KR100209402B1 - Manufacturing method of optical path control device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical path control device, wherein a transistor is embedded in a matrix form and a sacrificial film is formed on an upper surface of a driving substrate on which two connection terminals are electrically connected to each of the transistors. Removing a portion of the sacrificial layer so that the exposed portion is exposed, forming a support portion in the exposed portion by removing the sacrificial layer, forming a membrane on the sacrificial layer and the support portion, and part of the membrane and the support portion. Forming an opening through which the connection terminal is exposed, forming a plug in the opening, forming a signal electrode electrically connected to the plug on an upper surface of the membrane, and an upper portion of the signal electrode. Sequentially forming a deformable portion and a reflective film on the substrate, and patterning the reflective film to Separating the reflection film formed in the upper portion of the bias electrode, and a step of removing the sacrificial layer. Therefore, since the bias electrode is formed only on a portion including a portion overlapping with the support of the upper portion of the deformable portion, the reflective film formed on the remaining portion does not cause warpage due to stress of the deformable portion and the membrane to maintain flatness, thereby improving light efficiency. As a result, it is suppressed from the occurrence of cracks and can prolong the service life.

Description

Manufacturing method of optical path control device

1 is a plan view of an optical path control device manufactured according to the present invention.

2 is a cross-sectional view taken along the line a-a of FIG.

3 (a) to (d) is a manufacturing process diagram of the optical path control apparatus according to the present invention.

* Explanation of symbols for main parts of the drawings

11: drive board 13: connection terminal

15: sacrificial film 17: support

19: membrane 21: plug

23: signal electrode 25: deformation part

27: reflective film 29: bias electrode

30: actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical path control device for use in a projection image display of the present invention, and more particularly, to a method for manufacturing an optical path control device that can prevent cracks in a reflective film to improve light efficiency and lifespan.

Direct image display device includes CRT (Cathode Ray Tube), which has good image quality but it has problems such as increase of weight and thickness as the screen is enlarged and price is expensive. There is.

Projection type image display apparatuses include a large crystal display (hereinafter referred to as an LCD), and such a large-screen LCD can be thinned to reduce weight. However, such an LCD has a high light loss due to a polarizing plate, and a thin film transistor for driving the LCD is formed for each pixel, so that there is a limit in increasing the aperture ratio (light transmission area).

In order to improve the disadvantages of such LCD, a projection type image display apparatus using Actuated Mirror Arrays (hereinafter referred to as AMA) has been developed.

Projection type image display apparatuses are classified into using one-dimensional AMA and two-dimensional AMA. The one-dimensional AMA has mirror surfaces arranged in an M × 1 array, and the two-dimensional AMA has mirror surfaces arranged in an M × N array. Therefore, a projection image display device using a one-dimensional AMA pre-scans M × 1 beams using a scanning mirror, and a projection image display device using a two-dimensional AMA projects M × N beams to produce an array of M × N pixels. Branches represent images.

The conventional method for manufacturing an optical path control device using a thin-film actuator is disclosed in Korean Patent No. 93-31717, filed with the Korean Intellectual Property Office on December 30, 1993 (name of the invention: of the optical path control device of the projection image display device). Manufacturing method). The method selectively forms two support portions per pixel on a predetermined portion of the drive substrate, and forms a membrane in the region of each pixel so that a predetermined portion on one side is placed over the support portions. Thereafter, a signal electrode that is partially extended to the other side is selectively formed, including a portion overlapping with the supporting portions of the upper portion of the membrane, and then a reflective film, which is also used as a deformation portion and a bias electrode, is sequentially formed on the front surface. Then, the membrane is etched from the reflective film to the membrane and separated by each pixel unit, and at the same time, the membrane is transferred from one side to the signal electrode extending in the other direction so that the membrane between the supporting parts can move.

In the optical path control apparatus manufactured by the above-described conventional method, when a bias voltage is applied to an image signal and a reflective film to a signal electrode, the deformation part is generated and bent only at a portion where the signal electrode and the reflective film overlap. The portion where the signal electrode is not formed is not deformed, but the plate is inclined flat by the curved portion, resulting in high light efficiency.

However, in the above-described conventional optical path control device, since the deformation portion and the membrane contact each other without interposing the signal electrode, stress is generated due to a difference in the coefficient of thermal expansion, causing cracks in the reflective film. These cracks not only reduce reflection efficiency but also shorten their lifetime.

Accordingly, another object of the present invention is to provide a method of manufacturing an elder adjusting device which can prevent cracks from being generated in the reflective film, thereby improving reflection efficiency and lifetime.

According to another aspect of the present invention, there is provided a method of manufacturing an optical path control apparatus, wherein a sacrificial layer is formed on a driving substrate on which a transistor is embedded in a matrix form and two connection terminals are electrically connected to each of the transistors on a surface thereof. Thereafter, removing a portion of the sacrificial film so that the connection terminal is exposed, forming a support on the exposed portion by removing the sacrificial film, forming a membrane on the sacrificial film and the support, Removing a portion of the membrane and the support to form an opening through which the connection terminal is exposed, and forming a plug in the opening; and forming a signal electrode electrically connected to the plug on the upper surface of the membrane; And sequentially forming a deformable portion and a reflective film on the signal electrode, and the reflection Patterning a film to separate the reflective film formed on the support part with a bias electrode, and removing the sacrificial film.

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

1 is a plan view of an optical path control apparatus manufactured according to the present invention, and FIG. 2 is a cross-sectional view taken along line 3-3 of FIG.

The optical path adjusting device manufactured according to the present invention includes a driving substrate 11 and an actuator 30. The driving substrate 11 is made of an insulating material such as glass or alumina (A1 ₂ O ₃ ), or a semiconductor such as silicon, and M x N transistors (not shown) are embedded in a matrix form. In addition, a connection terminal 13 electrically connected to a transistor is formed on the surface of the driving substrate 11, and two connection terminals 13 are connected to each transistor.

The actuator 30 is composed of a support 17, a membrane 19, a plug 21, a deformable portion 25, a signal electrode 23, and a reflective film 29 to be separated from an adjacent actuator (not shown). It is.

The support part 17 is formed to separately cover two connection terminals 13 electrically connected to the same transistor on the top of the driving substrate 11, and the membrane 19 is formed on the lower surface of the support part 11. Only a predetermined portion of the contact portion and the remaining portion including between the support 17 is formed to be exposed to the space. In addition, the membrane 19 is cut by a predetermined length along the x-axis so as to coincide with the opposing surface of the support 17, and the signal electrode 23 and the deformable portion 25 are stacked on the membrane 19. The support 17 and the membrane 19 are formed by a method such as sputtering or chemical vapor deposition (hereinafter referred to as CVD) of silicon nitride, silicon carbide, silicon oxide, platinum, or the like. The deformable portion 25 may be a piezoelectric ceramic such as BaTiO ₃ , PZT (Pb (Zr, Ti) O ₃ ) or PLZT (Pb, La) (Zr, Ti) O ₃ ), or PMN (Pb (Mg). , Nb) O ₃ ) and the like, and are formed by applying a total distortion ceramic in a thickness of about 0.7 to 2 μm. The signal electrode 23 is formed by applying platinum (Pt), platinum / titanium (Pt / Ti), or the like to a thickness of about 500 to 2000 m 3.

The plug 21 is formed of tungsten (W) or titanium by electrically connecting the connection terminal 13 and the signal electrode 23 through the support 17 and the membrane 19.

The reflective film 22 is formed by applying a metal having good reflective properties such as aluminum or silver to the upper surface of the deformable portion 25 to a thickness of about 500 to 2000 Pa by sputtering or vacuum deposition. In addition, the reflective film 27 is cut along the y-axis so as to coincide with the cut end of the membrane 19 to form a '凸' shape. In the above, since aluminum or silver forming the reflective film 27 is a material having excellent electrical characteristics, the remaining portion except for the '凸' portion becomes the bias electrode 29. Therefore, the reflecting film 27 is in an electrically floating state.

In the optical path control device having the above-described structure, the same image signal is applied to the signal electrode 23 through two connection terminals 13 and a plug 21 electrically connected to the same transistor of the driving substrate 11, and the bias electrode ( 29, a bias voltage is applied. Therefore, an electric field is generated in the deformable portion 25 interposed between the signal electrode 23 and the bias electrode 29, thereby deforming the deformable portion 25 in the direction perpendicular to the electric field. At this time, the deformable portion 25 is bent and inclined by the strain difference with the membrane 19.

However, since no electric field is generated in the deformable portion 25 between the signal electrode 23 and the reflective film 27, no strain difference occurs between the membrane 19 and the warp does not occur. Therefore, the deformable portion 25 between the signal electrode 23 and the reflective film 27 is inclined flat by the bent and deformed deformable portion 25 between the signal electrode 23 and the bias electrode 29.

Therefore, the reflecting film 29 is maintained flat without bending, thereby improving the light efficiency.

3 (a) to (d) is a manufacturing process diagram of the optical path control apparatus according to the present invention.

Referring to FIG. 3A, a sacrificial layer is formed on a surface of a driving substrate 11 having a transistor (not shown) embedded in a matrix form and having connection terminals 13 electrically connected to each of the transistors two on top. (15) is formed. In the above, the sacrificial film 15 is formed to a thickness of about 1 to 2 μm with a metal material such as Mo, Cu, Fe, Ni or Al, PSG (Phoshop-Silicate Glass) or polycrystalline silicon, and the like. In the case of forming by PSG, by spin coating or by chemical vapor deposition (CVD), and by polycrystalline silicon, by chemical vapor deposition (Chemical Vapor Deposition). Then, the sacrificial film 15 of the portion where the connection terminal 13 is formed is removed by a conventional photolithography method to expose the connection terminal 13 and the driving substrate 11 around it. Then, silicon nitride (Si ₃ N ₄ ) silicon oxide (SiO ₂ ) silicon carbide or the like is deposited on the entire surface of the structure described above by a thickness of about 1 to 2 μm by sputtering or CVD, and then photolithography. The support 17 is formed by removing the deposit on the sacrificial layer 15 by the method. The silicide is applied by the CVD method and the support 17 is formed to surround the connection terminal 13 in the exposed portion of the drive substrate 11. In addition, if the silicide is deposited by sputtering, the support 17 may be lifted off without removing the photoresist layer (not shown) used as a mask when etching the sacrificial layer 15. It can also be formed by the method.

Referring to FIG. 3B, a membrane 19 is formed on the support 17 and the sacrificial layer 15. The membrane 19 is formed by depositing the same material as the support 17 in a thickness of about 0.7 to 2 μm by sputtering or CVD. Next, the membrane 19 and the support part 17 of the upper portion of the connection terminal 13 are removed to form holes. The inside of the hole is filled with a conductive metal such as tungsten (W) or titanium (Ti) to form a plug 21 that is electrically connected to the connection terminal 13.

Subsequently, platinum (Pt) or platinum / titanium (Pt / Ti) or the like is applied to the surface of the membrane 19 to a thickness of about 500 to 2000 kPa by a method such as vacuum deposition or sputtering to form a signal electrode 23. . The signal electrode 23 is formed to be electrically connected to the plugs 21 to electrically connect the connection terminals 13 and the signal electrode 23 by the plugs 21.

Referring to FIG. 3C, the deformable portion 25 and the reflective film 27 are sequentially applied to the surface of the signal electrode 23. In the above, the deformable portion 25 is a piezoceramic such as BaTiO ₃ , PZT (Pb (Zr, Ti) O ₃ ) or PLZT ((Pb, La) (Zr, Ti) O ₃ ), or PMN (Pb ( It is formed by applying a total distortion ceramic such as Mg, Nb) O ₃ ) to a thickness of about 0.7 to 2 μm by the So1-Gel method, sputtering, or CVD method. Since the deformable portion 25 is thinly formed, the deformable portion 25 is polarized by an image signal applied during driving without a separate polarization. In addition, the reflective film 27 is formed with a thickness of about 500 to 1000 Pa by a method such as sputtering or vacuum evaporation of a material having good reflection characteristics and electrical characteristics such as silver (Ag) or aluminum. Then, the reflective film 27 is patterned to form a bias electrode 29. At this time, the bias electrode 29 is equal to the width of the support 17 on the z-axis of FIG. 1.

Referring to FIG. 3 (d), a predetermined portion is cut by a laser to expose the sacrificial film 15 from the bias electrode 29 to the deformable portion 19 so that the edges of the support 17 are aligned. The actuators 30 are separated by removal by photolithography.

At this time, the length of the bias electrode 29 is cut from the reflecting film 27 to the membrane 19 so as to correspond to the opposing surfaces of the two support portions 17 of the same actuator 30, respectively. Then, the sacrificial film 15 is removed by a wet method.

Therefore, in the present invention, since the bias electrode is formed only in a portion including a portion overlapping with the support of the upper portion of the deformable portion, the reflective film formed on the remaining portion is kept flat without bending due to stress of the deformable portion and the membrane, and the lower electrode Since the deformation portion is deposited on the front surface, it is possible to suppress the occurrence of cracks, thereby extending the life and improving the light efficiency.

Claims (4)

Forming a sacrificial layer on a driving substrate in which a transistor is embedded in a matrix and having two connection terminals electrically connected to each of the transistors on a surface thereof, and then removing a portion of the sacrificial layer to expose the connection terminals; Forming a support on the exposed portion by removing the sacrificial film, forming a membrane on the sacrificial film and the support, and forming an opening through which the proximal connection terminal is exposed by removing the membrane and the support. Forming a plug in the opening, forming a signal electrode electrically connected to the plug on an upper surface of the membrane, and sequentially forming a deformable portion and a reflective film on the signal electrode; The reflective film is patterned so that the reflective film formed on the support part is a bias electrode. Li step of the method for producing the optical path control device comprising a step of removing the sacrificial layer. The method of claim 1, wherein the reflective film and the bias electrode are formed of silver or aluminum. The method of claim 2, wherein the reflective film and the bias electrode are formed by vacuum deposition or sputtering. The method of manufacturing an optical path control device according to claim 3, wherein the reflective film and the bias electrode are formed to a thickness of about 500 to 1000 mW.