JPH02267730A - Formation of magnetic recording medium - Google Patents

Abstract

PURPOSE:To make mass production of the magnetic recording medium which allows tracking with high accuracy by forming a resist mask of desired patterns and forming the magnetic recording medium having no magnetic thin films in desired parts. CONSTITUTION:There are tracks 2 on the magnetic recording thin-film medium 5 on a substrate 1. Many servo regions and data regions are alternately provided on one round of the tracks. Tracking marks are provided in the respective servo regions and a pair of rectangular pits 3, 4 which are long in the radial direction of the disk are formed on the right and left of the center line of the tracks 2. The magnetic recording thin film 5 of the pits 3, 4 is selectively etched via the resist mask. The initial magnetization direction 6 of the thin film 5 is circumferential direction. Magnetic poles 7, 8 of N and S are formed on both end walls of the respective pits and magnetic fields are generated in the pits 3, 4, according to this constitution. Magnetic fluxes 9 generated in a magnetic head 10 are detected by a coil 12 at the time of the passage in the pits 3, 4, by which a tracking signal 11 is obtd. The mass production of the recording medium which can track the magnetic head with the high accuracy is enabled by this constitution.

Description

[Detailed description of the invention]

[Industrial Application Field 1] The present invention relates to a method for producing a magnetic recording medium, and in particular to a method for producing a magnetic recording medium having tracking information suitable for magnetically recording and reproducing digital information while controlling tracking of a magnetic head. Regarding the creation method. [Prior Art] In magnetic recording media for recording digital information, a magnetic cylinder is sputtered onto a disk substrate, such as an aluminum substrate, and after initial magnetization, the disks are initialized one by one with a magnetic head using a servo writer or magnetic recording medium. ing. [Three Problems to be Solved by the Invention] The following points have not been considered in the prior art. In other words, in order to increase the density of the current magnetic recording media, it is necessary to make the rack width narrower and use saporide, which increases the processing precision of the mechanical parts of magnetic recording media and magnetic recording devices. There is a need. However, this reduces the productivity of magnetic recording media, requires ultra-precise mechanical parts of magnetic recording devices, and makes magnetic recording devices extremely large in terms of stability, cost, etc. There are drawbacks. A first object of the present invention is to provide a method for easily producing a magnetic recording medium that is magnetically detectable and has portions in which the magnetic film is removed in places. A second object of the present invention is to easily produce a magnetic recording medium having magnetically detectable tracking pits that enables highly accurate tracking electronic control of a magnetic head and enables highly reliable high-density recording. The purpose is to provide a method for creating new products.

[Means to solve the problem]

The production method of the present invention is characterized by producing a magnetic recording medium that is magnetically detectable and has a portion in which a magnetic film is locally removed. A large number of tracking marks are periodically provided along the track, each of which is formed by long pits in the radial direction of the disk, distributed left and right with respect to the track center line. A feature of this method is to create a magnetic recording medium without a magnetic film in the pit portion. The present invention first has a desired pattern, for example, a pattern in which a large number of tracking marks consisting of a pair of long pits in the radial direction of the disk distributed left and right with respect to the track center line are provided periodically along the rack. By preparing a mask, exposing a resist provided on the magnetic 7F crotch through the mask, removing the resist corresponding to the pit, and using the resist as a mask, removing the magnetic thin film corresponding to the pit. The present invention is characterized in that a magnetic recording medium having no magnetic film in a desired portion is produced. The above-mentioned mask having the desired pattern has a pattern formed by irradiating the mask with a substantially uniform amount of light by making the feed pitch of the optical system smaller than the diameter of the light spot.

[Operation 1] According to the present invention, a desired pattern, for example, a tracking mark consisting of a pair of long pits in the disk radial direction distributed left and right with respect to the track center line, is periodically placed on the magnetic recording medium along the track. It is possible to form a large number of patterns on the surface and remove the magnetic thin film only in desired areas with high precision, and easily create a magnetic recording medium that is magnetically detectable and has areas where the magnetic film is locally removed. It is possible to do so. Furthermore, since the mask having the desired pattern can be used multiple times, magnetic recording media having the same pattern can be easily produced with high precision. Embodiment 1 FIG. 1 shows an embodiment of a magnetic recording medium according to the present invention, and shows a tracking mark provided on a recording track of this magnetic recording medium in an enlarged manner. The magnetic recording medium base 1 is made of glass, resin, or aluminum. A magnetic recording thin film medium 5 is formed on this medium base 1. Tracks 2 are provided concentrically or spirally along the circumferential direction of the recording medium, and one circumference of the track 2 consists of a large number of servo areas and data areas. These servo areas and data areas are provided alternately as shown in FIG. 2(b). Each servo area is provided with a tracking mark, and a pair of long rectangular pits 3.4 are formed in the disk radial direction, distributed left and right with respect to the center line of the track 2. There is no magnetic recording thin film 5 in these pits 3.4. The initial magnetization direction 6 of the magnetic recording thin film 5 is uniformly oriented in the disk circumferential direction, that is, in the data recording direction. FIG. 2 is a diagram for explaining the operation of detecting a tracking signal by a magnetic head from the magnetic recording medium according to the present invention shown in FIG. 1. A cross-sectional view along the recording direction is shown. The pit 3.40 portion is flat, and there is no magnetic recording thin film 5 in that portion. In this way, N and S magnetic poles 7.8 are formed on both end walls of each pit, and as a result a magnetic field is generated in each pit 3.4. By scanning the pit 3.4 part with the magnetic head 10 and detecting the magnetic flux 9 formed in the magnetic head 10 with the coil 12 when passing through the pit 3.4 part, the magnetic flux 9 shown in FIG. Tracking signal 1 as shown in
You can get 1. A method for producing the magnetic recording medium shown in FIG. 1 will be explained using FIGS. 4 and 5. FIG. 4 shows a photomask recording apparatus used in one embodiment of the present invention. This recording device records a desired pit pattern on a chrome photomask 13 using ultraviolet laser light. In FIG. 4, a chrome photomask 13 is fixed to a rotation bearing and rotated. On the other hand, laser light, such as an argon laser (I11 = 0.45 microns), is intensity-modulated by an optical modulator, and when focused by a lens with a high NA (for example, NA = 0.93), it is projected onto a rotating mask with a diameter of 0.4 microns. A circular spot of micron size is formed. Now, the pit 3.4 shown in FIG. 1 has a long dimension in the disk radial direction, for example, 5 microns, so in a circular spot of 0.4 micron, the vertically long pit 3.4 shown in FIG. I can't make it. Fourth
Figure (b) shows the principle for forming vertically long pits. In FIG. 4(a), the optical system is moved linearly in the radial direction of the disk of the photomask 13 on a moving table, but the moving speed is such that the distance 1, which is smaller than the diameter of the light spot in the time it takes for the photomask 13 to rotate once, is approximately the same as the light spot. It is best to control it so that it moves by an amount corresponding to the radius of . Then, as shown in FIG. 4(b), the integral value of the amount of light irradiated onto a desired portion of the photomask 13 becomes a uniform rectangle. Now, in order to form a vertical pit of 5 microns with a light spot diameter of 0.4 microns, the amount of movement of the optical system is 0.2 microns/rotation, and 510.2=25, that is, the photomask 13 must rotate 255 times. Light may be irradiated at desired timing. The mask 13 with the pattern recorded on the pins 1 shown in FIG. 1 is developed by the apparatus shown in FIG. 4, and a magnetic recording medium is produced by the process shown in FIG. 5, which is an embodiment of the present invention. In FIG. 5(a), a ferromagnetic film 5 is formed on a disk substrate 1 made of aluminum or glass, a positive resist 14 is applied thereon, and a photomask 13 is used for contact exposure. In FIG. 5(b), after exposing the positive resist 14, the resist in the pit portions is dissolved by TM and the image. Figure 5 (
In c), for example, the ferromagnetic film 5 in the pit portions is etched using the positive resist 14 as a mask by ion milling to remove the magnetic film 5 in the pit portions. After that, see Figure 5 (
As shown in d), the resist is removed using a plasma asher or an organic solvent. As explained above, by the method of manufacturing a magnetic recording medium shown in FIGS. 4 and 5, it is possible to create a magnetic recording medium that does not have a magnetic film only in the pit portion shown in FIG. 1. The method shown in FIGS. 4 and 5 can also form any pattern other than pits on the mask 13,
For example, if a straight groove is formed in advance, it is also possible to form a straight groove without a magnetic thin film on a magnetic recording medium. Effects of the Invention According to the present invention, it is possible to produce a large number of magnetic recording media that can track a magnetic head with high precision and have magnetically detectable tracking pits.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a magnetic recording medium according to the present invention, FIGS. 2 and 3 are diagrams for explaining the operation of detecting a tracking signal from the magnetic recording medium of FIG. 1 with a magnetic head, and FIG. 5 and 5 are diagrams for explaining an embodiment of the method for producing a magnetic recording medium according to the present invention. Figure 1 Figure 4 Disk radial laser Figure 5 Atsushi 2T2

Claims (1)

[Claims] 1. Prepare a mask having a desired pattern, expose the resist provided on the magnetic thin film through the mask, remove the resist corresponding to the pits, and use the resist as a mask. A method for producing a magnetic recording medium, comprising: removing the magnetic thin film corresponding to the pit, thereby producing a magnetic recording medium that does not have a magnetic thin film in a desired portion. 2. The desired pattern is a pattern formed by irradiating the mask with a substantially uniform amount of light by making the feed pitch of an optical system smaller than the diameter of the light spot on the mask. The manufacturing method according to claim 1. 3. The desired pattern is characterized in that a large number of tracking marks, each consisting of a pair of long pits in the radial direction of the disk, distributed left and right with respect to the track center line, are periodically provided along the track. Claim 1
Or the creation method described in 2.