JP2011123928A - Method for manufacturing patterned medium type magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a patterned medium type magnetic recording medium having a smooth surface and excellent signal characteristics and reliability without reducing corrosion resistance, even when tape burnishing is performed after protective layer formation and lubricant application on a magnetic recording layer having a discrete track formed thereon. <P>SOLUTION: In the method for manufacturing the patterned medium type magnetic recording medium, a step P11 for irradiating the surface of the magnetic recording layer 14 layered on a non-magnetic substrate across a metal underlayer and formed by being divided by a recessed discrete track with UV of a vacuum UV region to control charge voltage of a substrate surface within 50 V, a step P12 for embedding a non-magnetic body in the recessed part of the magnetic recording layer, a surface flattening step P14, protective layer forming steps P17, P18 and P19 and a lubricant applying step are performed in this order, and then a tape burnishing step is performed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a patterned media type magnetic recording medium used in a storage device used in information equipment such as a computer.

  The demand for higher recording density for storage devices used in information devices such as computers is increasing year by year. Also in a magnetic recording apparatus which is one of storage apparatuses, correspondence with a high recording density is being advanced. Measures such as changing the constituent materials, making the recording layer finer, and changing the magnetic recording method have been taken, but the improvement in recording density is reaching its limit. In order to further improve the recording density, a patterned media type magnetic recording medium such as a discrete track type or a bit pattern type in which the magnetic recording layer is processed into a fine uneven pattern is required. As a method of manufacturing such a patterned media type magnetic recording medium, for example, as shown in FIG. 1, a soft magnetic layer 11, a seed layer 12, an intermediate layer (Ru) are formed on a nonmagnetic substrate 10 by sputtering or the like. A metal underlayer such as (alignment layer) 13 and a magnetic recording layer 14 are formed. After that, for example, a hard mask carbon layer 15 and a resist layer 16 are laminated, and a mask pattern of the resist layer 16 is formed by imprinting or the like (FIG. 1B). The carbon layer 15 is formed again as a protective layer through a discrete track forming process (FIGS. 1C to 1G) on the magnetic recording layer by dry etching or the like, and a lubricant is applied to the surface. Then, patterned media type magnetic recording that performs tape burnishing to remove protrusion defects and remove surface particles, performs glide inspection to inspect the presence or absence of protrusions in the inspection process, and then performs error inspection to inspect magnetic defects A method for manufacturing a medium is known (Patent Document 1). The tape burnishing process is a process for finishing the surface of the medium substrate 100 smoothly, reducing the spacing loss with the magnetic head, and improving the signal characteristics, and is an indispensable process for manufacturing the magnetic recording medium. It has become.

  With respect to a method for manufacturing such a patterned media type magnetic recording medium, a concave portion is formed by dry etching in a magnetic recording layer made of a continuous film and separated into divided recording elements, and then the periphery of the divided recording elements is formed by dry cleaning means. A manufacturing method is known in which a foreign substance is removed and then the process of filling the recess with a nonmagnetic material is continuously performed in a vacuum chamber (Patent Document 2). In addition, it is known to perform cleaning such as removal of foreign substances by ultraviolet irradiation, which can be said to be one of dry cleaning means (Patent Document 3). Furthermore, it is also known that the surface can be neutralized by ultraviolet irradiation (Patent Document 4).

JP 2009-87442 A JP-A-2004-326831 (Claims 1 to 3 and FIGS. 1 to 4) JP 2002-148396 A JP 2007-12467 A

  However, when tape varnishing is performed to remove surface protrusions as described above, the surface smoothness is improved and the number of particles is reduced, but the corrosion resistance is conversely reduced. When the corrosion resistance is lowered, the magnetic recording layer is easily deteriorated. As a result, there arises a problem that the signal characteristics are deteriorated and the reliability is deteriorated due to a magnetic recording defect.

  The present invention has been made in view of the above points. The object of the present invention is to have a smooth surface without reducing corrosion resistance even when tape burnishing is performed after forming a protective layer and applying a lubricant to the magnetic recording layer on which discrete tracks are formed, and An object of the present invention is to provide a method for manufacturing a patterned media type magnetic recording medium having excellent signal characteristics and reliability.

Means for Solving the Invention

  In the present invention, in order to achieve the object of the present invention, a substrate surface having a magnetic recording layer laminated on a nonmagnetic substrate via a metal underlayer and divided by a concave discrete track, After irradiating ultraviolet rays in the vacuum ultraviolet region and reducing the charging voltage of the substrate surface to 50 V or less, a step of embedding a non-magnetic material in the concave portion of the magnetic recording layer, a surface flattening step, a protective layer forming step, and a lubricant coating After the steps are performed in this order, a method for manufacturing a patterned media type magnetic recording medium in which a tape burnishing step is performed.

  The metal underlayer preferably includes a soft magnetic layer, a seed layer, and an intermediate layer (Ru alignment layer), and the ultraviolet irradiation in the vacuum ultraviolet region is performed with a power of 500 W or more and an irradiation time of 60 seconds or more. It is desirable. It is also preferable that the protective layer is a carbon protective layer.

  A method of manufacturing a patterned media type magnetic recording medium in which the magnetic recording medium is a perpendicular magnetic recording medium can be employed.

  According to the present invention, the magnetic recording layer on which the discrete track is formed has a smooth surface without reducing corrosion resistance even when tape varnishing is performed after forming the protective layer and applying the lubricant, and It is possible to provide a method for manufacturing a patterned media type magnetic recording medium having excellent signal characteristics and reliability.

It is board | substrate sectional drawing of the surface uneven | corrugated pattern formation process in a general patterned media type magnetic recording medium. It is a schematic block diagram of the round type vacuum apparatus concerning the manufacturing method of the patterned media type magnetic recording medium of this invention.

  Embodiments of a method for manufacturing a patterned media type magnetic recording medium of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to the description of the examples described below unless it exceeds the gist.

  FIG. 2 shows a schematic configuration diagram of a round type vacuum apparatus used for carrying out the method for producing a patterned media type magnetic recording medium of the present invention. This apparatus has a structure in which a plurality of general vacuum chambers used in the case of laminating a plurality of layers on a nonmagnetic substrate in a vacuum and connected in series to a dry device for a patterned media type magnetic recording medium. It is a continuous manufacturing process system with an etching process connected. In this round type vacuum apparatus (FIG. 2), a medium substrate on which a resist pattern is deposited is used as a mask for forming a discrete track on a magnetic recording layer made of a normal continuous film. It is carried into a chamber (vacuum tank). Next, the medium substrate placed on the carrier is sequentially transferred to each process chamber (P1 to P19) in the direction of the arrow in the round type vacuum apparatus, and the last process process in P19 which is a carbon protective layer forming process chamber is performed. After completion, it is unloaded from the L / UL chamber. The unloaded medium substrate is coated with a lubricant on the surface of the carbon protective layer and subjected to a tape burnishing process, whereby the patterned media type magnetic recording medium of the present invention is completed.

  In FIG. 2, a plurality of vacuum chambers are represented by rectangles with symbols such as L / UL, P1 to P19, C1 to C4, VTC, etc., depending on the application, and although not shown in the figure, they are all interconnected and not shown. The pressure is reduced by a vacuum pump. In addition, an opening / closing valve is provided at the connecting portion that connects the vacuum chambers, and the vacuum pressure of each of the chambers can be set individually. Hereinafter, the vacuum chamber may be abbreviated as a chamber. The L / UL chamber is a chamber serving as an inlet of a medium substrate carried into the apparatus and an outlet of a medium substrate that has undergone all the process processes in the apparatus. P1 to P19 are process chambers for performing respective process steps. C1 to C4 are corner chambers for changing the direction of the conveyor for moving the medium substrate by 90 degrees, and also have a function as a pressure adjusting chamber. VTC is a vacuum tunnel chamber for connecting the last process chamber P19 and the L / UL chamber.

  In the P1 to P19 chambers, for example, P2 is used for the resist etching process. In other chambers, P4 is a carbon layer etching process, P6 is a resist peeling process, P8 is a magnetic recording layer etching process, P10 is a carbon layer peeling process, P11 is a deuterium lamp (ultraviolet) irradiation process, and P12 is P14 is used for the surface flattening process of the medium substrate, and P17, P18, and P19 are used for the process of forming the carbon protective layer. Process chambers other than the aforementioned process chambers are used as pressure adjusting chambers. In this way, process chambers used for different processes are arranged not directly adjacent to avoid mixing of the gas species used. The chamber adjacent to each process chamber is set as a pressure adjusting chamber, and is set to a higher vacuum pressure or a vacuum containing argon gas than each adjacent process chamber.

  A perpendicular layer including at least a soft magnetic layer 11, a seed layer 12, a metal underlayer such as an intermediate layer (Ru orientation layer) 13, a magnetic recording layer 14, and a carbon layer 15 in this order on a nonmagnetic substrate 10 shown in FIG. For a magnetic recording medium (hereinafter referred to as medium substrate 100), the carbon layer 15 is used as a hard mask layer, and a resist layer 16 is patterned on the surface of the carbon layer 15 by imprinting. A substrate holder cassette (not shown) containing 25 medium substrates 100 is conveyed as it is to the L / UL chamber entrance by a sputter load conveyor (not shown).

  In order to evacuate 25 medium substrates 100 from the atmosphere to the vacuum, they are set in the load side sub-chamber in the L / UL chamber (not shown in FIG. 2). After the vacuum state is reached, the medium substrate set in the substrate holder is placed in a row on the carrier that transports the inside of a series of vacuum process chambers in the apparatus with the vacuum robot in the L / UL chamber. They are placed side by side and transferred to the process chamber P2 through the pressure adjustment chamber P1. In the process chamber P2, the imprint resist pattern processing shown in FIGS. 1B and 1C is performed. Thereafter, in order to form an uneven track on the medium substrate 100, the carbon layer etching process shown in FIG. 1D is performed in the process chamber P4, and the resist stripping process shown in FIG. Then, the magnetic recording layer etching process shown in FIG. 1 (f) and the process process including the carbon layer peeling process shown in FIG. 1 (g) are sequentially performed in the process chamber P10. Thereafter, before embedding the nonmagnetic material into the recesses 17 formed on the surface of the medium substrate 100, which is a feature of the present invention, the surface of the medium substrate 100 is irradiated with ultraviolet rays in a vacuum ultraviolet region by a deuterium lamp. Remove particles from. The conditions for the ultraviolet irradiation will be described later.

  As described above, in the present invention, it is important to remove particles from the surface of the medium substrate 100 before the step of embedding the non-magnetic material in the recesses 17 on the surface of the medium substrate 100. This is because when removing particles after the embedding process, the nonmagnetic material is deposited on the surface of the medium substrate in the order of particles, so that the surface of the nonmagnetic material is flattened after embedding the nonmagnetic material. This is because even if the particles are removed, the particles at the bottom of the recess cannot be removed. Furthermore, the surface of the convex magnetic recording layer is also a flat surface obtained by depositing a nonmagnetic material on the surface from which particles are removed (the former) and a flattened surface after depositing the nonmagnetic material without removing particles ( It has been found that there is a difference in adhesion between the carbon protective layer and the latter.

  That is, the former has better adhesion of the carbon protective layer, and the surface of the carbon protective layer is highly smooth even after tape varnishing, and local peeling is hardly observed. On the other hand, in the latter case, since the adhesion between the carbon protective layer and the magnetic recording layer is not so good, it was found that local peeling off from the surface of the carbon protective layer resulted in many peeled portions. As a result, compared to the latter, the former is a patterned media type magnetism that has a smooth surface and excellent signal characteristics and reliability, even if it is subjected to tape burnishing. Recording media can be manufactured.

  In addition, this particle removal step prevents the surface of the magnetic recording layer from being deteriorated by exposing the medium substrate 100 to the atmosphere, and avoids a decrease in productivity due to an extension of the tact time in the manufacture of the patterned media type magnetic recording medium. Therefore, it is important to carry out continuously in vacuum together with the previous processing step and the subsequent embedding step.

  Next, a method and conditions for removing particles caused by ultraviolet irradiation will be described below. After the carbon layer 15 is peeled off in the process chamber P10, the medium substrate 100 in the stage of FIG. 1G is transferred to the process chamber P11. In the process chamber P11, the distance between the view port which is a viewing window of the chamber and the medium substrate 100 on the carrier is set to be within 5 mm, and the vacuum region ultraviolet rays are irradiated to both surfaces of the medium substrate 100 at the center of the chamber. A deuterium lamp 19 is attached at the position to be operated. In the medium substrate 100 supported by the holder on the carrier and arranged in two lines, the holder on the downstream side in the transporting direction is set to position 1 and the upstream side is set to position 2. First, the substrate holder at position 1 on the carrier is transported to the center of the deuterium lamps on both sides and stopped. The deuterium lamp 19 is irradiated for a predetermined time, moved after completion, and then the substrate holder at position 2 is transported to the center of the deuterium lamp and stopped. While the position 2 medium substrate is irradiated with ultraviolet rays, the charging voltage on the surface of the position 1 medium substrate is measured.

  Next, the relationship between the irradiation time of the deuterium lamp, the charging voltage, and the number of particles was examined. The irradiation power of the deuterium lamp is fixed at 500 W, and the irradiation time is 0 second (reference), 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds. As a result, the change in charging voltage at each irradiation time was measured. After measuring the charging voltage, for confirmation, P11 was experimentally opened to the atmosphere, and the medium substrate 100 irradiated with the deuterium lamp was taken out. Carry out formation of carbon protective film, lubricant formation and tape varnish on the taken out medium substrate, and measure the number of particles attached to the surface (front and back both sides) of the magnetic recording medium for the produced magnetic recording medium, The effect of deuterium lamp treatment was investigated.

  The number of particles was measured by a wafer edge inspection apparatus that inspects particles and defects on edge portions of semiconductor wafers and the like using a laser-based optical surface analyzer technology at high speed and high accuracy. The measurement of the charging voltage and the number of particles was carried out on 20 surfaces of 10 sheets per condition, corresponding to 10 sheets for each of the 10 conditions of the irradiation time. Table 1 shows the irradiation time of the deuterium lamp, the charging voltage on the substrate surface, and the number of particles (the charging voltage and the number of particles are averages of 10 substrates each).

Table 1 shows that the charging voltage on the substrate surface decreases as the irradiation time of the deuterium lamp is increased. It also shows that as the charging voltage decreases, the particles adhering to the medium substrate decrease, and the irradiation time is 60 seconds or more, and is almost constant and within 300 particles. From the above, it can be seen that the charging voltage can be reduced by irradiating the surface of the medium substrate with a deuterium lamp, and the number of particles adhering to static electricity can be suppressed. After the medium substrate is released from the vacuum to the atmosphere and taken out from the chamber, the level of 300 particles remaining on the surface of the medium substrate is adhered to the 2.5 inch perpendicular magnetic recording medium. However, the number of particles is acceptable in terms of read / write characteristics and reliability, and the number of particles at the same level in a patterned media type magnetic recording medium.
(Comparative Example 1)
When the medium substrate is transported to P11 in the same process as in the first embodiment, with the P11 being opened and at atmospheric pressure, the medium substrate is irradiated with a deuterium lamp and charged voltage is measured, After irradiation with a hydrogen lamp and taking out the medium substrate from the substrate holder, formation of a carbon protective film, formation of a lubricant, and tape varnishing were performed. The difference between Example 1 and Comparative Example 1 is whether the deuterium lamp is irradiated in a vacuum or in the atmosphere. With respect to the patterned media type magnetic recording medium thus produced, the number of particles adhering to the medium substrate surface (front and back surfaces) was measured, and the effect of the deuterium lamp treatment at atmospheric pressure was confirmed. Table 2 shows the deuterium lamp irradiation time, the medium substrate charging voltage, and the number of particles (the charging voltage and the number of particles are averages of measured values on both sides of 10 sheets under the writing conditions).

According to Table 2, with respect to ultraviolet irradiation at atmospheric pressure, there is almost no change in the charging voltage of the medium substrate or the number of particles adhering to the medium substrate, depending on whether or not the deuterium lamp is irradiated and the irradiation time is changed. I understand that. That is, the effect of particle removal by ultraviolet irradiation is hardly seen.
(Comparative Example 2)
For the medium substrate manufactured in the same process as in Example 1 except that the particle removal by the deuterium lamp before embedding is not performed, and the medium substrate 100 in Example 1 where the irradiation time of the deuterium lamp is 60 seconds. Then, nitric acid dropping evaluation was performed. The evaluation was performed by measuring the amount of Co elution with an ICP-MS (Inductively Coupled Plasma Mass Spectrometer) apparatus and comparing them. When nitric acid is dropped, the presence or absence of defects in the carbon protective layer caused by particles on the dropping surface can be determined. If the carbon protective layer has a defect such as a hole or a thin part due to local peeling, nitric acid is immersed in the defect to dissolve the Co component from the magnetic recording layer, so that the amount of Co elution is easily detected. Therefore, if the detected amount of Co component is large, the carbon protective layer has many defects. If there are many defects, the magnetic recording layer is likely to come into contact with the air, so that deterioration such as oxidation is likely to proceed and reliability is lowered.

  Table 3 shows the presence / absence of the foreign substance removal step and the amount of Co (average value of 10 medium substrates).

  From Table 3, it can be confirmed that the amount of detected Co is reduced to about 1/5 when foreign matter (particle) removal is performed (Example 1) and when it is not performed (Comparative Example 2). From the above, it can be seen that the amount of Co elution in the nitric acid dropping evaluation can be reduced by performing the foreign matter removing step after the uneven processing of the magnetic recording layer and before the embedding step. That is, it is understood that a medium substrate manufactured without performing particle removal before embedding has many defects in the carbon protective layer.

  According to the embodiment described above, the ultraviolet ray in the vacuum ultraviolet region is formed on the surface of the magnetic recording layer laminated on the non-magnetic substrate via the metal underlayer and divided by the concave discrete tracks in a vacuum. , And the charging voltage on the surface of the substrate is reduced to 50 V or less, and then a step of embedding a non-magnetic material in the concave portion of the magnetic recording layer, a surface flattening step, a protective layer forming step, and a lubricant coating step are sequentially performed in this order. Then, by performing a tape burnishing process, a method for producing a patterned media type magnetic recording medium having excellent signal characteristics and reliability of the magnetic recording medium can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Nonmagnetic board | substrate 11 ... Soft magnetic layer 12 ... Seed layer 13 ... Intermediate | middle layer (Ru orientation layer)
14 ... Magnetic recording layer 15 ... Carbon layer 16 ... Resist 17 ... Recess 100 ... Media substrate P2, P4, P6, P8, P10, P11, P12, P14 ... Process chamber

Claims (5)

A substrate having a magnetic recording layer laminated on a nonmagnetic substrate via a metal underlayer and divided by a concave discrete track in a vacuum is irradiated with ultraviolet rays in a vacuum ultraviolet region, After the surface charging voltage is reduced to 50 V or less, a step of embedding a non-magnetic material in the concave portion of the magnetic recording layer, a surface flattening step, a protective layer forming step, and a lubricant coating step are sequentially performed in this order. A method of manufacturing a patterned media type magnetic recording medium, wherein a tape burnishing process is performed. The method of manufacturing a patterned media type magnetic recording medium according to claim 1, wherein the metal underlayer includes a soft magnetic layer, a seed layer, and a Ru alignment layer. 2. The method of manufacturing a patterned media type magnetic recording medium according to claim 1, wherein the ultraviolet irradiation in the vacuum ultraviolet region is performed with a power of 500 W or more and an irradiation time of 60 seconds or more. 2. The method for producing a patterned media type magnetic recording medium according to claim 1, wherein the protective layer is a carbon protective layer. 5. The method of manufacturing a patterned media type magnetic recording medium according to claim 1, wherein the magnetic recording medium is a perpendicular magnetic recording medium.

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