JP3926780B2 - Ferrite thin film manufacturing method - Google Patents

Description

  The present invention is used to suppress electromagnetic interference caused by interference of unwanted electromagnetic waves in a magnetic recording medium, magneto-optical recording medium, magnetic head, magneto-optical element, microwave element, magnetostrictive element, magnetoacoustic element, and high-frequency region. The present invention relates to a spinel ferrite thin film that is widely applied to electromagnetic interference suppressors and the like.

For example, as disclosed in Patent Document 1, ferrite plating is performed by bringing a solid surface into contact with an aqueous solution containing at least ferrous ions as metal ions, and contacting the solid surface with FeOH ⁺ or another metal hydroxide. FeOH ²⁺ is obtained by adsorbing ^ions and subsequently oxidizing the adsorbed FeOH ⁺ , which causes ferrite crystallization reaction with metal hydroxide ions in aqueous solution, thereby forming a ferrite thin film on the solid surface To do.

  Conventionally, based on this technology, a ferrite thin film has been homogenized and the reaction rate has been improved. Patent Document 2, which is intended to form a ferrite thin film on various solids by imparting surface activity to a solid surface. There are Patent Document 4, Patent Document 5, and Patent Document 6 relating to improvement of the formation speed of the ferrite thin film.

  The ferrite plating may be anything as long as the solid to form a film is resistant to the aqueous solution described above. Furthermore, since the reaction is via an aqueous solution, the spinel-type ferrite thin film can be formed at a relatively low temperature (from room temperature to the boiling point of the aqueous solution). Therefore, the limited range of the substrate is small compared to other ferrite thin film manufacturing techniques.

JP 59-11129 A JP 60-140713 A Japanese Patent Laid-Open No. 61-030684 JP-A 61-179877 Japanese Unexamined Patent Publication No. 63-042378 Japanese Patent Laid-Open No. 02-116631

  As described above, various improvements have been proposed for the homogenization of the film and the improvement of the film forming speed. However, in the inductance element, the impedance element, the magnetic head, the microwave element, the magnetostrictive element, and the high frequency region. From the viewpoint of application to an electromagnetic interference suppressor and the like, soft magnetic characteristics, film homogenization, and film formation speed are still insufficient, and therefore there have been major problems with respect to application to various electronic components and the like.

The ferrite thin film by ferrite plating is formed by crystal growth based on the solid surface as described above. Conventionally, ferrite fine particles or metal hydroxides, etc., which are produced secondary to other than the solid surface, adhere to the substrate surface without being completely removed, and inhibit the crystal growth of the ferrite thin film. By causing non-uniformity of FeOH ⁺ adsorbed on the surface, it has been difficult to obtain a ferrite thin film that is homogeneous throughout the film and has excellent soft magnetic properties.

  An object of the present invention is to provide a ferrite thin film having a very homogeneous and excellent soft magnetic property, and a method for producing the same, which eliminates the conventional shortcomings and improves productivity.

  As a result of various studies, the present inventors have brought a reaction solution containing at least ferrous ions into contact with the substrate, a step of removing the reaction solution from the substrate, and an oxidation solution containing at least an oxidizing agent in contact with the substrate. When the film is formed by repeating the process and the step of removing the oxidizing solution from the substrate, the film formation speed can be increased by placing the substrate on a substrate holder installed on a turntable or by providing partition plates on the front and side surfaces of the substrate. As a result, it was found that industrial productivity was increased, and an extremely homogeneous ferrite thin film in which individual crystal grains constituting the film were composed of uniform columnar crystals was obtained.

According to the present invention, there is provided a method for producing a ferrite thin film, wherein a substrate on which the ferrite thin film is to be formed is placed on a substrate holder having a height of 0.5 mm or more from the upper surface of the turntable, and is arranged with the rotation shaft of the turntable interposed therebetween. A method for producing a ferrite thin film is provided in which the turntable is rotated while supplying a reaction solution containing at least ferrous ions and an oxidizing solution containing at least an oxidizing agent from the nozzle to the substrate .

An L-shaped partition plate may be provided on a side surface of the substrate, the L-shaped direction of the partition plate may be directed to the rotation direction of the turntable, and the height of the partition plate may be 0.5 mm or more .

  According to the present invention, the step of bringing the reaction solution containing at least ferrous ions into contact with the substrate, the step of removing the reaction solution from the substrate, the step of bringing the oxidation solution containing at least an oxidizing agent into contact with the substrate, and the oxidation solution from the substrate When producing the ferrite plating film by repeating the removing step, ferrite fine particles generated as a result of placing the substrate on a substrate holder placed on the upper surface of the turntable or providing partition plates on the front and side surfaces of the substrate Alternatively, it prevents metal hydroxides from adhering to the substrate surface and hinders homogeneous crystal growth, improves the production rate and increases industrial productivity, and produces a ferrite thin film that is an aggregate of homogeneous columnar crystals. The manufacturing method for obtaining is obtained, and industrial utility value is great.

  ADVANTAGE OF THE INVENTION According to this invention, the production | generation speed | rate can be improved, industrial productivity can be increased, and the ferrite thin film which has a very homogeneous and excellent soft magnetic characteristic, and its manufacturing method can be provided.

  The ferrite thin film of the present invention and the manufacturing method thereof will be described below.

  The ferrite thin film and the method for producing the same of the present invention include a step of bringing a reaction liquid containing at least ferrous ions into contact with a substrate, a step of removing the reaction liquid from the substrate, and an oxidation liquid containing at least an oxidizing agent in contact with the substrate. In the method for producing a ferrite thin film, the substrate is placed on a substrate holder installed on the upper surface of the turntable or a partition plate is provided on the front and side surfaces of the substrate when the film is formed by repeating the steps and the step of removing the oxidizing solution from the substrate. is there. As a result, the deposition rate of the ferrite thin film is improved, industrial productivity is increased, and a homogeneous ferrite thin film in which the individual crystal grains constituting the ferrite thin film are composed of uniform columnar crystals can be obtained.

  The reason why the ferrite thin film of the present invention was obtained is considered as follows. Conventionally, ferrite fine particles or metal hydroxides, which are formed as a secondary material other than on the solid surface, adhere to the substrate surface without being completely removed, thereby inhibiting the crystal growth of the ferrite thin film as a whole film. It was difficult to obtain a homogeneous ferrite thin film.

  According to the method for producing a ferrite thin film of the present invention, a solid surface can be obtained by placing the substrate on a substrate holder installed on the upper surface of the turntable in the production step of the ferrite thin film or by providing partition plates on the front and side surfaces of the substrate. It is considered that the ferrite fine particles or metal hydroxides, etc., which are formed as secondary materials, are prevented from adhering to the substrate, and an extremely homogeneous ferrite thin film can be produced. At that time, by setting the height of the substrate holder and the partition plate to 0.5 mm or more, it is possible to extremely reduce the adhesion of ferrite fine particles or metal hydroxides formed on the substrate other than the solid surface to the substrate. It was. Further, if the partition plate is installed on the front side of the substrate and the side surface of the substrate on the rotation direction side when viewed from the rotation axis, removal of the reaction solution and the oxidizing solution is not hindered.

  The basic part of the method for forming a ferrite thin film of the present invention is almost the same as a known method. However, in the present invention, the step of bringing the reaction solution containing at least ferrous ions into contact with the substrate, the step of removing the reaction solution from the substrate, the step of bringing the oxidation solution containing at least an oxidizing agent into contact with the substrate, and the oxidation solution from the substrate When producing the ferrite plating film by repeating the removing process, the production speed is improved by placing the substrate on a substrate holder of 0.5 mm or more, or providing a partition plate of 0.5 mm or more in height. Thus, a ferrite thin film that is an aggregate of homogeneous columnar crystals can be obtained.

  FIG. 1 is a schematic view of a ferrite thin film of the present invention. Reference numeral 1 denotes a nozzle for supplying a reaction solution, and 2 is a nozzle for supplying an oxidizing solution. 3 is a turntable, 4 is a substrate holder having a height of 15 mm, and 5 is a substrate on which a ferrite thin film is formed. 5 is a substrate, and 6 is a tank for containing a reaction solution and an oxidizing solution.

A reaction solution was prepared by dissolving 3.3 g of FeCl ₂ .4H ₂ O, 1.25 g of NiCl ₂ .6H ₂ O, and 0.025 g of ZnCl ₂ in 1 liter of pure water. As another solution, an oxidizing solution was prepared by dissolving 0.3 g of NaNO ₂ and 5 g of CH ₃ COONH ₄ in 1 liter of pure water.

  The ferrite thin film was produced according to the following procedure. First, the flow rates of the reaction solution and the oxidizing solution were adjusted to 30 ml / min. Then, the temperature of the board | substrate which forms a plating film was adjusted to 90 degreeC using the heater. Further, nitrogen gas was supplied to the plating apparatus at 1.5 l / min to obtain a non-oxidizing atmosphere.

  The plating film was formed while rotating the turntable 3 at 150 rpm while supplying the reaction solution and the oxidizing solution to the substrate at the above flow rates. The direction of the arrow in the figure is the direction of rotation. Formation of the plating film was performed for 10,000 cycles, with one rotation of the turntable 3 as one cycle. Table 1 shows the characteristics of a conventional product that does not use a substrate holder and an inventive product that uses the substrate holder.

  From Table 1, it can be seen that the inventive product is superior in high-frequency soft magnetic properties than the conventional product.

  FIG. 2 is a top view of the rotating plate of the ferrite thin film manufacturing apparatus of the present invention. FIG. 3 is a perspective view of FIG. In addition, since the structure of a nozzle and a tank is the same as Example 1, it abbreviate | omitted to the figure. Reference numeral 13 denotes a substrate on which a ferrite thin film is formed. The substrate 13 is directly placed on the upper surface of the turntable 11. A partition plate 12 having a height of 15 mm is provided on the front side of the substrate and the substrate side surface in the rotation direction when viewed from the rotation axis of the turntable. It is. The direction of the arrow in the figure is the rotation direction of the turntable. Table 2 shows the characteristics of the conventional product using no partition plate and the invention using the partition plate.

  From Table 2, it can be seen that the inventive product has better high frequency soft magnetic properties than the conventional product.

Comparative example

  With the apparatus as shown in FIG. 1, the film was formed without using the substrate holder and the partition plate. Thereafter, a film was formed on the board of the substrate taken out, and as a result of the structure observation using SEM, the uniformity of the film thickness was remarkably deteriorated. In addition, a film having excellent high-frequency soft magnetic characteristics as shown in the inventive products of the above-mentioned examples could not be obtained.

The schematic of the manufacturing apparatus of the ferrite thin film of this invention. The top view of the rotating plate of the manufacturing apparatus of the ferrite thin film of this invention. The perspective view of the rotating plate of the manufacturing apparatus of the ferrite thin film of this invention.

Explanation of symbols

1, 2 Nozzle 3 Turntable 4 Substrate holder 5 Substrate 6, 7 Reaction liquid, oxidizing solution tank 11 Turntable
12 Partition plate
13 Substrate

Claims (2)

A method for producing a ferrite thin film, wherein a substrate on which the ferrite thin film is to be formed is placed on a substrate holder having a height of 0.5 mm or more from the upper surface of the turntable, and at least first from a nozzle disposed across the rotation shaft of the turntable. A method for producing a ferrite thin film, comprising: rotating the turntable while supplying a reaction solution containing iron ions and an oxidizing solution containing at least an oxidizing agent to the substrate . A method of producing a ferrite thin film according to claim 1, provided with L-shaped partition plate on the side surface of the substrate, facing the direction of the L-shaped of the partition plate in the direction of rotation of the turntable, the partition A method for producing a ferrite thin film, wherein the height of the plate is 0.5 mm or more.

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