Patent Publication Number: US-2013235490-A1

Title: Perpendicular magnetic recording media with seed layer structure
containing ruthenium (Ru)

Description:
TECHNICAL FIELD 
     Embodiments of the invention relate generally to perpendicular magnetic recording media. 
     BACKGROUND 
     Information can be recorded on a storage media by use of magnetic recording. Magnetic recording media are widely used in various devices such as hard disk drives and used in various industries such as the computer industry and the data storage industry. Efforts are continually being made to increase areal recording density (i.e., bit density of the magnetic media) of the media. In order to increase the recording densities, perpendicular recording media structures (PMR) have been developed and have been found to be superior to longitudinal recording media. 
     In perpendicular magnetic recording media, the recording bits are stored in a perpendicular or out-of-plane orientation in a recording layer of the recording media. The perpendicular orientation allows the recording bits to be more tightly packed in the horizontal direction. 
     Magnetic flux transmitted from a write head will affect the bits directly below the write head when the magnetic flux transmits down through the vertical bit area, through the soft underlayer, and back up the return pole. Examples of disk drive systems and magnetic heads for use with perpendicular magnetic recording media are disclosed in, for example, U.S. patent application Ser. No. 12/231,513, entitled PERPENDICULAR MAGNETIC RECORDING MEDIUM AND MAGNETIC RECORDING AND REPRODUCING APPARATUS USING THE SAME, U.S. patent application Ser. No. 11/645,252, entitled PERPENDICULAR MAGNETIC RECORD MEDIUM AND MAGNETIC STORAGE SYSTEM, and U.S. patent application Ser. No. 12/577,344, entitled PATTERNED PERPENDICULAR MAGNETIC RECORDING MEDIUM WITH DATA ISLANDS HAVING A FLUX CHANNELING LAYER BELOW THE RECORDING LAYER. Application Ser. Nos. 12/231,513, 11/645,252, and 12/577,344 are assigned to and owned by Hitachi Global Storage Technologies Netherlands B.V. 
     Cobalt based alloys are widely used in the recording layer of perpendicular magnetic recording media. By improving the crystalline C-axis (magnetic anisotropy is aligned along this crystalline axis) orientation in the vertical or perpendicular direction to the recording layer plane, the effective perpendicular magnetic anisotropy is increased, which leads to an increase in the coercivity of the recording layer. The improved orientation and higher coercivity can result in an improvement in the signal-to-noise ratio (SNR) and narrowing of the magnetic track width, which can yield an improvement in the areal density performance of the perpendicular recording media. 
     In conventional perpendicular magnetic recording media technology, a seed layer is increased in thickness in the recording media in order to achieve improved crystalline orientation in the magnetic layer so that the coercivity is increased. However, a thicker seed layer also forms larger-sized grains in the recording layer, and these larger-sized grains contribute to increased noise in the recording layer because the SNR is reduced due to the reduction in the number of grains per bit (due to the larger grain volume). 
     Therefore, there is a continuing need to achieve enhanced crystalline orientation in perpendicular magnetic recording media so that increased recording density and improved SNR are achieved. 
     SUMMARY 
     In one embodiment of the invention, an apparatus includes: a perpendicular magnetic recording medium including a soft under layer, a seed layer structure above the soft under layer, wherein the seed layer structure contains Ruthenium, and a magnetic recording layer above the seed layer structure. 
     In another embodiment of the invention, an apparatus includes: a perpendicular magnetic recording medium including a substrate, a soft under layer above the substrate, a seed layer structure above the soft under layer, wherein the seed layer structure comprises a first seed layer and a second seed layer above the first seed layer and wherein the second seed layer contains Ruthenium, and a magnetic recording layer above the seed layer structure. 
     In yet another embodiment of the invention, an apparatus includes a magnetic disk drive. The magnetic disk drive includes: a magnetic head for writing magnetic transitions in a perpendicular magnetic recording medium on a disk. The disk with the perpendicular magnetic recording medium includes: a substrate, a soft under layer above the substrate, a seed layer structure above the soft under layer, wherein the seed layer structure contains Ruthenium, and a magnetic recording layer above the seed layer structure. 
     In yet another embodiment of the invention, an apparatus includes: a perpendicular magnetic recording medium including a substrate, a soft under layer above the substrate, a magnetic recording layer, and means for controlling an orientation of grains in the magnetic recording layer, wherein the controlling means is above the soft under layer and wherein the controlling means contains Ruthenium. 
     In yet another embodiment of the invention, a method includes: providing a substrate, forming a soft under layer above the substrate, forming a seed layer structure above the soft under layer, wherein the seed layer structure contains Ruthenium, and forming a magnetic recording layer above the seed layer structure, wherein the recording layer is part of a perpendicular magnetic recording medium. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one (several) embodiment(s) of the invention and together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. 
         FIG. 1  is a block diagram of the layers in a perpendicular magnetic recording media, in accordance with an embodiment of the invention. 
         FIG. 2  is a block diagram of the layers in a perpendicular magnetic recording media, in accordance with another embodiment of the invention. 
         FIG. 3  is a block diagram of a plan view image of the structure of a magnetic recording layer in a perpendicular magnetic recording medium, in accordance with an embodiment of the invention. 
         FIG. 4  is a graph showing magnetic field values for different thickness values of a seed layer structure, in accordance with various embodiments of the invention. 
         FIG. 5  is a chart showing rocking curve angle values for seed layer structures in accordance with various embodiments of the invention. 
         FIG. 6  is a chart showing recording performance for seed layer structures in accordance with various embodiments of the invention. 
         FIG. 7  is a block diagram of a magnetic disk drive that can operate with a magnetic recording media in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, methods, components, materials, parts, layers, and/or the like. In other instances, well-known structures, materials, layers, or operations are not shown or described in detail to avoid obscuring aspects of embodiments of the invention. Additionally, the figures are representative in nature and their shapes are not intended to illustrate the precise shape or precise size of any element and are not intended to limit the scope of the invention. 
     For purposes of the discussion herein, the following terms are also defined as follows: the terms “above” or “on” means above, but not necessarily in contact with, and the term “alloy” means a composition of matter with two or more elements, wherein at least one of the elements is a metal. An alloy of a composition of matter can include itself (e.g., an FeCo alloy includes FeCo). 
       FIG. 1  is a block diagram of the layers in a perpendicular magnetic recording media  100 , in accordance with an embodiment of the invention. The term “media  100 ” is defined herein as a single recording medium  100  or as a plurality of recording medium  100 . The media  100  can be used, for example, as a disk in a disk drive or as another-type of device in a computing system, data storage system, or other systems. 
     The media  100  includes a substrate  105  that can be used for magnetic media. Above the substrate is an adhesion layer  110 . Above the adhesion layer  110  is a soft under layer (SUL)  115 . Above the SUL  115  is a first seed layer  120 . Above the first seed layer  120  is a second seed layer  125 . The first seed layer  120  and the second seed layer  125  together form dual seed layer structure  128  (i.e., seed layer structure  128 ) in accordance with an embodiment of the invention. Above the second seed layer  125  is an intermediate layer  130 . Above the intermediate layer  130  is a magnetic recording layer  135  (i.e., magnetic layer  135  or recording layer  135 ). Above the magnetic recording layer  135  is an overcoat  140 . The layers above the substrate  105  may be sputter deposited onto the media  110 , and will be discussed further below, or can be formed on the substrate  105  by another suitable method. As an example, Ar (Argon) gas can be used as part of the sputter deposition process. The perpendicular magnetic recording media  100  is manufactured by using a sputtering apparatus such as, for example, the LEAN 200 (C-3040) sputtering apparatus that is manufactured by INTEVAC (Canon Anelva) Company or other suitable sputtering devices known to those skilled in the art. 
     The substrate  105  is any substrate that can be used for magnetic media. The substrate  105  can be, for example, glass, AlMg, ceramics, glass/ceramic mixtures, or other suitable materials. Other materials that can be used for the substrate  105  include, for example, a conventional aluminum alloy with a NiP surface coating, or an alternative disk blank, such as silicon, canasite or silicon-carbide. The substrate  105  is, for example, approximately 0.6 or 0.8 mm in thickness. 
     The convention for alloy composition used in the discussion herein gives the atomic percentage (at. %) of an identified element with the balance being with the other element in the composition. The example atomic percentage compositions described herein are given without regard for the potential small amounts of contaminants that invariably exist in sputtered thin films as is well known to those skilled in the art. For instance NiTa20W5 is an alloy of 75 at. % Ni, 20 at. % Ta and 5 at. % W. Similarly, NiTa (20 at. %) W (5 at. %) is an alloy of 75 at. % Ni, 20 at. % Ta and 5 at. % W. 
     In forming the film layers for the media  100 , the metal, oxides and carbon materials can be formed by DC sputtering or RF sputtering. The oxides can be deposited from either a metallic or oxide containing target and be sputtered in a reactive gas environment. 
     The adhesion layer  110  prevents any exfoliation between the substrate  105  and the films stacked thereon. The adhesion layer  110  is made of, for example, NiTa (AITi) or a similar material. The adhesion layer  110  is, for example, between approximately 2 nm and 50 nm (20 nm) in thickness. The adhesion layer  110  is formed on the substrate  105  with, for example, sputtering. The target has a composition of, for example, AlTi (40-60 at. %). 
     The SUL  115  is for providing a flux return path for the magnetic field from the read/write pole head. The SUL layer  115  is typically a relatively low-coercivity magnetically permeable underlayer. The SUL layer  115  is made of, for example, an alloy of CoTaZr or other suitable materials. Other materials that can be used for the SUL layer  115  are, for example, the alloys of CoNiFe, FeCoB, CoCuFe, NiFe, FeAlSi, FeTaN, FeN, FeTaC, FeC, CoFeTaZr, CoFeB, CoB, CoTaNb, and CoZrNb, or a laminated structure formed of multiple soft magnetic films separated by nonmagnetic films, such as electrically conductive films like Al and CoCr or antiferromagnetic coupling films. As other examples, the SUL layer  115  is a stacked or laminated film composed of a Ru film and a soft magnetic film made of various particular compounds discussed above. The SUL layer  115  is, for example, between approximately 10 nm and 200 nm in thickness. The SUL layer  115  is formed with, for example, sputtering. The target has a composition of, for example, CoTa (8-12 at. %) Zr (1-4 at. %). 
     The dual seed layer structure  128  is provided to improve and control the crystalline orientation of the recording layer  135 , by controlling the growth orientation of crystals (grains) in the magnetic recording layer  135 . The use of the dual seed layer structure  128  leads to an improved magnetic media crystal orientation, as observed or measured as a narrower rocking curve width (XRD rocking curve angle) of the magnetic grains in the magnetic recording layer  135 . This narrower rocking curve width shows that the material has a tighter/narrower distribution of crystal orientation which leads to a higher coercivity (Hc) than a material with a higher rocking curve width and a less well defined crystal orientation. This increased coercivity increases the threshold (makes it harder) for the magnetic write head to reverse the polarity of a magnetic grain during write operations, and therefore, this increased coercivity limits the reversal of the media to a narrower higher field region underneath the write pole of the magnetic write head during write operations. The increased coercivity can achieve a higher recording density because a narrower written track may be achievable that can improve areal density. This method can also achieve higher coercivities without resorting to increasing the grain size in the recording layer  135 . Further, the more narrow distribution of the media reduces the noise of the media because a narrower distribution yields more grains more closely oriented in the proper vertical direction. 
     Additionally, an embodiment of the invention uses a seed layer with Ru which permits the seed layer to be decreased in thickness. In conventional perpendicular magnetic recording media technology, the seed layer is increased in thickness in order to achieve improved crystalline orientation (and the resulting higher coercivity) in the magnetic recording layer. However, a thicker seed layer also forms larger-sized magnetic grains that contribute to increased noise in the recording layer. In other words, an embodiment of the invention allows the use of a thinner seed layer to achieve the same (or an enhanced) coercivity (Hc) as compared to a media with a thicker seed layer, since the thinner seed layer avoids increasing magnetic grain size and larger magnetic grain sizes lowers the SNR. Therefore, an embodiment of the invention provides a decreased seed layer thickness to create smaller grains that provides a pathway to increased SNR. The properties in the seed structure  128  (which contains Ru) results in the narrower rocking curve width in the magnetic grains. 
     The first seed layer  120  is made of, for example, an alloy of NiFe. The first seed layer  120  is, for example, approximately 0.5 nm-5 nm and preferably 1.5 nm-2.5 nm in thickness. The second seed layer  125  is made of, for example, an alloy of NiWRu. The second seed layer  125  is, for example, approximately 0.5 nm-6 nm and preferably 2 nm-5 nm in thickness. The effect of adjusting the thickness of the first and second seed layers will be discussed below. Also discussed below is another embodiment of the invention, where the perpendicular magnetic recording media will have only a single seed layer and that single seed layer being Ru including seed layer  125 . 
     The seed layers  120  and  125  are each formed with, for example, sputtering. As an example, Ar gas can be used for performing the sputter deposit process for the seed layers  120  and  125 . For the first seed layer  120 , the layer has a composition of, for example NiFe (5-55 at. %) and preferably NiFe (15-40 at. %). For the second seed layer  125 , the layer has a composition of, for example, NiW (2-10 at. %) Ru (3-9 at. %) and preferably NiW (6-8 at. %) Ru (4-6 at. %). In some embodiments seed layers  120  or  125  is directly on SUL  115 . In some embodiments intermediate later  130  is directly on seed layer  125 . 
     The intermediate layer  130  also helps to improve the crystallographic texture of the magnetic recording layer and the attainment of improved magnetic properties. The intermediate layer  130  helps promote segregation of non-magnetic material (e.g., Si oxide or any other oxide or nitrides) into grain boundaries in magnetic recording layer  135 . The intermediate layer  130  is made of, for example, Ru or a similar material. The intermediate layer  130  is, for example, between approximately 2 nm and 30 nm in thickness. The intermediate layer  130  is formed with, for example, sputtering. 
     The recording layer  135  is the layer in which information is recorded as magnetization information. Since the media  100  is a perpendicular magnetic recording media, the direction of magnetization of the recording layer  135  is in the direction perpendicular to the film surface. The recording layer  135  is made of material composed of ferromagnetic crystal grains. For example, the recording layer  135  is made of the Co—Cr—Pt alloy film, with the grains being separated by a non-magnetic material. As another example, the recording layer  135  is another type of cobalt alloy such as CoCr or CoCr with one or more of Pt, Nb and Ta. As another example, the recording layer  135  is a multilayer film with Co and Pd or Pt being alternately layered and with the grains being separated by a non-magnetic material. The non-magnetic material can be, for example, any of the Ta, W, Nb, V, Mo, B, Si, Co, Cr, Ti, Al, and Zr oxides or nitrides. 
     As a particular example, the recording layer  135  is made of a cobalt alloy magnetic film containing Co (60-70 at. %) Pt (15-25 at. %) Cr (5-15 at. %)—SiO 2 . The recording layer  135  is, for example, between approximately 8 nm and 25 nm in thickness. The recording layer  135  is formed with, for example, sputtering. 
     The overcoat  140  is provided for protecting the layers which are successively disposed on the substrate  105 . The overcoat  140  is made of, for example, a carbon film. This carbon film can be an amorphous diamond-like carbon film. The overcoat  140  can also be made of other known protective overcoats, such as, for example, Si-nitride, BN or B4C. The overcoat  140  is, for example, between approximately 1 nm and 5 nm in thickness. The overcoat  140  is formed with, for example, sputtering. Of course, the thinner the overcoat  140  in thickness, the closer the slider will fly over the media. Generally, less distance between the slider and media improves the recording and reading characteristics of a recording system. 
       FIG. 2  is a block diagram of the layers in a perpendicular magnetic recording media  200 , in accordance with another embodiment of the invention. As mentioned above, in this embodiment, the seed layer structure  205  includes a single seed layer  125  containing Ru and does not include the seed layer  120  ( FIG. 1 ). As discussed above, the seed layer  125  is made of, for example, NiWRu. The recording performance and characteristics of the media  200  with the single seed layer structure  205  (with Ru) and the media  100  with the dual-seed layers structure  128  ( FIG. 1 ) will be discussed below. 
       FIG. 3  is a block diagram of a plan view image  300  of the structure of a magnetic recording layer in a perpendicular magnetic recording media, in accordance with an embodiment of the invention. This image  300  can be observed by using, for example, a high-resolution transmission electron microscope. The crystal grain boundaries  305  (which are non-magnetic regions) are identified around the crystal grains  310 . In practice, oxide segregant material  315  that could migrate to the grain boundaries may get trapped within the grain structure. 
     The intermediate layer  130  (e.g., Ru layer) ( FIG. 1 ) could have increased irregularities (or/and roughness or/and variance or/and texturing) due to the Ru surface roughness in the seed layer structures ( FIGS. 1 and 2 ). The increased irregularities in the intermediate layer  130  promote the magnetic de-coupling of the crystal grains  310  in the magnetic recording layer  135  by contributing to the separation of grains  310  along the non-magnetic boundaries  305 . Due to the sufficient grain boundaries  305  leading to more de-coupled grains in the magnetic recording layer  135 , the signal-to-noise ratio is increased in a perpendicular magnetic recording media with the seed layer structures (structure  128  in  FIG. 1  or structure  205  in  FIG. 2 ). 
     In an optimal perpendicular recording media, the direction of magnetization of the crystal grains in the magnetic layer are aligned perpendicular to the film plane. The C-axis (vertically oriented crystal axis) of the cobalt alloy in the magnetic layer  135  is desired to be perpendicular to the plane of the magnetic layer  135  so that the layer  135  has strong perpendicular magnetic anisotropy. In an embodiment of the invention, the seed layer structure  128  in  FIG. 1  (or structure  205  in  FIG. 2 ) improves the perpendicular crystalline C-axis orientation and also achieves a higher coercivity and a reduced rocking curve angle. A higher coercivity can allow a narrower written track to be achieved in the recording layer which can help increase recording density without degrading the SNR. Therefore, it is advantageous to reduce the rocking curve angle in perpendicular magnetic recording media. 
     In conventional perpendicular magnetic recording media technology, a seed layer is increased in thickness in the recording media in order to achieved improved crystalline orientation in the magnetic layer so that the coercivity is increased. However, a thicker seed layer also forms larger-sized grains in the recording layer, and these larger-sized grains contribute to increased noise in the recording layer. On the other hand, to obtain a high SNR of the cobalt alloy perpendicular media, the grain size of the media is made sufficiently small to obtain the high resolution required for sharp magnetic bit transitions. Embodiments of the invention can advantageously avoid the use of thicker seed layers and can therefore overcome the above problems in conventional technology. In embodiments of the invention, the seed layer structures  128  and  205  ( FIGS. 1 and 2 , respectively) are relatively small in thickness and allows the formation of smaller grain sizes in the recording layer  135 , while achieving a high coercivity due to a good C-axis orientation as discussed above. The enhanced SNR performance and high coercivity is a result of the improved orientation in the recording layer  135 , due to the balance of properties between the seed layer  125  (which contains Ru) and the intermediate layer  130  (which contains Ru). 
       FIG. 4  is a graph  400  showing magnetic field values for different thickness values of a seed layer structure, in accordance with various embodiments of the invention. The coercivity field (Hc) (Oersted) in the perpendicular magnetic recording media with the dual seed layers structure  128  ( FIG. 1 ), which contains NiFe+NiWRu, increases as the seed layers structure  128  thickness is increased, as shown by line  405 . The Hc field in the media with the dual seed layer structure  128  is greater than the Hc field (line  410 ) for media with the single seed layer structure  205  ( FIG. 2 ), which contains the single seed layer  120  of NiWRu. The Hc field for media with the single seed layer structure  205  is greater than the Hc field (line  415 ) for media with a single NiFe seed layer. Therefore, the graph  400  illustrates the increased coercivity for media with the seed layer structures  128  ( FIG. 1 ) or  205  ( FIG. 2 ) in accordance with various embodiments of the invention. 
     Also shown in the graph  400  are the following lines that further show additional magnetic characteristics of media with the various seed layers mentioned above. The lines  420 ,  425 , and  430  represent the switching field distribution for media (i) with a seed structure containing dual NiFe and NiWRu seed layer  128 , (ii) a seed structure containing a single NiWRu seed layer  205 , and (iii) a single seed layer of NiFe, respectively. The lines  435 ,  440 , and  445  represent the nucleation field (Hn), which represents the field at which the reversal process begins, for the media with a seed structure containing a single NiWRu seed layer  205 , with a seed structure containing dual NiFe and NiWRu seed layer  128 , and a single seed layer of NiFe, respectively. 
       FIG. 5  is a chart  500  showing rocking curve angle values for seed layer structures in accordance with various embodiments of the invention. As shown in row  505 , for the dual seed layer structure  128  ( FIG. 1 ) (with NiFe20 seed layer thickness of 2.1 nm and NiRu5W6 seed layer thickness of 1.4 nm), the rocking curve angle in the recording layer  135  is approximately 2.9 degrees. The rows  510 - 530  show the rocking curve angle values of the single seed layer structure  205  ( FIG. 2 ) (with NiRu5W6 seed layer thickness at various values). The rows  535 - 545  show the rocking curve angle values of a single NiFe20 seed layer thickness at various values. As shown in the chart  500 , the dual seed layer structure  128  at the thinner total size of 3.5 nm achieves an additional 0.5 degrees in decrease of in the Mag (0004) rocking curve angle as compared to the single seed layer structure  205  with the NiRu5W6 seed layer of 3.7 nm as well as a single NiFe20 seed layer of 3.5 nm. 
       FIG. 6  is a chart  600  showing recording performance for seed layer structures in accordance with various embodiments of the invention. Values for the coercivity field (Hc), nucleation field (Hn), switching field distribution (SFD), and saturation magnetic field (Hs) are listed for media with various thickness values of the dual seed layer structure  128  (NiFe20/NiRu5W6), the single seed layer structure  205  (NiRu5W6), and the seed layer NiFe20. The coercivity of a dual seed layer structure  128  with a thickness of 3.5 nm is higher, as shown in row  610 , as compared to the coercivity of a similar thickness single seed layer structure  205 , as shown in row  625 , and similar thickness single NiFe20 seed layer, as shown in row  655 . However, the similar thickness single seed layer structure  205  (with NiRu5W6) has higher coercivity values as compared to a similar thickness NiFe20 seed layer. 
       FIG. 7  is a block diagram of a magnetic disk drive  700  that can operate with a magnetic recording media  716  in accordance with an embodiment of the invention. In operation, the slider  733  is supported by a suspension as the slider flies above a disk  716 . The slider  733  includes the write head  723  that performs the task of writing magnetic transitions and the read head  712  that performs the task of reading the magnetic transitions. The electrical signals to and from the heads (read head  712  and write head  723 ) travel along the conductive paths  714  (e.g., leads) which are attached to or embedded in the slider suspension. The slider  733  is positioned over points of varying radial distances from the center of the disk  716  when the slider  733  performs reads or writes on the circular tracks (not shown) on the disk  716 . 
     The disk  716  is attached to a spindle  718  that is driven by a spindle motor  724  for rotating the disk  716 . As similarly discussed above, the disk  716  includes a substrate on which a plurality of thin films are deposited. The thin films include ferromagnetic material in which the write head  723  records the magnetic transitions in which information is encoded. The read head  712  reads information encoded by the magnetic transitions in the thin film ferromagnetic material. Other types of disk drive systems can be used with a disk according to an embodiment of the invention. 
     Other variations and modifications of the above-described embodiments and methods are possible in light of the teaching discussed herein. 
     The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. 
     These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.