Patent Publication Number: US-10762918-B2

Title: MAMR write head with thermal dissipation conductive guide

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of co-pending U.S. patent application Ser. No. 16/276,508, filed Feb. 14, 2019, which claims benefit of continuation of co-pending U.S. patent application Ser. No. 16/146,139, filed Sep. 28, 2018, which claims benefit of U.S. Provisional Patent Application Ser. No. 62/607,757, filed Dec. 19, 2017. Each of the aforementioned related patent applications is herein incorporated by reference. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     Embodiments of the present disclosure generally relate to data storage devices, and more specifically, to a magnetic media drive employing a magnetic recording head. 
     Description of the Related Art 
     Over the past few years, microwave assisted magnetic recording (MAMR) has been studied as a recording method to improve the areal density of a magnetic read/write device, such as a hard disk drive (HDD). MAMR enabled magnetic recording heads utilize a MAMR stack disposed between the trailing shield and the main pole to improve write field and/or field gradient, leading to better areal density capability (ADC). The MAMR stack may include a seed layer and at least one magnetic layer, such as a spin torque layer (STL) that is magnetized by a bias current from the main pole to the MAMR stack during operation. Alternatively, the MAMR stack may be a spin torque oscillator (STO) for generating a microwave (high frequency AC magnetic field). When a bias current is conducted to the STO from the main pole, the STO oscillates and provides an AC magnetic field to the recording medium. The AC magnetic field may reduce the coercive force of the recording medium, thus high quality recording by MAMR may be achieved. 
     However, Joule heating induced by the bias current from the main pole to the MAMR stack leads to heating or break-down induced failures. Conventionally, the MAMR stack and the main pole are surrounded by an electrically and thermally resistive material, such as aluminum oxide, which is very inefficient to dissipate heat. 
     Therefore, there is a need in the art for an improved data storage device. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure generally relates to data storage devices, and more specifically, to a magnetic media drive employing a magnetic recording head. The head includes a trailing shield, a main pole, a MAMR stack disposed between the trailing shield and the main pole, side shields surrounding at least a portion of the main pole, and a structure disposed between the side shields and the main pole at a media facing surface (MFS). The structure is fabricated from a material that is thermally conductive and electrically insulating/dissipative. The material has a thermal conductivity of at least 50 W/(m*K) and an electrical resistivity of at least 10 5  Ω*m. The structure helps dissipate joule heating generated from either the main pole or the MAMR stack into surrounding area without electrical shunting, leading to reduced heating or break-down induced failures. 
     In one embodiment, the magnetic recording head includes a trailing shield, a main pole, a stack disposed between the main pole and the trailing shield, and a first structure surrounding at least a portion of the main pole at a media facing surface, wherein the first structure is fabricated from a material having a thermal conductivity of at least 50 W/(m*K) and an electrical resistivity of at least 10 5  Ω*m. 
     In another embodiment, the magnetic recording head includes a trailing shield, a main pole, a stack disposed between the main pole and the trailing shield, and a first structure surrounding at least a portion of the main pole at a media facing surface, wherein the first structure is fabricated from a material selected from the group consisting of aluminum nitride, silicon carbide, beryllium oxide, gallium nitride, gallium phosphide, hexagonal boron nitride, cubic boron nitride, boron arsenide, gamma magnesium aluminate, zinc oxide, silicon, carbon, beryllium, tungsten, iridium, rhodium, molybdenum, diamond like carbon, and combination thereof. 
     In another embodiment, the magnetic recording head includes a trailing shield, a main pole, side shields surrounding at least a portion of the main pole, a stack disposed between the main pole and the trailing shield, and a first structure disposed between the trailing shield and the side shields, wherein the first structure includes at least one layer of gallium nitride, gallium phosphide, hexagonal boron nitride, cubic boron nitride, boron arsenide, gamma magnesium aluminate, silicon, carbon, beryllium, tungsten, iridium, rhodium, molybdenum, diamond like carbon, or zinc oxide, and at least one layer of aluminum oxide, aluminum nitride, or silicon carbide. 
     In another embodiment, the magnetic recording head includes a trailing shield, a main pole, a stack disposed between the main pole and the trailing shield, and means for dissipate heat generated from the main pole or the stack without electrical shunting, wherein the means for dissipate heat surrounds at least a portion of the main pole at a media facing surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  is a schematic illustration of a magnetic media device according to one embodiment. 
         FIG. 2  is a fragmented, cross sectional side view of a magnetic read/write head facing a magnetic disk according to one embodiment. 
         FIG. 3A  is a perspective MFS view of a portion of a write head of  FIG. 2  according to one embodiment. 
         FIG. 3B  is a perspective cross sectional view of the portion the write head of  FIG. 3A  according to one embodiment. 
         FIG. 3C  is a perspective view of the portion of the write head of  FIG. 3A  according to one embodiment. 
         FIG. 3D  is an exploded view of the portion of the write head of  FIG. 3A  according to one embodiment. 
         FIGS. 4A-4C  are side views of a MAMR stack of  FIG. 2  according to embodiments. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
     DETAILED DESCRIPTION 
     The present disclosure generally relates to data storage devices, and more specifically, to a magnetic media drive employing a magnetic recording head. The head includes a trailing shield, a main pole, a MAMR stack disposed between the trailing shield and the main pole, side shields surrounding at least a portion of the main pole, and a structure disposed between the side shields and the main pole at a MFS. The structure is fabricated from a material that is thermally conductive and electrically insulating/dissipative. The material has a thermal conductivity of at least 50 W/(m*K) and an electrical resistivity of at least 10 5  Ω*m. The structure helps dissipate joule heating generated from either the main pole or the MAMR stack into surrounding area without electrical shunting, leading to reduced heating or break-down induced failures. 
     The terms “over,” “under,” “between,” and “on” as used herein refer to a relative position of one layer with respect to other layers. As such, for example, one layer disposed over or under another layer may be directly in contact with the other layer or may have one or more intervening layers. Moreover, one layer disposed between layers may be directly in contact with the two layers or may have one or more intervening layers. In contrast, a first layer “on” a second layer is in contact with the second layer. Additionally, the relative position of one layer with respect to other layers is provided assuming operations are performed relative to a substrate without consideration of the absolute orientation of the substrate. 
       FIG. 1  is a schematic illustration of a data storage device such as a magnetic media device. Such a data storage device may be a single drive/device or comprise multiple drives/devices. For the sake of illustration, a single disk drive  100  is shown according to one embodiment. As shown, at least one rotatable magnetic disk  112  is supported on a spindle  114  and rotated by a drive motor  118 . The magnetic recording on each magnetic disk  112  is in the form of any suitable pattern of data tracks, such as annular patterns of concentric data tracks (not shown) on the magnetic disk  112 . 
     At least one slider  113  is positioned near the magnetic disk  112 , each slider  113  supporting one or more magnetic head assemblies  121 . As the magnetic disk  112  rotates, the slider  113  moves radially in and out over the disk surface  122  so that the magnetic head assembly  121  may access different tracks of the magnetic disk  112  where desired data are written. Each slider  113  is attached to an actuator arm  119  by way of a suspension  115 . The suspension  115  provides a slight spring force which biases the slider  113  toward the disk surface  122 . Each actuator arm  119  is attached to an actuator means  127 . The actuator means  127  as shown in  FIG. 1  may be a voice coil motor (VCM). The VCM includes a coil movable within a fixed magnetic field, the direction and speed of the coil movements being controlled by the motor current signals supplied by control unit  129 . 
     During operation of the disk drive  100 , the rotation of the magnetic disk  112  generates an air bearing between the slider  113  and the disk surface  122  which exerts an upward force or lift on the slider  113 . The air bearing thus counter-balances the slight spring force of suspension  115  and supports slider  113  off and slightly above the disk surface  122  by a small, substantially constant spacing during normal operation. 
     The various components of the disk drive  100  are controlled in operation by control signals generated by control unit  129 , such as access control signals and internal clock signals. Typically, the control unit  129  comprises logic control circuits, storage means and a microprocessor. The control unit  129  generates control signals to control various system operations such as drive motor control signals on line  123  and head position and seek control signals on line  128 . The control signals on line  128  provide the desired current profiles to optimally move and position slider  113  to the desired data track on disk  112 . Write and read signals are communicated to and from write and read heads on the assembly  121  by way of recording channel  125 . 
     The above description of a typical magnetic media device and the accompanying illustration of  FIG. 1  are for representation purposes only. It should be apparent that magnetic media devices may contain a large number of media, or disks, and actuators, and each actuator may support a number of sliders. 
       FIG. 2  is a fragmented, cross sectional side view of a magnetic read/write head  200  facing the magnetic disk  202  according to one embodiment. The magnetic disk  202  may correspond to the magnetic disk  112  described above in regards to  FIG. 1 . The magnetic read/write head  200  may correspond to the magnetic head assembly  121  described above in regards to  FIG. 1 . The magnetic read/write head  200  includes a MFS  212 , such as an air bearing surface (ABS), facing the disk  202 , a magnetic write head  210 , and a magnetic read head  211 . As shown in  FIG. 2 , the magnetic disk  202  moves past the write head  210  in the direction indicated by the arrow  232  and the magnetic read/write head  200  moves in the direction indicated by the arrow  234 . 
     In some embodiments, the magnetic read head  211  is a magnetoresistive (MR) read head that includes an MR sensing element  204  disposed between MR shields S 1  and S 2 . In other embodiments, the magnetic read head  211  is a magnetic tunnel junction (MTJ) read head that includes a MTJ sensing device  204  disposed between MR shields S 1  and S 2 . The magnetic fields of the adjacent magnetized regions in the magnetic disk  202  are detectable by the MR (or MTJ) sensing element  204  as the recorded bits. 
     The write head  210  includes a main pole  220 , a leading shield  206 , a trailing shield  240 , a MAMR stack  230  disposed between the main pole  220  and the trailing shield  240 , and a coil  218  that excites the main pole  220 . The coil  218  may have a “pancake” structure which winds around a back-contact between the main pole  220  and the leading shield  206 , instead of a “helical” structure shown in  FIG. 2 . The MAMR stack  230  is in contact with the main pole  220 . In one embodiment, a non-magnetic electrically conductive structure  246  surrounds at least a portion of the main pole  220 . The non-magnetic electrically conductive structure  246  surrounds a portion of the main pole  220  at the MFS  212 . The non-magnetic electrically conductive structure  246  is fabricated from a non-magnetic electrically conductive metal, such as NiTa, Cr, Cu, or Rh. In some embodiments, the non-magnetic electrically conductive structure  246  is fabricated from a multi-layer stack, such as NiTa/Ru, Cr/Cu, or Cr/Rh. A structure  254  surrounds the non-magnetic electrically conductive structure  246 . The structure  254  also surrounds at least a portion of the main pole  220 . The definition of the term “surround” includes having an intermediate material between a first element that is surrounding a second element and the second element that is being surrounded by the first element. For example, the non-magnetic electrically conductive structure  246  is disposed between the structure  254  and at least a portion of the main pole  220 . 
     The structure  254  is fabricated from a material that is thermally conductive and electrically insulating/dissipative. The material has a thermal conductivity of at least 50 W/(m*K) and an electrical resistivity of at least 10 5  Ω*m. The structure  254  helps dissipate joule heating generated from either the main pole  220  or the MAMR stack  230  into surrounding area without electrical shunting, leading to reduced heating or break-down induced failures. In one embodiment, the structure  254  is fabricated from aluminum nitride (AlN), silicon carbide (SiC), beryllium oxide (BeO), gallium nitride (GaN), gallium phosphide (GaP), hexagonal boron nitride (h-BN), cubic boron nitride (c-BN), boron arsenide (B 2 As 12 ), gamma magnesium aluminate (γ-MgAl 2 O 4 ), zinc oxide (ZnO), silicon (Si), carbon (C), beryllium (Be), tungsten (W), iridium (Ir), rhodium (Rh), molybdenum (Mo), diamond like carbon (DLC), or combination thereof. In one embodiment, the structure  254  is a multi-layer structure including at least one layer of GaN, GaP, h-BN, c-BN, B 2 As 12 , γ-MgAl 2 O 4 , ZnO, Si, C, Be, W, Ir, Rh, Mo, or DLC, and at least one layer of aluminum oxide (Al 2 O 3 ), AlN, or SiC. In addition to having good thermal conductivity, materials, such as C, Be, W, Ir, and Mo, having high melting point, such as greater than 1500 K, are less prone to thermal degradation due to diffusion or oxidation during operation. In one embodiment, the structure  254  includes at least a first layer fabricated from C, Be, W, Ir, Rh, or Mo, and at least a second layer fabricated from Al 2 O 3 , AlN, or SiC. In one embodiment, the structure  254  includes a Si layer and an Al 2 O 3  layer. In one embodiment, the structure  254  is a single layer that is a mixture of two or more materials including GaN, GaP, h-BN, c-BN, B 2 As 12 , γ-MgAl 2 O 4 , ZnO, Si, DLC, Al 2 O 3 , AlN, C, Be, W, Ir, Rh, Mo, and SiC. The single layer having two or more materials may be formed by a sputtering process that co-sputters two or more targets, or other processes that are known by the skilled in the art. 
     The main pole  220  includes a trailing taper  242  and a leading taper  244 . The trailing taper  242  extends from a location recessed from the MFS  212  to the MFS  212 . The leading taper  244  extends from a location recessed from the MFS  212  to the MFS  212 . The trailing taper  242  and the leading taper  244  may have the same degree of taper, and the degree of taper is measured with respect to a longitudinal axis  260  of the main pole  220 . In some embodiments, the main pole  220  does not include the trailing taper  242  and the leading taper  244 . Instead, the main pole  220  includes a trailing side (not shown) and a leading side (not shown), and the trailing side and the leading side are substantially parallel. The main pole  220  may be a magnetic material such as a FeCo or FeCo(N) alloy, or bct-Fe 16 N 2 . The leading shield  206  and the trailing shield  240  may be a magnetic material, such as NiFe alloy. 
       FIG. 3A  is a perspective MFS view of a portion of the write head  210  of  FIG. 2  according to one embodiment. As shown in  FIG. 3A , the write head  210  includes the main pole  220 , the MAMR stack  230  disposed on the main pole  220 , the non-magnetic electrically conductive structure  246  surrounding a portion of the main pole  220 , and side shields  302  surrounding the non-magnetic electrically conductive structure  246 . The main pole  220  includes a first surface  320  at the MFS  212 , a second surface  322  adjacent to the first surface  320 , a third surface  324  opposite the second surface  322 , a fourth surface  326  connected to the second surface  322 , and a fifth surface  328  opposite the fourth surface  326 . In one embodiment, the non-magnetic electrically conductive structure  246  surrounds the third surface  324 , the fourth surface  326 , and the fifth surface  328  of the main pole  220  at the MFS  212 . The structure  254  surrounds the non-magnetic electrically conductive structure  246 , and the side shields surround the structure  254 . The structure  254  has a thickness t 1  at the MFS  212 . The thickness ti ranges from about 2 nm to about 80 nm. In one embodiment, the structure  254  is in contact with the side shields and the non-magnetic electrically conductive structure  246 . During operation, joule heating generated in the main pole  220  gets dissipated to the side shields  302  via the non-magnetic electrically conductive structure  246  and the structure  254 . Because the structure  254  is electrically resistive, electrical shunting from the main pole  220  to the side shields  302  is prevented. 
     The MAMR stack  230  is disposed on both the main pole  220  and the non-magnetic electrically conductive structure  246 , so the electric current can flow to the MAMR stack  230  from the main pole  220  and the non-magnetic electrically conductive structure  246 . A structure  306  is disposed between the trailing shield  240  and the side shields  302 . In one embodiment, the structure  306  is in contact with the trailing shield  240  and the side shields  302 . The structure  306  is fabricated from a material that is thermally conductive and electrically insulating/dissipative. The material has a thermal conductivity of at least 50 W/(m*K) and an electrical resistivity of at least 10 5  Ω*m. In one embodiment, the structure  306  is fabricated from the same material as the structure  254 . In one embodiment, the structure  306  is fabricated from a different material from the structure  254 . The structure  306  includes first portions  308  at the MFS  212 , and the MAMR stack  230  is disposed between the first portions  308  of the structure  306  at the MFS  212 . Each of the first portions  308  of the structure  306  has a thickness t 2 . The thickness t 2  ranges from about the same as the thickness of the MAMR stack  230  to about 1.5 times the thickness of the MAMR stack  230 . The thickness t 2  is substantially greater than the thickness t 1 . In one embodiment, the first portions  308  of the structure  306  are in contact with the MAMR stack  230 . The first portions  308  of the structure  306  are in contact with the structure  254 , as shown in  FIG. 3A . In one embodiment, the first portions  308  of the structure  306  are in contact with both the structure  254  and the non-magnetic electrically conductive structure  246 . During operation, joule heating generated in the MAMR stack  230  gets dissipated to the trailing shield  240  and the side shields  302  via the structure  306 , the non-magnetic electrically conductive structure  246  and the structure  254 . Because the structures  254 ,  306  are electrically resistive, electrical shunting from the main pole  220  to the side shields  302  and from the side shields  302  to the trailing shield  240  is prevented. 
       FIG. 3B  is a perspective cross sectional view of the portion the write head  210  of  FIG. 3A  according to one embodiment. As shown in  FIG. 3B , the first portion  308  of the structure  306  is disposed between the trailing shield  240  and the side shield  302  at the MFS  212 . The structure  306  includes a second portion  330  that is recessed from the MFS  212 . The second portion  330  of the structure  306  is in contact with the MAMR stack  230  at a location that is recessed from the MFS  212 . The second portion  330  of the structure  306  is disposed between the trailing shield  240  and the main pole  220 . In one embodiment, the second portion  330  of the structure  306  is in contact with the trailing shield  240  and the trailing taper  242  of the main pole  220 . In one embodiment, the second portion  330  has a non-uniform thickness, as shown in  FIG. 3B . The second portion  330  has a portion  332  disposed on the taper  242  of the main pole  220 , and the portion  332  has a thickness t 3 . The thickness t 3  may be substantially the same as the thickness t 2 . The second portion  330  has a portion  334  extending from the portion  332  away from the MFS  212 , and the portion  334  has a thickness t 4 . The thickness t 4  is substantially equal to or greater than the thickness t 3 . Both thicknesses t 4  and t 3  are substantially equal to or greater than the thickness t 1 . 
     As shown in  FIG. 3B , the non-magnetic electrically conductive structure  246  and the structure  254  both extend from the MFS  212  to a location recessed from the MFS  212 . The one or more portions of the main pole  220  that are surrounded by the non-magnetic electrically conductive structure  246  and the structure  254  at the MFS  212  are also surrounded by the non-magnetic electrically conductive structure  246  and the structure  254  at locations recessed from the MFS  212 . 
       FIG. 3C  is a perspective view of a portion of the write head  210  of  FIG. 3A  according to one embodiment. As shown in  FIG. 3C , the first portion  308  of the structure  306  has a portion  336  disposed on a taper  340  of the side shield  302 . The taper  340  may be substantially parallel to the trailing taper  242  of the main pole  220 . The portion  336  has the thickness t 2 . The first portion  308  has a portion  338  extending from the portion  336  away from the MFS  212 , and the portion  338  has a thickness t 5 . The thickness t 5  is substantially equal to or greater than the thickness t 2 . Thus, similar to the second portion  330 , each of the first portions  308  may have a non-uniform thickness. 
       FIG. 3D  is an exploded view of the portion of the write head  210  of  FIG. 3A  according to one embodiment. The MAMR stack  230  is omitted for better illustration. As shown in  FIG. 3D , the write head  210  includes the trailing shield  240  disposed over the structure  306 . The first portions  308  of the structure  306  are disposed at the MFS  212 , and the second portion  330  is recessed from the MFS  212 . The first portion  308  includes the portion  336  and the portion  338  extending from the portion  336  away from the MFS  212 , and the portion  336  is disposed over the taper  340  of the side shield  302 . The thickness t 2  of the portion  336  is substantially less than the thickness t 5  of the portion  338 . The first portions  308  are disposed between the trailing shield  240  and the side shields  302 , and the second portion  330  is disposed between the trailing shield  240  and the main pole  220 . In one embodiment, the first portions  308  are in contact with the trailing shield  240  and the side shields  302 , and the second portion  330  is in contact with the trailing shield  240  and the main pole  220 . 
       FIGS. 4A-4C  are side views of the MAMR stack  230  of  FIG. 2  according to embodiments. As shown in  FIG. 4A , the MAMR stack  230  includes a seed layer  402 , a spacer layer  404  disposed on the seed layer  402 , and a magnetic layer  406  disposed on the spacer layer  404 . The seed layer  402  is fabricated from an electrically conductive material, such as a non-magnetic metal. In one embodiment, the seed layer  402  is fabricated from Ta, Cr, Cu, NiAl, Ru, Rh, or combination thereof. The magnetic layer  406  is fabricated from a magnetic material, such as NiFe, CoMnGe, CoFe, or combinations thereof. In one embodiment, the magnetic layer  406  is a STL. The spacer layer  404  is fabricated from a material such as copper (Cu) or silver tin alloy (AgSn). During operation, an electrical current flows into the magnetic layer  406  via the main pole  220  and the non-magnetic electrically conductive structure  246  ( FIG. 2 ), and the magnetic layer  406  is magnetized, leading to improved write-ability. 
       FIG. 4B  is a side view of the MAMR stack  230  according to another embodiment. As shown in  FIG. 4B , the MAMR stack  230  includes a first magnetic layer  408  disposed on the seed layer  402 , an interlayer  410  disposed on the first magnetic layer  408 , and a second magnetic layer  412  disposed on the interlayer  410 . In one embodiment, the first magnetic layer  408  is a spin polarization layer (SPL), and the second magnetic layer  412  is a field generation layer (FGL). In another embodiment, the first magnetic layer  408  is an FGL, and the second magnetic layer  412  is a SPL. The SPL may be a CoNi layer having perpendicular magnetic anisotropy. Other materials may be used as the SPL, such as CoMnGe, CoFe, NiFe, CoPt, CoCrPt, CoPd, FePt, CoFePd, TbFeCo, or combinations thereof. The FGL may be a CoFe layer or lamination of Co and Fe layers. The interlayer  410  may be a metal layer having long spin diffusion length such as Au, Ag, AgSn, or Cu. The first magnetic layer  408 , the interlayer  410 , and the second magnetic layer  412  may form a STO. During operation, an electrical current flows into the STO via the main pole  220  and the non-magnetic electrically conductive structure  246  ( FIG. 2 ), and the STO oscillates and provides an AC magnetic field to the recording medium. The AC magnetic field may reduce the coercive force of the recording medium, thus high quality recording by MAMR may be achieved. 
       FIG. 4C  is a side view of the MAMR stack  230  according to yet another embodiment. As shown in  FIG. 4C , the MAMR stack  230  includes the seed layer  402  and a non-magnetic gap layer  414  disposed on the seed layer  402 . The non-magnetic gap layer  414  is fabricated from a non-magnetic metal, such as Cu, Cr, Ta, Ru, W, Au, Ag, Sn, Mo, Ir, Pt, or Rh. During operation, an electrical current flows into the non-magnetic gap layer  414  via the main pole  220  and the non-magnetic electrically conductive structure  246  ( FIG. 2 ), and write-ability is improved. 
     The data storage device including the magnetic write head having a heat dissipating structure surrounding at least a portion of the main pole and another heat dissipating structure in contact with the MAMR stack. The heat dissipating structures are both electrically insulating/dissipative. Joule heating generated in the main pole and the MAMR stack is dissipated by the structures. As a result, the write-ability of the magnetic write head is improved, and the life-time of the magnetic write head is increased because failures induced by heating or break-down are minimized. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.