JP2002026417A - Spin injection three-terminal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-terminal element which uses an electrode of a ferromagnetic metal material. SOLUTION: A drain electrode 107 and a source electrode 106 comprising an alloy of nickel(Ni) and iron (Fe) are formed on a channel layer 102 through separation layers 104 and 105 comprising aluminum(Al).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin-injection three-terminal device in which a source / drain electrode is made of a ferromagnetic metal material which is a ferromagnetic material.

[0002]

2. Description of the Related Art A conventional general semiconductor device includes:
Only the charge of electrons has been used. However,
Electrons have a spin degree of freedom together with electric charges, and no semiconductor device has so far actively utilized the spin properties of electrons. In recent years, giant magnetoresistance (GMR) in a magnetic / non-magnetic metal laminated structure, (Ref. 1: Giant magnetoresistance effect of Physics Selected Papers VII, Teruya Shinjo, Yoshimichi Maekawa responsible editor), and large in ferromagnetic tunnel junction (TMR) With the discovery of the magnetoresistance ratio (Reference 2: T. Miyaz
aki, and N. Tezuka, J. Magn. Magn. Mater. 139 L231
(1995)), a non-volatile magnetic memory device (MRAM) using the magnetoresistance effect has attracted attention.

In a conventional spin injection device utilizing the above-described magnetoresistance change, in a device using a ferromagnetic metal / semiconductor structure, spin injection efficiency is low due to spin scattering caused by disturbance in potential at the ferromagnetic metal / semiconductor interface. And the change in magnetoresistance was as small as about 1% or less (Reference 3: J. Nitta, and H. Tak)
ayanagi, The proceedings of the 24th International
Conference on the Physics of Semiconductors, (199
9), Reference 4: S. Gardelis et al. Phys. Rev. B60 7764
(1999)). Note that "spin injection" means "injection while controlling the spin state of electrons", and hereinafter this is abbreviated as "spin injection".

Further, in a device using a diluted magnetic semiconductor / semiconductor structure, a very large spin injection efficiency of about 90% can be obtained by epitaxially growing a diluted magnetic semiconductor as a spin polarization source on a semiconductor. (Reference 5: R. Fiederling et al. Nature 402 78
7 (1999), Reference 6: Y. Ohno et al. Nature 402 790 (19
99)). However, since the Curie temperature of the diluted magnetic semiconductor is about 100K, there is a problem that the above-mentioned element cannot be operated at room temperature.

In addition, a magnetic / non-magnetic metal laminated structure (G
In a magnetic tunnel junction (MR, Reference 1) or a ferromagnetic tunnel junction (TMR, Reference 2), a large magnetoresistance ratio and room-temperature operation are possible. However, in GMR and TMR, a three-terminal operation in which a resistance change is controlled by a gate voltage or the like cannot be configured, and specific applications are limited to a memory or a passive element such as a sensor.

[0006]

When constructing a logic circuit or an integrated memory, a three-terminal element having an amplifying function is required. Since the GMR element and the TMR element are basically two-terminal elements, in order to configure these elements as an integrated memory device, another pass transistor for selecting one element to be a memory cell is required. Becomes Therefore, in order to form an MRAM, it is necessary to form a plurality of GMR elements and TMR elements as memory cells and to form pass transistors that are three-terminal elements. Similarly, when configuring a memory in which logic circuits and the like are integrated, a three-terminal element having an amplifying function is required.

In order to realize these configurations, a conventional transistor is formed, and a GMR element and a TMR element are formed.
Since the MR element is formed monolithically, there is a problem that the process becomes complicated and high integration is hindered. On the other hand, if there is a spin-injection three-terminal device that has a non-volatile memory function such as GMR and TMR, can operate at room temperature, and can control the gate, a complicated process is not required and the integration is further improved. It becomes possible to form a semiconductor device such as a memory device that has been subjected to the process.

The present invention has been made to solve the above problems, and has as its object to provide a three-terminal element using an electrode made of a ferromagnetic metal material which is a ferromagnetic material. .

[0009]

A spin-injection three-terminal device according to the present invention comprises: a channel layer formed of a compound semiconductor on a substrate formed of a compound semiconductor; First and second isolation layers made of aluminum formed by sputtering, a source electrode and a drain electrode made of a ferromagnetic metal formed on the first and second isolation layers, and a channel formed in a channel layer. And a gate electrode for controlling the state. According to the present invention, electrons whose spin states are controlled from the source electrode and the drain electrode are diffused through the separation layer and injected into the channel layer.

Further, the spin-injection three-terminal element of the present invention comprises:
A channel layer made of a compound semiconductor formed on a substrate made of a compound semiconductor and having a channel formed thereon, and first and second separation layers made of an oxide of aluminum formed on the channel layer so as to be separated from each other , A source electrode and a drain electrode made of a ferromagnetic metal formed on the first and second separation layers, and a gate electrode for controlling a state of a channel formed in a channel layer. According to the present invention, electrons whose spin states are controlled from the source electrode and the drain electrode tunnel through the separation layer and reach the channel layer. In the above invention, the first
The second isolation layer is formed to be thinner than the thickness through which the tunnel current flows.

Further, the spin-injection three-terminal element of the present invention
A channel layer formed of a compound semiconductor, in which a channel is formed over a substrate formed of a compound semiconductor, and a stacked structure of an aluminum film and an aluminum oxide film formed separately from each other on the channel layer. A first and a second separation layer, a source electrode and a drain electrode made of a ferromagnetic metal formed on the first and the second separation layer, and a gate electrode for controlling a state of a channel formed in the channel layer. It is provided. According to the invention,
The electrons whose spin states are controlled from the source electrode and the drain electrode diffuse and tunnel through the separation layer and reach the channel layer. In the above invention, the aluminum oxide film forming the first and second separation layers is formed to be thinner than a thickness through which a tunnel current flows.

In any one of the above-mentioned inventions, the channel layer is made of an n-type compound semiconductor, and a layer made of a p-type compound semiconductor is provided below the channel layer.
The gate electrode is formed in contact with a layer made of a p-type compound semiconductor. In this structure, a barrier layer may be provided between the p-type compound semiconductor layer and the n-type compound semiconductor layer. In any one of the above-mentioned inventions, the semiconductor device further includes an electron supply layer formed of an n-type semiconductor layer formed on the channel layer, and the channel layer includes a two-dimensional electron cloud formed by electrons supplied from the electron supply layer. A channel is formed, and the gate electrode is formed on the electron supply layer. Note that an alloy of nickel and iron may be used as the ferromagnetic metal.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a perspective view schematically showing a configuration of a spin injection three-terminal device according to a first embodiment of the present invention. The configuration of the spin-injection three-terminal element according to the present embodiment will be described. First, a carrier concentration of 1 × 10 ¹⁸ cm is formed on a semiconductor substrate 101 made of p-type InAs.
Film thickness of n− ³ InAs of ^{-3 where} a channel is formed
A channel layer 102 of about 0 nm is formed. The semiconductor substrate 101 has a carrier concentration of 5 × 10 ¹⁷ cm ⁻³ . Further, a channel layer 102 is formed on the semiconductor substrate 101.
And a gate electrode 103 formed separately from the gate electrode 103.

On the channel layer 102, separation layers 104 and 105 made of aluminum (Al) are interposed.
A source electrode 106 and a drain electrode 107 made of an alloy of nickel (Ni) and iron (Fe) are formed. Each of the electrodes is formed in a strip shape extending from the near side of the paper of FIG. The gate electrode is formed on the semiconductor substrate 10
It may be formed on one back surface. Alternatively, a p-type InAs layer having a carrier concentration of 5 × 10 ¹⁷ cm ⁻³ may be formed on an InAs substrate by crystal growth to a thickness of 100 nm or more, and may be used instead of the semiconductor substrate 101.

Here, the configuration of the spin three-terminal device described above will be considered. According to a spin injection experiment into an aluminum layer from an electrode made of a ferromagnetic metal NiFe by Mark Johnson et al., Aluminum has a very long spin diffusion length.
It has been reported that the electron spin injected from the electrode is diffused over 0.5 mm in the aluminum layer (Reference 7: M Johnson, and RH Silsbee, Phys.
Rev. Lett. 55 1790 (1985)).

If a ferromagnetic metal thin film is formed directly on a semiconductor channel containing As, such as GaAs or InAs, a diamagnetic compound such as FeAs is easily formed at the interface, which hinders spin injection. Alternatively, when a compound of Fe ₃ Ga ₂ -xAs _x is formed at the interface, it is reported that the magnetic susceptibility is reduced to about 1/2 with respect to bulk Fe, and it is reported that spin injection is greatly inhibited. (Reference 8: A. Filipe, A. Schuhl, and P. Galtier,
Appl. Phys. Lett. 70 129 (1997)).

On the other hand, "R. Taboriski"
Et al. Formed an aluminum thin film on n-GaAs epitaxially grown without breaking vacuum in the same chamber and formed a very good semiconductor / metal interface with a contact resistance of 0.5 × 10 ⁻¹⁰ Ωm ^2. (Reference 9: R. Taboryski et al. Appl. Phys. Lett. 69
656 (1996)). In addition, the Al / n thus formed
It has also been reported that in a -GaAs / Al junction, a superconducting current flows through n-GaAs at a low temperature below the superconducting critical temperature of aluminum (Reference 10: R. Taboryski et a).
l. SuperlatticeMicrostruct. 25 829 (1999), J. Kutc
hinsky et al. Phys. Rev. Lett. 83 4856 (1999)).

As described above, first, an aluminum thin film can be formed on a semiconductor layer such as GaAs with low contact resistance. In addition, if a ferromagnetic metal such as NiFe is formed on an aluminum film as in the configuration shown in FIG. 1, an antiferromagnetic material such as FeAs which greatly inhibits spin injection at the interface between the ferromagnetic metal and the aluminum film. No magnetic compound is formed, and a large spin injection efficiency can be obtained with respect to the underlying semiconductor layer even at room temperature.

Aluminum has an extremely long spin diffusion length, and if the thickness of aluminum is set to 100 nm or less,
The decay of the injected spin is negligible. From this structure, it is easy to fabricate the spin injection device of FIG. 1 or the ferromagnetic electrode / aluminum / semiconductor / aluminum / ferromagnetic structure. In the case of a ferromagnetic metal source / drain electrode formed through an aluminum film, since the channel portion is a semiconductor, the state of the channel can be controlled by adding a gate electrode as described below. Three-terminal operation with a functional memory function becomes possible. This spin injection three-terminal element can be applied not only as a memory cell array but also as a logic gate, as described below.

In the configuration of the spin-injection three-terminal element shown in FIG. 1, a gate voltage is applied between the source electrode 106 and the gate electrode or between the drain electrode 107 and the gate electrode 103, thereby forming the channel layer 102 and the semiconductor. The extension of the depletion layer between the substrate 101 and the substrate 101 can be controlled, whereby the "ON" and "OFF" of the channel can be controlled. In the case of the configuration of FIG. 1 described above, the channel of the channel layer 102 is depleted at a gate voltage of about −1 V, and “OFF”
State (> 100 MΩ).

When the magnetization directions of the source electrode 106 and the drain electrode 107 made of a ferromagnetic material are made parallel when the channel is in the “ON” state, the source
The resistance between the drains becomes a low resistance (low) state. On the other hand, when the magnetization directions of the source electrode 106 and the drain electrode 107 are made antiparallel when the channel is in the “ON” state, the resistance between the source and the drain becomes a high resistance (high) state. The magnetization of the source electrode 106 and the drain electrode 107 made of a ferromagnetic material is stable, and the respective magnetization states are maintained even when the power is turned off. Therefore, the spin injection three-terminal device of the present embodiment has a nonvolatile memory function.

When the present spin injection three-terminal device is used as an MRAM, the source electrode 106 and the drain electrode 1
07 may be in a state where the reversal magnetic field is different. For example, the source electrode 106 is made of a material having a large reversal magnetic field so that the magnetization direction can be fixed.
A material having an inversion magnetic field that is small enough to cause magnetization reversal by a local magnetic field generated by a write or read line may be used for 7. In the simplest case, when the source electrode and the drain electrode are made of the same ferromagnetic material and have different electrode widths, the source and drain electrodes have different reversal magnetic fields.

According to "Kryder", when an electrode is formed from an alloy of Ni and Fe, the reversal magnetic field increases sharply when the electrode width is 10 μm or less, and when the electrode width is 2 μm, the reversal magnetic field increases as compared with an electrode having a width of 10 μm. It is reported that the reversal magnetic field increases about 10 times (Reference 12: MH Kryder; et a
l. IEEE Mag-16 99 (1980)). If the width of the source electrode and the width of the drain electrode are designed to be different from each other in the element structure shown in FIG. 1, it can be applied as one memory cell. FIG. 2 is an equivalent circuit diagram when the width of the source electrode and the width of the drain electrode are designed to be different. The drain electrode has a small electrode width,
This magnetization direction can be changed to a local magnetic field by a current flowing through the control line.

The spin injection three-terminal element shown by the equivalent circuit in FIG. 2 can take three different states. When the signal to the gate G is ON, the semiconductor channel C is in an open state. In this state, the resistance of the semiconductor channel C is set to “hi” depending on the magnetization directions of the source electrode and the drain electrode.
gh ”state and“ low ”state. These result in two states. Assuming that a typical semiconductor channel C has a resistance of about 100Ω and a source electrode and a drain electrode are formed from an alloy of Ni and Fe and the spin polarization of each electrode is 40%, the change in resistance of the semiconductor channel C is about ± 15. % Is expected.

Therefore, the resistance value of the semiconductor channel C can be changed to 115Ω in the “high” state and to 85Ω in the “low” state. As a third state, the signal to the gate G is “O
FF ”. In this state, the extremely high resistance state where the semiconductor channel C is closed is> 100 MΩ, and the state between the source and the drain is “OFF” irrespective of the magnetization direction of the source electrode and the drain electrode.

By using the equivalent circuit of FIG. 2, a memory cell array as shown in FIG. 3 can be constructed. In reading from this memory cell array, first, only the gate G of the memory cell to be selected is turned on. this is,
It can be accessed by a decoder circuit of a normal semiconductor memory. For example, if V _B is 1 V and the load resistance _RL is 100
If Ω is selected, an output voltage of 0.54 V is obtained from V _OUT if the cell selected by the “ON” state is in the “low” state by the magnetization direction of the drain electrode G.

If the drain electrode G is in a "high" state depending on the magnetization direction, an output voltage of 0.465 V can be obtained from V _OUT . These output voltages can be converted into "ON" and "OFF" signals by a sense circuit having an amplifying action of the next stage (not shown). The spin-injection three-terminal element shown in FIG. 1 also has a function as a normal field-effect transistor (FET),
It is also possible to constitute a circuit for amplifying output voltages from these cells together with the memory cell array using only the elements having the configuration shown in FIG. Note that the magnetization direction of the drain electrode G can be changed by causing a current to flow through the write line W to generate a magnetic field.

Next, a method for manufacturing the spin-injection three-terminal device according to the present embodiment will be described. First, as shown in FIG. 4, n-type semiconductor substrate 101 made of p-type InAs is
The channel layer 102 is grown by crystal growth of InAs.
To form For this crystal growth, for example, a molecular beam epitaxial growth (MBE) apparatus may be used. Next, aluminum is deposited over the channel layer 102 to form an aluminum film 401.

In the formation of the aluminum film 401, aluminum is deposited while maintaining a vacuum state in the same chamber of the MBE apparatus in which the channel layer 102 is formed. At this time, it is better to lower the substrate temperature to 30 ° C. or lower so that an AlAs film serving as a barrier film is not formed at the interface with the channel layer 102. By these, the channel layer 102 and the aluminum film 4
No Schottky barrier is formed at the interface with 01,
A flat interface can be formed at the atomic layer level.

After the aluminum film 401 is formed, the substrate is taken out of the chamber, and a stripe-shaped stencil pattern 501 having a predetermined width is formed on the aluminum film 401 by a known photolithography technique as shown in FIG. Form. Stencil pattern 501
For example, an electron beam resist processed by electron beam lithography may be used, or a photoresist processed by photolithography may be used.

Next, as shown in FIG. 6, Ni film is formed on the aluminum film 401 on which the stencil pattern 501 is formed.
A ferromagnetic metal film 601 made of an alloy of Fe and Fe is formed.
This ferromagnetic metal film 601 may be formed by an evaporation method or a sputtering method, and need not be epitaxially grown. According to the analysis of the ferromagnetic / nonmagnetic laminated structure such as GMR, it is known that it is not necessary to form a flat interface at the atomic layer level at the NiFe / Al interface. However, when the ferromagnetic metal film 601 is formed, it is important to remove the natural oxide film on the surface of the aluminum film 401 by cleaning with argon plasma.

Next, the stencil pattern 501 of the ferromagnetic metal film 601 is selectively removed by, for example, dissolving the stencil pattern 501 in an organic solvent.
1 is lifted off, and the source electrode 106 is formed on the aluminum film 401 as shown in FIG.
And a drain electrode 107 are formed. Finally, using the source electrode 106 and the drain electrode 107 as masks, the aluminum film 501 is removed in a self-aligned manner, and separation layers 104 and 105 are formed as shown in FIG. The selective etching of the aluminum film 501 is performed by dissolving only aluminum in a phosphoric acid aqueous solution (H ₃ PO ₄ : H ₂ O =
1: 2) may be performed by wet processing using an etching solution.

Here, the formation of the aluminum film will be considered. In a molecular beam epitaxy apparatus (MBE) for forming a group III-V semiconductor film, GaAs /
Aluminum is an essential molecular beam source as represented by AlGaAs or InGaAs / InAlAs. Therefore, using a conventional MBE device,
After epitaxially growing a channel layer such as GaAs or InGaAs or InAs, it is extremely easy to form an aluminum thin film on a steep and flat semiconductor channel at the atomic layer level without breaking vacuum.

When a ferromagnetic metal film is formed successively after the formation of the aluminum thin film to form the structure of FIG. 1, a molecular beam source of the ferromagnetic metal is placed in the same MBE chamber. It will be prepared with a molecular beam source for semiconductors. However, when the same MBE apparatus is used for both the formation of the semiconductor layer and the formation of the ferromagnetic metal film, the ferromagnetic metal may be mixed as an impurity in the formed semiconductor layer, causing deterioration of the semiconductor epitaxial film. There is a risk.

As a means for solving this, it is conceivable to prepare a new chamber for forming a ferromagnetic thin film and to separate the semiconductor epitaxial apparatus from the ferromagnetic thin film forming apparatus. By such a vacuum partial process, it is possible to form a steep and clean semiconductor / ferromagnetic interface. However, in order to realize the above-described vacuum integrated process, large-scale equipment and cost are required. In contrast, according to the above-described manufacturing method of the present embodiment, the ferromagnetic metal film 601 (FIG. 6) may be formed on the aluminum film 401 by a vapor deposition method or a sputtering method. Therefore, a large-scale device is not required, and an element can be formed without increasing cost.

When an aluminum film serving as a separation layer is formed on a compound semiconductor layer, a two atomic layer of silicon is formed in advance on the surface of the compound semiconductor layer, and an aluminum film is formed thereon. The contact resistance of the aluminum film can be further reduced. "France
have formed a biatomic layer of Si used as a dopant at the interface between aluminum and InGaAs, and obtained Al / InGa from Andreev reflection measurements.
It has been reported that the contact of As is improved (Reference 11: S. De Franceschi et al. Appl. Phys. Lett.
73 3890 (1998)).

The spin-injection three-terminal element shown in FIG. 1 is, as shown in FIGS.
The width of the drain electrode 107 is made smaller and the two input lines 901 and 902 extending in a direction perpendicular to the extending direction of these electrodes are provided.
D "and" OR "logic circuits can be realized. First, "AN
When the “D” gate circuit is configured, the local magnetic field Ha generated by the input line 901 and the local magnetic field Hb generated by the input line 902 become larger than the reversal magnetic field Hc of the drain electrode 107. What is necessary is just to design an inductance. However, each of Ha and Hb is designed to be smaller than the reversal magnetic field Hc (Ha + Hb>Hc> Ha, H
b).

More specifically, the magnitude of the reversal magnetic field of the drain electrode 107 is about 5 to 100 (Gauss).
= I _in / 2πr (where r is the distance from the input line) The strength of the magnetic field generated by the input line is r = 5 μ
m, I _in = 0.25 μA and about 50 Gauss. When the element in FIG. 9 is an “AND” gate, the signal “0” on the input lines 901 and 902
Table 1 below shows the relationship between the combination of “1” and the element output and the element output.
Shown in

[Table 1] Input line 901 0 0 1 1 Input line 902 0 1 0 1 Element output low low low high

In order to realize an "OR" circuit using the spin injection three-terminal element shown in FIG. 1, a drain magnetic field is formed by a local magnetic field formed by a current flowing through either the input line 901 or the input line 902. The inductance of each input line may be designed so that the magnetization reversal occurs at 107. That is, Ha, Hb> Hc may be satisfied. Similarly, various circuits can be designed. The element shown in FIG.
Input line 901 and input line 902 when an “R” gate is used.
Table 2 below shows the relationship between the combination of "0" and "1" of the signal and the element output.

[Table 2] Input line 901 0 0 1 1 Input line 902 0 1 0 1 Element output low high high high

In the above embodiment, InAs is used for a semiconductor substrate or the like. However, the present invention is not limited to this, and GaAs, InGaAs or InSb may be used. Further, the carrier concentration is set to 1 × 10 ¹⁸ cm ⁻³ and the n-type In
As was used, but is not limited to this.
Non-doped InAs, GaAs, InGaAs or InSb may be used.

Second Embodiment Next, another embodiment of the present invention will be described. As shown in FIG. 11, the structure of the source / drain electrodes made of a ferromagnetic metal of the present invention can be applied to a high mobility transistor (HEMT).
The HEMT according to the present embodiment will be described. First, a channel layer 1102 made of non-doped GaAs is formed on a substrate made of semi-insulating GaAs (not shown), and a lower buffer made of non-doped AlGaAs is formed in a predetermined region above this. Layer 1103, electron supply layer made of n-type AlGaAs 1104, undoped AlGaAs
The upper buffer layer 1105 is laminated.

Further, on both sides of the above-mentioned laminated structure on the channel layer 1102, an alloy of Ni and Fe, which are ferromagnetic metals, is formed via separation layers 1106 and 1107 made of aluminum so as to sandwich the laminated structure. Source electrode 110
8, a drain electrode 1109 is formed. In addition, a gate electrode 111 is formed on the upper buffer layer 1105.
0 is formed. By the way, the laminated structure is formed by sequentially laminating non-doped AlGaAs, n-type AlGaAs, and non-doped AlGaAs on the channel layer 1102, and processing these laminated films by a known photolithography technique. Therefore, at the time of forming this laminated structure, the channel layers 1 on both sides of the laminated structure are formed.
The surface 102 is rough. Therefore, the channel layer 1 on which the separation layers 1106 and 1107 are formed
It is preferable to form the separation layers 1106 and 1107 by removing the target region on the substrate 02 once by etching, growing GaAs again thereon, and then forming aluminum.

<Embodiment 3> Next, another embodiment of the present invention will be described. As shown in FIGS. 12 and 13, the structure of the source / drain electrodes made of a ferromagnetic metal of the present invention can be applied to a transistor having a structure in which a barrier layer is provided below a semiconductor channel layer. In forming the spin injection three-terminal element of this embodiment, first, as shown in FIG. 12, a semiconductor substrate 120 made of p-type InAs is used.
1, a buffer layer 1202 is formed, and then AlGaS
a barrier layer 1203 of n-type InAs and a channel layer 12 of n-type InAs on which a channel is to be formed.
04, and an aluminum film 1205 serving as a separation layer is formed.

After forming the laminate of FIG. 12, FIGS.
As shown in FIG. 13, a source electrode 1208 and a drain electrode 1209 made of a ferromagnetic metal material are formed, separation layers 1206 and 1207 are formed, and then a gate is formed on the back surface of the semiconductor substrate 1201 as shown in FIG. Electrode 12
By forming 10, a spin-injection three-terminal element in the present embodiment can be formed.

In the above embodiment, aluminum is used for the separation layer. However, aluminum oxide may be used for the separation layer. In this case, electrons whose spin state is controlled from the ferromagnetic metal tunnel through the aluminum oxide film and reach the compound semiconductor layer.
"Miyazaki" et al., To produce a Fe / Al ₂ O ₃ / Fe junction, 30% 4.2 K, at room temperature, 18% a large magnetoresistance change is reported that the resulting (Reference 2). This is because, considering the spin polarization of Fe of 44%, the spin-polarized electrons in the Fe layer almost tunnel through the Al ₂ O ₃ layer without changing the spin polarization. Equivalent to. This has the same effect as the case where the ferromagnetic metal is directly coupled on the aluminum layer as in the above-described embodiment.

In Reference 2, Fe / Al ₂ O ₃ / F
When e-junction is manufactured, they deposit Fe on a glass substrate, sputter deposit aluminum of 5.5 nm, and then oxidize in air for 24 hours to form Fe to be an upper electrode. This experimental result means that the Fe / Al ₂ O ₃ interface does not necessarily have to be flat and steep at the atomic layer level. As described above, the same effect as the aluminum film can be obtained with the aluminum oxide film. Therefore, when the ferromagnetic metal film 601 is formed on the aluminum film 401 as described with reference to FIG. The ferromagnetic metal film 601 is formed on the aluminum film 401 on which the oxide film is formed without removing the natural oxide film on the surface.
May be formed.

As is clear from the above, in the present invention, the separation layers 104 and 105 shown in FIG. 1 are formed of a layer composed of only aluminum, a layer composed of only aluminum oxide, and a layer composed of a combination of aluminum and aluminum oxide. In any case, the same effect is exhibited. However, the layer of aluminum oxide needs to be thin enough to allow electrons whose spin state is controlled from the ferromagnetic metal electrode to tunnel, that is, to the extent that a tunnel current flows.

[0050]

As described above, according to the present invention, the source / drain of a ferromagnetic metal is formed on a channel layer in which a channel made of a compound semiconductor is formed via an aluminum oxide film such as aluminum or Al ₂ O _3. Since the electrodes are formed and electrons with controlled spin directions are injected into the channel layer, an excellent three-terminal device using an electrode made of a ferromagnetic metal material that is a ferromagnetic material is obtained. effective. In addition, this spin injection three-terminal element has a normal FET amplification function, can be applied as a memory cell or a logic element having a non-volatile memory function, and can operate at room temperature.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a spin injection three-terminal element according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an equivalent circuit in a case where the spin injection three-terminal device of FIG. 1 is designed in a state where the width of a source electrode and the width of a drain electrode are different.

FIG. 3 is a circuit diagram showing a configuration of a memory array using the spin injection three-terminal device of FIG. 2;

FIG. 4 is a process chart showing a manufacturing process of the spin-injection three-terminal element in the embodiment of the present invention.

FIG. 5 is a process drawing following FIG. 4 showing a manufacturing process of the spin injection three-terminal element in the embodiment of the present invention.

FIG. 6 is a process drawing following FIG. 5 showing a process for manufacturing the spin-injection three-terminal element in the embodiment of the present invention.

FIG. 7 is a process drawing following FIG. 6 and illustrating the manufacturing process of the spin-injection three-terminal element in the embodiment of the present invention.

FIG. 8 is a process diagram illustrating a manufacturing process of the spin injection three-terminal device according to the embodiment of the present invention, following FIG. 7;

FIG. 9 is a plan view showing another embodiment of the present invention.

FIG. 10 is a perspective view showing another embodiment of the present invention.

FIG. 11 is a sectional view showing another embodiment of the present invention.

FIG. 12 is a cross-sectional view illustrating another embodiment of the present invention.

FIG. 13 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

101: semiconductor substrate, 102: channel layer, 103: gate electrode, 104, 105: separation layer, 106: source electrode, 107: drain electrode.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H01L 29/417 H01L 27/10 447 29/66 29/50 U 29/778 29/80 H 21/338 A 29/812 29/80 (72) Inventor Hideaki Takayanagi 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 4M104 AA04 AA05 AA07 BB02 BB05 CC01 DD29 DD34 DD35 DD37 GG12 GG16 GG20 5F083 FZ10 5F102 FB05 FB10 GB01 GB02 GC01 GC02 GD01 GD10 GJ04 GJ05 GK04 GL04 GL05 GM04 GM06 GM08 GN04 GQ01 GT02 GV00 HC01 HC15

Claims (9)

[Claims] 1. A channel layer made of a compound semiconductor formed on a substrate made of a compound semiconductor, wherein a channel is formed, and first and second separation layers made of aluminum formed on the channel layer so as to be separated from each other. A source electrode and a drain electrode made of a ferromagnetic metal formed on the first and second separation layers, and a gate electrode for controlling a state of a channel formed in the channel layer. Characteristic spin injection three-terminal device. 2. A channel layer made of a compound semiconductor on which a channel is formed on a substrate made of a compound semiconductor, and a first and a second layer made of an aluminum oxide formed apart from each other on the channel layer. 2, a source electrode and a drain electrode made of a ferromagnetic metal formed on the first and second separation layers, and a gate electrode for controlling a state of a channel formed in the channel layer. A spin-injection three-terminal device, characterized in that: 3. The spin-injection three-terminal device according to claim 2, wherein the first and second separation layers are formed to be thinner than a thickness through which a tunnel current flows. . 4. A channel layer made of a compound semiconductor, in which a channel is formed on a substrate made of a compound semiconductor, and an aluminum film and an aluminum oxide film formed separately from each other on the channel layer. First and second separation layers each having a laminated structure; a source electrode and a drain electrode each formed of a ferromagnetic metal formed on the first and second separation layers; and a state of a channel formed in the channel layer A spin injection three-terminal device comprising: 5. The spin-injection three-terminal device according to claim 4, wherein an aluminum oxide film forming the first and second separation layers is formed to be thinner than a thickness through which a tunnel current flows. Characteristic spin injection three-terminal device. 6. The three-terminal device according to claim 1, wherein the channel layer is made of an n-type compound semiconductor, and a p-type compound semiconductor is provided below the channel layer. Wherein the gate electrode is formed in contact with the layer made of the p-type compound semiconductor. 7. The spin injection three-terminal device according to claim 6, wherein a barrier layer is provided between the p-type compound semiconductor layer and the n-type compound semiconductor layer. Injected three-terminal device. 8. The spin injection three-terminal device according to claim 1, further comprising: an electron supply layer formed of an n-type semiconductor layer formed on the channel layer, wherein the channel layer has A spin injection three-terminal device, wherein a channel formed of a two-dimensional electron cloud by electrons supplied from the electron supply layer is formed, and the gate electrode is formed on the electron supply layer. 9. The three-terminal device according to claim 1, wherein the ferromagnetic metal is an alloy of nickel and iron.