JPH0339469A - Sputtering device - Google Patents

Abstract

PURPOSE:To sputter a thick ferromagnetic target and to improve its availability by providing a magnetic circuit obtained by binding a couple of magnets magnetized in the longitudinal direction of a plate target with a soft magnetic core. CONSTITUTION:A soft magnetic core 15 is inserted between a couple of magnets 13 and 14 of plate shaped, etc., magnetized in the longitudinal direction of a plate target 22 to form a magnetic circuit. The magnetic circuit is adjoined to the sputtering surface of the target 22, and the polarities of the magnet surfaces facing each other through the core 15 are different from each other. The coercive force of the magnets 13 and 14 is controlled to >=5X10<5> (ampere turn/m) and the residual magnetic flux density to >=1 (tesla). Consequently, a magnetic field necessary for magnetron sputtering is formed on the ferromagnetic target 22 having high permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a planar sputtering apparatus for producing a ferromagnetic thin film such as Fe or CO2Ni, and a planar magnetron cathode for producing a magneto-optical recording medium. It is related to.

Conventional technology Thin films can be fabricated using sputtering for metals and semiconductors.

It has been developed as a technology that can make almost all inorganic materials such as dielectrics into thin films, and is often used to fabricate non-equilibrium alloys such as amorphous alloys. In recent years, magnetron sputtering, which enables high-speed film formation, has been developed and has come to be widely used in the industrial field of thin film devices.

Magnetron sputtering, which targets ferromagnetic materials, is used in industrial fields that use magnetic thin films.

In particular, alloys of rare earth metals and transition metals are used as recording media for magneto-optical disks, which are attracting attention as high-density recording media.
Fabrication by magnetron sputtering is suitable.

In magnetron sputtering equipment, crossed magnetic and electric fields are generally created. The electric field is the anode (
(which may be the wall of the sputtering chamber) and the cathode (which contains the target, with the target facing the anode). Electrons are ejected from the cathode by the action of this electric field, and these electrons ionize the gas in the sputtering chamber atmosphere to form plasma. These gaseous ions are accelerated toward the target, and when they collide with the target, they knock out constituent atoms of the target, and the atoms emitted from the target adhere to the surface of the object to be coated (generally referred to as a substrate).

In order to increase the deposition speed when the gas pressure is low, a magnetic field that crosses the above electric field is created to increase the distance that electrons eject from the target can travel, increasing the ionization efficiency of the electrons with respect to the gas in the sputtering chamber. , ensuring the number of gaseous ions that collide with the target.

This magnetic field is formed on the side of the anode of the target, and a permanent magnet such as a ferrite or alnico ferromagnetic magnet is usually configured on the opposite side of the anode side of the target to apply the magnetic field (for example, 59-3546), therefore, a magnetic field is formed on the target surface by the magnetic flux passing through the target, so when performing magnetron sputtering using a ferromagnetic material with high magnetic permeability as a target, the ferromagnetic material target is Since most of the magnetic flux passes through the target, the magnetic field required for magnetron sputtering cannot be obtained.

For this reason, the thickness of the target is reduced.

An example of the conventional sputtering apparatus mentioned above will be described below with reference to the drawings.

FIG. 5 shows a cross-sectional view of a conventional sputtering apparatus. In FIG. 5, 1 is a sputtering chamber composed of a vacuum chamber, 2 is a target, and 3 and 4 are magnets whose magnetization directions are approximately perpendicular to the longitudinal direction of the target 2 and whose magnetization directions are opposite to each other (for example, 5 is a magnetic core made of a soft magnetic material with high magnetic permeability, 6 is a container for water cooling the target 2, 7 is an insulating material, and 8 is a film coating. 9 is a power supply for supplying a high voltage to the target 2, 10 is a gas line for supplying a gas such as Ar to the sputtering chamber 1, 11 is a vacuum exhaust device, and 12 is a line of magnetic force.

Regarding the sputtering apparatus configured as above,
The operation will be explained below.

First, by introducing Ar from the gas line 10 and evacuating it with the vacuum exhaust device fll, the sputtering chamber 1 is
A magnetic field constituted by the magnets 3 and 4 and the magnetic core 5 exists on the target 2, which is maintained at a degree of vacuum of about 0.04 to 10.0 Torr.The lines of magnetic force are schematically indicated by broken lines 12.

A power source 9 applies high frequency power or negative DC voltage to the target 2 . Due to the action of this electric field, electrons fly out from the target 2, ionize Ar in the sputtering chamber 1, and form plasma.

This plasma is maintained even at low A pressures by the action of a magnetic field and efficiently forms Ar ions.
The r ions are accelerated toward the target 2 by the action of the electric field, and when they collide with the target 2, they knock out constituent atoms of the target 2. Atoms emitted from the target 2 adhere to the surface of the substrate 8 to be coated.

Problems to be Solved by the Invention However, in the above configuration, the magnetic field formed on the target 2 by the magnet 3.4 and the magnetic core 5 is formed by leakage magnetic flux passing through the target 2. Therefore, if the target 2 is a ferromagnetic material with high magnetic permeability, the magnetic field required for magnetron sputtering cannot be obtained because the target 2 forms a magnetic path. Therefore, if the target 2 is a ferromagnetic material, it can be used. The target 2 was limited to a thin one. Therefore, the target 2 has to be replaced frequently, making it difficult to continuously manufacture the target 2, resulting in high manufacturing costs.

In view of the above problems, the present invention provides a sputtering apparatus that enables sputtering of a relatively thick ferromagnetic target.

Means for Solving the Problems In order to solve the above problems, the magnetron cathode of the sputtering apparatus of the present invention includes a pair of plate-shaped magnetron cathodes whose magnetization direction is approximately parallel to the longitudinal direction of a flat target, and whose magnetization directions are the same. Alternatively, it is composed of a magnetic circuit in which a rod-shaped magnet is used as the edge of the image and a magnetic core made of soft magnetic material is inserted between them.

Function The present invention can form a magnetic field necessary for magnetron sputtering on a ferromagnetic target with high magnetic permeability by the above-described configuration, and therefore, it becomes possible to sputter a ferromagnetic target with a relatively thick plate.

Example Below, regarding a sputtering apparatus according to an example of the present invention,
This will be explained with reference to the drawings.

FIG. 1 is a diagram showing a schematic cross section of a magnetron cathode of a sputtering apparatus in an embodiment of the present invention. In FIG. 1, 22 is a target made of a ferromagnetic material, and 13.14 is a target made of SmCo or NdFe whose magnetization direction is approximately parallel to the longitudinal direction of the target 22, and whose magnetization direction is the same.
A rare earth magnet such as B (for example, magnetized in the direction shown by the arrow in FIG. 5), and 15 a magnetic core made of a soft magnetic material with high magnetic permeability.

The magnetron cathode shown in FIG. 1 is installed in the sputtering chamber 1 shown in FIG. 5 with a conventional configuration, and 1!
It is connected to a power source 9, and cooling water is fed thereto.

The operation of the sputtering apparatus in one embodiment of the present invention constructed as described above will be described below with reference to FIG.

The intersecting electric and magnetic fields ionize the gas in the sputtering chamber to maintain the plasma, and the target 2
The mechanism for attaching the constituent atoms of No. 2 onto the substrate is the same as the structure of the conventional example. However, since the magnetic field application mechanism is different, the magnetic field distribution on the target 22 is different from that of the conventional example. FIG. 2 is a diagram showing the horizontal magnetic field distribution on a ferromagnetic target 22 having a thickness of about 10 mm. As is clear from FIG. 2, in the magnetic field distribution according to this embodiment, the rate of change of the magnetic field with respect to the position on the target 22 is smaller than that in the conventional configuration.

According to our detailed experiments, the speed at which ions collide with the target 22 and knock out constituent atoms of the target 22 (the etching speed of the target 22) is
It has been found that there is a strong correlation with the rate of change of the magnetic field with respect to the position on 2.

That is, the smaller the rate of change of the magnetic field with respect to the position, the more uniform this speed becomes.

They are also experimentally determining the magnitude of the magnetic field required to maintain the discharge. FIG. 3 is a diagram showing the magnetic field required to maintain the plasma versus the Ar gas pressure in the sputtering chamber l. It can be seen that plasma can be maintained if there is a horizontal magnetic field component of 200 (Oe) on the target 22. In other words, with the magnet configuration in one embodiment of the present invention,
Even when a relatively thick target 22 of approximately 10 m is used, the magnetic field necessary to maintain plasma is obtained. This has a coercive force of 5X10' (ampere turns/m
) As described above, rare earth magnets 13.14 having a residual magnetic flux density of 1 (Tesla) or more were used, and a pair of rare earth magnets [magnets 13.14] magnetized substantially parallel to the longitudinal direction of the target 2 were used.
This is because the magnetic cores 15 are coupled by a magnetic core 15 made of a soft magnetic material, and the leakage magnetic field is effectively utilized.

As described above, according to this embodiment, by providing a magnetic circuit in which a pair of rare earth magnets 13 and 14 magnetized approximately parallel to the longitudinal direction of the target 22 are coupled by the magnetic core 15, sputtering of a relatively thick target is prevented. It can be carried out. Furthermore, since the distribution of the magnetic field formed on the target 2 is uniform, the etching speed of the target 22 can be made uniform, and the utilization rate of the target 22 is improved.

In the example, the rare earth magnets 13, 14 and the magnetic core 15 were annular, but as shown in FIG.
When 2 is in the shape of a strip, the same effect can be obtained even if the rare earth magnets 13, 14 and the magnetic core 15 are in the form of a strip, and furthermore, it is easy to create a magnetic circuit composed of the rare earth magnets 13, 14 and the magnetic core 15. You can also get the effect of

Effects of the Invention As described above, the present invention provides a pair of magnets that are magnetized substantially parallel to the longitudinal direction of a flat target, have a coercive force of 5 x 105 (ampere turns/m) or more, and a residual magnetic flux density of 1 (tesla) or more. By providing a magnetic circuit coupled by a magnetic core made of a soft magnetic material with high magnetic permeability, it is possible to sputter relatively thick ferromagnetic targets, and the etching speed of the targets can be made uniform. , the utilization rate of the target is improved, the frequency of target replacement is reduced, and continuous manufacturing is possible, so that the manufacturing cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a magnetron cathode of a sputtering apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of a magnetron cathode of a sputtering apparatus according to an embodiment of the present invention. Figure 3 is a diagram showing the distribution of the horizontal magnetic field in the sputtering chamber, Figure 3 is a diagram showing the magnetic field required to maintain plasma versus Ar gas pressure in the sputtering chamber, and Figure 4 is a diagram showing the distribution of the horizontal magnetic field in one embodiment of the present invention. FIG. 5 is a cross-sectional view of a conventional sputtering device, which shows a strip-like arrangement of magnets and magnetic cores when the target is in the form of a strip in a magnetron cathode of a sputtering device. ■...Sputtering chamber, 2...Target, 3.4...Magnet, 5...Magnetic core, 6...Water cooling Container, 7... Insulating material, 8... Substrate, 9... Power supply, 10.
... Gas line, 11 ... Vacuum exhaust device, 12 ... Lines of magnetic force, 13.14 ... Rare earth magnet, 15 ... Magnetic core, 22...Ferromagnetic target.

Claims (3)

[Claims] (1) A magnetic circuit consisting of a pair of plate-shaped or rod-shaped magnets whose magnetization direction is approximately parallel to the longitudinal direction of the flat target is used as the image edge, and a magnetic core made of a soft magnetic material is inserted between them. A sputtering device characterized by being adjacent to a sputtering surface. (2) The sputtering apparatus according to claim (1), wherein the polarities of the magnet surfaces facing each other via the magnetic core are different from each other. (3) The sputtering apparatus according to claim 1, wherein the magnet has a coercive force of 5×10^5 (ampere turns/m) or more and a residual magnetic flux density of 1 (tesla) or more.