JPH0233846A - Power cutoff recovery device - Google Patents

Abstract

PURPOSE:To restore power after arc extinction of discharge so as to enable generation of pulse voltage from DC voltage in synchronization with control signals given from the outside by detecting that the arc is extinct after breaking the power at discharge generation. CONSTITUTION:When the ion source of a power breaking/restoring device is in stationary operation, vacuum tubes 2A and 2B inside high voltage parts 1A and 1B become ON, and powers 6A. and 6B are applied to between ion source electrodes 9A and 9B and between 9B and 9C, and the values of interelectrode currents IEA and IEB are made stationary currents I, and the values of interelectrode voltages VEA and VEB are made stationary voltage V1. And if discharge arises between electrodes 9A and 9B or between 9A and 9C at time T1, the currents IEA and IEB rise up to a discharge current peak value I2 which is determined by current voltage characteristics of the vacuum tubes 2A and 2B and restriction resistances 8A-8D and short-circuit the voltage VEA and VEB making them almost zero. And the signals of voltage values detected by potential dividers 4C and 4D are transmitted to a control circuit 7 through photoelectric transfer circuits 11A and 11B or 11C and 11D and an optical fiber 18C, and the circuit 7 detects the discharge with the decrease of the voltage value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power source for a semiconductor ion implantation device, an ion source electron beam, a plasma processing headpiece, a laser, etc., and particularly a power source that can quickly shut off the power source and return it quickly. This invention relates to a cut-off/return device.

[Conventional technology]

Conventionally, in a device that has a built-in vacuum discharge gap such as a high-voltage power supply, an ion source, and an electron beam, if a power supply short circuit occurs due to discharge, Japanese Patent Publication No. 47-35498.

There are power cutoff devices described in Japanese Patent Publication No. 48-27278 and Japanese Patent Publication No. 62-28560. That is, when a discharge occurs in the device, the discharge current or the voltage of the discharge gap is detected, and the switching element such as a vacuum tube or semiconductor element is immediately controlled to become non-conductive, the power is cut off, and the power is turned off. A method of short-circuiting the short-circuit time is known. Further, in Japanese Patent Publication No. 62-28560, the reliability of power cut-off is improved by cutting off the power when discharge continues for a certain period of time or more. Regarding the power restoration, a method is known in which the power is restored after ms has elapsed since the power was cut off.

Furthermore, as a means for improving the vacuum insulation withstand voltage inside the device, a method is known in which a pulsed high voltage or an alternating current voltage is applied from the outside to perform a discharge treatment on the electrode surface. for example,
In JP-A No. 60-262339, a DC high voltage power supply,
A switch for switching between two electrodes of an AC high-voltage power source is provided so that the electrode surface can be subjected to discharge treatment by switching to the AC power source.

[Problem to be solved by the invention]

In the above-mentioned conventional power cut-off recovery device, after the power is cut off due to discharge, the pause time until the power is turned back on again is fixed to a certain period of time, for example, about several milliseconds. However, if the duration of the discharge is longer than the above pause time, the discharge will occur again even after the power is restored, making it impossible to reliably restore the power, and if this operation is repeated, oscillation of the high voltage circuit may occur. There is a problem. Therefore, if the above-mentioned pause time is set to be sufficiently longer than the discharge duration time, there is a problem in that the power supply pause time becomes longer.

For equipment equipped with an AC high-voltage power supply and a selector switch to perform discharge treatment on the electrode surface to improve withstand voltage, a separate power supply for the above-mentioned discharge treatment is required in addition to the DC high-voltage power supply for normal operation of the equipment. The problem was that it required a changeover switch. Furthermore, if an AC high voltage is used in the above-mentioned discharge treatment, there is a problem in that continuous arc discharge occurs between the electrodes, the electrode surface is consumed, and the electrode life is shortened.

A first object of the present invention is to reliably perform a recovery operation after power cutoff without malfunction, and to shorten the power outage time. The second purpose is to maintain high interelectrode withstand voltage,
In addition, in order to extend the life of the electrode, a pulse voltage for the discharge treatment is generated from a DC voltage without using the AC power source for the discharge treatment, thereby performing the discharge treatment with less wear on the electrode surface.

[Means to solve the problem]

A feature of the present invention is that when a discharge occurs, after cutting off the power supply, it is detected that the discharge is extinguished, and the system is restored after the discharge is extinguished. The second feature is that when the power is restored, the device is used for a certain period of time necessary to diffuse the ions remaining after the discharge is extinguished. The third feature of the present invention is that a pulse voltage is generated from a DC voltage in synchronization with a control signal given from the outside.

That's the point. A fourth feature of the present invention is that the pulse voltage is applied between the discharge electrodes on the load side to perform a process of removing defects on the electrode surface, that is, a conditioning process. A fifth feature of the present invention is to measure the number of discharges and the interval at which discharge occurs, and to condition the electrodes so that the number of discharges does not increase beyond the abnormal number or the discharge interval does not fall below the abnormal interval. The point is that it is processed.

[Effect]

After the power supply is cut off due to discharge, the power supply restoration operation is performed after the extinction of the discharge is detected. This prevents the power supply from malfunctioning in its return operation, and can shorten the power outage time to the necessary minimum. When the ions remaining between the electrodes disappear after detecting a discharge, the power is restored by the device.
The power recovery operation becomes more reliable.

Pulse voltage can be generated directly from the DC power supply by turning on and off the switching elements. This makes it possible to omit the power supply and switching circuit required for conditioning processing. Furthermore, since the voltage is pulsed, the duration of the discharge between the electrodes during conditioning is shortened, and wear and tear on the electrode surfaces can be reduced. Furthermore,
The number of discharge occurrences is measured during operation, and when this number increases, conditioning is performed. by this,
Even if the withstand voltage between the electrodes decreases, the withstand voltage can be immediately restored to a high value, so it is possible to prevent frequent discharges, and furthermore,
Since electrode consumption is also reduced, the life of the electrode can be extended.

〔Example〕

FIG. 1 shows an example of a system configuration of an ion source power-off recovery device for carrying out the present invention. During steady operation of the ion source, the vacuum tubes 2A and 2B in the high voltage parts IA and IB of the power cut-off recovery device are on, and the acceleration power supplies 6A and 6B are applied between the ion source electrodes 9A and 9B and between 9B and 9C. The value of the interelectrode current IE^IIEB is the steady current 1 in FIG. 3, and the value of the interelectrode voltage vE^tVEB is the steady voltage v1. At time T1 in FIG.
, 9B or between 9B and 9C, IE^
Or, IEB rises to the discharge current peak value I2 determined by the current-voltage characteristics of the vacuum tubes 2A, 2B and the limiting resistors 8A, 8B, 8G, 8D, and VE^ or VEB is short-circuited and becomes almost zero.

The voltage value detected by the voltage dividers 4C and 4D is the photoelectric conversion circuit 1
1A, IIB or IIC, 11D and optical fiber 18C
The signal is transmitted to the control circuit 7 at ground potential via
The control circuit 7 detects discharge due to the decrease in the voltage value. When a discharge is detected, the optical fibers 18A, 18
The vacuum tube off-trigger signal TR0FF shown in FIG. 3 is sent to the control circuits 3A and 3B via the
A.

The first grid voltage V at of 2B becomes the voltage V OFF at which the vacuum tube is turned off. After the vacuum tubes 2A and 2B are turned off, the discharge is extinguished at time tz, IE^ and IE[S become zero, and VE^ and VER become the voltage dividers 4A, 4C, and 4.
The output voltages of the acceleration power supplies 6A and 6B are divided into voltages Vz at B and 4D. Due to this rise in voltage, the control circuit 7 detects that the discharge is extinguished. The control circuit 3A immediately after the extinguishment of the discharge is detected or after a certain set time (about 100 μs) has elapsed.

Vacuum tube on trigger signal TR0NI is sent to 3B, and V
G1 becomes the voltage VON that turns on the vacuum tubes, the vacuum tubes 2A and 2B turn on again, the power is restored, and at time t3, the ion source returns to normal operation.

When the power is restored at such timing, the discharge is reliably extinguished before the power is restored, and the time required for the power to be restored after the discharge is extinguished can be kept to the minimum necessary. The downtime of operation can also be suppressed to a short time of about 500 μs or less. Further, in this embodiment, the power supply for the control circuits 3A and 3B, which are at a high potential, is connected to the isolation transformer 5A.

5B, and control signal transmission is provided by optical fiber 18A.
, 18B, and 18G, it is easy to exchange signals between control circuits at different potentials, and the control circuit 7 at ground potential allows the tonality of the control operation and control status to be viewed. Is possible.

As shown in Fig. 2, current detection shaft resistors 10A and IOB are provided in place of the voltage dividers 4C and 4D in Fig. 1, and discharge detection and discharge extinction detection are performed using an interelectrode type '4 I E^IIE.
This may be done by changing B.

Next, FIG. 4 shows an embodiment of the structure of the high-voltage parts IA and IB of the power interruption recovery device. Control circuit 3A, 3B, voltage divider 4A, 4B, vacuum tube 2A.

2B, and insulation transformers 5A and 5B are housed in an oil-tight tank 12 and are oil-insulated. The wiring with the power supply and electrodes is
Shield SL, S2 oil-immersed paper insulated cable C1, C2, G
3. C4, bushing.

This is achieved while maintaining insulation from the earth via 15A, 15B, 15C, 15D and high voltage insulated cables 16A, 16B, 16G, 16D. Optical fiber 18A, 18B
is an optical fiber support 17A.

17B, it is drawn out from above the oil level 14 through the duct ID. With this structure of the tank that allows the oil level 14 to be at a level above the cable heads], 5A, and 15B, the optical fiber can be drawn out from above the oil level without affecting the oil-immersed insulation. In addition, when assembling the device, instead of attaching each part directly to the tank 12, all parts are attached to the frame B that is integrated with the tank lid, and then inserted into the tank 12 after assembly. Assembly and disassembly work can be done without going inside.

Also, inside this oil-tight tank 12, there is a high voltage power supply 6A shown in FIG.
, 6B, one oil tank becomes unnecessary, and the high-voltage insulated cable 16A connects the high-voltage part of the power cut-off recovery device and the high-voltage power source.

16B and bushings 15A and 15B are no longer required, making it more compact and lower in cost.

FIG. 7 shows a configuration diagram of a control circuit that can apply a conditioning voltage having a waveform shown in FIG. 5 between electrodes 9A and 9B and between electrodes 9B and 9C in FIG. 1.

Voltage Vat between the cathode of the vacuum tube and the first grid G1
and the voltage VG2 between the cathode and the second grid G2,
It is given from the output terminal of the control circuit 3A.

The control circuit 7 at ground potential connects the optical fiber 18A1°1
8 A2.18 A control signal is sent to the control circuit 3A via A3 to perform power-off recovery control or conditioning control. During steady operation of the ion source, VGI control signal source 2
6 and the VO2 control signal source 23 are set so that the vacuum tube 2A is turned on. (For example, V G 1 is -
50V, Va2 is 500V) The Va1 control signal is sent from the signal source 26 to the switch 25. In the photoelectric conversion circuit 11,
It is transmitted to the VGI control circuit 24 via the IIL and the optical fiber 18A3, and in response to the signal from the control circuit 24, the F
The gate voltage of ET2OB changes and the value of V a 1 given from the Vat power supply becomes equal to the set value. Similarly, V
The az control signal is transmitted from the signal source 22 to the photoelectric conversion circuit 11G,
IIH, VO2 control circuit 2 via optical fiber 18Ar
1, the voltages of FET2OB and FET20A are adjusted, and the value of VO2 provided from the V G ZTi source 39B becomes equal to the set value. Note that during this steady state, FET20C.

There is an open circuit between the drain D and source S of 20D, and +
FET20C and FET20D do not affect control.

Further, resistors 19A, 19B, and IQ-C are load resistances necessary for the operation of the FET. Electrode 9A during steady operation.

When a discharge occurs between 9B and 9B, in the control circuit 7, the value of the interelectrode voltage VE^ measured by the voltage divider 4C and transmitted via the optical fiber 18C1 and the photoelectric conversion circuit 11C1IIF is determined by the discharge detection reference signal source 34. When the comparator 33A determines that the output is smaller than the output, the power cut-off recovery control circuit 32 detects the discharge, and the switch 31. Photoelectric conversion circuit 11 I, IIJ.

Optical fiber 18A2. Via the optical isolator 30,
The vacuum tube off control signal is transmitted to the on/off control circuits 29A, 29
B, the drain D and source S of FETs 20C and 20D become conductive, and the DS of FET 20A becomes an open circuit, and V G 1 becomes the negative maximum value (for example, -50
0V), VO2 becomes Ov, so the vacuum tube 2A
is turned off and the power is cut off. When the discharge is extinguished, the discharge extinguishment detection reference signal source 35 or 3 is activated in the same way as when the discharge occurs.
7 and the comparator 33B or 33D, the control circuit 32
Arc extinction is detected at , a vacuum tube ON control signal is sent, and VO
I and VO2 return to their normal setting voltages, the vacuum tube 2A is turned on again, and the power is restored. At this time, the vacuum tube on/off control signal transmitted through the optical fiber 18A2 is 1
Since it is a bit digital signal, it is transmitted at high speed, and V
at, VO2 (7) voltage change is FIET20A,
20 C.

Since this is done by the high-speed switching operation of the 20D, the power can be cut off and restored at a high speed of about 50 μs. Also, instead of the interelectrode voltage VE^ as shown in Fig. 8,
Discharge and arc extinction may be detected based on the value of the interelectrode withstand voltage E^ measured by the shunt resistor 10A.

Next, when performing conditioning, switch 31
By switching the vacuum tube 2A, the vacuum tube 2A is turned on and off in synchronization with the vacuum tube on/off control signal sent from the conditioning control signal source 38 regardless of the occurrence of discharge, and for example, a pulsed conditioning voltage having a waveform as shown in FIG. 5 is applied to the electrode 9A. , 9B. Also, if a vacuum tube ON signal is always sent from the V C1 control signal source 26 and a control signal of any waveform such as a sine wave or a triangular wave is transmitted from the V C1 control signal source 26, a conditioning voltage of an arbitrary waveform (for example, the 6th waveform) corresponding to the control signal waveform is transmitted. The voltage of the waveform shown in the figure) can be obtained.

Flowcharts of the conditioning process performed during continuous operation of the semiconductor ion implantation device are shown in FIGS. 9 and 10. FIG. 9 is a flowchart when conditioning is performed at the time of wafer exchange to reduce time loss. Count 41 the number of discharges N that occurred between the start of ion implantation 40 and the end of ion implantation 42, and if the number of discharges N is equal to or greater than a preset abnormal value No (44)
, a conditioning process 45 is performed in parallel with the wafer exchange 43, and after the wafer exchange 43 and conditioning process 45 are completed and the preparation for ion implantation is completed 46, ion implantation is started again (40). According to this method, frequent discharges can be detected and the recurrence of discharge can be prevented by the conditioning process 45, so that damage and contamination of the device due to discharge can be reduced. Furthermore, since the conditioning process is performed in parallel with the wafer exchange, there is less time loss, and the conditioning process does not affect the wafer during ion implantation. FIG. 9 is a flowchart when ion implantation is temporarily stopped and conditioning processing is performed. When the number of discharges N becomes equal to or greater than No from the start of ion implantation 47 to the end of ion implantation (48), ion implantation is temporarily stopped (53), and after conditioning processing 54 is performed, ion implantation is restarted. When the ion implantation amount exceeds the specified value no (4
9) The ion implantation is completed 50) and the wafer is replaced (52). According to this method, as soon as frequent discharges occur, ion implantation is temporarily stopped and the recurrence of discharges is prevented through conditioning treatment, so that frequent discharges do not continue and there is very little damage or contamination to the device. Examples of means for performing discharge cleaning in the conditioning process include increasing the peak value of the conditioning voltage higher than the voltage during steady operation, or introducing conditioning gas (a gas suitable for cleaning) to the pressure at which discharge occurs. There are many things that can be mentioned.

〔Effect of the invention〕

According to the present invention, it is possible to reliably restore the power after the power is cut off due to discharge without causing any malfunction. In addition, the power interruption time from power cutoff to power restoration due to discharge occurrence is reduced from the conventional several ms to, for example, 500 ms.
This has the effect of shortening the time to about μs. Furthermore, a pulse waveform is generated from the DC power supply.

Since it is possible to generate a pulse voltage whose pulse width, voltage value, pulse interval, number of pulse generation, etc. can be arbitrarily adjusted, it is possible to generate conditioning voltages with various waveforms.

Further, according to the present invention, even if the inter-electrode withstand voltage decreases during continuous operation, the withstand voltage value can be improved by the discharge treatment, that is, the conditioning treatment, of the electrode surface at 5', so that the effect and device that can suppress the occurrence of discharge can be improved. It has the effect of extending the life of the

In addition, by housing the power source and the power interruption recovery device in the same container, the cost of the device can be reduced and the device can be made smaller.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an embodiment of the present invention, Fig. 2 is a diagram showing a modification of Fig. 1, Fig. 3 is an explanatory diagram of the operating principle of the invention, and Fig. 4 is an embodiment of the invention. FIG. 5 is a pulse voltage waveform diagram explaining the operation of an embodiment of the present invention, FIG. 6 is a diagram showing a modification of FIG. 5, and FIG. 7 is an implementation of the configuration circuit of the present invention. FIG. 8 is a diagram showing a modification of FIG. 7, FIG. 9 is a flowchart explaining the operating procedure of an embodiment of the present invention, and FIG. 10 is a modification of FIG. 9. It is a diagram. IA, IB... High voltage part of power cutoff recovery device, 2A. 2B... Vacuum tube, 3A, 3B... High voltage side control circuit. 4A, 4B... Voltage divider, 7... Low voltage side control circuit, 9
A~9C...electrode, IOA, IOB...shunt resistance, VE^l VEB...interelectrode voltage, IE^, I[
! B...Current between electrodes, 11...Discharge occurrence time, t2
...Discharge arc extinguishing time, 12...Oiltight tank, 18A~
18C... Optical fiber, V a 1... First grid voltage, VO2... Second grid voltage, 21 VC
2 control circuit, 24...V G 1 control circuit, 29A,
29B... Vacuum tube on/off control circuit, 32... Power cutoff recovery control circuit, 38... Conditioning control signal source. Figure 3 Atsushi 40th! ;Figure 60 No. 9 Entrance

Claims (1)

[Claims] 1. Between the power supply output side and the load side of a high voltage circuit such as a semiconductor ion implantation device, which is composed of a DC high voltage power supply, a load having discharge poles, and a voltage measuring voltage divider. , by inserting high voltage switching elements such as vacuum tubes and semiconductor switches,
What is claimed is: 1. A power cut-off and recovery device that cuts off a power supply when discharge occurs on a load side, and is characterized in that the power supply is restored after detecting extinguishment of the discharge. 2. Claim 1 is characterized in that after detecting the extinction of the discharge arc, the power supply is restored after a certain period of time necessary to diffuse the ions remaining between the discharge electrodes. Power cutoff recovery device. 3. In claim 1, the switching element is turned on (turned on) in synchronization with a control signal applied from the outside;
1. A power cut-off recovery device characterized by conditioning an electrode on the load side by making it non-conductive (off) and generating a pulse voltage on the load side. 4. A power supply interruption recovery device according to claim 1, characterized in that it is housed in the same container as a high voltage power supply. 5. A power supply interruption recovery device according to claim 4, characterized in that the high voltage power source is housed in the same container, and the container is filled with an insulating liquid, a solid insulator, or a gas insulator. 6. The power cutoff recovery device according to claim 3, characterized in that conditioning is performed when the number of discharge occurrences on the load side exceeds a preset abnormal value. 7. A power-off recovery device according to claim 3, characterized in that conditioning is performed when the time interval between discharge occurrences on the load side becomes shorter than a preset abnormal value. 8. A power-off recovery device according to claim 3, characterized in that a conditioning process is performed at the time of sample exchange. 9. A power-off recovery device according to claim 6, characterized in that the operation is temporarily stopped and a conditioning process is performed. 10. In claim 3, if the number of discharge occurrences on the load side exceeds a preset abnormal value, the operation of the device is immediately stopped and conditioning processing is performed, or
Alternatively, a power-off recovery device is characterized in that a conditioning process is performed when replacing a sample. 11. In claim 3, when the time interval between discharge occurrences on the load side becomes shorter than a preset abnormal value, the operation of the apparatus is immediately stopped and conditioning processing is performed, or the sample is replaced. A power-off recovery device characterized by performing conditioning processing at times.