JPS59139616A - Manufacture of magnetic thin film - Google Patents

Abstract

PURPOSE:To obtain a magnetic film having a coercive force of 1.0 Oe or less with excellent reproducibility by the magnetron sputtering under Argon gas pressure of 1X10<-3>Torr or less. CONSTITUTION:For the formation of magnetic films 2, 5, a washed substrate 15 is first set to the specified position in the bell jar 8 and the inside is exhausted up to 1X10<-5>Torr by a diffusion pump 10. Thereafter, the substrate 15 is heated by a heater 16, residual gas is exhausted by a trap 12, a temperature of substrate 15 is lowered when a gas pressure in the bell jar 8 reaches 1X10<-6>Torr, and the Argon gas is introduced (T1) from the gas inlet port while monitoring a flow meter 18 so that the gas pressure in the bell jar 8 becomes 1X10<-3> Torr or less. Next, presputtering is carried out while a shutter 17 is being closed so that the film is not deposited on the surface of substrate 15. Before opening the shutter 17, the Argon gas pressure is lowered by operating a needle valve 19 while the discharging is being continued and the shutter 17 is opened while a magnetic field is being applied to the surface of substrate 15 under a pressure of 1X10<-3>Torr or less. The sputtering (T2) is carried out and a permalloy film is formed in the thickness of 1mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of manufacturing a magnetic thin film, and particularly to a method of manufacturing a magnetic thin film with a low coercive force by magnetron sputtering.

[Prior art]

FIG. 1 shows the structure near the medium facing surface of a magnetoresistive magnetic head, which is a type of thin film magnetic head.A magnetoresistive magnetic head is generally manufactured using a thin film forming technique such as sputtering on a ceramic substrate 1. The film thickness is 1 using
Lower shield film 2, which is a magnetic film of μm or more, film thickness 500
Magnetoresistive film 3 which is a magnetic film of A or less, conductor film 4, film thickness 1
It is formed by laminating the upper shield film 5, which is a magnetic film of μm or more.

Insulating films 6 and 7 are formed between the lower shield film 2 and the magnetoresistive film 3, and between the magnetoresistive film 3 and the upper shield film 50, respectively, for forming gaps.

The characteristics of such a thin film magnetic head are significantly influenced by the magnetic characteristics of the magnetic film 2.3.5 made of permalloy formed by evaporation in a magnetic field or sputtering method. The coercive force is the quantity that directly represents the magnetic properties of a magnetic thin film, but in order to obtain good head characteristics, the coercive force in the axis of easy magnetization of the shield films (magnetic films) 2 and 5 must be at least 1
．． The coercive force in the easy axis direction of the magnetoresistive film 3 must be kept below 2.56'e so that the QO'e is below.

When forming a permalloy film by sputtering, argon gas pressure is a factor that affects coercive force, and in order to reduce coercive force, it is desirable to lower the argon gas pressure as much as possible within the capability of the apparatus. This is because the amount of active impurity gas (for example, oxygen) occluded in the film during sputtering decreases as the argon gas pressure decreases, so deterioration of magnetic properties due to impurity gas is prevented. .

By the way, in a normal two-pole sputtering device, 1×10-”
Since the discharge cannot be sustained stably unless the argon gas pressure is over Torr, the main valve must be mostly closed and the pumping speed must be kept low to prevent the oil diffusion pump from going down. An increase in coercive force due to active impurity gas (active impurity gas) is unavoidable. That is,
The coercive force of a film of 1 μm or more is usually 1.0-, s, oooo
Therefore, such a film with high coercive force cannot be used as a magnetic film for a thin film magnetic head.

In order to solve such tf6M, a method is known in which a bias voltage is applied to the substrate in a two-pole sputtering device and sputtering is performed while sputter-etching the substrate surface, but this method results in non-uniform film thickness. However, it has not been put into practical use at present because it has the major drawback that the film thickness tends to be extremely thin, particularly in the peripheral area of the substrate.

Remove defects such as 2-pole spatter, 1 x 10'
Ion beam sputtering, three-pole sputtering, or four-pole sputtering are known as methods that can perform sputtering even under low argon gas pressure under Torr μ.

The ion beam sputtering method is a method in which sputtering is performed by irradiating a target with an ion beam.
) Since the film can be formed in a plasma-free state, the substrate surface temperature during film formation can be kept low; and (2) the film formation conditions can be precisely controlled.
It has played a major role in elucidating sputtering phenomena and in analytical equipment. However, because it is difficult to develop a high-current ion source, the film formation rate is slow, and its application to film formation is significantly delayed compared to plasma sputtering.

On the other hand, the three-pole or four-pole sputtering method, in which a third electrode for thermionic emission is added as an electron supply source for plasma generation, uses α
) Due to the short life of the filament, it becomes an obstacle to continuous operation of the device. ) There is a problem that impurities from the filament get mixed into the film and change the properties of the film, so it is hardly used today.

The magnetron sputtering method deflects high-speed electrons emitted from the target by applying a magnetic field parallel to the target surface, suppressing adverse effects such as substrate heating due to substrate collision, and actively using it to ionize argon gas. . Therefore, about 5×lOTorr! It is possible to form a film on an organic insulating film such as a photoresist at high speed even under a low argon gas pressure of 200 mL, making it the most suitable method for forming a magnetic film for a thin-film magnetic head.

However, according to experiments conducted by the inventors, I
Even when sputtering is performed under an argon gas pressure of It has been found that it is difficult to reduce the magnetic film to 1.0" Oe or less, which is the practical limit value for magnetic films for heads.

[Purpose of the invention]

The purpose of the present invention is to improve the above-mentioned conventional drawbacks by producing a magnetic film having a coercive force of 1.0 oersted or less by performing magneto 4 sputtering under an argon gas pressure of I x 10-'Torr or less. An object of the present invention is to provide a method for manufacturing a magnetic thin film that can be obtained with good reproducibility.

[Summary of the invention]

In order to achieve the above object, the present invention provides a method for forming a magnetic film by magnetron sputtering.
Discharge is started under an argon gas pressure of orr or more, and then the argon gas pressure is increased to lXl0-8'l'orr.
Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 2 to 6.

Fig. 2 is a schematic diagram of the magnetron type sputtering device used in this example, and Fig. 3 is a shield film (permalloy film) for a magnetoresistive thin film magnetic head as shown in Fig. 1.
The graph shows the change over time in the gas pressure inside the Pelger 8 when Nos. 2 and 5 were formed using the magnetron type sputtering apparatus shown in FIG. 2.

To form the magnetic film 2.5, first, a cleaned substrate 15 is placed in a predetermined location in a Pelger (vacuum chamber) 8, and the vacuum is evacuated to I.times.10' Torr using a diffusion pump 10. Thereafter, the substrate 15 was heated to 350°C using a Hilter 16.
the remaining gas is exhausted by the trap 12,
When the gas pressure inside the Pelger 8 reaches lXl0 Torr, the temperature of the substrate 15 is lowered to 300°C, and the gas pressure inside the Pelger 8 reaches IX10-8 Torr.
The above (in this example, 5 as shown in Fig. 3)
X I Q-8Torr) becomes J: Tsuni:, 7o
- Inject argon gas into gas inlet 1 while monitoring meter 18
Install from 1 (T-engineering).

Next, in order to clean the surface of the target 14, bliss sputtering is performed with the shutter 17 kept closed so as not to deposit a film on the surface of the substrate 15. Conventionally, as shown by the broken line a in FIG. 3, the shutter 1 is applied while applying a magnetic field of l OOOe to the surface of the substrate 15 by the coil 13 while continuing the discharge under the same argon gas pressure after pre-sputtering.
7 and moved on to main sputtering. In this embodiment, as shown by the solid line in FIG. 2, before opening the shutter 17, the needle valve 19 is operated while the discharge is maintained to reduce the argon gas pressure.
The main sputtering is started by opening the shutter 17 while applying a magnetic field of l OO6'e from the coil 13 to the surface of the substrate 15 under a pressure of (r or less (in this example, 2X10 Torr as shown in FIG. 3)). A permalloy film with a thickness of 1 μm was formed.

After the main sputtering (T,), the substrate 15 was cooled while exhausting the inside of the Pelger δ, and when the substrate temperature became 50° C. or lower, it was taken out of the Pelger 8.

It has been found that once the discharge is caused under the argon gas pressure (l X I O'Torr or higher) where discharge is likely to occur as in this example, the discharge continues even if the argon gas pressure is subsequently lowered.

FIG. 4 shows the relationship between the argon gas pressure during main sputtering when forming an 81 Ni-19Fe permalloy thin film and the easy axis coercive force of the formed thin film. In FIG. 4, a shows the characteristics of the permalloy film formed under the conventional argon gas pressure, and b shows the characteristics of the permalloy film formed under the argon gas pressure of this embodiment.

From FIG. 4, it can be seen that in this example,
The easy axis coercive force of permalloy thin films formed under argon gas pressure below rr is small, and the width of variation in properties between substrates C
It can be seen that even when considering It can be seen that it is difficult to suppress the coercive force of all films to 1.0'Oe or less because the easy axis coercive force is large and the variation width d between substrates is also large.

Figure 4 shows the relationship between the anisotropic dispersion angle (α90) and argon gas pressure in the permalloy film shown in Figure 4. In FIG. 5, a shows the anisotropic dispersion angle of the permalloy film formed under the conventional argon gas pressure, and b shows the permalloy film formed under the argon gas pressure of this embodiment.

From FIG. 5, the anisotropic dispersion angle of the permalloy film formed by the method according to this example is smaller than that of the permalloy film formed by the conventional method, and the anisotropic dispersion angle between the substrates is small. The dispersion angle variation width e is also the variation width f according to the conventional method.
It can be seen that a magnetic film that is smaller in size and has good magnetic properties can be obtained with good reproducibility.

FIG. 6 shows a 1 μm magnetic gap 6.7 made of Sin, a permalloy magnetoresistive film 3 with a film thickness of 0.05 μm,
The half-width (relative The relationship between the above-mentioned shield film 2.5 and the easy axis coercive force of the shield film 2.5 having a film thickness of 1 μm is shown. From Figure 6, the magnitude of the easy axis coercive force is 1. Below O'Oe, there is no significant difference in the half-width of the reproduced waveform, but above 1.0''O'e, the half-width increases, indicating that the shielding film is not fully functioning. An increase in half-width results in a decrease in head output when reproducing high-density recorded information,
Therefore, it was confirmed that this is not preferable because it causes a decrease in the S/N ratio.

In the above embodiment, a case was described in which a Fe--Nt gold alloy (permalloy) film was formed as a shielding film made of a high-permeability magnetic material. Ni-Mo, Fe-A
, 1-8i, Fe-B, Co-Ti.

It was also confirmed that this phenomenon was observed in amorphous alloy films such as Co-Fe-B and Co-Fe-B.

Further, in the above embodiments, a magnetoresistive type thin film magnetic head has been described, but it has been recognized that similar effects can also be observed in an inductive type thin film magnetic head.

As described above, a magnetic thin film formed using a magnetron type sputtering device under an argon gas pressure of less than 1.0 Torr has not only a coercive force of always less than 1.06e but also a small dispersion angle.

Furthermore, by using a thin film magnetic head having a magnetic film formed by the same method, even information recorded at high density can be reproduced without reducing the S/N ratio.

〔Effect of the invention〕

As explained above, according to the present invention, I
Magnetron sputtering can be performed under an argon gas pressure of orr or less, a magnetic film with a small coercive force can be manufactured with good reproducibility, and the manufacturing yield can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the structure of a magnetoresistive thin-film magnetic head near the medium facing surface, FIG. 2 is a diagram showing a schematic configuration of a magnetron sputtering apparatus used in the present invention, and FIG. FIG. 4 is a diagram showing the relationship between the argon gas pressure in the Pelger and the easy-axis coercive force of the permanent four-layer thin film formed under the argon gas pressure. , FIG. 5 is a diagram showing the relationship between the argon gas pressure in the Pelger and the dispersion angle of the permanent thin film formed under the argon gas pressure, and FIG. It is a diagram showing the relationship between the easy axis coercive force and the half width of the reproduced waveform in the head. a: Argon gas pressure in the conventional method, b: Argon gas pressure in the present invention, T: Argon gas introduction time, T2 : Main sputtering start time, T8: Main sputtering end time.

Claims (1)

[Claims] α) When forming a magnetic thin film by magnetron sputtering, discharge is started under an argon gas pressure of I X 1' 0-8 Torr or more, and then the discharge is started by reducing the argon gas pressure to I X 10' Torr or less. A method for producing a magnetic thin film, characterized in that it lasts.