JP2904951B2 - Method for manufacturing magneto-optical storage element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magneto-optical memory element for recording, erasing and reproducing information with light such as a laser beam.

[0002]

2. Description of the Related Art A Pt / Co multilayer film in which a Pt layer and a Co layer are alternately and repeatedly laminated has not only a perpendicular magnetic anisotropy but also a rare-earth-transition metal against short-wavelength light. It has a larger car rotation angle than the alloy. Therefore, P
A magneto-optical storage element using a t / Co multilayer film has been attracting attention as a magneto-optical recording medium capable of high-density magneto-optical recording.

In order to stably hold recorded information, it is desired that the Pt / Co multilayer film has a high coercive force.

On page 55 of the Abstracts of the Japanese Society of Applied Magnetics, published in 1989, it can be seen that, when a Pt / Co multilayer film is formed by sputtering, if the pressure of Ar gas as a sputtering gas is increased, the It is reported that a Pt / Co multilayer film having a magnetic force can be obtained.

On page 56 of the summary, Pt / C
It has been reported that when a multilayer film is formed on a metal film having an fcc (face-centered cubic) lattice such as Pt or Pd by a sputtering method, a Pt / Co multilayer film having a high coercive force can be obtained.

[0006]

However, when a Pt / Co multilayer film is formed under a high Ar gas pressure, Pt / Co
The multilayer will contain many vacancies. When a Pt / Co multilayer film is formed on a metal film having an fcc lattice, the thicker the metal film, the larger the coercive force.
The crystal grain size of the / Co multilayer film also increases.

[0007] An increase in vacancies and an increase in crystal grain size in the Pt / Co multilayer film has a problem that it causes noise during information reproduction.

[0008]

According to a method of manufacturing a magneto-optical memory device of the present invention, an Al target is sputtered under a mixed gas of N ₂ gas and Ar gas to form an amorphous AlN film on a substrate. After the formation, a Pt target and a Co target are alternately sputtered under Ar gas to form a Pt / Co multilayer film in which a Pt layer and a Co layer are alternately stacked on the amorphous AlN film. A method of manufacturing an optical memory element, wherein the flow rate of the N ₂ gas is set so that a high coercive force Pt / Co multilayer film is obtained when the amorphous AlN film is formed.

[0009]

According to the above arrangement, an Al target is sputtered under a mixed gas of N ₂ gas and Ar gas to form an amorphous AlN film on the substrate, and then the Pt target and the Co target are separated. A method for manufacturing a magneto-optical memory element, comprising forming a Pt / Co multilayer film in which a Pt layer and a Co layer are alternately laminated on the amorphous AlN film by alternately sputtering under an Ar gas. Amorphous Al
When forming the N film, the flow rate of the N ₂ gas is set so as to obtain a Pt / Co multilayer film having a high coercive force.
A magneto-optical storage element having a high coercive force Pt / Co multilayer film can be manufactured without forming a Pt / Co multilayer film under gas pressure. Therefore, a high coercive force Pt / C with few holes
o A multilayer film is obtained. In addition, Pt is formed on the amorphous AlN film.
Since the / Co multilayer film is formed, the crystal grains of the Pt / Co multilayer film are unlikely to grow. Therefore, Pt /
A Co multilayer film is obtained. As described above, it is possible to manufacture a magneto-optical storage element with less noise during information reproduction.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

The magneto-optical storage element manufactured in this embodiment is
As shown in FIG. 3, a substrate 1 made of a resin such as glass or polycarbonate, an amorphous AlN film 2 formed on the substrate 1 (hereinafter abbreviated as an a-AlN film 2), and an a-
It is mainly composed of a Pt / Co multilayer film 7 formed on the AlN film 2. The Pt / Co multilayer film 7 is composed of the Pt layer 3 and C
o layer 4 is alternately and repeatedly laminated.
The Pt layer 3 is formed on the uppermost layer and the lowermost layer of the Pt / Co multilayer film 7.
Is arranged.

FIG. 4 shows a schematic configuration of a sputtering apparatus for forming an a-AlN film 2 on a substrate 1.

The sputtering apparatus comprises a vacuum chamber 5,
It mainly includes a substrate holder 6 that holds the substrate 1 and serves as an anode, a cathode 9 on which an Al target 8 is mounted, and an RF (high frequency) power supply 10 connected to the cathode 9.

Hereinafter, using this sputtering apparatus, a-
A procedure for forming the AlN film 2 on the substrate 1 will be described.

First, the cleaned substrate 1 is placed on a substrate holder 6.
And the Al target 8 is set on the cathode 9. Next, the inside of the vacuum chamber 5 is sufficiently evacuated. Thereafter, a predetermined flow rate of N ₂ gas and Ar gas is introduced into the vacuum chamber 5, and the RF power supply 10 is turned on. Thereby, plasma is generated between the substrate holder 6 and the cathode 9, and reactive sputtering is performed. That is, the accelerated Ar ⁺
The Al target 8 on the cathode 9 is hit by the ions, and Al atoms jump out. The Al atoms react with the N ₂ gas to form an a-AlN film 2 on the substrate 1.

Next, FIG. 5 shows a schematic configuration of a binary sputtering apparatus for forming the Pt / Co multilayer film 7 (FIG. 3).

The binary sputtering apparatus comprises a vacuum chamber 1
1, a substrate holder 12 that holds an intermediate substrate 13 in an intermediate manufacturing stage in which an a-AlN film 2 is formed on the substrate 1 and serves as an anode, and cathodes 17a, on which a Pt target 16a and a Co target 16b are mounted, respectively. 1
7b, RF power supplies 18a and 18b connected to the cathodes 17a and 17b, respectively, a Pt target 16a and C
o It mainly comprises shutters 14a and 14b provided on the substrate holder 12 side of the target 16b.

One ends of the shutters 14a and 14b are attached to rotating shafts 15a and 15b, respectively. By rotating the rotation shafts 15a and 15b, the shutter 1
4a and 14b open and close, respectively. Shutter 14a
14b is closed, that is, the shutter 14a
14b is a Pt target 16a and a Co target 16
When the Pt target and the Co target 16b are located in front of the Pt target 16a and the Co target 16b, the shutters 14a and 14b prevent the Pt and Co atoms from reaching the intermediate substrate 13 on the substrate holder 12, respectively. become unable.

Hereinafter, using this binary sputtering apparatus,
A procedure for forming the Pt / Co multilayer film 7 on the a-AlN film 2 of the intermediate substrate 13 will be described.

First, the intermediate substrate 13 is set on the substrate holder 12 so that the substrate 1 is on the substrate holder 12 side.
The t target 16a and the Co target 16b are set on the cathodes 17a and 17b, respectively. Next, the inside of the vacuum chamber 11 is sufficiently evacuated. Thereafter, a predetermined flow rate of Ar gas is introduced into the vacuum chamber
a and 14b both closed, the RF power supply 18a.
18b are put together. As a result, plasma is generated and the Pt target 1 is accelerated by the accelerated Ar ⁺ ions.
6a and the Co target 16b are hit, and Pt atoms and Co
Atoms come out of the Pt target 16a and the Co target 16b, respectively. In this state, shutter 1
When 4a and 14b are alternately opened and closed, Pt atoms and Co atoms alternately reach the intermediate substrate 13 on the substrate holder 12, and
A Pt / Co multilayer film 7 in which a Pt layer 3 (FIG. 3) and a Co layer 4 are alternately and repeatedly laminated is formed.

A magneto-optical storage element was manufactured using the above-described sputtering apparatus and binary sputtering apparatus, and the obtained Pt /
The relationship between the coercive force of the Co multilayer film 7 and the conditions for forming the a-AlN film 2 was examined.

Glass was used as the material of the substrate 1 of the magneto-optical storage element. The thickness of the a-AlN film 2 is 50
Set to 0 °. The thicknesses of the Pt layer 3 and the Co layer 4 in the Pt / Co multilayer film 7 were set to 9.9 ° and 3.0 °, respectively. Pt layers 3 and Co layers 4 were alternately laminated in a total of 12 layers, and one more Pt layer 3 was laminated as the uppermost layer.

At the time of forming the a-AlN film 2, the flow rate of N ₂ gas was set to any value within the range of ₂ to 15 SCCM. A
The r gas flow rate was set at 4 SCCM. a-AlN film 2
Was 40 ° / min.

On the other hand, when forming the Pt / Co multilayer film 7, Ar
The gas flow rate was set at 6 SCCM. The deposition rate of the Pt layer 3 was 0.8 ° / sec, and the deposition rate of the Co layer 4 was 0.1 ° / sec.

The coercive force of the observed Pt / Co multilayer film 7, as shown in the graph of FIG. 1, highly dependent on the N ₂ gas flow rate during the deposition of a-AlN film 2, and, N ₂ gas It was found that when the flow rate was set to an appropriate value (about 8 SCCM in this embodiment), the coercive force became maximum.

[0026] Here, the vertical axis in the figure, a-AlN film 2 on to the coercive force obtained in the case of forming a Pt / Co multilayer film 7 and H _c, directly Pt / Co on a substrate 1 of glass Multilayer film 7
H when the coercive force obtained in the case of forming a was H _c0
and the ratio of _c to H _c0 , that is, H _c / H _c0 ,
The horizontal axis indicates the N ₂ gas flow rate. The unit of the gas flow rate is SCCM (standard cm ³ / min). Also, H
_c0 was 98 Oe in this example.

Next, the Pt / C of the above magneto-optical storage element
o The structure of the multilayer film 7 was examined by X-ray diffraction.

As a result, it was found that the Pt / Co multilayer film 7 was a polycrystal and was formed of an fcc (face-centered cubic) lattice. It was also found that the (111) plane of the fcc lattice was oriented parallel to the substrate 1.

As shown in the graph of FIG. 2, the intensity of the diffracted light by the (111) plane of the Pt / Co multilayer film 7 is similar to the coercive force described above when the a-AlN film 2 is formed. highly dependent on the flow rate of N ₂ gas, and setting the N ₂ gas flow rate to a suitable value, that the intensity becomes maximum, i.e.,
The crystallinity was found to be the best.

Here, the vertical axis in the figure is the Pt / Co multilayer film 7.
The intensity of the diffracted light by the (111) plane is shown, and the horizontal axis shows the N ₂ gas flow rate. The unit of strength is CP
S (count / sec). Incidentally, the strength when the Pt / Co multilayer film 7 was formed directly on the glass substrate 1 was 1000 CPS.

Comparing the above results (FIGS. 1 and 2), the N ₂ gas flow rate that maximizes the intensity of the diffracted light by the (111) plane substantially matches the N ₂ gas flow rate that maximizes the coercive force. It is considered that when the crystallinity of the Pt / Co multilayer film 7 is improved, the coercive force is increased.

As described above, by setting an appropriate N ₂ gas flow rate at the time of forming the a-AlN film 2, Pt / Co
The coercive force of the multilayer film 7 can be increased. Therefore, in order to increase the coercive force of the Pt / Co multilayer film 7,
When forming the Pt / Co multilayer film 7, it is not necessary to increase the Ar gas pressure. As a result, Pt is produced at a low Ar gas pressure.
/ Co multilayer film 7 can be formed, so that Pt /
The Co multilayer film 7 can be manufactured. Further, since the Pt / Co multilayer film 7 is formed on the a-AlN film 2, the crystal grain size does not increase unlike the case where the Pt / Co multilayer film 7 is formed on a metal having an fcc lattice. As described above, according to the method of manufacturing the magneto-optical storage element of the present embodiment, the Pt / Co multilayer film 7 having a small number of holes and a small crystal grain size can be obtained. Devices can be manufactured.

[0033]

As described above, the method of manufacturing a magneto-optical memory element according to the present invention uses an N ₂ gas such that a Pt / Co multilayer film having a high coercive force can be obtained when an amorphous AlN film is formed. Since the flow rate is set, a magneto-optical storage element having a high coercive force Pt / Co multilayer film can be manufactured without forming a Pt / Co multilayer film under a high Ar gas pressure. Therefore, a high coercive force Pt / Co multilayer film having few holes can be obtained. Further, since the Pt / Co multilayer film is formed on the amorphous AlN film, the crystal grains of the Pt / Co multilayer film are unlikely to grow. Therefore, a Pt / Co multilayer film having a small crystal grain size can be obtained.
As described above, there is an effect that a magneto-optical storage element with less noise can be manufactured during information reproduction.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a coercive force of a Pt / Co multilayer film and an N ₂ gas flow rate at the time of forming an a-AlN film.

FIG. 2 is a graph showing the relationship between the intensity of diffracted light from the (111) plane of a Pt / Co multilayer film and the flow rate of N ₂ gas when an a-AlN film is formed.

FIG. 3 is a schematic configuration diagram of a magneto-optical storage element.

FIG. 4 is a schematic view of a sputtering apparatus for producing an a-AlN film.

FIG. 5 is a schematic view of a binary sputtering apparatus for producing a Pt / Co multilayer film.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 amorphous AlN film (a-AlN film) 3 Pt layer 4 Co layer 7 Pt / Co multilayer film 13 intermediate substrate

Continuation of the front page (72) Inventor Kenji Ota 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-63-171448 (JP, A) JP-A-1-251356 (JP) , A) JP-A-3-228239 (JP, A) JP-A-4-258829 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 11/10 506 G11B 11/10 521 G11B 11/10 541

Claims (1)

(57) [Claims] An amorphous AlN film is formed on a substrate by sputtering an Al target under a mixed gas of N ₂ gas and Ar gas, and then a Pt target and a Co target are placed under an Ar gas. A method for manufacturing a magneto-optical memory element, wherein a Pt / Co multilayer film in which a Pt layer and a Co layer are alternately laminated on the amorphous AlN film by alternately sputtering is provided. At the time of film formation, the above-mentioned N ₂ is used so that a high coercive force Pt / Co multilayer film is obtained.
A method for manufacturing a magneto-optical storage element, wherein a flow rate of a gas is set.