KR100197379B1 - Method for fabricating an optical projection system - Google Patents

Abstract

The present invention relates to a method of manufacturing an optical path control device, comprising: forming a sacrificial layer such that a pad is exposed on an upper portion of a driving substrate having a pad embedded in a matrix and electrically connected to each of the transistors on a surface thereof; Forming a membrane on the exposed pad and the sacrificial layer, forming an opening to be exposed by the pad in a predetermined portion of the membrane, and forming a plug electrically connected to the pad in the opening; And forming a first lower electrode on the membrane to be electrically connected to the plug, oxidizing a predetermined portion of the first lower electrode to form an electrode isolation region; Forming a second lower electrode on the electrode isolation region, and forming a second lower electrode on the electrode isolation region Removing the lower electrode, sequentially forming the deformable portion and the upper electrode on the second lower electrode, etching the exposed sacrificial film from the upper electrode to the membrane, and separating the actuator; Forming a protective film on the surface of the upper electrode and on the side of the actuator; and removing the sacrificial film and the protective film. Thus, the electrode isolation region can be defined while preventing the membrane from being damaged.

Description

Manufacturing method of optical path control device

1 is a plan view showing a general light path control device.

FIG. 2 is a cross-sectional view of the optical path adjusting device 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 prior art.

4 (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

41: drive substrate 43: pad

45: sacrificial film 47: membrane

48: opening 49: plug

50: first lower electrode 51: second lower electrode

52: electrode separation region 53: deformation portion

55 upper electrode 57 protective film

59: air gap 60: actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical path adjusting device used in a projection image display device, and particularly to prevent the membrane from being damaged when defining an electrode separation region for separating the lower electrode for electrically separating adjacent actuators. It relates to a method for manufacturing an optical path control device that can be.

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 includes a CTR (Cathode Ray Tube), etc. The CRT image display device has good image quality but has a problem in that a large screen is increased and weight and thickness are increased, thereby limiting a large screen and cost. .

Projection type image display apparatuses include liquid crystal display apparatuses, which can be thinned to 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 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 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.

FIG. 1 is a plan view of the above-described optical path adjusting device, and FIG. 2 is a cross-sectional view taken along the line a-a of FIG.

The optical path adjusting device includes a driving substrate 11 and an actuator 30. The driving substrate 11 is made of an insulating material such as glass or alumina (Al ₂ O ₃ ), or a semiconductor such as silicon, and includes M × N transistors (not shown) in a matrix form. In addition, a pad 13 electrically connected to a transistor is formed on the surface of the driving substrate 11, and the pad 13 is formed to be connected to each transistor.

The actuator 30 is composed of a membrane 17, a plug 19, a lower electrode 21, a deformable portion 23, and an upper electrode 25, and is separated from neighboring actuators.

The membrane 17 is formed to be in contact with a predetermined portion of the upper portion of the driving substrate 11 to a thickness of about 0.1 ~ 2㎛ as an insulating material. Membrane 17 has two legs (leg) on one side around the center of the actuator (30), the protrusion is formed on the other side, the leg is on the other side of the actuator 30 and one end is matched together ' It forms the shape of yo (,), and the protrusion forms the form of 'iron (凸)' on one side. In addition, the membrane 17 is complementary by the protrusion of the actuator adjacent to one side of the recess between the two legs and the protrusion between the recesses of the legs of the actuator adjacent to the other side.

The plug 19 is filled with metal such as tungsten (W) or titanium (Ti) in the opening 18 formed in a predetermined portion of the membrane 17 stacked on the pad 13 of the driving substrate 11. It is formed to be electrically connected with (13).

The lower electrode 21 is formed on the membrane 17 to be electrically connected to the plug 19 by platinum (Pt) or platinum / titanium (Pt / Ti). The lower electrode 21 is separated from the adjacent lower electrode by the electrode isolation region 22 to be electrically spaced from each other, thereby separating the actuator 30 from the adjacent actuator.

The deformable part 23 is stacked on the lower electrode 21. The deformable portion 23 is formed of a piezoelectric ceramic or a total distortion ceramic.

The upper electrode 25 is formed of a metal having good electrical and reflective characteristics such as aluminum (Al) or silver (Ag) on the upper surface of the deformable portion 23 and is commonly connected to the upper electrodes of adjacent actuators. In the above, the upper electrode 25 causes the deformation portion 23 to be deformed due to the voltage difference from the lower electrode 21.

3 (a) to (d) are manufacturing process diagrams of an optical path control apparatus according to the prior art.

Referring to FIG. 3 (a), the entire surface of the upper portion of the driving substrate 11 having a pad (13) having transistors (not shown) embedded in the surface thereof and 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. 3B, a membrane 17 is formed on the driving substrate 11 and the sacrificial layer 15. Then, a predetermined portion of the membrane 17 is removed to expose the pad 13 to form the opening 18, and then filled with a conductive metal in the opening 18 to be electrically connected to the pad 13. A plug 19 is formed. Subsequently, a conductive metal is deposited on the upper surface of the membrane 170 to form a lower electrode 21 electrically connected to the plug 19. The lower electrode 21 is then subjected to the conventional photolithography method. A portion of the membrane 17 is removed to define an electrode isolation region 22 which is electrically separated from the lower electrodes of adjacent actuators.

Referring to FIG. 3 (c), 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. 3 (d), the sacrificial layer 15 is removed to define the air gap 29. After removing the sacrificial layer 15, 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 terminated at the top of the sacrificial film when defining the electrode separation region for separating the lower electrode by the step formed by the sacrificial film to electrically separate the actuator from the adjacent actuator. There was a problem in that the lower electrode overetched (damaged) the membrane is damaged.

Accordingly, an object of the present invention is to provide a method of manufacturing an optical path control apparatus that can prevent the membrane from being damaged when defining the electrode separation region for separating the lower electrode.

According to an 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 having a pad embedded in a matrix and electrically connected to each of the transistors on its surface. Forming a membrane on top of the exposed pad and the sacrificial film, forming an opening through which the pad is exposed in a predetermined portion of the membrane, and a plug electrically connected to the pad in the opening. Forming a first lower electrode to be electrically connected to the plug at an upper portion of the membrane, oxidizing a predetermined portion of the first lower electrode to form an electrode isolation region, and A first lower electrode and a second lower electrode are formed on the electrode separation region, and the electrode portion Removing the second lower electrode over the region, sequentially forming the deformable portion and the upper electrode on the second lower electrode, and etching the exposed sacrificial layer from the upper electrode to the membrane to expose the actuator. And a step of forming a protective film on the surface of the upper electrode and the side of the actuator, and a step of removing the sacrificial film and the protective film.

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

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

Referring to FIG. 4 (a), the PSG is formed on the entire surface of the driving substrate 41 having the pads 43 embedded therein in a matrix form and having pads 43 electrically connected to the transistors. A sacrificial film 45 is formed by depositing (Phospho-Silicate Glass) or the like to a thickness of about 1 to 2 μm. 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. 4 (b), 0.1 to 2 μm of silicide such as silicon nitride or silicon carbide is sputtered on the driving substrate 41 and the sacrificial layer 45 by a method such as sputtering or chemical vapor deposition. Deposition to thickness forms membrane 47. Then, a predetermined portion of the membrane 47 is removed to form the opening 48 so that the pad 43 is exposed, and then platinum (Pt) or platinum / titanium (Pt / Ti) inside the opening 48. The plug 49 may be electrically connected to the pad 43 by filling a conductive metal such as). Subsequently, the first lower electrode 50 is formed by depositing a conductive metal such as tantalum (Ta) or the like on the entire surface of the above structure to a thickness of 500 to 2000 kPa by a method such as sputtering or vacuum deposition. In this case, the first lower electrode 50 is electrically connected to the plug 49. Then, a photoresist film (not shown) is formed on the first lower electrode 50 as a mask, and oxygen (O ₂ ) is ion-implanted on the exposed portion of the first lower electrode 50 and heat-treated to oxidize it. Define an electrode isolation region 52 that electrically separates the lower electrodes of adjacent actuators. Subsequently, platinum (Pt) or platinum / titanium (Pt / Ti) or the like is deposited on the upper portion of the first lower electrode 50 and the electrode isolation region 52 by a method such as sputtering or vacuum deposition. Deposition to form a second lower electrode 51. Then, the second lower electrode 51 is removed by a conventional photolithography method to expose the electrode isolation region 52. At this time, since the etching selectivity of the second lower electrode 51 and the electrode isolation region 52 is different, it is used as an etching end point, whereby the electrode isolation region 50 can etch the second lower electrode 51. The membrane 47 protects from damage by preventing over-etching.

Referring to FIG. 4 (c), the deformation part 53 and the upper electrode 55 are sequentially formed on the second lower electrode 51 and the electrode isolation region 50. The deformable portion 53 may include piezoelectric ceramics 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 ), etc., are formed to a thickness of about 0.1 to 2 μm. At this time, since the deformation part 53 is thinly formed, it is polarized by the image signal at the time of driving, without a separate polarization. The upper electrode 55 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 0.1 to 2 μm. In addition, the upper electrode 55, the deformable portion 53, the lower electrode 51 and the membrane 47 are sequentially etched to define the actuator 60. Subsequently, a photoresist is applied to the surface of the upper electrode 55 and the side surfaces formed by the separation of the actuators 60, and is exposed and developed to form a protective film 57.

Referring to FIG. 4 (d), the sacrificial film 45 is removed with an etching solution such as hydrofluoric acid to define the air gap 59. The sacrificial layer 45 is removed by washing with deionized water, and the remaining etching solution is removed, followed by drying. In addition, the protective layer 57 is removed by a dry etching method using an oxygen plasma.

As described above, in the present invention, a first lower electrode is formed on the membrane, and a predetermined portion of the first lower electrode is oxidized by an oxygen ion implantation heat treatment to form an electrode separation region. A second lower electrode is formed on the separation region, and the second lower electrode on the electrode isolation region is etched to electrically separate the neighboring actuator.

Therefore, the present invention has the advantage of defining the electrode separation region while preventing the membrane from being damaged.

Claims (3)

Forming a sacrificial layer so that the pad is exposed 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 forming a membrane on the exposed pad and the sacrificial layer. Forming an opening through which the pad is exposed in a predetermined portion of the membrane, forming a plug electrically connected to the pad in the opening, and electrically connecting the plug to an upper portion of the membrane. Forming a first lower electrode to form an electrode, oxidizing a predetermined portion of the first lower electrode to form an electrode isolation region, and forming a second lower electrode on the first lower electrode and the electrode isolation region Removing the second lower electrode over the electrode separation region; Forming a deformable portion and an upper electrode in order, etching the sacrificial layer from the upper electrode to the membrane to expose the actuator, and forming a protective film on the surface of the upper electrode and the side of the actuator. And removing the sacrificial film and the protective film. The apparatus of claim 1, wherein the first lower electrode is formed of tantalum (Ta), and the second lower electrode is formed of one of platinum (Pt) or platinum / titanium (Pt / Ti). Manufacturing method. The method of claim 2, wherein the first and second lower electrodes are deposited in a thickness range of 500 to 2000 micrometers, respectively.