KR100207409B1 - Fabrication method for lightpath modulation device - Google Patents

Abstract

The present invention relates to a method for manufacturing an optical path control device, the method comprising the step of forming a sacrificial film to expose the pad on the top of the driving substrate having a pad electrically connected to a transistor embedded in a matrix form on the surface; Sequentially forming a membrane, a lower electrode, and a deformable portion on top of the driven substrate and the sacrificial layer; and removing the deformable portion, the lower electrode, and the membrane on the pad by secondary photolithography to expose the pad. A process of forming an opening, and depositing a conductive metal on the entire surface of the structure thus formed to contact the pad and removing the deposit on the deformed portion to form a connection portion electrically connecting the pad and the lower electrode in the opening. And the upper part of the deformable part so as not to be electrically connected to the connecting part. Forming a secondary electrode, etching the sacrificial layer from the upper electrode to the membrane to expose the actuator, forming a protective layer on the surface of the upper electrode and the side of the actuator, and And the process of removing the said protective film, it can prevent that a crack generate | occur | produces in a deformation | transformation part.

Description

Manufacturing method of optical path control device

1 (a) to (d) is a manufacturing process diagram of the optical path control apparatus according to the prior art.

2 (a) to (e) 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

41: drive substrate 43: pad

45: sacrificial film 47: membrane

49: lower electrode 51: deformation part

53: upper electrode 55: opening

59 connection part 61: protective film

63: air gap 65: actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing method of an optical path adjusting apparatus used for a projection type image display apparatus, and more particularly, to a manufacturing method of an optical path adjusting apparatus capable of preventing cracks from being generated due to a step when forming a deformable portion.

In general, a display device is classified into a direct view type image display device and a projection type image display device according to a display method.

The direct view type image display device has a CRT (Cathode Ray Tube), etc. The CRT image display device has good image quality, but the weight and thickness increase as the screen is enlarged, so that there is a limit in implementing a large screen and the price is expensive. have.

Projection type image display apparatuses include liquid crystal display apparatuses, which can be thinned and can reduce weight. However, the liquid crystal display device has a problem in that light loss due to the polarizing plate is large and a thin film transistor, which is a driving element, must be formed for each pixel, thereby limiting an increase in the aperture ratio. Thus, the light efficiency is very low and the viewing angle is small.

Accordingly, the United States Aura has developed a projection type image display device that can display an image by adjusting the optical path by an actuator mirror array (hereinafter referred to as AMA), which is a new optical path adjusting device. The AMA separates the white light emitted from the light source into red, green and blue light, and then changes the light path by driving an optical path adjusting device made of actuators. Since the actuators are individually driven by the image signal to incline the mirrors mounted on the upper part, the actuators change the light path of each color light and adjust the amount of color light by a device that adjusts the amount of light such as a knife edge to project onto the screen. The actuators are formed of piezoelectric ceramics or electrostrictive ceramics, and are inclined by an electric field generated by a voltage applied to an image signal to tilt the mounted mirrors.

The actuator is classified into a bulk type and a thin film type according to the shape.

The bulk type mounts a ceramic wafer thinly cut in a direction perpendicular to the metal electrodes on a driving substrate after processing a multilayer ceramic having metal electrodes formed therein on a driving substrate, and processes the same by sawing, and mounts mirrors on the respective actuators. The bulk type has a long process time because the actuators must be separated by sawing, and there is a problem that the response speed of the actuators is slow.

Accordingly, in order to solve the problem of the bulk type, a thin film type actuator capable of manufacturing using a semiconductor process and having a fast response speed was developed by Daewoo Electronics of Korea.

1 (a) to (d) is a manufacturing process diagram of the optical path control apparatus according to the prior art.

Referring to FIG. 1A, transistors (not shown) are embedded in a matrix, and the entire surface of the upper portion of the driving substrate 11 having pads 13 electrically connected to the transistors. A sacrificial film 15 is formed on the substrate. The sacrificial film 15 is then removed by a conventional photolithography method to expose the pad 13.

Referring to FIG. 1B, a membrane 17 is formed on the driving substrate 11 and the sacrificial layer 15. A portion of the membrane 17 is removed to expose the pad 13 to form the opening 19, and a conductive metal is deposited on the upper surface of the membrane 17 to form a pad (through the opening 19). A lower electrode 21 electrically connected to the 13 is formed.

Referring to FIG. 1C, the deformation part 23 and the upper electrode 25 are sequentially formed on the lower electrode 21. The upper electrode 25, the deformable portion 23, the lower electrode 21, and the membrane 17 are sequentially etched to define the actuator 30. Subsequently, the protective film 27 is formed on the surface of the upper electrode 25 and the side surfaces formed by the separation of the actuators 30.

Referring to FIG. 1D, the sacrificial layer 15 is removed to define the air gap 29. The sacrificial layer 15 is removed and the remaining etching solution is washed with deionized water and the protective layer 27 is removed.

However, the conventional method for manufacturing the optical path control apparatus described above forms the lower electrode so as to be electrically connected to the pad through an opening formed in the membrane and forms a deformation portion thereon, wherein the opening forms a void in the deformation portion. Thereby, there was a problem that cracks are generated.

Accordingly, it is an object of the present invention to provide a method of manufacturing an optical path control apparatus that can prevent cracks from occurring in the deformable portion.

According to an aspect of the present invention, there is provided a method of manufacturing an optical path control apparatus, including forming a sacrificial layer to expose a pad on an upper surface of a driving substrate having a pad electrically connected to a transistor embedded in a matrix. Sequentially forming a membrane, a lower electrode, and a deformable portion on the exposed driving substrate and the sacrificial layer, and removing the deformable portion, the lower electrode, and the membrane on the pad by secondary photolithography to expose the pad. And a connection portion for electrically connecting the pad and the lower electrode in the opening by depositing a conductive metal on the entire surface of the structure formed in such a manner so as to contact the pad and removing the deposit on the deformation portion. Forming and not electrically connected to the connecting portion at the upper portion of the deformable portion. Forming a lock upper electrode, separating the actuator by etching the sacrificial layer from the upper electrode to the membrane, and forming a protective film on the surface of the upper electrode and the side of the actuator; And removing the film and the protective film.

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

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

Referring to FIG. 2 (a), a PSG is formed on the entire surface of a driving substrate 41 having a pad 43 having a transistor 43 (not shown) embedded in the surface thereof and electrically connected to the transistors. (Phospho-Silicate Glass) or the like is deposited to a thickness of about 0.1 ~ 2㎛ to form a sacrificial film 45. In the above, the driving substrate 41 is made of an insulating material such as glass or alumina, or a semiconductor substrate such as silicon. The sacrificial film 45 is removed by a conventional photolithography method to expose the pad 43.

Referring to FIG. 2B, the membrane 47, the lower electrode 49, and the deformation part 51 are sequentially formed on the driving substrate 41 and the sacrificial layer 45. In the above, the membrane 47 is formed by depositing a silicide such as silicon nitride or silicon carbide to a thickness of about 0.1 to 2 μm by a method such as sputtering or chemical vapor deposition. The lower electrode 49 is formed by depositing platinum (Pt) or platinum / titanium (Pt / Ti) to a thickness of about 0.1 to 2 μm by a method such as sputtering or vacuum deposition. The deformation part 51 is 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, A total distortion ceramic such as Nb) O ₃ ) is formed to a thickness of about 0.1 to 2 μm by a sol-gel method or sputtering. In the above, since the deformation part 51 is formed thin, it is polarized by the image signal at the time of driving, without performing additional polarization.

Referring to FIG. 2C, an opening 55 is formed in the deformable portion 51 by the primary photolithography method and the lower electrode 49 and the membrane 47 by the secondary photolithography method. To expose the pad 43. In the above, the width of the portion to be removed is increased in the second photolithography than in the first photolithography. Therefore, the lower electrode 49 around the opening 55 is exposed without forming the deformable portion 51. In this case, the lower electrode 49 and the membrane 47 may be formed separately. Then, platinum (Pt) or titanium (Ti) or the like is deposited on the entire surface of the above structure to a thickness of about 0.1 to 2 μm by a method such as sputtering or vacuum deposition, and the deformation portion ( 51) the deposition portion formed on the upper portion is removed to form a connecting portion 59 that electrically connects the pad 43 and the lower electrode 49.

Referring to FIG. 2 (d), sputtering or vacuum of a metal having good electrical and reflective properties, such as aluminum (Al) or silver (Ag), on the upper portion of the deformable portion 51 to a thickness of about 0.1 to 2 μm. The upper electrode 53 is formed by vapor deposition. At this time, the upper electrode 53 is not electrically connected to the lower electrode 49 and the connecting portion 59. In addition, the upper electrode 53, the deformable portion 51, the lower electrode 49, and the membrane 47 are sequentially etched to define the actuator 65. Subsequently, a photoresist is applied to the surface of the upper electrode 53 and the side surfaces formed by the separation of the actuators 65, and the photoresist is exposed and developed to form the protective film 61.

Referring to FIG. 2E, the sacrificial layer 45 is removed with an etching solution such as hydrofluoric acid to define the air gap 63. The sacrificial layer 45 is removed by washing with deionized water, and the remaining etching solution is removed, followed by drying. The protective layer 61 is removed by a dry etching method using an oxygen plasma.

As described above, the present invention sequentially forms a membrane, a lower electrode, and a deformable portion on the driving substrate and the sacrificial layer, and then forms an opening for exposing the pad by a secondary photolithography method. Except for the connection part connecting the pad and the lower electrode, the width of the portion removed in the first photolithography is increased, the conductive metal is deposited on the entire surface, and the pad and the lower electrode are connected. Remove the rest.

Alternatively, the via hole may be formed by performing an etching process to reduce the cross-sectional size from the top to the bottom of the via hole while sequentially patterning the upper electrode to the lower layer after depositing the upper electrode.

Therefore, the present invention can prevent cracks from occurring in the deformed portion.

Claims (4)

Forming a sacrificial layer on the surface of the driving substrate having a pad electrically connected to a transistor embedded in a matrix form, and then forming a membrane, a lower electrode, and a deformation part on the exposed driving substrate and the sacrificial layer. Forming the opening by exposing the pad by removing the deformed portion, the lower electrode, and the membrane on the pad by secondary photolithography; and forming the opening on the entire surface of the formed structure. Depositing a conductive metal so as to be in contact with the contact portion and removing the deposit on the upper portion of the deformable portion to form a connecting portion for electrically connecting the pad and the lower electrode in the opening; Forming an upper electrode such that the upper electrode is prevented, and the membrane from the upper electrode Manufacturing an optical path control device including etching the exposed sacrificial layer to form an actuator, forming a protective layer on the surface of the upper electrode and the side of the actuator, and removing the sacrificial layer and the protective layer. Way. The optical path control apparatus of claim 1, wherein when the opening is formed, the deformable part, the lower electrode, and the membrane are patterned, respectively, or the deformed part is subjected to primary photolithography and the lower electrode and the membrane are formed by secondary photolithography. Manufacturing method. The method of claim 1, wherein the connection part is formed of platinum (Pt) or titanium (Ti). 4. The method of claim 3, wherein the connecting portion is formed by sputtering or vacuum deposition to a thickness of 500 to 2000 kPa.