JPS5820734A - Preparation of magnetic thin film of oxide - Google Patents

Abstract

PURPOSE:To obtain a magnetic thin film of oxide useful as a magnetic disc medium, by spattering Fe3O4 pieces or alpha-Fe2O3 pieces placed on an iron target in a given gas atmosphere. CONSTITUTION:Fe3O4 pieces, alpha-Fe2O3 pieces, Fe3O4 pieces containing an additive, or alpha-Fe2O3 pieces containing the additive are placed on a Fe target containing Fe or an additive. They are spattered in an atmosphere of a mixed gas of a neutral gas or an oxidizing gas. A thin film of a ferromagnetic iron oxide consisting essentially of Fe3O4 or Fe3O4 containing an additive is formed on a base plate. Consequently, a magnetic thin film of oxide useful as a high-density recording medium is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an oxide magnetic thin film used as a recording medium in a magnetic disk device or the like.

Improving the recording density in magnetic recording devices is a constant trend in this industry, and to achieve this it is essential to make magnetic recording media thinner and thinner.

Conventionally, so-called coating media in which a mixture of iron oxide fine particles and a binder is coated on the entire substrate have been widely used as magnetic recording media. However, with coating media, it is extremely difficult to achieve uniform recording and reproducing characteristics with a thickness of several thousand angstroms or less.

Therefore, continuous thin film media, which can be easily made into thin films, are attracting attention as high-performance magnetic media that can replace coating media. Although metal plated films have already been considered as continuous thin film media, oxide magnetic thin films have recently attracted attention. The reasons for this are: 1) the residual magnetic flux density is low, 2) it has high mechanical strength and chemical stability, and does not require the protective film required for thin metal films, and 3) the magnetic head-medium distance. This is because it can be made smaller and is suitable for high-density recording and low cost.

Iron oxide thin films are mainly used as oxide magnetic thin films because they are easy to form, but methods for producing them include sputtering (reactive sputtering in an oxidizing or reducing atmosphere), reactive vapor deposition, and CD. (Cheml
cal deposition) method, CVD (Chem
lcal Vapered Deposition)
There are laws, etc. Among these, the sputtering method is an excellent method because of its advantages such as good adhesion between the medium and the substrate, the ability to form a strong outer thin film, and suitability for continuous production.

The reactive sputtering method in an oxidizing atmosphere in this sputtering method includes methods called a "direct method" and an "indirect method." The "direct method" is a method in which a Feast film is directly formed by sputtering Fe under a constant oxygen partial pressure using a target, and the "indirect method" also targets iron, but sputtering is performed in a region with a high oxygen partial pressure. ,
This is a method in which an α-Fetus thin film is once deposited on a substrate and then subjected to reduction treatment to form Fe5Oa. Therefore, the "direct method" has the advantage of requiring a smaller manufacturing process.

However, it has been found that it is difficult to form the desired Fe504 film when forming the Fe5O4 film by this "contact method" under conditions of high sputtering rate for the purpose of increasing productivity. In the case of high-speed sputtering, a higher oxygen partial pressure than that during conventional low-speed sputtering is required to produce Fe atoms iFes (M), but this often results in oxidation of the target surface. This caused the formation of α-Fe*Os.There was a problem in that it was difficult to control the target surface to an appropriate state and perform sputtering under such high sputtering rate conditions.

The present invention aims to solve these problems, and one of its aims is the same as the "direct method" (the target is Fe, but in order to deal with high-speed sputtering, the total oxygen partial pressure introduced during sputtering is The object of the present invention is to provide a method for completely preventing excessive oxidation of the FC target surface and stably forming a FeaQa film without making it too large.

The present invention provides F
4 pieces of eas or α-FezQs pieces or Fe soa pieces containing additives or α-Fezes pieces are arranged,
It is characterized by forming a ferromagnetic iron oxide thin film containing pasQ4 or an additive as the main component on a substrate by sputtering in a mixed atmosphere of neutral gas and oxidizing gas. It is.

According to the present invention, it is possible to obtain an oxide magnetic thin film that can be used in magnetic disk media and the like and can be formed stably and efficiently even at high sputter rates.

Next, the present invention will be explained in detail with reference to Examples.

Example 1 Using a commercially available sputtering device, Fe f was used as the target as shown in the table, and a small piece of Fe504 (lxlcIn, thickness 2
1111) was dispersed and pre-sputtered for 20 minutes under the conditions shown in the table. After that, a main sputtering session was carried out to obtain a 0.16 μm film on an alumite-coated aluminum alloy substrate at a deposition rate of 7 oz-. This film was a film mainly composed of Fe5O4f and had a saturation magnetic flux density Ba of 4000 Gauss and a coercive force of 165 Oersteds.

Example 2 A Fe target was used as in Example 1, but as shown in the table, a small piece of α-Fetus (0.7×0.7q thickness 2
m111) A thin film of α18 μm was formed on the alumite-coated aluminum alloy substrate by dispersing and distributing it on the t-target and performing preliminary sputtering and then main sputtering.

At this time, the film deposition rate was 16,017 ml, which was impressive.

As a result of measuring magnetic properties, the film was mainly composed of Fe5Oa with a saturation magnetic flux density of 3900 Gauss and a coercive force of 225 oersteds. As in this example, α-FezOst
- By using Fe504 film 't1M, it was possible to form the film on the substrate.

Example 3 It is known that Co added to an iron oxide magnetic thin film is useful for increasing coercive force. Cobalt t-i as shown in the table
, Cobalt on top of 5% Fe target! -1.5% fully doped Fe1Oa pieces (IXII:
M, thickness 2111)'ft, and pre-sputtering followed by main sputtering to sputter-lay a 0.18 μm thin film on the alumite-coated Arun alloy substrate)2
It was formed with 70A/-. This film has a saturation magnetic flux density of 3100
Gauss, Fe5O4 with coercive force 450 oersted? It was the main ingredient. Note that this film annealed at a temperature of t-320°C for 1 hour has a specific resistance of 103Ω or more,
Nine films suitable for magnetic disk media were obtained with a saturation magnetic flux density of 3000 Gauss and a coercive force of 600 Oersteds.

Example 4 In order to increase the sputtering lay, a magnetron type sputtering device was used, and as shown in the table, P6S94 pieces (IXlz, thickness 2 fl) were placed on the Fe target to cover 40 mm of the target area. Place and preliminary sputtering? After 20 minutes, main sputtering (rate 50
0^, 4) A gX of 0.17 μm was obtained on an alumite-coated aluminum alloy substrate by t-conducting. As a result of measuring the magnetic properties of this film, it was found that the main component was FeSO4'e with a saturation magnetic flux density of 3000 Gauss and a coercive force of 200 Oersteds. By increasing the amount of Fe5OaO and lowering the introduced oxygen partial pressure as in this example, is it possible to increase the amount of Fe5OaO (sputtering)? It was possible to easily form a Fe504 film.

In the above examples, Fe504 pieces and α-pss
QsOa and α-Fe are placed on a single target, but at this time, due to the heat generated during sputtering, esOa and α-Fe
ll'esQa or α-F to prevent deterioration of sQ1 piece
Bonding the ezOiiFe target surface with a good thermal conductor has a great effect on improving reproducibility.

As described above, all Fe504 or α-Feze pieces, Feast pieces or α-FezOa pieces containing additives are placed on a target containing iron or additives, and a mixed atmosphere of neutral gas and oxidizing gas is placed. According to the method for producing an oxide magnetic thin film according to the present invention, in which a ferromagnetic iron oxide thin film containing FezO4 or an additive Kanekura Pea04 as the main component is directly formed on a substrate by sputtering, Widen the manufacturing margin during film formation compared to the Fe t-targeting method,
This has the effect that a higher deposition rate can be obtained and a recording medium for high-density recording can be easily formed with high manufacturing efficiency.

Claims (2)

[Claims] (1) Fe1 on iron target containing iron or additives
By placing Fe5Oa pieces or α-Feign pieces containing Fe504 or α-Fe11rs pieces or additives and sputtering them in a mixed atmosphere of neutral gas and oxidizing gas, the main component of Fe3O4f containing Fe504 or additives is obtained. 1. A method for manufacturing an oxide magnetic thin film, comprising: forming a ferromagnetic iron oxide thin film on a substrate. (2) Fea on iron targets containing iron or additives
r; F containing pieces or α-Fezes pieces or additives
By arranging e5Oa pieces or α-Fezes pieces and sputtering in a mixed atmosphere of neutral gas and oxidizing gas, Fe5Oa or additive Kanakuramu p
A ferromagnetic iron oxide thin film containing 63Q4 t- as the main component was formed on a substrate.