JP2003110166A - Magnetoresistance effect film, and memory using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistance effect film which uses a vertical magnetization film and has a greater change rate of magnetoresistance. SOLUTION: In the magnetoresistance effect film including first and second magnetic layers 52, 56, and a non-magnetic layer 54 held between the first and second magnetic layers 52, 56, at least one of the first and second magnetic layers 52, 56 is constructed as a ferrimagnetic layer which uses rare earth metals Fe and Co as chief components, and high spin polarizability magnetic layers 53, 55 are formed between the non-magnetic layer 54 and the ferrimagnetic layers 52, 56, which comprises Fe and Co, and exchange-couples with the ferrimagnetic layers 52, 56.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive effect film using a ferrimagnetic material containing a rare earth metal and a transition metal as main components, and more particularly to a magnetoresistive effect film having a large magnetoresistive effect and such a magnetic material. The present invention relates to a memory using a resistance effect film.

[0002]

2. Description of the Related Art In recent years, a semiconductor memory, which is a solid-state memory, has been widely used in information equipment, such as DRAM (dynamic random access memory) and FeRAM.
There are various types such as (ferroelectric random access memory) and flash EEPROM (electrically erasable programmable read only memory). The characteristics of these semiconductor memories have advantages and disadvantages, and there is no memory satisfying all the specifications required in the current information equipment. For example, a DRAM has a high recording density and a large number of rewritable times, but it is volatile and the stored information is lost when the power is turned off. On the other hand, flash EEPRO
Although M is non-volatile, it takes a long time to erase information 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 is non-volatile, and has a writing time, a reading time, a recording density, and a rewriting. It is promising as a memory that satisfies all the specifications required by many information devices in terms of the number of possible times and power consumption.
In particular, spin-dependent tunnel magnetoresistance (TMR; Tunnel Mag)
The MRAM utilizing the neto-Resistance) effect is advantageous for high recording density or high-speed reading because a large read signal can be obtained, and its feasibility as an MRAM has been proved in recent research reports.

The basic structure of a magnetoresistive effect film used as an element of an MRAM is a sandwich structure in which a magnetic layer is formed adjacent to both sides of a nonmagnetic layer. As a material often used for the non-magnetic layer, Cu or Al ₂ O _{3 is used.}
Is mentioned. Cu in the non-magnetic layer in the magnetoresistive film
The one using a conductor such as a giant magnetoresistive effect (G
MR; Giant Magneto-Resistance) film, Al ₂ O ₃
The one using an insulator such as is called a spin-dependent tunnel magnetoresistive (TMR) film. Generally, the TMR film is GM
It exhibits a larger magnetoresistive effect than the R film.

FIGS. 7A and 7B show a magnetoresistive film having a structure in which two magnetic layers, which are in-plane magnetized films, are stacked with a nonmagnetic layer interposed therebetween. The direction of magnetization is indicated by the arrow. When the magnetization directions of the two magnetic layers are parallel as shown in FIG. 7A, the electric resistance of the magnetoresistive film (the electric resistance between one magnetic layer and the other magnetic layer).
Is relatively small, and the electric resistance is relatively large when the magnetization directions are antiparallel as shown in FIG. 7 (b). Therefore, one magnetic layer is used as a memory layer and the other magnetic layer is used as a detection layer.
Information can be read by utilizing the above property. For example, when the magnetic layer 13 located above the non-magnetic layer 12 is a memory layer and the magnetic layer 11 located below is a detection layer, "1" is set when the magnetization direction of the memory layer (magnetic layer 13) is rightward, and leftward In case of, it is set to "0".

As shown in FIG. 8A, both magnetic layers 11, 1
When the magnetization directions of 3 are both rightward in the drawing, the electric resistance of the magnetoresistive film is relatively small, and the magnetization direction of the detection layer 11 is rightward in the drawing and the memory layer 1 as shown in FIG. 8B.
When the magnetization direction of 3 is leftward in the drawing, the electric resistance is relatively large. Similarly, when the magnetization direction of the detection layer 11 is leftward and the magnetization direction of the memory layer 13 is rightward as shown in FIG. 8C, the electric resistance is relatively large, and as shown in FIG. When the magnetization directions of both magnetic layers 11 and 13 are leftward, the electric resistance is relatively small. That is, when the magnetization direction of the detection layer 11 is fixed to the right, if the electric resistance is relatively large, “0” is recorded in the memory layer 13, and the electric resistance is relatively large. If it is small, "1" is recorded. Alternatively,
If the magnetization direction of the detection layer 11 is fixed to the left, if the electric resistance is relatively large, the memory layer 13
"1" is recorded in the field, and "0" is recorded if the electric resistance is relatively small.

Therefore, the composition of each magnetic layer 11, 13 is selected so that the coercive force of the detection layer 11 is relatively large and the coercive force of the memory layer 13 is relatively small, and the detection layer 11 is magnetized in one direction. Then, by adding magnetization to the memory layer 13 to the extent that magnetization reversal of the detection layer 11 does not occur and changing the direction of magnetization of the memory layer 13, it becomes possible to record information on the magnetoresistive film. Also, the recorded information can be read by detecting the electric resistance of the magnetoresistive film.

When the element size of the magnetoresistive effect film is reduced in order to increase the recording density of the MRAM, in the MRAM using the in-plane magnetized film as the magnetic layer, there is an influence such as demagnetizing field or curling of the magnetization of the element end face. Therefore, there arises a problem that information cannot be held. In order to avoid this problem, for example, the shape of the magnetic layer may be rectangular. However, this method cannot reduce the element size, and therefore the improvement in recording density cannot be expected so much.

Therefore, the present applicant has already proposed to avoid the above problem by using a perpendicular magnetization film, as described in, for example, Japanese Unexamined Patent Application Publication No. 11-213650. When the perpendicular magnetization film is used, the demagnetizing field does not increase even when the element size is reduced, so that a magnetoresistive effect film having a smaller size than the MRAM using the in-plane magnetization film can be realized.

In the magnetoresistive effect film using the perpendicular magnetization film,
Similar to the magnetoresistive effect film using the in-plane magnetized film, the electric resistance of the magnetoresistive effect film is relatively small when the magnetization directions of the two magnetic layers are parallel, and the electric resistance when the magnetization directions are antiparallel. Is relatively large. The magnetic layer 23 located above the non-magnetic layer 22 is used as a memory layer, and the magnetic layer 21 located below is used as a detection layer. The magnetization direction of the memory layer 23 is "1" when the magnetization direction is upward, and "0" when the magnetization direction is downward. And As shown in FIG. 9A, when the magnetization directions of both the magnetic layers 21 and 23 are upward, the electric resistance of the magnetoresistive effect film is relatively small.
As shown in (c), when the magnetization direction of the detection layer 21 is downward and the magnetization direction of the memory layer 23 is upward, the electric resistance becomes relatively large. Similarly, if the magnetization direction of the detection layer 21 is upward and the magnetization direction of the memory layer 23 is downward as shown in FIG. 9B, the electric resistance becomes relatively large, and as shown in FIG. 9D. Moreover, when the magnetization directions of both magnetic layers 21 and 23 are downward, the electric resistance becomes relatively small. That is, when the magnetization direction of the detection layer 21 is fixed upward, if the electric resistance is relatively large, "0" is recorded in the memory layer 23, and the electric resistance is relatively large. If it is smaller, "1" is recorded. Alternatively, when the magnetization direction of the detection layer 21 is fixed downward, if the electric resistance is relatively large, "1" is recorded in the memory layer 23, and the electric resistance is relatively large. If it is small, "0" is recorded.

In a magnetoresistive element using such a perpendicular magnetic film, the material used for the vertical magnetic film is, for example, at least one element selected from rare earth metals such as Gd, Dy, and Tb, and Co and Fe. , An alloy film of at least one element selected from transition metals such as Ni, an artificial lattice film, an artificial lattice film of a transition metal such as Co / Pt and a noble metal, and a crystalline magnetic anisotropy in the direction perpendicular to the film plane of CoCr. And an alloy film having properties. Among these materials, the alloy film of rare earth metal and transition metal has a squareness ratio of 1
Is suitable for a magnetoresistive film used as a memory element because it exhibits a sharp magnetization reversal when a magnetic field is applied and is easy to create.

In order to obtain a large magnetoresistance change rate, it is desired that the magnetic layer formed in contact with the nonmagnetic layer has a large spin polarizability. It is known that Fe, Co or their alloys have a large spin polarizability, but as a result of intensive studies by the present inventors, Gd, Tb or Dy existing near the interface with the non-magnetic layer has a magnetoresistance. It turns out that it reduces the rate of change. That is, it is difficult to obtain a large rate of change in magnetoresistance in a magnetoresistive film having a film structure in which a nonmagnetic layer is sandwiched by magnetic materials containing a rare earth metal and a transition metal as main components.

Therefore, as proposed by the present inventors in Japanese Unexamined Patent Publication No. 2000-306374, a high spin polarizability magnetic substance made of Fe, Co or an alloy thereof is formed between the non-magnetic layer and the perpendicular magnetization film. It is possible to obtain a large magnetoresistance change rate. However, in order to utilize the change in magnetoresistance due to the magnetization in the direction perpendicular to the film surface, the magnetization of the magnetic substance disposed between the perpendicular magnetization film and the nonmagnetic layer must be oriented in the direction perpendicular to the film surface. Fe, Co or F
The magnetic body made of eCo has a property that the magnetization is oriented in the in-plane direction of the film (in-plane magnetization anisotropy). However, due to the exchange coupling force with the perpendicularly magnetized film formed in contact with this magnetic body, the perpendicular direction is changed. Is directed to.

[0014]

As described above, in the high spin polarizability magnetic material, the magnetization is oriented perpendicular to the film surface by the exchange coupling force. However, the magnetization of the high spin polarizability magnetic material is oriented in the perpendicular direction. Thickness is limited to a few nm
Must be: If the thickness is further increased, the magnetization will be oriented in the in-plane direction, not in the direction perpendicular to the plane of the film, in the portion far from the perpendicular magnetization film. When trying to form a thin film of a high spin polarizability magnetic material of this thickness,
Depending on the film forming conditions, the high spin polarizability magnetic substance formed between the non-magnetic layer and the perpendicular magnetization film may not have a uniform film shape but may have an island shape or a net shape. In such a case, the perpendicular magnetization film partially contacts the nonmagnetic layer. Alternatively, even in the case of a film shape, in the method of forming a film by giving large energy to magnetic atoms such as sputtering, the interface between the perpendicular magnetization film and the high spin polarizability magnetic material is not clear, and the two magnetic materials Atoms may be mixed.

That is, even if a material having a high spin polarizability is arranged at the interface, the effect of the perpendicularly magnetized film exchange-coupled to the material appears in the magnetoresistance change rate.

In view of this point, an object of the present invention is to provide a magnetoresistive effect film using a perpendicular magnetization film and having a large magnetoresistive change rate, and a memory using such a magnetoresistive effect film. .

[0017]

The magnetoresistive effect film of the present invention comprises a first and second magnetic layers and a nonmagnetic layer sandwiched between the first and second magnetic layers. At
At least one of the first and second magnetic layers is a ferrimagnetic layer containing a rare earth metal, Fe and Co as main components, and is composed of Fe and Co between the nonmagnetic layer and the ferrimagnetic layer. A high spin polarizability magnetic layer exchange-coupled with the magnetic layer is formed.

That is, in the present invention, in order to obtain a large magnetoresistance change rate in a magnetoresistive effect film using an exchange coupling film of a ferrimagnetic layer containing a rare earth metal as a magnetic material and a high spin polarizability magnetic layer. It was made paying attention that the ferrimagnetic layer is also preferably formed of a material having a spin polarization as large as possible. As the ferrimagnetic layer, a ferrimagnetic layer containing a rare earth metal, Fe and Co as main components is used. It is the one to use.

In the present invention, it is effective to form the high spin polarizability magnetic layer on either the upper surface or the lower surface of the non-magnetic layer, but if it is formed on both surfaces of the non-magnetic layer,
A larger magnetoresistance change rate can be obtained. In the case of forming high spin polarizability magnetic layers on both sides of the non-magnetic layer, both the above-mentioned first and second magnetic layers are made of rare earth metal, Fe
It is preferable to use a ferrimagnetic layer containing Co and Co as main components.

In the ferrimagnetic layer in such a magnetoresistive film, rare earth metals are Gd, Tb, and D.
y or these alloys can be used. If the coercive force in the magnetic layer is to be reduced for use as a memory layer or the like, Gd is the main component, and if the coercive force is to be increased for use in the detection layer or the like, Dy or Tb is the main component. Preferably.

[0021] In the present invention, the non-magnetic layer, the insulating material such as a conductor, Al ₂ O _3, or the such as Cu can be used, Al ₂
When O ₃ is used, a spin tunnel effect occurs and a larger magnetoresistance change rate can be obtained, which is preferable.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, preferred embodiments of the present invention will be described with reference to the drawings.

First, the results of the present inventors' study of the relationship between the composition of Co in the ferrimagnetic layer and the magnetoresistance change rate in the structure in which the high spin polarizability magnetic layer is not provided will be described.

FIG. 1 shows Pt (film thickness 2 nm) / Tb₂₀(F
e_100-XCo_X)₈₀(Film thickness 10 nm) / Al₂O₃(Film thickness
2.2 nm) / Gd₂₀(Fe_100-XCo_X)₈₀(Film thickness 10
nm) / Al₅₀Cu₅₀(Film thickness 25 nm) / Si substrate (S
In the TMR element having the film structure of (i-wafer), C of the magnetic film
o Change in magnetoresistance change rate with respect to composition (X atom%)
It is a graph which shows a child. Where Tb₂₀(Fe_100-XC
o_X)₈₀Membrane and Gd₂₀(Fe _100-XCo_X)₈₀The membrane is ferri
A magnetic layer, Al₂O₃The film is a non-magnetic layer. From Figure 1
As can be seen, the rare earth metals, Fe and Co
Magnetoresistance effect when the remagnetic layer is formed in contact with the nonmagnetic layer
In the pericarp, C for Fe and Co in the ferrimagnetic layer
To make the composition of o 30 atomic% or more and 70 atomic% or less
Therefore, a large magnetoresistance change rate can be stably obtained.
Noh. There is a high spin component between the ferrimagnetic layer and the nonmagnetic layer.
Even if a polar magnetic layer is present, the ferrimagnetic layer
The composition of Co with respect to Fe and Co is 30 atomic% or more
It is considered preferable that the content be 70 atomic% or less.

FIG. 2 shows a magnetoresistive device according to an embodiment of the present invention.
It is sectional drawing which shows the structure of an effect film. This magnetoresistive film
Is a 25 nm thick Al film on the Si substrate 50.₅₀Cu₅₀Or
Conductive layer 51 made of Gd having a thickness of 50 nm₂₀(Fe₆₀Co
₄₀)₈₀A first ferrimagnetic layer 52 of 1 nm thick
Fe_100-XCo_XA first high spin polarizability magnetic layer 5
3, Al with a thickness of 2.2 nm₂O₃(Aluminum oxide)
Non-magnetic layer 54 consisting of 1 nm thick Fe_100-XCo_XFrom
Second high spin polarizability magnetic layer 55 having a thickness of 30 nm
Tb₂₀(Fe₄₀Co₆₀)₈₀Second ferrimagnetic layer comprising
56 and a protective layer 57 made of Pt having a thickness of 2 nm,
The films are sequentially formed by sputtering. Sanawa
, Pt (film thickness 2 nm) / Tb₂₀(Fe₄₀Co₆₀)
₈₀(Film thickness 30 nm) / Fe_100-XCo_X(Film thickness 1 nm) /
Al₂O₃(Film thickness 2.2 nm) / Fe_{100- X}Co_X(Film thickness 1
nm) / Gd₂₀(Fe₆₀Co₄₀)₈₀(Film thickness 50 nm) /
Al₅₀Cu₅₀(Film thickness 25 nm) / Si substrate film structure
Is a TMR element having Where 0 <X <100
It

FIG. 3 is a graph showing changes in the magnetoresistance change rate with respect to the Co composition (X atomic%) of the high spin polarizability magnetic layers 53 and 55 in the magnetoresistance effect film shown in FIG. Here, the Co composition means the ratio of Co to Fe and Co in the high spin polarization magnetic layer. As can be seen from this figure, the rate of change in magnetoresistance depends on the Co composition of the high spin polarizability magnetic layer, and is 15 atom% or more and 80% or more.
It is possible to achieve a magnetoresistance change rate of 40% within the range of atomic% or less, which is preferable. Further, it is more preferable that the content is in the range of 30 atomic% or more and 60 atomic% or less so that a large magnetoresistance change rate can be stably obtained.

By using the magnetoresistive film of this embodiment as a memory element, a memory (MRAM) having a large read signal can be created. In such a memory, a method of using a magnetic field generated by passing a current through a conducting wire (writing line) is generally used for recording information. For example, from a plurality of memory elements (magnetoresistive film) arranged in a matrix, it is necessary to apply a magnetic field so as to invert only the magnetization of a desired memory element. A conducting wire is arranged between the two, and a current is passed through the conducting wire to generate a magnetic field perpendicular to the film surface of the memory element. At that time, if a current is applied to the four conductors around the memory element (selected memory element) to be recorded so that a magnetic field is applied in the same direction to the memory element, the desired memory element is selected. The largest magnetic field is applied only to the memory element, and recording is performed only to this memory element.

The above recording method is a method of using only the magnetic field in the direction perpendicular to the film surface of the memory element, but it can also be selectively applied by applying a magnetic field in the film surface direction to the memory element. It is possible to record. For example, the conductive wire is arranged between the memory elements, and the 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 so as to be orthogonal to each other when viewed from directly above. Among the conductors arranged in this way, an electric current is applied to the conductor right next to the desired memory element to be recorded to apply a magnetic field in the direction perpendicular to the film surface of the memory element, and An electric current is also applied to the conducting wire arranged in the lower part to apply a magnetic field in the in-plane 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 by using the bit line provided for reading information from the memory element, It is possible to omit the conductor for generating the magnetic field.

[0029]

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

(Example-1) FIG. 2 shows a cross section of the magnetoresistive film produced in Example-1. A Si (silicon) substrate 100 is used as a substrate for forming a magnetoresistive film, and a Gd film having a thickness of 40 nm is formed as a first magnetic layer 111, which is a ferrimagnetic layer, on the Si substrate 100.
₂₄ (Fe ₆₀ Co ₄₀ ) ₇₆ film, Fe ₆₀ Co ₄₀ film with a thickness of 1 nm as the first high spin polarizability magnetic layer 112, non-magnetic layer 1
15, an Al ₂ O ₃ film having a thickness of 1.5 nm, Fe ₆₀ Co ₄₀ as the second high spin polarization magnetic layer 113, and Tb _{24 having} a thickness of 30 nm as the second magnetic layer 114 which is a ferrimagnetic layer. (Fe ₆₀ Co ₄₀ ) ₇₆ film, 2n as protective film 116
m Pt film was sequentially formed by sputtering. However, the second high spin polarizability magnetic layer 113 has a height of about 1.5 nm.
In a hemispherical shape, the Al ₂ O ₃ film, which is the non-magnetic layer 115, is uniformly formed in an island shape. Protective film 116
The (Pt film) is effective in preventing corrosion such as oxidation of the magnetic film. Here, the first magnetic layer 111 of Gd ₂₄ (Fe ₆₀ C
o ₄₀ ) ₇₆ film and the second magnetic layer 114 of Tb ₂₄ (Fe ₆₀
The Co ₄₀ ) ₇₆ films are both predominantly rare earth metal sublattice magnetization dominant.

Next, a 1 μm square resist film was formed on the obtained multi-layer film, and the magnetoresistive film not covered with the resist was removed by dry etching. After the etching, an Al ₂ O ₃ film having a film thickness of 80 nm is formed, the resist and the Al ₂ O ₃ film on the resist are removed, and the upper electrode and the first magnetic layer 111 (Gd ₂₄ (Fe ₆₀ Co ₄₀ )
An insulating film 121 for electrical insulation between the insulating film 121 and the film ₇₆ ) was formed. Then, the upper electrode 122 is formed by the lift-off method.
Was made of an Al film, and a part of the Al ₂ O ₃ film not covered by the upper electrode was removed to provide an electrode pad for connecting a measurement circuit.

In the magnetoresistive film thus obtained,
In contrast, a magnetic field of 2 MA / m is applied in the direction perpendicular to the film surface,
Magnetic layer 114 (Tb_{twenty four}(Fe₆₀Co₄₀)₇₆Film) magnetization
Was magnetized in the direction of the applied magnetic field. In addition, 1 on the substrate
cm square Tb_{twenty four}(Fe₆₀Co ₄₀)₇₆Separately formed film
As a result, the coercive force of this film was as large as 0.8 MA / m.
Value and the coercive force of the obtained magnetoresistive film is similar.
It is expected to show a large value.

For this magnetoresistive film, the upper electrode 12
2 and the lower electrode (Si substrate 100), a constant current power source is connected to the first magnetic layer 111 (Gd ₂₄ (Fe ₆₀ Co ₄₀ ).
₇₆ film) and the second magnetic layer 114 (Tb ₂₄ (Fe ₆₀ Co ₄₀ ).
_A constant current was passed so that electrons tunneled through the non-magnetic layer 115 (Al ₂ O ₃ film) between the ₇₆ films). In this state, a magnetic field was applied in a direction perpendicular to the film surface of the magnetoresistive effect film, and the magnitude and direction of the magnetic field were changed to measure the voltage change (magnetoresistive curve) of the magnetoresistive effect film. According to this measurement result, the rate of change in magnetoresistance was about 55%.

(Example-2) After forming a transistor, a wiring layer and the like on a Si substrate (Si wafer), a magnetoresistive film having the film structure used in Example-1 was formed, and further three lines were formed. A memory cell array was constructed by processing into three rows of nine memory elements. The 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 structure 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.

Further, 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. 6 schematically shows the three-dimensional structure of one peripheral portion of such a memory element. here,
The vicinity of the magnetoresistive film 105 in FIGS. 3 and 4 is shown. For example, two n-type diffusion regions 162 and 163 are formed on a p-type Si substrate 161, and a word line (gate electrode) 342 is interposed between these n-type diffusion regions 162 and 163.
Are formed. N via contact plug 351
The ground line 356 is connected to the type diffusion region 162, and the magnetoresistive effect 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 further includes
It is connected to the bit line 332 via the contact plug 355. Write lines 312 and 313 for generating a magnetic field are arranged beside the magnetoresistive film 105.

(Comparative Example) A magnetoresistive effect film was prepared using a ferrimagnetic layer made of only a rare earth metal and Fe (not containing Co).

The first magnetic layer 111 is formed on the Si substrate 100.
As a Gd with a film thickness of 40 nm_{twenty four}Fe ₇₆Membrane, the first high spin
Fe having a film thickness of 1 nm as the magnetic polarization layer 112.₆₀Co₄₀
Al film with a thickness of 1.5 nm as the non-magnetic layer 115₂O₃
Film, Fe as the second high spin polarizability magnetic layer 113₆₀C
o₄₀, Tb having a film thickness of 30 nm as the second magnetic layer 114
_{twenty four}Fe₇₆A Pt film having a thickness of 2 nm is used as the film and the protective film 116.
The layers were sequentially formed by sputtering. However, the second high spin
The polarizability magnetic layer 113 has a height of about 1.
Al in the form of a 5 nm hemisphere₂O₃Uniformly shaped like islands on the membrane surface
I made it. Here, the first magnetic layer 111 (Gd_{twenty four}Fe
₇₆Film) and the second magnetic layer 114 (Tb_{twenty four}Fe₇₆film)
Are ferrimagnets, both of which have a dominant rare earth metal sublattice magnetization.
It is a sex layer. Next, a 1 μm square
After forming a resist film, dry etching
The portion of the magnetoresistive film not covered with the mask was removed.
After etching, Al with a thickness of 80 nm₂O₃Deposit a film,
Furthermore, the resist and Al on top of it₂O₃Remove the membrane,
The upper electrode and the first magnetic layer 111 (Gd_{twenty four}Fe₇₆Membrane)
An insulating film 121 for electrical insulation between the layers was formed. So
After that, the upper electrode 122 is formed into an Al film by the lift-off method.
Of the part not covered with the upper electrode 122
l₂O₃Electrode for removing measurement film and connecting measurement circuit
It was Pat.

A magnetic field of 2 MA / m was applied to the magnetoresistive film thus obtained in the direction perpendicular to the film surface to produce a second magnetic field.
The magnetic layer 114 (Tb ₂₄ Fe ₇₆ film) was magnetized by directing the magnetization in the direction of the applied magnetic field. In addition, 1 cm square Tb on the substrate
_{When a 24} Fe ₇₆ film was separately formed, the coercive force of this film showed a large value of 0.6 MA / m, and the coercive force of the obtained magnetoresistive film was also expected to show a similar large value. It

For this magnetoresistive film, the upper electrode 12
2 and the lower electrode (Si substrate 100), a constant current power source is connected to the first magnetic layer 111 (Gd ₂₄ Fe ₇₆ film) and the second magnetic layer 111.
Non-magnetic layer 11 between the magnetic layers 114 (Tb ₂₄ Fe ₇₆ film) of
A constant current was applied so that electrons tunneled through 5 (Al ₂ O ₃ film). In this state, a magnetic field was applied in a direction perpendicular to the film surface of the magnetoresistive effect film, and the magnitude and direction of the magnetic field were changed to measure the voltage change (magnetoresistive curve) of the magnetoresistive effect film. According to this measurement result, the magneto-resistance change rate is about 4
It was 6%.

[0044]

As described above, according to the present invention, in a magnetoresistive effect film using a ferrimagnetic layer containing a rare earth metal and a transition metal as main components, rare earth metals, Fe and Co are mainly used as the ferrimagnetic layer. By using the component, a large magnetoresistance change rate can be achieved.

[Brief description of drawings]

FIG. 1 is a magnetoresistive film having a structure in which a nonmagnetic layer is sandwiched by two ferrimagnetic layers, and in the ferrimagnetic layer, the Co composition for Fe and Co and the magnetoresistance change rate (M
It is a graph which shows the relationship with R ratio.

FIG. 2 is a sectional view schematically showing a magnetoresistive effect film according to an embodiment of the present invention.

3 is a graph showing the relationship between the Co composition for Fe and Co and the magnetoresistance change rate (MR ratio) of the high spin polarizability magnetic layer in the magnetoresistive film shown in FIG.

FIG. 4 is a schematic cross-sectional view of a magnetoresistive film of Example-1.

FIG. 5 is a circuit diagram illustrating a memory configuration according to a second exemplary embodiment.

FIG. 6 is a sectional view schematically showing one memory cell of a memory using a magnetoresistive effect film in Example-2.

7A is a sectional view schematically showing a state where the magnetizations of the magnetoresistive effect film are parallel, and FIG. 7B is a sectional view schematically showing a state where the magnetizations of the magnetoresistive effect film are antiparallel. .

FIG. 8 is a diagram for explaining a recording / reproducing principle in a conventional magnetoresistive film using an in-plane magnetized film, and (a) and (c) are magnetizations when reading recorded information “1”. Sectional views schematically showing the state of (b) and (d) are
FIG. 7 is a cross-sectional view schematically showing a magnetization state when reading recorded information “0”.

FIG. 9 is a diagram for explaining a recording / reproducing principle in a magnetoresistive effect film using a perpendicular magnetization film, and FIGS.
Is a cross-sectional view schematically showing a magnetization state when reading recorded information “1”, and (b) and (d) are schematic sectional views showing a magnetization state when reading recorded information “0”. FIG.

[Explanation of symbols]

11, 21 Detection layer 12, 22, 54, 115 Nonmagnetic layer 13, 23 Memory layer 50, 100 Si substrate 51 Conductive layer 52, 56 Ferrimagnetic layer 53, 55, 112, 113 High spin polarization magnetic layer 57, 116 Protective film 100 Si substrate 101-109 Magnetoresistive film 111, 114 Magnetic layer 112, 113 High spin polarization magnetic substance 121, 123 Insulating film 122 Upper electrode 150 Fixed resistance 161 p-type Si substrate 162, 163 n-type diffusion region 211 ~ 218, 221-224, 231-242, 2
51 transistor 300 wiring 311 to 314 write line 331 to 333 bit line 341 to 343 word line (gate electrode) 351 to 355, 357 contact plug 356 ground line 358 local wiring 411, 412 power supply 500 sense amplifier

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 10/32 G01R 33/06 R H01L 27/105 H01L 27/10 447 F term (reference) 2G017 AA10 AD54 5D034 BA03 BA04 CA08 5E049 AA01 AA04 5F083 FZ10 GA30 JA32 JA36 LA03 LA18 MA06 MA16 MA19 PR00 PR03 PR22

Claims (16)

[Claims] 1. A magnetoresistive effect film having first and second magnetic layers and a non-magnetic layer sandwiched between the first and second magnetic layers, wherein: At least one is a ferrimagnetic layer containing a rare earth metal, Fe, and Co as main components, and Fe and C are provided between the nonmagnetic layer and the ferrimagnetic layer.
A magnetoresistive film comprising a high spin polarizability magnetic layer made of o and exchange-coupled with the ferrimagnetic layer. 2. The magnetoresistive film according to claim 1, wherein a composition of Co with respect to Fe and Co in the ferrimagnetic layer is in a range of 30 atomic% or more and 70 atomic% or less. 3. Fe in the high spin polarizability magnetic layer
And the composition of Co relative to Co is 15 atomic% or more and 80 atomic% or more.
The magnetoresistive film according to claim 1, which is within the following range. 4. Fe in the high spin polarizability magnetic layer
And the composition of Co with respect to Co is 30 atomic% or more and 60 atomic% or more.
The magnetoresistive film according to claim 1, which is within the following range. 5. The magnetoresistive film according to claim 1, wherein the rare earth metal comprises at least one element selected from the group consisting of Gd, Dy, and Tb. 6. The magnetoresistive film according to claim 1, wherein the nonmagnetic layer is an electrical insulator. 7. The magnetoresistive film according to claim 6, which exhibits a spin tunneling effect when a current is passed in a direction perpendicular to the film surface. 8. Each of the first and second magnetic layers is the ferrimagnetic layer, which is between the first magnetic layer and the non-magnetic layer and between the second magnetic layer and the non-magnetic layer. The high spin polarizability magnetic layers are formed between the layers,
The magnetoresistive effect film according to any one of claims 1 to 7. 9. The first magnetic layer and the second magnetic layer cause magnetization reversal due to magnetic fields of different magnitudes, and the relative magnetization of the first magnetic layer and the second magnetic layer is relatively large. The magnetic layer whose magnetization is inverted by a very small magnetic field contains Gd as a rare earth metal as a main component, and the first magnetic layer and the second magnetic layer
9. The magnetoresistive effect film according to claim 8, wherein the magnetic layer whose magnetization is reversed by a relatively large magnetic field contains at least one of Tb and Dy as a main component as a rare earth metal. 10. The magnetoresistive effect film according to claim 1, wherein the ferrimagnetic layer is a perpendicular magnetization film. 11. A recording means for arranging a plurality of the magnetoresistive film according to claim 1 as a memory element and recording information on the magnetoresistive film, and the magnetoresistive film. And a reading means for reading the information recorded in the memory. 12. The memory according to claim 11, wherein the recording means is means for applying a magnetic field having a magnitude such that the magnetization of the magnetoresistive effect film can be reversed. 13. The memory according to claim 12, wherein the applying unit has a conductive wire, and the magnetic field is generated by passing an electric current through the conductive wire. 14. At least two magnetic field generation sources for applying magnetic fields in different directions to one memory element.
The memory according to claim 12 or 13, which has one or more memory cells and selectively records from among the plurality of memory elements by applying the plurality of magnetic fields to the selected memory element. 15. Magnetic fields in two different directions are applied to one memory element, one magnetic field is directed in a direction perpendicular to the film surface of the memory element to be recorded, and the other magnetic field is recorded in the memory element to be recorded. The memory according to claim 12 or 13, which is directed in the in-plane direction of the film and selectively records from a plurality of memory elements by applying a plurality of two magnetic fields to the selected memory element. . 16. The memory according to claim 15, wherein the magnetic field in the in-plane direction is generated by passing a current through a bit line arranged above a memory element to be recorded.