JP5329212B2 - Magnetic storage medium manufacturing method - Google Patents

Abstract

Provided are a production method capable of producing a magnetic storage medium by suppressing distribution of magnetization reversal magnetic fields while employing an ion doping method, a magnetic storage medium produced by such production method, and an information storage device. A magnetization loss degree measurement process (Step S103) to measure a saturation magnetization loss degree by ion implantation into a sample; an anisotropic magnetic field calculation process (Step S104) to calculate an anisotropic magnetic field of a magnetic film before the saturation magnetization loss using the measured loss degree, under the premise that when the saturation magnetization is partially lost in areas other than a protection area, the magnetization reversal magnetic field in the protection area becomes identical with a predetermined magnetization reversal magnetic field; and a magnetic disk production process (Step S108) to form a magnetic film having the calculated anisotropic magnetic field and complete a bit-patterned magnetic disk by partial ion implantation into the magnetic film.

Description

  The present invention relates to a manufacturing method for manufacturing a magnetic storage medium, a magnetic storage medium, and an information storage device including the magnetic storage medium.

  Hard disk drives (HDD) have become the mainstream of information storage devices as mass storage devices capable of high-speed data access and high-speed transfer. With respect to this HDD, the surface recording density has been increasing at a high annual rate so far, and further improvement in recording density is still required.

  In order to improve the recording density of the HDD, it is necessary to reduce the track width and the recording bit length. However, if the track width is reduced, so-called magnetic interference is likely to occur between adjacent tracks. This interference is a generic term for a phenomenon in which magnetic recording information is overwritten on a non-target adjacent track during recording, or a phenomenon in which crosstalk occurs due to a leakage magnetic field from a non-target adjacent track during reproduction. It is a thing. These phenomena all cause a decrease in the S / N ratio of the reproduction signal, and cause a deterioration in error rate.

  On the other hand, when the recording bit length is shortened, a thermal fluctuation phenomenon occurs in which the performance of storing the recording bit for a long period of time decreases due to the influence of magnetic interference.

  Discrete track type magnetic storage media have been proposed as magnetic storage media that achieve short bit lengths and high track densities by avoiding these magnetic interference and thermal fluctuation phenomena. In addition to this discrete track type magnetic storage medium, a bit patterned type magnetic storage medium has also been proposed (see, for example, Patent Document 1). In particular, in a bit-patterned magnetic storage medium, the position of a recording bit is determined in advance, and a dot (magnetic dot) of a magnetic material is formed at the position of the determined recording bit so that there is no gap between the magnetic dots. Consists of magnetic material. When the magnetic dots are separated from each other in this way, the magnetic interaction between the magnetic dots is small, and the above-described interference and thermal fluctuation phenomena are avoided.

  Here, conventionally, many of bit patterned magnetic storage media are manufactured by the following manufacturing method. In this manufacturing method, first, a uniform magnetic film is formed on a substrate. Thereafter, the magnetic dots are formed by removing other areas from the magnetic film except for the areas used as bits by a technique such as etching. Then, a non-magnetic material is filled in the removed region, thereby forming an interdot separation band that magnetically separates the magnetic dots. A bit-patterned magnetic storage medium is obtained by such a series of processes.

  Here, in such a conventional manufacturing method, a difference in thickness is likely to occur between the magnetic dot and the dot dividing band. Therefore, in such a conventional manufacturing method, the surface of the magnetic storage medium needs to be flattened with high accuracy in order to stabilize the flying characteristics of the magnetic head on the magnetic storage medium. Therefore, the subject that it is necessary to perform a very complicated manufacturing process and the subject that manufacturing cost increases arise.

  In view of this, a processing method (ion doping method) has been proposed in which ions are implanted into a magnetic film to locally change magnetic characteristics to form a magnetic dot separation state (see, for example, Patent Document 2).

According to this ion doping method, ions are implanted to change the magnetic characteristics, so that complicated manufacturing processes such as etching, filling, and flattening are not required, and an increase in manufacturing cost can be significantly suppressed.
Japanese Patent No. 1888363 JP 2006-309841 A

  However, in the method of manufacturing a magnetic storage medium employing the above-described ion doping method, for example, when lot production is performed, there is a problem that the magnetization reversal magnetic field required for reversal of magnetization in the magnetic dots varies from lot to lot. It often happens.

  Heretofore, the problem that the magnetization reversal field varies when the magnetic storage medium is manufactured by the ion doping method has been described by taking a bit patterned magnetic storage medium as an example. However, such a problem is not limited to the bit-patterned magnetic storage medium, and is also a problem that applies to, for example, a discrete track magnetic storage medium. That is, such a problem is commonly applied to a magnetic storage medium including a magnetic part in which information is magnetically recorded and a low magnetic part having a saturation magnetization smaller than the saturation magnetization of the magnetic part. .

  In the present case, in view of the above circumstances, a manufacturing method capable of manufacturing a magnetic storage medium in which variation of the magnetization reversal magnetic field is suppressed while using an ion doping method, a magnetic storage medium manufactured using such a manufacturing method, and information An object is to provide a storage device.

  First, a basic method of manufacturing a magnetic storage medium that achieves the above object includes a first magnetic film formation process, a first ion implantation process, a disappearance measurement process, an anisotropic magnetic field calculation process, A magnetic film forming process and a second ion implantation process.

  The first magnetic film forming process is a process of forming a magnetic film.

  The first ion implantation process is a process for implanting ions into the magnetic film.

  The disappearance degree measurement process is a process of measuring the disappearance degree of saturation magnetization caused by the ion implantation in the first ion implantation process in the magnetic film.

  The anisotropic magnetic field calculation process is a process executed on the following assumptions. That is, when the saturation magnetization of the magnetic film disappears locally in other regions except for the protection region set at a predetermined location with the disappearance measured in the disappearance measurement process, The premise is that the magnetization reversal field is equal to a predetermined magnetization reversal field. The anisotropic magnetic field calculation process is a process for calculating the anisotropic magnetic field of the magnetic film before the disappearance of the saturation magnetization, based on this premise.

  In the second magnetic film forming process, a magnetic film having an anisotropic magnetic field equivalent to the anisotropic magnetic field calculated in the anisotropic magnetic field calculating process is formed on the substrate in the first magnetic film forming process. This is a process of forming under the same formation conditions as those of the magnetic film.

  In the second ion implantation process, an ion implantation condition in the first ion implantation process is locally applied to a region corresponding to the other region with respect to the magnetic film formed in the second magnetic film formation process. This is a process of performing ion implantation under the same ion implantation conditions.

  Next, a basic magnetic storage medium that achieves the above object includes a substrate, a magnetic part, and a low magnetic part.

  The magnetic part undergoes the first magnetic film formation process, the first ion implantation process, the disappearance measurement process, the anisotropic magnetic field calculation process, and the second magnetic film formation process. It has a formed magnetic film and information is recorded magnetically.

  The low magnetic part has an implanted film formed through a local ion implantation process into a magnetic film continuous with the magnetic film of the magnetic part, and has a saturation magnetization smaller than the saturation magnetization of the magnetic part. Is. The local ion implantation process for obtaining the low magnetic part is a process of performing ion implantation under the same ion implantation conditions as those in the first ion implantation process.

  An information storage device of a basic form for achieving the above object includes the magnetic storage medium, a magnetic head, and a head position control mechanism.

  The magnetic head performs magnetic recording and / or reproduction of information on the magnetic part in proximity to or in contact with the magnetic storage medium.

  The head position control mechanism moves the magnetic head relative to the surface of the magnetic storage medium, and positions the magnetic head on a magnetic part for recording and / or reproducing information by the magnetic head. Is.

  According to the present invention, a manufacturing method capable of manufacturing a magnetic storage medium while suppressing variations in the magnetization reversal magnetic field while using an ion doping method, and a magnetic storage medium and an information storage device manufactured by such a manufacturing method are provided. Can be obtained.

  Hereinafter, as specific embodiments of the magnetic storage medium manufacturing method, the magnetic storage medium, and the information storage device described above with respect to the basic form, first and second types of embodiments will be described with reference to the drawings.

  First, the first embodiment will be described.

  FIG. 1 is a diagram showing an internal structure of a hard disk device (HDD) which is a specific embodiment of an information storage device.

  A hard disk device (HDD) 100 shown in this figure is incorporated in a host device such as a personal computer and is used as information storage means in the host device.

  In the hard disk device 100, a disk-shaped magnetic disk 10 is housed in a plurality of housings H so as to overlap in the depth direction of the figure. This magnetic disk 10 corresponds to a specific embodiment of the magnetic storage medium whose basic form has been described above.

  Here, the following application forms are suitable for the above-described basic forms of the magnetic storage medium and the information storage device. In this application mode, the magnetic part is a magnetic dot regularly arranged on the substrate, on which information is magnetically recorded. Further, in this application mode, the low magnetic portion is an interdot separation band that is provided between the magnetic dots and inhibits magnetic coupling between the magnetic dots.

  This application mode corresponds to a bit patterned magnetic storage medium in which magnetic dots on which bit information is recorded are provided in advance on each location on the substrate. Since the bit patterned magnetic storage medium effectively avoids interference and thermal fluctuation as described above, the above-described application mode corresponding to such a bit patterned magnetic storage medium is preferable. is there.

  The magnetic disk 10 shown in FIG. 1 is a bit patterned magnetic storage medium, and corresponds to a specific embodiment of this application. The magnetic disk 10 is also a so-called perpendicular magnetic storage medium in which information is recorded with a magnetic pattern by magnetization in a direction perpendicular to the front and back surfaces of each magnetic dot.

  The magnetic disk 10 rotates around the disk shaft 11 in the housing H.

  A swing arm 20, an actuator 30, and a control circuit 50 are also housed in the housing H of the hard disk device 100.

  The swing arm 20 moves along the surface of the magnetic disk 10. The swing arm 20 holds a magnetic head 21 for writing and reading information with respect to the magnetic disk 10 at the tip. The swing arm 20 is rotatably supported by the housing H by a bearing 24. The swing arm 20 rotates within a range of a predetermined angle about the bearing 24 to move the magnetic head 21 along the surface of the magnetic disk 10. This magnetic head corresponds to an example of the magnetic head in the basic form described above.

  The actuator 30 drives the swing arm 20 described above.

  The control circuit 50 controls driving of the swing arm 20 by the actuator 30, reading / writing of information by the magnetic head 21, exchange of information between the HDD 100 and the host device, and the like.

  A combination of the swing arm 20, the bearing 24, the actuator 30, and the control circuit 50 corresponds to an example of the head position control mechanism in the basic form described above.

  FIG. 2 is a perspective view schematically showing the structure of the magnetic disk shown in FIG.

  FIG. 2 shows a part cut out from a disk-shaped magnetic disk.

  The magnetic disk 10 shown in FIG. 2 has a structure in which a plurality of magnetic dots 10 a are arranged in a regular arrangement on a glass substrate 60. Information corresponding to 1 bit is magnetically recorded on each of the magnetic dots 10a. The magnetic dots 10 a are arranged in a circle around the center of the magnetic disk 10. The row of magnetic dots arranged in this way forms a track 10c. The glass substrate 60 corresponds to an example of the substrate in the basic form described above. Further, the magnetic dot 10a corresponds to an example of the magnetic part in the basic form described above, and also corresponds to an example of the magnetic dot in the application form described above corresponding to the bit patterned magnetic storage medium.

  Further, between the magnetic dots 10a, an interdot separation zone 10b in which the magnetic anisotropy and saturation magnetization are lower than the magnetic anisotropy and saturation magnetization of the magnetic dot 10a is formed. The interdot dot band 10b magnetically divides between the magnetic dots 10a. That is, the magnetic interaction between the magnetic dots 10a is reduced by the interdot dot band 10b. This inter-dot dividing band 10b corresponds to an example of the low magnetic portion in the above-described basic form, and also corresponds to an example of the inter-dot dividing band in the above-described applied form corresponding to the bit-patterned magnetic storage medium. .

  Thus, when the magnetic interaction between the magnetic dots 10a is small, the magnetic interaction between the tracks 10c is small when recording / reproducing information on the magnetic dots 10a, so that there is little magnetic interference between the tracks. . Further, in each magnetic dot 10a, the boundary of recorded information bits does not fluctuate due to heat, so that a so-called thermal fluctuation phenomenon is also avoided. Therefore, according to the bit patterned magnetic disk 10 as shown in FIG. 2, the track width can be reduced and the recording bit length can be shortened, so that a magnetic recording medium having a high recording density can be realized.

  A method for manufacturing the magnetic disk 10 will be described below.

  This method of manufacturing the magnetic disk 10 corresponds to a specific embodiment of the magnetic storage medium manufacturing method described above with respect to the basic mode.

  Here, the following application forms are suitable for the basic form of the magnetic storage medium manufacturing method. That is, the ion implantation process is a process in which ions are locally implanted between the plurality of locations using a plurality of locations regularly arranged in the direction in which the magnetic film spreads as the protection region. Application form.

  This application mode corresponds to a magnetic storage medium manufacturing method in which a bit patterned magnetic storage medium is manufactured. Since the bit patterned magnetic storage medium effectively avoids interference and thermal fluctuation phenomena as described above, the above-described application mode in which such a bit patterned magnetic storage medium is manufactured is preferable. It is. The method of manufacturing the magnetic disk 10 described below corresponds to a specific embodiment of this application mode.

  Here, the magnetic disk manufacturing method of this embodiment is a magnetic disk manufacturing method for mass-producing the magnetic disk 10 shown in FIGS. 1 and 2 by lot production. An ion doping method is used for manufacturing individual magnetic disks 10 in mass production.

  Prior to the description of the magnetic disk manufacturing method of this embodiment, a comparative example for comparison with the ion doping method used in this manufacturing method will be described first. This comparative example is a type of manufacturing method in which a bit patterned magnetic storage medium is manufactured by etching and filling with a nonmagnetic material.

  FIG. 3 is a diagram showing a manufacturing method of a type in which a bit patterned magnetic storage medium is manufactured by etching and filling with a nonmagnetic material.

  In this type of manufacturing method, first, the magnetic film 2 is formed on the substrate 1 in the film forming step (A).

  Next, in the nanoimprint process (B), a resist 3 made of an ultraviolet curable resin is applied on the magnetic film 2, and a mold 4 with nano-sized holes 4 a is placed on the resist 3. As a result, the resist 3 enters the nano-sized hole 4a, and the dots 3a of the resist 3 are formed. Then, the resist 3 is irradiated with ultraviolet rays through the mold 4, so that the resist 3 is cured and the dots 3 a are printed on the magnetic film 2. Further, after the resist 3 is cured, the mold 4 is removed.

  Thereafter, etching is performed in the etching step (C), so that the magnetic film is removed leaving the magnetic dots 2 a protected by the dots 3 a of the resist 3. After etching, the dots 3 a of the resist 3 are removed by chemical treatment, and only the magnetic dots 2 a remain on the substrate 1.

  In the filling step (D), the space between the magnetic dots 2a is filled with a nonmagnetic material. Thereafter, the surface is flattened through a flattening step (E), whereby the bit patterned magnetic storage medium 6 is completed (F).

  According to this type of manufacturing method, high-precision flattening is required in the flattening step (E) in order to stabilize the flying characteristics of the magnetic head on the magnetic storage medium 6. Therefore, the subject that it is necessary to perform a very complicated manufacturing process and the subject that manufacturing cost increases arise.

  On the other hand, in this embodiment, as described above, the ion doping method is adopted.

  The ion doping method used in the magnetic disk manufacturing method of this embodiment will be described below.

  FIG. 4 is an explanatory diagram for explaining the ion doping method.

  FIG. 4 shows an underlayer 61, a magnetic film 62, a protective layer 63, and a resist pattern 64 that are formed on the glass substrate 60 prior to ion implantation.

  Hereinafter, the film formation of each of these layers will be described.

  Various values such as conditions and film thicknesses in the magnetron sputtering apparatus in the following description of FIG. 4 are not limited to the following values, and other values may be used as appropriate.

In the present embodiment, first, a well-cleaned glass substrate 60 is set in a magnetron sputtering apparatus and evacuated to 5 × 10 ⁻⁵ Pa or less. Thereafter, the glass substrate 60 is not heated, and the (111) crystal orientation of fcc-Pd having a film thickness of 3 nm is performed at an Ar gas pressure of 0.67 Pa. The glass substrate is used as an underlayer 61 for crystal orientation of the magnetic layer. 60 is formed.

  Subsequently, a magnetic film 62 is formed on the underlayer 61. In this embodiment, the magnetic film 62 has an artificial lattice structure in which Co atomic layers and Pd atomic layers are alternately stacked. After the formation of the underlayer 61, the magnetic film 62 having the artificial lattice structure is continuously formed with the Co monoatomic layer and the Pd at an Ar gas pressure of 0.67 Pa without returning the magnetron sputtering apparatus to atmospheric pressure. It is formed by repeatedly laminating a single atomic layer.

  After the magnetic film 62 is formed, a protective layer 63 made of diamond-like carbon and having a thickness of 4 nm is formed on the magnetic film 62. Then, a resist is applied on the protective layer 63, and a columnar resist having a rectangular cross section of 9 nm × 27 nm corresponding to the outer shape of the magnetic dot 10a of FIG. A pattern 64 is formed.

  When film formation of each layer is completed in this way, ion implantation is performed next.

  In the ion implantation, either one of oxygen ions and nitrogen ions 65 is irradiated from above the resist pattern 64. As a result, the irradiated ions 65 are implanted into the magnetic film 62. Further, the acceleration voltage in the ion implantation at this time is set so that the ions 65 are implanted into the central portion of the magnetic film 62. Note that the acceleration voltage of the ions 65 is preferably 1 keV or more and 10 keV or less in consideration of a realistic magnetic film thickness and damage to the magnetic film during ion implantation.

  In the ion implantation as described above, the ions 65 directed toward the resist pattern 64 remain in the resist pattern 64, and the ions 65 directed toward the gap between the resist patterns 64 are implanted into the magnetic film 62. As a result, saturation magnetization and magnetic anisotropy are reduced in the magnetic film 62 other than the region protected by the resist pattern 64. The region in which the saturation magnetization and magnetic anisotropy are reduced is the interdot separation band 10b in FIG. On the other hand, a region in which saturation magnetization and magnetic anisotropy are maintained by being protected by the resist pattern 64 becomes the magnetic dot 10a.

  After this ion implantation, the resist pattern 64 is removed by SCl cleaning, and the magnetic disk 10 of FIG. 2 is completed.

  Here, in the ion doping method described above, in many cases, the saturation magnetization slightly remains in the above-described interdot separation zone 10b, and the magnetization switching magnetic field in the magnetic dot 10a is reduced due to the remaining. Furthermore, the degree of disappearance of saturation magnetization due to ion implantation depends on the following conditions during manufacturing by sputtering. The conditions at the time of manufacturing by sputtering include conditions such as the thickness of a magnetic film obtained by sputtering, the purity of a target used in sputtering, and gas pressure. As a result, the degree of decrease in the magnetization reversal field also depends on these conditions.

  Furthermore, in general, in lot production, it is highly possible that the above-mentioned various conditions during production change from lot to lot. And the fall degree of a magnetization reversal magnetic field changes with the fluctuation | variation of the disappearance degree of saturation magnetization resulting from the fluctuation | variation of such various conditions. As a result, in the conventional magnetic disk manufacturing method using the ion doping method, such a problem that the magnetization reversal magnetic field varies from lot to lot often occurs.

  In the magnetic disk manufacturing method of the present embodiment, as described below, the ion doping method is applied to mass production in lot production while avoiding the variation of the magnetization reversal magnetic field for each lot.

  FIG. 5 is a flowchart showing the magnetic disk manufacturing method according to the first embodiment.

  In the magnetic disk manufacturing method shown in this flowchart, the magnetic disks shown in FIGS. 1 and 2 are mass-produced by lot production using an ion doping method.

  In the manufacturing method shown in the flowchart of FIG. 5, first, before starting mass production, the disappearance degree of saturation magnetization that would be caused by ion implantation at the time of mass production is grasped using a sample. The determination of the disappearance degree using this sample is performed by a series of processes from step S101 to step S103 described below.

  In the process of step S101, the next laminate is created as a sample. 4 is a laminate in which an underlayer, a magnetic film, and a protective layer equivalent to the underlayer 61, the magnetic film 62, and the protective layer 63 in FIG. 4 are laminated on a glass substrate equivalent to the glass substrate 60 in FIG. . Each layer in this sample is formed under the same numerical conditions as those described with reference to FIG.

  In this embodiment, in the artificial lattice structure of the magnetic film of this sample, the layer thickness ratio of the Co atomic layer to the Pd atomic layer (sample layer thickness ratio) is determined in advance by the same process as that of Step S105 described later. Desired. In the process of step S101, a sample magnetic film is created with the obtained sample layer thickness ratio. The details of how to obtain the layer thickness ratio in the magnetic film of this sample will be described together with the description of the processing in step S105.

  In this embodiment, the magnetic film of this sample has a Pd atomic layer thickness of 0.7 nm in the artificial lattice structure. The layer thickness of the Co atomic layer is a value obtained by multiplying the 0.7 nm layer thickness by the sample layer thickness ratio. Further, here, a pair of an atomic layer of Pd and an atomic layer of Co is regarded as a kind of layer as a unit of lamination. The sample magnetic layer is formed of 20 layers.

  The processing in step S101 corresponds to an example of the first magnetic film formation process in the basic mode described above.

  Next, in the process of step S102, first, the saturation magnetization of the magnetic film in the sample is measured. Thereafter, ion implantation is performed on the sample. In the ion implantation in step S102, ion implantation conditions equivalent to the ion implantation conditions described with reference to FIG. 4 are used as ion implantation conditions such as ion species and acceleration voltage. The processing in step S102 corresponds to an example of the first ion implantation process in the basic mode described above.

  In the subsequent step S103, the saturation magnetization of the magnetic film in the sample after ion implantation is measured. Then, by dividing the measured saturation magnetization after ion implantation by the saturation magnetization before ion implantation measured in step S102, the disappearance degree of saturation magnetization by ion implantation is obtained. The calculated saturation magnetization disappearance is considered to correspond to the saturation magnetization disappearance that will be caused by the subsequent ion implantation during mass production. The processing in step S103 corresponds to an example of the disappearance degree measurement process in the basic form described above.

  Hereinafter, the description will be continued assuming that the saturation magnetization disappearance obtained in step S103 is 90%.

  The following processing is executed using the disappearance degree obtained in step S103 (step S104). In this process, when the interdot separation band 10b of FIG. 2 or FIG. 4 is formed by erasing the saturation magnetization with the disappearance obtained in step S103, the magnetization reversal magnetic field at the magnetic dot 10a is designed. It is executed on the assumption that it becomes equal to the magnetization reversal field above. Under this assumption, the anisotropic magnetic field of the original magnetic layer before saturation magnetization disappears by ion implantation is calculated.

  In this embodiment, this anisotropic magnetic field is calculated using a so-called LLG (Landau-Liftshitz-Gilbert) equation, which is a mathematical model expressing the magnetic characteristics of a magnetic film or the like.

  In the present embodiment, an equation for obtaining the anisotropic magnetic field of the magnetic dot 10a, which is obtained by modifying this LLG equation and using the saturation magnetization disappearance in the interdot separation zone 10b of FIG. 2 as a variable, is used. .

  In the process of step S104, the designed magnetization switching magnetic field is substituted for the magnetization switching magnetic field that is one of the parameters in this equation.

  Here, the anisotropic magnetic field of the magnetic dots 10a is equal to the anisotropic magnetic field of the magnetic film before ion implantation in the ion doping method. Further, the saturation magnetization disappearance in the interdot separation zone 10b is the saturation magnetization disappearance due to the ion implantation. That is, the expression used in the process of step S104 is an expression representing a dependency relationship in which the anisotropic magnetic field of the magnetic film before ion implantation depends on the saturation magnetization disappearance level due to ion implantation. The process of step S104 corresponds to an example of an anisotropic magnetic field calculation process in the basic form described above. Hereinafter, the dependency represented by the equation derived from the LLG equation is referred to as saturation magnetization disappearance dependency of the anisotropic magnetic field.

  FIG. 6 is a graph showing the saturation magnetization disappearance dependence of the anisotropic magnetic field represented by the equation used in step S104 of FIG.

  FIG. 6 shows a graph G1 showing the saturation magnetization disappearance dependence of the anisotropic magnetic field when a 5 kOe magnetization switching magnetic field is adopted as the designed magnetization switching magnetic field.

  The graph G1 includes a line L1 representing the saturation magnetization disappearance dependence of the anisotropic magnetic field.

  In the graph G1, in addition to the magnetization reversal magnetic field, the following parameters are set. First, the external dimension (vertical × horizontal) of the magnetic dot 10a is set to a designed value of 9 nm × 27 nm.

  Further, the saturation magnetization of the magnetic dot 10a is set to 500 emu / cc, which is an empirical predicted value, and the anisotropic magnetic field of the interdot separation zone 10b is also set to 100 Oe, which is an empirical predicted value. Further, the exchange coupling force in the magnetic dot 10a is also set to 2 μerg / cm, which is an empirical predicted value, and the exchange coupling force between the magnetic dot 10a and the interdot separation band 10b is also an empirical predicted value of 0 .5 μerg / cm.

  As can be seen from this graph G1, the anisotropic magnetic field of the magnetic film 62 before the saturation magnetization disappears, which satisfies the above assumption, decreases almost linearly as the saturation magnetization disappearance increases.

  Here, according to the above assumption that the saturation magnetization disappearance obtained in step S103 of FIG. 5 is 90%, the anisotropic magnetic field of the magnetic film 62 before the saturation magnetization disappears becomes 18 kOe.

  Furthermore, in this embodiment, the anisotropic magnetic field (sample anisotropic magnetic field) for obtaining the layer thickness ratio (sample layer thickness ratio) of the Co atomic layer to the Pd atomic layer in the sample created in step S101 is: It is obtained by the same process as the process of step S104. However, in this embodiment, the sample anisotropic magnetic field is obtained under the assumption that the saturation magnetization disappearance due to ion implantation is 100%. According to the graph G1 in FIG. 6, this sample anisotropic magnetic field is 14 kOe.

  With respect to this sample anisotropic magnetic field, the anisotropic magnetic field obtained based on the disappearance degree obtained in step S103 in the process of step S104 is the anisotropy in the magnetic film actually formed during mass production as will be described later. Magnetic field. Therefore, hereinafter, the anisotropic magnetic field calculated in step S104 is referred to as an actual anisotropic magnetic field in distinction from the sample anisotropic magnetic field.

  When the actual anisotropic magnetic field is calculated in step S104, the following conditions necessary for realizing the actual anisotropic magnetic field in the magnetic film 62 are obtained (step S105).

  Here, in this embodiment, the magnetic film 62 subjected to ion implantation is a magnetic film having an artificial lattice structure in which Co atomic layers and Pd atomic layers are alternately stacked as described above. In the magnetic film having such an artificial lattice structure, the anisotropic magnetic field in the magnetic film depends on the layer thickness ratio of the Co atomic layer to the Pd atomic layer. That is, the anisotropic magnetic field can be adjusted by adopting the artificial lattice structure as described above as the magnetic film 62 and adjusting the layer thickness ratio of the Co atomic layer. Accordingly, in step S105, a desired layer thickness ratio of the Co atomic layer is obtained as a condition necessary for realizing the actual anisotropic magnetic field obtained in step S104.

  Here, in the present embodiment, the layer thickness ratio is obtained based on the following measurement data prepared in advance. That is, the measurement data represents a dependency relationship in which the anisotropic magnetic field depends on the layer thickness ratio of the Co atomic layer. Hereinafter, the dependency represented by the measurement data is referred to as the layer thickness ratio dependency of the anisotropic magnetic field. This measurement data was obtained by forming a plurality of magnetic films having different Co atomic layer thickness ratios and measuring the anisotropic magnetic field in each magnetic film. In step S105, the layer thickness ratio corresponding to the actual anisotropic magnetic field calculated in step S104 is obtained based on such measurement data.

  FIG. 7 is a graph showing an example of measurement data used in step S105 of FIG.

  FIG. 7 shows a graph G2 on which measurement data representing the dependence of the anisotropic magnetic field on the layer thickness ratio is plotted. The graph G2 includes a line L2 representing the layer thickness ratio dependence of the anisotropic magnetic field.

  The graph G2 also includes a line L3 representing a dependency relationship in which the saturation magnetization of the magnetic film 62 before ion implantation depends on the layer thickness ratio of the Co atomic layer. Hereinafter, the dependency represented by the line L3 is referred to as layer thickness ratio dependency of saturation magnetization. The line L3 representing the layer thickness ratio dependency of the saturation magnetization is used in step S106 described later in FIG.

  Further, two lines L2 and L3 shown in the graph G2 represent measurement data obtained for the magnetic film having an artificial lattice structure in which the thickness of the atomic layer of Pd is 0.7 nm and the number of stacks is 20 layers. Is.

  Hereinafter, the number of layers (20 layers) on which the measurement data is based is referred to as a default number of layers.

  In this example, the actual anisotropic magnetic field obtained in step S104 corresponding to the saturation magnetization disappearance (90%) obtained in step S103 is 18 kOe as described above. From the line L2 representing the dependence of the anisotropic magnetic field on the layer thickness ratio in the graph G2 in FIG. 7, the layer thickness ratio (hereinafter referred to as the actual layer thickness ratio) for obtaining this actual anisotropic magnetic field is approximately 0. .42.

  Furthermore, in the present embodiment, the sample layer thickness ratio in the sample created in step S101 is obtained by the same process as the process in step S105. In this example, since the sample anisotropic magnetic field is 14 kOe as described above, the sample layer thickness ratio is 0.72 according to the graph G2 in FIG.

  In step S101 described above, a sample having a magnetic film having an artificial lattice structure in which a Pd atomic layer and a Co atomic layer are stacked at the sample layer thickness ratio obtained by the same processing as in step S105 is formed. It will be.

  Next, in the flowchart of FIG. 5, the saturation magnetization (hereinafter referred to as the actual saturation magnetization) in the magnetic film having the artificial lattice structure in which the layer thickness ratio of the Co atomic layer is the actual layer thickness ratio is obtained. (Step S106). Further, in the process of step S106, saturation magnetization (hereinafter referred to as sample saturation magnetization) in the magnetic film of the sample is also obtained.

  For the calculation of the two saturation magnetizations in step S106, a line L3 representing the layer thickness ratio dependence of the saturation magnetization in the graph G2 in FIG. 7 is used.

  From this line L3, a value of about 450 emu / cc is obtained as the actual saturation magnetization corresponding to the actual layer thickness ratio (0.42) obtained in step S105. On the other hand, a value of about 550 emu / cc is obtained as the sample saturation magnetization corresponding to the sample layer thickness ratio (0.72).

  When two types of saturation magnetization are obtained in step S106, the actual number of layers in the magnetic film having the artificial lattice structure is obtained as follows based on the saturation magnetization (step S107).

  In the present embodiment, the actual number of layers is determined so that the product of the actual saturation magnetization and the actual number of layers is 90% or more of the product of the sample saturation magnetization and the default number of layers.

  This actual method for determining the number of layers is based on the following reason.

  In general, information reproduction with respect to a magnetic disk is performed by detecting a leakage magnetic field generated by magnetization carrying information in a magnetic dot by a magnetic head. At this time, the reproduction signal obtained by the magnetic head increases as the saturation magnetization of the magnetic dots increases or as the volume of the magnetic dots increases. For this reason, for example, when it is assumed that the saturation magnetization is small and a reproduction signal of a desired level cannot be obtained, the reproduction signal of a desired level is realized by increasing the volume by slightly thickening the magnetic dots. It becomes possible. When the magnetic dots have an artificial lattice structure as in the present embodiment, it is possible to realize a reproduction signal having a desired level as described above by increasing the number of layers in the artificial lattice structure. At this time, if the product of the saturation magnetization and the number of stacked layers is 90% or more of the product of the saturation magnetization and the number of stacked layers in a magnetic dot from which a reproduction signal of a desired level is obtained, the reproduction signal of the desired level is The developer found this to be achieved.

  In the present embodiment, the level of the reproduction signal obtained by the magnetic dots when the interdot dot band is formed with a saturation magnetization disappearance of 100% is adopted as the target level. Here, the magnetic film of the above sample is formed with a layer thickness ratio obtained on the assumption that the saturation magnetization disappearance is 100 percent. Therefore, in step S107 in FIG. 5, the actual number of stacked layers is such that the product of the actual saturation magnetization and the actual number of stacked layers is 90% or more of the product of the sample saturated magnetization and the default number of stacked layers. Is required.

  In the specific example described above, the sample saturation magnetization is 550 emu / cc, the default number of layers is 20, and 90 percent of the product of both is 9900. On the other hand, since the actual saturation magnetization is 450 emu / cc, the actual number of stacked layers is 22 or more.

  Through the processing up to step S107 described above, the layer thickness ratio and the number of layers necessary to realize the actual anisotropic magnetic field calculated in step S105 are obtained.

  In the magnetic disk manufacturing process (step S108) subsequent to step S107, a process using the layer thickness ratio and the number of stacked layers is executed.

  FIG. 8 is a diagram showing details of the magnetic disk manufacturing process (step S108).

  First, in the film forming step (A), the base layer 61, the magnetic film 62, and the protective layer 63 shown in FIG. 4 are formed on the glass substrate 60. In FIG. 8, the base layer 61 and the protective layer 63 shown in FIG. 4 are not shown for the sake of clarity.

  The formation here is performed under numerical conditions equivalent to the various numerical conditions described with reference to FIG. 4 when the sample is formed in step S101. However, the layer thickness ratio of the Co atomic layer 62a in the magnetic film 62 and the number of layers of the set of the Co atomic layer 62a and the Pd atomic layer 62b are the layers obtained by the processing up to step S107 in FIG. The thickness ratio and the number of layers are used. This film forming step (A) corresponds to an example of a second magnetic film forming process in the basic mode of the magnetic storage medium manufacturing method described above.

  In this embodiment, as described above, the magnetic film 62 formed in this film forming step (A) has an artificial lattice structure in which Co atomic layers 62a and Pd atomic layers 62b are alternately stacked. doing. And the artificial lattice structure here is constructed | assembled by the layer thickness ratio and lamination | stacking number calculated | required as mentioned above.

  In the present embodiment, as described above, the actual anisotropic magnetic field calculated in step S102 of FIG. 5 can be realized by the artificial lattice structure having the layer thickness ratio obtained in step S105.

  This means that the following application forms are preferable to the basic form described above.

  In this application mode, both the first magnetic film forming process and the second magnetic film forming process form a magnetic film having an artificial lattice structure in which Co atomic layers and Pd atomic layers are alternately stacked. It has become a process. In this application mode, the layer thickness of the Co atomic layer with respect to the Pd atomic layer is required to realize the anisotropic magnetic field calculated in the anisotropic magnetic field calculation process with the magnetic film having the artificial lattice structure. It has a layer thickness ratio calculation process for calculating the ratio. Further, in this application mode, the second magnetic film forming process includes alternately stacking Co atomic layers and Pd atomic layers at a layer thickness ratio calculated in the layer thickness ratio calculating process. This is a process of forming a magnetic film having a lattice structure.

  According to this application mode, the desired anisotropy calculated in the anisotropic magnetic field calculation process can be achieved by a simple method of appropriately adjusting the layer thickness ratio of the Co atomic layer in the magnetic film having the artificial lattice structure. A magnetic field can be realized.

  The process of step S105 in FIG. 5 corresponds to an example of a layer thickness ratio calculation process in this application mode. 8 corresponds to an example of a second magnetic film forming process in this application mode.

  In the present embodiment, as described above, the level of the reproduction signal obtained from the actual magnetic disk 10 can be adjusted to the target level by the artificial lattice structure having the number of layers obtained in step S107. it can. This means that the following application forms are more suitable for the above application forms employing magnetic films having an artificial lattice structure.

  This application form has a stacking number calculation process. This stacking number calculating process is a process of calculating the number of atomic layers in the magnetic film formed in the second magnetic film forming process. The calculation is based on the product of the saturation magnetization and the number of atomic layers in the magnetic film formed in the first magnetic film formation process, and in the magnetic film formed in the second magnetic film formation process. This is executed so that the product of the saturation magnetization and the number of atomic layers satisfies a predetermined degree of approximation. Further, in this application mode, the second magnetic film forming process is a process of forming the artificial lattice structure magnetic film by stacking the atomic layers having the number of atomic layers calculated in the stacking number calculating process. Yes.

  According to this application mode, a magnetic film that generates a leakage magnetic field of almost the same level as the leakage magnetic field generated from the magnetic film formed in the first magnetic film formation process is formed in the second magnetic film formation process. The Rukoto. The level of the leakage magnetic field generated from the magnetic film affects the level of a reproduction signal obtained from a bit patterned magnetic disk or the like formed using the magnetic film. Therefore, according to this application mode, a reproduction signal of a desired level can be obtained by a simple operation such as forming a magnetic film with saturation magnetization and the number of stacked layers so that a desired leakage magnetic field is generated in the first magnetic film forming process. The resulting magnetic disk can be obtained.

  The process of step S107 in FIG. 5 corresponds to an example of a stacking number calculation process in this application mode. Also, the product of the sample saturation magnetization and the default number of layers is the product of “the product of the saturation magnetization and the number of atomic layers in the magnetic film formed in the first magnetic film formation process” in this application. It corresponds to an example. Further, the product of the actual saturation magnetization and the actual number of stacked layers is referred to as “product of the saturation magnetization and the number of atomic layers in the magnetic film formed in the second magnetic film forming process” referred to in this application mode. It corresponds to an example. In this embodiment, an approximation degree of 90% or more is adopted as an example of the “approximation degree” in this application form.

  Further, the film forming step (A) in FIG. 8 corresponds to an example of a second magnetic film forming process in this application mode.

  Following the film forming step (A) described above, the nanoimprint step (B) is performed. In this nanoimprint step (B), a resist made of an ultraviolet curable resin is applied on the magnetic film 62, and a mold 66 having nano-sized holes 66a is placed on the resist. As a result, the resist enters the nano-sized hole 66a, and the resist pattern 64 shown in FIG. 4 is formed. Then, the resist is cured by irradiating the resist with ultraviolet rays through the mold 66, and the resist pattern 64 is printed on the magnetic film 62. Further, the mold 66 is removed after the resist is cured.

  After the nanoimprint process (B), the process proceeds to the ion implantation process (C). In this ion implantation step (C), ions are irradiated from above the magnetic film 62 on which the resist pattern 64 is printed. As a result, ions irradiated to a portion other than the resist pattern 64 are implanted into the magnetic film 62. This ion implantation step (C) corresponds to an example of the ion implantation step in the basic form described above. This ion implantation step (C) also corresponds to an example of the second ion implantation process in the above-described applied mode corresponding to the manufacture of the bit patterned magnetic storage medium.

  Here, in the present embodiment, one of oxygen ions and nitrogen ions is used as the implanted ions. These ions can reliably reduce the anisotropic magnetic field and saturation magnetization of the magnetic film 62 having the artificial lattice structure of the present embodiment and the magnetic film of the Co—Cr—Pt alloy in the second embodiment described later. it can.

  This means that the application form in which the second ion implantation process is a process using one of oxygen ions and nitrogen ions as the ions is preferable to the basic form described above. I mean.

  The ion implantation step (C) in FIG. 8 corresponds to an example of a second ion implantation process in this application mode.

  Further, the following application forms are also suitable for the basic forms described above. This application form has a mask formation process. This mask formation process is a process of forming a mask that inhibits ion implantation into the protective region on the magnetic film. In this application mode, the second ion implantation process applies ions from above the magnetic film on which the mask is formed, so that other regions except for the protection region protected by the mask are applied. It is a process of implanting the ions locally.

  According to this application mode, a portion that does not require ion implantation is reliably protected by the mask, and the magnetic dot formation accuracy is high. The nanoimprint process (B) in FIG. 8 corresponds to an example of a mask formation process in this application mode, and the ion implantation process (C) also corresponds to an example of a second ion implantation process in this application mode.

  Further, an application mode in which the mask formation process is a process of forming the mask with a resist is further preferable to the preferable application mode having a mask formation process. Also. In contrast to the above preferred application mode having a mask formation process, an application mode in which the mask formation process is a process of forming the mask with a resist by a nanoimprint process is further preferable.

  Mask formation with a resist is technically stable and high-precision mask formation can be expected. Mask formation by a nanoimprint process is preferable because a mask pattern at a nano level can be easily created. The nanoimprint process (B) shown in FIG. 8 also corresponds to an example of a mask formation process in these more preferable applications.

  In the nanoimprint described above, the resist is not completely removed even at the location where ions are to be implanted. However, when the resist is thin, ions pass through the resist and are injected into the magnetic film 62. When the resist is thick (that is, where the resist pattern 64 is formed), the ions stop at the resist and do not reach the magnetic film. . For this reason, a desired dot pattern can be formed.

  Further, in the ion implantation step (C) shown in FIG. 8, the acceleration voltage of ions is set so that ions are implanted into the central portion of the magnetic film 62. This acceleration voltage varies depending on the ion species, and varies depending on the depth to the magnetic film center and the material.

  In the magnetic film 62 where ions are implanted by this ion implantation step (C), ions remain inside, the crystal structure is distorted, and the coercive force and saturation magnetization are reduced. After the ion implantation, the resist pattern 64 is removed by chemical treatment.

  Through such an ion implantation step (C), an interdot separation band 10b that divides the magnetic interaction between the magnetic dots 10a is formed between the magnetic dots 10a. The disk 10 is completed (D).

  In the present embodiment, the saturation magnetization of the magnetic film 62 that has undergone ion implantation in the above-described ion implantation step (C) is the saturation magnetization loss degree grasped in step S101 of FIG. 5 (in this example, 90 percent). ) Disappears. As a result, some saturation magnetization remains in the interdot separation zone 10b formed by ion implantation. The saturation magnetization remaining in the interdot separation zone 10b reduces the magnetization reversal field in the magnetic dot 10a. However, in the present embodiment, the anisotropic magnetic field of the magnetic film 62, and hence the anisotropic magnetic field of the magnetic dot 10a, is calculated in step S104, and the designed magnetization reversal magnetic field in anticipation of such reduction. Is adjusted to an anisotropic magnetic field. As a result, in the present embodiment, the bit patterned magnetic disk 10 having the designed magnetization reversal magnetic field is manufactured regardless of the saturation magnetization disappearance.

  Further, the saturation magnetization of the magnetic film 62 affects the level of the reproduction signal obtained for the magnetic dot 10a. However, in the present embodiment, the number of stacked layers in the magnetic film 62 having an artificial lattice structure is adjusted to the appropriate number of layers calculated in step S102. As a result, in this embodiment, the bit patterned magnetic disk 10 from which a desired level of reproduction signal is obtained is manufactured.

  In the magnetic disk manufacturing method of the present embodiment shown in FIG. 5, the magnetic disk manufacturing process (step S108) shown in detail in FIG. 8 is performed until the number of magnetic disks 10 reaches a prescribed mass production number (step S109). (Yes determination) is repeated.

  According to the magnetic disk manufacturing method of the first embodiment described above, the saturation magnetization disappearance is grasped for each lot. Then, based on the grasped saturation magnetization disappearance level, the bit patterned magnetic disk 10 having a designed magnetization reversal magnetic field and capable of obtaining a reproduction signal of a desired level is manufactured. As a result, the magnetic disk 10 in which the variation of the magnetization reversal magnetic field for each lot is suppressed is manufactured. Also, the HDD 100 mass-produced using these magnetic disks 10 is one in which variations in the magnetization reversal magnetic field of the mounted magnetic disk 10 are suppressed.

  This is the end of the description of the first embodiment. Next, the second embodiment will be described.

  In the second embodiment, the magnetic dots are made of a Co—Cr—Pt alloy, and as a result, the magnetic disk manufacturing method becomes a manufacturing method corresponding to the formation of the magnetic film with this Co—Cr—Pt alloy. This is different from the first embodiment described above. Therefore, in the following description, attention is paid to differences from the first embodiment, and description of the same points is omitted.

  FIG. 9 is a flowchart showing the magnetic disk manufacturing method of the second embodiment.

  In FIG. 9, processes equivalent to those shown in FIG. 5 are given the same number of steps as in FIG. 5, and redundant description of these processes will be omitted below.

  In the magnetic disk manufacturing method of FIG. 9, first, sample preparation (step S201) and ion implantation into the sample (step S202) are executed as in the first embodiment described above. In the embodiment, the magnetic film in the sample is a magnetic film made of a Co—Cr—Pt alloy. In the present embodiment, the Pt composition ratio (sample composition ratio) in the sample magnetic film is obtained by the same process as the process of step S203 described later. In the process of step S201, a sample magnetic film is created with the calculated sample composition ratio. The details of how to obtain the composition ratio in the magnetic film of this sample will be described together with the description of the processing in step S203. In the present embodiment, the thickness of the sample magnetic film is 20 nm.

  The process of step S201 in the present embodiment also corresponds to an example of the first magnetic film forming process in the basic form described above, and the process of step S202 also corresponds to an example of the first ion implantation process in the basic form.

  For the sample having the magnetic film made of the Co—Cr—Pt alloy, the measurement of the saturation magnetization disappearance (step S103) and the calculation of the anisotropic magnetic field (step S104) are the same as in the first embodiment. Executed.

  Next, in the present embodiment, in the process of step S203 subsequent to step S104, the composition ratio of Pt (hereinafter referred to as the actual composition ratio) from which an actual anisotropic magnetic field is obtained is obtained.

  In the present embodiment, this composition ratio is obtained based on the following measurement data prepared in advance. That is, the measurement data is obtained by forming a plurality of magnetic films having different Pt composition ratios and measuring the anisotropic magnetic field in each magnetic film. This measurement data represents a dependency relationship in which the anisotropic magnetic field depends on the Pt composition ratio (hereinafter referred to as the Pt composition ratio dependency of the anisotropic magnetic field).

  In step S203, the composition ratio corresponding to the anisotropic magnetic field calculated in step S102 is obtained based on the dependency of the anisotropic magnetic field on the Pt composition ratio. Hereinafter, similarly to the description of the first embodiment described above, it is assumed that the saturation magnetization disappearance obtained in step S101 is 90% and the actual anisotropic magnetic field obtained in step S102 is 18 kOe. Continue.

  FIG. 10 is a graph showing an example of the dependence of the anisotropic magnetic field on the Pt composition ratio.

  FIG. 10 shows a graph G3 on which measurement data representing the dependence of the anisotropic magnetic field on the Pt composition ratio is plotted. The graph G3 includes a line L3 representing the dependence of the anisotropic magnetic field on the Pt composition ratio.

  This graph G3 also shows a line L5 representing a dependency relationship in which the saturation magnetization of the magnetic film before ion implantation depends on the Pt composition ratio (hereinafter referred to as the Pt composition ratio dependency of saturation magnetization). . This line L5 is used in step S204 described later in FIG.

  In addition, two lines L4 and L5 shown in the graph G3 represent measurement data obtained for a magnetic film made of a Co—Cr—Pt alloy and having a thickness of 20 nm.

  Hereinafter, the film thickness on which the measurement data is based is referred to as a default film thickness.

  From the line L4 representing the dependence on the anisotropic magnetic field in the graph G3 of FIG. 10, the actual composition ratio for obtaining the actual anisotropic magnetic field (18 kOe) is approximately 29 at percent.

  Furthermore, in the present embodiment, the sample composition ratio in the sample created in step S201 is obtained by the same process as the process in step S203. In this example, it is assumed that the sample anisotropic magnetic field is 14 kOe, as in the description of the first embodiment described above. Then, from the graph G2 of FIG. 7, the sample composition ratio corresponding to this sample anisotropic magnetic field is approximately 23 at percent.

  In step S201 described above, a sample having a magnetic film made of a Co—Cr—Pt alloy containing Pt in the sample composition ratio obtained by the same process as the process of step S203 is formed.

  Next, in the flowchart of FIG. 9, the actual saturation magnetization in the magnetic film corresponding to the measurement data of the graph G3 of FIG. 10 described above, in which the Pt composition ratio is the actual composition ratio, is calculated ( Step S204). Further, in the process of step S204, saturation magnetization (hereinafter referred to as sample saturation magnetization) in the magnetic film of the sample is also obtained.

  For the calculation of the two saturation magnetizations in step S204, the line L5 representing the dependency of the saturation magnetization on the Pt composition ratio in the graph G3 in FIG. 9 is used.

  From this line L5, a value of about 450 emu / cc is obtained as the actual saturation magnetization corresponding to the actual composition ratio (29 at percent) obtained in step S203. On the other hand, a value of about 500 emu / cc is obtained as the sample saturation magnetization corresponding to the above-described sample composition ratio (23 at percent).

  Once the two types of saturation magnetization are calculated in step S204, the actual film thickness of the magnetic film made of the Co—Cr—Pt alloy is calculated as follows based on the calculated saturation magnetization. (Step S205).

  In step S205, the actual film thickness is determined such that the product of the actual saturation magnetization and the actual film thickness is 90% or more of the product of the sample saturation magnetization and the default film thickness.

  In this example, the actual film thickness is 20 nm or more.

  This method of determining the film thickness is based on the following reason.

  As described above, for example, when it is assumed that the saturation magnetization of the magnetic material is small and a reproduction signal of a desired level cannot be obtained, by increasing the volume by slightly thickening the magnetic dots at the design stage, It becomes possible to realize a reproduction signal of a desired level. When the magnetic dot is a single-layer film made of a Co—Cr—Pt alloy as in the present embodiment, a reproduction signal having a desired level as described above can be realized by increasing the film thickness. . At this time, if the product of the saturation magnetization and the actual film thickness is 90% or more of the product of the saturation magnetization and the film thickness at the magnetic dot from which a reproduction signal of a desired level is obtained, the reproduction at the desired level is performed. The developer found that the signal was achieved.

  In the present embodiment, the level of the reproduction signal obtained by the magnetic dots when the interdot dot band is formed with a saturation magnetization disappearance of 100% is adopted as the target level. Here, the magnetic film of the above sample is formed with a composition ratio obtained on the assumption that the saturation magnetization disappearance is 100 percent. Therefore, in step S205 in FIG. 9, the actual film thickness so that the product of the actual saturation magnetization and the actual film thickness is 90% or more of the product of the sample saturation magnetization and the default film thickness. Is required.

  In the processing up to step S205 described above, the composition ratio of Pt necessary for realizing the actual anisotropic magnetic field calculated in step S105 and the film necessary for realizing a desired level of reproduction signal Thickness is obtained.

  Here, it can be seen from the shape of the line L4 shown in the graph G2 that a magnetic film made of a Co—Cr—Pt alloy cannot realize an anisotropic magnetic field exceeding about 18 kOe. Such an anisotropic magnetic field corresponds to a saturation magnetization disappearance lower than 90% from the graph G1 in FIG. That is, in the present embodiment, a desired magnetization reversal magnetic field can be realized only when the saturation magnetization disappearance obtained in step S103 of FIG. 9 is 90% or more. As a result, in this embodiment, when a saturation magnetization disappearance level lower than 90% is grasped, for example, a film forming condition in a sputtering apparatus is adjusted so that a saturation magnetization disappearance level of 90% or more is obtained. The Rukoto.

  Once the composition ratio of Pt and the film thickness of the magnetic film are obtained, the magnetic disk manufacturing process (step S206) using the composition ratio and the film thickness is then performed. This magnetic disk manufacturing process (step S206) is equivalent to the series of processes shown in FIG. 8 except that the magnetic film obtained in the film forming process is made of a Co—Cr—Pt alloy. Therefore, description of the magnetic disk manufacturing process (step S206) is omitted here.

  In this embodiment, as described above, the magnetic film made of Co—Cr—Pt alloy having the Pt composition ratio obtained in step S203 ensures the actual anisotropic magnetic field calculated in step S104. Can be realized.

  This means that the following application forms are preferable to the basic form described above.

  In this application mode, both the first magnetic film forming process and the second magnetic film forming process are processes for forming a magnetic film made of a Co—Cr—Pt-based alloy. In this application mode, the composition ratio for calculating the composition ratio of Pt required for realizing the anisotropic magnetic field calculated in the above-described anisotropic magnetic field calculation process with the magnetic film made of the Co—Cr—Pt-based alloy. It has a calculation process. Furthermore, in this application mode, the second magnetic film forming process forms a magnetic film with the Co—Cr—Pt based alloy containing Pt at the composition ratio calculated in the composition ratio calculating process as the magnetic film. It has become a process.

  According to this application mode, the desired anisotropy calculated in the anisotropic magnetic field calculation process can be obtained by a simple method of appropriately adjusting the composition ratio of Pt in the magnetic film made of the Co—Cr—Pt base alloy. A magnetic field can be realized.

  The process of step S203 in FIG. 9 corresponds to an example of a composition ratio calculation process in this applied form. The film forming process executed in the magnetic disk manufacturing process (step S206) in FIG. 9 corresponds to an example of a second magnetic film forming process in this applied embodiment.

  In the present embodiment, as described above, the level of the reproduction signal obtained from the actual magnetic disk can be adjusted to the target level by the film thickness obtained in step S205. This means that the following application forms are more suitable for the above application forms employing the magnetic film made of a Co—Cr—Pt base alloy.

  This application form has a film thickness calculation process. This film thickness calculation process is a process of calculating the film thickness of the magnetic film formed in the second magnetic film formation process. Then, the calculation is performed with respect to the product of the saturation magnetization and the film thickness in the magnetic film formed in the first magnetic film forming process, and the saturation in the magnetic film formed in the second magnetic film forming process. The product of magnetization and film thickness is executed so as to satisfy a predetermined degree of approximation. Further, in this application mode, the second magnetic film forming process is a process of forming a magnetic film made of a Co—Cr—Pt-based alloy with the film thickness calculated in the stacking number calculating process.

  According to this application mode, a reproduction signal of a desired level can be obtained by a simple operation of forming a magnetic film with a saturation magnetization and a film thickness that generates a desired leakage magnetic field in the first magnetic film formation process. A magnetic disk can be obtained.

  The process of step S205 in FIG. 9 corresponds to an example of a film thickness calculation process in this application mode. In addition, the product of the sample saturation magnetization and the default film thickness is an example of “the product of the saturation magnetization and the film thickness in the magnetic film formed in the first magnetic film formation process” in this application. It corresponds to. Furthermore, the product of the actual sample saturation magnetization and the actual film thickness is expressed as “the saturation magnetization and film thickness in the magnetic film formed in the second magnetic film forming process” described in this application. It corresponds to an example of “product”. In this embodiment, an approximation degree of 90% or more is adopted as an example of the “approximation degree” in this application form.

  As described above, the magnetic disk manufacturing process (step S206) is executed using the Pt composition ratio obtained in step S203 and the film thickness obtained in step S205. Thereby, in this magnetic disk manufacturing process (step S206), a bit patterned magnetic disk having a designed magnetization reversal magnetic field and obtaining a desired level of reproduction signal is manufactured regardless of the saturation magnetization disappearance. It will be.

  In the magnetic disk manufacturing method of the present embodiment shown in FIG. 9, this magnetic disk manufacturing process (step S206) is repeated until the number of magnetic disks reaches a prescribed mass production number (Yes determination in step S109).

  Also in the magnetic disk manufacturing method of the second embodiment described above, a magnetic disk in which the variation of the magnetization reversal magnetic field for each lot is suppressed is manufactured as in the magnetic disk manufacturing method of the first embodiment. Become. Also, HDDs mass-produced using these magnetic disks are those in which variations in the magnetization reversal magnetic field of the mounted magnetic disk are suppressed.

  In the above description, a bit patterned magnetic storage medium is illustrated as an example of the magnetic storage medium. However, the magnetic storage medium is not limited to the bit patterned type, and may be, for example, a discrete track type. good.

  In the above description, the Co—Cr—Pt alloy is exemplified as an example of the Co—Cr—Pt base alloy forming the magnetic film, but the Co—Cr—Pt base alloy is not limited thereto. The Co—Cr—Pt based alloy may be an alloy in which other elements are added to the Co—Cr—Pt alloy within a composition range that does not impair the magnetic properties of the Co—Cr—Pt alloy.

  In the above description, the use of a resist pattern as a preferred mask for forming magnetic dots is exemplified. On the other hand, in the ion implantation in the basic form described above, a process may be used in which ion implantation is performed by placing a stencil mask close to the medium surface so as not to contact the medium surface. According to this process, the steps of resist coating and resist removal can be omitted.

  In the above description, it is shown that the nanoimprint process is used as the best example of resist patterning. However, electron beam exposure may be used for patterning.

  Hereinafter, the following additional remarks are disclosed regarding various forms including the basic form described above.

(Appendix 1)
A first magnetic film forming process for forming a magnetic film;
A first ion implantation process for implanting ions into the magnetic film;
A disappearance measurement process for measuring the disappearance of saturation magnetization by ion implantation in the first ion implantation process in the magnetic film;
Magnetization reversal in the protection region when the saturation magnetization of the magnetic film disappears locally in other regions excluding the protection region set at a predetermined location with the disappearance measured in the disappearance measurement process An anisotropic magnetic field calculation process for calculating an anisotropic magnetic field of the magnetic film before the disappearance of saturation magnetization, assuming that the magnetic field is equal to a predetermined magnetization reversal magnetic field,
On the substrate, a magnetic film having an anisotropic magnetic field equivalent to the anisotropic magnetic field calculated in the anisotropic magnetic field calculating process is equivalent to the magnetic film forming conditions in the first magnetic film forming process. A second magnetic film forming process formed under the forming conditions;
The region corresponding to the other region with respect to the magnetic film formed in the second magnetic film formation process is locally ionized under an ion implantation condition equivalent to the ion implantation condition in the first ion implantation process. And a second ion implantation process for implanting the magnetic storage medium.

(Appendix 2)
Both the first magnetic film forming process and the second magnetic film forming process are processes of forming a magnetic film having an artificial lattice structure in which Co atomic layers and Pd atomic layers are alternately stacked,
Layer thickness ratio for calculating the layer thickness ratio of Co atomic layer to Pd atomic layer required for realizing the anisotropic magnetic field calculated in the anisotropic magnetic field calculation process with the magnetic film having the artificial lattice structure Has a calculation process,
In the second magnetic film forming process, the atomic layer of Co and the atomic layer of Pd are alternately stacked at the layer thickness ratio calculated in the layer thickness ratio calculating process to form the magnetic film having the artificial lattice structure. The method of manufacturing a magnetic storage medium according to appendix 1, wherein

(Appendix 3)
The saturation magnetization and the number of atomic layers in the magnetic film formed in the second magnetic film formation process with respect to the product of the saturation magnetization and the number of atomic layers in the magnetic film formed in the first magnetic film formation process. A stack number calculating step of calculating the number of atomic layers in the magnetic film formed in the second magnetic film forming process so that the product of
The second magnetic film forming process is a process of forming a magnetic film having the artificial lattice structure by stacking atomic layers having the number of atomic layers calculated in the stacking number calculating process. Magnetic storage medium manufacturing method.

(Appendix 4)
Both the first magnetic film forming process and the second magnetic film forming process are processes of forming a magnetic film made of a Co—Cr—Pt based alloy,
A composition ratio calculating step for calculating a composition ratio of Pt required for realizing the anisotropic magnetic field calculated in the anisotropic magnetic field calculating step with a magnetic film made of a Co-Cr-Pt-based alloy;
The second magnetic film forming process is a process of forming a magnetic film with a Co—Cr—Pt based alloy containing Pt at the composition ratio calculated in the composition ratio calculating process as the magnetic film. The method for manufacturing a magnetic storage medium according to appendix 1.

(Appendix 5)
The saturation magnetization and film thickness in the magnetic film formed in the second magnetic film formation process are compared with the product of the saturation magnetization and film thickness in the magnetic film formed in the first magnetic film formation process. A film thickness calculating process for calculating a film thickness in the magnetic film formed in the second magnetic film forming process so that the product satisfies a predetermined degree of approximation;
The magnetic material according to claim 4, wherein the second magnetic film forming process is a process of forming a magnetic film made of a Co-Cr-Pt-based alloy with a film thickness calculated in the stacking number calculating process. A storage medium manufacturing method.

(Appendix 6)
The second ion implantation process is a process in which ions are locally implanted between the plurality of locations by using a plurality of locations regularly arranged in the direction in which the magnetic film spreads as the protective region. 6. The method of manufacturing a magnetic storage medium according to any one of appendices 1 to 5, wherein:

(Appendix 7)
The magnetic storage medium according to any one of appendices 1 to 6, wherein the second ion implantation process is a process using one of oxygen ions and nitrogen ions as the ions. Production method.

(Appendix 8)
A mask forming step of forming a mask on the magnetic film that inhibits ion implantation into the protection region;
In the second ion implantation process, ions are applied from above the magnetic film on which the mask is formed, so that the ions are locally implanted into other regions except for the protection region protected by the mask. The method of manufacturing a magnetic storage medium according to any one of appendices 1 to 7, wherein

(Appendix 9)
The method of manufacturing a magnetic storage medium according to appendix 8, wherein the mask forming process is a process of forming the mask with a resist.

(Appendix 10)
The method of manufacturing a magnetic storage medium according to appendix 8 or 9, wherein the mask forming step is a step of forming the mask with a resist by a nanoimprint process.

(Appendix 11)
A substrate,
A first magnetic film forming process for forming a magnetic film, a first ion implantation process for implanting ions into the magnetic film, and saturation magnetization of the magnetic film by ion implantation in the first ion implantation process. The vanishing degree measuring process for measuring the vanishing degree, and the saturation magnetization of the magnetic film in the vanishing degree measured in the vanishing degree measuring process is locally in other areas except for the protective area set at a predetermined location. An anisotropic magnetic field calculation process for calculating the anisotropic magnetic field of the magnetic film before the disappearance of saturation magnetization on the premise that the magnetization reversal field in the protection region becomes equal to a predetermined magnetization reversal magnetic field when disappearing, On the substrate, a magnetic film having an anisotropic magnetic field equivalent to the anisotropic magnetic field calculated in the anisotropic magnetic field calculating process is equivalent to the magnetic film forming conditions in the first magnetic film forming process. Formation process of second magnetic film formed under formation conditions Has a magnetic film formed through a magnetic portion on which information is magnetically recorded,
Implantation formed through a local ion implantation process in which ion implantation is performed under an ion implantation condition equivalent to the ion implantation condition in the first ion implantation process into the magnetic film continuous with the magnetic film of the magnetic part A magnetic storage medium comprising a low magnetic part having a film and a saturation magnetization smaller than the saturation magnetization of the magnetic part.

(Appendix 12)
A plurality of the magnetic parts are regularly arranged on the substrate, each of which is a magnetic dot on which information is magnetically recorded,
The magnetic storage medium according to appendix 11, wherein the low magnetic part is an interdot separation band that is provided between the magnetic dots and inhibits magnetic coupling between the magnetic dots.

(Appendix 13)
A substrate, a first magnetic film forming process for forming a magnetic film, a first ion implantation process for performing ion implantation into the magnetic film, and ion implantation in the first ion implantation process in the magnetic film. With respect to other areas excluding the protection area where the saturation magnetization of the magnetic film is measured at the disappearance degree measured in the disappearance degree measurement process and the saturation magnetization of the magnetic film is set at a predetermined place. An anisotropic magnetic field calculation process for calculating the anisotropic magnetic field of the magnetic film before the disappearance of saturation magnetization on the premise that the magnetization reversal magnetic field in the protection region becomes equal to a predetermined magnetization reversal magnetic field when it disappears locally And a magnetic film having an anisotropic magnetic field equivalent to the anisotropic magnetic field calculated in the anisotropic magnetic field calculating process on the substrate, the formation conditions of the magnetic film in the first magnetic film forming process Second magnetic film formed under the same formation conditions as A magnetic part having a magnetic film formed through the formation process, and ions in the first ion implantation process into a magnetic part in which information is magnetically recorded and a magnetic film continuous with the magnetic film of the magnetic part A low magnetic part having an implanted film formed through a local ion implantation process in which ion implantation is performed under an ion implantation condition equivalent to the implantation condition, and having a saturation magnetization smaller than the saturation magnetization of the magnetic part Magnetic storage media
A magnetic head that magnetically records and / or reproduces information on a magnetic part in proximity to or in contact with the magnetic storage medium;
A head position control mechanism that moves the magnetic head relative to the surface of the magnetic storage medium and positions the magnetic head on a magnetic part that records and / or reproduces information by the magnetic head. An information storage device.

(Appendix 14)
A plurality of the magnetic parts are regularly arranged on the substrate, each of which is a magnetic dot on which information is magnetically recorded,
14. The information storage device according to appendix 13, wherein the low magnetic part is an interdot separation band that is provided between the magnetic dots and inhibits magnetic coupling between the magnetic dots.

It is a figure which shows the internal structure of the hard disk drive (HDD) which is specific embodiment of an information storage device. FIG. 2 is a perspective view schematically showing the structure of the magnetic disk shown in FIG. 1. It is a figure which shows the manufacturing method of the type which manufactures a bit pattern type magnetic storage medium by an etching and filling with a nonmagnetic material. It is explanatory drawing explaining an ion doping system. 3 is a flowchart illustrating a magnetic disk manufacturing method according to the first embodiment. It is a graph which shows the saturation magnetization disappearance dependence of the anisotropic magnetic field which the formula used by step S104 of FIG. 5 represents. 6 is a graph showing an example of measurement data used in step S105 of FIG. It is a figure which shows the detail of a magnetic disc manufacturing process (step S108). It is a flowchart which shows the magnetic disc manufacturing method of 2nd Embodiment. It is a graph which shows an example of Pt composition ratio dependence of an anisotropic magnetic field.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Hard disk device 10 Magnetic disk 10a Magnetic dot 10b Interstitial zone 10c Track 60 Substrate 61 Underlayer 62 Magnetic film 62a Co atomic layer 62b Pd atomic layer

Claims (5)

A first magnetic film forming process for forming a magnetic film;
A first ion implantation process for implanting ions into the magnetic film;
A disappearance measurement process for measuring the disappearance of saturation magnetization by ion implantation in the first ion implantation process in the magnetic film;
Magnetization reversal in the protection region when the saturation magnetization of the magnetic film disappears locally in other regions excluding the protection region set at a predetermined location with the disappearance measured in the disappearance measurement process An anisotropic magnetic field calculation process for calculating an anisotropic magnetic field of the magnetic film before the disappearance of saturation magnetization, assuming that the magnetic field is equal to a predetermined magnetization reversal magnetic field,
On a substrate, and a second magnetic layer formation process that form a magnetic film having an equivalent anisotropic magnetic field and the calculated anisotropic magnetic field in the anisotropic magnetic field calculating step,
Magnetic storage, characterized in that it comprises a second ion implantation process to perform locally ion-implantation for the region corresponding to the other region with respect to the second magnetic layer forming magnetic film formed in the process Medium production method. Both the first magnetic film forming process and the second magnetic film forming process are processes of forming a magnetic film having an artificial lattice structure in which Co atomic layers and Pd atomic layers are alternately stacked,
Layer thickness ratio for calculating the layer thickness ratio of Co atomic layer to Pd atomic layer required for realizing the anisotropic magnetic field calculated in the anisotropic magnetic field calculation process with the magnetic film having the artificial lattice structure Has a calculation process,
In the second magnetic film forming process, the atomic layer of Co and the atomic layer of Pd are alternately stacked at the layer thickness ratio calculated in the layer thickness ratio calculating process to form the magnetic film having the artificial lattice structure. The method of manufacturing a magnetic storage medium according to claim 1, wherein The saturation magnetization and the number of atomic layers in the magnetic film formed in the second magnetic film formation process with respect to the product of the saturation magnetization and the number of atomic layers in the magnetic film formed in the first magnetic film formation process. A stack number calculating step of calculating the number of atomic layers in the magnetic film formed in the second magnetic film forming process so that the product of
3. The second magnetic film forming process is a process of forming a magnetic film having the artificial lattice structure by stacking atomic layers having the number of atomic layers calculated in the stacking number calculating process. The magnetic storage medium manufacturing method as described. Both the first magnetic film forming process and the second magnetic film forming process are processes of forming a magnetic film made of a Co—Cr—Pt based alloy,
A composition ratio calculating step for calculating a composition ratio of Pt required for realizing the anisotropic magnetic field calculated in the anisotropic magnetic field calculating step with a magnetic film made of a Co-Cr-Pt-based alloy;
The second magnetic film forming process is a process of forming a magnetic film with a Co—Cr—Pt based alloy containing Pt at the composition ratio calculated in the composition ratio calculating process as the magnetic film. The method of manufacturing a magnetic storage medium according to claim 1. The saturation magnetization and film thickness in the magnetic film formed in the second magnetic film formation process are compared with the product of the saturation magnetization and film thickness in the magnetic film formed in the first magnetic film formation process. A film thickness calculating process for calculating a film thickness in the magnetic film formed in the second magnetic film forming process so that the product satisfies a predetermined degree of approximation;
The second magnetic film forming process is a process of forming a magnetic film made of a Co-Cr-Pt-based alloy with the film thickness calculated in the film thickness calculating process. Magnetic storage medium manufacturing method.

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