JPH079335Y2 - Discharge trigger - Google Patents

Description

[Detailed Description of the Invention] The present invention is an auxiliary device for facilitating the start of discharge of a main electrode in a device for performing thin film processing by generating plasma in a vacuum such as sputtering, sputter etching, plasma CVD, and ion plating. The present invention relates to the structure of electrodes. FIG. 1 shows the construction of an RF sputter etching apparatus showing an embodiment of the apparatus used in the present invention. Vacuum container 10
An RF electrode assembly 20 is provided inside. Gas is supplied to the vacuum vessel through the introduction valve 12 in the direction of arrow 12 ',
This gas is further exhausted through the exhaust pipe 11 in the direction of arrow 11 '. A quartz etching table 22 is placed on the RF electrode 21, and a sample 23 to be etched is placed on the quartz etching table 22. The surface of the RF electrode that is not in contact with the etching table is surrounded by the shield 24. The RF electrode is also electrically insulated from the vacuum container at earth potential by the insulator 25 and
It is connected to the RF power supply 26. Further auxiliary electrode in the vacuum container
30 are provided. When a voltage is applied to the auxiliary electrode and then power is supplied to the RF electrode, which is the main electrode, the discharge at the main electrode starts stably and reliably.

FIG. 2 shows a conventionally used auxiliary electrode. In the figure, a high-voltage rod-shaped electrode 32, which is insulated by an insulator 31 and vacuum-sealed, is attached to the vacuum chamber wall 13. A permanent magnet 33, which is electrically insulated from the high voltage electrode 32, is provided on the outer periphery of the root of the high voltage electrode 32. The atmosphere side of the high voltage electrode 32 is surrounded by a safety cover 34 to prevent danger. A high voltage is supplied to the high voltage electrode 32 from an external ignition coil or other high voltage power supply 35 via a power supply line 351, and discharge is performed. The auxiliary electrode of such a conventional structure has a permanent magnet provided in a vacuum and gas is released from the magnet.
This is not preferable especially when the impurity gas must be suppressed. In order to ensure the start of discharge, it is necessary to make the strength of the magnetic field generated by the space near the high-voltage electrode sufficiently strong by the permanent magnet 33. This is because the permanent magnet 33 has a larger volume. Although it can be easily achieved, it is not preferable for the original device that the auxiliary electrode becomes too large. Further, in order to secure the insulation between the permanent magnet 33 and the rod-shaped electrode 32, it is necessary to make the gap between them large enough, and there is a limit to making the auxiliary electrode smaller than the whole device.

The first object of the present invention is to provide a structure of the auxiliary electrode which is free from the emission of impurity gas. The second object of the present invention is to provide a structure of the auxiliary electrode which is very small as compared with the entire device. In particular, it is to provide a structure that reduces the vacuum volume of the auxiliary electrode portion. A third object of the present invention is to provide a magnet arrangement with a simple structure for generating a magnetic field that makes discharge initiation reliable and easy.

Hereinafter, the discharge trigger of the present invention will be described with reference to examples.

FIG. 3 shows an embodiment of the structure of the auxiliary electrode according to the present invention.
In the figure, two annular permanent magnets 33 are arranged opposite to each other outside the vacuum so as to sandwich the rod-shaped electrode 32. Opposing magnetic pole surfaces of the pair of permanent magnets have the same pole, and are provided so that the magnetization axis is perpendicular to the central axis 321 of the rod-shaped electrode.
Magnetic field lines 331 emitted from the magnetic pole face excite a strongly curved magnetic field in the space around the rod-shaped electrode.

FIG. 4 is a sectional view taken along the line AA of FIG.

The auxiliary electrode having this structure has the following effects.

Since the permanent magnet is provided outside the vacuum container, there is no possibility that the impurity gas in the vacuum container due to the gas release from the magnet increases and the etching characteristics are adversely affected.

As compared with the conventional structure shown in FIG. 2, there is no strict restriction on the size of the permanent magnet, so that it is possible to excite a strong magnetic field in the space near the rod electrode by enlarging only the magnet. As a result, the volume of the auxiliary electrode can be reduced as a whole to surely and easily start the discharge.

Since the opposing permanent magnets generate complicatedly curved high-density magnetic field lines in the discharge trigger space in the vicinity of the periphery of the rod-shaped electrode, the start of discharge is much more intense than in the case of the conventional relatively uniform magnetic field lines of FIG. You can easily.

The industrial value of the present invention, which has the above-mentioned remarkable effects due to its simple and inexpensive structure, is extremely high.

[Brief description of drawings]

FIG. 1 shows an example of the structure of a sputter etching apparatus using the discharge trigger of the present invention. FIG. 2 shows the structure of a conventional auxiliary electrode, FIG. 3 shows the cross-sectional structure of the auxiliary electrode according to the present invention, and FIG. 4 shows the cross section taken along the line A--A in FIG. In the figure
10 is a vacuum container, 20 is a main electrode, 30 is an auxiliary electrode, 31 is an insulator,
32 is a rod-shaped high-voltage electrode, 33 is a permanent magnet, 34 is a high-voltage safety protection cover, 35 is a high-voltage power supply, 321 is the central axis of the rod-shaped electrode, 331 is the magnetic field line,
Reference numeral 351 represents an electrical wiring between the high voltage electrode and the rod-shaped electrode.

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Claims (1)

[Scope of utility model registration request] 1. A discharge trigger provided in an apparatus for generating plasma in a vacuum to perform thin film processing such as sputtering, wherein a rod-shaped electrode connected to a high-voltage power source outside the vacuum vessel of the apparatus and an outside of the vacuum vessel. A permanent magnet having a magnetization axis perpendicular to the central axis of the rod-shaped electrode and having the same poles facing each other across the rod-shaped electrode; A discharge trigger characterized by being incorporated in the vicinity of the main electrode.