JPH04149812A - Magnetic head - Google Patents

Abstract

PURPOSE:To prevent the degradation in performance and to improve reliability by using a material consisting essentially of Nb as an electrode to be connected to a diaferromagnetic film. CONSTITUTION:The diaferromagnetic film 3 for controlling magnetic domain structures is connected to a magneto-resistance effect film 2 and a lead wire 4 consisting of Nb contg. unavoidable impurities is connected to the magneto- resistance effect film 2 and the diaferromagnetic film 3. The diaferromagnetic film 3 and the lead wire 4 are formed at both ends of the magneto-resistance effect film 2 and a part or the whole of the diaferromagnetic film 3 connected to the magneto-resistance effect film 2 is coated with the lead wire. A conductor film for biasing is formed in contact with the magneto-resistance effect film 2. The magneto-resistance effect film 2 and the conductor film for biasing are in contact with each other in the part which is not coated with the lead wire 4 or the diaferromagnetic film 3. The magneto-resistance effect film 2 consists of an Ni-Fe alloy or Ni-Fe-M alloy, where M consists of Co, Rh, Ru. The diaferromagnetic film 3 consists of an Fe-Mn, Ge-Mn, Co-Nd or Fe-Mn+X alloy and X is preferably Ni, Co, Rh, Ru, Pt, etc.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to the structure and material of a magnetic head in a magnetic recording device.

[Conventional technique] In a magnetic head that uses the magnetoresistive effect, an antiferromagnetic material is provided in part or all of the magnetoresistive film in order to suppress Barkhausen noise caused by movement of the domain wall of the magnetoresistive film. The magnetic domains are controlled by applying an exchange bias magnetic field. Further, lead wires are provided at both ends of the magnetoresistive film to detect the output, and the material used for the lead wires is Au, Cu, or the like. In a head having such a structure, an electrode is formed in contact with an antiferromagnetic film, as disclosed in Japanese Patent Laid-Open No. 62-40610 and Japanese Patent Laid-Open No. 2-12610. Furthermore, in JP-A-2-68706, a case is shown in which tungsten is used as an electrode when combined with an antiferromagnetic film.6 In order to improve the porosity and adhesion of tungsten, the top and bottom of tungsten are coated with other metals. A structure is disclosed in which sandwiched electrodes are formed on an antiferromagnetic material. [Problems to be Solved by the Invention] The above-mentioned prior art does not take into account the reaction that occurs between the electrode material and the antiferromagnetic film, and there is a problem with the reliability of the head. That is, in conventional electrodes made of Au or Cu, a reaction occurs between the antiferromagnetic film and the electrode material due to temperature rises during head manufacturing or during head operation, resulting in an increase in the resistance of the electrode portion. A phenomenon occurs in which the exchange bias magnetic field decreases. For this reason, there was a problem in that the head characteristics deteriorated. In addition, although the tungsten electrode is less likely to react with the antiferromagnetic film,
It required a layered structure, making the head manufacturing method complicated. The present invention aims to provide a magnetoresistive head that prevents reactions between electrodes and antiferromagnetic films, is easy to manufacture, and has high reliability.

[Means to solve the problem]

In order to achieve the above object, a material that reacts with the antiferromagnetic film, has excellent corrosion resistance and adhesion to the base, and has low resistivity is required. Nb is a material that satisfies these requirements.
A material containing as the main element was used for the electrode.

[Effect]

Fe-Mn alloy is known as an antiferromagnetic film suitable for magnetic domain control. Nb hardly diffuses with the Fe-Mn alloy, and almost no reaction occurs at temperatures below 350°C. Therefore, even if the temperature rises during the head manufacturing process or during head operation, a reaction layer will not be formed at the interface. Therefore, no increase in electrical resistance or decrease in bias magnetic field occurs, and no deterioration of head characteristics is observed. Furthermore, in terms of corrosion resistance, Nb has the same resistance as Ni--Fe under normal usage conditions, so long-term reliability can be ensured also from the viewpoint of corrosion resistance.

【Example】

[Example 1] FIG. 1 shows a first example of the present invention. This figure shows a cross section of a magnetoresistive thin film head. A magnetoresistive element 2 is formed on a substrate 1, and an antiferromagnetic film 3 is formed on both ends thereof. The electrode 4 is formed to cover the antiferromagnetic film. In this way, the antiferromagnetic film 3 and the electrode 4 are formed in contact with each other. In order to operate as a head, a magnetic shield layer sandwiching the magnetoresistive element and a bias magnetic field applying means are required, but these are omitted here. A Ni-Fe alloy with a thickness of 35 nm was used for the magnetoresistive film, and a Fe-Mn alloy with a thickness of 30 nm was used for the antiferromagnetic film. A Nb film with a thickness of 150 nm was used for the electrode. Thereafter, a magnetic shield made of a Ni-Fe alloy is laminated via an insulating layer. At this time, in order for the magnetic shield layer to obtain good magnetic properties, it is necessary to form the film at a temperature of about 300°C. Nb film must be heated to 350 degrees
-M Since it did not react with the n alloy, no increase in electrical resistance or decrease in exchange coupling magnetic field occurred. Furthermore, when a current with a current density of 6 x 10'A/cm2 was passed through the head element and the life of the current was investigated, no change occurred in the head characteristics even after 5 x 10'' hours.In this way, at about 300℃ By using Nb as the electrode in contact with the Fe-Mn antiferromagnetic film, the antiferromagnetic film and the electrode do not react and the magnetoresistive effect is maintained without deterioration of characteristics even in high-temperature process steps and high current density life tests. A mold head was obtained.Although this example shows the case where a Nb film body was used as an electrode, it is also possible to combine a low resistivity material such as Au on the Nb film. In this case, there is an effect that the resistance of the electrode can be lowered.Furthermore, in this embodiment, the electrode is formed inside the antiferromagnetic film, and the position of the magnetically sensitive part and the antiferromagnetic film are separated. Therefore, there is almost no decrease in the sensitivity of the magnetically sensitive part due to exchange coupling with the antiferromagnetic film, and there is also the effect that no decrease in reproduction output occurs.In the above embodiment, regarding the bias method of the magnetoresistive film, Although not specifically described, as is conventionally known, a soft bias method or a permanent magnet bias method in which a soft magnetic film or a permanent magnet film is provided adjacent to a magnetoresistive film and a bias magnetic field is applied is used. It is also possible to use the barber pole method in which the boundaries of the electrodes are made oblique so that the direction of current flow and the direction of magnetization are at an angle. [Example 2] Fig. 2 shows the second embodiment of the present invention. The stacking order, film thickness, and material of the a-resistance film, antiferromagnetic film, and electrode are the same as in the first example, but the positions of the electrode 4 and the antiferromagnetic film 3 are different. In this example, where the antiferromagnetic film is formed inside the electrode, as in Example 1, no reaction occurs between the Fe-Mn film and the Nb electrode during the process, so the characteristics No deterioration occurs.The part of the antiferromagnetic film that is not covered with the Nb electrode is in contact with the insulating film laminated thereon.
Since it does not react with iO, etc. at a temperature of about 300°C, a phenomenon such as a decrease in the exchange coupling magnetic field does not occur, and there is no deterioration of the characteristics. It's on the inside. Therefore, the magnetization change in the vicinity of the electrode is smaller than that in the center of the magnetically sensitive section, which reduces sensitivity at the track width boundary, making it less susceptible to noise from adjacent tracks. In this way, in this example,
By changing the positions of the electrode and the antiferromagnetic film, the sensitivity distribution in the track width direction can be changed. Further, in this embodiment as well, as in the first embodiment, any conventionally known method can be used as a biasing means. [Embodiment 3] FIG. 3 shows a third embodiment of the present invention. This embodiment shows a case where a shunt bias is used as a biasing method for the magnetoresistive head of the first embodiment. Substrate 1, magnetoresistive film 2, antiferromagnetic film 3, and electrode 4
The material, film thickness and forming method are the same as in Example 1. A shunt conductor 5 for shunt bias is formed on this. Nb with a thickness of 50 nm was used as the conductor. The head output varies depending on the shunting ratio of the current flowing through the shunt conductor and the magnetoresistive film. For this reason, it is necessary to accurately control each film thickness, specific resistance, and contact resistance between the two layers. Here, in order to control the contact resistance between the magnetoresistive film and the Nb film, it is effective to clean the surface of the magnetoresistive film by sputter etching or ion milling before depositing the Nb film layer for the shunt conductor. Ta. In this example, the shunt bias method using Nb was used for the conductor, and the same material as the electrode was used. Characteristic deterioration such as an increase in electrical resistance due to the reaction between the conductor and the electrodes does not occur. Furthermore, since Nb hardly reacts with Ni--Fe, there is an effect that the characteristics of the magnetically sensitive part do not deteriorate. In this embodiment, a case has been described in which a single layer of Nb is used as the shunt film, but a multilayer film in which Nb and a soft magnetic film, a Nb and a permanent magnet film, etc. are combined can also be used. In this case, in addition to the shunt bias by the Nb film, a soft bias and permanent magnet bias by a soft magnetic film or a permanent magnet are added. Therefore, the thickness of the Nb shunt film can be made thinner to reduce the magnetic field caused by the shunt. As a result, the shunt ratio of the shunt membrane is reduced, so that the output can be improved. [Embodiment 4] FIG. 4 shows a fourth embodiment of the present invention, in which a shunt bias is used as a biasing method for the magnetoresistive head of Embodiment 2. Substrate 1, magnetoresistive film 2, antiferromagnetic film 3, and electrode 4
The material, film thickness and forming method are the same as in Example 1. A shunt conductor 5 for shunt bias is formed on this. Nb with a thickness of 50 nm was used as the conductor. In this embodiment, the portions of the antiferromagnetic film that are not covered by the electrodes are also covered with the shunt film, so that no change in the characteristics of the antiferromagnetic film occurs. In the above embodiments, only Ni--Fe is used as the magnetoresistive film, but Co can also be used. N1-Fe added with Rh and Ru is also less likely to react with the Nb electrode and has the same effect. In this case, when 5 to 20% of these elements were added to Ni-Fe, the rate of change in magnetoresistance increased by several percent to several tens of percent, making it possible to improve the output. It has been found that the addition amount is more preferably in the range of 8 to 15%. Moreover, only the case of Fe-Mn is shown as a single antiferromagnetic film, but G e -Mn, Co-Nd
Even if N is used, there is a bias effect, and these materials and N
No change in properties due to the reaction with b was observed, and similar effects were obtained. In addition, F e −M used as an antiferromagnetic film
N alloy, G e -M n alloy, Co-Nd alloy
i, Co, Rh, Ru, Pt, Zr, Ti. Even when additive elements such as Nb and Cu are added, no significant decrease in the bias magnetic field is observed, and the bias magnetic field can be changed to approximately the same level. In this case as well, a reaction with the Nb film was less likely to occur, and the same effect of improving reliability was obtained. In this case, it was confirmed that the corrosion resistance of the antiferromagnetic film was improved by the additive elements, and that it had sufficient corrosion resistance under normal usage conditions. In particular, it is preferable to add 5% or more to improve corrosion resistance.
In addition, from the perspective of preventing a decrease in the bias magnetic field, it is 20%
It was preferable to do the following.

【Effect of the invention】

As mentioned above, by using a material containing Nb as the main element for the electrode connected to the antiferromagnetic film,
Since the properties of the antiferromagnetic film and electrodes do not deteriorate, a highly reliable magnetic head can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an MR element showing a first embodiment. FIG. 2 is a cross-sectional view of an MR element showing a second embodiment. FIG. 3 is a sectional view of an MR element showing a third embodiment. FIG. 4 is a cross-sectional view of an MR element showing a fourth embodiment. Explanation of symbols 1, ... Substrate 2, ... Magnetoresistive film 3, ... Antiferromagnetic film 4, ... Electrode 5, ... ...Shunt conductor
A-'4/ Figure No. 1.1 Pus 222. Low exhaust resistance (stiff φ...electrode year 2 figure

Claims (1)

[Claims] 1. An antiferromagnetic film for controlling the magnetic domain structure is connected to the magnetoresistive film, and a lead made of Nb containing unavoidable impurities in the magnetoresistive film and the antiferromagnetic film. A magnetic head characterized by connected wires. 2. The antiferromagnetic film and the lead wire are formed at both ends of the magnetoresistive film, and part or all of the antiferromagnetic film in contact with the magnetoresistive film is covered with the lead wire. A magnetic head according to claim 1. 3. The bias conductor film is formed in contact with the magnetoresistive film, and the magnetoresistive film and the bias conductor film are in contact with each other in a portion not covered with the lead wire or the antiferromagnetic film. A magnetic head according to claim 2, characterized in that: 4. Nb in which the bias conductor layer contains unavoidable impurities
A magnetic head according to claim 3, characterized in that the magnetic head comprises: 5. The magnetic head according to claim 1, 2, 3, or 4, wherein the magnetoresistive film is made of a Ni-Fe alloy. 6. Claims 1, 2, 3, or 4, characterized in that the magnetoresistive film is made of a Ni-Fe-M alloy, and M is made of Co, Rh, or Ru. The magnetic head described. 7. The antiferromagnetic film is Fe-Mn, Ge-Mn, Co-
A magnetic head according to claims 1, 2, 3, and 4, characterized in that the magnetic head is made of Nd. 8. The antiferromagnetic film is made of Fe-Mn+X alloy,
is Ni, Co, Rh, Ru, Pt, Zr, Ti, Nb,
A magnetic head according to claim 1, 2, 3, or 4, characterized in that the magnetic head is made of Cu. 9. The antiferromagnetic film is Co-Nd+X alloy or Ge-
Consisting of Mn+X alloy, where X is Ni, Co, Rh, Ru,
A magnetic head according to claim 1, 2, 3, or 4, characterized in that the magnetic head is made of Pt, Zr, Ti, Nb, or Cu.