JPH0922526A - Production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a carbon coating film or a film essentially comprising carbon with good adhesion property by forming first a silicon oxide layer on an oxide magnetic recording layer and then forming the carbon film. SOLUTION: A silicon-based film and a silicon carbide-based film are formed and etched under reduced pressure by introducing hydrogen as a carrier gas from the line 2 of a gas system 1 and introducing hydrogen silicide as a reactive gas through a nozzle 10 in a reaction system 9. A magnetic material with addition of a specified material formed on an aluminum substrate is prepared as the oxide base material and is mounted on a first electrode, namely, which is grounded by selecting switches 18, 19. Then the reaction system is evacuated to remove the residual gas on the base body and in the reaction chamber, and the specified reactive gas is introduced to the chamber and controlled to a specified inner pressure of the reaction chamber with a pressure controlling valve 21. High frequency voltage is applied between a pair of electrodes 11, 12 to make plasma of the reactive gas.

Description

Detailed Description of the Invention

[0001]

The present invention relates to the application of a carbon-based coating as a protective layer to a magnetic recording medium having an oxide surface, which improves the interfacial properties, particularly the adhesion, and is characterized by the characteristics of the carbon-based coating. It maximizes certain properties such as abrasion resistance, high smoothness, and high hardness.

[0002]

2. Description of the Related Art Heretofore, attempts have been made to form carbon or a film containing carbon as a main component on a wide variety of substrates, but satisfactory adhesion has not always been obtained due to differences in underlying substrates. is the current situation.

In particular, on an oxide magnetic recording medium,
Since essentially no good interfacial properties and good adhesion can be obtained with carbon-based coatings, the development of new technologies is urgent.

[0004]

It is considered that the reason why the interfacial adhesion is not good is that carbon-based organic contaminants or oxidative contaminants are impregnated in the base material or adsorbed on the surface. However, there are many unclear points how these work. It is well known that the above contaminants can be reduced by ozone treatment using UV (ultraviolet rays) or vacuum heating treatment and ion bombardment treatment.

However, when the substrate itself is an oxide, the surface of the substrate has a bond via oxygen. When a carbon-based film is formed there, carbon and oxygen react near the interface to form CO, which is adsorbed or contained at the interface.
Since this is originally a gas, it separates from the surface. As a result, even if carbon or a film containing carbon as a main component is formed on these upper surfaces, if a CO bond is present at the interface, the bond is inherently gaseous, so that the bond is initially and temporally adhered. It is clear that the sex is reduced. The interatomic bond energy is shown below.

C—O 256 Kcal / mol C—C 144 〃O-H 102 〃Fe-O 98 〃C-H 81 〃Si-O 192 〃Si-C 104 〃H-H 104 〃Si-H 75 〃

There is also an attempt to form an amorphous silicon film (containing no oxygen) on the surface of the oxide. In this case, however, since the oxidizing power in the silicon is strong, the oxide magnetic recording medium of the base material is not used. The stoichiometric ratio of oxygen is changed, and the recording characteristics are likely to deteriorate.

[0008]

According to the present invention, the lattice constant, the coefficient of thermal expansion or the stress strain is changed before forming carbon or a coating film containing carbon as a main component on a substrate having an oxide magnetic recording medium surface. It is characterized by providing a silicon oxide layer as a buffer layer between the underlying base material and the carbon-based coating, which is relaxed and does not damage the recording ability of the base material oxide magnetic recording medium.

In particular, stress relaxation between a carbon-based coating having a compressive stress of -5 to -20 × 10 ⁹ dyn / cm ² and a substrate having an underlying oxide surface, and an interface between the underlying coating and the underlying substrate. By eliminating the CO 2 bond, it is possible to form a carbon-based or carbon-based film with improved adhesion on an oxide substrate, which has been difficult in the past.

[0010] Through the coating of a carbon film, a patent application “Method of forming a coating containing carbon or carbon as a main component” (filed on March 2, 1988) filed by the present applicant is known. Have been. In order to achieve the above object, an outline of an apparatus for producing a buffer layer and a carbon-based coating used in the practice of the present invention will be described with reference to examples.

[0011]

【Example】

[Embodiment 1] FIG. 1 shows a parallel plate type plasma apparatus.
From (2), a hydrogen silicide gas, such as silane or disilane, which is a reactive gas, is converted into a hydrocarbon gas, such as methane or ethylene, as described in (3). Nitrogen fluoride, sulfur hexafluoride, etc. from (5), and nitrous oxide (N ₂ O) (6) as a gas for oxygen addition via valve (7) and flow meter (8) (9) Introduce from the middle nozzle (10). In the reaction system (9), a silicon-based coating, a silicon carbide-based coating, and a carbon-based coating are formed under reduced pressure and their etching is performed. The reaction system (9) has a first electrode (11) and a second electrode (12), and a pair of electrodes (11), (1
During 2), electric energy is applied from the high-frequency power supply (13), the matching transformer (14), and the DC bias power supply (15) to generate plasma. In order to promote the further decomposition of the reactive gas, it is better to use microwave excitation of 200W to 2KW at 2.45GHz microwave.

According to this embodiment, γ-Fe ₂ O ₃ or a magnetic material to which an additive is added to an oxide substrate, for example, an aluminum substrate, is used as a first electrode, ie, a changeover switch (18), (1).
9) was selected and set on the ground side.

This is to prevent the base material from being damaged due to bias when forming the buffer layer.
Next, the reaction system was evacuated to 1 × 10 ⁻⁵ torr or less to remove residual gas on the substrate and in the reaction vessel. Thereafter, a reactive gas of monosilane, for example, H ₂ -based 3% silane and N ₂ O were introduced. Then, N ₂ O / SiH ₄ was varied from 1 to 0.01. The pressure inside the reaction vessel is 0.01 to 1 torr, typically 0.1 torr
r was adjusted with a pressure adjusting valve (21), a high frequency voltage was applied, and the reactive gas was turned into plasma.

Next, FIG. 2 is a longitudinal sectional view showing a silicon oxide formed on γ-Fe ₂ O ₃ (24), and a protective material containing carbon or carbon as a main component. A layer (26) was formed. That is, formation of the silicon oxide layer (25), N ₂ with deposited
The addition amount of O was reduced, and the addition was zero at the end of the buffer layer.

The deposition rate is controlled at 10 mm / min, and the thickness is 20 to
500 mm, typically 100 mm. Next switch
(18) and (19) are selected so that the base material is on the high frequency application electrode side (cathode side). This is because a DC bias is applied when forming the carbon film. In this state, the reactive gases methane and hydrogen are introduced at a ratio of 2: 1.
The reaction gas was adjusted to 0.01 to 1.0 torr, typically to 0.1 torr, and a high-frequency voltage was applied to convert the reactive gas into plasma. Then, due to a difference in mobility and a difference in mass between the ions and the ions in the plasma, charges are accumulated in the electrode to which the high frequency is applied. Then, an electric field is generated between the potential of the plasma and the positive ions (for example, C, CH, CH ₂ , H) left in the plasma are accelerated. Is etched away
SP ³ Amorphous mosquito has binding - it is possible to deposit the carbon. As a result, a hard carbonaceous film
The film is formed at a film forming speed of in. 100 to 5000 mm, typically 1000 mm. Unnecessary substances after the reaction are pressure-adjusted from the exhaust system (20).
(21), the gas is exhausted through a turbo molecular pump (22) and a rotary pump (23).

The carbon-based coating thus obtained has a Vickers hardness of 1000 to 7000 kg / mm ^2, typically around 2000 to 2500 kg / mm ² . As described above, the oxide magnetic recording medium shown in FIG. 2, for example, the base material (24), for example, glass
/ mm ² , buffer layer (25) 1000 kg / mm ² , carbon-based coating (26)
A configuration of 2000 to 2500 kg / mm ² was obtained, and the distribution of AA ′ in the depth direction was measured by SIMS (secondary ion mass spectrometer). As a result, FIG. 3 (A) was obtained. In this drawing, iron (31), silicon (33), and carbon (34), while oxygen (32) is carbon (26) from the recording medium (24) side
It can be seen that it is gradually decreasing on the side. As a result, a carbon protective film with good adhesion could be formed without deteriorating the recording characteristics of the underlying oxide medium. The average concentration of oxygen in this buffer layer is 1 × 10 ¹⁹ cm ⁻³ or more,
It was less than the amount of oxygen having Si: O = 1: 1.

Example 2 In this example, the same apparatus as in Example 1 was used. Oxygen was added only to the oxide recording medium side, and then the addition of N ₂ O was stopped. The silicon layer or silicon carbide layer, the first buffer layer (32-1), and the second buffer layer (32-2) In a two-layer structure. A buffer layer (25) was laminated on these multilayer structures. Thereafter, as in Example 1, carbon or a film (26) containing carbon as a main component was formed. Then, oxygen is added to the oxide magnetic recording medium side,
Except for the deterioration of the recording characteristics, oxygen and carbon were prevented from being mixed with each other on the protective layer side containing carbon or carbon as a main component, thereby generating CO 2 bonds. As a result, good adhesion and
The recording characteristics could be improved.

[0019]

According to the present invention, an interfacial stress relieving effect can be obtained on a substrate which has been considered difficult, especially on an oxide substrate.
That is, the buffer layer can be expected to have the effect of controlling the stress in a stepwise manner and preventing interfacial CO 2 bonding by preventing direct contact between the oxide and the carbide, which are considered to be essentially inconsistent.

[0020] and CSS - in (contact Star door stop), I was able to create a protective film that does not result in any of the properties decreased in 10 ⁴ to 10 ⁵ times. From the above, it has been found that there is a great improvement effect on the interface characteristics, especially on the initial stage and the change over time of the adhesion.

According to the present invention, an industrially practicable magnetic recording medium can be manufactured for the first time by bringing carbon into close contact with a magnetic material and by bringing it into close contact with silicon oxide.

[Brief description of drawings]

FIG. 1 shows an outline of a parallel plate type plasma apparatus used for carrying out the present invention.

FIG. 2 shows a cross section of a carbon-based coating formed via a buffer layer manufactured according to the present invention.

FIG. 3 is a distribution in a depth direction of a magnetic recording medium manufactured according to the present invention.

[Procedure amendment]

[Submission date] August 21, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (1)

[Claims] 1. A second container in which a silicide gas and an oxide gas are introduced into a reaction vessel capable of being kept under a reduced pressure, and a first electrode and a substrate having an oxide magnetic recording layer as a formation surface are mounted thereon. After the gas is decomposed by plasma generated by applying direct current or high frequency energy between the electrode and the silicon oxide layer to form a silicon oxide layer, a hydrocarbon compound gas or, in addition thereto, decomposes an additive gas. A method for producing a magnetic recording medium, which comprises reacting to form carbon or a coating film containing carbon as a main component on the silicon oxide layer.