JPS621866A - Sputtering device - Google Patents

Abstract

PURPOSE:To thoroughly increase the film thickness in step part to uniformly grow a crystal by disposing a main target electrode to face a substrate and disposing auxiliary target electrodes in the positions where the electrodes face the step part. CONSTITUTION:The main target electrode 7 is disposed in the position where the electrode substantially faces the flat part of the substrate 10 surface and the auxiliary target electrodes 8, 8' are disposed in the positions where the electrodes substantially face the step part in a vacuum vessel 6. The film is formed by the electrode 7 and thereafter the film formation by the electrodes 8, 8' is successively or simultaneously executed. The principal component of the sputter particles to the substrate 10 come from the vertical direction according to the above-mentioned constitution and therefore the film thickness to the step part is thoroughly assured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a sputtering apparatus5, and in particular, to a sputtering chamber suitable for ensuring a sufficient film thickness at the stepped portion and obtaining desired film characteristics. Regarding the structure of

[Background of the invention]

The need for sputtering equipment is increasing in various fields as a means for thinning films of various materials. The method ranges from bipolar sputtering, in which a target electrode made of the film-forming material faces the substrate, which is the base material on which the film is to be formed, to magnetron sputtering, which uses a magnetic field to confine plasma and dramatically improve film-forming efficiency. Many methods have been proposed. On the other hand, there are various types of films to be formed, ranging from flat films to films with one step difference, and the latter is the target here. In ordinary sputtering equipment, there is a tendency for the film thickness to become thinner at the step part, but this tendency is not desirable from the viewpoint of the properties required for the film. It is possible to correct the film thickness at the stepped portion by tilting the substrate as disclosed in Japanese Patent Laid-Open No. 56-156765 and Japanese Patent Application Laid-Open No. 56-156766.

On the other hand, permalloy thin films and the like used as core materials of thin-film magnetic heads need to have -axis anisotropy in order to obtain magnetic properties. Since this is based on the compositional atomic arrangement, it is desirable that the crystal structure of the formed film be uniformly arranged over a wide range. In general, films obtained by sputtering have the property that the most dense plane of the crystal structure faces the direction of incidence of sputtered particles, so if the sputter particles are incident from multiple directions, uniform growth of the crystal structure will be hindered. .

Furthermore, crystals inside the thin film, which have been revealed by cross-sectional observation of the thin film, stand up on the substrate in the form of pillars.

The so-called columnar structure also has the property that the growth direction of the column faces the direction of incidence of sputtered particles. In this regard, incidence from multiple directions hinders the uniform growth of this columnar structure, or incidence from oblique directions, so-called oblique incidence, makes it difficult to grow a large columnar structure.

Efforts have been made to improve the film thickness characteristics at step portions by increasing the area of the target electrode, but as the target electrode becomes larger, process parameters such as gas pressure and injected power have a large effect on imparting magnetic properties. , the shape of the plasma,
That is, the density distribution changes and the variation in film thickness distribution characteristics including the step portion becomes large. This makes it difficult to independently control the magnetic properties and film thickness distribution properties, and becomes a major obstacle in satisfying both properties.

[Purpose of the invention]

An object of the present invention is to provide a sputtering apparatus that enables uniform crystal growth and obtains desired film characteristics by making the film thickness sufficiently thick at the stepped portion and suppressing the influence of oblique incidence as much as possible. It's about doing.

[Summary of the invention]

The key point of the present invention is that the target main electrode is placed at a position facing the substrate, and the target auxiliary electrode is placed at a position facing the one-step difference.

[Embodiments of the invention]

The present invention will be explained below using examples.

FIG. 1 is an enlarged schematic representation of only the essential parts of the thin film magnetic head. It consists of a coil 3 formed spirally from a conductor and covered with an insulator 2 on a substrate 1, and a core 4 made of a permalloy film formed to interlink with the coil 3. The size of the thin film magnetic head is from several tens to several hundreds of micrometers, and for example, is formed simultaneously on several hundred sides on a substrate with a diameter of 3 inches.

The operation of the magnetic head is such that after each piece is cut out from the substrate, a current is applied to the coil 3, a magnetic flux is generated in the core 4, and the magnetic flux leaks in the gap part 5, which writes on a medium such as a magnetic disk. It is done.

Reading from a medium is almost the reverse process. The issues concerning the core 4 here are the film thickness at the step P portion and the magnetic properties shown in the second column. The present invention will be mainly described with reference to the process of forming a magnetic layer including a step P portion. (a) is a B-H curve of the easy oxidation axis of the permalloy film, which is formed in a direction perpendicular to the paper plane of FIG. FIG. 2(b) shows the characteristics of the hard axis of magnetization, which is formed in a direction perpendicular to the easy axis, that is, in the direction in the plane of the paper in FIG. Since the magnetic flux within the magnetic head is oriented in the hard axis direction, the BH curve is closed and loss is small.

This separation of the easy axis and hard axis of magnetization, that is, imparting -axis anisotropy, can be achieved by applying a parallel magnetic field during film formation, with the easy axis in the direction of the applied magnetic field.

The difficulty axis is obtained with its vertical orientation. However, as mentioned above, this phenomenon is caused by the arrangement of Ni atoms and Fa atoms in the film composition, so when sputtered particles are incident from a direction perpendicular to the substrate surface, -axis anisotropy is obtained. On the other hand, in the case of perpendicular incidence, the film thickness at one step is thinner than that at a flat part, so when recording as a magnetic head, it is difficult to prevent magnetic saturation. This causes a drop in efficiency. As a countermeasure to this problem, oblique incidence from the direction opposite to the step is desired, and a structure inconsistent with the above-mentioned structure is required.

An embodiment that can realize these is shown in FIG.

In the figure, a target main electrode 7, target auxiliary electrodes 8, 8', and a substrate 10 mounted on a substrate tray 9 are arranged in a vacuum container 6. The inside of the vacuum container 6 is evacuated from the exhaust port 11 by an exhaust device (not shown) (here, 10-
'~10-' Torr), a desired gas (argon here) is supplied from the air supply port 12 by a gas supply system (not shown) while controlling the flow rate, and the inside of the vacuum vessel 6 is kept at a constant atmospheric gas pressure ( Here, 10-' ~ 10-1Torr
). The substrate tray 9 carrying the substrate 10 is placed almost directly above the target electrode 7 by the transport mechanism 13, and the potential is kept at the same ground potential as the vacuum container 6. The substrate surface has a stepped shape with two layers of insulators deposited on it as shown in Figure 1, but it is omitted because it is too small.In this example, planar magnetron type target electrodes were used for each target electrode. Both target 14. Magnet container 1
5. Permanent magnet 16° Cooling water piping 17. Insulating support 18.
It consists of an earth shield 19. The target auxiliary electrode 8 is placed substantially opposite to the stepped portion on the substrate. A permanent magnet 16 generates a magnetic field for plasma confinement on the surface of the target 14. At this time, since the target is a magnetic material, it is necessary to bring it into magnetic saturation, which requires a stronger magnet than in a normal sputtering device. In reality, an iron core is used to provide a return path for the magnetic field, but it is omitted in Figure 1. The target electrodes 7°8.8' are supported insulatingly from the vacuum vessel 6 by an insulating support 18, and are each connected to a power source 20.

Power source is high frequency (13.56MHz is commonly used)
Or direct current. Furthermore, the substrate is provided with a heating mechanism 21 such as a sheath heater or a lamp heater to preheat the substrate.
It is used for substrate temperature control during film formation and magnetic annealing after film formation. A shutter is provided in the space between the substrate 10 and the target 7, 8, 8' to prevent adhesion of sputtered particles during preliminary discharge prior to film formation, but is not shown in the figure. In this state, the power supply
When power is supplied, a glow discharge is generated in which the front surface of the target becomes dense, and the target material is sputtered to form a thin film on the substrate. Since the details of the sputtering phenomenon are already known, they will be omitted here. In order to impart uniaxial anisotropy to a thin film, it is necessary to apply a magnetic field parallel to the substrate surface during film formation, and this method involves arranging air-core coils facing each other.

There are methods of applying a magnetic field generated between the gaps of electromagnetic coils, methods of arranging permanent magnets facing each other, etc., but these are not shown in the figure.

The key point in this configuration is that the film is formed mainly using sputtered particles emitted from the target main electrode 7, and the film thickness at the stepped portion on the substrate is corrected by supplementarily using the target auxiliary medium electrodes 8, 8'. That's true. Therefore, preferably
It is better to first form a film using the target main electrode 7, and then perform film forming using the target auxiliary electrodes 8, 8' sequentially or simultaneously.
It is also possible to form a film at the same time as the target main electrode 7 within a range where the injection power is low. According to this example, since the main component of sputtered particles to the substrate comes from the vertical direction,
It is easy to impart magnetic properties to the film, and it is also possible to ensure a sufficient film thickness at the step portion.

Figure 4 is a front view of the target electrodes 7, 8, 8' and shows a case in which they are configured in a nearly circular shape, but when there are spatial constraints, etc., they may be made into a rectangular or similar shape as shown in Figure 5. In the present invention, all target electrodes are magnetron type that confine plasma using a magnetic field, but target main electrode 7 is of magnetron type, and target auxiliary electrodes 8 and 8' are of so-called conventional type without magnet. You can freely combine them to create a conventional type.

FIG. 6 shows an electrode arrangement suitable for processing a large number of substrates 10 (three in this case). (a) shows a front view, and (b) shows a cross-sectional view. The key point here is that the substrates 10 are arranged in a row with the step directions perpendicular to each other, and the targets 7, 8, 8' are made elongated. Although the sputtering method may be arbitrarily selected as described above, the magnetron sputtering method is shown here.

Each electrode has a target 14. It is composed of a permanent magnet 16 and an iron core 22. With this method, the same effects as described above can be obtained, and in principle, any number of sheets can be processed by increasing the length of the target electrode. However, the power supply capacity needs to be increased accordingly, and considering the efficiency of the vacuum container, we think it is better to perform parallel processing in multiple rows. In this example, unlike processing with a large-area target, the length of the short side 24 of the erosion area 23 shown by the broken line in the figure can be shortened, so that the influence on the film thickness distribution can be reduced. It is possible to reduce the difference in film thickness between the center and the edge of the substrate to be processed.

FIG. 7 shows a system in which multiple rows (in this case, two rows) of substrates can be processed simultaneously with the same configuration as the one described above by optimizing the substrate 10 and target electrodes 7, 8°8'. .

〔Effect of the invention〕

According to the present invention, since the main components of sputtered particles fly in the direction perpendicular to the substrate, the growth of the sputtered particles on the substrate is excellent, and therefore, when sputtering a permalloy magnetic film, it is difficult to impart magnetic properties to the film. This is easy, and it is possible to ensure a sufficient film thickness on the stepped portion.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the object to be deposited according to the present invention, and FIG.
A diagram showing the B-H characteristics in the figure, FIG. 3 is a cross-sectional view of the present invention,
FIG. 4 is a front view of the main part of FIG. 1, FIG. 5 is a front view showing a modification of the present invention, FIG. 6 is a front view and sectional view showing a different modification, and FIG. 7 is a different modification. FIG. 14...Target, 10...Substrate, 6...Vacuum container, 7...Target main electrode.

Claims (1)

[Scope of Claims] 1. A target and a substrate, which is a base material on which a film is to be formed, are held in a vacuum container, and a main electrode of the target is located at a position substantially opposing the flat portion of the substrate surface. A sputtering apparatus characterized in that an auxiliary electrode of the target is arranged at a position substantially facing the stepped portion. 2. In claim 1, a plurality of the substrates are arranged perpendicularly to the direction of the stepped portions, and an elongated target main electrode is provided at a position facing the substrates, and an elongated target is provided at a position opposite to the stepped portions. A sputtering device characterized by arranging auxiliary electrodes.