Abstract:
The embodiments disclose a patterned composite magnetic layer structure configured to use magnetic materials having differing temperature and magnetization characteristics in a recording device, wherein the patterned composite magnetic layer structure includes magnetic layers, at least one first magnetic material configured to be used in a particular order to reduce a recording temperature and configured to control and regulate coupling and decoupling of the magnetic layers and at least one second magnetic material with differing temperature characteristics is configured to control recording and erasing of data.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/844,407 filed Jul. 9, 2013, entitled “A METHOD FOR FABRICATING COMPOSITE MEDIA FOR HAMR MEDIA AND PATTERNED HAMR MEDIA”, by Ju, et al. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a block diagram of an overview of a method for fabricating a patterned composite structure of one embodiment. 
       FIG. 2  shows a block diagram of an overview flow chart of a method for fabricating a patterned composite structure of one embodiment. 
       FIG. 3  shows a block diagram of an overview flow chart of composite magnetic layer structure of one embodiment. 
       FIG. 4  shows for illustrative purposes only an example of etching a BPM composite magnetic layer structure of one embodiment. 
       FIG. 5  shows for illustrative purposes only an example of reducing switching field distribution of one embodiment. 
       FIG. 6  shows for illustrative purposes only an example of two sources of SFD-Hk and Tc dispersion of one embodiment. 
       FIG. 7A  shows for illustrative purposes only an example of HAMR switching of an individual grain of one embodiment. 
       FIG. 7B  shows for illustrative purposes only an example of switching field function of heating temperature of one embodiment. 
       FIG. 8  shows for illustrative purposes only an example of anisotropy switching vs. recording temperature of one embodiment. 
       FIG. 9  shows for illustrative purposes only an example of switching field vs. recording temperature of one embodiment. 
       FIG. 10  shows for illustrative purposes only an example of combining two layers into a composite structure of one embodiment. 
       FIG. 11  shows for illustrative purposes only an example of 2-layer composite structure of one embodiment. 
       FIG. 12  shows for illustrative purposes only an example of patterned 2-layer composite magnetic layer structure of one embodiment. 
       FIG. 13  shows for illustrative purposes only an example of 3-layer composite structure of one embodiment. 
       FIG. 14  shows for illustrative purposes only an example of patterned 3-layer composite magnetic layer structure of one embodiment. 
    
    
     DETAILED DESCRIPTION 
     In a following description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration a specific example in which the embodiments may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope. 
     General Overview 
     It should be noted that the descriptions that follow, for example, in terms of a method for fabricating a patterned composite structure is described for illustrative purposes and the underlying system can apply to any number and multiple types magnetic recording patterns including bit patterned media (BPM) in nano-recording devices. In one embodiment, the method for fabricating a patterned composite structure can be configured using two or more heat sink layers. The method for fabricating a patterned composite structure can be configured to include two or more composite magnetic layers and can be configured to include differing material layers to reduce degrees of temperature rise to perform decoupling. 
       FIG. 1  shows a block diagram of an overview of a method for fabricating a patterned composite structure of one embodiment.  FIG. 1  shows depositing a continuous first heat sink layer of high thermal conductivity onto a substrate  100 . The processing continues with depositing a second heat sink layer of low to medium thermal conductivity onto the continuous first heat sink layer  110  followed by depositing a thin interlayer and thermal resistor layer on the second heat sink layer  120  of one embodiment. 
     The fabrication of a HAMR media stack follows with depositing a composite magnetic layer structure onto the thin interlayer and thermal resistor layer  130 . Patterning of the HAMR stack is made by etching a pattern including a bit patterned media (BPM) pattern down to the continuous first heat sink layer  140 . The patterned composite magnetic layer structure is used for controlling coupling and decoupling of magnetic layers with raising and lowering temperature  150 . Raising a temperature above a Curie temperature (Tc) enables coupling of magnetic moments to change magnetization and lowering a temperature below Tc produces decoupling of magnetic moments preventing changes in magnetization. The patterned composite magnetic layer structure combined with the patterned second heat sink layer and continuous first heat sink layer is used for reducing degrees of temperature rise to accommodate decoupling  160  and preventing changes in magnetic materials from freezing in a non-magnetic state  170  of one embodiment. 
     DETAILED DESCRIPTION 
       FIG. 2  shows a block diagram of an overview flow chart of a method for fabricating a patterned composite structure of one embodiment.  FIG. 2  shows depositing a continuous first heat sink layer of high thermal conductivity onto a substrate  100  using materials with high thermal conductivity with k values from 10 to 200 k/(w m)  200 . Depositing a thin second heat sink layer of low to medium thermal conductivity onto the continuous first heat sink layer  110  is made using materials with low thermal conductivity with k values from 1 to 10 k/(w m)  210 . The deposition of the thin second heat sink layer is using materials including copper alloys including zirconium (Zr) and nickel (Ni) alloys, molybdenum (Mo) alloys, tungsten (W) alloys and ruthenium (Ru) alloys  220  and includes a thickness from 2 to 20 nm  230 . The first heat sink layer of high thermal conductivity and thin second heat sink layer of low to medium thermal conductivity is used to direct heat dissipation away from for example BPM patterned features including a heated island and adjacent non-heated islands of one embodiment. 
     Depositing a thin interlayer and thermal resistor layer on the second heat sink layer  123  using materials including magnesium oxide (MgO), titanium nitride (TiN) alloys and other thermal resistive materials  240  slow heat losses in the BPM patterned feature being heated during a recording function. Descriptions of continuing processes are shown in  FIG. 3  of one embodiment. 
       FIG. 3  shows a block diagram of an overview flow chart of fabricating a composite magnetic layer structure of one embodiment.  FIG. 3  shows continuing from  FIG. 2  depositing a composite magnetic layer structure onto the thin interlayer and thermal resistor layer  140 . The deposition of the composite magnetic layer structure is using at least two magnetic layers with gradient Curie temperature (Tc), saturated magnetization (Ms) and anisotropic magnetic field (Hk) to reduce SFD  300 . A composite magnetic layer structure  310  includes using magnetic materials including iron-platinum (FePt), iron-platinum alloys including FeCuPt, iron-platinum compounds including Fe65Pt and including iron-rhodium (FeRh) including alloys and compounds of one embodiment. 
     The composite magnetic layer structure  310  can include a 2-layer composite structure  320  with a magnetic layer No. 2—high (Tc, Ms) lower (Hk)  324  which is a break layer  350 . The 2-layer composite structure  320  includes a magnetic layer No. 1—low (Tc, Ms), higher (Hk)  328 . 
     The composite magnetic layer structure  310  can include a 3-layer composite structure  330 . The 3-layer composite structure  330  includes a magnetic layer No. 3-high (Tc, Ms) medium (Hk)  332  and magnetic layer No. 2—low (Tc, Ms) lower (Hk)  334  which is a break layer  350  and a magnetic layer No. 1—high (Tc, Ms) high (Hk)  336 . The composite magnetic layer structure  310  can include other composite magnetic layer structures  340  with more magnetic layers and using other combinations of materials with differing Tc, Ms and Hk properties of one embodiment. 
     The composite magnetic layer structure  310  can include using materials that goes through AF-FM transition or ferri-to-ferro transition  360 . The composite magnetic layer structure  310  can include using materials that at room temperature two or more high-Hk layers are strongly coupled  370 . The composite magnetic layer structure  310  can include using materials that at elevated temperature near Tc of the break layer the coupling becomes weaker and the composite magnetic layer stack can be switched via an exchange spring mechanism  380 . Processing continuation is described further in  FIG. 4  of one embodiment. 
       FIG. 4  shows for illustrative purposes only an example of etching a BPM composite magnetic layer structure of one embodiment.  FIG. 4  shows a continuation from  FIG. 3  including etching a pattern including a bit patterned media (BPM) pattern down to the continuous first heat sink layer  140 . Depositing higher damping filler material in between BPM features (islands)  400  can be made after the patterning etch is completed. The etching a pattern including a bit patterned media (BPM) pattern down to the continuous first heat sink layer  140  includes patterning composite magnetic layer structure  410 . The patterned composite magnetic layer structure is used for controlling coupling and decoupling of magnetic layers with raising and lowering temperature  150 . It is also used in reducing degrees of temperature rise to perform decoupling  160  and preventing changes in magnetic materials from freezing in a non-magnetic state  170 . Further uses of the patterned composite magnetic layer structure are described in  FIG. 5  of one embodiment. 
     The etching a pattern including a bit patterned media (BPM) pattern down to the continuous first heat sink layer  140  includes patterning thin interlayer and thermal resistor layer and the second heat sink layer  420 . The patterned thin interlayer and thermal resistor layer and the second heat sink layer are used in directing the dissipation of heat down to the first continuous heat sink layer  430 . Directing the dissipation of heat down to the first continuous heat sink layer  430  is used for avoiding lateral thermal bloom in adjacent magnetic patterned features including bit patterned media features  440 . The avoidance of lateral thermal bloom results in improving thermal gradient of the heat assisted magnetic recording stack  450  of nano-recording devices. The uses of the patterned thin interlayer and thermal resistor layer and the second heat sink layer are further described in  FIG. 5  of one embodiment. 
       FIG. 5  shows for illustrative purposes only an example of reducing switching field distribution of one embodiment.  FIG. 5  shows continuing from  FIG. 4  the patterned composite magnetic layer structure is used for reducing switching field distribution (SFD)  500 . The patterning of the composite magnetic layer structure is creating patterned thermal exchange spring mechanism for reduced SFD at high switching temp for HAMR-BPM stacks  510  and creating higher signal-to-noise ratio (SNR)  520 . The patterned composite magnetic layer structure is used in reducing thermal freezing noise using finite saturated magnetization (Ms) during switching  530 . The patterned composite magnetic layer structure is creating high/low damping BPM patterned HAMR composite  540  where higher damping further reduces the freezing noise  550 . Creating exchange coupled composite (ECC)  560  using the patterned composite magnetic layer structure and the avoidance of lateral thermal bloom using the patterned thin interlayer and thermal resistor layer and the second heat sink layer shown in  FIG. 4  combine for reducing the level of laser power used to heat the magnetic patterned feature subject to data recording encoding  570  of one embodiment. 
       FIG. 6  shows for illustrative purposes only an example of two sources of SFD-Hk and Tc dispersion of one embodiment.  FIG. 6  shows two sources of SFD: Hk and Tc dispersion  600 . Tc dispersion is illustrated using a first graph of Tc dispersion  610  shows the derivative ranges for anisotropic change (δhsw) of a switching field vs. derivative changes in Curie temperatures (δTc) in recording temperature. A second graph of the Tc dispersion with Hk values of the switching field vs. recording temperature shows the derivative changes divided by the Curie temperature (δTc/Tc=5%) equals 5%  630  of one embodiment. 
     Hk dispersion is illustrated using a third graph of Hk dispersion  620  shows the ranges for anisotropic change of a switching field vs. changes in Curie temperatures in recording temperature. A fourth graph of the Hk dispersion with Hk values of the switching field vs. recording temperature shows the derivative changes divided by the Hk value of the material (δHk/Hk=5%) equals 5%  640 . Near Tc, dispersion of Tc is the dominating source of SFD over Hk dispersion  650  of one embodiment. 
       FIG. 7A  shows for illustrative purposes only an example of HAMR switching of an individual grain of one embodiment.  FIG. 7A  shows a HAMR switching process of an individual grain  700  illustrated using a graph of m z  vs. TIME (ps)  710 . The graph of m z  vs. TIME (ps)  710  shows the heating up of a grain starts at 50 ps, reaches Tc at 90 ps and cools to room temperature at 250 ps  720 . The graphs shows the change in magnetization (m z ) over the time (ps) in pico seconds (ps) of the grain heat up period and the cooling period down to the Curie temperature of one embodiment. 
       FIG. 7B  shows a switching field is a function of the heating temperature  730  using a graph of switching field Hex values in Oe vs. recording temperature  740 . The graph illustrates that a switching field vanishes at 650 k, which is the Tc for FePt  750  of one embodiment. 
       FIG. 8  shows for illustrative purposes only an example of anisotropy switching vs. recording temperature of one embodiment.  FIG. 8  shows a graph of anisotropy switching sigma hsw values vs. recording temperature Tc  800 . Shown is a first single magnetic layer No. 2—high (Tc, Ms) lower (Hk)  810  with for example Tc=780 k, k=0.2 k FePt  820 . A second single magnetic layer-low Tc, lower Hk, Ms can be either higher or lower  840  with for example Tc=650 k, k=k FePt  830  and Hex=10000 Oe shows lower switching values than magnetic layer No. 2. 
     Combining two layers into composite  870  structure using magnetic layer No. 2—high (Tc, Ms) lower (Hk)  850  with Tc=780 k, k=0.2 k FePt  820  and magnetic layer No. 1—low (Tc, Ms), higher (Hk)  860  with Tc=650 k, k=k FePt  830  with Hex=50000 Oe results in lower switching values than either single magnetic layer of one embodiment. 
       FIG. 9  shows for illustrative purposes only an example of switching field vs. recording temperature of one embodiment.  FIG. 9  shows a graph of switching field Hex values vs. recording temperature Tc  900 . The range of Hex values at various recording temperature points are averaged to create a trend line. The single magnetic layer No. 2—high (Tc, Ms) lower (Hk)  810  with for example Tc=780 k, k=0.2 k FePt  820  shows a greater distribution from starting high Hex values to ending Hex values than that of the single magnetic layer No. 1—low (Tc, Ms), higher (Hk)  840  with for example Tc=650 k, k=kFePt  830  and Hex=10000 Oe. 
     A magnetic layer combining two layers into composite  870  structure using magnetic layer No. 2—high (Tc, Ms) lower (Hk)  850  and magnetic layer No. 1—low (Tc, Ms), higher (Hk)  860  with Hex=50000 Oe results in the least distribution from starting high Hex values to ending Hex values than either of the single magnetic layers alone of one embodiment. 
       FIG. 10  shows for illustrative purposes only an example of combining two layers into composite of one embodiment.  FIG. 10  shows a graph of SFD % vs. T  1000  where T=recording temperature. The SFD % results are highest for the single magnetic layer No. 2—high (Tc, Ms) lower (Hk)  810  with for example Tc=780 k, k=0.2 k FePt  820 . The SFD % results for the single magnetic layer No. 1—low (Tc, Ms), higher (Hk)  840  with for example Tc=650 k, k=kFePt  830  and Hex=10000 Oe are lower than those of the single magnetic layer No. 2. 
     Combining two layers into composite  870  using magnetic layer No. 2—high (Tc, Ms) lower (Hk)  850  and magnetic layer No. 1—low (Tc, Ms), higher (Hk)  860  with Hex=50000 Oe shows SFD % results lower than either single magnetic layer. SFD is reduced by stretching the transition band  1010  and switching field is reduced at lower Tc than single magnetic layer  1020 . Combining two layers into composite  870  produces results with reduced Tc contrast, SFD is reduced from 24% for single FePt layer to 5% for composite with Hex=50000 Oe at 580 k  1030  of one embodiment. 
       FIG. 11  shows for illustrative purposes only an example of 2-layer composite structure of one embodiment.  FIG. 11  shows a substrate  1100  with a continuous first heat sink layer of high thermal conductivity  1110  deposited thereon. A second heat sink layer of low to medium thermal conductivity  1120  deposited on the continuous first heat sink layer of high thermal conductivity  1110 . A thin interlayer and thermal resistor layer  1130  is deposited onto the second heat sink layer of low to medium thermal conductivity  1120  of one embodiment. 
     A deposition using for example low Tc FeCuPt high Hk  1160  deposits the magnetic layer No. 1—low (Tc, Ms), higher (Hk)  328  onto the thin interlayer and thermal resistor layer  1130 . A deposition using for example high Tc Fe65Pt low Hk  1170  to deposit the magnetic layer No. 2— high (Tc, Ms) lower (Hk)  324  to create the 2-layer composite structure  320  of a composite magnetic layer structure  310 . A patterning process is used to transfer a bit pattern media feature (island) pattern  1150 . The patterning process includes etching a pattern including a bit patterned media pattern down to the continuous first heat sink layer  140  of one embodiment. 
       FIG. 12  shows for illustrative purposes only an example of patterned 2-layer composite magnetic layer structure of one embodiment.  FIG. 12  shows the substrate  1100  and continuous first heat sink layer of high thermal conductivity  1110 . A patterned BPM feature (island)  1260  includes a patterned second heat sink layer of low to medium thermal conductivity  1200  and patterned thin interlayer and thermal resistor layer  1210 . A patterned 2-layer composite magnetic layer structure  1290  includes a patterned magnetic layer No. 1—low (Tc, Ms), higher (Hk)  1250  and a patterned magnetic layer No. 2—high (Tc, Ms) lower (Hk)  1240  of one embodiment. 
     A read/write head  1270  includes a writing module  1272  used to encode data in the patterned BPM feature (island)  1260  when heated. The read/write head  1270  can include for example a laser power heating source  1274 . The laser power heating source  1274  is used to heat the patterned 2-layer composite magnetic layer structure  1290 . The laser power heating source  1274  applies heat optically to a targeted patterned BPM feature (island)  1262 . Applied optical heat  1280  is spread throughout the magnetic materials as conducted heat  1282 . The patterned thin interlayer and thermal resistor layer  1210  is an insulating material that slows the dissipation of heat from the magnetic materials enabling the magnetic materials to rise in temperature quickly. As shown in  FIG. 7A  the rise in temperature takes place in pico seconds (ps) of one embodiment. 
     When the targeted patterned BPM feature (island)  1262  reaches a temperature at or above the Curie temperature (Tc) the laser power heating source  1274  power is cut and the application of heat is stopped. The writing module  1272  applies a current with a polarity to encode the data bit to the targeted patterned BPM feature (island)  1262 . When heat dissipation  1284  reduces the temperature below Tc the polarity of the patterned 2-layer composite magnetic layer structure  1290  is oriented to the same polarity as the encoding writing module  1272  current of one embodiment. 
     The heat dissipation  1284  is directed from the magnetic materials down through the patterned thin interlayer and thermal resistor layer  1210  to the patterned second heat sink layer of low to medium thermal conductivity  1200 . The heat dissipation  1284  is directed from the patterned second heat sink layer of low to medium thermal conductivity  1200  to the continuous first heat sink layer of high thermal conductivity  1110 . The direction of heat dissipation  1284  is enabled as the thermal transfer follows a path from low to medium thermal conductivity to high thermal conductivity. The patterned thin interlayer and thermal resistor layer  1210 , patterned second heat sink layer of low to medium thermal conductivity  1200  and continuous first heat sink layer of high thermal conductivity  1110  creates a graded heat dissipation thermal conductivity structure of one embodiment. 
     The mass of the continuous first heat sink layer of high thermal conductivity  1110  absorbs the heat applied to the patterned 2-layer composite magnetic layer structure  1290 . The patterning of the thin interlayer and thermal resistor layer and second heat sink layer removes the mass of the materials that extend laterally along the layer. The patterning isolates the heat dissipation  1284  to the patterned features of the targeted patterned BPM feature (island)  1262  and avoids transfers of the heat to adjacent patterned BPM feature (island)  1264 . The transfer of heat to adjacent patterned BPM feature (island)  1264  is referred to a lateral thermal bloom. Without patterning the thin interlayer and thermal resistor layer and second heat sink layer the heat can be dissipated laterally along the continuous layer of the materials and pass to the adjacent patterned BPM feature (island)  1264 . Avoiding lateral thermal bloom in adjacent magnetic patterned features including bit patterned media features  440  of  FIG. 4  enables improving thermal gradient of the heat assisted magnetic recording stack  450  of  FIG. 4  of one embodiment. 
     Lateral thermal bloom dissipates a greater amount of heat from the targeted patterned BPM feature (island)  1262  thereby increasing the amount of applied optical heat  1280  to raise the temperature of the magnetic materials. Avoiding Lateral thermal bloom and using the patterned 2-layer composite magnetic layer structure  1290  reducing degrees of temperature rise to perform decoupling  160  creates an overall reduction in the amount of power used by the laser power heating source  1274  of one embodiment. 
       FIG. 13  shows for illustrative purposes only an example of 3-layer composite structure of one embodiment.  FIG. 13  shows the substrate  1100 , continuous first heat sink layer of high thermal conductivity  1110 , second heat sink layer of low to medium thermal conductivity  1130  and thin interlayer and thermal resistor layer  1120 . The composite magnetic layer structure  310  includes the deposition of the S-layer composite structure  330  including the magnetic layer No. 1—high (Tc, Ms) high (Hk)  336 , magnetic layer No. 2—low (Tc, Ms) lower (Hk)  334  and magnetic layer No. 3—high (Tc, Ms) medium (Hk)  332 . The 3-layer composite structure  330  of the composite magnetic layer structure  310  is patterned using the bit pattern media feature (island) pattern  1150 . The HAMR stack is patterned by etching a pattern including a bit patterned media pattern down to the continuous first heat sink layer  140  of one embodiment. 
       FIG. 14  shows for illustrative purposes only an example of patterned 3-layer composite magnetic layer structure of one embodiment.  FIG. 14  shows the substrate  1100  and continuous first heat sink layer of high thermal conductivity  1110 . The process of etching a pattern including a bit patterned media pattern down to the continuous first heat sink layer  140  creates a BPM patterned HAMR stack including the patterned second heat sink layer of low to medium thermal conductivity  1200  and patterned thin interlayer and thermal resistor layer  1210 . The patterned BPM feature (island)  1260  further includes a patterned magnetic layer No. 1—high (Tc, Ms) high (Hk)  1400 , patterned magnetic layer No. 2—low (Tc, Ms) lower (Hk)  1410  and patterned magnetic layer No. 3—high (Tc, Ms) medium (Hk)  1420  to create a patterned 3-layer composite magnetic layer structure  1430  of one embodiment. 
     The read/write head  1270  includes the writing module  1272  and laser power heating source  1274 . The laser power heating source  1274  is used to provide applied optical heat  1280  to the targeted patterned BPM feature (island)  1262  including the patterned 3-layer composite magnetic layer structure  1430 . The applied optical heat  1280  transfers heat throughout the patterned 3-layer composite magnetic layer structure  1430  as conducted heat  1282 . When the patterned 3-layer composite magnetic layer structure  1430  reaches a temperature at or above the Curie temperature (Tc) the laser power heating source  1274  application of heat is stopped of one embodiment. 
     The writing module  1272  applies a current with a polarity to encode the data bit to the targeted patterned BPM feature (island)  1262 . Heat dissipation  1284  reduces the temperature below Tc and the polarity of the patterned 3-layer composite magnetic layer structure  1430  is oriented to the same polarity as the encoding writing module  1272  current. The patterned magnetic layer No. 2 can be tuned as coupling with temperature  1440 . The patterned magnetic layer No. 1 and 3 have strong coupling at room temperature  1450  of one embodiment. 
     The patterned second heat sink layer of low to medium thermal conductivity  1200  and patterned thin interlayer and thermal resistor layer  1210  are used for directing heat dissipation  1284  while avoiding lateral thermal bloom in adjacent magnetic patterned features including bit patterned media features  440  of  FIG. 4 . The HAMR stack including the patterned 3-layer composite magnetic layer structure  1430  included in the patterned BPM feature (island)  1260  uses the composite magnetic layer structures for controlling coupling and decoupling of magnetic layers with raising and lowering temperature  150  of  FIG. 1 , reducing degrees of temperature rise to accommodate decoupling  160  of  FIG. 1  and preventing changes in magnetic materials from freezing in a non-magnetic state  170  of  FIG. 1  of one embodiment. 
     The foregoing has described the principles, embodiments and modes of operation. However, the invention should not be construed as being limited to the particular embodiments discussed. The above described embodiments should be regarded as illustrative rather than restrictive, and it should be appreciated that variations may be made in those embodiments by workers skilled in the art without departing from the scope as defined by the following claims.