KR100927195B1 - Logic and Logic Logic Computing Device Using Dual Magnetic Tunnel Junction Devices Using Spin Torque Conversion - Google Patents

Abstract

The present invention relates to an XOR and XNOR logic operation apparatus using a dual magnetic tunnel junction device using a spin torque conversion that does not require an initialization process.

A first pinned layer to which a first input signal is applied and having a fixed magnetization direction, a first dielectric layer formed under the first pinned layer for electrical insulation, and a first free layer formed under the first dielectric layer and having a variable magnetization direction A first magnetic tunnel junction element composed of layers; A second pinned layer having a second input signal and having a fixed magnetization direction, a second dielectric layer formed on the second pinned layer for electrical insulation, and a second free layer formed on the second dielectric layer and having a variable magnetization direction A second magnetic tunnel junction element configured; And a third dielectric layer for electrical insulation between the first and second magnetic tunnel junction elements.

Description

Device for XOR and XNOR magneto-logic circuit using double STT-MTJ using dual magnetic tunnel junction device using spin torque conversion

The present invention relates to an XOR and XNOR logic operation apparatus, and more particularly, to an XOR and XNOR logic operation apparatus using a dual magnetic tunnel junction element using a spin torque conversion that does not require an initialization process.

In general, a logic circuit using a magnetic tunnel junction junction (MTJ) element changes the magnetization direction of the free magnetic layer when the same current flows through the input terminal, and free layer when the current directions are different. Since the magnetization direction of does not change, the magnetic spin of the free layer in the intersected cell can be arranged in the desired direction by the synthetic magnetic field generated by each current, and the magnetization direction of the pinned magnetic layer is fixed, so By implementing the magnetization direction of the magnetic layer of the parallel or anti-parallel, it is possible to record a digital signal that is a logic level of '1' and '0'.

In addition, when reading a digital signal having a logic level of '1' and '0', Tunnelling Magneto-Resistance (TMR) of a magnetic tunnel junction element is used. When a sensing voltage is applied to the magnetic tunnel junction element, the electron carrier is By tunneling through a nonmagnetic, non-conductive tunnel layer between magnetic material layers, the magnetic material layer passes through and the resistance to the sensing current is minimal when the magnetic vectors of the pair of magnetic material layers are parallel to each other in the same direction. The conductance of electrons tunneling through the insulating layer can be used to measure the resistance along the relative magnetization direction of the two magnetic layers.

Meanwhile, the XOR logic unit is an exclusive OR circuit, which is true when only one of the two input values is true. The XOR logic unit may be implemented using the magnetic tunnel junction element.

In Fig. 1, an XOR logic computing device using a magnetic tunnel junction element according to the prior art is shown (see J. of Applied Physics, vol. 97, p. 10D509, 2005).

Referring to FIG. 1, an XOR logic operation apparatus using a magnetic tunnel junction element according to the related art includes an upper electrode 2 and a lower electrode 3 provided with a current to conduct, and deposited between the upper electrode and the lower electrode. On the upper electrode 2 and the magnetic tunnel junction element comprising a fixed layer 4 and a free layer 6 which are magnetic steel layers, an insulating layer 5 which insulates between the fixed layer and the free layer and is deposited therebetween. A current input to the input layers 7 and 8, including two input layers 7 and 8 which are positioned to input current for magnetization of the fixed layer 4 and the free layer 6 of the magnetic tunnel junction element. Perform XOR logic operation according to the direction.

When the direction of the current flowing through each of the input layers 7 and 8 is -I as shown in FIG. 1 (the direction from the front to the rear of the input layer shown in FIG. 1, the left arrow), the logic level is' If 0 'or + I (right arrow), the logic level is defined as' 1'. The magnetization direction of the free layer 6 changes when the directions of currents flowing through the respective input layers are the same, and the magnetization direction of the free layer 6 does not change when the directions of currents flowing through the input layers are different. .

When no current flows through the lower electrode 3, the magnetization direction of the pinned layer 4 does not change. In order to change the magnetization direction of the pinned layer 4, the direction of the current flowing through each of the input layers 7 and 8 while the current I flows in the lower electrode 3 must be the same.

2 illustrates an initialization process and an operation process of an XOR logic operation apparatus using a magnetic tunnel junction element according to the related art. The operation of the magnetic tunnel junction element is divided into an initialization process (see FIG. 2 (a); 'SET') and an operation process (see FIGS. 2 (b) to (e); 'Logic').

Referring to FIG. 2A, the magnetization direction of the pinned layer 4 is to the left and the magnetization direction of the free layer 6 is to the right through a two-step initialization process before the logic operation unit operates. Is made of R _H.

Next, -I (logical level 0) or + I (logical level 1) is applied to each of the input layers 7 and 8 while the current I is applied to the lower electrode 3 of FIGS. When input as shown in (d) of 2, the resistance value of the magnetic tunnel junction element is determined as shown in (b) to (d) of FIG.

As shown in FIGS. 2B to 2D, when the logic levels of the respective input layers 7 and 8 are the same, the resistance value is determined as the resistance value R _L having a low level, and the logic level. If is different, R _H is determined as the initialization state.

When the resistance value of the magnetic tunnel junction element is compared with R _L using a sense amplifier as shown in FIG. 3, the magnetic tunnel junction element operates as an XOR logic arithmetic element as shown in Table 1 '.

TABLE 1

A B C R OUT 0 0 I R _L 0 0 One I R _H One One 0 I R _H One One One I R _L 0

At this time, when the resistance value of the magnetic tunnel junction element is R _L , the offset voltage (V _OS ) of the sense amplifier is decreased so that the output of the sense amplifier becomes a logic level '0'.

-I _SENS * ΔR <V _OS <0 (ΔR = R _H -R _L )

Must satisfy

The XOR logic operation apparatus using the magnetic tunnel junction element according to the related art has a disadvantage in that the magnetization directions of the free layer and the pinned layer of the magnetic tunnel junction element are always reinitialized after the operation.

That is, as shown in (a) to (e) of FIG. 2, the magnetization directions of the free layer and the fixed layer are changed by the logic levels of the input layers 7 and 8, so that the magnetization directions are reduced again for the next logical operation. There is a two-step initialization process. For this reason, there is a problem that the operating speed of the XOR logic computing device is reduced. This problem also occurs in the XNOR logic arithmetic unit.

An object of the present invention is to provide an XOR and XNOR logic operation apparatus that does not require an initialization process in order to solve the problem that the operation speed of the prior art XOR and XNOR logic operation apparatus is reduced as described above.

XOR and XNOR logic operation apparatus using a dual magnetic tunnel junction device according to the present invention for solving the above problems,

A first pinned layer to which a first input signal is applied and having a fixed magnetization direction, a first dielectric layer formed under the first pinned layer for electrical insulation, and a first free layer formed under the first dielectric layer and having a variable magnetization direction A first magnetic tunnel junction element composed of layers; A second pinned layer having a second input signal and having a fixed magnetization direction, a second dielectric layer formed on the second pinned layer for electrical insulation, and a second free layer formed on the second dielectric layer and having a variable magnetization direction A second magnetic tunnel junction element configured; And a third dielectric layer for electrical insulation between the first and second magnetic tunnel junction elements.

In addition, the magnetization direction of the first and second free layers is a current formed between the first and second fixed layers and the first and second free layers by the voltages of the input signals applied to the first and second fixed layers. The magnetization direction is determined by the spin torque conversion method according to the direction of.

In addition, the first and second free layers may be applied with a voltage between a voltage corresponding to logic level '0' and a voltage corresponding to logic level '1'. Here, preferably, the first and second free layers are applied with an intermediate voltage between a voltage corresponding to logic level '0' and a voltage corresponding to logic level '1'.

In this case, the voltage applied to the first and second free layers is a voltage capable of applying a current larger than a threshold current required to change the magnetization direction of the first and second free layers.

In addition, when the magnetization directions of the first pinned layer and the second pinned layer are fixed in the same direction, an XOR logic operation is performed. When the magnetization directions of the first pinned layer and the second pinned layer are fixed in different directions, an XNOR logic operation is performed. It characterized in that to perform.

According to the XOR and XNOR logic operation apparatus using the double magnetic tunnel junction element according to the present invention as described above,

Unlike the conventional XOR and XNOR logic arithmetic units, since no initialization process is required, the operation speed of the XOR and XNOR logical arithmetic units is improved.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; First, it should be noted that the same components or parts in the drawings represent the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the gist of the present invention.

4 is a diagram illustrating a dual magnetic tunnel junction element used in the XOR and XNOR logic operation apparatus according to the present invention, in which the first and second pinned layers are magnetized in the same direction to perform XOR logic operations. FIG. 5 is a diagram illustrating first and second input signals applied to the first and second pinned layers of FIG. 4 and voltages applied to the first and second free layers when data is written. FIG. 6 is an XOR according to the present invention. And a dual magnetic tunnel junction element used in the XNOR logic computing device, in which the first and second pinned layers are magnetized in different directions to perform XNOR logic operations, and FIG. The first and second input signals applied to the first and second pinned layers and the voltages applied to the first and second free layers are illustrated in FIG.

The magnetic tunnel junction elements 100 and 200 constitute a magneto-resistive random access memory (MRAM), and the magnetoresistive effect of changing the resistance of the electric conductor according to the surrounding magnetic field is shown in FIG. resistance effect) to store data and information.

In this case, the magnetoresistance effect is a phenomenon in which the electrical resistance of a material is changed by a magnetic field. When a magnetic field is applied to a metal or a semiconductor, the electrical resistance increases, and the increase in the electrical resistance is weak for an electric field. It is a phenomenon that is proportional to the square of the magnetic field strength, and the case where the direction of the current is perpendicular to the direction of the magnetic field is called a lateral effect. In a ferromagnetic material, a change in resistance occurs due to spontaneous magnetization.

Conventional magnetic tunnel junction devices use a phenomenon in which the magnetization direction of the free layer is changed by a magnetic field direction applied by an electric current flowing to an external metal line, but a magnetic tunnel using spin torque transfer is used. In the junction element, the magnetization direction of the free layer is changed by the direction of the current flowing through the magnetic tunnel junction element. When the current flows from the free layer to the fixed layer, the magnetization direction of the free layer is the same as the magnetization direction with the fixed layer, and the resistance value of the magnetic tunnel junction element becomes R _L. On the contrary, when the current flows from the fixed layer to the free layer, the magnetization direction of the free layer is opposite to the magnetization direction of the fixed layer, and the resistance value of the magnetic tunnel junction element becomes R _H.

XOR and XNOR logic operation apparatus according to the present invention is characterized in that the magnetic tunnel junction element (100, 200) using the spin torque conversion is formed in duplicate. As shown in FIG. 4, each of the magnetic tunnel junction elements 100 and 200 may include first and second pinned layers 110 and 210, first and second free layers 120 and 220, and the first and second layers, respectively. 2 The first and second dielectric layers 130 and 230 are formed between the pinned and free layers to electrically insulate between the pinned and free layers.

The magnetization direction of the first pinned layer 110 is fixed, and a first input signal 'A' of FIG. 5 is applied. Meanwhile, the magnetization direction of the second pinned layer 210 is also fixed, and a second input signal 'B' of FIG. 5 is applied. In this case, the fixed magnetization direction is determined to be the same as the magnetization direction of the first pinned layer 110 and the second pinned layer 210 according to whether to perform XOR logic operation or XNOR logic operation. When the XOR logic operation is to be performed, the magnetization direction of the first pinned layer 110 is the same as the magnetization direction of the second pinned layer 210, and when the XNOR logic operation is to be performed, the magnetization direction is changed. .

The first free layer 120 is formed under the first dielectric layer 130 for electrical insulation, and is formed by a voltage applied to the first free layer and a voltage of an input signal applied to the first fixed layer. According to the direction, the magnetization direction of the first free layer is determined by the spin torque conversion method. Similarly, the second free layer 220 is formed on the second dielectric layer 230 for electrical insulation and is formed by the voltage applied to the second free layer and the voltage of the input signal applied to the second fixed layer. The magnetization direction of the second free layer is determined by the spin torque conversion method according to the direction of. Meanwhile, a third dielectric layer 330 for electrical insulation is formed between the magnetic tunnel junction elements 100 and 200.

Referring to FIG. 5, a first input signal A is applied to the first pinned layer 110, and a second input signal B is applied to the second pinned layer 210. In this case, the first free layer 120 and the second free layer 220 may have a voltage corresponding to logic level '0' (for example, '0') and a voltage corresponding to logic level '1' (for example, For example, a voltage corresponding to the middle between 'V' (eg 'V / 2') is applied and maintained. In this case, a voltage (eg, 'V / 2') applied to the first and second free layers may apply a current larger than a threshold current required to change the magnetization direction of the first and second free layers. That is the voltage.

Referring to the process of performing the XOR logic operation in the XOR and XNOR logic operation apparatus using a dual magnetic tunnel junction device using the spin torque conversion according to the present invention as follows.

First, as shown in FIG. 5, the magnetization directions of the first and second pinned layers 110 and 210 are fixed to the right side. During the writing, the first and second free layers 120 and 220 maintain the same voltage, so that no current flows between the two layers. When the first input signal A applied to the first pinned layer 110 has a logic level of '1', current flows from the first pinned layer 110 to the first free layer 120. Accordingly, the magnetization direction of the first free layer 120 is magnetized to the left side opposite to the magnetization direction of the first pinned layer 110. On the contrary, when the first input signal is at logic level '0', current flows from the first free layer 120 to the first pinned layer 110. Therefore, the magnetization direction of the first free layer 120 is magnetized to the right, which is the same direction as the magnetization direction of the first pinned layer 110.

Similarly, when the second input signal B applied to the second pinned layer 210 has a logic level of '1', current flows from the second pinned layer 210 to the second free layer 220. Therefore, the magnetization direction of the second free layer 220 is magnetized to the left side opposite to the magnetization direction of the second pinned layer 210. On the contrary, when the second input signal is at logic level '0', current flows from the second free layer 220 to the second pinned layer 210. Therefore, the magnetization direction of the second free layer 220 is magnetized to the right, which is the same direction as the magnetization direction of the second pinned layer 210.

According to the combination of the first and second input signals, the magnetization directions of the first and second free layers 120 and 220 are configured as shown in Table 1 below.

TABLE 1

0 One 0 → → ← → One → ← ← ←

In Table 1, the first horizontal row refers to the logic level of the first input signal A, and the first vertical column refers to the logic level of the second input signal B. In each item, an up arrow indicates a magnetization direction of the first free layer, and a down arrow indicates a magnetization direction of the second free layer.

In the meantime, the resistance between the first free layer 120 and the second free layer 220 is measured while reading is performed. At this time, since the applied voltage is low enough to flow the current below the threshold current value, the magnetization direction of the free layer does not change. As a result, the resistance is measured as shown in Table 2 below, where R _H is defined as logic level '1' and R _L is defined as logic level '0', as shown in Table 3 below.

TABLE 2

0 One 0 R _L R _H One R _H R _L

TABLE 3

0 One 0 0 One One One 0

In [Table 2] and [Table 3], the first horizontal row refers to the logic level of the first input signal A, and the first vertical column refers to the logic level of the second input signal B.

According to Table 3, when the magnetization directions of the first pinned layer 110 and the second pinned layer 210 are the same, the logic operation device using the dual magnetic tunnel junction element according to the present invention operates as an XOR logic circuit. Able to know.

6 is a diagram illustrating a dual magnetic tunnel junction device used in the XOR and XNOR logic operation apparatus according to the present invention, in which the first and second pinned layers are magnetized in different directions to perform XNOR logic operations. As compared with FIG. 4, it can be seen that the magnetization direction of the first pinned layer 110 is different from the magnetization direction of the second pinned layer 210. That is, the first pinned layer is magnetized to the left and the second pinned layer is magnetized to the right.

Referring to FIG. 7, similar to FIG. 5 described above, a first input signal A is applied to the first pinned layer 110, and a second input signal B is applied to the second pinned layer 210. . In this case, the first free layer 120 and the second free layer 220 may have a voltage corresponding to logic level '0' (for example, '0') and a voltage corresponding to logic level '1' (for example, For example, a voltage corresponding to the middle between 'V' (eg 'V / 2') is applied and maintained. In this case, a voltage (eg, 'V / 2') applied to the first and second free layers may apply a current larger than a threshold current required to change the magnetization direction of the first and second free layers. That is the voltage.

Referring to the process of performing the XNOR logic operation in the XOR and XNOR logic operation apparatus using the dual magnetic tunnel junction element using the spin torque conversion according to the present invention as follows.

First, the magnetization direction of the first pinned layer 110 is fixed to the left side, and the magnetization direction of the second pinned layer 210 is fixed to the right side. During the writing, the first and second free layers 120 and 220 maintain the same voltage, so that no current flows between the two layers. When the first input signal A applied to the first pinned layer 110 has a logic level of '1', current flows from the first pinned layer 110 to the first free layer 120. Therefore, the magnetization direction of the first free layer 120 is magnetized to the right side opposite to the magnetization direction of the first pinned layer 110. On the contrary, when the first input signal is at logic level '0', current flows from the first free layer 120 to the first pinned layer 110. Therefore, the magnetization direction of the first free layer 120 is magnetized to the left, which is the same direction as the magnetization direction of the first pinned layer 110.

Similarly, when the second input signal B applied to the second pinned layer 210 has a logic level of '1', current flows from the second pinned layer 210 to the second free layer 220. Therefore, the magnetization direction of the second free layer 220 is magnetized to the left side opposite to the magnetization direction of the second pinned layer 210. On the contrary, when the second input signal is at logic level '0', current flows from the second free layer 220 to the second pinned layer 210. Therefore, the magnetization direction of the second free layer 220 is magnetized to the right, which is the same direction as the magnetization direction of the second pinned layer 210.

According to the combination of the first and second input signals, the magnetization directions of the first and second free layers 120 and 220 are configured as shown in Table 4 below.

TABLE 4

0 One 0 ← → → → One ← ← → ←

In Table 4, the first horizontal row refers to the logic level of the first input signal A, and the first vertical column refers to the logic level of the second input signal B. In each item, an up arrow indicates a magnetization direction of the first free layer, and a down arrow indicates a magnetization direction of the second free layer.

In the meantime, the resistance between the first free layer 120 and the second free layer 220 is measured while reading is performed. At this time, the applied voltage is low enough to flow a current below the threshold current value, so the magnetization direction of the free layer does not change. As a result, the resistance is measured as shown in [Table 5] below, where R _H is defined as logic level '1' and R _L is defined as logic level '0'.

TABLE 5

0 One 0 R _H R _L One R _L R _H

TABLE 6

0 One 0 One 0 One 0 One

In [Table 5] and [Table 6], the first horizontal row refers to the logic level of the first input signal A, and the first vertical column refers to the logic level of the second input signal B.

According to Table 6, when the magnetization directions of the first pinned layer 110 and the second pinned layer 210 are different, the logic operation device using the dual magnetic tunnel junction device according to the present invention operates as an XNOR logic circuit. Able to know. In addition, since the magnetization direction of the fixed layer does not change in these XOR or XNOR logic operations, it can be seen that an initialization process is not necessary.

Therefore, unlike the conventional XOR and XNOR logic operation apparatus, the XOR and XNOR logic operation apparatus using the dual magnetic tunnel junction device according to the present invention does not require an initialization process, so that the operation speed of the XOR and XNOR logic operation apparatus is improved. It works.

As described above with reference to the drawings illustrating the XOR and XNOR logic operation apparatus using a dual magnetic tunnel junction element using the spin torque conversion according to the present invention, the present invention is limited by the embodiments and drawings disclosed herein Of course, various modifications can be made by those skilled in the art within the technical scope of the present invention.

1 is a view showing an XOR logic operation apparatus using a magnetic tunnel junction element according to the prior art,

2 is a view illustrating an initialization process and an operation process of an XOR logic operation apparatus using a magnetic tunnel junction element according to the prior art;

3 is a diagram illustrating an XOR logic operation apparatus using a magnetic tunnel junction element according to the prior art;

4 is a diagram illustrating a dual magnetic tunnel junction element used in the XOR and XNOR logic operation apparatus according to the present invention, in which the first and second pinned layers are magnetized in the same direction to perform XOR logic operations.

FIG. 5 is a diagram illustrating first and second input signals applied to the first and second pinned layers of FIG. 4 and voltages applied to the first and second free layers when data is written;

FIG. 6 is a diagram illustrating a dual magnetic tunnel junction device used in an XOR and XNOR logic computing device according to the present invention, in which the first and second pinned layers are magnetized in different directions to perform XNOR logic operations.

FIG. 7 is a diagram illustrating first and second input signals applied to the first and second fixed layers of FIG. 6 and voltages applied to the first and second free layers when data is written.

<Description of the symbols for the main parts of the drawings>

100, 200: magnetic tunnel junction element

110, 210: first and second fixed layers

120, 220: first and second free layers

130, 230, 330: first, second and third dielectric layers

Claims (8)

A first pinned layer to which a first input signal is applied and having a fixed magnetization direction, a first dielectric layer formed under the first pinned layer for electrical insulation, and a first free layer formed under the first dielectric layer and having a variable magnetization direction A first magnetic tunnel junction element composed of layers; A second pinned layer having a second input signal and having a fixed magnetization direction, a second dielectric layer formed on the second pinned layer for electrical insulation, and a second free layer formed on the second dielectric layer and having a variable magnetization direction A second magnetic tunnel junction element configured; And, A third dielectric layer for electrical insulation between the first and second magnetic tunnel junction elements XOR and XNOR logic operation apparatus using a dual magnetic tunnel junction element comprising a. The method according to claim 1, The magnetization direction of the first and second free layers is a direction of a current formed between the first and second fixed layers and the first and second free layers by a voltage of an input signal applied to the first and second fixed layers. And the magnetization direction is determined by a spin torque conversion method. The method according to claim 1, The first and second free layers are XOR using a dual magnetic tunnel junction element, wherein a voltage between a voltage corresponding to logic level '0' and a voltage corresponding to logic level '1' is applied during data writing. And an XNOR logical operation unit. The method according to claim 3, The first and second free layers are provided with an intermediate voltage between the voltage corresponding to logic level '0' and the voltage corresponding to logic level '1' upon data writing. XOR and XNOR logic units. The method according to claim 3, The voltage applied to the first and the second free layer when data is written is a dual magnetic tunnel, characterized in that the voltage to apply a current larger than the threshold current required to change the magnetization direction of the first and second free layer. XOR and XNOR Logic Computing Device Using Junction Devices. The method according to claim 1, The XOR and XNOR logic arithmetic unit using the dual magnetic tunnel junction element when the magnetization direction of the first pinned layer and the second pinned layer is fixed in the same direction. The method according to claim 1, The XOR and XNOR logic arithmetic unit using the dual magnetic tunnel junction element when the magnetization direction of the first pinned layer and the second pinned layer is fixed in a different direction. The method according to claim 1, The voltage applied when reading data to the first and second free layers is a voltage capable of applying a current less than a threshold current required to change the magnetization direction of the first and second free layers. XOR and XNOR logic computing device using device.

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