JPS61202438A - Glow discharge stabilizing method - Google Patents

Abstract

PURPOSE:To obtain a stable glow discharge by providing phase controlling function in a plurality of RF power sources, and supplying powers of different phases from the power sources to discharging loads, thereby preventing an abnormal discharge. CONSTITUTION:Powers are supplied from RF power sources 7-11 of five systems to magnetron cathodes 2-5 provided in a vacuum chamber 1 and rotatable drum type etching electrode 6. Here, an RF reference signal obtained from one crystal oscillator 12 is supplied by a master oscillator 14 to the power sources 7-11. The RF power amplified by an amplifier 15 is transmitted through impedance matching circuits 16-20 to the cathodes 2-5 and the electrode 6. Automatic phase control units 22 provided in four power sources 8-11 monitor the phases of the RF voltage in the cathode 2 and detected by a phase detecting sensor 21 to control the both phase difference to the prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of obtaining a stable glow discharge in a vacuum apparatus using RF glow discharge such as a sputtering or dry etching apparatus.

(Prior art) In general, in an FC vacuum device that utilizes glow discharge, an equivalent circuit of a power thread α for one discharge load can be expressed as t - the circuit shown in Figure 1, and a high frequency power source a is connected to a discharge load b.
Power is supplied through the impedance matching circuit of. In such F & GE, there is a bus circuit CD- through which the return current IX- flows from the power introduction part (A'-0) from the impedance matching circuit 0 to the discharge load and from the discharge load to the impedance matching circuit Pf' a. 11') is extremely important in order to obtain a stable glow discharge 'i'.

(The point that the invention is trying to solve) M# of the previous lat force introduction Zheng (between A'-0)! Normally, the impedance matching circuit C is directly connected by a single O plate or coaxial tube with a large surface type placed close to the electrode that supplies the electric power, so if the layout design is faithful to the basics,
There is no particular cause of instability in glow discharge.

However, the pass circuit (between D and B') is damaged due to the combination of various components such as the earth shield installed at the 11L pole, the vacuum chamber wall, and the electrode shield cover installed on the atmosphere side. If several electrodes with a large load capacity, that is, a large IL, are used at the same time, the combination becomes even more complex in a device that simultaneously uses multiple discharge loads via plasma. The value also increases. Therefore, in such devices, abnormal discharges such as spark discharges are likely to occur in the vacuum chamber, and conventional technology has been unable to prevent such abnormal discharges.
In order to obtain a stable gummy discharge, there are methods other than adding more pass circuits and changing the constituent materials of the pass circuit to ones with low impedance. Nakatsu ratio.

It is an object of the present invention to provide a method for preventing abnormal discharge and obtaining stable glow emission regardless of the complicated WG or capacitance of a pass circuit for a shaft-mounted cage with a number of discharge loads. 0 (Means for solving the problem) In the present invention, power is supplied from the R7 power supply to a number of discharge loads in the vacuum chamber through impedance matching circuits, respectively,
In the device in which glow discharge is generated between the discharge loads, the RF power supply has R? A phase control function is provided to make the phases of the voltage waveforms match each other.

(Function) The function of the present invention will be explained in the case where two systems of discharge loads shown in FIGS. 2 and 3 are used simultaneously. FIG. 2 shows a case where the phase difference between the RF voltage waveforms applied to the two electrodes is 0°, and the third factor is a case where the phase difference is 180°. In all of these cases, the RF voltage applied to each electrode is Do on the negative side.
Since the ions in the plasma have low mobility, they are attracted to this DO bias and slow down for 9s.
move. Electrons in the plasma have a large degree of mobility, and are drawn to or moved from the electrode depending on the voltage waveform on the pole side.

In the case of Figure 2, if the voltages applied to both electrodes are on the negative side, to simplify it, the electrons will be repelled from both electrodes, and most of them will flow into the ground part such as the vacuum chamber wall. Become.

However, as in the case shown in the third diagram, when the voltage waveform of the -10,000 'ttt electrode goes to the negative side and the voltage waveform of the other 11L Yuzu goes to the positive side, the electrons are ejected from the 10,000' electrode side. It will be repelled and attracted to the other electrode. Therefore, most of the electrons go back and forth between the two electrodes, and the number of electrons flowing into the ground portion of the vacuum chamber bottle or the like is greatly reduced.

Grounded parts such as walls of vacuum chambers usually have a certain degree of impedance from a high-frequency perspective, and if a large number of electrons flow here, it will be easy to generate constant discharge, making the plasma unstable. cause In experiments, it has been found that in the case of Fig. 2, abnormal discharge is likely to occur with the trowel, but in the case of Fig. 3g3, almost no abnormal discharge occurs, and the most stable gwar discharge iIc can be obtained. -I was bitten.

Although the phase difference differs depending on the number of discharge loads used simultaneously, stable gummy discharge can be obtained very easily by providing the Ry power source with a phase control function.

In the conventional method that does not have a phase control function t-i in the RF power supply,
Each 'IIL! The phase difference of the voltage waveform of the RF power supplied to the IA is generated by each 11L#! ? It is extremely difficult to control to a specific preferred state, as it depends on the timing of starting, the dimensions of the power source, impedance matching circuit, load, and wiring conditions.

(Embodiment) An uninvented embodiment is shown in FIG. 4, in which four large magnetron cathodes and one large drum-shaped etching electrode a! 1 when applied to an R7 bias sputtering device with t-t! Stare at me.

In Figure 4, (1) is the vacuum chamber to be evacuated, (2)
+31141 +53 is a large magnetron cathode provided in the vacuum chamber (61i is a large drum-shaped etching electrode rotatably provided in the chamber opposite each magnetron cathode (2) to (5)) .Each cathode and electrode is supplied with power from an RF power source (81 (9) QG (11)) with a maximum output of 15 KW of 5 threads. , the Rv reference signal α4 obtained from one crystal oscillator α2 is supplied from the master oscillator α4, so that each power source becomes the same oscillating 114 wave and performs phase control.

Amplify up to +9r value with each power supply (I5! amplified R
F power is impedance matching circuit α61 (17) αu
sC! IIt- is transmitted to each cathode and electrode and used for sustaining the discharge.

A phase detection sensor (211) is provided on the load side of each impedance matching circuit αto 1, that is, at the connection portion with the cathode and ICM, and in the embodiment, an automatic phase control unit @ I connected it.

Each unit @ has the function of monitoring the phase of the RF voltage at the cathode (2) and the phase of the RF voltage of the cathode or electrode corresponding to the sensor υ, and controlling the plane phase difference to a set value. has.

In the case of having five independent discharge loads as shown in the figure,
Each R depends on whether you use the same system at the same time. The method of setting the phase difference of the power supply is different, but for example, the cathode (
When discharging to four of 21 to (5), cathode (2)
The phase difference of the cathode (4) is set to 0 for the RF voltage waveform of
8. Control the phase difference between cathodes (3) and (5) to t-180°. In this case, each cathode (2) to (5) has 1
An extremely stable glow discharge was obtained even when a power of 0 W or more was supplied. However, when all the phase differences between the cathodes (2) to (5) were set to O'tC&9, abnormal discharge occurred frequently just by supplying power of I KW to each cathode.

In addition, 5 pieces of each cathode (2) to (5) and electrode (6)
When discharging all, the phase difference between the cathodes 131 (4) (5) with respect to the RF voltage waveform of the cathode (2) is 0°,
Electron m (6J phase difference 1 to 180° control or cathode (21 R?voltage wave to cathode (4)
Upper phase difference 0°, cathode (3) + 5)' (phase difference 12
0°, 11L & (by controlling the 6Jt phase difference to 240°), the extremely stable glow discharge is superior at high input power.

(Effects of the Invention) As described above, in the present invention, each RF power source of the mantissa is provided with a phase control function, so that all the power with different phases is supplied from each RF power source to each discharge load. RF
It is possible to obtain a glow discharge tt-, no abnormal discharge occurs even when a relatively large power is supplied, and the defective product incidence of the conductor device processed in a vacuum apparatus having a discharge load t- of II number is reduced. There is an effect such as decreasing the amount.

[Brief explanation of the drawing]

Figure 1 is an equivalent circuit diagram of the power system of a conventional vacuum device using glow discharge, Figures 2 and 5 are diagrams for detailed explanation of the invention, and Figure 4 is an embodiment of the present invention. 0ill...Vacuum Presentation12+ 131(4)+51 +61...Discharge load (July 81 +9) αQltllJ...R
? Power supply (lbl (171 (16 (II Ca)...
... Impedance matching circuit patent applicant: Japan Vacuum Engineering #2 people outside the company

Claims (1)

[Claims] In a system in which power is supplied from an RF power supply to a plurality of discharge loads in a vacuum chamber through respective impedance matching circuits, and glow discharge is generated between the discharge loads, the R
A method for stabilizing glow discharge, characterized in that an F power source is equipped with a phase control function that makes the phases of RF voltage waveforms for each discharge different from each other.