JP2541318B2 - Magnetic memory - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic storage medium for magnetically writing and reading information.

[Prior Art] Conventionally, a magnetic tape or a magnetic card is used as a magnetic storage medium for magnetically writing and reading information to and from a magnetic recording medium (hereinafter referred to as medium) through a magnetic head (hereinafter referred to as head). , A flexible disk, a hard magnetic disk (hereinafter referred to as a hard disk), and the like have been put into practical use, but in order to increase the recording density, a space between the medium and the head (hereinafter referred to as spacing) is used. ) Should be as small as possible.

Among them, in the hard disk, in order to increase the relative speed between the head and the medium, a floating head is used in which the head floats on the hard disk in a non-contact manner by utilizing the levitation force of the air flow. At present, the minimum spacing is 0.2 μm in a hard disk drive. In the hard disk, the substrate has been made of a hard material such as an aluminum alloy, a nickel-phosphorus plated film-coated aluminum alloy, an alumite-coated aluminum alloy, glass or ceramics to reduce the waviness and surface roughness of the substrate. The same applies to the medium and protective film formed on the substrate. The head surface facing the medium has also been made smooth and the surface roughness has been reduced.

[Problems to be Solved by the Invention] When a glass substrate is used as the substrate, the material is excellent in workability and can reduce the manufacturing cost of Li, K, Na.
Silica glass containing alkali metals such as or alkaline earth metals such as Ba, Mg, Ca, and Sr has been used. However, such an added metal reacts with moisture and carbon dioxide in the air to form reaction products such as hydroxide and carbonate. These reaction products cause volume expansion, or show hygroscopicity or strong basicity, corrode the magnetic medium coated on the substrate, or increase the surface roughness to make contact between the head and the medium. There is a problem in that the magnetic storage device is damaged and the reliability of the magnetic storage device is significantly impaired.

The present invention has been made in order to solve the conventional problems described above, and provides a magnetic memory using a glass substrate and having improved chemical and mechanical reliability of the magnetic memory. is there.

[Means for Solving the Problems] In the present invention, an ion diffusion preventing layer made of a ZrO ₂ · SiO ₂ composite oxide film is formed on a glass substrate, and at least a magnetic medium layer is formed on the ion diffusion preventing layer. It is a magnetic memory body characterized by the following.

In the glass substrate of the magnetic memory of the present invention, Li, K, Na or other silicate glass containing alkali metal such as Ba, Mg, Ca, Sr or the substrate surface is replaced with another alkali metal. A chemically strengthened glass (for example, Na is replaced with K) is used.

An ion diffusion preventing layer made of a ZrO ₂ · SiO ₂ composite oxide film is coated on the glass substrate. The prevention layer is formed by a sputtering method, a plasma chemical vapor deposition method (PCVD method) or the like.

A magnetic medium is coated on the prevention layer directly or through a coercive force increasing layer of Cr, Mo, W or the like. Magnetic media include FeO ₄ , γ-Fe ₂ O ₃ , Fe ₃ N ₄ , barium ferrite, and Fe ₅ C.
_2, such as iron oxides, ceramics such as iron nitride or iron carbide, Co, Co-Ni, Co-Ni-P, Co-Mn-P, Co-Mn-Ni
-P, Co-Re, Co-Ni-Re, Co-Mn-Re-P, Co-Ni-Re-P,
Co-Cr, Co-Cr-Ta, Co-Fe-Cr, Co-V, Co-Ru, Co-Os, C
o-Pt, Co-Ni-Pt, Co-Pt-Cr, Co-Pt-V, Co-Rh, Co-C
r-Rh, Co-Ni-Mo, Co-Ni-Cr, Co-Ni-W, Co-Ru, Co-S
Metals containing cobalt such as m, Fe-Mg, Fe-Nd, Fe-Ag, Fe
-Pd, Fe-Tb, Fe-Ti and other metals containing iron, Mn-Al, Mn-C
Metals including manganese such as u-Al are used. Is the above metal formed as a thin film by vapor deposition, sputtering, plasma chemical vapor deposition (PCVD), etc.,
Alternatively, it is prepared by applying a magnetic paint mixed as a fine powder into a polymer compound such as polyurethane resin, epoxy resin or phenol resin.

A protective film is coated on the magnetic medium as needed.
As the protective film, SiO ₂ , SiO ₂ , Si ₃ N ₄ , SiC or a silicon compound such as a silicic acid polymer by the sol-gel method, Al ₂ O ₃ , CoO, Co
O ₄ , Co ₂ O ₃ , α-Fe ₂ O ₃ , Cr ₂ O ₃ , TiO ₂ , ZrO ₂ , ZnO, PbO, NiO, MoO
₂ or SnO ₂ and other metal oxides, TiN, ZrN, CrN, TaN, BN and other metal nitrides, MoS ₂ , WS ₂ , TaS ₂ and other metal stocks, Ti
C, ZrC, CrC, TaC and other metal carbides, fluorinated graphite and other metal fluorides, or W, Cr, Ir, NiB, NiP, FeCr, NiCr, Sn, Pb,
Metals or alloys such as Zn, Tl, Au, Ag, Cu, Ga, Ru, Rh, Mn, Mo, Os or Ta or their alloys, Si, Ge, B, C (amorphous or diamond-like or mixture thereof) ) And other semiconductors, and plastics such as polytetrafluoroethylene, phenolic resin, and polyimide are used.

A lubricating layer may be coated on the protective film. As the lubricating layer, perfluoropolyether, fatty acid, fatty acid ester, silicone oil, fluorinated silicone oil, etc. are used.

The protective film and the lubricating layer also have the effect of preventing the entry of water vapor in the air and the reaction of the alkali or alkaline earth metal in the glass substrate.

[Operation] In the magnetic memory of the present invention, the ion diffusion preventing layer made of the ZrO ₂ · SiO ₂ composite oxide film is formed between the glass substrate and the magnetic medium layer. Therefore, the ion diffusion preventing layer prevents the added metal in the glass substrate from entering the magnetic medium layer, and prevents corrosion of the magnetic medium and increase in surface roughness.

Therefore, the magnetic memory of the present invention is characterized by less corrosion of the magnetic medium layer and contact / destruction between the head and the medium due to the reaction of the alkali metal or alkaline earth metal, and the conventional glass substrate was used. It has much higher reliability than magnetic memory.

[Examples] Hereinafter, the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG. 1 is a partial sectional view of an embodiment of the magnetic memory body of the present invention. As shown in FIG. 1, a glass substrate 2 made of soda-lime glass containing Na and Ca was sputtered.
Ion diffusion prevention layer 3 consisting of ZrO ₂ SiO ₂ composite oxide film
m was coated, and Cr was further coated thereon as a coercive force increasing layer 4 by 1 μm by a sputtering method. On top of that, a CoCr alloy as a magnetic medium layer is formed to a thickness of 50 nm by a sputtering method.
Then, a protective film 6 was coated with carbon by a sputtering method to a thickness of 2 nm, and a lubricating layer 7 was further coated with perfluoropolyether by a dipping method to a thickness of 2 nm to prepare a magnetic memory body 1.

Embodiment 2 FIG. 2 is a partial sectional view of still another embodiment of the magnetic memory body of the present invention. As shown in Fig. ₂ , ZrO ₂ · Si was sputtered on a glass substrate 22 made of chemically strengthened glass.
An ion diffusion preventive layer 23 made of O ₂ was coated with 200 nm, and a CoPt alloy was coated with 30 nm as a magnetic medium layer 25 thereon by a sputtering method. On top of that, carbon is used as a protective film 26.
A magnetic memory body 21 was prepared by coating it to a thickness of 2 nm by the PCVD method, and further coating a perfluoropolyether as a lubricating layer 27 thereon to a thickness of 2 nm by the dipping method.

Comparative Example 1 FIG. 3 is a partial cross-sectional view of a conventional magnetic memory body used as a comparative example. The manufacturing method is the same as in Example 1, except that the ion diffusion preventing layer is not covered and the coercive force increasing layer 44, the magnetic medium layer 45, the protective film 46, and the lubricating layer 47 are formed on the glass substrate 42.
A magnetic memory body 41 was manufactured by sequentially coating the above.

Next, with respect to the magnetic memory bodies obtained in Examples and Comparative Examples, a weather resistance test was conducted for 6 months at a temperature of 90 ° C. and a relative humidity of 95%, and an error rate was measured. After 6 months weather resistance test,
The magnetic memory of the present invention showed no deterioration in the error rate, and after the test, a mechanical durability test (CSS test) was repeated by repeatedly starting and stopping rotation. There were no scratches on the magnetic memory. Regarding the magnetic memory according to the comparative example, the magnetic medium film was corroded by the diffusion of Na, K and Ca from the glass substrate by the weather resistance test, or the error rate was increased 100 times or more due to the generation of protrusions by the reaction product. . Moreover, when a CSS test was conducted after the weather resistance test, a head crash occurred several times, and scratches reaching the substrate occurred in the magnetic memory body.

[Effects of the Invention] As described in detail above, the magnetic memory body of the present invention is excellent in weather resistance and mechanical durability, and as a result, reliability can be improved. Has the effect.

[Brief description of drawings]

1 and 2 are partial cross-sectional views of an embodiment of the magnetic memory body of the present invention, and FIG. 3 is a partial cross-sectional view of an example of the conventional magnetic memory body. 1,21,41 …… Magnetic memory 2,22,42 …… Glass substrate 3,23 …… Ion diffusion prevention layer 4,44 …… Coercive force increasing layer 5,25,45 …… Magnetic medium layer 6,26 , 46 …… Protective film 7,27,47 …… Lubrication layer

Claims (1)

(57) [Claims] 1. A magnetic memory characterized in that an ion diffusion preventing layer comprising a ZrO ₂ .SiO ₂ composite oxide film is formed on a glass substrate, and at least a magnetic medium layer is formed on the ion diffusion preventing layer. body.