JP2022011105A - Magnetoresistive effect device and method for manufacturing the same - Google Patents

Abstract

To provide a magnetoresistive effect device that enables high-precision magnetic sensing.SOLUTION: In a magnetoresistive device having a plurality of elements on a substrate, the elements are spaced apart from adjacent elements, and the sides of the elements are covered by a magnetic particle anti-adhesion layer with a length of 100 nm or more, which prevents magnetic particles from adhering.SELECTED DRAWING: Figure 2

Description

The present invention relates to a magnetoresistive effect device, and more particularly to a magnetoresistive device that causes a huge change in magnetoresistance in a low magnetic field region.

In recent years, a magnetic sensor using a magnetoresistive effect element can detect a minute change in a magnetic field, and is used in various applications such as a read head of a hard disk drive. A general giant magnetoresistive element has a GMR (Giant Magneto Resistance, hereinafter referred to as giant magnetoresistance) composed of a ferromagnetic fixed layer, a non-magnetic intermediate layer, and a ferromagnetic free layer, which are laminated in order from the bottom as a basic structure. It has a laminated film.

The ferromagnetic free layer changes its magnetization direction sensitively to changes in the external magnetic field, whereas the ferromagnetic fixed layer is made of the material of the ferromagnetic fixed layer itself or ferromagnetic so that the magnetization direction does not change due to the external magnetic field. The laminated structure of the base of the fixed layer is designed. In such a basic structure, the phenomenon in which the electrical resistance changes significantly due to the relative angle of the magnetization direction between the ferromagnetic free layer and the ferromagnetic fixed layer changing due to an external magnetic field is the giant magnetoresistive effect (hereinafter referred to as the GMR effect). is called.

When the GMR laminated film is used as a GMR sensor, it is processed into a fine line so that its electrical resistance value changes linearly with respect to an external magnetic field. Further, in order to protect the processed GMR sensor from deterioration factors such as oxygen and humidity, it is generally necessary to protect the entire GMR sensor with an insulating film.

Patent Document 1 states that a magnetoresistive sensor processed into an elongated shape can prevent chattering and obtain stable operation, and can easily control magnetic sensitivity according to the application. The enabled magnetic sensor is described. Patent Document 2 describes a method for manufacturing a vertically energized GMR element in which a patterned GMR multilayer film is coated with an insulating film, which is used in a head for large-capacity magnetic recording / reproduction.

Japanese Unexamined Patent Publication No. 2007-273528 Japanese Unexamined Patent Publication No. 2010-87293

In Patent Document 1, the magnetoresistive effect element is processed into an elongated shape, but it is a non-contact type magnetic sensor, and the magnetic material to be detected does not come into direct contact with the magnetic sensor. When detecting a magnetic material that comes into direct contact with the sensor, positive and negative signals are generated depending on whether the detection target is directly above the sensor or next to the sensor, and the signals cancel each other out and become smaller.

In Patent Document 2, a vertically energized GMR element coated with an insulating film is manufactured, but since this is also a non-contact magnetic sensor and is not processed into an elongated shape, it is subject to an external magnetic field. The magnetic field range in which the magnetoresistive value changes linearly becomes extremely small.

Therefore, when the magnetic substance to be detected is in contact with the magnetic sensor, a large signal cannot be obtained, and high-precision magnetic sensing is difficult.

An object of the present invention is to provide a magnetoresistive effect device capable of highly accurate magnetic sensing.

A preferred example of the present invention is a magnetoresistive device having a plurality of elements on a substrate, wherein the elements are arranged at intervals from the adjacent elements.
The side surface of the element
A magnetoresistive device covered with a magnetic particle adhesion prevention layer having a length of 100 nm or more, which prevents the adhesion of magnetic particles.

According to the present invention, it is possible to realize a magnetoresistive effect device capable of magnetic sensing with high accuracy.

It is a figure which shows the laminated film which constitutes the magnetoresistive effect element of Example 1. FIG. It is a figure which shows the magnetoresistive effect device of Example 1. FIG. It is a figure which shows the laminated film which constitutes the magnetoresistive effect element of Example 2. It is a figure which shows the laminated film which constitutes the magnetoresistive effect element of Example 3. FIG. It is a figure which shows the magnetoresistive effect device of a comparative example. It is a figure which shows the magnetoresistive effect device in Experimental Example 1. FIG. It is a figure which shows the relationship between the signal and the measured magnetic field in Experimental Example 1. FIG. The figure which shows the relationship between the distance from a side wall and the signal. It is a figure which shows the relationship between the MR ratio in Experimental Example 2 and the aspect ratio of a GMR sensor. It is a figure which shows the relationship between the operating magnetic field range in Experimental Example 2 and the aspect ratio of a GMR sensor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the following, a GMR laminated film having a base layer, an antiferromagnetic layer, a ferromagnetic fixed layer, a non-magnetic intermediate layer, a ferromagnetic free layer and a protective layer laminated on a substrate in order is finely processed into fine lines to form magnetic particles. It will be described that the performance of the GMR sensor is improved by forming the adhesion prevention layer. Here, the thin line shape means an elongated shape composed of a minor axis and a major axis, and the width of the laminated film is the minor axis.

Specifically, it will be described that the magnetic field leaking from the magnetic material to be detected adhering to the upper part of the GMR sensor is detected more efficiently. In this embodiment, a magnetic particle adhesion prevention layer is formed on the GMR sensor processed into a fine line shape.

<Structure of magnetoresistive sensor>
FIG. 1 shows the configuration of the GMR laminated film of this embodiment. The GMR laminated film of this embodiment has a substrate 101 and has a base layer 102 formed on the substrate 101. The underlayer 102 has a role of forming the GMR laminated film flat and a role of crystallizing the constituent film of the GMR laminated film formed on the underlayer 102.

The base layer 102 has a metal containing Ta (tantalum), Ti (titanium), Ni (nickel), Cr (chromium), Al (aluminum), or Fe (iron). Alternatively, the base layer 102 has an oxide containing Ta (tantalum), Ti (titanium), Ni (nickel), Cr (chromium), Al (aluminum), or Fe (iron). Specifically, the base layer 102 is composed of one or more kinds of materials, and can be formed, for example, by a laminated film composed of two layers, a Ta layer and a NiCr (nickel chromium) layer. When the film thickness of the underlayer 102 is thin, it does not function as an underlayer, so it is desirable that the underlayer 102 has a film thickness of 1 nm or more.

An antiferromagnetic layer 103 is formed on the base layer 102. The antiferromagnetic layer 103 needs to maintain its magnetism at room temperature or higher at which the GMR laminated film operates. Therefore, the material constituting the antiferromagnetic layer 103 is preferably an oxide containing any one or more elements of Ni, Cr, Fe, Co (cobalt) or Mn (manganese). Alternatively, the material constituting the antiferromagnetic layer 103 is preferably a metal containing any one or more elements of Fe, Mn, Pt (platinum) or Ir (iridium).

The antiferromagnetic layer 103 is made of a material having no magnetic moment as a whole. However, from a fine point of view, the magnetic moments of the magnetic atoms are alternately and regularly arranged in the antiferromagnetic layer 103 in opposite directions. The antiferromagnetic layer 103 of this embodiment has, for example, only two types of magnetic moments in a direction along the upper surface of the substrate 101 and opposite to each other. As a result, since the spontaneous magnetization cancels each other out, the spontaneous magnetization of the antiferromagnetic layer 103 becomes zero as a whole.

A ferromagnetic fixed layer 104 is formed on the antiferromagnetic layer 103. The ferromagnetic fixed layer 104 is a ferromagnetic layer in which the direction of magnetization is not fixed by itself. However, the antiferromagnetic layer 103 and the ferromagnetic fixed layer 104 are magnetically coupled at the interface between them, so that the magnetization direction of the ferromagnetic fixed layer 104 is fixed. The magnetization direction of the ferromagnetic fixed layer 104 needs not to change easily even when the external magnetic field is large. Therefore, the material of the ferromagnetic fixed layer 104 preferably contains Fe, Ni, Co or at least one of these alloys.

A non-magnetic intermediate layer 105 is formed on the ferromagnetic fixed layer 104. Further, a ferromagnetic free layer 106 is formed on the non-magnetic intermediate layer 105. The non-magnetic intermediate layer 105 has a film thickness sufficiently thick to eliminate the magnetic bond between the ferromagnetic free layer 106 above the non-magnetic intermediate layer 105 and the ferromagnetic fixed layer 104 below the non-magnetic intermediate layer 105. Must be done.

The film thickness of the non-magnetic intermediate layer 105 is preferably 1 nm or more, for example. Further, since the GMR effect is exhibited in a region including the ferromagnetic fixed layer 104, the non-magnetic intermediate layer 105, and the ferromagnetic free layer 106, the non-magnetic intermediate layer 105 is conductive in order to efficiently pass a current through the region. It is preferably made of a high-grade material. Examples of the material of the non-magnetic intermediate layer 105 include Cu and the like.

The ferromagnetic free layer 106 formed on the non-magnetic intermediate layer 105 is a ferromagnetic layer in which the direction of magnetization is not fixed by itself. The ferromagnetic free layer 106 is in a sensing position where the magnetization direction changes when a weak magnetic field generated from an inspection object is detected above the magnetoresistive element.

Therefore, the ferromagnetic free layer 106 needs to be made of a material whose magnetization direction easily changes with a change of an external magnetic field. That is, the ferromagnetic free layer 106 needs to exhibit good soft magnetic properties. Therefore, the material of the ferromagnetic free layer 106 preferably contains Fe, Ni, Co or at least one of these alloys. In particular, it is more preferable that the ratio of Ni is 50% or more.

A protective layer 107 is formed on the ferromagnetic free layer 106. As described above, the GMR laminated film includes the substrate 101, the base layer 102, the antiferromagnetic layer 103, the ferromagnetic fixed layer 104, the non-magnetic intermediate layer 105, and the ferromagnetic free layer 106, which are sequentially laminated on the substrate 101. It has a layer 107. The protective layer 107 is in contact with the upper surface of the ferromagnetic free layer 106 and covers the entire upper surface of the ferromagnetic free layer 106.

The protective layer 107 has a role of preventing the ferromagnetic free layer 106 from being deteriorated by the external environment of the GMR laminated film. That is, the protective layer 107 has a role of preventing the ferromagnetic free layer 106 from being altered by a chemical reaction such as oxidation, thereby reducing the reliability of the magnetoresistive element. The film thickness of the protective layer 107 has a film thickness of at least 0.5 nm because it is necessary to maintain its crystallinity.

Further, one of the main features of this embodiment is that the GMR laminated film is processed into a fine line shape. At this time, the magnetization direction of the ferromagnetic fixed layer 104 is fixed in the short axis direction of the thin wire, and the magnetization direction of the ferromagnetic free layer is oriented in the long axis direction of the GMR laminated film of the thin wire due to the shape magnetic anisotropy. Specifically, the shape of the thin wire is a thin wire shape having an aspect ratio of 1: 5 or more and 1: 300 or less. Here, the aspect ratio is the width of the GMR laminated film (the length in the short axis direction indicated by the arrow 108) constituting the element of the magnetoresistive effect device and the length in the long axis direction of the GMR laminated film (paper surface of FIG. 1). It is the ratio with the length of the laminated film in the direction perpendicular to.

When the aspect ratio is 1: 5 or more, the electric resistance value linearly changes with respect to the external magnetic field. Further, when the aspect ratio is 1: 300 or less, the magnetization direction of the ferromagnetic fixed layer can be fixed in the minor axis direction of the thin wire, and it functions as a GMR sensor. Here, the GMR sensor is composed of at least one or more thin wires, and a plurality of fine wires may be electrically connected in series or in parallel.

Further, one of the main features of this embodiment is to form a magnetic particle adhesion prevention layer after processing the GMR laminated film into a fine line shape. FIG. 2 is a diagram showing a magnetoresistive effect device. The magnetoresistive device has a magnetoresistive element (GMR sensor) formed on the substrate 203. The magnetoresistive element (GMR sensor) is connected to an electrode, although omitted in FIG. 2.

The signal of the GMR sensor is positive and negative when the magnetic particles adhere to the upper part of the GMR sensor 201 shown in FIG. 2 and when the magnetic particles adhere to the side wall of the GMR sensor 201. Therefore, when magnetic particles adhere to the entire GMR sensor, the signals are attenuated by canceling each other.

Since the absolute value of the signal is larger when the magnetic particles are attached to the upper part of the GMR sensor, the total signal of the GMR sensor is improved by forming the magnetic particle adhesion prevention layer 202 on the side wall of the GMR sensor. The magnetic particle adhesion prevention layer 202 is formed of a non-magnetic or antiferromagnetic insulator material. Further, the side wall of the GMR sensor 201 needs to be covered with a magnetic particle adhesion prevention layer 202 having a length of at least 100 nm (indicated by an arrow 204).

Further, in this embodiment, the outermost surface of the GMR sensor can be molecularly modified to bind molecules including a detection target, and further specifically to bind a substance that generates a leakage magnetic field to function as a biosensor. As molecular modification on the surface of the GMR sensor, for example, oxygen is converted into a hydroxyl group by performing oxygen plasma treatment on the surface of the GMR sensor, and modified with 3-aminopropyltriethoxysilane (APTES) by a silane coupling reaction with an amino group. Is possible.

The crystal structure of the above GMR sensor can be easily confirmed by X-ray diffraction (XRD). Further, the structure of the GMR sensor can be confirmed by observing with an electron microscope such as TEM (Transmission Electron Microscope, transmission electron microscope) or SEM (Scanning Electron Microscope, scanning electron microscope). Further, the single crystal or polycrystal crystal structure and the laminated structure of the GMR laminated film can be confirmed by observing a spot-like pattern or a ring-like pattern in the electron diffraction image.

The composition distribution of each layer of the GMR sensor can be confirmed by using EPMA (Electron Probe Micro Analyzer) such as EDX (Energy dispersive X-ray spectroscopy). Further, the composition distribution can be confirmed by using a method such as SIMS (Secondary Ion Mass Spectrometry), X-ray photoelectron spectroscopy or ICP (Inductively Coupled Plasma) emission spectroscopy. ..

<Method of manufacturing GMR sensor>
Next, a method of manufacturing a GMR sensor will be described. Each layer of the GMR laminated film in the GMR sensor can be formed by, for example, a sputtering method performed in an ultra-high vacuum having a ultimate vacuum degree of 1.0 × 10 ^-5 Pa or less. The material of each layer can be formed using a sputtering target having the same composition as each layer to be formed. In order to obtain a flat layer having good crystallinity and orientation, the Ar (argon) pressure at the time of film formation is preferably 10 mTorr or less.

Next, the deviceization process will be described. Photolithography and electron beam lithography technologies are used to convert the GMR laminated film into a GMR sensor. First, a photoresist film having the shape of a GMR sensor pattern is formed on the GMR laminated film by using electron beam lithography technology. Then, the resist film is used as an etching blocking mask, and etching is performed using argon ion milling to overetch the substrate. After that, the resist film is removed. Then, it was annealed at 240 ° C. for 1 hour under an applied magnetic field of 6 kOe, and then cooled in a furnace as it was.

The annealing temperature at that time is preferably 200 ° C. or higher and 400 ° C. or lower in order to obtain a flat layer having good crystallinity and orientation. More preferably, annealing at 240 ° C. or higher and 300 ° C. or lower provides a flatter layer having better crystallinity and orientation. Further, when the magnitude of the magnetic field in annealing is 5 kOe or more, the fixation of the magnetization direction of the ferromagnetic fixed layer is promoted, which is preferable.

<Effect of GMR sensor>
In order to quantitatively detect a weak leakage magnetic field in a GMR sensor, the electrical resistance value of the sensor needs to change linearly with respect to an external magnetic field. Therefore, the GMR laminated film is processed into a fine line. At this time, the magnetization direction of the ferromagnetic fixed layer is fixed in the short axis direction of the thin wire, and the magnetization direction of the ferromagnetic free layer is oriented in the long axis direction of the thin wire due to the shape magnetic anisotropy.

In the initial state without a magnetic field, the relative angle between the ferromagnetic fixed layer and the ferromagnetic free layer in the magnetization direction is 90 °. When magnetic particles adhere and an external magnetic field such as a leakage magnetic field acts, the relative angle between the ferromagnetic fixed layer and the ferromagnetic free layer in the magnetization direction deviates from 90 °, and the electrical resistance value also increases with respect to the increase or decrease in the relative angle. Increase or decrease. Here, the GMR sensor is composed of at least one or more thin wires, and a plurality of fine wires may be electrically connected in series or in parallel.

FIG. 2 is a view of the magnetoresistive device from the long axis direction. When the GMR sensor 201, which is an element of the magnetoresistive device, detects deposits such as magnetic particles, there are cases where the magnetic particles adhere to the upper part of the GMR sensor and cases where the magnetic particles adhere to the side wall of the GMR sensor. be.

Since the signal of the GMR sensor is positive and negative when the magnetic particle adheres to the upper part of the GMR sensor and when the magnetic particle adheres to the side wall of the GMR sensor, the signal is canceled when the magnetic particle adheres to the entire GMR sensor. It decays. The absolute value of the signal is larger when the magnetic particles are attached to the upper part of the GMR sensor.

The magnetic particle adhesion prevention layer 202 of this embodiment is formed of a non-magnetic or antiferromagnetic insulator material. Further, the side wall of the GMR sensor 201 is covered with a magnetic particle adhesion prevention layer 202 having a length of at least 100 nm or more. Therefore, the signal of the magnetic particles adhering to the side wall can be attenuated, and the total signal of the GMR sensor can be improved.

According to this embodiment, the performance of the GMR sensor can be improved. In particular, the direction of the magnetic field due to the magnetic particles is unified, and the magnetic field of the magnetic material in contact with the GMR sensor can be efficiently detected. Therefore, it is possible to realize highly accurate magnetic sensing for a contact-type magnetoresistive device that detects the presence of a magnetic material by contacting the magnetic material with the magnetoresistive effect device.

The structure of the GMR laminated film constituting the GMR sensor may have a laminated structure as shown in FIG. The GMR laminated film of Example 2 has a base layer 302, an antiferromagnetic layer 303, a first ferromagnetic fixing layer 304, a non-magnetic bonding layer 305, and a second ferromagnetic fixing layer 306 formed in this order on the substrate 301. It is composed of a non-magnetic intermediate layer 307, a ferromagnetic free layer 308 and a protective layer 309.

Unlike the structure shown in FIG. 1, here, the first ferromagnetic fixed layer 304 and the second ferromagnetic fixed layer 306 are formed, and the non-magnetic bonding layer 305 is formed between them. .. The magnetization direction of the first ferromagnetic fixed layer 304 is fixed by the antiferromagnetic layer 303. Further, the magnetization direction of the second ferromagnetic fixed layer 306 formed on the first ferromagnetic fixed layer 304 via the non-magnetic bonding layer 305 is fixed in the direction opposite to that of the first ferromagnetic fixed layer 304. Has been done. The magnetization direction of the second ferromagnetic fixing layer 306 is determined by the thickness of the non-magnetic bonding layer 305, that is, the distance between the first ferromagnetic fixing layer 304 and the second ferromagnetic fixing layer 306.

The magnetization directions of the first ferromagnetic fixed layer 304 and the second ferromagnetic fixed layer 306 are opposite to each other. In other words, the magnetization direction of the first ferromagnetic fixed layer 304 and the magnetization direction of the second ferromagnetic fixed layer 306 are antiparallel to each other. As a result, the magnetic fields emitted from each of the first ferromagnetic fixed layer 304 and the second ferromagnetic fixed layer 306 loop between the first ferromagnetic fixed layer 304 and the second ferromagnetic fixed layer 306. ..

That is, most of the leaked magnetic field emitted from the first ferromagnetic fixed layer 304 passes through the second ferromagnetic fixed layer 306, and most of the leaked magnetic field emitted from the second ferromagnetic fixed layer 306 passes through the first ferromagnetic fixed layer 306. It passes through the fixed layer 304. Therefore, the magnetic fields emitted from each of the first ferromagnetic fixed layer 304 and the second ferromagnetic fixed layer 306 do not affect the external environment.

Such a structure is called a laminated antiferromagnetic structure. Since the magnetic field emitted from the GMR laminated film is reduced in the laminated antiferromagnetic structure, when detecting the magnetic field of a very weak magnetic material, the magnetic field of the magnetic material is not changed before and after the detection. Can be detected. Therefore, the magnetic state can be detected more accurately. At least one of the first ferromagnetic fixing layer 304 and the second ferromagnetic fixing layer 306 contains either Co or Co—Fe alloy, and the non-magnetic bonding layer 305 contains Ru (ruthenium) and Ir. It is preferable to include at least one of.

The laminated film composed of the first ferromagnetic fixing layer 304, the non-magnetic bonding layer 305 and the second ferromagnetic fixing layer 306 can be regarded as one ferromagnetic fixing layer. That is, in the magnetoresistive effect element of this embodiment, the ferromagnetic fixing layer 104 of Example 1 is a laminated film composed of a first ferromagnetic fixing layer 304, a non-magnetic bonding layer 305, and a second ferromagnetic fixing layer 306. It can be considered that it is composed of.

The structure of the GMR laminated film constituting the GMR sensor may have a laminated structure as shown in FIG. In the GMR laminated film of this embodiment, the following layers are sequentially formed on the substrate 401. That is, on the substrate 401, the base layer 402, the first antiferrous layer 403, the first ferromagnetic fixing layer 404, the first non-magnetic bonding layer 405, the second ferromagnetic fixing layer 406, and the first Non-magnetic intermediate layer 407, ferromagnetic free layer 408, second non-magnetic intermediate layer 409, third ferromagnetic fixing layer 410, second non-magnetic bonding layer 411, fourth ferromagnetic fixing layer 412, first. The anti-magnetic layer 413 and the protective layer 414 of 2 are laminated.

Unlike the structure shown in FIG. 3, here, the second non-magnetic intermediate layer 409, the third ferromagnetic fixing layer 410, the second non-magnetic bonding layer 411, the fourth ferromagnetic fixing layer 412, and the second. The antiferromagnetic layer 413 of 2 is formed in a laminated manner. These reverse the order of the first antiferromagnetic layer 403, the first ferromagnetic fixed layer 404, the first non-magnetic coupling layer 405, the second ferromagnetic fixed layer 406, and the first non-magnetic intermediate layer 407. It is laminated in and has the same role. However, the constituent materials do not have to be the same.

At least one of the third ferromagnetic fixed layer 410 or the fourth ferromagnetic fixed layer 412 contains either Co or Co—Fe alloy, and the second non-magnetic bonding layer 411 is Ru (ruthenium). It is preferable to include at least one of and Ir.

In this embodiment, the magnetization direction of the first ferromagnetic fixed layer 304 and the magnetization direction of the second ferromagnetic fixed layer 306 are antiparallel to each other. Further, the magnetization direction of the third ferromagnetic fixed layer 410 and the magnetization direction of the fourth ferromagnetic fixed layer 412 are antiparallel to each other.

Such a structure is called a dual type laminated antiferromagnetic structure. In the dual type laminated antiferromagnetic structure, the amount of change in electrical resistivity due to an external magnetic field becomes large.

<Experimental Example 1>
The present inventors first produced a GMR sensor without a magnetic particle adhesion prevention layer, and evaluated the signal obtained from the magnetic particles adhering to the upper part and the side wall of the GMR sensor. In addition, the signal obtained from the magnetic particles adhering to the side wall was evaluated with and without the magnetic particle adhesion prevention layer.

The structure of the GMR laminated film used here is the same as that shown in FIG. Here, a base layer 302, which is a laminated film composed of a film having a thickness of 5 nm made of Ta and a film having a thickness of 5 nm made of NiCr, is formed on a Si substrate whose surface is covered with a thermal oxide film. There is.

Further, an antiferromagnetic layer 303 made of Ir ₂₀ Mn ₈₀ and having a film thickness of 6 nm and a first ferromagnetic fixing layer 304 made of Co ₉₀ Fe ₁₀ and having a film thickness of 1.6 nm are formed.

Further, a non-magnetic bonding layer 305 made of Ru and having a film thickness of 0.85 nm, a second ferromagnetic fixing layer 306 made of Co ₉₀ Fe ₁₀ having a film thickness of 1.6 nm, and 2.5 nm made of Cu. It forms a non-magnetic intermediate layer 307 having a film thickness of.

Further, a ferromagnetic free layer 308 composed of a film made of Co ₉₀ Fe ₁₀ having a film thickness of 1.0 nm and a film made of Ni ₈₁ Fe ₁₉ having a film thickness of 3.5 nm is formed. In addition, a protective layer 309 composed of Ru and Ta was formed.

Next, the deviceization process will be described. Photolithography and electron beam lithography techniques are used to form a GMR sensor having a GMR laminated film.

First, a photoresist film having the shape of a GMR sensor pattern is formed on the GMR laminated film by using electron beam lithography technology.

Then, the resist film is used as an etching blocking mask, and etching is performed using argon ion milling to overetch the substrate. After that, the resist film is removed. This forms a pattern of a GMR sensor having a length of 50 μm in the vertical direction and 400 nm in the horizontal direction when viewed from a plane. The distance between the thin lines was set to 300 nm. Then, it was annealed at 240 ° C. for 1 hour under an applied magnetic field of 6 kOe, and then cooled in a furnace as it was.

The shape of the GMR sensor can be easily confirmed using an SEM, TEM or an optical microscope.

FIG. 5 shows a magnetoresistive effect device in the case where there is no magnetic particle adhesion prevention layer (comparative example). The magnetoresistive device of FIG. 5 has a GMR sensor 501 on a substrate 502.

FIG. 6 shows a magnetoresistive effect device when the GMR sensor 601 and the magnetic particle adhesion prevention layer 602 are on the substrate 603. After the GMR sensor 601 is finely patterned, the magnetic particle adhesion prevention layer 602 is formed by a sputtering method so that all the grooves formed between the plurality of GMR sensors 601 are filled. Here, SiO ₂ was used as the magnetic particle adhesion prevention layer 602. After that, chemical mechanical polishing was performed to flatten the entire surface.

FIG. 7 shows a signal obtained from a magnetic field leaking from the magnetic field adhering to the upper part and a leak from the magnetic particle adhering to the side wall when the magnetic particle is attached to the entire GMR sensor without the magnetic particle adhesion prevention layer. It is a figure which shows the total signal which added the signal obtained from the magnetic field, the magnetic particle attached to the upper part, and the signal from the magnetic particle attached to a side wall. The signal can be represented by the change in the electrical resistance of the GMR sensor when the magnetic particles are not attached to the GMR sensor and when the magnetic particles are attached to the GMR sensor.

It can be seen from FIG. 7 that the magnitude of the signal varies slightly depending on the measured magnetic field, but the signal from the magnetic particles adhering to the upper part is dominant. Therefore, the total signal can be increased by attenuating the signal obtained from the leakage magnetic field of the magnetic particles adhering to the side wall.

FIG. 8 is a diagram showing the relationship between the distance from the side wall to the magnetic particles and the signal from the magnetic particles when the magnetic particle adhesion prevention layer is present and when it is not (comparative example). In the comparative example, the signal increases as the position where the magnetic particles adhere is closer to the side wall.

On the other hand, in this experimental example, although the signal increases as the position where the magnetic particles adhere is closer to the side wall, it can be seen that the increase amount is suppressed as compared with the comparative example. As a result, in the comparative example, the signal from the magnetic particles adhering to the side wall can be suppressed by about 30% when the distance from the side wall is 50 nm. From FIG. 8, the effective distance from the side wall to sufficiently suppress the signal was about 100 nm. If the magnetic particle adhesion prevention layer has a length of 100 nm or more, the influence of the signal from the magnetic particles adhering to the side wall can be reduced by covering the side wall of the GMR sensor.

<Experimental Example 2>
Regarding the GMR sensor, the dimensional ratio of the thin wire shape that can operate as a sensor will be described. The structure of the GMR laminated film constituting the GMR sensor used here is the structure shown in FIG. Here, a base layer 302, which is a laminated film composed of a film having a thickness of 5 nm made of Ta and a film having a thickness of 5 nm made of NiCr, is formed on a Si substrate whose surface is covered with a thermal oxide film. There is.

Further, an antiferromagnetic layer 303 made of Ir ₂₀ Mn ₈₀ and having a film thickness of 6 nm and a first ferromagnetic fixing layer 304 made of Co ₉₀ Fe ₁₀ and having a film thickness of 1.6 nm are formed.

Further, a non-magnetic bonding layer 305 made of Ru and having a film thickness of 0.85 nm, a second ferromagnetic fixing layer 306 made of Co ₉₀ Fe ₁₀ having a film thickness of 1.6 nm, and 2.5 nm made of Cu. It forms a non-magnetic intermediate layer 307 having a film thickness of.

Further, a ferromagnetic free layer 308 composed of a film made of Co ₉₀ Fe ₁₀ having a film thickness of 1.0 nm and a film made of Ni ₈₁ Fe ₁₉ having a film thickness of 3.5 nm is formed. In addition, a protective layer 309 composed of Ru and Ta was formed.

Next, the deviceization process will be described. Photolithography and electron beam lithography technologies are used to convert the GMR laminated film into a GMR sensor. First, a photoresist film having the shape of a GMR sensor pattern is formed on the GMR laminated film by using electron beam lithography technology.

Then, the resist film is used as an etching blocking mask, and etching is performed using argon ion milling to overetch the substrate.

After that, the resist film is removed. This forms a pattern of a GMR sensor having a length of 100 μm in the vertical direction and 100 nm to 20 μm in the horizontal direction when viewed from a plane. The aspect ratio of the GMR sensor at this time was width: length = 1: 5 to 1: 1000. The distance between the GMR sensors was 600 nm. Then, it was annealed at 240 ° C. for 1 hour under an applied magnetic field of 6 kOe, and then cooled in a furnace as it was.

FIG. 9 is a diagram showing an MR ratio (MR ratio (magnetic resistance change rate)) on the vertical axis that determines the magnitude of the sensor signal and an aspect ratio of the GMR sensor. As the aspect ratio increases, the MR ratio decreases significantly. In order to use it as a sensor for detecting magnetic particles, it is necessary that the MR ratio exceeds 1% and the GMR effect is exhibited. Therefore, the aspect ratio of the GMR sensor needs to be 1: 300 or less.

FIG. 10 is a diagram showing the relationship between the operating magnetic field range in which the sensor operates and the aspect ratio of the GMR sensor. The working magnetic field range decreases as the aspect ratio decreases. The operating magnetic field range indicates the range of the detectable magnetic field, and at least 10 Oe or more is required to detect the magnetic particles, so that the aspect ratio needs to be 1: 5 or less. Therefore, the aspect ratio of the GMR sensor that can be used as the GMR sensor for detecting magnetic particles is 1: 5 or more and 1: 300 or less.

Although the invention made by the present inventors has been specifically described above based on the examples thereof, the invention is not limited to the above-mentioned examples and can be variously changed without departing from the gist thereof.

101, 203, 301, 401, 502, 603 Substrate 102, 302, 402 Underlayer 103, 303 Anti-ferrous layer 104 ferromagnetic fixed layer 105, 307 Non-magnetic intermediate layer 106, 308, 408 Hydrite free layer 107, 309 414 Protective layers 201, 501, 601 GMR sensor 202, 602 Magnetic particle adhesion prevention layer 304, 404 First ferromagnetic fixing layer 305 Non-magnetic bonding layer 306, 406 Second ferromagnetic fixing layer 403 First anti-strength Magnetic layer 405 1st non-magnetic bonding layer 407 1st non-magnetic intermediate layer 409 2nd non-magnetic intermediate layer 410 3rd ferromagnetic fixing layer 411 2nd non-magnetic bonding layer 412 4th ferromagnetic fixing layer 413 Second anti-magnetic layer

Claims (14)

A magnetoresistive device having multiple elements on a substrate.
The element is arranged at a distance from the adjacent element.
The side surface of the element
A magnetoresistive device covered with a magnetic particle adhesion prevention layer having a length of 100 nm or more that prevents the adhesion of magnetic particles. In the magnetoresistive device according to claim 1,
The element is
A magnetoresistive device which is a laminated film in which a base layer, an antiferromagnetic layer, a ferromagnetic fixed layer, a non-magnetic intermediate layer, a ferromagnetic free layer, and a protective layer are laminated on the substrate. In the magnetoresistive device according to claim 1,
The aspect ratio, which is the ratio of the width to the length of the element,
A magnetoresistive device that is greater than or equal to 1: 5 and less than or equal to 1: 300. In the magnetoresistive device according to claim 2,
The antiferromagnetic layer is
A magnetoresistive device having an oxide containing one or more elements of Ni, Cr, Fe, Co or Mn, or a metal containing one or more elements of Fe, Mn, Pt or Ir. In the magnetoresistive device according to claim 2,
The base layer is
A magnetoresistive device having a metal containing Ta, Ti, Ni, Cr, Al or Fe, or having an oxide containing Ta, Ti, Ni, Cr, Al or Fe. In the magnetoresistive device according to claim 1,
A magnetoresistive device having electrodes connected to the element. In the magnetoresistive device according to claim 2,
The ferromagnetic fixed layer is
A magnetoresistive device having a first ferromagnetic fixed layer, a non-magnetic coupled layer, and a second ferromagnetic fixed layer. In the magnetoresistive device according to claim 7.
The first ferromagnetic fixed layer or the second ferromagnetic fixed layer is
Contains Co or Co—Fe alloys
The non-magnetic bond layer is
A magnetoresistive device containing Ru or Ir. In the magnetoresistive device according to claim 7.
The magnetization direction of the first ferromagnetic fixed layer and the magnetization direction of the second ferromagnetic fixed layer are
Magnetoresistive devices that are antiparallel to each other. In the magnetoresistive device according to claim 7.
On the second ferromagnetic fixed layer,
A first non-magnetic intermediate layer, a ferromagnetic free layer, a second non-magnetic intermediate layer, a third ferromagnetic fixed layer, a second non-magnetic coupling layer, and a fourth ferromagnetic fixed layer. , A magnetic resistance effect device in which a second antiferromagnetic layer and the protective layer are laminated. In the magnetoresistive device according to claim 10.
The third ferromagnetic fixed layer or the fourth ferromagnetic fixed layer is
Contains Co or Co—Fe alloys
The second non-magnetic bond layer is
A magnetoresistive device containing Ru or Ir. In the magnetoresistive device according to claim 10.
The magnetization direction of the third ferromagnetic fixed layer and the magnetization direction of the fourth ferromagnetic fixed layer are
Magnetoresistive devices that are antiparallel to each other. In the magnetoresistive device according to claim 1,
The magnetic particle adhesion prevention layer is
A magnetoresistive device formed from a non-magnetic or antiferromagnetic insulator. A method for manufacturing a magnetoresistive device having a plurality of elements on a substrate.
The element is arranged at a distance from the adjacent element.
A method for manufacturing a magnetoresistive device in which a magnetic particle adhesion prevention layer having a length of 100 nm or more is formed on the side surface of the device.

Images