JP4450977B2 - Optical aperture manufacturing method and optical aperture manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an optical aperture. In particular, the present invention relates to a method for manufacturing an aperture used in a near-field optical device that irradiates and detects near-field light.
[0002]
[Prior art]
A scanning probe microscope (SPM) typified by a scanning tunneling microscope (STM) or an atomic force microscope (AFM) is used to observe a minute region on the order of nanometers on the sample surface. SPM scans a sample surface with a probe with a sharpened tip, and observes the interaction between the probe and the sample surface, such as tunneling current and atomic force, with an image of resolution depending on the probe tip shape. However, restrictions on the sample to be observed are relatively severe.
[0003]
Therefore, the near-field optical microscope (SNOM), which enables observation of a minute region on the sample surface by focusing on the interaction between the near-field light generated on the sample surface and the probe, is drawing attention. Has been.
[0004]
In the near-field optical microscope, the surface of the sample is irradiated with near-field light from an opening provided at the tip of a sharpened optical fiber. The aperture has a size equal to or smaller than the diffraction limit of the wavelength of light introduced into the optical fiber, and has a diameter of about 100 nm, for example. The distance between the opening formed at the probe tip and the sample is controlled by the SPM technique, and the value is equal to or smaller than the size of the opening. At this time, the spot diameter of the near-field light on the sample is substantially the same as the size of the opening. Therefore, it is possible to observe the optical properties of the sample in a minute region by scanning near-field light irradiated on the sample surface.
[0005]
In addition to being used as a microscope, by introducing relatively high intensity light toward the sample through the optical fiber probe, near-field light having a high energy density is generated at the opening of the optical fiber probe, and the sample surface is generated by the near-field light. The present invention can also be applied as a high-density optical memory recording that locally changes the structure or physical properties. In order to obtain near-field light with high intensity, attempts have been made to increase the tip angle of the probe tip.
[0006]
In these devices using near-field light, the formation of openings is the most important. As one of the methods for forming the opening, a method disclosed in Japanese Patent Laid-Open No. 5-21201 is known. In the method of manufacturing an opening disclosed in Japanese Patent Laid-Open No. 5-21201, a sample in which a light shielding film is deposited on a sharpened light wave guide is used as a sample for forming an opening. In the manufacturing method of the opening, the light shielding film at the tip is plastically deformed by pressing a sharpened light wave guide with a light shielding film against a hard flat plate with a very small pressing amount well controlled by a piezoelectric actuator.
[0007]
As a method for forming the opening, there is a method disclosed in JP-A-11-265520. In the method of manufacturing an opening disclosed in Japanese Patent Laid-Open No. 11-265520, a target for forming an opening is a projection tip formed by a focused ion beam (FIB) on a flat plate. The opening is formed by irradiating the light shielding film at the tip of the protrusion with FIB from the side surface and removing the light shielding film at the tip of the protrusion.
[0008]
[Problems to be solved by the invention]
However, according to the method disclosed in Japanese Patent Laid-Open No. 5-21201, an opening can be formed only for each light guide. Further, according to the method of Japanese Patent Laid-Open No. 5-21201, it is necessary to control the pushing amount by a piezoelectric actuator having a moving resolution of several nanometers, so that the opening forming device is less influenced by vibrations of other devices and air. It must be smelled. 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. Further, there is a problem that the cost for forming the opening is increased.
[0009]
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.
[0010]
[Means for Solving the Problems]
The present invention has been made in view of the above problems,
In the method of manufacturing an optical opening for forming an optical opening at the tip of a cone-shaped chip, the chip, and
At least with respect to an opening forming body made of a light shielding film formed on the chip,
A pushing body having a stopper projecting in the direction of the opening forming body at substantially the same height as the tip;
The optical opening is formed by displacing with a force having a component toward the chip to form an optical opening at the tip of the chip.
[0011]
Therefore, according to the optical aperture manufacturing method of the present invention, since the displacement of the plane is controlled by the stopper having substantially the same height as the chip, simply pressing the plane with a predetermined force makes it easy to optically A typical opening can be made. In addition, the opening can be formed under various environments such as vacuum, liquid, and air. In addition, since no special control device is required when producing the optical aperture, the device for producing the optical aperture can be simplified. In addition, the time for applying the predetermined force can be easily shortened, and the time required for opening preparation can be shortened. Therefore, the cost required for opening preparation can be reduced.
[0012]
In addition, the optical opening is made by a method in which the pusher is made of a material softer than the material of the chip.
[0013]
Therefore, the tip end is not deformed when the pusher removes the light shielding film, and as a result, an opening having a structure in which the tip end protrudes into the opening can be produced.
[0014]
Further, in the method for producing an optical opening, the pusher has a substantially flat surface in contact with the chip and the stopper.
[0015]
Therefore, since the push-in amount is determined only depending on the difference between the chip height and the stopper height, it is possible to stably produce an opening of a certain size.
[0016]
And a method for producing an optical aperture, comprising a method of adjusting a position at which the force is applied so that the force is applied to a portion of the pusher that is substantially above the tip of the tip. did.
[0017]
Therefore, since the force is always controlled at the tip of the chip, an optical opening having a desired size can be stably produced.
[0018]
Also, the optical aperture manufacturing method is characterized in that the opening forming body is formed on a substantially flat substrate.
[0019]
Therefore, it is possible to produce a large number of the above-mentioned openings to be formed using existing semiconductor process technology, and it is possible to produce optical openings by an inexpensive and stable method.
[0020]
The method for adjusting the position where the force is applied uses an alignment mark provided on the substrate.
[0021]
Therefore, the position where the force is applied can be easily determined, and the optical aperture can be produced at a low cost.
[0022]
In addition, the method for producing an optical opening is characterized in that the pusher is made of an optically transparent material.
[0023]
Therefore, when a force is applied to the pusher, the position of the tip below the pusher can be confirmed, and since the same force always acts on the tip of the tip, a fixed-size opening is stably produced. be able to.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
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)
1 to 3 are diagrams for explaining a method of forming an opening according to the first embodiment of the present invention. A workpiece 1000 shown in FIG. 1 includes a transparent layer 5 formed on a substrate 4, a cone-shaped chip 1 formed on the transparent layer 5, and a light shielding film 3. In the workpiece 1000, the transparent layer 5 is not necessarily required. In that case, the light shielding film 3 is formed on the chip 1 and the substrate 4. Further, the light shielding film 3 may be deposited only on the chip 1. The plate 6 shown in FIG. 2 has a stopper 2 formed thereon. In FIG. 2, two stoppers are formed, but a larger number may be formed. The distance between the stoppers is longer than the length of the bottom side of the chip 1 in FIG. 1, for example, several to several hundred microns longer. 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 1000 nm or less. Further, 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.
[0025]
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 or diamond, a dielectric material having a high transmittance in the infrared light region such as zinc selenium or silicon, or magnesium fluoride. A material having a high transmittance in the ultraviolet light region such as calcium 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 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.
[0026]
FIG. 3 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 having a stopper 2 is placed on the workpiece 1000 shown in FIG. 1, and a pushing tool 7 is placed on the plate 6. At this time, transparent glass was used for the plate 6. Even after the plate 6 is placed, the position of the chip 1 can be confirmed by a microscope or visually. In the present embodiment, the positions of the chip 1 and the pushing tool 7 are confirmed from two directions with a microscope, and the pushing tool 7 is arranged directly above the chip 1. 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. When the plate 6 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, so that the displacement amount of the plate 6 becomes smaller. It becomes easy to reduce the amount of plastic deformation of the light shielding film 3.
[0027]
FIG. 4 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 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. Further, by forming the substrate 4 from the transparent material 103, the step of forming the light inlet can be omitted.
[0028]
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.
[0029]
Next, a method for manufacturing the workpiece 1000 will be described. FIG. 5 shows a state where the chip mask 101 is formed after the transparent material 103 is formed on the substrate material 104. FIG. 5A shows a top view, and FIG. 5B shows a cross-sectional view at a position indicated by AA ′ in FIG. 5A. The transparent material 103 is formed on the substrate material 104 by chemical vapor deposition (CVD) 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 is formed on the transparent material 103 by a photolithography process.
[0030]
The chip mask 101 uses 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.
[0031]
The diameter of the chip mask 101 is, for example, several mm or less. FIG. 6 shows a state in which the chip 1 is formed. 6A is a top view, and FIG. 6B is a cross-sectional view at a position indicated by AA ′ in FIG. 6A. After the chip mask 101 is formed, the chip 1 is formed by isotropic etching by wet etching. By adjusting the relationship between the thickness of the transparent material 103 and the height of the chip 1, the transparent layer 5 shown in FIG. 1 is formed or not formed. 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. Can be formed.
[0032]
The plate 6 shown in FIG. 2 can be manufactured by the same method as that for the workpiece 1000. Since the only difference is the shape of the mask, the description of the manufacturing method is omitted. However, the workpiece 1000 and the plate 6 are made of the same material, for example, and are manufactured by etching the same amount by etching with the same etchant for the same time. . By using different size masks, the difference between the height H1 of the chip 1 and the height H2 of the stopper 2 can be formed to a desired value.
[0033]
As described above, according to the first embodiment of the present invention, the height of the chip 1 and the stopper 2 can be controlled well, and the displacement amount of the plate 6 is reduced by providing the stopper 2. Therefore, it is easy to form a minute opening 8 having a uniform size at the tip of the chip 1 without using an actuator with high resolution. In our experiment, it was possible to form the opening 8 having a diameter of 100 nm or less simply by striking the pushing tool 7 with a hand-held hammer. 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 8 is formed simply by applying the force F, the time required for opening preparation is very short, from several seconds to several tens of seconds. 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.
[0034]
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.
(Embodiment 2)
FIG. 7 shows a tip shape of a chip manufactured by the method according to Embodiment 2 of the present invention. The difference from the first embodiment is that the material of the plate 6 is made harder and softer than that of the chip 1, and the other steps are the same as in the first embodiment. Since it is the same as that, the description is omitted. FIG. 7A shows the shape of the tip of the chip produced when the material of the plate 6 is harder than the material of the chip 1, and FIG. 7B shows the shape of the material produced when the material of the plate 6 is softer than the material of the chip 1. The tip shape of the chip. In (a), the tip of the chip is flat, and when this is used as a near-field optical probe in a near-field optical microscope or near-field optical data storage device, the optical aperture is very close to the sample surface or recording medium surface. It is possible to make it close. As a result, stronger near-field light interaction can be caused, a high S / N ratio can be obtained, or high-speed data transfer can be achieved. Further, when a conductive material is present on the sample surface or the recording medium surface, the interaction with the break of the light-shielding film 3 at the tip of the chip 1 is enhanced, thereby further increasing the near-field light interaction. Become. On the other hand, in the case of (b), there is a protrusion 11 at the tip of the chip. The near-field light can have a resolution depending on the structure size when a minute structure is present in the aperture. However, if the projection 11 is present as shown in FIG. Bring improvement. Thus, by changing the material of the plate 6, a chip having a desired shape can be easily produced.
(Embodiment 3)
FIG. 8 is a diagram for explaining a method of manufacturing an optical aperture according to Embodiment 3 of the present invention. FIG. 8 is a top view of a part of a wafer formed by arranging a large number of chips 1 and alignment marks 112. The alignment mark 112 is made of the same material as the chip 1 and is formed simultaneously with the formation of the chip 1. Since the alignment mark mask is designed to have a smaller width than the chip mask, the alignment mark 112 is lower than the chip 1 and contacts the plate 6 when the plate 6 is pressed against it. Never do. The alignment mark 112 can also be produced by patterning the light shielding film 3. After that, an opening is formed by basically the same method as in the first embodiment. However, when the plate 6 is placed on the chip 1, the alignment mark 112 is confirmed visually or with a microscope, and the force F is substantially equal to that of the chip 1. Take it from above. This facilitates the alignment of the pushing tool 7 and makes it possible to produce an optical aperture with a stable size in a short time.
[0035]
【The invention's effect】
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.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a method for forming an opening according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a plate used in Embodiment 1 of the present invention.
FIG. 3 is a diagram illustrating a method for forming an opening according to the first embodiment of the present invention.
FIG. 4 is a diagram for explaining a method of forming an opening according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating a method for manufacturing a workpiece 1000;
6 is a diagram illustrating a method for manufacturing the workpiece 1000. FIG.
FIG. 7 is a diagram illustrating a tip shape according to a second embodiment of the present invention.
FIG. 8 is a top view of a part of a wafer formed with a large number of chips and stoppers used in the third embodiment of the present invention.
[Explanation of symbols]
1 chip 2 stopper 3 light shielding film 4 substrate 5 transparent layer 6 plate 7 pushing tool 8 opening 101 chip mask 103 transparent material 104 substrate material 112 alignment mark 1000 work F force H1 chip height H2 height of stopper

Claims (7)

An optical opening that forms an opening by plastically deforming the light-shielding film by bringing a pusher into contact with the tip of the near-field optical device having a cone-shaped chip and the light-shielding film provided on the chip. In the production method of
Forming an opening forming body having the near-field optical device on a substantially flat surface;
The pusher is provided with a stopper that is formed on a substantially flat surface and has a contact portion that is substantially the same height as the tip, and the contact portion controls the displacement of the pusher. With the substantially flat surface of the push-in body and the contact portion facing the light-shielding film on the chip and the substantially flat surface of the opening forming body, the push-in body faces the chip. Contact with the object to be opened by a force having a component
It allows a manufacturing method of optical aperture, characterized by forming the opening in the tip distal end.   The method for producing an optical aperture according to claim 1, wherein the pusher is made of a material softer than a material of the chip. 3. The method according to claim 1, further comprising a method of adjusting a position at which the force is applied so that the force is applied to a portion of the pusher that is substantially above the tip of the tip. 4. A method for producing an optical aperture. The method for manufacturing a optical aperture according to any one of claims 1 to 3, characterized in that the opening forming member is one formed on a substrate of a substantially flat plate shape. 5. The method for producing an optical aperture according to claim 4 , wherein the method for adjusting the position to which the force is applied uses an alignment mark provided on the substrate. The impactor is, a manufacturing method of optical aperture according to any one of claims 1 to 5, characterized in that it consists of an optically transparent material. A manufacturing apparatus of optical aperture using the method according to any one of claims 1 to 6
A pusher having a stopper formed on a substantially flat surface and having a contact portion of approximately the same height as the tip;
The contact portion controls the displacement of the pusher,
The pushing body is moved to the contact portion by a force having a component facing the chip in a state where the substantially flat surface of the push body and the stopper face the light shielding film and the contact portion on the chip, respectively. Is in contact with
A manufacturing apparatus for manufacturing the opening at the tip of the chip by displacing the pusher.

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