Magnetic tracks, information storage devices using magnetic domain wall movement, and methods of manufacturing the same

Information storage devices and methods of manufacturing the same are provided. A magnetic track of the information storage device includes a magnetic layer in which at least one magnetic domain forming region and at least one magnetic domain wall forming region are alternately disposed in a lengthwise direction. The at least one magnetic domain forming regions has a different magnetic anisotropic energy relative to the at least one magnetic domain wall forming region. An intermediate layer is formed under the magnetic layer. The intermediate layer includes at least one first material region and at least one second material region. Each of the at least one first material regions and the at least one second material regions corresponds to one of the at least one magnetic domain forming regions and the at least one magnetic domain wall forming regions.

PRIORITY STATEMENT

This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2007-0093847, filed on Sep. 14, 2007, in the Korean Intellectual Property Office (KIPO), the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

Description of the Related Art

Nonvolatile information storage devices such as hard disk drives (HDDs) and nonvolatile random access memories (RAMs) retain recorded information even when power is cut-off.

A conventional HDD stores recorded information using a rotating part. The rotating part may wear down over time, which increases the possibility of operational failure. This increased possibility of operational failure reduces reliability.

An example of a conventional non-volatile RAM is a flash memory. Conventional flash memories do not use a rotating part. As such, conventional flash memories do not suffer from the same wear as conventional HDDs. However, conventional flash memories have relatively slow reading and writing speeds, relatively short life spans, and relatively small storage capacity when compared to a conventional HDD. In addition, conventional flash memories have relatively high manufacturing costs.

Another nonvolatile information storage device uses magnetic domain wall movement of a magnetic material. In these conventional information storage devices, a minute magnetic region—a ferromagnetic substance—is referred to as a magnetic domain. A boundary portion between magnetic domains having different magnetization directions is referred to as a magnetic domain wall. The magnetic domain wall may be moved by applying a current or an external magnetic field to a magnetic layer.

In one example, bit movement may be controlled by artificially forming a pinning site for dividing a continuous storage region using a magnetic domain wall between magnetic domains and by maintaining constant bits. In this conventional method, however, the pinning sites must be artificially formed, and thus, manufacturing processes are relatively complicated.

SUMMARY

Example embodiments relate to magnetic tracks, information storage devices and methods of manufacturing the same, for example, magnetic tracks, information storage devices including magnetic tracks in which a magnetic domain and a magnetic domain wall are formed, and methods of manufacturing the same.

Example embodiments provide magnetic tracks and information storage devices for controlling a magnetic domain wall without artificially forming a pinning site. Example embodiments also provide methods of manufacturing information storage devices.

At least one example embodiment provides a magnetic track. The magnetic track may include an intermediate layer and a magnetic layer. The intermediate layer may be arranged on a substrate. The intermediate layer may include at least one first material region forming a magnetic domain and at least one second material region forming a magnetic domain wall arranged alternately on the substrate. The magnetic layer may be formed on the intermediate layer in a lengthwise direction. The magnetic layer may include at least one magnetic domain forming region and at least one magnetic domain wall forming region arranged alternately in the lengthwise direction.

At least one example embodiment provides an information storage device. The information storage device may include a magnetic track having a plurality of magnetic domains. A current applying unit may be connected or coupled to the magnetic track. A read/write unit may also be included in the information storage device. The magnetic track may include an intermediate layer formed on a substrate. The intermediate layer may include a first material region forming a magnetic domain and a second material region forming a magnetic domain wall. The first and second material regions may be alternately disposed on the substrate. A magnetic layer may be formed on the intermediate layer in a lengthwise direction. The magnetic layer may include a magnetic domain forming region and a magnetic domain wall forming region alternately formed in the lengthwise direction.

According to at least some example embodiments, a magnetic anisotropic energy of the magnetic domain forming region may be between about 2×103and about 107J/m3, inclusive. A magnetic anisotropic energy of the magnetic domain wall forming region may be between about 10 and about 103J/m3, inclusive.

At least one other example embodiment provides a method of manufacturing a magnetic track for an information storage device. According to at least this example embodiment, a seed layer may be formed on a substrate. An intermediate layer may be formed on the seed layer. The intermediate layer may include at least one first material region and at least one second material region arranged alternately. A magnetic layer may be formed on the intermediate layer. The magnetic layer may include at least one magnetic domain forming region and at least one magnetic domain wall forming region arranged alternately on the intermediate layer.

At least one other example embodiment provides a method of manufacturing an information storage device. According to at least this example embodiment, a seed layer may be formed on a substrate. An intermediate layer may be formed on the seed layer. The intermediate layer may include a first material region forming a magnetic domain and a second material region forming a magnetic domain wall. The first and second material regions may be alternately disposed on the seed layer. A magnetic layer may be formed on the intermediate layer. The magnetic layer may include a magnetic domain forming region and a magnetic domain wall forming region alternately formed in the lengthwise direction.

According to at least some example embodiments, the first material region may be formed of Pt and the second material region may be formed of Ru. The magnetic layer may be a multilayer or stack structure including CoFe and Pt.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Various example embodiments of the present invention will now be described more fully with reference to the accompanying drawings in which some example embodiments of the invention are shown. In the drawings, the thicknesses of layers and regions are exaggerated for clarity.

Detailed illustrative embodiments of the present invention are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments of the present invention. This invention may, however, may be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein.

Accordingly, while example embodiments of the invention are capable of various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments of the invention to the particular forms disclosed, but on the contrary, example embodiments of the invention are to cover all modifications, equivalents, and alternatives falling within the scope of the invention. Like numbers refer to like elements throughout the description of the figures.

Hereinafter, example embodiments will be described in detail with reference to the attached drawings. In the description, the detailed descriptions of well-known functions and structures have been omitted so as not to hinder the understanding of the present invention.

FIG. 1illustrates a magnetic track of an information storage device according to an example embodiment. Referring toFIG. 1, a magnetic track10of the information storage device may include a plurality of magnetic domains12and a plurality of magnetic domain walls14arranged alternately in a lengthwise direction.

The direction of rotation of electrons (e.g., the direction of a magnetic moment) may be the same throughout the magnetic domain12. The size of the magnetic domain12and its magnetization direction may be controlled by the shape and size of a magnetic material and/or external energy. The magnetic domain wall14may serve as a boundary portion of magnetic domains having different magnetization directions. A spin exchange energy of the magnetic domain wall14may be smaller than a spin exchange energy of the magnetic domain12thereby forming a more stable energy state. Because the magnetic domain wall14is a pinning site having a relatively small magnetic anisotropic energy, bit movement of the magnetic domain wall14is possible and data recorded in a magnetic layer may be retained more stably.

The magnetic domain wall14may be moved by a current or an external magnetic field applied to the magnetic material. The magnetic anisotropic energy of the magnetic domain12may be between about 2×103and about 107J/m3, inclusive. The magnetic anisotropic energy of the magnetic domain wall14may be between about 10 and about 103J/m3, inclusive.

An information storage device may include the magnetic track ofFIG. 1, a current applying unit and a read/write unit coupled thereto. The current applying unit may move the magnetic domain wall14by, for example, applying a current each side portions of the magnetic track. A magnetic resistance device may be used as a reading unit to read information stored in the magnetic track.

FIGS. 2A and 2Bare cross-sectional views of example structures of magnetic tracks of information storage devices according to example embodiments.

Referring toFIG. 2A, magnetic track30may include a seed layer23, intermediate layers25and27, and magnetic layer29arranged sequentially on substrate21. The magnetic layer29may be formed by alternately disposing magnetic domain forming regions22and magnetic domain wall forming regions24on the intermediate layers25,27.

Referring toFIG. 2B, magnetic track40may include a seed layer33, intermediate layers35and37and a magnetic layer39arranged sequentially on substrate31. The magnetic layer39may be formed by alternately disposing magnetic domain forming regions32and magnetic domain wall forming regions34on the intermediate layers35,37.

Referring toFIGS. 2A and 2B, the magnetic anisotropic energy of the magnetic domain forming regions22and32may be between about 2×103and about 107J/m3, inclusive. According to example embodiments, the magnetic anisotropic energy of the magnetic domain forming regions22and32may be similar, substantially similar, or different. The magnetic anisotropic energy of the magnetic domain wall forming regions24and34may be between about 10 and about 103J/m3, inclusive. According to example embodiments, the magnetic anisotropic energy of the magnetic domain wall forming regions24and34may be the same, substantially the same, or different.

As shown inFIGS. 2A and 2B, the magnetic tracks30and40may differ in that the intermediate layers25,27and the intermediate layers35,37may be structured differently. These differences will be discussed in more detail below.

The magnetic domain wall is a boundary portion between magnetic domains, and thus, may be smaller than the size of the magnetic domain. A magnetic domain may include a portion of a region in which magnetic domain walls are formed.

Still referring toFIGS. 2A and 2B, the magnetic layers29and39may be formed of, for example, Co or a Co alloy and Pt or may be formed of Co or a Co alloy and Pd. The magnetic layers29and39may be formed to have a multi-layer or stack structure in which n (e.g., 1≦n≦25) layers are stacked. In at least this example, the Co or the Co alloy may be, for example, CoCr, CoCu, CoTb, CoFeTb, CoFeGd, CoFeNi, a combination thereof, or the like.

Magnetic anisotropic energies of the magnetic layers29and39may vary according to materials formed under the magnetic layers29and39. According to example embodiments, materials used in forming the intermediate layers25,27,35, and37under the magnetic layers29and39may be changed so that magnetic anisotropic energies of the magnetic layers29and39vary in different portions of the magnetic layers29and39. According to example embodiments, portions of the intermediate layers2535may be referred to as first material regions, whereas portions of the intermediate layers27and37may be referred to as second material regions. Accordingly, first material regions25and35and second material regions27and37may be alternately formed as intermediate layers25and27and35and37under the magnetic layers29and39, respectively.

Referring back toFIG. 2A, after the first material region25is formed on the seed layer23, the patterned second material region27may be formed so that the first material region25and the second material region27may be disposed alternately with a given step difference. Accordingly, the magnetic domain forming regions22may have down-sloping sides and an upper surface that is arranged at a lower level than an upper surface of the magnetic domain wall forming regions24.

In addition, referring toFIG. 2B, the first material region35and the second material region37may be alternately disposed on the seed layer33on the same or substantially the same plane. As shown, the upper surfaces of the first material region35and the second material region37may be planar or substantially planar.

The first material regions25and35may be formed of, for example, Pt, and/or the second material regions27and37may be formed of, for example, Ru.

The seed layers23and33may be formed of, for example, a material selected from the group consisting of or including Ta, TaO2, Ti, TiO2, a combination thereof, or the like.

FIGS. 3A through 3Fillustrate a method of manufacturing a magnetic track of an information storage device according to an example embodiment. The example embodiment shown inFIGS. 3A through 3Fmay be used to manufacture the magnetic track shown inFIG. 2A, for example. Referring toFIGS. 3A and 3B, a seed layer43, a first material region45, and a second material region47may be sequentially formed on a silicon substrate41. In at least this example embodiment, the seed layer43may be formed of Ta, and the first material region45may be formed of Pt. The second material region47may be formed of, for example, Ru. The seed layer43, the first material region45, and the second material region47may be formed at a given (e.g., normal) temperature using a sputtering process or the like.

Referring toFIGS. 3C through 3F, a mask48may be formed on the second material region47. The second material region47may be patterned using, for example, reactive ion etching (RIE). The mask48may be removed. By removing the mask48, the first material region45and the second material region47may be alternately disposed with a given step difference. A magnetic layer49may be formed on the first material region45and the patterned second material region47using, for example, an atomic layer deposition (ALD) process. The magnetic layer49may be formed to have a multi-layer or stack structure by repeatedly forming a CoFe/Pt layer, for example.

Referring toFIG. 3F, the magnetic layer49may include a magnetic domain forming region42contacting the first material region45of the intermediate layers45and47and a magnetic domain wall forming region44contacting the second material region47. As such, a magnetic track50in which the first material region45and the second material region47are alternately formed under the magnetic layer49, may be manufactured.

FIGS. 4A and 4Bare graphs illustrating magnetic characteristics of a magnetic track according to an example embodiment. In these example characteristics, after forming the magnetic track having the structure ofFIG. 2B, a magnetic moment characteristic (M-H curve) according to an applied magnetic field was measured to determine a magnetic characteristic of a magnetic layer according to a material formed under the magnetic layer of the magnetic track. Sample A inFIGS. 4A and 4Bincludes a seed layer formed of Ta on a silicon substrate and an intermediate layer formed of Pt to a thickness of about 100 Å. A magnetic layer is formed by stacking a CoFe/Pt layer five times. Sample B inFIGS. 4A and 4Bincludes a seed layer formed of Ta on a silicon substrate and a Ru layer having a thickness of 300 Å formed on an intermediate layer formed of Pt having a thickness of 100 Å. A magnetic layer is formed by stacking a CoFe/Pt layer five times.

Referring toFIGS. 4A and 4B, magnetic anisotropic energies of samples A and B are different from each other resulting in a step difference. In addition, the magnetic anisotropic energy of sample A is relatively large.

As described above, according to example embodiments, a material formed under a magnetic layer may be changed to induce a magnetic domain and a magnetic domain wall forming region of the magnetic layer so that an information storage device for controlling a magnetic domain wall is realized.

In methods of manufacturing information storage devices according to example embodiments, information storage devices, which have simpler and/or easier manufacturing processes are provided.