JPH0456110B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a nitrided magnetic alloy film suitable for magnetic heads and a method for forming the same. BACKGROUND ART Conventionally, attempts have been made to create a magnetic alloy film containing nitrogen by a sputtering method using a mixture of N ₂ gas in Ar gas, a sputtering method using a nitride as a target, and the like. These include nitride films of alloys consisting of Fe, Co, Ni and vitrifying elements B, Si, Al, P, C, etc.
), and research on Fe nitrides (Journal).
of Applied Physics (J.Appl.
phys.) 53 (11) p8332 (1982)). In the former case, for example, Fe-B- nitrided Fe-B system is used.
In N, the perpendicular magnetic anisotropy increases, and in Fe−
The soft magnetism of the B-based alloy is damaged, and the coercive force is reduced.
At the same time as becoming a magnetic film with a large Hc, the saturation magnetization is 4πMs
is known to decrease with nitriding. In addition, in the latter Fe-N alloy film, 4πMs actually increases when it contains a small amount of N, but it is also known that Hc is large and does not exhibit soft magnetism. Applied research is underway. On the other hand, as shown in Japanese Patent Application No. 61-54054, nitride films of so-called metal-metal amorphous alloys have a relatively small Hc, and 4πMs does not decrease much due to nitridation, but rather increases. things are known. However, since this nitride film does not have a sufficiently small Hc, the invention related to the above patent application uses a multilayer structure in which nitrided and non-nitrided layers of the metal-metal amorphous alloy are stacked alternately, thereby making it extremely small. A soft magnetic alloy film of Hc was obtained. However, it has been found that although such a multilayer film has no problems when used at around room temperature, when it is heat-treated at around 300°C, its excellent soft magnetic properties are lost due to interlayer diffusion. Problems to be Solved by the Invention The present invention solves the above-mentioned problems, exhibits a small Hc, exhibits soft magnetism, and has thermally stable characteristics, and also has the wear resistance and relatively high electrical resistance characteristic of nitrides. This enables the nitrided magnetic alloy film shown in FIG. Means for Solving the Problems The nitrided magnetic alloy film of the present invention is represented by the following formula. Tx My Nz ……(1) However, T is one or more metals among Co, Fe, Ni, and Mn, and M is Ti, Nb, Hf, Zr, Ta, W, Mo,
One or more metals among Cr, N is N (nitrogen), and x, y, and z represent atomic percent, respectively 65x94 ……(2) 5y25 ……(3) 0.1z20 ……( 4) x+y+z=100...(5) However, this is a composition-modulated nitrided alloy that has a structure in which x, y, and z do not take constant values in the thickness direction of the alloy, but their values change periodically and continuously. It is something that is characterized by something. Function: Due to its compositionally modulated structure, it is difficult to change properties due to diffusion, is thermally stable, and
The effect of reducing Hc can also be obtained. Furthermore, by including N, wear resistance and relatively high electrical resistance can be obtained. Example To obtain soft magnetism, it is necessary to have x94, 5y, z20...(6), and to obtain sufficient 4πMs, it is necessary to have 65x, y25...(7), improving wear resistance, The experimental results showed that at least 0.1z...(8) is necessary to increase resistivity and improve thermal stability. (6)
From ~(8), it is necessary that (2) to (4) also become equation (5). The feature of the present invention is that it is not a simple nitrided alloy or a multilayer structure alloy, but a nitrided magnetic alloy whose composition has been modulated to have a structure that is thermally stable and difficult to cause diffusion. The objective is to obtain soft magnetic properties that are difficult to obtain with films.
Therefore, when the composition-modified nitride alloy of the present invention is shown in the following formula (1), it means the average composition, and x, y, z
varies periodically and continuously in the thickness direction. It was found that if the period of this compositional fluctuation is taken as the compositional modulation wavelength λ, then the smaller λ is, the smaller the Hc can be obtained. This effect was particularly large at λ1000Å. Conventionally, to form such a compositionally modulated alloy film, the composition of only the N (nitrogen) element was modulated in the film thickness direction by periodically mixing N ₂ gas in Ar gas and performing sputtering. However, such a film was thermally unstable because N diffused during heat treatment and its periodicity became unclear. However, in the present invention, M (=Ti, Nb, Hf, Zr,
Ta, W...) is a constituent element T (=Co, Ni,...)
Focusing on the point that N (nitrogen) is more likely to bond with N (nitrogen), by heat-treating the above alloy film in which only the N element is compositionally modulated at an appropriate temperature, the maximum of M element and N element and the T element are created in the film thickness direction. By creating an alloy with a thermally stable compositional modulation structure in which the minimum values of Extremely high Hc that could not be obtained with nitride film
The purpose is to obtain a soft magnetic alloy film with a small . Further N
It has been found that such a compositionally modulated alloy film containing N has less characteristic deterioration at high temperatures than an amorphous alloy film that does not contain N. That is, an amorphous alloy that does not contain N crystallizes above the crystallization temperature Tc and does not lose its soft magnetic properties, Hc>10 Oe. The Tc of an amorphous alloy is at most 560 to 570°C, and the higher the 4πMs, the lower this value, so when manufacturing a magnetic head using such an amorphous alloy, the heat treatment temperature is usually 500°C.
It is difficult to achieve the above. On the other hand, the composition-modulated nitride alloy film of the present invention has Hc<
It was found that it has an extremely high thermal stability of 5Oe. Although a simple nitride film without compositional modulation is stable, Hc is relatively large both before and after heat treatment, and the compositional modulated nitride film of the present invention is superior in terms of magnetic properties. The nitride magnetic alloy film of the present invention has wear resistance unique to nitrides and relatively high electrical resistance for an alloy, and has the above-mentioned thermally stable soft magnetic properties, making it suitable for applications such as magnetic head cores. It is suitable for [Example 1] Using a target with a composition of Co ₈₃ Nb ₁₇ (atomic %), nitriding was carried out on a ferrite substrate by sputtering and periodically mixing N ₂ gas in Ar gas so as to have a constant partial pressure ratio. A multilayer film with a structure in which a layer and a non-nitrided layer were periodically laminated was formed. Note that the N ₂ gas partial pressure ratio was changed to 0.2%, 5%, 10%, 20%, and 40%. Furthermore, the thicknesses of the nitrided layer and the non-nitrided layer were made almost equal, and three types of layers were created, each having a thickness of 1000 Å, 250 Å, and 125 Å. As a typical example of the obtained film, a multilayer structure film consisting of a nitrided layer and a non-nitrided layer with a N ₂ gas partial pressure ratio of 5% and a layer thickness of about 250 Å was measured using Auger spectroscopy (AES) in the depth direction of the film. The composition profile is shown in Figure 2a. As is clear from the figure, a multilayer structure film consisting of a clear nitrided layer and a non-nitrided layer is obtained. These films were then heated to 480°C.
The composition was heat-treated in vacuum to obtain the composition-modulated nitride film of the present invention. As a representative example, FIG. 1a shows the AES composition profile of the multilayer structure film shown in FIG. 2a in the depth direction after this heat treatment. What should be noted in the figure is that in Figure 2a, the nitrided layer has less Nb and relatively more Co, while the non-nitrided layer has a relatively large amount of Nb.
However, due to this heat treatment, N diffused and there was no clear distinction between the nitrided layer and the non-nitrided layer, but a compositionally modulated profile remained, leaving a compositional profile with a large amount of Co and a small amount of Co. It can be seen that the maximums of the two coincide, and on the contrary, Co shows a minimum at the maximum of both, resulting in a profile with a tendency opposite to that shown in Figure 2a. This is because when creating a multilayer film, sputtering in a _N2 mixed gas tends to result in a film with a reduced Nb composition compared to sputtering only in Ar gas, but Nb and N
Since Co and N bond more easily, it is thought that the above-mentioned compositional change was caused by heat treatment at an appropriate temperature. For comparison with these alloy films,
A simple nitride film with a N ₂ partial pressure ratio of 5%, 10%, or 20% is also N ₂
It was prepared by sputtering method in mixed gas. The multilayer structure film prepared above, the composition-modulated nitride alloy film of the present invention,
A simple nitride alloy film was heat-treated in a rotating magnetic field at 340°C, and the changes in properties before and after the heat treatment were investigated. The results are summarized in the table below.

[Example 2]

Using the same target as in Example 1, a normal Co--Nb amorphous alloy was prepared by sputtering only in Ar gas without mixing N ₂ gas. This alloy film and the invention alloy films b′, d′, g′ prepared in Example 1,
The hardness and electrical resistance measurements of j' and l' are summarized in the table below.

[Example 3]

Various compositionally modulated nitride alloy films were prepared using various targets in the same manner as in Example 1, and their properties were investigated. The results are summarized in the table below.

[Example 4]

Using Co ₈₂ Nb ₁₂ Ta ₂ Zr ₄ as a target, a composition-modulated nitride alloy film with an average N element content of 5% and a modulation wavelength of 500 Å was prepared in the same manner as in Example 1. For comparison, an amorphous alloy film was created by sputtering only in Ar gas using the same target.
Subsequently, using the same target, a nitride alloy film was created by sputtering in Ar gas mixed with 5% N ₂ gas. These samples were heat treated in vacuum at 620°C for 30 minutes, and the stability of their magnetic properties was compared.
FIG. 3 shows the 60Hz BH curves of these samples before and after heat treatment. As is clear from the experimental results, the non-nitrided amorphous alloy film (a) in the figure was completely crystallized by this heat treatment and lost its soft magnetic properties before the heat treatment, and the mere nitride film (c) in the figure was completely crystallized by the heat treatment. The deterioration of characteristics is small, but the drawback is that Hc is large. In contrast, it can be seen that the composition-modulated nitride alloy film of the present invention shown in b in the figure maintains its soft magnetic properties even after heat treatment, and has extremely good stability. Effects of the Invention As explained above with reference to Examples, the composition-modulated nitrided magnetic alloy film of the present invention has excellent thermal stability of magnetic properties compared to conventional amorphous alloy films and multilayer structure alloy films, and also has simple nitrided magnetic alloy films. This is a new magnetic alloy film that exhibits excellent soft magnetism that is difficult to obtain with films, and also has wear resistance and high specific resistance unique to nitride alloys, making it suitable for applications such as magnetic heads.

[Brief explanation of drawings]

Figure 1 shows the composition-modulated nitride alloy film of the present invention.
A graph showing the composition profile in the depth direction of the film by AES.
A graph showing the composition profile by AES in the depth direction of the film after °C heat treatment. Figure 3 is the B-H curve at 60Hz when creating the composition-modulated nitride alloy film, amorphous alloy film, and nitride alloy film of the present invention. It is a graph showing the BH curve after heat treatment at 620°C.

Claims (1)

[Claims] 1 Consisting of the composition TxMyNz, and T, M,
A nitrided magnetic alloy film characterized in that each composition of N is periodically and continuously modulated in the film thickness direction. However, T is at least one metal selected from the group consisting of Co, Fe, Ni, and Mn; M is Ti;
At least one metal selected from the group consisting of Nb, Hf, Zr, Ta, W, Mo, and Cr, where N is N (nitrogen), and x, y, and z represent atomic percent, each 65x94 5y25 0.1z20 x+y+z=100. 2. The nitride magnetism according to claim 1, wherein the composition is modulated such that the maximum of the compositional modulation of the constituent elements M and N in the film thickness direction becomes the minimum of the compositional modulation of the constituent element T. Alloy membrane. 3 Composition modulation wavelength or period in the film thickness direction is 1000
The nitrided magnetic alloy film according to claim 1 or 2, characterized in that: 4 Using an alloy target having the composition shown by Tx'My', a multilayer film consisting of a nitrided layer and a non-nitrided layer was formed by periodically mixing N ₂ gas in Ar gas and sputtering. 1. A method for forming a nitrided magnetic alloy film, characterized in that a nitrided magnetic alloy film having a composition represented by TxMyNz and whose composition is modulated in the film thickness direction is obtained by heat-treating a multilayer film. However, T is at least one metal selected from the group consisting of Co, Fe, Ni, and Mn; M is Ti;
At least one metal selected from the group consisting of Nb, Hf, Zr, Ta, W, Mo, and Cr, N is N (nitrogen), and x, y, z and x', y' are atoms They represent percentages and are respectively 65x94, 5y25, 0.1z20, x+y+z=100, 75x'94, 6y'25, x'+y'=100. 5 _N2 so that the composition modulation period is 1000〓 or less
5. The method of forming a nitrided magnetic alloy film according to claim 4, wherein a gas mixing period is set.