JPH113584A - Magnetic thin film memory element, production thereof, and recording and reproducing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance stability of magnetization, to preclude an adverse influence due to an anti-magnetic field and also to safely preserve magnetized information by allowing a magnetic thin film memory element to form a closed magnetic circuit constitution at a preservation time when an external magnetic field is zero. SOLUTION: A first magnetic layer 1 whose magnetization is mainly oriented in one direction being in a film surface and which has a low coercive force and a second magnetic layer 2 whose magnetization is mainly oriented in one direction being in a film surface and which has a high coercive force are laminated with a non-magnetic layer 3 on a substrate. This magnetic thin film memory element is a magnetro resistance element which show a low resistance value when magnetizations of the first and second magnetic layers 1, 2 are parallel and a high resistance value when they are anti-parallel and at the preservation time when the external magnetic field is zero, magnetizations of the first and second magnetic layer 1, 2 are in an anti-parallel state and since the first magnetic layer 1 is bent so as to be brought into contact with the end faces of the non-magnetic layer 3 to be in contact with end faces of the second magnetic layer 2 or the second magnetic layer 2 is bent so as to be brought into contact with the end faces of the non-magnetic layer 3 to be in contact with end faces of the first magnetic layer 2, the element becomes the closed magnetic circuit constitution and magnetizations of the layers 1, 2 are smoothly bent to form an annular loop and it becomes a stable energy state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element (magnetic thin film memory element) for recording information according to the direction of magnetization and reproducing the information by a magnetoresistance effect, a magnetic thin film memory using the same, and a recording / reproducing method thereof. Things.

[0002]

2. Description of the Related Art Like a semiconductor memory, a magnetic thin film memory is a solid-state memory having no moving parts, but does not lose information even when power is cut off, has an infinite number of rewrites, and records contents when radiation is incident. There is no danger of disappearing,
There are advantages over semiconductor memories. In particular, in recent years, a thin film magnetic memory utilizing the giant magnetoresistance (GMR) effect has attracted attention because a large output can be obtained as compared with a conventionally proposed magnetic thin film memory using the anisotropic magnetoresistance effect.

[0003] For example, the Japan Society of Applied Magnetics, Vol. 2
0, p22 (1996), a solid-state memory as a memory element is formed by laminating the components of the hard magnetic film 101 / non-magnetic film 102 / soft magnetic film 103 a plurality of times via the non-magnetic film as shown in FIG. Has been proposed. This memory element is provided with a sense line 104 joined to a metal conductor and a word line 106 insulated from the sense line by an insulating film 105, and is generated by the word line current and the sense line current. Information is written by a magnetic field.

More specifically, as shown in FIG. 15, a current I is applied to the word line 106 to generate magnetic fields in different directions according to the direction ID of the current, thereby inverting the magnetization of the hard soft magnetic film 101, and changing the memory state. “0” or “1” is recorded. For example, as shown in FIG. 15A, a positive current is applied to generate a rightward magnetic field to record "1" on the hard magnetic film, and a negative current is applied as shown in FIG. 15B. A "0" is recorded on the hard magnetic film by generating a leftward magnetic field.

In reading information, as shown in FIG. 16, a current I smaller than the recording current is applied to the word line to cause only the magnetization reversal of the soft magnetic film, and the resistance change at that time is measured. If the giant magnetoresistance effect is used, the resistance value differs between the case where the magnetization of the soft magnetic film and the hard magnetic film is parallel and the case where the magnetization is antiparallel,
The memory state of "1" or "0" can be determined from the resistance change that occurs at that time. When a positive to negative pulse as shown in FIG. 16A is applied, the soft magnetic film turns from right to left, and a small resistance value as shown in FIG. From the state shown in FIG.
The state changes to a state having a large resistance value as shown in FIG. 16C, and for the memory state “0”, the state changes from a state having a large resistance value as shown in FIG. 16D to a state as shown in FIG. The state changes to indicate a resistance value. By reading the change in resistance in this way, information recorded on the hard magnetic film can be read regardless of the magnetization state of the soft magnetic film after recording, and nondestructive reading can be performed.

[0006]

However, in the magnetic thin film memory having the above structure, the demagnetizing field (self-demagnetizing field) generated inside the magnetic layer cannot be neglected as the area of the bit cell is reduced, and the magnetic thin film memory for recording and holding is not able to be stored. The magnetization direction of the layer is not determined in one direction and becomes unstable. Therefore, the magnetic thin film memory having the above configuration has a disadvantage that it becomes difficult to store information as the bit cell is miniaturized, and high integration is impossible.

In a conventional memory having two magnetic layers,
The direction of magnetization of each magnetic layer exists in either a parallel or anti-parallel state. In particular, when the thickness of the nonmagnetic layer exceeds 40 nm, it is not uniform and cannot be determined. When the thickness of the nonmagnetic layer is reduced to 40 nm or less, depending on the thickness of the nonmagnetic layer, the magnetization may take one of an antiparallel state and a parallel state. Therefore, the magnetization of the two layers repeats parallel and antiparallel. For this reason, there is a problem that the margin of the thickness of the nonmagnetic layer in which the magnetization is antiparallel is narrow. That is, it has been difficult to stably realize an antiparallel magnetization state with many memory elements on one memory.

If the magnetizations of the two magnetic layers are parallel in the storage state, a magnetic field having a magnitude that cannot be ignored leaks to the outside of the memory element, which may cause erroneous recording and erroneous reproduction in adjacent cells. For this reason, recording and reproduction of the conventional device were unstable.

In view of the above, an object of the present invention is to provide a magnetic thin film memory element and a memory capable of eliminating a demagnetizing field of a magnetic thin film which is a problem when miniaturizing a bit cell and enabling high integration. I do. It is still another object of the present invention to provide a magnetic thin film memory element and a memory which have high magnetization stability during storage and excellent information preservability, and have low power consumption due to magnetization reversal even in a weak magnetic field during recording.

It is another object of the present invention to provide a recording / reproducing method which can record / reproduce stably, has a short reproduction time, and has little noise.

It is another object of the present invention to provide a method of manufacturing the above-mentioned memory element which has a wide manufacturing margin for the non-magnetic layer and can be manufactured by a simple process.

[0012]

Means for Solving the Problems The present inventor has made various studies in order to achieve the above object, and as a result, completed the present invention.

According to a first aspect of the present invention, there is provided a first magnetic layer having a low coercive force, which is mainly magnetized in one direction in a film plane, and a first magnetic layer, which is magnetized and oriented mainly in one direction in a film plane, on a substrate. And a second magnetic layer having a high coercive force is laminated via a non-magnetic layer,
A magnetoresistive element having a low resistance value when the magnetization of the magnetic layer and the magnetization of the second magnetic layer are parallel, and having a high resistance value when the magnetization is antiparallel. Is curved so as to be in contact with the end face of the nonmagnetic layer and is in contact with the end face of the second magnetic layer, or the second magnetic layer is curved so as to be in contact with the end face of the nonmagnetic layer and is in contact with the end face of the first magnetic layer. The present invention relates to a magnetic thin film memory element having a closed magnetic circuit configuration.

According to a second aspect of the present invention, after forming the second magnetic layer and the non-magnetic layer, the first magnetic layer is formed so as to be curved so as to be in contact with the end faces of the non-magnetic layer and the second magnetic layer. The magnetic thin film memory element according to the first invention, wherein after forming the first magnetic layer and the nonmagnetic layer, the second magnetic layer is formed to be curved so as to be in contact with the end faces of the nonmagnetic layer and the first magnetic layer. And a method for producing the same.

According to a third aspect, the magnetic thin-film memory elements of the first aspect are arranged in a matrix, and sense lines connecting the memory elements arranged in a vertical or horizontal direction in series, and intersecting the sense lines. And a word line provided adjacent to the memory element row arranged in a direction so as to be electrically insulated from each other.

According to a fourth aspect of the present invention, there is provided a magnetic memory device according to the first aspect, wherein the magnetic thin film memory elements are arranged in a matrix, and a first word line arranged in a vertical or horizontal direction and a second word arranged in a direction intersecting the first word line. The present invention relates to a magnetic thin-film memory, wherein the memory elements are connected in parallel by wires.

A fifth invention relates to a magnetic thin film memory characterized in that the magnetic thin film memory element of the first invention has a hybrid structure connected to a semiconductor element comprising a diode or a transistor.

According to a sixth aspect of the present invention, in the magnetic thin film memory according to the third, fourth or fifth aspect, an electric current is applied to the word line, and a magnetization direction of the second magnetic layer is determined by a magnetic field generated by the electric current. The present invention relates to a recording method for a magnetic thin film memory, wherein the states of "0" and "1" are recorded by changing the direction in which the current of a line flows.

According to a seventh aspect, in the magnetic thin film memory according to the third, fourth, or fifth aspect, the magnetization direction of only the first magnetic layer of the memory element is reversed by a magnetic field generated by a word current during reproduction. The present invention relates to a method for reproducing a magnetic thin-film memory, characterized by utilizing a change in resistance caused by such a phenomenon.

In the magnetic thin film memory of the present invention, since the magnetic film for recording is a closed magnetic path at the time of storage, it is possible to eliminate the adverse effect of the demagnetizing field and to stably store the magnetization information. Therefore, the cell width of one bit can be reduced, and a magnetic thin film memory with a high degree of integration can be realized. Further, since the magnetic field does not leak to the adjacent cells, information can be recorded and reproduced more stably. Further, since the reproduction can be performed by one pulse, the access time can be reduced. Further, it is possible to widen the manufacturing margin of the nonmagnetic layer. Resistance variation during reproduction can be suppressed, and S / N can be improved.

In view of the above-mentioned problems, the present invention is designed such that during storage, the magnetization stability is high due to the closed magnetic circuit structure, and during recording, the magnetization is reversed even in a weak magnetic field by eliminating the closed magnetic circuit structure. Has been made.

In the magnetic thin film memory of the present invention, since the magnetic film involved in recording has a closed magnetic path during storage, it is possible to eliminate the adverse effect of the demagnetizing field and to stably store magnetization information. On the other hand, during recording, the closed magnetic path is cut and the magnetization is easily reversed. Therefore, according to the present invention, a magnetic thin film memory with low power consumption, high integration, and good storage stability can be realized.

[0023]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments.

FIGS. 1 and 2 are sectional views showing an example of the magnetic thin film memory element of the present invention. In FIG. 1, 1 is a first magnetic layer, 2
Denotes a second magnetic layer, and 3 denotes a non-magnetic layer. Arrows indicate the main magnetization directions in each magnetic layer. Note that 1 is the second
The magnetic layer 2 may be the first magnetic layer.

As shown in FIG. 1, the magnetoresistive element of the present invention comprises, on a substrate, a first magnetic layer 1 having a low coercive force and being magnetized and oriented mainly in one direction in a film plane. Second magnetic layer 2 having a high coercive force and being magnetized in one direction in the film plane
Are stacked with the non-magnetic layer 3 interposed therebetween. The magnetoresistive element exhibits a low resistance when the magnetization of the first magnetic layer and the magnetization of the second magnetic layer are parallel, and exhibits a high resistance when the magnetization is antiparallel. When the external magnetic field is 0, the magnetization of the first magnetic layer and the magnetization of the second magnetic layer show an anti-parallel state, and the first magnetic layer is curved so as to be in contact with the end face of the non-magnetic layer and the second magnetic layer is bent. The second magnetic layer is curved so as to be in contact with the end face of the nonmagnetic layer and is in contact with the end face of the first magnetic layer to form a closed magnetic path structure.

In FIG. 1, the first magnetic layer 1 is disposed so as to be in contact with the side surfaces of the nonmagnetic layer 3 and the second magnetic layer 2, but as shown in FIG. The second magnetic layer may be in contact with the side surface of the magnetic layer 3 and the upper surface.

FIG. 3 shows the magnetization directions of the respective layers of FIGS. 1 and 2 in a simplified manner. As shown in FIG. 3, the first magnetic layer and the second magnetic layer form a closed magnetic circuit surrounding the nonmagnetic layer. Specifically, the magnetization of the first magnetic layer or the second magnetic layer is gently bent to form an annular loop, and a stable energy state is realized. In a conventionally known magnetic two-layer film structure that does not constitute a closed magnetic circuit, spin is bent at an end face having a high magnetic charge density, and magnetization is not stably held. Magnetization information can be stored.

Manufacturing Example of Magnetic Thin-Film Memory Element Next, a process for manufacturing the magnetic thin-film memory element of the present invention will be described with reference to FIGS.

In the magnetic thin-film memory element of the present invention, a closed magnetic circuit configuration having stable magnetization with a simplified structure can be obtained, so that the manufacturing process is also simple. For example, as shown in FIG. 4, if the first magnetic layer is formed after the second magnetic layer 2 and the non-magnetic layer 3 are formed and etched, the 1-bit memory cell shown in FIG. 1 can be manufactured. it can. Also, as shown in FIG. 5, if the first magnetic layer 1 is formed by etching only the non-magnetic layer after forming the second magnetic layer 2 and the non-magnetic layer 3, a 1-bit structure shown in FIG. A memory cell can be manufactured.

FIG. 6 is a diagram showing a case where 8-bit memory cells are connected in series. After forming the second magnetic layer 2 as shown in FIG. 6A, the non-magnetic layer 3 is formed as shown in FIG. 6B. Next, as shown in FIG. 6C, the first magnetic layer 1 is divided into eight parts by an etching process, and then the first magnetic layer 1 is formed as shown in FIG. 6D to produce a magnetic thin film memory of the present invention. be able to.

FIG. 7 is a diagram showing another example in which 8-bit memory cells are connected in series. In this case, the process is the same as that described above until the second magnetic layer is formed, but thereafter, as shown in FIG. 7C, only the nonmagnetic layer 3 is divided into eight by etching, Next, the first magnetic layer 1 is formed as shown in FIG. 7D to produce the magnetic thin film memory of the present invention.

FIG. 8 shows a hybrid structure of a magnetic thin film memory element of the present invention and a semiconductor. FIGS. 8 (a-1) and 8 (a-2) show a structure in which a plurality of memory elements of the present invention connected in series are arranged in parallel, and a diode for eliminating crosstalk in each structure. FIGS. 8 (b-1) and 8 (b-2) show an active matrix structure in which transistors and a memory element of the present invention are connected. FIG. 8 (c-1) and FIG. 8 (c-2) show a structure in which memory cells are arranged in parallel. 1A and 1B show a circuit diagram of one unit of a structure to which a memory element of the present invention is connected and a cross-sectional view of a device structure. As shown in FIG. 8, when the memory device of the present invention forms a hybrid structure in which the memory device is connected to a semiconductor device including a diode and a transistor, the manufacturing process is slightly complicated. Can eliminate an impedance component such as a stray capacitance generated in the device, and can perform more stable operation.

Next, a description will be given of an example of an array structure of memory cells when a matrix type solid-state memory is manufactured by arranging a large number of magnetic thin film memory elements of the present invention. 9, 10, and 11
1 shows a three-dimensional structure example in which the magnetic thin film memory elements of the present invention shown in FIG. 1 or 2 are arranged in series.

As shown in the figure, memory elements 10 are arranged in series, and a word line 5 is provided above each memory element. Another word line 6 is provided below the memory cell.

In the case of the series structure shown in FIGS. 9, 10 and 11, although not shown in the figure, an insulating layer is filled between each word line and the memory cell, and the space between the word line and the memory cell is formed. It prevents electrical conduction. In the case of the serial structure shown in FIGS. 9, 10 and 11, the word line 6 may not be provided when recording is performed using the sense line 7 and the word line 5.

In the case of a serial arrangement structure, the memory cells may be connected by the curved portion of the first or second magnetic layer as shown in FIG. 10, but the memory cells are connected by the good conductor 8 as shown in FIG. Alternatively, a good conductor 8 may be provided on the first magnetic layer as shown in FIG. 11 to reduce the resistance between the memory cells.
Examples of the good conductor include Al and the like, and it is preferable that the main conductor be a material having a lower resistivity than at least the first magnetic layer and the second magnetic layer. At the time of reproduction, a current passes through a curved portion of the first magnetic layer or the second magnetic layer to pass a current to the sense line. At this time, it is not preferable that the magnetization state of the curved portion affects the reproduction signal. Therefore, in order to avoid this, the length of the curved portion in the sense line direction is desirably 500 A or more. Note that in FIG. 9, the sense line refers to the entirety of a memory element and a good conductor arranged in series.

FIG. 12 shows an example of a structure in which memory cells are arranged in parallel. In this case, the word lines 5 are arranged so as to connect sense lines and each cell in parallel.

FIG. 13 is a top view of an example of the magnetic thin film memory of the present invention. Only a part of the memory cell 131 composed of a memory element is shown, and most of the others are omitted. The memory cells 1 are arranged in series to form a sense line 7. Although the sense lines are arranged in the horizontal direction in FIG. 13, the sense lines may be arranged in the vertical direction. The word line 5 is placed immediately above the memory element via an insulating layer not shown in the figure, and is arranged orthogonal to the sense line 7. Sense line 7
In some cases, a word line 6 (not shown) that is orthogonal to the word line 5 is provided at the lower part. The word line is provided mainly for recording, and the sense line is provided mainly for extracting a reproduced signal. Semiconductor elements such as a decoder and a driver for selectively driving these are provided at both ends 132, 133 and 134 of each word line and each sense line. Further, a sense amplifier for amplifying a reproduction signal is incorporated at an end of the sense line.

The substrate of the magnetic thin film memory element of the present invention is
It is desirable that the substrate be composed mainly of i. This is because the above-described semiconductor element can be manufactured over the same substrate as the memory element of the present invention.

Each of the word lines used in the present invention is made of a good conductor having a conductivity higher than that of the first and second magnetic layers. Examples of the word line include aluminum, copper, tungsten, a mixture thereof, or a mixture thereof with silicon or the like.

Recording method using magnetic thin film memory element of the present invention Next, an example of a recording method using the magnetic thin film memory element of the present invention will be described. The memory element of the present invention is provided with 72 electrode lines, word lines and sense lines. When a current flows through each of these lines, a magnetic field is generated according to Ampere's law. Since these two electrode lines are perpendicular to each other, the generated magnetic fields are also perpendicular to each other, and the magnetic field applied to the magnetic layer of the memory cell is the vector sum of these perpendicular magnetic fields. In this state, if a magnetic field large enough to reverse the second magnetic layer by the word line current is applied, the magnetization of the second magnetic layer is oriented in a desired direction and recording is performed. Therefore, it is possible to record only a specific cell from a large number of cells on the matrix.

The possibility of magnetization reversal is indicated by an asteroid curve of the magnetic layer. The second magnetic layer desirably has a high coercive force because it is desirable to stably maintain the magnetization state. However, at the same time, in order to prevent the word line from being disconnected by electromigration and to suppress power consumption, it is desirable that the magnetization of the second magnetic layer can be reversed by a weak magnetic field generated by a small current. The second magnetic layer needs to have a low coercive force. The coercive force of the second magnetic layer is determined so as to satisfy both requirements. Specifically, the coercive force of the second magnetic layer is desirably 5 to 50 Oe. More preferably, it is 10 to 30 Oe.

As described above, the basic recording of the present invention and the reproduction described later can be performed with the word line 5 and the sense line 7, so that the word line 6 shown in FIGS. 9 to 11 is not necessarily provided. Alternatively, recording and reproduction described later may be performed using a word line 6 orthogonal to the word line 5 to generate a larger magnetic field. Further, the word line 6 above the memory element may be omitted and the word line 6 below the memory element may be arranged in a direction orthogonal to the sense line 7.
However, when the semiconductor element and the memory element are formed on the same substrate, it is easier to manufacture the word line after forming the memory element. For this reason, it is preferable to configure in the order of substrate / first magnetic layer / non-magnetic layer / second magnetic layer / insulating layer / word line.

A buffer layer may be provided between the substrate and the memory element for the purpose of controlling the coercive force.
This is because by providing a buffer layer mainly composed of an insulator, it is possible to suppress the variation in coercive force between different memory cells and to easily control the absolute value of the coercive force. An example of such a buffer layer is an insulating material made of SiN.

Reproducing Method Using Magnetic Thin Film Memory Element of the Present Invention Next, an example of a reproducing method using the magnetic thin film memory element of the present invention will be described. The magnetic thin film memory of the present invention exhibits a giant magnetoresistance (GMR) effect due to spin-dependent scattering. The resistance value is low when the magnetizations of the first magnetic layer and the second magnetic layer are parallel, and is low when the magnetizations are antiparallel. Get higher. At the time of reproduction, a weaker current is applied to the word line above or below the memory element than during recording to generate a small magnetic field. This magnetic field is used to prevent the stored magnetization information from being erased during playback.
Only the first magnetic layer is inverted and the second magnetic layer is not inverted. The coercive force of the first magnetic layer needs to be smaller than the coercive force of the second magnetic layer. In order to secure a sufficient margin of the generated magnetic field, the coercive force of the first magnetic layer is preferably less than half, more preferably less than one-third, of the coercive force of the second magnetic layer. Further, the current value is set so that the magnetic field generated from the word line is larger than the switching field of the first magnetic layer and smaller than the switching field of the second magnetic layer.

In the above description, the reproduction of only one cell is described. However, in reality, a large number of cells are arranged on a matrix, and it is necessary to reproduce only the magnetization information of a specific cell. To this end, similarly to recording, a current is applied to the sense line connected to the target cell, and at the same time, a current is applied to a word line orthogonal to the sense line to generate a magnetic field. This is achieved by applying a magnetic field outside the asteroid curve of the magnetic field to only one magnetic layer.
Alternatively, only the first magnetic layer of a specific cell is inverted using two orthogonal word lines. The resistance change is measured at both ends of a sense line that connects memory elements arranged in a vertical or horizontal direction in series. Specifically, 134 or 133 shown in FIG.
A semiconductor element for detecting a change in resistance is disposed at the portion of the cell, and cells arranged on one sense line can be sequentially reproduced.

First Example of the Magnetic Thin Film Memory Element of the Present Invention The first example of the magnetic thin film memory element of the present invention is characterized in that the magnetoresistance effect is generated by spin-dependent scattering. The magnetoresistance effect due to the spin-dependent scattering can be obtained by using a metal layer made of a good conductor for the nonmagnetic layer in the structure of the first magnetic layer / nonmagnetic layer / second magnetic layer as shown in FIG. 1 or FIG. Can be generated. The magnetoresistance effect due to this spin-dependent scattering is derived from the fact that the scattering of conduction electrons differs greatly depending on the spin. In other words, conduction electrons having spins in the same direction as the magnetization are not scattered so much that the resistance is small, but conduction electrons having spins in the opposite direction to the magnetization have a large resistance due to scattering. Therefore, when the magnetizations of the first magnetic layer and the second magnetic layer are in opposite directions, the resistance value is larger than that in the case of the same direction.

The reproducing current may be either of two types, which flow parallel or perpendicular to the film surface. CPP (Current Perpendicular to the Current)
film Plane)-Uses the MR (Magneto-Resistance) effect. This CPP-MR has a CI that allows current to flow in parallel with the film surface.
Since the probability of conduction electrons crossing the interface increases more than the P (Current Inplane to the Film Plane) -MR effect, a large resistance change rate can be obtained, and the signal detection sensitivity can be increased.

The characteristics of the first magnetic layer, the second magnetic layer, and the nonmagnetic layer in this case are shown. The first magnetic layer is provided to form an annular loop with the second magnetic layer and to read out the magnetization information stored in the second magnetic layer using the giant magnetoresistance effect. It is desirable that the first magnetic layer be used mainly with Ni, Fe, and Co, or as an amorphous alloy mainly containing Co and Fe. For example, it is made of a magnetic film of NiFe, NiFeCo, FeCo, CoFeB or the like. The elemental composition of NiFe is Ni _x Fe
_{When 100-x} is set, x is desirably 35 to 86. Also,
The elemental composition of NiFeCo is Ni _x (Fe _100-y Co _y )
_{In the case of 100-x} , x is preferably from 10 to 70, y is preferably from 30 to 90, and y is preferably from 60 to 85. Also, C
o CoF having a composition such as ₈₄ Fe ₉ B ₇ and Co ₇₂ Fe ₈ B ₂₀
An amorphous magnetic material such as eB may be used.

The second magnetic layer is provided mainly for the purpose of storing magnetization information, and the direction of magnetization is determined according to information "0" and "1". Like the first magnetic layer, the second magnetic layer is required to efficiently generate a giant magnetoresistance effect and to be able to stably maintain a magnetization state. The second magnetic layer is made of a magnetic layer containing Fe and Co as main components, for example, a magnetic film of Fe, FeCo, Co or the like.
Further, an element such as Pt may be added. When Fe is added to Co, the coercive force decreases, and when Pt is added, the coercive force increases. Therefore, for example, Co _100-xy Fe _x
It may be controlled coercivity by adjusting the elemental composition x and y as Pt _y. Similarly, the coercive force of the first magnetic layer can be adjusted by the composition ratio of Fe and Co and the amount of elements such as Pt.

The thickness of the first magnetic layer needs to be set so that the scattering type giant magnetoresistance effect is efficiently generated. In the CPP-MR, a distance that can move while preserving the spin direction, that is, a spin diffusion length is an important factor. More specifically, if the thickness of the first magnetic layer is significantly larger than the mean free path of electrons, phonon scattering is exerted and the effect is reduced. Therefore, the thickness is preferably at least 200 A or less. More preferably, it is 150A or less. But,
If the thickness is too small, the resistance value of the cell becomes small, the output of the reproduced signal decreases, and the magnetization cannot be maintained.
A or more is desirable, and more preferably 80A or more.

As in the case of the first magnetic layer, the thickness of the second magnetic layer is set so that the scattering type giant magnetoresistance effect is efficiently generated. More preferably, it is 150A or less.
However, if the thickness is too small, the memory retention performance deteriorates, the cell resistance decreases, the reproduction signal output decreases, and the magnetization cannot be maintained, so that the current is preferably 20 A or more, and more preferably 80 A or more.

The nonmagnetic layer is made of a good conductor, and is preferably C
What has u as a main component is used. This is because the magnetic layer and the Fermi energy level are close to each other and the adhesion is good, so that the resistance easily occurs at the interface when the magnetization direction changes, which is convenient for obtaining a large magnetoresistance ratio. The thickness of the non-magnetic layer is preferably 5 to 60A.

A Co layer is provided between the first magnetic layer and the non-magnetic layer, between the second magnetic layer and the non-magnetic layer, or between the first magnetic layer and the non-magnetic layer and between the second magnetic layer and the non-magnetic layer. It is desirable to provide a magnetic layer containing as a main component, since the magnetoresistance ratio increases, and a higher S / N ratio can be obtained. In this case, the thickness of the layer containing Co as a main component is preferably 20 A or less. Further, in order to improve S / N, the first magnetic layer / non-magnetic layer / second magnetic layer / non-magnetic layer are formed as one unit,
The units may be stacked. It is preferable that the number of sets to be stacked is larger because the MR ratio becomes larger.
The magnetic layer becomes thicker and requires more current. Therefore, the number of laminations is preferably 40 or less, more preferably 3 to 20.

Second Example of Magnetic Thin Film Memory Device of the Present Invention A second example of magnetic thin film memory device of the present invention is characterized in that a magnetoresistive effect is generated by spin-dependent tunneling. The magnetoresistance effect due to this spin tunneling is
For example, as shown in FIG. 1 or FIG. 2, in the structure of the first magnetic layer / non-magnetic layer / second magnetic layer, it can be generated by using a thin insulating layer for the non-magnetic layer. And
An electron tunneling phenomenon from the first magnetic layer to the second magnetic layer occurs when a current flows perpendicular to the film surface during reproduction.

The spin-dependent tunneling type of the present invention
Magnetic thin-film memory elements use conduction electrons in ferromagnetic metals.
Is spin-polarized, so the Fermi surface
The electronic states of up spin and down spin are different
Using such a ferromagnetic metal, the ferromagnetic
When a ferromagnetic tunnel junction consisting of a ferromagnetic material and
Since the electron tunnels while maintaining its spin,
The tunnel probability changes depending on the magnetization state of the magnetic layer,
Appear as a change in tunnel resistance. As a result,
When the magnetizations of the first magnetic layer and the second magnetic layer are parallel, the resistance is small.
When the magnetizations of the first magnetic layer and the second magnetic layer are antiparallel,
Becomes larger. Up spin and down spin density of states
The larger the difference in
Since a raw signal is obtained, the first magnetic layer and the second magnetic layer
It is desirable to use a magnetic material having a high polarizability. Concrete
Specifically, the first magnetic layer and the second magnetic layer are formed on the Fermi surface.
Select Fe with a large amount of vertical spin polarization and change Co
It is selected as a component. Specifically, Fe, Co, Ni
It is desirable to select and use materials that contain
No. Preferably, Fe, Co, FeCo, NiFe, N
iFeCo or the like is preferable. The elemental composition of NiFe is Ni_xF
e_100-xIn this case, x is preferably from 0 to 82. More
Physically, Fe, Co, Ni₇₂Fe₂₈, Ni₅₁Fe₄₉,
Ni₄₂Fe₅₈, Ni _{twenty five}Fe₇₅, Ni₉Fe₉₁Etc.
It is.

The first magnetic layer is provided to form an annular loop with the second magnetic layer and to read out the magnetization information stored in the second magnetic layer by utilizing the giant magnetoresistance effect by spin tunneling. It is. The first magnetic layer has a lower coercive force than the second magnetic layer, so that only the first magnetic layer is inverted during reproduction. In addition, an annular loop is easily formed with the second magnetic layer. For this reason, a soft magnetic material containing Ni is desirable among the above-mentioned compositions, and specifically, NiF
e, it is desirable to use NiFeCo as a main component. When the element composition of NiFe is Ni _x Fe _100-x , x is preferably 30 to 82. When the element composition of NiFeCo is Ni _x (Fe _100-y Co _y ) _100-x ,
X is desirably 30 to 82, and y is desirably 0 to 90. If the film thickness of the first magnetic layer is too small, the resistance value of the cell becomes small and the output of the reproduced signal is reduced.
Further, 80A or more is desirable. If the thickness is too large, there is a problem that the resistance value of the cell becomes too large.
0A or less is desirable, and 1000A or less is more desirable.

The second magnetic layer is provided mainly for storing magnetization information, and the direction of magnetization is determined according to the information of "0" and "1". Like the first magnetic layer, the second magnetic layer is required to efficiently generate a giant magnetoresistance effect and to be able to stably maintain a magnetization state. The second magnetic layer has a higher coercive force than the first magnetic layer. For this reason, it is desirable to use Fe and Co as the main components in the above-mentioned composition for the second magnetic layer. For example, Fe, FeCo, Co
And the like. Further, an element such as Pt may be added to the second magnetic layer for the purpose of controlling coercive force and improving corrosion resistance. When Fe is added to Co, the coercive force decreases and Pt
Since the coercive force is increased when the addition of the second magnetic layer for example by adjusting the Co _100-xy Fe _x Pt _y as an element composition x and y may be controlled coercivity. Since the coercive force can be increased by increasing the substrate temperature during film formation, another method of controlling the coercive force may be to adjust the substrate temperature during film formation. This method may be combined with the above-described method of adjusting the composition of the ferromagnetic thin film. Also, the coercive force of the first magnetic layer can be adjusted by the film composition and the substrate temperature at the time of film formation in the same manner as described above.

If the film thickness of the second magnetic layer is too small, the memory holding performance is deteriorated, the resistance value of the cell is reduced, the reproduction signal output is reduced, and the magnetization cannot be held. And more preferably 80A or more. On the other hand, if the thickness is too large, the resistance of the cell becomes too large, and the distance from the word electrode becomes too large to cause the magnetization reversal to occur. Therefore, it is preferably 5000 A or less, more preferably 1000 A or less.

The non-magnetic layer tunnels while maintaining the spin.
In order to be non-magnetic. Part of the insulation layer
To minimize the magnetoresistive effect.
Can be further increased. Acid oxidized nonmagnetic metal film
As an example, a part of the Al film is oxidized in air.
Al_TwoO_ThreeAn example of forming a layer is given. The non-magnetic layer
Made of an insulator, preferably AlO_x-AlN_x, Si
O_x, SiN_x, NiO _xIs used as the main component
You. Of these, Al_TwoO_ThreeBecause the layer has high insulation and is dense
preferable. In addition, the non-magnetic layer has a uniform
Layer, the thickness of which is desirably 4 to 25A.
No. More preferably, it is 〜18A.

[0061]

As is apparent from the above description, according to the present invention, there is provided a magnetic thin film memory element and a memory which have excellent preservation of magnetization information, have high integration and high reliability, and have low power consumption. it can.

Further, it is possible to provide a recording / reproducing method in which recording / reproduction can be performed stably, the reproduction time is short, and the noise is small.

Since the magnetic thin film memory element and the memory of the present invention have a simple structure, the manufacturing process is simplified, and it can be manufactured easily and at low cost.

[Brief description of the drawings]

FIG. 1 is a structural sectional view of a magnetic thin film memory element of the present invention.

FIG. 2 is a structural sectional view of a magnetic thin film memory element of the present invention.

FIG. 3 is an explanatory view schematically showing an example of a magnetization orientation of the magnetic thin film memory element of the present invention.

FIG. 4 is an explanatory view showing one example of a manufacturing process of a 1-bit magnetic thin film memory element of the present invention.

FIG. 5 is an explanatory view showing one example of a manufacturing process of a 1-bit magnetic thin film memory element of the present invention.

FIG. 6 is an explanatory view showing one example of a manufacturing process of an 8-bit magnetic thin film memory element of the present invention.

FIG. 7 is an explanatory view showing one example of a manufacturing process of an 8-bit magnetic thin film memory element of the present invention.

FIG. 8 is an explanatory view showing an arrangement structure of a magnetic thin film memory element of the present invention.

FIG. 9 is an explanatory view showing an arrangement structure of a magnetic thin film memory element of the present invention.

FIG. 10 is an explanatory view showing an arrangement structure of a magnetic thin film memory element of the present invention.

FIG. 11 is an explanatory view showing an arrangement structure of a magnetic thin film memory element of the present invention.

FIG. 12 is an explanatory view showing an arrangement structure of a magnetic thin film memory element of the present invention.

FIG. 13 is a plan view of the magnetic thin film memory of the present invention.

FIG. 14 is a sectional view of a conventional magnetic thin film memory using the giant magnetoresistance effect.

FIG. 15 is an explanatory diagram showing a recording operation of a conventional magnetic thin film memory using the giant magnetoresistance effect.

FIG. 16 is an explanatory diagram showing a reproducing operation of a conventional magnetic thin film memory using the giant magnetoresistance effect.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st magnetic layer 2 2nd magnetic layer 3 non-magnetic layer 5, 6 word line 7 sense line 8 good conductor 10 memory element 81 memory element 82 word line 83 control gate 84 transistor 85 diode 86 P substrate 131 memory cell 101 hard magnetic film 102 Soft magnetic film 103 Non-magnetic film 104 Sense line 105 Insulating film 106 Word line ID Current direction

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[Procedure amendment]

[Submission date] July 16, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction contents]

The reproducing current may be either of two types, which flow parallel or perpendicular to the film surface. CPP (Current Perpendicular to the Current)
film Plane) -MR (Magneto-Resistance) effect can also be used. This CPP-MR is a CIP (Current Inplane to the film Plan) that allows current to flow parallel to the film surface.
e) Since the probability of conduction electrons crossing the interface increases more than the -MR effect, a large rate of change in resistance can be obtained, and the signal detection sensitivity can be increased.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 8

[Correction method] Change

[Correction contents]

FIG. 8

Claims (7)

[Claims] 1. A first magnetic layer having a low coercive force and mainly magnetized in one direction in a film plane on a substrate, and a high magnetic layer mainly magnetized and oriented in one direction in a film plane in a film plane. Second with magnetic force
A magnetic resistance element in which a magnetic layer is stacked with a non-magnetic layer interposed therebetween and shows a low resistance value when the magnetization of the first magnetic layer and the magnetization of the second magnetic layer are parallel, and shows a high resistance value when the magnetization is antiparallel. When the external magnetic field is 0, the first magnetic layer is curved so as to be in contact with the end face of the non-magnetic layer and is in contact with the end face of the second magnetic layer, or the second magnetic layer is in contact with the end face of the non-magnetic layer. A magnetic thin film memory element characterized in that the magnetic thin film memory element has a closed magnetic circuit configuration by being curved in contact with an end face of a first magnetic layer. 2. The method according to claim 1, wherein after forming the second magnetic layer and the non-magnetic layer, the first magnetic layer is formed so as to be curved so as to be in contact with end faces of the non-magnetic layer and the second magnetic layer. 2. The method according to claim 1, wherein after forming the non-magnetic layer, the second magnetic layer is formed to be curved so as to be in contact with the end faces of the non-magnetic layer and the first magnetic layer. 3. The memory according to claim 1, wherein the magnetic thin film memory elements are arranged in a matrix, and the memory elements are arranged in a vertical or horizontal direction and serially connected to the memory elements, and the memory is arranged in a direction intersecting the sense lines. A magnetic thin film memory comprising: a word line which is provided in close proximity to an element row in an electrically insulated manner. 4. The magnetic thin-film memory element according to claim 1, wherein the magnetic thin-film memory elements are arranged in a matrix, and include a first word line arranged in a vertical or horizontal direction and a second word line arranged in a direction intersecting the first word line. A magnetic thin film memory wherein memory elements are connected in parallel. 5. A magnetic thin-film memory according to claim 1, wherein the magnetic thin-film memory has a hybrid structure connected to a semiconductor element comprising a diode or a transistor. 6. The magnetic thin film memory according to claim 3, wherein a current is applied to the word line, a magnetization direction of the second magnetic layer is determined by a magnetic field generated by the current, and a direction in which the current of the word line is applied. Recording the state of "0" and "1" by changing the state of the magnetic thin film memory. 7. The magnetic thin film memory according to claim 3, wherein a change in resistance caused by reversing the magnetization direction of only the first magnetic layer of the memory element due to a magnetic field generated by a word current at the time of reproduction. A method for reproducing a magnetic thin film memory, wherein the method is used.