KR100223191B1 - Micromirror device and its fabrication method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micromirror display device and a method of manufacturing the same, and more particularly, to a micromirror display device and a method of manufacturing the same, which can display a high resolution image by applying to a projection TV (PTV), a high definition TV (HDTV), and the like. The unit micromirror display device of the present invention includes a unit micromirror that reflects incident light toward a screen, and an elastic barrier plate that moves around the unit micromirror according to a control operation of the driving circuit. Accordingly, the unit mirrors corresponding to each pixel may block or reflect incident light, thereby displaying a high resolution image on the screen, and may reduce manufacturing costs.

Description

Fine mirror display device and manufacturing method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micromirror display device and a method of manufacturing the same, which are applied to a device for displaying a high resolution image such as a projection television and a monitor, and particularly toward a screen as the elastic barrier plate moves around the unit mirror. The present invention relates to a micromirror display device and a method of manufacturing the same, capable of displaying a high resolution image by reflecting and blocking incident light.

In general, a cathode ray tube (CRT) has been used as an image display means for displaying an image on a screen, but since the late 1990s, a liquid crystal display (LCD) and a micro mirror device (DMD) have been used as new image display means. ) Is being rapidly researched. In particular, the micromirror display device has a superior light efficiency than the liquid crystal display device and is known as a suitable method for displaying a high quality image, an example of which is illustrated in FIG. 1.

1 is a perspective view illustrating a micromirror display device according to the related art, which is developed by Texas Instruments (TI). The micro mirror display device (DMD) belongs to a spatial light modulator (SLM) in a broad sense, and is a device capable of adjusting the position or intensity of light. Special light modulator (SLM) is a device that sends the input image information to the light sensor or to convert the actual image that can be seen by humans.

In Fig. 1, the electrode 14 is formed on a silicon substrate (not shown), and a mirror 11 reflecting incident light is positioned above the electrode 14, and the mirror 11 speaks to a post 13; It is supported and fixed on both sides by the hinge 12. The mirror 11 is a torsion mirror that is inclined as the electrostatic force with the electrode 14 is generated, and the mirror 11 is continuously arranged in all directions as many as the number of pixels constituting one image. Such an arrangement structure may be appropriately configured according to the overall size of the micromirror display element, and the size of one mirror 11 is approximately 16 μm × 16 μm. The mirror 11 is made of aluminum having a large light reflectance, and is inclined by the electrostatic force with the electrode 14. That is, when the mirror 11 is inclined to either side as shown in FIG. 2A, incident light is not reflected to the screen 15, and the corresponding pixel is turned off. However, as shown in FIG. 2B, when the mirror 11 is inclined, the incident light is reflected on the screen 15 so that the corresponding pixel is turned on.

However, in the conventional micromirror display device, since the brightness of the pixel is adjusted according to the on / off duration of the corresponding pixel, the driving circuit connected to the electrode 14 must satisfy a considerably fast processing speed. Information controlling on / off of each pixel is stored in an SRAM (static ram), and six SRAMs are required for one pixel, thereby increasing the manufacturing cost. In addition, since eight on / off operations are required for each pixel when displaying an image of one screen, there is a problem of fatigue fatigue phenomenon of the hinge 14. In addition, since the on / off operation of the mirror 11 is frequent, the mirror 11 is stuck due to a collision with the bottom surface, which makes it difficult to display a high quality image.

SUMMARY OF THE INVENTION An object of the present invention is to provide a micromirror display device capable of displaying a high-resolution image by driving control of an elastic barrier plate that can block incident light in a unit mirror corresponding to each pixel.

Another object of the present invention is to provide a method of manufacturing a micromirror that can display a high-resolution image by forming a unit micromirror and an elastic barrier plate on a silicon substrate.

1 is a perspective view showing a fine mirror display device according to the prior art,

2A is a view showing a case where a conventional fine mirror display element is in an off state;

2B is a view showing a case where a conventional fine mirror display device is in an on state;

3A is a perspective view showing a micromirror display device according to the present invention;

3B is a cross-sectional view of FIG. 3A,

Figure 4 is a perspective view of the elastic barrier plate of Figure 3a,

5A to 5C are views showing an operation example of the micromirror display device of the present invention;

6A to 6J illustrate a manufacturing process of the micromirror display device of the present invention.

※ Explanation of code for main part of drawing

11: mirror 12: hinge

13 support 14 electrode

15: screen 21: unit mirror

31: elastic barrier plate 32: blocking film

40: driving electrode 41: landing electrode

50: silicon substrate 51: insulating layer

52,53,54: sacrificial layer

An object of the present invention as described above is a display device in which a plurality of unit micromirrors controlled by a driving circuit of a substrate individually reflects incident light to form a predetermined image, by a pair of first supports formed on the substrate. A resilient shielding plate which is supported and has a blocking film formed on the body protruded to the first support to block the incident incident light; A reflector which is supported by a pair of second supports positioned above the elastic barrier plate, and formed with at least one of the unit micromirrors, and having a guide groove for moving the elastic barrier plate on the upper surface to reflect incident light; And a driving electrode positioned between the substrate and the elastic shielding plate to induce a predetermined voltage difference in accordance with the driving signal from the driving circuit to move the elastic shielding plate.

Another object of the present invention as described above is a method of manufacturing a display device in which a plurality of unit mirrors individually reflect incident light to form a predetermined image, and depositing a metal on an insulating layer coated on a silicon substrate and then etching the electrode. Forming; Depositing a first sacrificial layer on an upper surface including the electrode and forming a first opening for forming a first support; Depositing and etching a first component layer on an upper surface on which the first opening is formed to form an elastic barrier plate; Depositing a second sacrificial layer on the upper surface on which the elastic barrier plate is formed and forming a second opening for forming a second support; Forming a reflector by depositing and etching a second component layer on an upper surface of the second opening; Depositing a third sacrificial layer on an upper surface of the reflector and forming guide grooves for the barrier layer of the elastic barrier plate to move; Forming a blocking layer by depositing a fourth component layer on an upper surface of the guide groove; And removing the first to third sacrificial layers.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

According to the present invention, a plurality of unit mirrors controlled by a driving circuit of a substrate individually reflect incident light to form a predetermined image. Each of the unit mirrors is individually driven and controlled by a driving circuit formed on a substrate, and the structure and operation of any one unit mirror will be described with reference to FIG. 3.

3A is a perspective view illustrating a micromirror display device according to the present invention, and FIG. 3B is a cross-sectional view of FIG. 3A. As shown in the drawing, the micromirror display device according to the present invention has an elastic barrier plate 31 having a pair of first supports 31a fixedly supported on an upper surface of the landing electrode 41 and an upper portion of the landing electrode 41. A driving electrode which induces and swings a voltage difference between the reflective plate 21 having the pair of second supporters 21a fixed to the surface and the elastic barrier plate 31 according to the driving signal from the driving circuit of the silicon substrate ( 40).

The upper surface of the reflecting plate 21 reflects incident light incident from the side at a predetermined reflection angle, and the reflected incident light is incident on the screen side.

The driving electrode 40 and the pair of landing electrodes 41 positioned below the elastic barrier plate 31 are formed on the insulating layer 51 coated on the silicon substrate 50 (hereinafter, referred to as a substrate). The electrostatic force is generated between the driving electrode 40 and the elastic shielding plate 31 by the driving circuit formed on the substrate 50, which causes the elastic shielding plate 31 to be bent. The bending degree of the elastic barrier plate 31 is determined according to the magnitude of the electrostatic force, that is, controlled by the driving circuit. The elastic barrier plate 31 includes a pair of second supports 31a supported by the landing electrode 41 and a blocking film 32 formed integrally with the center of the upper surface to block incident light. The elastic barrier plate 31 has a bendable connection structure, but as shown in FIG. 4, the connection portion with the first support 31a is formed with a recess 31b, and the elastic force at the same time by the connection portion. Will have

The reflective plate 21 is made of a material having a large light reflectance, and preferably, aluminum (Al) or silver (Ag) is used as the material.

5 is a view showing an example of the operation of the micro-mirror display device of the present invention, Figure 5a shows a case where the incident light is completely blocked, Figure 5b shows a case of blocking a part of the incident light, Figure 5c reflects all the incident light The case is shown.

In FIG. 5A, the elastic barrier plate 31 maintains a horizontal state because no electrostatic force with the driving electrode 40 is generated, whereby the blocking film 32 formed on the upper surface is reflected from the right side by the reflecting plate 21. By blocking the incident light entirely, the incident light is not reflected to the screen side, which is not shown.

In FIG. 5B, when the electrostatic force between the elastic barrier plate 31 and the driving electrode 40 is generated, the elastic barrier plate 31 moves downward to the driving electrode 40 so as to correspond to the size of the electrostatic force. . As a result, the blocking film 32 moves downward and blocks only a part of the incident light reflected by the reflecting plate 21, and part of the blocking film 32 enters the screen side.

In FIG. 5C, when the electrostatic force between the elastic barrier plate 31 and the drive electrode 40 reaches the maximum value in the allowable range, the elastic barrier plate 31 moves downward in response to the generated electrostatic force and eventually the drive electrode 40. ) Is in contact with Accordingly, the blocking film 32 is moved downward to the state where the upper end is coincident with the upper surface of the reflecting plate 21, so that incident light incident on the reflecting plate 21 is incident on the screen side.

In this way, the elastic barrier plate 31 is moved by the generation of the electrostatic force with the drive electrode 40, the elastic barrier plate 31 can be moved upward or downward by the control of the drive circuit. Therefore, the driving circuit controls to appropriately block the incident light in order to adjust the brightness of the pixels constituting the image of one screen.

The manufacturing process of the above-mentioned micromirror display element is demonstrated with reference to FIG.

First, in FIG. 6A, a metal is deposited on the insulating layer 51 coated on the silicon substrate 50 and then etched to form a driving electrode 40 and a landing electrode 41. In this case, the driving electrode 40 and the landing electrode 41 are coated with a metal on the substrate 50 by sputtering or evaporation, and then a photoresist is applied thereto. It is formed by irradiating and etching light through. As a result, the driving electrode 40 and the landing electrode 41 are separated on the substrate 50.

Subsequently, the first sacrificial layer 52 is deposited on the entire upper surface as shown in FIG. 6B, and then a predetermined portion is etched to form a first opening 52a in which the first support 31a is to be formed (see FIG. 6C).

The first opening 52a may etch the corresponding portion by reactive ion etching (RIE) or photolithography.

Subsequently, a first component layer is deposited on the upper surface including the first opening 52a to form the elastic barrier plate 31 as shown in FIG. 6D. Subsequently, as shown in FIG. 6E, the second sacrificial layer 53 is deposited on the entire upper surface, and the second opening 53a is formed to form the second support 21a of the reflector 21. The second openings 53a etch the corresponding portions by reactive ion etching (RIE) or photolithography.

Subsequently, as illustrated in FIG. 6F, the second component layer 21 is deposited and etched on the entire upper surface including the second opening 53a to form the reflector 21. The reflector 21 is preferably a metal having high light reflectivity, and aluminum or silver is used.

Subsequently, as illustrated in FIG. 6G, the third sacrificial layer 54 is deposited and etched on the entire surface including the reflector 21 to form the guide groove 54a. Next, as illustrated in FIG. 6H, the fourth component layer 32 is deposited on the upper surface including the guide groove 54a. The fourth component layer uses metal or doped polysilicon and is deposited by electroplating.

Subsequently, as illustrated in FIG. 6I, when the upper surface is etched by a predetermined width to form the barrier layer 32, the first to third sacrificial layers 52, 53, and 54 are removed to complete the manufacturing process.

The first to third sacrificial layers 52, 53, and 54 may use photoresist, thick photoresist, polyimide, and the like as a deposition method. Coating method is used.

As the thick film photoresist, polymethyl methacrylate (PMMA) or polyimide, which is a kind of acrylic resin, is used.

Of course, in the present embodiment, a process of forming one unit mirror is described as an example, but the micromirrors manufactured through the above process have a micromirror group corresponding to the number of pixels on the screen.

As described above, the present invention adjusts the reflected light incident on the screen by moving the elastic shield plate of the unit mirror by the driving circuit of the substrate, thereby adjusting the brightness of the pixel. Therefore, the device can be suitably used for a device requiring a high resolution image such as adjusting the brightness of the pixel or partially blocking the incident light according to the on / off duration of the corresponding pixel. In addition, since the SRAM is not required to control the on / off of each pixel, it is possible to apply to a device displaying a high resolution image such as to reduce the manufacturing cost.

Claims (11)

A display device in which a plurality of unit fine mirrors controlled by a driving circuit of a substrate individually reflects incident light to form a predetermined image. An elastic barrier plate supported by a pair of first supports formed on the substrate and having a blocking film formed on a body protruded to the first support to block reflected incident light; A reflector which is supported by a pair of second supports positioned above the elastic barrier plate, and formed with at least one of the unit micromirrors, and having a guide groove for moving the elastic barrier plate on the upper surface to reflect incident light; And And a driving electrode positioned between the substrate and the elastic shielding plate, the driving electrode for oscillating the elastic shielding plate by inducing a predetermined voltage difference according to a driving signal from the driving circuit. The micromirror display device of claim 1, wherein the reflector is formed of a material having a high light reflectance. The micromirror display device of claim 2, wherein the reflector is made of aluminum (Al) or silver (Ag). The micromirror display device of claim 1, wherein the elastic barrier plate is bent at the same time as that of the elastic barrier plate. In the manufacturing method of the display device in which a plurality of unit mirrors reflect incident light individually to form a predetermined image, Depositing a metal on an insulating layer coated on a silicon substrate and then etching to form an electrode; Depositing a first sacrificial layer on an upper surface including the electrode and forming a first opening for forming a first support; Depositing and etching a first component layer on an upper surface on which the first opening is formed to form an elastic barrier plate; Depositing a second sacrificial layer on the upper surface on which the elastic barrier plate is formed and forming a second opening for forming a second support; Forming a reflector by depositing and etching a second component layer on an upper surface of the second opening; Depositing a third sacrificial layer on an upper surface of the reflector and forming guide grooves for the barrier layer of the elastic barrier plate to move; Forming a blocking layer by depositing a fourth component layer on an upper surface of the guide groove; And And removing the first to third sacrificial layers. The method of claim 5, wherein the electrode forming step comprises coating a metal on a substrate, and after coating a photoresist on the metal and irradiated with light through a mask and etching to separate the electrodes, characterized in that Manufacturing method of display element. The micromirror display device of claim 5, wherein the first to third sacrificial layers are any one of a photoresist, a thick photoresist, and a polyimide. Way. The method of claim 5, wherein the first to third sacrificial layers are deposited by a spin coating method. The method of claim 5, wherein the fourth component layer is made of metal or doped polysilicon. The method of claim 5, wherein the depositing of the fourth component layer is performed according to an electroplating method. The method of claim 5, wherein the first and second openings are etched by reactive ion etching (RIE) or photolithography.

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