JP4226679B2 - Magnetic storage - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a large output signal at the time of reading and facilitates high integration.Magnetic storageRelated.
[0002]
[Prior art]
For example, Japanese Patent Application No. 8-306014 and Japanese Patent Application No. 5-101641 have proposed magnetic storage devices using the magnetization state of a magnetic thin film as digital bit information storage and using the resistance change.
[0003]
First, problems of the magnetic storage device described in Japanese Patent Application No. 5-101641 (hereinafter referred to as Prior Art 1) will be described. FIG. 28 is a diagram showing a configuration of a memory cell described in the prior art 1. As shown in FIG. 28A is a plan view, FIG. 28B is a cross-sectional view taken along the line AA ′ in FIG. 28A, and FIG. 28C is a cross-sectional view taken along the line BB ′ in FIG. The figure is shown. In FIG. 28, 92 is a data selection line, and 81 and 83 are ferromagnetic films having a coercive force of, for example, 20 Oe or more and substantially the same coercive force. The ferromagnetic films 81 and 83 are magnetically coupled to each other with the nonmagnetic conductive film 82 interposed therebetween. The ferromagnetic film 81 / nonmagnetic conductive film 82 / ferromagnetic film 83 form the magnetic memory unit 16 that changes in resistance depending on the magnetic state.
[0004]
The memory cell stores a magnetic state at a portion where the magnetic storage unit 16 and the data selection line 92 intersect. That is, in FIG. 28, one memory cell is formed in each of two adjacent data selection lines 92. Further, the first conductive layer 84 and the second conductive layer 85 reduce the resistance of the connection portion of the adjacent memory cell, and extend in a direction orthogonal to the data selection line 92, so that the ferromagnetic thin film 81 The non-magnetic conductive film 82 / the ferromagnetic film 83 / the first conductive layer 84 / the second conductive layer 85 form the data transfer line 80.
[0005]
Further, the data selection line 92 and the data transfer line 80 are electrically separated by the interlayer insulating film 91. The data transfer line 80 and the data selection line 92 are formed in directions orthogonal to each other, and form magnetic fields in directions orthogonal to each other.
[0006]
The easy magnetization direction of the ferromagnetic films 81 and 83 is formed in parallel to the longitudinal direction of the data selection line 92 (hereinafter referred to as the data selection line direction). Then, the magnetization directions of the ferromagnetic films 81 and 83 are stored in one direction or the opposite direction along the easy magnetization direction as a whole in each film, so that two states, that is, 1-bit logical information. Is remembered.
[0007]
The magnetization direction of the ferromagnetic film 81 in the memory retention state is formed to be almost antiparallel to the magnetization direction of the ferromagnetic film 83. Therefore, when the ferromagnetic films 81 and 83 are far from their edges, the magnetization directions of the ferromagnetic films 81 and 83 are most stable when the films are antiparallel due to the influence of anisotropic magnetization.
[0008]
Further, when the direction of the current of the data transfer line 80 and the direction of magnetization of the ferromagnetic films 81 and 83 are perpendicular, the resistance of the data transfer line is low, and when the direction of current and the direction of magnetization are parallel, the data The resistance of the transfer line is increased.
[0009]
In the configuration of the prior art 1, a constant direct current I is applied to the data transfer line 80._BLOf the data transfer line 80 when flowing from the A to the A 'direction_BLCurrent I of the data selection line 92_WLThe dependency is shown in FIG. FIG. 30 shows the magnetization state of the ferromagnetic film 81 corresponding to the arrangement state by an arrow in the plan view of FIG. Note that the magnetization state of the ferromagnetic film 83 is obtained by inverting the magnetization state of the ferromagnetic film 81 up and down. Here, FIG. 30A shows the state D of FIG. 29, and FIG. 30B shows the state C of FIG.
[0010]
The anisotropy due to the demagnetizing magnetic field due to the free magnetic pole is large at the edge of the ferromagnetic thin film, and magnetization along the edge is formed near the edge of the data transfer line 80. In the central portion far from the edge of the data transfer line 80, the magnetization easy direction of the ferromagnetic films 81 and 83 is formed in parallel to the direction of the data selection line 92, so that the magnetization is also parallel to the data selection line 92. To change.
[0011]
Here, by passing a current from the A to A ′ direction through the data transfer line 80, the ferromagnetic film 81 has a magnetic field parallel to the data selection line 80 and upward, and the ferromagnetic film 83 has a downward direction. A magnetic field is formed. When such a magnetic field is applied to the state C (FIG. 30 (b)), the state C (FIG. 30 (b)) is more ferromagnetic than the state D (FIG. 30 (a)). The angle formed between the magnetization vector of the film 81 and the ferromagnetic film 83 and the current direction is reduced, and the orientation is more parallel to the current direction, so that the resistance is further increased.
[0012]
A magnetic field parallel and rightward to the data transfer line 80 is formed by the current of the data selection line 92 flowing in the A → A ′ direction (downward), and the combined magnetic field with the magnetic field formed by the current flowing in the data transfer line is ferromagnetic. The magnetic field is directed to the upper right with respect to the film 81. Therefore, when the data selection line current further increases positively, the magnetization vector of the ferromagnetic film 11 changes from downward to upward, and from the data state of the state C (FIG. 30B) to the state D (FIG. 30A). ) To the data state.
[0013]
The data selection line current required at this time is smaller than the data selection line current required to make the magnetization vector parallel to the data transfer line when no current is passed through the data transfer line.
[0014]
Next, the nondestructive reading method described in the prior art 1 will be described. In the non-destructive reading method of the prior art 1, a negative current I is applied to the data selection line 92._WLIt is done by flowing.
[0015]
Negative current I_WLGenerates a magnetic field parallel and leftward to the data transfer line 80, and the current I flowing through the data transfer line 80._BLMagnetic field H formed by_BLAnd the combined magnetic field is a magnetic field directed upward to the left with respect to the ferromagnetic film 81. Therefore, a negative current I is applied to the data selection line 92._WLWhen the transition is made from the upper right direction magnetization state (FIG. 30A) to the upper left direction magnetization state (FIG. 30C), a vector that is inverted by 180 degrees from the magnetization vector at the end of the data transfer line 80. Can be transferred without being formed inside the ferromagnetic film 81.
[0016]
On the other hand, the data selection line 92 has a negative current I_WLWhen the transition is made from the magnetization state of the right downward vector (FIG. 30B) to the upper left magnetization state (FIG. 30C), the magnetization vector at the end of the data transfer line 92 is inverted by 180 degrees. It is necessary to form the magnetization to be formed inside the ferromagnetic film 81.
[0017]
Therefore, by making the current supplied to the data selection line 92 sufficiently negative, a magnetic wall (Newel Wall) having a direction different from the magnetization vector at the end of the data transfer line 80 by 180 degrees is formed along the data transfer line 80. (FIG. 30D). As the domain wall is formed, the resistance R of the data transfer line 80 is increased._BLRises rapidly (FIG. 29: state A). Unlike the case where a positive current is applied to the data selection line 92, this increase in resistance does not cause data destruction even if the current in the data selection line 92 is increased, so that nondestructive reading is possible.
[0018]
However, in this nondestructive reading method, it is necessary to form a domain wall in the ferromagnetic film 81 that is 180 degrees different from the magnetization vector at the end of the data transfer line 80. The magnitude of the magnetic field necessary for forming the domain wall is necessarily larger than the magnitude of the magnetic field necessary for directing the magnetization of the ferromagnetic film 81 in the direction of the magnetization vector at the end of the data transfer line 80.
[0019]
This is because it is necessary to direct the magnetization of the central portion of the ferromagnetic film 81 in the direction opposite to the magnetization direction of the peripheral portion of the ferromagnetic film 81, so that the exchange interaction between the magnetization of the peripheral portion and the magnetization of the central portion This is because a larger magnetic field is required.
[0020]
Therefore, under the condition that the influence of the offset magnetic field is small, the current of the data selection line necessary for nondestructive reading is equal to or greater than the lower limit of the current of the data selection line necessary for writing, and it is necessary to pass a large current through the data selection line during reading. is there.
[0021]
By supplying a large current, electromigration is likely to occur due to an increase in the current of the data selection line, and reliability is likely to be reduced. Further, the rate of change in resistance decreases or a local change occurs due to heat generated from the data selection line. In addition, since the degree of temperature rise varies depending on the number of readings, a resistance change depending on the reading history occurs.
[0022]
That is, the signal output of read data changes or the resistance value of a neighboring memory cell changes. For this reason, there is a problem that when the integration is increased, the array noise rises and it becomes difficult to read.
[0023]
Next, problems of Japanese Patent Application No. 8-306014 (hereinafter referred to as Prior Art 2) will be described. FIG. 31 is a diagram showing a configuration of the magnetic storage device of the conventional technique 2. 31A is a plan view, FIG. 31B is a cross-sectional view taken along the line AA ′ in FIG. 31A, and FIG. 31C is a cross-sectional view taken along the line BB ′ in FIG. Is shown. In FIG. 31, the same components as those in FIG. 28 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0024]
In the prior art 2, instead of the ferromagnetic film 83, a soft magnetic film 101 having a coercive force smaller than that of the ferromagnetic film 81, for example, a coercive force of 20 Oe or less is formed. The ferromagnetic film 81 and the soft magnetic film 101 are magnetically coupled to each other with the nonmagnetic conductive film 82 interposed therebetween, and the ferromagnetic film 81 / nonmagnetic conductive film 82 / soft magnetic film 101 are laminated. A magnetic storage unit 16 is formed which causes a change in resistance depending on the magnetic state in the structure. These are memory cells that store a magnetic state in a place formed by being stacked with the data selection line 92. In FIG. 31, one memory cell is formed.
[0025]
In prior art 2, the easy magnetization direction of the ferromagnetic film 81 and the soft magnetic film 101 is formed in parallel with the data transfer line 80, and the magnetization direction of the ferromagnetic film 81 is 1 along the easy magnetization direction. By storing in one direction and in the opposite direction, 1-bit (two) logical information is stored.
[0026]
Further, when the thickness of the nonmagnetic conductive film 82 is smaller than the free path of the conductive carriers therein, the resistance of the data transfer line is obtained when the magnetizations of the ferromagnetic film 81 and the soft magnetic film 101 are parallel. Is low and the resistance of the data transfer line is the highest when the magnetizations of the two films 81 and 101 are antiparallel.
[0027]
In the prior art 2, the data transfer line 80 and the data selection line 92 are parallel on the memory cell. FIG. 32 shows an example in which a matrix is formed with the memory cells of Conventional Technique 2. In FIG. 32, the data selection line 101 is indicated by a dotted line.
[0028]
In order to realize a high-density memory cell matrix, when trying to arrange memory cells at each intersection of the data transfer line 80 and the data selection line 92, in the conventional technique 2, the data selection line 92 is bent and the data transfer line 80 is bent. And the data selection line 92 need to be changed in the orthogonal direction, or the data transfer line 80 needs to be bent.
[0029]
Further, for example, if a bent portion is formed in the data selection line 92, the current does not flow in parallel with the data transfer line in the bent portion, so that it does not function effectively as a portion for storing information. Therefore, the length in the longitudinal direction of the data transfer line 80 of the memory cell needs to be twice the length y of the bent portion of the data selection line 92 in addition to the length x of the portion storing information. This hinders integration.
[0030]
Of course, the data selection line 92 having a bent pattern is difficult to achieve high integration because the pattern interval is not constant and lithography and etching allowance are required as compared with the data selection line pattern having a linear shape. . In addition, it is necessary to form the data selection line 92 and the data transfer line 80 by laminating them in parallel. Compared with the case where the data selection line 92 and the data transfer line 80 are formed orthogonally, the direction perpendicular to the data transfer line is required. The margin for misalignment becomes smaller.
[0031]
By the way, in the prior art 2 (Japanese Patent Application No. 8-306014), the magnetization easy direction of the ferromagnetic film 11 is made to coincide with the direction of the synthetic magnetic field formed by the data selection line 92 and the data transfer line 80. A memory cell is also disclosed.
[0032]
In such a memory cell configuration, when a plurality of memory cells are connected to the data transfer line 80 and a plurality of data transfer lines are formed with respect to the data selection line 92, the magnetization of the ferromagnetic film 11. When writing arbitrary information using magnetization in two directions along the easy direction, the current of not only the data transfer line 80 but also the data selection line 92 changes to at least binary according to the write information. It is necessary to let
[0033]
The reason for this will be described below. First, consider writing binary information “0” and “1” given by a magnetic field generated by the data transfer line 92 to a specific memory cell selected by the data selection line 92.
[0034]
When writing binary information, the magnetic field in the easy magnetization direction created by the data transfer line corresponding to the two magnetization information is associated with the bit information “0” and “1”, respectively, and H_BL0And H_BL1And Further, the magnetic field in the easy magnetization direction formed by the selected data selection line is applied to the selected memory cell connected to the selected data selection line._WLSELAnd In addition, the magnetic field generated by the unselected data selection line is set to H with respect to an unselected memory cell connected to the unselected data selection line._WLUNSELAnd
[0035]
Here, the magnitude of the coercive force of the ferromagnetic film 81 along the easy magnetization direction is represented by H_K, Bias magnetic field to H₀Suppose that the positive and negative directions of magnetization along the easy magnetization direction correspond to information “0” and “1”. Here, the condition for writing information “0” in the selected memory cell is as follows.
[0036]
H_BL0+ H_WLSEL> H_K+ H₀    (1)
Further, at this time, “0” is not erroneously written in the memory cell connected to the same data transfer line as the memory cell to which the information “0” is written and to which the unselected data selection line is connected. The conditions are as follows.
[0037]
H_BL0+ H_WLUNSEL<H_K+ H₀    (2)
The following equation is obtained by solving equations (1) and (2) simultaneously.
[0038]
H_WLUNSEL<H_WLSEL    (3)
Next, the condition for writing information “1” in the selected memory cell is as follows because it is necessary to apply magnetization in the direction opposite to “0”.
[0039]
H_BL1+ H_WLUNSEL<-H_K+ H₀    (4)
Further, at this time, “1” is not written by mistake in the memory cell connected to the same data transfer line as the memory cell to which the information “1” is written and connected to the unselected data selection line. The conditions are as follows.
[0040]
H_BL1+ H_WLUNSEL> -H_K+ H₀    (5)
Then, the following equation is obtained by solving equations (4) and (5) simultaneously.
[0041]
H_WLSEL<H_WLUNSEL    (6)
Both equations (3) and (6) are constant H_WLSELAnd H_WLUNSELThen I can not be satisfied. That is, it can be seen that in the memory cell configuration method of the prior art 2, it is necessary to change the current flowing through the data selection line depending on the condition for writing “0” and “1”.
[0042]
That is, when a plurality of memory cells are connected to one data selection line and random data is written to them, the magnitude of the current of the data selection line is set to at least “0” and “1” writing. It is necessary to give binary values while shifting the time and write to each of the opposite magnetizations.
[0043]
Therefore, when writing “0” and “1”, the current direction of the data selection line is reversed and “1” and “0” are written, and ternary control is required for driving the data selection line. It becomes complicated.
[0044]
In addition, there is a problem that high-speed operation is difficult in order to secure a sufficient current value that changes to binary during writing and to stabilize the current value.
[0045]
[Problems to be solved by the invention]
As described above, the configuration of the memory cell using the conventional magnetoresistive element has a drawback that it is difficult to achieve high integration while obtaining a large read signal. Furthermore, it is necessary to change the current direction of the data selection line in the read and write operations, or to change the current direction of the data selection line at the time of writing in accordance with the state of the bit to be stored. There were drawbacks.
[0046]
An object of the present invention is to simplify the circuit of the data selection line by making the direction of the current flowing through the data selection line constant during the data write operation and the read operation, and to achieve high integration of the high-density memory cells.Magnetic storageIt is to provide.
[0047]
[Means for Solving the Problems]
[Constitution]
The present invention is configured as follows to achieve the above object.
[0048]
  (1) A magnetic memory device according to an example of the present invention includes a first magnetic body, a second magnetic body having a smaller coercive force than the first magnetic body, the first magnetic body, and the second magnetic body. A data transfer line including a non-magnetic material formed between the data transfer lines, and a data selection line arranged to intersect the data transfer line, and the first magnetic material has an easy magnetization direction and a first magnetization direction. The easy magnetization directions of the two magnetic materials are essentially parallel to the longitudinal direction of the data selection line, respectively.And the magnetization direction of both the first and second magnetic bodies is changed to a first direction parallel to the easy axis or a first direction by a magnetic field generated from a current flowing in the data selection line and the data transfer line. Store binary data by pointing in one of the second directions opposite to the one directionIt is characterized by that.
[0049]
  (2) A magnetic storage device according to an example of the present invention includes a plurality of data selection lines, a power supply node for supplying two types of voltages having the same polarity and different sizes to the data selection lines, and an easy magnetic axis. Is a first magnetic body that is parallel to the data selection line, and a second magnetic body that has a magnetic easy axis that is parallel to the data selection line and has a holding force smaller than the holding force of the first magnetic body. And a non-magnetic body formed between the first magnetic body and the second magnetic body, and a data transfer arranged so as to cross the plurality of data selection lines And writing data to the memory cell,A magnetization direction of both the first and second magnetic bodies is changed to a first direction parallel to the easy axis or a first direction by a magnetic field generated from a current flowing through the data selection line and the data transfer line. And store binary data by pointing in either of the second directions opposite toOne of the two types of voltages is supplied to a selected data selection line, and when reading data from the memory cell, the other of the two types of voltages is supplied to a selected data selection line. .
[0050]
In a preferred embodiment, one end of the data transfer line is connected to a voltage source that supplies a constant voltage.
[0051]
(3) A magnetic storage device according to an example of the present invention includes a plurality of data selection lines, a power supply node for supplying two kinds of currents having the same polarity and different sizes to the data selection lines, and an easy magnetic axis. A first magnetic body that is parallel to the data selection line; and a second magnetic body that has a magnetic easy axis parallel to the data selection line and having a holding force smaller than the holding force of the first magnetic body; A data transfer line including a plurality of memory cells each including a first magnetic body and a non-magnetic body formed between the first magnetic body and the second magnetic body, and arranged to intersect the plurality of data selection lines When writing data to the memory cell, one of the two types of current is supplied to the selected data selection line,A magnetization direction of both the first and second magnetic bodies is changed to a first direction parallel to the easy axis or a first direction by a magnetic field generated from a current flowing through the data selection line and the data transfer line. And store binary data by pointing in either of the second directions opposite toWhen reading data from the memory cell, the other of the two kinds of currents is supplied to a selected data selection line.
[0055]
Further, preferred embodiments for the present invention are shown below.
[0056]
In the read operation and the write operation, the data transfer line uses a common binary value.
[0057]
One end of the data selection line has a constant voltage.
[0058]
[Action]
The present invention has the following operations and effects by the above configuration.
[0059]
By using the structure of the present invention, the circuit can be configured with the current direction of the data selection line constant, and in addition, a large amount of read signal can be secured. Here, only a circuit that allows a current to flow in one direction to the driving circuit for the current of the data selection line necessary for reading and writing is sufficient. Therefore, the area of the switch element between the data selection line and the current source can be made smaller and the number of elements can be reduced as compared with the case where a current flows in both directions. Further, even if the potential at one end of the data selection line is fixed, the potential at the opposite end may be simply shifted in one direction, for example, positively than the potential at the one end, and the circuit is simpler than a circuit that generates positive and negative voltages. Thus, a large voltage amplitude can be secured, a current source that generates a negative voltage with respect to the potential at the one end is not necessary, and the circuit area and power consumption can be reduced.
[0060]
Also, one end of the data transfer line can be fixed at a constant voltage, and there is no need to change it. Therefore, the data transfer line can be kept at a low impedance with respect to the power supply, for example, capacitive coupling noise on the data transfer line, which occurs when the potential of the data selection line is changed, can be reduced, and more stable data reading can be performed. realizable.
[0061]
Further, it is not necessary to give two different current values to the data selection line in time series at the time of writing, and the current switching circuit can be simplified. In addition, it is possible to charge the data selection line necessary for switching to two different currents, reduce the time for stabilizing the current, and perform higher speed operation. Furthermore, the charge of the data selection line required for current switching can be reduced, and the power consumption can be further reduced. Further, the wiring area from the current source to the switch element can be reduced, and a higher density memory cell array can be formed.
[0062]
Furthermore, in the structure of the present invention, a configuration in which the data transfer line and the data selection line are orthogonal can be used. Therefore, both the data transfer line and the data selection line can be arranged in a straight line rather than the structure in which the data transfer line and the data selection line are arranged in parallel, and a higher density memory cell can be formed. In addition, a layout in which the data transfer line or data selection line is bent can be changed to a linear layout, the magnetic field formed by the wiring can be made more uniform, the variation between memory cells can be reduced, and the operation can be stabilized. it can. In addition, since the wiring layout is linear, fluctuations in the width of the wiring can be reduced with respect to the lithography and etching of the wiring. Further, the data selection line and the data transfer line can be formed orthogonally, and a margin for misalignment in the plane is increased as compared with the case where the data selection line and the data transfer line are formed in parallel. .
[0063]
By using the structure of the memory cell of the present invention, a sufficient resistance difference can be obtained between data “1” and “0” even if the current of the data transfer line during data reading is small. Therefore, at the time of reading, the resistance change rate decreases or changes locally due to the problem that electromigration due to the current rise of the data selection line tends to occur and the reliability decreases, and the heat generated by the data selection line, Since the degree of temperature rise varies depending on the number of readings, the problem of resistance change depending on the reading history can be reduced. Further, it is possible to reduce the problem that the signal output of the read data changes or the resistance value of the neighboring memory cell changes due to heat generated by the data selection line. Therefore, even if the integration is high, array noise rises and it becomes difficult to read out.
[0064]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0065]
[First Embodiment]
FIG. 1 is a diagram showing a configuration of a memory cell of a magnetic memory device according to the first embodiment of the present invention. 1A is a plan view, FIG. 1B is a cross-sectional view of the A-A ′ portion, and FIG. 1C is a cross-sectional view of the B-B ′ portion.
[0066]
For example, a soft magnetic film 13 having a coercivity smaller than that of the ferromagnetic film 11 is formed on the ferromagnetic film 11 having a coercive force of 20 Oe or more via a conductive nonmagnetic film 12. A barrier metal layer 14 having convex portions is formed on the soft magnetic film 13. A metal conductive layer 15 is formed on the top of the convex portion of the barrier metal layer 14.
[0067]
An interlayer insulating film 21 is formed on the entire surface. A data selection line 22 is formed around a region where the metal conductive layer 15 is not formed.
[0068]
It is a necessary condition that the coercive force of the soft magnetic film 13 is smaller than the coercive force of the ferromagnetic film 11, and the ferromagnetic film 11 is necessarily a ferromagnetic material and the soft magnetic film 13 is a soft magnetic material. It is not necessary. For example, both the ferromagnetic film 11 and the soft magnetic film 13 may be ferromagnetic, or both the ferromagnetic film 11 and the soft magnetic film 13 may be soft magnetic films.
[0069]
Here, as the ferromagnetic film 11, for example, Fe, Ni, Co, Cr, or Mn having a thickness of 0.5 to 500 nm, NiFe, CoFe, NiFeCo, CoPt that is an alloy thereof, or a laminated film thereof is used. Can be used.
[0070]
The soft magnetic film 13 preferably has a coercive force smaller than that of the ferromagnetic film 11 and has the same magnetization as the ferromagnetic film 11, and has a thickness of 0.5 to 500 nm, such as NiFe, CoFe, A laminated film of NiFeCo, CoTaZr, CoNbZr, FeTaN, CoZrNb / NiFe / CoFe, or the like can be used.
[0071]
In order to make the coercive force of the soft magnetic film 13 smaller than the coercive force of the ferromagnetic film 11, for example, not only the material of the soft magnetic film 13 but also the same material as the ferromagnetic film 11 is used. This can also be realized by making the thickness of the soft magnetic film 13 thinner than that of the ferromagnetic film 11.
[0072]
The nonmagnetic film 12 is made of a nonmagnetic material such as Cu, AgCu, or TaN having a thickness of 0.5 to 10 nm, for example. Further, the thickness of the non-magnetic film 12 is formed so as to be thinner than the free path of conduction carriers therein, and when the magnetization vectors of the ferromagnetic film 11 and the soft magnetic film 13 are parallel, data transfer is performed. When the resistance of the line is low and the magnetization vectors of the respective films are antiparallel, the resistance of the data transfer line is selected to be the highest. Further, it is desirable that the exchange magnetic field between the ferromagnetic film 11 and the soft magnetic film 13 is weaker than the coercive force of the soft magnetic film 13 in order to independently control the magnetization vectors of the respective films.
[0073]
Further, in order to make the magnetization of the central portion of the data transfer line 22 in the direction along the data selection line direction independently of the magnetization of the edge portion of the data transfer line 22, the ferromagnetic film 11 and the soft magnetic film 13 It is desirable to increase the thickness of the data transfer line 10 to be thicker than the thickness of the domain wall.
[0074]
Here, the ferromagnetic film 11, the nonmagnetic film 12, and the soft magnetic film 13 form a magnetic memory unit 16 having a laminated structure and a resistance that varies depending on the magnetic state. The magnetic storage unit 16 is a memory cell 23 that stores a magnetic state at a portion that intersects the data selection line 22. That is, in FIG. 1, one memory cell is formed on each of two adjacent data selection lines 22.
[0075]
The barrier metal layer 14 is made of, for example, TaN, TiN, WN, or TaW having a thickness of 1 to 100 nm, and has a role of preventing impurity contamination from the upper structure. The metal conductive layer 15 is formed of, for example, W, Al, AlCu, or Cu having a thickness of 50 to 1000 nm, and serves to reduce the parasitic resistance in the connection region between adjacent memory cells of the data transfer line 10.
[0076]
The interlayer insulating film 21 is made of, for example, a silicon oxide film or a silicon nitride film having a thickness of 5 to 100 nm, and electrically separates the data selection line 22 and the data transfer line 10. The data transfer line 10 and the data selection line 22 are crossed so as to be orthogonal to each other, and form magnetic fields in directions orthogonal to each other.
[0077]
The easy magnetization direction of the ferromagnetic film 11 and the easy magnetization direction of the soft magnetic film 13 are formed in parallel to the longitudinal direction of the data selection line 22. As a method of forming the easy magnetization direction, for example, when NiFe is used as the magnetic films 11 and 13, the film is deposited while applying a magnetic field in the direction along the data selection line 22, thereby approximately 5 to 15 Oe. Magnetic anisotropy can be built in.
[0078]
Then, by storing the magnetization directions of the ferromagnetic film 11 and the soft magnetic film 13 as a whole in one direction and the opposite direction along the easy magnetization direction, for example, two states, that is, one bit Stores logical information.
[0079]
Here, the magnetic field in the A-A ′ direction generated by passing a current through the data selection line 22 is represented as H._WL, The magnetic field in the B-B ′ direction generated by passing a current through the data transfer line 10 is H_BLAnd the directions A → A ′ and B → B ′ are positive, respectively. The direction of these magnetic fields is H_BLCoincides with the direction of easy magnetization and H_WLIs perpendicular to the easy magnetization direction and coincides with the hard magnetization direction.
[0080]
Here, the coercivity of the ferromagnetic film 11 and the soft magnetic film 13 is different, and the magnetization direction of the ferromagnetic film 11 in the memory retention state is substantially parallel to the magnetization direction of the soft magnetic film 13. Formed as follows. This is because the magnetization directions of the ferromagnetic film 11 and the soft magnetic film 13 are antiparallel in the memory retention state.
[0081]
Further, since the direction of easy magnetization of the ferromagnetic film 11 is formed parallel to the data selection line 22, the direction of the combined magnetic field generated from the current flowing through the data selection line 22 and the data transfer line 10 is generally easy to magnetize. Different from direction.
[0082]
Next, the magnetic field H_WLResistance R of the data transfer line 10 in a state where no voltage is applied_BLMagnetic field H_BLThe dependence on is shown in FIG. In FIG. 2, the arrow indicates the direction of the magnetic field history. Further, in FIGS. 3 and 4, the magnetization states of the ferromagnetic film 11 and the soft magnetic film 13 corresponding to the states A to D in FIG. 2 are indicated by arrows.
[0083]
3A shows the magnetization state of the soft magnetic film 13 in the state A, and FIG. 3B shows the magnetization state of the ferromagnetic film 11 in the state A. 3C shows the magnetization state of the soft magnetic film 13 in the state B, and FIG. 3D shows the magnetization state of the ferromagnetic film 11 in the state B.
[0084]
4A shows the magnetization state of the soft magnetic film 13 in the state C, and FIG. 4B shows the magnetization state of the ferromagnetic film 11 in the state c. 4C shows the magnetization state of the soft magnetic film 13 in the state D, and FIG. 4D shows the magnetization state of the ferromagnetic film 11 in the state D.
[0085]
Resistor R in FIG. 2 using FIGS._BLWill be described. In the state A, the magnetization of the central portion away from the edges of the soft magnetic film 13 and the ferromagnetic film 11 is almost antiparallel, so that the resistance R of the data transfer line 10_BLBecomes larger.
[0086]
From state A, the magnetic field H in the positive direction_BLAs the voltage is applied, the magnetic field H_K1Thus, the magnetization of the ferromagnetic film 11 changes from downward to upward and transitions to the state B. In the state B, the magnetization of the central portion of the soft magnetic film 13 and the ferromagnetic film 11 away from the edge is in a parallel state, so that the resistance R of the data transfer line 10_BLBecomes smaller.
[0087]
From state B, magnetic field H_BLThe direction of the magnetic field H_BL-H_K2Then, the magnetization of the soft magnetic film 13 changes from upward to downward and transitions to the state C. In the state C, the magnetizations of the central portions of the soft magnetic film 13 and the ferromagnetic film 11 that are separated from the edge are in an antiparallel state, so that the resistance R of the data transfer line 10_BLWill rise.
[0088]
Furthermore, from state C, the magnetic field H_BLWhen the direction of is further changed to the negative direction, the magnetic field becomes -H._K1Thus, the magnetization of the ferromagnetic film 11 changes from upward to downward and transitions to the state D. In the state D, the magnetization of the central portion of the soft magnetic film 13 and the ferromagnetic film 11 away from the edge is in a parallel state, so that the resistance R of the data transfer line 10_BLDecrease.
[0089]
From state D, magnetic field H_BLIs changed in the positive direction, and the magnetic field H_BLIs H_K2Then, the magnetization of the soft magnetic film 13 changes from downward to upward and transitions to the state A.
[0090]
Here, it is known that, in a ferromagnetic thin film having an easy magnetization direction in the film, the magnitude of the critical magnetic field that causes magnetization reversal in the easy magnetization direction decreases when a magnetic field in the difficult magnetization direction is applied. (Kanehara, Fujiwara, “Thin Film” Yukabo, Applied Physics Selection 3 p.300).
[0091]
This means that in an ideal magnetic thin film having a single magnetic domain, the angle formed by the magnetization vector M of the ferromagnetic film and the easy axis is θ, and the anisotropic magnetic field is H_KThe magnetic field H in the direction of difficult magnetization_WLAnd magnetic field H in the direction of easy magnetic field_BLCan be explained from the fact that the energy E of the magnetic film is as follows.
[0092]
E = (H_K/ 2) x sin²θ-H_BL× cosθ-H_WL× sinθ (7)
Where dE / dθ = 0 and d²E / dθ²Magnetic field H whose magnetization is reversed in the direction of the easy magnetic axis at the point where = 0_BL0Is given. In this case, the following relationship is established from Equation (7).
[0093]
H_BL0= (H_K ^2/3-H_WL ^2/3)^3/2    (8)
FIG. 5 shows a magnetic field H in the direction of difficulty in magnetization._WLOf the ferromagnetic thin film and the magnetic field H_BLIndicates dependency.
[0094]
From equation (8), the magnetic field H in the direction of hard magnetization_WLAs shown in FIG. 5, a magnetic field H that causes magnetization reversal is applied._BL0Can be reduced. In general, H_WLIs almost zero, the coercive force H in the direction of easy magnetism_CH is due to the magnetization mechanism by domain wall motion._C<H_KThe magnetic field H_WLBy increasing H_BL0The characteristic of monotonically decreasing is maintained.
[0095]
Next, the write operation of the magnetic storage device of this embodiment will be briefly described. At the time of writing, for example, a current in the positive direction is supplied to the data selection line 22 and a magnetic field H in the positive direction is supplied._WLForm. This magnetic field H_WLIt is desirable to follow the direction of magnetization at the edge of the data transfer line 10 in order to further reduce the current required for writing the data transfer line 10. Where magnetic field H_WLThe direction of is a magnetization difficult direction, and the magnetic field H_BLIs the direction of easy magnetization.
[0096]
Magnetic field H_WLAs a parameter, the resistance R of the data transfer line 10_BLMagnetic field H_BLThe dependence on is shown in FIG. The magnetic field history in FIG. 6 is the same as that shown in FIG. Magnetic field H_WLIs 0, H_K2> H_WL> 0 or H_WL> H_K2These three cases are shown.
[0097]
As described above, the magnetic field H in the direction of difficult magnetization_WLIs applied to the magnetic field H necessary for the magnetization to reverse._BL0Becomes smaller. For this reason, the magnetic field H_WLBy applying a magnetic field H_BLIs positive, the magnetic field at which the magnetization of the ferromagnetic film 11 is reversed is H_K1Smaller magnetic field H_aIt becomes. Magnetic field H_BL-H is negative, -H_K1Magnetic field H with smaller absolute value_bIt becomes.
[0098]
Further, FIG. 7 shows states A ′ and B ′ (magnetic field H of FIG._WL) And states A and B (magnetic field H)_WLThe magnetization state of the ferromagnetic film 11 and the soft magnetic film 13 corresponding to the case where no is applied is shown.
[0099]
FIG. 7A shows an equal H_BLOn the other hand, the states of the soft magnetic film 13 in the states A ′ and A are indicated by solid lines and dotted lines, respectively. Here, the direction of the magnetic field formed by the data selection line 22 is H_WLIt is shown as FIG. 7B shows an equal H_BLOn the other hand, the states of magnetization of the ferromagnetic film 11 in the states A ′ and A are indicated by solid lines and dotted lines, respectively. Further, FIG. 7C shows an equal H_BLOn the other hand, the magnetization state of the soft magnetic film 13 in the states B ′ and B is indicated by a solid line and a dotted line, respectively. Furthermore, FIG. 7 (d) shows that equal H_BLOn the other hand, the states of magnetization of the ferromagnetic film 11 in the states B ′ and B are indicated by a solid line and a dotted line, respectively.
[0100]
In the state A ′, the magnetization of the central portion of the soft magnetic film 13 and the ferromagnetic film 11 away from the edge is in a parallel state along the edge of the data transfer line more than in the state A. Small H_BLThe direction of magnetization can be changed from negative to positive. Furthermore, the positive magnetic field H_BLIs applied, the magnetic field H_aAs a result, the magnetization of the ferromagnetic film 11 changes from downward to upward, and transitions from the state A 'to the state B'. In the state B ′, the magnetizations of the soft magnetic film 13 and the central part of the ferromagnetic film 11 away from the edge are in a parallel state, and therefore the resistance R of the data transfer line_BLBecomes smaller.
[0101]
From the above, when writing data “0”, for example, by supplying a current to the data selection line 22, the magnetic field H in the positive direction_WLAnd applying a current to the data transfer line 10 to generate a magnetic field H_K1And magnetic field H_aMagnetic field H in the range_BLApply.
[0102]
When data “1” is written, the magnetic field H in the positive direction is supplied by supplying current to the data selection line 22._WL, And by supplying a current to the data transfer line 10, −H_K1And H_bMagnetic field H between_BLApply. Further, for example, the magnetic field H by the data selection line that is not selected._WLThe current is adjusted so that becomes approximately zero.
[0103]
By doing so, the magnetization of the ferromagnetic film 11 changes in the memory cell of the selected data selection line, whereas the absolute value of the magnetic field formed by the data transfer line is changed in the memory cell of the unselected data selection line. Value is H_K1Therefore, the magnetization change of the ferromagnetic film 11 does not occur.
[0104]
Therefore, even when a plurality of memory cells are connected to the data transfer line, data corresponding to the data given to the specific memory cell through the data transfer line is selectively written. In this write operation, the current of the data selection line need only flow in one direction.
[0105]
Next, the read operation of this embodiment will be briefly described. At the time of reading, a current flows in the positive direction through the data selection line 22 connected to the selected memory cell, and the positive magnetic field H_WLAnd the magnetic field H applied to the unselected data selection line 22_WLThe current is adjusted so that becomes approximately zero.
[0106]
Magnetic field H_WLIs 0 or a positive magnetic field (H_K2> H_WL> 0), the resistance R of the data transfer line 10_BLMagnetic field H_BLThe dependence on is shown in FIG. In FIG. 8, the arrow indicates the direction of the magnetic field history in the read operation. As explained in the write operation, the magnetic field H_WLThe magnetic field H required to reverse the magnetization by applying_BL0Becomes smaller. For this reason, the magnetic field in which the magnetization of the soft magnetic film 13 is reversed is also the magnetic field H._BLIf is positive, H_K2Smaller magnetic field H_CIt becomes. Magnetic field H_BL-H is negative, -H_K2Magnetic field H with smaller absolute value_DIt becomes.
[0107]
When reading data, the magnetic field H in the positive direction is supplied by supplying a current to the data selection line._WLAnd current is passed through the data transfer line to generate H_CAnd H_K2And a magnetic field in the range_{H BL}Form.
[0108]
By doing so, the magnetization state changes from the point A in FIG. 8 to the point “0” in the state where the data “0” is written. At the point “0”, the magnetization state shown in FIGS. 7C and 7D is obtained, and the magnetization of the soft magnetic film 13 is maintained in the upper right direction. Therefore, since the magnetizations of the central portions of the soft magnetic film 13 and the ferromagnetic film 11 are aligned in the upper right direction, the resistance of the data transfer line is reduced.
[0109]
On the other hand, in a state where data “1” is written, the magnetization state changes from point A to point “1”. At point “1”, H_CGreater than H_BLIs applied, the magnetization of the soft magnetic film 13 changes from the lower right direction to the upper right direction, and the magnetization states shown in FIGS. 7A and 7B are obtained. Therefore, the magnetizations of the central portions of the soft magnetic film 13 and the ferromagnetic film 11 are directed to the upper right and the lower right, respectively, and the angle formed by the magnetization of the soft magnetic film 13 and the ferromagnetic film 11 is greater than that in the state B ′. Therefore, the resistance of the data transfer line 10 becomes larger than the “0” state.
[0110]
On the other hand, in the unselected data selection line 22, the magnetic field H_WLThe current is adjusted so that becomes substantially 0, for example, a current is passed through the data transfer line 10 to generate H_K2And H_CMagnetic field H for sensing in the range_BLApply. In this way, in a memory cell connected to an unselected data selection line and having data “1”, H_K2Smaller H_BLIs applied, no magnetization reversal occurs, and the magnetization of the soft magnetic film 13 is maintained in the lower right direction. Therefore, since the magnetizations of the central portions of the soft magnetic film 13 and the ferromagnetic film 11 are aligned in the lower right direction, the resistance of the data transfer line is small. In a memory cell connected to an unselected data selection line and having data “0”, the magnetizations of the central portions of the soft magnetic film 13 and the ferromagnetic film 11 are aligned in the upper right direction. Resistance is small.
[0111]
Therefore, in the memory cell connected to the unselected data selection line, the output difference between the data “0” and the data “1” compared to the memory cell connected to the selected data selection line. Is small. Therefore, even when a plurality of memory cells are connected in cascade to the data transfer line 10, it is possible to selectively read data from the memory cell selected using the data selection line. In this read operation, the current of the data selection line only needs to flow in one direction, and the direction of the data selection line may be the same direction as the write operation.
[0112]
Incidentally, when the magnetic coupling between the soft magnetic film 13 and the ferromagnetic film 11 is weak, the magnetization of the soft magnetic film 13 changes from the lower right direction to the upper right direction in the read operation of data “1”. , Magnetic field H_BLEven if the data is “0”, the state returns to the state B in FIG. 8 and the high resistance state is maintained, and the resistances of the data “0” and the data “1” are greatly different.
[0113]
Consider a case where another memory cell connected to a common data transfer line is read after this data “1” has been read. Then, when a plurality of memory cells are connected in cascade to the data transfer line, the series resistance value in the memory cell from which data has been read out is different, and the read margin is greatly reduced.
[0114]
Therefore, in the read operation of data “1”, the magnetization of the soft magnetic film 13 is changed from the upper right direction to the lower right direction and returned to the read start state after the read operation._K2And H_DAnd H in the range_BLIt is desirable to apply.
[0115]
As described above, in this embodiment, reading and writing can be performed by selecting a memory cell connected to the data line by passing a current in one direction through the data selection line and controlling the current direction of the data transfer line. .
[0116]
Next, a plurality of memory cells are connected in series to the data transfer line, a plurality of memory cells are connected to the data selection line, read and write operations can be performed as a memory cell matrix, and a resistance output larger than that of the conventional configuration can be obtained. Indicates that
[0117]
FIG. 9 is a diagram showing an example in which a memory cell matrix is formed by the memory cells of this embodiment. 9A is a plan view showing the arrangement of the memory cell matrix, FIG. 9B is a cross-sectional view of the AA ′ portion of FIG. 9A, and FIG. 9C is FIG. 9A. FIG.
[0118]
In this example, two data transfer lines 10₁, 10₂And two data selection lines 22₁, 22₂Memory cell 23 at each intersection of₁₁, 23₁₂, 23_{twenty one}, 23_{twenty two}Is formed. Here, the data selection line 22₁Is the current source I_WLIs a selected data selection line connected to the memory cell 23₁₁, 23_{twenty one}Positive magnetic field H_WLgive. On the other hand, the data selection line 22₂Is a data selection line that is not selected and is not connected to a current source.
[0119]
Further, the data transfer line 10₁10₂Current source I_BLIs connected to the memory cell 23₁₁, 23_{twenty one}Are selectively written and read. In this case, an unselected data selection line 22₂Memory cell 23 connected to₁₂, 23_{twenty two}Therefore, it is necessary to prevent erroneous writing, erroneous reading, and data destruction.
[0120]
By the way, as a result of detailed examination of the operating magnetic field conditions of the memory cell, in the magnetic memory device described in the prior art, when the absolute value of the current that flows when the data selection line is read is less than or equal to the absolute value of the current that flows when the data is written It turns out that there is a problem. In the following discussion, for the sake of simplicity, when the current flowing through the data selection line is 0, the magnetic field H_WLDirection bias field is H in equation (8)._KWhen the current flowing through the data transfer line is zero,_BLDirection bias field is H in equation (8)._KIt is assumed that the effect of magnetization in the data transfer line direction at the edge of the data transfer line can be ignored. The arrangement of the memory cells in the prior art 1 may be the same as that shown in FIG.
[0121]
First, it will be described that the resistance change at the time of reading is very small in the configuration of the related art 1. For writing, magnetic field H_BLAnd magnetic field H_WLFIG. 10 (a) shows the restricted area for. In FIG. 10A, the horizontal axis represents the anisotropic magnetic field H of the ferromagnetic film 11 and the soft magnetic film 13._KMagnetic field H normalized by_WL, The vertical axis is the magnetic field H_KMagnetic field H normalized by_BLIs shown.
[0122]
In the figure, because of structural variations or current source current and resistance variations, H_WLAnd H_BLThe hatched area indicates a condition for stably writing a memory cell even if there is an error of ± 15.8%.
[0123]
Here, the writable area of the cell is an area surrounded by three restricted areas. First, the first limit is a lower limit determined by the magnetic field at which the magnetizations of the central portions of the ferromagnetic film 11 and the soft magnetic film 13 are reversed, which is obtained by Expression (8). When the magnetic field is lower than the lower limit, the magnetization of the ferromagnetic film 11 and the soft magnetic film 13 is not reversed, and writing cannot be performed.
[0124]
The second limitation is the magnetic field H formed by the data selection line 22._WLIs H_KIs greater than the magnetic field H that causes magnetization switching._BLThis is because the magnetization information stored in the memory cell 23 is lost.
[0125]
The third restriction is that the selected data selection line 22₁The magnetic field formed by the adjacent memory cells 23₁₂, 23_{twenty two}This is because the magnetic field H in the positive direction is generated at the same time, and thus erroneous writing occurs.
[0126]
As shown in FIG. 9B, when the width of the data selection line 22 is w, the interval between the data selection lines is s, and the distance between the data selection line 22 and the center of the data transfer line 10 is h. Selected memory cell 23₁₁Magnetic field H in the center of_WLIs the data selection line 22₁Adjacent memory cells 23 under the conditions formed by the current flowing through_{twenty one}The positive magnetic field formed above is wh / π {h²+ (W + s)²}.
[0127]
In FIG. 10A, the results obtained with h = 0.45 μm, w = 0.6 μm, and s = 0.4 μm are used. In this case, 0.07H is placed on the adjacent non-selected memory cell._WLThe magnetic field is formed. In this case, the condition for preventing erroneous writing is H from the equation (8)._BL ^2/3+ (0.07H_WL)^2/3<H_K ^2/3It becomes.
[0128]
Further, in the configuration of the prior art 1, the method of flowing the current direction of the data selection line 22 to the side opposite to the writing at the time of reading requires a larger current value for the reading than the writing as described in the prior art.
[0129]
FIG. 10B shows that the method of flowing the current direction of the data selection line at the time of reading in the same direction as at the time of writing in the configuration of the prior art 1 has a small read signal amount. FIG. 10B shows the magnetic field H with respect to readout._BLAnd magnetic field H_WLThe horizontal axis indicates the anisotropic magnetic field H of the ferromagnetic film 11 and the soft magnetic film 13._KMagnetic field H normalized by_WL, The vertical axis is the magnetic field H_KMagnetic field H normalized by_BLIs shown.
[0130]
In the figure, the magnetic field H due to structural variations or current source resistance variations._WLAnd magnetic field H_BLThe hatched area indicates a condition that can be stably read from the memory cell even if there is a variation of ± 15.8%.
[0131]
Further, in the cell readable region, the amount of change of the resistance value from the resistance value in the anti-parallel state is indicated by a dotted line as the read signal amount ΔGMR. Here, ΔGMR is the amount of change in resistance when the ferromagnetic film 11 and the soft magnetic film 13 are in the parallel state with reference to the resistance value when the magnetization is in the antiparallel state, that is, the maximum signal output obtained. It is normalized by. This is because ΔGMR = sin, where θ is the angle between the magnetizations of the ferromagnetic film 11 and the soft magnetic film 13.²It can be obtained by (θ / 2).
[0132]
As shown in FIG. 10B, in the configuration of the prior art 1, the condition that can be stably read from the memory cell even when there is a variation of ± 15.8% is ΔGMR of about 0.2 at most. A large read output cannot be obtained.
[0133]
Next, it is shown that ΔGMR can be secured large in the configuration of the present embodiment. First, regarding writing, H_BLAnd H_WLFIG. 11 (a) shows the restricted area for. Here, the anisotropic magnetic field of the soft magnetic film 13 is set to H._K2And the anisotropic magnetic field of the ferromagnetic film 11 is H_K1And H_K1= 0.4H_K2It is said.
[0134]
In FIG. 11A, the horizontal axis represents the anisotropic magnetic field H of the ferromagnetic film 11._K1H normalized by_WLThe vertical axis is H_K1H normalized by_BLIs shown. In the figure, because of structural variations or current source current and resistance variations, H_WLAnd H_BLThe hatched area indicates a condition for stably writing a memory cell even if there is an error of ± 15.8%.
[0135]
Here, the writable area of the memory cell is an area surrounded by three restricted areas as in the prior art 1. The first is a lower limit determined by the magnetic field at which the magnetization of the central portion of the ferromagnetic film 11 is reversed._BL ^2/3+ H_WL ^2/3<H_K1 ^2/3Is a condition. Below this, the magnetization of the memory cell is not reversed and writing is not possible.
[0136]
The second is the magnetic field H formed by the data selection line 22._WLIs H_K1If it is larger than this, the magnetic field that causes the magnetization switching becomes 0, and this is a limitation resulting from the disappearance of the magnetization information stored in the memory cell 23.
[0137]
Third, the magnetic field formed by the data selection line 22 is applied to the adjacent memory cell 23.₁₂, 23_{twenty two}H_WLThis is a limitation caused by the generation of a magnetic field in the direction, which in turn causes the magnetization of the soft magnetic film 13 to reverse and cause erroneous writing.
[0138]
Selected memory cell 23₁₁, 23_{twenty one}Magnetic field H at the center of_WLAdjacent memory cells 23 under the condition that is formed.₁₂, 23_{twenty two}H formed on_WLThe magnetic field in the direction is wh / π {h²+ (W + s)²}.
[0139]
In FIG. 11A, the results obtained with h = 0.45 μm, w = 0.6 μm, and s = 0.4 μm are used. In this case, 0.07H_WLAre formed on adjacent non-selected memory cells. The condition that no erroneous writing occurs is H from the equation (8)._BL ^2/3+ (0.07H_WL)^2/3<H_K2 ^2/3It becomes.
[0140]
Next, the read margin of the magnetic memory device of this embodiment is shown. FIG. 11B shows the H_BLAnd H_WLThe horizontal axis represents the anisotropic magnetic field H of the ferromagnetic film 11._K1Magnetic field H normalized by_WL, The vertical axis is the magnetic field H_K1Magnetic field H normalized by_BLIs shown.
[0141]
In the figure, because of structural variations or current source current and resistance variations, H_WLAnd H_BLThe hatched area indicates a condition that can be stably read from the memory cell even if there is a variation of ± 15.8%.
[0142]
The readable area of the cell is an area surrounded by three restricted areas. One is an upper limit determined by the magnetic field at which the magnetization of the ferromagnetic film 11 is reversed._BL ^2/3+ H_WL ^2/3<H_K1 ^2/3It becomes. If it exceeds this, the magnetization of the ferromagnetic film 11 is reversed, and erroneous writing occurs during reading.
[0143]
The second is the lower limit of the magnetic field for reversing the magnetization of the soft magnetic film 13 required at the time of the selected read, and in order to reverse the magnetization of the soft magnetic film 13 of the selected memory cell, H_BL ^2/3+ H_WL ^2/3> H_K2 ^2/3Is required.
[0144]
Third, the magnetic field formed by the selected data selection line 22 is applied to the adjacent memory cell 23.₁₂, 23_{twenty two}H_WLThis is the upper limit because a magnetic field in the direction is generated, so that the magnetization of the soft magnetic body 8 is reversed and erroneous reading occurs.
[0145]
0.07H for the same conditions as writing_WLAre formed on adjacent non-selected memory cells. In order to prevent erroneous reading from occurring in adjacent memory cells in the data transfer line direction, H_BL ^2/3+ (0.07H_WL)^2/3<H_K2 ^2/3These conditions are required.
[0146]
Further, in FIG. 11B, the amount of change from the resistance value in the parallel state, which is the data holding state, is indicated by a dotted line as the read signal amount ΔGMR in the cell readable region. Here, ΔGMR is the amount of change in resistance when the ferromagnetic film 11 and the soft magnetic film 13 are in the antiparallel state with reference to the resistance value when the magnetization is in the parallel state, that is, the maximum signal output obtained. It is normalized by. This is because the angle of magnetization of each of the ferromagnetic film 11 and the soft magnetic film 13 is obtained from the equation (8), and ΔGMR = sin²It can be obtained by (θ / 2).
[0147]
As shown in FIG. 11B, in the configuration of this embodiment, H_BL/ H_K1= 0.2, H_WL/ H_K1By setting the value to 0.2, ΔGMR can be set to 0.7 or more within the condition that data can be stably read from the memory cell even if there is a variation of ± 15.8%, which is larger than the conventional technique. A read output can be obtained.
[0148]
Further, in FIGS. 11A and 11B, H_BL/ H_K1= 0.2 and H_WL/ H_K1= 0.8 for writing to H_WL/ H_K1Reading can be realized by setting = 0.2, and arbitrary data read and write operations are performed using a binary current source for the data transfer line and a binary current source for the data selection line. This can be achieved. Therefore, the circuit configuration of the data transfer line and the data selection line is simplified.
[0149]
(Second Embodiment)
In this embodiment, a circuit configuration in which a memory matrix is formed using the memory cells described in the first embodiment and a read and write operation is performed will be described.
[0150]
FIG. 12 is a diagram showing a circuit configuration including a memory matrix according to the second embodiment of the present invention. The same parts as those in FIG. 9 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0151]
In FIG. 12, four data transfer lines 10 (10_S, 10_US) And four data selection lines 22 (22_S, 22_US) At each intersection of memory cells 23 (23_S, 23_US) Are formed one by one. The four data transfer lines 10 and the data selection line 22 are also provided._DDummy memory cell 23 at each intersection of_DIs formed.
[0152]
Here, the data selection line 22_SIndicates the selected data selection line 22 and the data selection line 22_SMemory cell 23 connected to_SAre selectively written and read. On the other hand, the data selection line 22_USIndicates a data selection line 22 that is not selected. Data selection line 22_USMemory cell 23 connected to_USTherefore, it is necessary to adjust the circuit configuration and timing so as to prevent erroneous writing, erroneous reading, and data destruction.
[0153]
One end of the data selection line 22 is connected to the transistor 33 (33_S, 33_US) Is connected to one end of the source / drain electrode. The gate electrode of the transistor 33 is connected to the voltage nodes W (W1 to W4). The voltage node W is connected to a so-called address decoder, and the selected data selection line 22 is selected._SCurrent is supplied exclusively to. As this address decoder, a circuit known in DRAM or SRAM may be used. Further, the other end of the data selection line 22 is connected to a voltage supply node at 0V, for example.
[0154]
Further, the other end of the source / drain electrode of the transistor 33 is connected to the current supply node 22._NIt is connected to the. Furthermore, the current supply node 22_NIs connected to one end of the source / drain electrode of the transistor 31, and the other end of the source / drain of the transistor 31 is, for example, a voltage node V for supplying a positive potential._HIt is connected to the. Voltage node V_HIs for supplying a data selection line current sufficient for memory cell writing, and the supplied voltage is, for example, the power supply voltage V_DDOr about 1 to 3 times that.
[0155]
The current supply node 22_NIs connected to one end of the source / drain electrode of the transistor 32, and the other end of the source / drain of the transistor 32 is connected to a voltage node V for supplying a positive voltage._LIt is connected to the. Voltage node V_LIs for supplying a data selection line current sufficient for memory cell reading, and the supplied voltage is, for example, from 0 V to the power supply voltage V_DDUp to the voltage.
[0156]
The transistor 31 and the transistor 32 are p-type MISFETs._NWhen charging the current supply node 22_NIs the voltage node V_HAnd voltage node V_LThis is desirable because there is no problem of voltage drop due to the threshold value.
[0157]
Further, the memory cell 23 connected in series is connected to one end of the data transfer line 10._S, 23_USAnd dummy memory cell 23_DThrough the voltage V_plateVoltage source V_plateIt is connected to the. Further, the other end of the data transfer line 10 is connected to a differential sense amplifier 36 (36)._S, 36_US)It is connected to the. The differential sense amplifier 36 has a data transfer line 35 (35) which is paired with the data transfer line 10 respectively._S, 35_US) Is connected.
[0158]
Then, the differential sense amplifier 36_USAnd data transfer line 10_US, 35_USThe differential sense amplifier 36_SAnd data transfer line 10_S, 35_STo the differential sense amplifier 36._SAnd data transfer line 10_S, 35_SAnd the selected data transfer line 10 can be operated._S, 35_SIt is also possible to operate only.
[0159]
In the circuit configuration shown in FIG. 12, four memory cells 23 are connected to each of the four data transfer lines 10 to form a 4 × 4 memory cell configuration. Each data transfer line 10 has a dummy memory cell 23._DIs connected. Of course, the number of memory cells 23 connected to the data transfer line 10 and the data selection line 10 is not limited to four but may be plural.ⁿThe number (n is a positive integer) is desirable for address decoding.
[0160]
FIG. 13 shows a pair of data transfer lines 10 in FIG._S, 35_SAnd differential sense amplifier 36_SFIG. In FIG. 13, the same parts as those in FIG. 12 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0161]
Further, in FIG. 13, the unselected data transfer line 10_US, 35_USAnd differential sense amplifier 36_USThe data transfer line 10_S, 35_SAnd differential sense amplifier 36_SSimilarly to FIG. 13, they may be formed in parallel.
[0162]
The differential sense amplifier 36 includes a p-type MISFET 40 (40_S, 40_US) And n-type MISFET 41 (41_S, 41_US). n-type MISFET41_USOne end of the source / drain electrode of the data transfer line 10_SThe other end is connected to the voltage node SAN. Also, n-type MISFET 41_USThe gate electrode of the data transfer line 35_SIt is connected to the.
[0163]
Further, the n-type MISFET 41_SOne end of the source / drain electrode is connected to the data transfer line 35._SThe other end is connected to the voltage node SAN. Also, n-type MISFET 41_SThe gate electrode of the data transfer line 10_SIt is connected to the. These n-type MISFET 41_SAnd 41_USThus, it is a so-called cross-coupled amplifier.
[0164]
Furthermore, p-type MISFET 40_USOne end of the source / drain electrode is connected to the data transfer line 10._SThe other end is connected to the voltage node SAP. Also, p-type MISFET 40_USThe gate electrode of the data transfer line 35_SIt is connected to the. These p-type MISFETs 40_S, 40_USThus, the data transfer line 10_S, 35_SThis is a so-called cross-coupled amplifier.
[0165]
MISFET42_USOne end of the source / drain electrode is connected to the data transfer line 10._SThe other end is connected to the external data input / output terminal I / O1. MISFET42_SOne end of the source / drain electrode is connected to the data transfer line 35._SThe other end is connected to the external data input / output terminal I / O2.
[0166]
MISFET42_S, 42_USAre connected to a voltage node YL. These MISFETs 42 and 42_USAre external data input / output terminals I / O1, I / O2 and data transfer line 10._S, 35_SCan be controlled by changing the voltage of the voltage node YL.
[0167]
Further, one end of the source / drain electrode of the MISFET 43 is connected to the data transfer line 10._SAnd the other end is connected to the data transfer line 35._SIt is connected to the. The gate electrode of the MISFET 43 is connected to the voltage node EQ. The data transfer line 10 is changed by changing the voltage of the voltage node EQ._S, 35_SOf the data transfer line 10_SAnd data transfer line 35_SReduce the voltage imbalance.
[0168]
The MISFET 43 and the voltage node EQ are, for example, the data transfer line 10_S, 35_SIs sufficiently low impedance and voltage V_plateCan be omitted if voltage imbalance of the data transfer line is not a problem.
[0169]
In the present embodiment, the memory cell 23_S, 23_USSense amplifier circuit and voltage power supply V_plateAre connected in series without a transistor. Therefore, it is possible to prevent the read signal margin from being reduced due to the voltage drop due to the channel resistance of the transistors connected in series. Further, at the time of reading, the read probe current flows through I / O1 and I / O2, and the sense amplifier transistor 40_S, 40_US, 41_S, 41_USAlmost does not flow. For this reason, in the sense amplifier transistor, the voltage drop due to the flow of the read current does not occur, and the read signal margin can be prevented from being reduced due to the voltage drop in the sense amplifier.
[0170]
Here, the dummy memory cell 23_DThe data selection line 22_DChange from the selected state to the non-selected state, the resistance change amount equal to or less than {(resistance value of the memory cell 23 with data “1”) − (resistance value of the memory cell 23 with data “0”)} This is a memory cell.
[0171]
The amount of change in resistance is half of {(resistance value of the memory cell 23 with data “1”) − (resistance value of the memory cell 23 with data “0”)}, {(selected memory cell 23_SResistance value of "0" state)-(unselected memory cell 23_USIt is desirable that the resistance value in the “0” state)} is added.
[0172]
Such a dummy memory cell 23_DFor example, as shown in FIG. 14, when the length of the data storage area of the memory cell 23 in the direction along the longitudinal direction of the data transfer line 10 is z, the dummy memory cell 23 is formed._DThe length may be set to z / 2. 14A is a plan view showing the configuration of the memory cell and the dummy memory cell, FIG. 14B is a cross-sectional view taken along the line AA ′ of FIG. 14A, and FIG. It is sectional drawing of the BB 'part of a).
[0173]
Here, the memory cell 23 and the dummy memory cell 23_DFor each data select line 22 and 22_DIf the currents to be supplied are equalized, the resistance change amount corresponding to the state change of “1” and “0” at the time of data selection is the dummy memory cell 23._DThen, it becomes half of the memory cell 23 and becomes a desirable value.
[0174]
Also, here, for comparison, the memory cell 23 and the dummy memory cell 23_DAre shown as cascaded to the data transfer line 10.
[0175]
Further, as shown in FIG. 15, the width of the data selection line 22 on the memory cell 23 and the dummy memory cell 23_DData selection line 22 above_DAnd the dummy memory cell 23_DIt is also possible to reduce the length of the storage area to half that of the memory cell 23. With this configuration, the data selection lines 22 and 22_DWhen the current is supplied to the data selection line 22 and the data selection line 22_DAs a result, the current densities at which the formed magnetic fields are equal are substantially the same, and the data selection line 22_DIt is possible to form a desirable shape for reliability.
[0176]
15A is a plan view showing the configuration of the memory cell and the dummy memory cell, FIG. 15B is a cross-sectional view taken along the line AA ′ in FIG. 15A, and FIG. It is sectional drawing of the BB 'part of a figure (a).
[0177]
Further, FIG. 16 shows another configuration example of the dummy memory cell. 16A is a plan view showing the configuration of the memory cell and the dummy memory cell, FIG. 16B is a cross-sectional view taken along the line AA ′ in FIG. 16A, and FIG. It is sectional drawing of the BB 'part of a).
[0178]
If there is a margin in the direction perpendicular to the longitudinal direction of the data transfer line 10, a memory cell having a width (2k) twice the width k of the memory cell 23 is formed, and the dummy memory cell 23_DIt is good.
[0179]
This dummy memory cell 23_DThe memory cell 23 and the dummy memory cell 23 in FIG._DThus, the respective data selection lines 22 and 22_DIf the currents to be supplied are equalized, the resistance change amount corresponding to the state change of “1” and “0” at the time of data selection is the dummy memory cell 23._DIs half of the memory cell 23, which is a desirable value.
[0180]
In the dummy memory cell of the present embodiment, the dummy memory cell 23 is made of the same material and configuration as the memory cell 23._DCan be created. Therefore, by using a differential sense amplifier and a dummy memory cell, magnetization due to a temperature change of the memory cell resistance, a variation in the film thickness direction of the ferromagnetic film 11, the nonmagnetic film 12, and the soft magnetic film 13, or a composition variation. The influence of the curve change can be compensated, and a more stable memory read operation can be realized.
[0181]
Further, the dummy memory cell 23_DFor the data selection line 22_DWhen the read selection current is supplied to the memory cell 23, the dummy memory cell 23 is previously set so that the same magnetization state as that obtained when the normal memory cell 23 is read in the data state "1" is obtained._DIt is assumed that the magnetization of the ferromagnetic film 11 is determined. For this purpose, for example, a write operation of “1” data, which will be described later, is performed by the dummy memory cell 23._DYou can do it.
[0182]
Of course, for the dummy memory cell, the dummy memory cell 23_DData selection line 22 above_DIs a memory cell having a resistance change amount equal to or less than {(resistance of “1” of the memory cell 23) − (resistance of “0” of the memory cell 23)}}. If it is present, it does not have to be formed of the same material and structure as the memory cell 23.
[0183]
Next, a write operation to the memory cell 23 corresponding to FIG. 13 will be described using the timing chart of FIG. In the following description, the on state of a transistor means that a voltage larger than the threshold value of the transistor is applied to the gate electrode to indicate that the source electrode and the drain electrode of the MISFET are in a conductive state. Indicates that a voltage lower than the threshold value of the transistor is applied to the gate electrode, and the source electrode and the drain electrode of the MISFET are cut off.
[0184]
The threshold value is the gate voltage when the current flowing between the source electrode and the drain electrode becomes a value of, for example, 40 nA × (channel width) / (gate length).
[0185]
In this embodiment, since the configuration of a normal CMOS logic circuit is simple, a transistor having a positive threshold value will be described as an example. Of course, it is obvious that even if a transistor having a negative threshold value is used, the threshold value may be included in the variable range of the gate voltage.
[0186]
First, for example, the gate potential Φw of the transistor (p-type MISFET) 31 is set to V_DDThe transistor 31 is turned on by setting the voltage to 0 V from the current supply node 22._NPotential V_WLV_HTo charge. Current supply node 22_NThe plurality of transistors 33_USAnd 33_DSince one end of each source / drain electrode is connected in parallel, the capacity increases and a large charging current is required. Therefore, the current supply node 22_NV in advance_HBy charging the current supply node 22_NAs compared with the case where the transistor 33 is not charged, when the transistor 33 transitions to the on state, a decrease in the current of the data selection line 22 at the time of writing can be prevented by the charging current.
[0187]
On the other hand, on the data transfer line side, a sequence is applied to the external data input / output terminals I / O1 and I / O2 as write data, and a current corresponding to the write data is supplied to the data transfer line 10. The write data “0” state is indicated by a solid line, and the “1” state is indicated by a broken line.
[0188]
First, voltage node EQ is set to V_DDTo 0V from the data transfer line 10_SAnd 35_SPotential V_Ten, V₃₅The transistor 43 for maintaining the same potential is turned off, and the data transfer line 10_STo a pair of data transfer lines 35_SInflow and outflow of current into the memory are prevented, and erroneous outflow of write current is prevented. The voltage transition of the voltage node EQ is caused by the MISFET 42._S, 42_USIs performed prior to the transition of the voltage node YL that is turned on.
[0189]
0V or V when writing_DDThe data transfer line 10 that takes the voltage of_S, 35_STherefore, when a parasitic effect of inflow and outflow of current to the voltage node SAN occurs, the write current changes or the power consumption increases. In order to prevent this parasitic effect, the n-type MISFET 41_S, 31_USThe voltage of the voltage node SAN of the cross-coupled amplifier formed by {is the maximum value of the data potential applied to I / O1 and I / O2− (n-type MISFET 41_S, 41_USData transfer line 10_S, 35_SPotential V_Ten, V₃₅Regardless, the cross-coupled amplifier is turned off.
[0190]
In this timing chart, the voltage of the voltage node SAN is expressed as V_DDIt is said. In addition, since the same parasitic effect occurs for the voltage node SAP, the p-type MISFET 40_S, 40_USThe voltage of the voltage node SAP which is the control terminal of the cross-coupled amplifier formed by {is the minimum value of the data potential applied to I / O1 and I / O2) + (p-type MISFET 41_S, 41_USData transfer line 10_S, 35_SPotential V_Ten, V₃₅Regardless, the cross-coupled amplifier is turned off.
[0191]
In this timing chart, the voltage of the voltage node SAP is 0V. The voltage transition of these voltage nodes SAN and SAP is performed after the voltage transition of the voltage node EQ._S, 42_USIs performed until the voltage transition of the voltage node YL in the on state.
[0192]
Next, a data potential corresponding to write data “0” or “1” is applied to I / O1, and a data potential corresponding to inverted data “1” or “0” of the write data is applied to I / O2. These I / O1 and I / O2 are low impedance power supplies such as 0V and V_DDIs desirable for stabilizing the write current and reducing noise.
[0193]
Then, for example, the voltage node YL is changed from 0V to V_DDBy making MISFET42_S, 42_USTurn on. Where V_plateAnd the I / O1 potential difference, the data transfer line 10_SA current corresponding to the write data is supplied to.
[0194]
As described in the first embodiment, in the present memory cell, the data transfer line 10 is used when data is written._SThe data is rewritten by changing the direction of the write current flowing through. To change the direction of the current, V_plateMust be in the range of the data potential of I / O1, V_DD/ 2 is desirable for equalizing the write currents of “0” and “1” to widen the current and magnetic field margins. The data potentials of I / O1 and I / O2 only need to be determined before the voltage node YL rises.
[0195]
Then, MISFET42_S, 42_USIs turned on, for example, the voltage node W2 to which the selected data selection line is connected is changed from 0V to V_DDSo that transistor 43_STurn on. Thereby, the data selection line 22 connected to the memory cell to which data is written is connected._SWrite current I_WLIs written selectively.
[0196]
As the current of the data transfer line 10 and the data selection line 22 at the time of writing, for example, H in the hatching range shown in FIG._WLAnd H_BLIs used, the magnetization direction of the ferromagnetic film 11 can be changed in accordance with the write current direction. For example, in the combination of magnetic bodies shown in FIG._BLIn the case of data “1”, 0.2H_K1The voltage of I / O1 is controlled so as to form a magnetic field that becomes -0.2H in the case of data “0”_K1The voltage of I / O1 is controlled so as to form a magnetic field. Further, the data selection line 22_SWrite current I_WAs the magnetic field H_WLAs a data selection line 22_S0.8H_K1The non-selected data selection line 22 is generated._USIt is sufficient to apply a substantially zero magnetic field.
[0197]
Transistor 33_SIs turned on, the non-selected data selection line 22_USAnd dummy memory cell 23_DData selection line 22 connected to_DTransistor 33 connected to_USAnd 33_DThe voltage nodes W1, W3 to W8, WD1 and WD2 are preferably set to 0 V, and are preferably in the off state in order to reduce power consumption.
[0198]
Next, transistor 33_SAlternatively, the transistor 31 is turned off and the data selection line 22 is turned on._SInterrupts the write current. Then, MISFET42_S, 42_USIn the off state, the data transfer line 10_SThe current supplied to is cut off. Data selection line 22_SThe data transfer line 10 is cut off first._SBy flowing a current corresponding to the write data, the magnetization direction of the soft magnetic film 13 can be stably aligned with the direction of the ferromagnetic film 11.
[0199]
Next, the potential V of the data transfer line 10_TenIs kept constant and the voltage V of the data transfer lines 10 and 35 is used to perform the next read operation at high speed._Ten, V₃₅V_plateTo. For this purpose, the voltage of the voltage node SAN of the sense amplifier control and the voltage of the voltage node SAP are set to V_plateReturn to. Further, the voltage of the voltage node EQ is changed from 0V to V_DDThe potential V of the data transfer lines 10 and 35_Ten, V₃₅Are made equal and balanced.
[0200]
In this write sequence, an unselected data selection line 22_USMemory cell 23 connected to_USThen, the magnetic field H generated by the data selection line_WLIs equal to or less than the coercive force of the soft magnetic film 13, so that data is not erroneously written to the soft magnetic film 13 and the ferromagnetic film 11, and the selected memory cell 23_SOnly selectively can be written.
[0201]
Next, the read operation of the memory cell 23 in the circuit shown in FIG. 13 will be described with reference to the timing chart of FIG.
[0202]
First, for example, p-type MISFET 41_SGate potential Φ_rV_DDIs set to 0 V, the p-type MISFET 41 is turned on, and the voltage node 22_NV_LTo charge.
[0203]
As shown in FIG. 13, the voltage node 22_NIs a plurality of transistors 33_USAnd 33_DSince one of the source and drain electrodes is connected in parallel, the capacity increases and a large charging current is required. Thus, voltage node 22_NV in advance_LBy charging the voltage node 22_NCompared with the case where the transistor is not charged, the transition of the transistor 33 to the on state can prevent a decrease in the current of the data selection line during the reading by the amount of the charging current.
[0204]
On the other hand, for the data transfer line, by applying the same potential to I / O1 and I / O2, for example, 0V, the data transfer line 10_SAnd data transfer line 35_SA sequence in which a read sense current equal to is supplied is performed.
[0205]
In this timing chart, the “0” state is indicated by a solid line, and the “1” state is indicated by a broken line. First, I / O1 and I / O2 are connected to a low-impedance power source, for example, 0 V, and given the same potential. This potential may be equal to the “0” state potential or the “1” state potential used for writing.
[0206]
Then, for example, input YL is changed from 0V to V_DDMISFET42_SAnd 42_USTurn on. Where V_plateAnd I / O1 potential difference and V_plateAnd the I / O 2 potential difference, the data transfer line 10_SAnd data transfer line 35_SA current equal to is applied. At this time, since no current flows through the data selection line, if the potentials of I / O1 and I / O2 are equal to the potential of the “0” state and the potential of the “1” state used for writing, Similarly to the memory cells connected to the non-selected data selection lines, erroneous writing and erroneous reading due to destruction of magnetization information of the ferromagnetic film 11 and the soft magnetic film 13 do not occur.
[0207]
Then, for example, voltage nodes W2 and WD2 are changed from 0V to V_DDSo that the transistor 33_SAnd 33_DTurn on. Here, the voltage node W2 is a memory cell 23 from which reading is performed._SData selection line 22 connected to_SIs a transistor input for selecting. The voltage node WD2 is connected to the data transfer line 35._SDummy memory cell 23 connected to_DIs a transistor input for selecting the memory cell 23 to be read out._SData transfer line 10 connected to_SAnd the dummy memory cell 23 to be selected_DData transfer line 35 connected to_SAre paired and input to the differential sense amplifier 36.
[0208]
Here, as the current of the data transfer line 10 and the data selection line 22 at the time of read sensing, for example, H in the hatching range shown in FIG._WLAnd H_BLIs used, the direction of magnetization of the soft magnetic film 13 is changed to H at the time of reading._BLThe resistance change output can be obtained.
[0209]
For example, in the combination of magnetic bodies in FIG._BLAs 0.2H_K1The voltages of I / O1 and I / O2 are controlled so as to form a magnetic field. Further, the selected memory cell 23_SData selection line 22_SRead current I_rAnd a dummy memory cell 23 connected to a transistor whose gate input is WD2._DAs the read current of H,_WLAs a selection data selection line 22_S0.2H_K1~ 0.3H_K1Control to generate a magnetic field. Further, the non-selected data selection line 22_USIn the memory cell, H_WLControl is performed so that almost zero magnetic field is applied in the direction.
[0210]
Here, the selected memory cell 23_SThe resistance value change with respect to the “1” and “0” states of the memory cell 23 is not selected._USIt is assumed that it is sufficiently larger than the resistance value change in the “0” and “1” states. In addition, the selected memory cell 23_SThe resistance value corresponding to “0” of R_sel, The resistance value corresponding to the “1” state is R_sel+ ΔR_selUnselected memory cell 23_USResistance value of R_unselAnd dummy memory cell 23_DThe resistance value corresponding to “0” of R_dummy, The resistance value corresponding to the “1” state is R_dummy+ ΔR_dummyMISFET42_S, 42_USChannel resistance when on_chAnd
[0211]
Under this condition, the data transfer line 10_SCurrent I_rImmediately after turning on the MISFET 42, the memory cell 23_SIs in the state of “0”,
V_plate/ (R_sel+3^*R_unsel+ R_dummy+ R_ch),
In the state of “1”,
V_plate/ (R_sel+ ΔR_sel+3^*R_unsel+ R_dummy+ R_ch)
It becomes.
[0212]
On the other hand, the data transfer line 35_SImmediately after turning on the transistor 32,
V_plate/ (4^*R_unsel+ ΔR_dummy+ R_dummy+ R_ch)
It becomes. Therefore,
ΔR_dummy= (R_sel-R_unsel) + ΔR_sel/ 2
If so, the data transfer line 35_SCurrent and data transfer line 10_SDepending on the magnitude of the current, the memory cell 23_S"0" and "1" can be discriminated.
[0213]
Therefore, the voltage node EQ is set to V_DDAfter changing from 0 to 0 V, the data transfer line 10_S, 35_SSince the current flowing through the data transfer line differs in the amount of voltage drop at the sense amplifier end, the data transfer line 10 depends on the data state of the memory cell 23._SAnd data transfer line 35_SAnd different results are obtained.
[0214]
Next, for example, the data transfer line 10_SAnd data transfer line 35_SN-type MISFET 41 by setting the voltage node SAN to 0 V when the voltage difference at the sense amplifier end of the transistor becomes 200 mV or more._SAnd 41_USThe cross-coupled amplifier formed in is operated. Here, the memory cell 23_SIs "0", the data transfer line 10_SSense amplifier terminal potential V_TenDecreases to 0V and the memory cell 23 is in the "1" state, the data transfer line 35_SSense amplifier terminal potential V₃₅Decreases to 0V.
[0215]
After this, the voltage node YL is once set to V_DDTo 0 V, I / O 1, 2 and data transfer line 10_S, 35_SAnd disconnect. Next, p-type MISFET 40_SAnd 40_USThe cross-coupled amplifier formed in is operated. Here, the memory cell 23_SIs “1”, the potential V of the sense amplifier end of the data transfer line 10_TenIs V_DDTo rise. As a result, the memory cell 23_SThe current direction of the data transfer line 10 is reversed, and the magnetic field H_BLIs reversed. Memory cell 23_SWhen the data of “1” is “1”, the memory cell 23 is driven by the read current._SThe magnetizations of the ferromagnetic film 11 and the soft magnetic film 13 are switched from the nearly parallel state of the data holding state to the nearly antiparallel state.
[0216]
However, this H_BLBy reversing, the magnetization of the soft magnetic film 13 is returned to the direction of the magnetization of the ferromagnetic film 11, and the memory cell 23_SCan be returned to the data holding state. In this timing chart, the range written as restore corresponds to this.
[0217]
Further, the memory cell 23_SIs “0”, the data transfer line 35_SSense amplifier terminal voltage V₃₅Is V_DDTo rise. Thus, the dummy memory cell 23_DData transfer line 10_SThe direction of the current is reversed and the magnetic field H_BLIs reversed.
[0218]
Memory cell 23_SWhen the data of “0” is “0”, the dummy memory cell 23 is driven by the read current._DThe magnetizations of the ferromagnetic film 11 and the soft magnetic film 13 are switched from the nearly parallel state of the data holding state to the nearly antiparallel state.
[0219]
However, this H_BLBy reversing, the magnetization of the soft magnetic film 13 is returned to the magnetization direction of the ferromagnetic film 11, and the dummy memory cell 23_DCan be returned to the initial state. In this timing chart, the range written as restore corresponds to this.
[0220]
Next, the I / Os 1 and 2 are disconnected from the low impedance power source and charged in advance to an equal voltage, for example, 0 V, to be in a floating state, for example, to be in a high impedance state. After that, input YL is changed from 0V to V again._DDThe data transfer line 10_S, 35_SAnd I / O 1 and 2 are connected. As a result, the read data is output to the I / Os 1 and 2. When data inversion does not occur accidentally due to noise and load capacitance generated in I / O 1 and 2 to set I / O 1 and 2 in a high impedance state, and P-type MISFET 40 has sufficient driving power, voltage node YL is set once. Reduced to 0V and again V_DDCan be omitted. Next, input YL is set to V_DDTo 0 V, I / O 1, 2 and data transfer line 10_S, 35_SAnd disconnect.
[0221]
Next, in order to keep the potential of the data transfer line constant and perform the next read operation at high speed, the data transfer line 10_S, 35_SPotential V_Ten, V₃₅V_plateTo. For this, the voltages of the sense amplifier control inputs SAN and SAP are set to V_plateReturn to. Further, the voltage of the voltage node EQ is changed from 0V to V_DDAs a data transfer line 10_S, 35_SPotential V_Ten, V₃₅Are made equal and balanced.
[0222]
In this read sequence, the data transfer line 10_S, 35_SThe absolute value of the current is equal to the value in the write sequence. Therefore, in this read sequence, the data selection line is generated in the memory cell connected to the unselected data selection line._BLIs less than or equal to the coercive force of the soft magnetic film 13, so that the selected memory cell 23 is not erroneously written to the soft magnetic film 13 and the ferromagnetic film 11._SReading can only be performed.
[0223]
In the circuit configuration of this embodiment, for reading and writing, reading and writing can be performed with only two values corresponding to “0” and “1” as the current of the data transfer line. Therefore, the peripheral circuit of the data transfer line is further simplified. Further, the memory cell includes a sense amplifier circuit and V_plateIs connected in series without a transistor. Accordingly, it is possible to prevent the read signal margin from being reduced due to variations in channel resistance of transistors connected in series.
[0224]
In the dummy memory cell configuration of the present embodiment, the dummy memory cell 23 is made of the same material and structure as the memory cell 23._DCan be created. Therefore, using the differential sense amplifier and the dummy memory cell, the temperature change of the memory cell resistance and the change due to the read current, and the film thickness direction of the ferromagnetic film 11, the nonmagnetic conductive film 12, and the soft magnetic film 13 are changed. The influence of the change in the magnetization curve due to the variation can be compensated, and a more stable memory read operation can be realized.
[0225]
(Third embodiment)
FIG. 19 is a diagram showing a configuration of a magnetic memory device according to the third embodiment of the present invention. 19A is a cross-sectional view corresponding to the A-A ′ portion of the plan view of FIG. 1A, and FIG. 19B is a cross-sectional view corresponding to the B-B ′ portion. In FIG. 19, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0226]
The feature of the present embodiment is that the magnetic memory portion composed of the ferromagnetic film 11, the nonmagnetic conductive film 12 and the soft magnetic film 13 in FIG. 1 is replaced with a granular thin film 52. Reference numeral 51 denotes an insulating film.
[0227]
FIG. 19C shows the structure of the granular thin film 52. For example, a nonmagnetic matrix 52 made of a nonmagnetic material such as Cu or Ag.₁Further, for example, ferromagnetic particles 52 made of a magnetic material such as Co and having a diameter of 0.1 μm or less.₂And ferromagnetic particles 52₂Ni or Fe soft magnetic particles 52 having a smaller coercive force, for example, a diameter of 0.1 μm or less._ThreeAre dispersed at a volume fraction of 10 to 50%, for example. And the ferromagnetic particles 52₂And soft magnetic particles 52_ThreeA resistance change occurs with respect to the change in the arrangement of the magnetization vectors.
[0228]
For example, the ferromagnetic particles 52₂Nonmagnetic matrix 52₁As an example of dispersion in a film in which Co is dispersed in Cu, it is known that there is a decrease in resistance of 5% or more when a magnetic field of 10 kOe is applied (Seiji Mitani, Hiroaki Takanashi, Keian Fujimori, Solid State Physics). Vol.32, No.4, p.238 (1997)).
[0229]
Further, the non-magnetic matrix 52₁As Al₂O_ThreeAnd SiO₂, MgO, HfO₂Nonmagnetic insulator matrix such as Co can be used. For example, Co in which Co is dispersed in aluminum oxide.₅₂Al₂₀O₂₈It is known that the film has a resistance decrease of 8% or more when a magnetic field of 10 kOe is applied (Seiji Mitani, Hironori Takanashi, Keiyasu Fujimori, Solid State Physics Vol. 32, No. 4, p. 235 (1997)). .
[0230]
Here, the resistance value and the resistance change amount of the granular thin film 52 are the same as the ferromagnetic particle 52.₂And soft magnetic particles 52_ThreeIt depends on the arrangement interval. Therefore, the film thickness of the non-magnetic film 12 of the first embodiment needs to be 10 nm or less at the average free path of carriers, typically at room temperature, whereas the film thickness of the granular thin film 52 is, for example, It may be about 10 nm. For this reason, the dispersion | variation in the film forming conditions of resistance value can be suppressed more.
[0231]
Further, the non-magnetic matrix 52₁As Al₂O_ThreeAnd SiO₂, MgO, HfO₂When a non-magnetic insulator such as is used, the resistance in the data transfer line direction of the memory cell can be made larger than when a non-magnetic matrix is used, and a MISFET having a channel resistance larger than that of a metal is used. When used in a read / write circuit, it is convenient for impedance matching.
[0232]
FIG. 20 shows a modification of the present embodiment. 20A is a cross-sectional view corresponding to the AA ′ portion of the plan view of FIG. 1A, FIG. 20B is a cross-sectional view corresponding to the BB ′ portion, and FIG. It is a figure which shows the structure of a granular thin film. In FIG. 20, the same parts as those in FIG. 19 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0233]
This modification is basically the same as that shown above, but has a structure in which a granular thin film 52 is sandwiched between soft magnetic films 55.
[0234]
Further, as shown in FIG. 20C, the granular thin film 52 is made of, for example, a nonmagnetic matrix 52 made of Cu or Ag.₁For example, a ferromagnetic particle 52 having a diameter of 0.1 μm or less made of a magnetic material such as Co, Ni or Fe.₂For example, at a volume fraction of 10 to 50%. And the granular thin film 52 is made into the ferromagnetic particle 52.₂Are sandwiched between soft magnetic films 55 having a smaller coercive force.
[0235]
Due to the change in the magnetization direction of the granular thin film 52 and the magnetization direction of the soft soft magnetic film 55, a scattering or tunneling phenomenon depending on the direction of magnetization occurs at the interface between the granular thin film 52 and the soft magnetic film 55, resulting in a resistance change. .
[0236]
Of course, this modified example also has a non-magnetic matrix 52.₁As Al₂O_ThreeAnd SiO₂, MgO, HfO₂A non-magnetic insulator parent phase such as may be used. In this modification, the resistance value and the amount of change in resistance are determined by the distance between the ferromagnetic particles and the soft magnetic film 55, so it is not necessary to make the granular thin film 52 extremely thin. Therefore, the dispersion of the resistance value can be further suppressed by forming the granular thin film 52 to a thickness of, for example, 10 nm or more. Of course, in this modification, the granular thin film 52 may have a structure in which particles to be a soft magnetic material are separated, and a structure using a ferromagnetic film instead of the soft magnetic film 55 may be used. In addition, a structure in which only one side of the soft magnetic film 55 is formed can be used.
[0237]
(Fourth embodiment)
FIG. 21 is a diagram showing the configuration of the magnetic memory device according to the fourth embodiment of the present invention. 21A is a plan view, FIG. 21B is a cross-sectional view taken along the line AA ′ in FIG. 21A, and FIG. 21C is a cross-sectional view taken along the line BB ′ in FIG. FIG. 21 (d) is a cross-sectional view taken along the line CC ′ of FIG. 21 (a). In addition, the same code | symbol is attached | subjected to the thing same as FIG. 1, and the description is abbreviate | omitted.
[0238]
A data selection line 22 is formed on the insulating substrate 61. A surface insulating film 63 and a side wall insulating film 64 are formed on the surface and side portions of the data selection line 22, respectively. An inter-side wall conductive film 65 is formed on the insulating base 61 between the side wall insulating films 64. The surfaces of the surface insulating film 63, the side wall insulating film 64, and the inter-side wall conductive film 65 are formed on the same plane. An interlayer insulating film 70 is formed on the insulating base 61 and between the conductive films between the side walls.
[0239]
On the surface insulating film 63, the sidewall insulating film 64, and the inter-side wall conductive film 65, the barrier metal 66, the ferromagnetic film 11, the nonmagnetic conductive film 12, and the soft magnetic film 13 are sequentially stacked.
[0240]
In the present embodiment, the conductive film 65 between the sidewalls is formed in a self-aligned manner with the data selection line 22, and the data transfer line 10 is formed on the data selection line 22 in the first embodiment. Is different.
[0241]
The barrier metal 66 is made of, for example, TaN, TiN, WN, TaW or the like having a thickness of 1 to 100 nm, prevents impurity contamination from the lower structure, the inter-side wall conductive film 65, the surface insulating film 63, the ferromagnetic film 11, and the like. Has a role of improving the base flatness when the ferromagnetic film 11 is deposited.
[0242]
The inter-side wall conductive film 65 is formed of W, Al, AlCu or Cu, for example, with a thickness of 50 to 1000 nm, and has a role of reducing the parasitic resistance in the connection region between the memory cells of the data transfer line 10 and is soft magnetic. It is formed in a self-aligned manner with the pattern of the body film 13. The interlayer conductive film 65 is in contact with the barrier metal 66.
[0243]
Further, the surface insulating film 63 and the sidewall insulating film 64 are made of an insulating film made of, for example, a silicon oxide film or a silicon nitride film having a thickness of 5 to 100 nm, and the data selection line 22 and the data transfer line 10 are electrically separated. It is carried out.
[0244]
The data transfer line 10 and the data selection line 22 are formed in a direction orthogonal to each other, and form a magnetic field in a direction orthogonal to each other. The insulating base 61 is made of, for example, an insulating film made of a silicon oxide film, a silicon nitride film, or alumina.
[0245]
Next, the manufacturing process of the magnetic memory device in FIG. 21 will be described with reference to process cross-sectional views in FIGS. 22 to 25, the parts shown in (a) to (d) respectively correspond to the parts shown in (a) to (d) in FIG. 21.
[0246]
First, as shown in FIG. 22, for example, a conductive film made of W, Al, and AlCu having a thickness of 50 to 1000 nm and a silicon oxide film having a thickness of 5 to 200 nm are formed on an insulating substrate 61 that has been flattened by CMP. An insulating film made of a film or a silicon nitride film is sequentially deposited on the entire surface. Further, the conductive film and the insulating film are selectively patterned by lithography and anisotropic etching to form the data selection line 22 and the surface insulating film 63.
[0247]
Next, for example, an insulating film made of a silicon oxide film or a silicon nitride film having a thickness of 1 to 200 nm is deposited on the entire surface. The thickness of this insulating film is set to ½ or less of the arrangement interval of the data selection lines 22. Then, as shown in FIG. 23, the insulating film is etched in the vertical direction by anisotropic etching, for example, and the insulating film is selectively left on the side wall where the data selection line 22 stands out, thereby forming the side wall insulating film 64. Here, the material of the sidewall insulating film 64 is preferably different from the material of the insulating base 61 in order to selectively form the sidewall insulating film 64 on the sidewall of the data selection line 22.
[0248]
Next, as shown in FIG. 24, a conductive film made of W, Al, AlCu, Cu, for example, having a thickness of 50 to 2000 nm is deposited on the entire surface, and then appears to the extent that it appears on the surface of the surface insulating film 63 by, eg, CMP. The conductive film is polished and planarized to form an inter-side wall conductive film 65 in a region surrounded by the side wall insulating film 64. This CMP process may be replaced by a so-called etch back process in which a smoothing resist is applied over the entire surface and then etched.
[0249]
Next, as shown in FIG. 25, for example, a barrier metal 66 made of TaN, TiN, WN, or TaW having a thickness of 1 to 100 nm, Fe, Ni, Co, Cr, Mn, or an alloy thereof having a thickness of 500 to 0.5 nm. A ferromagnetic film 11 made of NiFe, CoFe, NiFeCo, CoPt, and a laminated film thereof, and a nonmagnetic nonmagnetic conductive film 12 made of Cu, AgCu, or TaN having a thickness of 10 to 0.5 nm, a thickness A soft magnetic film 13 made of a laminated film of NiFe, CoFe, NiFeCo, CoTaZr, CoNbZr, FeTaN or CoZrNb / NiFe / CoFe having a thickness of 500 to 0.5 nm is sequentially deposited on the entire surface.
[0250]
Further, after the resist 71 is applied to the entire surface, the resist 71 is patterned by using a lithography technique, and the soft magnetic film 13, the nonmagnetic conductive film 12, the ferromagnetic film 11, the barrier metal 66, and the side wall are formed by etching or ion milling. The intermediate conductive film 65 is etched. In this way, the inter-side wall conductive film 65 electrically connected to each data transfer line 10 composed of the soft magnetic film 13, the nonmagnetic conductive film 12, the ferromagnetic film 11, and the barrier metal 66 is self-aligned. Can be formed. Thereafter, for example, the resist 71 is ashed and removed.
[0251]
Further, an insulating film made of a silicon oxide film or a silicon nitride film having a thickness of 50 to 1000 nm is deposited on the entire surface. For example, the insulating film is etched back in a trench surrounded by the sidewall insulating film 64 and the inter-sidewall conductive film 65. The interlayer insulating film 70 is formed by leaving only the film, and the shape shown in FIG. 21 is formed.
[0252]
In the present embodiment, the insulating base 61 on which the data selection line 22 is formed can be flattened in advance. Therefore, it is easy to make the thickness, particle size, and orientation of the data transfer line 22 uniform compared to the first embodiment. For this reason, it is possible to form the data selection line 22 that is less susceptible to disconnection due to electromigration, and to increase the current density that can be passed through the data selection line 22.
[0253]
Further, the film formation temperature of the data selection line 22 can be raised above the temperature at which the ferromagnetic film 11, the nonmagnetic conductive film 12, and the soft magnetic film 13 deteriorate. For example, when NiFe is used as the ferromagnetic film 11 and Cu is used as the nonmagnetic conductive film 12, if the temperature is 250 ° C. or more, there is a problem that the rate of change in resistance deteriorates due to the interface diffusion between NiFe and Cu. .
[0254]
For this reason, the process after the formation of the magnetic memory unit 16 composed of the ferromagnetic film 11, the nonmagnetic conductive film 12, and the soft magnetic film 13 needs to be configured at a low temperature of 250 ° C. or lower. In the configuration in which the data selection line 22 is formed after the formation of the film, as the insulating film between the data transfer line 10 and the data selection line 22, for example, a plasma SiN film that requires a film formation temperature of 250 ° C. or higher, TEOS decomposition is used. Plasma SiO₂Film, SiO formed by atmospheric pressure CVD₂It has been difficult to form a film having good electrical insulation characteristics, such as an insulating film.
[0255]
Furthermore, since the data selection line 22 cannot be deposited at a high temperature, it is difficult to form an Al or W film by using a CVD method that requires a substrate temperature of 400 ° C. or higher. Therefore, when the data transfer line 10 is formed at a substrate temperature of about 100 ° C. from room temperature, there is a problem that a grain boundary growth is difficult to occur, and a film with many grain boundaries, low reliability, and high electrical resistance is formed.
[0256]
However, if the structure and the manufacturing method of this embodiment are used, the data transfer line 10 can be formed after the data selection line 22 is formed at a temperature of 400 ° C. or higher, for example. The problem of heat resistance can be solved, and a film with better etching processability and electrical insulation characteristics can be used as the surface insulating film 63. Further, since the etching damage at the time of processing the data selection line 22 does not enter the magnetic storage unit 16, a more reliable magnetic memory cell can be formed.
[0257]
Furthermore, in the present embodiment, the processes that require lithography are two processes, that is, the process of forming the data selection line 22 and the process of forming the data transfer line 10, and the lithography process can be reduced as compared with the first embodiment. it can. Further, since the inter-side wall conductive film 65 that lowers the resistance of the data transfer line 10 is formed in a self-aligned manner, the formation of the data transfer line 10 in the memory cell region due to misalignment between the data transfer line 22 and the inter-side wall conductive film 65 is formed. The magnetic field non-uniformity can be prevented. Here, the resistance change can be made more uniform, and the variation in the characteristics of the memory cells can be made smaller.
[0258]
Further, FIG. 26 shows a structure of a modification of the present embodiment. 26A is a plan view, FIG. 26B is a cross-sectional view taken along the line AA ′ in FIG. 26A, FIG. 26C is a cross-sectional view taken along the line BB ′ in FIG. d) It is sectional drawing of CC 'part of (a). The same parts as those in FIG. 1 and FIG.
[0259]
The feature of this modification is that the above-described surface insulating film and side wall insulating film are integrated, and an interlayer insulating film 81 is formed so as to cover the insulating base 61 and the data selection line 22.
[0260]
For example, this structure may be formed as follows. A conductive film made of W, Al, AlCu, for example, having a thickness of 50 to 1000 nm is deposited on the entire surface of the insulating substrate 61 that has been flattened by CMP in advance, and then patterned to form the data selection line 22. Further, for example, a silicon oxide film or silicon nitride film having a thickness of ½ or less of the arrangement interval of the data selection lines 22, for example, a thickness of 5 to 200 nm is deposited on the entire surface by using an isotropic film forming method. An interlayer insulating film 81 is formed to obtain the shape shown in FIG. The subsequent steps are the same as those described with reference to FIGS.
[0261]
In this modification, the thicknesses of the surface insulating film 63 and the sidewall insulating film 64 cannot be arbitrarily selected, but fine anisotropic etching is not required when forming the surface insulating film 63. Therefore, it is difficult to perform anisotropic etching, for example, alumina or MgO can be used, and the process becomes simple. Further, when the data transfer line 10 is etched, the problem that the etching gas enters from the boundary between the surface insulating film 63 and the sidewall insulating film 64 and the data selection line 22 is etched through the sidewall insulating film 64 can be prevented. .
[0262]
In addition, this invention is not limited to each Example mentioned above. In the above embodiment, as a method for forming an insulating film such as an interlayer insulating film, a surface insulating film, and a sidewall insulating film, an oxide film forming method by thermal oxidation or an oxide film in which oxygen is implanted at a low acceleration energy of about 30 keV is formed. Alternatively, it may be formed by a method of depositing an insulating film, a method of depositing a silicon nitride film, or a combination thereof.
[0263]
In addition, the element isolation film or insulating film forming method itself is a method other than those for converting a magnetic film or a metal film into an insulating film, for example, a method of injecting oxide ions into a deposited magnetic film, or oxidizing a deposited magnetic film. The method may be used.
[0264]
Of course, as the insulating film, resist, spin-on-glass, silicon nitride film, other titanium oxide film, tantalum oxide film, resist, or Al₂O_ThreeAlternatively, a single layer film of an organic paraelectric film or a composite film thereof can be used.
[0265]
Further, the ferromagnetic film 11 and the ferromagnetic particles 52₂And the soft magnetic film 13 and the soft magnetic particles 52._ThreeThese materials may be diluted magnetic semiconductors such as HgMnTe, CdMnSe, InMnAs, GaMnAs, perovskite-type ferromagnets LaCaMnO, LaSrMnO, spinel ferrite FeO, MnFeO, CoFeO, NiFeO, PtMnSb, NiMnSb. In this case, the nonmagnetic conductive film 12 and the nonmagnetic matrix 52₁For example, n-type or p-type doped HgCdTe, InGaAs, SrTiO, or MgO can be used. Further, the vertical relationship between the ferromagnetic film 11 and the soft magnetic film 13 may be interchanged.
[0266]
In the second embodiment, the n-type MISFET or the p-type MISFET is used as the switch element. However, these may be switched between the p-type and the n-type if the gate input is inverted. Further, instead of the n-type MISFET, for example, an npn bipolar transistor or a pnp bipolar transistor may be used. When a bipolar transistor is used, a collector electrode is used instead of the drain electrode, an emitter electrode is used instead of the source electrode, a base electrode is used instead of the gate electrode, and the npn is turned on, for example, between the base and emitter electrodes. The forward voltage of the pn junction is positively applied by the transistor, for example, 0.6 V or more for Si, and the negative voltage is applied by the pnp transistor more than the forward voltage, and the base electrode may be set to 0 V to enter the off state.
[0267]
In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.
[0268]
【The invention's effect】
As described above, according to the present invention, the circuit of the data selection line is simplified by making the direction of the current flowing through the data selection line constant during the data write operation and the read operation, and the memory cell is highly integrated. Can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a magnetic memory device according to a first embodiment.
FIG. 2 is a data transfer line resistance R_BLMagnetic field H_BLThe characteristic view which shows the dependence with respect to.
3 is a diagram showing magnetization states of a ferromagnetic film and a soft magnetic film corresponding to states A to D in FIG. 2;
4 is a diagram showing magnetization states of a ferromagnetic film and a soft magnetic film corresponding to states A to D in FIG. 2;
FIG. 5 shows a magnetic field H in the direction of difficult magnetization_WLOf the ferromagnetic thin film and the magnetic field H_BLThe characteristic view which shows dependence.
FIG. 6: Magnetic field H_WLIs the parameter R of the data transfer line_BLMagnetic field H_BLThe characteristic view which shows the dependence with respect to.
7 is a characteristic diagram showing magnetization states of a ferromagnetic film and a soft magnetic film corresponding to the states A ′ and B ′ and the states A and B in FIG. 6;
FIG. 8: Magnetic field H_WLR of the data transfer line when is a zero or positive magnetic field_BLMagnetic field H_BLThe characteristic view which shows the dependence with respect to.
FIG. 9 is a diagram showing a configuration of a memory matrix according to the first embodiment.
FIG. 10 shows a magnetic field H during a read operation and a write operation according to the prior art._BLAnd magnetic field H_WLFIG.
FIG. 11 shows a magnetic field H during a read operation and a write operation according to the present embodiment._BLAnd magnetic field H_WLFIG.
FIG. 12 is a diagram showing a circuit configuration including a memory matrix according to a second embodiment.
13 is a diagram showing a part of the circuit configuration of FIG. 12 in detail.
FIG. 14 is a diagram showing a configuration of a dummy cell.
FIG. 15 is a diagram showing a configuration of a dummy cell.
FIG. 16 shows a structure of a dummy cell.
FIG. 17 is a timing chart for explaining a write operation.
FIG. 18 is a timing chart for explaining a reading operation.
FIG. 19 is a diagram showing a configuration of a magnetic memory device according to a third embodiment.
FIG. 20 is a diagram showing a configuration of a magnetic memory device according to a third embodiment.
FIG. 21 is a diagram showing a configuration of a magnetic memory device according to a fourth embodiment.
22 is a view showing a manufacturing process of the magnetic memory device in FIG. 21; FIG.
FIG. 23 is a view showing a manufacturing process of the magnetic memory device in FIG. 21;
24 is a view showing a manufacturing process of the magnetic memory device in FIG. 21; FIG.
25 is a view showing a manufacturing process of the magnetic memory device in FIG. 21; FIG.
FIG. 26 is a view showing a modification of the magnetic memory device of FIG.
27 is a view showing a manufacturing process of the magnetic memory device in FIG. 26; FIG.
FIG. 28 is a diagram showing a configuration of a conventional magnetic storage device.
FIG. 29 shows a resistance R of a data transfer line._BLCurrent I of the data selection line_WLThe characteristic view which shows dependence.
FIG. 30 is a diagram showing a magnetization state of a ferromagnetic film.
FIG. 31 is a diagram showing a configuration of a conventional magnetic storage device.
32 is a diagram showing a matrix configuration using the magnetic memory device of FIG. 31;
[Explanation of symbols]
10. Data transfer line
10_s... selected data transfer line
11 ... Ferromagnetic film
12 ... Nonmagnetic conductive film
13 ... Soft magnetic film
14 ... Barrier metal layer
15 ... Metal conductive layer
16 ... Magnetic storage unit
20 ... Switch element
20 ... transistor
21 ... Interlayer insulating film
22 ... Data selection line
22_S... selected data selection line
22_US... unselected data selection line
22_D... Data selection line for dummy memory cells
22_N... Current supply node
23 ... Memory cell
23_S... selected memory cell
23_US... unselected memory cells
23_D... Dummy memory cell
24_N…node
31 ... Transistor
32 ... Transistor
33 ... Transistor
35 ... Data transfer line
36 ... Differential sense amplifier
40 ... p-type MISFET
41 ... n-type MISFET
42 ... MISFET
43 ... transistor
51. Insulating film
52 ... Granular thin film
52₁... Non-magnetic matrix
52₂... ferromagnetic particles
52_Three... Soft magnetic particles
55. Soft magnetic film
61. Insulating substrate
63 ... Surface insulating film
64 .. Side wall insulating film
65. Conductive film between side walls
66. Conductive film
70 ... interlayer insulating film
71 ... resist
81. Interlayer insulating film

Claims (6)

A first magnetic body, a second magnetic body having a coercive force smaller than that of the first magnetic body, and a nonmagnetic body formed between the first magnetic body and the second magnetic body. Including data transfer lines;
A data selection line arranged crossing the data transfer line,
The easy magnetization direction of the first magnetic body and the easy magnetization direction of the second magnetic body are each parallel to the data selection line, and the magnetic field generated by the current flowing through the data selection line and the data transfer line By directing the magnetization directions of both the first and second magnetic bodies in either a first direction parallel to the easy axis or a second direction opposite to the first direction, binary data magnetic storage apparatus characterized by storing. Multiple data selection lines,
A power supply node for supplying two types of voltages having the same polarity and different sizes to these data selection lines;
A first magnetic magnetization easy axis is parallel to the data select lines, the magnetization easy axis which is parallel with the data selection line, with a small holding force than the holding force of the first magnetic body A plurality of memory cells each including a second magnetic body and a nonmagnetic body formed between the first magnetic body and the second magnetic body, and intersecting the plurality of data selection lines And arranged data transfer lines,
When writing data to the memory cell, one of the two kinds of voltages is supplied to the selected data selection line, and the first and second voltages are generated by a magnetic field generated from a current flowing through the data selection line and the data transfer line. Binary data is stored by directing both magnetization directions of the two magnetic bodies in a first direction parallel to the easy magnetization axis or a second direction opposite to the first direction; When reading data from the memory cell, the other of the two types of voltages is supplied to a selected data selection line. Multiple data selection lines,
A power supply node for supplying two types of current having the same polarity and different sizes to the data selection line;
A first magnetic magnetization easy axis is parallel to the data select lines, the magnetization easy axis which is parallel with the data selection line, with a small holding force than the holding force of the first magnetic body A plurality of memory cells each including a second magnetic body and a nonmagnetic body formed between the first magnetic body and the second magnetic body, and intersecting the plurality of data selection lines And arranged data transfer lines,
When writing data to the memory cell, one of the two kinds of currents is supplied to the selected data selection line, and the first and second currents are generated by a magnetic field generated from the current flowing through the data selection line and the data transfer line. Binary data is stored by directing both magnetization directions of the two magnetic bodies in either a first direction parallel to the easy axis or a second direction opposite to the first direction; When reading data from the memory cell, the other of the two kinds of currents is supplied to a selected data selection line. The memory cell is
A first film made of the first magnetic material;
A second film made of the second magnetic material;
A third film made of the non-magnetic material,
The magnetic memory device according to claim 1, wherein the third film is formed between the first film and the second film. A plurality of memory cells each including a first magnetization state storage element and a second magnetization state storage element having a lower coercive force than the first magnetization state storage element, and applying a magnetic field in a first direction to the memory cell; A data transfer line to be applied;
A second magnetic field is applied to a selected memory cell among the memory cells from a direction orthogonal to the first direction, and a synergistic action between the magnetic field in the first direction and the second magnetic field causes the A data selection line for changing the magnetization direction of at least one of the first and second magnetization state storage elements of the selected memory cell;
At the time of writing information, the first and second magnetization directions of the selected memory cell are oriented in a first direction parallel to the magnetization facilitating axis according to binary information to be written. Controlling the strength of the second magnetic field, changing the magnetization direction of one of the first and second magnetization state storage elements of the selected memory cell at the time of reading information , and reversing the first direction Magnetic field strength control means for controlling the strength of the first and second magnetic fields so as to be in the second direction ;
A determination means for electrically measuring whether the magnetization directions of the first and second magnetization state storage elements are parallel or anti-parallel in the selected memory cell and outputting a read signal; A magnetic storage device. The data transfer line generates a first magnetic field component having a different magnetic field direction at the time of writing corresponding to each of binary data stored in a memory cell,
6. The magnetic storage device according to claim 5 , wherein the data selection line generates a second magnetic field component having the same magnetic field direction in both cases of reading and writing.

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