JPS59157850A - Production of original disk for optical disk - Google Patents

Abstract

PURPOSE:To form a projected part of the uniform height by irradiating a detecting energy beam and an energy beam forming the projected part to a material film on a substrate and controlling the beam so as to obtain the fixed height of the projected part in response to the intensity of beam reflection. CONSTITUTION:A substrate 1 containing a material film 2 is fixed on a turntable 3 and revolved toward an arrow 5. The laser light outputted from a laser oscillator 6 is condensed on the material film 2 via a mirror 7 and a lens 8 which move in a body in the radius direction of the substrate 1. Thus a continuous spiral projected part 25 is formed on the film 2. While the laser light sent from a laser oscillator 10 is irradiated on the part 25 via a half mirror 11 and a lens 12, and the reflected light is reflected by the mirror 11 and made incident to a photodetector 14. The output of the detector 14 is supplied to a control circuit 15, and the forming state of the part 25 is decided from the reflecting intensity. Then the oscillator 6 is controlled to secure a fixed height of the part 25.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for manufacturing a master disc for manufacturing an optical disc, and in particular to a method for converting a material to form convex portions by irradiation with an energy beam such as a laser beam. The present invention relates to a method of manufacturing a master disc having the following.

[Technical background of the invention and its problems]

For writable optical discs, that is, disc-shaped optical information recording media in which information signals are inserted and read by laser beam irradiation, it is necessary to increase recording density (track density) for stable tracking. Therefore, media in which continuous spiral convex hGx or concave portions that can be optically discerned on the recording layer are formed on the substrate (disc cutting board) of the medium are often used.

Conventionally, a disk substrate on which continuous spiral-shaped protrusions or recesses are formed is produced by transferring the protrusions or recesses from a disk by a method such as electroforming. This stamper is used to transfer the convex portions and concave portions onto the disk substrate by injection molding, compression molding, casting, or other methods.

On the other hand, a master disc having concave portions or convex portions is generally manufactured by the following method. That is, a Cr film is deposited on a flat substrate such as glass, and a photoresist is applied thereon using a spinner. Next, while rotating this board,
By irradiating the photoresist with a laser beam focused to about mφ while moving the photoresist in the radial direction of the substrate at a predetermined feed rate, a continuous spiral pattern is formed. Then, further development and baking are performed to obtain a master disc.

However, with this master manufacturing method, it is difficult to form convex portions or four portions with a uniform shape over the entire surface of the substrate. The shape of the convex part or concave part to be formed on the substrate, taking the convex part as an example, has a height of about 800 OA, which is the wavelength of the semiconductor laser normally used, in order to enable stable tracking.
It is necessary to have a width of about 100 OA, which is 1/8 of the diameter, and a culm of 1 μm. In addition, the size of the bottom plate needs to be about 300 Inφ or more in view of the capacity of 2 sickles. However, the spinner coating method is a technique that is normally used for coating films with a thickness of 1 to 2 μm or more, and it is difficult to form a uniform coating film of 100X on the entire surface of a large-area substrate such as 306φ using this method. It is extremely difficult and partial peeling is unavoidable. Furthermore, even a small amount of dust in the atmosphere on the substrate surface causes serious coating unevenness. Also,
It is also extremely difficult to uniformly develop such thin photoresist over the entire area. Therefore, it is very difficult to fabricate an original structure in which the continuous spiral protrusions or four parts of the tracking stop are well formed using the photoresist method using spinner coating. 1 It was an impossible goal.

In order to solve the drawbacks of the master disk manufacturing method using the photoresist method, the inventors proposed a method of absorbing engineering energy and forming convex portions by irradiating the substrate with an energy beam such as a laser beam; We are proposing a master material made by replacing the photoresist with a photoresist. In this case, the material film can be formed using a film forming technique such as photoresist coating, sputtering, or vapor deposition, which is different from that of photoresist applied by a spinner, so there is no contamination with impurities or peeling. , it is possible to form a film with a relatively uniform thickness. Therefore, such master material.

If used, it is easy to form convex portions of uniform shape by laser beam irradiation.

By the way, although the film thickness of the material film in this master material is made uniform, for example, the film thickness is slightly different between the central part and the peripheral part of the substrate. It has been found that when there is such slight non-uniformity in the film thickness, the height of the convex portions formed by laser beam irradiation also becomes non-uniform.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing an optical disc master in which convex portions of uniform height can be formed by irradiation with an energy beam.

[Summary of the invention]

In this invention, a first energy beam for forming a convex portion is irradiated onto a material film formed on a substrate to form a convex portion by irradiation with a thousand energy beam, and a second energy beam is applied to the convex portion. The beam is irradiated and the state of convex formation is determined based on the reflected intensity, and the determination result is fed back to the first energy beam to control the energy so that the sieve of the convex portion is constant. It is characterized by

〔Effect of the invention〕

According to this invention, even if the thickness of the material film forming the convex portion is slightly uneven due to energy beam irradiation, the height of the convex portion can be kept constant.

Another great advantage is that the feedback control for constant height of the convex portion in the present invention can be performed in places without special restrictions, such as bright places in the atmosphere, when laser beam mura is used. For example, in the conventional master manufacturing process using the photoresist method, it is necessary to measure the thickness of the resist after it is formed, and if the film thickness is inappropriate, it must be peeled off and the resist is coated again. It is a series of wet processes such as treatment and cleaning. The present invention does not require any of these complicated processes.

[Embodiments of the invention]

FIG. 1 is a block diagram of a master manufacturing apparatus to which the present invention is applied. In the figure, 1 is the master board, for example 300
A glass plate of φ is used. This substrate 1 has one side finished smooth, and a material film 2 forming convex portions is formed on the smooth surface by irradiation with an energy beam, for example, a laser beam.

material? 11J2 is, for example, as shown in FIG. 2(a), the 11th accumulation 21 as an adhesion layer consisting of a fallen metal thin film or oxide thin film with good adhesion to the substrate 1, and the energy absorption and gas release properties. The third razs is made of a thin metal film with good properties.
and a fourth layer made of a metal thin film with good mold releasability from resin.
It has a 41-unit structure in which layers 24 are formed in sequence.

The metal thin film of the first layer 2J is T, i, Cre
k, l.

Mfr W + ”Or COr Ni r Fe
A film containing at least one of I'ra f v and 'z r + "f is suitable, and can be deposited on the substrate 1 by a conventional thin film forming method such as sputtering or vacuum evaporation. As an oxide thin film, For example, SiO2,T
eO2 etc. can be used. The 21st product that has energy absorption and gas release properties at the same time! The thin film 22 is made of, for example, Te.

A target of a low melting point metal such as B1 having a melting point below 600° C. is deposited by sputtering with plasma of a gas such as CH4+ NHs r H2r Co. - For example, Te target is CH,
Thickness 400mm formed by sputtering with gas plasma
A thin film with a component ratio of 0A Te50 C110H20 is
It has an absorption rate of 4゜1/2 for the wavelength of 8300X,
If an egg is heated to 150 degrees Celsius or higher in the air, it will release gas with a heavy weight loss of 30 degrees.

The metal thin film of 31st Emperor 23 contains Cr, T 1+ M
'□ t l'f' +At least one of Fe, Co, and Ni can be used. 4th again! @,? 4
The metal thin film contains A, u.

At least one type of Af r Pd HN 1 can be used.

The purpose of forming No. 1121 is to prevent the second layer 22 from peeling off from the substrate 1 and destroying the master when molding the optical disk substrate and when separating this substrate from the master (stamper) after molding. be. A desirable metal thin film for the first layer 2I is one that has good adhesion to the substrate I such as glass.
Tl,Cr tAI! ＋”t r W rMo *
cOr Ni r Fer Ta rV, Zr,
Hf is suitable.

The purpose of forming the third layer 23 is, firstly, to form continuous or discontinuous spiral convex portions with an excellent shape, and secondly, to avoid damage to the second layer 22 when forming the disk substrate. This is to prevent No. 3423 like this
A desirable metal thin film has good adhesion to No. 2422,
High hardness, Cr t, T i HuOI
W r COr ' l rFe is suitable.

The fourth ff124 can be made of polymethylacrylmide, polycarbonate, or other materials that have low adhesion to organic resins. Particularly desirable is Au r A
? It is HPd.

When the film 2 of such a material is continuously or discontinuously irradiated with a laser beam, for example, the material film 2 is locally heated by the laser beam, gas is released from the second layer 22, and this gas pressure increases to the third + mz :t, g4r A convex portion is formed by acting on the fort 24 and making it bulge.

In FIG. 1, a mounting plate 1 is mounted and fixed on a turntable 3, and is rotated as shown by an arrow 5 by the driving force of a motor 4. As shown in FIG. In this state, a first laser beam 9 is irradiated from a first laser oscillator (for example, an Ar laser is used) onto the object Vt film z via a mirror 7 and a lens 8 with a diameter of, for example, 1 μm or less. The mirror 7° and the lens 8 are driven and controlled so that the irradiation position of the laser beam 9 moves in the radial direction of the substrate 10 at a constant speed. At this time, if the power of the laser beam 9 is selected to be above a certain threshold, a seven-fold spiral convex portion 25 will be formed on the material +1142, as shown in an enlarged view in FIG. 2 (L,). .

On the other hand, a second laser oscillator 10 (for example, an Ar laser is used) is further prepared, and a second laser beam 13, which is narrowed down to a diameter of 2 μm by a lens 12, is transmitted through the laser oscillator 10 through a half mirror 11 to a material. It is irradiated onto the convex portion 25 of the membrane 2. Here, the irradiation position of the second laser beam 13 is set as close as possible to the irradiation position t of the first laser beam 9, for example, at a distance of 10 μm or less in the track length direction (direction of the convex portion 25). Set to .

Further, the power (irradiation energy density) of the second laser beam 13 is desirably set to a value that does not form a convex portion, for example, 1/2 or less of that of the first laser beam 9.

When the second laser beam 13 hits the convex portion 25, it is reflected, and its reflection intensity (amount of reflected interference light) changes depending on the formation state of the convex portion 25, especially its height. Therefore, this reflected light is guided to the photodetector 14 through the lens I2 and the half mirror 11, and the intensity of the reflection is detected. The output of the photodetector I4 is then guided to the control circuit 15, which determines the formation state of the convex portion 25 from the reflection intensity, and controls the laser oscillator θ based on the determination result to control the first laser oscillator θ. The power (energy) of the beam 9 is controlled so that the height of the convex portion 25 is constant.

That is, the above-mentioned substance rm 2i is the first irradiated material.
When the power of the laser beam 9 exceeds a certain threshold value 21 as shown in FIG. 3, a convex portion 25 begins to form, and the convex portion 259 increases as the power of the laser beam 9 increases. And the power of the laser beam 9 has a certain limit value 22
If it becomes more than that, the convex part will burst. For example, if the material J film 2 is m
2 m21 is formed of Te-C with a film thickness of 300 rbrrL, P, = 2.6 mW, P2
== 3.8 mW (both on the film surface), and the convex portion 2
The maximum height HO of 5 was 260 μm.

Although the change in the height of the convex portion 25 with respect to the power of the laser beam 9 is not a straight line as shown in FIG. 3, the reproducibility of the material film 2 is excellent. By controlling the power of the laser beam 9, the height of the convex portion 25 can be controlled at will.

On the other hand, the height of the convex portion 25 also changes depending on the thickness of the material film 2. FIG. 4 shows the 4)% factor, assuming that the power of the laser beam 9 is constant. If the film thickness is less than d1, the protrusions 25 will burst, but if the thickness is increased by dl, the height of the protrusions 25 will become saturated from a certain film thickness d2. This is because if the film thickness is 62 mm or more, the energy of the laser beam 9 will be absorbed within the film and will escape laterally. 242nd z is T
In the case of e-C, assuming that the power of the laser beam 9 is constant at 3 mW, d = 15QrLm.

d2: 400 nm.

From the above results, even if the thickness of the material film 2 changes, the height of the convex portions 25 can be made uniform by controlling the power of the laser beam 9 using the configuration shown in FIG.

The actual thickness is 300I at the center on the substrate 1 with a diameter of 300mm.
260 rLm at the periphery of the substance j formed unevenly
The laser beam 9 was irradiated onto the sample ('r'e-c system) while controlling the power as described above. However, the convex portions 25 could be formed with a uniform height of 80 rLrrL at a pitch of 1.6 μm. Incidentally, the power of laser beam 9 is 3 mtL at the center.

It changed to 2.1mW in the peripheral area.

When a large number of optical disks were manufactured directly from the master disc on which the convex portions 25 were formed or through a standber,
A disk was obtained having four continuous spiral sections of uniform depth as guide grooves.

Furthermore, among optical discs that have a random access function, there are many ways to reduce access time,
In order to make efficient use of the recording rib, a kind of control signal called preformat is formed in the form of a change or cut in the width of the groove. The present invention can also be applied to the production of such optical disk masters, and in that case, for example, the first
When forming the convex portion 25 with the laser beam 9, the power of the laser beam 9 may be weakened in the preformat signal area to partially lower the height of the convex portion.

Furthermore, the present invention can of course be applied not only to the production of master discs for internally grooved optical discs, but also to the production of master discs for reproduction-only optical discs such as video discs and digital audio discs. In that case, by modulating the first laser beam 9 according to an information signal such as a video signal or a digital audio signal, the convex portion can be formed not in a continuous spiral shape but in a discontinuous spiral shape according to the information signal. Bye.

Furthermore, the present invention is applicable to the production of master discs for original memories in the form of tapes and cards other than disks,
It is also effective when forming convex portions with analog height changes.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an optical disc master manufacturing apparatus for explaining an embodiment of the present invention, FIGS. 2(a) and 2(b) are diagrams showing the master disc packing and protrusion forming process, and FIG. 3 Figure 4 shows the change in the height of the convex portion with respect to the power of the irradiated laser beam when the thickness of the material film is constant, and Figure 4 shows the thickness of the K film when the power of the irradiated laser beam is constant. It is a figure which shows the change of the convex part height with respect to FIG. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Simulation of material that forms convex portions by irradiation with energy beam, 3...Turntable, 6
．． DESCRIPTION OF SYMBOLS 10... Laser oscillator, 9... First laser beam, 13... Second laser beam, 14... Photodetector, I5... Control circuit. Applicant's representative Patent attorney Takehiko Suze
, 3 n/') ;, Kazuo Wakasugi, Commissioner of the Japanese Patent Office1, Indication of the case Patent Application Shota-32447 No.2 Name of the invention Method for manufacturing optical disc masters3, Relationship to famous cases for supplementary IE Patent Applicant (307) Tokyo Shibaura Electric Co., Ltd. 4, Agent

Claims (4)

[Claims] (1) When manufacturing a master disc for manufacturing an optical disk from which information signals are read by irradiation with a light beam, a material layer is formed on the substrate to form convex portions by irradiation with an energy beam, and a layer of material is formed on this material film. The first energy beam is irradiated to form a convex part, and the second 'O energy beam is irradiated to this convex part, and the state of the convex part formation is determined based on the reflection intensity, and the determination result is used as the first energy beam. Feedback is given to the first
A method for manufacturing an optical disc Kawahara Jj,',j, characterized in that the energy of an energy beam of il+lI is controlled. (2) An optical disc master according to paragraph 1 of the patent C1j request, characterized in that the irradiation energy of the second energy beam is less than 1/2 of that of the first energy beam. manufacturing method. (3) The light of claim 1, characterized in that the distance between the irradiation position of the first energy beam and the irradiation (ikt) of the second energy beam in the track length direction is 10 μm or less. A method of manufacturing a disc master. (4) The first and second energy beams are laser beams, and the irradiation is performed in a bright place. (51) A method for manufacturing an optical disk master according to claim 1, characterized in that the convex portion formed by irradiation with the first A-Lugi beam has a continuous spiral shape. +6) No. 2. The method of manufacturing a master disk for a source disk according to claim 1, wherein the convex portion formed by irradiation with one energy beam has a discontinuous spiral shape according to a control signal or an information signal.