KR100207408B1 - Fabrication method for lightpath modulation device - Google Patents

Abstract

The present invention relates to an optical path control apparatus, comprising: forming a sacrificial layer to expose a pad on an upper portion of a driving substrate having transistors embedded in a matrix and electrically connected to the transistors on a surface thereof, and then patterning the sacrificial layer; And sequentially forming a membrane, a lower electrode, a deformable portion, and an upper electrode on the exposed substrate by the sacrificial layer and the patterning of the sacrificial layer, the upper electrode, the deformable portion, the lower electrode, and the upper portion of the pad. Forming an opening for exposing the pad by removing the membrane by secondary photolithography; forming a connection portion in the opening electrically connecting the pad and the lower electrode by a lift-off process; Etch so that the sacrificial layer is exposed from the upper electrode to the membrane. And includes a step of separating the actuator, and a step of forming a protective film on the side surface of the actuator and of the upper electrode, the step of removing the sacrificial layer and the protective film. Therefore, cracks can be prevented from occurring in the deformed portion.

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

57: photosensitive film 59: connection portion

61: protective film 63: air gap

65: Actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical path control device used in a projection type image display device, and more particularly, to a method for manufacturing an optical path control device that can prevent cracks from occurring in 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 control 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 control 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 for adjusting 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 by 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 is formed so that the lower electrode is electrically connected to the pad through an opening formed in the membrane, and a deformation portion is formed thereon, wherein a void is formed in the deformation portion filling the opening. Thereby, there was a problem that cracks are generated.

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

In another aspect of the present invention, there is provided a method of manufacturing an optical path control apparatus, in which a sacrificial layer is formed such that a pad is exposed on an upper portion of a driving substrate on which a pad is embedded in a matrix and electrically connected to each of the transistors. Thereafter, patterning the sacrificial layer, sequentially forming a membrane, a lower electrode, a deformation portion, and an upper electrode on the sacrificial layer and the driving substrate exposed by the patterning of the sacrificial layer, and the upper electrode on the pad Removing the deformable portion, the lower electrode and the membrane by secondary photolithography to form an opening for exposing the pad, and a connecting portion for electrically connecting the pad and the lower electrode in the opening by a lift-off process. Forming a, from the upper electrode to the membrane And a step and a step of forming a protective film on the side surface of the actuator and of the upper electrode, and removing the sacrificial layer and the protective film to remove the raw film is etched so as to expose the actuator.

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

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, the deformable portion 51, and the upper electrode 53 are sequentially formed on the driving substrate 41 and the sacrificial layer 45. Form. 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 addition, the upper electrode 53 is formed by sputtering or vacuum depositing a metal having good electrical and reflective properties such as aluminum (Al) or silver (Ag) to a thickness of about 500 to 2000 kPa. 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, the upper electrode 53, the deformable part 51, the lower electrode 49, and the membrane 47 are patterned by an etching process. That is, the opening 55 is formed by forming the upper electrode 53 and the deformable portion 51 by the primary photolithography method and the lower electrode 49 and the membrane 47 by the secondary photolithography method. The pad 43 is exposed. 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. Then, the photoresist film 57 is formed on the entire surface of the above-described structure, and the pad 43 is exposed by exposure and development. Then, the connection portion 59 for depositing platinum (Pt) or titanium (Ti) to a thickness of about 0.1 ~ 2㎛ by sputtering or vacuum deposition method to electrically connect the pad 43 and the lower electrode 49 ). At this time, a conductive metal for forming the connecting portion 59 is also deposited on the photosensitive film 57.

Referring to FIG. 2D, the photosensitive film 57 is lifted off to be removed. At this time, the conductive metal forming the connection portion 59 on the photosensitive film 53 is also removed. 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. Then, the protective film 61 is removed by a dry etching method by oxygen plasma.

As described above, the present invention sequentially forms a membrane, a lower electrode, a deformable portion, and an upper electrode on the driving substrate and the sacrificial layer, and then forms an opening for exposing the pad by a secondary photolithography method. Forming a connection part connecting the pad and the lower electrode by increasing the width of the portion removed in the first photolithography in the second photolithography so that the deformation portion is not formed in the upper portion of the lower electrode around the opening. do.

Therefore, according to the present invention, it is possible to prevent the occurrence of cracks in the deformed portion, and as a result, to prevent the short circuit between the upper electrode and the lower electrode through the crack.

Claims (4)

Forming a sacrificial layer so that the pad is exposed on an upper portion of a driving substrate having a transistor embedded in a matrix and electrically connected to each of the transistors, and then patterning the sacrificial layer, and forming the sacrificial layer and the sacrificial layer. Sequentially forming a membrane, a lower electrode, a deformable portion, and an upper electrode on the driving substrate exposed by patterning; and removing the upper electrode, the deformable portion, the lower electrode, and the membrane on the pad by secondary photolithography. Forming an opening for exposing the pad, forming a connecting portion electrically connecting the pad and the lower electrode in the opening by a lift-off process, and exposing the sacrificial film from the upper electrode to the membrane. Etching to separate the actuator so that the upper portion A step of forming a protective film on the side surface of the actuator and the electrode, method for producing the optical path control device comprising a step of removing the sacrificial layer and the protective film. The method of claim 1, wherein the opening is formed by first photolithography of the upper electrode and the deformable part and second photolithography of the lower electrode and the membrane. The method of claim 1, wherein the connection part is formed of platinum (Pt) or titanium (Ti). The method of claim 3, wherein the connecting portion is formed by sputtering or vacuum deposition to a thickness of 500 to 2000 kPa.