JPH0227524A - Production of perpendicular magnetic recording film - Google Patents

Abstract

PURPOSE:To obtain the perpendicular magnetic recording film having large saturation magnetization by specifying the base vacuum degree of a vapor deposition device and a substrate temp. and alternately laminating cobalt and aluminum by vapor deposition, thereby forming the recording film. CONSTITUTION:The base vacuum degree of the vapor deposition device is set at 10<-7>Torr or higher vacuum and thereafter, the cobalt layers 9 and the aluminum layers 10 are alternately laminated by vapor deposition on the substrate at >=-50 deg.C and <=+300 deg.C substrate temp. Further, the compsn. modulated cobalt/aluminum films are heat-treated at >=150 deg.C and <=450 deg.C. The perpendicularly magnetized films having the larger saturation magnetization than the saturation magnetization of the conventional cobalt/chromium alloy film is obtd. and the larger signals at the time of reading out than the conventional cobalt/chromium alloy film are taken. In addition, the magnetic recording density can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a perpendicular magnetic recording film having a composition modulation structure.

(Prior Art) Perpendicular magnetic recording is attracting attention and being actively researched as a recording method that dramatically increases magnetic recording density compared to conventional longitudinal recording methods. In particular, cobalt-chromium alloy films have excellent properties as perpendicular magnetic recording films, but perpendicularly magnetized films can only be obtained when the cobalt concentration is around 20%, and as a result, the saturation magnetization value is small. , S/ when reading
When considering N, etc., there is a limit to the magnetic recording density. For this reason, a perpendicular magnetic recording film with a large saturation magnetization value is required. As one method, research is being conducted on a perpendicular magnetic recording film, which is a film with a composition modulation structure formed by alternately laminating two metals (for example, Journal of Applied Physics (J, Appl., Phys.)). (See Vol. 61, No. 8, pp. 4317-4319).

(Problems to be Solved by the Invention) Cobalt-chromium alloy perpendicular magnetic recording films do not necessarily have a large saturation magnetization value, which limits the magnetic recording density.

An object of the present invention is to provide a method for manufacturing a perpendicular magnetic recording film having a cobalt-aluminum composition modulation structure with large saturation magnetization.

(Means for Solving the Problems) The present invention provides (1) a base vacuum degree of the vapor deposition apparatus of 1O-7t;
A method for manufacturing a perpendicular magnetic recording film, characterized in that it is formed by alternately laminating cobalt and aluminum at a substrate temperature of 150° C. or more and +300° C. or less after applying a vacuum of ) A method for producing a perpendicular magnetic recording film, comprising the step of heat-treating a cobalt-aluminum composition modulation film formed by alternately laminating cobalt and aluminum at a temperature of 150° C. or more and 450° C. or less.

(Example) The present invention will be described below with reference to Examples. FIG. 1 is a schematic cross-sectional view of the perpendicular magnetic recording film of the present invention, which has a so-called composition modulation structure in which cobalt layers 9 and aluminum layers 10 are alternately laminated on a substrate. In carrying out the present invention, film formation was performed using the alternate vapor deposition apparatus shown in FIG.

In the vacuum chamber of the evaporation apparatus shown in Fig. 2, there are two electron beam evaporation sources 1 and 1' filled with cobalt and aluminum.
, a substrate 2, a substrate heating and cooling stage 3, a crystal oscillator film thickness gage 4, 4' for monitoring the evaporation rate of the two electron beam evaporation sources, and for opening and closing the molecular beam fluxes emitted from the two evaporation sources. shutters 5 and 5', and a vacuum gauge 6, and is evacuated by a cryopump 8 through a gate valve 7. Furthermore, in order to obtain a degree of vacuum higher than 10 torr, a heater is attached to the outer periphery of the chamber to enable baking. 10=
The original film formation in an ultra-high vacuum higher than torr was performed after baking the chamber at 150°C for 10 hours.
The original film formation at a vacuum level lower than 10-8 torr was performed without chamber baking. The composition modulation film is produced by adjusting the power of the electron beam evaporation source so that the evaporation rate from the two electron beam evaporation sources is constant, and then by alternately opening and closing two shutters to deposit cobalt and aluminum into the desired film thickness. It is formed by laminating alternately. As a comparative example, using this evaporation apparatus, chromium was put into the electron beam evaporation source instead of aluminum, and C was co-deposited.
An alloy film of 0aoCr2o was produced, and a perpendicular magnetization film with a saturation magnetization value of 410 emu/cm3 was obtained. The magnetic measurements were performed using a vibrating sample magnetometer (VSM) at room temperature.
This was done by

First, a silicon wafer is used as a deposition substrate, and the substrate temperature is set to 100°C to 400°C, 1% deposition rate. Under the conditions of OA/sec, 15 people for cobalt, 10 people for aluminum, 100 repetitions, that is, a total film thickness of 250OA
Aluminum composition-modulated films were fabricated by changing the base vacuum of the chamber, and the saturation magnetization and perpendicular magnetization of each film were examined using VSM. The determination of whether or not the film is perpendicularly magnetized is determined by the M-H loop when the magnetic field is smaller than 5 kOe. If it is larger than that when the voltage is applied, it is assumed that the film is perpendicularly magnetized. Third
In FIG. 7, the base vacuum degree of the chamber is 2×10 −6 torr.

IX1 Kano 7torr, 3X10-8torr, 5
It shows the relationship between substrate temperature and saturation magnetization in the case of X10-9torr7×1"torr. In these figures, the ○ mark means a perpendicular magnetization film, and the x mark means an in-plane magnetization film.From these results, It can be seen that a perpendicularly magnetized film having a larger saturation magnetization than the co-deposited C05oCr2o film of the comparative example can be obtained when the base vacuum degree is higher than 1O-7 torr and the substrate temperature is 150° C. or more and +3000° C. or less. Here, the cobalt layer has 5 to 30 people, and the aluminum layer has 2.
Samples were prepared in a range of 5A to 20 people.

Next, under a chamber vacuum of 2X10-9 torr, 30 pieces of cobalt and 2 pieces of aluminum were placed on the sapphire substrate.
The cobalt/aluminum composition modulation film was made by 5 people repeatedly 50 times, that is, with a total film thickness of 2750, at a substrate temperature of 80°C.
Vapor deposition rate 1. Produced under the conditions of OA/sec and 100℃
Heat treatment for 30 minutes at a temperature of 500℃ from 5X10-6
This was carried out in a vacuum of Torr, and the saturation magnetization and whether or not each film had perpendicular magnetization were investigated using VSM. FIG. 8 shows the relationship between heat treatment temperature and saturation magnetization. In the figure, the ○ mark means a perpendicularly magnetized film, and the X mark means an in-plane magnetized film. These results show that a perpendicularly magnetized film having a larger saturation magnetization than a cobalt-chromium alloy film can be obtained by performing the heat treatment at a temperature of 150° C. or higher and 450° C. or lower.

Ru.

Furthermore, under a chamber vacuum of 2X10-9 torr, a cobalt-aluminum composition-modulated film was deposited on a sapphire substrate by 5 cobalt and 20 Aralminilam 100 times, or a total film thickness of 2500, at room temperature and at a evaporation rate of 0. Produced under the conditions of 5A/see, and heated from 100°C to 5
Heat treatment for 40 minutes at a temperature of 00℃ to 5X10=torr
This was carried out in a vacuum, and the saturation magnetization and perpendicular anisotropy were investigated using VSM. FIG. 9 shows the relationship between heat treatment temperature and saturation magnetization. The O and X marks are the same as in FIG. These results show that a perpendicularly magnetized film having a larger saturation magnetization than a cobalt-chromium alloy film can be obtained by heat treatment at 150° C. or more and 450° C. or less. In FIG. 8 and FIG. 9, the heat treatment time was 30 minutes and 40 minutes, but similar results were obtained when the heat treatment time was 1 hour. Moreover, although the case where the heat treatment atmosphere was a vacuum was described, similar results were obtained when nitrogen or argon gas was used.

As in the embodiment shown in Figure 8, a film that was not perpendicularly magnetized immediately after vapor deposition becomes a perpendicularly magnetized film by heat treatment at 150°C or higher and 450°C or lower, and as shown in the embodiment shown in Figure 9. Although it is a perpendicularly magnetized film immediately after evaporation, the saturation magnetization is similar to that of the Co8oCr2o alloy of the comparative example.
Heat treatment at temperatures above 0°C and below 450°C may increase saturation magnetization while maintaining perpendicular magnetization;
The properties of perpendicularly magnetized films that are better than those of o8oCr2o are composition modulated films with a cobalt thickness of 5 to 40 and an aluminum thickness of 2.5 to 30.

(Effects of the Invention) As explained above in the embodiments, according to the present invention, a perpendicularly magnetized film having a larger saturation magnetization than a conventional cobalt-chromium alloy film can be obtained, which makes it easier to read than a conventional cobalt-chromium alloy film. Not only can a large time signal be obtained, but also the magnetic recording density can be increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of the perpendicular magnetic recording film of the present invention. FIG. 2 is a schematic diagram of a vapor deposition apparatus used in an example of the present invention. FIGS. 3 to 7 are diagrams showing the relationship between the saturation magnetization and substrate temperature of cobalt-aluminum composition-modulated films produced by changing the vacuum degree of the chamber. Figures 8 and 9 show cobalt
FIG. 3 is a diagram showing the relationship between saturation magnetization and heat treatment temperature of an aluminum composition modulated film. In the figure, 1°1' is the evaporation source, 2 is the substrate, and 5
, 5' is a shutter, 9 is a cobalt layer, and 10 is an aluminum layer.

Claims (2)

[Claims] (1) The base vacuum level of the evaporation equipment is 10^-^7 torr.
, or after applying a higher vacuum than this, the substrate temperature is -50
A method for manufacturing a perpendicular magnetic recording film, characterized in that cobalt and aluminum are alternately deposited and laminated at a temperature of not less than 0.degree. C. and not more than +300.degree. (2) Cobalt/aluminum composition modulation film formed by alternately laminating cobalt and aluminum at temperatures above 450°C
1. A method for manufacturing a perpendicular magnetic recording film, comprising a step of heat treatment at a temperature of 50° C. or lower.