JPH0318007A - Manufacture of soft magnetic thin film - Google Patents

Abstract

PURPOSE:To obtain excellent soft magnetic characteristics by depositing thin film of cobalt alloy incorporating nitrogen atoms on a substrate to a specified thickness by sputtering such as ion sputtering. CONSTITUTION:Sintered NbN pellets are arranged on a Co plate, and a composite target 4 is formed. The target 4 and a subliterate 5 comprising heat resisting glass are set in a vacuum chamber 6. Thereafter, the inside of the vacuum chamber 6 is made to be a high vacuum state of 1X10<-6>Torr or less. Then, argon gas is introduced into the chamber through a needle pipe 2 so that the pressure in the chamber becomes 1.5 half-angle space X 10<-3>Torr. Then, argon ions which are accelerated at 0.7kV are projected on the target 4 from an ion gun 3. The sputtered particles generated in this way are deposited on the substrate 5 to a thickness of 5,000-8,000Angstrom . In this way, the excellent magnetic characteristics can be obtained even at high temperature.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of manufacturing a soft magnetic thin film used in, for example, a magnetic head, and particularly relates to a method of manufacturing a soft magnetic thin film of an alloy mainly composed of cobalt. It is. [Prior Art] Permalloy, cobalt-based amorphous alloys, Sendust, etc. are mainly being studied as soft magnetic thin film materials to be applied to magnetic heads, high-frequency reactor cores, magnetic shielding materials, etc. In particular, cobalt-based amorphous alloys such as Co-Nb-Zr alloys are considered promising because they have high saturation magnetic flux density, low magnetostriction constant, and good soft magnetic properties. However, this soft magnetic material is not without practical problems, and there are various constraints on the manufacturing process of various magnetic elements, especially in terms of thermal stability. For example, when manufacturing a magnetic head, there is a process in which glass is interposed between the magnetic cores and the glass is melted by heating to join the cores together, or the magnetic cores are heat-treated in a magnetic field to improve their magnetic properties. The process is carried out at a relatively high temperature of, for example, about 600° C. Therefore, there is a problem in that these heat treatments promote crystallization of the soft magnetic thin film and significantly deteriorate the soft magnetic properties. Furthermore, when this cobalt-based amorphous alloy is made cobalt-rich to increase the saturation magnetic flux density, the crystallization temperature of the soft magnetic thin film drops significantly, which limits the heat treatment temperature and narrows the process margin. be. Therefore, there are strong expectations for the development of materials that maintain a high saturation magnetic flux density and have a high crystallization temperature, both from the perspective of process margins and magnetic properties.

As one method to meet these expectations, a nitride film of cobalt-based amorphous alloy has already been proposed (IEICE Technical Research Report MR86-4, P25-32r)
Magnetism of amorphous alloy film sputtered in N, mixed gas"). As a result, chambering increases the crystallization temperature, increases the film hardness, and further increases the saturation magnetic flux density. [Problems to be Solved by the Invention] However, on the other hand, the soft magnetic properties of this film deteriorate significantly when the film thickness exceeds 300 Å, making it difficult to apply it to the field of application. As a countermeasure to this problem, an attempt was made to alternately stack extremely thin nitride films and non-nitride films to prevent deterioration of the magnetic properties. Although this method was able to prevent deterioration of the soft magnetic properties, it is necessary to form multiple extremely thin films to a desired thickness. The thickness of the nitride film and non-nitride film is 200 mm.
In the case of λ, for example, in order to form 10,000 soft magnetic thin films, it is necessary to repeatedly form nitride films and non-nitride films 50 times. As a result, the manufacturing process is extremely complicated and poses problems in terms of productivity and cost. The object of the present invention is to provide a method for manufacturing a soft magnetic film that overcomes these drawbacks and has excellent soft magnetic properties even when it is a thick single layer film. Means for Solving the Problems C. To achieve the above objects, the present invention provides sputtering such as ion sputtering using a cobalt-based alloy containing nitrogen atoms, such as C○-Nb or Go-Nb-Zr, as a target. For example, a Co-Nb amorphous alloy containing nitrogen atoms or a Co-
It is characterized by depositing a thin film of cobalt-based alloy, such as Nb-Zr amorphous alloy, to a predetermined thickness. [Example 2] The soft magnetic material used in the present invention is cobalt (C
o) as the main component, and niobium (Nb). Zirconium (Zr
). Tantalum (Ta). Titanium (Ti). hafnium(
Hf). A Co-Metal amorphous alloy containing at least l types of metal elements such as yttrium (Y), particularly at least Nb. Alloys containing either Zr are preferred. Furthermore, alloys having the following alloy composition formula are suitable. Alloy composition formula (T-M) z-X (Ml, MJ
- M) is mainly composed of Co, and a portion of the Co can be replaced by 10% or less with at least one metal element of Fa or Ni. Substitution beyond this level is undesirable because it deteriorates the soft magnetic properties. M1 is at least one metal element of Zr, Hf, and Y. M2 is at least one metal element selected from Nb, Ta, Mo, and V/. 8 is. It is a numerical value in the range of 0.05 to 0.3. Said M
E is an additive element for promoting vitrification, M2 is an additive element that makes magnetostriction negative, and M. / (M,
+M. ') is preferably in the range of 0.3 to 0.9. The sputtering method used in the present invention includes, for example, ion beam sputtering method, high frequency sputtering method,
There are direct current sputtering methods, among which ion beam sputtering method is particularly suitable. Next, embodiments of the present invention will be explained with reference to the drawings. (Example 1) No. 11 is a schematic diagram of an ion beam sputtering apparatus used in an example of the present invention. In the figure, 1 is an exhaust pipe, 2 is a 21 dollar valve, 3 is an ion gun, 4 is a target, 5 is a substrate, and 6 is a vacuum chamber. After setting a composite target 4 in which sintered NbN pellets are arranged on a CO plate and a substrate 5 made of heat-resistant glass in a vacuum chamber 6, the inside of the vacuum chamber 6 is heated to a temperature below I A high vacuum condition is established, and argon gas is introduced from the 21 dollar valve 2 so that the pressure inside the chamber becomes 15 half-width space XIO-' Torr. Next, the target 4 is irradiated with argon ions accelerated to 0.7 KV from the ion gun 3, and the sputtered fine particles generated by the ion gun 3 are deposited on the substrate S to a thickness of 5,000 to 8 KV.
Deposit so that there are 000 people. In addition, the argon ion irradiation current in the thin film type was 20 mA, and the film deposition rate was 20 to 30 people/min. The composition of the thus prepared sample was measured by Auger electron spectroscopy, the crystal structure by X-ray diffraction using CuKα, and the magnetic properties by B-H loop tracer. The high-temperature stability of the magnetic properties was evaluated by varying the heat treatment temperature from room temperature to 600°C and by the change in magnetic properties (H c ) when heat treated in a magnetic field of 4000e. In addition, in order to investigate the nitriding effect, a non-nitriding sample was also prepared for comparison. When making this sample, G
A Nb pellet placed on an O plate was used as a target. Nb/ (Co+N
b) So that X100 = 16 atom%. The number of NbN pellets or Nb pellets placed on the Co plate was adjusted. FIG. 2 and FIG. 3 show examples of the present invention.
FIG. 3 is a diagram showing the X-ray diffraction pattern of a sample subjected to ion sputtering using an o-NbN target after being directly treated as a film and heat-treated at 600° C. for 30 minutes in a 4000 g magnetic field. For comparison, Figures 4 and 5 show the results of X-rays immediately after ion sputtering of a sample using a Go-Nb target and after heat treatment at 600°C for 30 minutes.
m. It is a diagram showing a diffraction pattern. As is clear from Figures 2 and 4, both samples are in an amorphous state immediately after film formation (before heat treatment) and exhibit a broad halo pattern. When a soft magnetic thin film formed using a Co-Nb target that does not contain nitrogen is heat-treated at high temperature, the intensity of the diffraction peak is large, as shown in Figure 5, indicating that crystallization has progressed significantly. Co-N containing nitrogen
When a soft magnetic thin film formed using a bN target is heat-treated at high temperature, some crystallization is observed, as shown in Figure 3, but it is clear that the crystallization is not that pronounced. FIG. 6 is a characteristic diagram showing the dependence of coercive force on heat treatment temperature for the two samples. The fruit in the picture! ! A is a characteristic curve using a Go-NbN target according to an embodiment of the present invention, one point! mB is a characteristic curve of a comparative example using a Co-Nb target. As is clear from this figure, in the case of song tAB, approximately 450
℃ (M crystallization start temperature), crystallization occurs rapidly and the coercive force increases rapidly5.On the other hand, in the case of curve B, the coercive force is relatively high even at a high temperature of 600℃. It has low magnetic properties and good soft magnetic properties. (Example 2) Co-NbN (Co:Nb=87:13)
(The composition of each metal was adjusted by the number of NbN plates placed on the CO plate.) In an Ar atmosphere. Ar ion irradiation current 20
A film of Co-Nb amorphous alloy containing nitrogen was deposited on the substrate with a thickness of 500 mA and a film deposition rate of 20 to 30 in/min.
A soft magnetic thin film of 0λ was formed by ion beam sputtering. (Example 3) A composite target consisting of Co-NbN (Co:Nb=87:13) was set in a high-frequency two-pole sputtering device, and Go-Nb containing nitrogen was deposited on the substrate by high-frequency sputtering in an Ar atmosphere. A soft magnetic thin film with a thickness of 5000 mm was formed from an amorphous alloy. Immediately after film formation (I) of each sample obtained in Examples 2 and 3 and in a magnetic field of 4000 s,
After heat treatment at 0°C for 30 minutes, the Hcie of (n) was measured, and the results are shown in the following table. Table As is clear from this table, by using a Go-based alloy containing nitrogen as a target in the sub-frequency sputtering method, even at high temperatures such as 600°C, the film composition may differ slightly, but for example, curve B in Figure 6 It is possible to maintain a lower coercive force compared to . Furthermore, as in Example 2. If the film is formed using the ion beam sputtering method, the H will always be low even when exposed to high temperatures immediately after film formation.
It maintains a and has excellent thermal stability. Although the theoretical basis for why He is always lower when forming a film by ion sputtering even when the same target is used is not clear, the following may be considered. In other words, in the case of high-frequency sputtering, if nitrogen exists in the target, it will be ionized in the argon plasma and the film surface will be exposed to the nitrogen ions, resulting in the formation of columnar structures in the film. As it grows, perpendicular magnetic anisotropy occurs, which is thought to cause some deterioration of the soft magnetic properties. On the other hand, if the ion sputtering method is adopted as in the above embodiment, the plasma is inside the ion gun and the film is not exposed to these ions, so the soft magnetic film formed by the ion beam sputtering method is simply Even if it is a layered film, it has excellent soft magnetic properties regardless of whether it is heat-treated or not. Although the above heat treatment was performed in a magnetic field, it has been experimentally confirmed that similar excellent soft magnetic properties can be obtained even if heat treatment is performed without applying a magnetic field. In addition, although the case of Co-Nb based composition was explained in the above-mentioned example, the present invention is not limited to this, and for example, Co-Nb-Z
It can also be applied to other compositions such as r-based. [Effects of the Invention] As described above, the present invention performs sputtering using a cobalt-based alloy containing nitrogen atoms as a target to form a cobalt-based alloy thin film to a predetermined thickness on a substrate.
It is possible to produce soft magnetic thin films with excellent magnetic properties even at high temperatures. Furthermore, since there is no need to laminate multiple layers of nitride and non-nitride films as previously proposed, it is possible to improve productivity and reduce costs.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the ion beam sputtering device used in the present invention, and Figs. 2 and 3 show a Co-Nb film formed by the ion beam sputtering method using a Co-NbN composite target. -X before and after heat treatment of N film
I! The diffraction pattern diagrams, Figures 4 and 5 are Co-
Figure 6 shows the X-ray diffraction patterns before and after heat treatment of a Co-Nb film formed by ion beam sputtering using a Nb composite target. be. l...Exhaust pipe, 2...21 dollar valve, 3...Ion gun, 4...Target, 5...Board, 6・・・・・・Vacuum tank. 1st Figure 4 Figure 2e (deg.) 5th Figure 30 35 40 45 2e (deg.) 50 2nd Figure 30 35 40 45 50 20 (deg.) 3rd Figure 30 35 40 45 50 20 (deg.) Figure 6 Ta (go)

Claims (3)

[Claims] (1) A method for producing a soft magnetic thin film, which comprises depositing a nitrogen-containing cobalt-based alloy thin film to a predetermined thickness on a substrate by sputtering using a cobalt-based alloy containing nitrogen atoms as a target. (2) A method for manufacturing a soft magnetic thin film according to claim (1), wherein the target is mainly composed of cobalt and contains nitrogen and at least one of the metal elements niobium and zirconium. (3) In claim (1) or claim (2),
A method for manufacturing a soft magnetic thin film, characterized in that the sputtering is ion beam sputtering in which the target is irradiated with an accelerated ion beam.