JPH0447912B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field of the Invention> The present invention relates to an improvement in manufacturing an optical memory element that performs at least one operation of recording, reproducing, and erasing information by irradiation with a light beam. This invention relates to an improvement of a mask used for forming guide tracks, track addresses, etc. of an optical memory element.

<Technical background of the invention and its problems> In recent years, optical memory devices have attracted attention as high-density, large-capacity memory devices. This optical memory device can be divided into three types depending on its usage: read-only memory, additionally recordable memory, and rewritable memory.

Among these, in the case of an optical memory element used as an additional recordable memory or a rewritable memory, a guide track or a track number part, etc. are used to guide the light beam spot for recording and reproducing information to a predetermined position on the optical memory element. Usually equipped.
In particular, when the optical memory element is an optical disk as shown in FIG. 3, a guide track 3 and a track number part 2 (if the track is divided into many sectors, sector addresses are also formed in the same way) are formed concentrically on the substrate 1. Or it is formed in a spiral shape. In FIG. 3, only one track 3 and one address 2 are shown for simplicity.

Now, there are various methods of manufacturing disk substrates equipped with these tracks and addresses, but for example, as described in Japanese Patent Application No. 59-51977, a resist material is applied to a glass disk, and guide tracks and addresses are entered. In the method of directly forming tracks and addresses in the form of grooves and pits on the glass disk by dry or wet etching after exposing the resist material to light and developing the resist material, the center of the guide track and the glass disk are It is necessary to match the center of the center hole as much as possible. If the concentricity between the guide track and the center hole of the glass disc is poor, record it as shown in Figure 4.
During reproduction and erasing, the center hole of the glass is fixed to the rotating shaft 4, and when the glass disk is rotated, the guide track swings around greatly relative to the laser beam 5 for recording, reproduction, and erasing, so the position of the lens is controlled. Track servo has become difficult. From the above points, the concentricity of the guide track and the center hole of the glass disk should be maintained accurately (preferably within 20 μm) during guide track exposure.
It is necessary to match.

<Object of the Invention> The present invention provides a mask that facilitates alignment of the center of a disk hole and the center of a track when transferring guide tracks and address areas to a resist film coated on a disk. With the goal.

<Embodiments of the Invention> Examples of the mask for manufacturing an optical memory element according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan view of an embodiment of a mask for an optical disk substrate according to the present invention. For example, this mask forms a film of Cr or CrO on a quartz glass disk, and
A mask is formed by etching Cr or CrO so that the pattern shown in the figure remains. The shaded area in the figure is the area where Cr and CrO remain. The area a is an information area, and a track 3 and an address 2 are formed in a spiral or concentric circle in a part of this area. Inside the mask, there is a portion b where Cr or CrO is removed, and a reference marker C for positioning is provided at one location within the region b. If this reference marker C is recorded using the same recording device when recording the mask guide track, the concentricity with the track portion can be compensated. For example, if the diameter of marker C is made approximately equal to the diameter of the center hole of the glass disk shown in Fig. 3, when a pattern is transferred to the glass disk using a mask, it will be easier to match the center hole of the disk with this marker C. The center of the disk hole and the center of the track can be aligned.

Incidentally, the markers are not necessarily limited to the above embodiments, and for example, two markers C may be provided as shown in FIG. 2, and the interval between them may be, for example, 10 to 20 μm, and the diameter may be such that the center hole of the glass disk can fit between them. .
In other words, if the diameter of the center hole of the glass disk is 15 mm, the diameter of one marker C is 14.09 mm, and the diameter of the other marker C is 15.01 mm, making it easy to align with the center hole of the glass disk. . Normally, the center hole of a glass disk has good roundness, but the diameter varies depending on the manufacturing process, so for example, 15 ± 0.5 mm.
It often has a width such as . At that time, marker C
By providing a plurality of disks and changing their diameters little by little so as to form concentric circles, one mask can conveniently accommodate disks with different center hole diameters. It is also possible to erase c in FIG. 1 and shorten the area b to use the part b as a marker. Furthermore, in the above example, the shaded area was made of Cr or CrO film, but
Of course, other metal films such as Ni, Ti, Ta, etc. may also be used.

<Effects of the Invention> As described above, by using the mask of the present invention, the concentricity between the guide track and the center hole of the optical disk substrate can be improved, and the whirling of the guide track can be improved when recording, reproducing, or erasing information. This has the advantage that the servo of the objective lens that condenses the laser beam becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a plan view of one embodiment of an optical disk mask according to the present invention, FIG. 2 is a partial plan view of another embodiment, FIG. 3 is a perspective view of an optical disk, and FIG. 4 is a plan view of an optical disk mask. A partial cross-sectional view of the device is shown. In the figure, 1...board, 2...address, 3...track, 4...rotation axis, 5...laser light.

Claims (1)

[Scope of Claims] 1. A resist material is applied to a glass disk having a center hole, an optical disk substrate mask on which a pattern such as a guide track is recorded is closely attached, exposed to light, developed, and then etched. Accordingly, in a mask for an optical disk substrate for obtaining an optical disk substrate by forming a guide track or the like directly on the glass disk, the hole has approximately the same radius as the center hole of the glass disk;
A mask for an optical disk substrate, further comprising a marker concentric with a pattern such as the guide track.