparatus, an electron beam evaporation apparatus, a PVD apparatus, a CVD apparatus, etc. that process or process using plasma generated in a vacuum.

10: DC power supply 11: Reverse voltage DC voltage source 12: Vacuum load 20: Switch element 21: Overdrive capacitor charger 22: Overdrive capacitor 23: Bypass diode 24: Abnormal discharge arc extinguishing circuit 30: Current limiting Inductance 31: Overdrive charging switch element 32: Charging inductance 33: Commutation diode 40: Charging control circuit 42: Control circuit 50: Cable inductance

Claims (5)

A DC power source connected in parallel to the vacuum load and applying a DC voltage to the vacuum load;
An abnormal discharge arc extinguishing circuit that is connected in parallel to the vacuum load and applies a DC reverse voltage having a sign opposite to that of the DC voltage of the DC power supply to the vacuum load;
A control circuit for detecting an abnormal discharge in the vacuum load and controlling a DC reverse voltage of the circuit for extinguishing the abnormal discharge;
A vacuum load power source comprising:
The abnormal discharge arc extinguishing circuit is:
An inductance connected in series between the DC power source and the vacuum load;
A reverse voltage DC voltage source that applies a DC reverse voltage having a sign opposite to that of the DC voltage applied to the vacuum load from the DC power source;
A capacitor for overdrive for applying a DC reverse voltage having the same sign as the DC reverse voltage from the reverse voltage DC voltage source to the vacuum load;
A switching element that is turned on and off by the control of the control circuit, the DC reverse voltage applied from the reverse voltage DC voltage source and the overdrive capacitor;
A power source for a vacuum load, characterized by being connected in series. Energy from a commutation diode that prevents reverse charging, an overdrive charging switch element that is turned on / off by the control of the charging control circuit, and the reverse voltage DC voltage source are accumulated, and the accumulated energy is stored in the overdrive capacitor. Having charging inductance to charge,
The anode side of the commutation diode is connected to one end of the overdrive charging switch element and one end of the charging inductance,
The cathode side of the commutation diode is at the connection point between the switching element and the overdrive capacitor, and the other end of the charging inductance is at the connection point between the overdrive capacitor and the reverse voltage DC voltage source. 2. The overdrive capacitor charger according to claim 1, further comprising an overdrive capacitor charger in which the other end of the drive charging switch element is connected to a connection point between the reverse voltage DC voltage source and the DC power source. Power supply for vacuum load. A DC power source connected in parallel to the vacuum load and applying a DC voltage to the vacuum load;
An abnormal discharge arc extinguishing circuit that is connected in parallel to the vacuum load and applies a DC reverse voltage having a sign opposite to that of the DC voltage of the DC power supply to the vacuum load;
A control circuit for detecting an abnormal discharge in the vacuum load and controlling a DC voltage of the DC power source and a DC reverse voltage of the circuit for extinguishing the abnormal discharge;
A vacuum load power source comprising:
The abnormal discharge arc extinguishing circuit is:
A capacitor for overdrive that applies a DC reverse voltage having a sign opposite to that of the DC voltage applied to the vacuum load from the DC power supply;
A switching element that is turned on / off by the control of the control circuit, the DC reverse voltage applied from the overdrive capacitor;
A power source for a vacuum load, characterized by being connected in series.   The power supply for a vacuum load according to any one of claims 1 to 3, wherein the overdrive capacitor has a capacity for discharging all the charged charges while the switch element is on.   2. The control circuit according to claim 1, wherein the control circuit is a control circuit that detects that a voltage fluctuation in the vacuum load is a predetermined value or more and controls a DC reverse voltage of the abnormal discharge arc extinguishing circuit. 5. The power source for vacuum load according to any one of 4.

Images