JPH06326543A - High frequency device - Google Patents

Abstract

PURPOSE:To provide a high frequency device which performs a normal matching operation only in the case of causing the discharging in a load. CONSTITUTION:A matching box 3 has different output voltage levels between a case where the discharging is caused in a load 7 and a case where no discharging is caused in the load 7. When the discharging is caused in the load 7, a 3rd control circuit 16 turns on the switched 17 and 18 based on the bias voltage level. As a result, the variable capacitors 4 and 5 are automatically controlled and the optimum matching of impedance is secured. Meanwhile the bias voltage level is set at zero and therefore the circuit 16 turns off both switches 17 and 18 when no discharging is caused in the load 7. As a result, both capacitors 4 and 5 are not automatically controlled any more and can be controlled only with the manual operations. Under such conditions, the capacitors 4 and 5 are manually controlled so that the discharging is started in the load 7. When the discharging is started in the load 7, the circuit 16 turns on the switches 17 and 18 to ensure an automatic matching operation of impedance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency device such as a high frequency sputtering device or an etching device which can perform impedance matching in a short time.

[0002]

2. Description of the Related Art In a high frequency sputtering apparatus, a high frequency is applied between two electrodes to sputter one electrode (sample) to clean the surface of the sample. In another high-frequency device, a high frequency is applied between two electrodes so that particles sputtered from one electrode are attached to a substrate arranged close to the electrode. FIG. 1 shows an outline of such a high frequency device,
1 is a high frequency oscillator. The high frequency from the high frequency oscillator 1 is supplied to the matching box 3 via the detector 2. The matching box 3 includes a matching variable capacitor 4, a tuning variable capacitor 5, and a coil 6. The high frequency from the matching box 3 is supplied to the load 7. The detector 2 detects the high-frequency voltage and current input to the matching box 3, and the phase difference θ between the voltage and the current.

In such a configuration, the impedance and the phase are obtained based on the voltage, current and phase detected by the detector 2, and the capacitance of the matching variable capacitor 4 in the matching box 3 is changed based on the impedance value. , The capacitance of the tuning variable capacitor 5 is changed based on the phase difference. That is, the impedance Z detected by the detector 2 is supplied to the first control circuit 8 and compared in this circuit with the reference voltage. The first control circuit 8 compares the reference voltage with the value of the impedance Z supplied and outputs the difference voltage. The output of the first control circuit 8 is supplied to the motor 9 that drives the matching variable capacitor 4. As a result, the matching variable capacitor 4 is adjusted by the motor 9 so that the value of the impedance Z becomes equal to the reference voltage.

The phase difference θ detected by the detector 2 is supplied to the second control circuit 10 and compared with the reference voltage. The second control circuit 10 compares the reference voltage with the supplied value of the phase difference θ and outputs the difference voltage. The output of the second control circuit device 10 is supplied to the motor 11 that drives the tuning variable capacitor 5. As a result, the motor 1 is adjusted so that the value of the phase difference θ becomes equal to the reference voltage (0).
The matching variable capacitor 5 is adjusted by 1.

The first and second control circuits 8 and 10 are
Each is internally equipped with an AD converter, a DA converter, and a microprocessor, and compares the supplied signal with an internal reference signal and outputs a difference signal between the two signals. Further, the position information of the matching variable capacitor 4 and the tuning variable capacitor 5 is supplied to the control circuits 8 and 10.

[0006]

With the above-described structure, impedance matching is automatically executed, and high-frequency power is efficiently supplied to the load 7. With the above configuration, when the load 7 is discharged, the feedback loop operates properly. However, when discharge is not generated in the load 7, there is no matching condition, for example, the point of impedance Z = 50 ohms and θ = 0, and the variable capacitors 4 and 5 hunting operation in which the forward rotation and the reverse rotation are repeated by the detection signal. Will be done. When this hunting operation occurs, the feedback loop does not operate normally and impedance matching takes a long time.

The present invention has been made in view of the above circumstances, and an object thereof is to realize a high-frequency device which performs a normal matching operation only when discharge occurs in a load. .

[0008]

A high frequency device according to the present invention is arranged between a high frequency power source, a load to which high frequency power is supplied from the high frequency power source, a power source and the load, and a matching variable capacitor and a tuning variable. A matching box consisting of a capacitor and a coil, a detector that detects the phase difference between the high-frequency input impedance input to the matching box and the input high-frequency voltage and current, and variable matching based on the detected input impedance and phase. An automatic adjustment means for automatically adjusting the capacitor and the tuning variable capacitor; a means for detecting the output voltage of the matching box; a detection means for monitoring the output voltage of the matching box and detecting the occurrence of discharge in the load; Stops the operation of the automatic adjustment means according to the signal from the detection means It is characterized by comprising a means for.

[0009]

The high-frequency device according to the present invention utilizes the fact that a bias voltage is superimposed on the output of the matching box when discharge is occurring in the load, and monitors the voltage to detect the occurrence of load discharge. , When the discharge is stopped, the automatic impedance matching operation is stopped.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows an embodiment of the present invention, and the same reference numerals as those in the conventional apparatus of FIG. 1 indicate the same components. In this embodiment, the output voltage of the matching box 3 is detected by the voltage detector 15. The output signal of the voltage detector 15 is supplied to the third control circuit 16. Further, the output of the first control circuit 8 is configured to be supplied to the motor 9 via the switch 17, and the output of the second control circuit 10 is supplied to the motor 11 via the switch 18. Is configured. The third control circuit 16 includes the switch 1
Control of switching between 7 and 18 is performed. The operation of such a configuration will be described below.

With the above structure, the high frequency power from the high frequency oscillator 1 is applied to the load 7. At this time, the high frequency oscillator and the impedance on the load side are matched to efficiently supply the high frequency to the load 7. Impedance matching is performed by adjusting the matching variable capacitor 4 and the tuning variable capacitor 5 in the matching box 3.
The operation of impedance matching in this embodiment will be described below.

First, the output voltage of the matching box 3 is detected by the voltage detector 15. The output voltage of the matching box differs when the discharge is generated in the load 7 and when the discharge is stopped. Fig. 3 shows load 7
Shows the output voltage of the matching box 3 when a discharge is occurring, and the high frequency voltage is superposed with a predetermined bias voltage V _B. Further, FIG. 4 shows the output voltage of the matching box when the discharge is stopped by the load 7, and the bias voltage is not superimposed on the high frequency voltage.

When the load 7 is being discharged, the third control circuit 16 turns on the switches 17 and 18 based on the value of the bias voltage V _B. As a result, the matching variable capacitor 4 and the tuning variable capacitor 5 in the matching box 3 are automatically adjusted as in the conventional device of FIG. 1, and impedance matching is optimally performed. That is, at this time, the impedance Z
= 50 ohms, there is a point where the phase difference θ = 0, and the desired impedance matching is executed in a short period of time without the hunting operation in which the variable capacitors 4 and 5 repeat forward rotation and reverse rotation according to the detection signal.

On the other hand, when the discharge is stopped in the load 7,
Since the bias voltage of the third control circuit 16 becomes zero, the switches 17 and 18 are turned off based on the bias voltage. As a result, the matching variable capacitor 4 and the tuning variable capacitor 5 in the matching box 3 are not automatically controlled, and only manual control is possible.
In this state, each variable capacitor is manually adjusted so that the load 7 starts discharging. When discharging is started in the load 7 by manual adjustment, the third control circuit 16 turns on the switches 17 and 18 to perform the automatic impedance matching operation again.

[0015]

As described above, the high-frequency device according to the present invention utilizes the fact that the bias voltage is superimposed on the output of the matching box when the load is discharged, and the voltage is monitored. It is configured to detect the occurrence of discharge of the load and stop the automatic impedance matching operation when the discharge is stopped, prevent the hunting operation when the discharge is stopped, and normalize only when the load is discharged. Since the feedback loop is operated, impedance matching can be normally performed in a short time.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a conventional high frequency device.

FIG. 2 is a diagram schematically showing a high frequency device according to the present invention.

FIG. 3 is a diagram showing an output voltage waveform of a matching box.

FIG. 4 is a diagram showing an output voltage waveform of a matching box.

[Explanation of symbols]

 1 High Frequency Oscillator 2 Detector 3 Matching Box 4 Matching Variable Capacitor 5 Tuning Variable Capacitor 7 Load 8, 10, 16 Control Circuit 15 Voltage Detector

Claims (1)

[Claims] 1. A high-frequency power supply, a load to which high-frequency power is supplied from the high-frequency power supply, a matching box that is disposed between the power supply and the load, and includes a matching variable capacitor, a tuning variable capacitor, and a coil, and a matching box. A detector that detects the phase difference between the high-frequency input impedance and the input high-frequency voltage and current that are input to the controller, and to automatically adjust the matching variable capacitor and the tuning variable capacitor based on the detected input impedance and phase. Automatic adjustment means, means for detecting the output voltage of the matching box, detection means for monitoring the output voltage of the matching box and detecting the occurrence of discharge in the load, and the automatic adjustment according to the signal from the detection means. A high-frequency device having means for stopping the operation of the means.