KR20030052707A - disk structure optical recording medium type and production process of the same - Google Patents

Abstract

PURPOSE: A disk structure for an optical recording medium and a method for manufacturing the same are provided to prevent a surface of a disk from being damaged. CONSTITUTION: Information pits are formed on a substrate formed of a high polymer resin by injection-molding. A reinforced layer(70) is formed on the substrate(10) by accumulating SiO2 layers having opposite residual stress to increase the hardness. The strength of the reinforced layer is increased by a grain refinement, a precipitation hardening, and a dislocation density, or combination thereof. A reflective layer(20), a dieletric layer(30), an information recording layer(40), another dieletric layer(50), and a protective layer(60) are formed on the reinforced layer in order.

Description

Disk structure for optical recording medium and manufacturing method thereof {disk structure optical recording medium type and production process of the same}

The present invention relates to a structure of a disc for an optical recording medium capable of recording and reproducing information and a method of manufacturing the same.

Recently, with the advent of the information age, the development of information storage system is progressing rapidly, including the use of digital broadcasting, high-definition TV (HD-TV), and mobile application consumer products. Increasingly, the demand for information storage methods and media with high recording density, high reliability, and low price is increasing.

In order to achieve such a high density, a conventional approach has been to use a laser diode (LD) having a short wavelength of a light source or a numerical aperture (NA) of an objective lens located at the bottom of an optical pickup. Was to minimize the beam size at the focus.

However, this method belongs to the area of diffraction optics, and it is impossible to improve the recording density beyond the diffraction limit.

A new concept of the technique proposed to overcome the limit recording density in the diffraction optical domain is as follows.

First, near-field optical recording using near-field optics

Secondly, planar aperture array type smaller than optical fiber or diffraction limit

Third, SIL (Solid Immersion Lens)

Fourth, an optical flying head that performs a vertical servo based on the flying type used in a magnetic thin film hard-disk drive (HDD).

Among them, SIL is attached to the optical flying head so that information can be read and reproduced while floating at a height (tens of nanometers) very close to the surface of the media to increase density and speed simultaneously. Has received great attention.

However, there are some key technical challenges that must be addressed before this approach can be put to practical use.

First, in order to overcome the existing diffraction limit using near field optics, a small beam waist below the diffraction limit due to the near field must be created, and the small beam below this diffraction limit can be recorded or recorded. You must bring it to the location.

However, one difficulty here is that the exponential function decreases the intensity and the size of the beam as it moves away from the light source (lower lens or optical fiber tip) due to the nature of the near field beam. There is a growing problem.

Therefore, in order to take advantage of the near field light formed, the distance between the light source (such as an optical pickup including a lens) and the medium (exactly the information recording layer of the medium) must be kept very close (tens of nanometers).

This causes the media and the lens to be close enough to physical contact with each other by self-vibration or external forces, causing a crash (lens crash, similar to a head-crash on an HDD).

So in order to minimize the possible tragedy, the surface of the medium has a structure coated with a protective film (eg, Diamond-Like Carbon (DLC)) and a lubricant film.

Eventually, in order to overcome the diffraction limit, the near field of light must be used, but the collision between the lens and the medium is maintained by keeping the flying height low to keep the intensity and beam size small, which are the properties of the near field. This occurs and has a problem of deteriorating reliability.

Secondly, in order to control the environment in which information is recorded and reproduced from contaminants (dust, heads or debris away from the surface of the media), the magnetic hard disk drive (HDD), which is sealed from the outside, is controlled. In contrast, in the optical recording method, there is a problem in that the recording and reproducing areas must be exposed in the air in order to make use of the removability of inserting and removing the media from the drive.

At this time, it can be put in the cartridge to prevent fingerprints or dust on the surface of the media while handling the media, but there are many sources of contamination including dust of various sizes, so it is very likely to be exposed to contamination. high.

In particular, the lubricant layer covering the surface of the medium exists in a low-viscosity liquid phase in order to minimize the side effects caused by lens collision, which is like a gum when the dust comes close to the surface of the medium. It has the effect of scraping off the media surface.

As a result, the surface roughness of the medium is changed, and as the intensity of the power from the light source of the optical pickup passes through this contaminant layer, the reduced power reaches the recording layer so that the size of the recorded mark becomes smaller and jitter. It causes an increase.

In particular, jitter tolerance in high density information storage media is very tight, making it difficult to meet the specification of the Bit Error Rate (BER).

In the end, a lubricant layer should be used to reduce the specific polarity during lens collisions, but the presence of this layer usually causes the adverse effect of scraping dust.

Third, when light energy as a light source propagates through the medium, part of the light energy is converted into thermal energy because the absorption coefficient k of the material placed in the path is not zero, resulting in low melting point. Part of the lubricating oil is vaporized by laser radiation to cover the surface of the lens, so that there is a problem that contaminants such as dust accumulate later on the lens surface. This problem must be solved by causing additional problems in succession once occurring.

Fourth, the optical recording media is superior to the conventional magnetic hard disk drive (HDD) method in that the media can be inserted and removed from the drive. On the other hand, a multilayer film is coated on a metal substrate that requires processing, while optical disks are manufactured by injection molding polymer resins, including polycarbonate, and thus have great strength in manufacturing time and cost. It is characteristic that there is.

However, as the recording density gradually increases, the distance between the medium and the head decreases so that the slider physically contacts the medium more accurately than the head.

In this case, although the surface of the disk is covered with a high hardness protective layer and a lubricant layer, there is a problem that the surface of the disk is easily damaged due to the low hardness of the injection molded polymer substrate.

In order to solve this problem, in the past, a high hardness organic substrate was used, but the disk was expensive because the power consumption was large and it could not be produced by injection molding, and thus, the disk was expensive, and pre-pits or land and grooves were used. There is a problem that is difficult to make.

Accordingly, the present invention has been made to solve the above problems, and the structure and fabrication of an improved optical recording medium disc for realizing ultra high density optical recording by overcoming the diffraction limit for determining the limit recording density in the diffraction optical area. The purpose is to provide a method.

Fig. 1A is a schematic diagram showing the structure of an optical recording disc for a ring-shaped medium according to the prior art.

Fig. 1B is a schematic diagram showing the structure of an optical recording disc including a reinforcing layer in a slow ring type media according to the present invention.

2A is a diagram showing the structure of a reproduction-only optical recording disc according to the prior art;

FIG. 2B is a schematic structural diagram of a disc including a reinforcing layer in a read-only medium according to the present invention. FIG.

* Explanation of symbols for main parts of the drawings

10 substrate 20 reflective layer

30, 50: dielectric layer 40: information recording layer

60: protective film 70: reinforcing layer

Features of the structure of the disk for an optical recording medium according to the present invention for achieving the above object is a reinforcing layer laminated on one or more layers facing each other on the substrate made of a polymer resin to have opposite residual stress components, and the reinforcing layer It is stacked on top of the reflective layer, the dielectric layer, the information recording layer, the dielectric layer, and the protective film.

At this time, the substrate has a land-groove structure for pre-pits or servo, which has another feature.

Another feature of the structure of the disk for an optical recording medium according to the present invention for achieving the above object is a reinforcing layer laminated on one or more layers facing each other on the substrate composed of a polymer resin to have opposite residual stress components, The stack is stacked on the reinforcing layer in order of a reflective layer and a protective film.

In this case, the substrate has an information pit structure, which is another feature.

The thickness of the reinforcing layer has a range of 0.5 to 3 micrometers, and has another feature of increasing strength by grain refinement and precipitation hardening or dislocation density or a combination thereof.

The reinforcing layer has another feature of alternately stacking two or more layers of materials having different stress components (compression residual stress and tensile residual stress).

Features of the manufacturing method of the disc for optical recording media according to the present invention for achieving the above object is the step of injection molding the information pits (pis) on a substrate formed of a polymer resin, the hardness on the injection molded substrate Laminating one or two or more reinforcing layers having increased strength by grain refinement, precipitation hardening or dislocation density or a combination thereof to increase the resistance, and a reflective layer, a dielectric layer, an information recording layer, a dielectric layer, and a protective film on the reinforcing layer. It comprises a step of forming by laminating in order.

A feature of the manufacturing method of a disk for an optical recording medium according to the present invention for achieving the above object is a land-groove for pre-pits or servo on a substrate formed of a polymer resin. groove) and a reinforcing layer having increased strength by grain refinement and precipitation hardening or dislocation density or a combination thereof to increase hardness on the pre-pit or land-groove injection molded substrate or Forming by stacking two or more, and the step of laminating in the order of the reflective layer, the protective film on the reinforcing layer, there is another feature.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Referring to the accompanying drawings, a structure of a disc for an optical recording medium and a method of manufacturing the same according to the present invention will be described below.

FIG. 1B is a schematic view of a structure of a disc including a reinforcing layer in a slow ring type medium according to the present invention, that is, a medium for repetitive information recording and rewritable media.

Referring to FIG. 1B, a reinforcement layer 70 including a plurality of SiO ₂ layers having opposite residual stress components on the substrate 10 facing each other, a reflection layer 20, a dielectric layer 30, The information recording layer 40, the dielectric layer 50, and the protective film 60 are sequentially stacked.

That is, compared with the conventional disc structure shown in Fig. 1A, a reinforcing layer 70 is further added between the substrate 10 and the reflective layer 20, thereby increasing the hardness of the disc, thereby bending the disc during recording / reproducing of the recording medium. It is reducing the phenomenon.

At this time, the substrate 10 used is made of a polymer resin that is easy to injection molding, and is a recordable (write-one read-many (WORM)) and repeatable erase-writable disc as shown in FIG. It has a land-groove structure for pre-pits or servos.

In addition, the reinforcing layer 70 increases the strength by grain refinement and precipitation hardening or dislocation density or a combination thereof, and has a structure in which materials having different stress components are alternately stacked.

2B is a diagram showing the structure of a disc including a reinforcing layer in a read-only medium according to the present invention.

Referring to FIG. 2B, a reinforcement layer 70 including a plurality of SiO ₂ layers having the same residual stress components on the substrate 10 facing each other, and a reflective layer 20 and a protective layer 60 on the reinforcement layer 70 may be formed. It consists of a structure laminated sequentially.

That is, compared with the conventional disc structure shown in Fig. 2A, a reinforcing layer is further added between the substrate and the reflective layer, thereby increasing the hardness of the disc, thereby reducing the warpage of the disc when the recording medium is played back.

When configured in this way, Figure 2b is made of a polymer resin that is easy to injection molding the substrate 10 used in the same manner as in Figure 1b.

The injection molded substrate 10 has an information pit structure as shown in FIG. 2B in the case of a read-only memory (ROM) disk.

The reinforcing layer 70 is to increase the surface strength of the injection-molded disk substrate, one or two or more laminated to form a thickness of 0.5 ~ 3 micrometers (micrometer) range.

As a result, the reinforcing layer 70 is microstructured so as to have great resistance to stress caused by contact with the external head, such as grain refinement, precipitation hardening, or dislocation density, or a combination thereof. It serves to increase the strength by.

A method of manufacturing a disc for an optical recording medium according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

A method of manufacturing the disk for a slow ring type optical recording medium shown in Fig. 1B is as follows.

Referring to FIG. 1B, first, information pits are injection molded on a substrate 10 formed of a polymer resin that is easy to injection molding.

In order to increase hardness, the pits are formed by stacking one or two or more reinforcing layers 70 having increased strength by grain refinement, precipitation hardening, or dislocation density, or a combination thereof.

At this time, the thickness of the reinforcing layer 70 is formed to have a range of 0.5 ~ 3 micrometers, in order to minimize the degradation of the adhesive strength due to the residual stress in the reinforcing layer 70, or the possibility of bending, different stress components, that is, Formed by alternately stacking materials having compressive residual stress or tensile residual stress.

Subsequently, the reflective layer 20, the dielectric layer 30, the information recording layer 40, the dielectric layer 50, and the passivation layer 60 are stacked on the reinforcement layer 70.

Accordingly, in the case of repetitive information recording and rewritable media, the stacking layer is stacked on the reinforcing layer in order of the reflective layer 20, the dielectric layer 30, the information recording layer 40, the dielectric layer 50, and the protective film 60. When pressed by the stress caused by contact with the head, the reinforcement layer 70 prevents the multilayer film laminated on the reinforcement layer 70 from being pressed due to the low strength of the polymer resin substrate.

Next, a manufacturing method of the optical recording disc for reproduction shown in FIG. 2B will be described.

Referring to FIG. 2B, first, land-groove for pre-pits or servo is injection molded on a substrate 10 formed of a polymer resin which is easy to injection molding.

One or two reinforcing layers 70 having increased strength by grain refinement, precipitation hardening, or dislocation density, or a combination thereof in order to increase hardness on the pre-pit or land-groove injection-molded substrate 10. It forms by laminating | stacking above.

At this time, the thickness of the reinforcing layer 70 is formed to have a range of 0.5 ~ 3 micrometers, in order to minimize the degradation of the adhesive strength due to the residual stress in the reinforcing layer 70, or the possibility of bending, different stress components, that is, Formed by alternately stacking materials having compressive residual stress or tensile residual stress.

Subsequently, the reflective layer 20 and the protective film 60 are stacked on the reinforcing layer 70 in this order.

Accordingly, in the case of a regeneration-only medium, the reflective layer 20 and the protective film 60 are stacked on the reinforcing layer 70 in order, and when the medium is pressed by the stress generated by the contact with the head, the reinforcing layer 70 is laminated on the reinforcing layer 70. The reinforced layer 70 prevents the multilayered film from being pressed due to the low strength of the polymer resin substrate.

As described above, the structure of a disk for an optical recording medium and a method of manufacturing the same according to the present invention provide a reinforcing layer on an injection molded polymer resin substrate, thereby reinforcing a multilayer film including a hard protective layer on the surface of the disk. By doing so, it is possible to effectively prevent the problem that the surface of the disk is damaged.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (7)

An optical recording and reproducing medium comprising a substrate, a reflective layer, and a protective film, wherein a plurality of reinforcing layers having residual stress distributions in opposite directions are stacked between the reflective layer and the protective film, wherein the reinforcing layer is grain refined, precipitated. A disk structure for an optical recording medium, wherein the strength is increased by a hardening method, a dislocation density method, or a combination thereof. The method of claim 1, And the total thickness of the reinforcing layer has a range of 0.5 to 3 mu m. The method of claim 1, And the reinforcing layer is formed of SiO ₂ . Injection molding information pits on a substrate formed of a polymer resin; Stacking one or more reinforcing layers of increased strength by grain refinement, precipitation hardening or dislocation density or a combination thereof to increase hardness on the injection molded substrate; And laminating a reflective layer, a dielectric layer, an information recording layer, a dielectric layer, and a protective film on the reinforcing layer in the order of forming the optical recording medium. The method of claim 4, wherein The step of forming the reinforcing layer is formed to have a thickness in the range of 0.5 ~ 3 micrometers, and is formed by alternately stacking materials having different stress components to each other. Injection molding a land-groove for pre-pits or servo on a substrate formed of a polymer resin, Laminating one or two or more reinforcing layers having increased strength by grain refinement, precipitation hardening, or dislocation density or a combination thereof to increase hardness on the pre-pit or land-groove injection molded substrate; , And laminating the reflective layer on the reinforcing layer in order of the protective layer. The method of claim 6, The forming of the reinforcing layer may include forming a thickness in a range of 0.5 to 3 micrometers, and alternately stacking materials having different stress components in the reinforcing layer.