JPS63104313A - Manufacture of gamma iron oxide thin film - Google Patents

Abstract

PURPOSE:To easily manufacture a vertical magnetic film of gamma-Fe2O3 by chemically depositing organic iron compound vapor as a material on a substrate coated with a spinel ferrite film oriented in a plane (111). CONSTITUTION:Si is used as a substrate 8, a mixture powder of iron (III) acetylacetonate and cobalt (III) acetylacetonate is used as the organic metal compound 4 of a bubbler 2, and the bubbler 2 is heated to introduce the vapor of the compound 4 into a reaction tube 1 together with oxygen gas 6. A current flows to a high frequency coil 9 to generate a plasma, and a spinel oxide film of a cobalt and an iron oriented in (111) plane is formed on the substrate 8. Then, only iron (III) acetylacetonate is used as the compound 4, and similarly deposited by the plasma to form a continuous film of gamma-Fe2O3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a (111)-oriented γ medium that can be developed into a perpendicular magnetic recording medium, which is attracting attention as a high-density magnetic recording system, and has excellent environmental resistance. The present invention relates to a method of manufacturing a gamma iron oxide thin film, which is a Fe203 perpendicular magnetization film.

2. Description of the Related Art Conventionally, vacuum evaporation and sputtering have been mainly used as methods for producing magnetic continuous thin films. In terms of materials, alloy thin films such as Co--Cr alloys have been studied as perpendicularly magnetized films. However, there are many problems in terms of environmental resistance, such as corrosion due to humidity in the air. In comparison, since T-FezO3 (gamma iron oxide) is an oxide, it has extremely excellent environmental resistance, and various studies have been made on the synthesis of magnetic thin films of γ-FezO+.

Conventionally, γ-Fe, 04 thin films have been produced by sputtering. First, γ-Fe was sputtered using a reactive sputtering method using a metal iron target while flowing oxygen gas.
20. It has been common practice to prepare a thin film, reduce it in a hydrogen stream to transform it into spinel-type iron oxide FezO4, and slightly oxidize this to produce a continuous r-FezO3 film. [For example, Ju. Kay, Howard, Journal of Vacuum Science Technology
A, p. 4-95.1 1986 (J., Holy
ard, J., Vac., Sci., Technol.
A, 4. P11986) ).

Problems to be Solved by the Invention The synthesis of the T -FezOi continuous magnetization film by the above-mentioned sputtering method is based on the process of first producing r -FezO by using metal iron as a target and performing reactive sputtering in a chamber into which a small amount of oxygen gas is introduced. ,,Since a continuous film is made, reduced to form a Fe,04 film, and then slowly oxidized to synthesize a γ-FezO=continuous film, cracks tend to form on the film surface and the film quality is not good. Since it is a crystalline film, it has many drawbacks, such as the difficulty in forming a film that is preferentially oriented in a certain crystal plane. As a method to improve this drawback, γ-Fe, 0.0. Although there is a method for producing a film, this method tends to produce a film with in-plane magnetization oriented in the (100) plane, and it is difficult to produce a film with perpendicular magnetization.

The present invention can be easily oxidized at a relatively low temperature <1
(111)-oriented γ-Fe2 with a developed plane in the 11> direction
0. It is an object of the present invention to provide a method for manufacturing a perpendicularly magnetized film.

Means for Solving the Problems The present invention heats and vaporizes an organic iron compound, and uses a mixed gas containing oxygen gas to form a spinel-type ferrite, CoxFe3-xo4 (0,1<C
This is a method of manufacturing a perpendicularly magnetized magnetic thin film of γ-FezO, by performing chemical vapor deposition on a substrate on which a thin film with (111) plane orientation of o≦3) is disposed on the surface, so -i Spinel type ferrite with solid solution of cobalt, CoxFe
3-xOt (0,1≦CO≦3) can be produced relatively easily by the CVD method, and it is easy to form a film with the (111) plane oriented.
1) The reason why a plane-oriented spinel-type cobalt ferrite film is easy to produce, and this spinel-type ferrite, C
When a γ-FezO:+ film is formed on an oxFet-xOa film as a base, γ-p620:I and the underlying CoxFe3-
Both xOa have the same spinel crystal structure,
Furthermore, since the interatomic distances between oxygen and oxygen in the same crystal structure are very similar, the γ-Fez03 film is similar to the underlying CoxFe.
γ-Fe, 0.0. The easy axis of magnetization is 〈111
r-Fez with (111) plane completely oriented in the > direction
This makes it possible to manufacture an Oi perpendicular magnetization film.

Function The present invention is made by plasma and CVD method (ill) in advance.
This is a method of manufacturing a perpendicularly magnetized γ-FezO film with a (111) plane orientation on a substrate coated with a spinel-type ferrite film with an oriented plane by plasma CVD using the vapor of an organic iron compound as a raw material gas. Therefore, it is possible to easily synthesize a continuous film with extremely good crystallinity at a relatively low pressure that does not require a high vacuum, and at a relatively low temperature using easily available raw material gases.

In other words, an inexpensive perpendicular magnetization film can be manufactured using a simple manufacturing process.

EXAMPLE Below, a method for manufacturing a gamma iron oxide thin film according to an example of the present invention will be described with reference to the drawings.

Example 1 This example was carried out using a manufacturing apparatus as shown in FIG. This manufacturing apparatus roughly consists of a quartz reaction tube 1, a raw material vaporization bubbler 2 that can be heated, and an exhaust pump 3. Put the organometallic compound 4 into this bubbler 2,
When heated, a vapor of the organometallic compound is emitted, which is introduced into a quartz reaction tube 1 using nitrogen gas 5 as a carrier gas. On the other hand, oxygen gas 6 is also introduced into the reaction tube 1 at the same time.

Inside the reaction tube, a substrate heating heater 7 is arranged in the center, and a substrate 8 is held on top of the substrate heater 7. Furthermore, a high frequency coil 9 for plasma generation is installed outside the reaction tube, and uses a high frequency power source to generate a mixed gas of organometallic compound vapor and oxygen gas sent by the carrier gas flowing inside the reaction tube. It can excite plasma. Note that the inside of the reaction tube of the manufacturing apparatus is always forcibly evacuated using the exhaust pump 3 to maintain a constant degree of vacuum.

A silicon substrate is used as the substrate 8, and iron (II[) acetylacetonate and cobalt (I) are used as the organic metal compounds.
II) Using 16g of powder mixed with acetylacetonate at a molar ratio of 3:1, place it in bubbler 2 and heat it at 170°C.
Heat to 3ml of nitrogen gas! quartz reaction tube 1 while flowing oxygen gas at a flow rate of 2 mff/min.
While adjusting the bubble 11 so that the vacuum level inside the chamber is 2 Xl0-'Torr, the high frequency output is set to 30 W, plasma is excited for 5 minutes, the substrate is heated and held at 300°C, and the CVD film is deposited on the substrate. Formed. From X-ray diffraction and chemical analysis of this film, Coo, 5Fe with perfect orientation in the (111) plane was found.
It is a spinel-type oxide film with a composition of z and soa, and it was found from measurement with a vibrating magnetometer (VSM) that it is a film with an in-plane spin axis.

The film thickness was 0.15 μm.

Subsequently, iron (III
) Refill 16g of acetylacetonate only, 17
The silicon substrate on which the (111) plane-oriented spinel oxide film was formed was used as the substrate, and the substrate temperature was heated to 100°C and 150°C under the same conditions as above.
, 200° C., 250° C., 300° C., and 350° C., high frequency output was set to 30 W, and plasma was excited for 30 minutes to form a CVD film. As a result of X-ray diffraction and chemical analysis, the obtained CVD film showed that spinel-type iron oxide γ-Fe20. A continuous film was obtained, and as a result of VSM measurement, the film had the properties shown in Table 1.

For comparison in Table 1, using the same manufacturing equipment, (11
1) A bubbler (
2) was filled with only iron(II[) acetylacetonate, the other conditions were the same as in this example, and the substrate temperature was set to 100.1.
50. Plasma CVD films were prepared at temperatures of 200, 250, 300, and 350°C. The obtained film was heated to 100°C.
The film on the substrate was X-ray amorphous, but the rest was a γ-Fez03 film. However, all of these γ-Fez03 films were (100) plane oriented films with magnetic spin in the plane, and a perpendicularly magnetized film like the one in this example could not be obtained.

Example 2 Using the same manufacturing equipment as in Example 1 and in exactly the same manner as in Example 1, Coo, 5Fez, and (111)-plane perfectly oriented were prepared.
A silicon substrate coated with a spinel type oxide film having a composition of s04 was prepared.

As organometallic compound 4 of bubbler 2, ferrocene 10
Heat bubbler 2 to 85°C using 3ml of nitrogen gas! 3mff/oxygen gas at a flow rate of 7 minutes
2xlO− inside the quartz reaction tube 1 while flowing at a flow rate of
'Adjust the bubble 11 to a vacuum level of Torr, and excite the plasma for 30 minutes with a high frequency output of 30W.
A VD film was produced. At this time, the temperature of the substrate was 100, 15
The temperature was set at 0, 200, 250, 300, and 350°C. The obtained membrane was analyzed in the same manner as in Example 1. The results are shown in Table 2.

Table 2 For comparison, a silicon substrate without a spinel-type oxide film formed as a base was used as the substrate, ferrocene was placed in bubbler 2, and a plasma and CVD film was produced in the same manner as above. .

As in this example, an amorphous film was formed on the substrate at 100°C. The substrate at 150°C contains unoriented r-Fe.
A 203 film was obtained, and a film with (100) orientation in which the magnetic spin was in the plane was produced on all substrates heated to temperatures above 200°C, and a perpendicularly magnetized film such as in this example was not obtained. Ta.

That is, as shown in this example, (
111) According to the manufacturing method of the present invention, which uses a substrate thinly coated with a plane-oriented spinel-type oxide film and performs plasma CVD using an organic iron compound, γ-Fe,
It can be seen that a perpendicularly magnetized film of O.

Effects of the Invention As described above, according to the production method of the present invention, γ-Fe20. ．． This makes it possible to manufacture a perpendicularly magnetized film. This perpendicular magnetization film can be expected to be developed into a media material for perpendicular magnetic recording.

[Brief explanation of the drawing]

The figure is a configuration diagram of a manufacturing apparatus used in an embodiment of the present invention. 1...Quartz reaction tube, 2...Bubbler for raw material vaporization, 3...Exhaust pump, 4...
・Organometallic compound, 5... Nitrogen gas, 6...
...Oxygen gas, -...Substrate heating heater, 8
... Board, 9 ... High frequency coil, 10
...Vacuum gauge, 11...Vacuum adjustment valve.

Claims (5)

[Claims] (1) An organic iron compound is heated and vaporized, and a mixed gas mixed with oxygen gas is excited by plasma to generate a spinel type ferrite, Co_xFe_3_-_xO_4 (0.
On a substrate on which a thin film oriented in the (111) plane (1≦X≦3) is disposed, a (111) film is deposited by chemical vapor deposition (CVD) in a crystallographically epitaxial relationship with this oriented film.
) A method for manufacturing a gamma iron oxide thin film, which is a plane-oriented perpendicular magnetization film. (2) A thin film of Co_xFe_3_-_xO_4 (111)-oriented spinel-type ferrite placed on the substrate surface heats and vaporizes an organic iron compound and an organic cobalt compound at the same time, and further oxygen gas is added to the resulting mixed gas. The method for producing a gamma iron oxide thin film according to claim (1), wherein the film is produced by a method of chemical vapor deposition by plasma excitation of a mixed gas. (3) The method for producing a gamma iron oxide thin film according to claim (2), wherein the organic cobalt compound is a β-diketone cobalt complex such as cobalt acetylacetonate. (4) The method for producing a gamma iron oxide thin film according to claim (1), wherein the organic iron compound is a β-diketone iron complex such as iron (III) acetylacetonate. (5) The method for producing a gamma iron oxide thin film according to claim (1), wherein the organic iron compound is ferrocene.