JPS6334225B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a facing target sputtering apparatus suitable for manufacturing high-density magnetic recording media, etc., in which a thin film of ferromagnetic material or the like is deposited on the surface of a substrate at high speed. In particular, the present invention relates to a facing target type sputtering apparatus using a rectangular target having a rectangular shape or the like.

(Prior Art) Conventionally, as this type of facing target type sputtering device, there is one described, for example, in Japanese Patent Application Laid-open No. 158380/1983.

That is, in this conventional method, as shown in FIG. 6, two targets 1 and 1a are placed facing each other with a space between them, and a voltage is applied to the targets 1 and 1a to make them cathodes under a predetermined sputtering gas atmosphere condition. By applying the voltage and sputtering, a plasma space consisting of scattered atoms of the target, secondary electrons, sputter gas ions, etc. is formed in the space 3 between the targets 1 and 1a, and the plasma space is placed on the side of the space 3. The scattered atoms of the target are deposited on the substrate 11.

(Problems to be Solved by the Invention) However, in the conventional sputtering apparatus described above, when a rectangular square target is used to form a thin film on a wide substrate, the distance between the targets during sputtering is The plasma density in the space is not uniform due to the influence of the magnetic field distribution, resulting in a phenomenon in which high-density plasma is formed near the center in the longitudinal direction.

Therefore, the film thickness distribution of the thin film deposited on the substrate surface facing the space between the targets is as shown in Figure 7 (setting values will be described later), with the thickness being thicker at the center in the longitudinal direction of the targets, and thicker at both ends. The disadvantage is that the film becomes thinner on the side, making it impossible to obtain a thin film with a uniform thickness on the substrate. In particular, the problem of nonuniform film thickness distribution becomes more pronounced when the target and substrate are long.

As a result, conventionally, when a wide magnetic recording tape or the like is manufactured by sputtering, a problem has arisen in that the properties and quality of the thin film deteriorate.

Incidentally, as a measure to solve the above-mentioned difficulties, it is possible to consider, for example, changing the arrangement of the magnets 8 on the back side of the targets to appropriately set the magnetic field distribution in the space 3 between the targets. When the materials of the targets 1 and 1a are ferromagnetic, the targets themselves are magnetized by the magnet, and as a result, the magnetic field distribution in the space between the targets cannot be set uniformly.
Unevenness in film thickness cannot be resolved.

Furthermore, when a circular target is used instead of a rectangular target, the plasma density in the inter-target space can be made uniform by the magnetic field distribution and the movement of secondary electrons. However, in order to form a thin film on a wide substrate, it is necessary to generate a large plasma space corresponding to the width of the substrate. It has to be made bigger.
Therefore, in the case of a circular target, a larger magnetic field is required than in the case of a rectangular target, which increases the power required for sputtering the target and also reduces the speed of thin film formation on the substrate, making it unsuitable for practical use. .

Therefore, in the present invention, when using a rectangular target that enables thin film formation at a lower cost and at a higher speed than when using a circular target on a wide substrate, it is possible to form a thin film on a substrate surface. To make it possible to set a thin film with a uniform thickness,
That is the purpose.

(Means for Solving the Problems) The present invention attempts to make the plasma density uniform by separately providing an auxiliary means for reducing the plasma density in the longitudinal center portion of the target where the plasma density is high. This structure is designed to achieve uniform thickness of the thin film deposited on the surface of the substrate.

That is, in the present invention, a pair of rectangular targets 1 and 1a serving as cathodes are provided with their sputtering surfaces 5 and 5a facing each other with a space between them, and the sputtering of the rectangular targets 1 and 1a causes the sputtering of the rectangular targets 1 to 1. , 1a, a plasma space is formed in the space 3 between them, and the substrate 1 is disposed on the side of the space.
In an opposed target sputtering device configured to be able to form a thin film on a sputtering target 1, a sputtering device is provided at approximately the center of the outer periphery of the rectangular targets 1, 1a in the longitudinal direction. A grounded shield chip 7 for absorbing secondary electrons in the plasma space is located at a position facing the sputtering surface of the square targets, which is located inside the shield ring covering the outer periphery of the square targets 1 and 1a. This is an opposed target type sputtering device in which at least one target is provided in a protruding state.

(Function) Therefore, in the opposed target sputtering device characterized by the above configuration, the square targets 1,
The grounded shield chip 7, which is provided at a substantially central position in the longitudinal direction of 1a and facing the rectangular target, absorbs secondary electrons that increase the plasma density in the plasma space. Ionization of the atmospheric gas in the area is suppressed and the plasma density is reduced. In other words, by reducing the plasma density in the central part, which is originally in a higher density plasma state than in other parts, the plasma density can be equalized as a whole. the result,
Even if the substrate facing this plasma space is wide, the scattered atoms of the target are deposited on the entire surface at approximately the same speed, resulting in a uniform film thickness distribution.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In Fig. 1, 1 and 1a are target holders 2,
2A and 2A are respectively shown square targets made of rectangular flat ferromagnetic material mounted on backing plates 20 and 20a and facing each other with a space 3 in between. 4, 4a are square targets 1, 1a
A shield ring which covers the outer peripheral edge of the rectangular targets 1, 1a at a small distance from the sputtering surfaces 5, 5a of the target holders 2, 2.
a and is insulated and grounded via insulators 6 and 6a. The shield rings 4, 4a are for preventing the backing plates 20, 20a from being eroded by spatter due to the plasma space formed in the space 3 by spatter.

As shown in FIG. 2, shield chips 7 are provided at appropriate intervals in six locations, three at approximately the center of the shield ring 4 located at the outer periphery of both long sides of the rectangular target 1. is provided so as to protrude inwardly from the shield ring 4 so as to face the sputtering surface 5 of the rectangular target 1, and is also grounded via the shield ring 4. Reference numeral 7a denotes a shield chip provided on the other shield ring 4a side, and its arrangement is the same as that of the one shield chip 7 described above.

Permanent magnets 8 and 8a are provided on the back side of the rectangular targets 1 and 1a, and are used to generate a magnetic field perpendicular to the sputtering surfaces 5 and 5a of the targets. Reference numeral 9 denotes a vacuum chamber surrounding the rectangular targets 1, 1a, the space 3, etc. In FIG. 3, reference numeral 11 denotes a substrate provided on the side of the space 3 between the rectangular targets, facing the space 3;
For example, a continuous tape wrapped around the cooling roller 12 is used.

The present embodiment has the above configuration, and an example of its use will be described next.

In the conditions shown in FIGS. 1 to 3, to perform sputtering work, first, after evacuation of the vacuum chamber 9, a sputtering gas such as argon gas is introduced.
Thereafter, a voltage is applied to the rectangular targets 1 and 1a so as to make them cathodes. By this,
In the space 3 where the rectangular targets 1, 1a are sputtered and a magnetic field is formed by the magnets 8, 8a, metal atoms, secondary atoms, argon gas ions, etc. of the rectangular targets 1, 1a are scattered. A plasma space is formed.

Since the grounded shield chips 7, 7a are provided in a protruding state approximately at the center of the space 3, the shield chips 7, 7
Secondary electrons present in the central part of the plasma space are absorbed by a. As a result, the ionization of argon gas in the central part of the plasma space is suppressed, and the plasma density in the central part, which is supposed to be in a high-density plasma state, is reduced, resulting in a uniform plasma density as a whole.

Therefore, the target metal atoms in the plasma space where the plasma density is generally uniform are uniformly coated on the surface of the substrate 11 at high speed by diffusion while repeatedly colliding within the space and losing energy. This results in the formation of a desired ferromagnetic thin film with a uniform thickness distribution.

Incidentally, when the sputtering operation as described above was carried out under the following setting conditions, a film thickness distribution as shown in FIG. 5A was obtained.

Target material: Fe Target dimensions: 80 x 250 x 5 [mm] Distance between targets: 110 [mm] Plasma convergence magnetic field: 140 [0e] Substrate: Distance between glass substrate and target end: 20 [mm] Target applied power : DC power source Target applied voltage: -650 [V] Target applied power: 1300 [W] Atmospheric gas pressure (Ar): 4 [mTorr] The dimensions and position of the shield chip are as shown in FIG.

In other words, the film thickness distribution shown in Figure 5A shows that a film thickness error within 10% was obtained over a wide range of 200 mm with respect to 250 mm in the longitudinal direction of the target, and under the same conditions, no shielding chip was provided. The film thickness distribution in the present invention is much more uniform than that shown in FIG. 8, which was obtained by sputtering using conventional means.

In the above embodiment, a total of six shield chips 7 are provided at the center of the shield ring 4 in pairs, but the present invention is not limited to this. The specific number, shape, etc. of the shield chips can be changed as desired.

Further, the position where the shield chips 7 are provided is not limited to the exact center position of both side edges of each rectangular target 1, 1a, and a plurality of shield chips may be provided over a wide range at predetermined intervals as in the above embodiment. do not have. In short, the rectangular targets 1, 1a are placed approximately in the center of the outer periphery of the rectangular targets 1, 1a in the longitudinal direction.
It is sufficient that at least one or more sputtering plates are provided in a protruding state at a position facing the sputtering surface of the rectangular target inside the shield ring covering the outer peripheral edge of the rectangular target. In addition, when the shield chips 7 are arranged in pairs facing each other approximately in the center of the rectangular target 1, the movement of secondary electrons in the plasma space is as shown by the arrow line as shown in FIG. As shown, the shield chips 7 are separated at the center where the shield chips 7, 7 are provided. As a result, the plasma density in the central portion is reduced, resulting in a substantially uniform plasma density as a whole.

Further, in the present invention, the shield chip 7 does not necessarily need to be provided directly attached to the shield ring, but may be provided separately from the shield ring. Further, the shield chip 7 only needs to be electrically grounded so as to be able to absorb secondary electrons in the plasma space, and its specific material is not limited.

Furthermore, the present invention is not limited to the specific configuration of other parts constituting the sputtering device as in the above embodiments, and the design of the specific configuration of each part can be changed within the scope of the present invention. It is also possible to use a high frequency power source as a target application power source for sputtering.

(Effects of the Invention) As described above, the present invention provides a grounded shield chip at approximately the center of the longitudinal outer periphery of a rectangular target so that the high-density plasma is lower than that at the end of the space between the targets. Because the structure is configured so that the plasma density in the center of the plasma space can be reduced by absorption of secondary electrons, the plasma density in the center of the plasma space is significantly lower than in other locations, unlike conventional sputtering equipment. The density of the plasma space can be made uniform over the entire surface without causing uneven high density, and the thickness distribution of the thin film deposited on the surface of a wide substrate can also be made uniform with less variation. It became possible for those who were given the opportunity to do so.

As a result, according to the present invention, a thin film of uniform thickness can be appropriately formed on a wide substrate, and the present invention has the extraordinary effect of contributing to improving the quality characteristics of the thin film forming product.

In addition, the facing target sputtering apparatus using the rectangular targets of the present invention has lower operating costs and can operate at higher speeds than means using circular targets, which require large distances between targets, large magnetic fields, and large power consumption. It also has the advantage of excellent properties.

In addition, the present invention has a very simple structure in which a shield tip is simply added to an existing facing target type sputtering device, and has the practical advantage of being excellent in its manufacturability.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the facing target type sputtering apparatus according to the present invention, FIG. 1 is a schematic explanatory view of the whole, and FIG. FIG. 2B is a plan view, FIG. FIG. 4 is a schematic plan view showing the movement state of secondary electrons in a plasma space in another embodiment. FIG. 5A is an explanatory diagram showing the thickness distribution of the thin film obtained in this example, and FIG. 5B is an explanatory diagram showing the setting conditions of the shield chip. 6 and 7 show conventional examples, FIG. 6 is an explanatory diagram showing the conventional apparatus, and FIG. 7 is an explanatory diagram showing the thickness distribution of a thin film obtained by the conventional apparatus. 1, 1a... Square target, 3... Space part,
4, 4a... Shield ring, 5, 5a... Sputter surface, 7... Shield chip, 11... Substrate.

Claims (1)

[Claims] 1 A pair of rectangular targets 1, 1a serving as cathodes are provided with their sputtering surfaces 5, 5a facing each other with a space between them, and the rectangular targets 1, 1a
The facing target type is configured to form a plasma space in the space 3 between the rectangular targets 1 and 1a by sputtering, and to form a thin film on the substrate 11 placed on the side of the space. In the sputtering device, at approximately the center of the outer periphery of the rectangular targets 1, 1a in the longitudinal direction, there is a groove for absorbing secondary electrons in the plasma space in the longitudinal center of each rectangular target 1, 1a. At least one grounded shield chip 7 is provided in a protruding position facing the sputtering surfaces 5, 5a of the rectangular targets on the inner side of the shield rings 4, 4a that cover the outer peripheral edges of the rectangular targets 1, 1a. A facing target type sputtering device characterized in that: