JP2003268541A - Arc interruption circuit, power supply for sputtering and sputtering equipment - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide an arc cutoff circuit capable of shutting off arc discharge quickly and reliably, and a sputter power supply and a sputter apparatus using the same. SOLUTION: A load (101,
When an arc discharge (150) is detected in 104), an arc cutoff circuit for applying a reverse voltage to the load, wherein the rectifiers (D1, D2) and the capacitor (Cpass) are connected in parallel. In the state where the forward voltage is applied to the load, the current flowing through the load flows through the rectifier as a forward current, and the reverse voltage is applied to the load. Wherein the charging current for charging the capacitor flows through the load when the voltage is applied.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an arc breaking circuit,
The present invention relates to a power supply for sputtering and a sputtering apparatus, and more particularly to an arc cutoff circuit for stopping a forward current and applying a voltage in a reverse direction to cut off an arc discharge, a power supply for sputtering and a sputtering apparatus using the same.

[0002]

2. Description of the Related Art In various types of plasma-applied equipment, high-voltage equipment, power switching equipment, etc., arc discharge causes adverse effects on equipment operation. Therefore, a circuit that surely and quickly interrupts arc discharge is often required. As a concrete example of this, a sputtering apparatus used for forming a thin film will be described as an example.

FIG. 9 is a schematic view showing the structure of the main part of a DC (direct current) sputtering device. This sputtering apparatus has a vacuum chamber 101 and a DC power source 110 for sputtering. The anode of the power supply 110 is the connection cable 120A.
It is connected to the chamber 101 via and is set to the ground potential. On the other hand, the cathode of the power supply 110 is the connection cable 120.
It is connected via B to a sputtering target 104 provided inside the chamber 101. Then, inside the chamber 101, the substrate 1 on which a thin film is to be deposited
00 is installed.

When forming a film, first, the vacuum exhaust pump 1
The chamber 101 is evacuated by 06, and a discharge gas such as argon (Ar) is introduced from the gas supply source 107 to maintain the chamber at a predetermined discharge pressure. Then, an electric field is applied between the target 104 and the chamber 101 by the power supply 110 to generate the glow discharge 108. Then, the positive ions in the plasma generated in the discharge space collide with the surface of the target 104, and the target 10
Kick out 4 atoms. By utilizing such a sputtering phenomenon, a thin film made of the material of the target 104 can be formed on the substrate 100.

However, during such a sputter operation, arc discharge 150 may occur. Such arc discharge 150 occurs relatively often in the vicinity of the target 104, but may occur in the vicinity of the substrate 100. When such an arc discharge 150 occurs, a large current locally flows, so that the target 1
04 and the substrate 100 are damaged.

For example, when an arc discharge 150 occurs on the side of the target 104, a large amount of current is concentrated in a minute area of the target 104, so that a large amount of deposition material is instantaneously discharged from that area. This phenomenon is called “splash” or the like, and the particles of the deposition material scatter on the surface of the substrate 100, which causes damage.

On the other hand, an arc discharge 150 is provided on the substrate 100 side.
In many cases, the substrate 100 is damaged and becomes a defective product.

Therefore, in order to prevent damage due to such arc discharge, it is necessary to provide the power supply 110 with an arc interruption circuit. That is, it is effective to stop the power supply to the chamber at the time when the arc discharge occurs and keep the voltage in the reverse direction within the range where the chamber is not discharged. The shorter the required time, the smaller the arc damage.

FIG. 10 is a circuit diagram showing an example of the essential structure of a sputtering DC power supply 110Z that the present inventor has studied in the course of reaching the present invention. The power supply 110Z illustrated in the drawing includes a forward direction DC voltage source unit and an arc interruption circuit.

The forward DC power source is a power source for applying a positive voltage to the chamber 101 and a negative voltage to the target 104 to perform sputtering. Its configuration is, for example, as illustrated in FIG. 10, a rectifying diode group DB1 that receives a three-phase AC input of R, S, and T, a switching transistor IGB.
T, transformer transformer T1, rectifier diode group DB1, DB
2 and smoothing inductors L1 and L2.

The output from the forward direction DC power supply unit is supplied to the chamber via an arc breaking circuit and power transmission cables 120A and 120B.

The arc breaking circuit is a reverse DC power source (N
4, DB3, C1), arc detection circuit (arc sensor),
It consists of output current bypass transistors (Q1, Q2) and an output limiting resistor (Rpass).

The operation of the sputtering DC power source 110 will be described below.

First, during normal film formation, the transistor Q
1 and Q2 are off, and the output current from the positive direction DC power supply unit is supplied to the chamber via the output diodes (D1 and D2). Then, during sputtering, an arc detection circuit (arc sensor) monitors the occurrence of arc discharge by monitoring the discharge voltage (or discharge current) during sputtering.

When the arc detection circuit (arc sensor) detects the occurrence of arc discharge, the operation of the switching transistor (IGBT) of the inverter is stopped and the bypass transistors Q1 and Q2 are turned on (ON). That is, a bypass of the forward DC power supply is formed, and the chamber current due to the forward voltage is cut off. Then, the reverse voltage from the reverse DC power supply unit (N4, DB3, C1) is applied to the chamber via the transistors Q1 and Q2 and the output limiting resistor (Rpass).

As described above, when the arc discharge is detected, the forward voltage is cut off and the reverse voltage is applied to the chamber, whereby the arc discharge is cut off.

When the output impedance of the arc interruption circuit is small, a large amount of current flows in the opposite direction to that during film formation, which may cause arc discharge in the opposite direction. Therefore, the reverse current is limited by the output limiting resistance (Rpass).

After the arc discharge is cut off in this way, the arc detection circuit (arc sensor) turns on the transistor Q.
1, Q2 is turned off, the output from the reverse direction DC power supply unit is cut off, and the supply of output from the forward direction DC power supply unit is restarted. Output diodes (D1, D2)
Is provided so that the current during film formation can bypass the limiting resistance (Rpass).

When arc discharge occurs again after restarting the sputtering, the arc detection circuit (arcsensor) detects the occurrence and repeats the above-described arc interruption operation.

[0020]

However, as a result of the inventor's own study, in the case of the arc interruption circuit as illustrated in FIG. 10, there is room for improvement in the time required for interruption and restart of sputtering. found.

That is, in the above-described arc interruption operation, when the chamber current from the forward direction DC power supply unit disappears and the chamber is reversely biased, the limiting resistance (Rpass) provided in the path from the reverse direction DC power supply unit. If the resistance value is large, the time required for the reverse voltage to rise becomes long.

This is a power transmission cable 120 to the chamber.
A and 120B have parasitic inductance (Lwire),
In addition, the chamber 101 and the target 104 have a capacitance. That is, when the current is reversed from the positive direction to the reverse direction, if the parasitic inductance and the electrostatic capacitance are present, it takes time to charge if the resistance (Rpass) is large.

In order to prevent this, a limiting resistor (Rpa
If the resistance value of ss) is reduced, a large amount of current may flow in the chamber due to the reverse bias from the reverse direction DC power supply unit, which may cause reverse arc discharge.

On the other hand, output diodes (D1, D
A method of reverse-biasing the chamber with a recovery current having a reverse recovery time of 2) is also conceivable. However, generally, regarding the reverse recovery time of the diode, the maximum value thereof is specified, but the minimum value thereof is not specified. Therefore, this time value is inaccurate, and it is difficult to control the application time of the reverse current.

As described above, the conventional arc breaking circuit has not been able to easily perform the rapid arc breaking while suppressing the generation of the arc in the reverse direction during the arc breaking operation. For this reason, if arc discharge occurs during sputtering, there is a problem that interruption time is required for interrupting and restarting sputtering.

The present invention has been made on the basis of the recognition of the above problems, and an object thereof is to provide an arc interruption circuit capable of interrupting arc discharge quickly and surely, and a sputtering power source and a sputtering apparatus using the same. To do.

[0027]

To achieve the above object, the first arc interruption circuit of the present invention detects the occurrence of arc discharge in a load to which a positive voltage is applied.
An arc interruption circuit for applying a reverse voltage to the load, comprising a circuit in which a rectifying element and a capacitor are connected in parallel, in a state in which the positive voltage is applied to the load. The current flowing through the load flows through the rectifying element as a forward current, and the charging current for charging the capacitor flows through the load when the reverse voltage is applied to the load. It is characterized by having done.

The second arc interruption circuit of the present invention is
An arc cutoff circuit for cutting off arc discharge generated in a load to which a positive voltage is applied, and an arc detection unit for detecting occurrence of the arc discharge in the load,
A reverse voltage applying unit that applies a voltage in a direction opposite to the positive direction with respect to the load, a rectifying element, and a capacitor connected in parallel to the rectifying element, and with respect to the load When the voltage in the positive direction is applied, the current flowing through the load flows as a forward current through the rectifying element, and when the arc detecting means detects the occurrence of arc discharge in the load, the reverse voltage application is performed. The means applies a reverse voltage to the load so that a charging current for charging the capacitor flows through the load.

Here, in the first and second arc interruption circuits, a plurality of the rectifying elements and a plurality of the capacitors are provided, and the plurality of the rectifying elements are connected in series with each other. Each of the capacitors may be connected in parallel to each of the plurality of rectifying elements.

The third arc interruption circuit of the present invention is
An arc interruption circuit that applies a reverse voltage to the load when it detects the occurrence of arc discharge in a load to which a positive voltage is applied, and has a circuit in which a switching element and a capacitor are connected in parallel. In the state in which the forward voltage is applied to the load, the switching is turned on, the current flowing through the switching element flows through the load, and the reverse voltage is applied to the load. In this state, the switching element is turned off so that the charging current for charging the capacitor flows through the load.

The fourth arc interruption circuit of the present invention is
An arc cutoff circuit for cutting off arc discharge generated in a load to which a positive voltage is applied, and an arc detection unit for detecting occurrence of the arc discharge in the load,
A reverse voltage applying means for applying a voltage in the reverse direction to the load, a switching element, and a capacitor connected in parallel to the switching element, and to the load In the state where the voltage in the positive direction is applied, the switching element is turned on, the current flowing through the switching element flows through the load, and the arc detecting means detects the occurrence of arc discharge in the load, The switching element is turned off, the reverse voltage applying means applies a reverse voltage to the load, and a charging current for charging the capacitor flows through the load.

Here, in the third and fourth arc breaking circuits, the switching element may have a rectifying characteristic in which a forward current flows in accordance with the positive voltage.

Further, a plurality of the switching elements and a plurality of the capacitors are provided, the plurality of the switching elements are connected in series with each other, and each of the plurality of the capacitors is the plurality of the switching elements. Can also be connected in parallel to each of.

On the other hand, the sputtering power supply of the present invention is a sputtering power supply for sputtering a target to form a thin film, and includes any one of the above-described arc interruption circuits and a positive voltage for applying the positive voltage. Direction voltage applying means.

Further, the sputtering apparatus of the present invention comprises a vacuum chamber capable of maintaining an atmosphere depressurized to a pressure lower than atmospheric pressure, and the sputtering power source described above, and the positive voltage applied from the positive voltage applying means. The sputtering is performed by a voltage in the direction, and the arc discharge generated in the vacuum chamber is interrupted by the arc interruption circuit.

In addition, a plurality of the sputtering power sources may be provided, and the plurality of sputtering power sources may be connected in parallel with each other.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic view showing an arc interruption circuit according to an embodiment of the present invention and a sputtering apparatus using the arc interruption circuit.

That is, the figure shows a DC power source 110A for spatters having a built-in arc interruption function and a power transmission cable 12
0A and 120B, and chamber 101 represent a combined system. However, the constant power operation of the power supply 110A, the control unit of the inverter circuit, and the like are omitted as appropriate.

The power source 110A includes a positive direction DC voltage source section,
And an arc interruption circuit.

The forward DC power source is a power source for applying a positive voltage to the chamber 101 and a negative voltage to the target 104 to perform sputtering. The configuration of the positive direction DC power supply unit illustrated in FIG. 1 is similar to that described above with reference to FIG. 10, and includes a rectifying diode group DB0 that receives a three-phase AC input of R, S, and T, a switching transistor IGBT, a transformer transformer T1, It has rectifying diode groups DB1 and DB2 and smoothing inductors L1 and L2. However, the positive direction DC power supply unit in the present invention can employ various configurations in addition to the configuration illustrated in FIG.

The output from the forward direction DC power supply unit is supplied to the chamber via the arc breaking circuit and the power transmission cables 120A and 120B.

The arc interruption circuit monitors the output voltage (or output current) from the power source and detects arc discharge by the voltage drop (or current increase) (arc sensor).
And a reverse voltage source (C1) that is rectified and smoothed by adding an N4 winding to the transformer T1 of the inverter, and a transistor that outputs a reverse voltage source (C1) while providing a bypass path for the output current to cut off the current output. Q1 and Q2), and diodes (D1 and D2) that output a forward current during sputtering film formation,
It has a capacitor (Cpass) that outputs a reverse current when the arc is cut off to make the chamber have a reverse voltage.

Comparing the arc interruption circuit of this embodiment with the arc interruption circuit illustrated in FIG. 10, a capacitor (Cpas) is used at the output end instead of the output limiting resistance (Rpass).
The feature is that s) is provided.

The operation of the power supply 110A of this embodiment will be described below.

First, the operation during sputtering film formation will be described. When forming a film by sputtering, use an inverter (DB0, IG
The output from BT, T1 is the diode group (DB1, DB
2) and smoothing inductors (L1, L2) for rectification and smoothing, and diodes (D1, D2) to power transmission cable 1
Output via 20A and 120B. At this time, the polarity of the chamber 101 is positive and the polarity of the target 104 is negative.

During the sputtering operation, the reverse voltage obtained by rectifying and smoothing the output of the N4 winding of the inverter by the diode group (DB3) is charged in the capacitor (C1).

On the other hand, when arc discharge occurs and the arc sensor detects a decrease in output voltage (or an increase in output current), it is recognized as arc discharge and the arc interruption operation is started.

The arc interruption operation of the arc interruption circuit of this embodiment will be described below.

First, when the arc detection circuit (arc sensor) detects arc discharge, the operation of the switching transistor (IGBT) of the inverter is stopped and the transistors (Q1, Q2) are turned on (ON). At this time, forward direction D
The output current from the C power supply unit is held for a predetermined time by the inductors (L1, L2), but
Since 2) forms a detour, it is not output to the chamber.

At the same time, the capacitor (C
The reverse voltage charged in 1) is the transistor (Q
1, Q2), a diode (D1, D2) and a capacitor (Cpass) in a parallel circuit, and a cable (120
A, 120B).

However, the cables (120A, 120B)
Since the chamber and the chamber have parasitic inductance, it takes time for the forward current to disappear even when the reverse voltage is output. The forward current during this period is the diode (D1, D
Since it flows through 2), the capacitor (Cpass) is not charged. When the forward current of the cable due to parasitic inductance disappears, the reverse current becomes dominant, and the diodes (D1, D2) are reverse biased. Then, the capacitor (Cpass) is charged.

Since the impedance of the capacitor (Cpass) used in the present invention is lower than the output limiting resistance (Ppass) illustrated in FIG. 10, the capacitor (Cpa) is used.
The large charging current for ss) allows the chamber to be rapidly biased to a reverse voltage. Moreover, since the current flowing through the capacitor (Cpass) is only the charging current and limits the reverse current flowing in the chamber system, the problem that a large amount of reverse current flows causing reverse arc discharge is solved. it can.

When the charging of the capacitor (Cpass) is completed in this way, the current from the reverse voltage source (C1) is stopped and the power supply to the chamber is stopped.

After the arc discharge is cut off in this way, the transistors Q1 and Q2 are turned off, the output from the reverse direction DC power supply unit is cut off, and the output from the forward direction DC power supply unit is supplied. It will be restarted. The timing for resuming the sputter operation may be set after a predetermined time has elapsed from the detection of arc discharge, or may be determined by monitoring the chamber current with an arc detection circuit (arc sensor) or the like. Good.

In the present embodiment, the output diodes (D1, D2) have a capacitor (C
It is provided so that you can bypass.

When the arc discharge occurs again after restarting the sputtering, the arc detection circuit (arcsensor) detects the occurrence and repeats the above-described arc interruption operation.

According to the arc interrupting circuit of the present embodiment described above, when the capacitor (Cpass) is provided instead of the output limiting resistor (Rpass) at the output end, when arc discharge is detected and the arc interrupting operation is performed. The output impedance of the reverse voltage source is small, and the time required for reverse biasing the chamber is shortened. That is, the arc discharge can be interrupted at high speed.

Further, according to this embodiment, when the application of the reverse bias is completed, no current is output and no power is supplied to the chamber. Therefore, it is possible to eliminate damage caused by reverse arc discharge caused by a large amount of current flowing in the reverse direction.

When an output limiting resistor (Rpass) as shown in FIG. 10 is provided, a current flows through this resistor both when a forward voltage is applied and when a reverse voltage is applied. As a result, power loss occurs, and at the same time, resistance (Rpass)
Fever occurs. According to the study by the present inventor, in the case of a DC power source for spatters having an output current of 10 amperes, even if a resistive element of 100 watt class is provided as an output limiting resistance (Rpass), depending on the frequency of arc discharge, It was recognized that there was some overheating. That is, in order to suppress overheating of the resistance, a considerably large resistance element is required, and there is room for improvement in that the cost also rises.

On the other hand, with regard to the capacitor (Cpass) used in the present embodiment, even if it is a capacitor element that sufficiently exceeds the breakdown voltage required for the sputtering power source, it is very small and low-cost, and at the same time Loss can be eliminated.

The present inventor prototyped the arc breaking circuit shown in FIG. 1 and evaluated its breaking characteristics while comparing it with the arc breaking circuit illustrated in FIG.

FIG. 2 is a graph illustrating the arc breaking characteristic of the arc breaking circuit of the present invention.

Further, FIGS. 3 to 5 are graphs illustrating the arc breaking characteristics of the arc breaking circuit of FIG. 10 and a comparative series similar thereto.

In these graphs, the upper characteristic curve represents the time change of the applied voltage to the target 104, and the lower characteristic curve represents the time change of the discharge current.

First, FIGS. 3 to 5 will be described.

FIG. 3 shows the arc cutoff characteristics when the output limiting resistance (Rpass) is 1 kilohm (kΩ) in the arc cutoff circuit of the comparative example shown in FIG. The scale is 1 microsecond, the current scale on the vertical axis is 5 amperes, and the voltage scale is 200 volts.

In FIG. 3, arc discharge occurs at the time point indicated by arrow P, the voltage (minus) decreases, and the current starts to increase. Then, as represented by the symbol S, the voltage applied to the target 104 is −80.
An arc detection circuit (arc sensor) when the voltage is reduced to volts
Detects the occurrence of arc discharge and the arc interruption circuit has started operation.

However, as can be seen from FIG. 3, the rate of arc discharge, that is, the decrease in the positive direction current is slow, and does not reach zero even after 3.5 microseconds have elapsed since the start of the arc breaking operation. As described above, the reason why the decreasing rate of the arc discharge is slow is that the power transmission cable 12 to the chamber is used.
This is because 0A and 120B have a parasitic inductance (Lwire), and the chamber 101 and the target 104 have a capacitance. That is, when the current is reversed from the positive direction to the reverse direction, if the resistance (Rpass) is large and the parasitic inductance and the electrostatic capacitance are present, the charging time becomes long. Furthermore, as you can see from the voltage characteristics, because the reverse voltage does not rise,
It is also possible that there is stray current flowing through the closed circuit formed by the cables 120A, 120B and the chamber.

In FIG. 3, the application of the forward voltage is restarted at the time of the symbol E, but this is the result of setting a predetermined time by the timer, and originally, the arc breaking operation. Therefore, it is desirable that the forward current after the arc discharge is reduced to zero or to less than zero.

Next, FIG. 4 shows an arc interruption characteristic when the limiting resistance (Rpass) is set to zero in the circuit of the comparative example shown in FIG. In the figure, one scale on the horizontal axis is 1 microsecond, one scale on the vertical axis is 10 amperes, and one scale on the voltage is 200 volts.

As can be seen from FIG. 4, the limiting resistance (Rpas
When s) is set to zero, the current rapidly decreases from the time point S when the arc interruption circuit starts to operate, and the current is swung out in the negative direction. This is because the removal of the limiting resistance (Rpass) shortens the charging time of the parasitic inductance and parasitic capacitance in the cables 120A and 120B and the chamber. However, since the reverse current is not limited, a large amount of reverse current flows, causing a problem of arc discharge in the reverse direction.

In this specific example, as the diodes (D1, D2) at the output end, elements having a reverse recovery time of several tens of microseconds were used. Therefore, during the arc breaking operation (between the reference sign S and the reference sign E), a complete short circuit state due to the reverse bias is suppressed.

Next, FIG. 5 shows the arc interruption characteristics when the limiting resistance (Rpass) is 20 ohms (Ω) in the circuit of the comparative example shown in FIG. Here, one scale on the horizontal axis in the figure is 0.5 microseconds, and one scale on the vertical axis is 5
Ampere, one scale of voltage is 200 volts.

In the case of the comparative example shown in FIG. 5, the discharge current reaches zero in about 1 microsecond from the start of the arc breaking operation (reference S).

This is almost the best result among the comparative examples of FIG. 10 examined by the present inventor. That is, FIG.
In the case of the arc interruption circuit of 0, if the resistance value of the output limiting resistance (Rpass) is too high, the interruption time of the discharge current becomes long as illustrated in FIG. 3, while if the resistance value is too low, as illustrated in FIG. There arises a problem that a large amount of current flows in the opposite direction.

The optimum resistance value of the limiting resistance (Rpass) depends on the parasitic inductance and the parasitic capacitance in the cables 120A and 120B and the chamber. The optimum resistance value also tends to change depending on the material of the target 104 and the conditions such as the type of discharge gas introduced into the chamber during sputtering.

On the other hand, FIG. 2 shows the arc interruption characteristics when an element of 10,000 picofarads (pF) is used as the capacitor (Cpass) in the arc interruption circuit of the present invention shown in FIG. In the figure, one scale on the horizontal axis is 0.5 microseconds, one scale on the vertical axis is 5 amperes, and one scale on the voltage is 200 volts.

Referring to FIG. 2, after the arc detection circuit detects arc discharge and starts the arc interruption operation (reference S), the discharge current reaches zero in only 0.3 microseconds (reference F), It can be seen that the arc discharge was interrupted very rapidly and reliably.

That is, the impedance of the capacitor (Cpass) used in the present invention is lower than that of the output limiting resistance (Ppass) illustrated in FIG.
The large charging current resulting from 1) allows the chamber to be rapidly biased to a reverse voltage. As a result, the reverse voltage rises rapidly as can be seen from the voltage characteristic curve of FIG.

Moreover, the capacitor (Cpass) limits the reverse current flowing in the chamber. That is, as can be seen from the current characteristic curve of FIG. 2, the reverse current is also reliably suppressed. As a result, it is possible to solve the problem that a large amount of reverse current flows to cause reverse arc discharge.

As described above, the arc interruption circuit of the present invention has an extremely high operating time of only about 0.3 microseconds and can reliably suppress arc discharge in the reverse direction. This effect of the present invention has become particularly important in recent years.

That is, in the case of forming a thin film on a silicon (Si) wafer in the conventional manufacturing of a semiconductor device, under the condition that the input power from the power source is relatively low and the deposition rate is slow, for example, sputtering for about several minutes. Was often done.

On the other hand, for example, the demand for CD-R (Compact Disk Recordable), which is rapidly expanding in recent years,
And DVD-R (Digital Versatile Disk-Recordabl
In the production of optical disks such as e), there is a demand to reduce the time required for the sputter film formation process to about several seconds under the condition that the input power is large and the deposition rate is increased. In such a short-time process, the delay of the process due to the interruption operation to the arc discharge and the interruption until the restart of the spatter becomes a serious problem. Moreover, since the polycarbonate disk used as the substrate also has a relatively large amount of released gas in a vacuum as compared with, for example, a silicon wafer, arc discharge due to gas release easily occurs under high power.

Therefore, in the production of these optical discs, there is a particular demand for a sputtering device capable of performing a quick and reliable arc interruption. According to the present invention, as illustrated in FIG. 2, it is possible to surely interrupt the arc discharge in a time that is ⅓ or less of that in the conventional case, and it is possible to largely meet such a requirement.

According to a study by the present inventor, the value of the capacitor (Cpass) is determined by the cable 1 connected to the power supply.
It is desirable that the capacitance value is larger than the parasitic capacitance of 20A, 120B, chamber system, or the like. For example, in the case of a 10 amp class sputter device, cables 120A, 1
The parasitic capacitance of 20B is, for example, 1000 picofarads (p
F), and the parasitic capacitance of the chamber system is, for example, about 400 to 500 picofarads (pF). Therefore, a good result can be obtained if the capacitance value of the capacitor (Cpass) is set to be somewhat larger than the sum of these.

Next, a modified example of the present invention will be described.

FIG. 6 is a schematic diagram showing a first modified example of the present invention. In this figure, elements similar to those described above with reference to FIGS. 1 to 10 are marked with the same reference numerals and not described in detail.

That is, in the DC power source 110B for sputtering of this modified example, two capacitors (Cpass1, Cpass2) are connected in series to the output terminal of the arc interruption circuit. By connecting a plurality of capacitors in series in this way, the voltage withstand voltage can be increased.

FIG. 7 is a schematic diagram showing a second modified example of the present invention. Also in this figure, elements similar to those described above with reference to FIGS. 1 to 10 are marked with the same reference numerals and not described in detail.

In the sputtering DC power source 110C of this modified example, the output diode (D) of the circuit illustrated in FIG.
Instead of 1, D2), transistors Q3, Q4 are provided. As these transistors Q3 and Q4,
For example, a MOSFET (Metal-
Oxide-Semiconductor Field Effect Transistor) is desirable. These transistors Q3, Q4
Can be controlled by, for example, an arc sensor, which is turned on during sputtering and turned off during arc interruption operation.

When ordinary elements are used as the diodes (D1 and D2) in the circuit illustrated in FIG. 1, the forward parasitic resistance is about 1.3 to 1.5 volts, so that the parasitic resistance is increased during sputtering. Power loss occurs corresponding to the resistance value. On the other hand, transistors Q3 and Q4
When a MOSFET is used as, the parasitic resistance in the ON state is as low as about 0.1 to 0.2 V, so that the effect of reducing power loss during sputtering can be obtained.

Further, a MOSF having a parasitic diode
With ET, the transistors Q3 and Q4 can be operated as diodes in the off state.

FIG. 8 is a schematic diagram showing a third modified example of the present invention. Also in this figure, elements similar to those described above with reference to FIGS. 1 to 10 are marked with the same reference numerals and not described in detail.

In this modification, a plurality of sputtering DC power supplies 110 are connected in parallel to one chamber system. Each power supply 110 is a power supply including the arc interruption circuit of the present invention as described above with reference to FIGS.

According to the present invention, it is possible to easily increase the current capacity by connecting a plurality of power sources in parallel as described above. this is,
The element connected to the output end of the arc interruption circuit is
This is because the capacitor (Cpass) is used instead of the resistance (Rpass) represented by 0.

If a power source having an arc breaking circuit as shown in FIG. 10 is connected in parallel, control during arc breaking operation is not easy. That is, when the power supplies of FIG. 10 are connected in parallel and operated, when there is a disturbance such as arc discharge, there is a “deviation” in the timing of the arc interruption operation.
Occurs, there is a risk that the control loop may diverge due to a "breakup state" in which one of them applies the reverse voltage and the other applies the positive voltage. This is because current can flow in both directions through the resistor (Rpass). In order to solve such a problem, it is necessary to operate these multiple power supplies by so-called "master / slave control".
The control system becomes complicated.

On the other hand, according to the present invention, the output end of the arc interruption circuit is not a resistor but a capacitor (Cpas).
s) is provided, there is no concern that the control loop diverges due to the current from one power supply 110 flowing into the other power supply 110.

That is, in the case of the present invention, the current capacity of the sputtering apparatus can be very easily expanded by connecting a plurality of power sources in parallel as necessary while ensuring the arc breaking operation. In other words, the power source can be reused, which is extremely convenient and economical for the user.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

For example, the arc cutoff circuit, the power supply for sputtering of the present invention, the configuration and structure of each part in the sputtering apparatus,
The number, arrangement, shape, material, etc. are not limited to the above specific examples, and those appropriately selected and adopted by those skilled in the art are also included in the scope of the present invention as long as they include the gist of the present invention.

More specifically, for example, regarding the specific configuration of the arc detection circuit provided in the arc cutoff circuit, and the number and arrangement relationship of each circuit element such as a diode, a resistor, and a transistor, those skilled in the art will also understand. Those whose design is appropriately changed are included in the scope of the present invention.

In addition, all arc breaking circuits, power supplies for sputtering, and sputtering devices which have the elements of the present invention and can be appropriately modified in design by those skilled in the art are included in the scope of the present invention.

[0104]

As described above, in the arc breaking circuit of the present invention, the arc breaking operation is extremely fast and the arc discharge in the reverse direction can be surely suppressed.

As a result, it becomes possible to stably carry out sputtering for optical discs, of which demand is rapidly increasing in recent years.

That is, according to the present invention, it is possible to provide an arc interruption circuit, a sputtering power source, and a sputtering apparatus capable of quickly and surely interrupting arc discharge with a simple structure, and industrial merits are great.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an arc interruption circuit according to an embodiment of the present invention and a sputtering apparatus using the arc interruption circuit.

FIG. 2 is a graph illustrating an arc breaking characteristic of the arc breaking circuit of the present invention.

FIG. 3 is a graph diagram illustrating an arc interruption characteristic of an arc interruption circuit of FIG. 10 and a comparative column similar to FIG.

FIG. 4 is a graph diagram illustrating an arc interruption characteristic of an arc interruption circuit of FIG. 10 and a comparative column similar thereto.

FIG. 5 is a graph diagram illustrating an arc interruption characteristic of an arc interruption circuit of FIG. 10 and a comparative series similar thereto.

FIG. 6 is a schematic diagram showing a first modified example of the present invention.

FIG. 7 is a schematic diagram showing a second modified example of the present invention.

FIG. 8 is a schematic diagram showing a third modified example of the present invention.

FIG. 9 is a schematic diagram showing a configuration of a main part of a DC (direct current) sputtering device.

FIG. 10 is a circuit diagram illustrating the configuration of a main part of a sputtering DC power supply 110Z that the present inventor has studied in the course of reaching the present invention.

[Explanation of symbols]

100 substrates 101 vacuum chamber 104 target 106 Vacuum pump 107 gas supply source 108 glow discharge 110, 110A-110Z Sputtering power supply 120A, 120B cable 150 arc discharge DB1 Rectifier diode group IGBT switching transistor L1, L2 smoothing inductor Q1-Q4 transistors T1 transformer

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[Procedure amendment]

[Submission date] April 8, 2002 (2002.4.8)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

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Claims (10)

[Claims] 1. An arc cutoff circuit for applying a reverse voltage to a load when the occurrence of arc discharge in a load to which a positive voltage is applied is detected. A rectifying element and a capacitor are connected in parallel. In the state where the voltage in the positive direction is applied to the load, the current flowing in the load flows as a forward current in the rectifying element, and the voltage in the reverse direction is applied to the load. The arc interruption circuit is characterized in that a charging current for charging the capacitor is caused to flow through the load when a voltage is applied. 2. An arc interruption circuit for interrupting an arc discharge generated in a load to which a positive voltage is applied, said arc detection circuit detecting an occurrence of said arc discharge in said load, and said arc detection circuit for said load. A reverse voltage applying means for applying a voltage in the reverse direction to the forward direction; a rectifying element; and a capacitor connected in parallel to the rectifying element, wherein the forward voltage is applied to the load. In the applied state, the current flowing through the load flows as a forward current through the rectifying element, and when the arc detecting means detects the occurrence of arc discharge in the load, the reverse voltage applying means applies to the load. And a reverse voltage is applied to cause a charging current for charging the capacitor to flow through the load. 3. A plurality of said rectifying elements and a plurality of said capacitors, said plurality of said rectifying elements being connected in series with each other, wherein each of said plurality of said capacitors is said plurality of said rectifying elements. 3. The arc interruption circuit according to claim 1, wherein the arc interruption circuit is connected in parallel to each of the above. 4. An arc cutoff circuit for applying a reverse voltage to the load when the occurrence of arc discharge in a load to which a positive voltage is applied is detected, wherein a switching element and a capacitor are connected in parallel. In the state where the voltage in the positive direction is applied to the load, the switching is turned on, the current flowing through the switching element flows through the load, and the reverse voltage is applied to the load. In a state in which a directional voltage is applied, the switching element is turned off so that a charging current for charging the capacitor flows through the load. 5. An arc interruption circuit for interrupting an arc discharge generated in a load to which a positive voltage is applied, said arc detection means detecting an occurrence of said arc discharge in said load, and said arc detection circuit for said load. Reverse direction voltage applying means for applying a voltage in the reverse direction to the forward direction, a switching element, and a capacitor connected in parallel to the switching element, comprising: In the applied state, the switching element is turned on, the current flowing through the switching element flows through the load, the arc detection means, when detecting the occurrence of arc discharge in the load, the switching element is turned off. And the reverse voltage applying means applies a reverse voltage to the load to charge the capacitor. An arc interruption circuit characterized in that a current flows through the load. 6. The arc breaking circuit according to claim 4, wherein the switching element has a rectifying characteristic in which a forward current flows in accordance with the positive voltage. 7. A plurality of the switching elements and a plurality of the capacitors, wherein the plurality of the switching elements are connected in series with each other, wherein each of the plurality of capacitors is the plurality of the switching elements. 7. The arc interruption circuit according to any one of claims 4 to 6, wherein the arc interruption circuit is connected in parallel to each of the above. 8. A sputtering power source for sputtering a target to form a thin film, the arc interruption circuit according to claim 1, and a positive voltage source for applying a voltage in the positive direction. A power supply for sputtering, comprising: directional voltage applying means. 9. A vacuum chamber capable of maintaining an atmosphere at a pressure lower than atmospheric pressure, and the sputtering power source according to claim 8, wherein the positive voltage is applied by the positive voltage applying means. A sputtering apparatus, wherein sputtering is performed, and the arc discharge generated in the vacuum chamber is interrupted by the arc interruption circuit. 10. A sputtering apparatus comprising: a plurality of sputtering power supplies, wherein the plurality of sputtering power supplies are connected in parallel with each other.