JP2011076676A - Method for manufacturing patterned medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing patterned media such as discrete track media to be used for a high-density hard disk drive, which removes a resist mask layer without deteriorating surface flatness due to a remaining resist mask. <P>SOLUTION: The patterned media include magnetic recording layers wherein recording areas and non-recording areas are regularly arranged in an in-plane direction of a substrate. The method of manufacturing the patterned media has a process of removing a resist mask layer including SOG by using the alkaline solvent, wherein an end of removing the resist mask layer is determined based on a film thickness of a recess of the resist mask layer in which solubility to an alkaline-based system solvent is reduced compared with that in a projection part due to ion irradiation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  According to the present invention, in a magnetic recording medium mounted on an HDD (hard disk drive) or the like, a magnetic recording area for recording / reproducing magnetic information and a non-recording area for magnetically separating the magnetic recording area are provided. Of patterned media such as Discrete Track Media (hereinafter referred to as DTM) and Bit Patterned Media (hereinafter referred to as BPM) having magnetic recording layers arranged in the in-plane direction of the substrate. It relates to a manufacturing method.

  With the increase in information processing capacity and downsizing of equipment, there is an increasing demand for high surface recording density and downsizing of the magnetic disk 21 used in the HDD 20 (FIG. 1A). As one means, a perpendicular magnetic recording system has been proposed and put into practical use. Compared with the conventional in-plane recording method, the perpendicular magnetic recording method suppresses a so-called thermal fluctuation phenomenon (a phenomenon in which the thermal stability of the recording signal is lost due to the superparamagnetic phenomenon and the recording signal disappears). Therefore, it is suitable for increasing the recording density.

  In order to further improve the surface recording density, it is required to improve the linear recording density and the track density to narrow the 1-bit recording width. As a means for this, a DTM for patterning the recording magnetic track (recording part) and the nonmagnetic track (non-recording part) in parallel to prevent interference between adjacent recording parts, and an arbitrary pattern are artificially arranged regularly. There are patterned media such as BPM. FIG. 1B illustrates a conceptual diagram of DTM. A soft magnetic layer 2 is formed on an upper layer of the substrate 1, and a magnetic recording area 4a and a non-recording area 4b are arranged in parallel in a track shape thereon.

  As a method for producing patterned media, after forming a magnetic recording layer on a non-magnetic substrate, the magnetic recording layer is partially irradiated with ions to make the ion irradiated portion non-magnetic or non-magnetic, amorphous A technique (for example, Patent Documents 1, 2, and 3) for forming a magnetically separated pattern has been proposed.

  The manufacturing method is described in Patent Document 2 and Patent Document 3, for example. That is, a magnetic recording layer is formed on a nonmagnetic substrate, a resist is formed thereon, and a desired uneven pattern is formed. Thereafter, ions are irradiated from the surface. Ions are shielded by the convex portions of the resist, but the resist concave portions have a thin resist film thickness, so that the ions reach the magnetic recording layer below the resist and demagnetize the magnetic material. Thereafter, the resist is peeled off to obtain a structure in which a magnetic recording layer and a non-magnetic layer as recording portions are arranged in the plane of the patterned medium. That is, this resist plays a role of a mask in ion irradiation, and a layer formed by this resist is called a resist mask layer.

  In Patent Document 2, as a manufacturing method that eliminates the magnetic layer removal step, forms a mask suitable for ion irradiation without increasing the number of steps, and has a low contamination risk, SOG (spin on glass) is applied to the resist mask layer. A method of using is disclosed.

  On the other hand, in the HDD, the flying height of the magnetic head from the magnetic disk has been reduced to about 5 nm as the magnetic recording technology is increased in density, and this flying height is expected to be further minimized in the future. The If this happens, slight irregularities on the magnetic disk cause head crashes and thermal asperity failures, so there is a strong demand for higher flatness of the magnetic disk.

JP 2008-226428 A JP 2008-77788 A JP 2008-135092 A

  In the above-described manufacturing method of patterned media by ion irradiation, removal of remaining resist has been proposed by dry etching, reactive ion etching, ion milling, and the like (Patent Document 3). However, with these techniques, such as etching, the layer immediately below the resist is etched away by excessive etching, or conversely, the etching is terminated early so as not to scrape the layer immediately below the resist. There is a problem that it is very difficult to determine the point at which the etching is optimally stopped in the nm order.

  Therefore, by the same applicant as the present application, the resist mask layer formed by SOG is removed with an alkaline solvent after patterning of the magnetic recording layer by ion irradiation, and unnecessary resist mask layer is easily and optimally removed. Patent applications relating to methods for producing patterned media that can be performed have been filed.

  However, when the present inventors have further studied, when the resist mask layer formed by SOG is removed with an alkaline solvent, a level difference of several nanometers (difference in thickness between the concave portion and the convex portion) is caused by the magnetic field. It was found that the pattern may remain along the pattern formed in the recording layer. FIG. 2 shows an intermediate product of a patterned medium after removal of the resist mask layer with a step remaining (an intermediate product up to a finished product in the process of manufacturing the patterned media. Hereinafter, it is also simply referred to as an intermediate product). .) Shows an AFM (Atomic Force Microscope) image of the surface.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention performed ion irradiation on an intermediate body having a resist mask layer having a concavo-convex pattern and then removed the resist mask layer by etching with a solvent. Since the etching rate is different between the resist mask layer and the resist mask layer of the non-transparent part, the step becomes zero once. However, the step is immediately reversed, and the step becomes zero by further etching. I found out. It was confirmed that the resist mask layer was completely removed when the step difference was zero for the second time.

  FIG. 3 shows how the level difference changes when the resist mask layer is removed by etching. Conventionally, it is considered that the step does not change after about 60 minutes when the step becomes constant, and the etching is finished. After that, the change in the level was saturating, so it was thought that the level would not disappear. However, when the present inventors conducted a detailed investigation, it was discovered that the etching rate of the concave portion and the convex portion was different, and if the etching was performed for a longer time, the resist mask layer was completely removed without leaving a step. It was found that it can be removed.

  Reference numeral 31 in FIG. 3 denotes a step before the removal of the resist mask layer when the resist mask layer on which the uneven pattern is formed is on the surface. When the resist mask layer is removed by etching, the level difference decreases (34), and the level difference becomes zero for the first time (32). After that, a step having inverted concaves and convexes is generated (35), and the resist mask layer is completely removed by continuing the etching, so that the step becomes zero for the second time (33).

  The present invention has been made based on the above-mentioned findings, and the gist thereof is as follows.

(1) A magnetic recording area for recording / reproducing magnetic information and a non-recording area for magnetically separating the magnetic recording area are regularly arranged on the base in the in-plane direction of the base. A patterned recording medium manufacturing method comprising: forming a non-recording region by irradiating the magnetic recording layer with ions;
A release layer forming step of forming a release layer mainly composed of carbon on the magnetic recording layer;
A resist mask layer forming step of forming a resist mask layer made of SOG (spin-on-glass) on the release layer;
The thickness of the resist mask layer is partially changed to form a convex portion and a concave portion of a predetermined pattern, and the convex portion has a thickness that does not transmit ions when the ions are irradiated, and the concave portion is an ion A patterning process to make the thickness sufficiently thin to transmit,
An ion irradiation step of irradiating ions from above the resist mask layer after the patterning step;
And removing the resist mask layer with an alkaline solvent after the ion irradiation step, and a resist mask layer removing step in this order,
In the resist mask layer removing step, determining the end point of the resist mask layer removing step based on the film thickness of the concave portion of the resist mask layer whose solubility in an alkaline solvent is worse than that of the convex portion by the ion irradiation step. A method for producing a patterned medium.

  (2) In the resist mask layer removing step, when the step between the convex portion and the concave portion adjacent to the resist mask layer removed by the alkaline solvent becomes zero for the second time, the resist mask layer removing step is performed. The method for producing a patterned medium according to (1), which is terminated.

  (3) The patterned media manufacturing method according to (1) or (2), wherein a step between the adjacent convex portion and the concave portion is measured during the resist mask layer removing step.

  (4) The patterned medium according to (1) or (2), wherein a processing time for removing the resist mask layer is determined in advance, and the removal of the resist mask layer is completed within the determined processing time. Manufacturing method.

  (5) A processing time for removing the resist mask layer is determined in advance based on the step between the adjacent convex portion and the concave portion manufactured in the immediately preceding batch, and the resist mask layer is removed at the determined time. (1) or (2) the method for producing a patterned medium.

  (6) A processing time for removing the resist mask layer is determined in advance for a plurality of combinations of ion irradiation conditions, resist conditions, and / or etching conditions, and a resist mask layer having a condition suitable for the implementation conditions is determined. (1) or (2), wherein the removal of the resist mask layer is completed in a processing time for the removal.

(7) Ion irradiation in the ion irradiation step includes B, P, Si, F, C, In, Bi, Kr, Ar, Xe, W, As, Ge, Mo, Sn, N ₂ , O ₂ , Ne, Irradiating one or more ions selected from He and H ₂ at an irradiation energy of 1 keV to 50 keV and a dose of 1E15 atoms / cm ² to 1E17 atoms / cm ² (1) to ( 6) The patterned medium manufacturing method according to any one of 6).

(8) When the film thickness of the convex part of the resist mask layer formed in the patterning step is t _s and the film thickness of the concave part is t _c ,
t _c ≦ 30nm
2 ≦ t _s / t _c ≦ 10
The method for producing a patterned medium according to any one of (1) to (7), wherein:

  (9) A patterned layer according to any one of (1) to (8), further comprising a lubricating layer forming step of forming a lubricating layer on the protective layer after completion of the resist mask layer removing step. Media production method.

  (10) The patterned medium manufacturing method according to any one of (1) to (9), wherein the formation of the pattern of the resist mask layer in the patterning step is performed by a nanoimprint method.

  The patterned media manufactured by the manufacturing method of the patterned media in any one of (1)-(10).

  According to the present invention, in a method for producing patterned media such as DTM and BPM, the step on the surface can be easily reduced sufficiently, and patterned media with high surface flatness can be obtained.

(A) is a schematic diagram of a hard disk drive (HDD), and (b) is a schematic diagram of a discrete track medium (DTM). It is an AFM image of the surface of a magnetic disk by a conventional manufacturing method. It is a figure which shows an example of the change of the level | step difference of the intermediate body of a patterned media in a resist mask layer removal process. It is a figure which shows the concept of the cross-section of patterned media. It is a figure which shows the concept of the manufacturing process of the patterned media based on this invention, (a) is a conceptual diagram of a protective layer film-forming process, (b) is a conceptual diagram of a resist mask layer film-forming process, (c) is patterning The conceptual diagram of a process, (d) is a conceptual diagram of an ion irradiation process. It is a figure which shows the concept of the surface change of the intermediate body in a resist mask layer removal process, (a) is a conceptual diagram of the intermediate body surface before a resist mask layer removal process, (b) is a resist mask layer of a fixed amount removed. (C) is a conceptual diagram of the intermediate surface when the step is zeroed for the first time, (d) is a certain amount of resist after the step is zero for the first time. The conceptual diagram of the intermediate body surface from which the mask layer was removed, (e) is the conceptual diagram of the intermediate body surface from which the convex portion was completely removed before the resist mask layer removing step, and (f) is 2 steps. The conceptual diagram of the intermediate body surface when it becomes zero in the 2nd time, (g) is the conceptual diagram of the intermediate body surface after a process with a solvent is advanced after a level | step difference became zero in the 2nd time. It is the result of having measured the patterned media manufactured with the method of this invention with the magnetic force microscope.

  In the present invention, when producing patterned media by the ion irradiation method, after removing the resist mask layer using an alkaline solvent after ion irradiation, ion irradiation is performed instead of the convex portion of the thick resist mask layer. Thus, the end point of the resist mask layer removing step is determined based on the film thickness of the concave portion of the thin resist mask layer whose solubility in the alkaline solvent is worse than that of the convex portion.

  Specifically, for example, the end point of the resist mask layer removing step can be determined based on the point where the film thickness of the concave part becomes zero or the step between the concave part and the convex part becomes zero for the second time. . Hereinafter, the present invention will be described in detail.

  FIG. 4 shows a conceptual diagram of the cross-sectional structure of the patterned media. In general, a soft magnetic layer 42 (SUL: Soft Under Layer), an intermediate layer 43, a magnetic recording layer 44, a protective layer 45, and a lubricating layer 46 are arranged in this order on a disc-shaped substrate 41 made of a nonmagnetic material. Each layer is built up. Each layer below the magnetic recording layer is also subdivided into several layers, but the subdivided layer structure is not particularly limited in the present invention. Each of these layers is formed by depositing a material necessary for each layer by a CVD method, a PVD method, a magnetron sputtering method, or the like.

  As the non-magnetic base material, glass or aluminum is usually used. The material of the glass substrate is not particularly limited. Examples thereof include glass ceramics such as aluminosilicate glass, soda lime glass, soda aluminosilicate glass, aluminoborosilicate glass, borosilicate glass, quartz glass, chain silicate glass, or crystallized glass. These glass and aluminum are processed into a disk shape and subjected to surface polishing, etc., and the glass is subjected to treatment such as scientific strengthening and used as a non-magnetic substrate.

  The soft magnetic layer 42 is a layer for temporarily forming a magnetic circuit at the time of recording in order to pass a magnetic flux in a direction perpendicular to the magnetic recording layer in the perpendicular magnetic recording method. As the material of the magnetic layer, for example, a cobalt-based alloy such as CoTaZr, or a Co—Fe-based alloy such as CoFeTaZr or CoCrFeB is used.

  The intermediate layer 43 is a layer that blocks material interference between the lower soft magnetic layer 42 and the upper magnetic recording layer 44. Further, it has a so-called base function for controlling the grain size, grain size dispersion, and crystal orientation of the upper magnetic recording layer 44. If the intermediate layer is further divided into an upper layer and a lower layer, it is preferable for simultaneously controlling the crystal orientation and the grain size of the magnetic recording layer. For example, for the lower layer of the intermediate layer, a simple metal such as Ni, Cu, Pt, Pd, Zr, Hf, or Nb, or an alloy obtained by adding W, Cr, V, Ta, Mo or the like to them can be used. For controlling the crystal orientation of the magnetic recording layer 44, for example, an hcp or fcc crystal material such as Ru, Re, Pd, or Pt, or an alloy such as RuCr or RuCo can be used. In particular, Ru is effective in improving the crystal orientation of Co because it has a lattice constant close to that of Co, which is the main component of the magnetic grains of the magnetic recording layer 44, and has the same crystal structure.

  The magnetic recording layer 44 becomes a part for recording information, which is a main function of the patterned medium. Due to the perpendicular recording system, the magnetic particles of the ferromagnetic material having a columnar structure are formed in a granular structure in which a grain boundary made of a nonmagnetic material is surrounded. As a material for the magnetic recording layer, for example, a composite material obtained by adding an oxide to a Co-based alloy, an Fe-based alloy, or a Ni-based alloy is used. A columnar granular structure can be suitably obtained by depositing this material on the intermediate layer and epitaxially growing it.

  The protective layer 45 can be formed by forming a thin film mainly made of carbon by a CVD method. The protective layer 45 has a role of protecting the magnetic recording layer 44 from the impact of the magnetic head and increasing the reliability by suppressing the corrosion of the magnetic recording layer. In general, carbon formed by the CVD method is denser and has a higher film hardness than that formed by the sputtering method, so that the reliability can be further improved.

  The lubrication layer 46 is usually a finished product of patterned media and is formed on the protective layer 45, and is intended to prevent damage or loss of the protective layer 45 when the magnetic head comes into contact. . The lubricating layer 46 can be formed of PFPE (perfluoropolyether) by dip coating.

  Next, the manufacturing method of the patterned media based on this invention is demonstrated using FIG. In the manufacturing process according to the present invention, an intermediate of a patterned medium in which a soft magnetic layer, an intermediate layer, and a magnetic recording layer are laminated on a substrate is used as a protective layer forming process, a resist mask layer forming process, a patterning process, an ion By passing the irradiation process and the resist mask layer removal process in this order, a patterned medium of a finished product is obtained. FIG. 5 shows a layer above the magnetic recording layer.

  FIG. 5A shows a protective layer forming step. The protective layer film forming step is a step of forming the protective layer 45 on the intermediate body laminated up to the magnetic recording layer, and is a method of forming carbon by the CVD method. The film thickness is about several nm, and a uniform film forming technique is required.

  FIG. 5B shows a resist mask layer forming process. The resist mask layer forming step is a step of forming a resist mask layer 51 for subsequent patterning on the protective layer 45. As the resist, a resist suitable for the subsequent patterning method is selected. Here, a case where patterning is performed by the nanoimprint method will be described as an example. Of course, the patterning method is not limited to the nanoimprint method, and a lithography method used in a semiconductor can also be used.

  In the present invention, a room temperature nanoimprint resist is used as a nanoimprint resist for nanoimprint.

  The room temperature nanoimprint resist is formed by pressing a stamper, taking a mold as it is, and releasing the mold. It is a very simple process because it simply presses the stamper. However, since the pressing pressure of the stamper is high, it is necessary to develop a device for that purpose. However, it is easy to handle and the equipment configuration is not complicated.

  A room temperature nanoimprint resist is a liquid material in which a silicon (Si) compound and additives (diffusion impurities, glassy forming agent, organic binder, etc.) are dissolved in an organic solvent (alcohol, ester, ketone, etc.). There are glass, hydrogenated silsesquioxane polymer (HSQ), hydrogenated alkylsiloxane polymer (HOSP), alkylsiloxane polymer, alkylsilsesquioxane polymer (MSQ), etc., which are called SOG (spin-on-glass) ing. In the resist mask layer forming step, SOG is applied on the protective layer by spin coating to form a film. The thickness is preferably about 50 to 60 nm although it depends on patterning. The resist mask layer has a role of resist and a role of mask in the ion irradiation process.

  FIG. 5C shows a patterning process. As shown in FIG. 5C, the magnetic track pattern is transferred (imprinted) by pressing the stamper 52. The stamper 52 has a concavo-convex pattern corresponding to each pattern of a track portion as a recording region to be transferred and a non-track portion which is a non-recording region, that is, an ion transmission region and an ion shielding (mask) region.

  At the time of ion irradiation, a portion through which ions are transmitted becomes a concave portion of the resist mask layer, and a portion that blocks ions becomes a convex portion of the resist mask layer. That is, the unevenness of the stamper 52 is reversed.

In other words, the thickness of the convex portion of the resist mask layer has at least a thickness that does not transmit ions when ion irradiation is performed, and the thickness of the concave portion is sufficiently thin to allow ions to pass therethrough. For example, the resist is SOG, and the implanted ions are B, P, Si, F, C, In, Bi, Kr, Ar, Xe, W, As, Ge, Mo, Sn, N ₂ , O ₂ , Ne, and He. If the ion irradiation energy is 1 KeV to 50 KeV and the dose is 1E15 to 1E17 atoms / cm ² with one or more ions selected from H ₂ , the thickness of the concave portion of the resist mask layer is 30 nm or less. desirable. At that time, when the thickness t _s of the convex portion of the resist mask layer and the thickness of the concave portion are t _c, it is desirable that the ratio of the thickness satisfies 2 ≦ t _s / t _c ≦ 10. Although the thickness of the convex portion of the resist mask layer depends on the ion irradiation energy, if it is 50 nm or more, there is no ion transmission and a sufficient mask effect is obtained.

  After the magnetic recording track pattern is transferred by the stamper 52, the stamper is released (released) from the resist mask layer 51, whereby a desired uneven pattern is formed on the resist mask layer 51. At this time, if a release agent is applied to the stamper surface, the stamper can be easily released.

  FIG. 5D shows an ion irradiation process. The intermediate body whose surface is covered with the resist mask layer is irradiated with ions 53, and the medium is irradiated with ions. At this time, the convex portion of the resist mask layer 51 is shielded because the resist mask layer is thick and the ions 53 do not pass through the resist mask layer. On the other hand, since the resist mask layer is thin in the concave portion of the resist mask layer, the ions 53 are transmitted through the resist mask layer 51 and the protective layer 45, and ions are irradiated to the magnetic recording layer directly therebelow.

  By irradiating the magnetic recording layer with ions, the magnetic property of the magnetic recording layer becomes soft, non-magnetic, or amorphous. Therefore, the magnetic layer is much weaker than that of a ferromagnetic layer that is not irradiated with ions, so that a non-recording region is formed. Since the ion beam is highly linear, a non-recording area can be formed in accordance with the shape of the recess in the resist mask layer. As a result, a layer separation region is formed between the track regions serving as the memory regions. The narrower the width, the higher the magnetic recording density.

Although the ion is not particularly limited to irradiation, typically, B, P, Si, F , C, In, Bi, Kr, Ar, Xe, W, As, Ge, Mo, Sn, N 2, O 2, Ne, He , One or more ions selected from the group consisting of H ₂ are irradiated. The valences of the above ions are all +1. Among the above ions, Ar, N ₂ , O ₂ , Kr, Xe, Ne, He, and H ₂ are preferably used from the viewpoint of ease of handling. Furthermore, from the viewpoint of cost, it is more preferable to use Ar, N ₂ , or O ₂ .

If the irradiation energy is 1 to 50 keV and the dose amount is 1E15 to 1E17 atoms / cm ² , ions can be implanted into the magnetic recording layer through the recess of the SOG resist mask layer.

  Next, the outline of the resist mask layer removing process will be described with reference to FIG. The removal of the resist mask layer is performed by wet etching. When the resist mask layer is SOG, the etching rate is remarkably reduced when an organic solvent is used, so an alkaline solution is used as the solvent. As the alkaline solution, a KOH-containing solution, a NaOH-containing solution, or the like is usually used.

  In the present invention, the end point of the resist mask layer removing step is determined based on the film thickness of the concave portion of the resist mask layer. For example, the step between the concave portion and the convex portion becomes zero for the second time (FIG. 6F). ) To determine the end point of the resist mask layer removing step. Hereinafter, the fact that the step becomes zero twice will be described in detail.

  FIG. 6A schematically shows the surface of the intermediate of the patterned media before removing the resist mask layer. The resist mask layer has a desired uneven pattern, and has a step between the convex portion 51a and the concave portion 51b. This corresponds to point 31 in the graph of FIG.

  When the resist mask layer 51 is removed by wet etching using a solvent, the level difference on the surface of the intermediate body is gradually reduced (FIG. 6B). This corresponds to the area 34 of the graph shown in FIG.

  The step is gradually reduced because the speed at which the convex portions 51a of the resist mask layer are etched is faster than the speed at which the concave portions 51b are etched. This phenomenon occurs because the concave portion of the resist mask layer near the protective layer is altered by the transmission of the ion beam and is difficult to be etched by the solvent, and is stuck to the protective layer 45. Conceivable.

  As the etching progresses, the step between the convex portion 51a and the concave portion 51b disappears, and the step becomes zero for the first time (FIG. 6C). This corresponds to the point 32 in the graph shown in FIG. At this time, the surface of the intermediate is flat, but the resist mask layer 51 is not removed and remains on the surface.

  After the step becomes zero for the first time, etching of the portion that was a convex portion in FIG. 6A proceeds, and a step is immediately formed on the surface again (FIG. 6D). The unevenness at this time is opposite to that in FIG. 6A, that is, the portion that was a convex portion in FIG. 6A becomes a concave portion. This corresponds to the area 35 of the graph shown in FIG.

  Thereafter, when the removal of the resist mask layer was further advanced, the resist mask layer that was a concave portion in FIG. 6D was removed (FIG. 6E), and the remaining convex portion was shown in FIG. 6D. The resist mask layer is removed, and the point where the level difference becomes zero for the second time is reached (FIG. 6F). This corresponds to the point 33 in the graph shown in FIG. It is a feature of the present invention that the etching of the resist mask layer is terminated when this point is reached. In the present invention, since the resist mask layer removing process is terminated at the point where the step becomes zero for the second time, a patterned medium having a sufficiently small step can be obtained.

  In addition, after the level difference becomes zero for the second time, when the processing with the solvent is further advanced, the level difference is generated again. This is thought to be because the metal under the protective layer was dissolved in the solvent because the portion of the protective layer 45 that was ion-irradiated and was a concave portion in FIG. FIG. 6 (g)). This corresponds to the region 36 of the graph shown in FIG.

  The present inventors have confirmed that such a phenomenon occurs for a plurality of types of SOG, when a KOH-containing solution is used as a solvent, and when a NaOH-containing solution is used. In this case, the method of the present invention can be similarly applied.

  Here, in the step of removing the resist mask layer, the resist mask layer remains on the surface of the protective layer at the point where the step becomes zero for the first time (FIG. 6C). In addition, when used in an HDD, the distance between the head and the magnetic layer is increased, which adversely affects R / W (recording / reproduction) characteristics.

  On the other hand, the resist mask layer does not remain at the point where the level difference becomes zero for the second time (FIG. 6F). Since the resist mask layer is unnecessary for the patterned media as described above, in the present invention, the resist mask layer removing process is completed when the step becomes zero for the second time.

  The change in the level difference of the intermediate of the patterned media is performed by, for example, a method in which a predetermined number of patterned media samples for level difference measurement are prepared, one of them is taken out at a constant interval, and the level difference is sequentially measured. Can do.

  In addition, if the processing time for removing the resist mask layer until the step reaches zero for the second time is determined first, the subsequent batches finish removing the resist mask layer in the determined processing time. Thus, patterned media having a flat surface can be obtained.

  Further, based on the level difference of the patterned media manufactured in the immediately preceding batch, it is possible to perform a feedback process that determines the time for the resist mask layer removal process of the next batch.

  Also, ion irradiation conditions such as ions to be irradiated and ion irradiation process time, resist mask conditions such as resist mask type and thickness, and / or solvent type, concentration and temperature etching for removing resist mask layer For a plurality of combinations having different conditions, a processing time for removing the resist mask layer is determined in advance, and, for example, by creating a database of the processing time, the resist mask layer having a condition that meets the conditions for implementation can be obtained. The processing time for removal can be extracted from the database, and the removal of the resist mask layer can be completed with the extracted processing time.

  According to the method of the present invention, after completion of the resist mask layer removal step, patterned media having a flat surface can be obtained by a simple method without requiring steps such as surface polishing and recoating.

  By passing through the above process, the patterned media of the high surface flatness which patterned by the ion irradiation method are obtained.

  Examples in which patterned media are manufactured by the method of the present invention will be described below.

  A room-temperature nanoimprint resist (SOG) was applied to a laminate of up to a protective layer on a glass substrate having a diameter of 2.5 inches in the same manner as in ordinary magnetic disk production to form a resist mask layer. The resist mask layer thickness was 95 nm.

  Next, the resist mask layer was patterned by a nanoimprint method using a stamper having an uneven width of 90 nm and a height of 150 nm, respectively. The pressing pressure at this time was 100 MPa and the pressing time was 10 seconds.

Next, the ion beam was irradiated onto the magnetic disk after patterning to perform ion irradiation. Ion irradiation was performed by irradiating nitrogen (N ₂ ) ions at 20 KeV to a dose of 2 × 10 ¹⁶ atoms / cm ² .

  Next, in the resist mask layer removing step, the magnetic disk after the ion irradiation was immersed in a KOH-containing solution. The concentration of the solution was 10%, and the temperature was 50 ° C.

  In the resist mask layer removing step, one magnetic disk was taken out every 5 minutes and the step was measured by AFM. The measurement range of AFM was 2 μm. The level difference was calculated from the height difference between the two peak values by outputting a frequency distribution curve of height from the AFM data. The two peaks indicate the most typical heights of the concave portion and the convex portion, and a step within the measurement range can be calculated by looking at this difference.

  When the step of the magnetic disk taken out 10 minutes after the start of immersion in the KOH-containing solution was measured, it was 0.4 nm, and when the step of the magnetic disk taken out after 15 minutes was measured, it was 1.7 nm. After 20 minutes, 3.1 nm, after 30 minutes, 4.4 nm, and after 50 to 100 minutes, saturated in a range of about 5 nm. Therefore, 10 minutes after the start of immersion, it was determined that the level difference became zero for the first time.

  Thereafter, since the step of the magnetic disk taken out 180 minutes after the start of immersion in the KOH-containing solution was 0.3 nm, it was determined that the step was zero for the second time, and the resist mask layer removal step was terminated there.

  FIG. 8 shows the results of measuring the manufactured patterned media with a magnetic force microscope (hereinafter referred to as MFM). It was confirmed that the magnetic area 81 and the non-recording area 61 were magnetically clearly separated.

  The manufactured patterned media was subjected to a glide test using a glide test head equipped with a pico slider in a RQ7800 evaluation device manufactured by Hitachi High-Technologies Corporation, with a glide height (head flying height) of 5 nm. As a result, abnormal protrusions were not detected.

  A magnetic disk was manufactured in the same manner as in Example 1. However, the immersion time of the KOH-containing solution in the resist mask layer removing step was determined to be 180 minutes in advance from the result of Example 1, and the step measurement was not performed by taking out the magnetic disk in the middle.

  When the surface of the manufactured patterned media was confirmed by AFM, no protrusions or the like were confirmed. In addition, as a result of measurement by MFM, the recording area and the non-recording area are magnetically separated as in the case of Example 1. As a result of performing the glide test, the abnormal projections and the like are similar to those in Example 1. Not detected.

[Comparative Example]
Patterned media with immersion times of 10 minutes, 60 minutes, and 220 minutes in the KOH-containing solution were produced (respectively referred to as Comparative Examples 1, 2, and 3). The conditions were the same as in Example 1 except for the immersion time in the KOH-containing solution.

  As a result of observing Comparative Examples 1 to 3 with MFM, the recording area and the non-recording area were clearly separated as in Examples 1 and 2. When the surface shape was confirmed by AFM, no step was observed in Comparative Example 1, but a step of about 5 nm was observed in Comparative Examples 2 and 3. As a result of the glide test, Comparative Example 1 was acceptable and Comparative Examples 2 and 3 were unacceptable.

  Therefore, when the recording / reproducing characteristics of Examples 1 and 2 and Comparative Example 1 were compared, Comparative Example 1 was inferior to Examples 1 and 2. This is because, although the surface level difference disappears in the immersion time of Comparative Example 1, the SOG remains uniformly, so that the distance between the head and the magnetic recording layer is increased by the thickness, and the recording / reproducing characteristics deteriorate. . The recording / reproduction characteristics were measured by a spin stand tester using a perpendicular magnetic recording head equipped with a TMR element for reproduction.

  As described above, in the patterned media manufactured by the method according to the present invention, the resist mask layer is appropriately removed, a very high surface flatness is realized, and functionally high-density magnetic recording is possible. It was confirmed.

  The present invention can be used for manufacturing high-density patterned media manufactured by an ion implantation method. In particular, since high surface flatness can be realized, it can be applied to high-density small magnetic disks and the like that will be increasingly demanded in the future.

1 Base 2 Soft Magnetic Layer 4a Magnetic Recording Area 4b Non-Recording Area 20 HDD
21 Magnetic disk 22 Gimbal spring 23 Drive system (rotary actuator)
24 Magnetic head 31 Point before resist mask layer removal step 32 Point where level difference becomes zero for the first time 33 Point where level difference becomes zero for the second time 34 Area with large level difference (initial stage of resist mask layer removal)
35 Area with large steps (stage after the unevenness of the resist mask layer is reversed)
36 Area with large steps (stage where magnetic atoms have dissolved into the solvent and have stepped again)
DESCRIPTION OF SYMBOLS 41 Base 42 Soft magnetic layer 43 Intermediate layer 44 Magnetic recording layer 45 Protective layer 46 Lubricating layer 51 Resist mask layer 51a Convex part of resist mask layer 51b Concave part of resist mask layer altered by ion irradiation 52 Stamper 53 Ion 61 Non-recording area ( Nonmagnetic region)
81 Magnetic recording area

Claims (11)

Magnetic recording in which a magnetic recording area for recording and reproducing magnetic information and a non-recording area for magnetically separating the magnetic recording area are regularly arranged in the in-plane direction of the base on the base A patterned medium manufacturing method for forming the non-recording region by irradiating the magnetic recording layer with ions,
A release layer forming step of forming a release layer mainly composed of carbon on the magnetic recording layer;
A resist mask layer forming step of forming a resist mask layer made of SOG (spin-on-glass) on the release layer;
The thickness of the resist mask layer is partially changed to form a convex portion and a concave portion of a predetermined pattern, and the convex portion has a thickness that does not transmit ions when the ions are irradiated, and the concave portion is an ion A patterning process to make the thickness sufficiently thin to transmit,
An ion irradiation step of irradiating ions from above the resist mask layer after the patterning step;
And removing the resist mask layer with an alkaline solvent after the ion irradiation step, and a resist mask layer removing step in this order,
In the resist mask layer removing step, determining the end point of the resist mask layer removing step based on the film thickness of the concave portion of the resist mask layer whose solubility in an alkaline solvent is worse than that of the convex portion by the ion irradiation step. A method for producing a patterned medium.   In the resist mask layer removing step, the resist mask layer removing step is terminated when the step between the convex portion and the concave portion adjacent to the resist mask layer removed by the alkaline solvent becomes zero for the second time. The method for producing a patterned medium according to claim 1.   3. The method for manufacturing a patterned medium according to claim 1, wherein a step between the adjacent convex portion and the concave portion is measured during the resist mask layer removing step.   3. The method of manufacturing a patterned medium according to claim 1, wherein a processing time for removing the resist mask layer is determined in advance, and the removal of the resist mask layer is finished at the determined processing time. .   A processing time for removing the resist mask layer is determined in advance based on the step between the adjacent convex portion and the concave portion manufactured in the immediately preceding batch, and the removal of the resist mask layer is completed at the determined time. The method for producing a patterned medium according to claim 1 or 2, wherein:   The processing time for removing the resist mask layer is determined in advance for a plurality of combinations of ion irradiation conditions, resist conditions, and / or etching conditions, and the resist mask layer is removed under conditions that match the conditions of implementation. The patterned medium manufacturing method according to claim 1, wherein the removal of the resist mask layer is completed within a processing time of 3. Said ion irradiation in the ion irradiation step, B, P, Si, F , C, In, Bi, Kr, Ar, Xe, W, As, Ge, Mo, Sn, N 2, O 2, Ne, He, H ₂ selected from one or more of the ion irradiation energy 1keV or more, 50 keV or less, dose 1E15 atoms / cm ² or more, any one of claims 1 to 6, wherein the irradiation with 1E17atoms / cm ² or less 2. A method for producing a patterned medium according to item 1. When the film thickness of the convex part of the resist mask layer formed in the patterning step is t _s and the film thickness of the concave part is t _c ,
t _c ≦ 30nm
2 ≦ t _s / t _c ≦ 10
The method for manufacturing a patterned medium according to claim 1, wherein:   The patterned media according to claim 1, further comprising a lubricating layer forming step of forming a lubricating layer on the protective layer after completion of the resist mask layer removing step. Manufacturing method.   The patterned medium manufacturing method according to claim 1, wherein the formation of the pattern of the resist mask layer in the patterning step is performed by a nanoimprint method.   The patterned media manufactured by the manufacturing method of the patterned media of any one of Claims 1-10.