JPH05274668A - Production of magnetic thin film - Google Patents

Abstract

PURPOSE:To enable fine patterning of an iron oxide film formed on a substrate by preventing the formation of a layer which blocks etching by a reaction of the iron oxide film with the substrate when the iron oxide film is formed by chemical atomization deposition or sputtering and patterend by etching. CONSTITUTION:A ZnO film 2 and an alpha-Fe2O3 film are successively formed on a heated substrate 1 by spraying, an iron oxide (alpha-Fe2O3) film pattern 3 having a prescribed mask shape is formed by etching and a gamma-Fe2O3 film is obtd. by subjecting the pattern 3 to reduction and oxidation modification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a magnetic thin film capable of fine patterning.

[0002]

2. Description of the Related Art In the conventional manufacturing method of a magnetic thin film, iron oxide (α-Fe ₂ O ₃ ) is first formed on a substrate by a spray method or a chemical atomization deposition method (CMD). Then, it is subjected to hydrogen reduction treatment to obtain Fe ₃ O _4, and further modified to γ-Fe ₂ O ₃ by oxidation treatment to obtain a desired magnetic thin film.

A film forming apparatus using the above chemical atomization deposition method is
It consists of an air supply device, an atomizer, and a film formation chamber. The atomization device consists of a container connected to each of the air supply device and the film formation chamber by a conduit and an ultrasonic oscillator, and a magnetic thin film is formed in the container. The raw material solution is stored.

The manufacturing procedure is as follows. First, pure water is mixed with a predetermined amount of FeC.
l ₃ · 6H ₂ O and ethanol - adding and Le to prepare a magnetic thin film forming raw material solution, a substrate placed in the deposition chamber hot plate - heated with bets after maintaining the surface at a predetermined temperature, the container The raw material solution stored therein is atomized by an ultrasonic oscillating device, and mist-like raw material solution particles are supplied to the film forming chamber by blowing air from an air supply device to form a film on the surface of the substrate.

[0005]

The patterning of a magnetic thin film is carried out by iron atomization (α-F) formed by a chemical atomization deposition method.
Since e ₂ O ₃ ) is soluble in hydrochloric acid, it is performed at the stage when a thin film of iron oxide is formed. The thin film is firmly bonded to the substrate and a reaction layer between the substrate and iron oxide is formed at the boundary with the substrate. Since it is formed, patterning by etching is not easy. Since this reaction layer does not usually dissolve only by dipping in hydrochloric acid, the steps of applying zinc powder and then dipping in hydrochloric acid are repeated 10 times or more, and if necessary, hydrofluoric acid treatment is applied to complete etching. ..

However, during the etching process, the photoresist forming the fine pattern or the printing resist forming the rough pattern is corroded, so that after the resist is peeled off, defects such as thinning of the pattern and disconnection may occur. There was a problem that appeared.

Therefore, an object of the present invention is to form an iron oxide film on a substrate by a chemical atomization deposition method or a spray method,
When this is patterned by etching, it is possible to perform fine patterning by etching so that the reaction layer of the substrate and the iron oxide film, which is a factor that inhibits etching, is not formed during the formation of the iron oxide film. Another object of the present invention is to provide a method for producing a magnetic thin film.

[0008]

Means for Solving the Problems As a result of research to achieve the above object, the present inventor found that a thin film was formed on a substrate according to the film forming procedure described below, and then the thin film was further subjected to reduction and oxidation treatments. The inventors have found that the above-mentioned problems can be solved, and a magnetic thin film can be obtained with high precision and fine patterning, and have reached the present invention.

That is, according to the present invention, (a) an aqueous solution or ethanol solution of zinc acetate is applied from above the heated substrate by a chemical atomization deposition method or a spray method to form Z on the substrate.
The first step of forming an nO film, (b) applying the raw material liquid for magnetic thin film in which an iron compound is dissolved in a solvent is applied from above the heated substrate by a chemical atomization deposition method or a spray method
a second step of forming an α-Fe ₂ O ₃ film on the nO film,
(C) A photoresist is evenly applied to the formed α-Fe ₂ O ₃ film, and ultraviolet rays are irradiated according to a predetermined mask to dissolve the unirradiated uncured resist to dissolve α-Fe ₂ O ₃
After exposing the film, the α-
Fe ₂ O ₃ film is removed corresponding to a predetermined mask pattern alpha-Fe ₂ O ₃ film patterns - a third step of forming a down,
(D) The patterned α-Fe ₂ O ₃ film is subjected to hydrogen reduction treatment to form a Fe ₃ O ₄ film, which is further oxidized and modified to give γ.
Provided is a method for producing a magnetic thin film, which comprises a fourth step of forming a —Fe ₂ O ₃ film. The thickness of the zinc oxide film formed is preferably 50 to 1000 nm. If the thickness is less than 50 nm, a reaction layer is rather generated, which is not desirable, and if the thickness is more than 1000 nm, it is difficult to manufacture, that is, mass production efficiency is deteriorated. Considering the effect of the present invention and the mass production efficiency, a film thickness of 100 to 200 nm is particularly optimal. Further, in the examples of the present specification, the spray method was used, but according to the known chemical atomization deposition method,
Mass production becomes easier.

[0010]

[Function] Zinc oxide can control the crystal orientation depending on the film forming conditions, and can control the epitaxy of the iron oxide film formed on the zinc oxide as a base. That is, α-Fe ₂ O _{3 is formed} on the (100) orientation of zinc oxide.
(0001) orientation easily grows, and α-Fe ₂ O
₃ (0001) crystal axis coincides with the direction of the (111) crystal axes of Fe ₃ O ₄ produced by the hydrogen reduction treatment (magnetite). Therefore, the initial orientation of zinc oxide affects the orientation of the finally produced magnetite.

Further, since the zinc oxide film can be easily etched only with hydrochloric acid, when the iron oxide film formed thereon is patterned by etching, the recesses of the pattern are wiped off together with the zinc oxide film. Etching is easy and no reaction layer remains. This will be described in more detail with reference to the following examples.

[0012]

[Embodiment 1] FIG. 1 is a schematic sectional view showing an iron oxide magnetic material pattern formed on a glass substrate in an embodiment of the present invention. The procedure in the manufacturing method of the present invention will be described below with reference to this figure. (1) A glass substrate was scribed in a 70 mm square and washed with a solvent and pure water. (2) The substrate 1 was placed on a hot plate heated to 400 ° C., and an ethanol solution of 0.05 mol% zinc acetate was sprayed from above the substrate by a chemical atomization deposition method to obtain a film thickness. A ZnO film 2 having a thickness of 100 nm was formed. (3) 40 g of FeCl ₃ .6H ₂ O in 150 ml of pure water
After dissolving, 15 ml of ethanol was further added to prepare a raw material liquid for producing a magnetic thin film. Then, the substrate was placed on a hot plate heated to 300 ° C., and α-Fe ₂ O having a film thickness of 1 μm was formed from above the substrate by a chemical atomization deposition method using the raw material liquid.
_{A 3} (hematite) film was formed. (4) A photoresist is uniformly applied to the substrate, and 120
After prebaking at 30 ° C. for 30 minutes, ultraviolet rays were irradiated according to a predetermined mask to dissolve and remove the unirradiated resist to expose the iron oxide film. Subsequently, the substrate was prebaked at 150 ° C. for 30 minutes, placed in an etching solution (HCl) to remove the exposed portion of the iron oxide film, and then the resist was peeled off with a solvent to form an iron oxide having a predetermined mask shape. A membrane pattern 3 was formed. (5) Next, the patterned hematite film was reduced in hydrogen gas at around 350 ° C. to form a Fe ₃ O ₄ (magnetite) film. (6) Further, the Fe ₃ O ₄ film is subjected to oxidation treatment to form γ-F.
An e ₂ O ₃ (maghemite) film was modified to obtain a desired magnetic thin film.

[0013]

[Comparative Example] An iron oxide film pattern was formed on a glass substrate according to a predetermined mask shape by the same procedure as in Example except that the step (2) in Example was omitted, and reduction treatment and modification by oxidation were performed. However, thinning of the photoresist was observed during the patterning for forming the reaction layer.

[0014]

As described above, according to the method of the present invention, since one layer of the zinc oxide film is provided between the substrate and the iron oxide film, the reaction layer between the substrate and the iron oxide film is formed. Etching is facilitated because precipitation is prevented.Furthermore, by controlling the crystal orientation of zinc oxide, it is possible to control the orientation due to the epitaxial growth of the iron oxide formed on the zinc oxide in the initial stage. The magnetic thin film having a desired orientation can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an iron oxide film pattern formed on a glass substrate in one embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing an iron oxide film pattern formed on a glass substrate in a conventional method for producing a magnetic thin film.

[Explanation of symbols]

 1 glass substrate 2 zinc oxide film 3 iron oxide film pattern

Claims (1)

[Claims] 1. A first step of forming a ZnO film on a substrate by applying an aqueous solution of zinc acetate or an ethanol solution from above the heated substrate by a chemical atomization deposition method or a spray method, (B) A raw material liquid for magnetic thin film preparation in which an iron compound is dissolved in a solvent is applied from above the heated substrate by a chemical atomization deposition method or a spray method to form α-F on the ZnO film.
The second step of forming the e ₂ O ₃ film, (c) the formed α-
Photoresist is uniformly applied to the Fe ₂ O ₃ film, ultraviolet rays are irradiated according to a predetermined mask, the unirradiated uncured resist is dissolved to expose the α-Fe ₂ O ₃ film, and then etching is performed. third step of forming a down, (d) said pattern - - the exposed portion of the alpha-Fe ₂ O ₃ film is removed a predetermined alpha-Fe ₂ O ₃ film corresponding to the mask pattern pattern is training α- The Fe ₂ O ₃ film is hydrogen-reduced to form a Fe ₃ O ₄ film, and is further oxidized and modified to form a γ-Fe ₂ O ₃ film.
A method for producing a magnetic thin film, characterized by comprising steps.