JPH0689568A - Memory element - Google Patents

Abstract

PURPOSE:To enable non-volatility, large capacity, high reliability and high-speed access at a low cost by constituting the memory element at least with a magnetic thin film having magnetorestriction and a piezoelectric thin film disposed in a position proximate thereto to the extent of being elastically couplable therewith. CONSTITUTION:The memory element is constituted of at least the magnetic thin film 2 having the magnetorestriction and the piezoelectric thin film 1 disposed in a position proximate thereto to the extent of being elastically couplable therewith. Electrodes 3, 4 are mounted thereto and these electrodes 3, 4 are connected to sense lines 5, 6 and a word line 7 is disposed. The magnetic thin film 2 is the magnetic film formed by laminating a magnetic film expressed by Co, Fe, M (M is at least one kind of the elements selected from among V, Nb, Ta, Cr, Mo, W, Ti, Zr, Hf, N and O) or the oxides thereof and a soft magnetic film. The memory elements are disposed in a matrix form and are laminated via sepn. layers in plural steps. Magnetic fields are impressed to the magnetic thin film 2 and the change in the strain induced by the impression of the magnetic field is converted to an electric signal by the piezoelectric thin film 1, by which the signal is read out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory element for recording information according to the magnetization direction of a thin film magnetic material, a memory in which the memory elements are arranged in a matrix, a method for reading the same, and a method for manufacturing the memory.

[0002]

2. Description of the Related Art Conventionally, an external storage device such as a computer uses magnetic recording such as HDD and FDD or optical recording such as ODD. These recording devices have advantages of non-volatility, large capacity, and low cost, but it is necessary to mechanically move a reading mechanism such as a magnetic head to a place where there is information to be read. There are drawbacks such as a limited improvement and the inevitably heavy weight of the device because it has a movable part.

On the other hand, a semiconductor memory that can be accessed at high speed is used for the main memory such as the computer. However, the semiconductor memory has a small capacity and high cost, and the RAM, which is the mainstream thereof, always requires a certain voltage to retain the memory. In recent years, flash memories and the like have been developed in order to solve the disadvantage of semiconductor memories, such as volatility, but there is a problem that the number of times of writing is limited and the reliability is still insufficient.

In response to these problems, a magnetic memory using a magnetic thin film having stable characteristics has been proposed. For example, FIG. 14 shows an example of the magnetic memory cell described in Japanese Patent Laid-Open No. 4-23293. In FIG. 14, 60 is a heating element,
62 is a magnetoresistive element, 64 is a switching transistor, 66
Is a transfer gate, 68 is a magnetic thin film, 70, 72, 74, 7
6, 78 and 80 are lead wires. Information is recorded by setting the magnetization of the magnetic thin film upward or downward.

Next, the operation will be described. First, recording will be described. In the initial state, the magnetization of the magnetic thin film 68 is uniformly upward. When the switching transistor 64 of a certain cell is turned on, the magnetic thin film 68 in this portion is heated to raise its temperature and its coercive force is lowered, and finally the magnetization is reversed due to the influence of the demagnetizing field, and the magnetic thin film 68 is directed downward. On the other hand, in the cells that do not turn on the switching transistor 64, the magnetization does not reverse and remains upward. In this way, the magnetization of any cell can be uniquely determined, and the signal can be recorded.

The signal is erased only in the cell having the downward magnetization by utilizing the characteristic that the magnetic domain erases under a specific heating condition.

Reproduction is carried out by utilizing the fact that the magnitude of the magnetic field with respect to the magnetoresistive element 62 differs depending on whether the magnetization is upward or downward. The reason why the magnitudes of the magnetic fields are different is that the magnetization in the periphery is in the same direction in the upward direction when the magnetization is upward, whereas the magnetic field is weakened in the downward direction because the periphery is upward. Moreover, since the electric resistance of the magnetoresistive element changes depending on the applied magnetic field, the signal can be read by measuring the resistance.

[0008]

However, in the magnetic memory using the above magnetic thin film, two cells are required for each cell of the memory, and one cell of the memory is composed of one transistor and one capacitor. The integration degree is lower than that of the dynamic RAM of the semiconductor memory. In addition, the substrate of the memory cell is S due to the necessity of the transistor.
Since a semiconductor substrate such as i is required, it is not easy to realize a large capacity memory having a three-dimensional structure. Further, since the signal appears as a difference in electrical resistance, a current must be passed during detection for detection, and power consumption is high.

Further, in the above magnetic memory, the magnetic thin film is a perpendicular magnetic film, but in general, the perpendicular magnetic film is apt to undergo alteration such as oxidation, and heating for each recording also accelerates the alteration, thereby improving reliability. Also has a problem.

The present invention has been made to solve the above problems, and is a non-volatile, large-capacity, high-reliability, low-cost and high-speed accessible memory, its reading method, and the memory. The purpose is to provide a manufacturing method.

[0011]

The memory device of the present invention comprises:
A memory element that records information according to the direction of magnetization of a thin film magnetic body, and is composed of at least a magnetic thin film having magnetostriction and a piezoelectric thin film arranged at a position close enough to be elastically coupled to it. It is characterized by.

A memory according to a second aspect of the present invention is a memory having a plurality of memory elements for recording information according to the magnetization direction of the thin film magnetic body, wherein one recording unit of the memory element is at least magnetostrictive. The memory element is composed of a magnetic thin film and a piezoelectric thin film, and the memory elements are arranged in a matrix and electrically coupled to each other.

A memory according to a third aspect of the present invention is a memory having a plurality of memory elements for recording information according to a magnetization direction of a thin film magnetic body, wherein one recording unit of the memory element is at least magnetostrictive. The memory element is composed of a magnetic thin film and a piezoelectric thin film, and the memory elements are arranged in a matrix, and the memories arranged in the matrix are stacked in a plurality of stages with a separation layer interposed therebetween. It is a thing.

A memory according to a fourth aspect of the present invention is a memory having a plurality of memory elements for recording information according to a magnetization direction of a thin film magnetic body, and one recording unit of the memory element is at least easy to magnetize. A magnetic thin film whose axis is in the plane of the film surface and has magnetostriction; a piezoelectric thin film which is arranged directly or close to the upper or lower part of the magnetic thin film and has anisotropy in the in-plane direction of the film surface; A plurality of memory elements each including a read circuit for reading the voltage across the piezoelectric thin film, a voltage generating circuit for generating a comparison voltage, and a comparison for comparing a signal indicating the voltage across the piezoelectric thin film with the comparison voltage. It is characterized by having a container.

According to another aspect of the present invention, there is provided a method for reading a memory, comprising a plurality of memory elements for recording information according to a magnetization direction of a thin film magnetic body, one recording unit of the memory element having at least magnetostriction and the magnetic thin film. A piezoelectric thin film arranged at a position close enough to be elastically coupled to the thin film, and applying a magnetic field to the magnetic thin film having magnetostriction,
A signal is read by converting a change in strain induced by the application of the magnetic field into an electric signal by the piezoelectric thin film.

A method of manufacturing a memory according to the present invention has a magnetic thin film having a plurality of memory elements for recording information according to a magnetization direction of a thin film magnetic body, and one recording unit of the memory element has at least magnetostriction, and an elastic thin film. It is composed of a piezoelectric thin film arranged in a position close enough to be coupled to the piezoelectric thin film, and the piezoelectric thin film is formed by a physical or chemical vapor deposition method, and the film forming direction is inclined. It is characterized by inducing anisotropy in the in-plane direction of the film surface.

Further, the memory according to claim 7 is a memory having a plurality of memory elements for recording information according to the direction of magnetization of the thin film magnetic body, and one recording unit of the memory element has at least magnetostriction. The magnetic thin film is composed of a thin film and a piezoelectric thin film arranged at a position close enough to be elastically coupled to the thin film, and the magnetic thin film having magnetostriction is Co _x Fe _y M (M is V, Nb, Ta, Cr, Mo). , W,
A magnetic film represented by one kind of element selected from Ti, Zr, Hf, N and O and represented by 0 <x <1, 0 <y <1, x + y ≦ 1) or its oxide, and the magnetic film. And a magnetic film having a soft magnetic characteristic are laminated to form a magnetic thin film.

[0018]

The memory element of the present invention can record a signal depending on the direction of magnetization of the magnetic thin film, and the magnetostrictive effect generated by the magnetization of the magnetic thin film elastically couples the strain of the magnetic thin film to the piezoelectric thin film. And a reproducing voltage can be obtained by the piezoelectric effect.

In the memory of the present invention, one recording unit of the memory element is composed of at least a magnetic thin film having magnetostriction and a piezoelectric thin film, and the memory elements are arranged in a matrix. In addition to the effect, the wiring between the memory elements is simple and minimal, and the peripheral circuit is also simple.

In the memory of the present invention, memory elements each of which has at least one magnetic thin film having magnetostriction and a piezoelectric thin film as a recording unit are arranged in a matrix and arranged in the matrix. Due to the structure in which a plurality of memory elements are stacked in a plurality of stages, in addition to the actions and effects described above,
Much more memory devices can be placed on a single substrate than planar structures.

In the memory according to the present invention, one recording unit of the memory element has a magnetic thin film having at least the easy axis of magnetization in the plane of the film surface and having magnetostriction, and directly or close to the upper or lower part of the magnetic thin film. A plurality of memory elements each including a piezoelectric thin film arranged and having anisotropy in the in-plane direction of the film surface, and a read circuit for reading the voltage across the piezoelectric thin film, and a voltage generating circuit for generating a comparison voltage. And a comparator for comparing the reproduced voltage with the comparator,
In addition to the actions and effects described above, a wide range of usage conditions such as usage temperature can be obtained, and a highly reliable memory can be obtained.

The memory read method of the present invention is a method of applying a magnetic field to a magnetic thin film having magnetostriction and converting a change in strain induced as a result into an electric signal by the piezoelectric thin film to read a reproduction signal. Since it is adopted,
With a relatively simple configuration, signals can be read reliably and easily.

In the method of manufacturing the memory of the present invention, the method of forming the piezoelectric thin film is a physical or chemical vapor deposition method, and by making the film forming direction oblique, an anisotropy is obtained in the in-plane direction of the film surface. Can be easily triggered.

Further, a magnetic thin film having magnetostriction is formed by Co _x Fe _y
By using M or its oxide, the magnetostriction constant becomes large, recording and reading can be performed with a small current, and the sensitivity is improved.

[0025]

EXAMPLES The present invention will be described in detail below based on specific examples. [Embodiment 1] First, an embodiment of the memory of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing the configuration of an embodiment of a memory element in the memory of the present invention. In FIG. 1, 1 is a piezoelectric thin film, 2 is a magnetic thin film, 3 and 4 are electrodes,
Reference numerals 5 and 6 are sense lines, and 7 is a word line. FIG. 2 is a perspective view of the memory device according to this embodiment. In FIG.
Reference numeral 8 is an insulating film for electrically separating the sense line 6 and the word line 7. FIG. 3 is an explanatory diagram showing the structure of a 4 × 4 bid memory in which the memory elements are arranged in a matrix. In FIG. 3, 11 is a memory element, and 11r is a signal level comparison memory element. Further, 5a to 5d and 5r are sense lines corresponding to 5 in FIG. 1, and 6a to 6d and 6r are shown in FIG.
The sense lines 7a to 7d and 7r corresponding to 6 in FIG.
Is a word line corresponding to.

First, the recording operation will be described. Figure 4
(A) and (b) show the magnetization direction 13 of the magnetic thin film 2 in the memory element 11. In this embodiment, the magnetic thin film 2
Is, for example, F on a non-conductive substrate such as glass or Si.
e _x Co _y V (0.4 <x <1, 0 <y <0.6, 0 <x + y ≦
1. The composition x and y of the alloy indicate the atomic ratio.
V alloy is 200 nm and Ni _x Fe (0.1 <x <0.6,
The composition x of the alloy is an atomic ratio, hereinafter referred to as a NiFe alloy), and a laminated film having a thickness of 10 nm is formed by 15-layer sputtering. The coercive force is 3 Oe and the magnetostriction constant is 2 × 10 ⁻⁵ . Have This magnetic thin film 2 has anisotropy in the film plane, and when there is no magnetic field applied from the outside, the direction of magnetization 13
Is parallel to the direction 12 of easy magnetization, so that FIG.
Alternatively, the orientation is as shown in FIG. Figure 4
By associating the state of (a) with the bit "1" and the state of FIG. 4 (b) with the bit "0", this element can be a 1-bit recording element.

Next, the recording method will be described. In addition,
(A) and (b) of the following figures are (a) and (b) of FIG. 4, respectively.
Corresponds to (b). The initial state is one of the states shown in FIG. As shown in FIG. 5, when a recording current I _WW 14 is passed through the word line 7 of this memory element, a magnetic field H _exw 15 is generated according to Ampere's law. This magnetic field H _exw
If 15 is a sufficiently large value, the magnetization direction 13 is magnetized in the same direction as the magnetic field H _{exw in the} direction perpendicular to the easy axis of magnetization, regardless of the initial state shown in FIG. Next, as shown in FIGS. 6A and 6B, when the magnetization direction determining current I _ws 16a or 16b is passed through the sense line 6, a magnetic field H _exs 17a or 17b is generated according to Ampere's law. The direction of the current 16 (16a, 16b) is as shown in FIG. 7A when the recording state is set to bit "1" and as shown in FIG. Magnetic field H _exw 15 and magnetic field H _exs
The direction of magnetization is 13a due to the synthetic magnetic field of 17 (17a, 17b).
Or 13b. In this state, when the currents I _ww 14 and I _ws 16 flowing in the memory element 11 are turned off, the state of (a) or (b) shown in FIG. 4 is obtained. This recording process is an overwrite recording without an erasing process.

In order to simplify the explanation, the currents I _ww 14 and I _ws 16 are sequentially passed through the memory element 11 in the recording process, but the same operation is performed even if they are reversed in time or simultaneously. Become. Further, recording can be performed only by the magnetization determining current I _ws 16 without flowing the current I _ww 14 in the word line 7. However, the direction of magnetization is reversed, that is, from the state of (a) to (b) of FIG. 4, or from (b) to (a).
Since the magnetic field required to obtain the state of 1 is much larger than when the current 1 _ww 14 is applied, that is, when a bias magnetic field is applied, the magnetization determining current I _ws 16 has a considerable magnitude. I need.

Next, the reproducing process, that is, the reading method will be described. FIG. 7 shows the direction of magnetization when a read current I _rw 18 is applied to the word line 7 of the memory element in the recording state shown in FIG.
13a and 13b are shown. This is because the magnetic field H _exr 19 according to Ampere's law is generated by passing the current I _rw as in the recording process, and the direction of magnetization is the magnetic field H _exr 19.
_This is because it rotated a little in the direction of _exr 19. So that the magnetization direction is not parallel to the H _exr 19, the magnetic field H _EXW 15 field H _exr 19 generated by the read current I _rw is shown in a recording process
Need to be smaller. Therefore, the read current I _rw 1 is generated so that the magnetic field H _exr 19 having the appropriate magnitude is generated.
The size of 8 is set.

FIGS. 8A and 8B are explanatory views schematically showing the strain of the magnetic thin film 2 and the piezoelectric thin film 1. The distorted directions are 21 and 22 respectively corresponding to FIGS. 7A and 7B, and the film thickness direction of the piezoelectric thin film is 23. Since the piezoelectric thin film 1 and the magnetic thin film 2 are elastically and mechanically coupled to each other, the magnetic thin film 2 is distorted similarly to the piezoelectric thin film. In this embodiment, the piezoelectric thin film is ZnO.
When forming the ZnO film, a vertical direction 23 is formed along the direction 21.
When a ZnO film having a thickness of, for example, 0.1 to 1 μm is formed by performing oblique sputtering at an angle of 20 to 70 degrees, ZnO crystals grow in an oblique direction as shown in FIG. In FIG. 9, the crystal grain is indicated by 24. In this case, in-plane anisotropy occurs, and when the direction 21 is distorted and the direction 22 is distorted, the voltage E generated in the film thickness direction is different under the same strain. Here, the voltages in the case of distortion in the direction 21 and in the case of distortion in the direction 22 are Ea and Eb, respectively. The voltages Ea and Eb are generated at both ends of the piezoelectric thin film 1, but in the present embodiment, the magnetic thin film 2 is a metal, has a large conductivity, and has substantially the same potential as the electrode 4, so that the sense line 5,
It is almost equal to the voltage across 6.

In this embodiment, the piezoelectric thin film is formed by sputtering ZnO in an oblique direction. The piezoelectric thin film has a high electric resistance and a film thickness direction due to in-plane unidirectional strain. It is necessary that the generated voltage in the film thickness be different from the generated voltage in the film thickness direction due to the strain in the other direction in the plane, and any material may be used as long as it satisfies the voltage. Therefore, in the present invention, quartz, LiNbO ₃ ,
A piezoelectric thin film such as LiTaO ₃ is epitaxially grown to form a film having a thickness of, for example, about 0.1 to 1 μm, or a thin film that does not cause anisotropy in the in-plane direction is formed obliquely by a normal method. It can be used as a piezoelectric thin film satisfying the above-mentioned conditions by inducing anisotropy. As a film forming method, either a physical vapor deposition method such as sputtering or a chemical vapor deposition method such as CVD can be used. In addition, in the case of a ZnO sputtered film, a piezoelectric thin film with better characteristics is obtained by heating the substrate at the time of film formation to about 200 to 400 ° C. Other conditions may be used as long as the conditions have the function of the piezoelectric thin film that is different.

Since the memory element is configured as described above, when a read current is applied to the word line 7, all the memory elements connected to the word line 7 are Ea or E.
The voltage of b is generated between the sense lines 5 and 6. For example, when the recording of the memory element indicated by the hatched lines in FIG. 3 is reproduced, a read current is passed through the word line 7c and the sense line 5c,
The voltage between 6c may be measured. In this case, the voltage is Ea
If so, it is a bit "1", and if Eb, it is a bit "0". In this embodiment, the comparison memory element 11r shown in FIG.
Are all recorded in the bit "0" in advance, and the sense lines 5c, 6
The bit of the memory element to be read is recognized by comparing the voltage Em between c and the voltage Er between 5r and 6r. That is, the bit is "1" when the difference between Em and Er exceeds a certain level, and the bit is "0" when the difference is small. Ideally, if the memory element to be read has bit "0", Em and Er are exactly the same, but in reality, Zn is
There are variations in the manufacture of the O film, etc., and the values are slightly different. Therefore, the binary value described above can be recognized by providing an appropriate threshold value.

In the above description, an example in which the memory configuration is 4 × 4 bits has been described, but the bit configuration is completely arbitrary, and it is preferable that the number of bits is also a megabit level.

The operation of the comparison voltage Er generating circuit is as follows.
Although the voltage is generated by the memory element for comparison, the same effect can be obtained by other methods such as using a voltage between resistors.

[Embodiment 2] In Embodiment 1, a planar structure is shown, but in this embodiment, a larger scale memory is realized by making this structure multi-layered. Since the basic structure of the memory element of the present invention is composed of a magnetic thin film, a piezoelectric thin film and electrodes, and does not require a switching element such as a transistor, it is not necessary to use a semiconductor such as Si for the substrate of the memory element part. For this reason,
It is easy to stack a plurality of layers of the memory element part. An embodiment of a memory in which the memory element portion is laminated in a plurality of layers will be described with reference to the drawings.

FIG. 10 is an explanatory diagram showing the concept of a multi-layered memory. In the figure, 25 is a decoder, 26 is a word line selection circuit, 27 is a sense line selection circuit, 28 is a comparator, and 29 to 32 are memory element layers.

In this circuit, the decoder 25 and the word line selection circuit 26 receive an address signal, select a word line designated by the address signal, and write current I
_ww (see FIG. 6) or read current I _rw (see FIG. 7). Similarly, the decoder 25 and the sense line selection circuit 27 similarly select a sense line and connect it to a circuit for passing a current.

In the present embodiment, stable and high-speed operation is made possible by providing peripheral circuits of 25 to 28 memories such as a decoder, a selection circuit, and a comparator on the Si substrate, and a separation layer such as SiO 2 is provided on the peripheral circuit. _Four memory layers are provided via an insulating layer made of ₂ , Si ₃ N ₄ , Al ₂ O _3, or the like.

The insulating layer may be provided with a thickness such that the distance between the upper and lower memory elements is, for example, about 0.1 to 1 μm. Each of these memory element layers has memory elements arranged in rows and columns as shown in FIG. The total number of memory element layers may be any number and is not particularly limited, but normally, for example, it has about 8 to 16 memory layers.
The material of the separation layer is, for example, Si having a low electric conductivity.
Examples thereof include an inorganic insulating material such as O ₂ and an organic insulating material such as a resist.

[Embodiment 3] In Embodiments 1 and 2, there was only one word line in the memory element, but in this embodiment, as shown in FIG. 11, word lines 7a are formed above and below the element.
7b is provided. Other configurations are similar to those of the first or second embodiment.

In this case, the recording current I _ww 14 (see FIG. 5)
, The generated magnetic fields can be superposed, so that the required magnetic field can be obtained with a smaller current than the memory element having only one word line, and the cross-sectional area of the word line can be reduced. Can be made smaller.

[Embodiment 4] In Embodiment 1, a configuration example of a memory element using a non-conductive substrate is shown. In this embodiment, as shown in FIG. 12, for example, a conductive substrate such as carbon or the non-conductive substrate is used. Conductor film 33 such as Al or Cu on a conductive substrate
And a piezoelectric thin film 1 and a magnetic thin film 2 are formed thereon. Other configurations are the same as those in the first embodiment.

In this embodiment, when the magnetic thin film 2 is a conductor such as FeCoV alloy, the electrode 4 may be omitted. Further, the piezoelectric thin film 1 and the magnetic thin film 2 are elastically and mechanically coupled to each other so that a magnetic field is applied to the magnetic thin film 2, and any voltage can be applied across the piezoelectric thin film. Even if there is, the effect of the present invention is exhibited.

[Embodiment 5] In a memory using a metal magnetic material as the magnetic thin film 2, the electrode 2 and the sense line 6 have almost the same potential, but when the magnetic thin film 2 is a non-conductive material such as an oxide, With the same configuration, the voltage across the piezoelectric thin film cannot be obtained. A sectional view of the memory cell of the memory in this case is shown in FIG. Other configurations are as in Examples 1, 2, 3 or 4.
Is the same as. By forming the electrode 4 between the piezoelectric thin film 1 and the magnetic thin film 2, the voltage across the piezoelectric thin film 1 can be obtained. However, if the thickness of the electrode 4 is large, the elastic and mechanical coupling between the piezoelectric thin film 1 and the magnetic thin film 2 will be weakened, and the efficiency during reproduction will be reduced, so that a suitable thickness, for example 0.01 to 0.1 μm, is obtained. There is a need to. In this embodiment, the magnetic thin film 2 may be a conductor.

[Embodiment 6] In the above-mentioned embodiment, a laminated magnetic thin film of FeCoV alloy and NiFe alloy is used as the magnetic thin film. However, the magnetic thin film has anisotropy and maintains the easy axis direction. It is necessary that the magnetic force is small and the magnetostriction is large, and any magnetic thin film may be used as long as it satisfies these requirements. The film forming method may be either a physical vapor deposition method or a chemical vapor deposition method. In particular, according to the study by the present inventors, by adding a third element such as V to the Fe—Co system, the magnetostriction becomes a practical size, and the protection is achieved by stacking with a soft magnetic thin film such as permalloy. Magnetic force is 1/10
It has been found that the above functions can be easily satisfied because the following can be done. As the magnetic thin film, Co _x Fe _y
M (M is V, Nb, Ta, Cr, Mo, W, Ti, Z
A magnetic thin film represented by 0 <x <1, 0 <y <1, x + y ≦ 1) or its oxide, which is one kind of element selected from r, Hf, N, and O, and the magnetic thin film and the soft thin film. The effect of the present invention is further exerted by using a magnetic thin film in which a magnetic thin film having magnetic characteristics is laminated. Other configurations are similar to those of the other embodiments. Here, as the magnetic thin film having the soft magnetic property, in addition to the above-mentioned permalloy, C
An oZrNb amorphous alloy, sendust, etc. can be used.

[0046]

As described above, the memory element of the present invention is non-volatile because it records signals according to the direction of magnetization of the thin film magnetic material, and is highly reliable because it does not require a special function as a constituent material. Since the material can be selected and the element structure is simple, it is possible to supply the material at low cost.

According to a second aspect of the present invention, there is provided a memory having a plurality of memory elements for recording information according to the magnetization direction of the thin film magnetic body, wherein one recording unit of the memory element is at least magnetostrictive. Since the memory element is composed of the magnetic thin film and the piezoelectric thin film, and the memory elements are arranged in a matrix, a large capacity high-speed operation and non-volatile memory can be obtained on a single substrate with a small number of circuits. There is an effect that can be.

According to a third aspect of the present invention, there is provided a memory having a plurality of memory elements for recording information according to the magnetization direction of the thin film magnetic body, wherein one recording unit of the memory element is at least magnetostrictive. Memory elements composed of the magnetic thin film and the piezoelectric thin film are arranged in a matrix,
Since the memories arranged in rows and columns are laminated in a plurality of stages, there is an effect that a single chip operates at high speed and a large-capacity and non-volatile memory can be obtained at low cost. .

According to a fourth aspect of the present invention, there is provided a memory having a plurality of memory elements for recording information according to the magnetization direction of the thin film magnetic body, wherein one recording unit of the memory element is at least easy to magnetize. A magnetic thin film whose axis is in the plane of the film surface and has magnetostriction; a piezoelectric thin film which is arranged directly or close to the upper or lower part of the magnetic thin film and has anisotropy in the in-plane direction of the film surface; A plurality of memory elements each including a read circuit for reading the voltage across the piezoelectric thin film, a voltage generating circuit for generating a comparison voltage, and a comparator for comparing a signal indicating both ends of the piezoelectric thin film with the comparison voltage. With such a configuration, it is possible to obtain a wide range of use conditions such as use temperature and obtain a highly reliable memory.

According to the memory reading method of the present invention, a magnetic thin film having a plurality of memory elements for recording information depending on the magnetization direction of the thin film magnetic body, and one recording unit of the memory element has at least magnetostriction. And a piezoelectric thin film arranged at a position close enough to be elastically coupled to it, a memory read method is applied by applying a magnetic field to the magnetic thin film having magnetostriction and induced by the application of the magnetic field. Since it is a method of reading out a signal by converting the change in strain due to the piezoelectric thin film into an electric signal,
This has an effect that it can be used with less power consumption in the reproducing process.

According to the method of manufacturing a memory of the present invention, the memory has a plurality of memory elements for recording information depending on the magnetization direction of the thin film magnetic body, and one recording unit of the memory element has at least magnetostriction. It is composed of a magnetic thin film and a piezoelectric thin film arranged in a position close enough to be elastically coupled to the magnetic thin film, and the method for forming the piezoelectric thin film is a physical or chemical vapor deposition method, and the film forming direction is oblique. Since it is a manufacturing method that induces anisotropy in the in-plane direction of the film surface, it is possible to use a material for a piezoelectric thin film of a crystal crystal system with relatively good symmetry that allows stable film formation, and is easy. Since the film can be formed by any method, a high manufacturing yield can be obtained, and a memory can be obtained at low cost.

Further, the magnetic thin film of the memory of the present invention has the formula Co
_In the case of a laminated magnetic thin film of a magnetic film represented by _x Fe _y M or an oxide thereof and a magnetic film having soft magnetic characteristics, the large magnetostriction constant not only increases the reproduction output of the memory but also increases the material properties. It is stable and highly reliable and can be used under a wide range of conditions.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a memory device of the present invention.

FIG. 2 is a perspective view showing an embodiment of a memory device of the present invention.

FIG. 3 is an explanatory diagram showing one embodiment of a memory of the present invention.

FIG. 4 is an explanatory diagram showing a recording state in an embodiment of the memory element of the present invention.

FIG. 5 is an explanatory diagram showing a recording process in one embodiment of the memory device of the present invention.

FIG. 6 is an explanatory diagram showing a recording process in one embodiment of the memory device of the present invention.

FIG. 7 is an explanatory diagram showing a reproducing process in one embodiment of the memory device of the present invention.

FIG. 8 is an explanatory diagram showing a reproducing process in one embodiment of the memory device of the present invention.

FIG. 9 is an explanatory diagram schematically showing crystal grains of a piezoelectric thin film in a memory element in one example of the memory of the present invention.

FIG. 10 is an explanatory diagram showing a configuration of an example of a memory according to the present invention.

FIG. 11 is a perspective view of an embodiment of a memory device of the present invention.

FIG. 12 is a perspective view of an embodiment of a memory device of the present invention.

FIG. 13 is a cross-sectional view of a memory element in one embodiment of the memory of the present invention.

FIG. 14 is an explanatory diagram showing the concept of a memory element of a conventional memory.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 piezoelectric thin film 2 magnetic thin film 3, 4 electrode 5, 5a-5d, 5r sense line 6, 6a-6d, 6r sense line 7, 7a-7d word line 11 memory element 11r comparative memory element 12 easy magnetization axis 13, 13a, 13b Magnetization direction 14 Recording current 15 Magnetic field generated by recording current 16 Magnetization direction determining current 17, 17a, 17b Magnetic field generated by magnetization direction determining current 18 Read current 19 Magnetic field generated by read current 25 Decoder 26 Word line selection circuit 27 Sense line selection circuit 28 Comparator 29 to 32 Memory device layer

Claims (7)

[Claims] 1. A memory element for recording information according to the direction of magnetization of a thin film magnetic body, the piezoelectric thin film being disposed at a position close to at least a magnetic thin film having magnetostriction and elastically coupled to the thin film. A memory device comprising: 2. A memory having a plurality of memory elements for recording information according to the direction of magnetization of a thin film magnetic body, wherein one recording unit of the memory element comprises at least a magnetic thin film having magnetostriction and a piezoelectric thin film. A memory, wherein the memory elements are arranged in a matrix and are electrically connected. 3. A memory having a plurality of memory elements for recording information according to the direction of magnetization of a thin film magnetic body, wherein one recording unit of the memory element comprises at least a magnetic thin film having magnetostriction and a piezoelectric thin film. The memory is characterized in that the memory elements are arranged in a matrix, and the plurality of memory elements arranged in the matrix are stacked in a plurality of stages with a separation layer interposed therebetween. 4. A memory having a plurality of memory elements for recording information according to a magnetization direction of a thin film magnetic body, wherein one recording unit of the memory element has at least an easy axis of magnetization in a plane of a film surface. A magnetic thin film having magnetostriction, a piezoelectric thin film arranged directly or close to the upper or lower part of the magnetic thin film and having anisotropy in the in-plane direction of the film surface, and reading for reading the voltage across the piezoelectric thin film. A memory having a plurality of memory elements each composed of a circuit, a voltage generation circuit for generating a comparison voltage, and a comparator for comparing a signal indicating the voltage across the piezoelectric thin film with the comparison voltage. . 5. A thin film magnetic body having a plurality of memory elements for recording information according to a magnetization direction, and one recording unit of the memory element can be elastically coupled to the magnetic thin film having at least magnetostriction and the magnetic thin film. A method for reading a memory, which comprises a piezoelectric thin film arranged at a position close to each other, wherein a magnetic field is applied to the magnetic thin film having magnetostriction, and a change in strain induced by the application of the magnetic field is suppressed. A method of reading a memory, wherein the signal is read by converting the signal into an electric signal by the piezoelectric thin film. 6. A thin film magnetic body having a plurality of memory elements for recording information according to a magnetization direction, and one recording unit of the memory element is close to a magnetic thin film having at least magnetostriction and elastically coupled to the magnetic thin film. A method of manufacturing a memory composed of piezoelectric thin films arranged at different positions, wherein the method of forming the piezoelectric thin film is a physical or chemical vapor deposition method, and the film is formed by obliquely forming the film. A method of manufacturing a memory characterized by inducing anisotropy in the in-plane direction of a plane. 7. A memory having a plurality of memory elements for recording information according to a magnetization direction of a thin film magnetic body, wherein one recording unit of the memory element can be elastically coupled to a magnetic thin film having at least magnetostriction. The magnetic thin film having magnetostriction is composed of piezoelectric thin films arranged at positions close to each other, and the magnetic thin film having a magnetostriction is Co _x Fe _y M (M is V, Nb, T
It is one kind of element selected from a, Cr, Mo, W, Ti, Zr, Hf, N and O, and 0 <x <1, 0 <y <
1, x + y ≦ 1), or a magnetic film represented by an oxide thereof, and a magnetic thin film in which the magnetic film and a magnetic film having soft magnetic characteristics are laminated.