JPS6058564B2 - Method for manufacturing hard magnetic thin film - Google Patents

Description

[Detailed description of the invention] The present invention has large coercive force, saturation magnetization, and squareness,
A hard magnetic thin film containing at least cobalt and phosphorus, such as cobalt-phosphorus, cobalt, or nickel-phosphorus, with a smooth surface and uniform magnetic properties and film thickness, can be produced without complicated substrate pre-treatment and post-treatment after film formation. The present invention relates to a manufacturing technique that can be obtained with good reproducibility without requiring the use of the same method.

Note that the hard magnetic material refers to a material with high coercive force. Conventionally, electroless plating methods and electroplating methods have been widely used as methods for obtaining cobalt phosphorus hard magnetic films.

However, these plating methods inevitably require complicated pretreatment of the substrate or making it conductive, and the pretreatment in particular has a significant effect on the condition and properties of the plated film formed. For example, if the chemical etching of the substrate is insufficient, the bond between the substrate and the plating film will be incomplete, resulting in problems such as the plating film not being formed or the formed plating film peeling off. Occur. Further, depending on the degree of chemical etching or activation treatment, disadvantageous situations such as differences in the deposition rate of the plated film and the smoothness of the plated film surface may occur. For this reason, strict processing conditions must be established and controlled in the pre-treatment of the plating process. Also, after the plating film is formed, post-treatment such as washing with water is essential. Therefore, in the production method of a hard magnetic film using the conventional plating method, the production equipment becomes large and the pre-processes are diverse, resulting in an impediment of productivity and reproducibility. In addition to the above-mentioned drawbacks, in the conventional method, when forming a plating film with a thickness of several hundred Λ or less, it is quite difficult to obtain a uniform plating film, and the substrate material is Naturally, these liquids cannot be used on items that are likely to be attacked by the processing liquid or the polishing liquid.

In view of the above-mentioned current situation, it is an object of the present invention to provide a new and useful method for producing a hard magnetic thin film that can reduce the complexity of work and obtain a uniform film even in a thin film by making full use of technical means. The purpose is to

The manufacturing method of the present invention is characterized in that a hard magnetic thin film is manufactured in two steps, including a step of obtaining a plated film to serve as a target for RF sputtering by plating, and a step of obtaining a hard magnetic thin film as a sputtered film by RF sputtering. shall be.

That is, a plating film of cobalt, phosphorous, etc. is formed on a suitable substrate by electroless plating or electroplating, and then using this as a target, a plating film of cobalt, phosphorus, etc. is formed on a semiconductor or glass substrate by RF sputtering. A hard magnetic thin film containing at least cobalt and phosphorus, such as phosphorus, is produced. Hereinafter, the present invention will be explained in detail based on one embodiment.

Cobalt phosphorus is used as a hard magnetic material, and cobalt
Diameter 80wrm 1 thickness 10T1 as a substrate for phosphor plating
Using a standard copper plate, this copper plate is etched with aqua regia and then activated with palladium chloride.

Next, adjust the bath composition, pH value, temperature, and liquid volume to the values shown in the table below, and plate the copper plate with cobalt phosphorus for about 5 hours to form a cobalt phosphorus plating film with a thickness of 20 μm to 30 μm. obtain. The cobalt-phosphorous plating film obtained in this plating process is used as a target for RF sputtering in the next process.

In the above target manufacturing process, after a series of pre-treatments such as chemical etching and activation treatment of the copper plate that will become the plating substrate, after the formation of the plating film, and after washing with water, etc. Treatment is naturally necessary, but the requirements for the deposition rate, smoothness, uniformity of film thickness, etc. of the plated film itself do not need to be strictly controlled, and the allowable range of processing conditions for pre-treatment and post-treatment is quite wide. Can be set.

Using the above cobalt phosphorus plating film as a target, R
A thickness of 500 mm is deposited on the substrate by F sputtering.
~1200A cobalt/phosphorus thin film is formed.

The substrate at this time is, for example, a 2-inch diameter SiO,
A Si substrate (Si crystal coated with a Siα film) is used. The magnetic properties of the sputtered film (cobalt-phosphorus thin film) obtained by the above method are shown in the attached drawings.

The figure shows the coercive force Hc (
The values of residual magnetization Mr (unit 0e), residual magnetization Mr (unit Gauss), saturation magnetization Ms (unit Gauss), and squareness ratio Mr/Ms are expressed on the vertical axis. Note that the number of extracted samples is 12. The plating film surface of the target was matte, but the film surface of the cobalt-phosphorus thin film formed as a sputtered film was glossy, extremely smooth, and had uniform magnetic properties and film thickness. The adhesion strength with the substrate was sufficient to withstand use, and a strong bond could be formed.

As explained in detail above, the present invention targets a hard magnetic plating film containing at least cobalt and phosphorus such as cobalt-phosphorus obtained by a plating method, and forms a hard magnetic plating film containing at least cobalt and phosphorus on a substrate by an RF sputtering method. This sputtering process does not require pre-treatment of the substrate or post-treatment after forming the thin film, and the sputtered film is extremely glossy regardless of the smoothness of the target film surface. Even when obtaining a hard magnetic thin film with a thickness of several hundred amps or less, it is possible to obtain a thin film having a uniform thickness.

Moreover, the film thickness can be easily controlled. The magnetic properties of the produced hard magnetic thin film are large and uniform in coercive force, saturation magnetization, and squareness ratio, and both reproducibility and productivity are good. Furthermore, it is also possible to control the magnetic properties of the sputtered film by the plating processing conditions during target production.

[Brief explanation of the drawing]

The accompanying drawings are magnetic characteristic diagrams of cobalt-phosphorus thin films obtained according to the present invention.

Claims (1)

[Claims] 1. Form a plating film made of a hard magnetic material containing at least cobalt and phosphorus on a plating substrate, and then use the plating film as a target by RF sputtering,
1. A method for producing a hard magnetic thin film, comprising forming a hard magnetic thin film containing at least cobalt and phosphorus on a sputtering substrate.