JPH04344383A - Magnetic thin film memory and its read-out method - Google Patents

Abstract

PURPOSE:To provide a structure capable of integrating a magnetic thin film memory recording information depending upon a direction of magnetization of a thin film magnetic body in a large scale and a read-out method thereon. CONSTITUTION:Sensor lines 12a, 12b are provide in a matrix form and a magnetic thin film memory element 11A and a diode 20 are connected in series at a point corresponding to the crossing point. Hence a sense current flows through the magnetic thin film memory element 11a only in one direction, so there is no sneak path from the magnetic thin film memory element positioning at other crossing positions when each one line of the sense lines 12a, 12b is selected and the specific magnetic thin film memory element 11A is selected, and the signal only for one element can be taken out from an amplifier 21. Hitherto one amplifier was necessary to a few of elements and the integration degrees is not increased but a highest integration as a solid memory is realized, since it can attain the same level as a semiconductor memory in a plane and also attain multilayers.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic thin film memory and a reading method thereof.

0002

2. Description of the Related Art FIGS. 18 and 19 show, for example, IE
EE TRANSACTICNS ON MAG
NETICS VOL 26. NO5 2828
(1990) “REPROGRAM MABLE LO
GICARRAYUSING M-R ELEME
1 is a perspective view of a conventional magnetic thin film memory element shown in "NTS" and a circuit diagram of a magnetic thin film memory using the same. Figure 1
8 and FIG. 19, 1a and 1b are magnetic thin films, such as permalloy, having a magnetoresistive effect, and 2 is a metal thin film, such as copper, sandwiched between the magnetic thin films 1a and 1b. 3 is a word line for applying an external magnetic field to the magnetic thin films 1a and 1b. Further, 11 is a magnetic thin film memory element, 12 is a magnetic thin film 1a,
1b and a sense line composed of a metal thin film 2, 13 is a dummy line corresponding to the sense line 12, and 14 is a sense line 12.
15 is an automatic zero point detector that automatically detects a zero signal, 16 is a differential amplifier, 17 is a switching element that determines the sense line 12 to be accessed, and 25 is a switch on the dummy line 13. It is comparative resistance.

Next, the operation will be explained. First, we will discuss the magnetoresistive effect. As shown in FIG. 20, an external magnetic field Hex 60 is applied in the hard magnetization axis direction 51 such that the magnetization direction 52 of the magnetic thin film 1 has an angle of θ with the easy magnetization axis direction 50. At this time, when a voltage E64 is applied to both ends of the magnetic thin film 1 and a flowing sensor current i63 is measured by an ammeter 62, the relationship between the magnetization direction and the current i is as shown in FIG. That is, the direction of the current flowing (here, the direction of the difficult magnetization axis 51
) When the direction of magnetization 52 is parallel, the resistance of the magnetic thin film 1 is maximum, and when it is perpendicular, it is minimum (the most current flows).

Next, the operation of the magnetic thin film memory element shown in FIG. 18 will be explained. First, let's talk about records. When a word current is passed through the word line 3 in the direction of the arrow in the figure, the direction of the magnetic field generated by the current becomes the direction 51 of the difficult magnetization axis of the magnetic thin film 1, and by passing a sufficient current, the direction of magnetization 52 (Fig. 20 ) is the direction of the hard magnetization axis 51. Next, a current is passed through the sense line 12 to determine the direction of magnetization. The magnetic fields generated by this current are in opposite directions in the magnetic thin films 1a and 1b, but both are in the easy magnetization axis direction 50. At this time, if the current in the word line 3 is cut off, the direction of magnetization is uniquely determined. FIG. 22 shows the relationship. The direction of magnetization 52 of the magnetic thin films 1a and 1b depends on the direction of the current 63 flowing through the sense line 12.
a and 52b are determined.

Next, reproduction will be described. FIG. 23 shows a diagram in which a current smaller than that during recording is passed through the word line 3, and for simplicity, only the magnetic thin film 1a is shown in a bottom view. Due to the magnetic field Hex60 generated by the current in the word line 3, the magnetization direction 52a is tilted by θ1 with respect to the easy magnetization axis direction 50. This is the same in FIGS. 23(a) and 23(b), only that the sign of the angle θ1 is reversed. Next, a current 63 is caused to flow through the sense line 12. This sense line 12 is shown in FIG.
It shows the magnetic field Hsf66 generated by the external magnetic field Hex60, and also shows the magnetization direction 52a determined by the external magnetic field Hex60. The direction of magnetization 52a is determined by the state of magnetization recorded thereby.
The angle θ2 formed by the easy magnetization axis direction 50a is different, and the state of magnetization finally recorded as shown in FIG. 21 can be detected as an increase and a decrease in electrical resistance.

Next, the operation as a memory will be explained with reference to FIG. Regarding recording, only the memory element 11 whose word line 3 and sense line 12 are switched on at the same time is recorded. As explained above, the recording state is determined by the direction of the current flowing through the sense line 12.
The direction of the current is determined by the switching element. For reproduction, first, the switching element 17 of the sense line 12 that accesses the word line 3 is turned on without passing a current, and the automatic zero point detector 15 detects the potential at the connection point X in the figure and the potential at the connection point of the dummy line 13. Compare and memorize. after that,
A current is passed through the word line 3, and the recorded state of the accessed element is determined based on whether the potential difference becomes larger or smaller than the stored potential difference.

[0007]

[Problems to be Solved by the Invention] As described above, since the conventional magnetic thin film memory connects the memory element 11 in series to the sense line 12, the resistance of each memory element 11 enters in series and the impedance of the sense line 12 connects. Memory element 11
increases in proportion to the number of Therefore, in order to ensure the signal-to-noise ratio of the signal, only a limited number of memory elements (four in the conventional example) can be arranged on one sense line. Moreover, since the signal is basically detected with the resistance value of the sense line 12 in a static state, the comparison resistor 25 is necessary. Therefore, it is necessary to compensate for the temperature characteristics of the resistance of the memory element 11, and the comparative resistor 25 must also be made of a magnetic thin film, resulting in problems such as a complicated structure and limited flexibility in design.

The present invention was made in order to solve the above-mentioned problems, and it provides a magnetic thin film memory and a magnetic thin film memory that can mount an extremely large number of memory elements at high density and easily ensure design likelihood. The purpose is to provide a method for reading the information.

[0009]

[Means for Solving the Problems] A magnetic thin film memory according to the present invention is a magnetic thin film memory having a plurality of magnetic thin film memory elements that record information depending on the direction of magnetization of a thin film magnetic material, wherein the magnetic thin film memory element One memory unit is composed of at least a magnetic thin film and a semiconductor element having nonlinear current-voltage characteristics.

[0010] Furthermore, the magnetic thin film memory according to the present invention includes:
A magnetic thin film memory having a plurality of magnetic thin film memory elements that record information depending on the direction of magnetization of a thin film magnetic material,
One memory unit is formed by arranging magnetic thin film memory elements in a matrix, each of which is composed of at least a magnetic thin film and a semiconductor element having nonlinear current-voltage characteristics.

[0011] Furthermore, the magnetic thin film memory according to the present invention has the following features:
A magnetic thin film memory having a plurality of magnetic thin film memory elements that record information depending on the direction of magnetization of a thin film magnetic material,
Magnetic thin film memory elements in which one memory unit is composed of at least a magnetic thin film and a semiconductor element having nonlinear current-voltage characteristics are arranged in a matrix, and the magnetic thin film memories arranged in the matrix are stacked in multiple stages. It is something.

[0012] Furthermore, the magnetic invention memory according to the present invention includes:
This is a magnetic thin film memory in which an active element is formed using a semiconductor material on a substrate, and a magnetic thin film memory element that records information according to the direction of magnetization of a thin film magnetic material is laminated on the substrate via an insulator. The element and the magnetic thin film memory element are connected by a wiring material.

[0013] Furthermore, the reading method for a magnetic thin film memory according to the present invention is such that the reproducing method for a magnetic thin film memory having a plurality of magnetic thin film memory elements that record information according to the direction of magnetization of the thin film magnetic material is performed by applying a bias magnetic field to the magnetic thin film. The change in the output of the magnetic thin film memory element is read out by applying .

[0014]

[Operation] In this invention, one of the magnetic thin film memory elements is
Magnetic thin film and nonlinear current with at least two memory units
Constructed of semiconductor elements with voltage characteristics. This results in
Noise and power consumption do not depend much on the number of memory elements, making it possible to supply large-scale magnetic thin film memories.

Further, in the present invention, the magnetic thin film memory elements are arranged in rows and columns so that the reproduction signal of the memory element read by the semiconductor element does not effectively pass through other memory elements. This makes it possible to form a large-scale magnetic thin film memory on a single substrate and obtain an output signal with a high S/N ratio.

Further, in the present invention, the magnetic thin film memory elements are arranged in rows and columns and stacked in a plurality of stages. Thereby, a large-scale magnetic thin film memory can be formed.

Further, in the present invention, a semiconductor material is used for the substrate, active elements are formed in the first layer, and a memory layer is arranged in the upper layer. This improves the performance of the active element and makes it possible to form a highly reliable magnetic thin film memory.

Further, in the present invention, a dynamic signal based on a change in the bias magnetic field is used in the readout method of the reproduced signal. Thereby, a magnetic thin film memory can be constructed with a simple circuit configuration without compensating for the temperature characteristics of the resistance of the memory element.

[0019]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In each figure, parts corresponding to those of the conventional device are designated by the same reference numerals and explained. FIG. 1 is a perspective view of one recording unit in a magnetic thin film memory. In the figure, a semiconductor element such as a diode 20 (
20a is a p-type semiconductor, and 20b is a PN consisting of an n-type semiconductor.
A PN junction diode 2 is formed, and a PN junction diode 2 is formed.
A magnetic thin film 1b, a metal thin film 2, and a magnetic thin film 1a are formed on the sense line 12b via an insulator 19a so as to be in contact with the magnetic thin film memory element 11A. Further, the other end of the magnetic thin film memory element 11A is connected to the sense line 12a. The sense line 12a is connected to the sense line 12b and the insulator 19a.
electrically isolated by Moreover, the magnetic thin film 1a
A word line 3 crosses over it with an insulator 19b interposed therebetween. FIG. 2 is a circuit diagram of a 4-bit×4-bit magnetic thin film memory using the magnetic thin film memory element 11A of FIG. 1, for example. Here, 17a and 17b are switching elements for selecting the sense line 12, 18 is a switching element for selecting the word line 3, and 21 is an amplifier for reproduction output.

Next, the operation will be explained. The case where recording is performed on the magnetic thin film memory element 11A indicated by diagonal lines in FIG. 2 will be described. The easy magnetization axis direction 50 of the magnetic thin film 1a is the hard magnetization axis direction of the conventional example, as shown in FIG. First, the switching elements 17a3 and 17b3 are turned on, and the recording current I
rs70 (FIG. 4) is applied to the sense line 12. The direction of the magnetic field Hsf66 (FIG. 4) generated by this current is approximately parallel to the hard magnetization axis direction 51, and the magnetization direction 52a is inclined to the hard magnetization axis direction 51. FIG. 4 shows a state in which this recording current Irs70 is sufficiently applied. Next, the switching element 18
3 is turned on, and the switching element 14 determines the direction of the current flowing through the word line 3. Since the magnetic field Hex60 (FIG. 5) generated by the current flowing through the word line 3 is parallel to the easy axis direction 50, the current I flowing through the word line 3
The direction of magnetization 52a can be determined by the directions of rw61 and rw71. This state is shown in FIG. Finally, when the switching elements 17a3, 17b3, and 183 are turned off to remove the magnetic field applied to the magnetic thin film 1a, the magnetization direction is 5.
2a faces in either direction of the easy magnetization axis direction 50. This state is shown in FIG. However, FIGS. 6A and 6B correspond to FIGS. 5A and 5B, respectively.

Next, the diagonally shaded magnetic thin film memory element 1 in FIG.
The case of reproducing 1A will be described. The state of the magnetic thin film memory element 11A before starting the reproduction operation is as shown in FIG. 6(a) or (b). In the reproducing operation, similarly to recording, the switching elements 17a3 and 17b3 are turned on and a bias magnetic field is applied to the magnetic thin film 1a. However, at this time, the sense line 12a
The current Irs70 passed through is made smaller than that during recording. This state is shown in FIG. However, Fig. 7(a) and (b) are respectively Fig. 6
Corresponds to (a) and (b). Next, the switching element 18
3 is turned on and a current 71 is passed through the word line 3 in one direction, a magnetized state as shown in FIG. 8 is obtained. This figure 8(a),
(b) also corresponds to (a) and (b) in FIGS. 6 and 7. This is due to the magnetization direction 52 with respect to the current flowing through the sense line 12a.
This means that the recorded state can be determined as a difference in resistance due to the magnetoresistive effect (see FIG. 22) because the angle formed by a differs depending on the recording state. If the current flowing through the word line 3 is made stepwise, the resistance of the magnetic thin film memory element 11A changes stepwise. This is shown in FIG. However, Figure 9
(a) and (b) correspond to FIGS. 8(a) and (b), and FIG. 9(c) shows the current in the word line 3. At this time, when the recorded magnetization is in FIG. 6(a), the potential at point X in FIG. ), the waveform has a peak at the top, as shown in FIG. 10(b). The AC portion of this signal is amplified by an amplifier 21 to obtain a predetermined reproduction output.

In FIG. 2, each magnetic thin film memory element 11
The reason why the diode 20 is inserted at A will be explained below. A simplified circuit diagram without the diode 20 is shown in FIG. However, Sij corresponds to each magnetic thin film memory element in FIG. In this case, if the magnetic thin film memory elements connected to the sense lines 12a and 12b pass through the three magnetic thin film memory elements in addition to S33, such as through S13, S14, and S34, there are many circuits. Since this circuit is connected in parallel to the accessed magnetic thin film memory element, the larger the memory configuration, the smaller the total impedance, which increases power consumption and noise. On the other hand, if the diode 20 is inserted in series with the magnetic thin film memory element 11A as in this embodiment, there will be no parallel circuit, so basically no matter how large the memory configuration is, the consumption will be reduced. Power and noise remain unchanged.

Example 2. In the above embodiment, a planar structure is shown, but a larger scale memory can be realized by forming this structure into multiple layers. There is also a method of three-dimensionally arranging the wiring of the magnetic thin film memory element. This will be explained with reference to FIG. Magnetic thin film memory element 11A, diode 20, word line 3, sense line 1
2a, and a through hole is formed so as to be in contact with the n-type semiconductor PN junction diode 20b of the diode 20,
Embed the sense line 12b. However, in FIG. 12, the empty space is covered with insulators 19a, 19b, etc. A large-scale memory is formed by stacking several such layers. In this case, it is preferable to form switching elements and amplifiers in the first layer on the semiconductor substrate, and use the second or higher layers as memory layers, since a peripheral circuit with good characteristics can be obtained. However, it is of course possible to form a memory in the empty space of the first layer. In addition, in this embodiment, the sense line 1
2b is placed in a through hole, but other wiring may be used.

Example 3. Further, in the above embodiments, the magnetoresistive effect was used for reading, but the anomalous Hall effect may be used for reading. This will be explained below using figures. Figure 13
In the figure, a current Irs70 is passed through the magnetic thin film memory element 11B. Here, Tb is applied to the magnetic thin film memory element 11B.
A perpendicular magnetization film such as HoCo is used. Figure 13 (
In a), the direction of magnetization is upward, and in FIG. 13(b), the direction of magnetization is downward. At this time, a voltage VH is generated in a direction perpendicular to the current Trs70 and the magnetization direction, but the polarity is reversed depending on the magnetization direction. A magnetic thin film memory element 11B using this anomalous Hall effect is shown in FIG. 14, and a part of the memory circuit is shown in FIG. 14 and 15 roughly correspond to FIGS. 1 and 2, respectively. However, in this embodiment, since a perpendicular magnetization film is used for the magnetic thin film memory element 11B, the magnetic thin film memory element Only the vertical component of 11B is valid. Therefore, the word line 3 is placed close to the side of the magnetic thin film memory element 11B. The operating principle is similar to the embodiment using the magnetoresistive effect. However, 80 is a ground line that connects the potential of the magnetic thin film memory element 11B to ground.

Example 4. In the above embodiment, the magnetic thin film memory elements 11A and 11B have a three-layer structure of the magnetic thin film 1a, the metal thin film 2, and the magnetic thin film 1b, and generate their own current by the current flowing through the sense line 12 during recording and reproduction. Although the so-called self-bias method in which a magnetic field is applied has been described, the magnetic thin film memory element connected to the sense line 12 may be made of a layer of magnetic thin film 1a1, and a bias line may be provided separately. FIG. 16 shows a cross-sectional view of the magnetic thin film memory element 11C at this time.
Shown below. A bias line 81 is provided below the sense lines 12a, 12b and the magnetic thin film 1a via an insulator 19, and the magnetic field Hsf66 in the above embodiment is obtained by the current flowing through the bias line 81.

Example 5. In addition, the word line 3 and bias line 81 in the above embodiment are connected to each other for each magnetic field thin film.
The book corresponds to this, but if you install another one at a position almost symmetrical to the magnetic thin film memory element and generate a magnetic field as a pair,
It becomes easy to apply the necessary amount of magnetic field to the entire magnetic thin film. In this case, each of the pair causes current to flow in opposite directions. FIG. 17 shows a cross-sectional view corresponding to FIG. 1 when word lines are paired. In the figure, 3a and 3b are a pair of word lines, and 11D is a magnetic thin film memory element.

Example 6. Further, in the above embodiment, the diode 20 is connected in series with the magnetic thin film memory element, but since it is sufficient that no current flows from the sense line 12b toward the sense line 12a, any method that realizes this may be used. For example, a similar effect can be obtained by using a transistor instead of a diode as the semiconductor element. Furthermore, in the above embodiments, the magnetoresistance effect of the thin film magnetic material or the anomalous Hall effect is used as a means for reading recorded information, but the anomalous magnetoresistance effect may also be used. Further, in the above-described embodiment, the magnetic thin film memory element was formed directly under the recording line, that is, the word line 3, but it may be formed directly above the recording line. Furthermore, a current line, that is, a word line 3 constituting the magnetic thin film memory
, the sense line 12 may be formed of a superconducting wire.

[0028]

As described above, according to the present invention, one storage unit of a plurality of magnetic thin film memory elements is composed of at least a magnetic thin film and a semiconductor element whose electric resistance depends on the sign and magnitude of the applied voltage. Therefore, noise and power consumption do not depend much on the number of memory elements, and a large-scale memory can be provided.

Further, according to the present invention, the recording units of the magnetic thin film memory element are arranged in a matrix, and the reproduction signal of the magnetic thin film memory element read by the semiconductor element does not effectively pass through other magnetic thin film memory elements. As a result, a large-scale memory can be formed on a single substrate, and an output signal with a high S/N ratio can be obtained.

Further, according to the present invention, it is possible to form a large-scale memory by arranging the recording units of the magnetic thin film memory element three-dimensionally.

Further, according to the present invention, since a semiconductor material is used for the substrate, the active element is formed in the first layer, and the memory layer is arranged in the upper layer, the performance of the active element is improved.
This has the effect that a highly reliable magnetic thin film memory can be formed.

Further, according to the present invention, since a dynamic signal based on a change in the bias magnetic field is used as the readout method of the reproduced signal, a magnetic thin film memory can be manufactured with a simple circuit configuration without having to compensate for the temperature characteristics of the resistance. This has the effect that it is possible to configure the following.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magnetic thin film memory element according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a magnetic thin film memory according to an embodiment of the present invention.

FIG. 3 is a principle diagram illustrating a recording operation for a magnetic thin film memory element.

FIG. 4 is a principle diagram illustrating a recording operation for a magnetic thin film memory element.

FIG. 5 is a principle diagram illustrating a recording operation for a magnetic thin film memory element.

FIG. 6 is a principle diagram illustrating a read operation for a magnetic thin film memory element.

FIG. 7 is a principle diagram illustrating a read operation for a magnetic thin film memory element.

FIG. 8 is a principle diagram illustrating a read operation for a magnetic thin film memory element.

FIG. 9 is a principle diagram illustrating a read operation for a magnetic thin film memory element.

FIG. 10 is a principle diagram illustrating a read operation for a magnetic thin film memory element.

FIG. 11 is a simplified circuit diagram of a magnetic thin film memory without using the present invention.

FIG. 12 is a perspective view of a magnetic thin film memory device according to another embodiment of the present invention.

13 is a principle diagram illustrating the reproduction operation for the magnetic thin film according to the embodiment of FIG. 12; FIG.

FIG. 14 is a perspective view of a magnetic thin film memory element according to another embodiment of the present invention.

FIG. 15 is a circuit diagram of a magnetic thin film memory according to the embodiment of FIG. 14;

FIG. 16 is a cross-sectional view of a magnetic thin film memory element according to another embodiment of the present invention.

FIG. 17 is a cross-sectional view of a magnetic thin film memory element according to another embodiment of the present invention.

FIG. 18 is a perspective view of a conventional magnetic thin film memory element.

FIG. 19 is a circuit diagram of a conventional magnetic thin film memory.

FIG. 20 is an explanatory diagram of the magnetoresistive effect.

FIG. 21 is an explanatory diagram of the magnetoresistive effect.

FIG. 22 is a recording state diagram of a conventional magnetic thin film memory element.

FIG. 23 is a diagram illustrating the principle of reproducing a conventional magnetic thin film memory element.

FIG. 24 is a diagram illustrating the principle of reproducing a conventional magnetic thin film memory element.

[Explanation of symbols]

1, 1a, 1b magnetic thin film 3 word lines 11A to 11D magnetic thin film memory elements 12, 12
a, 12b sense lines 19, 19a, 19b
Insulator 20 Diode

Claims (5)

[Claims] 1. A magnetic thin film memory comprising a plurality of magnetic thin film memory elements that record information depending on the direction of magnetization of a thin film magnetic material, wherein one storage unit of the magnetic thin film memory element has at least a magnetic thin film and a nonlinear current. - A magnetic thin film memory comprising a semiconductor element having voltage characteristics. 2. A magnetic thin film memory comprising a plurality of magnetic thin film memory elements that record information depending on the direction of magnetization of a thin film magnetic material, wherein one memory unit is a semiconductor having at least nonlinear current-voltage characteristics with the magnetic thin film. A magnetic thin film memory characterized in that magnetic thin film memory elements made up of elements are arranged in a matrix. 3. A magnetic thin film memory comprising a plurality of magnetic thin film memory elements that record information depending on the direction of magnetization of a thin film magnetic material, wherein one memory unit is a semiconductor having at least nonlinear current-voltage characteristics with the magnetic thin film. 1. A magnetic thin film memory characterized in that magnetic thin film memory elements made up of elements are arranged in a matrix, and the magnetic thin film memories arranged in the matrix are stacked in multiple stages. 4. A magnetic thin film memory in which an active element is formed using a semiconductor material on a substrate, and a magnetic thin film memory element that records information according to the direction of magnetization of a thin film magnetic material is laminated on the substrate via an insulator. A magnetic thin film memory, wherein the active element and the magnetic thin film memory element are connected by a wiring material. 5. A method for reproducing a magnetic thin film memory having a plurality of magnetic thin film memory elements that record information depending on the direction of magnetization of a thin film magnetic material, which changes the output of the magnetic thin film memory element by applying a bias magnetic field to the magnetic thin film. A reading method for a magnetic thin film memory characterized by reading out.