JP2999154B2 - Magnetoresistive head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Broadly, AMR heads and Spi
With respect to a magnetoresistive read head typified by an n-Valve head, it is for ensuring linear response of the magnetoresistive effect and suppressing Barkhausen noise. The present invention relates to a magnetoresistive head for improving and effectively applying a bias by an exchange coupling magnetic field.

[0002]

2. Description of the Related Art Conventional magnetoresistive read heads (MR heads) include an AMR (Anisotropic Magnetoresistance) head using an anisotropic magnetoresistance effect phenomenon and a GMR (Gian) using a spin scattering phenomenon of conduction electrons.
t Magnetoresistance) head, and one of the GMR heads that exhibits a high magnetoresistance effect under a low external magnetic field.
A Valve head is shown in U.S. Pat. No. 5,159,513.

FIGS. 1 and 2 are schematic views of an AMR head element structure. For optimal operation of AMR head, AMR
Two bias fields are required for the ferromagnetic layer 3 (AMR material) to be effective. One bias magnetic field is A
This is to make the resistance change of the MR material linearly respond to the magnetic flux from the magnetic medium, and this bias magnetic field is perpendicular to the plane of the magnetic medium (the Z direction in the figure), and is relative to the film plane of the AMR material. Parallel. Usually, this bias magnetic field is called a lateral bias, and is obtained by arranging a soft magnetic material 1 formed via an electrical insulating layer 2 near an AMR material and flowing a detection current from the conductive layer 5 to the MR element. Can be.

Another bias magnetic field is usually called a longitudinal bias magnetic field, and is applied in parallel (in the X direction in the figure) to the magnetic medium and the film surface of the AMR material 3. The purpose of the longitudinal bias magnetic field is to suppress Barkhausen noise caused by the AMR material 3 forming a large number of magnetic domains, that is, a noise-free smooth magnetic field from the magnetic medium.
This is to make the resistance change smaller.

In order to suppress Barkhausen noise, it is necessary to form the AMR material 3 into a single magnetic domain. There are two methods for applying a longitudinal bias. One is A
A method of arranging the magnets 6 on both sides of the MR material 3 and using a leakage magnetic flux from the magnets 6 and a method of utilizing an exchange anisotropic magnetic field generated at a contact interface with the antiferromagnetic layer 4 It is.

On the other hand, as shown in FIGS.
For an optimum operation of the Valve head, in a sandwich structure of the free magnetic layer 7 / non-magnetic intermediate layer 8 / pinned magnetic layer 9, a bias in the track direction (X direction in the drawing) is applied to the free magnetic layer 7 simply. The magnetization is directed in the track direction in a state where the magnetic domain is formed, and the magnetization direction of the pinned magnetic layer 9 is the Z direction in the drawing, that is, the Free magnetic layer 7
It is necessary to apply a bias in the direction perpendicular to the magnetization direction of the magnetic field and make it oriented in the Z direction in FIG. The magnetization direction of the pinned magnetic layer 9 must not be changed by the magnetic flux from the magnetic medium (the Z direction in the figure), and the direction of the free magnetic layer 7 is 9 degrees with respect to the magnetization direction of the pinned magnetic layer 9.
By changing within the range of 0 ± θ degrees, a linear response of the magnetoresistance effect can be obtained.

The magnetization direction of the pinned magnetic layer 9 is indicated by Z in FIG.
A relatively large bias magnetic field is required to fix in the direction, and the larger the bias magnetic field, the better. In order to overcome the demagnetizing field in the Z direction in the figure and prevent the magnetization direction from fluctuating due to the magnetic flux from the magnetic medium, a bias magnetic field of at least 1000e is required.

As a method for obtaining the bias magnetic field, there is a method utilizing an exchange anisotropic magnetic field generated by bringing the diamagnetic layer 10 into contact with the pinned magnetic layer 9.

The bias applied to the free magnetic layer 7 is to ensure linear response and to suppress Barkhausen noise caused by forming a large number of magnetic domains. That is, the magnets 11 are arranged on both sides of the free magnetic layer 7 and the magnets 11
A method using a magnetic flux leaking from the magnetic field and a method using an exchange anisotropic magnetic field generated at a contact interface with the antiferromagnetic layer 13 are usually used.

As described above, the exchange anisotropic magnetic field generated at the contact interface with the antiferromagnetic film is used for the longitudinal bias of the AMR head, the bias of the Pinned magnetic layer and the bias of the Free magnetic layer of the Spin-Valve head. Thus, a magnetoresistive head having good linear response and suppressing Barkhausen noise can be realized.

The exchange anisotropic magnetic field is a phenomenon caused by an exchange interaction between two magnetic moments at a contact interface between a ferromagnetic film and an antiferromagnetic film.
As an antiferromagnetic film that generates an exchange anisotropic magnetic field with the film, Fe
Mn films are well known. However, the FeMn film has remarkably poor corrosion resistance, and has a problem that corrosion occurs during the magnetic head manufacturing process and the operation of the magnetic head, and the exchange anisotropic magnetic field is greatly deteriorated, and a magnetic medium is damaged. It is known that the temperature near the FeMn film during the operation of the magnetic head rises to about 120 ° C. due to heat generated by the detection current, but the exchange anisotropic magnetic field due to the FeMn film is sensitive to temperature change, The exchange anisotropic magnetic field decreases almost linearly with the temperature until disappearance (blocking temperature: Tb) at a temperature of about 150 ° C., so that a stable exchange anisotropic magnetic field cannot be obtained. .

As an invention in which the corrosion resistance and the blocking temperature of the FeMn film are improved, there is, for example, a NiMn alloy or a NiMnCr alloy having a face-centered tetragonal structure disclosed in JP-A-6-76247. Although better than the corrosion resistance of the film, it is not practically sufficient. The NiMnCr film is an alloy to which Cr is added in order to improve the corrosion resistance of the NiMn film. However, although the corrosion resistance is improved by adding Cr, there is a problem that the magnitude of the exchange anisotropic magnetic field and the blocking temperature decrease.

In order to obtain an exchange anisotropic magnetic field in a NiMn alloy or a NiMnCr alloy, CuAg-I having a face-centered tetragonal (fct) structure in a part of the antiferromagnetic film is used.
In order to obtain stable characteristics, it is necessary to control the ordered-disorder transformation and to control the volume ratio of the ordered phase and the disordered phase. The process control and management in must be very complicated. In addition, in order to obtain the required exchange anisotropic magnetic field, heat treatment in a magnetic field must be repeated a plurality of times, and the rate of temperature decrease must be slow, for example, from 255 ° C to 4 ° C.
Up to 5 ° C., 17 HR (Appl. Phys. Lett.
65 (9), 29 August 1994) is another problem in the manufacturing process.

Further, as an invention for improving the blocking temperature of the FeMn film, the NiFe / FeMn laminated film is formed at 260 ° C.
A heat treatment of 20 HR to 50 HR is performed at a temperature of 〜350 ° C., and Ni is added to the NiFe / FeMn interface by diffusion by the heat treatment.
A method for forming a Fe-Mn ternary alloy layer is disclosed in U.S. Pat.
No. 809109, it can be easily understood that it is not effective in improving the corrosion resistance, which is the biggest problem of the FeMn film, and the required heat treatment time is 20 HR or less.
A very long 50 HR poses a problem in the manufacturing process.

Further, existing publications such as “Magnetic Material Handbook” published by Asakura Shoten include Mn as an antiferromagnetic material.
Based alloys such as NiMn, PdMn, AuMn, PtM
Although materials such as n and RhMn3 are shown, there is no comment on the exchange anisotropic magnetic field at the contact interface with the ferromagnetic film, and furthermore, the antiferromagnetic film in an extremely thin film having a thickness of several hundred angstroms. Its properties and exchange anisotropic magnetic field are completely unknown.

[0016]

SUMMARY OF THE INVENTION A first object of the present invention is to provide an antiferromagnetic material film having excellent corrosion resistance and capable of applying a necessary and sufficient exchange anisotropic magnetic field in an extremely thin film. An object of the present invention is to provide a magnetoresistive head (MR head) having excellent responsiveness and suppressing Barkhausen noise.

A second object is to provide an MR head which has an excellent linear response and suppresses Barkhausen noise by slowing the temperature dependence of the exchange anisotropic magnetic field and providing an antiferromagnetic film having a high blocking temperature. It is to be.

A third object is to provide an antiferromagnetic film in which a heat treatment step for obtaining the above-described characteristics can be realized at a temperature, a time, and a temperature lowering rate used in a normal MR head manufacturing process. Another object of the present invention is to provide an MR head having excellent linear response and suppressing Barkhausen noise.

[0019]

SUMMARY OF THE INVENTION The present invention relates to a magnetoresistive read head, in which the magnetoresistive effect linearly responds to magnetic flux from a magnetic medium and suppresses Barkhausen noise. A bias magnetic field necessary and sufficient is applied by an antiferromagnetic film directly in contact with the body film, and the antiferromagnetic film is a PtMn alloy,
After forming a ferromagnetic film that is in direct contact with the PtMn antiferromagnetic film, a heat treatment is performed at a temperature of 200 ° C. to 350 ° C. at the interface between the PtMn antiferromagnetic film and the ferromagnetic film that directly contacts. It is characterized in that a predetermined interdiffusion layer is formed to generate an exchange anisotropic magnetic field.

This heat treatment can be achieved with the same temperature, holding time, and heating / cooling rate as the heat treatment performed in the normal magnetoresistive head manufacturing process, and is a very realistic heat treatment method.

The PtMn alloy is made of FeMn, NiMn,
Compared with NiMnCr alloy, it has extremely excellent corrosion resistance, does not progress at all in various solvents and cleaning agents in the manufacturing process of the magnetoresistive head, and is chemically resistant even in the operation of the magnetoresistive head in a severe environment. It is stable.

The exchange anisotropic magnetic field obtained by forming a predetermined interdiffusion layer at the interface between the PtMn antiferromagnetic film and the ferromagnetic film directly in contact with the PtMn antiferromagnetic film is the exchange anisotropy magnetic field produced by the FeMn antiferromagnetic film. It is extremely thermally stable compared to the magnetic field, and can exhibit a constant magnitude of the exchange anisotropic magnetic field in a temperature range from room temperature to 120 ° C., which is the operating temperature of the magnetoresistive head. It is characterized by being extremely stable within the operating temperature range. Furthermore, the temperature at which the exchange anisotropic magnetic field disappears is extremely high at 380 ° C. compared to 150 ° C. of the FeMn alloy. Extremely stable.

Further, the PtMn alloy can exhibit an exchange anisotropic magnetic field at either the upper or lower interface of the ferromagnetic film which is in direct contact with the PtMn alloy, and has the crystal orientation required for obtaining the exchange anisotropic magnetic field with FeMn. Since an exchange anisotropic magnetic field can be obtained without a base film to be adjusted, for example, a Ta film, an element structure which cannot be realized due to a limitation by a conventional method of using an antiferromagnetic film becomes possible.

Further, a ferromagnetic film and a PtMn antiferromagnetic film are formed by DC magnetron sputtering, and a large exchange anisotropic magnetic field is obtained by reducing the film thickness of the ferromagnetic film. In addition, the heat treatment temperature in the annealing step can be lowered to the temperature in the UV curing step and the hard baking step.

[0025]

5 to 22 show a first embodiment of the exchange anisotropic magnetic field obtained by the present invention. Pt
The exchange anisotropic magnetic field obtained by forming a predetermined interdiffusion layer at the interface between the Mn antiferromagnetic film and the ferromagnetic film directly in contact with the Mn antiferromagnetic film is a longitudinal bias in the AMR head shown in FIG.
The bias of the pinned magnetic layer 9 and the bias of the free magnetic layer 7 and the bias of the pinned magnetic layer 9 in FIG. 4 can be used in the pin-valve head.

The film was formed by RF (Radio Frequency) conventional sputtering. The substrate is indirectly water cooled and is not actively heated. 8 "φ size Ni80
Fe20, Co, Ta, Mn, Ni47Mn 53 atomic%
The PtMn film composition was adjusted by appropriately arranging 10 mm square Pt pellets on the Mn target. The film composition of the NiMnCr film is Ni47Mn53.
Adjustments were made by appropriately arranging 10 mm square Cr and Mn pellets on the target. The film composition is about 2 μm on the Si substrate.
Was formed and analyzed by XMA (X-ray microanalyzer). A glass substrate was used as a substrate for the magnetic property measurement and the corrosion resistance test. The sputtering power was 100 W and the sputtering gas pressure was 1 mTorr.
The obtained films were sequentially laminated one by one. During film formation, a pair of magnets arranged on both sides of the glass
A magnetic field in one direction 0e was applied.

The heat treatment was performed in a vacuum of 5 × 10 to ⁶ Torr or less, and a unidirectional magnetic field of about 1000 Oe was applied. The rate of temperature rise and fall of the heat treatment was such that the temperature rise from a predetermined temperature and the temperature fall from a predetermined temperature to room temperature were fixed at 3 hours. The predetermined temperature of the heat treatment was changed from 200 ° C. to 350 ° C., and the holding time at the predetermined temperature was in the range of 4 hours to 20 hours. P
The analysis of the interdiffusion at the interface directly contacting the tMn antiferromagnetic film and the NiFe ferromagnetic film was performed by the depth profile by the Auger electron beam analysis. The analysis of the film structure was performed by X-ray diffraction using a Co tube. The measurement of the exchange anisotropic magnetic field was determined from the amount of MH loop shift normally performed.

FIG. 5 shows that the film composition of the PtMn film was changed to a Pt content of 0-6.
The measured values of the exchange anisotropic magnetic field (Hex) after the heat treatment at 270 ° C. for 9 hours and the state immediately after film formation (as depo.) When changed to 0 atomic% (at%). The film configuration is Glass / Ta (100A) / NiFe (50A) /
PtMn (200A) / Ta (100A). A represents Angstroms.

The reason why Ta was formed on Glass was that
This is to prevent the components on the ass and the NiFe film from mutually diffusing due to the heat treatment. as depo. Hex occurs when the amount of Pt is in the range of 0 to 21 at% in the state of
Hex that can be substantially observed when the amount is 21 at% or more
Does not occur. However, after the heat treatment, the amount of Pt is 0-5.
Hex occurs over the entire composition range of 4 at%, particularly Pt
A composition having an amount of 36 to 54 at% is as depo. In this case, Hex not observed is generated by the heat treatment, and its value is also a large value exceeding 200 Oe. Pt
A composition having an amount of 0 to 21 at% is also available as as depo. The exchange anisotropic magnetic field after the heat treatment is larger than that after the heat treatment.

FIG. 6 shows a change in Hex when the heat treatment temperature is changed for a film having a Pt amount of 44 to 54 at%. Holding time at heat treatment temperature is 200 ° C, 230 °
C, 270 ° C for 9 hours, 250 ° C for 20 hours, 29
0 ° C., 330 ° C., and 350 ° C. are 4 hours, the temperature raising time to the heat treatment temperature is 3 hours, and the temperature lowering time is also 3 hours. Film composition is Glass / Ta (100A) / NiFe
(75A) / PtMn (200A) / Ta (100A)
It is. No substantial Hex is observed in the heat treatment at less than 200 ° C, but Hex begins to be observed in the heat treatment at 200 ° C or more, and Hex is rapidly generated by the heat treatment at a temperature of 230 ° C or more. 44-
The film of 51 at% shows a large value of 200 Oe or more.

FIGS. 7 and 8 show the results of a more detailed examination of the dependence of Hex and the coercive force (Hc) at that time on the heat treatment temperature and the holding time. The film configuration is Glass / Ta (100
A) / NiFe (50A) / PtMn (200A) / T
a (100 A), and the film composition of PtMn is Pt47M
n53 at%. Focusing on 250 ° C. and 270 ° C., it can be seen that the longer the holding time, the larger the value of Hex.

As can be seen from the comparison between 20 hours at 250 ° C., 9 hours at 270 ° C., and 4 hours at 290 ° C.
It can be seen that the higher the temperature, the higher the value of Hex, but the higher the high-temperature heat treatment with a shorter holding time, despite the shorter holding time.

Hc shows almost the same temperature-dependent tendency as Hex, and its value is almost the same as Hex. That is, the shape of the MH loop at this time is such that the center shifts by Hex in one direction of the H axis, and the coercive force has substantially the same magnitude as the shift amount. Considering exchange anisotropy bias in AMR or Spin-Valve, if Hex and Hc are both large, the bias amount is large and stable.
It is preferable that both x and Hc are large.

The exchange anisotropic magnetic field is a physical phenomenon originating from the exchange interaction between magnetic atoms at the interface between the ferromagnetic film and the antiferromagnetic film. The higher the temperature at that time, the higher the temperature.
Some physical change is given to the interface between the film and the PtMn film, suggesting that the physical change becomes larger as the temperature is higher and the holding time is longer. This physical change,
The mechanism will be described later in detail.

FIG. 9 shows the relationship between Hex and the heat treatment temperature when the thickness of the PtMn film is changed. Retention time is 200
° C, 230 ° C, 250 ° C for 9 hours, 270 ° C,
290 ° C. and 330 ° C. are 4 hours, and the temperature rise / fall time is 3 hours each. The film configuration is Glass / Ta (100
A) / NiFe (75A) / PtMn (XA) / Ta
(100A), and the film composition of PtMn is Pt49Mn.
It is 51 at%. When the film thickness of PtMn is 100, 200,
Hex increases as the thickness increases to 300 A, and the heat treatment temperature at which Hex starts to occur is also shifted to a lower temperature. FIG. 10, FIG. 11, and FIG. 12 show the results of a more detailed examination of the film thickness dependency.

The film configuration of FIG. 10 is Glass / Ta (10
0A) / NiFe (XA) / PtMn (300A) / T
a (100 A), and the film composition of PtMn is Pt49M
n51 at%, and a heat treatment temperature of 250 ° C., 270 ° C.
° C, 290 ° C, and 330 ° C.

The film configuration of FIG. 11 is Glass / Ta (10
0A) / NiFe (XA) / PtMn (200A) / T
a (100 A), and the film composition of PtMn is also PtMn.
49 Mn, 51 at%, and the same heat treatment as in FIG. 9 has been performed.

In the film structure shown in FIG. 12, the film thicknesses of PtMn and NiFe are simultaneously changed, and Glass / Ta (100
A) / NiFe (XA) / PtMn (XA) / Ta (1
00A), the film composition of PtMn is shown in FIGS.
As in the case of Pt49Mn51at%. Heat treatment is 29
The test was carried out at 0 ° C. for 4 hours. 9, 10, and 11, the heat-up / down time of the heat treatment is 3 hours.

The results of FIGS. 9, 10, 11 and 12 show that H
It can be seen that the size of ex increases as the thickness of NiFe decreases, and increases as the thickness of PtMn increases. Regarding the thickness of PtMn, the thickness dependency is remarkable in the range of 100A to 300A, but the thickness is 300A to 5A.
In the range of 00A, there is not much dependency on the film thickness (FIG. 1).
2). Therefore, it is understood that a film thickness of PtMn of 300 A is sufficient.

On the other hand, it can be seen that the film thickness of NiFe is substantially inversely proportional to Hex. This is because the exchange coupling energy due to the action of the exchange phase between the magnetic atoms at the interface between the PtMn film and the NiFe film is NiFe.
This shows that it does not depend on the film thickness.
This is the same as the film thickness dependence of the NiFe film in the n film / NiFe film.

Next, the result of examining the change in Hex when the ferromagnetic film is changed from NiFe to Co is shown. Spin-
It has been experimentally and theoretically shown that the use of a Co film for a Pinned magnetic layer of a Valve head can increase the magnetoresistance ratio compared to the use of a NiFe film. Co is used for a Pinned magnetic layer. Since the possibility is high, it is desired that the exchange anisotropic magnetic field with Co be large.

The film configuration of FIG. 13 is Glass / Ta (10
0A) / NiFe or Co (XA) / PtMn (20
0A) / Ta (100A), the film composition of PtMn is Pt49Mn51at%, the heat treatment is maintained at 290 ° C. for 4 hours, and the temperature rise and fall time is 3 hours each. Even when the ferromagnetic film was changed to Co, Hex almost equivalent to that of the NiFe film was obtained. From this result, it can be easily inferred that the same Hex can be obtained even when the NiFeCo ternary alloy film is used as the ferromagnetic film.

As described above, the exchange anisotropic magnetic field between the PtMn film and the ferromagnetic film depends on the film composition of the PtMn film, the heat treatment temperature, the heat treatment holding time, the PtMn film thickness,
The ferromagnetic film thickness dependence was examined in detail, and the thickness of the ferromagnetic film directly contacting the PtMn alloy was 50 to 300 A.
It has been shown that a large exchange anisotropic magnetic field can be obtained by performing a heat treatment at 200 ° C. to 350 ° C. on an ultrathin film.

Next, the thermal stability of the exchange anisotropic magnetic field and the high corrosion resistance of the antiferromagnetic PtMn film, particularly NiMn, NiMnCr, which are other objects to be solved by the present invention.
Examples will be described with respect to comparison of corrosion resistance with the film. Finally, examples will be given regarding the differences and similarities in the mechanism between the exchange anisotropic magnetic field obtained by the NiMn and NiMnCr antiferromagnetic films and the exchange anisotropic magnetic field obtained by the PtMn antiferromagnetic film. .

FIG. 14 shows the result of examining the temperature characteristics of Hex and Hc. The film configuration is Glass / Ta (100A) /
NiFe (200A) / PtMn (300A) / Ta
(100A), and the film composition of PtMn is Pt46Mn.
At 54at%, heat treatment is maintained at 260 ° C for 20 hours,
The temperature rise and fall time is a sample of 3 hours each. The measurement was performed using a vibrating magnetometer (VSM) with a degree of vacuum of 5 × 10 to ⁵ Torr.
While gradually heating the sample from room temperature under the following conditions,
The -H curve was measured. The temperature rise rate during measurement was 20 ° C /
20 minutes.

Hex at room temperature is 90 Oe, which is about 1.5 times the Hex of the conventional FeMn film. The temperature at which Hex disappears (Tb: blocking temperature) is 380 ° C., and Tb of the FeMn film is 160.
It is much higher than ° C. It is known that the temperature around the magnetoresistive film when the magnetic head is operating ranges from room temperature to about 120 ° C., but in this temperature range, Hex of the PtMn film has a substantially flat value. It is clearly different from the tendency that Hex of the FeMn film decreases with temperature in the temperature range from room temperature to 120 ° C. It is very preferable that Hex and Tb are large and the value of Hex is flat in the operating temperature range of the magnetoresistive head because it leads to thermal stability of the bias magnetic field. I have.

Now, all the film configurations of the above-described embodiments are Gl
ass / Ta / ferromagnetic film (NiFe or Co) / P
An example in which the order of forming the ferromagnetic film and the PtMn film was exchanged and the case where the Ta underlayer was eliminated was described below.

FIG. 15 shows Glass / Ta / NiFe / P
tMn, Glass / NiFe / PtMn / Ta, Gl
ass / Ta / PtMn / NiFe / Ta, Glass
4 is a comparison of Hex in four film configurations of / PtMn / NiFe / Ta. The uppermost layer Ta is provided to prevent surface oxidation during the heat treatment, and does not affect the stacking order dependence of Hex. NiFe film thickness is 20
0, 300, and 400 A, and the PtMn film is 300 A. The film composition of PtMn is Pt49Mn51
at%, heat treatment is maintained at 270 ° C. for 9 hours, and temperature rise and fall times are each 3 hours.

Although the value of Hex varies slightly depending on the stacking order, a good value of H is obtained in all the stacking orders.
ex has been obtained. In conventional FeMn, the formation of the γ-FeMn phase, which is an antiferromagnetic phase, leads to the development of an exchange anisotropic magnetic field, and a large difference appears in Hex depending on the crystal orientation and the presence or absence of a base Ta film for adjusting the crystal phase. It is known. That is, in the case of the FeMn film, Hex cannot be obtained unless a film for adjusting the lattice constant is provided on the base, and Hex cannot be obtained if the FeMn film is formed first and then the NiFe film is formed. Although the element structure was restricted by this restriction, it is understood that Hex using a PtMn film is very easy to use because there is no such restriction, and that it is a film that can enable an element structure that was impossible in the past. .

FIG. 16 shows an experimental result when the PtMn film is replaced with the NiMn film under the same film configuration, film thickness and heat treatment conditions as those of FIG. The film composition of NiMn is Ni
49 Mn 51 at%. The characteristic of the NiMn film is that the dependency of Hex on the stacking order is higher than that of the PtMn film by FeMn.
It is similar to a film, that is, a large difference appears in Hex depending on the presence or absence of the base Ta. These facts suggest that the mechanism of generating the exchange anisotropic magnetic field is slightly different between the NiMn film and the PtMn film.

Next, a description will be given of an embodiment supporting the consideration of the reason why the exchange anisotropic magnetic field is greatly different depending on the presence or absence of the heat treatment by performing an appropriate heat treatment at the interface between the PtMn film and the ferromagnetic film directly in contact with the PtMn film. . Several factors are presumed as to the reason, one of which is the formation of a PtMn ordered phase (CuAu-I type) already known in existing publications such as “Magnetic Handbook”. It is considered that the change in the interface state where the exchange anisotropic magnetic field acts, that is, the formation of an interdiffusion layer at the interface between the PtMn film and the ferromagnetic film.

FIGS. 20 and 21 show the interdiffusion state before and after the heat treatment by Auger electron spectroscopy depth profile (AES).
This is the result of an investigation. as depo. Is composed of Glass / Al-O (alumina) (100A) / Ta
(80A) / NiFe (200A) / PtMn (200
A) / Ta (80A), and the film composition of PtMn is PtMn.
The heat treatment is carried out at 290 ° C. for 4 hours at 47 Mn at 53 at%. As depo. In FIG. Although no apparent diffusion higher than the resolution of AES was observed in the sample in the state, the PtMn film and the N
Clear interdiffusion is observed at the interface with the iFe film. That is, Pt and Mn of PtMn diffuse in particular to the NiFe film side, and Ni and Fe of the NiFe film diffuse to the PtMn side. The diffusion distance is about 100 A or less when estimated from the film thickness of 200 A.

Considering that the exchange anisotropic magnetic field is physically originated from the exchange interaction between both magnetic atoms at the interface between the antiferromagnetic film and the ferromagnetic film, the mutual diffusion layer formed by the heat treatment is formed. Is the region where the exchange interaction between the two magnetic atoms works, and the exchange anisotropic magnetic field between the PtMn antiferromagnetic film and the NiFe ferromagnetic film works via the interdiffusion layer. In a NiFe film directly in contact with a PtMn film, an exchange anisotropic magnetic field is generated by performing a heat treatment at 200 ° C. to 350 ° C. In particular, the higher the heat treatment temperature and the longer the heat treatment holding time, the larger the exchange anisotropic magnetic field. One reason for this is that the higher the heat treatment temperature and the longer the heat treatment time, the easier it is to form an interdiffusion layer.

However, mutual diffusion progresses further, and P
When the tMn film and the NiFe film are completely diffused, PtMnN
Since it is certain from the mechanism of exchange interaction that an exchange anisotropic magnetic field cannot be obtained after forming an iFe quaternary alloy, it must be appropriately formed between the PtMn layer and the NiFe layer.

Regarding the appearance of the exchange anisotropic magnetic field, as described above, the change in the crystal structure, that is, the PtMn ordered phase (CuAu-
Since the formation of (I type) is also conceivable, the change in the crystal structure before and after the heat treatment was examined by X-ray diffraction.

FIG. 22 shows an X-ray diffraction profile. The film configuration is Glass / Ta (100A) / NiFe (20
0A) / PtMn (200A) / Ta (100A), the film composition of PtMn is Pt47Mn53at%, and the heat treatment is kept at 290 ° C. for 4 hours. The measurement was performed by a θ-2θ method using a Co tube.

As depo. And the difference after heat treatment is f
Similar to the PtMn {111} peak of the cc structure, the peak intensity of the NiMn {111} peak of the fcc structure is only slightly changed due to the change of the lattice constant, and the PtMn ordered phase showing the fct structure can be seen from these results. (C
uAu-I type) cannot be determined.

Next, the experimental results regarding the improvement of corrosion resistance, which is another major object of the present invention, will be described.

FIG. 18 shows that a PtMn, Ni
It is a result of examining the amount of corrosion of a sample in which a Mn and NiMnCr film each having a thickness of 300 A were immersed in physiological saline and an emulsifier at room temperature for 24 hours. The film composition is PtM
The n film is Pt47Mn53at%, and the NiMn film is Ni47.
Mn 53 at%, Cr added amount is 5, 9, 13, 17 at
%. The concentration of NaCl in saline is 0.9%,
The emulsifier is used in various cleaning processes in the magnetic head manufacturing process, is a solution containing sodium tripolyphosphate, and is weakly alkaline. The amount of corrosion (%) was determined by measuring the area where the film was dissolved in the solution and the glass substrate was exposed, using an optical microscope. The sample area is 4 cm ² .

The PtMn film did not corrode at all in both the physiological saline and the emulsifier, but NiMn was in 10% in both solutions.
Corrosion in which the 0% glass substrate was exposed proceeded. NiM
The addition of Cr to n did reduce the amount of corrosion in saline, but had little effect on emulsifiers. PtMn film is NiMn, NiMnCr
It can be seen that the corrosion resistance is much better than the film. FIG. 17 shows the result of examining the exchange anisotropic magnetic field in the film composition of which corrosion resistance was examined.

The film configuration of FIG. 17 is Glass / Ta (10
0A) / NiFe (50 or 75A) / PtMn or NiMn or NiMnCr (200A) / Ta (1
00A), and the heat treatment is maintained at 270 ° C. for 9 hours. Hex of the PtMn film, the NiMn film and the NiMnCr film to which 5% and 9% of Cr were added showed good values.
Hex increases as the amount of added r increases to 13% and 17%.
Is expected to decrease and become a practical problem. Based on the above results, PtMn was observed in both the corrosion resistance of the film and Hex.
It can be seen that the film is excellent.

Finally, the result of examining the effect of the improvement in corrosion resistance given by the amount of Pt in the PtMn film is shown.

FIG. 19 shows a film composition sample similar to FIG.
It is the result of performing the same corrosion resistance test on the solution. P
It can be easily understood that the element improving the corrosion resistance of the tMn film is Pt, and it can be seen that the corrosion resistance is remarkably improved particularly when the Pt content is 44 at% or more.

[0064]

Next, in addition to the above-described first embodiment, an additional second embodiment focusing on the heat treatment temperature and the thickness of the ferromagnetic layer will be described in detail.

FIG. 23 is a diagram showing the relationship among the exchange anisotropic magnetic field of the PtMn film formed by DC magnetron sputtering, the thickness of the NiFe film, and the heat treatment temperature. FIG.
FIG. 3 is a diagram showing a relationship among an exchange anisotropic magnetic field, a heat treatment temperature, a type of a ferromagnetic layer, and a film thickness of a PtMn film formed by magnetron sputtering. FIG. 25 is a diagram showing the relationship between the blocking temperature, the type of ferromagnetic layer, and the thickness of a PtMn film formed by DC magnetron sputtering. FIG.
FIG. 6 is a diagram illustrating experimental conditions for obtaining an exchange coupling magnetic field required for the magnetoresistive heads according to the first and second embodiments.

The antiferromagnetic film for generating a sufficient and sufficient exchange anisotropic magnetic field for a magnetoresistive head (MR head) includes:
There are materials that require an annealing step (heat treatment step) after the formation of a multilayer film such as a NiFe layer and a PtMn layer, and materials that do not require the same. For example, as shown in FIG. As the magnetic film, Mn-X (X = platinum group 10 to 30 at%) exists. Other antiferromagnetic films that do not require annealing include FeMn and Cr.
-Mn-X (X = platinum group 0 to 20 at%) and NiO (nickel oxide) are present.

The annealing step for performing the treatment at a high temperature is performed by using the MR
The non-magnetic layer (for example, the Cu layer of the non-magnetic intermediate layer 8 shown in FIG. 4) in the head, particularly the spin valve type MR head, is diffused into adjacent upper and lower layers, thereby deteriorating the magnetic reproducing characteristics of the MR head. There is a risk of causing For this reason,
When the material of the antiferromagnetic film requiring the annealing step is used, there is an adverse effect of the above-described diffusion of the Cu layer, and this is disadvantageous in comparison with the antiferromagnetic film not requiring the annealing step. Pt 36-54M in the first embodiment of the present invention
The disadvantage of the diffusion of the Cu layer also existed in the PtMn film of n 46 to 94 atomic%. However, the intensity of the generated exchange anisotropic magnetic field is not discussed in this case.

By the way, in the manufacturing process of the MR head, a known UV curing process (ultraviolet curing process) and a hard baking process are essential manufacturing processes, and in these processes, heating is performed to a temperature of about 250 ° C. Therefore, even if a diamagnetic material that does not require an annealing step is used, the magnetic reproducing characteristics of the MR head deteriorate in this step due to the heating temperature of 250 ° C.
Conversely, when using a diamagnetic material that requires an annealing step, if the annealing temperature can be suppressed to 250 ° C. or less, it should be within the minimum required damage range in the UV curing step and the hard baking step. Can be
As a result, it is possible to achieve damage equivalent to that of an antiferromagnetic film that does not require an annealing step.

In the second embodiment of the present invention, in order to form an antiferromagnetic film requiring an annealing step, a DC magnetron sputtering method is adopted instead of RF conventional sputtering, and the thickness of the ferromagnetic film is Is formed to be thin, thereby obtaining a stronger exchange anisotropic magnetic field and further reducing the heat treatment temperature in the annealing step by 2
The temperature can be set to, for example, 210 ° C. which is 50 ° C. or less.

FIG. 26 shows the experimental conditions for obtaining the data of the second embodiment of the present invention, together with the experimental conditions of the first embodiment. Here, Pt48Mn52 (a typical composition example as shown in FIGS. 5 and 6) was used as an antiferromagnetic film requiring an annealing step, and other conditions were substantially the same as in the first embodiment. A DC magnetron sputtering method was employed as a film forming method.

According to FIG. 23, a DC magnetron sputtering method was used, NiFe was used as the ferromagnetic film, Pt48Mn52 was used as the antiferromagnetic film, and the NiFe film thickness was 200.
The strength of the exchange anisotropic magnetic field when the thickness was reduced from about Å to about 15 Å was determined.
° C, 210 ° C, 190 ° C, as depo. , And as parameters. Although the NiFe film thickness actually measured in FIGS. 10 and 11 was up to 50 Å, an experiment was performed to a thickness of 15 Å or less.

As a result, the intensity of the exchange anisotropic magnetic field of 360 Oe shown in FIG. 8 increased to 750 Oe. According to this experimental result, a stronger exchange anisotropic magnetic field can be obtained as the thickness of NiFe becomes thinner. However, the thinness of 5 Å makes it possible to form a uniform NiFe film on the underlying film and to obtain an exchange anisotropic magnetic field. This is a limit value at which an ionic magnetic field can be obtained, and if the thickness is less than this, there is a risk that pinholes (pores) are generated in the film, so that the thickness cannot be reduced to 5 Å or less.

Therefore, considering the strength of the exchange anisotropic magnetic field, the thickness of NiFe is generally preferably 15 to 100 Å, and the strongest anisotropic magnetic field is obtained with the thickness of 15 to 30 Å. (Assuming the adoption of the DC magnetron sputtering method). Furthermore, the higher the heat treatment temperature in the annealing step, the higher the strength of the exchange anisotropic magnetic field. However, even if the temperature is lowered to about 210 ° C., the strength of the exchange anisotropic magnetic field does not decrease so much. I also understood.

According to FIG. 24, the type of the ferromagnetic film and the
e40 angstroms, Co40 angstroms,
NiFe 200 angstroms and Co 200 angstroms were used.
This is an actual measurement of the intensity of the exchange anisotropic magnetic field when t48Mn52 is employed.

According to this, the difference in the type of ferromagnetic film (N
(Difference between iFe and Co) (NiF as ferromagnetic film)
(e and Co can obtain almost the same exchange anisotropic magnetic field.) The difference in the film thickness affects the strength of the exchange anisotropic magnetic field. The thinner the film, the stronger the exchange anisotropic magnetic field can be obtained. Further, the temperature is lower than 250 ° C. in the UV curing step and the hard baking step described above.
It can be seen that an exchange anisotropic magnetic field can be obtained from 0 ° C.

Further, according to FIG. 24, the strength of the exchange anisotropic magnetic field when the heat treatment temperature in the annealing step is variously changed is determined. A peak tendency of the magnetic field strength appears. This is shown in FIG.
The tendency of the increase in the magnetic field at 250 ° C. in the first embodiment shown in FIG. 1 shows a clear difference in the tendency, and the annealing temperature exceeding 250 ° C. in the UV curing step and the hard baking step described above. It indicates that there is no need.

In other words, according to the first embodiment of FIG. 6, increasing the heat treatment temperature in the annealing step to 350 ° C. can increase the exchange anisotropic magnetic field. If the temperature is increased up to 350 ° C., the Cu
The disadvantage is that the reproduction characteristics deteriorate due to layer diffusion.

On the other hand, other steps for manufacturing the MR head (U
250 in the V cure and hard bake steps)
Since a heating temperature of ° C is required, it would be desirable if the annealing step could be appropriately performed at a temperature within this 250 ° C. According to the second embodiment of FIG.
Since the intensity of the exchange anisotropic magnetic field tends to peak at 250 ° C., there is an effect that it is not necessary to increase the heat treatment temperature to 250 ° C. or higher (assuming the use of DC magnetron sputtering).

FIG. 25 shows the blocking temperature of a PtMn laminated film formed by DC magnetron sputtering in relation to the type of ferromagnetic film and its film thickness. However, it also shows a high blocking temperature of about 380 ° C. Also, NiFe
In comparison with Co and Co, NiFe can obtain a stronger exchange anisotropic magnetic field in the temperature range of 20 ° C. to 320 ° C., and in this regard, NiFe is more preferable.

[0081]

According to the present invention, there is provided a material having a large exchange anisotropic magnetic field, good temperature characteristics of the exchange anisotropic magnetic field, and very excellent corrosion resistance. It is possible to provide a magnetoresistive read head that is excellent in linear response of a magnetoresistive effect by a bias magnetic field using a magnetic field and can suppress Barkhausen noise.

According to the second embodiment of the present invention, an antiferromagnetic layer P formed by DC magnetron sputtering is used.
By using a tMn film and forming a thin ferromagnetic layer, a stronger exchange anisotropic magnetic field can be obtained, the heat treatment temperature in the annealing step can be reduced, and the blocking temperature is relatively high, and the corrosion resistance is excellent. An antiferromagnetic film can be provided.

Further, by using a PtMn film which is an antiferromagnetic layer formed by a DC magnetron sputtering method and forming a thin ferromagnetic layer, a UV curing step and a hard baking step (an essential step for manufacturing an MR head) Since the peak value of the exchange anisotropic magnetic field can be obtained at the heat treatment temperature of the annealing step at around 250 ° C. in the case of), the reproduction characteristic is deteriorated in the same manner as when the antiferromagnetic material which does not require annealing is used. Can be suppressed.

Further, conventionally, when the ferromagnetic layer was formed thinly, the blocking temperature tended to decrease. However, Pt, which is an antiferromagnetic layer formed by a DC magnetron sputtering method, was used.
By using the Mn film, a large blocking temperature can be ensured even if the ferromagnetic layer is formed thin.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a bias magnetic field in an AMR head.

FIG. 2 is an explanatory diagram of a bias magnetic field in an AMR head.

FIG. 3 is an explanatory diagram of a bias magnetic field in a Spin-Valve head.

FIG. 4 is an explanatory diagram of a bias magnetic field in a Spin-Valve head.

FIG. 5 is a diagram showing a relationship between a film composition of a PtMn film and an exchange anisotropic magnetic field.

FIG. 6 is a diagram showing a relationship between a film composition of a PtMn film, a heat treatment temperature, and an exchange anisotropic magnetic field.

FIG. 7 is a diagram showing a relationship between a heat treatment temperature and a holding time of a PtMn film and an exchange anisotropic magnetic field.

FIG. 8 is a diagram showing a relationship between a heat treatment temperature, a holding time, and a coercive force of a PtMn film.

FIG. 9 is a diagram showing the relationship between the thickness of a PtMn film, a heat treatment temperature, and an exchange anisotropic magnetic field.

FIG. 10 is a diagram showing the relationship between the thickness of a NiFe film, a heat treatment temperature, a holding time, and an exchange anisotropic magnetic field.

FIG. 11 is a diagram showing the relationship between the thickness of a NiFe film, a heat treatment temperature, a holding time, and an exchange anisotropic magnetic field.

FIG. 12 is a diagram showing a relationship among a PtMn film thickness, a NiFe film thickness, a heat treatment temperature, a holding time, and an exchange anisotropic magnetic field.

FIG. 13 is a diagram showing a comparison of exchange anisotropic magnetic fields of a NiFe film and a Co film.

FIG. 14 is a diagram showing a relationship between an exchange anisotropic magnetic field and a measurement temperature.

FIG. 15 is a diagram showing a comparison of the exchange anisotropic magnetic field of a PtMn film with and without a base Ta film when the stacking order is changed.

FIG. 16 is a diagram showing a comparison of the exchange anisotropic magnetic field of a NiMn film with and without a base Ta film when the stacking order is changed.

FIG. 17 is a diagram showing a comparison of exchange anisotropic magnetic fields of PtMn, NiMn, and NiMnCr films.

FIG. 18 is a diagram showing a comparison of the corrosion resistance of PtMn, NiMn, and NiMnCr films.

FIG. 19 is a view showing the relationship between the film composition of a PtMn film and corrosion resistance.

FIG. 20: As depo. By Auger electron spectroscopy depth profile. It is a figure showing the interface diffusion situation of a state.

FIG. 21 is a diagram showing an interface diffusion state after heat treatment by Auger electron spectroscopy depth profile.

FIG. 22 is a diagram showing an analysis result of a film structure by an X-ray diffraction profile.

FIG. 23: PtM film formed by DC magnetron sputtering
FIG. 4 is a diagram illustrating a relationship among an exchange anisotropic magnetic field of an n film, a film thickness of a NiFe film, and a heat treatment temperature.

FIG. 24: PtM formed by DC magnetron sputtering
FIG. 4 is a diagram illustrating a relationship among an exchange anisotropic magnetic field, a heat treatment temperature, a type of a ferromagnetic layer, and a film thickness of an n film.

FIG. 25: PtM formed by DC magnetron sputtering
FIG. 4 is a diagram illustrating a relationship among a blocking temperature of an n film, a type of a ferromagnetic layer, and a film thickness.

FIG. 26 is a diagram illustrating experimental conditions for obtaining an exchange anisotropic magnetic field required for the magnetoresistive heads according to the first and second embodiments.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 soft magnetic material layer 2 electric insulating layer 3 ferromagnetic layer 4 diamagnetic layer 5 conductive layer 6 magnet 7 Free magnetic layer 8 nonmagnetic intermediate layer 9 Pinned magnetic layer 10 antiferromagnetic layer 11 magnet 13 antiferromagnetic layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-325934 (JP, A) JP-A-6-76247 (JP, A) JP-A-6-314617 (JP, A) JP-A-54-1979 10997 (JP, A) JP-A-1-248578 (JP, A) JP-A 8-88118 (JP, A) JP-A 8-138935 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 5/39

Claims (15)

(57) [Claims] 1. A magnetoresistive head having a ferromagnetic layer and an antiferromagnetic layer directly in contact with the ferromagnetic layer, wherein the antiferromagnetic layer has a film composition of Pt36 to 54Mn46.
Of the PtMn alloy of about 64 atomic%, and the antiferromagnetic layer is formed at the interface between the antiferromagnetic layer and the ferromagnetic layer.
Constituting Pt and Mn atoms and the ferromagnetic layer
Magnetic atom is interdiffusion layer is formed which diffuses mutually to
Cage, exchange anisotropic magnetic field between said antiferromagnetic layer and said <br/> ferromagnetic layer through the mutual diffusion layer is not acting
Magnetoresistive head, characterized in that that. 2. An exchange anisotropic magnetic field (Hex) of 200
(Oe) or more.
De. 3. The temperature change of the exchange anisotropic magnetic field (Hex).
The temperature is in the range of room temperature to 120 ° C.
Claim that is flat compared to said variation at temperatures above
Item 3. The magnetoresistive head according to item 1 or 2. 4. A magnetoresistive head comprising a ferromagnetic layer and an antiferromagnetic layer in direct contact with said ferromagnetic layer, wherein said antiferromagnetic layer has a film composition of Pt5-20Mn80-
The antiferromagnetic layer is composed of a 95 atomic% PtMn alloy and is formed at an interface between the antiferromagnetic layer and the ferromagnetic layer.
Pt and Mn atoms and the ferromagnetic layer
Magnetic atoms are mutually diffused to form an interdiffusion layer .
And an exchange anisotropic magnetic field acts between the antiferromagnetic layer and the ferromagnetic layer via the interdiffusion layer . 5. The antiferromagnetic layer has a Pt content of 44 atomic%.
The magnetoresistive head according to any one of claims 1 to 3, which is as described above. 6. The magnetoresistive head according to claim 1, wherein said antiferromagnetic layer is in contact with said ferromagnetic layer. 7. The magnetoresistive head according to claim 1, wherein said ferromagnetic layer is in contact with said antiferromagnetic layer. 8. The interdiffusion layer has a thickness of 20 to 100 °.
Any claims 1 a (Å) 7
A magnetoresistive head according to any of the claims. Film composition according to claim 9, wherein said ferromagnetic layer is any one of a NiFe alloy, NiFeCo alloy, or Co
A magnetoresistive head according to claim 1 . 10. The antiferromagnetic layer has a thickness of 100 to 5
A Å (angstrom), claim a film thickness of the ferromagnetic layer is 5～300A (Å)
10. The magnetoresistive head according to any one of 1 to 9 . Wherein said thickness of the antiferromagnetic layer 100-5
A Å (angstrom), the thickness of the ferromagnetic layer is 15～300A (Å) according
Item 10. A magnetoresistive head according to any one of Items 1 to 9 . 12. The antiferromagnetic layer having a thickness of 100 to 5
A Å (angstrom), the thickness of the ferromagnetic layer is 50 to 300 Å (angstrom) wherein
Item 10. A magnetoresistive head according to any one of Items 1 to 9 . Wherein said thickness of the antiferromagnetic layer 100-5
A Å (angstrom), the thickness of the ferromagnetic layer is 15～100A (Å) according
Item 10. A magnetoresistive head according to any one of Items 1 to 9 . 14. The film thickness of the antiferromagnetic layer 100-5
A Å (angstrom), claim a film thickness of the ferromagnetic layer is 15～30A (Å)
10. The magnetoresistive head according to any one of 1 to 9 . 15. The film thickness of the antiferromagnetic layer 100-3
2. The method according to claim 1 , wherein the angle is 00 ° (angstrom).
5. The magnetoresistive head according to any one of 4 .