JP2002328313A - Optical switching element, its manufacturing method, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical switching element for color display which is simple in structure, small and light, and permits a high speed response, and which can be suitably used for a direct viewing/reflection type image display device requiring a quickly moving picture display. SOLUTION: The optical switching element 10 has optical multilayered structures 10R, 10G, 10B for displaying red color, green color and blue color, respectively on a substrate 11. Each layer (or a gap) differs in its film thickness (or a size) for each color, and is formed by using a gray scale mask or lift-off method. Color display is performed by changing reflected, transmitted or absorbed quantity of incident light by changing the sizes of the gaps 13R, 13G, 13B for displaying red color, green color and blue color, respectively. The substrate 11 is formed with carbon (C) for example. First layers 12R, 12G, 12B are formed with tantalum (Ta) for example. Second layers 14R, 14G, 14B are formed with silicon nitride (SiNx ) for example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switching element for displaying a color image using an optical multilayer structure having a function of reflecting, transmitting or absorbing incident light, a method of manufacturing the same, and an image display device. .

[0002]

2. Description of the Related Art In recent years, direct-view / reflection-type image display devices have
It is a key device for miniaturization and power saving of portable information devices. In addition, in this type of information portable device, display of black and white still images such as character information has been mainly used, but demands for color image display and moving image display have been greatly increased. Moreover, the quality of color image display,
For example, requirements for brightness, color reproducibility, accuracy of gradation display, and the like are very severe, and it is no longer possible to satisfy such requirements with an image having only colors. Therefore, there is a demand for the development of an optical switching element capable of responding at high speed and capable of supporting full-color display as an element for a direct-view / reflection-type image display device that can meet such a demand.

As conventional optical switching elements, those using liquid crystal and those using micromirrors (DMD;
Digital Micro Mirror Device, Digital Micro Mirror Device, registered trademark of Texas Instruments), one using a diffraction grating (GLV: Grating Light)
Valve, grating light valve, SLM (silicon light machine) company, and the like.

A conventional reflection-type image display device using liquid crystal has a structure in which liquid crystal molecules are sealed between an upper substrate made of glass and a lower substrate made of silicon or glass. Optical switching is performed by applying a voltage between the lower electrode and the liquid crystal molecules to control the direction of the liquid crystal molecules and rotate the deflecting surface.

However, the liquid crystal has a high response speed of only about several milliseconds, and has a poor high-speed response characteristic. Therefore, the conventional reflective image display device using liquid crystal has a problem in that when displaying a moving image with a fast movement, the outline is blurred and accurate display cannot be performed. In addition, a reflective image display device using liquid crystal requires a polarizing plate, and therefore has low light use efficiency. Further, at present, black-and-white display is the mainstream among reflection-type image display devices using liquid crystals, and those that can sufficiently satisfy the brightness, color reproducibility, and accuracy of gradation display as color image display devices are practical. Not converted.

An optical switching element using a micro mirror switches incident light by controlling the angle of the micro mirror. An optical switching element using a micromirror is a DMD (Digital Micro Mi
ror Device, a digital micromirror device, a registered trademark of Texas Instruments of the United States). Micromirrors are roughly classified into two types, a cantilever structure supported at one point and a torsional hinge structure supported at two points, and are driven using electrostatic force, a piezoelectric element, a thermal actuator, and the like. .

In the case of the cantilever structure, each micromirror is supported horizontally with respect to the substrate. When a potential difference is applied between the micromirror and the corresponding drive electrode, an electrostatic attraction is generated, The micromirrors are tilted toward the corresponding drive electrodes. Since the inclined micromirror and the non-tilted micromirror reflect the incident light at different angles, the incident light can be switched in two directions. When the potential difference applied between the micromirror and the drive electrode is removed, the micromirror returns to the original position by the spring force of the hinge supporting the micromirror.

On the other hand, in a micro mirror having a twisted hinge structure, each micro mirror is supported on a common upper substrate by a pair of hinge portions. The lower substrate is provided with a pair of electrodes corresponding to each micro mirror. The same potential difference is generated between each micromirror and one electrode of the pair of electrodes, and between the micromirror and the other electrode, so that the micromirror moves with respect to the lower substrate. And is kept horizontal.

Here, for example, by increasing the voltage applied to one electrode and decreasing the voltage applied to the other electrode, the electrostatic attraction generated between the micromirror and each of the corresponding pair of electrodes is unbalanced. And tilt the micromirror toward one of the pair of electrodes. As a result, the micromirror is inclined in one of two different directions, so that the incident light can be reflected and switched in two different directions. In such a micromirror, the angle at which light can be deflected, that is, the difference between the angles of reflected light in two directions is twice the mechanical deflection angle of the mirror, and the angle at which the light can be deflected becomes large.

However, the response speed of such a micromirror is generally on the order of several microseconds, and the high speed is not sufficient. When used for an image display device,
In order to improve the contrast, it is necessary to increase the angle at which light can be deflected, which causes a problem that the response speed is further reduced. Therefore, an optical switching element using a micromirror has already been used in a projection type image display device, but it is difficult to apply it to a direct-view type image display device.

As an optical switching element using a diffraction grating, for example, there is a GLV (Grating Light Valve, SLM (Silicon Light Machine)) disclosed in Japanese Patent Application Laid-Open No. 10-510374. In this GLV, a potential difference is generated between a ribbon-shaped mirror having a light reflecting surface and the lower electrode, and the resulting electrostatic attraction causes the ribbon-shaped mirror to move by ４ of the wavelength of the incident light. Thus, a diffracted light is generated by creating an optical path difference of 1/2 wavelength between the stationary ribbon-shaped mirror and the movable ribbon-shaped mirror, and the reflected light is switched between the 0th-order diffracted light direction and the 1st-order diffracted light direction. I do. At this time, it is also possible to control the intensity of the first-order diffracted light by controlling the optical path difference in a range up to 波長 wavelength.

The GLV can perform light switching only by moving a very light ribbon-shaped mirror by a small distance, so that the response speed is as fast as several tens of nanoseconds and is suitable for high-speed switching. It also has some problems.

First, at least two ribbon-shaped mirrors are required to cause light diffraction, and four or more, in practice, six ribbon-shaped mirrors are required to enhance the light use efficiency. A mirror is required. Therefore, when used one-dimensionally, it is difficult to reduce the overall size.

Second, the first-order diffracted light is generated at a certain angle with respect to two directions symmetric with respect to the optical axis of the zero-order diffracted light.
In order to use the first-order diffracted light, a complicated optical system for collecting the light traveling in these two directions into one light is required.

Third, when no voltage is applied to the electrodes,
The reflection surface of the ribbon mirror in the stationary state and the reflection surface of the movable ribbon mirror should ideally be on the same plane, but they are not actually aligned on the same plane. Therefore, it is necessary to apply a small voltage to each of the lower electrodes so that the reflection surfaces of all the mirrors are aligned on the same plane.

Fourth, the GLV uses a laser as a light source, irradiates switching elements integrated in a one-dimensional array with light formed in a line shape, and scans the light with a mirror or the like to scan a two-dimensional image. However, it is very difficult in principle to use a light source other than a laser or a direct-view image display device.

[0017] US Pat. No. 5,589,974 and US Pat.
00761 is disclosed. This light valve has a gap (gap layer) on a substrate (refractive index n _S ).
, A light-transmitting thin film having a refractive index of Δn _S is provided. In this element, an optical signal is transmitted or reflected by driving a thin film using electrostatic force and changing the distance between the substrate and the thin film, that is, the size of the gap. Here, the refractive index of the thin film is Δn _S with respect to the refractive index n _{S of the} substrate, and it is described that high contrast light modulation can be performed by satisfying such a relationship.

[0018]

However, the element having the above-mentioned structure cannot be realized in the visible light region unless the refractive index n _{S of the} substrate is a large value such as “4”. There is. That is, considering that the light-transmitting thin film is a structural body, a material such as silicon nitride (Si ₃ N ₄ ) (refractive index n = 2.0) is desirable. n _S = 4.
In the visible light region, such transparent substrates are difficult to obtain, and the choice of materials is narrow. For communication wavelengths such as infrared,
Although it can be realized by using germanium (Ge) (n = 4) or the like, application to a direct-view / reflection-type image display device seems to be practically difficult.

Therefore, the same applicant as the present applicant firstly
An optical multilayer structure having a structure in which a first layer having light absorption, a gap having a size capable of causing a light interference phenomenon and having a variable size, and a second layer are provided on a substrate. And an optical switching element and an image display device using the same (Japanese Patent Application No. 2000-219599). This optical multilayer structure has a configuration in which a first layer, a gap, and a second layer are arranged in this order on a substrate. In this optical multilayer structure, the complex refractive index of the substrate is represented by N _S (= n _S −i k _S , n _S is the refractive index, k _S is the extinction coefficient, i is the imaginary unit), and the first layer The complex refractive index of N
₁ (= n ₁ −ik ₁ , n ₁ is the refractive index, k ₁ is the extinction coefficient), the refractive index of the second layer is n ₂ , and the refractive index of the incident medium is 1.0. It is configured to satisfy the relationship of Expression (4).

[0020]

(Equation 1)

By using the above-mentioned optical multilayer structure, a high-speed response sufficient to constitute a two-dimensional image display device can be achieved, and an optical switching element can be realized with a simple structure in principle. . Further, since it is possible to switch between reflection and absorption of light, unnecessary light processing which is a problem in realizing an image display device can be extremely easily performed. Therefore, this optical switching element can be suitably used for a direct-view / reflection-type image display device.

However, this optical switching element can perform optical switching in a wide wavelength range with respect to a design wavelength, in other words, has a very broad band characteristic. Therefore, if this optical switching element is used as it is in a full-color image display device, the color reproducibility will be extremely poor. Such a problem of color reproducibility can be solved by forming a color filter on a cover glass used for sealing an optical switching element, as in the case of a direct-view / reflection-type image display device using liquid crystal. is there. At this time, by reducing the distance from the color filter to the light reflecting surface, as seen in a reflective liquid crystal,
It is possible to reduce a color shift or the like caused by a viewing angle.

Another problem in applying the above-described optical switching element to a full-color image display device is that when an optimal design is performed for each of the RGB colors, the dimension in the thickness direction is reduced in all layers except the upper electrode layer. It is difficult to adopt a normal manufacturing process because the color is different for each color.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide a direct-view / reflection type camera which has a simple structure, is small in size and light in weight, and is particularly required to display a fast-moving moving image. An object of the present invention is to provide an optical switching element which can be suitably used for an image display device and can respond at high speed.

A second object of the present invention is to produce a plurality of optical multilayer structures having different dimensions in the thickness direction of each layer on a common substrate by a normal manufacturing process, so that optical switching for color display can be achieved. It is an object of the present invention to provide a method for manufacturing an optical switching element that can realize an element by simple steps.

A third object of the present invention is to provide an image display device which is small, light and power-saving, has high light use efficiency, and is capable of displaying high-quality full-color display and fast-moving moving images.

[0027]

An optical switching element according to the present invention has, on a substrate, a first layer for red display having light absorption, a size capable of causing a light interference phenomenon, and the size thereof. And a red display optical multilayer structure having a structure in which a variable red display gap portion and a second layer for red display are provided, and a first for green display having light absorption on a substrate. A green display optical multilayer structure having a structure in which a layer, a green display gap having a size capable of causing a light interference phenomenon and having a variable size, and a second layer for green display are provided; A first layer for blue display having light absorption on a substrate, a gap for blue display having a size capable of causing a light interference phenomenon and having a variable size, and a second layer for blue display. Optical multilayer structure for blue display having a structure in which Driving means for changing the optical size of the red display gap, the green display gap, or the blue display gap, and the red display gap, the green display gap, or the blue display by the driving means. By changing the size of the use gap, the amount of reflection, transmission or absorption of the incident light is changed.

According to the method of manufacturing an optical switching element of the present invention, a first red display element having a different film thickness is provided on a substrate.
Forming a first layer for green display and a first layer for blue display using a first gray scale mask; and forming a first layer for red display and a first layer for green display. On the first layer and the first layer for blue display, as a sacrificial layer, three-dimensional shapes corresponding to the red display gap, the green display gap, and the blue display gap having different sizes from each other are provided. A step of forming an amorphous silicon (a-Si) film using a second gray scale mask; and forming a second layer for displaying red and a green layer having different thicknesses on the amorphous silicon film. The second layer for display and the second layer for blue display
Forming a red display gap, a green display gap, and a blue display gap having different sizes from each other by removing the amorphous silicon film by etching. And a process.

According to another method of manufacturing an optical switching element according to the present invention, a first layer for displaying red, a first layer for displaying green, and a first layer for displaying blue are provided on a substrate. Forming a layer using a lift-off method, and forming a sacrificial layer on the first layer for red display, the first layer for green display, and the first layer for blue display. Forming an amorphous silicon (a-Si) film having a three-dimensional shape corresponding to the red display gap, the green display gap, and the blue display gap by using a lift-off method. Forming a second layer for red display, a second layer for green display, and a second layer for blue display using a lift-off method, on the amorphous silicon film; , By removing the amorphous silicon film by etching. Different red display gap sizes, in which green display gap portion and a step of forming a blue display gap.

An image display device according to the present invention displays a two-dimensional image in color by irradiating a plurality of one-dimensionally or two-dimensionally arranged optical switching elements with light. A red display first layer having light absorption, a red display gap having a size capable of causing a light interference phenomenon and having a variable size, and a red display second layer And an optical multilayer structure for red display having a structure in which a first layer for green display with light absorption is provided on a substrate. The first layer has a size capable of causing a light interference phenomenon. A green display optical multilayer structure having a structure in which a variable green display gap and a green display second layer are provided, and a first layer for blue display having light absorption on a substrate With a size that can cause light interference A blue display optical multilayer structure having a structure in which a blue display gap portion having a variable size, and a blue display second layer are provided, a red display gap portion, a green display gap portion or Driving means for changing the optical size of the blue display gap.

In the optical switching device according to the present invention, the driving means changes the optical size of the red, green and blue display gaps of the red, green and blue display optical multilayer structure, so that the incident light is changed. , A switching operation is performed, and color display can be realized.

In the method for manufacturing an optical switching element according to the present invention, the first, second, and third gray scale masks are used, so that the number of steps can be reduced.
It is possible to easily and accurately form an optical multilayer structure for red, green, and blue display in which the film thickness (or size) of each layer (or gap) differs for each color.

In another manufacturing method of the optical switching element according to the present invention, since the lift-off method is used, the manufacturing can be performed by repeating the normal manufacturing process, and the process conditions can be easily set.

In the image display device according to the present invention, a two-dimensional color image is displayed by irradiating light to a plurality of optical switching elements of the present invention arranged one-dimensionally or two-dimensionally.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 and FIG.
1 schematically illustrates an optical switching element according to a first embodiment of the present invention. The optical switching element 10 is used for a full-color display of an information portable device such as a PDA (Personal Digital Assistant) and a portable terminal.

The optical switching element 10 includes an optical multilayer structure 10R for red display and an optical multilayer structure 10 for green display.
G and blue display optical multilayer structures 10B are provided one by one, which can support color display.
Red, green, blue display optical multilayer structure 10R, 10
G and 10B are arranged on the substrate 11 in one direction.
The dimension of the optical switching element 10 in the planar shape is, for example, 147 in the case of a 5-inch SVGA, 800 × 600 pixel direct-view / reflection image display device.
It fits in μm × 147 μm in width.

The red display optical multilayer structure 10R is formed on the substrate 11 so as to be in contact with the substrate 11, the first layer 12R for red display having light absorption, and can cause a light interference phenomenon. A red display gap 13R having a size and the size can be changed, and a second layer 14R for red display are arranged in this order.

The green optical display multilayer structure 10G is formed on the substrate 11 so as to be in contact with the substrate 11, the first layer 12G for absorbing green light and capable of causing light interference. A green display gap 13G having a size that can be changed in size and a second layer 14G for green display are arranged in this order.

Further, the optical multilayer structure for blue display 10B
Is formed on and in contact with the substrate 11,
A first layer 12B for blue display having light absorption, a gap 13B for blue display having a size capable of causing a light interference phenomenon and having a variable size, and a second layer for blue display. Are arranged in this order.

Red, green and blue display optical multilayer structure 1
As shown in FIG. 1, a spacer 1 made of, for example, silicon oxide (SiO ₂ ) is provided above the OR, 10G, and 10B.
6, a common cover glass 17 is joined.
The cover glass 17 is partially cut away for easy understanding of the drawing. The cover glass 17
Is common to the entire optical switching element array described later, in which a large number of the optical switching elements 10 are arranged two-dimensionally.

On the back surface of the cover glass 17, that is, the surface joined to the spacer 16, to improve color reproducibility,
Red, green, blue optical multilayer structures 10R, 10G, 10
B, red filter 18R, green filter 18
The G and blue filters 18B are formed by a known method. The distance (that is, the height of the spacer 16) from the front surface of the substrate 11 to the back surface of the cover glass 17 (the back surface of the red, green, and blue filters 18R, 18G, and 18B) is as short as 2.2 μm, for example, and the color shift depends on the viewing angle. Does not occur.

The substrate 11 is made of a non-metal such as carbon (C) or graphite (graphite), a metal such as tantalum (Ta), a metal oxide such as chromium oxide (CrO), a metal nitride such as titanium nitride (TiN _x ), Silicon carbide (S
An opaque and light-absorbing material such as a carbide such as iC) or a semiconductor such as silicon (Si), or a thin film of such a light-absorbing material formed on a transparent substrate It may be. The substrate 11 may be formed of a transparent material such as glass or plastic, or a translucent material having a small extinction coefficient.

First layer 12 for displaying red, green and blue
R, 12G, 12B is a layer of light absorption, for example Ta, Ti, a metal such as Cr, metal oxide such as CrO, a metal nitride such as TiN _X, such as SiC carbides, such as silicon (Si) It is formed of a semiconductor or the like.

Second layer 14 for displaying red, green and blue
R, 14G and 14B are made of transparent material
For example, titanium oxide (TiO 2)_Two) (Refractive index 2.
4), silicon nitride (Si_ThreeN_Four) (Refractive index 2.0), oxidation
Zinc (ZnO) (refractive index 2.0), niobium oxide (Nb_Two
O_Five) (Refractive index 2.2), tantalum oxide (Ta)_TwoO_Five)
(Refractive index 2.1), silicon oxide (SiO) (refractive index 2.
0), tin oxide (SnO) _Two) (Refractive index 2.0), ITO
(Indium-Tin Oxide) (refractive index 2.0)
Have been.

The second display for displaying red, green and blue is
Since the layers 14R, 14G, and 14B function as movable parts during the switching operation as described later, it is particularly preferable that the layers 14R, 14G, and 14B are formed of Si ₃ N ₄ , which has a high Young's modulus and is durable. . The second layers 14R, 14G, and 14B for displaying red, green, and blue are driven by static electricity as described later, so that the second layers 14R, 14G, and 14B for displaying red, green, and blue are formed. And a composite layer including transparent conductive films 15R, 15G, and 15B for red, green, and blue, which are transparent conductive films made of ITO or the like.

Optical multilayer structure 1 for red, green and blue display
Each of the layers 0R, 10G, and 10B has a different physical or optical film thickness (or size) in each color in all layers (or gaps). However, the transparent conductive films 15R, 15G, and 15B for red, green, and blue display may have the same film thickness for each color. In the present embodiment, the thickness is, for example, 20 nm.

First layer 12 for displaying red, green and blue
The physical film thickness of R, 12G, and 12B is the wavelength of the incident light,
It is determined by the refractive index and extinction coefficient of the material, and the optical constants of the substrate 11 and the second layers 14R, 14G, and 14B for displaying red, green, and blue, and takes a value of, for example, about 5 to 60 nm. In the present embodiment, the physical thickness of the first layer 12R for red display is, for example, 12.8 nm,
The physical thickness of the first layer 12G for green display is, for example, 2
The physical thickness of the first layer 12 </ b> B for blue display is set to 1.6 nm, for example.

Second layer 14 for displaying red, green and blue
The optical film thickness of R, 14G and 14B is such that the substrate 11 is formed of a transparent material such as carbon, graphite, carbide or glass, and the first layers 12R and 12G for displaying red, green and blue. , 12B are tantalum (T
In the case of being formed of a metal material having a large extinction coefficient such as a), “λ / 4” (λ is a design wavelength of incident light)
It is as follows. However, the substrate 11 is formed of a transparent material such as carbon, graphite, carbide or glass, and has a first layer 12R for displaying red, green and blue.
When 12G and 12B are formed of a material having a small extinction coefficient such as silicon (Si), red, green,
The optical thicknesses of the second layers 14R, 14G, and 14B for blue display are larger than “λ / 4” and equal to or smaller than “λ / 2”. This is the first layer 12R for displaying red, green and blue.
Since the trajectory of the optical admittance when 12G and 12B are formed of Si moves upward on the admittance diagram, the second layer 1 for displaying red, green and blue is used.
This is because the points of intersection with 4R, 14G, and 14B are above the real axis (+ on the imaginary axis).

It should be noted that the above film thickness is strictly “λ / 4”, “λ
/ 2 ", values near these values may be used. This is because, for example, as the optical film thickness of one layer becomes larger than λ / 4, the other layer can be supplemented by making it thinner. This is the same in other embodiments.
Therefore, in this specification, the expression of “λ / 4” includes the case of “almost λ / 4”.

The optical characteristics of the second layers 14R, 14G and 14B for displaying red, green and blue are as follows.
Transparent conductive films 15R, 15G, 15B for green and blue display
Is a synthesized optical characteristic (optical admittance) as a composite layer containing. The first layers 12R, 12G, and 12B for displaying red, green, and blue also have two or more optical characteristics different from each other similarly to the second layers 14R, 14G, and 14B for displaying red, green, and blue. It may be a composite layer composed of layers. In this case, the combined optical characteristics (optical admittance) of the composite layer are assumed to have the same characteristics as those of a single layer.

In this embodiment, the physical thickness of the red, green and blue display second layers 14R, 14G and 14B (the red, green and blue display transparent conductive films 15R, 15G,
15B excluding the physical film thickness) is 32.
8 nm, 31.7 nm, and 22.8 nm.

Red, green, and blue display gaps 13R, 1
3G and 13B are optically sized (the first layers 12R and 12R for red, green and blue display) by driving means described later.
12G, 12B and second layer 1 for red, green, blue display
4R, 14G, and 14B) are set to be variable. Red, green, and blue display gaps 13R,
The medium filling 13G and 13B may be gas or liquid as long as it is transparent. As the gas, for example, air (refractive index n _D = 1.10 with respect to sodium D line (589.3 nm)).
0), nitrogen (N ₂ ) (n _D = 1.0) and the like, water (n _D = 1.333), silicone oil (n _D
= 1.4 to 1.7), ethyl alcohol (n _D = 1.3
618), glycerin (n _D = 1.4730), and iodomethane (n _D = 1.737). The red, green, and blue display gaps 13R, 13G, 1
3B may be in a vacuum state.

Red, green, and blue display gaps 13R, 1
The optical size of 3G, 13B is “odd multiple of λ / 4”
And “even number multiples of λ / 4 (including 0)” in a binary or continuous manner. As a result, the amount of reflection, transmission, or absorption of incident light changes in a binary or continuous manner. Note that the first for red, green, and blue display is
As in the case of the thicknesses of the layers 12R, 12G, and 12B and the second layers 14R, 14G, and 14B for displaying red, green, and blue, even if the thickness slightly deviates from a multiple of λ / 4, Since it can be complemented by a slight change in thickness or refractive index, "λ /
The expression “4” includes the case of “almost λ / 4”.

In this embodiment, the optical size of the red, green, and blue display gaps 13R, 13G, and 13B is “λ / 4”, that is, 162.5 nm, respectively.
137.5 nm and 112.5 nm.

The optical switching element 10 having the above configuration can be manufactured by the manufacturing method shown in FIGS.

First, as shown in FIG. 3, a substrate 11 made of, for example, carbon is prepared. Then, as shown in FIG. 4, for example, CVD (Chemical Vapor Deposition;
For example, a tantalum (Ta) film 41 is formed as a thin film made of the above-described material on the substrate 11 by a chemical vapor deposition method. As described above, in the present embodiment, the thickness of the first layer 12R for red display is, for example, 12.8 nm,
The thickness of the first layer 12G for green display is, for example, 21.6 n.
m, the thickness of the first layer 12B for blue display is, for example, 16.
Although the thickness is set to 3 nm, the thickness of the tantalum film 41 formed in the process of FIG.
The thickness of G should be equal to 21.6 nm.

The subsequent steps shown in FIGS. 5 to 7 are performed by etching the tantalum film 41 into a three-dimensional shape, thereby forming a first layer 12R for red display and a green display for which the film thicknesses are different from each other. This is a step for forming the first layer 12G and the first layer 12B for blue display. Specifically, the first layer 12R for red display has a thickness of 21.6 nm.
Is formed by etching away the tantalum film 41 of 8.8 nm. The first layer 12G for green display is formed by maintaining the initial film thickness so that the tantalum film 41 is not etched. The first layer 12B for blue display is formed by etching off the tantalum film 41 by 5.3 nm. As shown in FIG. 7, both end portions 41A, 41A of the tantalum film 41 are not removed by etching. As described above, in order to remove the tantalum film 41 by etching so as to have a different thickness depending on the location, a gray scale mask is used in the present embodiment as described in detail below.

First, as shown in FIG.
A first photoresist film 21 is applied to a uniform thickness on 1, and the first photoresist film 21 is exposed using a first gray scale mask 31 prepared in advance. The first gray scale mask 31 is a gray scale mask manufactured by mask-exposing a glass plate having a film thickness of several mm in which the surface layer has been specially processed using a direct drawing apparatus using an electron beam or a laser beam. . As such a gray scale mask, a mask capable of adjusting a black level (a level at which light passes through the mask) by an irradiation amount of an electron beam or a laser beam has been put into practical use (for example, HEBS manufactured by Canyon Material Co., Ltd.).
(High Energy Beam Sensitive) glass plate). By using a gray scale mask with a changed black level of the mask, the amount of exposure of the photoresist can be adjusted and the thickness of the exposed photoresist can be changed.

Such a first gray scale mask 3
1 to expose the first photoresist film 21;
It is processed into a three-dimensional shape as shown in FIG. After that, by etching the tantalum film 41 together with the first photoresist film 21, the shape of the first photoresist film 21 can be transferred to the tantalum film 41 as shown in FIG.

In general, for example, when it is desired to etch a thin film having an etching rate of 1 in a stepwise manner, if the etching rate of a photoresist film is 2, a required shape (in a step to be formed, a certain step is the lowest) The photoresist film may be processed stepwise with a thickness twice as large as the difference in thickness from the step. In the present embodiment, in the step of exposing the first photoresist film 21 to light, the thickness T _P1 of the first photoresist film 21 after the exposure shown in FIG. To meet. T _P1 = R _P1 · D _P1 (5) (where R _P1 represents the ratio of the etching rate of the first photoresist film 21 to the etching rate of the tantalum film 41, and D _P1 is the first photoresist after exposure. Membrane 2
1 (ie, the first layer 12R for displaying red) and portions other than the portion having the smallest thickness (ie, the first layers 12G, 1G for displaying green and blue).
2B and both end portions 41A, 41 of the tantalum film 41
It represents the difference in film thickness from A))

As described above, the first layer 12 for displaying red color
The thickness of R is the smallest, the first layer 12G for green display is 8.8 nm thicker than the first layer 12R for red display, and the first layer 12B for blue display is the first layer for red display. Layer 12
3.5 nm thicker than R. Therefore, the tantalum film 41
If the ratio of the etching rate of the first photoresist film 21 to the first photoresist film 21 is 2, the first photoresist film 21 is twice as large as 8.8 nm, that is, 17.6 nm in the process of FIG.
Is applied in advance. Then, the thickness of the first photoresist film 21 after the exposure shown in FIG. 6 is 0 nm (the first photoresist film 21) in the first layer 12R for red display.
Is completely removed), the first layer 12G for green display is twice 8.8 nm, that is, 17.6 nm (the first photoresist film 21 maintains the original thickness), and the first layer 12G for green display is In the first layer 12B of FIG.
m (the first photoresist film 21 slightly remains).

When the first photoresist film 21 and the tantalum film 41 processed into the above-described shapes are etched together, the ratio of the etching rate of the first photoresist film 21 to the tantalum film 41 is two. Then, the tantalum film 41 not covered with the first photoresist film 21 is etched by 8.8 nm to form the first layer 12R for red display, so that the film thickness covering the tantalum film 41 is obtained. The first photoresist film 21 of 6 nm is entirely etched, and the surface of the tantalum film 41 is exposed,
A first layer 12G for green display is formed. On the other hand, within the same time, the first photoresist film 21 having a thickness of 7.0 nm covering the tantalum film 41 is also completely etched, and the tantalum film 41 is further etched by 5.3 nm to have a thickness of 1 nm.
A first layer 12B for 6.3 nm blue display is formed.

As described above, the tantalum film 41 is processed into a three-dimensional shape by etching, and as shown in FIG. 7, the first layer 12R for red display and the first layer for green display having different film thicknesses from each other. The layer 12G and the first layer 12B for blue display can be formed.

Next, as shown in FIG. 8, the red, green, and blue display gaps 13R, 13G,
An amorphous silicon (a-Si) layer 42 is formed with a uniform thickness as a sacrificial layer for forming 13B. Since the size of the red display gap 13R among the red, green, and blue display gaps 13R, 13G, and 13B is 162.5 nm, which is the largest, the amorphous silicon film 42 also has 162.5 n.
m.

The subsequent steps shown in FIG. 9 to FIG.
To form the red display gap 13R, the green display gap 13G, and the blue display gap 13B having different sizes from each other, the amorphous silicon film 42 has
This is a step of etching into three-dimensional shapes corresponding to the green and blue display gaps 13R, 13G, and 13B. Specifically, in order to form the red display gap 13R having a size of 162.5 nm, the amorphous silicon film 42 is maintained at the original film thickness so as not to be etched. Size 1
To form the 37.5 nm green display gap 13 G, the amorphous silicon film 42 is etched away by 25 nm. 112.5 nm blue display gap 13B
Is formed by forming the amorphous silicon film 42 to a thickness of 50 nm.
Remove by etching. Note that both end portions 42A, 42A of the amorphous silicon film 42 shown in FIG. 8 are completely removed by etching as shown in FIG.

First, as shown in FIG. 9, a second photoresist film 22 is applied on the amorphous silicon film 42 to a uniform thickness, and this second photoresist film 22 is formed in advance. It is exposed to light using the second gray scale mask 32 and processed into a three-dimensional shape. In the present embodiment, in the step of exposing the second photoresist film 22 to light, the thickness T _P2 of the second photoresist film 22 after exposure shown in FIG. To meet. T _P2 = R _P2 · D _P2 (6) (where R _P2 represents the ratio of the etching rate of the second photoresist film 22 to the etching rate of the amorphous silicon film 42, and D _P2 represents the second rate after the exposure. Of the photoresist film 22 having the smallest thickness (ie, both end portions 42A, 42A) and portions other than the portion having the smallest thickness (red, green, and blue display gaps 13R, 13R).
G, represents the difference in film thickness from the portion that should be 13B)

The setting of the specific numerical value of the film thickness of the second photoresist film 22 after the exposure is the same as that of the first photoresist film 21, so that the detailed description is omitted.

Thereafter, the amorphous silicon film 42 is etched together with the second photoresist film 22 to thereby form the second photoresist film 22 on the amorphous silicon film 42 as shown in FIG. Can be transferred.

Subsequently, as shown in FIG. 12, a plasma C is formed on the tantalum film 41 and the amorphous silicon film 42.
VD (PECVD; Plazma Enhanced Chemical Vapor D)
eposition) or low pressure CVD (LPCVD; Low Pres)
The silicon nitride (SiN _x ) film 43 for forming the second layers 14R, 14G, and 14B for displaying red, green, and blue is formed to have a uniform thickness by sure chemical vapor deposition. At this time, the internal stress of the silicon nitride film 43 needs to be adjusted according to the response frequency required for the optical switching element 10, and is approximately 100 to 800 MPa.
a tensile stress is required. In the present embodiment, since the response time is required to be 1 μs or less, the silicon nitride film 43 is formed under the condition that the tensile stress becomes 200 MPa. The red, green, and blue display second layers 14R, 14G, and 14B are the second layers for red display.
Since the thickness of the layer 14R is 32.8 nm, which is the thickest, the thickness of the silicon nitride film 43 formed here is 32.8 nm.

The subsequent steps shown in FIG. 13 to FIG. 15 are the second layers 14R, 14R for red display having different film thicknesses.
Second layer 14G for green display, second layer 1 for blue display
This is a step of etching the silicon nitride film 43 into a three-dimensional shape to form 4B. Specifically, the film thickness 3
In order to form the second layer 14R for 2.8 nm red display, the silicon nitride film 43 is kept from being etched so as to maintain the original thickness. In order to form the second layer 14G for displaying green with a thickness of 31.7 nm, the silicon nitride film 43 is etched away by 1.1 nm. Film thickness 22.
In order to form the second layer 14B for blue display of 8 nm, the silicon nitride film 43 is etched away by 10 nm.
Note that both end portions 43 of the silicon nitride film 43 shown in FIG.
A and 43A are completely etched away as shown in FIG.

First, as shown in FIG. 13, a third photoresist film 23 is applied to a uniform thickness on a silicon nitride film 43, and this third photoresist film 23 is formed in advance. Using the third gray scale mask 33 that has been exposed, it is processed into a three-dimensional shape as shown in FIG.
At this time, as can be seen from FIG. 14, the third photoresist film 23 is divided into three portions having different thicknesses. In the present embodiment, in the step of exposing the third photoresist film 23, the film thickness T _P3 of the third photoresist film 23 after the exposure shown in FIG. To meet. T _P3 = R _P3 · D _P3 (7) (where R _P3 represents the ratio of the etching rate of the third photoresist film 23 to the etching rate of the amorphous silicon film 43, and D _P3 represents the third rate after the exposure. Of the photoresist film 23 (ie, both end portions 43A, 43A) and portions other than the portion having the smallest thickness (the second layers 14R, 1 for displaying red, green, and blue).
4G, 14B).

The setting of the specific numerical value of the film thickness of the third photoresist film 23 after exposure is the same as that of the first photoresist film 21, and therefore the detailed description is omitted.

Thereafter, by etching the silicon nitride film 43 together with the third photoresist film 23, the shape of the third photoresist film 23 is transferred to the silicon nitride film 43 as shown in FIG. At the same time, second layers 14R, 14G, and 14B for red, green, and blue display, which are divided into three portions and have different thicknesses, are formed.

Subsequently, an ITO film for forming the red, green, and blue display transparent conductive films 15R, 15G, and 15B is formed with a uniform thickness, for example, a thickness of 20 nm in the present embodiment. Transparent conductive film 15 for red, green and blue display
Since it is not necessary to change the film thickness of each of R, 15G and 15B for each color, the ITO film is patterned using a normal mask. As a result, as shown in FIG.
The red, green, and blue display transparent conductive films 15R and 15R are respectively formed on the blue display second layers 14R, 14G, and 14B.
G and 15B are formed.

Next, the spacer 1 shown in FIGS.
A silicon oxide (SiO ₂ ) film for forming 6 is formed to a thickness of 2.2 μm from the surface of the substrate 11,
This silicon oxide film is patterned by a lift-off method. Thus, as shown in FIGS. 17A and 17B, the red, green, and blue optical multilayer structures 10R, 10G,
A pair of spacers 16 is formed on each of the spacers 10B.

Thereafter, for example, xenon fluoride (Xe
The amorphous silicon film 42 as the sacrificial layer is removed by dry etching using F ₂ ). Thus, FIG.
19, as shown in FIG. 19, the red, green, and blue display gaps 13R and 13 having an optical size of “λ / 4”.
G and 13B are formed. In this manner, the optical switching element 10 capable of displaying a color including the optical multilayer structures 10R, 10G, and 10B for displaying red, green, and blue is completed.

Although one optical switching element 10 is shown in FIGS. 1 to 19, in practice, a large number of optical switching elements 10 are formed in a two-dimensional array An element array is configured. Further, a cover glass 17 common to the entire optical switching element array is further provided via a spacer 16.
(See FIG. 1). Red, green, and blue filters 18R, 18G, and 18B for improving color reproducibility are formed on the back surface of the cover glass 17 in advance. When joining the cover glass 17, the inside of the optical switching element array is sealed in a nitrogen (N ₂ ) or helium (He) atmosphere. The internal pressure is determined in consideration of the required attenuation of the optical switching element 10 depending on the application,
In the present embodiment, for example, a helium atmosphere of 50 KPa is used.

Thereafter, the optical switching elements 10 formed in a two-dimensional array are individually divided into chips. The optical switching element 10 can be formed into a chip by, for example, first dicing the cover glass 17 and then dicing the substrate 11.

The optical multilayer structure 10 for displaying red, green, and blue light of the optical switching element 10 having the above-described structure.
R, 10G, and 10B indicate the optical size of the red, green, and blue display gaps 13R, 13G, and 13B between odd multiples of λ / 4 and even multiples of λ / 4 (including 0). (For example, between “λ / 4” and “0”), the amount of reflection, transmission, or absorption of incident light is changed by changing the value in a binary or continuous manner. Red, green,
The optical or physical film thickness or size of each layer or gap constituting the blue display optical multilayer structure 10R, 10G, 10B is optimized for each color. Color display becomes possible.

In the present embodiment, the red, green, and blue display optical multilayer structures 10R, 10G, and 10B are driven by static electricity. That is, the electrostatic force generated by the potential difference due to the voltage application between the red, green, and blue display transparent conductive films 15R, 15G, and 15B and the red, green, and blue display first layers 12R, 12G, and 12B. Red, green, and blue display gaps 13R, 13G, 1
The optical size of 3B is binary-switched, for example, between “λ / 4” and “0” or between “λ / 4” and “λ / 2”. Of course, by continuously changing the voltage application to the red, green, and blue display transparent conductive films 15R, 15G, and 15B and the red, green, and blue display first layers 12R, 12G, and 12B, the red, green, and blue display first conductive layers 15R, 12G, and 12B are continuously changed. The sizes of the green and blue display gaps 13R, 13G, and 13B are continuously changed within a certain value range, and the amount of reflected, transmitted, or absorbed incident light is changed continuously (in an analog manner). You can also do so.

Here, the red, green, and blue display gaps 1
It is assumed that the optical sizes of 3R, 13G, and 13B are binary-switched between, for example, the above-mentioned “λ / 4” and “0”. Red, green, and blue display transparent conductive films 15R, 15
G, 15B and first layer 12 for red, green, and blue display
When the potential difference between R, 12G, and 12B is 0 V, the second layers 14R, 14G, and 14B for displaying red, green, and blue are red, green, and blue, as shown in FIG.
The first display layers 12R, 12G, and 12B for blue display are separated from each other, and the red, green, and blue display gaps 1 are provided.
The optical size of each of 3R, 13G, and 13B is, for example, “λ / 4”. At this time, the incident light is reflected and becomes white on the screen.

On the other hand, a positive voltage (for example, +10 V in this embodiment) is applied to the red, green, and blue display transparent conductive films 15R, 15G, and 15B, and the first red, green, and blue display is performed. When the layers 12R, 12G, and 12B are grounded and set to 0 V, an electrostatic attraction is generated. Due to this electrostatic attraction, as shown in FIG. 20B, the second layers 14R, 14G, and 14B for displaying red, green, and blue become the first layers 12R, for displaying red, green, and blue. Adhere to 12G, 12B.
Thus, the gaps 13R, 13 for displaying red, green, and blue are displayed.
The optical sizes of G and 13B are all “0”. At this time, if the substrate 11 is made of an opaque material that absorbs light such as carbon, incident light is completely absorbed by the substrate 11 and becomes black on the screen.

Of course, the red, green, and blue display optical multilayer structures 10R, 10G, and 10B can be individually driven. For example, in the state of FIG. 20A, a positive voltage (for example, +10 V in the present embodiment) is applied to the green and blue display transparent conductive films 15G and 15B,
The first layers 12G and 12B for displaying green and blue are grounded to zero.
If V, electrostatic attraction is generated. Due to this electrostatic attraction, as shown in FIG. 21A, the green and blue display second layers 14G and 14B adhere to the green and blue display first layers 12G and 12B, respectively. The second layer 14R for displaying red is kept separated from the first layer 12R for displaying red. Thus, the green and blue display gaps 13G,
The optical size of 13B is “0”, and the optical size of the red display gap 13R is “λ / 4”. At this time, the green and blue display optical multilayer structures 10G and 10B
Is completely absorbed by the substrate 11, and only the light that has entered the optical multilayer structure for red display 10R is reflected, so that the screen becomes red.

For example, in the state shown in FIG. 20A, a positive voltage (for example, +10 V in the present embodiment) is applied to the transparent conductive film 15B for blue display, and the first conductive film 15B for blue display is applied.
When the layer 12B is grounded to 0 V, an electrostatic attraction is generated. Due to this electrostatic attraction, as shown in FIG. 21B, the second layer 14B for blue display becomes the first layer for blue display.
The second layers 14R and 14G for displaying red and green are in close contact with the first layer 12B for displaying red and green.
Maintain a state separated from R and 12G. Thus, the optical size of the blue display gap 13B is “0”, and the optical size of the red and green display gaps 13R and 13G is “λ / 4”. At this time, the light incident on the blue display optical multilayer structure 10B is completely absorbed by the substrate 11, and
Since only the light that has entered the optical multilayer structures 10R and 10G for displaying red and green is reflected, the screen turns yellow.

As described above, in the present embodiment, red, green, and blue having the same configuration on the same substrate 11 except that the film thickness (or size) of each layer (or gap) is different for each color. Display optical multilayer structures 10R, 10G,
Since the optical switching element 10 is manufactured by manufacturing the optical switching element 10B, the optical switching element 10 capable of performing color display with a simple configuration can be realized. Furthermore, since one optical switching element 10 forms one pixel on the screen, the configuration is simpler and the size is smaller than, for example, a GLV in which one pixel requires six grid ribbons. Can be. Therefore, when applied to an image display device, the size and weight can be reduced, and the response speed increases as the size is reduced.
It can be expected to improve the quality of fast moving video display.

In the present embodiment, the substrate 11 and the first layers 12R, 12G, 1
Since the refractive index of 2B may be any value within a certain range,
The degree of freedom in material selection is increased. Further, when the substrate 11 is made of an opaque material, incident light is absorbed by the substrate 11 at the time of low reflection, so that there is no fear of generating stray light and the like, and the contrast is improved when applied to an image display device. I do.

In addition, in the present embodiment, if a plurality of optical switching elements 10 are assigned to one pixel, they can be driven independently of each other. Therefore, when performing gradation display of image display as an image display device, In addition to the time-division method, gradation display by area is also possible.

Further, in the present embodiment, in the method of manufacturing the optical switching element 10 described above, the respective layers (or gaps) of the red, green, and blue display optical multilayer structures 10R, 10G, and 10B are formed. First, second and second
Since the third photoresist layers 21, 22, and 23 are three-dimensionally processed using the first, second, and third gray scale masks 31, 32, and 33, the number of steps can be reduced. The red, green, and blue display optical multilayer structures 10R, 10G, and 10B in which the thickness (or size) of each layer (or gap) differs for each color can be easily and accurately formed.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An optical switching element according to the embodiment will be described. The optical switching element according to the present embodiment is different from the optical switching element according to the first embodiment shown in FIG. 1 only in the manufacturing method, and the other configurations and operations are the same as those of the first embodiment. Has an effect. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

The manufacturing method of the optical switching element according to the present embodiment is different from the first embodiment in the following points. That is, in the first embodiment, the red, green, and blue display optical multilayer structures 10R, 1R in which the film thickness (or size) of each layer (or gap) is different from each other for each color.
The first to third gray scale masks 31, 32, and 33 are used in order to form 0G and 10B on the same substrate 11.
Is used. On the other hand, in this embodiment, a layer having a desired film thickness is formed in a separate step for each color by using a lift-off method.

Hereinafter, a method for manufacturing the optical switching element according to the present embodiment will be described with reference to FIGS.

First, as shown in FIG. 22, a substrate 11 made of, for example, carbon is prepared. On this substrate, first layers 12 for displaying red, green, and blue having different thicknesses from each other are provided.
R, 12G, and 12B are formed in separate steps for each color.

First, a photoresist is applied over the entire surface of the substrate 11 and exposed using a normal mask (not shown). As a result, the photoresist is patterned, and as shown in FIG.
A photoresist film 61 for forming R is formed.

Subsequently, as shown in FIG.
And red, over the entire surface of the photoresist film 61.
As a thin film made of the above-described material for the first layers 12R, 12G, and 12B for displaying green and blue, for example, tantalum (T
a) The film 62 is formed. As described above, in the present embodiment, since the thickness of the first layer 12R for red display is, for example, 12.8 nm, the thickness of the tantalum film 62 is also 1
2.8 nm.

Thereafter, a photoresist film 61 is formed on the tantalum film 6
Remove with 2. As a result, as shown in FIG. 25, a first layer 12R for red display having a desired film thickness made of tantalum is formed.

Next, a photoresist is applied to the entire surface of the substrate 11 and the first layer 12R for red display, and is exposed using a normal mask (not shown). Thus, the photoresist is patterned, and as shown in FIG. 26, a photoresist film 63 for forming the first layer 12G for green display is formed.

Subsequently, as shown in FIG.
A tantalum (Ta) film 64 is formed over the entire surface of the photoresist film 63. As described above, in the present embodiment, the thickness of the first layer 12G for green display is, for example, 21.6 nm, so that the thickness of the tantalum film 64 is also 21.6 nm.

Thereafter, a photoresist film 63 is formed on the tantalum film 6
Remove with 4. As a result, as shown in FIG. 28, a first layer 12G for displaying green with a desired film thickness made of tantalum is formed.

Further, a photoresist is applied to the entire surface of the substrate 11 and the first layers 12R and 12G for displaying red and green, and is exposed using a normal mask (not shown). Thus, the photoresist is patterned, and as shown in FIG. 29, a photoresist film 65 for forming the first layer 12B for blue display is formed.

Subsequently, as shown in FIG.
Then, a tantalum (Ta) film 66 is formed over the entire surface of the photoresist film 65. As described above, in the present embodiment, since the thickness of the first layer 12B for blue display is, for example, 16.3 nm, the thickness of the tantalum film 66 is also set to 16.3 nm.

Thereafter, a photoresist film 65 is formed on the tantalum film 6
Remove with 6. As a result, as shown in FIG. 31, the first layer 12B for blue display having a desired film thickness made of tantalum is formed.

As described above, the first layers 12R, 12R for displaying red, green, and blue, each having a desired film thickness, are provided.
G and 12B are completed by separate processes for each color. Next, an amorphous silicon film is formed as a sacrificial layer for forming the red, green, and blue display gaps 13R, 13G, and 13B having different sizes for each color by a separate process for each color.

First, a photoresist is applied over the entire surface of the substrate 11 and the first layers 12R, 12G, and 12B for displaying red, green, and blue, and is exposed using a normal mask (not shown). As a result, the photoresist is patterned, and as shown in FIG.
Amorphous silicon film 6 as sacrificial layer for forming R
8 (see FIG. 33) for forming a photoresist film 6
7 is formed.

Next, as shown in FIG. 33, an amorphous silicon (a-Si) film 68 is formed over the entire surface of the photoresist film 67 and the first layer 12R for red display. As described above, in the present embodiment, since the size of the red display gap 13R is, for example, 162.5 nm, the thickness of the amorphous silicon film 68 is also set to 162.5 nm.

Thereafter, the photoresist film 67 is removed together with the amorphous silicon film 68 formed thereon by using the lift-off method. Thus, as shown in FIG. 34, the red display gap 13 having a desired size is formed.
Amorphous silicon film 6 as sacrificial layer for forming R
8 are formed.

Subsequently, the substrate 11, the amorphous silicon film 68
Then, a photoresist is applied over the entire surface of the first layers 12G and 12B for displaying green and blue, and is exposed using a normal mask (not shown). Thereby, the photoresist is patterned, and as shown in FIG. 35, a photoresist film for forming an amorphous silicon film 70 (see FIG. 36) as a sacrificial layer for forming the green display gap 13G. Form 69.

Next, as shown in FIG. 36, an amorphous silicon (a-Si) film 70 is formed over the entire surface of the photoresist film 69 and the first layer 12G for green display. As described above, in the present embodiment, since the size of the green display gap 13G is, for example, 137.5 nm, the thickness of the amorphous silicon film 70 is also 137.5 nm.

Thereafter, the photoresist film 69 is removed together with the amorphous silicon film 70 formed thereon using the lift-off method. As a result, as shown in FIG. 37, the green display gap 13 having a desired size is formed.
Amorphous silicon film 7 as sacrificial layer for forming G
0 is formed.

Further, the substrate 11, the amorphous silicon film 6
A photoresist is applied to the entire surface of the first layer 12B for blue display, and the first layer 12B for blue display, and is exposed using a normal mask (not shown). Thus, the photoresist is patterned, and as shown in FIG. 38, a photoresist film for forming an amorphous silicon film 72 (see FIG. 39) as a sacrificial layer for forming the blue display gap 13B. 71 is formed.

Next, as shown in FIG. 39, an amorphous silicon (a-Si) film 72 is formed over the entire surface of the photoresist film 71 and the first layer 12B for blue display. As described above, in the present embodiment, since the size of the blue display gap 13B is, for example, 112.5 nm, the thickness of the amorphous silicon film 72 is also set to 112.5 nm.

Thereafter, the photoresist film 71 is removed together with the amorphous silicon film 72 formed thereon by using a lift-off method. Thereby, as shown in FIG. 40, the blue display gap 13 having a desired size is formed.
Amorphous silicon film 7 as sacrificial layer for forming B
2 are formed.

As described above, the red, green, and blue display gaps 13R, 13R each having a desired size are provided.
Amorphous silicon films 68, 70, 72 as sacrificial layers for forming G, 13B are completed by separate processes for each color. Next, second layers 14R, 14G, and 14B for displaying red, green, and blue having different thicknesses from each other are formed.
It is formed by a separate process for each color.

First, the substrate 11 and the amorphous silicon film 6
A photoresist is applied over the entire surface of each of 8, 70, and 72, and is exposed using a normal mask (not shown). Thus, the photoresist is patterned, and as shown in FIG. 41, a photoresist film 73 for forming the second layer 14R for red display is formed.

Subsequently, as shown in FIG. 42, the second layers 14R, 14 for displaying red, green, and blue are formed over the entire surface of the photoresist film 73 and the amorphous silicon film 68.
For example, a silicon nitride (SiN _x ) film 74 is formed as a thin film made of the above materials G and 14B. As described above, in the present embodiment, the second layer 1 for red display is used.
Since the thickness of 4R is, for example, 32.8 nm, the thickness of silicon nitride film 74 is also 32.8 nm.

Thereafter, the photoresist film 73 is removed together with the silicon nitride film 74 formed thereon by using a lift-off method. As a result, as shown in FIG. 43, a second layer 14R for red display having a desired film thickness made of silicon nitride is formed.

Next, the substrate 11, the second layer 1 for red display
A photoresist is applied over the entire surface of the 4R and amorphous silicon films 70 and 72, and is exposed using a normal mask (not shown). Thus, the photoresist is patterned, and as shown in FIG. 44, a photoresist film 75 for forming the second layer 14G for green display is formed.

Subsequently, as shown in FIG. 45, a silicon nitride (SiN _x ) film 76 is formed over the entire surface of the photoresist film 75 and the amorphous silicon film 70. As described above, in the present embodiment, the second display for green display is performed.
Since the thickness of the layer 14G is, for example, 31.7 nm, the thickness of the silicon nitride film 76 is also 31.7 nm.

Thereafter, the photoresist film 75 is removed together with the silicon nitride film 76 formed thereon by using a lift-off method. As a result, as shown in FIG. 46, a second layer 14G for green display having a desired film thickness made of silicon nitride is formed.

Further, a photoresist is applied over the entire surface of the substrate 11, the second layers 14R and 14G for displaying red and green, and the amorphous silicon film 72, and is exposed using a normal mask (not shown). Thus, the photoresist is patterned, and as shown in FIG. 47, a photoresist film 77 for forming the second layer 14B for blue display is formed.

Subsequently, as shown in FIG. 48, a silicon nitride (SiN _x ) film 78 is formed over the entire surface of the photoresist film 77 and the amorphous silicon film 72. As described above, in the present embodiment, the second display for blue display is performed.
Since the thickness of the layer 14B is, for example, 22.8 nm, the thickness of the silicon nitride film 78 is also 22.8 nm.

Thereafter, the photoresist film 77 is removed together with the silicon nitride film 78 formed thereon by using a lift-off method. As a result, as shown in FIG. 49, a second layer 14B for blue display having a desired film thickness made of silicon nitride is formed.

Thereafter, in the first embodiment, FIG.
By the manufacturing steps described with reference to FIGS. 6 to 19, the optical switching element 10 as shown in FIGS. 1 and 2 is completed. Therefore, a detailed description of the steps that follow is omitted.

As described above, in the present embodiment, red,
Green / blue display optical multilayer structure 10R, 10G, 10
Since each layer of B is manufactured by a separate process for each color using the lift-off method, the number of processes is increased, but the optical switching element 10 capable of color display is manufactured by repeating a general process. be able to. Therefore, there is an advantage that the process conditions can be easily set as compared with the first embodiment using the gray scale masks 31, 32, and 33.

(Third Embodiment) Next, the third embodiment of the present invention will be described.
The optical switching element according to the embodiment will be described. FIG. 50 and FIG. 51 show a schematic configuration of the optical switching element 80 according to the present embodiment. The optical switching element 80 includes optical multilayer structures 80R, 80G, for displaying red, green, and blue formed on the same substrate 81.
80B.

The substrate 81 has three layers corresponding to the first layers 82R, 82G, and 82B for displaying red, green, and blue, respectively.
First recess 81R and second recess 81 having a two-dimensional shape
G, a third concave portion 81B is formed. Then, the first layers 82R, 82G, 82 for displaying red, green, and blue are displayed.
B indicates the first concave portion 81R, the second concave portion 81G, and the third concave portion 81R.
Is formed so as to be embedded in the concave portion 81B. Except for this, the substrate 81 and the first layers 82R, 82G, and 82B for displaying red, green, and blue are the same as the substrate 11 and the first layer 1 for displaying red, green, and blue according to the first embodiment.
Since it has the same configuration as 2R, 12G, and 12B,
Further detailed description is omitted.

First layer 82 for displaying red, green and blue
Except for R, 82G and 82B, the optical switching element 80
All have the same configuration, operation and effect as the optical switching element 10 according to the first embodiment. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

Referring to FIGS. 52 to 55, in the method of manufacturing optical switching element 80 according to the present embodiment, steps different from those in the first or second embodiment, that is, in red, green, and blue. First layers 82R, 82 for display
Only the steps of forming G and 82B will be described.

First, as shown in FIG. 52, a substrate 81 made of, for example, carbon is prepared. Then, as shown in FIG. 53, the first layer 8 for displaying red is
A first recess 81R having the same three-dimensional shape as 2R, a second recess 81G having the same three-dimensional shape as the first layer 82G for green display, and a third recess 81G having the same three-dimensional shape as the first layer 82B for blue display. The third concave portion 81B having a dimensional shape is formed using, for example, an ion beam.

Next, as shown in FIG.
The first layer 82 for displaying red, green, and blue is formed by the D method.
For example, a tantalum film 82 is formed over the entire surface of the substrate 81 as a thin film for forming R, 82G, and 82B.

Subsequently, as shown in FIG.
The tantalum film 82 is formed by a (Chemical Mechanical Polishing) method into a first layer 82 for displaying red, green and blue.
R, 82G, and 82B are formed into desired film thicknesses and flattened. Thus, the first layers 82R, 82G, and 82B for displaying red, green, and blue are formed in a state of being embedded in the substrate 81.

Subsequently, the first embodiment using the gray scale mask or the second embodiment using the lift-off method is used.
Optical switching element 8 using the manufacturing method of the third embodiment.
Zero remaining layers (or gaps) can be formed. Here, the detailed description is omitted.

As described above, according to the present embodiment, the first layers 82R, 82G, 82 for displaying red, green, and blue are displayed.
Since B is formed in a state embedded in the substrate 81, the first layers 82R, 82G, and 82 for displaying red, green, and blue are formed.
The surfaces of B are aligned on the same plane. Therefore, the difference in film thickness between the first layers 82R, 82G, and 82B for displaying red, green, and blue is eliminated, and the steps on the surfaces of the optical multilayer structures 80R, 80G, and 80B for displaying red, green, and blue are small. Become. Thereby, the flatness of the surface of the optical switching element 80 is improved.

(Image Display Apparatus) FIG. 56 shows an example of an image display apparatus according to one embodiment of the present invention.
The image display device 100 is a direct-view / reflection image display device using the optical switching element 10 according to each of the above-described embodiments. Of course, instead of the optical switching element 10, a third
It goes without saying that the optical switching element 80 according to the embodiment can also be used. Image display device 100
Is, for example, on the substrate 101, the optical switching element 10
Are arranged in a two-dimensional array so that an image can be viewed directly.

According to the image display device 100, the optical switching element 1 capable of high-speed response according to each of the above embodiments is provided.
Since 0 is used, it is possible to reduce the size and weight and not only to be suitable for use in a direct-view / reflection-type image display device in a portable information device, but also to be able to respond at high speed and to display a moving image with fast movement. Also, the optical switching element 10
Unlike the reflection type liquid crystal, since no polarizing plate is required, the image display device 100 has a high light use efficiency and a brighter image to be displayed.

In addition, since the optical switching element 10 is a voltage-controlled element, when it is applied to the image display device 100, the power consumption becomes very small. Furthermore, if an opaque material such as carbon that absorbs light is used as the substrate 11 of the optical switching element 10, unnecessary light can be absorbed by the substrate 11, so that image display using the optical switching element 10 The device 100 can be expected to improve the contrast.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and can be variously modified. For example, in the above-described embodiment, the optical multilayer structure 10R, 1 for displaying red, green, and blue is used.
Although the optical switching element 10 that drives the 0G and 10B using static electricity has been described, as a method of driving the optical multilayer structure, in addition to static electricity, a method using a micromachine such as a toggle mechanism or a piezoelectric element, or a magnetic force is used. There are various methods such as a method, a method using a shape memory alloy, and a method using a magnetic force.

Further, the first method using a gray scale mask
Manufacturing method according to the embodiment of the present invention and a second method using a lift-off method.
The manufacturing methods according to the embodiments can be appropriately combined and adopted.

In the above embodiment, a direct-view / reflection type image display device in which the optical switching elements 10 are arranged in a two-dimensional array on the glass substrate 101 has been described.
Instead of 01, a paper-like display using a flexible (flexible) substrate having a film thickness of, for example, 2 mm or less may be provided.

Further, in the above-described embodiment, an example was described in which the optical switching element of the present invention was used in a direct-view / reflection type image display device. It is clear that application to an image display device is also possible. Furthermore, the present invention can be applied to various devices such as an optical printer other than the image display device, for example, drawing an image on a photosensitive drum using an optical printer.

[0141]

As described above, claims 1 to 1
According to the optical switching element described in any one of Items 5,
Since the red, green, and blue display optical multilayer structures having the same configuration except that the film thickness (or size) of each layer (or gap) is different for each color on the same substrate, the configuration is simple. And the size can be reduced. Therefore, when applied to an image display device, the size and weight can be reduced, and the response speed increases as the size is reduced, so that the effect of improving the quality of moving image display with fast movement can be expected. Further, since the optical switching element of the present invention does not require a polarizing plate unlike the reflection type liquid crystal, the image display device to which the optical switching element of the present invention is applied has high light use efficiency, and the displayed image is bright. Become.

In particular, according to the optical switching element of the third, fourth or fourteenth aspect, since a material having light absorption such as carbon is used for the substrate, unnecessary light can be absorbed by the substrate. . Therefore, the image display device using the optical switching element has a further effect that an improvement in contrast can be expected.

According to the optical switching element of the tenth aspect, since the optical multilayer structure for displaying red, green and blue is driven by electrostatic force, image display using the optical switching element of the present invention is performed. The power consumption of the device is very low.

In addition, any one of claims 16 to 25
In the method of manufacturing an optical switching element described in (1), the first, second, and third gray scale masks are used when forming each layer (or gap) of the optical multilayer structure for red, green, and blue display. As a result, the number of steps can be reduced, and a red, green, and blue display optical multilayer structure in which the film thickness (or size) of each layer (or gap) differs for each color can be easily and accurately formed. This has the effect.

Further, any one of claims 26 to 32
According to the method for manufacturing an optical switching element described in (1), the lift-off method is used when forming each layer (or gap) of the optical multilayer structure for red, green, and blue display. And the process conditions can be easily set.

According to the method for manufacturing an optical switching element according to the twenty-fifth or thirty-second aspect, the first layer for displaying red, green, and blue is formed in a state of being embedded in the substrate. The surfaces of the first layers for displaying red, green, and blue are aligned on the same plane. Therefore, the difference in film thickness between the first layers for displaying red, green, and blue is eliminated, and the step on the surface of the optical multilayer structure for displaying red, green, and blue is reduced. Thereby, there is an effect that the flatness of the surface of the optical switching element is improved.

In the image display device according to the thirty-third aspect, 1
A two-dimensional color image is displayed by irradiating light to the plurality of optical switching elements of the present invention that are arranged two-dimensionally or two-dimensionally. Not only is it suitable for use as a reflection-type image display device, but also because it can respond at high speed, it is possible to display a moving image with fast movement.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of an optical switching element according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the optical switching device shown in FIG.
It is sectional drawing along the line.

FIG. 3 is a cross-sectional view for explaining a manufacturing process of the optical switching element shown in FIG.

FIG. 4 is a cross-sectional view for describing a step that follows the step of FIG.

FIG. 5 is a cross-sectional view for describing a step that follows the step of FIG.

FIG. 6 is a cross-sectional view for describing a step that follows the step of FIG.

FIG. 7 is a cross-sectional view for explaining a step that follows the step of FIG.

8 is a cross-sectional view for explaining a step that follows the step of FIG.

FIG. 9 is a cross-sectional view for describing a step that follows the step of FIG.

FIG. 10 is a cross-sectional view for explaining a step that follows the step of FIG.

11 is a cross-sectional view for explaining a step that follows the step of FIG.

FIG. 12 is a cross-sectional view for describing a step that follows the step of FIG.

FIG. 13 is a cross-sectional view for explaining a step that follows the step of FIG.

FIG. 14 is a cross-sectional view for explaining a step that follows the step of FIG.

FIG. 15 is a cross-sectional view for explaining a step that follows the step of FIG.

16 is a cross-sectional view for describing a step that follows the step of FIG.

17A and 17B are views for explaining a step that follows the step of FIG. 16, wherein FIG. 17A is a plan view and FIG. 17B is a cross-sectional view taken along line BB of FIG.

FIG. 18 is a plan view illustrating a step that follows the step of FIG.

19 is a cross-sectional view of the optical switching element shown in FIG. 18, where (A) is a cross-sectional view taken along line AA of FIG. 18;
FIG. 19B is a sectional view taken along line BB of FIG. 18.

20 is a cross-sectional view for explaining driving of the optical switching element shown in FIG.

21 is a cross-sectional view for explaining driving of the optical switching element shown in FIG.

FIG. 22 is a cross-sectional view for explaining a manufacturing process of the optical switching element according to the second embodiment of the present invention.

FIG. 23 is a cross-sectional view for explaining a step that follows the step of FIG. 22.

24 is a cross-sectional view for describing a step that follows the step of FIG.

FIG. 25 is a cross-sectional view for describing a step that follows the step of FIG. 24.

FIG. 26 is a cross-sectional view for explaining a step that follows the step of FIG. 25.

FIG. 27 is a cross-sectional view for explaining a step that follows the step of FIG. 26.

FIG. 28 is a cross-sectional view for describing a step that follows the step of FIG. 27.

FIG. 29 is a cross-sectional view for describing a step that follows the step of FIG. 28.

FIG. 30 is a cross-sectional view for explaining a step that follows the step of FIG. 29.

FIG. 31 is a cross-sectional view for describing a step that follows the step of FIG. 30.

FIG. 32 is a cross-sectional view for explaining a step that follows the step of FIG. 31.

FIG. 33 is a cross-sectional view for describing a step that follows the step of FIG. 32.

FIG. 34 is a cross-sectional view for explaining a step that follows the step of FIG. 33.

FIG. 35 is a cross-sectional view for explaining a step that follows the step of FIG. 34.

FIG. 36 is a cross-sectional view for explaining a step that follows the step of FIG. 35.

FIG. 37 is a cross-sectional view for explaining a step that follows the step of FIG. 36.

FIG. 38 is a cross-sectional view for explaining a step that follows the step of FIG. 37.

FIG. 39 is a cross-sectional view for describing a step that follows the step of FIG. 38.

40 is a cross-sectional view for describing a step that follows the step of FIG. 39.

FIG. 41 is a cross-sectional view for describing a step that follows the step of FIG. 40.

FIG. 42 is a cross-sectional view for explaining a step that follows the step of FIG. 41.

FIG. 43 is a cross-sectional view for describing a step that follows the step of FIG. 42.

FIG. 44 is a cross-sectional view for describing a step that follows the step of FIG. 43.

FIG. 45 is a cross-sectional view for describing a step that follows the step of FIG. 44.

FIG. 46 is a cross-sectional view for illustrating a step that follows the step of FIG. 45.

FIG. 47 is a cross-sectional view for illustrating a step that follows the step of FIG. 46.

FIG. 48 is a cross-sectional view for explaining a step that follows the step of FIG. 47.

FIG. 49 is a cross-sectional view for describing a step that follows the step of FIG. 48.

FIG. 50 is a plan view illustrating a schematic configuration of an optical switching element according to a third embodiment of the present invention.

FIG. 51—51- of the optical switching element shown in FIG. 50;
It is sectional drawing which followed the 51 line.

FIG. 52 is a cross-sectional view for explaining a manufacturing step of the optical switching element shown in FIG. 50.

FIG. 53 is a cross-sectional view for explaining a step that follows the step of FIG. 51.

FIG. 54 is a cross-sectional view for describing a step that follows the step of FIG. 52.

FIG. 55 is a cross-sectional view for describing a step that follows the step of FIG. 53.

FIG. 56 is a diagram illustrating a configuration of an example of an image display device according to the present invention.

[Explanation of symbols]

10, 80 ... optical switching element, 10R, 80R ... optical multilayer structure for red display, 10G, 80G ... optical multilayer structure for green display, 10B, 80B ... optical multilayer structure for blue display, 11, 81 ... substrate, 12R, 82R: first layer for red display; 12G, 82G: first layer for green display; 12B, 82B: first layer for blue display; 13R;
Red display gap, 13G ... Green display gap, 13B
... Blue display gap, 14R ... Second layer for red display
14G: second layer for green display, 14B: second layer for blue display, 15R: transparent conductive film for red display, 15G: transparent conductive film for green display, 15B: transparent conductive film for blue display,
16 spacer, 17 cover glass, 18R red filter, 18G green filter, 18B blue filter, 21 first photoresist layer, 22 second photoresist layer, 23 third photoresist layer , 31 ...
First grayscale mask, 32... Second grayscale mask, 33... Third grayscale mask, 81
R: first concave portion, 81G: second concave portion, 81B: third concave portion, 100: image display device

Continued on the front page F term (reference) 2H041 AA02 AA04 AB14 AC06 AZ02 AZ03 AZ08 2H048 GA01 GA07 GA09 GA12 GA22 GA23 GA25 GA35 GA51 GA57 GA60 GA61

Claims (33)

[Claims] 1. A red display first layer having light absorption on a substrate, a red display gap having a size capable of causing light interference and having a variable size, and a red display. An optical multilayer structure for red display having a structure in which a second layer for light emission is provided; a first layer for green display with light absorption on the substrate;
A green display optical multilayer structure having a structure in which a green display gap having a size capable of causing light interference and having a variable size, and a green display second layer are provided; A first layer for light-absorbing blue display on a substrate,
An optical multilayer structure for blue display having a structure in which a blue display gap having a size capable of causing a light interference phenomenon and having a variable size, and a second layer for blue display are provided; Driving means for changing the optical size of the red display gap, the green display gap or the blue display gap, wherein the red display gap and the green display are driven by the driving means. An optical switching element, wherein the amount of reflection, transmission, or absorption of incident light is changed by changing the size of the gap or the gap for blue display. 2. In the optical multi-layer structure for red display, the first layer for red display, the gap for red display, and the second layer for red display are arranged on the substrate in this order. In the green display optical multilayer structure, the green display first layer, the green display gap, and the green display second layer are arranged in this order on the substrate. In the blue display optical multilayer structure, the blue display first layer, the blue display gap, and the blue display second layer are arranged in this order on the substrate. 2. The optical switching element according to claim 1, wherein the optical switching element is disposed. 3. The optical switching element according to claim 1, wherein the substrate is a substrate that absorbs light or a substrate on which a thin film that absorbs light is formed. 4. The optical switching element according to claim 1, wherein said substrate is made of carbon. 5. The method according to claim 1, wherein the second layer for displaying red, the second layer for displaying green, and the second layer for displaying blue are formed of a transparent material. The optical switching element according to claim 1. 6. The optical unit according to claim 6, wherein the driving unit sets the optical size of the red display gap, the green display gap, or the blue display gap to an odd multiple of λ / 4 and an even number of λ / 4. The amount of reflection, transmission, or absorption of incident light is changed in a binary or continuous manner by changing the value of the incident light in a binary or continuous manner between times (including 0). 2. The optical switching element according to 1. 7. The first layer for red display, the first layer for green display, the first layer for blue display, the second layer for red display, and the second layer for green display. 2. The device according to claim 1, wherein at least one of the second layer and the second layer for blue display is a composite layer including two or more layers having optical characteristics different from each other. Optical switching element. 8. The method according to claim 1, wherein the second layer for displaying red, the second layer for displaying green, and the second layer for displaying blue are made of a silicon nitride (SiN _x ) film. The optical switching element according to claim 5. 9. The red display second layer, the green display second layer, and the blue display second layer are made of a silicon nitride (SiN _x ) film and a transparent conductive film. The optical switching element according to claim 8, wherein: 10. The first layer for displaying red, the first layer for displaying green, the first layer for displaying blue, the second layer for displaying red, and the layer for displaying green. At least one of the second layer and the second layer for blue display includes a transparent conductive film in part, and the driving unit generates an electrostatic force generated by applying a voltage to the transparent conductive film. The optical switching element according to claim 1, wherein the optical size of the gap for red display, the gap for green display, or the gap for blue display is changed. 11. The transparent conductive film is made of ITO, SnO ₂
The optical switching element according to claim 10, wherein the optical switching element is formed of any one of ZnO and ZnO. 12. The first layer for red display, the first layer for green display, and the first layer for blue display,
2. The optical switching device according to claim 1, wherein the optical switching device is made of any one of a metal, a metal oxide, a metal nitride, a carbide, and a semiconductor. 13. The device according to claim 1, wherein the first layer for displaying red, the first layer for displaying green, and the first layer for displaying blue are made of tantalum (Ta). Optical switching element. 14. The substrate is made of carbon, and the first layer for red display, the first layer for green display, and the first layer for blue display are made of tantalum (Ta). A second layer for displaying red, a second layer for displaying green
And the second layer for blue display are made of silicon nitride (S
2. The optical switching device according to claim 1, comprising an iN _x ) film and a transparent conductive film made of ITO. 15. The substrate has a first recess having the same three-dimensional shape as the first layer for red display, and a second recess having the same three-dimensional shape as the first layer for green display. A third concave portion having the same three-dimensional shape as the first layer for blue display, wherein the first layer for red display is embedded in the first concave portion, The optical switching element according to claim 1, wherein a first layer is embedded in the second recess, and the first layer for blue display is embedded in the third recess. 16. Using a first gray scale mask, a first layer for red display, a first layer for green display, and a first layer for blue display having different film thicknesses are formed on a substrate. A red display having different sizes from each other as a sacrificial layer on the first layer for red display, the first layer for green display, and the first layer for blue display. Forming an amorphous silicon (a-Si) film having a three-dimensional shape corresponding to the gap for display, the gap for green display, and the gap for blue display using a second grayscale mask; Using a third gray scale mask, a second layer for red display, a second layer for green display, and a second layer for blue display having different thicknesses are formed on the amorphous silicon film. Forming, and removing the amorphous silicon film by etching. Forming the red display gap, the green display gap, and the blue display gap having different sizes from each other. 17. A transparent conductive film for red display and a transparent conductive material for green display on the second layer for red display, the second layer for green display and the second layer for blue display. 17. The method for manufacturing an optical switching element according to claim 16, further comprising a step of forming a film and a transparent conductive film for blue display. 18. A pair of spacers for bonding a cover glass to each of the optical multilayer structure for red display, the optical multilayer structure for green display, and the optical multilayer structure for blue display. 17. The method for manufacturing an optical switching element according to claim 16, comprising a step of forming. 19. The step of forming the first layer for red display, the first layer for green display, and the first layer for blue display comprises: forming a metal film on a substrate; Forming a first photoresist film on the metal film, exposing the first photoresist film to light using a first grayscale mask, and processing the first photoresist film into a three-dimensional shape; And etching the first photoresist film together to form a first layer for red display, a first layer for green display, and a first layer for blue display having different thicknesses from each other. 17. The method for manufacturing an optical switching element according to claim 16, comprising the steps of: 20. In the step of exposing the first photoresist film, the thickness T _P1 of the first photoresist film after exposure satisfies the following expression (1): T _P1 = R _P1. D _P1 (1) (where R _P1 represents the ratio of the etching rate of the first photoresist film to the etching rate of the metal film, and D _P1 is the most film thickness of the first photoresist film after exposure. 20. The method for manufacturing an optical switching element according to claim 19, wherein a difference in film thickness between a portion having a small thickness and a portion other than the portion having the smallest thickness is represented. 21. The step of forming the amorphous silicon (a-Si) film includes: forming the first layer for red display, the first layer for green display, and the first layer for blue display. Forming an amorphous silicon (a-Si) film as a sacrificial layer on the layer; forming a second photoresist film on the amorphous silicon film; Processing the film into a three-dimensional shape by exposing the film to light using a second gray scale mask; and etching the amorphous silicon film and the second photoresist film together to obtain a size 17. A step of processing the amorphous silicon layer into a three-dimensional shape to form different red display gaps, green display gaps, and blue display gaps. Optical switching element Manufacturing method. 22. In the step of exposing the second photoresist film, the film thickness T _P2 of the second photoresist film after exposure satisfies the relationship of the following equation (2): T _P2 = R _P2. D _P2 (2) (where R _P2 represents the ratio of the etching rate of the second photoresist film to the etching rate of the amorphous silicon film, and D _P2 represents the ratio of the etching rate of the second photoresist film after exposure. 22. The method of manufacturing an optical switching element according to claim 21, wherein a difference in film thickness between a portion having the smallest film thickness and a portion other than the portion having the smallest film thickness is represented. 23. The step of forming the second layer for red display, the second layer for green display, and the second layer for blue display, the step of forming a nitride layer on the amorphous silicon film Forming a silicon film; forming a third photoresist film on the silicon nitride film; and exposing the third photoresist film to light using a third gray scale mask to form a three-dimensional shape. Processing, and etching the silicon nitride film and the third photoresist film together to form a second layer for red display, a second layer for green display, and a blue display having different film thicknesses from each other. Forming a second layer for use in the optical switching element according to claim 16. 24. In the step of exposing the third photoresist film, the thickness T _P3 of the third photoresist film after exposure satisfies the following equation (3): T _P3 = R _P3. D _P3 (3) (where R _P3 represents the ratio of the etching rate of the third photoresist film to the etching rate of the silicon nitride film, and D _P3 is the most of the third photoresist film after exposure. 24. The method for manufacturing an optical switching element according to claim 23, wherein a difference in film thickness between a portion having a small film thickness and a portion other than the portion having the smallest film thickness is represented. 25. The step of forming the first layer for displaying red, the first layer for displaying green, and the first layer for displaying blue, comprises: forming the first layer for displaying red on the substrate; A first recess having the same three-dimensional shape as the first layer; a second recess having the same three-dimensional shape as the first layer for green display; and a third recess having the same three-dimensional shape as the first layer for blue display. Forming a third concave portion having a three-dimensional shape; and forming the first layer for red display, the first layer for green display, and the first layer for blue display by the first layer. Recess,
Forming the first layer for the red display, the first layer for the green display, and the blue display using a CMP method. 17. The method for manufacturing an optical switching element according to claim 16, further comprising: forming the first layer for use to a desired thickness and flattening the first layer. 26. A step of forming a first layer for red display, a first layer for green display, and a first layer for blue display having different thicknesses on a substrate by a lift-off method. A red display gap having different sizes as a sacrificial layer on the first layer for red display, the first layer for green display, and the first layer for blue display, Forming an amorphous silicon (a-Si) film having a three-dimensional shape corresponding to the green display gap and the blue display gap by using a lift-off method; Forming a second layer for red display, a second layer for green display, and a second layer for blue display using a lift-off method, wherein the amorphous silicon film has different thicknesses; Are removed by etching, so that the red Forming a gap for color display, a gap for green display and a gap for blue display. 27. A transparent conductive film for red display and a transparent conductive material for green display on the second layer for red display, the second layer for green display and the second layer for blue display. 27. The method for manufacturing an optical switching element according to claim 26, further comprising a step of forming a film and a transparent conductive film for blue display. 28. A pair of spacers for bonding a cover glass to each of the red display optical multilayer structure, the green display optical multilayer structure, and the blue display optical multilayer structure. 27. The method for manufacturing an optical switching element according to claim 26, comprising a step of forming. 29. The step of forming the first layer for displaying red, the first layer for displaying green, and the first layer for displaying blue is performed by using a lift-off method on the substrate. Forming the first layer for red display having a desired film thickness; and forming the first layer for green display having a desired film thickness on the substrate by using a lift-off method. 27. The optical switching element according to claim 26, further comprising: forming a first layer for blue display having a desired film thickness on the substrate by using a lift-off method. Manufacturing method. 30. The step of forming the amorphous silicon (a-Si) film, comprising the steps of: forming a size of the red display gap on the first red display layer by using a lift-off method; Forming a first amorphous silicon film having a thickness equal to: a size equal to the size of the green display gap on the first green display layer by using a lift-off method. Forming a second amorphous silicon film having a thickness; and forming a film thickness equal to the size of the blue display gap on the first blue display layer by using a lift-off method. Forming a third amorphous silicon film having the following characteristics. 27. The method according to claim 26, further comprising: 31. The step of forming the second layer for red display, the second layer for green display, and the second layer for blue display, comprising the steps of: Using the lift-off method,
Forming a second layer for red display having a desired film thickness, and using a lift-off method on the amorphous silicon film,
Forming a second layer for green display having a desired film thickness, and using a lift-off method on the amorphous silicon film,
27. The method according to claim 26, further comprising: forming a second layer for blue display having a desired film thickness. 32. The step of forming the first layer for displaying red, the first layer for displaying green, and the first layer for displaying blue, comprises: forming the first layer for displaying red on the substrate; A first concave portion having the same three-dimensional shape as the first layer, a second concave portion having the same three-dimensional shape as the first layer for green display, and a third concave portion having the same three-dimensional shape as the first layer for blue display. Forming a third concave portion having a three-dimensional shape; and forming the first layer for red display, the first layer for green display, and the first layer for blue display by the first layer. Recess,
Forming the first layer for the red display, the first layer for the green display, and the blue display using a CMP method. 27. The method for manufacturing an optical switching element according to claim 26, further comprising: forming the first layer for use to a desired film thickness and flattening the first layer. 33. An image display device for displaying a two-dimensional image in color by irradiating light to a plurality of one-dimensionally or two-dimensionally arranged optical switching elements, wherein the optical switching elements are: A red display first layer having light absorption, a red display gap having a size capable of causing a light interference phenomenon and having a variable size, and a red display second layer are provided. An optical multilayer structure for red display having a structure as described above, and a first layer for green display with light absorption on the substrate,
A green display optical multilayer structure having a structure in which a green display gap having a size capable of causing light interference and having a variable size, and a second layer for green display are provided; A first layer for light-absorbing blue display on a substrate,
An optical multilayer structure for blue display having a structure in which a blue display gap having a size capable of causing a light interference phenomenon and having a variable size, and a second layer for blue display are provided; An image display device comprising: a driving unit that changes an optical size of the gap for red display, the gap for green display, or the gap for blue display.