YOU, Chun Yeol (# Dong-a Apt, Dongchun-dong Yeonsu-g, Incheon 406-130, 115-1001, KR)
Claims
[1] A magnetic domain wall movement memory device, comprising: a substrate including a plurality of cell regions; and a memory pattern in each of the cell regions, wherein the memory pattern comprises: a first data storage pattern including a plurality of magnetic domains; a second data storage pattern including a plurality of magnetic domains, the second data storage pattern being parallel to the first data storage pattern; and at least one non-magnetic pattern between the first data storage pattern and the second data storage pattern.
[2] The magnetic domain wall movement memory device of claim 1, wherein a magnetization direction of a predetermined magnetic domain of the first data storage pattern is anti-parallel to that of a corresponding magnetic domain of the second data storage pattern facing the predetermined magnetic domain of the first data storage pattern.
[3] The magnetic domain wall movement memory device of claim 1, wherein a magnetization direction of a predetermined magnetic domain of the first data storage pattern is parallel to that of a corresponding magnetic domain of the second data storage pattern facing the predetermined magnetic domain of the first data storage pattern.
[4] The magnetic domain wall movement memory device of claim 1, wherein the first data storage pattern and the second data storage pattern comprise at least one of a ferromagnetic material, ferromagnetic alloy, and a ferrimagnetic material.
[5] The magnetic domain wall movement memory device of claim 4, wherein the memory pattern has at least one shape of a strip line shape, a "U" shape, and a serpentine shape.
[6] The magnetic domain wall movement memory device of claim 1, wherein the first data storage pattern and the second data storage pattern are different in thickness.
[7] The magnetic domain wall movement memory device of claim 1, wherein the first data storage pattern and the second data storage pattern have the same thickness.
[8] The magnetic domain wall movement memory device of claim 1, wherein the first data storage pattern and the second data storage pattern have the same material.
[9] The magnetic domain wall movement memory device of claim 1, wherein the first data storage pattern and the second data storage pattern are different in material. [10] The magnetic domain wall movement memory device of claim 1, wherein the non-magnetic pattern comprises at least one of a transition metal and a transition metal alloy. [11] The magnetic domain wall movement memory device of claim 10, wherein the transition metal comprises at least one of Cu, Cr, and Ru. [12] The magnetic domain wall movement memory device of claim 1, wherein the first data storage pattern is spaced a distance ranging from about 0.1 nm to about
100 nm from the second data storage pattern. [13] The magnetic domain wall movement memory device of claim 1, further comprising: at least one reproducing electrode structure on a side of the memory pattern, the reproducing electrode structure facing at least one magnetic domain of the magnetic domains of the first data storage pattern and second data storage pattern; and at least one recording electrode structure on the side of the memory pattern, the recording electrode structure facing at least one magnetic domain of the magnetic domains of the first data storage pattern and second data storage pattern. [14] A method of forming a magnetic domain wall movement memory device, comprising: forming a first data storage pattern including a plurality of magnetic domains; forming a non-magnetic pattern on the first data storage pattern; and forming a second data storage pattern on the non-magnetic pattern. [15] The method of claim 14, wherein the forming of the second data storage pattern, the non-magnetic pattern, and the first data storage pattern comprises: forming a first data storage layer, a non-magnetic layer, and a second data storage layer which are sequentially stacked on a substrate; and sequentially patterning the second data storage layer, the non-magnetic layer, and the first data storage layer to form a second data storage pattern, a non-magnetic layer, and a first data storage pattern, respectively. [16] The method of claim 14, wherein the non-magnetic pattern comprises at least one of a transition metal and a transition metal alloy. [17] The method of claim 16, wherein the transition metal comprises at least one of
Cu, Cr, and Ru. [18] The method of claim 14, wherein the first data storage pattern is spaced a distance ranging from about 0.1 nm to about 100 nm from the second data storage pattern. [19] The method of claim 14, wherein the first data storage pattern and the second data storage pattern are different in thickness. |
Description
DOMAIN WALL MOVEMENT MEMORY DEVICE HAVING
ARTIFICIAL ANTIFERROMAGNETISM OR ARTIFICIAL FER-
RIMAGNETISM AND METHOD OF FORMING THE SAME
Technical Field
[1] The present invention disclosed herein relates to a memory device, and more particularly, to a magnetic domain wall movement memory device. Background Art
[2] Examples of memory devices include dynamic random access memory devices
(DRAMs), static random access memory devices (SRAMs), flash memory devices, and magnetic hard disk drives. A flash memory is one kind of non-volatile semiconductor devices. However, manufacturing costs of the flash memory are expensive, and it is difficult to manufacture a large capacity flash memory. A magnetic hard disk driver is advantageous in that it has non-volatile characteristics and a high recording density. However, the magnetic hard disk driver is subject to an external impact because it has a head that mechanically is moved. Therefore, the magnetic hard disk driver is not suitable for a mobile storage device. Disclosure of Invention Technical Problem
[3] The present invention provides a memory device that can be used for a large capacity memory device, be protected against an external impact, and realize a high-speed performance.
[4] The present invention also provides a method of forming a memory device that can be used for a large capacity memory device, be protected against an external impact, and realize a high-speed performance. Technical Solution
[5] Embodiments of the present invention provide magnetic domain wall movement memory devices including a substrate including a plurality of cell regions and a memory pattern in each of the cell regions, wherein the memory pattern includes a first data storage pattern including a plurality of magnetic domains, a second data storage pattern including a plurality of magnetic domains, the second data storage pattern being parallel to the first data storage pattern, and at least one non-magnetic pattern between the first data storage pattern and the second data storage pattern.
[6] In some embodiments, a magnetization direction of a predetermined magnetic domain of the first data storage pattern may be anti-parallel to that of a corresponding
magnetic domain of the second data storage pattern facing the predetermined magnetic domain of the first data storage pattern. [7] In other embodiments, a magnetization direction of a predetermined magnetic domain of the first data storage pattern may be parallel to that of a corresponding magnetic domain of the second data storage pattern facing the predetermined magnetic domain of the first data storage pattern. [8] In still other embodiments, the first data storage pattern and the second data storage pattern may be formed of at least one of a ferromagnetic material, ferromagnetic alloy, and a ferrimagnetic material. [9] In even other embodiments, the memory pattern may have at least one shape of a strip line shape, a "U" shape, and a serpentine shape. [10] In yet other embodiments, the first data storage pattern and the second data storage pattern may be different in thickness. [11] In further embodiments, the first data storage pattern and the second data storage pattern may have the same thickness. [12] In still further embodiments, the first data storage pattern and the second data storage pattern may have the same material. [13] In even further embodiments, the first data storage pattern and the second data storage pattern may be different in material. [14] In yet further embodiments, the non-magnetic pattern may be formed of at least one of a transition metal and a transition metal alloy. [15] In yet further embodiments, the transition metal may include at least one of Cu, Cr, and Ru. [16] In yet further embodiments, the first data storage pattern may be spaced a distance ranging from about 0.1 nm to about 100 nm from the second data storage pattern. [17] In yet further embodiments, the magnetic domain movement memory device may further include at least one reproducing electrode structure on a side of the memory pattern, the reproducing electrode structure facing at least one magnetic domain of the magnetic domains of the first data storage pattern and second data storage pattern and at least one recording electrode structure on the side of the memory pattern, the recording electrode structure facing at least one magnetic domain of the magnetic domains of the first data storage pattern and second data storage pattern. [18] In other embodiments of the present invention, methods of forming a magnetic domain wall movement memory device include forming a first data storage pattern including a plurality of magnetic domains, forming a non-magnetic pattern on the first data storage pattern, and forming a second data storage pattern on the non-magnetic pattern. [19] In some embodiments, the forming of the second data storage pattern, the non-
magnetic pattern, and the first data storage pattern may include forming a first data storage layer, a non-magnetic layer, and a second data storage layer which are sequentially stacked on a substrate and sequentially patterning the second data storage layer, the non-magnetic layer, and the first data storage layer to form a second data storage pattern, a non-magnetic layer, and a first data storage pattern, respectively.
[20] In other embodiments, the non-magnetic pattern may be formed of at least one of a transition metal and a transition metal alloy
[21] In still other embodiments, the transition metal may include at least one of Cu, Cr, and Ru.
[22] In even other embodiments, the first data storage pattern may be spaced a distance ranging from about 0.1 nm to about 100 nm from the second data storage pattern.
[23] In yet other embodiments, the first data storage pattern and the second data storage pattern may be different in thickness.
Advantageous Effects
[24] According to an embodiment of the present invention, a memory pattern includes first and second data storage patterns which are parallel to one another. Since a nonmagnetic pattern stabilizing energy is disposed between the first data storage pattern and the second data storage pattern, a movement speed of magnetic domain walls of the first and second data storage patterns further increases when a current flows into the first and second data storage patterns. That is, the memory pattern having an artificial antiferromagnetism or an artificial ferrimagnetism increases an operating speed of a current driven magnetic domain wall movement memory device.
[25] According to an embodiment of the present invention, a recording electrode structure is disposed on one side of a data storage pattern. Since the recording electrode structure is disposed on a substrate, a current driven magnetic domain wall movement memory device can be protected against an external impact.
[26] According to an embodiment of the present invention, since a data storage pattern includes a plurality of magnetic domains, a current driven magnetic domain wall movement memory device can be used as a large capacity memory device. Brief Description of the Drawings
[27] FIGS. 1 and 2 are conceptual views illustrating current driven magnetic domain wall movement phenomenon.
[28] FIGS. 3 and 4 are perspective views illustrating artificial antiferromagnetism phenomenon.
[29] FIGS. 5 and 6 are perspective views illustrating artificial ferrimagnetism phenomenon.
[30] FIGS. 7 and 8 are perspective views illustrating a structure of a data storage pattern
in a memory device using an artificial antiferromagnetism or an artificial ferri- magnetism.
[31] FIGS. 9 through 11 are perspective views of a magnetic domain wall movement memory device according to an embodiment of the present invention.
[32] FIGS. 12 through 16 are perspective views illustrating a method of forming a memory device according to an embodiment of the present invention.
[33] FIGS. 17 and 18 are perspective views illustrating a method of forming a memory device according to an embodiment of the present invention. Mode for the Invention
[34] Embodiments of the present invention provide magnetic domain wall movement memory devices using an artificial antiferromagnetism or an artificial ferrimagnetism. The magnetic domain wall movement memory devices include a substrate including a plurality of cell regions and a memory pattern in each of the cell regions, wherein the memory pattern includes a first data storage pattern including a plurality of magnetic domains, a second data storage pattern including a plurality of magnetic domains, the second data storage pattern being parallel to the first data storage pattern, and at least one non-magnetic pattern between the first data storage pattern and the second data storage pattern.
[35] In other embodiments of the present invention, methods of forming a magnetic domain wall movement memory device using an artificial antiferromagnetism or an artificial ferrimagnetism. The methods include forming a first data storage pattern including a plurality of magnetic domains, forming a non-magnetic pattern on the first data storage pattern, and forming a second data storage pattern on the non-magnetic pattern.
[36] A magnetic domain wall movement memory device includes a data storage pattern having a plurality of magnetic domains. The magnetic domains are divided by an interface called a magnetic domain wall. The adjacent magnetic domains have different magnetization directions.
[37] The magnetization direction of each of the magnetic domains may be changed by a magnetic field applied from a recording electrode structure disposed on one side of the data storage pattern. However, the magnetization direction of one magnetic domain is either parallel or anti-parallel to that of another magnetic domain. Hence, since the magnetization directions of the magnetic domains are variable and either parallel or anti-parallel to each other, the magnetization directions of the magnetic domains may be used as binary data.
[38] Since the magnetic domains act as independent regions that can store data, a plurality of data can be recorded in one data storage pattern. In addition, since the magnetic
domains are consecutively arranged with a magnetic domain wall disposed therebetween as a boundary, the magnetic domain wall movement memory device can realize a higher storage density than that of a flash memory device in which regions storing data (e.g., floating gate electrodes) must be spatially separated from each other.
[39] When a predetermined current flows into the data storage pattern, certain data recorded in a predetermined magnetic domain is sequentially moved to an adjacent magnetic domain. This phenomenon is called current driven magnetic domain wall movement phenomenon. In the current driven magnetic domain wall movement phenomenon, a position of the predetermined magnetic domain in which the certain data is recorded is changed without loss of data recorded in another magnetic domain. As the current driven magnetic domain wall movement phenomenon is used, it does not need to mechanically move a recording electrode structure like a magnetic hard disk in order to change data recorded in a predetermined magnetic domain. Hence, a memory device using current driven magnetic domain wall movement phenomenon is protected against an external impact.
[40] Particularly, data to be changed is moved toward a magnetic domain adjacent to the recoding electrode structure using the current driven magnetic domain wall movement phenomenon, and then the corresponding data is changed using the recording electrode structure.
[41] Hereinafter, preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the figures, the dimensions of layers and regions are exaggerated for clarity of illustration. It will also be understood that when a layer (or film) is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Like reference numerals refer to like elements throughout.
[42] FIGS. 1 and 2 are conceptual views of current driven magnetic domain wall movement phenomenon.
[43] Referring to FIG. 1, a data storage pattern 100 includes magnetic domains 10 and 30, and has a strip line shape. For descriptive convenience, the data storage pattern 100 is divided into only three regions. A first region 10 is a magnetic domain magnetized in a long-axis direction 6 of a strip line. A third region 30 is a magnetic domain magnetized in an opposite direction of the long-axis direction 6. A magnetic domain wall defined as a second region 20 exists between the first region 10 and the third region 30. A magnetization direction of the second region 20 (i.e., the magnetic domain wall) may not
be parallel or anti-parallel to a progression direction of the strip line.
[44] The magnetization direction inside the magnetic domain wall 20 must be moved in order to move the magnetic domain wall 20 when a current is applied. Current driven magnetic domain wall movement phenomenon can be explained by physically dividing movement factors into an adiabatic term, a non-adiabatic term, a damping term, and an effective field term.
[45] As illustrated in FIG. 1, in case where the data storage pattern 100 has the strip line shape, magnetization directions of the magnetic domains can be divided into a normal direction 2 to a surface of the strip line and a plane direction 4 including the surface of the strip line perpendicular to the normal direction 2. When a current is applied to the data storage pattern 100, a magnetization direction of the magnetic domain wall 20 between the magnetic domains 10 and 30 may be deviated from the plane direction 4 including the surface of the strip line by a spin torque. The magnetization direction of the magnetic domain wall 20 may have a component of the normal direction 2.
[46] If only the adiabatic term contributes to the magnetic domain wall movement, the magnetization direction of the magnetic domain wall 20 is moved in the plane direction 4 including the surface of the strip line by the current. Then, the magnetic domain wall 20 is again moved in a direction generating a movement in the normal direction 2 by the damping term. In this case, a static magnetic energy of the data storage pattern 100 in which the magnetization direction of the magnetic domain wall 20 is in the normal direction 2 becomes an unstable state. The static magnetic energy generates a force which opposes the movement in the normal direction 2. Therefore, if only the adiabatic term contributes to the magnetic domain wall movement, the magnetic domain wall 20 may not be moved although the current is applied.
[47] If both the adiabatic term and the non-adiabatic term contribute to the magnetic domain wall movement, the effect of the damping term can efficiently cancel out when the magnetization direction inside the magnetic domain wall 20 changes due to the current. Hence, the magnetization direction is efficiently moved in the plane direction 4 including the surface of the strip line. When the magnetization direction of the magnetic domain wall 20 does not include the component of the normal direction 2, the static magnetic energy of the data storage pattern 100 becomes a stable state. The static magnetic energy may not generate a force which opposes the movement in the plane direction 4 including the surface of the strip line. Therefore, when the non- adiabatic term contributes to the magnetic domain wall movement, the magnetic domain wall can be moved by the current. That is, a current driven magnetic domain wall movement speed may depend on the non-adiabatic term.
[48] Transition-metal ferromagnetic materials (e.g., Co, Fe, Ni, etc) or their alloys (e.g.,
FeNi, etc) have a relatively low value of the non-adiabatic term. Therefore, the
unstable static magnetic energy due to the adiabatic term needs to be stabilized.
[49] Referring to FIG. 2, when a current is applied to a data storage pattern 100a, the first region 10, the second region 20, and the third region 30 are moved in the long-axis direction 6 of the strip line due to the current driven magnetic domain wall movement phenomenon to thereby define a moved first region 10a, a moved second region 20a, and a moved third region 30a, respectively. When the current is applied to the data storage pattern 100a, the magnetization direction of the magnetic domain wall 20 is deviated from the plane direction 4 including the surface of the strip line by the spin torque. The magnetization direction of the magnetic domain wall 20a includes a component of the normal direction 2.
[50] When the magnetization direction of the magnetic domain wall 20 is the normal direction 2, a static magnetic energy of the data storage pattern 100a becomes an unstable state and generates a force which opposes the movement in the normal direction 2. According to an embodiment of the present invention, the static magnetic energy of the data storage pattern 100a is stabilized using an artificial antiferro- magnetism or an artificial ferrimagnetism.
[51] FIGS. 3 and 4 are perspective views illustrating artificial antiferromagnetism phenomenon.
[52] Referring to FIG. 3, at least one non-magnetic pattern 150a is disposed between a first data storage pattern 300a and a second data storage pattern 200a which have the same thickness. When an interlayer exchange coupling energy value between the first data storage pattern 300a and the second data storage pattern 200a is a positive number, a magnetization direction of the first data storage pattern 300a is parallel to that of the second data storage pattern 200a.
[53] Referring to FIG. 4, at least one non-magnetic pattern 150b is disposed between a first data storage pattern 300b and a second data storage pattern 200b which have the same thickness. When an interlayer exchange coupling energy value between the first data storage pattern 300b and the second data storage pattern 200b is a negative number, a magnetization direction of the first data storage pattern 300b is opposite to that of the second data storage pattern 200b. That is, the magnetization direction of the first data storage pattern 300b is anti-parallel to that of the second data storage pattern 200b. This phenomenon is called as an artificial antiferromagnetism. The artificial antiferromagnetism is affected by a material and a thickness of the non-magnetic pattern 150b. According to an embodiment of the present invention, the artificial antiferromagnetism may be used in a current driven memory device. A static magnetic energy of the memory device having the artificial antiferromagnetism is stabilized to increase a magnetic domain wall movement speed.
[54] FIGS. 5 and 6 are perspective views illustrating artificial ferrimagnetism
phenomenon.
[55] Referring to FIG. 5, at least one non-magnetic pattern 150c is disposed between a first data storage pattern 300c and a second data storage pattern 200c which are different in thickness. When an interlay er exchange coupling energy value between the first data storage pattern 300c and the second data storage pattern 200c is a positive number, a magnetization direction of the first data storage pattern 300c is parallel to that of the second data storage pattern 200c.
[56] Referring to FIG. 6, at least one non-magnetic pattern 150d is disposed between a first data storage pattern 300d and a second data storage pattern 20Od which are different in thickness. When an interlay er exchange coupling energy value between the first data storage pattern 300d and the second data storage pattern 20Od is a negative number, a magnetization direction of the first data storage pattern 300d is opposite to that of the second data storage pattern 20Od. The magnetization direction of the first data storage pattern 300d is anti-parallel to that of the second data storage pattern 20Od. This phenomenon is called as artificial ferrimagnetism. The artificial ferri- magnetism is affected by a material and a thickness of the non-magnetic pattern 150d. A static magnetic energy of a memory device having the artificial ferrimagnetism is stabilized to increase a magnetic domain wall movement speed.
[57] FIGS. 7 and 8 are perspective views illustrating a structure of a data storage pattern in a memory device using an artificial antiferromagnetism or an artificial ferrimagnetism.
[58] Referring to FIG. 7, according to an embodiment of the present invention, a magnetic domain wall movement memory device having an artificial antiferromagnetism includes a first data storage pattern 300e and a second data storage pattern 20Oe. At least one non-magnetic pattern 150e is disposed between the first data storage pattern 300e and the second data storage pattern 20Oe. A memory pattern 9Oe includes the first data storage pattern 300e, the second data storage pattern 20Oe, and the non-magnetic pattern 150e.
[59] The first data storage pattern 300e includes a plurality of magnetic domains and has a strip line shape. For descriptive convenience, the first data storage pattern 300e is divided into only three regions. A first region 310e is called a magnetic domain magnetized in a long-axis direction 6 of a strip line. A third region 330e is called a magnetic domain magnetized in an opposite direction of the long- axis direction 6. A magnetic domain wall defined as a second region 32Oe exists between the first region 310e and the third region 330e. A magnetization direction of the second region 330e may not be parallel or anti-parallel to the long-axis direction 6 of the strip line.
[60] Referring to FIG. 8, in the magnetic domain wall movement memory device having the artificial antiferromagnetism, when a current is applied to the first and second data
storage patterns 30Oe and 20Oe, the first and second regions 310e and 21Oe, the second regions 32Oe and 22Oe, and the third regions 330e and 23Oe are moved in the long-axis direction 6 of the strip line to define moved first and second regions 310f and 21Of, moved second regions 32Of and 22Of, and moved third regions 330f and 23Of, respectively.
[61] At least one non-magnetic pattern 150f is disposed between a first data storage pattern 300f and a second data storage pattern 20Of. The non-magnetic pattern 150f stabilizes a static magnetic energy of the magnetic domain wall movement memory device. Hence, when a current is applied to the first data storage pattern 300f, a force of resistance against a movement of magnetic domain wall decreases.
[62] FIGS. 9 through 11 are perspective views of a magnetic domain wall movement memory device according to an embodiment of the present invention.
[63] Referring to FIG. 9, a magnetic domain wall movement memory device according to an embodiment of the present invention includes first and second data storage patterns 300 and 200 and at least one non-magnetic pattern 150 between the first and second data storage patterns 300 and 200. A memory pattern 90 includes the first and second data storage patterns 300 and 200 and the non-magnetic pattern 150. A magnetization direction of a predetermined magnetic domain 301 of the first data storage pattern 300 is anti-parallel to that of a magnetic domain 201 of the second data storage pattern 200 facing the predetermined magnetic domain 301 of the first data storage pattern 300. The magnetic domain wall movement memory device includes at least one reproducing electrode structure 230 facing at least one magnetic domain at a side of the memory pattern 90 and at least one recording electrode structure facing at least another magnetic domain at the side of the memory pattern 90.
[64] A substrate 400 includes a plurality of cell regions which are two-dimensionally arranged. A memory pattern including a plurality of magnetic domains is disposed in each of the cell regions. The first data storage pattern 300 is disposed on the substrate 400. The substrate 400 may include an insulating substrate or a semiconductor s ubstrate. A device driving the magnetic domain wall movement memory device of the present invention is disposed on the substrate 400.
[65] An insulating layer is disposed between the substrate 400 and the memory pattern 90.
The insulating layer may include a silicon oxide film or a silicon nitride film.
[66] The memory pattern 90 has at least one shape of a strip line shape as illustrated in
FIG. 9, a serpentine shape as illustrated in FIG. 10, and a "U" shape as illustrated in FIG. 11. The first data storage pattern 300 is parallel to the second data storage pattern 200.
[67] The first and second data storage patterns 300 and 200 may be formed of at least one of ferromagnetic materials, their alloys, and ferrimagnetic materials. The ferromagnetic
materials may include transition-metal ferromagnetic materials such as Fe, Ni, Co, etc.
[68] The first and second data storage patterns 300 and 200 include a magnetic domain wall between the magnetic domains. The first and second data storage patterns 300 and 200 are individually divided into a storage region 242 and a reservoir region 244. The storage region 242 includes a region in which the first and second data storage patterns 300 and 200 are magnetized by the recording electrode structure 220. The reservoir region 244 temporarily stores data of the storage region 242.
[69] The first data storage pattern 300 and the second data storage pattern 200 may be different in material. The first data storage pattern 300 and the second data storage pattern 200 may be different in width W. According to an embodiment of the present invention, the first data storage pattern 300 and the second data storage pattern 200 may be different in thickness t.
[70] According to an embodiment of the present invention, the memory pattern 90 is parallel to the substrate 400, but the present invention is not limited thereto. For example, the memory pattern 90 may be inclined or perpendicular to the substrate 400.
[71] Referring to FIG. 9, according to an embodiment of the present invention, a magnetic domain wall movement memory device includes interconnections 202 connected to the first data storage pattern 300. According to an embodiment of the present invention, the interconnections 202 connected to the first data storage pattern 300 are electrically connected to a current supply circuit 204 generating a current flowing into the first data storage pattern 300. The first data storage pattern 300 is electrically connected to the second data storage pattern 200 through the non-magnetic pattern 150. The first data storage pattern 300 or the second data storage pattern 200 has lower resistance than the non-magnetic pattern 150. The first and second data storage patterns 300 and 200 have greater electrical conductivity than the non-magnetic pattern 150.
[72] Again referring to FIG. 9, the non-magnetic pattern 150 may be formed of at least one of transition metals (i.e., 3d, 4d, and 5d metals of a periodic table) and their alloys. Particularly, the transition metal may include at least one of Cu, Cr, and Ru. A distance h between the first data storage pattern 300 and the second data storage pattern 200 is within a range of from about 0.1 nm to about 100 nm. The non-magnetic pattern 150 includes a plurality of layers which are different in material.
[73] According to an embodiment of the present invention, as described above, the memory device includes the recording electrode structure 220. The recording electrode structure 220 may be formed of a conductive material. When a current flows into the recording electrode structure 220, a predetermined magnetic domain 301 of the first data storage pattern 300 facing the recording electrode structure 220 is magnetized in a specific direction. Therefore, a predetermined magnetic domain 201 of the second data storage pattern 200 facing the first data storage pattern 300 is magnetized in an
opposite direction of the specific direction. A direction of the current flowing into the recording electrode structure 220 is changed according to data stored in the first data storage pattern 300. The current flowing into the recording electrode structure 220 has a pulse shape.
[74] Again referring to FIG. 9, when the recording electrode structure 220 is disposed on one side of the memory pattern 90, and a current is applied to the recording electrode structure 220, the predetermined magnetic domain 301 of the first data storage pattern 300 most adjacent to the recording electrode structure 220 is magnetized in a predetermined direction. The predetermined magnetic domain 201 of the second data storage pattern 200 facing the adjacent magnetic domain 301 is magnetized in an opposite direction of the magnetization direction of the adjacent magnetic domain 301.
[75] According to a modified embodiment of the present invention, the recording electrode structure 220 is disposed on a position of a side of the memory pattern 90, and the reproducing electrode structure 230 is disposed on another position of the side of the memory pattern 90. The magnetization direction of the predetermined magnetic domain 301 of the first data storage pattern 300 is parallel to that of the predetermined magnetic domain 201 of the second data storage pattern 200.
[76] The reproducing electrode structure 230 may be formed of a conductive material. A sensor detecting a magnetization direction of a predetermined magnetic domain is disposed at an intersection of the reproducing electrode structure 230 and the memory pattern 90. The sensor is electrically connected to the reproducing electrode structure 230. The sensor may include a tunneling magnetoresistance sensor or a giant magne- toresistance sensor.
[77] FIGS. 12 through 16 are perspective views illustrating a method of forming a memory device according to an embodiment of the present invention.
[78] Referring to FIG. 12, a conductive layer is formed on a substrate 400. The conductive layer may include at least one of a metal film, a metal suicide film, and a doped polysilicon film. A first photoresist pattern is formed on the conductive layer. The conductive layer is etched using the first photoresist pattern as a mask to form a recording electrode structure 220 and a reproducing electrode structure 230. A sensor detecting a magnetization direction of a magnetic domain is disposed on the reproducing electrode structure 230. The sensor is electrically connected to the reproducing electrode structure 230. The sensor may include a tunneling magnetoresistance sensor or a giant magnetoresistance sensor.
[79] Referring to FIG. 13, a first insulating layer 210 is formed on the reproducing electrode structure 230. The first insulating layer 210 may include a dielectric. The first insulating layer 210 may include at least one of a silicon oxide film and a silicon nitride film.
[80] Referring to FIG. 14, a first data storage layer is formed on the first insulating layer
210. A second photoresist pattern is formed on the first data storage layer. The first data storage layer is etched using the second photoresist pattern as a mask to form a first data storage pattern 300.
[81] The first data storage pattern 300 may be formed of at least one of a ferromagnetic material, their alloy, and a ferrimagnetic material. The ferromagnetic material may include transition-metal ferromagnetic materials such as Fe, Ni, Co, etc. The first data storage pattern 300 has at least one shape of a strip line shape, a "U" shape, and a serpentine shape. The first data storage pattern 300 includes a plurality of magnetic domains and a magnetic domain wall between the magnetic domains. The first data storage pattern 300 crosses over the reproducing electrode structure 230.
[82] Referring to FIG. 15, a non-magnetic layer is formed on the first data storage pattern
300. The non-magnetic layer may be formed of at least one of transition metals (i.e., 3d, 4d, and 5d metals of a periodic table) and their alloys. Particularly, the transition metal may include at least one of Cu, Cr, and Ru. The non-magnetic layer may include a conductive layer. The non-magnetic layer 150 includes a plurality of layers which are different in material. The non-magnetic layer is patterned to form a non-magnetic pattern 150.
[83] Referring to FIG. 16, a second data storage layer is formed on the non-magnetic pattern 150. A third photoresist pattern is formed on the second data storage layer. The second data storage layer is etched using the third photoresist pattern as a mask to form a second data storage pattern 200. The second data storage pattern 200 is parallel to that of the first data storage pattern 300 in a long-axis direction. The first data storage pattern 300 and the second data storage pattern 200 may be different in thickness. A distance h between the first data storage pattern 300 and the second data storage pattern 200 is within a range of from about 0.1 nm to about 100 nm.
[84] FIGS. 17 and 18 are perspective views illustrating a method of forming a memory device according to an embodiment of the present invention.
[85] Referring to FIG. 17, as illustrated in FIGS. 12 and 13, a recording electrode structure 220 and a reproducing electrode structure 230 are formed on a substrate 400. There is formed a first insulating layer 210 covering the recording electrode structure 220 and the reproducing electrode structure 230. There is formed a first data storage layer 300g, a non-magnetic layer 150g, and a second data storage layer 20Og which are sequentially stacked on the first insulating layer 210. Characteristics of the first data storage layer 300g, the non-magnetic layer 150g, and the second data storage layer 20Og are the same as described in FIGS. 12 through 16.
[86] Referring to FIG. 18, the second data storage layer 300g, the non-magnetic layer
150g, and the first data storage layer 20Og are sequentially patterned to form the
second data storage pattern 200, the non-magnetic layer 150, and the first data storage pattern 300, respectively. The patterning process may include a photolithography process and an etch process. An advantage of this embodiment is to provide simplified manufacturing processes. [87] According to a modified embodiment of the present invention, at least one of the recording electrode structure 220 and the reproducing electrode structure 230 is formed on the second data storage pattern 200.