JP2003124539A - Magnetoresistive effect film and memory using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistive effect film of very small size less than submicron size, specially, a magnetoresistive effect film of minimum processing size and further a memory element using the magnetoresistive effect film. SOLUTION: Magnetic bodies 111 and 112 as constitution elements of the magnetoresistive effect film have vertical magnetism and are in such shapes that when the magnetic bodies are viewed from the laminating direction of magnetoresistive effect films, the ratio of the length of the magnetic body to the width is 0.77 to 1.30 and the length and width are both <1 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submicron size magnetoresistive effect film and a memory using the magnetoresistive effect film.

[0002]

2. Description of the Related Art In recent years, semiconductor memories, which are solid-state memories, have been widely used in information equipment, such as DRAM (dynamic random access memory) and FeRAM (ferroelectric random memory).
Access memory), flash EEPROM (electrically erasable programmable read-only memory), and so on. The characteristics of these semiconductor memories have advantages and disadvantages, and there is no memory that meets all of the specifications required in current information devices. For example, DRAM has a high recording density and a large number of rewritable times, but is volatile and loses information when the power is turned off. Also flash EEPROM
Is non-volatile, but has a long erasing time and is not suitable for high-speed information processing.

In contrast to the current state of the semiconductor memory as described above, a memory (MRAM; magnetic random access memory) using the magnetoresistive effect has a recording time, a reading time, a recording density, the number of rewritable times, power consumption, etc. It is promising as a memory that meets all the specifications required by many information devices. In particular, MR utilizing the spin-dependent tunnel magnetoresistance (TMR) effect
Since AM can obtain a large read signal, AM is advantageous for high recording density or high-speed read, and its feasibility as MRAM has been proved in recent research reports.

The basic structure of the magnetoresistive film used as an element of the MRAM is a sandwich structure in which magnetic layers are formed adjacent to each other with a nonmagnetic layer interposed therebetween. Cu and Al ₂ O ₃ are examples of materials that are often used as the non-magnetic film. Giant magnetoresistive effect (GMR; Giant Magneto-Resista) is used for the magnetoresistive film that uses a conductor such as Cu for the non-magnetic layer.
nce) film, which uses an insulator such as Al ₂ O ₃ is called a spin-dependent tunnel effect (TMR) film. Generally TMR film is GM
It exhibits a larger magnetoresistive effect than the R film.

As shown in FIG. 8A, when the magnetization directions of the two magnetic layers are parallel, the electric resistance of the magnetoresistive film is relatively small, and as shown in FIG. When antiparallel, the electric resistance becomes relatively large. Therefore,
Information can be read by using one of the magnetic layers as a memory layer and the other as a detection layer and utilizing the above properties. For example, the magnetic layer 13 located on the non-magnetic layer 12 is a memory layer,
The lower magnetic layer 14 is used as a detection layer, and the magnetization direction of the memory layer is "1" when the magnetization direction is rightward and "0" when the magnetization direction is leftward. When the magnetization directions of both magnetic layers are rightward as shown in FIG. 9A, the electric resistance of the magnetoresistive film is relatively small, and as shown in FIG. 9B, the magnetization direction of the detection layer is rightward. When the magnetization direction of the memory layer is leftward, the electric resistance is relatively large. Further, as shown in FIG. 9C, when the magnetization direction of the detection layer is leftward and the magnetization direction of the memory layer is rightward, the electric resistance is relatively large, and as shown in FIG. When the magnetization direction of the magnetic layer is leftward, the electric resistance is relatively small. In other words, when the magnetization direction of the detection layer is fixed to the right, if the electric resistance is large, "0" is recorded in the memory layer, and if the electric resistance is small, "1" is recorded. Has been done. Alternatively, when the magnetization direction of the detection layer is fixed to the left, if the electric resistance is large, it means that “1” is recorded in the memory layer, and if the electric resistance is small,
"0" is recorded.

[0006]

In order to increase the recording density of MRAM, it is necessary to reduce the element size. However, if the size of the magnetic material exhibiting in-plane magnetization is reduced, a unique phenomenon occurs. Appears. EY Chen, S. Tehranni, T. Zh
u, M. Durlam, and H. Goronkin: J. Appl. Phys., 81,
According to 3992 (1997), the magnetization reversal magnetic field in the longitudinal direction of an infinite thin film magnetic material is assumed to be a single domain simultaneous rotation model.
Follow the 1 / W rule. This is due to the shape magnetic anisotropy, that is, as the width of the magnetic body is narrowed, the magnetization reversal magnetic field increases. From this fact, when miniaturizing the magnetoresistive effect film using a magnetic material exhibiting in-plane magnetization, it is necessary to pay sufficient attention to the magnetization reversal magnetic field.

When the magnetoresistive film using a magnetic material exhibiting in-plane magnetization is rectangular, curling of magnetization (end magnetic domain) is observed on the end face. This occurs in order to reduce the demagnetizing field energy, but it causes the magnetization reversal magnetic field to fluctuate, which is a serious problem in the device using the magnetoresistive effect film. There is also a proposal to make the shape of the magnetic body elliptical in order to suppress this variation, but in this case there is the problem that the magnetization reversal field becomes large. Further, when the shape of the magnetic body is made square, the curling of the magnetization spreads not only at the ends but also in the whole, and the magnetization is oriented in the direction of a vortex. Pt (2nm) / Ni ₆₅ Fe ₁₅ Co ₂₀ (15n
m) / Al ₅₀ Cu ₅₀ (25 nm) / Si-wafer rectangular multi-layered film, long side length is fixed at 1 μm and width is changed to MFM (m
The magnetized state was investigated using an (agnetic force microscope). As a result, for example, in the case of a rectangle with a length of 1 μm and a width of 0.6 μm, a magnetic pole was observed at the end in the length direction, but in the case of a square with both length and width of 0.6 μm, a magnetic pole was found at the end. Was not observed. As a result of further detailed examination, when both the length and the width were less than 1 μm and the ratio of the length and the width was 0.77 or more and 1.30 or less, the magnetization was swirled in the zero magnetic field, and the magnetic poles were formed at the ends. Was found not to be observed. In addition, Pt (2 nm) / Fe ₆₀ Co ₄₀ (15 nm) /
Al ₂ O ₃ (1.2nm) / Ni ₆₅ Fe ₁₅ Co ₂₀ (10nm) / Al ₅₀ Cu ₅₀ (2
When the magnetic resistance curve of (5 nm) / Si-wafer was examined, it was found that the magnetic resistance curve as shown in FIG. 10 can be obtained when the length-width ratio is 0.77 or more and 1.30 or less. In such a state, it is no longer possible to use this magnetoresistive film as a memory element.

Incidentally, the minimum processing dimension (F) in recent semiconductor fine processing technology is about 0.13 μm. Moreover, in the memory currently used, the cell size of SRAM is
It is said to be 40F ² . On the other hand, the cell size of MRAM is US
According to the method disclosed in P5991193, it becomes 4F ² and SRA
When considering replacing M with MRAM, the size of the magnetoresistive effect film is preferably 0.41 μm × 0.41 μm or less, and in order to realize MRAM with a higher recording density,
The size of the magnetoresistive film is preferably 0.13 μm × 0.13 μm. However, such miniaturization is not possible in the magnetoresistive effect film using a magnetic material exhibiting in-plane magnetization, which is being actively studied at present, for the above reason.

In view of this point, the present invention has an object to provide a magnetoresistive effect film of a submicron size or less, particularly a magnetoresistive effect film having a minimum processing dimension, and further to use the magnetoresistive effect film. The purpose is to provide the memory that was used.

[0010]

As a method for avoiding the formation of the end magnetic domains found in a magnetic body exhibiting in-plane magnetization, a magnetic body exhibiting perpendicular magnetization as described in, for example, JP-A-11-213650 is used. The method used is proposed. In this method, the magnetization is oriented in the direction perpendicular to the film surface even at the end of the magnetic body. Further, since magnetic reversal magnetic fields having substantially the same magnitude can be obtained in magnetic bodies of various shapes, the element can be easily manufactured. Furthermore, in a magnetoresistive effect film using a magnetic material exhibiting perpendicular magnetization, even if the size is reduced to less than 1 μm, the magnetization does not become spiral, and even in a zero magnetic field, two magnetization directions such as upward and downward directions are obtained. Since it can be used, it can be used as a memory device.

Therefore, the element size is reduced by processing the magnetoresistive effect film using a magnetic material exhibiting perpendicular magnetization into a size of less than 1 μm so that the ratio of the length to the width is close to 1. It is possible to reduce the size, and by using this as a memory element, a high recording density memory can be realized. When the ratio of length to width is within the range of 0.77 or more and 1.30 or less, the magnetoresistive effect film using the in-plane magnetized film cannot be used as a memory element, but the magnetoresistive effect film using the perpendicular magnetized film is used. It is possible.

The shape includes a square shape.

Further, the above shape includes that it is circular.

As the perpendicular magnetization film, at least one element selected from rare earth metals such as Gd, Dy and Tb and Co, Fe,
An alloy film of at least one element selected from transition metals such as Ni, a ferrimagnetic material that is an artificial lattice film, an artificial lattice film of a transition metal and a noble metal such as Co / Pt, and a crystalline magnetic anomaly in the direction perpendicular to the film surface such as CoCr. An alloy film having a directionality is mainly mentioned. Among these materials, a ferrimagnetic material composed of a rare earth metal and a transition metal exhibits a magnetization curve with a squareness ratio of 1, and causes a sharp magnetization reversal when a magnetic field is applied. Therefore, it is used as a memory element. Most suitable for magnetoresistive film.

The non-magnetic material used in the magnetoresistive film of the present invention may be a conductor or an insulator.

The memory of the present invention has a magnetoresistive film as a memory element, and has means for recording information on the magnetoresistive film and means for reading the recorded information.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows Pt (2 nm) / Tb ₂₀ (Fe ₆₀ Co ₄₀ ) ₈₀ (15n
m) / Al ₂ O ₃ (1.2nm) / Gd ₂₀ (Fe ₆₀ Co _{4 0} ) ₈₀ (15nm) / Al
It is the measurement result of the magnetoresistive curve of the magnetoresistive effect film of ₅₀ Cu ₅₀ (25 nm) / Si-wafer. However, the magnetoresistive film is 0.2 μm
× 0.2μm square, Tb _{2 0} (Fe ₆₀ Co ₄₀ ) ₈₀ and Gd ₂₀ (Fe
₆₀ Co ₄₀ ) ₈₀ shows perpendicular magnetization.

As can be seen by comparing FIG. 1 and FIG. 10, the magnetoresistive effect film using the perpendicularly magnetized film gives a square magnetoresistive curve and can take two resistance values at zero magnetic field. In the magnetoresistive film using the in-plane magnetized film, the magnetoresistive curve has a closed shape. This is because, as described above, the size of the magnetic substance is small, so that the magnetization is oriented in the in-plane magnetized film at the zero magnetic field in a state of swirling.

FIG. 11 shows the results of similarly measuring the magnetoresistive curve with the size of the magnetoresistive film using the magnetic material exhibiting the in-plane magnetization set to 10 μm × 10 μm. Thus, as the size increases, the magnetoresistive curve has a shape close to a rectangular shape.

FIG. 12 shows the results of similarly measuring the magnetoresistive curve with the size of the magnetoresistive film using the magnetic material exhibiting the in-plane magnetization set to 0.2 μm × 1 μm. However, there is uniaxial magnetic anisotropy in the longitudinal direction. Thus, the length of one side
Even if it is as short as 0.2 μm, if it is a rectangle whose length and width are sufficiently different, the magnetoresistive curve becomes almost rectangular.

As can be seen from the above results, the magnetoresistive effect film using the in-plane magnetized film cannot realize a memory element having a small size, and the perpendicular magnetized film can realize it. . The shape of the magnetoresistive effect film using this perpendicularly magnetized film is not limited to a square and may be, for example, a circle. According to the results of experiments including examples described later, in the case of a magnetoresistive effect film using a perpendicular magnetization film, the shape of the magnetic body viewed from the stacking direction has a ratio of the length to the width of the magnetic body of 0.77 or more and 1.30 or more. It has been found that if the length and width are both less than 1 μm in the following range, a magnetoresistive curve that can be sufficiently used as a memory element is exhibited.

Gd, Dy, and Tb are preferably used as the rare earth metal used for the magnetic body exhibiting perpendicular magnetization. Gd is preferably used to reduce the magnetization reversal field. On the contrary, when increasing the magnetization reversal magnetic field, it is preferable to use Tb. Further, although Fe, Co, and Ni are preferably used as the transition metal, since the alloy of Fe and Co has a large spin polarization, it is possible to obtain a large magnetoresistance change.

The non-magnetic film formed between the two magnetic bodies of the magnetoresistive effect film has a magnetoresistance change regardless of whether it is a conductor or an insulator. However, in the case of a conductor, the magnitude of change in magnetoresistance is generally smaller than that in the case of an insulator. When a conductor is used as this non-magnetic film, Cu is preferably selected. In the case of an insulator, Al ₂ O ₃ is preferably selected.

By using the magnetoresistive film of the present invention as a memory element, the recording density can be increased.

Recording of information on the magnetoresistive film is generally performed by applying a magnetic field. To selectively perform recording from a plurality of arranged memory elements, it is necessary to apply a magnetic field so that only the magnetization of a desired memory element is reversed.

As a method for realizing this, for example, a conductive wire is arranged between the respective memory elements, and a current is passed through the conductive wires to generate a magnetic field in a direction perpendicular to the film surface of the memory element. When a current is applied to the four conductors around the memory element to be recorded so that the magnetic field is applied in the same direction to the memory element, the largest magnetic field is applied only to the desired memory element. Recording is performed only in the memory element.

The above-mentioned recording method is a method of using only the magnetic field in the direction perpendicular to the memory element, but selective recording can also be performed by applying a magnetic field in the in-plane direction to the memory element. is there. For example, a conductive wire is arranged between the memory elements, and a conductive wire is also arranged above or below the memory element. However, the conductors between the elements and the conductors above or below the elements are arranged at twisted positions so that they do not exist in one plane, and these conductors are arranged orthogonally when viewed from directly above. An electric current is passed through a conductor wire just next to a desired memory element to be recorded among the conductor wires arranged in this way,
A magnetic field is applied in a direction perpendicular to the film surface of the memory element, and a current is also applied to a conductor wire arranged above or below the memory element to apply a magnetic field in the film surface direction to the memory element. By doing so, it becomes possible to record only the memory element to which the magnetic field in the film plane direction and the magnetic field in the film plane perpendicular direction are simultaneously applied. The conducting wire for generating the magnetic field in the in-plane direction of the film may be separately provided as described above, but the conducting wire for generating the in-film magnetic field can be omitted by using the bit line.

Information is read out by passing a current through the magnetoresistive film and detecting the voltage of the magnetoresistive film. In the case of the GMR film, the direction of the current to flow may be either in the film surface direction or in the film surface vertical direction. However, it is known that a relatively large magnetoresistive effect can be obtained by flowing in the direction perpendicular to the film surface. When the memory element is a TMR film, current must flow in the direction perpendicular to the film surface so that electrons tunnel through the insulating film.

[0030]

EXAMPLES Next, the magnetoresistive film of the present invention will be described in more detail based on examples.

(Example-1) FIG. 2 schematically shows a cross section of the magnetoresistive film of Example-1.

In this embodiment, a Si (silicon) substrate 100 is used as a substrate, and a 15 nm thick Gd ₂₀ (Fe ₅₅ Co ₄₅ ) ₈₀ film and a non-magnetic film (tunnel) are used as the first magnetic film 111. As an insulating film) 113, an Al ₂ O ₃ film having a thickness of 1.3 nm, the second
Magnetic film 112 of 15 nm thick Tb ₂₀ (Fe ₅₀ Co ₅₀ ).
_{A 80} nm film and a 2 nm Pt film were sequentially formed as the protective film 114. P
The t film is effective in preventing corrosion such as oxidation of the magnetic film. Here, both the Gd ₂₀ (Fe ₅₅ Co ₄₅ ) ₈₀ film and the Tb ₂₀ (Fe ₅₀ Co ₅₀ ) ₈₀ film are dominant in the transition metal sublattice magnetization. Next, a 0.8 μm square resist film was formed on the obtained multilayer film, and the magnetoresistive film not covered with the resist was removed by dry etching. After etching, 34 nm thick Al
₂ O ₃ film is formed, and the resist and Al ₂ O _{3 on} top of it are also formed.
The film was removed, and an insulating film 121 for performing electrical insulation between the upper electrode and the Gd ₂₀ (Fe ₆₀ Co ₄₀ ) ₈₀ film was formed. afterwards,
The upper electrode 122 was formed of an Al film by the lift-off method, and the Al ₂ O ₃ film in the portion not covered with the upper electrode was partially removed to provide an electrode pad for connecting a measurement circuit.

The obtained magnetoresistive film is perpendicular to the film surface.
Applying a magnetic field of 2 MA / m, Tb₂₀(Fe₅₀Co ₅₀)₈₀Mark the magnetization of the film
Magnetization was performed in the direction of the applied magnetic field. However, 1 cm square Tb
₂₀(Fe₅₀Co₅₀)₈₀The coercive force of the film shows a large value of 0.6 MA / m.
However, the coercive force of the obtained magnetoresistive film is as large as
Expected to show value.

A constant current power source was connected to the upper electrode 122 and the lower electrode (Si substrate 100) of the magnetoresistive film to make Gd ₂₀ (Fe
_A constant current is passed so that electrons tunnel through the Al ₂ O ₃ film 113 between the ₆₀ Co ₄₀ ) ₈₀ film and the Tb ₂₀ (Fe ₅₀ Co ₅₀ ) ₈₀ film. A magnetic field was applied in a direction perpendicular to the surface of the magnetoresistive film, and the magnitude and direction of the magnetic field were changed to measure the change in the voltage of the magnetoresistive film (magnetoresistance curve). The result is shown in FIG.

(Example-2) This example was the same as Example-1 except that the resist size (processing size) of Example-1 was 0.2 μm × 0.2 μm. The measurement result of the magnetoresistive curve is shown in FIG. 4, and the schematic view of the cross section of the magnetoresistive film is shown in FIG.

(Embodiment 3) This embodiment is the same as Embodiment 1 except that the resist shape of Embodiment 1 is a circle having a diameter of 0.2 μm.
Same as. The measurement result of the magnetic resistance curve is shown in FIG.
A schematic view of a cross section of the magnetoresistive film is shown in FIG.

(Example-4) Examples-1 to 1 after forming transistors, wiring layers, etc. on a Si substrate (Si wafer)
A magnetoresistive film having the film structure used in 3 was formed and further processed into 9 memory elements in 3 rows and 3 columns to form a memory cell array. A circuit configuration of this memory including such a memory cell array is shown in FIG. In this memory,
Information recording is performed by applying an in-plane magnetic field and a vertical magnetic field to a desired memory element. Here, the in-plane magnetic field is generated by passing a current through the bit line.

As a configuration for recording information, FIG.
As shown in FIG. 9, nine memory elements (magnetoresistive effect films) 101 to 109 are arranged in a 3 × 3 array in the memory cell array, and write lines 311 to 311 extending in the column direction sandwich each row of the memory elements. 314 is provided. The upper ends of the write lines 311 to 314 in the drawing are commonly connected,
These writing lines 311 to 311 are respectively provided at the lower ends of the drawings.
Transistor 211 for connecting 14 to the power supply 411
To 214 and transistors 215 to 218 for connecting to the wiring 300 are provided.

As a structure for reading information, each memory element (magnetoresistive film) 101-109.
Transistors 231 to 239 for grounding the memory element are formed in series at one end of each.
Bit lines 331 to 333 are provided for each row, and transistors 240 to connect the bit lines 331 to 333 to a power supply 412 via fixed resistors 150 at the right ends of the bit lines 331 to 333, respectively. 242
And transistors 221 to 223 for connecting these bit lines 331 to 333 to the wiring 300. The bit line 331 is connected to the other ends of the magnetoresistive effect films 101 to 103, and the bit line 332 is connected to the magnetoresistive effect film 104.
To 106, and the bit line 333 is connected to the other ends of the magnetoresistive films 107 to 109. Bit line 331
The left ends of ˜333 in the figure are commonly connected, and are connected via a transistor 251 to a sense amplifier 500 for amplifying the difference between the potential of these bit lines and the reference voltage Ref.
Further, it is connected to the ground potential through the transistor 224. Further, word lines 341 to 343 are provided for each column, and the word line 341 is the transistors 231 and 23.
4, 237, the word line 342 is connected to the gates of the transistors 232, 235, 238, and the word line 343 is connected to the gates of the transistors 233, 236, 239.

A method of selectively reversing the magnetization of the magnetic film of the selected memory element will be described. For example, when selectively reversing the magnetization of the magnetoresistive effect film 105, the transistors 212, 217, 222, and 224 are made conductive, and the other transistors are made in a cutoff state. By doing so, current flows through the write lines 312 and 313, and a magnetic field is applied in a direction perpendicular to the film surface of the magnetoresistive effect film 105. Further, a current also flows through the bit line 332, and the magnetic field generated by the current flows in the magnetoresistive film 10.
It is applied in the in-plane direction to the film surface of No. 5. Therefore, since a magnetic field in the in-plane direction and a relatively large magnetic field in the direction perpendicular to the film plane are applied to the magnetoresistive effect film 105, the magnetization of the magnetoresistive effect film 105 can be reversed. Since no magnetic field is applied to the other magnetoresistive effect films 101 to 104 and 106 to 109 as much as that applied to the magnetoresistive effect film 105, the magnetization direction can be prevented from being reversed. After all, it is possible to reverse the magnetization of only the magnetoresistive film 105 by appropriately setting the magnitude of the current. Further, when a magnetic field in the direction opposite to that described above is applied to the magnetoresistive effect film 105, the transistors 213, 216, 222, and 224 are turned on, and the other transistors are turned off. In this way, a current flows through the bit line 332 and a magnetic field is applied to the magnetoresistive effect film 105 in the in-plane direction, and at the same time, a current flows through the write lines 313 and 312 in the opposite direction to the direction described above. A magnetic field perpendicular to the film surface in the opposite direction is applied to the resistance effect film 105. Therefore, binary information different from the above is recorded on the magnetoresistive film 105.

Next, the read operation will be described. For example, it is assumed that the information recorded on the magnetoresistive film 105 is read. In this case, the transistors 235 and 241 are turned on. Then, the power source 412, the fixed resistor 150, and the magnetoresistive film 105 are connected in series. Therefore, the power supply voltage is divided into respective resistances at a ratio of the resistance value of the fixed resistance 150 and the resistance value of the magnetoresistive effect film 105. Since the power supply voltage is fixed, if the resistance value of the magnetoresistive film changes,
The voltage applied to the magnetoresistive film changes. By reading this voltage value with the sense amplifier 500, the information recorded in the magnetoresistive effect film 105 can be read.

FIG. 7 schematically shows the three-dimensional structure of one peripheral portion of such a memory element. here,
The vicinity of the magnetoresistive effect film 105 in FIGS. 3, 4 and 5 is shown. For example, two n-type diffusion regions 162 and 163 are formed in a p-type Si substrate 161, and a word line (gate electrode) is interposed between these n-type diffusion regions 162 and 163.
342 is formed. The ground line 356 is connected to the n-type diffusion region 162 via the contact plug 351, and the magnetoresistive film 105 is connected to the n-type diffusion region 163 via the contact plugs 352, 353, 354, 357 and the local wiring 358. . The magnetoresistive film 105 is further provided with a bit line 332 via a contact plug 355.
It is connected to the. Write lines 312 and 313 for generating a magnetic field are arranged beside the magnetoresistive film 105.

(Comparative Example) FIG. 2 schematically shows a cross section of a magnetoresistive effect film of a comparative example.

A Si substrate 100 is used as a substrate, and
The first magnetic film 111 is made of Ni with a thickness of 15 nm.₆₅Fe₁₅Co₂₀
Film, non-magnetic film (tunnel insulating film) 113 of 1.3 nm
Thickness of Al₂O₃Film, 15 nm thick as the second magnetic film 112
Fe₆₀Co₄₀A 2 nm Pt film is sequentially formed as the film and the protective film 114.
I made it. Next, a 0.8 μm square resist is placed on top of the resulting multilayer film.
Coating film and cover the resist by dry etching.
The part of the magnetoresistive film that was not exposed was removed. Etch
Al film with a thickness of 34 nm₂O₃Form a film, then register
And the upper Al₂O₃Remove the film and remove the upper electrode and Ni₆₅F
e₁₅Co₂₀Insulating film 121 for electrically insulating the film
Was formed. After that, the upper electrode 1 is formed by the lift-off method.
22 is made of Al film and is not covered by the upper electrode
Minute Al₂O ₃For removing a part of the membrane and connecting the measurement circuit
The electrode pad was used.

A magnetic field of 2 MA / m was applied to the magnetoresistive effect film thus obtained in the in-plane direction of the film surface, and Fe ₆₀ Co ₄₀
The film was magnetized by directing the magnetization of the film in the direction of the applied magnetic field.

A constant current power source was connected to the upper electrode 122 and the lower electrode (Si substrate 100) of the magnetoresistive film, and Ni ₆₅ Fe _{15 was used.}
A constant current is passed so that electrons tunnel through the Al ₂ O ₃ film 113 between the Co ₂₀ film and the Fe ₆₀ Co ₄₀ film. A magnetic field was applied to the surface of the magnetoresistive film in the in-plane direction, and the magnitude and direction of the magnetic field were changed to measure the change in the voltage of the magnetoresistive film (magnetoresistance curve). The result is shown in FIG.

[0047]

As described above, according to the present invention, it is possible to provide a small magnetoresistive effect film having a size of submicron size or less, and further recording by using the magnetoresistive effect film as a memory element. It is possible to provide a high-density memory.

[Brief description of drawings]

FIG. 1 is a measurement result of a magnetoresistive curve of a magnetoresistive film of the present invention having a size of 0.2 μm × 0.2 μm.

FIG. 2 is a diagram schematically showing a cross section of a magnetoresistive effect film described in Examples-1, 2, 3 and Comparative Example.

FIG. 3 is a measurement result of a magnetoresistive curve of the magnetoresistive film of the present invention described in Example-1.

FIG. 4 is a measurement result of a magnetoresistive curve of the magnetoresistive film of the present invention described in Example-2.

5 is a measurement result of a magnetoresistive curve of the magnetoresistive effect film of the present invention described in Example-3. FIG.

FIG. 6 is a schematic diagram of an electric circuit of a magnetic field application wiring and a detection wiring of the memory of Example-4.

FIG. 7 is a schematic view showing a cross section of a part of the memory of Example-4.

8A is a sectional view schematically showing a state where the magnetizations of the magnetoresistive effect film are parallel, and FIG. 8B is a sectional view schematically showing a state where the magnetizations of the magnetoresistive effect film are antiparallel. .

FIG. 9 is a diagram for explaining a recording / reproducing principle in a conventional magnetoresistive effect film using an in-plane magnetized film, FIG.
And (c) are cross-sectional views that schematically show the state of magnetization when reading recorded information “1”, and (b) and (d) show the magnetization state when reading recorded information “0”. It is sectional drawing which shows a state typically.

FIG. 10 is a measurement result of a magnetoresistive curve of a conventional magnetoresistive film.

FIG. 11 is a measurement result of a magnetoresistive curve of a conventional magnetoresistive film.

FIG. 12 is a measurement result of a magnetoresistive curve of a conventional magnetoresistive film.

FIG. 13 is a measurement result of a magnetoresistive curve of a conventional magnetoresistive film described in Comparative Example.

[Explanation of symbols]

12 non-magnetic film 13, 14, 111, 112 magnetic film 100 Si substrate 101-109 magnetoresistive effect film 113 non-magnetic film (tunnel insulating film) 114 protective film 121, 123 insulating film 122 upper electrode 150 fixed resistance 161 p-type Si Substrates 162, 163 n-type diffusion regions 211-218, 221-224, 231-242, 2
51 transistors 311 to 314 conducting wires (writing lines) 331 to 333 bit lines 341 to 343 word lines (gate electrodes) 351 to 355, 357 contact plugs 356 ground lines 358 local wiring 411, 412 power supply 500 sense amplifier

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 10/16 H01F 10/16 10/30 10/30 10/32 10/32 H01L 27/105 H01L 27/10 447

Claims (8)

[Claims] 1. In a magnetic body that is a constituent element of a magnetoresistive effect film, the magnetic body exhibits perpendicular magnetization, and the shape of the magnetic body seen from the stacking direction of the magnetoresistive effect film has a length relative to the width of the magnetic body. A magnetoresistive film having a ratio of 0.77 or more and 1.30 or less and a length and a width of less than 1 μm. 2. The magnetoresistive film according to claim 1, wherein the shape is a square. 3. The magnetoresistive film according to claim 1, wherein the shape is circular. 4. The magnetoresistive effect film according to claim 1, wherein the magnetic substance is a ferrimagnetic substance containing a rare earth metal, Fe and Co as main components. 5. The magnetoresistive film is a composite body in which at least a first magnetic body, a non-magnetic body and a second magnetic body are sequentially stacked, and the non-magnetic body is a conductor. The magnetoresistive effect film according to any one of claims 1 to 4. 6. The magnetoresistive film is a composite body in which at least a first magnetic body, a non-magnetic body and a second magnetic body are sequentially laminated, and the non-magnetic body is an insulator. The magnetoresistive effect film according to any one of claims 1 to 4. 7. The magnetoresistive film according to claim 6, wherein the magnetoresistive film exhibits a spin tunnel effect when an electric current is applied to the magnetoresistive film in a direction perpendicular to the film surface. 8. A memory comprising the magnetoresistive effect film according to claim 1 as a memory element, and means for recording information, and means for reading the recorded information.