Patent ID: 12236987

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. In addition to the illustrative aspects, aspects, and features described above, further aspects, aspects, and features will become apparent by reference to the drawings and the following detailed description. The description of elements in each figure may refer to elements of proceeding figures. Like numbers may refer to like elements in the figures, including alternate aspects of like elements.

The disclosure relates in some aspects to various apparatuses, systems, methods, and media for magnetic recording and data storage. In some aspects, areal density in magnetic recording media can be improved using a capping layer that has a high magnetic moment and low magnetic exchange coupling between grains. In one aspect, a metal-doped capping layer can have a high percentage of Co to achieve a high magnetic moment without suffering from a high grain-to-grain exchange coupling. Therefore, magnetic recording media using the disclosed metal-doped capping layer can achieve higher areal density. Some exemplary magnetic recording media include perpendicular magnetic recording (PMR) media, heat-assisted magnetic recording (HAMR) media, microwave-assisted magnetic recording (MAMR) media, and shingled magnetic recording (SMR) media.

In some designs, a capping layer may consist of various materials, for example, Co, Cr, Pt, and B. Increasing the percentage of Co in the capping layer may increase the magnetic moment of the magnetic recording media. However, simply increasing the Co percentage in the capping layer may not result in higher areal density because higher Co percentage in the capping layer can increase grain-to-grain magnetic exchange coupling that leads to wider track-width and lower areal density. In some aspects, this disclosure relates to a capping layer for magnetic recording media doped with a small amount of metal to control grain-to-grain exchange coupling of the capping layer. In some aspects, the capping layer can be etched to obtain a smoother air bearing surface such that a thinner protective layer can be deposited on the capping layer (e.g., to reduce head to media spacing and possibly increase recording density just for this reason).

FIG.1is a top schematic view of a data storage device100(e.g., disk drive or magnetic recording device) configured for magnetic recording comprising a slider108and a magnetic recording medium102according to one or more aspects of the disclosure. Disk drive100may comprise one or more disks/media102to store data. Disk/media102resides on a spindle assembly104that is mounted to a drive housing106. Data may be stored along tracks in the magnetic recording layer of disk102. The reading and writing of data is accomplished with the head108(slider) that may have both read and write elements (108aand108b). The write element108ais used to alter the properties of the magnetic recording layer of disk102and thereby write information thereto. In one aspect, head108may have magneto-resistive (MR) based elements, such as tunnel magneto-resistive (TMR) elements for reading, and a write pole with coils that can be energized for writing. In operation, a spindle motor (not shown) rotates the spindle assembly104, and thereby rotates the disk102to position the head108at a particular location along a desired disk track107. The position of the head108relative to the disk102may be controlled by the control circuitry110(e.g., a microcontroller). Some embodiments of the data storage device100are HAMR, EAMR, or non-EAMR magnetic data recording systems, including perpendicular magnetic recording (PMR) disk drives or magnetic tape drives.

FIG.2is a side schematic view of the slider108and magnetic recording medium102ofFIG.1. The magnetic recording medium102may have a capping layer (e.g., a capping layer shown inFIG.3) configured to have a high magnetic moment and low grain-to-grain exchange coupling to increase the recording areal density of the medium102in accordance with one or more aspects of the disclosure. The slider108comprises a write element (e.g., writer)108aand a read element (e.g., reader)108bpositioned along an air bearing surface (ABS)108cof the slider for writing information to, and reading information from, respectively, the media102.

FIG.3is a side schematic view of a magnetic recording medium300with a metal-doped capping layer in accordance with one aspect of the disclosure. In some embodiments, the magnetic recording medium300may be a PMR or HAMR medium. The magnetic recording medium300has a stacked structure with a substrate302at a bottom/base layer, a seed layer306on the substrate302, a magnetic recording layer (MRL)310on the seed layer306, a capping layer312on the MRL310, an overcoat layer314on the capping layer312. In some examples, the MRL310may include one or more magnetic recording layers. In some embodiments, the medium300may have a lubricant layer316on the overcoat layer314.

In some aspects, the substrate302may be made of one or more materials such as an Al alloy, NiP plated Al, glass, glass ceramic, and/or combinations thereof. In some aspects, the seed layer306may be made of MgO or other suitable materials known in the art. In one embodiment, the seed layer306has a certain lattice structure that can determine a lattice structure of a layer (e.g., MRL310) grown/deposited on the seed layer306. In some aspects, the MRL310may be made of FePt or an alloy selected from FePtX, where X is a material selected from Cu, Ni, and combinations thereof. In some aspects, the MRL310may be made of a CoPt alloy. In some aspects, the overcoat layer314may be made of carbon. In some aspects, the lubricant layer316may be made of a polymer-based lubricant. In some aspects, the MRL310may include a plurality of recording layers (e.g., RL 1, RL 2, RL 3, RL 4, RL 5) interleaved with exchange coupling layers (e.g., ECL 1, ECL 2, ECL 3, ECL 4, ECL 5). The recording layers may have the same thickness or different thicknesses. In one example, RL 1 may be 2 nm thick, RL 2 may be 2 nm thick, RL 3 may be 1.4 nm thick, RL 4 may be 1.25 nm thick, and RL 5 may be 1.25 nm thick. The exchange coupling layers may have the same thickness or different thicknesses. In one example, ECL 1 may be 1 nm thick, ECL 2 may be 1 nm thick, ECL 3 may be 0.58 nm thick, ECL 4 may be 0.57 nm thick, and ECL 5 may be 1.45 nm thick. In other embodiments, the MRL310may include more or fewer exchange coupling layers and/or recording layers.

In one embodiment, the capping layer312can be doped with an effective amount of metal to control grain-to-grain exchange coupling. In another embodiment, the capping layer312can be doped with an effective amount of Ru or Ta. Ru or Ta doping may improve the corrosion robustness of the capping layer. In some aspects, the capping layer312may include Co, Pt, Cr, B, and combinations thereof. In one example, the capping layer312may include an alloy consisting of Co, Pt, Cr, and B in various proportions.

In some examples, the capping layer312can include these composition options: 54.5Co-17Pt-9.5Cr-12B-7Ru, 56.5Co-26Pt-6.5Cr-8B-3Ru, 58.5Co-24Pt-6.5Cr-8B-3Ru, 53.5Co-24Pt-9.5Cr-10B-3Ru, 60.5Co-24Pt-5.5Cr-7B-3Ru, 62.5Co-24Pt-4.5Cr-6B-3Ru, 62.5Co-24Pt-6.5Cr-4B-3Ru, 59Co-24Pt-6Cr-10B-1Ru, or variations thereof. In one embodiment, the capping layer312may include an alloy containing higher than 60 atomic percent of Co. Increasing the percentage of Co in the capping layer312can increase the magnetic moment of the capping layer312, thus increasing the overall magnetic moment of the medium300. However, increasing the magnetic moment of the capping layer can also increase the grain-to-grain exchange coupling (e.g., lateral exchange coupling) that could reduce the areal density of the medium.

In some aspects, the capping layer312can be further processed in a planarization procedure to smooth out a top surface before the overcoat314is formed on the capping layer312. After planarization, the capping layer312may have a thickness between 5 Angstrom (Å) and 20 Å and a surface roughness (Ra) (e.g., Ra analyzed at 1 micrometer (μm)×1 μm scan surface) less than 4 Å. In an exemplary planarization procedure, the capping layer312can be etched using a non-reactive gas or noble gas, for example, Ar, Kr, Xe, etc. However, etching the capping layer312can increase the lateral grain-to-grain exchange coupling of the capping layer12that results in wider track width and reduced areal density of the medium300. In some embodiments, the capping layer312can be doped with an effective amount of metal (e.g., Ru or Ta) to control or prevent the increase of lateral grain-to-grain exchange coupling after etching or planarization. In some embodiments, the capping layer312is doped with Ru in a range of about 1 atomic percent to about 5 atomic percent, inclusive. In one example, the capping layer132is doped with Ru in a range of about 2 atomic percent to about 4 atomic percent, inclusive. In one example, the capping layer132is doped with about 3 atomic percent (e.g., 2.5 atomic percent to 3.5 atomic percent) of Ru. In one example, the capping layer132is doped with Ta in a range of about 1 atomic percent to about 3 atomic percent, inclusive. In one example, the capping layer132is doped with about 2 atomic percent (e.g., 1.5 atomic percent to 2.5 atomic percent) of Ta.

The terms “above,” “below,” “on,” and “between” as used herein refer to a relative position of one layer with respect to other layers. As such, one layer deposited or disposed on, above, or below another layer may be directly in contact with the other layer or may have one or more intervening layers. Moreover, one layer deposited or disposed between layers may be directly in contact with the layers or may have one or more intervening layers.

FIG.4is a flowchart of a process400for fabricating a medium with a metal-doped capping layer in accordance with some aspects of the disclosure. In one aspect, the process400can be used or modified to fabricate the medium described above in relation toFIG.3. In some aspects, the fabricated medium may be used in the data storage device100ofFIG.1.

In block402, the process provides a substrate (e.g., substrate302). In some aspects, the substrate can be made of one or more materials such as an Al alloy, NiP plated Al, glass, glass ceramic, and/or combinations thereof. In block404, the process provides a seed layer (e.g., seed layer306) on the substrate. In some aspects, the seed layer may be on a heat sink layer already formed on the substrate for HAMR. In block406, the process provides a magnetic recording layer (e.g., MRL310) on the seed layer. In one example, the magnetic recording layer may include one or more magnetic recording layers for storing data magnetically, for example, PMR and HAMR.

In block408, the process provides a capping layer (e.g., capping layer312) on the substrate, for example, on the magnetic recording layer. In one example, the capping layer includes an alloy containing Co, Cr, Pt, and B. In one example, the capping layer may contain more than 50 atomic percent of Co (e.g., more than 60 atomic percent Co). Higher percentage of Co can increase the magnetic moment of the capping layer. In one embodiment, the capping layer may be doped with an effective amount of metal (e.g., Ru or Ta) to control lateral grain-to-grain magnetic exchange coupling in the capping layer. In some examples, the capping layer is doped with Ru in a range of about 1 atomic percent to about 5 atomic percent, inclusive. In one example, the capping layer is doped with Ru in a range of about 2 atomic percent to about 4 atomic percent, inclusive. With the doped metal (e.g., Ru or Ta), the capping layer can have a higher magnetic moment without a significant increase in grain-to-grain exchange coupling.

In block410, the process planarizes the capping layer. Planarization can make the top surface of the capping layer smoother such that a thinner overcoat layer (e.g., overcoat314) can be used to cover the capping layer. A thinner overcoat layer can improve the magnetic recording performance of the medium because the distance between the slider and the magnetic recording layer can be reduced by using a thinner overcoat layer that is positioned between the slider and the magnetic recording layer. The planarization of the metal-doped capping layer allows the magnetic recording layer (e.g., MRL310) to be optimized for magnetic performance and not constrained by surface roughness of the medium if planarization is not used. In one example, the planarization process can etch the capping layer using a non-reactive gas or noble gas (e.g., Ar, Kr, Xe). The etching process removes more lighter elements than elements heavier (e.g., Ru, Ta, Pt) than the etching gas (e.g., Kr). Therefore, after etching, increased Pt content in the capping layer can increase the grain-to-grain exchange coupling in the capping layer. However, the capping layer is doped with an effective amount (e.g., between 1 to 5 percent) of metal (e.g., Ru or Ta) to control or reduce the grain-to-grain exchange coupling in the capping layer such that the magnetic moment of the capping layer can be increased without undesirable increase of grain-to-grain exchange coupling. In one example, the planarization process (e.g., etching) reduces the surface Ra of the capping layer to about 4 Å or less, in one particular example, the Ra of the capping layer is about 3.5 Å or less. Higher smoothness of the capping layer enables the use of a thinner overcoat on the capping layer. In one example, a thickness of the capping layer is between about 5 Å and about 20 Å.

In one aspect, the process can perform the sequence of actions in a different order. In another aspect, the process can skip one or more of the actions. In other aspects, one or more of the actions are performed simultaneously. In some aspects, additional actions can be performed.

In several aspects, the deposition of such layers can be performed using a variety of deposition sub-processes, including, but not limited to physical vapor deposition (PVD), sputter deposition and ion beam deposition, and chemical vapor deposition (CVD) including plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD) and atomic layer chemical vapor deposition (ALCVD). In other aspects, other suitable deposition techniques known in the art may also be used.

FIG.5is a chart comparing the magnetic moments of exemplary magnetic recording media that can be manufactured using the processes described above in relation toFIG.4. These media have different capping layers in terms of the level of metal doping. Medium M1 has a capping layer without any metal doping for comparison. Media M2, M3, M4, and M5 each have a capping layer doped with a small amount of Ru. Further, medium M1 can contain an amount of Co equal to, or higher than, that of media M2, M3, and M4.FIG.5shows the respective capping layer magnetic moment (Ms) of the media before and after etching. For each magnetic recording medium, the left column502represents the Ms before etching the capping layer, and the right column504represents the Ms after etching the capping layer. In one example, the etching amount of the media M1, M2, M3, M4, and M5 are 10.1 Å, 9.3 Å, 10.2 Å, 10.8 Å, and 10.3 Å, respectively. As shown inFIG.5, medium M1 has a Ms less than 600 emu/cc, and media M2, M3, and M4 each have Ms equal to or greater than 600 emu/cc before or after etching. For each sample media,FIG.5shows that the magnetic moment (Ms) of the media is increased by etching.

FIG.6illustrates the effect of a metal-doped capping layer in controlling grain-to-grain exchange coupling in capping layers of six exemplary magnetic recording media. Some of the exemplary media are the same as those described above in relation toFIG.5. As discussed above, the grain-to-grain exchange coupling of a capping layer can be controlled by doping an effective amount of metal (e.g., Ru) in the capping layer such that the magnetic moment of a capping layer can be increased (e.g., by etching and/or modifying the content of Co/Pt) without significant grain-to-grain exchange coupling increase. InFIG.6, the horizontal axis represents the capping layer thickness, and the vertical axis separately represents magnetic coercivity (Hc), nucleation field (Hn), saturation field (Hs), and switching field distribution (SFD). The grain-to-grain exchange coupling of a capping layer of media can be characterized using Hc, Hs, Hn, and SFD, where higher values of Hc, Hs, Hn, and SFD generally correspond to lower grain-to-grain exchange coupling. As shown inFIG.6, values of Hc, Hs, Hn, and SFD of a medium without a metal-doped capping layer602are generally lower than those of other magnetic recording media using a metal-doped capping layer as described above in relation toFIGS.3-4. Correspondingly, the grain-to-grain exchange coupling characteristics of the medium without the metal-doped capping layer are generally higher than those of other magnetic recording media using the metal-doped capping layer as described above in relation toFIGS.3-4. Therefore, it can be appreciated that the addition of an effective amount of metal (e.g., Ru or Ta) in the capping layer can prevent or reduce an increase of the grain-to-grain exchange coupling of a capping layer even when it has a higher Ms (e.g., an increase of Co content after etching).

FIG.7illustrates the effect of a metal-doped capping layer in controlling the magnetic core width (MCW) of exemplary magnetic recording media. InFIG.7, the horizontal axis represents the capping layer thickness, and the vertical axis represents the MCW of the media. Reducing the MCW of magnetic recording media can reduce the track width of the media and increase the areal density of the media. As shown inFIG.7, the MCW702of a magnetic recording medium without a metal-doped (e.g., Ru or Ta) capping layer is higher than the other magnetic recording media using a metal-doped (e.g., Ru) capping layer as described above in relation toFIGS.3-4.

Additional Aspects

The examples set forth herein are provided to illustrate certain concepts of the disclosure. The apparatuses, devices, or components illustrated above may be configured to perform one or more of the methods, features, or steps described herein. Those of ordinary skill in the art will comprehend that these are merely illustrative in nature, and other examples may fall within the scope of the disclosure and the appended claims. Based on the teachings herein those skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein.

Aspects of the present disclosure have been described above with reference to schematic flowchart diagrams and/or schematic block diagrams of methods, apparatuses, systems, and computer program products according to aspects of the disclosure. It will be understood that each block of the schematic flowchart diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and/or schematic block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a computer or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor or other programmable data processing apparatus, create means for implementing the functions and/or acts specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.

The subject matter described herein may be implemented in hardware, software, firmware, or any combination thereof. As such, the terms “function,” “module,” and the like as used herein may refer to hardware, which may also include software and/or firmware components, for implementing the feature being described. In one example implementation, the subject matter described herein may be implemented using a computer readable medium having stored thereon computer executable instructions that when executed by a computer (e.g., a processor) control the computer to perform the functionality described herein. Examples of computer-readable media suitable for implementing the subject matter described herein include non-transitory computer-readable media, such as disk memory devices, chip memory devices, programmable logic devices, and application specific integrated circuits. In addition, a computer readable medium that implements the subject matter described herein may be located on a single device or computing platform or may be distributed across multiple devices or computing platforms.

It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated figures. Although various arrow types and line types may be employed in the flowchart and/or block diagrams, they are understood not to limit the scope of the corresponding aspects. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted aspect.

The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of this disclosure. In addition, certain method, event, state or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described tasks or events may be performed in an order other than that specifically disclosed, or multiple may be combined in a single block or state. The example tasks or events may be performed in serial, in parallel, or in some other suitable manner. Tasks or events may be added to or removed from the disclosed example aspects. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed example aspects.

Those of skill in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Likewise, the term “aspects” does not require that all aspects include the discussed feature, advantage or mode of operation.

While the above descriptions contain many specific aspects of the invention, these should not be construed as limitations on the scope of the invention, but rather as examples of specific aspects thereof. Accordingly, the scope of the invention should be determined not by the aspects illustrated, but by the appended claims and their equivalents. Moreover, reference throughout this specification to “one aspect,” “an aspect,” or similar language means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect of the present disclosure. Thus, appearances of the phrases “in one aspect,” “in an aspect,” and similar language throughout this specification may, but do not necessarily, all refer to the same aspect, but mean “one or more but not all aspects” unless expressly specified otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well (i.e., one or more), unless the context clearly indicates otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” “including,” “having,” an variations thereof when used herein mean “including but not limited to” unless expressly specified otherwise. That is, these terms may specify the presence of stated features, integers, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. Moreover, it is understood that the word “or” has the same meaning as the Boolean operator “OR,” that is, it encompasses the possibilities of “either” and “both” and is not limited to “exclusive or” (“XOR”), unless expressly stated otherwise. It is also understood that the symbol “/” between two adjacent words has the same meaning as “or” unless expressly stated otherwise. Moreover, phrases such as “connected to,” “coupled to” or “in communication with” are not limited to direct connections unless expressly stated otherwise.

Any reference to an element herein using a designation such as “first,” “second,” and so forth does not generally limit the quantity or order of those elements. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements may be used there or that the first element must precede the second element in some manner. Also, unless stated otherwise a set of elements may include one or more elements. In addition, terminology of the form “at least one of a, b, or c” or “a, b, c, or any combination thereof” used in the description or the claims means “a or b or c or any combination of these elements.” For example, this terminology may include a, or b, or c, or a and b, or a and c, or a and b and c, or 2a, or 2b, or 2c, or 2a and b, and so on.

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining, and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, “determining” may include resolving, selecting, choosing, establishing, and the like.