JPS62188776A - Opposed target type sputtering device - Google Patents

Abstract

PURPOSE:To stabilize the plasma to be formed between opposed targets and to make the characteristics of a thin film uniform by providing means for radiating electrons alongside the spacing between the targets. CONSTITUTION:A substrate 13 is disposed alongside the spacing between the opposed targets 1 and 2 and the plasma generated between the targets 1 and 2 sputter the targets 1, 2 to form the thin film on the substrate 13. A hot cathode 15 and an anode 16 facing said cathode are provided alongside the spacing between such targets 1 and 2. The electrons radiated from the hot cathode 15 are radiated into the spacing between targets 1 and 2 so that the electrons are intruded into the plasma. The thin film is formed at a high speed under a high vacuum by such method. The environmental characteristics of the film are improved in the case of forming the thin film consisting of a rare earth-fiber metallic material having a magnetooptic effect.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a method in which a plurality of targets are arranged facing each other, plasma is generated between the targets to perform sputtering, and sputtering is performed by generating a plasma between the targets. The present invention relates to an improvement in the structure of a facing target sputtering apparatus for forming a thin film on a substrate.

[Prior art] Opposed target sputtering involves applying a magnetic field in a direction perpendicular to the target surface between opposing targets and applying a high voltage to the targets to perform sputtering. This method forms a thin film on a substrate placed on a substrate.

An example of this type of facing target type sputtering apparatus is described in "Oyoi Physics" No. 48, No. 6, pp. 558-559.

The facing target type sputtering apparatus is equipped with a means for applying an LA field in a direction perpendicular to the target surface between two targets, so that the ionization efficiency of the sputtering gas is increased by the influence of the magnetic flux generated by the magnetic field application means. be able to. Therefore, sputtering under high vacuum is possible, and 11JflU can be formed at high speed.

In addition, since the target and the substrate are arranged almost perpendicularly, the substrate and N film are less likely to be damaged by high-energy particles such as recoil ions of the sputtering gas, and the temperature rise of the substrate is also reduced. It has the advantage of being able to

Magnetron sputtering is known as a method of obtaining a similar effect using the movement of electrons due to magnetic lines of force. However, with a simple magnetron sputtering device,
If the target is made of a ferromagnetic material and the thickness is increased, the above-mentioned effects cannot be obtained. This is because the magnetic flux generated by the magnetic field generating means fixedly provided on the back surface of the target is almost confined within the target. Therefore, the above-mentioned facing target sputtering apparatus is effective when using a target made of such a ferromagnetic material, that is, when forming a ferromagnetic thin film.

[Problem to be solved by the invention 1 In recent years, the density of recording media has been increasing, and in particular, magneto-optical disks that use laser light for recording and reproduction have achieved significantly higher recording densities than conventional recording media. It is attracting attention because it can be done. By the way, in such a low density recording medium, the micro-uniformity of the film has a great influence not only on its recording and reproducing characteristics and reproducibility, but also on its storage life, that is, the storage life of recording. Therefore, there is a need for a recording film that is more uniform and therefore more reliable than ever before. The current facing target type sputtering MflF cannot sufficiently meet such demands.

Therefore, an object of the present invention is to provide a new facing target sputtering apparatus that can form a more uniform thin film.

[Means for Solving the Problems] The facing target type sputtering apparatus of the present invention includes a magnetic field applying means for applying a magnetic field in a direction perpendicular to the target surface between the targets arranged facing each other, and a high voltage applied to the targets. An improved facing target type sputtering apparatus is provided with a voltage applying means for applying a voltage, and performs sputtering by generating plasma between facing targets to form a thin film on a substrate placed on the side of a space between the targets. and
It has the following characteristic configuration.

That is, it is characterized in that it is arranged on the side of the space between the targets and includes an electron emitting means for emitting electrons into the space between the targets.

[Operation] In this invention, although the mechanism of operation is not necessarily clear, electrons are supplied to the space between the targets by the electron emitting means. Therefore, the discharge state between the targets is stabilized, making it possible to form thin films under higher vacuum and at higher speeds than with conventional facing target sputtering equipment, resulting in improved environmental resistance. A uniform thin film with excellent properties is formed.

[Description of Embodiment] An embodiment of the present invention will be described with reference to FIG. Similar to the conventional facing target type sputtering apparatus, targets 1.2 are arranged facing each other at a predetermined distance. On the back side of each target 1.2, a magnetic field applying means 3.4 for applying a magnetic field in a direction perpendicular to the target surface between the targets 1.2 and a water cooling device 5.6 as a cooling means are provided. There is. Further, a shield ring 7.8 is provided to surround the outer periphery of the target 1.2 and to hold the target 1.2. Furthermore, a sputtering gas inlet 9 and an exhaust port 10 are provided in the tank 11 .

Note that the targets 1.2 do not necessarily have to be opposed in parallel, and may be opposed, for example, at an angle of about 30°.

The above configuration is no different from a conventional facing target type sputtering apparatus, and the substrate 13 (indicated by a broken line) is placed on the side of the space between the targets 1.2. Here, the plasma generated in the space between the targets 1.2 sputters the targets 1.2, thereby forming a thin film on the substrate 13.

Incidentally, in this embodiment, a hot cathode 15 as an electron emitting means is arranged on the side of the space between the targets 1.2. The reason why the hot cathode 15 is arranged on the side of the space between the targets 1.2, that is, shifted from the space between the targets 1.2, is to keep it sufficiently away from the plasma generated in the space. By moving to the side in this way, the hot cathode 1
5 or the formation of a film on the hot cathode 15 can be prevented.

Furthermore, in this embodiment, an anode 16 is provided on the side of the space of the target 1.2 so as to face the hot cathode 15. The anode 16 is provided to cause discharge to occur between the anode 16 and the hot cathode 15, and in particular to ensure that electrons enter the space between the targets 1.2. However, the anode 16 is not an essential component, and may be replaced by the side wall of the tank 11. However, hot cathode 1
Ensure that the electrons emitted from 5 enter the plasma!
In this case, it is preferable to provide an anode 16. In this case, it is necessary to apply a positive voltage to the side wall of the tank 11 to the anode 16. It is also possible to apply a positive potential even when the battery is at rest.

As mentioned above, in this embodiment, the electrons emitted from the hot cathode 15 are emitted into the space between the targets 1.2.

Therefore, although its mechanism of action is not necessarily clear, it is possible to form a thin film with better environmental resistance, as is clear from the experimental examples described later. Therefore, the W1 film can be formed at a higher speed under a higher vacuum than in the conventional facing target sputtering apparatus.

In the above embodiment, the hot cathode 15 is used as the electron emitting means.
was used, but other electron emitting means such as an electron gun can be used.

Next, a specific experimental example will be explained.

Friend 11 Tt) aoFe7o# and TbtOCO on the glass substrate
70 films were formed using the facing target sputtering apparatus of the present invention. As a target, Fe
Alternatively, a composite target in which Tb chips were appropriately arranged on a CO root plate was used. A W-type hot cathode was used as the electron emitting means, and a copper tube coil with an outer diameter of 5 mm+ was placed opposite the space between the two targets to serve as an anode. 'The sputtering conditions are as follows.

(a) Target diameter: 100mm (b) Target spacing: 80n+n+ (c) Hot cathode 15 top 〇 or -1000V (d) Anode voltage: +2
00V (e) Ultimate vacuum: 5X 10-' torr (
f) Sputtering gas: Argon (T) Bias voltage knee 50V (H) Input power: DC 300W (S) Substrate cooling method: Indirect water cooling After sputtering was performed under one condition to form a thin film, a voltage was applied to the hot cathode. When not used, the minimum gas pressure for stable sputtering was 7 x 10-' torr, whereas when a voltage of -1000 V was applied to the hot cathode, the input power was 300 W DC up to 2 x 10-' torr. It discharged stably. Therefore, sputtering was performed at this gas pressure. The film forming speed is approximately 400A/
It was a minute. A film with a thickness of 2000A was formed for each, and H
The reflectance was examined using an e-Ne laser. Also, the temperature is 60
℃ and 95% relative humidity for 10 days, and then the reflectance was examined to evaluate the environmental resistance characteristics. Table 1 shows the changes in reflectance thus obtained.

From the results in Table 1, when a voltage of -1000V is applied compared to when no voltage is applied to the hot cathode, the decrease in reflectance is significantly improved from -53% to -21% in the TbFe film. Similarly, in the TbC0 film, -19%
→ It can be seen that there is a significant improvement of -11%.

[Effects of the Invention] As described above, in this invention, the electron emitting means is provided on the side of the space between the opposing targets, and the electron emitting means radiates electrons into the space between the target and the target. . Therefore, the plasma formed between the targets is stabilized,
As a result, it becomes possible to form a film with excellent environmental resistance. In particular, according to experiments conducted by the present inventors, it has been confirmed that the environmental resistance characteristics can be greatly improved when a thin film made of a rare earth-fiber metal material having a magneto-optic effect is formed.

In addition, in facing target sputtering, the content of sputtering gas in the thin film is originally lower than that in magnetron sputtering, and in many cases it cannot be analyzed, but this effect is maintained in the sputtering apparatus of the present invention. I would like to point this out. In this respect, it is significantly different from magnetron sputtering, in which the gas m contained in the thin film often increases as the gas pressure decreases during sputtering.

This phenomenon is presumed to be related to the above-mentioned effect of improving environmental resistance properties. Of course, even in the sputtering apparatus of the present invention, if a negative bias voltage is applied, the atmospheric gas content in the film tends to increase, but the environmental resistance of the film itself is maintained.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an outline of an embodiment of a facing target type sputtering apparatus of the present invention. In the figure, 1.2 is a target, 3.4 is a magnetic field applying means, 13 is a substrate, and 15 is a hot cathode as an electron emitting means.

Claims (2)

[Claims] (1) Comprising a magnetic field applying means for applying a magnetic field in a direction perpendicular to the target surface between targets arranged facing each other, and a voltage applying means for applying a high voltage to the targets,
In a facing target type sputtering apparatus that performs sputtering by generating plasma between facing targets to form a thin film on a substrate placed on the side of the space between the targets, the sputtering apparatus is placed on the side of the space between the targets. A facing target sputtering apparatus, further comprising an electron emitting means for emitting electrons into a space between the targets. (2) The facing target sputtering apparatus according to claim 1, wherein the electron emitting means emits electrons in a direction parallel to the surface of the substrate on which the thin film is formed.