JPH06119997A - High frequency generating device - Google Patents

Abstract

PURPOSE:To prevent ill influence upon a thin film. CONSTITUTION:When an arc is generated in a plasma producing chamber 18, the plasma load becomes low impedance, and a serial resonance is generated by a capacitor 23 and inductor 21. A current transformer 22 senses the resonant current due to this serial resonance, and a control circuit 12 restricts the power supplied to the plasma producing chamber 18, so that the arc extinguishes in a short time before it grows.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency generator for supplying electric power to a plasma reactor to generate high frequency discharge.

[0002]

2. Description of the Related Art As a conventional high frequency generator, for example, there is one as shown in FIG. That is, the high frequency generator 1 includes a control circuit 2 and a detection circuit 3, and the operation of the high frequency generator 1 is such that when an arc is generated in the plasma generation chamber 8, the detection circuit 3 detects the arc generation and The detection signal is transmitted to the control circuit 2, and the output of the high frequency generator 1 is reduced or temporarily stopped (tens of msec) to extinguish the arc.

[0003]

However, in such a conventional high-frequency generator, the detection circuit 3 has a voltage standing wave ratio.
ratio: VSWR), and the reflected power is detected. Therefore, after the arc is generated, the arc grows until the reflected power is generated, and the growth of the arc causes the thin film to be formed on the substrate. There was a problem that it adversely affected.

The present invention has been made by paying attention to such a conventional problem. The arc generation is not detected by the reflected power of VSWR, so that the arc is generated in a short time before the arc grows. It is an object of the present invention to provide a high frequency generator capable of extinguishing an arc and preventing an adverse effect on a thin film.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the gist of the present invention is to provide a high-frequency generator for supplying high-frequency discharge to a plasma reactor (18) to generate the high-frequency discharge. An arc current detection circuit (20) connected in parallel with an electrode (19) of the device (18) and capable of detecting an arc current, and based on a detection signal of the arc current detection circuit when an arc occurs during plasma generation. And a control circuit (12) for limiting the power supply to the plasma reactor (18) and for removing the power supply limitation after the arc is extinguished, wherein the arc current detection circuit (20) supplies the arc current. Current transformer for detection (2
2) A capacitor (23) and an inductor (21) are connected in series, which is a high-frequency generator.

[0006]

When an arc is generated in the plasma reactor (18), the plasma load becomes low impedance close to zero, and the capacitor (23) and the inductor (21) cause series resonance. The current transformer (22) detects the resonance current due to the series resonance, and the control circuit (12) supplies electric power to the plasma reaction device (18) for a fixed time (tens of microseconds).
The arc can be extinguished in a short time before the arc grows by stopping (~ several hundreds of microseconds) to prevent the thin film from being adversely affected.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the present invention. As shown in the figure, an electrode 19 for plasma generation is provided in a plasma generation chamber 18 which is a plasma reactor.
An oscillation source 11 is connected to 9 via a control circuit 12, a reflected power detection circuit 13, and a matching box 14.

The matching box 14 includes the inductor 1
5, 21, capacitors 16, 17, 23 and a current transformer 22. An inductor 15 is connected to the reflected power detection circuit 13, and the inductor 15 is connected to the electrode 19 via a capacitor 16. Reflected power detection circuit 13
One end of the capacitor 17 is connected to
The other end of is grounded.

The inductor 21, the current transformer 22, and the capacitor 23 constitute an arc current detection circuit, the inductor 21 and the capacitor 23 are connected via the current transformer 22, and one end of the inductor 21 is connected to the electrode 19. Connected,
One end of the capacitor 23 is grounded. Current transformer 2
2 is connected to the control circuit 12.

Next, the operation will be described. Inductor 15 and capacitors 16 and 17 in matching box 14
Serves to perform impedance matching between the high frequency generator and the plasma load. And inductor 2
Since 1 is used, the impedance matching is not affected by the capacitor 23.

The inductor 21 and the capacitor 23 function to cause series resonance when an arc is generated. The current transformer 22 functions to detect the series resonance current. The control circuit 12 functions to stop the electric power supplied to the plasma generation chamber 18 for a certain period of time according to the detection signal from the current transformer 22.

As shown in FIG. 2, in the voltage waveform of the electrode 19, the plasma generation chamber 18 normally has a negative potential (-V _DC ).
Have. Assuming that the plasma impedance when an arc is generated at t ₁ is 0 [Ω], the inductor 2
1 and the capacitor 23 cause series resonance, and the frequency thereof is f = 1 / [2π√ (LC)]. However, L,
C indicates the inductance of the inductor 21 and the capacitance of the capacitor 23, respectively. The current of the capacitor 23 is as shown in FIG.

At t ₂ , the capacitor current is detected by the current transformer 22, and the control circuit 12 stops the power supply to the plasma generation chamber 18 in a short time (several μsec).

At t ₃ after the arc is extinguished, the control circuit 12 reactivates the high frequency generator and the plasma shifts to normal. Stop time [T] of high frequency generator is several tens of μs
ec to several hundred μsec. The series resonance frequency is selected from several tens to several hundreds of kHz.

In the high frequency generator, a DC power source 24 may be used as a bias, as shown in FIG. In this case, the capacitor 16 functions to block the voltage of the DC power supply 24, and the inductor 21 functions to block the high frequency voltage.

[0016]

According to the high frequency generator of the present invention, when an arc is generated in the plasma reactor, the plasma load has a low impedance and the capacitor and the inductor cause series resonance. The current transformer detects the resonance current due to the series resonance, and the control circuit limits the power supply to the plasma reactor, so that the arc extinguishes in a short time before it grows, It is possible to prevent adverse effects.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a high frequency generator showing an embodiment of the present invention.

FIG. 2 is a waveform diagram of a voltage of an electrode of a plasma generation chamber, showing an embodiment of the present invention.

FIG. 3 is a waveform diagram of a current of a capacitor of an arc current detection circuit according to an embodiment of the present invention.

FIG. 4 is a circuit diagram of a high frequency generator showing an embodiment of the present invention.

FIG. 5 is a circuit diagram of a conventional high frequency generator.

[Explanation of symbols]

 11 ... Oscillation source 15, 21 ... Inductor 12 ... Control circuit 13 ... Reflected voltage detection circuit 14 ... Matching box 16, 17, 23 ... Capacitor 18 ... Plasma generation chamber (plasma reactor) 19 ... Electrode 22 ... Current transformer 24 ... DC bias power supply

Claims (1)

[Claims] 1. A high-frequency generator for supplying electric power to a plasma reactor to generate a high-frequency discharge, an arc current detection circuit connected in parallel with an electrode of the plasma reactor and capable of detecting an arc current, and a plasma generator. When an arc occurs in the, limiting the power supply to the plasma reactor based on the detection signal of the arc current detection circuit, and, and comprising a control circuit for releasing the restriction of the power supply after arc extinction, The arc current detection circuit comprises a current transformer for detecting an arc current, a capacitor and an inductor which are connected in series.