JP2000151329A - High frequency device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent a mismatching operation when a high-frequency output rises. A pulse signal from the modulation signal generation circuit 12, by the action of the diode D, up sharply in synchronism with the pulse signal, the falling start in synchronization with the rising edge of the high-frequency output, the resistor R ₁ and capacitor C ₁ , And the signal falls at a time constant based on the time constant, and is input to the base of the transistor Tr. Transistor Tr becomes on-state over the on period to Q ₁ this pulse signal, the period Q ₂ off condition until the next rising edge. The high-frequency signal input to the diode D of the conversion circuit 22A flows to the transistor Tr side, does not flow to the DC conversion circuit 28, and if there is no load change, the input signal and the output signal of the DC conversion circuit 28 become zero.

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 and a high-frequency etching device capable of performing impedance matching accurately and in a short time.

[0002]

2. Description of the Related Art In a high frequency sputtering apparatus, one electrode (material) is sputtered by applying a high frequency between two electrodes to generate a discharge between the two electrodes, and the sputtered particles are used as an electrode. On a substrate placed close to the substrate.

FIG. 1 schematically shows such a high-frequency device, and 1 is a high-frequency oscillator. The high frequency from the high frequency oscillator 1 passes through the detection circuit 2 to the matching box 3
Supplied to 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. Note that the detection circuit 2 includes a high-frequency impedance input to the matching box 3,
The phase difference between the voltage and the current is determined as a high-frequency signal, and the high-frequency signal determined by a DC conversion circuit (not shown) including a built-in diode and a capacitor is converted into a DC signal.

In such a configuration, an impedance and a phase difference are obtained based on the high-frequency voltage and the high-frequency current detected by the detection circuit 2, and the obtained signal of the impedance and the signal of the phase difference are temporarily converted into a DC signal. Thus, the capacity of the matching variable capacitor 4 in the matching box 3 is changed based on the value of the impedance, and the capacity of the tuning variable capacitor 5 is changed based on the phase difference.

That is, the impedance Z from the detection circuit 2
Is supplied to a comparison amplifier 8 and compared with a reference voltage. The output of the comparison amplifier 8 is supplied to a 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 DC signal _Vθ corresponding to the phase difference θ from the detection circuit 2 is supplied to a comparison amplifier 10 and compared with a reference voltage. The output of the comparison amplifier 10 is supplied to a motor 11 that drives the tuning variable capacitor 5. As a result, the tuning variable capacitor 5 is adjusted by the motor 11 so that the value of the phase difference θ becomes equal to the reference voltage (0).

[0007]

In such a high-frequency device, when, for example, an arc discharge occurs on the material to be sputtered under the load 7, large particles fall from the material to be sputtered onto the substrate. As a result, the quality of the film formed on the substrate deteriorates. Therefore, the high-frequency output from the high-frequency oscillator 1 is modulated by a pulse signal ((a) in FIG. 2) from the modulation signal generating circuit 12 and a signal that repeatedly turns on and off in a pulsed manner (FIG. 2).
(B)), even if an arc discharge occurs during a certain on-period of the high-frequency output, it disappears in the next off-period.

In general, the high-frequency output changes transiently during a short period A from when the high-frequency output is turned on until a stable plasma discharge is reached, so that the matching state is broken during the short period. Large reflected power (FIG. 2C) is generated. Incidentally, when the high-frequency output falls (off), reflected power that is negligibly small is generated. However, the large reflected power is generated only for a short period A when the high-frequency output is turned on. Does not occur unless there is a change.

Therefore, if the high-frequency output is turned into a signal that repeatedly turns on and off as described above, a large reflected power is generated every time the high-frequency output is turned on. At this time, during each reflected power generation period, the impedance signal and the phase difference signal detected by the detection circuit 2 (for convenience of description, referred to as a detected high-frequency signal, an example of a signal waveform thereof is shown in FIG. 2D). As described above, in the detection circuit 2, the signal should be converted into a DC signal by a DC conversion circuit (not shown) including a diode and a capacitor. However, actually, while the voltage based on the detected high-frequency signal charged in the capacitor is not completely discharged, the next reflected power is generated. Therefore, the output signal of the detection circuit 2 is shown in FIG. As shown, between each rising edge of the high-frequency output, 0
, And a signal having a waveform rising slightly to the right and falling downward to the right. Even if the original matching is obtained in the period B (the period in which the high-frequency output is on and the period A is excluded) ( That is, the matching deviation based on the load fluctuation is eliminated), and the signal is as if the matching has not been achieved. Therefore, during the high-frequency output ON period, the motors 9 and 11 of the matching box 3 rotate, and during this period, matching does not occur due to load fluctuation, or matching occurs after the matching deviation due to load fluctuation occurs. , The matching will be deviated.

The present invention has been made to solve such problems, and an object of the present invention is to provide a novel high-frequency device.

[0011]

A high-frequency device according to a first invention includes a high-frequency power supply, a modulation circuit for modulating a high-frequency output from the high-frequency power supply, a load to which the modulated high-frequency output is supplied, a high-frequency power supply and a load. And a matching box including a matching variable capacitor and a tuning variable capacitor, and an input impedance provided between the high-frequency power supply and the matching box.
Equipped with a detection circuit that calculates the phase of the input high-frequency voltage and current, adjusts the capacitance of the matching variable capacitor according to the impedance determined by the detection circuit, and adjusts the capacitance of the tuning variable capacitor according to the phase determined by the detection circuit. A high-frequency device configured to adjust a high-frequency signal corresponding to the determined impedance and a high-frequency signal corresponding to the determined phase, respectively, into a DC signal. When performing the matching based on the DC signal, the matching operation based on the reflected power detected when the high-frequency output rises is not performed.

A high-frequency device according to a second aspect of the present invention includes a high-frequency power source, a modulation circuit for modulating a high-frequency output from the high-frequency power source, a load to which the modulated high-frequency output is supplied, and a high-frequency power source and a load. A matching box comprising a matching variable capacitor and a tuning variable capacitor, and a detection circuit provided between the high-frequency power supply and the matching box, for determining the input impedance and the phase of the input high-frequency voltage and current are provided. A high-frequency device configured to adjust the capacitance of the matching variable capacitor according to the determined impedance and adjust the capacitance of the tuning variable capacitor according to the phase determined by the detection circuit, wherein the detection circuit includes a reflection circuit. A rectifier circuit that rectifies high-frequency signals based on electric power,
A DC conversion circuit that converts the output of the rectifier circuit into a DC signal; and a transistor circuit that cuts off input of a high-frequency signal based on reflected power generated at the time of rising of the high-frequency output to the DC conversion circuit. The matching is performed on the basis of the output signal.

A high-frequency device according to a third aspect of the present invention is characterized in that the modulation circuit modulates a high-frequency output from a high-frequency power supply into a pulse.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 shows an example of the high-frequency device according to the present invention. In the figure, components denoted by the same reference numerals as those in FIG. 1 are the same components. In this embodiment, the configuration of the detection circuit is different from that of the device of FIG.

That is, the detection circuit 20 comprises an arithmetic circuit 21 for obtaining an impedance and a phase difference based on the detected high-frequency voltage and high-frequency current, as in the prior art (the apparatus shown in FIG. 1). The conversion circuits 22A and 22B convert the high-frequency signal representing the phase difference and the high-frequency signal representing the phase difference into DC signals, respectively. The configuration of these conversion circuits is the same as that of the DC conversion circuit (not shown) forming the detection circuit 2 in FIG. different. Hereinafter, the conversion circuit will be described.

FIG. 4 shows an example of a conversion circuit, which includes a diode 23, a DC conversion circuit 28 comprising a diode 26 and a capacitor 27, a transistor Tr and a resistor R.
₁ , a transistor circuit 29 comprising a capacitor C ₁ , a diode D and a resistor R ₂ . A pulse signal ((a) in FIG. 5) from the modulation signal generating circuit 12 is input to a positive connection point between the diode D of the transistor circuit 29 and the resistor R2. The diode D of the transistor circuit
Means that the input pulse signal rises sharply and the resistance R
₁ and is intended to operate as falls with a time constant based on the capacitor C _1. Thus, in the detection circuit 20, the arithmetic circuit 21 calculates the impedance and the phase difference based on the detected high-frequency voltage and high-frequency current. Both the impedance and the phase difference are high-frequency signals, and are converted into DC signals by the high-frequency signal 22A representing the impedance, and the high-frequency signals representing the phase difference are converted into DC signals by the conversion circuit 22B. The DC signal Vz corresponding to the impedance from the detection circuit 20 is supplied to the comparison amplifier 8 and compared with a reference voltage. The output of the comparison amplifier 8 is supplied to a 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 DC signal _Vθ corresponding to the phase difference θ from the detection circuit 20 is supplied to the comparison amplifier 10 and compared with a reference voltage. The output of the comparison amplifier 10 is supplied to a motor 11 that drives the tuning variable capacitor 5. As a result, the tuning variable capacitor 5 is adjusted by the motor 11 so that the value of the phase difference θ becomes equal to the reference voltage (0).

A high-frequency output from the high-frequency oscillator 1 is a signal (FIG. 5 (b)) which repeatedly turns on and off in a pulsed manner by a pulse signal (FIG. 5 (a)) from the modulation signal generating circuit 12. Is modulated. At this time, during the rising period A of each high-frequency output, the matching state is broken and large reflected power ((c) in FIG. 5) is generated.

At this time, during each reflected power generation period, the impedance signal and the phase difference signal from the arithmetic circuit 21 are converted by the conversion circuits 22A and 22B as follows. Since these conversion circuits perform the same operation, for convenience of explanation, the impedance signal and the phase difference signal from the arithmetic circuit 21 are referred to as detected high-frequency signals (an example of the signal waveform is shown in FIG. 5D). The operation of one of the circuits (in this case, a high-frequency signal representing impedance) will be described.

The diode D of the transistor circuit 29
The pulse signal ((a) in FIG. 5) from the modulation signal generating circuit 12 which is input to the positive side connection point of the resistor R2 and the pulse signal ((a) in FIG. synchronization with rising steeply, the high-frequency output in synchronization with the rising (in (b) FIG. 5) of the beginning falling, resistors R ₁ and falls at the time constant based on the capacitor C ₁ (in FIG. 5 (e)) And input to the base of the transistor Tr. Incidentally, the fall period is the capacitance value of the resistance value and the capacitor C ₁ of the resistor R ₁ to be equal to the fall period A of the high frequency power is selected.

[0021] By By such pulse signal (in FIG. 5 (e)) is input to the base, the transistor Tr becomes ON state over the on period to Q ₁ this pulse signal, the period until the next rising the state of off Q _2.

Accordingly, the high-frequency signal (FIG. 5 (d)) input to the diode D of the conversion circuit 22A flows to the transistor Tr side and does not flow to the DC conversion circuit 28. The input signal and the output signal of the conversion circuit 28 become 0 ((f) and (g) in FIG. 5). as a result,
The reflected power generated when the high-frequency output rises is cut off, and the rotation of each of the motors 9 and 11 of the matching box 3 based on the reflected power generated during the high-frequency output rising period is lost. Is not lost.

When the reflected power (H in FIG. 5 (h)) due to the load fluctuation occurs in the on period B except the rising period A of the high frequency output, the transistor Tr is turned off in the period B. The detected high-frequency signal (S in FIG. 5 (i)) based on the reflected power (H in FIG. 5 (h))
The input signal (FIG. 5 (j)) is converted by the DC converter 28 into a DC signal (FIG. 5 (k)).
This signal is sent to the comparison amplifiers 8 and 10, and the normal matching as described above is performed.

[Brief description of the drawings]

FIG. 1 schematically shows a conventional high-frequency device.

FIG. 2 shows a waveform of each signal.

FIG. 3 shows an example of a high-frequency device for implementing the present invention.

FIG. 4 shows some details of the device shown in FIG.

FIG. 5 shows a signal waveform in the device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 High frequency oscillator 3 Matching box 4 Matching variable capacitor 5 Tuning variable capacitor 6 Coil 7 Load 8,10 Comparison amplifier 9,11 Motor 12 Modulation signal generation circuit 20 Detection circuit 21 Arithmetic circuit 22A, 22B Conversion circuit 25,26 Diode 27 Capacitor 28 DC conversion circuit Tr transistor D diode R ₁ , R ₂ resistor C ₁ capacitor

Claims (3)

[Claims] 1. A high-frequency power supply, a modulation circuit for modulating a high-frequency output from the high-frequency power supply, a load to which the modulated high-frequency output is supplied, and a matching variable capacitor and a tuning variable capacitor disposed between the high-frequency power supply and the load. And a detection circuit provided between the high-frequency power supply and the matching box, the detection circuit obtaining the input impedance and the voltage and current phases of the input high-frequency power, and matching in accordance with the impedance obtained by the detection circuit. A high-frequency device configured to adjust the capacity of a variable capacitor and adjust the capacity of a tuning variable capacitor according to a phase obtained by a detection circuit, wherein the detection circuit obtains a high-frequency signal corresponding to the obtained impedance. Converts high-frequency signals corresponding to the specified phases to DC signals respectively A high-frequency device that performs a matching operation based on the reflected power detected when the high-frequency output rises when performing matching based on the DC signal. 2. A high-frequency power supply, a modulation circuit for modulating a high-frequency output from the high-frequency power supply, a load to which the modulated high-frequency output is supplied, and a matching variable capacitor and a tuning variable capacitor disposed between the high-frequency power supply and the load. And a detection circuit provided between the high-frequency power supply and the matching box, the detection circuit obtaining the input impedance and the voltage and current phases of the input high-frequency power, and matching in accordance with the impedance obtained by the detection circuit. A high-frequency device configured to adjust a capacity of a variable capacitor and adjust a capacity of a tuning variable capacitor according to a phase obtained by a detection circuit, wherein the detection circuit rectifies a high-frequency signal based on reflected power. Rectifier circuit, DC converter circuit that converts the output of the rectifier circuit into a DC signal, high frequency A high frequency signal based on the reflected power generated at the time of rising of the wave output, comprising a transistor circuit for blocking input to the DC conversion circuit, and performing matching based on an output signal of the detection circuit. A high-frequency device characterized by the above-mentioned. 3. The high-frequency device according to claim 1, wherein the modulation circuit modulates a high-frequency output from a high-frequency power supply in a pulse shape.