JP2006309841A - Magnetic pattern forming method, magnetic recording medium, magnetic recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic pattern forming method which is suitable for the magnetic recording medium compatible with high-density recording. <P>SOLUTION: Forming a magnetic layer 16 and an ion buffer layer 20 in this order on a base plate 10, ions are implanted to the magnetic layer 16 while interposing this ion buffer layer 20. Then, the magnetic property of the areas implanted with ions is reformed by heating the magnetic layer 16 implanted with ions. The magnetic pattern is formed by using this reforming. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming a magnetic pattern used for a magnetic recording medium or the like, and more particularly to a method for forming a magnetic pattern suitable for high density recording by reducing magnetic interference between recorded information.

  In recent years, with the improvement in performance of information devices, the amount of information handled by these devices has also increased. 2. Description of the Related Art In the field of magnetic recording media such as hard disk drives (hereinafter referred to as HDDs), technical development for the purpose of improving recording density has been actively conducted in order to cope with the amount of information required by information equipment.

  For example, a discrete track medium in which a magnetic thin film serving as a recording layer is separated and processed for each concentric track, and a patterned medium in which the magnetic thin film is separated in the recording bit direction as well as between the tracks have been proposed. Discrete track track media reduce the magnetic interference between tracks by ensuring concentric non-magnetic regions between tracks, and achieve a higher track density. Also, since the patterned medium is independent of the magnetic material that records one dot (bit), this magnetic material can be one magnetic domain (single magnetic domain), and one bit per several tens of magnetic particles. Compared with the current magnetic recording for recording, the thermal stability of magnetization can be dramatically improved. In addition, since the bit boundary becomes physically clear, signal noise can be reduced.

As a method for producing these discrete track media and patterned media, a concavo-convex shape according to the separation shape is formed on a nonmagnetic substrate, and a magnetic thin film is formed along the concavo-convex shape, or once formed. In general, a part of the magnetic thin film is removed by etching. In magnetic recording media prepared by these methods, the magnetic film for recording magnetization information is physically separated, so that magnetic interference between adjacent dots or tracks is reduced, and the quality of the reproduced signal is also improved. improves.
JP 2000-322710 A

  However, since the magnetic recording medium manufactured by these methods has irregularities formed on the magnetic thin film or nonmagnetic substrate serving as the recording layer, a floating type head that performs recording / reproduction while flying around 10 nanometers is used. In the conventional HDD, there is a problem that the air flow fluctuates due to the unevenness and the flying characteristics deteriorate.

  In order to reduce the unevenness on the surface, it is necessary to flatten the surface after filling the unevenness in the magnetic thin film with a nonmagnetic material. As a result, there is a problem that the manufacturing process becomes complicated, the productivity deteriorates, and the manufacturing cost increases. Further, since the distance between the flying head and the recording layer is increased due to the presence of the nonmagnetic material for filling, there is a contradiction that the recording density cannot be improved correspondingly.

  Further, according to the detailed examination of the present inventor, the conventional idea that the recording dots and the recording tracks are separated in the surface direction of the magnetic thin film (in the case of a disk type, radial direction and circumferential direction, etc.) Further, when the recording density was further improved, it was considered that there was a certain limit due to the limitation of the medium area.

  The present invention has been made in view of the above problems, and by using a technique for modifying the magnetic properties, it exhibits the same function as a discrete track medium or a patterned medium, and enables higher density recording. The purpose is to obtain a magnetic pattern.

  As a result of diligent research, the present inventor has focused on improving the magnetic characteristics of a specific region by efficiently performing ion implantation in a state where the ion buffer layer is stacked on the magnetic layer. That is, the above object is achieved by the following means.

  (1) A step of forming a magnetic layer and an ion buffer layer in this order on a substrate, a step of implanting ions into the magnetic layer with the ion buffer layer interposed, and a heat treatment of the magnetic layer And a step of modifying the magnetic characteristics of the ion implantation region.

  (2) The method for forming a magnetic pattern as described in (1) above, wherein the ion buffer layer comprises carbon.

  (3) The magnetic pattern forming method as described in (1) or (2) above, wherein the ion buffer layer comprises an organic resist.

  (4) The magnetic pattern forming method as described in (1), (2) or (3) above, wherein a stencil mask is disposed on the opposite side of the ion buffer layer to set the ion implantation region. .

  (5) The method of forming a magnetic pattern as described in any one of (1) to (4) above, including a step of removing the ion buffer layer after the ion implantation.

  (6) When the thickness of the ion buffer layer is T1 and the thickness of the magnetic layer is T2, T1 ≦ T2, wherein the magnetic property according to any one of (1) to (5) above Pattern forming method.

  (7) A magnetic recording medium comprising, as a recording layer, the magnetic layer produced by the magnetic pattern forming method according to any one of (1) to (6).

  (8) A magnetic recording medium comprising a substrate and a magnetic layer formed on the substrate, wherein the recording region in the recording region is compared with the ferromagnetic region on the surface opposite to the substrate in the recording region of the magnetic layer. A magnetic recording medium, wherein a ferromagnetic region on a substrate side surface is reduced.

  (9) The magnetic recording medium according to (7) or (8), a magnetic head that records information on the magnetic recording medium, and an arm that moves the magnetic head on the magnetic recording medium. Magnetic recording / reproducing apparatus characterized by the above.

  According to the present invention, it is possible to obtain a magnetic layer that exhibits functions similar to those of a discrete track medium and a patterned medium without requiring physical processing, and can realize high-density recording. In particular, by using an ion buffer layer, it is possible to control the ion implantation concentration in the thickness direction of the magnetic layer and concentrate the ferromagnetic region in a specific region. Further, since a separation effect can be obtained in the thickness direction of the magnetic layer, it is possible to cope with high density recording.

  Hereinafter, examples of embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a magnetic recording medium 1 according to the first embodiment of the present invention. This magnetic recording medium 1 includes a nonmagnetic substrate 10, a soft magnetic backing layer 12, a nonmagnetic intermediate layer 14, a magnetic layer 16 formed of a magnetic thin film, and a protective layer 18 that protects the surface of the magnetic layer 16. Are stacked in this order. The substrate 10 is made of aluminum or glass, and ensures the overall strength of the magnetic recording medium 1. The backing layer 12 has a function of efficiently drawing leakage magnetic flux generated from the single-pole head when performing perpendicular magnetic recording to the magnetic layer 16. Therefore, the backing layer 12 employs a soft magnetic material such as NiFe having a high saturation magnetic flux density, and is formed with a thickness of about 100 nanometers. The intermediate layer 14 is formed of a material such as MgO with a thickness of about 2 nanometers, and functions as a buffer layer for epitaxially forming the magnetic layer 16. The magnetic layer 16 is a thin film having a film thickness of about 5 nm to 20 nm, mainly composed of FePt, and is set to 10 nm here. Information is recorded and held in the magnetic layer 16 by a change in magnetism. The protective layer 18 is a diamond-like carbon (DLC) thin film or a silicon oxide thin film (SiO2), and has a film thickness of 1 to 5 nanometers or the like so as to ensure strong adhesion and high surface hardness. ing. The protective layer 18 prevents the magnetic layer 16 from being worn or corroded.

  The FePt alloy used for the magnetic layer 16 is an fcc-A1 type crystal structure and an irregular alloy immediately after film formation. However, by performing annealing treatment (heat treatment) at a high temperature, the LP type crystal structure has a high strength. It becomes magnetic. In order to examine these crystal structures, an X-ray diffraction apparatus may be used. According to this apparatus, the crystal structure of the magnetic layer can be analyzed by irradiating the magnetic layer with X-rays and utilizing the diffraction phenomenon caused by the constituent atoms.

As schematically shown in FIG. 2, the magnetic layer 16 is formed with a recording track 30 serving as a recording region and a guard region 32 serving as a region other than the recording track 30. The recording track 30 serving as a recording area is formed concentrically in the circumferential direction of the magnetic recording medium 1 and contains Fe and Pt as main components. In Fe _1−X Pt _X which is the ratio of Fe to Pt, X is It is set in the range of 0.35 or more and 0.65 or less. Further, the recording track 30 is set so that elements such as B and Ag are contained in the range of 1 atomic% to 20 atomic%. These elements B and Ag have a function of increasing the coercive force of the magnetic layer 16 by heat treatment, as will be described later.

On the other hand, the guard region 32 is mainly composed of Fe and Pt, and in Fe _1−X Pt _X , which is the ratio of Fe and Pt, X is set in a range of 0.35 or more and 0.65 or less. . Furthermore, the guard region 32 is set so as to contain elements such as Cr, Mo, Al, and Nb in the range of 1 atomic% to 10 atomic%. These elements such as Cr have a function of reducing the coercive force of the magnetic layer 16 by heat treatment, as will be described later. In order to examine the composition ratio of such elements, an energy dispersive X-ray analyzer may be used. According to this apparatus, the element contained in the magnetic layer is clarified by irradiating the magnetic layer with an electron beam and detecting the X-ray energy specific to the element to be emitted, and the intensity ratio of this energy. Thus, the composition ratio can be examined.

  In the recording track 30, the high coercive force region 30B on the substrate side surface is reduced as compared with the high coercive force region 30A on the counter substrate side surface. Accordingly, the cross-sectional shape of the recording track 30 is virtually a trapezoidal or kamaboko shape. This shape is realized by controlling the range of the ferromagnetic region of the magnetic layer 16 in the thickness direction by ion implantation described later.

Next, the basis for selecting elements to be injected into the recording track 30 and the guard region 32 and the basis for setting the element ratio in the magnetic layer 16 will be described with reference to the experimental results in FIGS. In the experiment, an ion buffer layer of carbon having a thickness of 5 nm was formed on Fe ₄₂ Pt _{58 having} a thickness of 20 nm, and ion implantation was performed.

The table of FIG. 3 shows the coercive force after heat-treating a sample in which B ions are implanted with Fe ₄₂ Pt ₅₈ set at an implantation voltage of 6 keV. It can be seen that the coercive force after the heat treatment is higher than the implantation of the B element. For example, the coercive force after the heat treatment when the injection amount is 20 atomic% is about twice that when no injection is performed.

The table in FIG. 4 shows the coercive force after heat-treating a sample in which Ag ions are implanted with Fe ₄₂ Pt ₅₈ set at an implantation voltage of 45 keV. By injecting 2.5 atomic% of the Ag element, a coercive force approximately twice that in the case of not injecting is obtained.

The table of FIG. 5 shows the coercivity after heat treatment at 600 ° C. of a sample in which Cr ions are implanted with Fe ₄₂ Pt ₅₈ set at an implantation voltage of 21 keV. It can be seen that the coercive force after the heat treatment is lowered by the implantation of Cr element. For example, the coercive force after the heat treatment when the injection amount is 10 atomic% is about 1/10 that when the injection amount is not injected.

The table of FIG. 6 shows the coercive force after heat-treating a sample in which Mo ions are implanted with Fe ₄₂ Pt ₅₈ set at an implantation voltage of ₄₂ keV. It can be seen that the coercive force after the heat treatment is lowered by the implantation of the Mo element. For example, the coercive force after the heat treatment when the injection amount is 10 atomic% is about 1/10 that when the injection amount is not injected.

The table of FIG. 7 shows the coercive force after heat-treating a sample in which Al ions are implanted with Fe ₄₂ Pt ₅₈ set at an implantation voltage of 12 keV. It can be seen that the coercive force after the heat treatment is lowered by the implantation of the Al element. For example, the coercive force after the heat treatment when the implantation amount is 20 atomic% is about 1/10 that when the implantation amount is not implanted.

The table of FIG. 8 shows the coercivity after heat treatment at 600 ° C. of a sample in which Nb ions are implanted with Fe ₄₂ Pt ₅₈ set at an implantation voltage of 39 keV. It can be seen that the coercive force after the heat treatment is lowered by the implantation of the Al element. For example, the coercive force after the heat treatment when the injection amount is 10 atomic% is about 1/10 that when the injection amount is not injected.

  For the purpose of the magnetic layer 16, it is desirable that the recording track 30, which is a recording area, is set to a high coercivity, and the guard area 32 is set to a low coercivity. Therefore, an element whose coercive force is increased by the subsequent heat treatment, such as B ions and Ag ions shown in FIGS. 3 and 4, is implanted into the recording track 30 side. On the other hand, Cr ions, Mo ions, Al ions, Nb ions, etc. shown in FIGS. 5, 6, 7 and 8 are implanted into the guard region 32, and the coercive force is lowered by the subsequent heat treatment. To do. As a result, the difference in coercive force between the recording track 30 and the guard region 32 is increased, and a state suitable for high-density recording can be configured. In this embodiment, ion implantation is performed on both the recording track 30 and the guard region 32. However, the ion implantation may be performed on one of the recording track 30 and the guard region 32.

  Next, the manufacturing process of the recording medium 1 will be described. In addition, since the film forming process itself of each layer is the same as the conventional one, the description here is omitted.

First, when the magnetic layer 16 is formed, the FePt content ratio is set to Fe: Pt = 42: 58 (Fe ₄₂ Pt ₅₈ ). After the formation of the magnetic layer 16 is completed, an ion buffer layer 20 is further formed on the surface of the magnetic layer 16 (see FIG. 10). The material of the ion buffer layer 20 is carbon or an organic resist such as polymethyl methacrylate (PMMA). When the film thickness of the magnetic layer 16 is T2, the film thickness T1 of the ion buffer layer 20 is 0.1. It sets so that it may become xT2 <T1 <2 * T2. The reason for this is that if the film thickness T1 is 0.1 × T2 or less, it becomes difficult to function as the ion buffer layer 20 in the first place. If it is 2 × T2 or more, 30% or more of the implanted ions are ions. This is because it stops at the buffer layer 20 and the ion implantation efficiency for the magnetic layer 16 is extremely reduced. In this embodiment, since the thickness of the magnetic layer 16 is 10 nanometers, the thickness of the ion buffer layer 20 is preferably set within the range of 1 nanometer to 20 nanometers. It is set to nanometer. The material is carbon.

  In this state, as shown in FIG. 9, in order to implant other elements into the magnetic layer 16, a stencil mask 50 is disposed on the recording surface side of the recording medium 1, and this stencil mask 50 is formed by an ion implantation apparatus 60. B ions are implanted into the magnetic layer 16 via. The ion implantation apparatus 60 includes an ion source 62 that generates ions, an extraction power source 64 that extracts B ions from the ion source 62, a beam line 66 in which ions move as an ion beam, and necessary ions (here, B). An analysis magnet 68 for selecting ions), an acceleration tube 70 for applying energy necessary for the ion beam, a vacuum chamber 72 for storing the recording medium 1 into which ions are implanted, and the like.

  FIG. 10 shows an enlarged view of the state of the stencil mask 50 and the recording medium 1 when ions are implanted. A thin film of tantalum or the like is used as the material of the stencil mask 50, and a recording area pattern 52 that coincides with the overall arrangement of the recording track 30 is formed by subjecting this thin film to (electron beam) lithography. Accordingly, by implanting ions into the upper surface of the recording medium 1 with the stencil mask 50 interposed, the B element is implanted into the implantation region that coincides with the recording region pattern 52. Since the B ion beam emitted from the ion implantation apparatus 60 is diffused after passing through the stencil mask 50 as shown by the arrows in the drawing, the recording area pattern 52 is actually assumed by assuming the diffusion amount in advance. The recording track 30 is formed to be thinner than the recording track 30.

  FIG. 11 schematically shows the distribution state of the B element in the depth direction when the B element is ion-implanted into the magnetic layer 16 through the ion buffer layer 20. The B ions contained in the ion beam lose their energy and stop while repeatedly colliding with the elements contained in the ion buffer layer 20 and the magnetic layer 16. Therefore, B ions hardly stop on the surface of the ion buffer layer 20 on which the ion beam first collides. Most of the B ions are adjusted so as to stop after losing energy at a depth of about 10 nanometers, and are distributed with a certain extent before and after that. Therefore, the presence of the 10 nanometer ion buffer layer 20 makes it possible to bring the peak position of the B ion implantation concentration to the surface of the magnetic layer 16 opposite to the substrate.

  After the completion of the B ion implantation, a second stencil mask (not shown) having an opening formed on the guard region 32 side is rearranged, and Cr ions are implanted on the guard region 32 side. Also in this case, as in the case of B ion implantation, since the ion buffer layer 20 exists, Cr ions can be actively implanted in a state where the content of the surface on the side opposite to the substrate in the magnetic layer 16 is maximized. it can. As a result, the magnetic layer 16 containing B ions in the recording track 30 and Cr ions in the guard region 32 is formed.

  By the way, when the magnetic layer 16 is considered alone, a large amount of B ions and Cr ions are implanted into the surface on the side opposite to the substrate, but the implantation concentration decreases as it proceeds in the depth direction. Therefore, especially the ferromagnetic boundary on the surface of the magnetic layer 16 becomes clear, and the reproduction noise of recorded information can be reduced. If the ion implantation voltage is reduced, the energy of the ion beam is reduced. Therefore, it is possible to stop B ions and Cr ions near the surface of the magnetic layer 16 without using the ion buffer layer 20. However, it is still very difficult to stop ions directly on the surface of the magnetic layer 16, and in this case, the amount of ion implantation per unit time is reduced, so that the target number of ions can be implanted. take time. Therefore, by using the ion buffer layer 20 as in the present embodiment, ions are effectively implanted into the surface of the magnetic layer 16 using a high-power ion beam. As already described, the concentrated ion implantation on the surface side of the magnetic layer 16 leads to a reduction in the influence on the backing layer 12 on the back side.

  FIG. 12 schematically shows, as an example, how B ions that have passed through the stencil mask 50 spread in the width direction of the recording track 30. Clonal interactions occur between the ion beams and try to repel each other. Accordingly, B ions are implanted into the ion buffer layer 20 and the magnetic layer 16 so as to wrap around the back side of the stencil mask 50. As a result, the implantation region becomes larger than the recording region pattern 52 formed on the stencil mask 50, and therefore it is necessary to make the opening width narrower than the recording track 30 actually formed on the magnetic layer 16. It is. More specifically, the spreading amount in the width direction increases with respect to the film thickness T1 of the magnetic layer 16 from the time when the film thickness T2 of the ion buffer layer 20 becomes larger than T1, and thus the ion buffer. The thickness T2 of the layer 20 is desirably set to be equal to or less than the thickness T1 of the magnetic layer 16. Here, the thickness (10 nanometers) of the magnetic layer 16 is matched. In order to make the boundary between the recording track 30 and the guard region 32 clear, it is also desirable to keep the stencil mask 50 in close contact with the recording medium 1 as much as possible.

  When the implantation of B ions and Cr ions is completed, the magnetic characteristics of the recording track 30 and the guard region 32 are made different by heating at 600 ° C. for about 1 hour using a rapid thermal annealing (RTA) apparatus (not shown). Specifically, the coercive force on the recording track 30 side is increased, and the coercive force on the guard region 32 side is decreased. Thereafter, the ion buffer layer 20 is removed by etching or ashing, and a protective layer 18 made of DLC is formed on the magnetic layer 16 to complete the recording medium 1 as shown in FIGS. To do.

  Next, a recording / reproducing apparatus 100 using the recording medium 1 will be described with reference to FIG. The recording / reproducing apparatus 100 includes a spindle 102, a magnetic head 104, an arm 106, an actuator 108, a housing 110, and the like. The spindle 102 holds a plurality of recording media 1 in a coaxial state, and is rotationally driven at 3000 rpm to 10000 rpm by a spindle motor (not shown). The magnetic head 104 is arranged corresponding to each of the plurality of recording media 1, writes information to the recording medium 1, and reads recorded signals. In particular, here, the magnetic head 104 is a single pole type head, and by using the backing layer 12, the magnetic field lines pass perpendicularly to the surface direction of the magnetic layer 16, and perpendicular recording is possible. I have to. The magnetic head 104 is held on the tip side of the arm 106. The arm 106 swings itself so that the magnetic head 104 is moved to a specific recording bit of the recording medium 1 to read and write signals. The actuator 108 controls the arm 106 with extremely high accuracy.

  According to the recording medium 1 of the first embodiment, since the guard region 32 is formed between the adjacent recording tracks 30, magnetic interference between the recording tracks 30 can be reduced. Further, unlike the case where the recording medium 1 is physically processed and separated by etching or the like, the separation effect is obtained by property change by ion implantation, so that the manufacturing process becomes simple and the productivity can be improved. it can.

  Furthermore, in the first embodiment, it is possible to draw a firm ferromagnetic pattern on the side opposite to the substrate (front side) of the magnetic layer 16 using the ion buffer layer 20, so that the reproduction noise of the recording signal is reduced. Is done. In addition, since a high-power ion beam can be used, a backscatter phenomenon in which ions repel on the surface of the ion buffer layer 20 can be avoided, and ion implantation efficiency can be improved.

  The presence of the ion buffer layer 20 covering the magnetic layer 16 also contributes to preventing a sputtering phenomenon in which other atoms in the magnetic layer 16 are released from the surface of the magnetic layer 16 due to the collision of implanted ions. . Similarly, the presence of the ion buffer layer 20 can prevent scratches from being formed on the surface of the magnetic layer 16 during ion implantation, and can also prevent particles from adhering to the magnetic layer 16. As a result, the quality of the magnetic layer 16 can be stabilized.

  Furthermore, in the first embodiment, by containing B ions on the recording track 30 side, the coercive force is increased as compared with the non-contained state, and Cr ions are implanted into the guard region 32 so as to maintain the non-contained state. Since the magnetic force is reduced, a magnetic pattern having a large coercive force difference can be easily formed. Further, since the track format can be drawn on the magnetic layer 16 using the stencil mask 50, the track format can be flexibly changed. Further, since the recording track 32 is formed by ion implantation, the substrate 10 and the magnetic layer 16 can be flattened. As a result, it is possible to prevent the recording head 104 from colliding with the protrusion on the surface of the recording medium 1, and in the case of the flying head, the flying characteristics can be stabilized.

  When magnetic recording is performed using the recording / reproducing apparatus 100, writing for the purpose of refreshing the guard area 32 may be performed periodically. That is, even when the guard area 32 is affected by some magnetic influence by the magnetic recording process on the recording track 30 side, the effect of separating the adjacent recording tracks 30 by the active refresh operation including the guard area 32 is achieved. Can be maintained. At that time, since the magnetic recording for refreshing can be executed with a very weak magnetic flux because the guard region 32 has a low coercive force, it is possible to prevent the recording state of the recording track 30 from being affected. Furthermore, since the recording / reproducing apparatus 100 uses the present recording medium 1 and the surface of the medium is smooth, the existing apparatus configuration can be employed as it is. As a result, the recording / reproducing apparatus 100 with a low recording cost and high recording density can be obtained.

  Next, a method for forming a magnetic pattern in the magnetic recording medium 200 according to the second embodiment of the present invention will be described with reference to FIG. In addition, about the part and member which are the same as or similar to the magnetic recording medium 1 of 1st Embodiment, the detailed description is abbreviate | omitted by making the code | symbol shown with the recording medium 1 and the last two digits correspond.

  Here, a protective layer 218 formed by DLC is formed in advance, and ion implantation is performed thereon. That is, the protective layer 218 also serves as an ion buffer layer. In the stencil mask 250, recording dot openings are formed as the recording area pattern 252. In this embodiment, B ions are implanted into the magnetic layer 216 through the stencil mask 250, and then heat treatment is performed, so that the B ion implanted region becomes the recording dots 230 with high coercivity. This is because, as already shown in FIG. 3, the magnetic layer 216 corresponding to the implantation region has a high coercive force by performing the heat treatment after ion implantation of B. On the other hand, since B ions are not implanted into the guard region 232 around the recording dot 230, the guard region 232 after the heat treatment has a lower coercive force than the recording dot 230.

  Furthermore, in the second embodiment, since the protective layer 218 is used as the ion buffer layer, the step of removing the ion buffer layer is omitted, and the productivity can be improved. Further, the protective layer 218 can concentrate B ions on the surface of the magnetic layer 216 on the side opposite to the substrate, so that the boundaries of the recording dots 230 to be formed can be made clear, and signal noise can be reduced. be able to.

  In the second embodiment, B ions are implanted to obtain a high coercive force. However, Cr ions are implanted into the guard (separation) region side to reduce the coercive force on the guard region side, thereby recording. You may make it ensure the coercive force difference with the dot 230. FIG. Of course, as in the first embodiment, an element that can be made to have a high coercivity by heat treatment is implanted into the recording dot 230 side, while an element that can be made to have a low coercivity by heat treatment is implanted into the guard region side. It is also possible to form a pattern.

  Next, a method for forming a magnetic pattern in the magnetic recording medium 300 according to the third embodiment of the present invention will be described with reference to FIGS. In addition, regarding the magnetic recording medium 300 shown in FIG. 15, the same or similar parts / members as those of the magnetic recording medium 1 of the first embodiment are made to match the last two digits with the reference numerals shown in the recording medium 1. Therefore, detailed description is omitted.

  In this magnetic recording medium 300, the content ratio of Fe and Pt is changed by ion implantation into the magnetic layer 316 containing FePt as a main component. That is, the ions to be implanted are Fe ions or Pt ions that are the main component of the magnetic layer 316.

  In the magnetic layer 316, a recording track 330 and a guard region 332 are formed. The Fe content on the recording track 330 side is at least partially in the range of 38 atomic% to 60 atomic%, specifically, It is set to about 50 atomic%. On the other hand, the guard region 332 is set so that the Fe content is in the range of 35 atomic% or less and 20 atomic% or more, specifically about 29 atomic%.

  FIG. 16 compares the crystal structure and magnetism according to the atomic content before and after heat treatment. For example, when Fe: Pt is 75:25 or 50:50, it is an fcc-A1 type (cubic Cu3Au type) crystal structure disordered alloy before the heat treatment and has soft magnetism. It changes into a regular alloy of L12 type (cubic Cu3Au type) or fct-L10 type (tetragonal CuAuI type), and becomes a ferromagnetic material with high coercive force.

  On the other hand, when Fe: Pt is 25:75, it becomes an fcc-L12 type (cubic Cu3Au type) ordered alloy after heat treatment and has paramagnetism. That is, when Fe: Pt is 25:75, even if heat treatment is performed, the state is extremely unsuitable for magnetic recording. Thus, by varying the content ratio, it is possible to vary the magnetic characteristics even with the same combination of atoms.

  FIG. 17A shows how the coercive force fluctuates by changing the heat treatment temperature of the magnetic layer 316 and the Fe content ratio. For example, when heat treatment at 600 ° C. is performed, it is found that when Fe is set to less than 38 atomic% (approximately 35 atomic% or less, and definitely 34 atomic% or less), paramagnetism is obtained. On the other hand, it can be seen that if it is 38 atomic% or more, it becomes ferromagnetic.

  Similarly, when the Fe content is approximately 35 atomic% or less, the coercive force is 1 (kOe) or less, and when it is set to 38 atomic% or more, the coercive force is 4 (kOe) or more. Therefore, the coercive force of the region with a low Fe content is less than or equal to one-fourth that of the region with a high Fe content. That is, by setting one to 35 atomic percent or less and the other to 38 atomic percent or more, a coercive force difference of 3 (kOe) or more can be secured between the low coercive force side region and the high coercive force side region. Thus, the magnetic interference between the recording tracks 330 can be greatly reduced. The boundary between paramagnetism and ferromagnetism is about 35 atomic%. In order to investigate the coercive force, a vibrating sample magnetometer may be used. Thereby, the static coercive force in the magnetic layer can be clarified.

  In addition, when the heat treatment temperature is 400 ° C., if the Fe content is 44 atomic% or more, it becomes ferromagnetic. On the other hand, it can be seen that when the Fe content is 38 atomic% or less, the coercive force does not increase and becomes paramagnetic. In other words, the boundary between paramagnetism and ferromagnetism is about 40 atomic%.

  FIG. 17B shows how the amount of saturation magnetization varies by changing the heat treatment temperature and the Fe content ratio of the magnetic layer 316. For example, when heat treatment at 600 ° C. is performed, the saturation magnetization can be set to 400 G or less by setting the Fe content to 34 atomic% or less, while the saturation magnetization is set to 38 atomic% or more when the Fe content is 38 atomic% or more. The amount exceeds 400G. In other words, considering the saturation magnetization amount of 400 G as a reference, about 35 atomic% is the boundary.

  It can also be seen that when the heat treatment temperature is 400 ° C., the saturation magnetization is extremely reduced when the Fe content is 29 atomic% or less. On the other hand, when Fe is 34% or more, it can be seen that the saturation magnetization does not decrease and greatly exceeds 400G. That is, when considering the saturation magnetization amount of 400 G as a reference, it is considered that the boundary is about 32 atomic%.

  In any case, it is not realistic that the Fe content is less than 20 atomic%. This is because, as shown in FIG. 17 (A), in order to make it ferromagnetic, it is necessary to increase the content from less than 20% to at least about 15 atomic% to about 35 atomic%. This is because the Fe ion implantation operation must be performed over time. Moreover, it is not realistic to make the Fe content ratio larger than 60 atomic%. If it is set larger, an L12 type ordered alloy with Fe: Pt of 75:25 will be formed, and the magnetic anisotropy will be lower than that of the L10 type ordered alloy.

  The following (1) and (2) become clear when the above analysis is arranged.

  (1) When heat treatment is performed at about 400 ° C., the Fe content of the recording track 330 is set to at least 40 atomic% or more, preferably 44 atomic% or more, and a high coercive force of 4 (kOe) or more and a high of 400 G or more. The saturation magnetization is set. On the other hand, the guard region 332 is set to have a low coercive force of 1 (kOe) or less and a low saturation magnetization of less than 400 G by setting the Fe content to 30 atomic% or less.

  (2) When heat treatment is possible at 600 ° C. or higher, the Fe content of the recording track 330 is about 35 atomic% or higher, preferably 38 atomic% or higher, high coercive force of 4 (kOe) or higher, and 400 G or higher. Ensure high saturation magnetization. On the other hand, the guard region 332 has a low coercive force of 1 (kOe) or less and a low saturation magnetization of less than 400 G by setting the Fe content to less than about 35 atomic%, preferably 34 atomic% or less. Like that. In the case of heat treatment at 600 ° C., a sufficient magnetic difference is obtained with a difference in content ratio between the two, so that the ion implantation time can be shortened and the productivity is improved. By these (1) and (2), the coercive force of the guard region 332 is ¼ or less of the coercive force of the recording track 330, and magnetic interference between the recording tracks 330 can be reduced.

  In the third embodiment, on the basis of the above setting basis, Fe is set to about 50 atomic% in the recording track 330 and about 29 atomic% in the guard area 332. Therefore, if annealing is performed at 400 ° C. or higher, a state where the recording track 330 side is ferromagnetic and the guard region 332 is paramagnetic can be easily created.

  Next, returning to FIG. 15, the manufacturing process of the recording medium 300 will be described. In addition, specific description is abbreviate | omitted about the part similar or similar to the manufacturing process of 1st Embodiment, and it demonstrates centering on a different part.

  The content ratio of FePt when forming the magnetic layer 316 is set to the content ratio obtained on the guard region 332 side, that is, Fe: Pt = 29: 71. After the film formation is completed, an ion buffer layer 320 is further formed on the surface of the magnetic layer 316. The material of the ion buffer layer 320 is carbon or the like. When the film thickness of the magnetic layer 316 is T2, the film thickness T1 of the ion buffer layer 320 is 0.1 × T2 <T1 <2 × T2. Set to.

  In this state, in order to change the content ratio of FePt in the magnetic layer 316, a stencil mask 350 is disposed on the recording surface side of the recording medium 300, and the stencil mask 350 is interposed by an ion implantation apparatus (not shown). Fe ions are implanted into the magnetic layer 316.

  The stencil mask 350 is formed with a recording area pattern 352 that matches the entire arrangement of the recording tracks 330. Therefore, by implanting ions with the stencil mask 350 interposed on the upper surface of the recording medium 300, Fe is implanted into a region that coincides with the recording region pattern 352.

  Due to the presence of the ion buffer layer 320, a large amount of Fe ions are implanted into the surface of the magnetic layer 316 on the side opposite to the substrate, and the implantation concentration decreases as the depth advances. Therefore, the ferromagnetic boundary on the surface of the magnetic layer 316 becomes clear, and the reproduction noise of recorded information can be reduced. Concentration of Fe ions on the surface side of the magnetic layer 316 leads to a reduction in the influence on the backing layer 312 on the back side.

  Although the content ratio of the guard region 332 covered with the stencil mask 350 is not different from that at the time of film formation, on the recording track 330 side, Fe is actively ion-implanted to improve the Fe content ratio, and Fe: Control is performed so that Pt falls within the range of 38:72 to 60:40. Specifically, in this embodiment, it is set so that Fe: Pt is 50:50. When ion implantation is completed, the magnetic characteristics of the recording track 330 and the guard region 332 are made different by heating at 600 ° C. for about 1 hour using a rapid thermal annealing (RTA) apparatus. Thereafter, the ion buffer layer 320 is removed by etching or ashing, and a protective layer 318 made of DLC is formed on the magnetic layer 316 to complete the recording medium 300.

  According to the recording medium 300 of the third embodiment, the magnetic layer 316 contains atoms that can form an L10 crystal structure (here, FePt) and does not become ferromagnetic even if heat treatment is performed. While film formation is performed at a ratio, ion implantation is limited to a specific region to make it ferromagnetic, so that a magnetic pattern suitable for a track format can be easily formed.

  Further, as in the present recording medium 300, by setting the Fe content in the guard area 332 to 35 atomic% or less, the coercive force of the guard area 332 can be set to 1 (kOe) or less, so that the recording track A large difference in coercive force can be ensured with 330. Similarly, since the saturation magnetization amount of the guard region 332 is set to 400 G or less, a large saturation magnetization amount difference with the recording track 330 can be secured. Moreover, it is a rational manufacturing method in which a coercive force difference and a saturation magnetization amount difference can be secured simultaneously by a single ion implantation process.

  In the third embodiment, only the case where ions are implanted into the recording area is shown. However, for example, the magnetic characteristics of the guard area may be improved by implanting Pt into the guard area. Absent. For example, it is possible to form a magnetic layer from a material that can be made ferromagnetic by heat treatment, and to make it partially paramagnetic by ion implantation into the guard region. These selections may be appropriately determined in consideration of whether or not the atom is suitable for ion implantation.

  As described above, in the embodiment of the present invention, only the case of Fe—Pt is shown as the atomic combination of the magnetic layer. However, the present invention is not limited to this, and other atoms may be adopted. In particular, an atomic combination (for example, Fe—Pt, Fe—Pd, Co—Pt) capable of constituting an ordered alloy having an L10 crystal structure is preferable. This is because the ferromagnetic pattern can be freely formed by adjusting the content ratio and the content of the third element.

  Further, in the present embodiment, the method for forming a magnetic pattern is shown only when it is used for a magnetic layer in a disk type magnetic recording medium. However, the present invention is not limited thereto, and may be used for other magnetic recording media. Of course it is possible. There are various ion implantation techniques, and the present invention is not limited to the use of the ion implantation apparatus shown in the present embodiment.

  The magnetic pattern forming method and the like can be used in various fields such as a magnetic recording card, a magnetic recording tape, and various display media using a magnetic layer. Further, it is possible to use a medium on which this magnetic pattern is formed in magneto-optical recording such as MO (Magnet Optical) or heat-assisted recording using both magnetism and heat.

Sectional drawing which shows the lamination | stacking state of the magnetic-recording medium based on 1st Embodiment of this invention The perspective view which shows the state of the magnetic layer in the cross section of the same magnetic recording medium Table showing changes in magnetic properties when B ions are implanted into the magnetic recording medium Table showing changes in magnetic properties when Ag ions are implanted into the magnetic recording medium Table showing changes in magnetic properties when Cr ions are implanted into the magnetic recording medium Table showing changes in magnetic properties when Mo-on is injected into the magnetic recording medium Table showing changes in magnetic properties when Al ions are implanted into the magnetic recording medium Table showing changes in magnetic properties when Nb ions are implanted into the magnetic recording medium Overall view schematically showing the configuration of an apparatus for ion implantation into the magnetic recording medium The perspective view which expands and shows the stencil mask at the time of ion implantation with respect to the magnetic recording medium A graph schematically showing the distribution of ion implantation depth in the magnetic recording medium A graph schematically showing the diffusion state in the width direction during ion implantation of the magnetic recording medium Partial sectional view showing the configuration of a recording / reproducing apparatus using the magnetic recording medium The perspective view which shows the ion implantation process of the magnetic-recording medium based on 2nd Embodiment of this invention. The perspective view which shows the ion implantation process of the magnetic-recording medium based on 3rd Embodiment of this invention. Table showing the magnetic state according to the content ratio of FePt used in the magnetic recording medium before and after heat treatment Graph showing changes in coercive force and saturation magnetization according to the content ratio of FePt used in the magnetic recording medium and the heat treatment temperature

Explanation of symbols

1, 200, 300 Magnetic recording medium 10, 210, 310 Substrate 12, 212, 312 Backing layer 14, 214, 314 Intermediate layer 16, 216, 316 Magnetic layer 18, 218, 318 Protective layer 30, 330 Recording track 32, 232 332 Guard area 50, 250, 350 Stencil mask 100 Recording / reproducing apparatus 102 Spindle 104 Recording head 106 Arm 108 Actuator 230 Recording bit

Claims (9)

Forming a magnetic layer and an ion buffer layer in this order on the substrate;
Implanting ions into the magnetic layer with the ion buffer layer interposed;
Modifying the magnetic properties of the ion implantation region by heat-treating the magnetic layer; and
A method for forming a magnetic pattern, comprising:   The magnetic pattern forming method according to claim 1, wherein the ion buffer layer includes carbon.   3. The magnetic pattern forming method according to claim 1, wherein the ion buffer layer includes an organic resist.   4. The method of forming a magnetic pattern according to claim 1, wherein a stencil mask is disposed on the side of the ion buffer layer opposite to the substrate to set the ion implantation region.   The magnetic pattern forming method according to claim 1, further comprising a step of removing the ion buffer layer after the ion implantation.   6. The magnetic pattern forming method according to claim 1, wherein T1 ≦ T2, where T1 is a thickness of the ion buffer layer and T2 is a thickness of the magnetic layer.   A magnetic recording medium comprising the magnetic layer produced by the magnetic pattern forming method according to claim 1 as a recording layer. A magnetic recording medium comprising a substrate and a magnetic layer formed on the substrate,
A magnetic recording medium, wherein the ferromagnetic region on the substrate side surface in the recording region is reduced as compared with the ferromagnetic region on the non-substrate side surface in the recording region of the magnetic layer. A magnetic recording medium according to claim 7 or 8,
A magnetic head for recording information on the magnetic recording medium;
An arm for moving the magnetic head on the magnetic recording medium;
A magnetic recording / reproducing apparatus comprising:

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