JPS5938947A - Master disk for information storing medium - Google Patents

Abstract

PURPOSE:To obtain a master disk for information storing medium with which the signal information bits can be easily and quickly produced with high accuracy and high yield, by forming recessing and projecting parts on the surface of a substrate to obtain tracking guides and then irradiating partially the radiant energy to the surface of the tracking guide to obtain new recessing and projecting parts. CONSTITUTION:The 1st recessing/projecting part is formed by a diamond stylus to a glass substrate 1 having its polished surface, for example, with lambda/8 depth (lambda: wavelength of reading laser light). Then a photosensitive layer 3 of Cu, etc. is vapor-deposited on the surface of the 1st recessing/projecting part to obtain a master disk for information storing medium containing tracking guides 4. Then the master disk is used to form a photoresist layer 5 on the layer 3, and the laser light is condensed and irradiated by a lens 6 to trace the guide 4. At the same time, the laser light quantity is increased at a prescribed position to form an exposed part 7. Then a development is performd to remove the part 7 and expose the layer 3, and this exposed part is etched by using the layer 5 as a mask to form information signal pits 8. The remaining resist 5 is removed to complete the pits 8. Thus it is possible to produce a highly accurate master disk for information storing medium when necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a master disc for an information storage medium used when mass-producing an information storage medium in which at least information can be read using a focused laser beam.

[Technical background of the invention and its problems]

As an information storage medium, a compact disc (CD) used for a digital audio disc (DAD) is used.
A read-only information storage medium, such as an image file or computer output, that is in the form of a disc or tape, such as an optical video disc, and can read information using focused laser light. Memory (COM)
Information storage media for recording and playback that have the shape of a trap disk or tape and are capable of writing information to and reading information from a recording layer using a focused laser beam. Examples include erasable information storage media.

Such information storage media have narrow track pitches in order to increase the density of information. Therefore, in order to cause the optical head to follow a predetermined track during reading or writing, a tracking guide is provided in advance on the information storage medium. Furthermore, if the track number and sector position indicating the position where information is recorded are recorded in advance, it will be easier to use the recording/reproducing device. (
Tracking guide with preformatting).

The tracking guide and the signal information pit are formed by concavities and convexities, and the difference in the amount of light reflected therefrom can be read as information. Therefore, the tracking guide has a depth of 1, for example, λ/8 (λ is the wavelength of the reading laser beam. Below, the tracking guide is set to a depth of 1, for example, λ/8 (λ is the wavelength of the reading laser beam. Same), width is 0.6 to 0
．． It is a rectangular groove of about 8 txn. In addition, the signal information pits are designed to have the maximum modulation degree (when the reading laser beam is irradiated directly above the signal information pits, the intensity of the reflected light from there is the smallest).
The depth is set to λ/4 and the width is set to about 1/6 of the spot size of the reading laser beam.

By the way, in order to mass-produce the information storage medium as described above, a master disk for the information storage medium is prepared that is equipped with a tracking guide and signal information pits, which are conventionally formed by unevenness on the surface of the substrate, and Tracking guides and signal information pits were transferred through various processes.

However, when the content that should be recorded in advance is changed by the signal information pit, or when new information must be recorded one after another, such as on a digital audio disk (DAD), the tracking guide and the signal information pit are used. If a master disc for an information storage medium having both of the following was made each time, there was a problem in that it was not possible to quickly respond to changes in the information to be recorded due to the signal information pits. In addition, in conventional master discs, both the tracking guide and the signal information pits are formed together through a series of γ processes, so if the tracking guide is poorly formed, the process of forming the signal information pits may be delayed. There was a problem that the retainer was lowered.

[Purpose of emitting]

The present invention has been made based on the above circumstances, and is capable of forming signal information pits with high yield, and can easily and quickly cope with changes in information to be recorded using the signal information pits. It is an object of the present invention to provide a highly versatile master disc for an information storage medium that can be used in various ways.

[Summary of the invention]

In a master disk for manufacturing an information storage medium in which information can be read using a focused laser beam according to the present invention,
The tracking guide is characterized in that it is provided with a tracking guide formed with unevenness on the surface of the substrate, and that new unevenness can be formed on the surface by receiving at least partial irradiation with radiant energy.

[Embodiments of the invention]

The master disk for information storage medium of the present invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of an information storage medium master disc of the present invention. In FIG. 1, reference numeral 1 denotes a glass substrate 1 with a polished surface, and this substrate 1 is provided with first irregularities m2 formed in a spiral or concentric shape by, for example, a diamond needle. The depth of the first concavo-convex portion 2 is, for example, 700 A, and corresponds to λ cutting when the wavelength of the laser source for reading is λ. On the upper surface thereof, Cu is sputter-deposited or vacuum-deposited to a thickness of 700 J, for example, as a photosensitive layer 6 made of a photosensitive material. At this time, the surface of the photosensitive layer 6 has a shape that roughly follows the surface shape of the first uneven portion 2.
A tracking guide 4 having a depth of 700 A is formed on the surface thereof by l. Note that the surface of the photosensitive layer B on which the tracking guide 4 is formed has a trap so that new unevenness can be formed by receiving partial irradiation with radiant energy.

Next, the process of forming new irregularities on the surface of the information storage medium master shown in FIG. 1 to provide signal information pits will be described with reference to FIGS. 2(α) to 2(d).

First, as shown in FIG. 2(α)K, a photoresist layer 5 is formed by spinner coating the surface of a master for an information storage medium. Then, while the substrate 1 is placed on a tongue table and rotated, a laser beam focused by an objective lens 6 is irradiated onto the photoresist layer 5 on the tracking guide 4 to trace the photoresist layer. This tracing is performed by obtaining a track missing detection signal based on the diffraction pattern of the laser beam reflected from the tracking guide 4. Then, the amount of laser light is increased at a position where a signal information pit is to be provided in this trace to form a photoresist exposed portion 7 in the photoresist layer 5. Then, as shown in FIG. 2(h) K, the photoresist layer 5 is developed and fixed to expose the photoresist exposed area 7.
is removed to partially expose the photosensitive layer 3. Thereafter, the exposed portion of the photosensitive layer 3 is etched using the remaining photoresist layer 5 as a mask, and the etched portion is removed to form signal information pits 8 therein as shown in FIG. 2(C). It is preferable to use a ferric nitrate solution having a concentration of 55% as the etching solution at this time. after that,
By removing the photoresist layer 5 with an organic solvent, a depth of 1 is applied to the master disc for an information storage medium equipped with a tracking guide 4 having a depth of 700 A, as shown in FIG. 2(d).
400. (The signal information pit 8 will be formed.

In such master discs for information storage media, the process of forming signal information pits can be completely separated from the process of forming tracking guides, so even if the tracking guides are formed poorly, they can be discarded. By doing so, signal information bits can be formed with high yield. For the same reason, if you stock a large number of master discs for information storage media equipped with tracking guides as shown in Figure 1 in advance, pits for various signal information can be quickly formed on these master discs as needed. It is possible to make pressure. Furthermore, since the signal information pits are formed by optically tracing the tracking guide,
The feed mechanism of the objective lens that condenses the laser beam does not require high mechanical precision, and the manufacturing equipment for providing signal information pits can be made smaller and simpler. It can contribute to

A second embodiment of the master disk for information storage medium of the present invention will be described. FIG. 6 is a sectional view showing a second embodiment of the master disk for information storage medium of the present invention.

In FIG. 3, reference numeral 1 denotes a glass substrate with a polished surface, and on this substrate, Cu or Cr or the like is sputter-deposited or vacuum-deposited to a thickness of 700 Å as a photosensitive material M3 made of a photosensitive material. This photosensitive layer 3 has a depth of 700 Å consisting of concentric or circular grooves.
A tracking guide 4 is formed.

Here, a manufacturing method for obtaining the master disc for an information storage medium as described above will be explained. For example, as shown in FIG. 4(a), a photoresist layer 10 is formed by spin coating a negative type photoresist on a glass substrate 1 whose surface has been polished.

Then, the photoresist layer 10 is exposed in a concentric or circular pattern with a laser beam focused by an objective lens 11 to form a photoresist exposed portion 12. Thereafter, this photoresist layer 10 is developed and fixed, and the portions of the photoresist other than the exposed portions 12 are removed. And Figure 4 <
As shown in FIG. 1B, a photosensitive layer 6 is provided on the substrate 1 and the photoresist exposure portion 12 by vacuum evaporating or sputtering VcCr to a thickness of 700 Å. At this time, since the photosensitive layer 6 is thinner than the thickness of the photoresist exposed area 12, the photosensitive layer 6 is separated at the sides of the photoresist exposed area 12. Therefore, as shown in FIG. 3, when this photoresist exposed MS area 12 is dissolved with an organic solvent, the photosensitive layer 3 on the photoresist exposed area 12 is dissolved.
When the photoresist layer 3 is removed, the photosensitive layer 3 remains in contact with the substrate 1, and a tracking guide 4 is formed in the portion where the photoresist exposed portion 12 has been removed. Moreover, it can be manufactured by a method other than the above method. For example, although not shown, a photosensitive layer made of a photosensitive material such as CTL or Cr is formed on a glass substrate to a thickness of 700 mm.
A is sputter-deposited or vacuum-deposited, and a photoresist is spin-coated on the upper surface to form a photoresist layer. Thereafter, the photoresist layer is exposed in a spiral or concentric manner using a laser beam focused by an objective lens, and the exposed portion is removed after development and fixation. Using the photoresist layer from which the exposed areas have been removed as a mask, the exposed photosensitive layer is etched to a depth of 70 mm.
A tracking guide can be formed by removing at 0A.

Next, the process of forming new uneven portions on the surface of the information storage medium master shown in FIG. 6 to provide signal information bits will be explained with reference to FIGS. 5(α) to (d). do. First, as shown in FIG. 5 (α) and (13), explanation 1. In the same manner as above, the photoresist sheath light section 7 is removed to expose the substrate 1 from that section (detailed explanation is omitted). Then, using the remaining photoresist layer 5 as a mask, the substrate 1 emanating from it is etched to a depth of 700mm to form signal information bits 8 with a depth of 1400i (see FIG. 5(c)). ). The etchant used at this time was 60% hydrofluoric acid and 40% ammonium fluoride.
It is desirable to use a mixture of %. After that, by removing the photoresist layer 5 with an organic solvent,
As shown in FIG. 5(d), a master disc for an information storage medium equipped with a tracking guide 4 having a depth of 70 OA has a depth of 1400 OA.
4' signal information bit 8 is formed.

Even in the second embodiment, the same effects as in the first embodiment can be obtained.

Next, a fifth embodiment of the present invention will be explained.

FIG. 6 is a sectional view showing a sixth embodiment of the master disk for information storage medium of the present invention. In FIG. 6, reference numeral 1 denotes a glass substrate with a polished surface, and a photosensitive layer 6 made of a photosensitive material is coated with Alj and In.

A material softer than the substrate 1, such as Ph, Te, or FiZn, is sputter-deposited or vacuum-deposited to a thickness of 1400A0. The L-layer filter is provided with a tracking guide 4 formed in a spiral or concentric shape using, for example, a diamond needle. The tracking guide 4 has a V-shaped cross section in a direction perpendicular to the track and a depth of 1400.4 VC.

This depth is just an example, and corresponds to λ/4 where λ is the wavelength of the reading laser beam.

Such a master disk for an information storage medium undergoes the same process as described in the first embodiment to form new irregularities on its surface to a depth of 1400 mm. (Figure 7 (α), (
h)). Note that the tracking guide 4 provided in the information storage medium master disk described in this embodiment has a depth of λ.
/4, the cross-sectional shape in the direction perpendicular to the track is V
Needless to say, since it is in the shape of a letter, it is possible to obtain a large tracking detection signal due to the diffraction pattern of the reflected light when reading information, and stable tracking is possible.

Even in such a sixth embodiment, the same effects as in the first embodiment can be obtained.

It should be noted that the above-mentioned embodiment is merely an example, and it goes without saying that various modifications can be made within the scope of the present invention. For example, although the tracking guide described in each embodiment is a concave groove, it is also possible to form the tracking guide with a convex portion. Further, the tracking guide can also be provided directly on the substrate without using a photosensitive layer. Further, as a method for providing signal information bits on such an information storage medium master disc, it is possible to employ an appropriate method other than those described in the embodiments. By the way, an information storage medium having a tracking guide and a signal information bit can be manufactured by transferring the tracking guide and the signal information bit provided on the information storage medium master disk described in each embodiment. Although this is particularly difficult, it is also possible to form the tracking guide and the signal information bit so that the width of the cross section perpendicular to the direction of the three tracks Kf is narrower than that of the signal information bit. In particular, in information storage media manufactured using such master discs, the width of the tracking guide is wider than the width of the signal information bits, so when reading information, the outside of the tracking guide must be used. The amount of light reflected from inside the tracking guide is much larger than the amount of light reflected from inside the tracking guide. Therefore, it is possible to suppress the decrease in the light reflection intensity that was conventionally bundled due to the interference of the emitted light from both directions. As a result, the level of light reflection on the tracking guide increases,
It is possible to obtain a large difference in the light reflection level between the signal information pit and the part of the recording layer that stores other information, and to improve the SIN ratio for information reading and to obtain accurate information. Information can be read. In addition, when providing signal information bits on the master disc for the information storage medium of the present invention, if the signal information pits are formed on the tracking guide, stable tracking can be achieved when information is read from the signal information bits. It becomes possible to do it.

〔Effect of the invention〕

As is clear from the above description, in the master disc for information storage medium of the present invention, signal information bits can be formed with a high yield, and the signal information pits are resistant to changes in information to be recorded. It has excellent effects such as being able to deal with it easily and quickly.

Wisdom

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a first embodiment of a master disc for an information storage medium of the present invention, and FIGS. 2(a) to (d) show the steps of forming signal information bits on the master disc for an information storage medium. A cross-sectional view showing,
6 is a sectional view showing a second embodiment of the master for information storage medium of the present invention; FIG. Figure 5 (α) ~ (
d) is a cross-sectional view showing the process of forming signal information bits on the master disk for information storage medium, FIG. 6 is a cross-sectional view showing the sixth embodiment of the master disk for information storage medium of the present invention, and FIG. α),
(h) is a sectional view showing a process of forming signal information pits on the master disc for the information storage medium. 1... Board, 4... Tracking guide,
8...Signal information pit. 2-,,-' Figure 5

Claims (2)

[Claims] (1) A master disk for manufacturing an information storage medium from which information can be read by a focused laser beam, which is equipped with a tracking guide formed with unevenness on the surface of the substrate, and whose surface is at least emissive. A master disc for an information storage medium, characterized in that new uneven parts can be formed by receiving partial irradiation with energy. (2) The master disk for an information storage medium according to claim 1, wherein the tracking guide is formed via a photosensitive layer provided on the surface of the substrate.