KR20010103476A - optical pick-up device and method for fabricating the same and apparatus for record/playback of optical information using those - Google Patents

Abstract

An optical pickup apparatus, a method of manufacturing the same, and an optical information recording / reproducing apparatus using the same, comprising: a solid immersion lens frame, a solid immersion lens formed in the solid immersion lens frame, and a lower surface of the solid immersion lens frame And a thin film having a fine opening in the center portion. Here, the thin film is any one of a photochromic material, a thermochromic material, and a phase change material, and the opening is changed according to the power of light incident on the solid immersion lens. Therefore, by manufacturing the micro aperture by the optical self-alignment characteristic formed on the surface of the solid immersion lens to further reduce the beam size of the near-field light, the effective aberration of the near-field optical system can be further increased, and thus, the pickup head By improving the uniformity and resolution of the high density optical information storage device can be implemented.

Description

Optical pick-up device and method for fabricating the same and apparatus for record / playback of optical information using those

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro-optical system used in a high density information recording apparatus, and in particular, a near field optical pickup device using a slit integrated into a solid immersion lens (SIL), a manufacturing method thereof, and optical information using the same. A recording / reproducing apparatus.

The recent rapid development of multimedia technology is largely attributed to the increase in the capacity of information storage devices and the reduction of the unit cost per information storage density.

The improvement of personal computer performance, the rapid spread of data communication such as Internet, VOD (Video On Demand), and the emergence of high-quality television are large-capacity information storage media that can process large amounts of data including moving images and audio signals in real time. There is a stronger demand for the need.

By increasing the storage density and capacity of the HDD (Hard Disk Drive), magnetic storage products have been introduced for the realization of high density information devices, but in the case of the magnetic storage method, the particle size of a material whose magnetization density can be magnetized Limited by, it is known that it is quite difficult to realize more than a few tens of gigabytes (G: giga) per square inch.

Optical information storage devices, due to the potential to realize high-density information capacity in principle, have recently been actively progressed in R & D and commercialization.

That is, the optical information storage device has advantages such as fast response speed, non-contact pickup and easy portability, and above all, the data density can be increased to the wavelength range of the laser light source for recording / reproducing.

The data density of the optical information storage device is limited by the diffraction limit of the input light source, and this relationship is expressed by the following equation (1).

d = λ / (2NA)

Here, d is the spot size of the laser light irradiated to the surface of the optical disk after passing through the optical system, λ is the wavelength of the input light irradiated to the information storage medium, NA is the aperture ratio (or aberration: Aperture: general optical system) The lens has a value of about 0.5 to 0.7.

The geometric minimum size of one data that can be identified is determined by the focal size of the input laser light represented by d in Equation 1 above.

Therefore, the size of the data that can be determined is approximately the upper limit of the data recording density at approximately the wavelength of the input laser light.

This limit is due to the diffraction property of the light, and as shown in Equation 1 above, by reducing the data bit size, that is, increasing the information storage density, by using shorter wavelength input light or increasing the aberration of the optical system. The diffraction limit of the input light can be overcome.

In particular, as a technique to overcome the diffraction limit of the input light by increasing the aberration (NA) of the optical system, research into the practical use of the method using the solid immersion lens is active, and the optical pickup head using the solid immersion lens Implementation has emerged as a key component of high-density optical information storage.

The method of increasing the effective NA of the optical system with the near field optical system using the solid immersion lens is to increase the refractive index of the material constituting the solid immersion lens. A method of adding a protruding probe to the emitted micro area, and a method of coupling an optical aperture of a suitable shape to the micro area where the near-field light is emitted from the flat surface of the solid immersion lens have been proposed. The beam size of the focal point irradiated onto the optical disc recording film to be further reduced can be further reduced.

In another approach, when the laser beam focused on the recording film of the optical disk is irradiated, a thin film is formed so that an opening through which light is transmitted in a minute region near the laser beam optical axis is formed by the heating effect of the laser beam. Research is also being conducted to generate ultra-fine near-field light suitable for high density optical information storage.

This method is called SRENS (Super Resolution Enhancement Structure), and has proposed an optical disk structure in which a self-aligned opening is formed by forming a multi-layered film structure of a silicon nitride film / antimony (Sb) thin film / silicon nitride film on an optical recording film. .

The antimony thin film has a property of transmitting a laser beam having a specific wavelength when heated above a certain temperature, so that a focused laser beam having a Gaussian distribution focused by an optical system used in an existing optical recording device is SRENS. If the irradiation time or amount of light is controlled to the extent that an opening can be formed so that only the temperature of the region adjacent to the optical axis is transmitted to the layer, the beam size is further reduced than the spot size of the focused laser beam. Only one can reach the recording film.

In addition, in the method of forming an opening in the surface of the conventional solid immersion lens, a metal having a predetermined thickness is deposited on the flat surface of the solid immersion lens, and ion milling the metal thin film at the center of the surface of the solid immersion lens. ) To remove it.

However, the optical pickup apparatus, the manufacturing method thereof, and the optical information recording / reproducing apparatus using the same according to the related art described above have the following problems.

Using the conventional SRENS technology, an additional thin film is required on the optical disk, which makes the structure of the optical disk complex and increases the manufacturing cost of the optical disk.

In the conventional method of forming an opening in the solid immersion lens, it is very difficult to form an accurate opening at a position coinciding with the optical axis, so that the position of the opening has an alignment error with the optical axis, thereby reducing the shape of the near-field light. Rather, it can cause deterioration, and the throughput is very low.

Accordingly, the present invention is to solve the above problems, a high-density near-field optical pickup device and method of manufacturing the same and the light using the same by integrating the self-aligned opening on the surface of the solid immersion lens to further reduce the beam size An object thereof is to provide an information recording / reproducing apparatus.

1A is a structural perspective view of a solid immersion lens (SIL) according to the present invention.

1b is a structural cross-sectional view of a solid immersion lens according to the present invention;

2A and 2B are structural perspective views of an optical pickup device according to the present invention.

3 is a structural cross-sectional view of an optical pickup device according to the present invention.

4 is a block diagram of an optical information recording / reproducing apparatus according to the present invention.

5A to 5I are sectional views of the manufacturing process of the optical pickup apparatus according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Solid immersion lens (SIL) 11: Solid immersion lens frame

2: opening forming thin film 12: air-bearing surface (ABS)

3: self-aligning opening 13: tapered edge

In order to achieve the above object, an optical pickup apparatus, a method of manufacturing the same, and an optical information recording / reproducing apparatus using the same include: a solid immersion lens frame, a solid immersion lens formed in the solid immersion lens frame; And a thin film formed on the lower surface of the solid immersion lens frame and having a micro-opening in the center thereof.

Here, the thin film is any one of a photochromic material, a thermochromic material, and a phase change material, and the opening is changed according to the power of light incident on the solid immersion lens.

In addition, an air-bearing surface for supporting the solid immersion lens frame is formed on the lower surface of the solid immersion lens frame, and a portion of the lower surface of the solid immersion lens frame is inclined at an angle.

Features of the optical information recording / reproducing apparatus according to the present invention include a light source module for generating light, a focusing unit for focusing light generated from the light source module on the surface of the optical recording medium, and light reflected by the optical recording medium. A light detector for converting an electric signal into a light detector, and a light separator that is located between the light source module and the focusing unit to transmit light generated from the light source module to the focusing unit, and is reflected by the optical recording medium to transmit light passing through the focusing unit to the light detecting unit. And a mirror positioned between the focusing part and the light splitting part to change the path of incident light, and a thin film having a micro aperture at the bottom of the solid immersion lens, and precisely inputting the light input to the solid immersion lens through the micro aperture. An optical pickup device comprising an optical pickup head portion that focuses and irradiates an optical disk is used.

In still another aspect of the present invention, there is provided a first step of forming a first mask and a second mask on the lower and upper portions of a substrate, and by patterning the first mask to expose a lower center portion of the substrate, and etching the exposed area. A second step of forming a mold, a third step of removing a first mask, and filling a mold with a material to form a solid immersion lens, and an opening forming thin film on the surface of the substrate filled with the solid immersion lens A fourth step of forming, a fifth step of forming an air-bearing surface (ABS) on both sides of the opening-forming thin film, a sixth step of patterning the second mask to expose a central portion of the substrate, and an exposed substrate. And a seventh step of removing the substrate to a predetermined thickness by etching, and an eighth step of forming a self-aligning opening by irradiating light to the exposed solid immersion lens.

In the second step, the mold is isotropically etched using any one of a solution, gas, and plasma, and the fifth step is a shadow mask method, a lift-off method, and a screen printing method. One of the printing methods is used, and the seventh step uses any one of bulk micromachining technology, dry etching, and wet etching.

The solid immersion lens material is formed of a material having a high refractive index.

According to a feature of the present invention, by forming the aperture by the optical self-aligning characteristics formed on the surface of the solid immersion lens to further reduce the beam size of the near-field light, it is possible to further increase the effective aberration of the near-field optical system, Accordingly, it is possible to implement a high density optical information storage device by improving the uniformity and resolution of the pickup head.

In addition, since the pickup apparatus is manufactured using a semiconductor batch fabrication process, the manufacturing process is simple and mass production is easy, thereby reducing the manufacturing cost of the optical pickup head.

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 preferred embodiment of an optical pickup device, a method of manufacturing the same, and an optical information recording / reproducing apparatus using the same will be described below.

First, FIG. 1 is a view showing a solid immersion lens for near-field optical pickup of a high-density optical information storage device integrated with a self-aligning opening according to the present invention.

1 shows a solid immersion lens 1 which overcomes the diffraction limit of the input light and reduces the beam size of the incident light to form near field light, a self-aligning opening 3 integrated on the solid immersion lens 1, and A near field optical pickup composed of a thin film 2 or the like in which an opening is formed is shown.

FIG. 1A shows a light aperture in which a focused laser beam is irradiated onto a hemispherical solid immersion lens 1 to form a self-aligning opening 3, and automatically aligned with a laser optical axis incident on the opening forming thin film 2. Through 3) shows the shape in which the near-field light is emitted.

1B is a cross-sectional view of the solid immersion lens in which the self-aligning opening 3 is integrated.

The present invention, unlike the prior art, has a fine opening 3 in the near-field optical pickup itself, which is automatically aligned with the optical axis, and the opening-forming thin film 2 forming the opening 3 is used for light having a specific wavelength. Photochromic materials, thermochromic materials, and phase change materials, in which light transmittance changes over a certain temperature, are used.

In this case, the information storage device which forms a self-aligning opening in the manufacturing process of the near-field optical pickup head, or has already assembled a certain energy light having a specific wavelength after the optical system assembly of the optical information storage device is completed and the optical system alignment is completed. The self-aligned opening can be obtained by irradiating the opening forming layer through the optical system for the dragon, and in both cases, the opening formed once is permanently used.

In addition, the SRENS structure in which the application to the high density optical disk is studied can also be used.

When the SRENS structure is used as a self-aligning opening forming material, an opening is formed only when recording / reproducing optical information, and the power of light is different when recording and reproducing normally. The size of the opening can vary.

2A and 2B show the structure of a floating near field optical pickup head integrated with a solid immersion lens 1 having a self-aligning opening 3 according to the present invention.

FIG. 2A is a rear perspective view of a near field optical pickup head having an automatic alignment opening according to the present invention, wherein the optical aperture-forming thin film deposited or coated on the flat surface of the solid immersion lens 1 which is processed by etching and filling ( A part of 2) is formed with an opening 3 which is automatically aligned with the optical axis of the solid immersion lens 1.

As shown in FIG. 2A, the near-field optical pickup head according to the present invention has an air-bearing surface (ABS) 12 for maintaining near-field fine gaps, and a tapered edge for supporting the head ( 13) The structure is integrated.

2B is a top perspective view of the near field optical pickup head according to the present invention showing the solid immersion lens 1 integrated in the frame 11.

3 is a cross-sectional view showing the principle of operation of the near field optical pickup head according to the present invention, in which the near field optical pickup head 10 having the self-aligning opening 3 is used to lift the near field region in the air-floating manner to the surface of the high density optical disk 20. The laser beam, which floats and is maintained by the gap 14 and passes through the optical system of the optical information storage device, passes through the solid immersion lens 1, and is then densified by the narrower near field light through the self-aligning mechanism 3. The principle of recording / reproducing optical information is shown.

As described above, the self-aligning opening may be formed in the manufacturing process of the near field pickup head 10, may be permanently formed after the assembly / alignment of the high density optical information storage device optical system is finished, and only when recording / reproducing optical information. It may be formed temporarily.

4 is a block diagram of an optical system for a high density optical information recording / reproducing apparatus of a magneto-optical method according to the present invention.

This will be described in detail according to the optical path as follows.

The input laser beam radiated from the laser light source 41 such as a laser diode is converted into parallel light by the collimator 42 and reflected by the mirror 44 to change the optical path so that the primary focusing of the near field optical pickup is performed. After passing through the lens 45 is irradiated to the near-field optical pickup head 10, passes through the solid immersion lens (1), which is suspended from the surface of the magneto-optical disk 20 to the ultra-fine gap of the near-field region, and then automatically aligned Near-field light is irradiated to the recording layer of the magneto-optical disk 20 through the formed opening 3, and a part of the input light reflected from the magneto-optical disk 20 travels back to the optical path so that the near-field optical pickup head 1, the primary The light enters the optical analyzer 46 through the focusing lens 45, the mirror 44 and the light splitter 43, and reaches the photodetector 48 through the focusing lens 47 to detect the optical signal. The information signal can be discriminated.

This process is a description of recording / reproducing optical information of the phase change method, and the same method can be applied to reproducing information recorded on an optical disc of a magneto-optical method.

On the other hand, when the optical disk is a magneto-optical system, the magnetic field can be formed by the inductor coil added to a part of the optical pickup head or the inductor coil assembled with the pickup head, and the high-density optical information of the magneto-optical method can be recorded. .

5A to 5I are cross-sectional views of the manufacturing process of the magneto-optical near-field optical pickup head 10 according to the present invention.

Such a manufacturing method is an example using a semiconductor device manufacturing process and a micromachining technique, and is a technique suitable for processing an ultra-light weight pickup head for the high-speed search required in a high density optical information storage device.

First, as shown in FIG. 5A, the first mask thin film 52 and the second mask thin film 53 for etching are formed on both surfaces of the substrate 51 such as a silicon wafer by oxidation, vapor deposition, and coating. Form each or simultaneously.

Then, as shown in FIG. 5B, the first mask thin film 52 is front side by using photolithography and a thin film etching process to form a solid immersion lens on one side of the substrate. Etch window 54 is formed.

In this case, the radius of the solid immersion lens is determined by the size of the etching window 54, and the shape of the etching window 54 is preferably circular.

As shown in FIG. 5C, a hemispherical microstructure is formed in an etching solution or gas, plasma, and the like that isotropically etches the substrate exposed through the patterned front etching window 54.

This microstructure serves as a mold 55 in which the solid immersion lens 56 is to be formed.

When the substrate is silicon, a chemical solution (Hydrofluoric Nitric Acid mixture), which is appropriately mixed with hydrofluoric acid, nitric acid, acetic acid, and water, may be used as an etching solution, and XeF ₂ may be used as an etching gas. Fully isotropic etching using fluorine base plasma generated from SF ₆ gas may be used.

Thereafter, as shown in FIG. 5D, the first mask thin film 52 is removed from the substrate surface on which the mold 55 is formed, and the material for forming the solid immersion lens 56 is filled.

In this case, a material having a high refractive index is advantageous as the solid immersion lens material, and the surface is planarized after filling the material.

Subsequently, as shown in FIG. 5E, an opening forming thin film 57 capable of forming an automatic alignment opening on the surface filled with the solid immersion lens 56 is formed by a method such as vapor deposition or application.

Next, as shown in FIG. 5F, the ABS 58 is applied to both sides of the aperture-forming thin film 57 by a shadow mask technique, a lift-off, or a screen printing method. Form.

Then, as shown in FIG. 5G, the second mask thin film 53 on the rear surface of the substrate 51 is aligned with the position of the embedded solid immersion lens 56 formed on the front surface of the substrate 51. The back etch window 59 is formed.

At this time, micromachining techniques such as double-sided alignment are utilized.

As shown in FIG. 5H, when the substrate 51 is selectively removed by the required thickness through the patterned second mask thin film 53, the near-field optical pickup head of the magneto-optical method is completed.

Here, the method of selectively etching the substrate 51 may be easily controlled by a bulk micromachining technique, and dry or wet etching may be applied.

As shown in FIG. 5I, the exposed spherical solid immersion lens 56 is irradiated with ultraviolet light (UV) or laser light having a short wavelength to form a fine self-aligning opening 60 in the region having the highest light transmission efficiency. .

As described above, the opening may be a substrate unit method of simultaneously forming a plurality of near-field optical pickup head elements formed on the same substrate in a manufacturing process, and may also be divided into a near-field separated by a method such as dicing. It is also possible to form a self-aligning opening so that the optical pickup head is assembled / aligned with the high density optical information storage optical system and then automatically aligned with the optical axis of the optical system of the information storage apparatus by irradiating a laser beam through the optical system.

In this process, a high density near field optical information storage device can be realized by attaching a small near field optical pickup device that is uniformly precisely processed in large quantities to a slider mechanism of the optical information storage device.

As described above, the optical pickup apparatus, the method of manufacturing the same, and the optical information recording / reproducing apparatus using the same have the following effects.

The near-field optical pickup device according to the present invention is formed on the surface of the solid immersion lens to manufacture the opening by the optical self-aligning characteristics that can further reduce the beam size of the near-field light, thereby further increasing the effective aberration of the near-field optical system, thereby increasing the light efficiency It is possible to implement the high density optical information recording / reproducing apparatus by increasing the height, and thereby improving the uniformity and resolution of the pickup head.

In addition, since the pickup apparatus is manufactured by using a semiconductor batch fabrication process, the manufacturing process may be simplified and mass production may be easily performed, thereby reducing the manufacturing cost of the optical pickup head.

In addition, since the solid immersion lens component is integrated into a frame such as silicon and manufactured by using a semiconductor device manufacturing process and a micromachining technology, it is possible to reduce the size and weight of the pick-up head. When combined with a slider mechanism having a precision suitable for the purpose, there is an advantage in that the seeking speed and tracking speed of the near field optical pickup head related to the access time of the information can be improved.

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 (15)

A solid immersion lens frame; A solid immersion lens (SIL) formed in the solid immersion lens frame; And a thin film formed on a lower surface of the solid immersion lens frame and having a micro-opening in a central portion thereof. The method of claim 1, The thin film is an optical pickup device, characterized in that any one of a photochromic material, a thermocromic material, a phase change material. The method of claim 1, And the opening is changed in accordance with the power of light incident on the solid immersion lens. The method of claim 1, And an air-bearing surface for supporting the solid immersion lens frame on a lower surface of the solid immersion lens frame. The method of claim 1, And a part of the lower surface of the solid immersion lens frame is inclined at an angle. The method of claim 1, The solid immersion lens frame is an optical pickup device, characterized in that the opening is formed in the center area. The method of claim 4, wherein The opening is an optical pickup device, characterized in that the side is inclined at a predetermined angle so that the upper width is wide and the lower width is narrow. The method of claim 4, wherein And the solid immersion lens is mounted in the opening. A light source module for generating light; A focusing unit for focusing the light generated from the light source module on the surface of the optical recording medium; An optical detector for converting light reflected by the optical recording medium into an electrical signal; An optical separation unit positioned between the light source module and the focusing unit to transmit light generated from the light source module to the focusing unit, and to be reflected by the optical recording medium and to transmit light passing through the focusing unit to the light detection unit; A mirror positioned between the focusing unit and the light splitting unit to change a path of incident light; And an optical pickup head portion having a solid immersion lens and a thin film having fine openings under the solid immersion lens, and precisely focusing light inputted to the solid immersion lens through the micro apertures to irradiate the optical disk. An optical information recording / reproducing apparatus, characterized by using an optical pickup device. Forming a first mask and a second mask on the lower and upper portions of the substrate, respectively; Patterning the first mask to expose a lower central portion of the substrate, and etching the exposed region to form a mold; Removing the first mask and filling a material with the mold to form a solid immersion lens; Forming a thin film on a surface of the substrate filled with the solid immersion lens; A fifth step of forming an air bearing surface (ABS) on both sides of the thin film; Patterning the second mask to expose a central portion of the upper portion of the substrate; A seventh step of removing the substrate to a predetermined thickness by etching the exposed substrate; And an eighth step of forming an opening in the thin film by irradiating light to the exposed spherical surface of the solid immersion lens. The method of claim 10, In the second step, the mold is an optical pickup device, characterized in that the isotropic etching using any one of a solution, gas, plasma. The method of claim 10, The mold has a hemispherical shape, characterized in that the optical pickup device manufacturing method. The method of claim 10, And the solid immersion lens material is formed of a material having a high refractive index. The method of claim 10, The fifth step is a method of manufacturing an optical pickup device, characterized in that using any one of a shadow mask method, a lift-off method, a screen printing method. The method of claim 10, The seventh step is a method of manufacturing an optical pickup device, characterized in that using any one of bulk micromachining technology, dry etching, wet etching.