JP4805205B2 - Power supply for discharge load - Google Patents

Description

  The present invention relates to a discharge load suitable for supplying a trigger voltage higher than a rated plasma voltage and then a rated plasma discharge power to a discharge load such as a sputtering apparatus for forming a thin film in a manufacturing process of a semiconductor device or the like. Regarding power supply.

  As a discharge load using plasma discharge energy, sputtering devices for forming thin films such as semiconductor devices or optical disks, various lasers, discharge lamps, strobe devices, electric discharge machining devices, fusion splicing devices for optical fibers, or plasma arcs or plasmas There are welding devices that use jets, and discharge loads are used in a very wide range of fields. The discharge is generated in a vacuum, a specific gas such as an inert gas, or in the atmosphere. When a discharge is generated, a high DC voltage or a high-frequency voltage is applied to an ignition (ignition or ignition) voltage (ignition or ignition). In the following, it is referred to as a trigger voltage) and must be applied between the discharge electrodes of the discharge load. The trigger power is smaller than the rated plasma discharge power such as glow discharge or arc discharge. However, when the trigger voltage is a DC voltage, it must be considerably higher than the voltage in the rated plasma discharge state, for example, 1-1. .5 kV. However, once rated plasma discharge occurs between the discharge electrodes, the rated plasma discharge (hereinafter referred to as rated discharge) is lower than the trigger voltage for generating partial plasma discharge (hereinafter referred to as trigger discharge). ) Is maintained, it is only necessary to supply electric power that allows a discharge current of a necessary magnitude to flow.

  Various power sources for discharge loads that supply power suitable for such discharge loads have already been proposed. For example, a two-power-source type that includes a trigger power source that generates a high trigger voltage when a trigger discharge occurs and a main discharge power source that supplies power corresponding to the rated discharge power (see, for example, Patent Documents 1 and 2), Or the thing of the 1 power supply system which supplies trigger discharge electric power and rated discharge electric power with one power supply (for example, refer patent document 3, 4) is disclosed. The above-mentioned Patent Document 1 discloses a thin film forming apparatus having a trigger power source and a main discharge power source. The trigger discharge is generated in a vacuum atmosphere by a trigger voltage from the trigger power source, and the main discharge power source is a rated discharge. The arc discharge is maintained to form a thin film. Patent Document 2 listed above discloses a plasma processing apparatus using a plasma arc, and at the time of arc generation, a pilot arc corresponding to trigger discharge is generated by combining a DC power source for pilot arc and a DC high voltage power source, Next, power is supplied from the main power source to generate a plasma arc corresponding to the rated discharge.

In the above-mentioned Patent Document 3, a single power source is configured to simplify the power source, and an auxiliary winding is provided in addition to the main secondary winding on the secondary side of the transformer, and a trigger voltage is applied to the auxiliary winding. Is connected to the ignition circuit. Patent Document 4 described above is a further simplification of the power supply configuration disclosed in Patent Document 3, and can generate a high trigger voltage simply by adding a capacitor to the output side rectifier circuit. In addition to these, a large number of single power source discharge power sources have been disclosed. As with the two power source discharge power sources described above, a trigger voltage is applied when a trigger discharge occurs, and a part of the power source is placed in the vacuum chamber. In addition to forming a typical discharge path, discharge power is supplied to generate a rated discharge, and the rated discharge is maintained.
JP 09-165673 A JP-A-11-254144 JP 2001-095242 A JP 2005-033968 A JP 2006-202605 A

  The rated discharge power amount of the discharge load currently in practical use is overwhelmingly 1 kW or more, and in the case of such a large discharge power, regardless of the one power source method or the two power source method described above, The discharge power source can easily generate and maintain a rated discharge. However, various strict requirements may be imposed on the processing conditions as the parts progress, and as one of them, for example, the rated discharge power is significantly smaller than the conventional one, for example, with a small rated discharge power of 10 W to 100 W, for example. Processing such as forming a desired thin film may be required. For example, when the discharge load is a vacuum chamber of a sputtering apparatus, the atmosphere in the vacuum chamber changes depending on the vacuum state or gas flow rate, and the trigger voltage or plasma sustaining voltage varies depending on the type of target and the amount of power injected. Different. In such a state, in order to uniformly form a very thin film with a short sputtering time, if the plasma state is not uniform and stable in each short sputtering time, the quality is stable and uniform. It is difficult to form a thin film. In order to stably generate and maintain a rated discharge in a small rated discharge power region of, for example, several tens of watts or less in the state of the vacuum chamber as described above, it is necessary to smoothly shift from the trigger discharge to the rated discharge. Difficult depending on the discharge load. This is particularly difficult when the trigger current is limited to a small value.

  The above-mentioned Patent Documents 1 to 4 and the like are intended for discharge loads with a large power such as 1 kW or more during rated discharge, and do not describe discharge loads with a rated discharge power of several tens of watts or less. Even if the power source or processing method for a discharge load disclosed in Patent Literature 1 to Patent Literature 4 is combined with the power supply method that merely gradually increases current at the time of startup disclosed in Patent Literature 5 described above, It is difficult to form a desired thin film with a discharge load of steady discharge power of W or less. The power supply method disclosed in Patent Document 5 is a soft start power supply method in which when the plasma jet torch is triggered (ignited), the power is gradually increased and supplied.

  The present invention can reliably and stably reach the rated discharge from the trigger discharge without adversely affecting the formation of the thin film even in a discharge load in the low rated power region where the rated discharge power is several tens W or less. The main purpose is to provide a power supply for a discharge load.

  According to a first aspect of the present invention, there is provided a discharge load power source for supplying power to the discharge load, the first inverter circuit, a first transformer having a primary winding connected to the output side of the first inverter circuit, An output-side rectifier circuit connected between the secondary winding of the first transformer and a DC output terminal to which the discharge load is connected; an output capacitor connected between the DC terminals of the output-side rectifier circuit; A main power source comprising a separation diode connected in series between one output terminal of the output side rectifier circuit and one of the DC output terminals, a second inverter circuit, and a second inverter circuit thereof A DC high voltage generating circuit connected to the output side of the DC high voltage generating circuit, connected between the high voltage output terminal of the DC high voltage generating circuit and the DC output terminal, and when the discharge load is triggered, Before voltage generator A trigger power source including a current limiting impedance that suppresses a current flowing through the discharge load to a limit value or less; and a control circuit that controls the first inverter circuit and the second inverter circuit; When the discharge load is triggered by the high-voltage output of the trigger power supply when the charge charged in the output capacitor by the output current of the output-side rectifier circuit is activated during the period when the separation diode is non-conductive A discharge load power supply characterized in that the separation diode is forward-biased and discharged to conduct, and the discharge current is superimposed on the output current from the output-side rectifier circuit and flows to the discharge load. To do.

  According to a second invention, in the first invention, the control circuit starts up the second inverter circuit first, and then starts up the first inverter circuit when the discharge load is triggered. Provided is a discharge load power source.

  In a third aspect based on the first aspect or the second aspect, the control circuit starts up the first inverter circuit with an initial control signal having a predetermined pulse width, and then the initial control signal Provided is a power supply for a discharge load, which is driven by a control signal having a pulse width that gradually increases from a minimum pulse width smaller than the pulse width of the control signal after being driven by a control signal having a smaller pulse width. .

  In a fourth aspect based on the first aspect, the control circuit activates the second inverter circuit and activates the first inverter circuit before the discharge load is triggered. A discharge load power supply is provided, wherein the first inverter circuit is controlled so as to charge the output capacitor to a set voltage (a voltage not higher than a plasma sustaining voltage) until a load is triggered.

  According to a fifth aspect of the present invention based on the fourth aspect, the control circuit has a control signal having a pulse width that gradually increases from a certain minimum pulse width from when the first inverter circuit starts up to a rated discharge state. A power supply for a discharge load is provided which starts the first inverter circuit.

  According to a sixth invention, in any one of the first to fifth inventions, the control circuit uses the trigger circuit when the output power of the main power source exceeds 80% of a set power. Disclosed is a discharge load power supply characterized by stopping power supply.

  In a seventh aspect based on any one of the first aspect to the sixth aspect, the control circuit includes a low potential side terminal of the DC high voltage generation circuit and a grounded side of the output side rectifier circuit. There is provided a light source for a discharge load that includes a light emitting element connected to a direct current terminal of the light source and detects that the discharge load is triggered by lighting of the light emitting element.

  According to an eighth invention, in any one of the first invention to the seventh invention, the trigger power supply includes a backflow prevention diode connected in series with the current limiting impedance. Provide a power supply for a discharge load.

  A ninth invention is characterized in that, in any one of the first to eighth inventions, the current limiting impedance has a resistance value for limiting the trigger current to several percent or less of the rated discharge current. A power supply for a discharge load is provided.

  According to the first aspect of the invention, when the main power source is activated and the charge charged in the output capacitor during the period when the separation diode is non-conductive is triggered by the high voltage output of the trigger power source. The separation diode is forward-biased and discharged by conduction, and the discharge current is superimposed on the output current from the output-side rectifier circuit and flows to the discharge load. Therefore, it is possible to reliably and stably maintain the trigger discharge and shift to the rated discharge without adversely affecting the quality, and to form a high-quality thin film with a low-power plasma discharge. Also, in the present invention, by selecting a large current limiting impedance, the inrush current that flows during trigger discharge can be limited to a few tenths of the rated current, which further reduces the adverse effect on the discharge load. This makes it possible to produce high-quality thin films and to reduce the capacity of the trigger power supply.

  According to the second invention, in addition to the effect of the first invention, the first inverter circuit is started when the discharge load is triggered, so that the current limiting resistor having a large resistance value is not provided. The inrush current can be prevented by controlling the first inverter circuit, and the power loss of the main power source can be reduced without causing a large operation delay due to the operation switching.

  According to the third aspect of the invention, in addition to the effects of the second aspect of the invention, the first control signal has a pulse width that gradually increases from a certain pulse width at the initial start of the first inverter circuit of the main power supply. The inverter circuit is activated and driven by a control signal having a pulse width that gradually increases from a pulse width that is smaller than the pulse width after a certain period of time has elapsed. The discharge can be stably transferred to the rated discharge, and a uniform thin film can be formed with a low power plasma discharge.

  According to the fourth and fifth aspects of the invention, in addition to the effects of the first aspect, the first inverter of the main power supply before the discharge load is triggered by the high voltage output of the trigger power supply The first inverter circuit is controlled to start the circuit and charge the output capacitor to the set voltage (voltage below the plasma sustain voltage) until the discharge load is triggered. Because the inverter circuit is controlled at constant power, it can be transferred to the rated discharge more reliably and stably with a simple control method without adversely affecting the formation of thin film, and high quality with low power plasma discharge. Enables the formation of thin films. Further, it is possible to prevent an inrush current from flowing when the main power supply is started without adversely affecting the occurrence of trigger discharge.

  According to the sixth invention, in addition to the effects of the first to fifth inventions, the trigger power supply is stopped at any time when the output power of the main power exceeds 80% of the set power. Therefore, the power loss of the trigger power source can be reduced.

  According to the seventh invention, in addition to the effects obtained in the first to sixth inventions, the control circuit is provided between the high potential side terminal of the DC high voltage generating circuit and the DC terminal grounded by the rectifier. Since it is detected that the discharge load is triggered by the lighting of the light emitting element, the trigger detection unit of the control circuit can be simplified and can be detected at high speed.

  According to the eighth invention, in addition to the effects obtained in the first to seventh inventions, the diode prevents backflow even when a large noise occurs in the high voltage output of the trigger power supply. Therefore, the discharge load and the main power source are not adversely affected.

  According to the ninth aspect, in addition to the effects obtained in the first to eighth aspects, the current limiting impedance has a resistance value that limits the trigger current to several percent or less of the rated discharge current. Since it is selected, the output capacity of the trigger power supply can be reduced, and the trigger power supply can be made smaller and lighter.

[Embodiment 1]
First, a power supply 100 for a discharge load according to Embodiment 1 of the present invention will be described with reference to FIG. The discharge load power source 100 will be described with reference to FIG. The main power supply MS mainly supplies constant power to the discharge load DL after the discharge load DL as described above is ignited or ignited, that is, triggered (ignition), and the trigger power supply TS A high trigger voltage is supplied to trigger and reach a trigger discharge state.

(Main power MS)
First, the main power source MS will be described. The first inverter circuit 3 is connected to the DC input terminals 1 and 2, and the primary winding 4 </ b> A of the transformer 4 is connected to the output side of the first inverter circuit 3. An output side rectifier circuit 5 is connected to the secondary winding 4B. In most cases, the discharge load power source 100 is connected to a commercial three-phase AC power source or a single-phase AC power source. In this case, the commercial three-phase AC power or the single-phase AC power is converted into DC power (not shown). An input side rectifier circuit and a smoothing circuit are connected to the DC input terminals 1 and 2. The first inverter circuit 3 converts the DC voltage into a high-frequency AC voltage of 20 kHz or more, for example, 40 kHz.

  The inverter circuit 3 is a switching semiconductor element such as a MOSFET or IGBT having a well-known full-bridge configuration or a half-bridge configuration. The inverter circuit 3 is subjected to pulse width control (on-time ratio control) by the control circuit CC, and direct current power Is converted into single-phase high-frequency power. The transformer 4 reduced in size by the high-frequency switching operation of the inverter circuit 3 has a high-frequency AC voltage obtained by boosting the high-frequency AC voltage applied from the inverter circuit 3 to the primary winding 4A with a predetermined transformation ratio. To occur. The AC voltage of the secondary winding 4B is converted into a DC voltage by an output side rectifier circuit 5 in which four or four sets of rectifying elements connected in parallel are connected to a bridge, and the DC voltage is smoothed by an output capacitor 6. It becomes. The output capacitor 6 is charged with the illustrated polarity.

  Between the output capacitor 6 and the DC output terminals 7 and 8, there is an output side resistor 9 for limiting the output current of the main power source MS, and a separation for separating the main power source MS from the high voltage output of the trigger power source TS. A current detecting means 13 such as a diode 10, a voltage dividing resistor 11 and a voltage detecting resistor 12 constituting a load voltage detector, and a small resistor for detecting an output current of the main power source MS is connected. . Since the resistors 11 and 12 are directly connected across the DC output terminals 7 and 8 without going through the separation diode 10, the resistors 11 and 12 detect the load voltage at the DC output terminals 7 and 8. One DC output terminal 8 is grounded, and therefore the other DC output terminal 7 has a negative potential. The main power source MS is constituted by the members 3 to 13. The discharge load DL connected between the DC output terminals 7 and 8 is a vacuum chamber of a sputtering device for forming a thin film, various laser devices, a discharge lamp, a strobe device, an electric discharge machining device, an optical fiber by heat of discharge. These devices are usually supplied with power under constant power control or constant current control.

(Trigger power TS)
The input of the second inverter circuit 21 of the trigger power source TS is connected to the DC input terminals 1 and 2, and its output terminal is connected to the primary winding 22 </ b> A of the transformer 22. The second inverter circuit 21 has a circuit configuration similar to that of the first inverter circuit 3 of the main power supply MS, is driven by a high frequency, for example, 50 kHz pulse width control signal, and converts DC power into high frequency AC power. . The high-frequency AC power is converted into a DC high voltage by the booster circuit 23 through the secondary winding 22B of the transformer 22. The booster circuit 23 is a general one, for example, a voltage doubler rectifier circuit having a simple configuration, and a DC high voltage at which the output terminal 24 is negative with respect to the output terminal 25, for example, -1200 to -1500V. Outputs the load voltage. The transformer 22 and the booster circuit 23 constitute a direct current high voltage generation circuit, but this is an example, and another circuit configuration in which a high voltage transformer and a high voltage rectifier (not shown) are combined may be used. Note that neither of these output terminals 24 and 25 is grounded.

  A high voltage dividing resistor 26 and a voltage detecting resistor 27 constituting a voltage detector for detecting the output voltage of the booster circuit 23 are connected between the output terminals 24 and 25. The output terminal 24 is connected to the DC output terminal 7 through a current limiting impedance 28 and a backflow prevention diode 29. The current limiting impedance 28 used in the first embodiment is much larger than the current flowing when the discharge load DL reaches the trigger discharge state (initial discharge state) when the discharge load DL is in the rated discharge state. It has a large resistance that can be limited to a small current. By selecting the resistance value in this way, the power capacity of the trigger power source TS can be reduced, and the trigger power source TS can be reduced in size. Can prevent such damage.

  In other words, in a sputtering apparatus or the like, when the discharge load DL is triggered, discharge breakdown usually occurs in a narrow spot-like region of a part of the target, and the trigger current flows concentratedly in the narrow spot-like region. Since the current density increases, it is meaningful for the discharge load DL to limit the trigger current to be significantly smaller than the rated discharge current at the rated discharge (for example, a current value of 0.5 to 3% of the rated discharge current). is there. However, especially in the case of low power, it is difficult to maintain the trigger discharge state and shift to the rated discharge state. However, as will be described later, by appropriately adjusting the initial current of the main power source MS, the discharge load DL It is possible to stably shift to the rated discharge state without adversely affecting the battery. The present invention is particularly effective when the trigger current is limited to such a small value.

(Control circuit CC)
A control circuit CC that drives and controls the operation of the inverter circuit 3 of the main power supply MS and the inverter circuit 21 of the trigger power supply TS includes a control unit 31 that controls the inverter circuit 3 and the inverter circuit 21, signal input lines 32 and 33, 34, 35, signal output lines 36, 37, and the like. The control unit 31 will be described in detail when the operation is described later. In the first embodiment, the control circuit 31 controls the inverter circuit 3 of the main power source MS in the period from the start-up to the rated discharge state, for example, in the power control mode. First, start with the initial control signal with a relatively large pulse width set first, then drive with a control signal with a pulse width that gradually becomes narrower than the pulse width of the initial control signal for the next short period, and then set The inverter circuit 3 of the main power supply MS has a circuit portion for controlling the pulse width so that the switching operation is performed with a control signal having a pulse width that gradually increases from the minimum width. In order to perform this control, the control unit 31 includes a pulse width control portion related to the above-described control shown in FIG.

  The configuration of the pulse width control portion will be described with reference to FIG. 2. The load voltage detection signal Vo at the voltage detection point A and the load current detection signal Io at the current detection point B in FIG. A power detection signal Wo corresponding to the multiplied value is input, and a power setting signal S3 that changes with a preset curve or a constant slope is input to the terminal 31b. A start signal S4 is input to the terminal 31c when starting up the inverter circuit 3 of the main power source MS, and a pulse width control signal S5 corresponding to the control signal S1 shown in FIG. 1 is output from the terminal 31d. The control signal S1 is input to the inverter circuit 3. The control amplifier 31e indicated by the broken line calculates the power detection signal Wo and the power setting signal S3 and outputs a signal S6. The switch element 31f is closed when the start signal S4 is not applied and the terminal 31b is grounded, and is opened when the start signal S4 is applied so that the power setting signal S3 of the terminal 31b is input to the control amplifier 31e. To work.

  Similarly to the switch element 31f, the switch element 31g is closed when the start signal S4 is not applied, and is opened when the start signal S4 is applied. Since the switch element 31f and the switch element 31g are closed until the start signal S4 is applied, the control amplifier 31e does not operate. When the start signal S4 is applied to open the switch element 31f and the switch element 31g, the control amplifier 31e effectively operates. Resistors 31h and 31i provided on the output side of the control amplifier 31e generate a voltage signal Va obtained by dividing the voltage Vx at their connection point X. The resistor 31i acts as an initial value setting means, and the resistance value is selected so as to set the initial value Va 'of the voltage signal Va at the connection point X to a predetermined value. The comparator 31j compares the voltage signal Va with a predetermined triangular wave signal S7 and generates a control signal S5 'having a pulse width equal to the width between the points intersecting each other. Only when receiving the start signal S4, the AND circuit 31k passes the control signal S5 'and causes the pulse width control signal S5 to appear at the terminal 31d.

  Returning to FIG. 1, the signal input line 32 is connected to a voltage detection point A between the resistors 11 and 12, and a load voltage detection signal Vo proportional to the voltage between the DC output terminals 7 and 8 is supplied. Input to the control unit 31. The signal input line 33 is connected to a current detection point B between the positive output terminal of the output-side rectifier circuit 5 and the current detection means 13, and receives a current detection signal I1 proportional to the output current of the main power source MS. Input to the control unit 31. The input signal line 34 is connected to a voltage detection point C between the high voltage dividing resistor 26 and the voltage detection resistor 27 that are connected in series with each other, and is connected to the output terminals 24 and 25 of the booster circuit 23. A voltage detection signal V2 proportional to the DC high voltage is input to the control unit 31. The input signal line 35 detects the current flowing from the terminal 25 of the booster circuit 23 to the current detection point B, that is, the trigger discharge current detection signal I2 proportional to the trigger current, and inputs it to the control unit 31. The line 35 is connected to simple current detection means 38 that constitutes a part of the control unit 31. In the first embodiment, a commercially available photocoupler is used as the trigger detection means 38. A light emitting element 38A of the photocoupler is connected to the input signal line 35, and a light receiving element 38B that converts light emitted from the light emitting element 38A into an electric signal is provided. It is connected to the control unit 31.

  In the first embodiment, the output terminal 25 is in a floating potential state. Therefore, when the discharge load DL is triggered by the triggering DC high voltage between the output terminals 24 and 25 of the booster circuit 23, the output is output. A current of about several milliamperes flows from the terminal 25 to the current detection point B through the light receiving element 38B, causes the light emitting element 38A to emit light, and the light receiving element 38B receives the light to detect that the discharge load DL has been triggered. That is, it is detected whether or not the discharge load DL is triggered with a very simple circuit configuration in which a photocoupler is connected between the output terminal 25 of the trigger power supply TS and the current detection point B of the main power supply MS. be able to.

(Description of operation)
Next, the operation of the discharge load power supply 100 according to the first embodiment will be described with reference to FIGS. 1 to 4. 3, (A) and (B) show a voltage detection signal V2 indicating the output voltage of the trigger power supply TS and a trigger discharge current detection signal I2 indicating the output current, respectively. (C) and (D) are the main signals. An output voltage detection signal V1 indicating the output voltage of the power supply MS and an output current detection signal I1 indicating the output current are respectively shown. (E) and (F) are load voltage detection signals indicating the load voltage and the load current of the discharge load DL, respectively. Vo and load current detection signal Io are shown respectively. FIG. 4 is a diagram for explaining the pulse width at the time of soft start of the control signal S1 supplied to the inverter circuit 3 of the main power source MS.

  The control unit 31 of the control circuit CC first drives the inverter circuit 21 of the trigger power supply TS with a pulse width control signal S2 of high frequency, for example, 50 kHz, at time t1. This driving is performed by a soft start in which the pulse width gradually increases in a constant voltage control mode in which the output voltage is controlled to be kept constant. This soft start method is the same as that described with reference to FIG. 2, and it is widely known that the pulse width control signal is gradually increased by comparing the triangular wave signal with a signal having a predetermined slope. The details will not be described. Therefore, the output voltage of the trigger power supply TS rises with a certain slope as shown in FIG. When the output voltage of the inverter circuit 21 reaches the set voltage at time t2, the control unit 31 drives the inverter circuit 21 with the control signal S2 having the set pulse width, so that the output voltage of the trigger power supply TS is substantially until time t3. It is at a constant high voltage. Here, the set voltage means, for example, a voltage selected in advance that is lower than the voltage during the sputtering when the discharge load DL is triggered.

  The high frequency output voltage of the inverter circuit 21 is converted into a high negative DC voltage by a DC high voltage generating circuit including a transformer 22 and a booster circuit 23. The negative DC high voltage at the output terminal 24 is applied to the DC output terminal 7 through the current limiting impedance 28 and the reverse current blocking diode. Therefore, even if the current limiting impedance 28 has a large resistance value (100 kΩ or more, for example, 120 kΩ), no current flows before the discharge load DL is triggered. A DC high voltage (for example, −1200 V) is applied as it is, and the discharge load DL is triggered at time t3. Even after the discharge load DL is triggered, the trigger power source TS operates at least until the rated discharge is stably and reliably maintained to supply current to the discharge load DL.

  When the discharge load DL is triggered at time t3, a trigger discharge current I2 as shown in FIG. 3B is generated from the DC output terminal 8 to the discharge load DL, the DC output terminal 7, the backflow prevention diode 29, and the current limiting impedance. 28, the output terminal 24, the booster circuit 23, the output terminal 25, the signal line 35, the light emitting element 38A of the photocoupler, the current detection point B, and the current detection means 13. Therefore, when the light emitting element 38A emits light and the light receiving element 38B converts into an electric signal, the trigger detecting means 38 detects that the discharge load DL is triggered. When the discharge load DL is triggered, the load voltage at both ends of the discharge load DL decreases rapidly, and the current limiting impedance 28 shares a voltage substantially equal to the reduced voltage. The voltage also rises rapidly, and thus the load voltage detection signal Vo rises above the set value.

  When energization of the trigger current is detected by the trigger detection means 38, the control circuit CC supplies a control signal S1 having a high frequency, for example, 40 kHz, to the first inverter circuit 3 and controls to maintain the output power constant. Start in constant power control mode. Since this activation causes an operation delay in the actual circuit, it is performed at a time t4 delayed by, for example, several tens to 100 μs from the time t3, and the inverter circuit 3 is shown in FIG. 3C from the time t4. Thus, an output voltage that rises until time t5 is output. When the output voltage of the inverter circuit 3 exceeds the voltage of the discharge load DL at time t5, the separation diode 10 is forward biased and becomes conductive, and the main power supply MS supplies a current I1 as shown in FIG. Supply to DL. Here, since the separation diode 10 is reverse-biased and non-conductive during the period from time t4 to time t5, the output current of the inverter circuit 3 is charged to the output capacitor 6, and the charge of the output capacitor 6 is not discharged. When the separation diode 10 is forward-biased and conductive after the time t5 has elapsed, the charge of the output capacitor 6 is superposed on the output current of the output side rectifier circuit 5 and discharged to the discharge load DL.

  The start-up operation will be described in more detail with reference to FIGS. 2 and 4. When the trigger of the discharge load DL is detected, the start signal S4 is given to the terminal 31c in FIG. In a state where the start signal S4 is not applied to the terminal 31c, the switch element 31f and the switch element 31g are closed, so that the control amplifier 31e does not operate and its output signal S6 is zero, so that the voltage signal Va at the connection point X is zero. Is at the initial value Va ′ as shown in FIG. Since the initial value Va 'is a relatively large value, the comparator 31j generates a control signal S5' having a relatively large pulse width as shown in FIG. In this state, the start signal S4 is applied to the terminal 31c and simultaneously input to one input terminal of the AND circuit 31k. Therefore, the AND circuit 31k passes the control signal S5 ′ and outputs the pulse width control signal S5. It occurs at the terminal 31d. Thus, the control circuit CC supplies the control signal S1 to the inverter circuit 3 and drives it.

  The control signal S1 at the start-up has a relatively large pulse width with a relatively large initial value Va 'as shown in FIG. 4D, and charges the output capacitor 6 with a current corresponding to the pulse width. When the load voltage detection signal Vo and the load current detection signal Io are higher than the respective set values and the power detection signal Wo is higher than the power setting signal S3, the control amplifier 31e generates a signal S6 for narrowing the pulse width. Output. Accordingly, as shown in FIG. 4, the pulse width of the control signal S1 corresponding to the pulse width control signal S5 is gradually narrowed. As described above, since the separation diode 10 is reverse-biased and non-conductive during the period from time t4 to time t5, the output current of the inverter circuit 3 is charged in the output capacitor 6 and the charge in the output capacitor 6 is not discharged. . When the separation diode 10 is forward-biased and conductive after the time t5 has elapsed, the charge of the output capacitor 6 is superposed on the output current of the output side rectifier circuit 5 and discharged to the discharge load DL. As the charge of the output capacitor 6 is discharged, the power detection signal Wo at the terminal 31a is lower than the power setting signal S3 at the terminal 31b, so that the control amplifier 31e gradually increases the pulse width of the signal S6. Therefore, after time t5, the pulse width of the control signal S1 gradually increases, and this state continues until time t7 when the rated discharge is achieved. Note that FIG. (B) shows a triangular wave signal S7. At time t7, the inverter circuit 3 switches from the above-described power control mode to a known constant power control mode and supplies constant power to the discharge load DL.

  As described above, the power source 100 for a discharge load is mainly intended for power supply to a low-power discharge load DL, for example, a low-power sputtering device of 10 W to several tens W that forms an extremely thin and uniform thin film. In such low-power processing, it is difficult to stably maintain the discharge atmosphere at the time of triggering without causing damage to the formed thin film, and to shift to rated discharge stably and reliably. Therefore, as shown in FIG. 4, when the inverter circuit 3 is activated, the control circuit CC is activated with an initial control signal S1 having a predetermined relatively large pulse width from time t4 to time t5, and then once the control signal S1 After the pulse width is reduced and the separation diode 10 is turned on to discharge the charge of the output capacitor 6 to the discharge load DL, the inverter circuit 3 is started with the control signal S1 having a pulse width that gradually increases from the minimum pulse width. ing. Accordingly, since the main power source MS can supply a current of an appropriate magnitude in a short period immediately after the discharge load DL is triggered, the trigger discharge atmosphere is stably maintained and the rated discharge is stably and reliably transferred. be able to.

  The control circuit CC stops driving the second inverter circuit 21 at time t6 when the output power of the main power source MS exceeds a set value, for example, 80% of the set power. The control circuit CC multiplies the load voltage detection signal Vo at the voltage detection point A and the load current detection signal Io at the current detection point B by a multiplication circuit (not shown) to obtain a detected power value, and the power detection signal Wo is set. When the power signal S3 is exceeded, the supply of the control signal S2 to the second inverter circuit 21 is stopped. Although it is not always necessary to stop the second inverter circuit 21, power loss due to the trigger power source TS can be reduced. When the output power of the main power source MS reaches the rated power at time t7, a process such as forming a thin film is performed by the discharge load DL. When one process is completed, the control circuit CC also stops the main power source MS. The above operation is repeated again.

[Embodiment 2]
With reference to FIG. 5, the discharge load power source 200 of the second embodiment will be described. In FIG. 5, the same symbols as those used in FIG. 1 indicate members having the same names. Since the operation waveform is almost the same as that in FIG. 3, reference is made to FIG. The main difference between the discharge load power supply 200 and the discharge load power supply 100 is that the control circuit CC ′ activates the main power supply MS at approximately the same time as the activation of the trigger power supply TS, or after the trigger power supply TS is activated. The main power source MS is started before the discharge load DL is triggered, and the resistor 11 and the resistor 12 are provided on the cathode side of the separation diode 10 so that the trigger power source TS is high at the time of startup. A voltage proportional to the voltage of the output capacitor 6 without being influenced by the voltage output is detected at the voltage detection point A, and a pulse that gradually increases from the minimum pulse width when the first inverter circuit 3 is started. The soft start is performed by the width control signal, and the discharge load DL is triggered, and at the same time, the first inverter circuit 3 is switched from the constant voltage control to the constant power control. Apart from the detailed configuration of the control circuit CC ′, the other circuit configurations are substantially the same as those of the first embodiment, and thus the description thereof will be omitted.

  The control circuit CC ′ supplies the control signals S1 and S2 almost simultaneously, or first supplies the control signal S2 to the second inverter circuit 21 of the trigger power supply TS, and then decides in advance before the discharge load DL is triggered. At a given time, the control signal S1 is supplied to the first inverter circuit 3 of the main power source MS. Here, the control circuit CC ′ incorporates first and second set voltage signals that increase at a predetermined slope so that the voltage detection signal V2 becomes equal to the first set voltage signal in the initial stage of driving. The control signal S2 to be controlled is supplied to the trigger power source TS, and the control signal S1 is supplied to the first inverter circuit 3 of the main power source MS so that the load voltage detection signal Vo becomes equal to the second set voltage signal. Then, constant voltage control is performed. The control signals S1 and S2 are pulse width control signals whose pulse width gradually increases from the minimum pulse width. Therefore, the control circuit CC ′ does not have the resistors 31h and 31i and the voltage Vx in FIG. 2, and when the discharge load DL is triggered, the first inverter circuit 3 is controlled from the constant voltage control as in the first embodiment. Switch to constant power control mode. Similar to the discharge load power supply 100, the second inverter circuit 2 is activated by the control signal S2, and the negative high voltage of the trigger power supply TS is applied to the DC output terminal 7 through the current limiting impedance 28 and the backflow prevention diode 29. Applied. Since no current flows until just before the discharge load DL is triggered, the negative high voltage of the trigger power source TS is applied to the DC output terminal 7 as it is.

  In this state, the isolation diode is reverse-biased and non-conductive. During this period, since the separation diode is non-conductive, naturally no current flows from the main power source MS to the discharge load DL, and the output capacitor 6 is charged by the output of the first inverter circuit 3. When the discharge load DL is triggered by a negative high voltage of the trigger power supply TS, that is, when a partial discharge path is formed, the output terminal 23 of the DC high voltage generation circuit comprising the transformer 22 and the booster circuit 23, trigger detection means 38, the current detection point B, the current detection means 13, the DC output terminal 8, the discharge load DL, the DC output terminal 7, the current limiting impedance 28, and the reverse current blocking diode 29, the trigger current is output from the DC high voltage generating circuit. Flows to terminal 24. Therefore, a large voltage is applied to the current limiting impedance 28, the negative voltage of the DC output terminal 7 rapidly increases in the zero direction, and the voltage between the DC output terminals 7 and 8 decreases rapidly. At the same time, the control circuit CC ′ detects that the discharge load DL has been triggered by the trigger detection means 38, switches the first inverter circuit 3 from constant voltage control to constant power control, and thereafter the same as in the first embodiment. In addition, constant power control is performed on the first inverter circuit 3.

  When the discharge load DL is triggered, the separation diode 10 is forward-biased and becomes conductive, the charge that has been charged in the output capacitor 6 until then is discharged, and the discharge current becomes the DC output current of the output side rectifier circuit 5. It is superimposed and flows through the discharge load DL. As described in the first embodiment, the discharge current of the output capacitor 6 functions to maintain a discharge atmosphere without adversely affecting the formation of a thin film and to shift to a rated discharge stably and reliably. When the discharge load DL is triggered, the trigger current from the trigger power supply TS is also superimposed as in the first embodiment. However, in this second embodiment, the trigger current is set to a value significantly smaller than the rated discharge current. The trigger power supply TS has been reduced in size and size. Compared to the first embodiment, the second embodiment has a longer period from when the main power source MS is activated until the discharge load DL is triggered and the output capacitor 6 is discharged, that is, the charging time of the output capacitor 6 is longer. Even if the first inverter circuit 3 is soft-started with a pulse width signal in which the pulse width of the control signal S1 gradually increases from the start-up stage, effective energy can be stored in the output capacitor 6. Therefore, in the second embodiment, the control signal S1 that gradually increases the pulse width at the time of activation is used.

  Although the discharge load power source according to the above embodiment has been described particularly in the case where a quality thin film can be formed with a rated discharge power of 10 W to several tens of W, the present invention requires a higher rated power. The present invention can be similarly applied to a power source for a discharge load. In the above embodiment, the simplest photocoupler is used as the trigger detection means 38. However, a general current transformer, a current detection resistor, a current detection IC, or the like may be used. In order to reduce the size and weight of the trigger power source TS, the second inverter circuit 21 is driven by a high-frequency control signal S2 of 20 kHz or higher, and the resistance value of the current limiting impedance 28 is increased. The current is limited to several percent or less, preferably about 2% or less of the constant discharge current. By selecting the conditions in this way, the output power capacity of the trigger power supply TS can be made sufficiently small, and the trigger power supply TS as a whole can be reduced in size and weight, including downsizing of the transformer 22. it can.

It is a figure which shows the power supply device 100 for discharge which is one Embodiment of this invention. It is a figure for demonstrating the function of the control circuit used for the power supply apparatus 100 for discharge. It is a figure which shows the waveform of the voltage for demonstrating the power supply apparatus 100 for discharge, and an electric current. It is a figure which shows an example of waveforms, such as a control signal, in order to demonstrate starting operation | movement of the power supply device 100 for discharge. It is a figure which shows the power supply device 200 for discharge which is another one Embodiment of this invention.

Explanation of symbols

MS ·· Main power supply TS ·· Trigger power supply CC, CC '·· Control circuit DL · · Discharge load 1, 2 ... DC input terminal 3 ... First inverter circuit 4 ... Transformer 5 ·· Output side rectifier circuit 6 ... Output capacitors 7, 8 ... DC output terminal 9 ... Output resistor 10 ... Diode for separation 11 ... Resistor for voltage division 12 ... Resistance for voltage detection 13: Current detection means 21 ... Second inverter circuit 22 ... Transformer 23 ... Boosting circuit 24, 25 ... Output terminal 26 ... High voltage dividing resistor 27 ... Voltage detection resistor 28 ... Current limiting impedance 29 ... Backflow prevention diode 31 ... Control units 31f, 31g of control circuit CC ... Switch element 31e ... Control amplifier 31j ... Comparator 31d ... AND circuit 32, 33, 34, 35 ... signal input lines 36, 37 ... signal output lines 38 ... trigger detection means S1, S2 ... control signal S3 ... power setting signal S4 ... start signal S5 ... Pulse width control signal S6 ... Output signal S7 of control amplifier 31e ... Triangular wave signal Vo ... Load voltage detection signal Io ... Load current detection signal V2 ... Power supply TS for trigger Voltage detection signal I2 ... Trigger discharge current detection signal Wo ... Power detection signal

Claims (9)

In the power source for the discharge load that supplies power to the discharge load,
A first inverter circuit; a first transformer having a primary winding connected to an output side of the first inverter circuit; and a direct current to which the secondary winding of the first transformer and the discharge load are connected An output-side rectifier circuit connected between the output terminals, an output capacitor connected between the DC terminals of the output-side rectifier circuit, one output terminal of the output-side rectifier circuit and one of the DC output terminals; A main power source consisting of a separation diode connected in series between
A second inverter circuit; a DC high voltage generation circuit connected to the output side of the second inverter circuit; and a high voltage output terminal of the DC high voltage generation circuit and the DC output terminal. A trigger power source comprising a current limiting impedance that suppresses a current flowing from the DC high voltage generation circuit to the discharge load when the discharge load is triggered, to a value equal to or lower than a limit value;
A control circuit for controlling the first inverter circuit and the second inverter circuit;
With
The charge charged in the output capacitor by the output current of the output side rectifier circuit during the period when the main power supply is activated and the separation diode is non-conductive, the discharge load is generated by the high voltage output of the trigger power supply. The discharge load is discharged when the separation diode is forward-biased and conducted when triggered, and the discharge current is superimposed on the output current from the output-side rectifier circuit and flows to the discharge load. Power supply. In claim 1,
The control circuit starts up the second inverter circuit first, and then starts up the first inverter circuit when the discharge load is triggered. In claim 1 or claim 2,
The control circuit starts up the first inverter circuit with an initial control signal having a predetermined pulse width, and then drives the control circuit with a control signal having a pulse width smaller than the initial control signal, and then the pulse width of the control signal A power supply for a discharge load, which is driven by a control signal having a pulse width that gradually increases from a smaller minimum pulse width. In claim 1,
The control circuit activates the second inverter circuit, activates the first inverter circuit before the discharge load is triggered, and sets the output capacitor to a set voltage until the discharge load is triggered. A power supply for a discharge load, wherein the first inverter circuit is controlled to be charged. In claim 1 or claim 4,
The control circuit starts up the first inverter circuit with a control signal having a pulse width that gradually increases from a certain minimum pulse width from when the first inverter circuit starts up to a rated discharge state. Power supply for discharge load. In any one of Claims 1 thru | or 5,
The control circuit stops the power supply to the trigger power supply at any time when the output power of the main power supply exceeds 80% of the set power. In any one of Claims 1 thru | or 6,
The control circuit includes a light emitting element connected between a low potential side terminal of the DC high voltage generating circuit and a grounded DC terminal of the output rectifier circuit, and the light emitting element is turned on to turn on the light emitting element. A power supply for a discharge load that detects that the discharge load has been triggered. In any one of Claims 1 thru | or 7,
The power supply for a trigger is provided with a backflow prevention diode connected in series with the current limiting impedance. In any one of Claims 1 thru | or 8,
The discharge load power source, wherein the current limiting impedance has a resistance value that limits a trigger current to several percent or less of a rated discharge current.

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