JP2003315691A - Image display element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display element which is small in size, high in density of integration, low in manufacturing cost and functions as an MEM (mechanical electromodulator) element of a transmission type by using a facility for manufacturing a semiconductor. <P>SOLUTION: The MEM element has an Si (silicon) substrate 1 having a thickness to transmit visible rays, an insulating layer 2 formed in contact with the top surface of the Si substrate 1, a lower electrode layer 3 formed in contact with the top surface of the insulating layer 2, a sacrificial gap 4 of the space formed in the partial region atop the layer 3, a movable film 5 formed to cove the gap 4 atop the layer 3, an upper electrode 6 formed in contact with the upper part of the movable film 5, a contact hole 7 pepetrating from the surface of the movable film 5 down to the surface of the layer 3, and a lower electrode 8 formed up to the surface of the layer 3 through the contact hole 7 from the circumference in the upper part of the contact hole 7. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device and a method for manufacturing the same, and more particularly to a transmissive MEM (Mechanic).
al Electro Modulator: An image display element that functions as a mechanical electro-optical modulator and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, various types of image display devices have been proposed, and examples of devices using typical ones include CRT (cathode ray tube) display devices and LCD (liquid crystal) devices.
Display devices, LED (light emitting diode) display devices, plasma display devices, and the like have been put into practical use. In particular, as a reflective image display device, LCOS (Liquid Crystal on Si) is used.
Is well known and is used as a reflection type liquid crystal projector and a small image display device.

In recent years, as an image display device, M
An EM device has been proposed, which is an electromechanical optical modulation in which a flexible thin film manufactured by a micromachining technique on a glass substrate or a plastic film is mechanically operated by electrostatic force to perform optical modulation. The element is conventionally known as a transmissive display element. More specifically, as the light modulation element, there is, for example, one in which a flexible thin film composed of a transparent electrode and a diaphragm is provided on a fixed electrode on a light source via a support portion. In this light modulation element, by applying a predetermined voltage between both electrodes, an electrostatic force is generated between the electrodes, and the flexible thin film is bent toward the fixed electrode. Along with this, the optical characteristics of the element itself change, and light passes through the light modulation element. On the other hand, when the applied voltage is set to zero, the flexible thin film elastically recovers, and the light modulation element blocks light. Light modulation is performed in this way. Figure 5
It is sectional drawing which shows the internal structure of the type which utilizes the interference which is one of the conventional MEM elements. In the MEM element shown in FIG. 5, two upper and lower transparent electrodes 94 are formed at intervals on the upper surface of a glass substrate 91, and the lower transparent electrode 94 is formed.
Two upper and lower half mirrors 92 are arranged on the upper part of the above through two spacers 95. In the space between the two half mirrors 92 and the two spacers 95,
A transparent spacer 93 made of an insulating material is formed in contact with the lower half mirror 92. The upper transparent electrode 94 described above is formed on the upper half mirror 92.

Since no voltage is applied between the upper and lower transparent electrodes 94 in the MEM device shown in FIG. 5, the upper half mirror 92 is formed without being adhered to the transparent spacer 93. State, and as a result, the collimated planar light source 96 disposed below the glass substrate 91.
The light 97 emitted from is reflected by the lower half mirror 92 and does not pass through the MEM element body.

FIG. 6 shows the MEM element shown in FIG.
It is sectional drawing which shows an internal state at the time of applying a voltage between two transparent electrodes of upper and lower sides. In the MEM element shown in FIG.
As a result of the voltage being applied between the upper and lower two transparent electrodes 94 of the MEM element shown in FIG. 5, an electrostatic force due to the applied voltage acts between the transparent electrodes 94, and the upper transparent electrode 94 and the upper transparent electrode below the transparent electrode 94. The half mirror 92 is pushed downward, and the upper half mirror 92 is brought into close contact with the transparent spacer 93, and the transmittance of light in the optical path orthogonal to the upper and lower half mirrors 92 is increased. As a result, the collimated planar light source is obtained. Light 97 emitted from 96 passes through the MEM element body and
Appropriate scattering is obtained by the glass substrate 98 arranged on the upper side of the EM element body.

[0006]

The display devices using the above-mentioned conventional image display elements have their respective problems. For example, a CRT display device has a problem that it is difficult to miniaturize the device, and if it is miniaturized, it is difficult to uniformly improve the life and reliability, and the power consumption increases. Also, the LCD display device
With respect to those requiring backlight light, there is a problem in that the use efficiency of the light becomes a problem, and further, a high-cost TFT (thin film transistor) is required. In addition, the LED display device includes a light emitting diode, particularly a blue light emitting diode, which has a price and lifespan.
The problem is the manufacturing cost of the dimensional array. Further, as the plasma display device, as an essential problem, it is necessary to form a circuit in which the control system of the image signal and the control system of the power supply necessary for the fluorescence emission are integrated, so that the control system of the image signal becomes huge. In addition, there is a problem that the operation speed cannot be increased.

Incidentally, M, which is one of the conventional image display elements,
Since the EM element is formed on a glass substrate or a plastic film, there is a problem that it is necessary to introduce a special machining technique and the degree of integration cannot be improved. Further, it is necessary to arrange and connect a semiconductor circuit for converting / processing an image signal into a signal form suitable for the MEM element and driving the same as a device separate from the MEM element, and these cannot be integrated. There was a problem such as.

The present invention has been made in view of the above-mentioned problems in the conventional image display device and the manufacturing method thereof, and is small in size and high in the integration density by using the semiconductor manufacturing equipment, and the manufacturing cost is high. It is an object of the present invention to provide an image display device that functions as a transmissive MEM device at low cost.

Another object of the present invention is to provide a method of manufacturing an image display device which functions as a transmissive MEM device using a semiconductor manufacturing facility, which is small in size, has a high integration density, and is low in manufacturing cost. To do.

[0010]

In order to solve the above problems, the present invention provides an image display device according to claim 1, wherein
Transmission that has upper and lower two electrode layers formed at intervals and changes the transmittance of light emitted from a direction orthogonal to the horizontal direction of the main body by applying a voltage between the two electrode layers. Type electromechanical optical modulator, wherein the main body including the two-layer electrodes as constituent elements is formed on a silicon substrate having a predetermined transmittance for visible light. A modulator element is provided.

The image display device according to claim 2 is the image display device according to claim 1, wherein the silicon substrate has a predetermined transmittance for at least a part of visible light in a wavelength range of 400 to 650 nm. A mechanical-electro-optical modulator is provided.

An image display device according to a third aspect is the image display device according to the second aspect, further comprising an insulating layer between the silicon substrate and an electrode layer below the two electrode layers. And a movable film between the two electrode layers, and a void portion covered with the movable film above the electrode layer below the two electrode layers. A light modulation element is provided.

According to a fourth aspect of the present invention, there is provided the image display element according to the third aspect, in which the surface of the end portion of the movable film which is separated from the upper portion of the void portion includes the two layers from the surface. There is provided a mechanical-electro-optical modulation device having a contact hole penetrating to a surface of the electrode layer below the electrode layer.

According to a fifth aspect of the present invention, in the image display element according to the fourth aspect, the inner surface of the electrode layer below the two electrode layers is penetrated under the contact hole. There is also provided a mechanical-electro-optical modulator comprising a lower electrode having electrical contact with the electrode layer.

An image display device according to claim 6 is the image display device according to any one of claims 1 to 5, wherein the voltage is applied between the two layers of electrodes on the silicon substrate. Provided is a mechanical-electro-optical modulator, wherein a semiconductor circuit for supplying a driving voltage is formed.

Further, as the image display element according to claim 7, in the image display element according to claim 6, an image signal processing semiconductor circuit for controlling the drive voltage is formed on the silicon substrate. A mechanical electro-optical modulator is provided.

Further, as a method of manufacturing an image display element according to any one of claims 8 to 12, a method of manufacturing a mechanical-electro-optical modulator for manufacturing the mechanical-electro-optical modulator according to any one of claims 1 to 5 is disclosed. It

That is, in the present invention, a silicon substrate is used in place of the conventional glass substrate or plastic film on which the main part of the MEM element is formed, and M is formed on the silicon substrate.
After forming the main part of the EM element, the bottom surface of the silicon substrate is scraped off until the silicon substrate transmits visible light with a predetermined transmittance, whereby a transmissive MEM element can be manufactured using the method for manufacturing a semiconductor device. As a result, the miniaturized transmissive M that can increase the integration degree without using a special technique such as a micromachining technique.
The EM element can be manufactured at a low cost. Further, another semiconductor circuit related to the manufactured MEM element can be simultaneously and integrally formed on the silicon substrate.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an internal configuration of an image display device according to an embodiment of the present invention. The image display element according to the present embodiment shown in FIG. 1 has a Si (silicon) substrate 1 having a thickness that allows visible light to pass therethrough, and an insulating layer 2 formed in contact with the upper surface of the Si substrate 1.
And the lower electrode layer 3 formed in contact with the upper surface of the insulating layer 2.
A sacrificial layer void 4 in a space formed in a partial region of the upper surface of the lower electrode layer 3, a movable film 5 formed on the upper surface of the lower electrode layer 3 so as to cover the sacrificial layer void 4, and an upper portion of the movable film 5. An upper electrode layer 6 formed in contact with the contact hole 7, a contact hole 7 penetrating from the surface of the movable film 5 outside the sacrificial layer void 4 to the surface of the lower electrode layer 3, and a contact from around the upper portion of the contact hole 7. The lower electrode 8 is formed to the surface of the lower electrode layer 3 through the hole 7.

FIG. 2 is a table showing a combination of typical material compositions forming the constituent elements of the image display device according to the embodiment of the present invention. In the table shown in FIG. 2, as possible material combinations, for example, in the combination example of combination number 1, silicon dioxide (SiO 2) as the insulating layer 2,
Polysilicon (PolySi) as the lower electrode layer 3, aluminum (Al) as the sacrificial layer 41, silicon nitride (SiN) as the movable film 5, and ITO as the upper electrode layer 6.
(Indiumtin Oxide) is shown. The lower electrode 8 can have the same material composition as the upper electrode layer 6. In the table shown in FIG. 2, W is tungsten,
metal is any metal, PI is Poly-imi
means d). It should be noted that each of these components has a thickness such that visible light can be transmitted with a predetermined transmittance. It is preferable that the predetermined transmittance is as high as technically possible.

Further, in the table shown in FIG. 2, as the insulating layer 2 and the movable film 5, instead of SiO2, phosphosilicate glass (PSG), borosilicate glass (BSG), borophosphosilicate glass (BPSG), or a combination thereof is used. Composites can also be used. Similarly, as the lower electrode layer 3,
In addition to tungsten, molybdenum (Mo), gold (A
u), palladium (Pd), platinum (Pt), or alloys thereof can also be used. In addition, examples of the arbitrary metal include Al, Mo, and W.
However, it is necessary to select a different material for the lower electrode layer 3. Further, the upper electrode layer 6 may be tin oxide (SnO 2) in addition to ITO.

Next, the manufacturing process of the image display device according to this embodiment will be described. FIG. 3 is a cross-sectional view of each step showing the internal structure of each step of the image display device according to the embodiment of the present invention. First, in the step shown in FIG. 3A, the insulating layer 2 is formed on the upper surface of the Si substrate 10 similar to that used for manufacturing a semiconductor device. The insulating layer 2 is formed on the Si substrate 1 by using a thermal oxidation method, a CVD method or a high-density plasma CVD method such as ICP plasma CVD which is generally used in a semiconductor manufacturing process.
It is possible to form a film on the upper surface of 0. It is also possible to form the insulating layer 2 by a simple coating method.

Next, the lower electrode layer 3 is formed on the surface of the insulating layer 2. At this time, the lower electrode layer 3 can be formed on the surface of the insulating layer 2 by using the sputtering method. Poly
When Si is formed as the lower electrode layer, a CVD method or the like which is a general method in the semiconductor manufacturing process can be used. Further, when the surface of the lower electrode layer 3 needs to be a plane figure having a specific shape, it can be patterned by photolithography and etching in the semiconductor manufacturing technology. After that, a sacrifice layer 41 that will be removed in a later step is formed on a predetermined surface region of the lower electrode layer 3. At this time, the plane pattern of the sacrificial layer 41 can be formed by photolithography and etching, but it may be formed by mask vapor deposition using a mask that is matched to the plane shape in advance. In this way, the sacrificial layer 41 having an arbitrary pattern can be formed on the predetermined surface region of the lower electrode layer 3.

Next, in the step shown in FIG.
The movable film 5 that covers the lower electrode layer 3 and the sacrificial layer 41 formed in the step shown in (a) is formed. At this time, the movable film 5 that covers the lower electrode layer 3 and the sacrificial layer 41 can be formed by using a film forming method such as a CVD method. Further, the movable film 5 can be formed by a simple coating method.

In the step shown in FIG. 3C, first, as shown in FIG.
In order to secure electrical connection between the lower electrode layer 3 formed in (a) and the outside, a contact is made outside the region of the sacrificial layer 41 in the movable film 5 formed in FIG. 3 (b). Hole 7 is formed. The contact hole 7 can be formed by photolithography and etching. The upper electrode layer 6 is formed on the upper surface of the movable film 5 formed in the step shown by removing the right end portion (not shown) that does not overlap the sacrificial layer 41. At this time, the right end portion can be masked and the upper electrode layer 6 can be formed on the surface of the movable film 5 by using a sputtering method or the like.

After that, ITO or SnO 2 is formed as the upper electrode layer 6 on the surface of the movable film 5. here,
The upper electrode layer 6 can be formed on the front surface by a sputtering method, a coating method, or the like. The upper electrode layer 6 formed in this way
Is patterned by photolithography and etching processes after formation. In the patterning, the sacrificial layer 41 and the movable film 5 are sandwiched between the lower electrode layer 3 and the upper electrode layer 6 and patterned so as to form pixels. At the same time, the upper electrode layer 6 is also formed with a wiring pattern so that it can be electrically connected to the outside. Further, at the time of patterning the upper electrode layer 6, at the same time, a lower electrode 8 is formed so as to enable electrical connection from the contact hole 7 formed above to the outside, and a wiring region is left. The conductive layer used for forming the lower electrode 8 and wiring from the lower electrode 8 to the outside may be a layer different from the upper electrode layer 6.

Next, the sacrificial layer 41 under the movable film 5 formed in the step shown in FIG. 3A is removed to form the sacrificial layer void 4, and the movable portion as shown in FIG. 1 is provided. The finished image display device. At this time, etching or the like can be used to remove the sacrificial layer 41.

Finally, the bottom surface of the Si substrate 10 is etched to finish the thin Si substrate 1 having a predetermined transmittance for visible light. The thickness of the Si substrate 1 is a thickness capable of transmitting blue light (about 100 Å) of visible light and is as thick as technically possible,
Specifically, it is preferably 50 [μm] or less. Further, instead of the above etching, CMP (Chemical Mec
hanical Polishing) may be used.

FIG. 4 is an explanatory view showing a concrete example of use of the image display device according to the embodiment of the present invention. In the example of use shown in FIG. 4, the image element 22 which is the image display element according to the embodiment of the present invention uses the lens 2 for magnifying an image.
1, a diffusion layer 23 for obtaining scattered light, and an LED 24 of three colors of R (red), G (green), and B (blue) that serves as a light source system.
Along with the (liquid crystal element), the center point is set to match the optical axis 20.

Next, the operation of the image display device according to this embodiment will be described. The image display element according to the present embodiment shown in FIG. 1 has a state in which no voltage is applied between the upper electrode layer 6 and the lower electrode 8 (state shown in FIG. 1) and an upper electrode layer 6
When a voltage is applied between the lower electrode 8 and the lower electrode 8 (not shown), in the latter state where a voltage is applied between the electrodes, an attractive force is generated between the electrodes due to the action of electrostatic force. As a result, the movable film 5 is brought into close contact with the lower electrode layer 3 to change the transmittance of light emitted in the vertical direction. As a result, in the image element 22 shown in FIG. 4, when the voltage is applied between the electrodes and the LED 24 arranged on the back side of the image element 22 is turned on, the light of the LED 24 is diffused in the diffusion layer 23. After that, it is projected on the display side through the Si substrate 1. Therefore, when the three colors of the LED 24 are sequentially turned on in accordance with the drive control of the image element 22, R / G / B
It is possible to obtain a color-displayed image by frame sequential printing.

In the structure shown in FIG. 4, the image element 22 can be directly seen without the lens 21 as long as the display image has a size that allows visual observation. Therefore, the lens is not an essential component in the image display device. Further, in the above configuration, a color image is displayed, but it is of course possible to obtain a monochrome image using a white light source. Although the above description has described a single pixel, the present invention is not limited to a single pixel. One-dimensional (on line)
The same applies to the case where the two-dimensional (planar) arrangement is performed.

As described above, according to the present embodiment, the same process as that for manufacturing a semiconductor element such as FET (electric field control transistor) is used without using a special technique such as a micromachining technique. Thus, a transmissive MEM element can be manufactured. Further, according to the present embodiment,
A semiconductor circuit for driving the image display element according to the present embodiment shown in FIG. 1 and a semiconductor circuit for converting or transmitting a signal supplied to the image display element are constituent elements of the image display element. On the same substrate as a certain Si substrate, at the same time as an extension circuit or an auxiliary circuit of the image display element,
And it can be integrally formed.

[0033]

As described above, according to the present invention, F
By using the same process as manufacturing a semiconductor device such as ET, a miniaturized transmissive MEM device capable of increasing the degree of integration can be reliably manufactured at low cost. Further, a semiconductor circuit necessary for driving the image display element and a semiconductor circuit for supplying a signal to the image display element are formed on the same substrate as the substrate on which the image display element is formed, and these are imaged. It can be manufactured integrally with the display element.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an internal configuration of an image display element according to an embodiment of the present invention.

FIG. 2 is a table showing a combination of typical material compositions forming constituent elements of the image display device according to the embodiment of the present invention.

FIG. 3 is a sectional view for each step showing an internal configuration for each step of the image display element according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a specific usage example of the image display element according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the internal structure of a conventional MEM element.

6 is a cross-sectional view showing an internal state when a voltage is applied between two upper and lower transparent electrodes in the MEM element shown in FIG.

[Explanation of symbols]

1, 10 Si substrate 2 insulating layers 3 Lower electrode layer 4 Sacrificial layer void 5 movable membrane 6 Upper electrode layer 7 contact holes 8 Lower electrode 20 optical axis 21 lens 22 Image display device 23 Diffusion layer 24 LED 41 Sacrificial layer

Continued front page    (72) Inventor Shintaro Washisu             200, Onakazato, Fujinomiya City, Shizuoka Prefecture Fuji Photo             Within Film Co., Ltd. F-term (reference) 2H041 AA02 AA05 AB16 AB40 AC06                       AZ02 AZ08

Claims (12)

[Claims] 1. A transmission of light emitted from a direction orthogonal to the horizontal direction of the main body by having two upper and lower electrode layers formed at intervals and applying a voltage between the two electrode layers. In a transmissive electromechanical modulator that changes the transmittance, the main body including the two-layer electrodes as constituent elements is formed on a silicon substrate having a predetermined transmittance for visible light. An image display device that functions as a mechanical electro-optical modulator. 2. The silicon substrate has a wavelength of 400 to 65.
The image display device according to claim 1, wherein the image display device has a predetermined transmittance for at least a part of visible light in the range of 0 nm. 3. An insulating layer is provided between the silicon substrate and an electrode layer below the two electrode layers, and a movable film is provided between the two electrode layers. The image display device according to claim 1, further comprising a void portion covered with the movable film, above the electrode layer below the electrode layer. 4. A contact hole penetrating from the surface to the surface of the electrode layer below the two-layer electrode layer on the surface of the end portion of the movable film which is separated from the upper portion of the void portion. The image display device according to claim 3, wherein 5. A lower electrode that penetrates through the inside of the contact hole to reach the surface of the electrode layer below the two electrode layers and has an electrical contact with the electrode layer. The image display device according to claim 4. . 6. The semiconductor circuit according to claim 1, wherein a semiconductor circuit for supplying a driving voltage applied between the electrodes of the two layers is formed on the silicon substrate.
An image display device according to item. 7. The image display device according to claim 6, wherein an image signal processing semiconductor circuit for controlling the drive voltage is formed on the silicon substrate. 8. A transmission of light emitted from a direction orthogonal to the horizontal direction of the main body by having two upper and lower electrode layers formed at intervals and applying a voltage between the two electrode layers. A method of manufacturing a transmissive electromechanical modulator that changes a rate, comprising: forming the main body including the two-layer electrodes as constituent elements on a silicon substrate; and forming the main body on the silicon substrate after forming the main body. And a step of scraping the bottom surface of the silicon substrate until the silicon substrate has a predetermined transmittance for visible light, and a method for manufacturing an image display element functioning as a mechanical-electro-optical modulator. 9. The method according to claim 8, further comprising a step of scraping the bottom surface of the silicon substrate after forming the main body until the silicon substrate has a predetermined transmittance for visible light having a wavelength of about 10Å. Image display device manufacturing method. 10. A step of forming an insulating layer between the silicon substrate and an electrode layer below the two-layer electrode layer, a step of forming a movable film between the two-layer electrode layers, 10. The method of manufacturing an image display element according to claim 8 or 9, further comprising: forming a void portion covered with the movable film on an upper portion of the electrode layer below the electrode layer of the layer. . 11. A contact hole penetrating from the surface to the surface of the electrode layer below the two electrode layers is formed on the surface of the end portion of the movable film, which is separated from the upper portion of the void portion. The method according to claim 1, further comprising a step.
0. A method for manufacturing an image display device according to 0. 12. A step of forming a lower electrode that penetrates through the inside of the contact hole to reach the surface of the electrode layer below the two-layer electrode layer and has electrical contact with the electrode layer. The method for manufacturing an image display device according to claim 11, wherein: