JPS5914617A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a super-high density magnetic recording medium by adding Ti of the particular rate or less as the third element to the two elements system of Co-Cr. CONSTITUTION:Ti in such an amount up to 10wt% is added to the Co-Cr system. When Ti of 10% or more is added, crystal orientation is rapidly deteriorated and vertical magnetic anisotropy is lowered suddenly. A vertical magnetic recording medium which is outstandingly exceeding a limit of vertical magnetic anisotropy in the two element alloy of Co-Cr can be formed by including Ti of 10wt% or less in the Co-Cr film as described above and moreover a super-high density magnetic recording medium which has drastically improved recording density characteristic can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to magnetic recording materials, and more particularly to cobalt chromium perpendicular magnetic recording media.

Magnetic recording media are used in computer storage devices and are generally magnetized in the longitudinal direction of the recording media. However, such a magnetization method has a limit in increasing the recording density, and a method has been proposed in which magnetization is performed in a direction perpendicular to the surface of the recording medium, which makes it possible to achieve a much higher density. and,
Cobalt-o-chromium (hereinafter abbreviated as CQ-Cf) is used as a perpendicular magnetic recording medium that can be magnetized in the direction perpendicular to the magnetic thin MIIC, and a thin film is formed on the substrate by sputtering.

To create a perpendicular recording medium, it is necessary to provide perpendicular magnetic anisotropy that overcomes the demagnetizing field in the direction perpendicular to the film plane. Close-packed hexagonal cobalt has a large magnetocrystalline anisotropy in the C-axis direction, but due to its large magnetization, the shape magnetic anisotropy energy is large1, and a perpendicular magnetic anisotropic film cannot be obtained. Therefore, it is possible to reduce the saturation magnetization by adding Ri-Rom and to create a perpendicular magnetic anisotropic film by strongly aligning the C-axis of the close-packed hexagonal crystal in the direction perpendicular to the substrate. become. However, if ultra-high-density magnetic recording is realized, the demagnetizing field for one bit should be much smaller than the maximum demagnetizing field for thin films, 4πMJ (Mg is saturation magnetization)6; It is considered that there is no need to satisfy the condition Km >2πMg'' (Ks is the crystal anisotropy constant of the magnetized film).

On the other hand, in the case of a CQ-Cr perpendicularly magnetized film, the saturation magnetization of cobalt decreases continuously as the chromium content increases, whereas the saturation magnetization of the CQ-Cr perpendicularly magnetized film shows a slightly higher decreasing tendency than that of the chromium content. From this, it was predicted that chromium was polarized at the grain boundaries, and this was recently confirmed by Auger electron spectroscopy analysis of a cross section of the film. In order to lower the saturation magnetization and reduce the demagnetizing field, a moderate amount of chromium is mixed into each crystal grain, and chromium is polarized at the grain boundaries and forms a nonmagnetic layer, which causes domain wall movement. An ideal perpendicular magnetic recording medium would be to reduce the magnetization mechanism due to the magnetic field, magnetically separate crystal grains, and only rotate the magnetization of single domain grains.

Conventional Co--Cr perpendicular magnetization recording media exhibit perpendicular anisotropy of the film (in particular, the perpendicular anisotropy field is expressed by the perpendicular anisotropy magnetic field HE).

), the vertical coercive force Hc(1) also increases.

Place a Cf pellet on a 4 inch co target and
．． An example in which 5 μm thick polyimide was formed by RF magnetron sputtering will be described below.

Example 1: Initial degree of vacuum: 3 X lO-' torr Input power: IK7 70mA Time IAosr: Example 2: Initial vacuum: 3.5 This is an example when the input power is changed, but the same tendency is shown when the substrate is heated.

Due to the heat applied during film formation, the coercive force H
c and the anisotropic magnetic field Hz also rise. However, this is actually very inconvenient. It is naturally desirable for perpendicular recording media to have high H and K as in Example 2, but if HC(L) is too large, magnetic heads using ferrite, permalloy, sendust, amorphous soft magnetic materials, etc. will be saturated. In order to do this, the current flowing through the head must be made extremely large. Even if saturation recording is possible, erasing is difficult and override characteristics deteriorate. On the other hand, in a case like Example 1, although the write current and override characteristics are improved, the original perpendicular anisotropy field of perpendicular magnetic recording is small, so the magnetization reversal in high-density recording is not sharp. , recording density characteristics deteriorate.

In view of these points, the present invention solves these difficulties by further adding titanium as a third element to the Go-Cr system.

An object of the present invention is to provide an ultra-high density magnetic recording medium by magnetically separating crystal grains.

Another object of the present invention is to dramatically increase the output and resolution in ultra-high density magnetic recording of 1QQKFRP or higher.

The present invention is clearly effective when adding up to 10% by weight (hereinafter abbreviated as wt) of titanium C (hereinafter abbreviated as T4) to cm -Cr.

When the amount of T6 added exceeds 10 wt%, the crystallinity of the film is significantly reduced, and the perpendicular magnetic anisotropy of the film is sharply reduced.

Conventional cOcr binary systems are said to have good magnetic properties and crystal orientation when Cf is in the range of 12 to 30 wt, but the addition of Ti in the present invention expands the lower limit of Cf content compared to the case of cylindrical systems. Shi also showed good characteristics. FIG. 1 shows the effects of the present invention. The numbers in the table represent the contents of Cr and Tj in Co in weight%. The shaded area is the area where the perpendicular magnetic anisotropy has been improved by the present invention, and the other areas are areas where the effect of the present invention is not exhibited.

Specific examples include DC sputtering, RF sputtering, magneto four sputtering, facing target sputtering, electron beam evaporation, plating, and other thin film manufacturing methods, and the present invention applies regardless of substrate materials such as polyethylene terephthalate, polyimide, glass, and alumite-treated aluminum substrates. There is an effect of adding Ti. In general, perpendicular magnetic recording media may have a single perpendicular magnetic recording layer or a high magnetic permeability layer provided thereunder as a backing layer. , CQ-based, and Fg-based amorphous high permeability thin films can be modified in various ways.

The present invention will be explained below with reference to Examples.

Example 1 CQ Cr and CQ- using polyimide substrate KRF power supply
A cp-T6 perpendicular magnetization film was formed.

The target is Col:31Dt% CfeC
016u) t%CfC020wtellr Cr and three types of CQ-Cf alloy targets were used. C6-Cr
-T4 ternary perpendicularly magnetized films were prepared by arranging Tt pellets with a size of 5X5X1s+a on a cm-Cr alloy target so that the distribution was uniform to produce thin films with various ri amounts.

The content of each component was determined by XMA.

Sputtering conditions Before sputtering, the Pelger was baked and the polyimide substrate was degassed. A sputter Chusha substrate holder was water-cooled. The sputtering time was 1.15 minutes, and the film thickness was approximately 0.5 minutes.
It was 6.μm. The half width Δθso of the rocking curve and the magnetic properties of the produced film are shown below.

c(, -13wt% When T4 pellets are placed on the cr target, t- is shown in Table 1. Similarly, 1fCCo -16
The target ratios of wt% Cr and C0-20wt%C0wt%C are shown in Tables 2 and 3, respectively.

Table 1 (Cerr 'tts') too-ZTf
(Displayed as weight %) Table 2 CCOmCsee-cT
iz Table 3 (ao 帥Cr@)yH-ycTiz A diagram showing the relationship between the anisotropic magnetic field HK and T (quantity) is shown in FIG.

This data is the average of three experiments, and the Ti amount has an error of ±1%. Based on this data, we can see the following.

○By adding T6 below LOwtli, the perpendicular magnetic anisotropy increases by nearly 20 inches.

As the amount of OCr increases, the amount of Ti that takes the maximum value of the anisotropic magnetic field HK shifts toward the lower side. B-chi, CO*oo-
Z CrZ (D The optimum amount of SiRI addition varies depending on the zO value.

○ When 10 wt% or more of T4 is added, the crystal orientation deteriorates rapidly and the perpendicular magnetic anisotropy also decreases rapidly.

Example 2 A video tape was produced using a facing target type sputtering device and subjected to image processing.

FIG. 3 shows a schematic diagram of the facing target type snow vine device, showing a Co-Cr binary target 1, a dedicated DC power supply C (hereinafter referred to as DC power supply) 2, and a C6-Cr- installed opposite to it. Tj Between the ternary target 3 and the dedicated DC power supply 4, there is approximately 3
This configuration generates a magnetic field of 0.00 Gauss and includes an electromagnet 6 outside the Pelger so that the substrate 5 is not exposed to plasma. The board 5 is designed so that it can be rolled up using a roll method, and there is a board holder 7 that can be heated and cooled with water at the rear.
It also has a button that can be moved up and down by a guide rod linked to it.

Sputtering conditions In this facing target sputtering system, each electrode is provided with an independent power supply, so the T in the C0-Cr film is
6 The amount of K can be changed by changing the power applied to the target, and the variation in film thickness distribution caused by changing the power was controlled by controlling the substrate holder and the top and bottom of the substrate.

Figure 3 shows the changes in 60 horses and HK when changing TZi. In the range where T6 is 10% or less, HE increases rapidly due to the addition of T.However, when T6 is added in excess of 10%, polycrystallinity and its orientation worsen with abnormally large Δθso. It seems that he did.

The tendency in FIG. 4 is exactly the same as that in FIG. 2, and there is no difference depending on the film forming apparatus and substrate.

Example 3 Using the 8-inch magnetron sputtering apparatus, a 5-inch colloppy media for recording/reproduction evaluation was produced. This sputtering apparatus is equipped with three 8-inch targets, and the electrode L has a co-metal target film composition of Dv m.
G? A Zf pellet was placed so as to form a "grain" (indicated by weight %). Electrode 2 was a Go-16wt%Cf target, and electrode 3 was a CO-16wt%Cf tercerat with a T
6 pellets with film composition (CouCde1@)asTi4
It was arranged so that

The substrate used was .mu.m thick polyethylene terephthalate. Generally, PET or Mylar is used, and since it has poor heat resistance, a film was formed using a DC power source. The sputtering order is C01162 on separate substrates.
? After forming a 'lS film with a thickness of Q and 3 μm under the same conditions, a CQ film was formed on one substrate, and a 4Cf16 film was formed with a thickness of 0.6 tim on another substrate (
A Cfi efts)n Tj4 film was produced for 0.6 turns. Later, a film was formed on the opposite side under the same conditions so that there was no warpage on the mesodermal skin.

Sputtering Conditions FIG. 5 shows the structure of the media produced according to this example. Media A is coated with 0.0 mm on both sides of □□□μm Mylar 8.
Media B consists of a 3μm thick CON""Ill amorphous soft magnetic film 9 and a 0.6μm thick CO2 perpendicularly magnetized film 1 (). C05i""Is amorphous soft magnetic film 9 with thickness and (Cou ('rts)os'r with 0.6 m thickness)
<44 perpendicular magnetization film 1'l is formed. Table 4 shows the characteristics of each film.

"LSc (184°rtsjl and (Cou Cr1@
) 911T (Film 4 has the characteristics of the CQZf amorphous film underlying layer 1 removed by etching.

Table 4 Media A composed of a film exhibiting magnetic properties as shown in Table 4
FIG. 6 shows the recording density characteristics tl when recording and reproducing were performed using Media B111-11.3 μm thick permalloy main pole-auxiliary pole type head. FIG. 6 is plotted on a log-log graph. The vertical axis represents relative output, and the horizontal axis represents recording density in units of (KFRP units).

From the same figure, media B has a second peak.

The output of the third peak has increased significantly.

This means that c6crT6, which is a C0Cr film with Ti added to it,
In practical use, the ternary perpendicularly magnetized film is superior to the COCR binary film, and can sufficiently perform magnetic recording with a working height of 9.100 KF'RP or higher.

Example 4 1 non-magnetic amorphous C05oTcLs on a 5-inch anodized aluminum disk using a Magneoron sputtering apparatus with an 8-inch target.

(wt%) was formed to a thickness of 0.5 μm, and the disk GK was co
@4Cr16 is 0.3μm, disk DK is (c014
Cr1g) esTjs4 was fabricated to a thickness of 0.3 μm.

The configuration diagram is shown in FIG. Table 5 shows the magnetic properties of the above two types of disks.

The purpose of providing the 0.5 μm non-magnetic amorphous CO,,'r copper layer as the lower layer was to reduce the roughness of the alumite-treated disk surface, and to form the Co84 Cr5s and (G
o, 4C? ha) This is to improve the magnetic properties of mTis.

Recording and reproduction were performed using the above two types of discs with a 5-inch Winchester disc drive.

In order to reduce the flying height, from the standard 360 Orpm,
Dropped 11000rp Ic. The floating height is 0.2μm
That's about it. The magnetic head is a standard Mn-Zn-7
Elite, the gap was 1 μm. FIG. 8 shows recording density characteristics when discs C and D are used. The vertical axis is relative output, and the horizontal axis is recording density (unit: KFRP)
Compared to Disc D and Disc C, which had 4% Tt added, twice the output was obtained at the second peak value.

Note that the present invention is not limited to the above embodiments.

Other means than sputtering that can produce the CoCrTj a-based alloy, such as electron beam evaporation, plating, and roll methods, may also be used. In addition, in Example 2, an example was given in which an improved device with a facing target method was used.
There is nothing wrong with using the same ternary material for both types of targets and using a common DC and high frequency power source. In addition, the data of Examples 1 and 2 are for the case where the substrate is water-cooled, and the characteristics of the -Cr binary alloy film, for example, under the production conditions where a4K = 6800 is high, the addition of Ti may The effect of increasing He from -7800 to 8500 remains the same.

As explained above, the present invention provides a film with a
We created a perpendicular magnetic recording medium containing 10% by weight or less of C0Cr, which greatly exceeds the limit of perpendicular magnetic anisotropy in binary C0Cr alloys, and created an ultra-high-density magnetic recording medium that significantly improved the current recording density characteristics. It is something to put out.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the present invention in detail. Figure 2 shows
Figures 3 and 4 are for explaining Example 1 and show changes in the anisotropic magnetic field El with respect to the amount of Ti added, and Figures 3 and 4 are for explaining Example 2, respectively. A diagram showing the change in film properties depending on the amount of Ti.
Figures 5 and 6 are for explaining Embodiment 3; media configuration diagrams and recording density characteristics of each media; Figures 7 and 8 are for explaining Embodiment 4. This is a block diagram of a magnetic disk and the recording density characteristics of each magnetic disk. 1 Working・CQCf alloy target 2・・DC power supply 3・・C6cyT6 alloy target 4・・DC power supply 5・・Substrate 6・・Electromagnet 7・・Substrate holder 8・・Mylar (50 μWL) 9 mm C6Zr film (0, 3μ) IQ a a
CQCr film (0.6 μm) 11 mm C6CrTi
Membrane (0,6Jl?71) 12... Aluminum disk (1,
9 tone) 13--Alumite 14 m e CoTa film (0.5tsn) 15 e
* CoCr film or CoCrTi film (0.3 μm
) and more Applicant Suwa Seikosha Co., Ltd. Agent Patent Attorney Mogami Figure 1 η (Koya) Figure 2 ψ Figure 3 Figure 4 Figure 5 Takuya l Figure 6 Figure 7 Kennobu @ fL CyFRrI') Figure 8

Claims (1)

[Claims] 10) A perpendicular magnetic recording medium characterized by having cobalt-chromium containing titanium of less than telA.