KR20000050426A - Magnetic RAM cell using planar hall effect - Google Patents

Abstract

The present invention is to provide a magnetic memory element using the planar hole effect, the present invention is a base plate layer using a semiconductor substrate or a glass plate; It is composed of a diamagnetic layer positioned on the base plate layer, a soft magnetic layer positioned on the diamagnetic layer, and a current line layer for forming a magnetic field positioned on the diamagnetic layer and the soft magnetic layer. A magnetoresistive sensor layer for measuring the magnetization direction of the hard magnetic layer in the memory layer; A magnetic layer comprising a hard magnetic layer positioned on the magnetoresistive sensor layer, a magnetic field forming current line layer positioned on the magnetoresistive sensor layer and the hard magnetic layer, and an anti-oxidation protective film layer positioned on the magnetic field forming current line layer. By constructing the memory layer, it is nonvolatile and the time required for input / output can be reduced by using a fine current.

Description

Magnetic RAM element using planar hall effect {Magnetic RAM cell using planar hall effect}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a basic element of a magnetic memory, and in particular, to develop a magnetic RAM that maximizes the magnetoresistance ratio and improves the linearity of the output signal. The present invention relates to a basic element of a magnetic memory using a planar hole effect capable of reading stored information.

In general, magnetic RAM memory is expected to replace DRAM, SRAM and flash memory with next generation memory, and can be used as memory for personal computers, large computers, smart cards, portable computers, mobile communication terminals, telephones, and televisions. . In addition, since it is highly resistant to ion radiation, it can be used as a memory for spacecraft such as satellites, space-shuttles, and military equipment.

Conventional DRAMs and SRAMs use a semiconductor device, and thus have a high volatility, and thus have a weak resistance to ion radiation. Among these shortcomings, FeRAM (Ferroelectric RAM) has been developed as a highly volatile memory device, but at the present stage, it has a small capacity and requires a high voltage when inputting information and a large dielectric constant to reduce the size of the basic device. It requires the development of materials. Therefore, research on magnetic memory is being conducted as a next generation memory to replace semiconductor RAM, Fe RAM, and the like.

Some developed countries have already been developing magnetic RAM, and FIG. 1 is a conceptual diagram of a basic element of a magnetic RAM under study at Stanford University in the United States. Meanwhile, Toshiba Corp., Japan, has already manufactured a test chip to test the characteristics of its magnetic RAM. The test chip manufactured by Toshiba Corp. records information with a fine magnet generated when an input current flows through a micro-hard magnet of a platinum-cobalt alloy wrapped with aluminum or an insulating layer, and at the time of output, a separate current It is designed to output information by using. As a result of experimenting basic input and output operation, it is confirmed that the time required for output is 6ns faster than DRAM.

Magnetic memory technology is already used in hard disks, floppy disks, magnetic tapes, etc., but the technique of reading the information of the static magnetization (Static Magnetization) was not complete. In 1996, however, magneto-resistive materials capable of reading sperm began to be developed, and research and development on magnetic RAMs began in earnest. In other words, the key to the development of a magnetic RAM depends on the development of a magnetoresistive material. Magnetoresistive materials are used in various fields throughout the industry such as hard disk read sensors, magnetic field sensors, magnetic torque sensors and motion sensors.

The magnetoresistance of an anisotropic magnetoresistive material used in the related art is changed as in Equation 1 according to the direction of magnetization.

here Is the angle between the direction of the current and the magnetization direction, Is the resistance when magnetization is in the current direction, Is the resistance when magnetization is perpendicular to the current. Magnetoresistance ratio, which is one of the main characteristics of the anisotropic magnetoresistance material, is defined as in Equation 2 below.

Currently, active research on magnetoresistive materials focuses on the improvement of the magnetoresistance ratio (MR).

Magnetic RAM using magnetoresistive sensors is still in the research stage, but several patents have already been applied (see US Pat. Nos. 5734606, 5732016, 5703805, 5650958, 5640343, etc.).

Therefore, the conventional reading structure of the magnetic RAM using a magnetoresistive sensor uses a four-terminal method, which is a general resistance measurement method as shown in FIG. 2, and the resistance change according to the magnetic field strength of these anisotropic magnetoresistive materials is shown in FIG.

However, the magnetoresistance ratio of the conventional magnetoresistive material already developed is about 2 to 10%, but the off-set voltage ( ), The sensitivity is large, and the sensitivity and linearity is poor.

Accordingly, the present invention has been proposed to solve the conventional problems as described above, and an object of the present invention is to maximize the magnetoresistance ratio and at the same time develop a magnetic RAM that improves the linearity of the output signal. The present invention provides a magnetic memory basic device using a planar hole effect capable of recording information in a magnetic material and reading stored information using a magnetoresistive material.

In order to achieve the above object, the magnetic memory basic element using the planar hole effect according to the present invention,

A base plate layer using a semiconductor substrate or a glass plate; It is composed of a diamagnetic layer positioned on the base plate layer, a soft magnetic layer positioned on the diamagnetic layer, and a current line layer for forming a magnetic field positioned on the diamagnetic layer and the soft magnetic layer. A magnetoresistive sensor layer for measuring the magnetization direction of the hard magnetic layer in the memory layer; A magnetic layer comprising a hard magnetic layer positioned on the magnetoresistive sensor layer, a magnetic field forming current line layer positioned on the magnetoresistive sensor layer and the hard magnetic layer, and an anti-oxidation protective film layer positioned on the magnetic field forming current line layer. It consists of a memory layer characterized by its technical construction.

1 is a diagram of a basic element of a magnetic RAM under study at Stanford University,

2 is a view showing a magnetoresistance measurement using a conventional four-terminal method,

3 is a graph showing the magnetoresistance characteristic curve shown in FIG.

4 is a view showing a measurement of a magnetic memory element using the planar hole effect of the present invention;

5 is a graph showing a magnetoresistance characteristic curve by a magnetic memory element using the planar hole effect of the present invention;

6 is a diagram showing a layered structure of a magnetic memory basic element using the planar hole effect according to the present invention;

7 is a diagram showing a line configuration for current-voltage measurement of a magnetoresistive sensor of a magnetic memory basic element using the planar Hall effect of the present invention;

8 is a graph showing a current-magnetization characteristic curve of a magnetic recording medium using a magnetic memory element using the planar hole effect of the present invention.

9 is a view showing a magnetic field forming current line of a magnetic memory basic device using the planar hole effect of the present invention.

<Description of the code | symbol about the principal part of drawing>

10: bottom plate layer 20: magnetoresistance sensor layer

21: diamagnetic layer 22: soft magnetic layer

23: current line layer 30: magnetic memory layer

31: hard magnetic layer 32: current line layer

33: protective layer

Hereinafter, with reference to the accompanying drawings an embodiment according to the technical idea of the magnetic memory basic device using the planar hole effect of the present invention as described above in detail.

4 is a diagram showing a measurement of a magnetic memory element using the planar hole effect of the present invention.

Therefore, in the present invention, unlike the conventional magnetoresistance measuring method, the voltage is measured perpendicularly to the direction of the main current (Planar Hall Effect), and a minute negative current flows in the voltage measuring direction to maximize the magnetoresistance ratio and simultaneously output the same. The company wanted to develop a magnetic RAM with improved signal linearity.

The magnetoresistance of the anisotropic magnetoresistance material changes with the angle between the magnetization direction and the current direction. Therefore, the relationship between the applied current, the anisotropic resistance of the specimen, and the measured voltage is shown in Equations 3 and 4 below.

Here, by using the coordinate transformation When is calculated as shown in the following equations (5) to (8).

The prior art is represented by equations (5) to (8). (Magnetoresistance, MR), but the present invention uses the equation (6) Or in Equation 7 (Planar Hall Effect) and the main current to improve the magnetoresistance ratio and the linearity of the output signal. therefore In the case of using and the case of using the housewife current, the magnetoresistance characteristic change is explained as follows.

(One) (Planar Hall Effect)

Current in the direction and the voltage in the direction perpendicular to the direction of the current. The case of measuring is called Planar Hall Effect. In this case, the measured voltage Is expressed by the following equations (9) and (10).

The magnetoresistance ratio at this time is expressed by Equation 11 below.

So, comparing Equation 11 with Equation 2, which is a conventional technology, generally Is Since the present invention has a significantly smaller value, the magnetoresistance ratio can be improved by 100% or more when the magnetoresistance ratio is calculated by the present invention.

(2) When main and negative current are applied

Is the main current Is applied as a negative current, When measuring, the magnetoresistance is expressed as Equation 12 below.

If the magnitude of the main current is very large compared to the magnitude of the negative current, i.e. Equation 12 is expressed as Equation 13 below.

At this time, the magnetoresistance ratio is expressed as Equation 14 below.

Therefore, by controlling the direction and intensity of the current By matching the conditions of the magnetoresistance ratio can be improved infinitely, the experimental results are as shown in the graph showing the magnetoresistance characteristic curve by the magnetic memory element using the planar hole effect of the present invention of FIG. 5A is a graph showing the magnetoresistance characteristic curve when the housewife current is applied, and FIG. 5B is a graph showing the magnetoresistance characteristic curve by the Planer Hall Effect.

FIG. 6 is a diagram showing a layered structure of a magnetic memory basic element using the planar hole effect according to the present invention.

As shown here, a substrate layer (Substrate) layer 10 using a semiconductor substrate or a glass plate; A diamagnetic layer 21 positioned on the base plate layer 10, a soft magnetic layer 22 positioned on the diamagnetic layer 21, and a magnetic field located on the diamagnetic layer 21 and the soft magnetic layer 22. A magnetoresistive sensor layer 20 having a current line layer 23 for forming and measuring a magnetization direction of the hard magnetic layer 31 in the magnetic memory layer 30 by using a resistance change according to the strength of the magnetic field; A hard magnetic layer 31 positioned on the magnetoresistive sensor layer 20, a magnetic field forming current line layer 32 located on the magnetoresistive sensor layer 20 and the hard magnetic layer 31, and the magnetic field. It is composed of a magnetic memory layer 30 composed of an anti-oxidation protective film layer 33 positioned on the forming current line layer 32.

Therefore, the bottom plate layer 20 as a substrate may improve the characteristics of the magnetic RAM by using a semiconductor substrate such as Si or GaAs together with the RAM's address register or TFT (Thin-Film Transistor). If it is not necessary to configure such as a glass plate can be used inexpensive.

In addition, the magnetoresistive sensor layer 20 uses a resistance change according to the strength of the magnetic field. The magnetoresistive sensor layer 20 is composed of a diamagnetic layer 21, a soft magnetic layer 22 and a current line layer 23 which is a copper line, and measures the magnetization direction of the hard magnetic material. FeMn or NiO is used as a material of the diamagnetic layer 21 of the magnetoresistive sensor layer 20, and materials such as NiFe, Fe, Ni, Co, and the like are used as the material of the soft magnetic layer 22. Therefore, anisotropic magnetoresistance, giant magnetoresistance, tunnel magnetoresistance, ferroelectric magnetoresistance and the like are used as magnetoresistance materials for magnetoresistance sensors.

The structure of the current-voltage measuring line for reading the magnetoresistance change is shown in FIG. In Fig. 7, resistors attached to both ends of the voltage measuring line prevent current from leaking for voltage measuring.

Fig. 8 is a graph showing a current-magnetization characteristic curve of a magnetic recording medium using the magnetic memory basic element using the plane hole effect of the present invention. As shown in FIG. 8, the magnetization of the hard magnetic material in the magnetic memory layer is applied to the magnetoresistive material. The magnetic field strength of the magnetoresistive material is about 30 Oe, so the magnetoresistance characteristic curve of the magnetoresistive material is about 30 It must have a magnetic field-resistance characteristic that operates at Oe.

On the other hand, the magnetic memory layer 30 is composed of a hard magnetic layer 31, a magnetic field forming current line layer 32, and an antioxidant cover layer 33.

At this time, the principle of magnetic memory is to generate a magnetic field by applying a fine current, and the magnetization direction of the inclined body of the hard magnetic layer 31 is rotated according to the direction of these magnetic fields to input information of "0" and "1". At this time, the magnetic field is changed according to the direction and intensity of the current, so the current for inputting information is about ?? 1mA. The strength of the magnetic field generated at this time can be obtained from Equation 15 below.

Where r is the distance between the conductor and the hard magnetic material applying the current. Distance r is 1 When a current of 1 mA is applied, the magnetic field induced by the hard magnetic material is about 200 Oe, and thus sufficient magnetic field strength can be made to rotate the magnetization direction of the hard magnetic material.

Therefore, when storing information using a current of 1mA, the hard magnetic material should be able to rotate the magnetization direction at about 200 Oe, and use magnetic garnet, which is a material used in hard disks, floppy disks, and magnetic tapes. Can be.

9 is a view showing a magnetic field forming current line layer 32 of a magnetic memory basic element using the planar hole effect of the present invention.

In the magnetic field formation, as shown in FIG. 9, dual currents I1 and I2 are simultaneously applied to input information into the permanent magnet. At this time, the strength of the current and the magnetic hysteresis of the permanent magnet are placed in the relationship as shown in FIG. That is, by making I1 and I2 have the same direction at the same time, the magnetization of the permanent magnet is rotated to record the magnetic information.

As such, the present invention is to develop a magnetic RAM that maximizes the magnetoresistance ratio and improves the linearity of the output signal.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, the magnetic memory basic element using the planar hole effect according to the present invention uses a hard magnetic material as a recording medium, and thus has a nonvolatile information that does not disappear even when the power is cut off. As it is made using current, it can reduce the time required for input / output, so it can be replaced by next generation memory for DRAM, SRAM, flash memory, etc.Personal computer, large computer, smart card, portable computer, mobile communication terminal, telephone The present invention can be used as a memory of a television, etc., and furthermore, it has a high resistance to ion radiation, and thus can be used as a memory of a spacecraft such as a satellite, a space shuttle, or military equipment.

Claims (8)

In the magnetic memory element, A base plate layer using a semiconductor substrate or a glass plate; It is composed of a diamagnetic layer positioned on the base plate layer, a soft magnetic layer positioned on the diamagnetic layer, and a current line layer for forming a magnetic field positioned on the diamagnetic layer and the soft magnetic layer. A magnetoresistive sensor layer for measuring the magnetization direction of the hard magnetic layer in the memory layer; A magnetic layer comprising a hard magnetic layer positioned on the magnetoresistive sensor layer, a magnetic field forming current line layer positioned on the magnetoresistive sensor layer and the hard magnetic layer, and an anti-oxidation protective film layer positioned on the magnetic field forming current line layer. Magnetic memory element using the planar Hall effect, characterized in that consisting of a memory layer. The magnetoresistive sensor layer of claim 1, wherein A magnetic memory element using the planar Hall effect, characterized by using the planar Hall effect to improve the magnetoresistance ratio and linearity of the output signal. The magnetoresistive sensor layer of claim 1, wherein A magnetic memory element using the planar hole effect, characterized by using a main current and a negative current to improve the magnetoresistance ratio and the linearity of the output signal. The method of claim 3, wherein the main current and the negative current, A magnetic memory element using the planar hall effect, wherein the strength of the main current is greater than that of the negative current. The magnetic resistance ratio of claim 3, Main current And negative current Using To determine the magnetoresistance ratio Where Is the resistance when magnetization is in the current direction, Is the resistance when magnetization is perpendicular to the current, and adjusts the direction and intensity of the current Magnetic memory basic element using the planar Hall effect, characterized in that to make the magnetic memory element by improving the magnetoresistance ratio to the maximum. The magnetoresistive sensor layer of claim 1, wherein A magnetoresistive element using a planar hole effect, characterized in that anisotropic magnetoresistance, giant magnetoresistance, tunnel magnetoresistance, ferroelectric magnetoresistance, etc. are selectively used as a magnetoresistance material for a magnetoresistance sensor. The method of claim 1, wherein the magnetic memory layer, A magnetic memory element using the planar hole effect, wherein information is stored by rotating magnetization of the magnetic memory layer by using a magnetic field induced by a double current. The magnetic field forming current line layer of claim 1, wherein A magnetic memory element using the planar hall effect, by adding a resistor to both ends of a voltage measuring line, which is a current line for forming a magnetic field, to prevent leakage of main current for measuring magnetic resistance.