JPH1186528A - Magnetic memory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic memory device in which sense currents flow in the direction perpendicular to a film plane and the magnetic memory device which is high in sense sensitivity, is simultaneously nonvolatile and makes it possible to obtain effects of a higher SN, higher speed access and higher integration, etc. SOLUTION: This memory device is provided with a memory section laminated and formed with a first ferromagnetic layer 12, a nonmagnetic layer 13 and a second ferromagnetic layer 14 and a third ferromagnetic layer 11 which is a ferromagnetic layer laminated and formed via the first ferromagnetic layer 12 and the nonmagnetic layer 16 and has a longitudinal direction. The device reads the resistance change according to the magneto-resistive effect of the memory section and the third ferromagnetic layer 11 as memory information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic storage device, and more particularly to a magnetic storage device that stores information by using a change in magnetic resistance.

[0002]

2. Description of the Related Art Today, storage devices (memory) typified by semiconductor storage devices are used everywhere from the main memory of large computers to personal computers, home appliances, cellular phones, and the like. Semiconductor memories include volatile DRAM (Dynamic RAM) and SRAM (Static RA).
M), nonvolatile MROM (Mask ROM), Flash EEP
ROM (Electrically Erasable Programmable ROM) and the like are on the market. In particular, although DRAM is a volatile memory, it is excellent in low cost (cell area is 1/4 compared with SRAM) and high speed (Flash EEPROM), and occupies most of the market. That is the current situation.

[0003] Rewritable and nonvolatile Flash EEPROM
Can be turned off, but the number of rewrites (W / E
(The number of times) is as small as about 10 6, and the writing time also takes about a microsecond. Further, the market is not as open as DRAM because of the problem that a high voltage (12 V to 22 V) needs to be applied at the time of writing.

On the other hand, a ferroelectric capacitor (ferr
FR of non-volatile memory using oelectric capacitor)
AM (Ferroelectric RAM) has been non-volatile since it was proposed in 1980, has a large number of rewrites of 10 to the 12th power, and has a read and write time of about DRAM.
Each storage device maker is developing it because it has advantages such as operation at 3 V to 5 V. However, when the number of rewrites is 10 to the 12th power, the cycle time is 100 ns, which is 1.15 days. Therefore, if the number of rewrites is not 10 15 or more, continuous operation cannot be performed for more than 10 years, and DR
At present, it cannot be used as a main memory such as AM.

On the other hand, in recent years, giant magnetoresistance GMR
(Giant Magneto Resistive) Magnetic resistance (Magnet
o A non-volatile storage device utilizing the resistive effect has been developed (JL Brown et al, IEEE Trans. o
f Components Packaging, andManufacturing Technolog
y-PART A, Vol. 17, No. 3, Sep., 1994. and Y. Irie
et al., Japanese Journal of Applied Physics Lette
r, Vol. 34, pp. L415-417, 1995., DD Tang et a
l., IEEE InterMAG'95, AP03, 1995, S. Tehraniet al
, IEDM 96-193, etc.). A storage device utilizing such a giant magnetoresistance effect (hereinafter referred to as a GMR memory)
In addition to the advantages of nondestructive reading, high-speed operation, and high radiation withstand voltage, there is a possibility that the number of rewrites is 10 15 or more, and the DRAM market, all semiconductor memories, Hard Disk (HD), and the like are directly replaced.

FIG. 7A is a plan view of a memory cell of a conventional GMR memory, and FIG. 7B is a sectional view taken along the line AA 'of FIG. 7B. As shown in FIGS. 7A and 7B,
The GMR film 1 is connected in series to the bit lines 2 and 3, and the word line 4 is formed on the GMR film 1 and is orthogonal to the direction in which the bit lines 2 and 3 extend. The GMR film 1 is made of a metal artificial lattice, a nano-granular alloy, or a thin ferromagnetic layer as shown in FIG.
1a, a nonmagnetic conductor layer 1b, and a ferromagnetic layer 1c. FIG. 8 shows a cross section taken along the line CC 'of the GMR film 1 shown in FIG.

Next, the read and write operations of the GMR memory will be described with reference to the laminated film of FIG. 8 as an example. The memory state in which the magnetizations of the ferromagnetic layers 1a and 1c sandwiching the nonmagnetic conductor layer 1b from above and below are clockwise as shown in FIG.
On the other hand, the left-handed storage state corresponds to the other side.

The reading of these storage states is performed by using a bit line
A current is simultaneously applied to the word lines 2 and 3 and the word line 4 in the direction of the arrow shown in FIG. 7A to generate a combined magnetic field. That is, if the memory state is counterclockwise, the relative angle of the magnetization of the two magnetic layers 1a and 1c of the GMR film 1 decreases due to the combined magnetic field, and the resistance value of the GMR film decreases. On the other hand, if it is clockwise, even if a combined magnetic field is generated, the relative angle between the two magnetic layers 1a and 1c does not change, and the resistance value of the GMR film 1 does not change. The presence or absence of such a change in the resistance value is determined by applying a sense current to the bit lines 2 and 3 to determine the storage state.

On the other hand, as shown in FIG. 7 (a), information is written using a combined magnetic field generated by applying currents to the bit lines 2, 3 and the word line 4 at the same time. The amount of current at the time of writing is larger than that at the time of reading, and the GMR film
It is set to such an extent that the magnetization of the ferromagnetic layers 1a and 1c can be reversed. In this way, word line 4 and bit lines 2, 3
The storage information is selectively written into the GMR film 1 of the memory cell at the intersection of.

[0010] Such a GMR memory has not yet been put into practical use due to the following problems. Since the GMR film 1 is a metal film, the specific resistance is low, and the sheet resistance is 10 to 30 Ω /
□ If the cell is approximately square, the resistance is
This is because the resistance value is only about 0Ω and the resistance value is smaller than that of the semiconductor element. When the resistance value is small as described above, the resistance value of the cell becomes substantially invisible due to variations in the resistance of the semiconductor material such as the bit lines 2 and 3, and it is difficult to extract a read signal. Therefore, there is a problem in that the read signal has a poor SN ratio and takes a long time to read.

On the other hand, researches on magnetic memories using a magnetoresistance effect other than the above-mentioned GMR are also in progress. For example,
A ferromagnetic tunnel junction device in which a tunnel junction is formed by a laminated film in which an insulator film is inserted between two ferromagnetic layers, and a laminated film consisting of a magnetic material / non-magnetic material / magnetic material is inserted in the base of a metal base transistor. And a spin transistor formed by stacking an emitter and a collector made of a ferromagnetic layer using a nonmagnetic layer as a base layer. These junction elements and transistors have a structure in which current flows in a direction perpendicular to the film surface of the stacked film, and no specific method has been devised for their write / read operations.

[0012]

As described above,
The conventional GMR memory has advantages such as nondestructive reading, high-speed operation, high radiation pressure resistance, and continuous operation for 10 years. On the other hand, since the obtained output signal is weak, the SN ratio is low. It has a problem that it is low and takes a long time to read. In the magnetic memory using the magnetoresistance effect other than the GMR, the cell structure is devised, but the write / read operation and the configuration of the bit lines and word lines around the cell are not devised.

The present invention has been made in view of the above circumstances, and is a magnetic storage device in which a sense current flows in a direction perpendicular to a film surface. It is an object of the present invention to provide a magnetic storage device that can obtain effects such as an SN ratio, high-speed access, and high integration.

[0014]

[Means for Solving the Problems]

(Summary) In order to solve the above problems, the first of the present invention is
, A storage unit in which a first ferromagnetic layer, a first non-magnetic layer, and a second ferromagnetic layer are stacked, and a first ferromagnetic layer formed through a second non-magnetic layer And a third ferromagnetic layer having a longitudinal direction in a predetermined direction.

According to a second aspect of the present invention, there is provided a storage unit having a first ferromagnetic layer, a first non-magnetic layer, and a second ferromagnetic layer stacked thereon. A third ferromagnetic layer having a longitudinal direction in a predetermined direction and laminated with the first ferromagnetic layer via a second non-magnetic layer; a first ferromagnetic layer and the third ferromagnetic layer And a reading means for reading a resistance change between the first ferromagnetic layer and the third ferromagnetic layer based on the relative difference in the magnetization directions of the magnetic storage device.

Further, in order to solve the above-mentioned problem, a third aspect of the present invention is to provide a semiconductor device comprising a laminated body of a first ferromagnetic layer, a first non-magnetic layer, and a second ferromagnetic layer. A plurality of storage portions forming a current path having a longitudinal direction in a direction, and a plurality of stripe-shaped third ferromagnetic layers having a longitudinal direction substantially perpendicular to a predetermined direction, wherein the second nonmagnetic layer is First through
And a third ferromagnetic layer formed by lamination.

(Function) The first to third aspects of the present invention relate to a magnetic storage device, wherein the storage unit holds the magnetization direction of the first ferromagnetic layer as storage information, and The magnetoresistive effect, in which electric characteristics change depending on whether the magnetization direction of one ferromagnetic layer is parallel or antiparallel, is used. For example, a state where the magnetization directions of both ferromagnetic layers are parallel and a state where they are antiparallel can be stored as a “0” state or a “1” state, respectively. A second non-magnetic layer is formed between the storage unit and the third ferromagnetic layer, and by selecting its electrical properties, the above-described magnetoresistance effect includes the ferromagnetic tunnel effect, the metal-base transistor effect, and the spin resistance. A transistor effect can be generated.

The ferromagnetic tunnel effect can be obtained by laminating the first ferromagnetic layer of the storage section with the third ferromagnetic layer via the insulating second nonmagnetic layer (tunnel insulating layer). . When a voltage is applied between both magnetic layers via the insulating film, a tunnel current whose current amount changes depending on the magnetization direction of both magnetic layers flows. That is, the state density on the Fermi surface of the ferromagnetic layer depends on the spin (magnetization direction), the tunnel establishment between spin bands having a large state density is high, and the state where the magnetization directions of both ferromagnetic layers are parallel to each other is opposite. The conductance is larger than in the parallel state. Reading is performed by sensing this difference in conductance.

The metal-base transistor effect can be obtained by a third Schottky junction with a collector electrode made of a semiconductor.
Is formed by forming a base layer together with a first ferromagnetic layer formed by lamination via a conductive second nonmagnetic layer. If the magnetization directions of the third ferromagnetic layer and the first ferromagnetic layer are parallel, the collector current increases, and if the magnetization directions are antiparallel, the collector current decreases. Information is read out by judging the magnitude of the collector current. A negative voltage (-V) is applied to the emitter connected to the base layer.
(V> 0), hot electrons are tunnel-injected into the base layer, and the hot electron current flowing into the collector over the Schottky barrier is measured as the collector current Ic. When the magnetization directions of the third ferromagnetic layer and the second ferromagnetic layer forming the base layer are parallel, about 9 to 19 times the electron transmittance is obtained as compared with the antiparallel state, and the collector current Fluctuates due to this difference in transmittance, and the stored magnetization direction is read out using this fluctuation.

The spin transistor effect can be obtained by laminating a first ferromagnetic layer and a third ferromagnetic layer via a conductive second non-magnetic layer. A spin transistor can be configured by using a nonmagnetic conductive layer as a base layer and using both magnetic layers laminated thereon as an emitter and a collector. If the magnetization directions of both magnetic layers are parallel, the collector voltage increases, and a current flows from the base layer to the collector layer. Conversely, if the magnetization directions of both magnetic layers are antiparallel, the collector voltage decreases, and current flows from the collector layer to the base layer. Information reading is performed by judging such a change in the collector voltage or the magnitude of the current amount.

In the first and second aspects of the present invention,
It is preferable to have the following configuration. 1) The length of the third ferromagnetic layer in the longitudinal direction is set to 5 times or more the length in the width direction. By doing so, the demagnetizing field of the third ferromagnetic layer can be made sufficiently small, and the fluctuation of the stored information due to the magnetization of the first wiring can be sufficiently suppressed. 2) The magnetization direction of the third ferromagnetic layer is substantially the same as its longitudinal direction. As the magnetization direction of the third ferromagnetic layer approaches the direction perpendicular to the longitudinal direction, the stored information due to the magnetization of the first wiring is easily destroyed. When the storage unit has a longitudinal direction perpendicular to the third ferromagnetic layer, curling of magnetization occurs. Therefore, when such a structure is provided, it is preferable that the magnetization direction be slightly shifted from the parallel direction in order to cope with the occurrence of curling. 3) The easy axis of magnetization of the first ferromagnetic layer is substantially the same as the longitudinal direction of the third ferromagnetic layer. 4) A storage unit and a wiring formed by lamination are provided. It is also possible to write information to the storage unit by using this wiring. 4-1) The wiring is formed of a laminated film including a non-magnetic layer and a magnetic layer. With such a laminated film, a large current magnetic field can be generated with a small current. 5) The storage unit is connected to a bit line, and the third ferromagnetic layer is connected to a plate potential via a transistor. As the plate potential, either a fixed system or a variable system can be applied. 6) The first ferromagnetic layer and the third ferromagnetic layer are formed of an insulating second ferromagnetic layer.
The ferromagnetic tunnel junction is formed by laminating through the non-magnetic layer. 7) the first ferromagnetic layer and the third ferromagnetic layer
And the third ferromagnetic layer is in Schottky junction with the semiconductor layer on the surface opposite to the surface joined to the second nonmagnetic layer. 8) The first ferromagnetic layer constitutes an emitter layer, the third ferromagnetic layer constitutes a collector layer, and the conductive second nonmagnetic layer constitutes a base layer.

If the first ferromagnetic layer is made of a magnetic material having a high coercive force, such as a hard magnetic material, it is not always essential to provide the second ferromagnetic layer. However, when a hard magnetic film is used, a write current large enough to cause the magnetization reversal is required, and it is considered that power consumption is increased as compared with the structure including the second ferromagnetic layer.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, magnetic storage devices according to first to third embodiments of the present invention will be described with reference to the drawings. (First Embodiment) In a first embodiment, a memory cell has a tunnel junction. As shown in FIG. 1A, a memory cell 10 includes a first ferromagnetic layer 12 made of CoFe or the like, Cu, Au, or the like.
A storage unit including a nonmagnetic layer 13 made of a good conductor such as CoFe and a second ferromagnetic layer 14 made of CoFe or the like;
And a third ferromagnetic layer 11 made of a hard magnetic material laminated on a nonmagnetic tunnel insulating layer 16 made of, for example, SiO ₂ , Al ₂ O ₃ or the like. The tunnel junction includes a first ferromagnetic layer 12, an insulating layer 16, and a third ferromagnetic layer 11. By providing the second ferromagnetic layer 14,
The magnetic flux can be returned to the first ferromagnetic layer 12. FIG. 1A shows a cross section taken along the line AA ′ in FIG. 1B.

The memory cells 10 are sequentially laminated on a main surface of a semiconductor substrate 15 made of a non-magnetic material such as Si or a substrate 15 made of a non-magnetic material such as Al ₂ O ₃ .TiC. At this time, a buffer layer or the like is inserted between the memory cell 10 and the substrate 15 as necessary.

FIG. 1B shows the three memory cells 10 _{i, j} , 10 _{i-1, j} and 10 _{i-2, j} of FIG. 1A as viewed from above the third ferromagnetic layer 11. It is a top view. The third ferromagnetic layers 11 _i , 11 _i-1 and 11 _i-2 having a longitudinal direction are formed in a stripe shape having the longitudinal direction in the y direction. Note that a non-magnetic insulating layer such as a silicon oxide layer is formed between the plurality of third ferromagnetic layers formed in a stripe shape. A stacked body including the first ferromagnetic layer 12, the nonmagnetic layer 13, and the second ferromagnetic layer 14 has a longitudinal direction in a direction (x direction) orthogonal to the third ferromagnetic layer to constitute BLj. . Each memory cell 10 is arranged at an intersection of the stacked body and the third ferromagnetic layer 11.
The stacked body may be formed only at the intersection of each BL and the third ferromagnetic layer, and the stacked bodies arranged in an array in the x direction may be connected to each other by a conductive layer to form a bit line. .
Further, the non-magnetic layer 13 may be conductive or insulating.

Since the magnetization of the third ferromagnetic layer is fixed in one direction as described above, for example, a hard magnetic material such as CoPt, or a ferromagnetic layer such as FeMn, IrMn, PtMn, PdMn, etc. Mn
Laminated film in which the antiferromagnetic layer of the system is antiferromagnetically exchange-coupled, or a soft magnetic layer made of a soft magnetic material such as CoZrNb or FeNi and having an easy axis of magnetization substantially in the same direction as the longitudinal direction. Is raised.

The fact that the third ferromagnetic layer does not have a magnetostatic effect on the memory cell prevents adverse effects such as fluctuation of stored information, generation of noise during writing and reading, and reduction of output. It is preferable for If the aspect ratio (length / width) of the third ferromagnetic layer is set to 5 or more in order to prevent magnetostatic effects, the magnetic field generated from the longitudinal end of the third ferromagnetic layer can be kept small. This makes it possible to prevent the above adverse effects.

To read these stored states, a voltage is applied between the third ferromagnetic layer 11 and the first ferromagnetic layer 12,
This is performed by determining the magnitude of the flowing tunnel current.
That is, when the magnetization direction of the magnetic conductive layer 12 is parallel to the third magnetic layer 11, the tunnel junction is formed more easily than when the magnetization direction of the magnetic conductive layer 12 is antiparallel to the third magnetic layer 11. The amount of current flowing increases. The storage state is determined by reading this amount of current using the potential difference between the longitudinal end of the first ferromagnetic layer 12 and the longitudinal end of the third ferromagnetic layer 11. In FIG. 1 (b)
The storage information of the cell 10 _{i−1, j} is determined by the end of the first wiring 11 _{i−1 and the} end of the j-th bit line BL _j .

On the other hand, when writing information, as shown in FIG. 1B, the current Iw is applied to at least one of the first magnetic layer 12, the non-magnetic layer 13, and the second magnetic layer 14, and the third Magnetic layer 11
And a combined magnetic field generated by flowing a current Iw 'at the same time.
The amount of current during writing is larger than that during reading,
The magnetization of the first and second ferromagnetic layers 12 and 14 is set to such an extent that the magnetization can be reversed. In this way, the storage information is selectively written in the memory cell 10 at the intersection.

The storage state is changed to the memory cells 10 _{i-1, j} and 10 shown in FIG.
_This will be described with reference to FIGS. 2A and 2B using _{i and j} as examples. FIG. 2A is a cross-sectional view taken along the line BB ′ of FIG.
Shows a cross section taken along the line CC ′ of FIG. Third ferromagnetic layer 11 _i-1
Is fixed in the left direction of the drawing. The first and second ferromagnetic layers 12 and 14 return a magnetic flux. FIG. 2 (a)
Then, the magnetization direction of the first ferromagnetic layer 12 is
_{Assuming that the} storage state is "0", for example, the magnetization direction of the first ferromagnetic layer 12 and the magnetization direction of the third ferromagnetic layer 11i in FIG. Are antiparallel, and the storage state of the memory cell 10 _{i, j} can be set to, for example, “1”.

[0031] Incidentally, the third ferromagnetic layer 11 _n word lines, if the bit line BL _m a laminate having a longitudinal direction perpendicular thereto, as shown in FIG. 6 (c), the memory cell 10 _n, An integrated storage device in which _m are arranged in an array in the bit line direction and the word line direction can be configured.

Next, a modification of the first embodiment is shown in FIG.
This will be described with reference to the cross-sectional views and plan views of FIGS. FIG. 3A shows a cross section taken along line AA ′ of FIG. 3B. In this modification, the first ferromagnetic layer 12, the nonmagnetic layer 13,
The storage section C composed of the second ferromagnetic layer 14 is formed on the third ferromagnetic layer 11 constituting a read word line (wiring) via a nonmagnetic insulating layer 16 such as Al ₂ O _3. ing. Further, a passivation film 17 made of Al or the like is provided on the storage section C.
The wiring constituting the write word line Write WL composed of a laminated film of the nonmagnetic conductive layer 18 and the ferromagnetic layer 19 is arranged in the direction perpendicular to the plane of FIG. 3A (the y direction in FIG. 3B). It is growing. The third ferromagnetic layer has a longitudinal direction (y direction in FIG. 3B) in a direction perpendicular to the paper surface of FIG. 3A and is formed in a stripe shape. The storage units C _{i-1, j} and C _{i, j} in the same column are
A bit line BL electrically connected by a conductive layer 59 of Cu or the like and extending in the y direction is configured. The magnetization direction of the third ferromagnetic layer 11 is fixed to be substantially the same as the longitudinal direction, and this direction is the direction from the front to the back of the drawing in FIG. 3A (the y direction in FIG. 3B). is there. Write word line Write
WL is composed of two layers, a nonmagnetic conductive layer 18 and a ferromagnetic layer 19, and has an effect that an efficient write operation can be performed with a small current consumption.

In this modification, unlike the first embodiment, the write word line Write WL and the bit line B.
By passing a current through L. at the same time, a combined magnetic field is formed and stored information is written into the storage unit C. On the other hand, reading is performed in the same manner as in the first embodiment using the BL and the reading word line 11.

As described above, the write word line Write WL
By making the read word line and the read word line Read WL in different layers, the configuration of the write word line can be optimized so that writing can be performed with the minimum current.

FIG. 4 (a) shows a transistor Tr for reading selection connected to one end of the storage section C, the storage section C connected to a plate potential via the transistor Tr, and the other end of the storage section C connected. FIG. 3 is a circuit diagram in a case where is connected to a bit line BL. The read selection transistor Tr is the read WL
To connect / disconnect the storage unit C to / from the plate.

FIG. 4 (b) shows the circuit section 10 'of FIG. 4 (a).
FIG. 3 is a cross-sectional view illustrating an example of an element structure corresponding to FIG. An element isolation region 22 is formed on the main surface of the semiconductor substrate 21, and a source / drain diffusion layer 23 and a gate electrode G are provided in an element region insulated between adjacent element regions by the element isolation region 22. A transistor Tr is formed. An interlayer insulating film 25 covering this transistor is formed on the substrate 21, and a third magnetization direction is fixed on the interlayer insulating film 25 in one direction and has a longitudinal direction (a direction perpendicular to the paper surface of FIG. 4B). The ferromagnetic layer 11 and the storage section C are stacked. The third ferromagnetic layer is connected to one of the source / drain diffusion layers 23 of the readout selection transistor via a contact 24 formed in the interlayer insulating film 25. The other source / drain diffusion layer 23 is connected to the plate potential, and the third ferromagnetic layer 11 can be connected to the plate by turning the read selection transistor from the OFF state to the ON state. Note that the selection Tr can be provided for each of the serially connected storage units corresponding to the resistance change rate of the magnetoresistance effect. That is, if the rate of change in resistance is high enough to be read as a switching operation, the selection transistor Tr does not need to be provided, and the lower the rate of change, the smaller the number of storage units in the cell block connected to the selected Tr. is there.

(Second Embodiment) A second embodiment of the present invention relates to a magnetic storage device having a metal base transistor.

FIG. 5A is a simple circuit diagram in which a memory cell 30 is connected to a write word line Write WL, a read word line Read WL, a bit line BL, a plate potential Plate, and the like. The memory cell 30 is composed of a metal base transistor, and the collector is a read word line Read.
WL, and the emitter is connected to bit line BL. The base layer is connected to a plate potential Plate via a read selection transistor Tr.

FIG. 5B is a sectional view of a metal base transistor constituting the memory cell 30. Base layer B is
Third made of CoPt or the like and having a longitudinal direction perpendicular to the paper surface.
Ferromagnetic layer 31, nonmagnetic conductive layer 32 of Cu, Au, etc., CoFe
And a first ferromagnetic layer 33 composed of
A non-magnetic conductive layer 35 of Cu, Au or the like and a second ferromagnetic layer are formed on the layer 33 via a non-magnetic tunnel insulating layer 34 of Al ₂ O ₃ , STO or the like.
An emitter E consisting of 36 is formed. The third ferromagnetic layer 31 has a Schottky junction with a collector C composed of a semiconductor substrate 37 and the like.

To read the recorded magnetization, a negative voltage (-V (V> 0) is applied to the emitter E, hot electrons are tunnel-injected into the base layer B, and the hot electron current flowing into the collector over the Schottky barrier is detected. It is measured as a collector current Ic.Ic flows when the voltage V exceeds the barrier height of the Schottky barrier.The magnetization directions of the third ferromagnetic layer 31 and the first ferromagnetic layer 33 constituting the base layer are parallel. In the state (1), the electron transmissivity is about 9 to 19 times as large as that in the antiparallel state.The collector current fluctuates due to the difference in the transmissivity.
The magnetization direction stored in the ferromagnetic layer 33 is read out.

The second ferromagnetic layer 36 constituting the emitter
As a result, the magnetic flux returns between the first ferromagnetic layer 33 and a good storage state. In the present embodiment, the read word line Read W.
In addition to L., a write word line Write WL was formed on the emitter E via a non-magnetic insulating layer.

(Third Embodiment) A third embodiment of the present invention relates to a magnetic storage device having a spin transistor.

FIGS. 6A and 6B are cross-sectional views showing spin transistors in different storage states. Second
The stacked body of the ferromagnetic layer 41, the nonmagnetic layer 42, and the first ferromagnetic layer 43 constitutes a storage section and also constitutes an emitter E. On the first ferromagnetic layer 43, a nonmagnetic layer serving as a base layer is formed. A collector including the third ferromagnetic layer 45 is formed via the conductive layer 44.
The third ferromagnetic layer 45 has a longitudinal direction in a direction perpendicular to the plane of FIG. 6A, and has substantially the same magnetization direction as the longitudinal direction.
On the other hand, in the first ferromagnetic layer 43, the magnetization direction is written by a synthetic magnetic field generated by flowing a current to the emitter and the collector, and the written magnetization direction and the third ferromagnetic layer 45 are written.
The amount of the collector current and the level of the collector voltage are determined by the relative angle with respect to the fixed magnetization direction. By judging these relative differences, the storage state can be read.

[0044]

According to the present invention, there is provided a magnetic storage device in which a sense current flows in a direction perpendicular to a film surface, which has a high sense sensitivity, is nonvolatile, has a high SN ratio, has a high speed access, and has a high integration. As a result, a magnetic storage device that can obtain the effect of the structure and the like can be obtained.

[Brief description of the drawings]

1A and 1B are a cross-sectional view and a plan view illustrating three cells for explaining a magnetic storage device according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of a storage cell for describing an operation of the magnetic storage device according to the first embodiment.

FIGS. 3A and 3B are a cross-sectional view and a plan view illustrating two cells for describing a magnetic storage device according to a modification of the first embodiment; FIGS.

FIGS. 4A and 4B are a circuit diagram and a cross-sectional view of a periphery including a memory cell of a magnetic storage device according to a modification of the first embodiment;

5A and 5B are a circuit diagram around a memory cell including a memory cell and a cross-sectional view of the memory cell for explaining a magnetic storage device according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a memory cell for explaining a magnetic storage device according to a third embodiment of the present invention, and a plan view of a device in which memory cells of the magnetic storage device of the present invention are integrated. is there.

FIG. 7 is a plan view and a cross-sectional view of a memory cell of a magnetic storage device according to the related art of the present invention, and a characteristic diagram showing an MR change rate of a GMR film.

FIG. 8 is a cross-sectional view for explaining storage magnetization of a GMR film according to a conventional technique.

[Explanation of symbols]

 1… GMR film 2,3… bit line 4… word line 1a, 1C, 11,12,14,19,31,33,36,41,43,45… ferromagnetic layer 1b, 13,18,32,35 , 42,44… Nonmagnetic layer 10,30… Memory cell 16… Tunnel insulating layer 17… Passivation film 21… Semiconductor substrate 22… Element isolation region 23… Source / drain diffusion layer 24… Contact 25… Interlayer insulation Film 34: insulating layer 37: semiconductor substrate 59: conductive layer C: storage unit G: gate

Continued on the front page (72) Inventor Masashi Sahashi 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Kawasaki Plant

Claims (12)

[Claims] A first ferromagnetic layer and a second ferromagnetic layer laminated with a first non-magnetic layer interposed therebetween; and a first ferromagnetic layer and a second ferromagnetic layer laminated via a second non-magnetic layer. A magnetic storage device comprising: a ferromagnetic layer and a third ferromagnetic layer having a longitudinal direction in a predetermined direction and formed in a stacked manner. 2. A storage section in which a first ferromagnetic layer and a second ferromagnetic layer are formed via a first nonmagnetic layer, and the first ferromagnetic layer and a second ferromagnetic layer via the second nonmagnetic layer. A third ferromagnetic layer laminated and formed with a ferromagnetic layer and having a longitudinal direction in a predetermined direction, and the first ferromagnetic layer based on a relative difference between magnetization directions of the first ferromagnetic layer and the third ferromagnetic layer. And a reading means for reading a resistance change between the third ferromagnetic layer and the third ferromagnetic layer. 3. A laminate comprising a first ferromagnetic layer and a second ferromagnetic layer with a first non-magnetic layer interposed therebetween, and a plurality of current paths having a longitudinal direction in a predetermined direction. A memory section, and a plurality of stripe-shaped layers having a longitudinal direction substantially perpendicular to the predetermined direction;
And a third ferromagnetic layer formed by lamination. 4. The magnetic memory device according to claim 1, wherein the length of said third ferromagnetic layer is at least five times its width. 5. The magnetic memory device according to claim 1, wherein a magnetization direction of said third ferromagnetic layer is substantially the same as a longitudinal direction thereof. 6. The magnetic memory according to claim 1, wherein an axis of easy magnetization of said first ferromagnetic layer is substantially the same as a longitudinal direction of said third ferromagnetic layer. apparatus. 7. The wiring according to claim 1, further comprising a wiring laminated on said storage section, wherein the wiring has a longitudinal direction coinciding with the longitudinal direction of said third ferromagnetic layer. A magnetic storage device according to any one of the above. 8. The magnetic memory device according to claim 7, wherein said wiring comprises a laminated film of a nonmagnetic layer and a ferromagnetic layer. 9. The magnetic storage according to claim 1, wherein one or a plurality of the storage units forming a current path are connected to a selection transistor for selecting the storage unit. apparatus. 10. The second non-magnetic layer is insulative,
4. The magnetic memory device according to claim 1, wherein a tunnel junction is formed between the first ferromagnetic layer and the third ferromagnetic layer. 11. The first ferromagnetic layer, the second nonmagnetic layer, and the third ferromagnetic layer together form a base layer,
4. The magnetic memory device according to claim 1, wherein a semiconductor layer having a Schottky junction is formed on the third ferromagnetic layer, and the second ferromagnetic layer forms an emitter. 12. The semiconductor device according to claim 1, wherein said first ferromagnetic layer forms an emitter layer, said third ferromagnetic layer forms a collector layer, and said second nonmagnetic layer forms a base layer. The magnetic storage device according to claim 1.