JP6598184B2 - COLOR FILTER, AND LIGHT EMITTING DEVICE AND DISPLAY DEVICE USING THE SAME - Google Patents

Description

  The present invention relates to a color filter, and a light emitting device and a display device using the color filter, and in particular, a color filter which transmits light by excitation of surface plasmons and whose transmission wavelength is adjustable, and uses the same. The present invention relates to a light emitting device and a display device.

  A color filter used in a display element typified by a liquid crystal panel is formed using a color resist or the like so as to correspond to each color of RBG by light absorption. In recent years, with the development of information communication technology, information terminals have become smaller or mobile, and the importance of miniaturizing display elements, increasing brightness, and reducing power consumption has increased. In the case of a liquid crystal panel, the light transmittance is about 10%, and a high-luminance light source is used in order to realize sufficient luminance, but it goes against low power consumption. In addition, the color resist corresponding to each color in the color filter cannot be formed of the same material, naturally, the number of manufacturing steps is increased, and it is difficult to reduce the size of the pixel.

  Therefore, as a technology that can transmit light of a specific wavelength without using the above-described color resist, a color filter using a nano-periodic structure in a metal thin film and utilizing abnormal transmission of light by surface plasmon excitation has attracted attention. ing. Non-Patent Document 1 discloses the light transmission characteristics of a hole array in which nanoholes are formed in an aluminum thin film at a specific period. By changing the period of the hole array, the center wavelength of the transmission band corresponding to the period is disclosed. Have been reported to shift.

  On the other hand, the inventors of the present application have developed a sub-wavelength grating in which the gap between the beam bodies is variable in order to realize a black matrix and three primary colors (RBG) with a small number of elements (see Patent Document 1). The sub-wavelength grating has two pairs of beams constituting at least one predetermined gap per unit of the grating, and the gap is changed by an actuator to transmit light of a specific wavelength. .

  Further, Patent Document 2 and Non-Patent Document 2 have a configuration in which both of the above-described technologies are combined, and a technique for changing a transmission wavelength by surface plasmon excitation by changing a gap of a sub-wavelength grating by a metal beam by an actuator. It is disclosed.

  Non-Patent Documents 3 to 10 describe that a color filter that forms a nano-periodic structure in a metal thin film and uses an abnormal transmission of light by surface plasmon excitation attracts attention.

JP 2011-99936 A JP 2013-178498 A

Naoki Ikeda, Taiki Tsuya, Yoshimasa Sugimoto, Yasuo Koide, Atsushi Miura, Daisuke Inoue, Souko Nomura, Hisaki Fujikawa, Kazuo Sato, “Aluminum Surface Plasmon Color Filter”, IEICE Research Report. PN, Photonic Network 109 (401), pp.129-132,2007 K. Yamaguchi, M. Fujii, T. Okamoto, M. Haraguchi, "Electrically driven plasmon chip: Active plasmon filter", Applied Physics Express 7, 012201 (2014) B. Zeng, Y. Gao, F.J. Bartoli, "Ultrathin Nanostructured Metals for Highly Transmissive Plasmonic Subtractive Color Filters," Scientific Reports 3, 2840,2013. T.Xu, Y.K.Wu, X.Luo, L.J.Guo, "Plasmonic nanoresonators for high-resolution color filtering and spectral imaging," Nature communications 1, pp.59, 2010. H.S.Lee, Y.T.Yoon, S.S.Lee, S.H.Kim, K.D.Lee, "Color filter based on a subwavelength patterned metal grating," Optics Express 15, No.23, 2007. A.Krishnan, T.Thio, TJKim, HJLezec, TWEbbesen, PAWolff, J.Pendry, L.Martin-Moreno, FJGrarcia-Vidal, "Evanescently coupled resonance in surface plasmon enhanced transmission," Optics Communications 200, pp.1-7, 2001. W.L.Barnes, A.Dereux, T.W.Ebbesen, "Surface plasmon subwavelength optics," Nature 424, pp.824-830, 2003. Q.Chen, D.R.S.Cumming, "High transmission and low color cross-talk plasmonic color filters using triangular-lattice hole arrays in aluminum films," Optics Express 18, 13, 2010. MAVincenti, M. Grande, D. de Ceglia, T. Stomeo, V. Petruzzelli, M. De Vittorio, M. Scalora, A. D'Orazio, "Color control through plasmonic metal gratings," Aoolied Physics Letters 100, 201107 , 2012. T.Lee, A.Higo, H.Fujita, Y.Nakano, H.Toshiyoshi, "A Study on Color-tunable MEMS Device based on Plasmon Photonics," Int. Conf. Optical MEMS & Nanophotonics 2010, pp.107-108 , 2010.

  The technologies disclosed in Patent Document 2 and Non-Patent Document 2 described above have a structure in which metal beams having sub-wavelengths are arranged with a gap between sub-wavelengths, suspension beams are continuous at both ends, and the suspension beams are fixed to a substrate. It has become. And it was the structure which changes a gap | interval by making adjacent metal beams approach or separate by electrostatic attraction or electrostatic repulsion, and bending a metal beam.

  However, since both ends of the metal beam (both ends of the suspension beam) are fixed, for example, when approaching the metal beam by electrostatic attraction, the gap between the pair of metal beams can be approached, Since the gap with the metal beam is separated, the lattice period formed by the metal beam cannot be changed as a result. That is, although the transmission wavelength can be changed by changing the gap, the transmission wavelength is realized as a reflective effect of suppressing the transmission intensity of a specific wavelength, and the transmittance is attenuated as a whole. It was a tendency to do. This kind of phenomenon is the same in the sub-wavelength grating disclosed in Patent Document 1.

  The present invention has been made in view of the above points, and the object of the present invention is to provide a color filter that can adjust the transmission wavelength without attenuating the transmittance in the transmission wavelength band. Another object is to provide a light receiving device and a display device using the color filter.

  Therefore, the present inventors have considered that the attenuation of the transmittance in the transmission wavelength band can be eliminated by changing the gap of the sub-wavelength grating and simultaneously changing the grating period, and thus the present invention has been completed. .

  That is, according to the present invention relating to the color filter, fine metal wires are arranged in parallel and periodically, the period of each metal wire is made narrower than the light wavelength, and each period of each metal wire is simultaneously expanded in the extending direction. Alternatively, the transmission wavelength band of light is changed by appropriately changing in the contraction direction.

  According to the said structure, while arrange | positioning a fine metal wire in parallel and periodically, and making the period of the said metal wire narrower than a light wavelength (it is set as the sub wavelength which is comparable as or less than a light wavelength). The transmitted light in a specific transmission wavelength band can be obtained by excitation of the surface plasmon. By changing the period of each metal wire in the expansion direction or contraction direction at the same time, the grating period formed by each metal wire can be changed at the same time (substantially evenly). It can be arbitrarily adjusted.

  Further, according to the present invention relating to the color filter, a plurality of fine metal wires are aligned with their axes parallel to each other with an appropriate interval therebetween, and adjacent ends of each metal wire are connected to each other by a deformable connecting portion. At least one of the sub-wavelength grating, a support portion that supports the sub-wavelength grating in a state of being levitated from the base surface, and both sides of the sub-wavelength grating in a direction perpendicular to the axial direction of the metal wire. And an actuator for advancing and retreating the actuator in the orthogonal direction.

  According to the above configuration, since the metal wires constituting the sub-wavelength grating are connected to each other by the elastically deformable connecting portions at both ends of the adjacent metal wires, all the metal wires are continuous and integrated. A sub-wavelength grating is formed. In addition, since the sub-wavelength grating is in a state of being levitated from the base surface by the support portion, the position of each metal wire can be easily changed.

  Therefore, by moving at least one of the sub-wavelength gratings by the actuator, the connecting portion is deformed almost evenly, and a plurality of metal wires move in accordance with the deformation of the connecting portion, and these metal wires are formed. It is possible to change the respective gaps simultaneously and almost uniformly. Since the grating period can be changed by changing the gap between the metal wires, the transmission wavelength characteristics can be adjusted.

  In the invention having the above-described configuration, as the metal wire, a metal wire made of aluminum or having a MIM structure formed of a metal layer and an insulator layer can be used.

  When the metal wire is made of aluminum, surface plasmons are excited by light having a shorter wavelength than gold and silver, so that the variable range of transmission wavelength characteristics can be widened. Further, when the wire is formed by a metal-insulator-metal (MIM) laminated structure, the wavelength selectivity of the surface plasmon is increased, so that the characteristics of the color filter such as transmittance and saturation are improved.

  Further, in the invention of each configuration described above, the support portion is connected by the connecting portion between both ends of the metal wire located on both sides of the sub-wavelength grating, so that at least one of the support portions can be advanced and retracted by the actuator. Can be configured.

In such a configuration, the support force by the support portion does not directly act on the metal wire forming the sub-wavelength grating, and the metal wire can be supported through the connecting portion while being movable. . Further, by connecting at least one of the support parts to the movable part of the actuator (part driven in the advance / retreat direction), the support part can be operated to approach or separate the gap between the metal wires by the advance / retreat of the support part. It becomes.

  Furthermore, in the inventions of the above-mentioned configurations, the width and thickness of each metal wire of the sub-wavelength grating are arbitrary, and the gap between each metal wire is determined so as to form a desired period. It becomes. At this time, the period can be determined by adjusting the width dimension of the metal wire and the gap, and the period can be changed by further expanding the gap. In this case, the initial gap width and the range of gap expansion are appropriately selected according to the desired transmission wavelength band to be changed, but it is also possible to limit the transmission wavelength band to the visible light range. It is. When changing the transmission wavelength band in the visible light range, for example, the width of each metal wire of the sub-wavelength grating is 250 nm, the thickness is 100 nm, and the gap between each metal wire is 150 nm. The gap between the metal wires can be expanded to 350 nm and the grating period can be expanded to 600 nm by the actuator.

  According to the above configuration, the grating period is determined by the width dimension of each metal wire and the gap dimension between each metal wire, but the grating period can be changed in the range of 400 nm to 600 nm. . Here, the wavelength at which the surface plasmon resonance in the sub-wavelength grating is excited substantially depends on the grating period. Therefore, even when the width dimension of the metal wire is constant, the surface plasmon resonance is changed by changing the grating period. The wavelength at which resonance is excited can be varied. And when the width dimension of a metal wire is fixed to 250 nm, the gap | interval dimension between metal wires can be changed in the range of 150 nm-350 nm, and a grating | lattice period can be changed in the range of 400 nm-600 nm.

  On the other hand, the present invention relating to the light receiving device is a light receiving device using any one of the color filters described above, wherein the sub filter is floated on the surface of the substrate on which the light receiving element is manufactured. A wavelength grating is formed.

  According to the above configuration, the surface plasmon is excited in the sub-wavelength grating by the light irradiated to the light receiving element, and the transmission wavelength characteristic is changed by changing the grating period in the sub-wavelength grating. The transmission intensity can be detected. It can be used when measuring the intensity of light of a specific wavelength, such as when measuring the fluorescence intensity of a fluorescent substance or the like.

  Further, the present invention relating to a display device is a display device using any one of the color filters described above, a color filter substrate formed by arraying the sub-wavelength gratings forming the color filter, and the color filter And a light source that emits white light to the filter substrate.

  According to the above configuration, surface plasmons are excited in the individual sub-wavelength gratings arrayed on the color filter substrate by the light emitted from the light source, and light having a specific wavelength is transmitted by specifically transmitting through the sub-wavelength gratings. Can be displayed. Since the grating period of the sub-wavelength grating is variable, by adjusting the grating period, light having an arbitrary color can be transmitted and a display device in which various colors appear can be configured. Note that an LED that emits white light can be used as the light source. By using a light source that emits white light, black can be displayed by exciting surface plasmons to wavelengths in the ultraviolet region.

  According to the present invention relating to the color filter, it is possible to change the grating period at the same time as changing the gap of the sub-wavelength grating, thereby changing the wavelength at which the surface plasmon is excited in the sub-wavelength grating and transmitting it. The wavelength can be adjusted. Also, unlike the configuration that limits the transmittance at a specific wavelength by changing only the gap between metal wires (conventional configuration), it is a configuration that promotes excitation of surface plasmon resonance at a specific wavelength. Therefore, the transmittance of other wavelengths is not limited, and the transmittance can be improved.

  Further, since the present invention according to the light receiving device uses the color filter having the above-described effects, the wavelength of the surface plasmon excited by the light irradiated to the light receiving element is changed to the sub-wavelength grating. It can be adjusted by. Thereby, the transmitted light intensity of a specific wavelength can be detected.

  Furthermore, since the present invention according to the display device uses the color filter having the above-described effects, various wavelengths can be obtained by adjusting the wavelength of the surface plasmon excited by the light of the light source using the sub-wavelength grating. Can be displayed. Since this sub-wavelength grating can change the grating period by an actuator, it can display light of different wavelengths by a single structure. Therefore, it contributes to miniaturization in a miniaturized display device.

It is explanatory drawing which shows embodiment of a color filter. It is explanatory drawing which shows the connection state of the metal wire by a connection part, and the state of the change of the clearance gap between metal wires. FIG. 3 is an end view of a cut portion taken along line III-III in FIG. 1. It is explanatory drawing which shows the preparation methods of a color filter. It is explanatory drawing which shows the preparation methods of a color filter. It is explanatory drawing which shows the other preparation methods of a color filter. It is explanatory drawing which shows the other preparation methods of a color filter. It is explanatory drawing which shows the outline of embodiment of a light-receiving device. It is explanatory drawing which shows the outline of embodiment of a display apparatus. It is a SEM photograph of the subwavelength grating produced for experiment. It is a graph which shows the analysis result of the transmission wavelength characteristic accompanying the change of a grating period. (A) is a graph showing a transmission spectrum when TM polarized light is incident, and (b) is a graph showing a transmission spectrum when TE polarized light is incident.

Embodiments of a color filter and a light emitting device and a display device using the color filter will be described below with reference to the drawings.

<Color filter>
FIG. 1 is a diagram showing an outline of an embodiment of the invention relating to a color filter. As shown in this figure, the outline of the color filter of the present embodiment is as follows. It is composed of an actuator 4 that operates as possible.

  The sub-wavelength grating 1 is a structure in which fine metal wires 11, 12, 13,... 15 are arranged in parallel and periodically, and the period of each metal wire is narrower than the optical wavelength (optical wavelength). The so-called sub-wavelength. And it is comprised so that each period by these metal wires can be suitably changed to an expansion direction or a contraction direction simultaneously. By simultaneously changing the period in the expansion direction or the contraction direction, the period formed by the plurality of metal wires 11 to 15 is changed almost uniformly at the same time. A configuration for expanding or contracting such a cycle will be described later.

  By the way, the sub-wavelength grating 1 is composed of a plurality of metal wires 11, 12, 13,... The metal wires 11 to 15 are formed of aluminum, and by using the MEMS technology, for example, a metal wire having a width of 250 nm, a thickness of 100 nm, and a length of 10 μm can be formed. The metal wires 11 to 15 are respectively connected to adjacent metal wires on both sides by connecting portions 16a, 16b, 17a, 17b... 19a, 19b. For example, both ends of the metal wires 12 positioned in the second row from the one support portion 2 are connected to the first row of metal wires 11 adjacent thereto by connecting portions 16a and 16b, and The third row metal wires 13 are also connected by the connecting portions 17a and 17b. Details will be described later.

  The support portions 2 and 3 that support both sides of the sub-wavelength grating 1 support the sub-wavelength grating 1 in a state of being levitated from the surface of the base A. One of the support portions 2 and 3 is integrated with the movable portion 41 of the actuator 4, and the other support portion 3 is fixed to the surface of the base A. The actuator 4 exemplified here is a comb-teeth electrode type electrostatic drive actuator used as an electronic component drive device, and comb-like electrodes 43 and 44 are provided on both the movable portion 41 and the fixed portion 42. It is formed and arranged in such a manner that both electrodes 43 and 44 are opposed to each other and are inserted between the comb teeth. Then, by charging the electrodes 43 and 44 with the opposite sign or the same sign, an electrostatic attractive force or an electrostatic repulsive force is applied, and the movable portion 41 can be driven to move forward and backward. In the present embodiment, one of the electrodes 43 and 44 is grounded, and the other is charged with a positive or negative charge (for example, the movable part 41 is connected to the ground, and a voltage is applied to the electrode 44 of the fixed part 42. Thus, only the electrostatic attractive force is applied, and only the driving force in the pulling direction is supplied. In this case, since a driving force due to electrostatic repulsion cannot be expected, only electrostatic attraction is used to obtain a stable driving force. In the case of the present embodiment, as will be described later, since the connecting portions 16a to 19b that connect both ends of the metal wires 11 to 15 are elastically deformed, after being moved (advanced) by driving in the pulling direction. One of the reasons is that it is not necessary to drive by electrostatic repulsive force because the reverse movement (retreat) is enabled by the restoring force of the connecting portions 16a to 19b.

Also, the movable portion 41 is provided with suspensions 45a and 45b continuously on both sides thereof, and the distal ends 46a and 46b of the suspensions 45a and 45b are fixed to the surface of the base portion A, so that the movable portion 41 is attached to the base portion. It floats from the surface of A. The support portion 2 is configured to support one side of the sub-wavelength grating 1 by being integrated with the movable portion 41.

  In addition, in order to support the sub-wavelength grating 1 by both the support portions 2 and 3, the connecting portions 20a and 20b similar to the above are respectively provided between both ends of the metal wires 11 and 15 adjacent to the support portions 2 and 3. It is connected by 20b, 30a, 30b.

  Here, the configuration of the sub-wavelength grating 1 formed by the metal wires 11, 12, 13,... 15 will be described with reference to FIG. FIG. 2 shows the configuration of the metal wire 11 located in the first row, the metal wire 12 located in the second row, the metal wire 13 located in the third row and the vicinity thereof from one support portion 2. It is the figure which expanded the state in planar view.

  As shown in FIG. 2 (a), the metal wires 11, 12, and 13 are connected between the adjacent ends 11a, 11b, 12a, 12b, 13a, and 13b by connecting portions 16a, 16b, 17a, and 17b. It is in a connected state. These connecting portions 16a, 16b, 17a, and 17b are all formed in a substantially U shape having a curved portion, and have the same size and the same shape. The curved portions are formed at both ends 11a to 13b of the metal wires 11 to 13. It arrange | positions toward outward and is connected so that it may straddle the adjacent both ends 11a-13b. That is, one connecting portion 16a is connected so as to straddle both ends 11a, 12a of the first row of metal wires 11 and the second row of metal wires 12, and the second row of metal wires 12 and the second row of metal wires 12 are connected. One connecting portion 17a is connected so as to straddle both ends 12a, 13a of the third row 13 as well. Similarly, the other ends 11b, 12b, and 13b are connected so that the connecting portions 16b and 17b straddle. And each connection part 16a-17b functions as a kind of hinge which deform | transforms so that the curvature of a curved part may be changed.

  Thereby, both ends 12a and 12b of the metal wire 12 of the 2nd row located in the middle will be in the state which continued between adjacent metal wires 11 and 13 adjacent, and all the metal wires 11-15 are integrated. A sub-wavelength grating 1 is formed continuously (FIG. 1). And as mentioned above, the both ends of the adjacent metal wires 11-13 are connected by the connection parts 16a-17b, and a continuous ring shape will be formed (it is not what continues to a waveform).

  Therefore, as shown in FIG. 2 (b), the connecting portions 16a to 17b are elastically deformed (enlarged both ends of the substantially U-shape), so that the adjacent metal wires 11 to 13 maintain the axes in parallel. The mutual gap can be changed. Therefore, for example, when the metal wire 11 in the first row moves in a direction orthogonal to the axial direction, the connecting portions 16a and 16b continuous to both ends 11a and 11b are elastically deformed, and the metal in the second row At the same time as acting to expand the gap with the wire 12, the metal wires 12 in the second row are attracted by the elastic force of the connecting portions 16a and 16b. The attracted second row of wires 12 acts so as to draw the third row of metal wires 13 while elastically deforming the next connecting portions 17a and 17b and expanding the gap. This also acts on the other connecting portions and other metal wires in the same manner. As a result, all the connecting portions 16a to 19a and 16b to 19b (FIG. 1) are uniformly elastically deformed, and the adjacent metal wires 11 The gap of ~ 15 is changed in a substantially uniform state. Such movement of the metal wire 11 is driven by the above-described actuator 4 (FIG. 1), and the driving force in the forward / backward direction by the actuator 4 is transmitted via one support portion 2. It is. Moreover, since the connection parts 16a-17b function as a hinge by moderate elastic force, they are comprised with the material (For example, silicon nitride etc. can be mentioned) which can be elastically deformed.

As described above, the sub-wavelength grating 1 is supported by the support portions 2 and 3 in a state of floating from the surface of the base A, and the individual metal wires 11 to 15 are continuously connected by the connecting portions 16a to 19b. It is composed of. Therefore, when one support part 2 moves in the forward / backward direction, the gap between the metal wires 11 to 15 can be changed, and the grating period of the sub-wavelength grating 1 can be changed. This state is shown in FIG.

  3 is an end view of a cut portion taken along line III-III in FIG. As shown in this figure, of the movable part 41 and the fixed part 42 constituting the actuator 4, the movable part 41 is supported at a position appropriately spaced from the surface Aa of the base A, and the fixed part 42 is Since they are fixed to the surface, the same height is maintained. Then, by generating an electrostatic attractive force or electrostatic repulsive force between the two (between the comb-like electrodes, see FIG. 1), the movable portion 41 has its height (gap with the surface Aa of the base A). While maintaining, it approaches or separates from the fixing | fixed part 42, and will advance / retreat as a result. Moreover, when the movable part 41 advances and retreats, one support part 2 also advances and retreats simultaneously, and the space | interval of both the support parts 2 and 3 will be changed.

  By changing the distance between the support portions 2 and 3, the metal wire 11 in the first row can be moved via the connecting portions 20 a and 20 b connected to the one support portion 2. Then, the other metal wires 12 to 15 connected by the connecting portions 16a to 19a and 16b to 19b are moved. Since the other support portion 3 is fixed, the connecting portions 16a to 19a and 16b to 19b are similarly deformed between the support portions 2 and 3, and the gap between the metal wires 11 to 15 is changed. G diffuses and contracts in an almost uniform state. And the grating period Λ determined by the gap G and the width dimension W of the metal wires 11 to 15 can be changed. Such movement of the support portion 2 and the metal wires 11 to 15 is possible because they float from the surface Aa of the base portion A.

  Since the present embodiment is configured as described above, by operating the comb electrode type electrostatic drive actuator 4, the movable portion 41 and the one support portion 2 are advanced and retracted, whereby each of the metal wires 11 to 15. The grating period Λ can be changed for the entire sub-wavelength grating 1. By changing the lattice period Λ, the wavelength λ of the excited surface plasmon changes.

  For example, in the case of the metal wires 11 to 15 having the above exemplary dimensions, if the initial gap dimension is 150 nm, the initial lattice period Λ is 400 nm. Then, by extending the gap size from the initial value of 150 nm and making it variable in the range up to 350 nm, the grating period Λ can be changed in the initial range of 400 nm to 600 nm. At this time, the wavelength λ of the surface plasmon excited by the sub-wavelength grating 1 can be calculated by the following equation.

Where λ is the wavelength of the surface plasmon excited by the subwavelength grating, Λ is the period of the grating structure (grating period), m is the parameter of the subwavelength grating dispersion (diffraction order), and ε _m is the metal The dielectric constant of the beam, ε _d indicates the dielectric constant of the dielectric in contact with the metal beam.

  As is clear from the above equation, the wavelength λ of the surface plasmon excited by the sub-wavelength grating 1 is proportional to the grating period Λ, so that the transmission wavelength can be easily changed by changing the grating period Λ. Will be able to. As described above, since the gaps G of the metal wires 11 to 15 constituting the sub-wavelength grating 1 in the present embodiment change substantially evenly, the grating period Λ similarly changes throughout the sub-wavelength grating 1. Can be made. Therefore, the transmission wavelength can be changed in the entire sub-wavelength grating 1.

<Color filter manufacturing method>
A method for manufacturing a color filter having the above-described configuration will be briefly described. 4 and 5 show an outline of a process for producing a color filter on a glass substrate.

First, a Ti / TiN layer functioning as the light shielding film 101 is formed on the surface of the glass substrate 100 by patterning (see FIG. 4A). The light-shielding film 101 is for shielding the irradiation of light to a range (actuator or the like) excluding the portion where the sub-wavelength grating is formed. Next, silicon serving as the sacrificial layer 102 is deposited on the entire surface of the glass substrate 100 and the surface of the light shielding film 101 (see FIG. 4B). Further, a portion of the surface of the sacrificial layer 102 formed by a metal wire or the like is patterned by lift-off (see FIGS. 4c (a) to 5 (b)). That is, the resist 103 is directly drawn in a region to be removed in a later process (see FIG. 4C), and then a metal material 104 is deposited on the entire surface (see FIG. 5A), and finally the resist 103 is removed. (See FIG. 5B). Since the metal material 104 later functions as a metal wire, the desired metal material (aluminum to excite surface plasmons with short wavelength light) can be used. When the metal wire has an MIM structure, after depositing the metal material 104, an insulating material is laminated, and the metal material is again deposited. Aluminum can be used as the metal material, but the material is not limited to this, and materials such as gold and silver can be used. Further, as the insulating material, SiO ₂ , Ta ₂ O _5, ZrO ₂ or the like can be used, but is not limited to this.

  The metal material 104 patterned by lift-off as described above is laminated in a predetermined shape on the surface of the sacrificial layer 102, and the shape thereof is the above-described sub-wavelength grating 1 (metal wires 11 to 15, connecting portions 16 a to 16 a. 19b), support portions 2 and 3, and actuator 4 (including suspensions 45a and 45b). Then, the sacrificial layer 102 is removed by etching, so that the sub-wavelength grating 1 and the support portions 2 and 3 are floated from the surface of the glass substrate 100 (see FIG. 5C).

  The removal of the sacrificial layer 102 by etching does not remove all of the sacrificial layer 102, but estimates the etching rate, so that the fixed portion of the actuator 4 (the suspension or one support portion 3 is not shown). The lower layer part of the part appropriately selected) is left. 4 and 5 show the case where the actuators 4 are formed on both sides of the sub-wavelength grating 1, the one support portion 3 is not the actuator 4 but is a metal that is fixed to the surface of the glass substrate 100. The material may be patterned.

  Next, another manufacturing method will be described. 6 and 7 are diagrams showing an outline of a method for manufacturing a color filter using a silicon substrate.

First, a silicon oxide film 201 is formed on the back surface of the silicon substrate 200, and the region where the sub-wavelength grating is formed in a later process and the silicon substrate 200 should be separated (in a direction perpendicular to the paper surface in the figure). The resist 202 is patterned with a photoresist for the entire region (only the back surface side) except for a continuous region (see FIG. 6A). The silicon oxide film 201 is partially removed by dry etching or wet etching (see FIG. 6B). As a result, the silicon substrate 200 is exposed on the back side in the region where the silicon oxide film 201 is removed. Thereafter, the silicon substrate 200 in the region is dug to an appropriate depth by deep digging reactive ion etching (Deep-RIE) from the back side. At this time, the etching rate is predicted and adjusted so that the thickness up to the surface of the substrate 200 in the region remains at about 1/10 to 1/30 (see FIG. 6C).

  Next, after removing the silicon oxide film 201 and the resist 202 on the back surface side, a metal material is patterned on the front surface side by lift-off (see FIGS. 6D to 7B). That is, the resist 203 is directly drawn in a region to be removed in a later process (see FIG. 6D), and then a metal material 204 is deposited on the entire surface (see FIG. 7A), and finally the resist 203 is removed. (See FIG. 7B). Thereby, the metal material 204 is patterned on the surface of the silicon substrate 200 in a desired shape. In the region where the sub-wavelength grating 1 is to be formed, a metal material is deposited so as to form a metal wire with an appropriate interval. The surface of the silicon substrate 200 is exposed in the gap portion where no metal material is deposited, and the surface of the silicon substrate 200 is etched to a predetermined depth using this exposed region (FIG. 7C). reference).

  This etching can be performed by isotropic etching using an etching gas (for example, xenon difluoride gas), and the portion removed from the front surface side of the silicon substrate 200 is estimated from the back surface side by predicting the etching rate. It is adjusted to be equivalent to the thickness of the remaining dug. Thus, by etching from the front surface of the silicon substrate 200, a portion etched from the back surface side and a portion etched from the front surface side are continuous, and the silicon substrate 200 is divided into left and right. In addition, the portion where the metal material is deposited floats from the surface of the silicon substrate 200 and constitutes a metal wire that forms the sub-wavelength grating 1.

<Light receiving device>
Next, an embodiment of the light receiving device will be described with reference to FIG. 8 illustrates a photodiode 301 as a light receiving element, and reference numerals 302 and 303 denote electrodes. As shown in this figure, as the light receiving device, it is assumed that a light receiving element such as a photodiode 301 is previously formed on a substrate 300 and the color filter CF is installed on the light receiving surface. In this embodiment, a color filter CF created by a production method (see FIGS. 4 and 5) for forming a subwavelength grating on a glass substrate is attached to the light receiving surface of the light receiving element 301 by bonding. . Further, a light source L for exciting surface plasmons is provided. Surface plasmons are excited in the color filter CF by light emitted from the light source L, and transmitted light of a specific wavelength reaches the light receiving surface of the photodiode 301 by adjusting the grating period of the sub-wavelength grating.

  As described above, by installing the color filter on the light receiving surface of the photodiode, the transmitted light intensity of a specific wavelength can be measured. This can be used, for example, when detecting light of a specific wavelength emitted from a fluorescent substance, or for detecting light of a specific wavelength in a fluorescent labeling technique that uses a fluorescent label when specifying a protein.

<Display device>
As shown in FIG. 9, the display device includes a backlight 400 and a light guide plate 500 and a color filter substrate 600. The color filter substrate 600 used here is an array of the sub-wavelength gratings, and is manufactured with the same configuration by adjusting the transmitted light wavelength for each pixel, but with different colors. Can be displayed. Note that a glass substrate 700 is provided on the surface of the color filter substrate 600 so that transmitted light can be visually recognized through the glass substrate 700.

  At this time, by making the light emitted from the backlight 400 white light, surface plasmons can be excited to wavelengths in the ultraviolet region by adjusting the grating period of the sub-wavelength grating, thereby displaying black. Is also possible. In this manner, RBG and black can be displayed by the color filter substrate 600 in which the color filters having the same structure are arrayed, and thus manufacturing is easy and a small display device can be provided.

  Although the embodiments of the present invention are as described above, these are merely examples, and the present invention is not limited to these embodiments. Therefore, various modifications can be made within the scope of the present invention.

  For example, in the embodiment of the color filter, the connecting portions 16a to 19b that connect the metal wires forming the sub-wavelength configuration are configured in a substantially U shape having an arc-shaped curved portion. The overall shape may be substantially U-shaped. The point is that all the connecting portions have the same shape and can be similarly elastically deformed so that the gaps between the metal wires are uniformly expanded and contracted.

  As an example of an actuator, a comb electrode type electrostatic drive actuator has been shown. However, the actuator is not limited to this type of actuator, and other structures can be used as long as they can be advanced and retracted efficiently and accurately. An actuator may be configured.

<Experimental example>
In order to obtain the transmission wavelength characteristic by the color filter, a sub-wavelength grating made of aluminum was prepared, and the transmission wavelength characteristic when irradiated with white light was analyzed. The sub-wavelength grating used was an aluminum wire having a width dimension of 250 nm and a thickness (height dimension) of 100 nm, and a gap of 150 nm (lattice period 400 nm), 200 nm (lattice period 450 nm), 250 nm (lattice period 500 nm). , 300 nm (grating period 550 nm) and 350 nm (grating period 600 nm), the transmittance of each wavelength was analyzed. For the analysis experiment, the gap between the wires was not movable, but the gap ( A fixed subwavelength grating matched to each dimension of the grating period was created, and a space was formed below the subwavelength grating to reproduce the case where the subwavelength grating floated from the base. The sub-wavelength grating is shown in Fig. 10. The width dimension of the aluminum wire in the figure is 20 nm before and after 250 nm, and the allowable range. Cycle 11 the analysis result by. The experiment was used as the front and rear 10nm desired period.

  As is clear from FIG. 11, it can be confirmed that the peak of the transmission wavelength changes from purple to red as the gap between the aluminum wires is increased to 150 nm to 350 nm (lattice period is 400 nm to 600 nm).

  Further, in order to determine whether or not the change in the peak of the transmission wavelength is due to excitation of the surface plasmon, a transmission spectrum when TM polarized light and TE polarized light were incident was measured. The results at this time are shown in FIGS. 12A shows the transmittance at each wavelength when TM polarized light is incident, and FIG. 12B shows the transmittance when TE polarized light is incident.

As apparent from the comparison between FIGS. 12A and 12B, when TM polarized light is incident, the transmission peak is shifted to the longer wavelength side by increasing the grating period, but when TE polarized light is incident. Had a relatively flat transmission spectrum, and no transmission peak appeared. As is well known, since surface waves cannot exist in the case of TE polarized light, surface plasmons can be excited only in the case of TM polarized light. Therefore, it is determined that the change in the peak of the transmission wavelength is caused by the excitation of the surface plasmon.

  For sub-wavelength gratings with a grating period of 450 nm, 500 nm, 550 nm, and 600 nm, the transmitted light when irradiated with random polarized light was visually observed, and the states were expressed in blue, green, yellow, and red, respectively. I was able to confirm.

DESCRIPTION OF SYMBOLS 1 Sub wavelength grating 2, 3 Support part 4 Actuator 11, 12, 13, 15 Metal wire (aluminum wire)
11a, 11b Both ends 12a, 12b of the first row of metal wires Both ends 13a, 13b of the second row of metal wires Both ends 16a, 16b, 17a, 17b, 19a, 19b of the third row of metal wires , 20b, 30a, 30b Connecting portion 41 Actuator movable portion 42 Actuator fixed portion 43, 44 Actuator electrodes 45a, 45b Suspension 46a, 46b Suspension tip 100 Glass substrate 101 Light shielding film 102 Sacrificial layer 103 Resist 104 Metal material 200 Silicon Substrate 201 Silicon oxide film 202 Resist 203 Resist 204 Metal material 300 Substrate 301 Photodiode 302, 203 Electrode 400 Backlight 500 Light guide plate 600 Color filter substrate 700 Glass substrate A Base Aa Base surface CF Color Width Λ the grating period of the gap W metal wires between the filters G metal wire

Claims (5)

A color filter capable of obtaining transmitted light in a specific transmission wavelength band by excitation of surface plasmons, wherein a plurality of fine metal wires are aligned with their axes parallel to each other with appropriate spacing therebetween, and each metal A sub-wavelength grating formed by mutually connecting adjacent ends of a wire by a connecting portion capable of elastic deformation;
A support portion for supporting the sub-wavelength grating in a state of being levitated from the base surface;
An actuator for advancing and retracting at least one of the two sides of the sub-wavelength grating in a direction orthogonal to the axial direction of the metal wire in the orthogonal direction;
The support portion is connected by the connecting portion between both ends of the metal wire located on both sides of the sub-wavelength grating, and only one of the support portions is continuous with a suspension whose tip is fixed to the base surface. Integrated with the movable part floating from the surface of the base part, and can be advanced and retracted by the actuator,
By changing the period formed by the metal wires of the sub-wavelength grating at the same time in the expansion direction or the contraction direction only by moving the movable part integrated in one of the support parts, the light transmission wavelength band can be changed. A color filter characterized by changing.   The color filter according to claim 1, wherein the metal wire is made of aluminum.   The color filter according to claim 1, wherein the metal wire has a MIM structure formed of a metal layer and an insulator layer. A light receiving device using the color filter according to any one of claims 1 to 3,
A light receiving device, wherein the sub-wavelength grating is formed on a surface of a substrate on which a light receiving element is manufactured in a state of being floated from the surface of the substrate. A display device using the color filter according to any one of claims 1 to 3,
A display device comprising: a color filter substrate formed by arraying the sub-wavelength gratings that form the color filter; and a light source that irradiates the color filter substrate with white light.