JPH0734360B2 - Ion milling equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion milling apparatus, and more particularly to an ion milling apparatus suitable for irradiating a target with an ion beam extracted from an ion source to finely process the target surface.

[0002]

2. Description of the Related Art 200 drawn out from a plasma generation chamber
Conventionally, an ion milling apparatus having a configuration shown in FIG. 3 has been used as an ion milling apparatus that irradiates a wide ion beam having an energy of about 5000 V to a target and sputters the target to perform fine processing on the target surface. This ion milling apparatus includes an ion source 1 that draws out a wide ion beam, a target 2 that is used for fine processing of the surface, a target holder 3 that holds and cools the target 2, a target 2 and a target holder 3. A vacuum container 4 to be housed, a vacuum pump 5 for evacuating the inside of the vacuum container 4, and a neutralizing filament 6 for supplying thermoelectrons for electrically neutralizing an ion beam. .

The configuration of the ion milling device will be described in more detail. A neutral gas 10 such as argon gas introduced from a gas introduction port 9 provided in the plasma generation container 11 which constitutes the ion source 1 serves as an anode 8 and a cathode 7 formed on the wall surface of the plasma generation container 11. Extraction electrodes 12 and 1 provided with a large number of apertures (small holes for extracting an ion beam) by forming a plasma in the plasma generation container 11 by ionizing by applying a DC voltage therebetween.
Plasma is extracted as an ion beam by means of 3 (see FIG. 4) and guided into the vacuum container 4. The ion beam guided into the vacuum container 4 is supplied with thermoelectrons for electrically neutralizing by the neutralizing filament 6, and is irradiated to the target 2 fixed to the rotating target holder 3 to thereby obtain the target. 2 is finely processed.

[0004]

By the way, in the above-described ion milling apparatus for processing a large number of targets 2, the targets 2 are arranged concentrically in the target holder 3 in order to utilize a uniform beam of the ion source. In the ion milling device at this time, the peripheral ions used for processing the target 2 are bent by the Coulomb repulsive force (which is called the space charge effect) of the ions running in the central portion which is not originally required, and are incident on the target 2. At that time, the beam becomes a beam largely curved in the outer diameter direction. For this reason,
There is a drawback that the processing accuracy is significantly lowered, and the space charge effect described above becomes more remarkable as the beam diameter of the ion source increases (IONICS 1978 1
See the January issue, p27, 28).

The present invention has been made in view of the above points, and it is an object of the present invention to reduce the space charge effect, suppress the divergence of an ion beam, and dispose a large number of targets on a target holder. Even in the case, it is to provide an ion milling device with good processing accuracy.

[0006]

Means for Solving the Problems The above-mentioned object is to provide a plasma generating container forming a plasma generating chamber, a filament for ionizing a neutral gas introduced into the plasma generating chamber by arc discharge to generate plasma, and the plasma generating chamber. Ions provided with an ion source composed of an extraction electrode for extracting ions in the room as an ion beam, a vacuum container provided adjacent to the ion source, and a target holder for holding and cooling a target in the vacuum container. In the milling device, the extraction electrode is provided with a substantially circular beam shield that blocks passage of an ion beam in the central portion, and has an ion extraction hole that is extracted into the vacuum container by passing the ion beam in the outer peripheral portion. A plurality of beam shields and ion extraction holes are provided as an integral member. It is achieved by there.

[0007]

In order to process a large amount of targets at one time and improve the production speed, it is necessary to increase the diameter of the ion source, but due to the space charge effect, the ion beam is the most useful in the outer peripheral portion, Due to the remarkable divergence, the conventional practice has been that the diameter of about 25 cm has been practically used, but it is difficult for the present inventors to accurately quantify the degree of contribution of the space charge effect. Focusing on the point that the ion beam in the central part has the greatest effect on the beam divergence, the ion beam divergence is most effectively reduced by removing the central ion beam using a circular beam shield. However, an invention capable of improving processing accuracy has been achieved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The ion milling device of the present invention will be described below based on the illustrated embodiments.

FIGS. 1 and 2 show an embodiment of the ion milling device of the present invention. Since the basic structure is almost the same as the conventional one, the description thereof will be omitted.

In the present embodiment shown in FIGS. 1 and 2, the extraction electrodes 21 and 22 for extracting ions as an ion beam from the plasma generated in the plasma generation chamber 11 are
A substantially circular beam shield 20 for blocking passage of the ion beam is formed in the central portion, and the ion beam is extracted in a range in which only the target 2 accommodated in the vacuum container 4 is irradiated with the ion beam. As shown in FIG. 2, a plurality of ion extraction holes 23 are provided in the outer peripheral portion. The beam shield 20 and the ion extraction hole 23 are formed as an integral member, and the extraction electrode 2
1 and 22 are configured.

In this embodiment, DC arc discharge is performed between the cathode 7 and the anode 8 installed in the plasma generating container 11 to generate plasma, and the ion beam is extracted by the extraction electrodes 21 and 22 shown in FIG. However, plasma can be generated in the entire plasma generation container 11, and the ion beam is shielded by the beam shield 20 in the vicinity of the central portion of the extraction electrode 21 and is extracted only from the periphery of the portion, and the target holder 3 It is possible to irradiate the target 2 which is fixed concentrically above. Generating plasma in the entire plasma generation container 11 is a neutral gas in the plasma generation container 11 because the flight distance of electrons from the cathode 7 (thermoelectrons emitted from the filament) to reach the anode 8 becomes long. This increases the probability of collision with molecules, which is advantageous in generating high-density plasma.

Further, since the beam shield 20 is formed in the central portion of the extraction electrode, it is possible to reduce the amount of neutral gas such as argon introduced into the plasma generation chamber. The capacity of the pump can be reduced.

Further, the range of the extraction electrode 21 for extracting the ion beam from the plasma formed by ionizing a neutral gas such as argon gas is limited to only the outer peripheral portion of the peripheral edge of the electrode for irradiating the target. Since the area for irradiating the target is reduced, the amount of unnecessary substances sputtered on the target can be reduced, and the range of the ion extraction hole of the extraction electrode for extracting the ion beam from the plasma formed by ionizing neutral gas such as argon gas can be reduced. By irradiating the ion beam in the vicinity of the target, the area of the target holder irradiated with the ion beam becomes small, so that the cooling device of the target holder can be downsized.

[0014]

According to the present invention, since the central ion beam, which has the greatest influence on the beam divergence, can be eliminated, the repulsive force between the ions can be reduced and the beam divergence can be made extremely small. The accuracy can be remarkably improved, and even when a large number of targets are arranged in a wide area, each target can be processed with the same effect, and the effect to be achieved is very large.

[Brief description of drawings]

FIG. 1 is a sectional view showing an ion source of an ion milling apparatus according to an embodiment of the present invention.

FIG. 2 is a front view of the extraction electrode according to the embodiment of the present invention.

FIG. 3 is a sectional view of a conventional ion milling device.

FIG. 4 is a front view of a conventional extraction electrode.

[Explanation of symbols]

 1 Ion Source 2 Target 3 Target Holder 4 Vacuum Container 5 Vacuum Pump 6 Neutralizing Filament 7 Cathode 8 Anode 9 Gas Inlet 10 Neutral Gas 11 Plasma Generator Vessel 14 Solenoid Coil 20 Beam Shield 21 Extractor Electrode 22 Extractor Electrode 23 Ion Drawer hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Higaki 3-1-1, Saiwaicho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Isao Hashimoto 1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 Stock company Hitachi Ltd. Kokubun factory

Claims (1)

[Claims] 1. A plasma generation container forming a plasma generation chamber, a filament that ionizes a neutral gas introduced into the plasma generation chamber by arc discharge to generate plasma, and ions in the plasma generation chamber are extracted as an ion beam. In an ion milling device provided with an ion source composed of an extraction electrode, a vacuum container provided adjacent to the ion source, and a target holder that holds a target in the vacuum container and cools the extraction electrode, A substantially circular beam shield for blocking the passage of the ion beam is formed in the central portion, and a plurality of ion extraction holes through which the ion beam passes and is extracted into the vacuum container are provided in the outer peripheral portion, and The beam shield and the ion extraction hole are composed of an integral member, Milling apparatus.