JP3014867B2 - Discharge detection device in vacuum equipment using discharge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge detecting device for detecting a discharge in a vacuum device utilizing a discharge, for example, a sputtering, an etching device or a CVD device.

[0002]

2. Description of the Related Art FIG. 5 schematically shows a conventional vacuum apparatus. An RF power source or a high-frequency power of a high-frequency power source 1 is supplied to a vacuum chamber 3 through a matching circuit 2.
Is applied to the inside electrode 4. An earth-side electrode 6 is disposed in the vacuum chamber 3 so as to face the same, and a plasma 5 is generated between the electrodes to perform operations such as sputtering and etching. In any case, it is necessary to know whether a plasma discharge has occurred.

Conventionally, this method has been divided into (1) a visual method, (2) a method of detecting a traveling wave power Pf and a reflected power Pr by a directional coupler, and (3) a self-bias voltage generated at an electrode during discharge. There is a way to detect
The method (1) cannot be handled as an electric signal, so there are various inconveniences. The method (2) is for detecting the input stage of the matching circuit, and the electrode 4 which is the final load and the ground-side electrode facing the electrode 4 There is no guarantee that a plasma discharge will occur between the two. Further, the method (3) has a disadvantage that it cannot be used in a process in which self-bias does not occur.

On the other hand, in processes such as sputtering and etching utilizing discharge, it is necessary to transmit the output of the RF power supply 1 to a load with maximum efficiency. For this purpose, a matching circuit 2 is provided. The input impedance of the matching circuit 2 is adjusted to be equal to the output impedance of the power supply 1 (50Ω). In a state where the matching is achieved, the reflected power is minimized, but this does not guarantee that the discharge has occurred on the load side.

It is required to detect the occurrence of discharge as soon as possible to increase the production of secondary products. Further, by reliably catching the occurrence of this discharge, the timing of starting the auto-matching can be accurately grasped, and the loss of operation time can be reduced.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide a discharge detecting device in a vacuum apparatus utilizing a discharge capable of automatically, promptly and reliably catching the occurrence of a discharge. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vacuum apparatus in which a high-frequency voltage from a high-frequency power source is applied to an electrode provided in a vacuum chamber to generate a plasma discharge in the vacuum chamber. A discharge detection device in a vacuum device utilizing discharge, comprising a discharge detection device for detecting the occurrence of the plasma discharge, wherein the discharge detection device is connected to an electric wire for applying the high-frequency voltage to the electrode. A high-frequency current detecting means for detecting a high-frequency current flowing in the electric wire in close proximity thereto, connected to a detection output terminal of the high-frequency current detecting means, and a higher-order harmonic frequency of a frequency component of the high-frequency power supply; A filter for mainly passing the components, and detecting that the output of the filter is equal to or higher than a predetermined level to detect the occurrence of the plasma discharge. Is achieved by the discharge detection device in the vacuum apparatus utilizing discharge that.

Alternatively, a high-frequency voltage from a high-frequency power supply is applied to an electrode provided in a vacuum chamber to detect the occurrence of the plasma discharge in a vacuum apparatus which generates a plasma discharge in the vacuum chamber. In a discharge detection device in a vacuum device using discharge, comprising a discharge detection device of
The discharge detection device is close to a wire for applying the high-frequency voltage to the electrode, a high-frequency current detection unit for detecting a high-frequency current flowing in the wire, and a high-frequency current detection unit. A low-pass filter connected to a detection output terminal for mainly passing a frequency component of the high-frequency power supply; a high-frequency ammeter for detecting the output of the low-pass filter; and a high-frequency ammeter connected to the detection output terminal, A high-pass filter for mainly passing the next harmonic frequency component, and detecting that the output of the high-pass filter is equal to or higher than a predetermined level to detect the occurrence of the plasma discharge. This is achieved by a discharge detection device in a vacuum device utilizing discharge.

[0009]

The current flowing through the electric wire is detected by a high-frequency current detecting means arranged close to the electric wire for applying a high-frequency voltage to the electrodes in the vacuum chamber, and the electric current is passed through a filter. When the output of this filter is higher than a predetermined level, it is detected that a plasma discharge is occurring, so that the plasma discharge is detected. Can be detected.

When a low-pass filter and a high-pass filter are connected to the high-frequency current detecting means, when the output of the high-pass filter exceeds a predetermined level, it is detected that plasma discharge has occurred in the vacuum chamber. However, by detecting the output of the low-pass filter, the intensity of the current component of the frequency of the high-frequency power supply is detected by the high-frequency ammeter connected to the low-pass filter, and the intensity of the plasma discharge can also be detected.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a discharge detector in a vacuum apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows an outline of the present embodiment, and the same reference numerals are given to portions corresponding to FIG. 5 showing a conventional apparatus, and the detailed description thereof will be omitted. Although shown in more detail, the matching circuit 2 includes variable capacitors C1 and C2, an inductive element L, and the like, as is well known. An electric discharge line 9 connecting the output stage of the matching circuit 2 and the electrode 4 in the vacuum chamber 3 is provided with a discharge detection device A according to the present invention. That is, the high-frequency current detecting means 11 is provided in the vicinity of the electric wire line 9, and the detection output is supplied to a low-pass filter
And a high-pass filter 13. These output terminals are respectively supplied to one input terminal of a high-frequency ammeter 17 and a comparator 15 via a buffer amplifier 14, and the other input terminal is connected to a threshold setting device 16
(Variable resistor). The output of the comparator 15 detects that a plasma discharge has occurred in the vacuum chamber 3.

According to the present invention, it has been made based on the discovery that there is a remarkable difference in the phenomenon of the current flowing in the electric wire line 9 between when a discharge is occurring and when it is not. is there.

FIG. 2 shows an oscilloscope waveform of a current flowing through the electric wire 9, and FIG. 2A shows a waveform of a current flowing through the electric wire 9 when discharge has not yet occurred. shows a 13.56MH _Z exchange is the frequency of the power supply 1, although slight ripple riding, the plasma discharge is generated, the current waveform flowing in the electrical line 9 as shown in B of FIG. 2 becomes, the harmonics have been observed that rests largely on the high-frequency component of the 13.56MH _Z.

FIG. 3 shows the frequency spectrum of the current flowing in the electric wire when no discharge is occurring and when the discharge is occurring, where A is when no discharge is occurring and a is 13.56 MHz Represents the _Z component, which is twice (2
× up frequency component b, 3 times c, 4 times d, 5 times e of 13.56MH _Z) is observed. However, when a discharge occurs using copper as a target in the vacuum chamber, a large number of harmonic components appear as shown in FIG. 3B. That is, when no discharge occurs, there is only the fifth-order frequency component as shown in A, but when the discharge occurs, a large amount of the sixth-order or higher harmonic component is generated.

In FIG. 3C, aluminum is used as a target. In this case, a large number of sixth-order and higher harmonic components are also generated in this case, but higher-order harmonic components are also generated. I have. And D of FIG. 3 is SUS as a target.
When (stainless steel) is used, higher harmonic components are generated with a greater intensity than in the case of C in FIG.

The present invention utilizes the phenomenon shown in FIGS.

FIG. 4 is a circuit diagram showing the block diagram of FIG. 1 in more detail, and portions corresponding to FIG. 1 are denoted by the same reference numerals. The discharge detection circuit A mainly includes a current detection section X, a harmonic component separation circuit Y, and a comparator section Z.

The current detector resonant circuit the inductive element L ₂ frequency 13.56MH _Z of the power supply 1 to the closed casing 40 made of copper in X, is constituted by a capacitive element C ₃ and a variable capacitance element C ₄ The output is transmitted via the coaxial cable 20 to the harmonic component separating circuit Y side. The copper casing 40 is disposed close to the electric line 9.

In the harmonic component separating circuit Y, the resistor R ₁
The low-pass filter 12 and the high-pass filter 13 described above are connected to each other via the inductive element L ₃ L ₄ and the capacitive element C ₅ in this embodiment. It is derived via R ₂ and connected to the high-frequency ammeter 17 described above.

In the present embodiment, the high-pass filter 13 includes capacitive elements C ₆ and C _{7, an} inductive element L ₅ and a resistor R _3, and the output thereof is led out through a diode D ₁ and a capacitive element C _8. outputs are voltage regulated by a variable resistor VR _4, is connected to one comparison input terminal of the aforementioned comparator 15. It is grounded through the capacitor C _9. The other comparison input terminal is connected to the DC power supply VCC through a variable resistor VR _5. This is the configuration for setting the above-described threshold voltage.

The output of the comparator 15 is a transistor Q
It is supplied to the base electrode, but for this collector is the diode D ₂ and the DC power source VCC is connected, the diode D ₂ is connected with the relay coil L ₁₀ in parallel, in proximity to this relay A contact 30 is provided for contacting one of the contacts 31, 32, and these contacts 31, 32 are connected to the input terminals of the automatic triggering device T. That relay R is constituted by a relay coil L ₁₀ and the contacts 30.

The output from the current detecting section X is supplied to the low-pass filter 12 and the high-pass filter 13, and this cut-off frequency is 4 in this embodiment.
It is set as the 0.68MH _Z.

The discharge detecting device A in the vacuum device according to the embodiment of the present invention is configured as described above.
Next, this operation will be described.

As shown in FIG. 1, 13.
Although high frequency 56MH _Z is being applied to the electrode 4 in the vacuum chamber 3 through the electrical line 9, yet when the discharge vacuum tank 3 has not occurred, the electric line 9 in FIG. 2 A When an alternating current flows as shown in FIG. 3 and is applied to a spectrum meter, a spectrum as shown in FIG. 3A is obtained.
That is, 2 of 13.56MH _Z of the fundamental frequency component a
Next-order, third-order, and fourth-order frequency components also appear, but no sixth-order or higher-order frequency components exist.

Therefore, at this time, the output of the high-pass filter 13 in FIG. 1 or FIG. 4 is almost 0, and the output of the low-pass filter 12 is amplified by the buffer amplifier 14 by passing a high-frequency current indicated by A in FIG. The high-frequency ammeter 17 measures the current intensity.

When a plasma discharge occurs, a current as shown in FIG. That is, 13.5
There is a large harmonic component with respect to the 6 MHz _Z alternating current.
A spectrum as shown by B was obtained. That fundamental frequency component and other six-order or higher harmonic components of the components up to the fifth order 13.56MH _Z when the discharge is generated a large amount generated. Therefore, this harmonic component passes through the high-pass filter 13 in FIG. 1 or FIG. 4 and is now larger than the voltage set by the threshold setting device 16, so that the comparator 15 generates a discharge confirmation signal. On the other hand, FIG.
The output of the comparator 15 in the circuit of, by being added to the base electrode of the transistor Q, which is turned on, current flows through the relay coil L _10, and sucks the contacts 30 that are disposed in proximity thereto, Although normally connected to the contact 31 side as shown in the figure, this is switched to the contact 32 side to drive the auto matching circuit T. That is, the automatic matching operation is immediately performed upon detecting the start of the discharge.

This embodiment performs the operation as described above,
In addition, it has the following effects.

That is, according to the present embodiment, the current detector X
The copper casing 40 has a built-in resonance circuit composed of an inductive element L ₂ and capacitive elements C ₃ and C ₄ , which is located close to the electric line 9 and detects the current flowing through the electric line 9. As a result, it is possible to pick up only the minimum necessary high frequency components for detecting the occurrence of discharge. Therefore, the voltage applied to the electrodes in the vacuum chamber has almost no effect.

Further, according to this embodiment, since the high-frequency ammeter 17 is connected to the low-pass filter 12, the discharge intensity can be detected, and automatic control for keeping the discharge intensity constant based on the detected value is performed. You can also. Further, according to this embodiment, by simply connecting the commercially available spectrum analyzer to the current sensor is built resonant circuit 13.56MH _Z, unnecessary radiation (spurious radiation), i.e. also be observed harmonics, thus discharging Detection can be easily performed. Further, since the discharge current can be detected, the load impedance can be estimated in real time, and the constant value (current) can be controlled. Therefore, a high-quality thin film can be formed.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical concept of the present invention.

For example, in the above embodiments, a sputtering apparatus, an etching apparatus, and a CVD apparatus have been described as vacuum apparatuses. However, the present invention can be applied to all other vacuum apparatuses utilizing discharge in other processes, and the load is undefined. Even when the discharge current is detected, a constant discharge state can be ensured.

[0032] Further, in the above embodiments, the high pass filter was to pass a 6-order or higher harmonic components of 13.65MH _Z, it is further pass harmonic or more higher harmonics Good.

Alternatively, the frequency range of the harmonic component to be passed may be determined by the material of the target in the vacuum apparatus.

[0034]

As described above, according to the discharge detecting device for a vacuum apparatus utilizing discharge of the present invention, the occurrence of discharge in a vacuum chamber can be detected quickly and reliably. Accordingly, for example, an automatic trigger operation can be automatically performed.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a vacuum apparatus using discharge according to an embodiment of the present invention.

FIG. 2 is a current waveform showing a phenomenon applied to the present invention;
Is a current waveform when discharge has not yet occurred, and B is a current waveform when discharge has occurred.

3 is a spectrum diagram of current waveforms of A and B in FIG. 2, where A is a spectrum diagram when no discharge occurs, B is a spectrum diagram when a discharge occurs when copper is used as a target, and C is a diagram. In the case where aluminum is used as a target, a spectrum diagram when a discharge occurs and D is a spectrum diagram when a discharge occurs using a stainless steel as a target.

FIG. 4 is a specific circuit diagram of the discharge detector in FIG.

FIG. 5 is a block diagram of a conventional vacuum apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 High frequency power supply 9 Electric wire path 11 High frequency current detecting means 12 Low pulse filter 13 High pulse filter 15 Comparator A Discharge detector C ₆ Capacitance element C ₇ Capacitive element L ₂ Inductive element L ₅ Inductive element R ₃ Resistance

Claims (5)

(57) [Claims] 1. A vacuum apparatus for applying a high-frequency voltage from a high-frequency power source to an electrode disposed in a vacuum chamber to generate a plasma discharge in the vacuum chamber to detect the occurrence of the plasma discharge. A discharge detection device in a vacuum device utilizing discharge, comprising a discharge detection device, wherein the discharge detection device is close to a wire for applying the high-frequency voltage to the electrode, and flows through the wire. High-frequency current detecting means for detecting a high-frequency current, and a filter connected to a detection output terminal of the high-frequency current detecting means and mainly for passing higher harmonic frequency components of the frequency component of the high-frequency power supply. Detecting the occurrence of the plasma discharge by detecting that the output of the filter is equal to or higher than a predetermined level. Discharge detection device. 2. The high-frequency current detection means includes a resonance circuit that resonates with a frequency of the high-frequency power supply.
A discharge detection device in a vacuum device using the discharge described in (1). 3. The discharge detecting apparatus according to claim 2, wherein the high-frequency current detecting means is housed in a metal case and is disposed close to the electric wire. 4. The filter according to claim 1, wherein
2. The discharge detecting device in a vacuum apparatus using discharge according to claim 1, wherein the harmonic frequency components higher than the second order are mainly passed. 5. A vacuum apparatus configured to apply a high-frequency voltage from a high-frequency power source to an electrode disposed in a vacuum chamber and generate a plasma discharge in the vacuum chamber to detect the occurrence of the plasma discharge. A discharge detection device in a vacuum device utilizing discharge, comprising a discharge detection device, wherein the discharge detection device is close to a wire for applying the high-frequency voltage to the electrode, and flows through the wire. A high-frequency current detecting means for detecting a high-frequency current, a low-pass filter connected to a detection output terminal of the high-frequency current detecting means for mainly passing a frequency component of the high-frequency power supply, and an output of the low-pass filter. High-frequency ammeter and a high-pass filter connected to the detection output terminal for mainly passing high-order harmonic frequency components of the frequency component A discharge detection device for a vacuum apparatus using discharge, wherein the detection of the output of the high-pass filter becomes equal to or higher than a predetermined level to detect the occurrence of the plasma discharge.