JPH0576103B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a stamper for molding a substrate for an optical information recording medium, and particularly to a stamper in which continuous or discontinuous convex portions are formed over the entire surface. .

[Technical background of the invention and its problems]

For example, optical information recording media have optically distinguishable continuous or discontinuous spiral protrusions or depressions on the substrate constituting the medium because it is necessary to enable stable track tracking and increase recording density. There is a demand for forming so-called guide grooves. For this purpose, for example, first a master disc with continuous spiral protrusions or depressions is produced,
A stamper is manufactured from this master using a method such as electroforming, and this stamper is used to injection mold organic resin.
A substrate on which the convex or concave shapes are transferred is formed by compression molding or casting, or by curing an ultraviolet curable resin with ultraviolet rays.

A stamper having such continuous spiral convex portions or concave portions is usually manufactured as follows. First, in the first step, a Cr film is deposited on a flat substrate made of glass or the like. Next, in the second step, a photoresist is applied onto the Cr film using a spinner or other method. Next, in the third step, the glass substrate coated with the photoresist is rotated, and continuous spiral exposure is performed while a laser beam reduced to about 1 μm in diameter is moved in the radial direction at a predetermined feed speed. Next, the fourth step is development, and the fifth step is pacing, creating a master disc. Next, an electrode film is formed on the master using a method such as vacuum evaporation, Ni electroforming is performed, and the master is peeled off to obtain a Ni stamper.

However, such a manufacturing method has the following drawbacks. That is, it is extremely difficult to form uniformly shaped protrusions or depressions over the entire surface of the substrate. The height of the convex shape to be formed on the stamper is 100 nm, which is 1/8 of the wavelength of the commonly used semiconductor laser, approximately 800 nm, in order to enable good track tracking.
It is desired that the width be about 1 μm.
On the other hand, the shape of the board is 300 mm to increase the recording capacity.
Something up to about φ is required. On the other hand, coating with a spinner is a technique that is normally used for coatings with a thickness of 1 to 2 μm or more;
It is extremely difficult to form a uniform coating film with a thickness of 100 μm over the entire area of φ, and partial peeling is unavoidable. Moreover, even a small amount of dust in the atmosphere that adheres to the substrate can cause serious coating unevenness. Furthermore, it is extremely difficult to uniformly develop the entire area, and the occurrence of uneven development is unavoidable. A stamper made by electroforming Ni from such a master disc can only be obtained by transferring all the defects of the master disc. Furthermore, it is necessary to peel the photoresist from the stamper in a later step, but it is inevitable that the photoresist will adhere to the stamper surface as a residue due to phenomena such as burn-in. Furthermore, there is still room for improvement in that two steps are required: firstly, the master disk, and secondly, the stamper is manufactured from this master disk.

As an improvement to these, we devised a method that does not use any photoresist and filed an application for it (patent application
57-168623). The configuration diagram of the stamper is shown in FIGS. 1 and 2. Fig. 1 is a sectional view of a semi-finished product, and Fig. 2 is a sectional view of a minute part of the stamper. The second layer 3 is made of a thin film that has good release properties, and the third layer is made of a thin metal film that has high mechanical strength and good adhesion.
A fourth layer 5 made of a thin film with good mold releasability is sequentially laminated, placed on a rotating support 5, and irradiated with a focused laser beam 8 through a lens 7 while rotating the substrate. Four layers of thin film are stretched, and a continuous spiral protrusion 9 is formed as shown in FIG. This stamper eliminated all the drawbacks of the conventional method, but after manufacturing a large number of stampers, the following drawbacks were discovered. That is, the adhesion between the substrate and the first layer is good, but when the organic resin substrate is molded and peeled off, partial peeling occurs from the second layer, probably because the adhesion between the first layer and the second layer is poor. The main component of the second layer that has both energy absorption and gas release properties is
Since it is a low melting point metal with a melting point of 600℃ or less, when the film is stretched by laser beam irradiation, if the laser beam intensity changes due to fluctuations in the power supply, etc., the film may break beyond the tension. The third layer film required for mechanical strength is
It also becomes a laser beam absorption film, greatly reducing the efficiency of laser power.
The fourth layer required for mold releasability ends up becoming a laser beam absorption film, which greatly reduces the efficiency of laser power.

[Purpose of the invention]

The present invention proposes a stamper for forming a substrate that overcomes the above-mentioned drawbacks.

[Summary of the invention]

That is, the stamper of the present invention maintains mutual adhesion between the first layer, which is a thin metal film that has good adhesion to the substrate, and the third layer, which has a characteristic of being stretched, on the substrate. The second layer has a role to play; the third layer contains an alkyl component and has the property of being stretched by laser beam irradiation; it does not absorb much laser beam energy, has stretchability, and has excellent peelability from organic resins. The fourth layer of the third layer is peeled off sequentially onto the substrate, and the fourth layer of the third layer is
Continuous or discontinuous spiral convex portions are formed on the surface of the layer.

The first layer metal thin film mentioned above is made of Ti, Cr, W,
Using Mo, Co, Ni, Ta, V, Zn, Hf, etc., it is deposited on the substrate by a normal thin film forming method such as sputtering or vacuum deposition. Furthermore, the most suitable substrate is a glass substrate with a smooth surface. Next, without breaking the vacuum, Au, Ag, Cu, Pd, etc. are formed using a normal thin film forming method, and this film becomes the second layer. Next, a third layer is formed by sputtering. This film is formed by sputtering in a mixed gas of methane-based hydrocarbon gas and inert gas, but the metal plate attached as a target has a high melting point, but
Metals that easily form eutectic alloys with Cu, Sn, etc., e.g.
Ag or Ge etc. are most suitable. Plasma is generated by placing the substrates facing each other with the Ag plate as a target, applying a voltage between them, and flowing CH ₃ gas as a methane-based hydrocarbon gas and Ar gas as an inert gas.
The -H, _-CH3 , _-H2 , and _-CH2 groups dissociate and hit the target surface. Then, Ag atoms are knocked out and form Ag-H, Ag-CH ₃ , Ag-H ₂ , Ag-CH ₂
Alkyl Ag metals such as are reacted and formed. On the other hand, Ar
Since Ag atoms are also knocked out by gas,
A film containing a mixture of alkyl Ag and Ag grows on the substrate. When the resulting film was examined by X-ray diffraction, it was found to be amorphous, and when examined with more precision using a microplane scattering method, it was found to be a collection of crystalline Ag fine particles with a diameter of approximately 6 nm. It was found that the voids were filled with alkyl molecules, and that the Ag particles and alkyl molecules were bonded by alkyl Ag. When this film is heated to about 180°, the alkyl molecules evaporate, resulting in a weight loss of about 30%. Fourth
The layer is a film of Au, Ag, Cu, Pd, etc., and is formed by a normal film formation method. Here, the thickness of these films becomes a problem.

Even if the first layer is thick, it will not be effective, and if it is too thin, it will not be effective, and a thickness of 5 to 500 nm at most is sufficient. The second layer needs to have a thickness of about 50 to 500 nm to allow the reaction to proceed sufficiently. The third layer confines the evaporated molecules within the film so that they cannot escape from the film when evaporation of alkyl molecules occurs, and if the film is thin enough to swell the film with its force, the gas It cannot be kept confined, and even if it swells, it will burst immediately, and even if the film is made too thick, it will absorb too much energy and will not be able to swell effectively. Tests have shown that a film thickness of 100 to 500 nm can most effectively inflate the film, and the thickness of the fourth layer is the most severe. That is, since the laser beam irradiation is applied to the third layer through the fourth layer, it is necessary to have a film thickness that does not absorb the laser beam, and to help the third layer swell and prevent it from bursting, it is necessary to use a stretchable material with a certain thickness or more. It is necessary to cover the film with a sufficient thickness, and the film thickness must be sufficient to allow the organic resin to be peeled off. As for the material, the above-mentioned Au, Ag, Cu, Pd, etc. are excellent, and their film thicknesses are optimally in the extremely thin range of 20 to 35 nm. Continuous or discontinuous spiral convex parts are created by rotating the substrate on which four layers of thin films are formed, and continuously or discontinuously irradiating the laser beam focused to about 1 μm diameter while sending it in the radial direction at a predetermined speed. It can be formed by The convex portion is locally heated by the irradiated laser beam, and is formed by the stretching of the third layer due to gas expansion and the stretching of the fourth layer due to this pressure.

In order to form an organic resin substrate using such a stamper, there are no restrictions on its usage as long as the base forming the stamper is not destroyed. For example, a pre-formed flat recording medium-like substrate material and this stamper are placed opposite each other, and an ultraviolet curing resin is poured between the two, and ultraviolet rays are irradiated from the flat substrate side to harden it, forming continuous spiral convex parts. A transferred recording medium substrate is obtained. Alternatively, for example, a casting method may be used in which an organic resin monomer or syrup is poured onto the stamper and polymerized by heating.

[Embodiments of the invention] Examples will be described below.

Example 1 FIG. 3 is a sectional view of a semifinished stamper of this example. First, a 300 mmφ glass is used as the substrate 11, and a 30 nm thick Ti film 12 is used as the first layer.
A 100 nm thick Au film 13 is continuously formed as a second layer by sputtering. Next, the Ag target was sputtered in a mixed gas of CH ₄ gas and Ar gas,
A third layer 14 having a thickness of 300 nm and containing Ag-CH ₃ and Ag-CH ₃ as components is formed. Next, the thickness of the Au film is
The fourth layer 15 is formed with a thickness of 30 nm. These four layers are best formed by continuous sputtering. The substrate on which these four layers have been formed is placed on a rotating support 16, and irradiated with an Ar gas laser beam 18 focused to 1 μm diameter by a lens 17 while moving in the radial direction at a predetermined speed. FIG. 4 shows a sectional view of a minute portion of the stamper formed in this manner. A continuous spiral convex portion 19 is formed on the film surface of the stamper. The height of the convex portion is 0.1 μm, and the width at the bottom is 1.1 μm. This convex portion is uniformly formed over the entire surface of the 300 mmφ glass plate, and no peeled portions are observed.

The advantages of a stamper obtained by forming a thin film in a vacuum in this way are that, unlike a stamper that is electroformed from a master using the photoresist method, it can form uniform protrusions over the entire surface of the substrate, and there is no dust in the atmosphere. It is possible to form a film with a uniform thickness over a large area.

When the stamper of this example was used to transfer the acrylic ultraviolet curable resin onto a flat acrylic plate, it was possible to transfer an extremely uniform continuous spiral concavity over the entire surface of the recording medium substrate. does not peel off any thin film.

Example 2 30nm Cr as the first layer on 300mmφ glass,
Mo, W, Co, Ni, Fe, Ta, V, type 2
A layer of 300 nm of Al, Ag, or Pd, and a 400 nm thick film of Ag-CH ₃ or Ag-CH ₂ as the third layer, or a film of Ge-CH ₃ or Ge-CH ₂ . , a 30 nm thick film of Ag, Pd, or Al is formed as the fourth layer. Next, 144 kinds of stampers (8×3×2×3=) are manufactured by placing the stamper on a rotating table and discontinuously irradiating it with a laser beam in the radial direction at a predetermined speed while rotating. All stampers have a width of 0.9~
It has a discontinuous spiral convex portion of 1.2 μm and a height of 0.6 μm or more. When a substrate was molded by the cell casting method using these stampers, a well-shaped discontinuous spiral concave portion could be transferred.

These stampers can also be used as master discs for stampers made by ordinary electroforming.

From the above results, the first layer has good adhesion to the glass substrate, and since the second layer is continuously molded in the same vacuum as the first layer, the adhesion with the first layer is improved and the third layer is eutectic at low temperature. In order to form an alloy, the adhesion with the third layer has been improved, and a fourth layer has been introduced to freely control the expansion of the third layer, and the ingredients of the fourth layer are also the same as the metal of the third layer. Because the ingredients and the ingredients that tend to form a eutectic alloy are arranged, the strength of swelling is enhanced and deformations such as shrinkage and crushing do not occur. Therefore, it can sufficiently withstand heat and pressure during molding of organic resin substrates, allowing molding of a large number of substrates without any peeling or the like.
In addition, because we used a metal that does not have a low melting point as the third layer metal, stretching occurs at around 180°C when the alkyl molecules are about to evaporate, and as the temperature is raised, gas escapes through the gaps in the film, causing the film to deteriorate. Changes to metallic crystalline state. After that, holes are formed in this film due to the melting point of the film, Si
In the case of a film, this occurs when the temperature reaches 1412°C, so the temperature range that can be maintained in a metal film is much wider than that of a low-melting metal film. For this reason, there were no cases where holes were formed in the lining due to changes in laser power, etc.

〔Effect of the invention〕

As described above, the present invention eliminates the drawbacks of the conventional stamper and provides a stamper for molding a substrate having a simple structure and extremely uniform continuous or discontinuous spiral convex portions over a large area. be able to.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a semi-finished product and a minute portion of a conventional stamper, and FIGS. 3 and 4 are cross-sectional views of a semi-finished product and a minute portion of a stamper of the present invention. 11; Substrate, 12; Ti film, 13; Au film, 1
4; third layer, 15; fourth layer, 16; rotating support,
17; lens; 18; laser beam; 19; convex portion.

Claims (1)

[Scope of Claims] 1. A stamper for forming a substrate for an energy information recording medium film, wherein the stamper has a first metal thin film on the base, which is made of a thin metal film having good adhesion to the base.
layer, a second layer that improves the adhesion between the first layer and the third layer.
The third layer consists of a thin film containing an alkyl metal made of alkyl molecules and a metal with a melting point of 600°C or more, and the third layer consists of a thin metal film that has energy non-absorption properties, stretchability, and good mold releasability from resin. 1. A stamper for forming a substrate, characterized in that a fourth layer is sequentially formed, and continuous or discontinuous spiral convex portions are formed on the film surfaces of the third and fourth layers by laser exposure. 2 The first layer metal thin film is Ti, Cr, W, Mo,
The stamper for molding a substrate according to claim 1, wherein the stamper is a single substance or an alloy containing at least one of Co, Ni, Fe, Ta, V, Zn, and Hf. 3. The stamper for forming a substrate according to claim 1, wherein the second layer film is a single substance or an alloy containing at least one of Au, Ag, Al, Cu, and Pd. 4 The third layer film is formed by generating an electric discharge between the metal plate and the substrate on which the first layer and the second layer are laminated in a mixed gas of methane-based hydrocarbon gas and inert gas. A metal film mainly made of an inert gas and an alkyl metal film made of a methane-based hydrocarbon gas are simultaneously grown and formed on the second layer by generating a gas. A stamper for forming a substrate according to scope 1. 5 The fourth layer metal thin film is Au, Ag, Pd, Al, Cu
The stamper for molding a substrate according to claim 1, characterized in that it is a single substance or an alloy containing at least one of the above. 6. A patent claim characterized in that a thick film is formed on a stamper by electrolytic Ni plating, the stamper is peeled off to form a surface on which unevenness is reversely transferred, and this surface is transferred onto an organic resin substrate surface. A stamper for molding a substrate according to scope 1.