JP2003060261A - Magnetoresistive effect film, memory element, and memory therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistive effect film which is easy to fabricate for reducing a magnetization reverse field of a vertical magnetized film, without causing reduction in yield or a significant increase in cost, and to provide a memory with small power consumption. SOLUTION: A first magnetic film 111, having magnetized orientation slanted to a vertical direction of the film face in a zero magnetic field and in non-exchange force with another magnetic body, a second magnetic film 112 as a vertically magnetized film, a non-magnetic film 113, and a third magnetic film 114 as a vertically magnetized film, are formed sequentially. The first magnetic film and the second magnetic film are put in exchange coupling. The second magnetic film is so formed that the magnetization is orientated in the vertical direction of the film face, at least near to an interface with the non-magnetic film in a non-magnetic field, or oriented easily in the vertical direction of the film face, when the field is applied in the vertical direction of the film face. The magnetic film, having magnetization slanted to the vertical direction of film face in a zero-magnetic field and in non-exchange force with another magnetic body, is made to exchange couple with the vertically magnetized film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive effect film using a method of reducing a magnetization reversal field of a perpendicular magnetization film, a memory device having the same, and a memory using the same.

[0002]

2. Description of the Related Art In recent years, semiconductor memories, which are solid-state memories, have been widely used in information equipment, and DRAM, FeRAM, flash EEP
There are various types such as ROM. The characteristics of these semiconductor memories have advantages and disadvantages, and there is no memory that meets all of the specifications required in current information devices. For example, DRAM has a high recording density and a large number of rewritable times,
It is volatile and loses information when the power is turned off. Also,
Flash EEPROM is non-volatile, but it takes a long time to erase,
It is not suitable for high-speed processing of information.

In contrast to the current state of the semiconductor memory as described above, a memory (MRAM) using the magnetoresistive effect is
It is promising as a memory that meets all the specifications required by many information devices in terms of read time, recording density, number of rewritable times, power consumption, and the like. In particular, MRAM using the spin-dependent tunneling magnetoresistance (TMR) effect is advantageous for high recording density or high-speed read because a large read signal can be obtained.
The feasibility as MRAM has been proven.

The basic structure of the magnetoresistive film used as an element of the MRAM is a sandwich structure in which magnetic layers are formed adjacent to each other with a nonmagnetic layer interposed therebetween. Cu and Al ₂ O ₃ are examples of materials that are often used as the non-magnetic film. A magnetoresistive film that uses a conductor such as Cu for the non-magnetic layer is called a giant magnetoresistive film (GMR film), and a film that uses an insulator such as Al ₂ O ₃ is a spin-dependent tunnel magnetoresistive film. It is called an effect film (TMR film). Generally, the TMR film exhibits a larger magnetoresistive effect than the GMR film.

When the magnetization directions of the two magnetic layers are parallel as shown in FIG. 13A, the electric resistance of the magnetoresistive film is relatively small, and the magnetization directions are antiparallel as shown in FIG. 13B. Then, the electric resistance becomes relatively large. Therefore,
Information can be read by using one of the magnetic layers as a recording layer and the other as a reading layer and utilizing the above properties. For example, the magnetic layer 13 located above the non-magnetic layer 12 is the recording layer, the magnetic layer 14 located below is the reading layer, and the magnetization direction of the recording layer is "1" when the magnetization direction is right, and "0" when the magnetization direction is left. And When the magnetization directions of both magnetic layers are rightward as shown in FIG. 14A, the electric resistance of the magnetoresistive film is relatively small, and as shown in FIG. 14B, the magnetization direction of the read layer is rightward and When the magnetization direction of the recording layer is leftward, the electric resistance is relatively large. Further, as shown in FIG. 14C, when the magnetization direction of the read layer is leftward and the magnetization direction of the recording layer is rightward, the electric resistance is relatively large, and FIG.
As shown in, the electric resistance is relatively small when the magnetization directions of both magnetic layers are leftward. That is, if the magnetization direction of the read layer is fixed to the right and the electric resistance is large,
"0" is recorded in the recording layer, and if the electric resistance is small, "1" is recorded.
Alternatively, if the magnetization direction of the read layer is fixed to the left and the electrical resistance is high, then “1” is added to the recording layer.
Is recorded, and if the electric resistance is small,
"0" is recorded.

When the element size is reduced in order to increase the recording density of the MRAM, the MRAM using the in-plane magnetized film cannot hold information due to the demagnetizing field or the curling of the end surface magnetization. Occurs. In order to avoid this problem, for example, the shape of the magnetic layer may be made rectangular. However, since the element size cannot be reduced by this method, improvement in recording density is not expected so much. Therefore, for example, as described in Japanese Patent Laid-Open No. 11-213650, a proposal has been made to avoid the above problem by using a perpendicular magnetization film. With this method, the demagnetizing field does not increase even if the element size is reduced,
It is possible to realize a magnetoresistive film having a size smaller than that of an MRAM using an in-plane magnetized film.

The magnetoresistive effect film using the perpendicular magnetization film has the same electric resistance as the magnetoresistive effect film using the in-plane magnetization film when the magnetization directions of the two magnetic layers are parallel to each other. If it is relatively small and the magnetization directions are antiparallel, the electrical resistance becomes relatively large. A magnetic layer located above the non-magnetic layer 22
23 is a recording layer, and the magnetic layer 21 located below is a reading layer. The magnetization direction of the recording layer is "1" when the magnetization direction is upward, and "0" when the magnetization direction is downward. When the magnetization directions of both magnetic layers are upward as shown in FIG. 15A, the electric resistance of the magnetoresistive film is relatively small, and as shown in FIG. 15C, the magnetization direction of the read layer is downward and If the magnetization direction of the recording layer is upward, the electric resistance becomes relatively large. Therefore,
When a magnetic field is applied so that the magnetization direction of the readout layer is upward with "1" recorded, and then a magnetic field is applied so that the magnetization direction of the readout layer is downward, the electrical resistance of the magnetoresistive film is increased. Changes so that it becomes larger, and "1" can be read from this change. However,
The magnetic field applied during reading has a magnitude such that the magnetization direction of the recording layer does not change. When the magnetization direction of the read layer is upward and the magnetization direction of the recording layer is downward as shown in FIG. 15B, the electric resistance becomes relatively large, and as shown in FIG. When the magnetization direction is downward, the electric resistance becomes relatively small. Therefore,
When "0" is recorded, the read operation changes so that the electric resistance decreases, so that "0" can be read.

[0008]

As the perpendicular magnetization film,
An alloy film or artificial lattice film of at least one element selected from rare earth metals such as Gd, Dy and Tb and at least one element selected from transition metals such as Co, Fe and Ni, and transition metals such as Co / Pt An artificial lattice film of a noble metal and an alloy film such as CoCr having crystal magnetic anisotropy in the direction perpendicular to the film surface are mainly mentioned. The magnetization reversal field of a perpendicular magnetization film is generally larger than that having an in-plane magnetic anisotropy due to a transition metal. For example, the magnetization reversal field of permalloy, which is an in-plane magnetization film, is about several hundred A / m. In the case of a Co / Pt artificial lattice film which is a perpendicular magnetization film, it is remarkably large at about several tens kA / m. In an alloy film of a rare earth metal and a transition metal, the sublattice magnetization of the rare earth metal and the sublattice magnetization of the transition metal are antiparallel to each other, so that the apparent magnetization magnitude differs depending on the film composition. Therefore, the magnetization reversal field differs depending on the composition. The GdFe alloy film has a relatively small magnetization reversal magnetic field among the alloy films of rare earth metals and transition metals, but the magnetization reversal is usually about several thousand A / m near the critical composition where the squareness ratio of the magnetization curve starts to decrease from 1. Has a magnetic field.

When a sensor, a memory or the like is composed of a magnetoresistive film using a perpendicular magnetization film, it does not operate unless a large magnetic field is applied for the above reason. Therefore, for example, it is necessary to concentrate the stray magnetic field in the magnetic layer of the magnetoresistive film in the sensor, and it is necessary to devise to generate a large magnetic field in the memory. The magnetic field applied to the memory generally causes a current to flow through the conductive wire to generate the current, but especially in the case of a memory used for a mobile terminal, it is not preferable to flow a large current due to the restriction of the power supply capacity. For this reason, for example, it is necessary to take measures such as winding a conducting wire for generating a magnetic field around the memory element made of the magnetoresistive film. However, such a measure complicates the structure around the magnetoresistive effect film and the electric circuit, which makes it difficult to manufacture the magnetoresistive film, resulting in a decrease in yield and a significant increase in cost.

In view of this point, the present invention provides a magnetoresistive effect film which reduces the magnetization reversal magnetic field of the perpendicular magnetization film, is easy to manufacture, and does not cause a decrease in yield or a significant increase in cost. It is an object to provide a memory with low power consumption.

[0011]

The magnetoresistive film of the present invention is a magnetoresistive film having a structure in which a non-magnetic film is sandwiched between magnetic films, and at least one of the magnetic films is a perpendicular magnetization film. , A magnetic film having an easy axis of magnetization inclined from the direction perpendicular to the film surface at a position in contact with the perpendicular magnetic film and not in contact with the non-magnetic film.

Further, the easy axis of at least one of the magnetic films may be inclined from the direction perpendicular to the film surface.

The magnetic film may be exchange-coupled with the magnetic film whose easy axis of magnetization is inclined from the direction perpendicular to the film surface. Further, a layer having a spin polarizability larger than that of the perpendicular magnetic film may be inserted between the perpendicular magnetic film and the non-magnetic film.

Further, the perpendicular magnetization film and the layer having a large spin polarization may be exchange-coupled.

Further, a first magnetic film having an axis of easy magnetization inclined from a direction perpendicular to the film surface, a second magnetic film, and a non-magnetic film,
A third magnetic film and a fourth magnetic film having an easy axis of magnetization inclined from the direction perpendicular to the film surface are formed in this order, and at least one of the second magnetic film and the third magnetic film is perpendicularly magnetized. The first magnetic film and the second magnetic film, and the third magnetic film and the fourth magnetic film may be exchange-coupled, respectively.

Further, the easy magnetization axis of at least one of the second magnetic film and the third magnetic film may be inclined from the direction perpendicular to the film surface.

A layer having a spin polarizability larger than that of the second magnetic film may be formed between the second magnetic film and the non-magnetic film.

Further, a layer having a spin polarizability larger than that of the third magnetic film may be formed between the third magnetic film and the non-magnetic film.

Further, the layer having a large spin polarization and the second magnetic film, and the layer having a large spin polarization and the third magnetic film may be exchange-coupled.

The layer having a large spin polarizability may have a grain shape.

The magnetization of the magnetic film whose easy axis of magnetization is inclined from the direction perpendicular to the film surface may be oriented in the direction perpendicular to the film surface by a magnetic field having a magnitude of 4 kA / m or less.

Further, in a state where the magnetization of the magnetic film whose easy axis of magnetization is oriented in a direction inclined from the direction perpendicular to the film surface is exchange-coupled with the perpendicular magnetization film, at least partially with respect to the direction perpendicular to the film surface. You may lean.

The perpendicularly magnetized film may be a ferrimagnetic material.

Further, the ferrimagnetic material may be an alloy of a rare earth metal and a transition metal.

The alloy of rare earth metal and transition metal may be amorphous.

The ferrimagnetic material may be an artificial lattice film of rare earth metal and transition metal.

The rare earth metal may be at least one element selected from Gd, Tb and Dy, and the transition metal may be at least one element selected from Fe, Co and Ni.

The non-magnetic film may be an insulator.

The memory element of the present invention is, in the memory element having the above-mentioned magnetoresistive effect film, means for applying a magnetic field in the direction perpendicular to the film surface of the magnetoresistive effect film and electric resistance of the magnetoresistive effect film. And means.

The means for applying the magnetic field may be a conducting wire.

Further, a means for applying a magnetic field in a direction inclined from the direction perpendicular to the film surface of the magnetoresistive film may be provided.

The memory of the present invention is a memory using the above magnetoresistive film as a memory element, and in the recording of information, among the magnetic films sandwiching the non-magnetic film, the easy axis of magnetization is from the direction perpendicular to the film surface. Information is recorded / reproduced by changing the magnetization direction of the magnetic film provided in contact with the tilted magnetic film and without changing the magnetization direction of the other magnetic film.

Of the magnetic films formed in contact with the non-magnetic film, the magnetic film whose magnetization is oriented in the direction perpendicular to the film surface in a zero magnetic field is used as the recording layer, and the magnetization is inclined from the direction perpendicular to the film surface. The read magnetic layer may be a magnetic film.

Further, of the magnetic films formed adjacent to the non-magnetic film against the magnetic field applied at the time of recording or reading, the magnetic film formed in contact with one surface of the non-magnetic film. The magnetization of the magnetic film formed in contact with the other film surface of the non-magnetic film may be reversed without reversing the magnetization.

Further, there are provided means for arranging a plurality of magnetoresistive effect films and selectively recording on the desired magnetoresistive effect film, and means for selectively reading out information recorded on the desired magnetoresistive effect film. Good.

Therefore, the magnetoresistive effect film of the present invention is capable of reversing the magnetization with a comparatively small magnetic field, and particularly the memory using this magnetoresistive effect film can reduce the power consumption.

[0037]

1 shows an example of a magnetoresistive effect film of the present invention. A magnetic film in which the magnetization is oriented in a direction tilted from the direction perpendicular to the film surface in the absence of a magnetic field and in the state where the exchange force with other magnetic materials is not working, that is, the easy axis of magnetization is tilted from the direction perpendicular to the film surface. One magnetic film 111, a second magnetic film 112 that is a perpendicular magnetization film, a non-magnetic film 113, and a third magnetic film 114 that is a perpendicular magnetization film are sequentially formed. First magnetic film 111
And the second magnetic film 112 are exchange-coupled. Second magnetic film 1
The magnetization of 12 is oriented in the direction perpendicular to the film surface at least in the vicinity of the interface with the non-magnetic film 113 at zero magnetic field, or is easily oriented in the direction perpendicular to the film surface when a magnetic field is applied in the direction perpendicular to the film surface. . In the MRAM, the magnitude of the magnetic field that can be applied to the memory element is preferably 4 kA / m or less because of the limitation of the current density flowing in the conductor. Therefore, the magnetization tilted from the direction perpendicular to the film surface in the zero magnetic field should be oriented in the perpendicular direction by applying a magnetic field of 4 kA / m or less. When a magnetic film whose magnetization is oriented in a direction tilted from the direction perpendicular to the film surface is exchange-coupled to the perpendicular magnetic film in the absence of a magnetic field and the exchange force with other magnetic substances is not acting, the perpendicular magnetic film is Perpendicular magnetic anisotropy is apparently reduced. Therefore, it is possible to reduce the magnetization reversal magnetic field in the direction perpendicular to the film surface.

A magnetoresistance effect film using an exchange coupling film of a perpendicular magnetization film and an in-plane magnetization film is disclosed in Japanese Patent Laid-Open No. 2000-306374. The major difference of the present invention from this is the position of the magnetic film whose magnetization is oriented in a direction inclined from the direction perpendicular to the film surface. Japanese Patent Laid-Open No. 2000-306374 aims at obtaining a large magnetoresistive effect, and has a means of forming a magnetic film having a large spin polarizability in contact with a nonmagnetic film. An in-plane magnetized film is used as a magnetic film having a large spin polarizability, but the magnetization of the magnetic film needs to be oriented in the direction perpendicular to the film surface. Is achieved by the exchange coupling force of.

On the other hand, the present invention is intended to reduce the magnetization reversal magnetic field with respect to the magnetic field applied in the direction perpendicular to the film surface, and in the absence of magnetic field and in the state in which the exchange force with other magnetic materials is not working. The magnetic film whose magnetization is oriented in a direction inclined from the direction perpendicular to the film surface is not in contact with the non-magnetic film, and the magnetization of the magnetic film need not be oriented perpendicular to the film surface.

Even if a magnetic film whose magnetization is oriented in a direction inclined from the direction perpendicular to the film surface is formed in contact with the non-magnetic film in the absence of a magnetic field and in the state where the exchange force with other magnetic material is not working. Even if they are formed so as not to be in contact with each other, the magnetization reversal field of the exchange coupling film between the magnetic film and the perpendicular magnetization film is smaller than that in the case of the single perpendicular magnetization film. However, the magnetization reversal in the direction perpendicular to the film plane is
The magnetization depends on the film thickness of the magnetic film oriented in a direction inclined from the direction perpendicular to the film surface, and the film thickness of the magnetic film is determined by the magnitude of the magnetization reversal magnetic field. In JP-A-2000-306374, the film thickness of the in-plane magnetized film cannot be increased because the magnetization needs to be oriented in the direction perpendicular to the film surface as described above, and the film thickness of the in-plane magnetized film is 2 nm. The amount of decrease in the magnetization reversal magnetic field cannot be expected so much because it needs to be below. On the other hand, in the magnetoresistive film of the present invention, the magnetization of the magnetic film whose magnetization is oriented in the direction inclined from the direction perpendicular to the film surface does not need to be oriented in the direction perpendicular to the film surface. It is possible to make it relatively thick, and therefore it is easy to make the magnetization reversal field in the direction perpendicular to the film surface sufficiently small.

As described above, the film structure shown in FIG. 1 can be cited as an example of the embodiment of the present invention. Second magnetic film
In the state of being exchange-coupled with 112, the magnetization of the first magnetic film 111 may be oriented in the direction perpendicular to the film surface or may be inclined from the direction perpendicular to the film surface. However, when a magnetoresistive effect film whose magnetization is inclined from the direction perpendicular to the film surface is used as a memory element, both the magnetization of the third magnetic film 114 and the magnetization of the second magnetic film 112 must be reversible. Therefore, the third magnetic film 114 is used as the recording layer and the second magnetic film 112 is used as the reading layer.
When a current is applied to the conductor and recording is performed with a magnetic field generated by this current, it is generally difficult to generate a magnetic field larger than 4 kA / m. Therefore, recording on the third magnetic film 114 is 4 kA / m. It is preferable that the magnetic field is set to the following magnetic field, and at the time of reading, the magnetization of the second magnetic film 112 inclined from the direction perpendicular to the film surface is smaller than the reversal magnetic field of the magnetization of the third magnetic film 114. It is preferable to face the direction perpendicular to the film surface. The magnetization of the second magnetic film 112 is the same as that of the third magnetic film 1.
It is inverted by a magnetic field smaller than the magnetization of 14.

As the perpendicular magnetization film, as described above, Gd, D
An alloy film or artificial lattice film of at least one element selected from rare earth metals such as y and Tb and at least one element selected from transition metals such as Co, Fe and Ni, and transition metals such as Co / Pt and noble metals An artificial lattice film, an alloy film such as CoCr having crystal magnetic anisotropy in the direction perpendicular to the film surface can be mainly used. As a magnetic film in which the magnetization is oriented in a direction inclined from the direction perpendicular to the film surface in the absence of a magnetic field and in the state where the exchange force with other magnetic materials is not working, a magnetic film having the above perpendicular magnetic anisotropy is used. It can be obtained by using the same material and adjusting the film forming conditions so that Ku−2πMs ² <0. This makes it possible to obtain a magnetic film in which the axis of easy magnetization is inclined from the direction perpendicular to the film surface. Here, Ku is the perpendicular magnetic anisotropy energy constant, and Ms is the magnitude of saturation magnetization. Also, an in-plane magnetized film formed by using a film made of one kind of element selected from transition metals such as Co, Fe, and Ni or an alloy film made of two or more kinds of elements can be used.

As the non-magnetic film 113, a conductor such as Cu or Cr or an insulator such as Al ₂ O ₃ or NiO can be used. When an insulator is used for the nonmagnetic film 113, a relatively large magnetoresistance change can be obtained, which is preferable when used as a memory element.

When the magnetoresistive film having the film structure shown in FIG. 1 is used as a memory element, the magnetization of the second magnetic film 112 can be reversed by the applied magnetic field, and the third magnetic film 11 can be inverted.
The magnetization of 4 may or may not be reversible. However, when the magnetization of the third magnetic film 114 is non-reversible, the recorded information is not destroyed at the time of reading, so that the magnetization direction is not changed,
It is preferable to directly read the voltage of the device. When the magnetization of the third magnetic film 114 is reversible, the exchange coupling film of the first magnetic film 111 and the second magnetic film 112, which has a relatively small magnetization reversal magnetic field, is used as the read layer, and the magnetization of the third magnetic film 114 is relatively high. The third magnetic film 114 having a large reversal magnetic field can be used as a recording layer, and information recorded by reading the voltage change of the element caused by reversing the magnetization direction of the second magnetic film 112 is recorded. Can be read nondestructively.

FIG. 2 is a cross-sectional view schematically showing a film structure as an example of the embodiment of the present invention, which is different from the film structure shown in FIG. 1 in that a fourth magnetic film 115 is formed. The fourth magnetic film 115 is a magnetic film in which the magnetization is oriented in a direction inclined from the direction perpendicular to the film surface in the absence of a magnetic field and in the state where the exchange force with another magnetic body is not working, and the third magnetic film 115 Exchange coupled with membrane 114. That is, like the first magnetic film 111, it functions to reduce the magnetization reversal field of the perpendicular magnetization film. With such a structure, the second magnetic film
Both the 112 and the third magnetic film 114 can be magnetized by a small applied magnetic field. However, the magnitudes of the magnetization reversal magnetic field of the second magnetic film 112 and the third magnetic film 114 are different. When the magnetoresistive film having such a structure is used as a memory, the exchange coupling film of the first magnetic film 111 and the second magnetic film 112, the exchange coupling film of the third magnetic film 114 and the fourth magnetic film 115. Among them, the one having a relatively small magnetization reversal magnetic field is the reading layer and the one having a relatively large magnetization reversal magnetic field is the recording layer. The magnitude of the magnetization reversal magnetic field can be adjusted by the composition, film thickness, film forming conditions, etc. of each magnetic film.

Further, as shown in FIG. 3, a magnetic film 116 made of a material having a large spin polarizability is formed at the interface between the non-magnetic film 113 and the magnetic film.
It is also possible to form or 117 to increase the magnetic resistance. Although such films are formed on both interfaces in FIG. 3, only one of them may be formed. The magnetic films 116 and 117 formed on the interface may be either those whose magnetization is oriented in a direction inclined from the direction perpendicular to the film surface or which are perpendicularly magnetized films. The second magnetic film 112 and the third magnetic film are respectively formed. 1
In the state of being exchange-coupled with 14, the magnetization in the vicinity of the interface with the non-magnetic film 113 needs to be oriented perpendicular to the film surface.

The magnetic film 116 and the magnetic film 117 may have a grain shape.

In the above magnetoresistive film of the present invention,
The non-magnetic film may be a metal such as Cu or a dielectric such as Al ₂ O ₃ , but when used as a memory, it is preferable to use a non-magnetic film as a dielectric because a change in magnetic resistance is large.

By arranging a plurality of magnetoresistive films having any one of the above film configurations side by side and applying a relatively large magnetic field to only one desired element, a memory cell capable of selective recording is obtained. can do.

[0050]

EXAMPLE 1 FIG. 4 is a sectional view schematically showing the magnetoresistive film of the present invention. A Si wafer is used as the substrate 001, and its surface is oxidized to a SiO ₂ film of about 1 μm 00
2 is formed. The first magnetic film 111 is formed on the SiO ₂ film 002.
As an in-plane magnetized film, a Fe film with a thickness of 5 nm, and as the second magnetic film 112, a perpendicularly magnetized film with a thickness of 30 nm of Gd ₂₀ Fe.
₈₀ film, 2 nm thick Al ₂ O ₃ film as the non-magnetic film 113, 10 nm Tb ₂₂ Fe ₇₈ film which is a perpendicular magnetization film as the third magnetic film 114,
As the protective film 118, a 5 nm Pt film was sequentially formed. Where Fe
Film and Gd ₂₀ Fe _{8 0} film is exchange-coupled, Pt film is a protective film for preventing corrosion such as oxidation of the magnetic film. Both the Gd ₂₀ Fe ₈₀ film and the Tb ₂₂ Fe ₇₈ film are dominant in the transition metal sublattice magnetization. Next, a 1 μm square resist film was formed on the obtained multilayer film, and the Pt film and the Tb ₂₂ Fe ₇₈ film in the portion not covered with the resist were removed by dry etching. After etching, form an Al ₂ O ₃ film with a thickness of 15 nm, remove the resist and the Al ₂ O ₃ film above it, and short-circuit the upper electrode and the lower electrode consisting of the Fe film and Gd ₂₀ Fe ₈₀ film. An insulating film 121 was formed to prevent this. After that, the upper electrode 122 was formed of an Al film by the lift-off method, and the Al ₂ O ₃ film at a position deviated from the upper electrode was removed to form an electrode pad for connecting a measurement circuit. Further, the obtained magnetoresistive film was magnetized by applying a magnetic field of 2 MA / m in the direction perpendicular to the film surface and directing the magnetization of the Tb ₂₂ Fe ₇₈ film in the direction of the applied magnetic field. However, 1 cm square Tb
The coercive force of the ₂₂ Fe ₇₈ film is as large as 1.6 MA / m, and the coercive force of the obtained magnetoresistive film is expected to be as large as that.

The upper and lower electrodes of the magnetoresistive film are fixed.
Connect current power supply and Gd₂₀Fe₈₀Membrane and Tb _{twenty two}Fe₇₈Al between the membranes₂O
₃A constant current is passed so that electrons tunnel through the film. Magnetic
Applying a magnetic field in the direction perpendicular to the film surface of the resistance effect film,
And the direction of the magnetoresistive film.
Was measured (magnetoresistance curve). The result is shown in Fig. 8.
You According to this measurement result, the magnetization reversal is about 3 kA / m.
It was

(Example-2) FIG. 6 shows the magnetoresistive effect of the present invention.
It is sectional drawing which showed the peritoneum typically. Si as substrate 001
Using a wafer, this surface is oxidized and the SiO2 film is about 1 μm.₂film
002 is formed. SiO₂First magnetic film 11 on top of film 002
1 as an in-plane magnetized film, a 3 nm thick Fe film, the second magnetic
As the film 112, a Gd film having a film thickness of 50 nm, which is a perpendicular magnetization film, is used._{twenty five}Fe
₇₅The film, which exhibits a spin polarizability greater than that of the second magnetic film
As the magnetic film 116 of the fifth example, Co having a film thickness of 1 nm, which is an in-plane magnetized film, is used.₅₀
Fe₅₀2 nm thick Al film and non-magnetic film 113₂O₃Membrane, further
The sixth magnetic film showing a spin polarizability larger than that of the third magnetic film.
As the magnetic film 117, an in-plane magnetized film of 1 nm thick Co₅₀Fe₅₀
Film, 30 nm film that is a perpendicular magnetization film as the third magnetic film 114
Thick Tb_{twenty five}Fe₇₅Film, an in-plane magnetized film as the fourth magnetic film 115
An Fe film with a thickness of 3 nm and a Pt film with a thickness of 5 nm are formed in order as the protective film 118.
Formed next. Where Fe film and Gd_{twenty five}Fe₇₅Membrane, Gd_{twenty five}Fe₇₅With a membrane
Co₅₀Fe₅₀The membranes are exchange-coupled and Co₅₀Fe
₅₀Membrane and Tb_{twenty five}Fe₇₅Membrane, Tb _{twenty five}Fe₇₅Exchanged film and Fe film
I am fit. Gd_{twenty five}Fe₇₅Membrane and Tb_{twenty five}Fe₇₅Both films are rare earth
The metal sublattice magnetization is dominant. 2 layers of Co₅₀Fe₅₀Membrane is Gd_{twenty five}Fe
₇₅Membrane or Tb_{twenty five}Fe₇₅The spin polarizability is larger than that of the film, and its magnetic
The direction of crystallization is in the direction perpendicular to the membrane surface due to the exchange coupling force.
It The Pt film is a protective film to prevent corrosion such as oxidation of the magnetic film.
is there. Next, a 1 μm square resist film is formed on top of the obtained multilayer film.
And covered with resist by dry etching
Not the part of Pt film and Tb_{twenty five}Fe₇₅The film was removed. Eh
Al with a thickness of 39 nm after etching₂O₃Form a film, then register
And the upper Al₂O₃The film is removed, and the upper electrode and Fe film
And Gd_{twenty five}Fe₇₅To prevent short circuit with the lower electrode made of film
The insulating film 121 was formed. After that, by the lift-off method
The upper electrode 122 with an Al film,
Position of Al₂O₃For removing the membrane and connecting the measuring circuit
The electrode pad was used.

The upper electrode and the lower electrode of the magnetoresistive film are fixed.
Connect current power supply and Gd_{twenty five}Fe₇₅Membrane and Tb _{twenty five}Fe₇₅Al between the membranes₂O
₃A constant current is passed so that electrons tunnel through the film. Magnetic
Applying a magnetic field in the direction perpendicular to the film surface of the resistance effect film,
And the direction of the magnetoresistive film.
Was measured. The result is shown in FIG. 7. The magnetization reversal is about 2.
It occurs at 5kA / m and 3.8kA / m.

(Example-3) The magnetoresistive film 101, 102, 103, 104, 105, 106, 107, 108, 109 used in Example-2.
8 and 9 are electric circuit diagrams of the memory cells in which the memory cells are arranged in 3 rows and 3 columns. FIG. 8 shows a circuit for generating a magnetic field applied to the magnetoresistive film, and FIG. 9 shows a circuit for detecting a resistance change of the magnetoresistive film.

A method of selectively reversing the magnetization of the magnetic film of an arbitrary element will be described. For example, magnetoresistive film
To selectively reverse the magnetization of 105, transistor 21
Turn on 2, 217, 225, 220, and other transistors are OF
Leave it at F. In this way, the current will flow through conductors 312, 313, 3
It flows through 23, 322 and creates a magnetic field around them. Therefore, magnetic fields in the same direction are applied to the magnetoresistive film 105 only from the four conductors, and if the combined magnetic field is adjusted to be slightly larger than the magnetization reversal field of the magnetic film of the element, it is possible to selectively. Only the magnetization of the magnetoresistive effect film 105 can be reversed. When applying a magnetic field in the upside down direction to the magnetoresistive effect film 105, the transistors 213, 216, 22
Turn on 4 and 221 and turn off other transistors. By doing so, the current flows through the conductors 312, 313, 323, and 322 in the opposite direction to the previous direction, and the opposite magnetic field is applied to the magnetoresistive effect film 105.

Next, the read operation will be described. For example, when reading the information recorded on the magnetoresistive effect film 105, the transistors 235 and 241 are turned on. Then power supply 412, fixed resistance 100 and magnetoresistive effect film
It becomes a circuit in which 105 is connected in series. Therefore, the power supply voltage is divided into respective resistances at the ratio of the resistance value of the fixed resistance 100 and the resistance value of the magnetoresistive effect film 105. Since the power supply voltage is fixed, when the resistance value of the magnetoresistive effect film changes, the voltage applied to the magnetoresistive effect film changes accordingly. This voltage value is read by the sense amplifier 500. There are mainly two reading methods. One is a method of detecting the magnitude of a voltage value applied to the magnetoresistive film and discriminating information by the magnitude, which is called absolute detection. The other is a method in which only the magnetization direction of the read layer of the magnetoresistive film is changed, and the information is identified by the difference in the voltage change that occurs at that time. When the magnetization of the readout layer is reversed, the voltage value drops, for example,
Then, if the voltage value rises, it is "0". Such a reading method is called relative detection.

FIG. 10 is a sectional view schematically showing the peripheral portion of one element. Two n-type diffusion regions 1 on p-type Si substrate 011
19 and 120 are formed, and the word line (gate electrode) 342 is formed therebetween with the insulating layer 123 interposed. The ground wire 356 is connected to the n-type diffusion region 013, and the other contact plugs 352, 35 are connected.
Magnetoresistive film through 3, 354, 357 and local wiring 358
Connect 105. The magnetoresistive film is further connected to the bit line 332. A conductor 322 and a conductor 323 for generating a magnetic field are arranged beside the magnetoresistive film 105.

(Comparative Example) FIG. 11 is a sectional view schematically showing a conventional magnetoresistive effect film. A Si wafer is used as the substrate 001, and the surface of this is subjected to an oxidation treatment to a SiO ₂ film 002 of about 1 μm.
Are formed. On the SiO ₂ film 002, a Gd ₂₀ Fe ₈₀ film having a film thickness of 30 nm, which is a perpendicular magnetization film, is used as the magnetic film 21 having a relatively small magnetization switching field, and an Al ₂ O ₃ film having a film thickness of ₂ nm is used as the non-magnetic film 22.
A perpendicular magnetization film is used as the magnetic film 23 having a relatively large coercive force.
A 10 nm Tb ₂₂ Fe ₇₈ film and a 5 nm Pt film as a protective film 118 were sequentially formed. Here, the Pt film is a protective film for preventing corrosion such as oxidation of the magnetic film. Both the Gd ₂₀ Fe ₈₀ film and the Tb ₂₂ Fe ₇₈ film are dominant in the transition metal sublattice magnetization. Next, a 1 μm square resist film was formed on the obtained multilayer film, and the Pt film and the Tb ₂₂ Fe ₇₈ film in the portion not covered with the resist were removed by dry etching. 15 nm thick Al after etching
₂ O ₃ film is formed, and the resist and Al ₂ O _{3 on} top of it are also formed.
The film was removed to form an insulating film 121 for preventing a short circuit between the upper electrode and the lower electrode composed of the Gd ₂₀ Fe ₈₀ film. After that, the upper electrode 122 is formed by an Al film by the lift-off method,
The Al ₂ O ₃ film at a position deviated from the upper electrode was removed to provide an electrode pad for connecting a measurement circuit. Furthermore, the obtained magnetoresistive film was applied with a magnetic field of 2 MA / m in the direction perpendicular to the film surface,
Magnetization was performed by directing the magnetization of the b ₂₂ Fe ₇₈ film in the direction of the applied magnetic field.
However, the coercive force of the 1 cm square Tb ₂₂ Fe ₇₈ film is as large as 1.6 MA / m, and the coercive force of the obtained magnetoresistive film is expected to be as large as that.

The upper electrode and the lower electrode of the magnetoresistive film are fixed.
Connect current power supply and Gd₂₀Fe₈₀Membrane and Tb _{twenty two}Fe₇₈Al between the membranes₂O
₃A constant current is passed so that electrons tunnel through the film. Magnetic
Applying a magnetic field in the direction perpendicular to the film surface of the resistance effect film,
And the direction of the magnetoresistive film.
Was measured (magnetoresistance curve). The result is shown in Figure 12.
You According to this measurement result, the magnetization reversal field is about 24 kA / m.
It was.

[0060]

As described above, the magnetoresistive effect film of the present invention is capable of reversing the magnetization with a comparatively small magnetic field, and particularly the memory using this magnetoresistive effect film can reduce the power consumption. There is an effect that there is.

[Brief description of drawings]

FIG. 1 is a view schematically showing a cross section showing an example of a magnetoresistive effect film of the present invention.

FIG. 2 is a diagram schematically showing a cross section showing an example of a magneto-resistance effect film of the present invention.

FIG. 3 is a diagram schematically showing a cross section showing an example of the magneto-resistive effect film of the present invention.

FIG. 4 is a view schematically showing a cross section of a magnetoresistive effect film used in Example-1.

FIG. 5 is a diagram showing a magnetoresistive curve of the magnetoresistive film used in Example-1.

FIG. 6 is a diagram schematically showing a cross section of a magnetoresistive effect film used in Example-2.

FIG. 7 is a diagram showing a magnetoresistive curve of a magnetoresistive film used in Example-2.

FIG. 8 is a schematic diagram of an electric circuit for applying a magnetic field to the magnetoresistive film used in the memory of Example-3.

FIG. 9 is a schematic diagram of a read circuit used in the memory of Example-3.

FIG. 10 is a schematic view showing a cross section of a part of the memory of Example-3.

FIG. 11 is a schematic view showing a cross section of a magnetoresistive effect film used in a comparative example.

FIG. 12 is a diagram showing a magnetoresistive curve of a magnetoresistive effect film used in a comparative example.

FIG. 13A is a sectional view schematically showing a state where the magnetizations of the magnetoresistive effect film are parallel to each other. (B) It is sectional drawing which shows typically the state where the magnetization of a magnetoresistive effect film is antiparallel.

FIG. 14 is a diagram for explaining a recording / reproducing principle in a conventional magnetoresistive effect film using an in-plane magnetized film. (A) It is sectional drawing which shows typically the state of magnetization at the time of reading recording information "1". (B) A sectional view schematically showing the state of magnetization when reading recorded information “0”. (C) It is sectional drawing which shows typically the state of magnetization when reading the recording information "1". (D) It is sectional drawing which shows typically the state of magnetization when recording information "0" is read.

FIG. 15 is a diagram for explaining a recording / reproducing principle in a conventional magnetoresistive effect film using a perpendicular magnetization film. (A) It is sectional drawing which shows typically the state of magnetization at the time of reading recording information "1". (B) A sectional view schematically showing the state of magnetization when reading recorded information “0”. (C) It is sectional drawing which shows typically the state of magnetization when reading the recording information "1". (D) It is sectional drawing which shows typically the state of magnetization when recording information "0" is read.

[Explanation of symbols]

001 Si substrate 002 SiO ₂ film 011 p-type Si substrate 12, 22 Non-magnetic layer 13, 14, 21, 23 Magnetic layer 100 Fixed resistance 101-109 Magnetoresistive film 111 First magnetic film 112 Second magnetic film 113 Non-magnetic film 114 Third magnetic film 116, 117 Magnetic film made of material with high spin polarization 118 Protective film 119, 120 n-type diffusion regions 121, 123 Insulating film 122 Upper electrodes 211-226, 231-242 Transistor 311- 314, 321-324 Conductive wire (write wire) 331-333 Bit line 341-343 Word line (gate electrode) 351-355, 357 Contact plug 356 Ground wire 357 Local wire 411, 412 Power supply 500 Sense amplifier

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 10/16 H01F 10/16 10/187 10/187 10/32 10/32 H01L 27/105 H01L 27 / 10 447

Claims (26)

[Claims] 1. A magnetoresistive effect film having a structure in which a non-magnetic film is sandwiched between magnetic films, wherein at least one of the magnetic films is a perpendicular magnetization film, and the non-magnetic film is in contact with the perpendicular magnetization film. A magnetoresistive film having a magnetic film having an axis of easy magnetization inclined from a direction perpendicular to the film surface at a position not in contact with the magnetic film. 2. The magnetoresistive film according to claim 1, wherein at least one of the magnetic easy axes of the magnetic film is inclined from the direction perpendicular to the film surface. 3. The magnetoresistive effect film according to claim 1, wherein the magnetic film and the magnetic film having the easy axis of magnetization inclined from the direction perpendicular to the film surface are exchange-coupled. 4. The magnetoresistive effect according to claim 1, further comprising a layer having a spin polarizability larger than that of the perpendicular magnetic film between the perpendicular magnetic film and the non-magnetic film. film. 5. The magnetoresistive film according to claim 4, wherein the perpendicular magnetization film and the layer having a large spin polarizability are exchange-coupled with each other. 6. A first magnetic film having an easy axis of magnetization inclined from a direction perpendicular to the film surface, a second magnetic film, a non-magnetic film, a third magnetic film, and an easy axis of magnetization perpendicular to the film surface. A fourth magnetic film inclined from the direction is formed in this order, at least one of the second magnetic film and the third magnetic film is a perpendicular magnetization film, and the first magnetic film and the third magnetic film are formed. A magnetoresistive film, wherein the second magnetic film and the third magnetic film and the fourth magnetic film are exchange-coupled with each other. 7. The magnetoresistive film according to claim 6, wherein the easy magnetization axis of at least one of the second magnetic film and the third magnetic film is inclined from the direction perpendicular to the film surface. 8. The layer according to claim 6, wherein a layer having a spin polarizability larger than that of the second magnetic film is formed between the second magnetic film and the non-magnetic film. Magnetoresistive film. 9. A layer having a larger spin polarization than the third magnetic film is formed between the third magnetic film and the non-magnetic film. The magnetoresistive film described. 10. The layer having a large spin polarization and the second magnetic film, and the layer having a large spin polarization and the third magnetic film are exchange-coupled with each other. The magnetoresistive film described. 11. The magnetoresistive effect film according to claim 4, wherein the layer having a large spin polarization has a grain shape. 12. The magnetization of a magnetic film, the axis of easy magnetization of which is inclined from the direction perpendicular to the film surface, is oriented in the direction perpendicular to the film surface by a magnetic field having a magnitude of 4 kA / m or less.
Alternatively, the magnetoresistive film according to item 6. 13. The magnetization direction of the magnetic film, wherein the easy axis of magnetization is oriented in a direction inclined from the direction perpendicular to the film surface, is at least partially in the direction perpendicular to the film surface in a state of being exchange-coupled with the perpendicular magnetization film. The magnetoresistive film according to claim 1, wherein the magnetoresistive film is inclined with respect to the film. 14. The magnetoresistive film according to claim 1, wherein the perpendicular magnetization film is a ferrimagnetic material. 15. The magnetoresistive film according to claim 14, wherein the ferrimagnetic material is an alloy of a rare earth metal and a transition metal. 16. The magnetoresistive film according to claim 15, wherein the alloy of the rare earth metal and the transition metal is amorphous. 17. The magnetoresistive effect film according to claim 14, wherein the ferrimagnetic material is an artificial lattice film of a rare earth metal and a transition metal. 18. The rare earth metal is at least one element selected from Gd, Tb and Dy, and the transition metal is Fe or C.
18. The magnetoresistive effect film according to claim 15, wherein the magnetoresistive film is one or more kinds of elements selected from o and Ni. 19. The magnetoresistive film according to claim 1, wherein the nonmagnetic film is an insulator. 20. A memory element comprising the magnetoresistive effect film according to claim 1, wherein the magnetoresistive effect film is applied with a magnetic field in a direction perpendicular to a film surface of the magnetoresistive effect film. A memory device comprising a means for detecting the electric resistance of an effect film. 21. The memory device according to claim 20, wherein the means for applying the magnetic field is a conductive wire. 22. The memory device according to claim 20, further comprising means for applying a magnetic field in a direction inclined from a direction perpendicular to the film surface of the magnetoresistive effect film. 23. A memory using the magnetoresistive film according to claim 1 as a memory element, wherein among the magnetic films sandwiching a non-magnetic film at the time of recording information,
It is possible to change the magnetization direction of the magnetic film provided in contact with the magnetic film whose easy axis of magnetization is inclined from the direction perpendicular to the film surface, and to record / reproduce information without changing the magnetization direction of the other magnetic film. Characteristic memory. 24. A memory using the magnetoresistive effect film according to claim 2 as a memory element, wherein in a magnetic film formed in contact with a non-magnetic film, magnetization is perpendicular to a film surface in a zero magnetic field. A memory characterized in that a magnetic film facing the recording layer is used, and a magnetic film whose magnetization is inclined from a direction perpendicular to the film surface is used as a reading layer. 25. In a memory using the magnetoresistive film according to claim 1 as a memory element, a non-magnetic film is adjacent to a magnetic field applied during recording or reading. Of the formed magnetic film, the magnetization of the magnetic film formed in contact with one film surface of the non-magnetic film is not reversed, and the magnetic film formed in contact with the other film surface of the non-magnetic film is not reversed. A memory characterized in that the magnetization of the film is reversed. 26. A memory using the magnetoresistive effect film according to claim 1 as a memory element, wherein a plurality of the magnetoresistive effect films are arranged to selectively form a desired magnetoresistive effect film. And a means for selectively reading information recorded on a desired magnetoresistive film.