JPS62230010A - Magnetic thin film - Google Patents

Abstract

PURPOSE:To obtain a sufficient Kerr rotation angle even by a practical semiconductor wavelength by specifying a composition ratio of Ptx Niy Mnz Sbt to be formed on a substrate. CONSTITUTION:As a target for forming a Ptx Niy Mnz Sbt thin film by spattering, a target having an areal ratio or a composition ratio as Ptx' Niy' Mnz' Sbt' which is corresponding to a desired composition ratio is used. The elements Pt, Ni, Mn, and Sb are different in probability of bound due to ion bombardment distributing to the spattering, so that target compositions x', y', Z', and t' are determined corresponding to x, y, z, and t of a desired thin film composition Ptx Niy Mnz Sbt in consideration of the above spattering probabilities. These x,y,z, and t are selected out of 0.05<=x<=0.33, 0.005<=y<=0.10, 0.10<=z, t<=0.70, more preferably, 0.1<=x<=0.28, 0.01<=y<=0.06, 0.30<=z<=0.60, 0.20<=t<=0.50. Thus, a photomagnetic recording medium having a big Kerr rotation angle to a light of 780-830 nm and accordingly having a good S/N ratio can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic thin film suitable for magneto-optical recording media and magneto-optic mirrors for polarized beams.

(Prior Art) Various magnetic thin films are being studied with a focus on applications such as magneto-optical recording. For example, edible iron group alloys such as TbFe, MnBL, MnouBi, orthoferrite, P
tMnSb, lPdMn8b%NiMn8b, etc. are known. Here, in order to improve the quality of the signal, it is necessary to have a high Kerr rotation angle, and ptMnsb is attracting attention as a material that has an extremely high Kerr rotation angle at room temperature.

(Problem to be solved by the invention) However, when does ptMnsb exhibit the highest Kerr rotation angle? There is a problem that the Kerr rotation angle decreases near tr o nm, which is a practical semiconductor wavelength.

Therefore, the present inventor conducted research to obtain a magnetic thin film having a sufficient Kerr rotation angle at this practical semiconductor wavelength, and arrived at the present invention.

That is, the gist of the present invention is to form Pt on a substrate.
XNiyMnzdaybt(o, o, r≦X≦0.33,
o, oos-≦y≦0.10, 0.10≦Z, 1t≦0
．． 70).

(Means for solving problems) The present invention will be explained in detail below.

The method for producing the magnetic thin film of the present invention mainly includes the well-known sputtering method, as well as so-called physical vapor deposition methods such as evaporation method, ion blating method, and cluster ion beam method.
Vapor Deposition (hereinafter abbreviated as pVD method) is used. In the sputtering method, ions such as Ar are bombarded with a target material corresponding to the thin film material to be formed, and atoms of the target material are ejected (=sputtering), and the sputtered atoms are deposited on the substrate to form a film. conduct. Generation of ions such as Ar is 10-4~70''I
A gas with a partial pressure of TOrr is introduced into a sputtering vacuum chamber, and a direct current or high-frequency alternating current field is applied to the sputtering vacuum chamber.
et) and a counter electrode (usually a grounded substrate support or vacuum vessel), producing a known glow emission.

When forming the PtxNiyMnz8bt thin film of the present invention, a target having a Ptx'Niy'Mnz's 'bt' area ratio or composition ratio having a composition corresponding to a desired composition ratio is used. Since each element has a different sputtering rate due to the collision of ions contributing to sputtering, i*= sputtering rate, the desired thin film composition PtxNiyMnz8bt corresponds to "+7.z, t" in consideration of this sputtering rate. target composition z′, y
/, zl, -C/ are defined.

This "*79"t t is o, ozkux≦0. J.J.
.

o, ooz≦y≦O, 10, o, io≦z, t≦0.7
0, and X is preferably 0. /≦X≦0・Koz, 0.0/≦y≦0.06.0. ．． 10≦2≦o, b
θ, θ, selected from the range of −〇≦t≦0.30.

In order to obtain the magneto-optical recording medium of the present invention, an alloy target of Ptx'Niy'Mnz'8bt' may be used, or an alloy target of Niy'Mnz'Sbt'
A Pt/js piece is placed on the sintered body of the alloy or the sintered body, and the target surface area ratio as a whole is Ptx'Niy'Mnz'8.
bt'(x' - 1 - y' 1 z' + t' = l) (may also be mixed. PtNi
, MnSb can be used as a target by a combination of small pieces or alloys.

The ions used for sputtering are usually inert gas such as Ar. The power for discharge varies depending on the gas pressure (~degree of vacuum), target size, and substrate area, but is several tens of W.
It ranges from several kilowatts.

In the present invention, substrate materials on which thin films are deposited include glass, polycarbonate (PC), polymethyl methacrylate, epoxy, polyimide, polyamideimide, etc., preferably substrates with low optical birefringence, etc. As the material, well-known materials such as glass, resin, metal, etc. can be used. These substrates may be provided with optical guide troughs (groups) as is known in the optical memory art. The film thickness is usually go-s, oo.

Selected from around λ.

As mentioned above, the method for manufacturing the magnetic thin film of the present invention is not limited to the above-mentioned sputtering method, and any film forming technique known in the field of thin film technology may be used. Raw materials Pt, Ni, Mn,
Using sb as an evaporation source, each or these alloys are placed in a heating crucible and heated by electrical resistance or force-heated by an electron beam to melt the raw materials in a vacuum (10''4
It is possible to form a desired alloy film on the substrate by evaporating the alloy at a temperature of less than TOrr). It is also possible to ionize the evaporated atoms (ridges) during film deposition on the substrate and accelerate them in a t-field while making them reach the substrate. Compared to sputtering, these evaporation methods in a broad sense are more difficult to control the composition of the film to be formed.It is preferable to evaporate each component independently (and at the same time) while adjusting the evaporation rate of each component to the thickness of the film. The temperature of the crucible is adjusted while detecting it with a commercially available product using a crystal oscillator.
Adjust the ratio of each component for evaporation amount.

The thin film thus obtained can then be thermally annealed to control its crystallinity.

Normally, a thin film immediately after deposition solidifies (solidifies) without sufficient diffusion time during the deposition of atoms ((2), resulting in disordered crystallinity, multiphase crystals, or amorphous There are many cases.

As a former magnetic recording medium, it is not possible to determine which is preferable, a film with such disordered crystallinity or a film with high integrity, but it is possible to obtain a film with higher crystallinity. 1 In the case of the medium of the present invention, the temperature is 00°C, preferably 110°C.
Thermal annealing is performed under vacuum at 100°C for 7-20 hours.

Also, instead of the above annealing, the substrate may be heated to 10θ℃ during film formation.
It can also be heated to a certain degree or higher.

The magnetic thin film obtained by the above method is 710-r3
The Kerr rotation angle for 0 nm light is large (therefore,
87N ratio is improved) to provide an excellent magneto-optical recording medium. The obtained medium can also be used by further laminating other magnetic materials. For example, amorphous transition metal alloys (TeF
By stacking with a magnetic material with high recording sensitivity, coercive force, or small Kerr rotation angle, such as e-type), /) it can be used as a protective film for an amorphous host transition metal film; By placing the medium according to the present invention in the li'lij, the Kerr rotation angle of the M# metal film on the amorphous layer can be improved.

(Example) Hereinafter, the present invention will be further explained in detail with reference to Examples.

Example/ (Preparation of magnetic thin film by two-pole sputtering method.) First, N1 powder and Mn8t) powder as a target were mixed and placed in a circular container (SO 56), and NixMn8b (x
= 0.0. Oj, 0.7θ) as a target, a Pt sheet (/θB×10×10, thickness lu) was placed on the target, and the amount of Pt and the amount of N1 were adjusted.

In this way, after moving the target m(j2), move the vacuum chamber to /
After exhausting to below X/0-6 TOrr, hr(q
q, qq%) pressure! The film was formed at RF power of 10 OW at X/04 Torr.

A thermally oxidized S1 wafer is used as the substrate, and the distance between the substrate and the target is 4'! r cm, the substrate temperature was 100°C.

The film thickness is 5000 to 7000λ.

Next, in order to improve the crystallinity of the thin film produced,
After heat treatment at ℃ for 3 to 3 hours, an external magnetic field was applied to account for the magneto-optic effect, and a light beam was incident from the film side to measure the Kerr hysterins. We obtained a value almost equal to the saturation value of the Kerr rotation angle.

Therefore, the dependence of the Kerr effect on the measurement wavelength was investigated with the external magnetic field fixed at 3 Koθ.

The results are shown in Figure/.

The three curves in the figure are NixMn8b targets,
/ MnB b , -I N i (165Mn8 b
.

It is compatible with thin films obtained using JNiO, oMns'b, and is compatible with induced high frequency plasma oscillator spectrometer (IOP).
) are shown in Table 1.

In curves λ and 3 in the figure, the Kerr rotation angle increases at longer wavelengths.

Table 1 Results of engineering ap analysis (effects of the invention) Since the magnetic thin film according to the present invention has a large Kerr rotation angle near g 00 nm, it provides a practical magneto-optical recording medium.

[Brief explanation of drawings]

Figure / shows the wavelength dependence of the Kerr rotation angle at jKOe of the magnetic thin film according to the present invention.

Claims (1)

[Claims] (1) Formed on a substrate, Pt_xNi_yMn_zS
bt(0.05≦x≦0.33, 0.005≦y≦0,
10, 0, 10≦z, t≦0, 70).