JP4620166B2 - Near-field optical head and manufacturing method thereof - Google Patents

Description

  The present invention relates to a near-field optical head that records and reproduces information on a medium using the interaction of near-field light and a method for manufacturing the same.

  Information recording / reproducing apparatuses using light have evolved in the direction of larger capacity and smaller size, and therefore higher recording bit density is required. As countermeasures, research using blue-violet semiconductor lasers and SIL (Solid Immersion Lens) has been carried out. However, these technologies can only improve the current recording density by several times due to the problem of light diffraction limit. Absent. On the other hand, an information recording / reproducing method using near-field light is expected as a technique for handling optical information in a minute region exceeding the diffraction limit of light.

  In this technique, near-field light generated by the interaction between a minute region and an optical aperture having a size equal to or smaller than the wavelength of light formed in the near-field optical head is used. As a result, it is possible to handle optical information in a region below the wavelength of light, which is the limit in the conventional optical system, and high density of the optical memory can be expected. The principle of playback is briefly introduced. In a method generally referred to as a collection mode, first, near-field light is localized in the vicinity of the medium surface by irradiating scattered light onto the medium surface in accordance with the structure of minute marks on the medium surface. Data reproduction is possible by optically interacting the near-field light and the minute aperture to convert it into scattered light and detecting it through the aperture. In a method called illumination mode, near-field light is generated around the minute aperture by irradiating the minute aperture with propagating light. The near-field light is brought close to the media surface and interacts with minute optical information recorded on the media surface. Therefore, it is possible to reproduce the light by detecting the scattered light with a detector provided separately. Furthermore, information recording methods include irradiating the surface of the medium with near-field light generated from a minute aperture, changing the shape of a minute area on the medium (heat mode recording), This is done by changing the transmittance (photon mode recording). By using such a near-field optical head having an optical minute aperture exceeding the light diffraction limit, the recording bit density higher than that of the conventional optical information recording / reproducing apparatus can be achieved.

  When producing a near-field optical head for recording and reproducing such optical information, the formation of a minute aperture that directly affects the resolution and signal SN is an important process. As one of the methods for producing a minute opening, a method disclosed in Japanese Patent Application Laid-Open No. 52-1201 is known. In this method of making an opening, the light shielding film at the tip is plastically deformed by pressing a sharp light wave guide on which a light shielding film is deposited against a hard flat plate with a very small pressing amount well controlled by a piezoelectric actuator.

  As another method for forming an opening, there is a method disclosed in JP-A-11-265520. In this method, the opening is formed by irradiating the vicinity of the tip of the light shielding film covering the protrusion with FIB (Focused Ion Beam) from the side surface direction and removing the light shielding film at the tip of the protrusion.

Japanese Unexamined Patent Publication No. H5-21201 Japanese Patent Laid-Open No. 11-265520

  However, according to the method of Japanese Patent Laid-Open No. 5-21201, an opening can be formed only for each light guide. In addition, since it is necessary to control the push-in amount with a piezoelectric actuator having a moving resolution of several nanometers, the opening forming device must be placed in an environment that is less affected by vibrations from other devices and air. In addition, it takes time to adjust the light propagating rod so that it is perpendicular to the flat plate. In addition to a piezoelectric actuator with a small amount of movement, a mechanical translation table with a large amount of movement is required. Furthermore, a control device is required to control the push-in amount using a piezoelectric actuator having a small moving resolution, and it takes several minutes to control and form the opening. Therefore, a large-scale device such as a high voltage power supply or a feedback circuit is required for manufacturing the opening. In addition, there is a problem that the cost for forming the opening is increased.

  Further, according to the method of JP-A-11-265520, the object to be processed is a projection on a flat plate, but since the opening is formed using FIB, the time required for forming one opening is as long as about 10 minutes. . Also, in order to use FIB, the sample must be placed in a vacuum. Therefore, there is a problem that the manufacturing cost for the opening manufacturing becomes high.

  The present invention has been made in view of the above problems, and in a near-field optical head having an optical microscopic aperture and a manufacturing method thereof, a cone-shaped tip sharpened toward the medium, and the vicinity of the apex of the tip An optical aperture that interacts with the medium via near-field light, a light shielding film that covers the chip excluding the optical aperture, and a plurality of stoppers having substantially the same height as the chip. The field light head includes a step of forming an optical opening by deforming at least a part of a substantially flat plate covering at least a part of the chip and the stopper and bringing it into contact with a light shielding film near the top of the chip.

  Therefore, a minute displacement of the plane can be easily controlled by a stopper having substantially the same height as the tip, and a predetermined force can be applied to the optical minute aperture with high accuracy without requiring a special control device. A simple device can be easily manufactured in a short time, and a near-field optical head can be manufactured at low cost.

  In the step of forming the optical aperture, a plurality of optical apertures in the plurality of near-field optical heads are formed simultaneously.

  Therefore, by applying substantially the same force simultaneously to the chip and the stopper, a plurality of optical openings can be formed at one time, and the processing time per opening can be shortened. Therefore, the cost spent for opening formation can be further reduced.

  Also, there are a plurality of optical apertures in the near-field optical head, and the plurality of optical apertures are formed in the step of forming the optical aperture.

  Therefore, by simultaneously forming a plurality of openings, the opening forming process can be reduced in cost and a head with excellent mass productivity can be supplied.In addition, when the near-field optical head according to the present invention is used as an optical memory head, High-speed information can be recorded and reproduced without performing high-speed head sweeping.

  Further, the chip and the stopper are simultaneously formed in the same process. The tip and the stopper are made of the same material.

  Therefore, since the tip and the stopper can be formed simultaneously, the difference in height between the tip and the stopper can be controlled, and an optical opening of an arbitrary size can be precisely produced. This can be expected to improve the yield.

  Further, by forming the optical opening in the step of forming the optical opening, a part of the chip protrudes from a part of the light shielding film deformed by the flat plate.

  Therefore, a characteristic spatial distribution of near-field light due to the shape of the protrusion is generated, and an effective irradiation range can be determined using this. In a high-density memory, a sharpened protrusion with near-field light localized around it is placed close to the media, enabling data playback and recording with a high spatial resolution comparable to the curvature radius of the protrusion tip. High density is realized.

  Further, a part of the near-field optical head receives a levitating force due to a relative motion with the medium, and the levitating force is used as means for keeping the distance between the optical aperture and the medium constant. Further, a part of the stopper constitutes a part of the near-field optical head that receives the levitation force.

  Therefore, the high-speed processing is achieved because the distance between the medium and the distance can be kept sufficiently close while the medium is played back at high speed. In addition, downsizing is realized by adopting a configuration like a hard disk drive.

  By controlling the height of the chip 1 and the stopper 2 and the force F, the opening 8 can be easily formed without using an actuator with high resolution. Further, since the heights of the chip 1 and the stopper 2 are well controlled, the production yield of the openings 8 is improved. In addition, since the workpiece 1000 described in the first embodiment of the present invention can be manufactured by a photolithography process, a plurality of workpieces 1000 can be manufactured on a sample having a large area such as a wafer, and the force F is constant. By doing so, it is possible to form the openings 8 having a uniform opening diameter for each of the plurality of workpieces 1000 produced. In addition, since it is very easy to change the magnitude of the force F, it is possible to form the openings 8 having different opening diameters individually for a plurality of workpieces 1000 produced.

  Further, since the opening is formed by simply applying the force F, the time required for opening preparation is as short as several tens of seconds or less. Moreover, according to Embodiment 1 of this invention, a processing atmosphere is not ask | required. Therefore, it can be processed in the atmosphere, and the processing state can be immediately observed with an optical microscope or the like. Further, by processing in a scanning electron microscope, it is possible to observe the processing state with a higher resolution than that of an optical microscope. Moreover, since the liquid functions as a damper by processing in the liquid, processing conditions with improved controllability can be obtained.

  It is also possible to produce a plurality of apertures 8 having the same aperture diameter at a time by applying force F to a sample on which a plurality of workpieces 1000 are produced. In the case of batch processing, although depending on the number of workpieces 1000 per wafer, the processing time per opening is extremely short, being several hundred milliseconds or less.

  In the near-field optical head shown in the first embodiment, since the opening can be formed at the same height as the air bearing surface, the opening can be close to the medium up to the flying height of the head. Further, the shape of the minute opening formed by the manufacturing method shown in Embodiment Mode 1 protrudes from the light shielding film and the tip is sharpened, and an optical resolution (about 50 nm or less) of the tip diameter is realized. Further, the chip is a quartz material having a high light transmittance. Further, it has a refractive index of about 1.5 and is formed at an apex angle of about 90 °. When viewed from the light, the cut-off region where the light attenuation is large becomes small. As a result, the light efficiency at the aperture is improved, and high-speed reproduction or recording of minute marks becomes possible.

  Further, the near-field optical head according to the first embodiment can be manufactured by a silicon process using microfabrication represented by photolithography and the like, and is a head suitable for mass production. In addition, the method shown in FIG. 1 to FIG. 7 makes it possible to manufacture a stable and uniform size opening at a low cost, so mass production is easy, and a large number of near-field optical heads that are low in price and excellent in reliability. Can supply. Furthermore, the minute aperture can be formed stably and easily, and its optical efficiency is high, so that the recording bit density and disk diameter are reduced, and the optical recording / reproducing apparatus itself can be made smaller and lighter. .

  In addition, in the near-field optical head according to Embodiment 2, it is not necessary to form a stopper. Therefore, the yield is further improved, and a low-cost near-field optical head and high-density optical memory device can be supplied.

It is a figure explaining the formation method of the opening which concerns on Embodiment 1 of this invention. It is a figure explaining the formation method of the opening which concerns on Embodiment 1 of this invention. It is a figure explaining the formation method of the opening which concerns on Embodiment 1 of this invention. It is a figure explaining the manufacturing method of the workpiece | work 1000. FIG. It is a figure explaining the manufacturing method of the workpiece | work 1000. FIG. It is a figure explaining the relationship between the height of the chip | tip 1 and the stopper 2 in the production method of the workpiece | work 1000. FIG. It is a figure explaining the relationship between the height of the chip | tip 1 and the stopper 2 in the production method of the workpiece | work 1000. FIG. It is the schematic of the near-field optical head for recording memories which formed the optical opening with the manufacturing method which concerns on Embodiment 1 of this invention. 1 shows an example of an optical storage / reproduction device equipped with a near-field optical head for memory in which an optical aperture is formed by the manufacturing method according to Embodiment 1 of the present invention. It is the figure seen from the side surface when the near-field optical head concerning Embodiment 1 of this invention is scanned on the medium rotated at high speed. 1 shows an example of a near-field optical head structure in which an optical aperture is formed by a manufacturing method according to Embodiment 1 of the present invention. 1 shows an example of a near-field optical head structure in which an optical aperture is formed by a manufacturing method according to Embodiment 1 of the present invention. 1 shows an example of a near-field optical head structure in which an optical aperture is formed by a manufacturing method according to Embodiment 1 of the present invention. An example of a method for manufacturing a near-field optical head according to Embodiment 1 of the present invention will be described. Sectional drawing of the opening formed with the preparation method which concerns on Embodiment 1 of this invention is shown. An example of a near-field optical head structure in which an optical aperture is formed by the manufacturing method according to Embodiment 2 of the present invention will be described.

Hereinafter, a method for forming an opening according to the present invention will be described in detail with reference to the accompanying drawings.
(Embodiment 1)
First, a method for forming an aperture of a near-field optical head according to Embodiment 1 of the present invention will be described with reference to FIGS. A workpiece 1000 shown in FIG. 1 includes a transparent layer 5 formed on a substrate 4, a cone-shaped chip 1 and a ridge-shaped stopper 2 formed on the transparent layer 5, a chip 1, a stopper 2, and a transparent layer 5. The light shielding film 3 is formed on the substrate. In the work 1000, the transparent layer 5 is not necessarily required. In that case, the light shielding film 3 is formed on the chip 1, the stopper 2, and the substrate 4. Further, the light shielding film 3 may be deposited only on the chip 1.

  The height H1 of the chip 1 is several mm or less, and the height H2 of the stopper 2 is several mm or less. The difference between the height H1 and the height H2 is 100 nm or less. The distance between the tip 1 and the stopper 2 is several mm or less. The thickness of the light shielding film 3 is several tens nm to several hundreds nm although it varies depending on the material of the light shielding film 3.

The chip 1, the stopper 2 and the transparent layer 5 are made of a dielectric material having a high transmittance in the visible light region such as silicon dioxide, silicon nitride, or diamond, or a dielectric material having a high transmittance in the infrared light region such as zinc selenium or silicon. A material having a high transmittance in the ultraviolet region such as magnesium fluoride or calcium fluoride is used. The material of the chip 1 can be any material as long as it transmits the chip 1 even in the wavelength band of light passing through the opening. Moreover, the chip | tip 1, the stopper 2, and the transparent layer 5 may be comprised with the same material, and may be comprised with a different material. For example, the chip 1 may be made of silicon oxide and the stopper 2 may be made of single crystal silicon. Further, the stopper 2 may be composed of a plurality of materials such as a two-layer structure of single crystal silicon and silicon oxide. In particular, it is not necessary for the stopper 2 to transmit light, and the constituent material may include a light shielding material, for example, a metal or an alloy thereof. Of course, it does not matter if the chip is composed of many kinds of dielectrics. For the light shielding film 3, for example, a metal such as aluminum, chromium, gold, platinum, silver, copper, titanium, tungsten, nickel, cobalt, or an alloy thereof is used. The substrate 4 may be a transparent material, and the chip 1, the stopper 2, the transparent layer 5, and the substrate 4 may be the same material.

  FIG. 2 is a view showing a state in which the light shielding film 3 on the chip 1 is plastically deformed in the method of forming the opening. A plate 6 that covers a part of the chip 1 and at least the stopper 2 and is flat on at least the chip 1 and the stopper 2 side is placed on the workpiece 1000 shown in FIG. 7 is put. By applying a force F to the pushing tool 7 in the direction of the central axis of the chip 1, the plate 6 moves toward the chip 1. Compared with the contact area between the chip 1 and the plate 6, the contact area between the stopper 2 and the plate 6 is several hundred to several tens of thousands of times larger. Therefore, the applied force F is distributed by the stopper 2, and as a result, the displacement amount of the plate 6 becomes small. Since the displacement amount of the plate 6 is small, the plastic deformation amount that the light shielding film 3 receives is very small. Further, the tip 1 and the stopper 2 are only subjected to very small elastic deformation. The method of applying force F includes a method of lifting a weight having a predetermined weight by a predetermined distance and allowing it to fall freely, or a method of attaching a spring having a predetermined spring constant to the pushing tool 7 and pressing the spring by a predetermined distance. is there. The material of the plate 6 includes metals such as Al, Cr, Au, and W, dielectric materials such as silicon dioxide, silicon nitride, and diamond, semiconductor materials such as silicon, germanium, and gallium arsenide, ceramic materials, and other visible light. Transparent material is used in the area. In particular, when the plate 6 is made of a material that is harder than the light-shielding film and softer than the chip 1 and the stopper 2, the force received by the chip 1 and the stopper 2 is absorbed by the plate 6. It becomes small and it becomes easy to make the plastic deformation amount of the light shielding film 3 small.

  FIG. 3 is a view showing a state in which the plate 6 and the pushing tool 7 are removed after the force F is applied. Since the plastic deformation amount of the light shielding film 3 is very small and the chip 1 and the stopper 2 are displaced only in the elastic deformation region, an opening 8 is formed at the tip of the chip 1. The size of the opening 8 is about the diffraction limit of the wavelength of light passing through the chip 1 from several nm. In the above description, the plate 6 is inserted between the pushing tool 7 and the workpiece 1000. However, it goes without saying that the opening 8 can be formed similarly by removing the plate 6 and pushing it directly with the pushing tool 7. Absent. In order to introduce light into the opening 8, the transparent body 5 or at least a part of the chip 1 is exposed by etching the substrate 4 from the side opposite to the formation surface of the chip 1, so that the light introduction port into the opening 8 is formed. Form. It goes without saying that the step of forming the light inlet can be omitted by configuring the substrate 4 with the transparent material 103.

  As described above, according to the opening manufacturing method of the present invention, the displacement amount of the plate 6 can be well controlled by the stopper 2 and the displacement amount of the plate 6 can be made very small. A uniform and small opening 8 can be easily produced at the tip of the chip 1. Further, near-field light can be generated from the opening 8 by irradiating light from the substrate side.

  Next, the manufacturing method of the workpiece | work 1000 is demonstrated using FIG. 4 and FIG. FIG. 4 shows a state in which the transparent material 103 is formed on the substrate material 104 and then the chip mask 101 and the stopper mask 102 are formed. 4A shows a top view, and FIG. 4B shows a cross-sectional view at a position indicated by AA ′ in FIG. 4A. The transparent material 103 is formed on the substrate material 104 by vapor phase chemical vapor deposition (CVD), physical vapor deposition (PVD), or spin coating. The transparent material 103 can also be formed on the substrate material 104 by a method such as solid phase bonding or adhesion. Next, a chip mask 101 and a stopper mask 102 are formed on the transparent material 103 by a photolithography process. The chip mask 101 and the stopper mask 102 may be formed simultaneously or separately.

  The chip mask 101 and the stopper mask 102 are made of a photoresist, a nitride film, or the like, depending on the material of the transparent material 103 and the etchant used in the next process. The transparent material 103 is made of a dielectric material having high transmittance in the visible light region such as silicon dioxide or diamond, a dielectric material having high transmittance in the infrared light region such as zinc selenium or silicon, or magnesium fluoride or calcium fluoride. A material having high transmittance in the ultraviolet region is used.

  The diameter of the chip mask 101 is, for example, several mm or less. The width W1 of the stopper mask 102 is, for example, the same as or smaller than the diameter of the chip mask 101 by several tens nm to several μm. Further, the width W1 of the stopper mask 102 may be several tens nm to several μm larger than the diameter of the chip mask 101. The length of the stopper mask 102 is several tens of μm or more.

  FIG. 5 shows a state in which the chip 1 and the stopper 2 are formed. 5A is a top view, and FIG. 5B is a cross-sectional view at a position indicated by AA ′ in FIG. 5A. After the chip mask 101 and the stopper mask 102 are formed, the chip 1 and the stopper 2 are formed by isotropic etching by wet etching. The transparent layer 5 shown in FIG. 1 is formed or not formed by adjusting the relationship between the thickness of the transparent material 103 and the height of the chip 1 and the stopper 2. The tip radius of the chip 1 is several nm to several hundred nm. Thereafter, a work 1000 shown in FIG. 1 can be formed by depositing a light shielding film by a method such as sputtering or vacuum evaporation. When the light shielding film 3 is deposited only on the chip 1, in the deposition process of the light shielding film 3, a metal mask having a shape such that the light shielding film is deposited on the chip 1 is placed on the chip 1 and sputtering or vacuum evaporation is performed. Further, even if a photolithography process in which the light shielding film 3 remains only on the chip 1 after the light shielding film 3 is deposited on the entire surface of the workpiece 1000 on which the chip is formed, the light shielding film 3 is formed only on the chip 1. Needless to say, it can be formed.

  6 and 7 are diagrams for explaining the relationship between the height of the chip 1 and the stopper 2 in the method for manufacturing the workpiece 1000 described above. Hereinafter, the case where the diameter of the chip mask 101 is smaller than the width of the stopper mask 102 will be described. 6 is a view showing only the chip 1 and the stopper 2 in the process described with reference to FIG. 5A, and FIG. 7 is a view of the chip 1 at the position indicated by BB ′ in FIG. It is sectional drawing of the stopper 2 of the position shown by CC '. FIG. 7A shows a state in which the chip 1 has just been formed. Since the width of the stopper mask 102 is larger than the diameter of the chip mask 101, in the state shown in FIG. 7A, a flat portion remains on the upper surface of the stopper 2, and the stopper mask is formed on the flat portion. 102 remains. However, the chip mask 101 comes off because the contact area with the chip 1 is very small. In the state of FIG. 7A, the height H11 of the chip 1 and the height H22 of the stopper 2 are the same.

  FIG. 7B shows a state where the etching is further advanced from the state of FIG. 7A and the flat portion on the upper surface of the stopper 2 has just disappeared. When further etching is performed from the state of FIG. 7A, the height H111 of the chip 1 without the chip mask 101 gradually decreases. On the other hand, the height H222 of the stopper 2 where the stopper mask remains remains the same as H22. The width of the flat portion of the upper surface of the stopper 2 gradually decreases, and the cross-sectional shape becomes a triangle as shown in FIG. The height difference ΔH between the chip 1 and the stopper 2 at this time varies depending on the difference between the diameter of the chip mask 101 and the width of the stopper mask 102 and the tip angle of the chip 1 and the stopper 2, but is approximately 1000 nm or less. It is.

  FIG. 7C shows a state where the etching is further advanced from the state of FIG. 7B. The height H1111 of the chip 1 is lower than the height H111. Similarly, the height of the stopper H2222 is also smaller than the height H222. However, since the reduction amounts of the height H1111 and the height H2222 are the same, the height difference ΔH between the tip 1 and the stopper 2 does not change. When the width of the stopper mask 102 is smaller than that of the chip mask 101, the height relationship between the chip 1 and the stopper 2 is merely reversed. Needless to say, when the chip mask 101 and the stopper mask 102 are equal, the heights of the chip 1 and the stopper 2 are equal.

  According to the method for manufacturing the workpiece 1000 of the present invention, the height difference ΔH between the chip 1 and the stopper 2 can be satisfactorily controlled by the photolithography process. Therefore, in the opening manufacturing method described with reference to FIGS. 1 to 3, the displacement amount of the plate 6 can be well controlled.

  Next, a reproduction (information reading) and recording (information writing) method in an information recording / reproducing apparatus using a near-field optical head will be described. Although details of the vicinity of the aperture are not described, FIG. 8 shows a schematic view of a near-field optical head for high-density memory in which an optical aperture is manufactured by the method described with reference to FIGS.

  FIG. 8 shows a state of reproduction using a so-called illumination mode. Here, the light incident on the near-field optical head 11 enters from a direction substantially parallel to the medium. Of course, it may be incident from a direction substantially perpendicular to the medium or from an oblique direction. A waveguide 13 is provided in the near-field optical head 11, and light incident from the outside is propagated to the minute aperture 12 through the waveguide 13. The light irradiated to the minute opening 12 is localized near the minute opening 12 as near-field light. This near-field light is brought close to the surface of the medium 14 on which information is recorded, and the near-field light is scattered by interacting with the shape or physical optical structure of the surface of the medium 14, and the scattered propagation light. Is received by a detector 15 provided separately. Since the near-field light at this time has a resolution about the size of the minute aperture 12, minute optical information exceeding the diffraction limit of light can be reproduced.

  Further, as in the so-called collection mode, near-field light generated by irradiating the surface of the medium 14 with propagating light is scattered by interaction with the minute aperture 12, and the scattered light is propagated in the waveguide 13. Information can also be reproduced by detecting information in the same manner as described above.

  Furthermore, not only reproduction but also recording on a medium is possible. In this case, light modulated through the waveguide 13 is guided to the minute aperture 12, and near-field light is generated in accordance with the signal. If a reaction occurs on the medium 14 side by the modulated near-field light, recording becomes possible. For example, when a GeSbTe phase change film is formed on the surface of the medium 14, the GeSbTe film that is locally in an amorphous state (non-crystalline state) exceeds 180 degrees by irradiation with near-field light, and is in a crystalline state. The reflectivity increases by about 0.1 from 0.43 to 0.53. Using this characteristic, a minute mark having an opening diameter is recorded on the medium.

  Here, FIG. 9 shows an example of an optical information storage / reproduction device equipped with the near-field optical head 11. First, the scanning method will be described. The near-field optical head 11 has a flying slider structure used in an HDD, and two air bearing surfaces that receive a flying force due to an air flow are formed in a medium side surface. Therefore, as shown in FIG. 9, the near-field optical head 11 attached to the tip of the arm 16 has a distance from the medium 14 due to the flying force received by the fluid motion of air generated by high-speed rotation and the load applied by the arm 16. It becomes possible to always keep constant. For seek and tracking, the near-field optical head 11 can be scanned at an arbitrary position on the medium 14 and the track can be followed by moving the arm 16 in the medium radial direction by a rotating shaft 17 with a motor. . Next, a light propagation method will be described. First, although not shown in the drawing, light oscillated from a small semiconductor laser propagates through the optical waveguide 18 attached in the arm 16 and is guided into the near-field optical head 11. This light passes through the waveguide 13 in the near-field optical head 11 and irradiates the minute opening 12 formed in the surface on the medium side. The light is converted into near-field light in the vicinity of the minute aperture 12. When the medium 14 is in the state of being close to the minute opening 12, an interaction occurs between the near-field light and the minute region on the surface of the medium 14, and the near-field light is scattered. Although not shown in the figure, the scattered light is received by a light receiving element provided in the near-field optical head 11, in the vicinity of the near-field optical head 11, or on the back side of the disk 14. The optical information scattered by the light receiving element is converted into an electric signal and reproduced through a signal processing circuit.

  Next, FIG. 10 shows a view of the posture when the near-field optical head is slightly flying above the medium rotating at high speed, as seen from the side. When the medium 14 is rotated at high speed, air fluid motion occurs between the near-field optical head 11 and the medium 14. As a result, the medium-side surface of the near-field optical head 11 receives a large pressure from the medium 14 side, and the near-field optical head 11 floats. On the contrary, by applying a constant load to the near-field optical head 11 from the arm 16 side toward the medium 14 with respect to this levitation force, the balance of force is maintained and the distance from the surface of the medium 14 is always kept constant. Is possible. FIG. 10 shows the posture of the near-field optical head 11 at this time. When the medium 14 moves in the direction of the white arrow, an air flow is generated between the medium 14 and the near-field optical head 11, and the inlet side (inflow) is determined from the distribution of pressure applied to the air bearing surface 19 at that time. At the end, the distance from the medium 14 is larger than at the outlet side (outflow end). Therefore, the head itself is inclined as shown in FIG. 10, and the distance between the air bearing surface 19 and the medium 14 is reduced at the outflow end side of the air flow. By providing the minute openings 12 at the small intervals, the distance between the minute openings 12 and the medium 14 is closer, and information can be reproduced with high resolution.

  Next, FIG. 11 shows an example of a near-field optical head in which an optical aperture is manufactured by the method described with reference to FIGS. In FIG. 11, the surface of the near-field optical head 20 facing the medium is drawn as the upper surface. The near-field optical head 20 includes a micro-opening 24 for generating / detecting near-field light, a chip 21 formed at the apex of the micro-opening 24 and propagating light to the micro-opening 24, and not shown in the drawing. A metal film that covers the chip except for the minute opening 24 and shields light and collects light to the opening, a stopper 22 that plays a role in making the opening, and a floating force from the media direction It is comprised with the air bearing surface 23 to receive.

  In order to reproduce information using near-field light, it is necessary to bring the minute aperture 24 close to the medium so that the near-field light localized in the vicinity of the minute aperture 24 interacts with the optical information on the medium. Furthermore, it is required to scan at high speed and keep the distance constant. Therefore, two air bearing surfaces 23 as shown in FIG. 11 are provided in the surface of the near-field optical head facing the medium. As shown in FIG. 10, the air bearing surface 23 receives a constant flying pressure due to the relative movement with the medium, and the near-field optical head 20 provided with the air bearing surface 23 can hold a minute flying height. The flying height (the distance between the air bearing surface and the medium) can be controlled to 100 nm or less. Here, by making the height of the air bearing surface 23 and the height of the chip 21 substantially coincide with each other, the distance between the minute opening and the medium can always be brought close to stably and high-speed scanning can be performed.

  The minute aperture of the near-field optical head in FIG. 11 is formed by a method of deforming the light shielding film at the tip of the chip using the stopper 22 as described in FIGS. Therefore, a stopper 22 having a height substantially the same as that of the chip is provided around the chip 21. As in FIG. 6, four stoppers are formed around the chip. Here, in order to form the minute opening 24, it is necessary to form the chip 21 and the stopper 22 at substantially the same height, and in order to make the opening close to the medium, the chip 21 and the air bearing surface 23 are formed. Must be formed at approximately the same height. The heights of the stopper 22, the chip 21, and the air bearing surface 23 can be aligned by forming the same material and etching simultaneously.

  Further, in the near-field optical head 20 shown in FIG. 11, four stoppers 22 are arranged like a cross when viewed from above the chip 21, but 3 like the near-field optical head 30 shown in FIG. 12. A book stopper 25 may be formed. Of course, the number is not limited to three or four, and a plurality of more may be formed. Alternatively, like the near-field optical head 40 shown in FIG. 13, one stopper 26 may be formed in a donut shape with the chip at the center. These stoppers are arranged so that the distance from the chip to each stopper is the same. This is because the push-in amount of the push-in jig is maximized when the distance from each stopper is equidistant, and the amount can be controlled.

  Here, an example of a manufacturing method of the near-field optical head according to Embodiment 1 described in FIG. 11 will be described with reference to FIG. FIG. 14 shows a cross section of AA ′ in FIG. First, a transparent material is selected for the substrate 51 (FIG. 14-P101). Glass, quartz, and other optical materials that are transparent in the ultraviolet, visible, and infrared bands are suitable. In particular, the case where a quartz substrate is selected will be described here. Next, as shown in FIG. 14-P102, a mask pattern 52 for a chip, a stopper, and an air bearing surface is formed by a photolithography process used in a semiconductor process. A photosensitive photoresist is used as the mask material, and the mask pattern 52 with high dimensional accuracy can be formed by using a photolithography technique of a semiconductor process. In consideration of adhesion with silicon oxide, it is preferable to use a negative resist, but of course, a positive resist may be used. The thickness of the resist is suitably about 1 μm that can easily control the thickness variation. When silicon nitride is used as a mask material, the mask pattern 52 is formed by laminating silicon nitride on the substrate and processing the silicon nitrogen in accordance with the photoresist pattern formed in the photolithography process. The The shape of the mask pattern 52 for chips and stoppers is almost the same as that in FIG.

  Next, as shown in FIG. 14-P103, the quartz base 51 plate is etched to form the chip 53, the stopper 54, and the air bearing surface 55 on the surface. Thereafter, the state where the mask material is peeled off is the state shown in FIG. 14-P103. As shown in FIG. 14-P103, when observing from the cross-sectional direction of the substrate 51, the chip 53 gradually increases in height from a trapezoid with a low height, and the upper side becomes shorter, and then the triangular chip 53 is formed. It becomes. When the trapezoidal shape changes to a triangle, the height of the apex of the chip 53 coincides with the height of the stopper 54 and the air bearing surface 55, and the etching is finished at this time. The apex angle of the chip 53 can be manufactured in the range of 110 to 70 °. This adjustment of the angle is realized by controlling the adhesion between the mask pattern 52 and the quartz substrate 51. For the etching, either wet etching or dry etching may be used. In wet etching, buffer hydrofluoric acid (mixed solution of hydrofluoric acid and ammonium fluoride) is used as an etchant, and an arbitrary chip is formed by controlling the amount of underetching. In dry etching, the gas type, flow rate selection, RF power of plasma, and degree of vacuum slightly affect the chip shape. In this dry etching, etching using a chemical reaction with a fluorinated gas or a chloride gas may be used, or etching using a physical reaction such as sputtering may be used.

  Next, as shown in FIG. 14-P104, a metal film 56 that shields the chip 53 is laminated on the entire chip-side surface. As a lamination method, a vacuum deposition method, a sputtering method, an ion plating method, a plating method, or the like is used. The vacuum deposition method is mainly used because it can be thinly and uniformly laminated and the grain can be kept small. By this lamination method, the film is laminated to an arbitrary thickness in the range of about 100 nm to 1 μm. Aluminum, gold, silver, copper, platinum, titanium, tungsten, chromium, and their alloys are the main materials to be laminated, but a small amount of silicon is used to improve adhesion and suppress grain. In some cases, impurities such as

  Next, as shown in FIG. 14-P105, the metal film 56 laminated at a place other than the chip 53 is removed. A mask pattern is formed only on the chip 53 by photolithography, and the metal film 56 exposed in the remaining portion is removed by etching, and then the mask is removed to leave the metal film 56 only on the chip 53. By removing the metal film 56 on the air bearing surface 55 or the stopper 54, the height of the apex of the chip 53 and the height of the air bearing surface 55 or the stopper 54 can be maintained.

  Finally, as shown in FIG. 14-P106, an optical opening 57 is formed at the apex of the chip 53 by the method described with reference to FIGS. The details are omitted here.

  In this manner, a near-field optical head having a minute aperture can be manufactured with high productivity. Here, FIG. 15 shows a cross-sectional view of the opening formed by the manufacturing method described with reference to FIGS. FIG. 15A shows a state in which the metal film 59 is pushed in by the deformed plate 58 pushed by the pushing jig, and the chip 60 itself is also elastically deformed. In FIG. The state after removing is shown. When the tip of the chip 60 comes into contact with the plate 58 and a force is applied from above, the metal film 59 near the tip of the chip 60 undergoes plastic deformation, and the metal film 59 near the tip of the chip 60 is deformed as shown in FIG. The tip 60 is driven to the periphery, and the tip of the tip 60 directly contacts the plate 58. The force transmitted from the pushing jig to the plate 58 is also applied to the chip 60 itself, and the chip 60 is elastically deformed by the force and contracts somewhat. When the plate 58 is removed from this state, the metal film 59 remains in the shape of being driven around while being plastically deformed, but the elastically deformed tip 60 is released and returns to its original shape. As a result, as shown in FIG. 15B, the tip of the chip 60 has a shape protruding slightly from the metal film 59.

  Near-field light is generated around the protruding chip. The top of the chip is formed at the same height as the air bearing surface by the manufacturing method described with reference to FIG. 14, and the near-field light generated around the chip can be brought close to the flying height of the head amount to the same distance. . Depending on the design of the air bearing surface, a flying height of 20 nm or less is possible, and the medium can be irradiated without increasing the beam spot diameter of near-field light generated around the aperture. The resolution also depends on the radius of curvature of the sharpened tip apex. Since the tip diameter of the chip can be manufactured to 50 nm or less, it is possible to realize the optical resolution (50 nm or less) corresponding to it. A quartz chip is formed with an apex angle of about 90 °. Light propagates in the chip having a refractive index of about 1.46 and an apex angle of 90 °, and reaches the aperture. Before reaching this aperture, large light attenuation occurs in the sub-wavelength region (cut-off region), but due to this high refractive index and wide apex angle, the cut-off region is reduced when viewed from the light. As a result, the light efficiency at the aperture is improved.

  As described above, in the method of manufacturing the near-field optical head described in the first embodiment, a stopper is provided in the head, the stopper is formed at the same height as the chip 1, and the stopper 2 is used. Since the displacement amount of the plate 6 can be reduced, it is easy to form the minute opening 8 having a uniform size at the tip of the chip 1 without using an actuator with high resolution. Further, since the heights of the chip 1 and the stopper 2 are well controlled, the production yield of the openings 8 is improved. Further, since the workpiece 1000 can be manufactured by a photolithography process, a plurality of workpieces 1000 can be manufactured on a sample having a large area such as a wafer, and a plurality of workpieces 1000 manufactured by keeping the force F constant. An opening 8 having a uniform opening diameter can be formed for each. In addition, since it is very easy to change the magnitude of the force F, it is possible to form the openings 8 having different opening diameters individually for a plurality of workpieces 1000 produced. Further, since the opening 8 is formed by simply applying the force F, the time required for making the opening is very short, from several seconds to several tens of seconds. Further, in such a manufacturing method, a processing atmosphere is not limited. Therefore, it can be processed in the atmosphere, and the processing state can be immediately observed with an optical microscope or the like. Further, by processing in a scanning electron microscope, it is possible to observe the processing state with a higher resolution than that of an optical microscope. Moreover, since the liquid functions as a damper by processing in the liquid, processing conditions with improved controllability can be obtained. It is also possible to produce a plurality of apertures 8 having the same aperture diameter at a time by applying force F to a sample on which a plurality of workpieces 1000 are produced. In the case of batch processing, although depending on the number of workpieces 1000 per wafer, the processing time per opening is extremely short, being several hundred milliseconds or less.

  In an optical memory device using near-field light, the optical resolution greatly depends on the proximity distance and the aperture shape. In the near-field optical head shown in the first embodiment, since the opening can be formed at the same height as the air bearing surface, the opening can be close to the medium up to the flying height of the head. Moreover, the opening shape protrudes from the light shielding film and the tip is sharpened (50 nm or less). Near-field light is generated with a distribution depending on the tip diameter. In the near-field optical head shown in the first embodiment, the sharpened tip can be finely levitated, and when the opening is miniaturized, an optical resolution (50 nm or less) of the tip diameter is realized. Furthermore, in the near-field optical head shown in the first embodiment, the chip has a refractive index of about 1.46 and is formed at an apex angle of about 90 °, and has a large light attenuation when viewed optically. The cut-off area becomes smaller. Quartz is a material with high light transmittance. For this reason, the light efficiency at the aperture is improved, and high speed reproduction and recording are possible.

Further, the near-field optical head according to the first embodiment can be manufactured by a silicon process using microfabrication represented by photolithography and the like, and is a head suitable for mass production. In addition, the method shown in FIG. 1 to FIG. 7 makes it possible to manufacture a stable and uniform size opening at a low cost, so mass production is easy, and a large number of near-field optical heads that are low in price and excellent in reliability. Can supply. Further, since the minute openings can be formed stably and easily, the recording bit density and the disk diameter can be reduced, and the optical recording / reproducing apparatus itself can be reduced in size and weight.
(Embodiment 2)
FIG. 16 shows a schematic diagram of a near-field optical head according to the second embodiment. In FIG. 16, the air bearing surface 27 and the chip 28 are drawn as the upper surface. In the near-field optical head 50 according to the second embodiment, a groove 29 is formed in a part of the air bearing surface 27, and a chip 28 is formed in the part of the groove 29. The stopper shown in the first embodiment is not formed. In FIG. 16, a circular groove 29 is formed. However, the groove is not limited to a circle, and may be a triangle, a rectangle, or a polygon. However, the tip 28 is always placed in the center. In FIG. 16, two grooves 29 are drawn, but the number is not limited to two, and one or a plurality of grooves may be formed. However, in order to maintain the left and right balance of the levitation force received by the air bearing surface 27, it is desirable to form grooves 29 at the same position on the two air bearing surfaces 27 as shown in FIG. The position of the groove 29 was determined from the position of the chip 28. As shown in FIG. 10, the air bearing surface 27 is closer to the medium on the fluid outflow end side. The tip 28 is preferably located on the outflow end side of the air bearing surface 27. Therefore, in FIG. 16, a groove 29 is formed at a position corresponding to the position of the chip 28. The size of the groove 29 is designed in consideration of the floating force received by the air bearing surface 27, and the diameter and the size of one side are about 10 μm to 300 μm.

  In the near-field optical head according to the second embodiment, the stopper as in the near-field optical head according to the first embodiment is not formed. A part of the air bearing surface 27 also serves as a stopper in forming the opening. The manufacturing method of the near-field optical head according to the second embodiment is the same as the manufacturing method of the near-field optical head according to the first embodiment, and is manufactured by the process shown in FIG. They are formed at almost the same height. Therefore, the stopper is not formed, but the air bearing surface 27 formed around the chip 28 plays the same role as the stopper, and the plate pushed by the pushing jig covers the air bearing surface 27 and the chip 28, A part of the air bearing surface 27 is deformed as a fulcrum, and comes into contact with the metal film at the apex of the chip 28. The chip 28 is formed at a position where the displacement amount of the plate is maximum and is displaced in parallel with the substrate, that is, substantially at the center of the groove 29 formed in the air bearing surface 27.

  Further, the light shielding film on the air bearing surface 27 may or may not be provided. When there is no light-shielding film, when light leaked from the air bearing surface 27 is detected by a detector, a pinhole is inserted in the vicinity of the detector to reduce the cause of disturbance.

  As described above, in the near-field optical head according to Embodiment 2, a part of the air bearing surface serves as a stopper and does not form a stopper. Therefore, it is not necessary to form a stopper, it is only necessary to match the height of the air bearing surface and the height of the chip, and the manufacturing process is simplified. Further, the opening forming method is the same as that of the first embodiment, and the effect is also the same.

1, 2, 28, 53, 60 Chip 2, 22, 25, 26, 54 Stopper 3 Light-shielding film 4, 51 Substrate 5 Transparent layer 6, 58 Plate 7 Pushing tool 8, 57 Opening 11, 20, 30, 40, 50 Near-field optical head 12, 24 Micro-aperture 13 Waveguide 14 Media 15 Detector 16 Arm 17 Rotating shaft 18 Optical waveguide 19, 23, 27, 55 Air bearing surface 29 Groove 52 Mask pattern 56, 59 Metal film 101 Chip mask 102 Stopper mask 103 Transparent material 104 Substrate material 1000 Work F Force H1 Chip height H2 Stopper height

Claims (5)

A substrate,
A cone-shaped chip provided on the substrate and sharpened toward the medium;
A light-shielding film covering the chip ;
An air bearing surface disposed around the chip, the height from the substrate being the same as the height of the apex of the chip from the substrate, and generating a levitation force by an air flow from the media; A floating slider structure having,
The light-shielding film near the apex of the chip is plastically deformed to protrude from the light-shielding film, and a minute aperture that generates near-field light,
A near-field optical head characterized in that the near-field optical head is formed in the vicinity of the minute opening, and the light-shielding film includes a plastically deformed convex portion .   The near-field optical head according to claim 1, wherein the chip and the floating slider structure are made of the same material. A substrate,
A cone-shaped chip provided on the substrate and sharpened toward the medium;
A light-shielding film covering the chip ;
An optical aperture for generating near-field light from the apex portion of the chip;
Are disposed around the chip, the height from the substrate, the stopper Ru height and same der of the tip apex of from the substrate,
The light-shielding film near the apex of the chip is plastically deformed to protrude from the light-shielding film, and a minute aperture that generates near-field light,
Protrusions made near the micro-openings, and the light-shielding film is plastically deformed;
Compared to the stopper, near-field optical head characterized by comprising a floating slider structure having an air bearing surface that contributes to the generation of by that floating force the airflow from said media.   4. The near-field optical head according to claim 3, wherein the chip and the stopper are made of the same material.   The near-field optical head according to claim 1, comprising a plurality of the optical apertures.

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