JPH035081Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an auxiliary electrode structure that facilitates the start of discharge from the main electrode in equipment that generates plasma in vacuum to process thin films, such as sputtering and plasma CVD ion plating. It is related to. FIG. 1 shows the configuration of an RF sputter etching apparatus showing an embodiment of the apparatus used in the present invention. An RF electrode assembly 20 is provided inside the vacuum vessel 10. Gas is supplied to the vacuum vessel through an inlet valve 12 in the direction of arrow 12', and this gas further passes through an exhaust pipe 11 in the direction of arrow 11'.
is exhausted in the direction of A quartz etching table 22 is placed on the RF electrode 21, and a sample 23 to be etched is placed on top of the quartz etching table 22.
The surface of the RF electrode not in contact with the etching table is surrounded by a shield 24. Further, the RF electrode is electrically insulated from the vacuum container at ground potential by an insulator 25 and connected to an RF power source 26.
The vacuum vessel is further provided with an auxiliary electrode 30. When voltage is applied to the auxiliary electrode and then power is supplied to the RF electrode, which is the main electrode, 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 insulated by an insulator 31 and vacuum-sealed is connected to a vacuum container wall 13.
installed on. A permanent magnet 33 electrically insulated from the high voltage electrode 32 is provided around 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 source 35 via a power supply line 351 to cause discharge. In an auxiliary electrode having such a conventional structure, the permanent magnet is provided in a vacuum, and gas is released from the magnet, so this is not preferable, especially when impurity gas must be suppressed. In addition, in order to ensure the start of discharge, it is necessary to make the strength of the magnetic field generated by the permanent magnet 33 in the space near the high voltage electrode sufficiently strong, and this is because the volume of the permanent magnet 33 is large. Although this can be achieved more easily, it is not desirable for the auxiliary electrode to become too large for the original device. Furthermore, in order to ensure insulation between the permanent magnet 33 and the rod-shaped electrode 32, it is necessary to make the gap between them sufficiently large, and there is a limit to how small the auxiliary electrode can be compared to the entire device.

The first object of the present invention is to provide an auxiliary electrode structure that does not release impurity gas. A second purpose is to provide a very compact auxiliary electrode structure compared to the main body of the device. In particular, it is an object of the present invention to provide an auxiliary electrode structure in which the internal volume of the vacuum vessel is hardly increased by attaching the auxiliary electrode, and the shape of the interior of the vacuum vessel is not complicated. A third object is to provide an auxiliary electrode structured in combination with a gas inlet in order to generate a magnetic field that will ensure and facilitate the initiation of discharge.

Hereinafter, the discharge trigger of the present invention will be explained with reference to Examples.

FIG. 3 shows an embodiment of the structure of the auxiliary electrode according to the present invention. Components that are the same as in FIG. 2 are designated by the same reference numerals. In the figure, an annular permanent magnet 33 is provided outside the vacuum. Further, the magnetic poles of the permanent magnet are provided so that the direction of magnetic lines of force 331 emanating from the magnetic poles are orthogonal to the central axis 321 of the rod-shaped high voltage electrode 32.
An inlet 121 for introducing gas into the vacuum container is provided very close to the rod-shaped electrode 32, and is indicated by an arrow 12'.
Gas is introduced along. Therefore, when using the auxiliary electrode of the present invention, gas is introduced into the vacuum container through the inlet 121 instead of providing a gas introduction valve at a separate and independent position from the auxiliary electrode as in the embodiment shown in FIG. A gas introduction valve is provided in the connected piping. As a result, when the present invention is used, the gas introduced into the vacuum container necessarily passes through the space around the rod-shaped electrode. For this reason, the pressure around the rod-shaped electrode can be made higher than in other places in the vacuum container, making it extremely easy to discharge.

The structure of the present invention provides the following effects.

Since the permanent magnet is provided outside the vacuum chamber, there is no possibility that the impurity gas in the vacuum chamber due to gas release from the magnet will increase and adversely affect the etching characteristics.

Compared to the conventional structure shown in FIG. 2, there are no strict restrictions on the dimensions of the permanent magnets, so it is possible to excite a strong magnetic field in the space near the rod-shaped electrode by only increasing the size of the magnets. As a result, the volume of the auxiliary electrode can be reduced as a whole, making it possible to start the discharge reliably and easily.

The permanent magnet is arranged so that the normal line of the magnetic pole surface of the permanent magnet is perpendicular to the axis of the rod-shaped electrode, so even if the magnet is located away from the rod-shaped electrode, it is strong against the discharge trigger space near the rod-shaped electrode. A magnetic field can be excited.

Since the gas is introduced from near the rod-shaped electrode to which high pressure is applied, the pressure in the space where the auxiliary electrode is provided can be made higher than the pressure in other spaces in the vacuum container, and therefore discharge can be easily and reliably carried out. You can start.

The industrial value of the present invention is high as it provides the above-mentioned remarkable effects with a simple and inexpensive structure.

[Brief explanation of the drawing]

FIG. 1 shows an example of the construction of a sputter etching apparatus in which a discharge trigger is used. Fig. 2 is a sectional view of a conventional auxiliary electrode used as a discharge trigger, and Fig. 3 is a sectional view of a discharge trigger according to the present invention. In the figure, 10 is a vacuum container, 20 is a main electrode,
30 is a discharge trigger having an auxiliary electrode, 31 is an insulator, 32 is a rod-shaped high voltage electrode, 33 is a permanent magnet, 3
4 is a high voltage safety protection cover, 35 is a high voltage power supply, 32
1 is the central axis of the rod-shaped electrode, 331 is the line of magnetic force, 351
121 shows the electrical wiring between the high-voltage power source and the rod-shaped electrode, and 121 shows the gas introduction pipe.

Claims (1)

[Scope of utility model registration request] A discharge trigger installed in equipment that generates plasma in a vacuum to perform sputtering and other thin film processing, and is connected to a rod-shaped electrode connected to a high-voltage power source outside the vacuum container of the equipment, and to the central axis of the rod-shaped electrode. A permanent magnet placed outside the vacuum vessel so as to emit perpendicular lines of magnetic force, and a gas inlet for introducing gas into the vacuum vessel through the space around the rod-shaped electrode are connected to the vacuum vessel of the apparatus. A discharge trigger characterized by being incorporated near the main electrode.