JPH0648526B2 - Method of manufacturing magnetic head - Google Patents

Description

Detailed Description of the Invention a. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head manufacturing method.

B. BACKGROUND ART Conventionally, magnetic recording media such as magnetic tapes and magnetic disks are
It is widely used for recording various electric signals such as video, audio and digital. In the method using the magnetization in the in-plane longitudinal direction of the magnetic layer (magnetic recording layer) formed on the substrate, a high density has been achieved by a new magnetic material or a new coating technique. On the other hand, in recent years, along with the increase in density of magnetic recording, a perpendicular magnetization recording method using magnetization (so-called perpendicular magnetization) in the thickness direction of a magnetic layer of a magnetic recording medium has been developed.
It has been recently proposed (for example, “Nikkei Electronics” No.192, August 7, 1978). According to this recording method, the demagnetizing field that acts on the residual magnetization in the medium decreases as the recording wavelength becomes shorter, so that it has characteristics preferable for high density recording and is essentially suitable for high density recording. Therefore, research is currently being conducted toward practical application.

C. OBJECT OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a magnetic head which is suitable for the magnetic recording method as described above and which can be expected to have high magnetization, resistance magnetic force and high corrosion resistance.

D. Structure of the invention That is, the present invention, a plurality of targets made of iron are opposed to each other in a plasma generation vacuum tank, a nitrogen-containing gas is supplied between these opposed targets, and plasma for sputtering the target is generated, After accelerating iron nitride ions generated by this plasma with an accelerating electric field, the energy is controlled with a control electric field and is led out from the plasma generating vacuum chamber to the outside thereof, and the derived iron nitride ions are discharged from the plasma generating vacuum chamber. The present invention relates to a method of manufacturing a magnetic head, which is guided to a magnetic head substrate disposed outside and is deposited on the substrate as iron nitride forming at least a part of a magnetic permeable layer.

E. Examples Hereinafter, examples of the present invention will be described in detail.

First, the structure of the magnetic head manufactured according to the present invention will be described.

FIG. 1 shows magnetic heads 16 and 17 used for perpendicular magnetic recording on a magnetic recording medium 15 such as a magnetic tape. Of these, the head 16 functions as an auxiliary magnetic pole,
The head 17 arranged opposite to this is made to function as a main magnetic pole.

What is characteristic here is that the magnetic film 14 made of iron nitride (FexN), particularly γ′-Fe ₄ N or (α-Fe + γ′-Fe ₄ N) is deposited on the glass substrate S as the main magnetic pole 17. This means that a structure in which this is protected by another holder 18 such as a glass plate is used. As will be described later, the FexN forming the magnetic film 14 has a large saturation magnetization and can sufficiently perform signal recording, and at the same time, exhibits a low resistance (Hc) required for the head. Therefore, the performance of a head having such a magnetic film 14 as a magnetically permeable layer is extremely good. Moreover, FexN also has good corrosion resistance due to the inclusion of nitrogen, which also contributes to the improvement of the head characteristics.

Note that, for example, in this perpendicular magnetic recording system, the auxiliary magnetic pole 16 is excited by a recording signal, and the medium 15 is then excited.
A magnetic field is generated toward the side, whereby the flux is concentrated in the in-plane direction toward the main pole 17, and magnetic recording corresponding to the main pole 17 is performed on the magnetic layer of the medium 15.

FIG. 2 shows another magnetic head 27, but in this head as well, the magnetic film 14 made of FexN is formed on the facing surface of the core material S made of ferrite, for example, on the magnetic gap 20 side. The head may be a head whose entire surface is covered with FexN. A head made of these FexN is particularly suitable for high density recording.

The FexN magnetic film 14 can also be formed on a magnetic head (for example, a thin film head) other than the above.

Next, a method of manufacturing the above magnetic head will be described.

First, a substrate S (glass plate, ferrite core material, etc.) is prepared, and Fe is formed on a predetermined surface of the substrate S by the method described below.
The xN film 14 is formed. For this reason, it is desirable to use the ion beam generator shown in FIGS.

The apparatus shown in FIG. 3 basically comprises an opposed target sputtering section A and an ion beam deriving section B for deriving ionized particles from this sputtering section.

In the sputtering unit A, 1 is a vacuum chamber, 2 is a predetermined gas (Ar + N ₂ ) introduced into the vacuum chamber 1, and the gas pressure is 10 ⁻³ to
It is a gas inlet pipe set to about 10 ^-4 Torr. The exhaust system of the vacuum chamber 1 is omitted in the figure. The target electrode is a pair of targets T ₁ and T ₂ made of Fe by the target holder 4.
Are opposed to each other in parallel and are arranged as opposed target electrodes. A magnetic field is formed between these targets by the external magnetic field generating means (magnet coil) 3. In the figure, 5 is a cooling water inlet pipe, 6 is the outlet pipe, and 13 is an accelerating electrode.

In the sputtering apparatus configured as described above, a magnetic field is formed in the direction perpendicular to the surfaces of the targets T ₁ and T ₂ that face each other in parallel, and this magnetic field causes the cathode descending portion (that is, clearly shown in FIG. 4). as, released by the impact against the target surface of the electric field at an accelerated sputtering gas ions in the region 8,9) between the plasma atmosphere 7 generated between the target T ₁ -T ₂ and each target T ₁ and T ₂ The γ electrons are trapped in the space between the targets and moved toward the other facing target. The γ-electrons that have moved to the surface of the other target are reflected by the cathode fall portion in the vicinity thereof. Thus, the γ-electrons repeat the reciprocating motion while being bound by the magnetic field between the targets T _{1 and} T ₂ . During this reciprocating motion, the γ-electrons collide with the neutral atmospheric gas to generate ions and electrons of the atmospheric gas, and these products promote the emission of γ-electrons from the target and the ionization of the atmospheric gas. . Therefore, high-density plasma is formed in the space between the targets T _{1 and} T ₂ , and the target material is sufficiently sputtered accordingly.

Compared to other flying means, this facing target sputtering apparatus is capable of forming a film at a high deposition rate by high-speed sputtering, does not directly expose the substrate to plasma, and can form a film at a low substrate temperature. It is possible.

The structure to be noted in the apparatus of FIG. 3 is that Fe sputtered from the target in the sputter part A and the reaction gas (N
₂ ) has a lead-out portion B for efficiently leading out the ionized particles, that is, the ions of FexN, to the outside. That is, the deriving unit B includes a screen grid G which is disposed outside the vicinity of the target T _2, the targets T ₂ and the grid G at the same time is held in each predetermined potential, passes through the ionized particles 10 Small holes 11 and 12 are formed in a corresponding number and pattern. This is clearly shown in FIGS. 5 and 6, respectively. The small holes 11 and 12 are, for example, 2 mmφ and are formed at intervals of 5 mm, and the thickness of the grid G is 1 mm.
May be

FIG. 7 schematically shows an electric circuit system for operating the above-mentioned device. In the state where the acceleration voltage Vp is applied to the acceleration electrode 13, a negative voltage Vt is applied to both targets T ₁ and T ₂ , and The grid G is grounded. The substrate S arranged on the side of the ion beam derivation unit B is also grounded. Fig. 8 shows the potential distribution of each part. Vp is 0 to 200 V and Vt is 5
It is set to 0 to 1000V.

When the above apparatus is operated under such conditions, the ions in the plasma generated in the sputter part A (vacuum degree 10 ⁻³ to 10 ⁻⁴ Torr) are generated in the cathode descending part 9 (the fourth target) of the lower target T ₂ .
After being accelerated by the accelerating electrode 13 in FIG. 2), the energy is passed through the small holes 11 and 12 while being decelerated by the electric field between the target T ₂ and the grid G, and the energy corresponding to the potential difference between the substrate S and the plasma is applied. Derived. The extracted ion beam 10 is guided to the derivation part B (vacuum degree 10 ⁻⁵ Torr
The above is effectively focused by the action of the electric field E (see FIG. 3) formed on the side, and is incident on the substrate S with the above energy. Thus, the acceleration electrode (or anode)
By changing the anode voltage Vp applied to 13, the energy of the deposited ions (FexN) on the substrate S is controlled, and the ion beam 1 is efficiently generated by the action of the grid G.
0 can be pulled out and guided onto the substrate S. Further, since the side on which the substrate S is located is pulled by a high vacuum of 10 ⁻⁵ Torr or more, a clean magnetic film containing few impurities can be deposited.

The target T placed on the side from which the ion beam is extracted
It is better not to make the small holes 11 and 12 of No. ₂ larger than necessary, but if they are made too large, unnecessary gas leaks to the substrate S side due to the gas pressure difference between the sputter part A and the lead-out part B, and the purity of the deposited film decreases. It is conceivable that this is likely to occur or is not desirable in terms of the strength of the target T ₂ and the grid G, and that the target area is reduced and the sputtering efficiency is also likely to be reduced.

By the method and apparatus described above, for example, as shown in FIGS. 1 and 2, Fe having a thickness of 2000 Å is formed on the substrate S.
A magnetic head having the xN magnetic film 14 can be created. This magnetic head has a magnetic film 14 suitable for in-plane longitudinal direction recording for high density recording and for perpendicular magnetic recording.

Next, the above magnetized film (FexN) will be described in more detail based on experimental results.

(A), Structure of FexN film The formed films all showed crystallinity, and the crystal structure changed depending on the nitrogen gas mixing ratio, the substrate temperature (Ts) and the ion acceleration voltage (Vp).

Fig. 9 shows the total pressure Ptotal = 5 × 10 ^-4 Torr, Vp = 20V
The crystal structure of the film produced under (constant) conditions and PN ₂ · Ts
(However, the substrate is a (111) Si substrate). T
When s = 200 ° C., the crystal phase formed is a mixed phase of α-Fe and γ′-Fe ₄ N with increasing PN ₂ → γ′-Fe ₄
N single phase → mixed phase of ε-Fe ₃ N and ζ-Fe ₂ N → ζ-Fe
It changes to ₂ N and the nitriding degree of the film increases. Also, α-
In the mixed phase film of Fe and γ'-Fe ₄ N, the interplanar spacing is 1.9 to 2.0.
An unknown crystal phase (UK) having Å was present. T
When s rises above 200 ℃, the boundary between each region becomes high PN ₂
Move to the side. Even when Ts is 200 ° C or lower, the nitriding degree of the film tends to decrease as Ts decreases.
At the temperature of PN ₂ ≦ 4 × 10 ⁻⁵ Torr, only α-Fe phase was formed.

FIG. 10 shows X-ray diffraction patterns of examples of films formed under various conditions. Among the formed phases, the ε phase and the ζ phase showed random crystal orientations. The α-Fe phase of the bcc structure had a <110> direction, and the γ′-Fe ₄ N phase of the fcc structure had a <10> direction.
The 0> direction was strongly oriented perpendicular to the film surface. Conventionally, the α-Fe and γ′-Fe ₄ N films produced by the ordinary sputtering method using only neutral particles as the deposited particles are (110) and (111) planes (for each phase) as the atmospheric pressure decreases. (Closest packing surface)
The above results indicate that in the ion beam deposition method of the present invention, the high kinetic energy and uniform directivity of the deposited particles promote the orientation of the film, and It can be said that this indicates that the surface other than the close-packed surface is likely to be oriented depending on the kind of the compound due to the influence of the charge of the deposited particles.

Ptotal = 5 × 10 ⁻⁴ Torr, PN ₂ = 1.5 × 10 ⁻⁵ Torr
The change of the X-ray diffraction pattern gram with respect to Vp of the film produced under the condition of constant r and Ts = 150 ° C. was examined. At Vp = 0V,
Only the diffraction line of the α-Fe phase with the (110) plane oriented, but V
At p = 40 V, a broad peak clearly appears at the diffraction position of γ ′ = Fe ₄ N phase (111), (200) plane, and at Vp = 60 V, only the diffraction line of α-Fe phase (110) plane again. These show that in the range of Vp = 0 to 40 V, the ratio of the amount of the γ'Fe ₄ N phase increases with the increase of Vp. Further, the orientation of the γ'-Fe ₄ N phase of the film deposited at Vp = 40V and Ts = 150 ° C. is random, and the above Vp =
The γ'phase in the film deposited at 20V, Ts = 200 ° C is (200)
It was different than it showed orientation. Since the increase in Vp causes the increase in the kinetic energy of the deposited ions, it is considered that the surface temperature of the substrate and the mobility of the deposited particles on the substrate surface are increased, and as a result, the reaction between iron and nitrogen is promoted. To be The result of Vp = 60 V is that if the kinetic energy of ions becomes excessive, the bond between iron and nitrogen is suppressed,
Alternatively, it is considered that the particles are re-separated by the impact of another particle even if they are once bonded. Further, it can be said that the orientation of the film is lowered by the impact of the high-energy particles generated by the increase of Vp on the substrate.

(B), Saturation magnetization of FexN film The saturation magnetization (4πMs) of the film was measured by a magnetic balance. 11 and 12 show the relationship between 4πMs and each manufacturing condition. Ptotal = 5 × 10 ^-5 Torr, Vs = 20V (constant)
4 shows the dependence of 4πMs on the PN ₂ and Ts of the film prepared under the conditions described above.

4πMs means that the crystal structure of the film is α-Fe + γ′-Fe ₄ N
+ U. K. In the case of (Unknown) mixed phase and in the γ'phase single phase region, the value exceeds 4πMs (21.6KG) of pure iron,
Especially in the vicinity of the boundary between both regions, it is a very high value of about 25 KG. This high 4πMs is due to the γ'phase and U.S. K. It can be said that it is due to the phase. The region of high 4πMs is shown by the diagonal lines in FIG. 9, but in this region, low Hc can be obtained at the same time as high 4πMs, which is a suitable FexN film as a head material. The reported 4πMs of γ'phase is about 24KG
And that of the γ'single-phase film in the present invention is also 22 to 24 KG.
Are almost the same. Therefore, the fact that the 4πMs of the membrane reaches 25 KG means that the U.S.P. K. This means that the phase 4πMs is higher than the γ ′ phase. High 4πMs film is α + γ ′ +
U. K. Since it was obtained near the boundary between the γ ′ single-phase region and K. The phase may be Fe ₈ N.

High 4πM under Ptotal = 5 × 10 ^-4 Torr and Vp = 20V
The production condition range for obtaining a film having s is PN ₂ = 1.1 × 10 ^-5 to 4.0 × 10 ^-5 Torr (nitrogen gas mixing ratio PN ₂ / Ptotal = 2.0 to 8.0%) when Ts = 250 ° C is constant. , PN ₂ = 3 ×
At a constant 10 ^-5 Torr, Ts = 150 to 250 ° C. Conditions for obtaining a high 4πMs of a film deposited by using an ordinary Rf sputtering device PN ₂ / PBtotal = 2.7 to 4.
Compared with 0%, the range of nitrogen gas mixing ratio is wider. The phase considered to be Fe ₈ N with high 4πMs is
It has been reported that it is vulnerable to the impact of high energy particles on the substrate and the rise in substrate temperature, but in the case of the ordinary Rf sputtering method,
When the plasma potential and the sputtering efficiency change due to the fluctuation of the nitrogen gas mixture ratio, the substrate impact effect of high-energy particles and the fluctuation of the substrate temperature occur, and these act in the direction of inhibiting the crystal growth (breakdown of the metastable phase). Etc.), the forming range becomes narrow. On the other hand, in the ion beam deposition method of the present invention, since the nitrogen gas mixing ratio can be changed independently, it is considered that the production range of the high 4πMs film is expanded.

Also, when the change of 4πMs with Ptotal was measured, it was found that the substrate temperature at which a film having a high 4πMs was obtained increased as Ptotal increased. It is considered that this is because the crystallinity of the formed film is lowered due to the decrease of the ion ratio of the deposited particles with the increase of Ptotal.

FIG. 13 shows the change of 4πMs with Vp. The sample here was prepared under the conditions of Ptotal = 5 × 10 ⁻⁴ Torr, Ts = 150 ° C. and Ptotal = 1 × 10 ⁻³ Torr, Ts = 150 ° C. 4πMs tended to decrease with increasing Vp. This result shows that in the Fe-N film, when the deposited particle energy exceeds 30 eV (corresponding to Vp = 20 V), the short-range order of the film is rapidly lowered.

The following summarizes the results described above.

(a), Fe is controlled by controlling each film deposition condition independently.
The dependency of the crystal structure of the -N film on the nitrogen partial pressure and the substrate temperature becomes clear, and the film can be formed with good reproducibility.

(b) When the ion accelerating voltage Vp = 20 V, among the obtained crystals, α-Fe and γ′-Fe ₄ N phases are (110)
) And the (200) plane were strongly oriented parallel to the film plane. It is considered that this is due to the effects of high kinetic energy, uniform directionality and electric charge of the deposited particles.

(c), the saturation magnetization of the film is 4πMs, and the crystal structure is α + γ ′ +
U. K. (Unknown) In the production condition region where the transition from the mixed phase state to the γ'single phase, the value was about 25 KG, which was higher than that of pure iron.

(d) Substrate temperature at which high 4πMs is obtained is the total pressure Ptotal.
Ptotal is 5 × 10 ^-5 Torr
In the following cases, the temperature was 150-250 ℃. From this, it was found that by increasing the ratio of ions in the deposited particles, the order of the film can be improved even at a low substrate temperature.

Among them, (a) shows good controllability of the ion beam deposition method of the present invention, (d) shows the effect of ionization, and a high-quality film that is difficult to form by the conventional preparation method, It has been shown that the ion beam deposition method can be formed with good reproducibility, which is a proof that the ion beam deposition method is an extremely excellent manufacturing method.

Further, the above FexN film has excellent corrosion resistance due to the inclusion of nitrogen, and is also excellent in this respect.

The above-described example can be modified in various ways.

For example, in FIG. 3, a plurality of grids G may be set to control the ion beam in various ways. Further, without forming the small hole 11 to the lower target T _2, the screen grid as mentioned above on the side between the two targets T ₁ -T ₂ (vertically) arranged so to draw from this ion beam laterally You may In the example of FIG. 3, the FexN film is directly deposited on the substrate S, but instead of the substrate S, a third target T ₃ is arranged as shown by an imaginary line, and the ion beam 10 is applied to the target T _3. The other ionized particles that were impacted and knocked out (sputtered) were added to the above Fe.
The xN particles can be introduced together with the substrate onto the substrate S ′, and a mixed film of them can be deposited on the substrate S ′. For example, if permalloy (Ni ₈₀ Fe ₂₀ ) is used as the target T ₃ , a thin film of a mixture of FexN and permalloy can be obtained on the substrate S ′.

F. EFFECTS OF THE INVENTION As described above, according to the present invention, at least a part of the magnetic permeable layer is made of iron nitride (that is, high magnetization and low H characteristic of iron nitride).
(c, which exhibits corrosion resistance) When manufacturing a high-performance head, a plasma generation vacuum tank is used after accelerating iron nitride ions generated by facing target sputtering with an accelerating electric field and further controlling them under a control electric field (grid voltage). Since it is led out to the outside and is led on the substrate, it is possible to efficiently take out the ions while controlling the energy, and it is possible to form an iron nitride film having excellent magnetic properties and corrosion resistance. In this case, the control electric field (grid voltage) contributes to appropriately control the energy of the ions and pull them out of the vacuum chamber, so that the impact of the ions on the substrate is relaxed to promote the growth of crystals and to improve the magnetic properties. Film can be formed.

Further, since the substrate is arranged outside the plasma generation vacuum tank, the substrate is not exposed to plasma, film formation is possible at a low substrate temperature, and the substrate temperature does not fluctuate. As a result, the substrate temperature can be appropriately set together with the above energy control, and the crystal growth can be sufficiently advanced to form a film with high magnetic characteristics with good reproducibility.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIGS. 1 and 2 are schematic views showing two examples of a magnetic head, FIG. 3 is a sectional view of an ion beam generator, and FIG. Principle diagram of target sputtering, FIG. 5 is a plan view of a target and a grid on the ion beam deriving side, FIG. 6 is a sectional view taken along line XX of FIG. 5, and FIG. 7 is a diagram showing an electric circuit system of the above apparatus. Fig. 8 is a potential distribution diagram of each part, Fig. 9 is a diagram showing the relationship between the crystal structure of the deposited film, the nitrogen partial pressure, and the substrate temperature, Fig. 10 is an X-ray analysis diagram of the deposited film, and Fig. 11 is A graph showing the relationship between the saturation magnetization and coercive force of the deposited film and the nitrogen partial pressure, FIG. 12 is a graph showing the relationship between the saturation magnetization of the deposited film and the substrate temperature, and FIG. 13 is the saturation magnetization of the deposited film and the acceleration voltage. It is a graph which shows the relationship with. In addition, in the code | symbol shown in drawing, 2 ... Gas introduction tube 3 ... Magnet coil 10 ... Ion beam 11, 12 ... Small hole 13 ... Anode (accelerating electrode) 14 ... Magnetic (ized) film T ₁ a T 2 _...... target G ...... screen grid a ...... sputtering unit B ...... ion beam outlet portion S ...... substrate.

Claims (1)

[Claims] 1. A plurality of iron targets are made to face each other in a plasma generating vacuum chamber, a nitrogen-containing gas is supplied between these facing targets to generate plasma for sputtering the target, and the plasma is generated by the plasma. After accelerating the iron nitride ions with an accelerating electric field, the energy is controlled with a control electric field to lead out from the plasma generation vacuum chamber to the outside, and the derived iron nitride ions are placed outside the plasma generation vacuum chamber. A method of manufacturing a magnetic head, which comprises leading to a magnetic head substrate and depositing iron nitride as at least part of a magnetically permeable layer on the substrate.