JP3781407B2 - Photonic crystal optical element and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photonic crystal optical element and a photonic crystal optical element manufacturing method capable of introducing different materials into a photonic crystal in the field of optoelectronics.
[0002]
[Prior art]
In the field of optoelectronics, the use of photonic crystals is being studied for the miniaturization and integration of optical elements. In particular, in order to realize a micro optical active element, it is necessary to be able to arbitrarily introduce a different material into the photonic crystal. Two-dimensional photonic crystals and three-dimensional photonic crystals are currently being studied.
[0003]
The two-dimensional photonic crystal is expected to be applied to a planar optical circuit. The two-dimensional photonic crystal has a basic structure of a periodic arrangement of pores, but when creating a photonic crystal optical element, a part of the pores are selectively filled to change the refractive index, It is necessary to provide functionality.
[0004]
A conventional method for producing a two-dimensional photonic crystal optical element will be described with reference to FIG.
FIG. 10 is a schematic view of a method for producing a two-dimensional photonic crystal optical element.
As shown in FIG. 10, the substrate 01 is patterned by electron beam exposure or the like, and a metal mask 02 is formed on the substrate 01. Next, the photonic crystal is manufactured by forming the vertical through hole 03 by etching.
[0005]
Here, at the time of the above patterning, the optical waveguide portion 04 is formed by leaving a portion where the pores are not formed in a part of the substrate 01, and the sharp bend waveguide 04 that is a feature of the photonic crystal optical device is manufactured. can do. Further, by using a semiconductor material, a non-linear material, a light emitting material, or the like for the substrate 01, it is possible to give the optical waveguide part functionality or to produce a light emission center in the photonic crystal.
[0006]
By combining these, an integrated optical circuit using a two-dimensional photonic crystal optical element can be realized.
[0007]
[Problems to be solved by the invention]
By the way, as described above, in order to realize an integrated optical circuit using a two-dimensional photonic crystal optical element, it is necessary to provide various functions in the photonic crystal. Therefore, it is required that materials having different properties can be arbitrarily introduced into the photonic crystal.
[0008]
However, materials other than the material constituting the photonic crystal cannot be arbitrarily introduced by the manufacturing method according to the prior art shown in FIG. This is because it is difficult to perform microfabrication such as introducing a material other than the crystal constituent material into the vertical hole 03 formed in the photonic crystal.
Therefore, it is anxious to introduce different materials into the photonic crystal by a simple method.
[0009]
In view of the problems described above, it is an object of the present invention to provide a photonic crystal optical element and a method for manufacturing the same, which can arbitrarily introduce materials other than the materials constituting the photonic crystal.
[0010]
[Means for Solving the Problems]
The method for producing a crystal element of the present invention achieves the above object by the following means. In the production of a two-dimensional photonic crystal optical device, the inventors closed one end of a hole, and when a part of the hole is open, by applying or vapor-depositing a filling material from the sealing surface, It has been found that the filler material is selectively introduced into the holes opened at both ends .
[0011]
Based on these findings, the invention of the first photonic crystal optical element, the substrate to a periodic openings at both ends of the hole the two-dimensional photonic crystal composed of a more sequestering one end of the hole in the material of the substrate A portion thereof is open, and a filling material is selectively introduced into a hole having both ends open. Therefore, according to the present invention, any functional material can be introduced into the two-dimensional photonic crystal by selectively introducing the filler material.
[0012]
In addition, the inventors have shown that in the production of a two-dimensional photonic crystal optical device, by forming a thin film on the back surface of the substrate, a through hole and a closed hole can be produced corresponding to the difference in the thickness of the etching mask. I found it. Furthermore, it has been found that the filler can be selectively introduced into the through holes by applying or vapor-depositing the filler on the sealing surface.
A first photonic crystal optical element manufacturing method based on such knowledge includes a step of manufacturing an etching mask partially different in thickness using a second material for a substrate made of a first material, and a back surface of the substrate. Forming a thin film with the second material or the third material, forming a hole in the substrate by etching, and further penetrating a part of the back thin film; And a filling step.
According to the present invention, any functional material can be introduced into the two-dimensional photonic crystal by selectively introducing the filler material.
[0013]
Further, the inventors have removed the barrier layer blocking one end of the holes of the alumina nanohole array by ion beam irradiation in the production of the two-dimensional photonic crystal optical device using the alumina nanoholes, and thereby removing one of the blocked holes. It was found that the part can be selectively made into a through hole. Furthermore, it has been found that the filler can be selectively introduced into the through holes by applying or vapor-depositing the filler on the sealing surface.
[0014]
Based on this knowledge, the second photonic crystal optical element manufacturing method, possess one end of the sequestered periodically blocked pores by the barrier layer, an alumina nanohole array in which the barrier layer is made of alumina nanoholes array of the same material characterized by having a step of forming a portion is removed by ion beam or the like through holes of the barrier layer, and a step of filling the filling material from the barrier layer side in the through hole. According to the present invention, any functional material can be introduced into the two-dimensional photonic crystal by selectively introducing the filler material.
[0015]
Furthermore, the inventors of the present invention, in manufacturing a two-dimensional photonic crystal optical device, sprayed a sphere that substantially matches the hole diameter on the surface of the substrate having a through hole, and then washed off the extra sphere, thereby removing one end of all the through holes. It was found that can be made into a blocking hole. Moreover, it discovered that a part of blockade hole could be made into a through-hole by removing a part of spherical body by ion beam irradiation or an etching. Moreover, it discovered that a filler could be selectively introduce | transduced with respect to a through-hole by apply | coating or vapor-depositing a filler on the sealing surface.
[0016]
The third photonic crystal optical element manufacturing method based on such knowledge is obtained by spraying spheres having a diameter slightly larger than the hole diameter on the surface of the substrate having periodic through- holes , and then cleaning the excess spheres. by removing the steps of one end of all of the through hole making blockade surface which is blocked by the spherical body, a portion of a sphere of said spherical body is removed by etching, again through a portion of the sealed surface a step of, characterized by a step of filling the through-hole filling material from the sealed surface. According to the present invention, any functional material can be introduced into the two-dimensional photonic crystal by selectively introducing the filler material.
[0017]
In the above invention, it is preferable to use, for example, alumina, silicon, silicon oxide, GaAs, InP or the like as the first material.
In the above invention, as the filling material, for example, a functional filling material such as SiO ₂ gel, TiO ₂ gel, polythiophene, polyphenylene vinylene, polyacetylene, alumina gel, aluminum hydroxide, Alq ₃ which is an organic electroluminescence material, DCM dye, etc. It is desirable to use.
In the above invention, it is desirable to use, for example, Ti, Ni, Au, Cr, C ₆ O, ZEP, PMMA, SiO ₂ or the like as the second and third materials.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
[0019]
“First Embodiment”
FIG. 1 is a schematic process diagram showing the optical element according to the first embodiment.
As shown in FIGS. 1C and 1D, the optical element according to the present embodiment has a two-dimensional structure in which a substrate 11 made of a first material has vertical through-holes 12 with periodic openings. In the photonic crystal, an arbitrary functional filling material 13 is introduced into a part of the vertical through-hole 12.
[0020]
As shown in FIGS. 1A to 1D, in the present embodiment, the substrate 11 is provided with through vertical holes 12 and blocking vertical holes 14 (see FIG. 1A). By applying the filling material 15 on the back side (see FIG. 1B), only the through vertical holes 12 are filled with the filling material 13 (see FIGS. 1C and 1D), and any functionality An optical element of material is obtained.
[0021]
That is, in the fabrication of a two-dimensional photonic crystal optical device, only a predetermined hole of a plurality of holes is made a through vertical hole 12, and the remaining is sealed at the lower end and the vertical sealed through hole 14 is opened at the upper end. The filling material 15 is applied or vapor-deposited from the back side of the substrate 11. As a result, the filling material 13 is selectively introduced from the back surface side of the substrate 11 into the through vertical hole 12 having both ends opened.
Therefore, by selectively introducing the filling material 13 by the above method, it is possible to fill and introduce any functional material into the two-dimensional photonic crystal, and the characteristics of the functional material are exhibited. Functional optical elements can be obtained.
[0022]
Further, as shown in FIG. 2, the filling material 13 remaining on the back surface side of the substrate 11 is positively peeled off by a method such as etching or acid treatment, and the filling material 13 is filled only in the through vertical holes 12. By using an optical element, the effect of filling the functional material may be exhibited.
[0023]
In the present embodiment, the hole has been described as a vertical hole, but the present invention is not limited to this and may be an oblique hole having a predetermined angle.
[0024]
[Second Embodiment]
FIG. 3 is a schematic view showing an embodiment of a second optical element manufacturing method according to the present invention.
(1) First, as shown in FIG. 3, two types of first and second etchings of a second material and different thicknesses are performed on a substrate 21 which is a first material by, for example, electron beam exposure. Masks 22A and 22B are formed (see FIG. 3A). The first etching mask 22A is a thin mask in the thickness direction of the substrate 21, and the second etching mask 22B is a thick mask in the thickness direction of the substrate 21.
The reason why the masks having different thicknesses are used is that through holes are formed only at arbitrary positions due to the difference in etching rate, as will be described later.
Further, a thin film 23 on the back surface side is formed on the back surface of the substrate 21 with the same material as the etching mask (FIG. 3A).
Note that the thin film 23 may be formed of a third material different from the second material.
(2) A vertical hole 24 is formed in the substrate 21 by dry etching or the like (FIG. 3B).
(3) When the etching is further advanced, the thin etching mask 22A is removed, and at the same time, the thin film 24 on the back surface side is etched in the vertical hole 24 to form the through vertical hole 25 (FIG. 3C). ).
(4) Further, the etching is advanced, and the substrate portion on which the thin etching mask 22A has been formed is etched to just before the back thin film to form the sealed vertical hole 26 (FIG. 3D).
(5) Thereafter, the filling material 27 is applied to the back side of the substrate 21 (FIG. 3E).
{Circle around (6)} Finally, the filling material 27 is filled only in the through-holes 27 (FIG. 3F). This filling is performed by filling the filling material 27 from the end face of the through vertical hole 27 by capillary action.
[0025]
When filling the through-holes 27 with the filling material 27 by vapor deposition, the steps of FIGS. 3E and 3F are performed simultaneously.
[0026]
[Third Embodiment]
FIG. 4 is a schematic view showing an embodiment of a third optical element manufacturing method according to the present invention.
(1) First, in FIG. 4, a metal film 34 is formed by vapor deposition on the barrier layer 33 of the alumina nanohole array 32 having the closed vertical holes 31 sealed at one end (FIGS. 4A and 4B). .
{Circle around (2)} A portion of the barrier layer 33 at a predetermined location is removed from the back side of the array 32 by ion beam irradiation, and a through vertical hole 35 is produced (FIG. 4C).
(3) Next, a filling material 36 is applied from the side of the barrier layer 33 (FIG. 4D) By applying this filling material 36, only the through vertical hole 35 is filled with the filling material 36 to obtain an optical element. (FIG. 4E).
[0027]
By peeling off the metal film 34 with an acid or the like, the filling material 36 and the metal film 34 can be removed at the same time, and the functional efficiency of the optical element is higher than in the case of the optical element with the filling material 36 attached. improves.
[0028]
[Fourth Embodiment]
FIG. 5 is a schematic diagram showing an embodiment of a second optical element manufacturing method according to the present invention.
(1) First, in FIG. 5, a sphere 43 having a hole diameter substantially equal to that of the hole 41 is sprayed on the surface of the substrate 42 having the periodic through-hole 41, and one end of the through-hole 41 is sealed. 44 is produced (FIGS. 5A and 5B).
(2) Next, after forming an etching mask 45 by vapor deposition, a part of the metal film is removed by ion beam irradiation (FIGS. 5C and 5D).
(3) Next, the sphere 46 from which the metal film 45 has been removed by dry etching is etched to produce a through vertical hole 47 (FIG. 5E).
(4) Next, a filling material 48 is applied from the sealing surface side (FIG. 5 (F)). Thus, only the through vertical hole 47 is filled with the filling material to obtain an optical element (FIG. 5G).
[0029]
Here, examples of the material of the substrate in the present invention include alumina, silicon, silicon oxide, GaAs, InP, and the like, but any known substrate material for optical elements is not limited thereto. Absent.
[0030]
Examples of the filling material in the present invention include SiO ₂ gel, TiO ₂ gel, polythiophene, polyphenylene vinylene, polyacetylene, alumina gel, aluminum hydroxide, and the like. Examples of the filling material include known functional filling materials used for optical elements and the like. If there is, it is not limited to this.
[0031]
Examples of the material of the etching mask in the present invention include Ti, Ni, Au, Cr, C ₆ O, ZEP, PMMA, and SiO _2. However, any known mask material can be used. It is not a thing.
[0032]
According to the present invention, it is possible to fill an arbitrary hole of a two-dimensional photonic crystal, and it is particularly effective as a method for manufacturing an optical functional element using a two-dimensional photonic crystal.
[0033]
【Example】
Hereinafter, preferred examples of the present invention will be described, but the present invention is not limited thereto.
[0034]
Example 1
Example 1 is a specific example of the method according to the embodiment shown in FIG.
As a photonic crystal substrate, periodic blocked vertical holes 14 having a period of 0.25 μm were formed on an AlGaAs substrate 11 by electron beam exposure and etching.
By aligning and repeating the electron beam exposure and etching again, a part of the blocked vertical hole was made into the through vertical hole 12. A polythiophene solution was applied from the sealed surface by spin coating and solidified to produce an optical element 100A.
In this example, the pore diameter was in the range of 25 to 85% of the above period (0.25 μm).
[0035]
When the filling portion filled with the polythiophene filling material 13 of the optical element 100A having the pattern as shown in FIG. 6 is irradiated with excitation light having a wavelength of 600 nm and fluorescence emitted at 750 nm emitted from the upper surface is observed, a photonic band is observed. Due to the confinement effect by the gap, a fluorescence yield of 100 times that of light emission from the bulk polythiophene thin film was obtained.
[0036]
(Example 2)
Next, another example according to the present invention will be described. Example 2 is a specific example of the method according to the embodiment shown in FIG.
A Si substrate was used as the substrate 21. Further, SiO ₂ was used as an etching mask material and a backside thin film material. Electron beam lithography was repeated to prepare SiO ₂ etching mask patterns having different thicknesses. Periodic through vertical holes 25 and closed vertical holes 26 with a period of 0.25 μm were prepared by dry etching using C ₂ F ₆ . The substrate was turned over and the PMMA solution was applied by spin coating and solidified. Excess PMMA was removed together with the SiO ₂ film on the back surface in hydrofluoric acid.
An optical element 100B having a PMMA filling portion filled with a filling material 27 as shown in FIG. 7 was produced. When light was incident on the PMMA filling portion 114, it was confirmed that a good waveguide was obtained.
[0037]
Example 3
Next, another example according to the present invention will be described. Example 3 is a specific example of the method according to the embodiment shown in FIG.
On the barrier layer side of the 300 nm-period alumina nanohole array 32 having a barrier layer, Ni 250 nm was deposited. The barrier layer was removed at an interval of 1.5 μm while observing the barrier layer by ion beam irradiation. The polythiophene solution as the filler 36 was applied by spin coating from the barrier layer side and solidified. Excess polythiophene was removed together with the Ni film on the back surface in hydrochloric acid.
An optical element 100C having a polythiophene filling portion filled with a filling material 36 as shown in FIG. 8 was produced. The polythiophene-filled portion was irradiated with excitation light having a wavelength of 600 nm, and fluorescence emitted at 750 nm emitted from the upper surface was observed. Yield was obtained.
[0038]
(Example 4)
Next, another embodiment according to the present invention will be described. Embodiment 4 is a specific embodiment of the method shown in FIG.
A Si substrate 42 having vertical holes with a hole diameter of 80 nm and a pitch of 300 nm was used. After spraying polystyrene spheres 43 having a diameter of 310 nm on the substrate, washing to remove excess polystyrene spheres, a Ni film was deposited from the sealed surface. After removing a part of the Ni film with an ion beam, the polystyrene sphere at that location was etched by O ₂ RIE to form a through vertical hole 48. A polythiophene solution was applied by spin coating from the sealing surface side and solidified.
An optical element 100D having a polythiophene filling portion filled with a pattern filling material 48 as shown in FIG. 9 was produced. The polythiophene-filled portion was irradiated with excitation light having a wavelength of 600 nm and the fluorescence emitted at 800 nm was observed on the upper surface. Got the rate.
[0039]
【The invention's effect】
As described above, according to the present invention, an optical element in which a functional material is arbitrarily introduced into a two-dimensional photonic crystal is obtained by selectively filling holes in the two-dimensional photonic crystal. Thus, a functional optical element using a photonic crystal can be manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of a photonic crystal optical element according to the present invention.
FIG. 2 is a schematic view showing an embodiment of a photonic crystal optical element according to the present invention.
FIG. 3 is a schematic process diagram showing an embodiment of a photonic crystal optical element manufacturing method according to the present invention.
FIG. 4 is a schematic process diagram showing another embodiment of the photonic crystal optical element manufacturing method according to the present invention.
FIG. 5 is a schematic process chart showing another embodiment of the photonic crystal optical element manufacturing method according to the present invention. .
FIGS. 6A and 6B are views showing a top surface and a cross section of a photonic crystal optical element in a first example of the present invention. FIGS.
FIGS. 7A and 7B are diagrams showing a top surface and a cross section of a photonic crystal optical element in a second embodiment of the present invention. FIGS.
FIG. 8 is a view showing a top surface and a cross section of a photonic crystal optical element according to a third embodiment of the present invention.
FIG. 9 is a view showing a top surface and a cross section of a photonic crystal optical element according to a fourth embodiment of the present invention.
FIG. 10 is a schematic process diagram showing a photonic crystal optical element manufacturing method according to a conventional method.
11 Substrate 12 Vertical through hole 13 Filling material 14 Sealed vertical hole 21 Substrate 22A First etching mask 22B Second etching mask 23 Thin film 24 Vertical hole 25 Through vertical hole 26 Sealed vertical hole 27 Filling material 31 Sealed vertical hole 32 Alumina nanohole Array 33 Barrier layer 34 Metal film 35 Through vertical hole 36 Filling material 41 Through vertical hole 42 Substrate 43 Sphere 44 Sealed vertical hole 45 Etching mask 46 Spherical body 47 with metal film removed Through vertical hole 48 Filling material

Claims (4)

In the substrate a periodic openings at both ends of the hole the two-dimensional photonic crystal composed of a, one end of the hole is more sequestered material of the substrate, some of which are not open, both ends of which are openings A photonic crystal optical element characterized in that a filler material is selectively introduced into the photonic crystal optical element. A step of forming an etching mask having a partially different thickness using a second material on a substrate made of the first material, and a step of forming a thin film on the back surface of the substrate with the second material or the third material. ,
Forming a hole in the substrate by etching, and further penetrating a part of the backside thin film; and
And a step of filling the through hole with a filling material from the back surface of the substrate. Barrier layer which one end have a sequestered periodically blocked holes by using the alumina nanoholes array in which the barrier layer is made of alumina nanoholes array of the same material,
Forming part is removed by ion beam or the like through holes of said barrier layer,
Photonic crystal optical element manufacturing method characterized by a step of filling the through-hole filling material from the barrier layer side. By spraying spheres having a diameter slightly larger than the hole diameter on the surface of the substrate having periodic through holes , and then cleaning to remove excess spheres , one end of all through holes is sealed by the spheres. Producing a sealed surface;
A step of a portion of a sphere of said spherical body is removed by etching to penetrate a portion of the sealed surface again,
And a step of filling the through hole with a filling material from the sealing surface side.

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