JPS60247843A - Manufacture of information recording medium disk - Google Patents

Abstract

PURPOSE:To form exactly grooves having a uniform and shallow depth by determining such a beam quantity at which a photoresist layer can be exposed over the entire thickness thereof as the central value of the intensity thereof the changing the beam quantity so as to change the groove width according to an information signal. CONSTITUTION:As for the quantity of the laser beam to be irradiated from an optical system 5 to the photoresist layer Da of an information recording medium disk D, such a laser beam quantity Ic at which the layer Da coated on the disk K can be exposed over the entire part of the thickness to thereof (the quantity Ic of the light which is the central value of the laser beam quantity of the intensity changed according to the information signal) is determined as the quantity of the laser beam to be irradiated from the optical system 5 facing the part 9 shown by the groove width W in the guide groove 9 for generating a tracking reference signal. The laser beam quantity is changed variously like Ih, Il with the quantity Ic as a central value. The width of the groove 9 is thus changed like Wa, Wb.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to both the recording of an information signal to the recording layer of an information recording medium disc and the reproduction of an information signal from the recording layer of an information recording medium disc. Information such that a guide groove for generating a tracking reference signal used in a tracking control operation to be performed on one or both of them is configured in advance so that the groove width thereof is changed by another information signal. Concerning a method of manufacturing a recording medium disc.

(Prior Art) In recent years, as the demand for high-density recording and reproduction of information signals has increased in various technical fields, attempts have been made to record and reproduce information signals at high density using various types of information recording media. .

Now, ferromagnetic media has traditionally been used as an information recording medium on which information signals can be easily recorded and reproduced, and the recorded information signals can also be easily erased and the information signals re-recorded (re-written). Magnetic recording media with a general structure equipped with a recording layer made of materials have been known, but recently, information recording media that can be recorded, reproduced, and rewritable have been developed by applying electromagnetic waves, electric fields, and heating. By doing such things as
Materials in which a phase change occurs from an amorphous state to a crystalline state, or from a crystalline state to an amorphous state, e.g.
An information recording medium in which a recording layer made of TeOx, Ge, S n) is formed on a substrate, or a magnetic thin film (for example, M n B i, MnCuB
1. , a magnetic thin film made of a substance such as GdCo) is used on an information recording medium on a substrate.
Attempts have been made to record and reproduce information signals at a much higher recording density than the recording and reproduction of information signals performed using conventional general magnetic recording media.

Incidentally, in order to successfully perform high-density recording and reproduction of information signals, the interval between recording traces (track pitch) must be made narrow, but when the track pitch is made narrow, the recording element, the reproduction element, or Since it is difficult to cause the recording/reproducing element to accurately track the recording trace on the information recording medium, attempts have been made to solve this problem by applying various tracking control means. However, as recording density becomes even more sophisticated, extremely high mechanical precision is required for the recording mechanism in order to prevent overlapping recording traces during recording, which makes the device significantly more expensive. The problem is that it becomes.

As a means to solve the above-mentioned problems, conventionally, for example, special As disclosed in Japanese Patent Publication No. 58-57643, this may be carried out either when recording an information signal on the recording layer of an information recording medium disk, or when reproducing an information signal from the recording layer, or both. Conventionally, a guide groove for generating a tracking reference signal used in a tracking control operation to be performed is formed in advance on an information recording medium disc.

As described above, the guide groove for generating the tracking reference signal in the information recording medium disc, in which the guide groove for generating the tracking reference signal is pre-strengthened, can be used as the guide groove for generating the tracking reference signal. If it is used only for the purpose of this purpose, it is sufficient to have a certain groove iJ and depth, but by using the guide groove portion for generating the tracking reference signal described above, other grooves may be placed therein. information signals, such as address signals, speed control signals,
Other necessary signals are fixed in advance (non-erasable mode)
It has also been conventional practice to have the information recorded in the

If you want to use the guide groove for tracking reference signal generation to record other information signals in a fixed manner, it is possible to record other information signals in a fixed manner. The embodiment was such that, for example, the depth of the guide groove for generating the 1-racking reference signal was varied depending on other information signals to be recorded therein.

By the way, a recording layer that can perform recording, reproduction, and erasing, can be rerecorded (rewritten), and can record information signals at a high recording density (for example, a phase change from an amorphous state to a crystalline state, Alternatively, a recording layer made of a material that undergoes a phase change from a crystalline state to an amorphous state (TeOx, Ge, Sn), or thermomagnetic recording such as so-called cue point temperature recording or guaranteed temperature recording. A recording layer of a magnetic thin film (for example, a magnetic thin film made of a substance such as MnB1.MnCuB1.GdCo) that is to be recorded on the recording layer of an information recording medium disc, which is to be recorded and reproduced. The difference between the light reflectance at the part corresponding to "j" and the light reflectance at the part corresponding to "0" of the seven-wheel signal is as low as 25% at most. Although it is a thing, on the other hand,
As described above, in the information recording medium disc in which the guide groove for generating the tracking reference signal is formed in advance, other information signals such as address signals and speed control signals are inserted into the guide groove for generating the tracking reference signal. , and other required numbers are recorded in advance in a fixed (non-erasable manner) at different depths. The signal level of the dragging reference signal to be generated and the signal level of the reproduction signal based on the other information signal recorded in the guide groove for generating the racking reference signal are determined by the recording and reproduction signal level recorded on the recording layer. The problem has been that the signal level tends to be higher than the signal level of the information signal being targeted.

In order to solve the above-mentioned problems, the degree of modulation of the reproduced signal modulated by the guide groove for generating the tracking reference signal may be set to about 10%, for example. However, in the conventional method, it is necessary to reduce the modulation degree by reducing the depth of the guide groove for generating the tracking reference signal by tJs. The problem has been that it is extremely difficult to form them accurately.

Therefore, the present applicant company has developed an information recording medium disk which is free from the defects in the conventional information recording medium disk as described above, when recording an information signal on the recording layer of the information recording medium disk.
A guide groove for generating a tracking reference signal used in a tracking control operation to be performed in either or both of the reproduction of the information signal from the recording layer of the information recording medium disc is configured in advance. In the information recording medium disk, the width of the groove is changed by an information signal to be recorded in advance on the information recording medium disk as a guide groove for generating the tracking reference signal, which is formed in advance on the information recording medium disk. By using a guide groove that is in a state of The modulation degree of the reproduced signal due to another information signal to be fixedly recorded on the information recording medium disc is obtained as the difference between the modulation degrees determined in correspondence with the groove width. To provide an information recording medium disk in which the amount of change in a groove 111 of a guide groove for generating a tracking reference signal based on another information signal to be fixedly recorded on the disk can be arbitrarily determined according to the setting method. This made it possible to easily solve the above-mentioned problems.

(Problems to be Solved by the Invention) However, the above-mentioned information recording medium disk proposed by the applicant's company has an information signal that should be fixedly recorded in advance on the information recording medium disk. It is necessary to form a guide groove for generating a tracking reference signal in a state where the tracking reference signal is changed to have a substantially constant depth, but in the conventional manufacturing method of an information recording medium disk,
The difficulty of constantly and stably manufacturing information recording medium discs with such a configuration has become a problem, and a solution has been sought.

(Means for Solving the Problems) The present invention records information signals such that the groove width of a spiral or concentric groove having a substantially constant depth is changed in accordance with the information signal. A method of manufacturing an information recording medium disk as described above, comprising means for coating a substrate with a photoresist layer having a thickness corresponding to the depth of a spiral or concentric groove to be formed on the information recording medium disk; A shape corresponding to the spiral or concentric groove shape to be formed on the information recording medium disk; means for relatively moving the information recording medium disk and the laser beam so that a trajectory is drawn by the laser beam; The intensity of the laser beam is set at a central value that can expose the entire thickness of the photoresist layer in the spiral or concentric groove-shaped portion to be formed on the information recording medium disc, and the intensity of the laser beam is set at a central value such that the entire thickness of the photoresist layer is exposed in the spiral or concentric groove-shaped portion to be formed on the information recording medium disk. The present invention provides a method for manufacturing an information recording medium disk comprising means for changing the beam amount so that the groove 1 changes.

(Example) Hereinafter, with reference to the accompanying drawings, specific details of the method for manufacturing an information recording medium disk of the present invention will be described in detail.

FIG. 1 is a block diagram showing a schematic configuration of an information signal recording device used when manufacturing an information recording medium disk by applying the method for manufacturing an information recording medium disk of the present invention.
In the figure, 1 is a laser light source, 2 is a light modulation system, 3 is a signal source, 4 is a reflecting mirror, 5 is an optical system, D is an information recording medium disk,
6 is a turntable, 7 is a motor, and a laser beam FA
The laser beam emitted from I is intensity-modulated in the optical modulation system 2 by a signal supplied from the signal source 3 to the optical modulation system 2, and is then applied to the optical system 5 via the reflecting mirror 4.

In the optical system 5 described above, as illustrated in FIG. 2, for example, the groove 11 is changed by another information signal, so that the guide groove 9 for generating a tracking reference signal has a predetermined planar shape. The photoresist layer Da of the information recording medium disk (1-) is irradiated with a laser beam having a cross-sectional shape that can form the information recording medium at IB and D in the information recording medium.

One information recording medium disc is fixed to a turntable 6 which is driven and rotated by a motor 7 at a predetermined number of revolutions, and an optical system 5 moves the information recording medium disc by a transport mechanism 8. By being moved in a predetermined manner in the radial direction, the photoresist layer Da on the information recording medium disc is exposed in a spiral or concentric pattern by the laser beam emitted from the optical system 5 described above. It is done.

The laser beam applied from the optical system 5 to the photoresist layer Da of the information recording medium disk has a substantially constant depth in the information recording medium disk and generates a tracking reference signal of a predetermined planar shape. It is designed to have a strength as described below so that the guide groove 9 for use can be formed.

FIG. 2 shows an example of the planar shape of a guide groove for generating a tracking reference signal formed in an information recording medium disk manufactured by the method of manufacturing an information recording medium disk of the present invention. FIG. 2 is a plan view of a part of the guide groove (the cross section of the groove is trapezoidal).

In FIGS. 2(a) to 2(c), D is an information recording medium disc, and 9 is a guide groove for generating a tracking reference signal provided in the information recording medium disc.

In FIGS. 2(a) to 2(c), in order to avoid the complexity of illustration, a guide groove 9 for generating a tracking reference signal is shown.
Although only one tree is shown for each, in an actual information recording medium disk, a large number of guide grooves for generating tracking reference signals are arranged in parallel on the surface at predetermined recording trace intervals. It goes without saying that there is.

In (a) to (c) of FIG. 2, the portion of the guide groove 9 for generating the tracking reference signal whose groove width is indicated as W is the original groove width of the guide groove for generating the tracking reference signal. , and (a) in Figure 2 and (
c) and the part 9a of the groove rl'l W a and the second
The portion 9b of the groove width wb in FIG. 2A and FIG. 2 shows a portion that is fixedly recorded but is modulated by another information signal to vary wide and narrow.

However, even in the portions 9, 9a, 9b having different groove widths such as W, Wp, and Wb, the groove depths of the portions 9.9a, 9b are approximately the same.

In FIG. 2(a), the original groove 11 is used to generate the original tracking reference signal by using another information signal to be fixedly recorded on the information recording medium disk. This is an example of a case where the groove width Wa is wider than the groove width W of the guide groove for use, and
FIG. 2(b) shows that the original groove [1] is used to convert the guide groove 9 for generating the tracking reference signal of W into the original tracking reference signal by using another information signal to be fixedly recorded on the information recording medium disc. This is an example in which the groove rllWb is modulated to be narrower than the groove width W of the guide groove for signal generation.
Furthermore, FIG. 2(c) shows that the guide groove 9 for generating the tracking reference signal, which has an original groove width of W, is formed by a first other information signal to be fixedly recorded on the information recording medium disc.
The groove width Wa of the guide groove for generating the original tracking reference signal is modulated to be wider than the groove width W of the guide groove for generating the tracking reference signal, and the guide groove 9 for generating the tracking reference signal whose original groove width is W is changed to the information recording medium disk. This is an example of a case where the groove width wb is modulated by a second other information signal to be fixedly recorded in the groove width Wb, which is narrower than the groove width W of the guide groove for generating the original tracking reference signal.

As shown on each side shown in Fig. 2 (a) to (C), the original groove 11 is W for generating a tracking reference signal, and the guide groove 9 is inserted into the information recording medium disk with its depth unchanged. By using other information signals to be recorded in a fixed manner, the groove width may be modulated so that the groove width Wa becomes wider than the groove width of the guide groove for generating the original tracking reference signal + 11W, or the groove width may be changed to generate the original tracking reference signal. When the groove width is modulated so that the groove width Wb is narrower than the groove rlJW of the guide groove for use, a state is obtained in which the degree of modulation changes in accordance with the change in the groove width.

In the information recording medium disc described above, the guide groove 9 for generating the tracking reference signal is formed on the substrate of the information recording medium disc in which a groove having a predetermined cross-sectional shape such as a trapezoid is formed. On top of that, there is a recording layer (for example, a recording layer that can record, reproduce, and erase data, rewrite data, and record information signals at high recording density) materials that undergo a phase change or a phase change from a crystalline state to an amorphous state;
(TcOx, G'e, Sn), or a magnetic thin film (for example, Mn) on which thermomagnetic recording such as cue point temperature recording or guaranteed temperature recording is to be performed
B1. MnCuB1. In the state in which a recording layer (a magnetic thin film made of a substance such as GclCo) is applied, it can be used as a guide groove for generating a tracking reference signal on the disk surface of an information recording medium (hereinafter referred to as The term "information recording medium disk" refers to an information recording medium disk that is completed by coating a recording layer on a substrate on which a guide groove for generating a tracking reference signal is formed, and an information recording medium disk that is completed by covering a substrate with a guide groove for generating a tracking reference signal on the substrate. (Used to refer to information recording medium disks that are intermediate products that have been formed, as well as master disks (base disks) of information recording medium disks that have photoresist layers adhered to substrates.)

Now, the intensity of the laser beam irradiated from the optical system 5 to the photoresist layer Da of the information recording medium disc corresponds to the planar shape of the guide groove 9 for generating a tracking reference signal to be formed on the information recording medium disc. The planar shape of the guide groove 9 for generating the tracking reference signal to be formed on the information recording medium disk is, for example, as shown in FIG. 2. If it is as shown in (c), the laser beam that should be irradiated from the optical system 5 to the photoresist layer Da of the information recording medium disc will have a change in intensity on the time axis. This is done as shown in FIG.

In Figure 3, the horizontal axis is time and the vertical axis is information recording medium disk I.
] is the light intensity of the laser beam to be irradiated from the optical system 5 onto the photoresist layer Da, and the symbol Ic on the vertical axis indicates the groove width in the guide groove 9 for generating the tracking reference signal shown in FIG. The amount of light of the laser beam to be irradiated from the optical system 5 corresponding to the portion 9 indicated by W (photoresist layer D coated on the information recording medium disk)
The central value of the laser beam amount is such that the intensity can be changed according to the information signal, and the intensity is changed according to the information signal, with the amount of laser beam that can expose the entire thickness of the laser beam. The symbol Ih on the vertical axis in FIG. 3 indicates the guide groove for generating the tracking reference signal shown in FIG. 2. 9 indicates the amount of laser beam to be irradiated from the optical system 5 corresponding to the portion 9a whose groove width is indicated by Wa, and furthermore, the symbol TI on the vertical axis in FIG. 3 is as shown in FIG. In the illustrated guide groove 9 for generating a tracking reference signal, groove 1] corresponds to a portion 9b indicated by wb, and indicates the amount of laser beam to be irradiated from the optical system 5.

By the way, the relationship between the depth of the guide groove 9 for generating a tracking reference signal formed in the photoresist layer Da having a thickness of to through the exposure process and the development process and the exposure amount is shown in FIG. In the characteristic diagram shown in FIG. 4, when the exposure amount is I, a photoresist layer Dn with a thickness of to is used for generating a tracking reference signal with a depth of to. It is shown that a guide groove is formed therein.

FIG. 5 is a characteristic diagram in which the horizontal axis represents the exposure amount and the vertical axis represents the width of the groove obtained by the development process. As shown, when the exposure amount is around Io or more, the amount of change in the groove width with respect to the change in the exposure amount decreases, and the slope of the characteristic curve becomes gentle.

The exposure amount Io at which the slope of the curve in the characteristic curve shown in FIG. When the photoresist layer Da is exposed with an exposure amount near Io, an information recording medium disk can be stably manufactured. Note that It in FIG. 5 is the exposure amount adjustment shown in FIG. 4 described above.

In the method for manufacturing an information recording medium disc of the present invention, the intensity of the laser beam irradiated from the optical system 5 to the photoresist layer Da of the information recording medium disc is used for generating a tracking reference signal to be formed on the information recording medium disc. As described above, the optical system 5 is placed in the photoresist layer Da of the information recording medium disc in a state that changes on the time axis in correspondence with the planar shape of the guide groove 9. The amount of laser beam that should be irradiated from the optical system 5 is as follows: , a laser beam amount Ic that can expose the entire thickness to of the photoresist layer Da coated on the information recording medium disk (light amount Ic at the center value of the laser beam amount whose intensity is changed according to the information signal) ), and by changing the laser beam amount as Th and IQ with this central value of the laser beam amount Tc as the center value, the groove width of the guide groove 9 for generating the tracking reference signal can be set as Wa and Wb. It can be done so that it can be changed into. In this case, the center value Ic of the laser beam amount described above is set to a value near the exposure amount Io described above, that is, the exposure amount Io (4 When the exposure amount Ic is set to a value close to the exposure amount IO, a more stable recording operation can be performed than when the exposure amount Ic is set to a value other than the exposure amount IO.

In carrying out the method for manufacturing the information recording medium disk of the present invention, the thickness of the photoresist layer Da of the information recording medium disk is set to, and the photoresist layer Da having the thickness to is shown in FIG. As shown, It < I Q < Io
It is a desirable embodiment to perform exposure with a laser beam of a size that satisfies the relationship: =Ic<Ih.

In addition, when the information recording medium disc is used while being rotated at a constant angular velocity, it is also a desirable embodiment to apply so-called radial convention to the exposure amount during recording.

(Effects) As is clear from the detailed explanation, the method for manufacturing an information recording medium disk of the present invention is such that the groove width of the spiral or concentric groove having a substantially constant depth is A method of manufacturing an information recording medium disk in which an information signal is recorded in a manner that varies according to the information signal, and the method corresponds to the depth of spiral or concentric grooves to be formed on the information recording medium disk. means for applying a photoresist layer of a certain thickness onto a substrate; means for relatively moving the laser beam and the laser beam, and the laser beam exposes the entire thickness of the photoresist layer in the spiral or concentric groove-shaped portion to be formed on the information recording medium disk. The central value of the intensity is set to a beam amount that can be adjusted to a certain level, and means for changing the beam amount so that the width of the groove changes according to the information signal. a guide groove for generating the desired tracking reference signal;
In other words, it is possible to easily configure a tracking reference (a guide groove for generating number a) whose groove width is changed by another information signal, and also to determine the center value Ic of the exposure amount.

By setting the characteristic curve near the exposure Jt I o where the slope of the characteristic curve indicating the relationship between the exposure amount and groove rl starts to become gentle, it is possible to stably configure the guide groove for generating the tracking reference signal. Since the depth of the guide groove for generating the reference signal is a constant depth 1o, the 1-racking error signal output can be stably obtained, and the recording groove covered in the guide groove for generating the tracking reference signal can be stably obtained. The recording, erasing, and reproducing operations of information signals on the B layer can also be performed stably, and all the problems of the conventional method can be solved satisfactorily by using the method of manufacturing the information recording medium disc of the present invention.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a recording device that implements the method for manufacturing an information recording medium disc of the present invention, FIG. 2 is a plan view of a guide groove for generating a tracking reference signal, and FIG. 3 is a diagram showing a recording device during recording. FIG. 4 is a diagram showing the relationship between the exposure amount and the depth of the guide groove for generating the tracking reference signal, and FIG. 5 is a diagram showing the relationship between the exposure amount and the depth of the guide groove for generating the tracking reference signal. ] FIG. DESCRIPTION OF SYMBOLS 1... Laser light source, 2... Light modulation system, 3... Signal source, 4... Reflector, 5... Optical system, 6... Turntable, 7... Motor, 8 ...transport mechanism, 9...
・Guide groove for tracking reference signal generation, time closing - Rako 3 work 40 brother 5 mouth

Claims (1)

[Claims] A method for manufacturing an information recording medium disc in which an information signal is recorded by changing the width of a spiral or concentric groove having a substantially constant depth in accordance with the information signal, the method comprising: Means for coating a photoresist layer on a substrate with a thickness corresponding to the depth of the spiral or concentric grooves to be formed on the information recording medium disk; The shape corresponds to the groove shape! means for relatively moving the information recording medium disk and the laser beam so that a trajectory is drawn by the norther beam, and the laser beam having a spiral or concentric groove shape to be formed on the information recording medium disk; means for setting the intensity of the beam at a central value such that the photoresist layer can be exposed over the entire thickness of the photoresist layer, and changing the beam amount so that the groove width changes in accordance with the information signal. How to make a recording medium disc