JP2006041266A - Magnetoresistive effect element, and magnetic head and magnetic reproducing apparatus using element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an enormous resistance change rate based on a point contact between ferromagnetic substances with excellent reproducibility using a practical device structure, and indispensable when it is utilized as a magnetic reproducing head or the like. <P>SOLUTION: The magnetic resistance effect element 1 comprises a magnetization fixing layer 5 having a ferroelectric metal film of which a magnetization direction is fixed substantially in one direction, a magnetization free layer 7 having a ferromagnetic metal film of which a magnetization direction changes corresponding to an external magnetic field, an intermediate layer 6 interposed between the magnetization fixed layer 5 and the magnetization free layer 7, and a pair of electrodes 3, 4 for conducting a sense current perpendicularly to the film surface of each layer. The intermediate layer 6 includes an insulating layer 13 and a conduction 14 composed of a semi-metal compound or a semiconductor compound having a magnetic moment disposed in the insulating layer 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetoresistive effect element, a magnetic head using the same, and a magnetic reproducing apparatus.

  In recent years, a magnetoresistive effect element has been developed. In particular, with the development of a magnetoresistive film exhibiting a giant magnetoresistive effect (GMR), the performance of a magnetic device to which the magnetoresistive effect film is applied, particularly a magnetoresistive head (MR head) used as a magnetic head, is as follows. It has improved dramatically.

  As the GMR film described above, a spin valve film (Spin valve film) is known in which a large magnetoresistive effect is obtained by a sandwich structure film of a ferromagnetic layer / nonmagnetic layer / ferromagnetic layer. The spin valve film has a structure in which a nonmagnetic layer (referred to as a spacer layer or an intermediate layer) is interposed between two ferromagnetic layers. An exchange bias magnetic field is applied to one ferromagnetic layer (referred to as a pinned layer or pinned layer) to fix the magnetization, and the other ferromagnetic layer (referred to as a free layer or free layer) is used as a signal magnetic field, etc. A large magnetoresistive effect can be obtained by reversing the magnetization with an external magnetic field and changing the relative angle of the magnetization direction of the magnetization fixed layer and the magnetization free layer.

  As the MR element, a so-called CPP (Current Perpendicular to Plane) type element is proposed in which a sense current is passed in the direction perpendicular to the surface of the magnetoresistive film. The spin valve MR element is also expected to improve the MR ratio by applying the CPP structure, and it has been reported that an MR ratio about 10 times that of the CIP (Current in Plane) structure is obtained. Yes. Further, the CPP type MR element has an advantage that the resistance is lower than that of the TMR element using the tunnel effect.

  In addition, it has been reported that conduction is quantized in a portion (point contact) in which ferromagnetic metals are joined on an atomic order (see Non-Patent Document 1). This indicates that a very large resistance change rate may be obtained, and it has been reported that a very large resistance change rate of 3000% was obtained (see Non-Patent Document 2). There are various theories about the origin of this resistance change rate, but one is thought to involve conductance quantization. When the point contact is made of metal, a contact with a size of several atoms to several nanometers is necessary to quantize the conduction, and a large resistance change rate is actually only in such a very small contact portion. Observed.

  The resistance change rate based on the point contact between the ferromagnetic materials described above is only experimentally obtained, and it is indispensable to realize the point contact with a practical device structure in order to be applied to the MR head. Become. For example, as a means for realizing a point contact structure between ferromagnetic metals, it is considered to apply a semiconductor process such as a lithography technique to form a fine hole and to contact the ferromagnetic metal using the fine hole. It is done.

Furthermore, in Patent Document 1, a hole having a maximum width of 20 nm or less is provided in an insulating layer disposed between a magnetization fixed layer and a magnetization free layer as a magnetoresistive effect element using a point contact between ferromagnets. A magnetoresistive effect element in which a magnetic fine contact is formed by filling a hole with a ferromagnetic material is described. Here, a minute hole is made in the insulating layer with a needle or the like, and a ferromagnetic material is deposited on the insulating layer including the inside of the hole.
Phys. Rev. Let. 82 2923 (1999) Phys. Rev. B, 66 020403R (2002) Japanese Patent Laid-Open No. 2003-204095

  When applying the point contact structure between ferromagnets to a practical device, the above-mentioned lithography technique has a limited processing size, and it is very difficult to obtain a physical phenomenon based on conductance quantization with good reproducibility. . In Patent Document 1, since a ferromagnetic material is deposited on the insulating layer including the inside of the hole opened using a needle or the like, the ferromagnetic layer (magnetization pinned layer or magnetization free layer) and the magnetic microcontact are defined as Consists of the same ferromagnetic material. In the magnetoresistive effect element having such a structure, when a ferromagnetic metal is applied to the ferromagnetic layer, it is difficult to extract a physical phenomenon based on conductance quantization with high reproducibility as described above.

When a magnetic semiconductor or the like is applied to the ferromagnetic layer, there is a problem that the element resistance is significantly increased and the S / N ratio is deteriorated. That is, the resistance of the magnetic microcontact decreases when the conduction is quantized, but the specific resistance specific to the material is reflected as it is in the other ferromagnetic layer portion (magnetization fixed layer and magnetization free layer). For example, if both the magnetization pinned layer and the magnetization free layer with a thickness of 2 nm are made of a magnetic semiconductor having a specific resistance of 1 × 10 ⁻² Ω · m, the resistance RA per unit area is 40 Ω · μm ² , and the magnetization pinned layer When the magnetic free layer and the magnetic free layer are both magnetic metals having a specific resistance of 1 × 10 ⁻⁷ Ω · m, RA greatly exceeds 0.4 mΩ · μm ² . Thus, since the S / N ratio is deteriorated when the element resistance is increased, the magnetic reproducing head cannot be put to practical use.

  The present invention makes it possible to obtain a large resistance change rate based on a point contact between ferromagnetic materials with a practical device structure with good reproducibility, and an element resistance that is indispensable when used as a magnetic reproducing head or the like. It is an object of the present invention to provide a magnetoresistive effect element that realizes a reduction in magnetic field, a magnetic head using the same, and a magnetic reproducing apparatus.

  The magnetoresistive effect element of the present invention includes a magnetization pinned layer having a ferromagnetic metal film whose magnetization direction is fixed substantially in one direction, and a magnetization having a ferromagnetic metal film whose magnetization direction changes corresponding to an external magnetic field. A free layer, an insulating layer interposed between the magnetization pinned layer and the magnetization free layer, and disposed within the insulating layer so as to connect the magnetization pinned layer and the magnetization free layer; An intermediate layer having a conductive portion made of at least one selected from a semimetal compound and a semiconductor compound, and a sense current passed in a direction perpendicular to the film surfaces of the magnetization fixed layer, the intermediate layer, and the magnetization free layer And a pair of electrodes.

  In the magnetoresistive effect element of the present invention, the conducting portion is, for example, at least one metalloid compound selected from Fe—Si, Co—Mn—Si, Mn—Si, Cr—Si, Fe—Si, and Co—Si, Or Mn-Sb, As-Mn, Cr-As, (Ga, Mn) -As, (Ga, Cr) -As, (Ga, Mn) -N, (Ga, Cr) -N, (Zn, Fe) It is composed of at least one semiconductor compound selected from —O, (Zn, Mn) —O, and (Zn, Co) —O.

  A magnetic head according to the present invention includes the magnetoresistive element according to the present invention described above. The magnetic reproducing apparatus of the present invention comprises the magnetic head of the present invention, and is characterized in that information magnetically recorded on a magnetic recording medium is read by the magnetic head.

  In the magnetoresistive effect element of the present invention, the conductive part connecting the magnetization pinned layer and the magnetization free layer is formed of a material that exhibits a relatively large size and conductance quantization, that is, a metalloid compound having a magnetic moment, It is composed of a semiconductor compound. As a result, it is possible to quantize the conduction between the magnetization fixed layer and the magnetization free layer after applying a conductive part of a size that can be produced by a practical technique. It becomes possible to provide a magnetoresistive element exhibiting a giant magnetoresistive effect by a manufacturing technique. Furthermore, since the ferromagnetic metal film is applied to the magnetization fixed layer and the magnetization free layer, it is possible to realize a reduction in element resistance that is indispensable when used as a magnetic reproducing head or the like.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing the structure of a magnetoresistive element according to an embodiment of the present invention. The magnetoresistive effect element 1 shown in FIG. 1 is provided so as to pass a sense current in a direction perpendicular to the magnetoresistive effect film 2 having a spin valve structure and the film surface of the spin valve magnetoresistive effect film 2. It is mainly composed of a pair of electrodes 3 and 4. The spin valve magnetoresistive film 2 enhances the practicality of the magnetoresistive element 1.

  The spin valve magnetoresistive film 2 has a laminated film structure of a fixed magnetization layer 5 / intermediate layer 6 / magnetization free layer 7 structure. That is, an antiferromagnetic layer 9 made of a Pt—Mn alloy, an Ir—Mn alloy, or the like is formed on the lower electrode 3 via the underlayer 8. On the antiferromagnetic layer 9, a ferromagnetic metal film to be the magnetization pinned layer 5 is formed. This ferromagnetic metal film has its magnetization direction fixed substantially in one direction by the exchange bias magnetic field from the antiferromagnetic layer 9, whereby the ferromagnetic metal film functions as the magnetization fixed layer 5.

  The magnetization pinned layer 5 is not limited to the single-layered ferromagnetic film shown in FIG. 1, and may have a laminated structure. FIG. 2 shows a magnetization pinned layer 5 made of a laminated film in which ferromagnetic metal films 11 and 12 are arranged on both sides of a magnetization antiparallel coupling layer 10 made of Ru or the like. In this structure, the ferromagnetic metal film 11 is fixed in one direction by the antiferromagnetic layer 9, and the ferromagnetic metal films 11 and 12 are in an antiparallel state through the magnetization antiparallel coupling layer 10. Are connected. A ferromagnetic metal material such as Fe, Co, Ni, an alloy of these elements, or an alloy containing these elements as a main component is applied to the ferromagnetic metal film constituting the magnetization pinned layer 5.

  A ferromagnetic metal film functioning as the magnetization free layer 7 is formed on the magnetization pinned layer 5 via the intermediate layer 6. This ferromagnetic metal film has a magnetization direction that changes in response to an external magnetic field such as a signal magnetic field, thereby functioning as a magnetization free layer 7. The ferromagnetic metal film constituting the magnetization free layer 7 is made of, for example, a ferromagnetic metal material such as Fe, Co, Ni, an alloy of these elements, or an alloy containing these elements as a main component, similarly to the magnetization fixed layer 5. used. Further, the structure of the magnetization free layer 7 is not limited to a single layer structure, and a laminated structure including a ferromagnetic metal film can be applied. In any case, the magnetic pinned layer 5 and the magnetic free layer 7 are made of a ferromagnetic metal material in order to realize a practical element resistance.

  The film thickness of the magnetization pinned layer 5 and the magnetization free layer 7 is not particularly limited, but is preferably 10 nm or less, for example. 1 and 2 show the spin valve magnetoresistive film 2 in which the magnetization pinned layer 5 is arranged on the lower layer side, the positions of the magnetization pinned layer 5 and the magnetization free layer 7 may be reversed. That is, it is also possible to apply a film structure in which the magnetization pinned layer 5 is disposed on the lower layer side and the magnetization pinned layer 7 is disposed thereon via the intermediate layer 6. The magnetization pinned layer 5 and the magnetization free layer 7 having such a ferromagnetic metal film realize a low element resistance with respect to a sense current flowing in the direction perpendicular to the film surface. It is possible to obtain practicality when applied to a reproducing head or the like, that is, an excellent S / N ratio or the like.

  The intermediate layer 6 interposed between the magnetization pinned layer 5 and the magnetization free layer 7 described above includes an insulating portion 13 and a conducting portion 14. The insulating portion 13 constitutes the entire shape of the intermediate layer 6, and is arranged in layers between the magnetization pinned layer 5 and the magnetization free layer 7. In such a layered insulating portion (insulating layer) 13, at least one conducting portion 14 is disposed so as to connect the magnetization fixed layer 5 and the magnetization free layer 7. For the insulating portion (insulating layer) 13, a metal oxide, metal carbide, metal nitride, or the like having an electrically conductive property is used. Specific examples of such compounds include Al, Ta, Cr, Hf, Mg, Cu, Ca, Ba, Sr, Zr, Li, Ti, Nb, Mo, Si, Y, oxides and carbides of rare earth elements, etc. And nitride.

  The conducting part 14 disposed in the insulating part 13 realizes point contact between the magnetization fixed layer 5 and the magnetization free layer 7. This point contact preferably achieves quantized conduction. When the conductive portion 14 is made of metal, the point contact size needs to be several nm or less in order to develop conductance quantization as described above, and such a conductive portion 14 is accurately manufactured. It ’s difficult. Therefore, in the magnetoresistive effect element 1 of this embodiment, the conducting portion 14 is made of a material that exhibits a conductance quantization with a relatively large size, that is, a metalloid compound or a semiconductor compound having a magnetic moment.

  As shown in FIG. 3, the magnitude D at which conductance quantization appears in the case of the metal M is several nanometers or less (see FIG. 3A), whereas in the case of the semimetal SM, the magnitude D is several. Conductance quantization occurs at a size of 10 nm or less (see FIG. 3B), and in the case of a semiconductor SC, a size of several μm or less (see FIG. 3C). Therefore, the conduction between the magnetization fixed layer 5 and the magnetization free layer 7 in the conduction part 14 having a size D that can be practically produced by forming the conduction part 14 with a metalloid compound or a semiconductor compound having a magnetic moment. Can be quantized.

  Specifically, when the conduction part 14 is formed of a metalloid compound having a magnetic moment, the size (maximum width) of the conduction part 14 can be 20 nm or less. Moreover, when the conduction | electrical_connection part 14 is formed with the semiconductor compound which has a magnetic moment, the magnitude | size (maximum width) of the conduction | electrical_connection part 14 can be 1 micrometer or less. Note that the minimum value of the size of the conductive portion 14 is not particularly limited, but the size of the conductive portion 14 is 5 nm in consideration of the size that can be stably manufactured by various methods described later. The above is preferable.

  Thus, by connecting the magnetization pinned layer 5 and the magnetization free layer 7 with the conduction portion 14 formed of a metalloid compound or semiconductor compound having a magnetic moment, for example, the conduction portion 14 has a size of 10 nm or more. Even so, the conduction can be quantized. That is, the conduction between the magnetization fixed layer 5 and the magnetization free layer 7 can be quantized after applying the conduction portion 14 having a practical size. In other words, the conduction between the magnetization pinned layer 5 and the magnetization free layer 7 can be quantized with a practical device structure and device manufacturing technology. According to such a quantized conducting portion 14, a new physical phenomenon based on the magnetoresistive effect based on the change in the magnetization direction of the magnetization fixed layer 5 and the magnetization free layer 7, that is, a physical phenomenon based on the quantization of conduction. In consideration of this, it is possible to obtain a huge magnetoresistance effect.

  The number of conduction portions 14 connecting the magnetization pinned layer 5 and the magnetization free layer 7 described above should be small, and ideally, it should be one. However, from the viewpoint of obtaining the quantized conducting part 14 with good reproducibility, it is preferable to arrange a plurality of conducting parts 14 in the insulating part 13. That is, although the resistance change rate itself of the magnetoresistive effect element 1 is reduced by using a plurality of conducting portions 14, even if the conducting portion 14 with incomplete quantization is generated, A large resistance change rate can be stably obtained by quantizing the conductive portion 14.

  Here, although the material which comprises the conduction | electrical_connection part 14 may be any of a metalloid compound and a semiconductor compound, it is preferable to apply a metalloid compound from the point of reproducibility of conduction quantization. Moreover, although a semiconductor has a large resistance, there is no problem if the resistance of the conductive portion 14 is lowered due to quantization of conduction. However, if the quantization is incomplete, the metalloid has the advantage of being easier to use because it has a lower resistance than a semiconductor. Also from such a point, it is preferable that the conducting portion 14 is formed of a metalloid compound having a magnetic moment.

Specifically, the resistance value of a semiconductor at room temperature is approximately several hundred μΩ · m to several hundred MΩ · m, while that of a semimetal is as small as several μΩ · m to several hundred μΩ · m. Incidentally, the metal is several tens of nΩ · m to several μΩ · m. The resistance RA per unit area (product of the resistance R of the element itself and the element area A) when the thickness of the intermediate layer 6 is 1 nm is estimated as follows. In the magnetoresistive effect element 1 of this embodiment, the current concentrates on the conducting part 14, so that it can be said that the resistance of the element 1 is almost determined by the resistance value of the conducting part 14. In a semiconductor, when the resistance RA is several tens mΩ · μm ² to several hundred GΩ · μm ² , and the two-dimensional size of the conductive portion 14 is 10 nm × 10 nm square, the element resistance is several hundred Ω or more by itself. Become. On the other hand, in the case of a semimetal, the above-described element resistance becomes the upper limit, and actually the element resistance is lower than this. Therefore, in consideration of the case where the quantization is incomplete, it is preferable that the conductive portion 14 is formed of a metalloid compound.

  The conducting part 14 disposed in the insulating part 13 constituting the intermediate layer 6 is formed of a metalloid compound or a semiconductor compound having a magnetic moment. Examples of metalloid compounds having a magnetic moment include Fe-Si compounds, Co-Mn-Si compounds, Mn-Si compounds, Cr-Si compounds, Fe-Si compounds, Co-Si compounds, and the like. Can be mentioned. Examples of the semiconductor compound having a magnetic moment include a Mn—Sb compound, an As—Mn compound, a Cr—As compound, a (Ga, Mn) —As compound, a (Ga, Cr) —As compound, (Ga , Mn) -N compounds, (Ga, Cr) -N compounds, (Zn, Fe) -O compounds, (Zn, Mn) -O compounds, (Zn, Co) -O compounds, and the like. It is done.

Among the semi-metal compounds described _{above, Fe 3 Si, Fe 5 Si} 3, Co 2 MnSi is a metalloid compound exhibiting ferromagnetism even above room temperature. These Curie point 550 ° C., respectively, 100 ° C., at 712 ℃, 2.4μ _B is in the magnetic moment of Fe ₃ Si at room temperature, 1.2μ _B, 1.05μ _B is in _{Fe 5 Si 3, 1.55μ B,} Co is in ₂ MnSi is demanded Co = 0.75μ _B, and Mn = 3.57μ _B. Unlike metals, metalloids are quantized even when the size is 10 nm or more, so that a large amount of magnetoresistance change can be stably obtained. Even if the composition is slightly deviated from the above-described compound composition, since the magnetization fixed layer 5 and the magnetization free layer 7 are ferromagnetic, ferromagnetism is also induced in the conduction portion 14 and a large amount of change in magnetoresistance is expected. it can.

MnSi and (Co _100-x Mn _x ) ₅₀ Si ₅₀ (30 ≦ x ≦ 80) are semimetals that exhibit ferromagnetism at room temperature or lower. Since the Curie point is not more than room temperature, it is Curie paramagnetism. However, since the Curie point is also in contact with the magnetization fixed layer 5 and the magnetization free layer 7 which are ferromagnetic materials, the conduction portion 14 is also ferromagnetic. Induced. Therefore, a large magnetoresistance change amount can be obtained. Even when the above-described compounds are slightly deviated from the composition, ferromagnetism is induced by the magnetization fixed layer 5 and the magnetization free layer 7 and it is expected to show a large amount of change in magnetoresistance. In particular, Mn—Si is a material system that easily has a magnetic moment because it exhibits various magnetisms as described below.

Mn ₃ Si, Mn ₅ Si ₃ , and MnSi _1.72 are semimetals each having a magnetic moment at low temperatures and exhibiting screw magnetism, antiferromagnetism, and metamagnetism. Since it has a magnetic moment at a low temperature, ferromagnetism is also induced in the conduction portion 14 by being sandwiched between the magnetization fixed layer 5 and the magnetization free layer 7. Therefore, a large magnetoresistance change amount can be obtained. These compounds are also expected to show a large change in magnetoresistance due to induction of ferromagnetism, even if the composition is slightly deviated. CrSi, FeSi, CoSi are Curie paramagnetic semimetals that do not have magnetic order even at low temperatures but have a magnetic moment. These are also sandwiched between the magnetization pinned layer 5 and the magnetization free layer 7 so that magnetic order is generated, and a large magnetoresistance change amount can be obtained. In addition, these compounds can be expected to have the same effect even if their compositions are slightly deviated.

  Of the semiconductor compounds having a magnetic moment, MnSb, AsMn, CrAs and the like are semiconductors that are theoretically predicted to exhibit half-metallic ferromagnetism. A half metal is a material that has up spin electrons at the Fermi level but does not have down spin electrons, that is, only up spin is conducted, and exhibits a large amount of change in magnetoresistance. When such a material is used for the conducting portion 14, not only the giant magnetoresistance effect based on the above-described conduction quantization but also the effect of conducting only upspin can be obtained, and thus a larger amount of magnetoresistance change is exhibited. It will be.

  As described above, the material constituting the conducting portion 14 is not limited to a semimetal or semiconductor exhibiting ferromagnetism, or a semimetal or semiconductor having a magnetic moment at room temperature, but a semimetal or semiconductor having a magnetic moment at a low temperature. Furthermore, metalloids or semiconductors which do not have magnetic order even at low temperatures but have a magnetic moment can be used. As described above, various metalloid compounds or semiconductor compounds having a magnetic moment can be applied to the constituent material of the conducting portion 14, and the material system is not limited to the above-described material system.

  The film thickness of the intermediate layer 6 composed of the insulating part 13 and the conductive part 14 is, for example, to improve the formability of the fine conductive part 14 and the formability of the quantized point contact by the conductive part 14. The thickness is preferably 5 nm or less. The film thickness of the intermediate layer 6 is more preferably 3 nm or less. Note that the film thickness of the intermediate layer 6 is preferably set to 1 nm or more in consideration of the uniform film formability of the insulating material (insulating portion 13). The intermediate layer 6 only needs to have the conduction portion 14 in contact with the magnetization fixed layer 5 and the magnetization free layer 7. For example, as shown in FIGS. 4, 5, and 6, the intermediate layer 6 may be extended above and below the insulating portion 13. Good. FIG. 4 shows a state in which the extended conductive portion 14 </ b> A exists above the insulating portion 13. FIG. 5 shows a state in which a conductive portion 14B extended below the insulating portion 13 exists, and FIG. 6 shows a state in which conductive portions 14A and 14B extended above and below the insulating portion 13 exist.

  The intermediate layer 6 having the conductive portion 14 as described above can be manufactured by applying, for example, a normal lithography technique, or using an agglomeration phenomenon caused by a needle drilling technique, heat treatment, or the like. FIG. 7 shows an example of the formation process of the intermediate layer 6 to which the lithography technique is applied. First, after forming the insulating layer 15 to be the insulating portion 13 on the magnetization pinned layer 5, a resist pattern 16 is formed on the insulating layer 15 by lithography (FIG. 7A). Next, a portion of the insulating layer 15 other than that covered with the resist 16 is removed by etching, for example, by RIE (Reactive Ion Etching) to form a contact hole 17 that becomes the conductive portion 14 (FIG. 7B).

  Next, a material for forming the conductive portion 14, that is, a metalloid compound or a semiconductor compound having a magnetic moment is deposited in the contact hole 17 (FIG. 7C). Subsequently, the resist 16 is removed to obtain the intermediate layer 6 in which the conductive portion 14 made of a semimetal compound or a semiconductor compound having a magnetic moment is disposed in the insulating portion 13 (FIG. 7D). Thereafter, a magnetization free layer 7 is formed on the intermediate layer 6 to obtain a laminated film having a spin valve structure (FIG. 7E).

  The contact hole 17 to be the conductive portion 14 can also be formed by applying a lift-off method as shown in FIG. That is, a resist pattern 16 is formed on the magnetization pinned layer 5 by a lithography technique (FIG. 8A). Next, after forming an insulating layer 15 to be the insulating portion 13 (FIG. 8B), the resist 16 is removed (FIG. 8C). After the contact hole 17 is formed in the insulating layer 15 in this way, the deposition of the semimetal compound or semiconductor compound having a magnetic moment that becomes the conduction portion 14 (FIG. 8D) and the film formation of the magnetization free layer 7 are performed. Are sequentially performed to obtain a laminated film having a spin valve structure (FIG. 8E). In FIG. 8, the material for forming the conductive portion 14 extends to the upper side of the insulating portion 13, but there is no particular problem if the conductive portion 14 is in contact with the magnetization fixed layer 5 and the magnetization free layer 7 as described above.

  Formation of the contact hole 17 with respect to the insulating layer 15 can also be performed using a needle-shaped thing, for example. That is, the insulating layer 15 is formed on the magnetization pinned layer 5 (FIG. 9A). Next, for example, an STM needle or template is pressed against the insulating layer 15 to form the contact hole 17 (FIG. 9B). Alternatively, the contact hole 17 may be formed by passing a large current by bringing the needle close to the insulating layer 15. Thereafter, the deposition of the conduction portion 14 (FIG. 9C) and the film formation of the magnetization free layer 7 (FIG. 9D) are sequentially performed.

  Furthermore, the contact hole 17 can be formed by agglomeration by heat treatment of the insulating layer, or agglomeration by an ion beam or plasma. For example, after depositing a layer (Si, Al, etc.) as a base of the insulating layer, it is heated and aggregated to form a sea island, which is formed into an insulating layer by oxidation or the like. Further, instead of heating, energy such as an ion beam or plasma may be applied to the surface of the insulating layer or a layer that is a source of the insulating layer to form a sea island. After forming the contact hole 17 by these methods, the deposition of the conduction portion and the formation of the magnetization free layer are sequentially performed, whereby a laminated film having a spin valve structure as shown in FIG. 9D is obtained.

  The magnetization free layer 7 is disposed on the intermediate layer 6 described above, and the upper electrode 4 is disposed thereon via a protective layer 18. In the spin valve magnetoresistive film 2 having a laminated film of the magnetization pinned layer 5 / intermediate layer 6 / magnetization free layer 7 structure, sensing is performed in a direction perpendicular to the film surface from the lower and upper electrodes 3 and 4 provided on the upper and lower sides thereof. Current is energized. The magnetoresistive effect element 1 changes the magnetization direction of the magnetization free layer 7 by an external magnetic field such as a signal magnetic field, and develops the magnetoresistive effect based on the relative magnetization direction with the magnetization fixed layer 5 at that time. is there.

  In such a magnetoresistive effect element 1, the conductive portion 14 that connects the magnetization fixed layer 5 and the magnetization free layer 7 is a material that exhibits conductance quantization even with a relatively large size, that is, a metalloid compound having a magnetic moment. Since it is composed of a semiconductor compound, a quantized point contact can be obtained with good reproducibility. Therefore, it is possible to stably develop a giant magnetoresistance effect based on conduction quantization or the like with respect to a sense current that flows in the direction perpendicular to the film surface of the spin valve magnetoresistive film 2. Furthermore, since the magnetization fixed layer 5 and the magnetization free layer 7 are composed of a ferromagnetic metal film, a practical element resistance can be obtained.

  The magnetoresistive effect element 1 of the above-described embodiment is used as a constituent element such as a magnetic head in the same manner as a conventional magnetoresistive effect element. A magnetic head using the magnetoresistive effect element 1 is used for reading information magnetically recorded on a magnetic recording medium. Various magnetic reproducing apparatuses are configured using such a magnetic head. Further, the magnetoresistive effect element 1 is not limited to a magnetic head but can be used as a constituent element of a magnetic storage device such as a magnetic memory.

  Next, specific examples of the present invention and evaluation results thereof will be described.

Example 1
In Example 1, the magnetoresistive effect element 1 having the structure shown in FIG. 2 was produced. That is, in the magnetoresistive effect element 1 whose structure is shown in FIG. 2, a laminated film of a Ta film having a thickness of 5 nm and a NiFeCr alloy film having a thickness of 2 nm is applied to the base layer 8 of the spin valve magnetoresistive film 2. A PtMn alloy film having a thickness of 15 nm was formed as an antiferromagnetic layer 9 on the underlayer 8. Further, a 2 nm thick Co ₉₀ Fe ₁₀ alloy film 11, a 1 nm thick Ru film 10 and a 2 nm thick Co ₉₀ Fe ₁₀ alloy film 12 were sequentially formed thereon as the magnetization pinned layer 5.

Next, the intermediate layer 6 having the insulating portion 13 and the conductive portion 14 was formed on the magnetization pinned layer 5. SiO ₂ was applied to the insulating part 13 and Fe ₃ Si was applied to the conductive part 14. The intermediate layer 6 was produced by applying the manufacturing process shown in FIG. The size of the conductive portion 14 is 20 nm × 20 nm, and the number of the conductive portions 14 is one. That is, one conductive portion 14 made of Fe ₃ Si was disposed in a ₂ nm thick SiO ₂ layer with a size of 20 nm × 20 nm. Thereafter, a Co ₉₀ Fe ₁₀ alloy film having a thickness of 1 nm and a Ni ₈₀ Fe ₂₀ alloy film having a thickness of 3 nm are sequentially formed on the intermediate layer 6 as the magnetization free layer 7, and further a protective layer 18 having a thickness of 1 nm is formed thereon. Cu film, 5 nm thick Ta film, and 10 nm thick Ru film were formed in this order.

The laminated film (spin valve type magnetoresistive film 2) described above was patterned by lithography to a size of 1 μm × 1 μm, and electrodes were arranged above and below it. When the MR change rate of the magnetoresistive effect element thus obtained was measured, it showed a large value of 100%. The element resistance was 0.3 Ω · μm ² .

Examples 2-33
In the first embodiment described above, the spin valve type is used under the same conditions as in the first embodiment except that the constituent material of the insulating portion 13 and the constituent material, size, and number of the conductive portions 14 are changed to the conditions shown in Table 1. A magnetoresistive film 2 was produced. The intermediate layer forming process was the same as in Example 1. The laminated film thus obtained was patterned to the same element size as in Example 1 to produce a magnetoresistive element. The MR change rate of these magnetoresistive effect elements was measured. The results are also shown in Table 1.

As is clear from Table 1, it can be seen that a large MR ratio is obtained in the magnetoresistive effect elements of the respective examples. In addition to the intermediate layer forming step shown in FIG. 7, similar results were obtained when the forming step shown in FIGS. 8 and 9 and the forming step utilizing aggregation were applied. In addition, when the number and size of the conductive portions were controlled, in Examples 1 to 24, the same effect was obtained even if trials were performed from several nm to 100 nm. The size of the part is desirably 20 nm × 20 nm or less. In Examples 25-33, the same effect was obtained with a size of 1 μm × 1 μm, but the resistance change rate decreased as the crystallinity and the like decreased. Therefore, it is desirable that the size of the conductive portion is 500 nm × 500 nm or less, and further 100 nm × 100 nm or less. The same effect can be obtained when Fe ₅₀ Co ₅₀ , Fe, Fe—Co—Ni alloy or the like is used for the ferromagnetic metal film constituting the magnetization fixed layer and the magnetization free layer.

It is sectional drawing which shows typically the structure of the magnetoresistive effect element by one Embodiment of this invention. It is sectional drawing which shows the modification of the magnetoresistive effect element shown in FIG. It is a figure for demonstrating the magnitude | size from which the conduction in a metal, a semimetal, and a semiconductor begins to be quantized. It is sectional drawing which shows the modification of the intermediate | middle layer in the magnetoresistive effect element shown in FIG. It is sectional drawing which shows the other modification of the intermediate | middle layer in the magnetoresistive effect element shown in FIG. FIG. 10 is a cross-sectional view showing still another modification of the intermediate layer in the magnetoresistive element shown in FIG. 1. It is sectional drawing which shows an example of the principal part manufacturing process of the spin valve type | mold magnetoresistive effect film | membrane in the magnetoresistive effect element shown in FIG. It is sectional drawing which shows the other example of the principal part manufacturing process of the spin valve type magnetoresistive film in the magnetoresistive effect element shown in FIG. FIG. 10 is a cross-sectional view showing still another example of a main part manufacturing process of the spin valve magnetoresistive film in the magnetoresistive element shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnetoresistance effect element, 2 ... Spin valve type magnetoresistive effect film, 3, 4 ... Electrode, 5 ... Magnetization fixed layer, 6 ... Intermediate | middle layer, 7 ... Magnetization free layer, 13 ... Insulation part, 14 ... Conduction part.

Claims (7)

A magnetization pinned layer having a ferromagnetic metal film in which the magnetization direction is substantially pinned in one direction;
A magnetization free layer having a ferromagnetic metal film whose magnetization direction changes in response to an external magnetic field;
An insulating layer interposed between the magnetization pinned layer and the magnetization free layer, and a metalloid compound disposed in the insulating layer so as to connect the magnetization pinned layer and the magnetization free layer and having a magnetic moment And an intermediate layer having at least one conductive portion selected from semiconductor compounds,
A magnetoresistive effect element comprising: a pair of electrodes provided to pass a sense current in a direction perpendicular to the film surfaces of the magnetization pinned layer, the intermediate layer, and the magnetization free layer. The magnetoresistive effect element according to claim 1,
The conducting portion is composed of at least one metalloid compound selected from Fe-Si, Co-Mn-Si, Mn-Si, Cr-Si, Fe-Si, and Co-Si. Effect element. The magnetoresistive effect element according to claim 1,
The conducting portion includes Mn—Sb, As—Mn, Cr—As, (Ga, Mn) —As, (Ga, Cr) —As, (Ga, Mn) —N, (Ga, Cr) —N, ( A magnetoresistive effect element comprising at least one semiconductor compound selected from Zn, Fe) -O, (Zn, Mn) -O, and (Zn, Co) -O. A magnetization pinned layer having a ferromagnetic metal film in which the magnetization direction is substantially pinned in one direction;
A magnetization free layer having a ferromagnetic metal film whose magnetization direction changes in response to an external magnetic field;
An insulating layer interposed between the magnetization pinned layer and the magnetization free layer, and disposed in the insulating layer so as to connect the magnetization pinned layer and the magnetization free layer, Fe-Si, Co-Mn An intermediate layer having a conductive portion made of at least one metalloid compound selected from -Si, Mn-Si, Cr-Si, Fe-Si, and Co-Si;
A magnetoresistive effect element comprising: a pair of electrodes provided to pass a sense current in a direction perpendicular to the film surfaces of the magnetization pinned layer, the intermediate layer, and the magnetization free layer. A magnetization pinned layer having a ferromagnetic metal film in which the magnetization direction is substantially pinned in one direction;
A magnetization free layer having a ferromagnetic metal film whose magnetization direction changes in response to an external magnetic field;
An insulating layer interposed between the magnetization pinned layer and the magnetization free layer, and disposed in the insulating layer so as to connect the magnetization pinned layer and the magnetization free layer, Mn-Sb, As-Mn Cr-As, (Ga, Mn) -As, (Ga, Cr) -As, (Ga, Mn) -N, (Ga, Cr) -N, (Zn, Fe) -O, (Zn, Mn) An intermediate layer having a conductive portion made of at least one semiconductor compound selected from -O and (Zn, Co) -O;
A magnetoresistive effect element comprising: a pair of electrodes provided to pass a sense current in a direction perpendicular to the film surfaces of the magnetization pinned layer, the intermediate layer, and the magnetization free layer.   6. A magnetic head comprising the magnetoresistive effect element according to claim 1. A magnetic reproducing apparatus comprising the magnetic head according to claim 6, wherein information magnetically recorded on a magnetic recording medium is read by the magnetic head.

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