JP3113358B2 - Magneto-optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rewritable magneto-optical recording medium. More specifically, the present invention relates to a magneto-optical recording medium in which a recording film having a Pt layer, for example, an alternately laminated film composed of Pt / Co is formed on a substrate via a ZnO underlayer.

[0002]

2. Description of the Related Art As a recording film (perpendicular magnetization film) for a magneto-optical recording medium which can be repeatedly recorded / reproduced, an alternately laminated film comprising Pt and Co alternately laminated has been proposed. This is because the Pt / Co alternately laminated film has good sensitivity in a short wavelength region and is promising as a high-density recording medium. In addition, as shown in FIG. 4, a dielectric film such as SiN is formed as an underlayer 10 between the alternately laminated film and the substrate as shown in FIG. The surface 11 is usually subjected to an etching process for smoothing (the 14th Annual Meeting of the Japan Society of Applied Magnetics P65).

[0003]

A dielectric film such as SiN is formed as a base layer 10 on a substrate, and a Pt / C
In the above-described configuration in which the perpendicular magnetization film composed of the alternately stacked films of O is formed, SiN is in an amorphous state. For this reason,
Initially, the Pt layer formed on the SiN film is [11]
1) The layers are not stacked neatly in the direction, and the perpendicular magnetic anisotropy is small. Therefore, the coercive force required for high-density recording is also 1 [k
Oe].

In view of the above problems, the present applicant has first devised a magneto-optical recording medium using ZnO as an underlayer,
An application has been filed [1991 Patent Application No. 126087 (Japanese Unexamined Patent Publication No. Hei 4-351733)]. In the magneto-optical recording medium of the above-mentioned application, the underlying layers (ZnO) are densely arranged like Pt as viewed from the [111] direction. For this reason, the underlayer (Zn
The Pt layers formed on O) are also easily aligned in the [111] direction, and the coercive force required for high-density recording is improved as compared with the conventional case using a SiN underlayer.

However, in the configuration of the above application using ZnO as the underlayer, the interatomic distance of Pt as viewed from the [111] direction is 2.8 [、 ２], whereas the interatomic distance of ZnO is Is as large as 3.25 [Å], and there is a considerable difference between the two. For this reason, it is difficult to arrange the Pt layers densely from the beginning of the lamination, and the coercive force is insufficiently improved.

The present invention relates to the above-mentioned application [1991 Patent Application No. 1
No. 26087 (Japanese Patent Laid-Open No. 4-351733)], and a magneto-optical recording medium formed on a substrate such that a Pt layer of a recording film having a Pt layer is in contact with an underlayer (ZnO). The purpose is to further increase the magnetic force.

[0007]

According to the present invention, there is provided a magneto-optical recording medium comprising an alternately laminated film comprising a Pt layer and a transition metal layer formed so that the Pt layer is in contact with an underlayer on a substrate. Then, while using ZnO as the underlayer,
O is characterized by containing N or C to form a film having orientation.

In the above, the amount of the N or C element to be added to ZnO as the underlayer is 0 to 40%.
(Excluding 0%), preferably about 3 to 40%. That is, if it exceeds 40%, the structure of ZnO shown in FIG. 3 is broken, so that the intended purpose of "closely arranged like Pt viewed from the [111] direction" cannot be achieved, while 3% If it is less than 3, the effect of bringing the interatomic distance of the underlayer closer to 2.8 [原子], which is the interatomic distance of Pt, cannot be sufficiently achieved. The elements to be added may be plural types. The element replaced by the added element may be any of Zn and O.

The magneto-optical recording medium of the present invention has another conventional structure, for example, a dielectric layer as a protective film, or
As in the conventional case, another structure such as a reflective layer for adding the Faraday effect to the Carr effect by multiple reflection may be added. Further, as the substrate, glass, polycarbonate (PC), polymethyl methacrylate, epoxy resin or the like can be used as in the conventional case.

[0010]

In the formation of the underlayer (ZnO) to be in contact with the Pt layer, if the N or C element is added in the above-mentioned amount as described above, the crystal structure is the same as the original structure of ZnO, and the added element is added. Partially replaces Zn or O. As a result, the interatomic distance is reduced, and 2.8 [Å] (P
(interatomic distance of t). For this reason, the underlayer (Zn
The Pt layer formed on O) is likely to be densely arranged from the beginning of the lamination. That is, the coercive force is improved.

[0011]

Embodiments of the present invention will be described below. FIG. 1 schematically shows a part of a cross section of a magneto-optical disk, and FIG. 2 shows a configuration of a sputtering apparatus used for producing the magneto-optical disk. FIG. 3 shows a crystal structure of ZnO having the same crystal structure as the underlayer (ZnON) of the magneto-optical disk.

The magneto-optical disk shown in FIG.
First, Z is applied to the surface of the substrate 3 by the apparatus shown in FIG.
An underlayer 1 of nON (= a structure in which a part of “O” of ZnO in FIG. 3 is replaced with “N”) is formed, and then, Pt / Co alternately The laminated film (perpendicular magnetization film) 2 is formed. Note that the substrate 3 may be glass.

The illustrated apparatus includes a vacuum chamber 4, a substrate holder 7 rotatably disposed above the vacuum chamber 4, and a vacuum chamber 4.
And a shield plate for partitioning the inside, and performing sputtering by RF or DC power supplied by a power supply 8. The rotation speed of the substrate holder 7 is controllable, and the substrate 3 is held on the lower surface of the substrate holder 7 eccentrically from the axis of rotation.

The sputtering target 6 is held in each holding plate below each space divided by the shielding plate 5 in the vacuum chamber 4. As a target,
Zn or ZnO is used when the underlayer 1 is formed, and Pt and Co are used when the Pt / Co alternately laminated film is formed. The sputtering gas is supplied from the cylinder 9 via a valve, a pipe, and the like.

When ZnON is formed as the underlayer 1, (1) a method using Zn as a target and using Ar + O ₂ and N ₂ gas as a gas;
There is a method using ZnO as a get and using Ar or Ar + O ₂ and N ₂ gas as a gas. When ZnON is formed in this manner, ZnON having a structure in which a part of “O” in FIG. 3 is substituted with “N”, that is, a hexagonal wurtzite structure (ZnO structure) ([001] direction) When viewed from above, a ZnON underlayer 1 having a structure similar to that of the face-centered cubic structure (a structure densely arranged as viewed from the [111] direction) is formed. The interatomic distance of ZnON is smaller than 3.25 [Å], which is the interatomic distance of ZnO, and close to 2.8 [Å], which is the interatomic distance of Pt. This is because the atomic radius of N is 0.9 [Å], which is smaller than the atomic radius of O, 1.32 [Å].

For this reason, the Pt layers formed on the ZnON underlayer 1 are densely arranged from the beginning of the lamination, and the crystallinity and orientation are improved. Therefore, the coercive force of the Pt / Co alternately laminated film is increased, and higher density recording can be performed. In the above, a part of “O” of ZnO is replaced by “N”. However, when CH ₄ gas is used instead of N ₂ gas, Z
A part of “O” of nO is replaced with “C”. Also in this case, the same effect as described above is obtained by the same principle as described above.

[0017]

According to the present invention, when the underlayer (ZnO) is formed, a part of Zn or O is replaced by an element of N or C. Thereby, the crystal structure is the same as that of ZnO (= P
(similar to t), and an underlayer whose interatomic distance is substantially the same as the interatomic distance of Pt is obtained. For this reason, the Pt layer (= the component of the perpendicular magnetization film) formed on the base layer is also finely and densely arranged from the beginning of the lamination, and the crystallinity and orientation are improved. That is, a large coercive force can be obtained, and high-density recording can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a cross-sectional structure of a magneto-optical disk according to an embodiment.

FIG. 2 is an explanatory diagram of a sputtering apparatus for producing the magneto-optical disk.

FIG. 3 is an explanatory diagram showing a crystal structure of ZnO.

FIG. 4 is an explanatory diagram schematically showing a cross-sectional structure of a conventional magneto-optical disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Underlayer (ZnON) 2 Pt / Co alternate lamination film 3 Substrate

Continuation of the front page (72) Inventor Yasuyuki Komomoto 2-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-3-162739 (JP, A) JP-A-4- 351733 (JP, A) JP-A-2-206045 (JP, A) JP-A-4-337544 (JP, A) JP-A-3-132915 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 11/105 526 G11B 11/105 511

Claims (1)

(57) [Claims] 1. A magneto-optical recording medium comprising an alternately laminated film composed of a Pt layer and a transition metal layer formed so that the Pt layer is in contact with an underlayer on a substrate, wherein ZnO is used as the underlayer. Used and the ZnO
A magneto-optical recording medium comprising N or C and a film having orientation.