KR0159393B1 - Method for fabricating optical projection system - 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 protective film is formed on surfaces of an upper electrode and side surfaces generated when separating actuators, and a protective film formed on actuators adjacent to a predetermined portion of an exposed driving substrate. The bridge is formed long to be mechanically connected to remove the sacrificial film with an etching solution, and then prevent the flow of the actuators when cleaning and drying. Therefore, it is possible to prevent the sticking phenomenon caused by the surface tension of the cleaning solution during cleaning and drying.

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

* Explanation of symbols for main parts of the drawings

41: drive substrate 43: pad

45: sacrificial film 47: membrane

49: opening 51: plug

53: lower electrode 55: deformation part

57: upper electrode 59: protective film

61: bridge 63: air gap

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for manufacturing an optical path control device used in a projection image display device, and more particularly, to a method for manufacturing an optical path control device capable of removing a sacrificial film and preventing sticking during cleaning and drying.

An image display apparatus is classified into a direct view type image display apparatus and a projection type image display apparatus according to a display method.

The direct view image display device includes a CRT (Cathode Ray Tube). Such a CRT image display device has good image quality but has a problem such as an increase in weight and thickness as the screen is enlarged, and a price is expensive. There is.

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

Accordingly, a projection image display device using Actuated Mirror Arrays (hereinafter referred to as AMA) has been developed by Aura, USA. A projection image display device using AMA separates white light emitted from a light source into red, green, and blue light, and then changes the light path by driving an optical path adjusting device made of actuators. That is, the actuators are mounted on the actuators, and the actuators are individually driven to reflect the inclined mirrors, thereby changing the light path, thereby controlling the amount of light to project onto the screen. Therefore, an image appears on the screen. In the above, the actuator tilts the mirror by using an electric field generated and deformed by a voltage to which a deformable part made of piezoelectric or electrostrictive ceramic is applied. AMA is classified into one-dimensional AMA and two-dimensional AMA according to the driving method. The one-dimensional AMA has mirrors arranged in an M × 1 array, and the two-dimensional AMA has mirrors arranged in an M × N array. Therefore, the projection image display device using the one-dimensional AMA pre-scans the M × 1 beams using the scanning mirror, and the projection image display device using the two-dimensional AMA displays the image by projecting the M × N beams.

In addition, the actuator is classified into a bulk type and a thin film type according to the shape of the deformable portion. The bulk type thinly cuts a multilayer ceramic, mounts a ceramic wafer having a metal electrode therein on a driving substrate, processes it by sawing, and mounts a mirror. However, bulk actuators require a long process time because the actuators must be separated by sawing, and there is a problem that the response speed of the deformation part is slow. Therefore, a thin-film actuator that can be manufactured using a semiconductor process has been developed.

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

Referring to FIG. 1A, a driving substrate (not shown) having a pad (13) embedded in a matrix form and having a pad 13 made of metal such as Al, TiN, or W electrically connected to the transistor ( A sacrificial film 15 for forming an air gap on the surface of 11) is formed to a thickness of about 1 ~ 2㎛. Then, the sacrificial film 15 in the portion where the pad 13 is formed is removed by a conventional photolithography method to expose the pad 13 and the surrounding driving substrate 11.

Referring to FIG. 1B, the membrane 17 is formed on the driving substrate 11 and the sacrificial layer 15 to a thickness of about 1 μm to 2 μm. In addition, after the opening 18 is formed to expose the pad 13 to a predetermined portion of the membrane 17, the plug 18 is electrically connected to the pads 13 by filling a conductive metal in the opening 18. plug 19). Subsequently, a lower electrode 21 having a thickness of about 500 to 2000 micrometers is formed on the membrane 17 so as to be electrically connected to the plug 19. Therefore, the pad 13 and the lower electrode 21 are electrically connected to each other by the plug 19.

Referring to FIG. 1C, the deformation part 23 and the upper electrode 25 are formed on the surface of the lower electrode 21. In the above, the deformable portion 23 is applied to the piezoelectric ceramic or the total distortion ceramic to a thickness of about 0.7 ~ 2㎛, the upper electrode 25 is formed by depositing a metal having good reflection characteristics and electrical characteristics. Subsequently, the upper electrode 25, the deformable portion 23, the lower electrode 21, and the membrane 17 are etched to expose the driving substrate 11 to separate the actuators. When separating the actuators, the upper electrode 25, the deformable portion 23, the lower electrode 21 and the membrane 17 are etched by reactive ion etching (RIE) using respective etching masks. Then, a protective film 27 is formed on the surface of the upper electrode 25 and side surfaces of the actuators by photoresist or the like.

Referring to FIG. 1D, the sacrificial layer 15 is removed with an etching solution such as hydrofluoric acid solution (HF). In this case, the protective layer 27 prevents sidewalls of the membrane 17 and the deformable portion 23 from being etched to separate the layers. Next, the sacrificial film 15 is removed to form an air gap 29.

However, in the method of manufacturing the optical path control apparatus according to the related art described above, after the sacrificial film is removed by the solvent, the solvent is removed to be removed, and the bottom portion of the membrane is attached to the driving substrate by the surface tension when the cleaning solution is dried. There was a problem that the phenomenon occurs.

Accordingly, an object of the present invention is to provide a method for manufacturing an optical path control apparatus capable of preventing a sticking phenomenon during cleaning and drying for removing a solvent from which a sacrificial film is removed.

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 on an upper surface of a driving substrate having pads embedded in a matrix state and having pads electrically connected to the transistors on a surface thereof. Removing the sacrificial layer around a predetermined portion to expose the driving substrate, forming a membrane on the exposed driving substrate and the sacrificial layer, and removing the predetermined portion of the membrane so that the pad is exposed. And forming a plug in the opening, forming a lower electrode in electrical contact with the plug on the membrane, and sequentially forming a deformable portion and an upper electrode on the lower electrode. And a portion of the sacrificial layer formed from the upper electrode to the membrane. Forming a bridge on the surface of the upper electrode and on the side of the actuator, and forming a bridge that mechanically connects the passivation layer of the actuator adjacent to the passivation layer to a predetermined portion of the exposed driving substrate. And a step of removing the sacrificial film, and a step of removing the protective film and the bridge.

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

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

Referring to FIG. 2 (a), a transistor (not shown) is built in a matrix on the surface thereof, and the surface of the driving substrate 41 having the pad 43 electrically connected to the transistor is about 1 to 2 μm. A sacrificial film 45 of thickness is formed. In the above, the driving substrate 41 is made of an insulating material such as glass or alumina (Al ₂ O ₃ ), or a semiconductor such as silicon. In the above, the sacrificial layer 45 is formed of PSG (Phospho-Silicate Glass) or polycrystalline silicon, and PSG surface spin coating method, if the polycrystalline silicon chemical vapor deposition (hereinafter, referred to as CVD) It is formed by the method. In addition, the sacrificial layer 45 including the periphery of the pads 43 is etched to expose the driving substrate 41.

Referring to FIG. 2 (b), a silicide such as silicon nitride (Si ₃ N ₄ ) or silicon carbide, such as silicon nitride (Si ₃ N ₄ ) or silicon carbide, is formed on the driving substrate 41 and the sacrificial layer 45 by 1 to 2 μm. The membrane 47 is formed by depositing to a thickness of a degree. Next, an opening 49 is formed in a predetermined portion of the membrane 47 by a conventional photolithography method, and the pad is filled with a metal such as tungsten (W) or titanium (Ti) inside the opening 49. And a plug 51 which is electrically connected to the 43. Subsequently, platinum (Pt), platinum / titanium (Pt / Ti), or the like is deposited on the membrane 47 to a thickness of about 500 to 2000 mW by vacuum deposition or sputtering to form a lower electrode 53. The lower electrode 53 is formed to be electrically connected to the plug 51. Therefore, the pad 43 and the lower electrode 53 are electrically connected by the plug 51.

Referring to FIG. 2C, the deformation part 55 is formed on the surface of the lower electrode 53. The deformation part 55 is a piezoceramic 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 ) is formed by applying a total distortion ceramic, such as Sol-Gel method, sputtering or CVD method to a thickness of about 1 ~ 2㎛. In the above, since the deformable portion 55 is formed thin, it is polarized by an image signal applied during driving without any additional polarization. Subsequently, the upper electrode 57 is formed on the deformation part 55. The upper electrode 57 is formed by depositing a metal having good electrical conductivity and reflective properties to a thickness of about 500 to 1000 mW by sputtering or vacuum deposition. The actuators are separated by removing a predetermined portion of the upper electrode 57, the deformable portion 55, the lower electrode 53, and the membrane 47 by a photolithography method. In this case, each of the upper electrode 57, the deformable part 55, the lower electrode 53, and the membrane 47 requires an etching mask for each layer. Then, the photoresist is applied to the entire surface of the structure described above, followed by exposure and development to form a protective film 59 and a bridge 61. The passivation layer 59 is formed on the surface of the upper electrode 57 and the side surfaces generated when the actuators are separated, and the bridge 61 is formed on the actuators adjacent to a predetermined portion of the exposed driving substrate 41. The protective film 59 is formed long to mechanically connect the protective film 59.

Referring to FIG. 2 (d), the sacrificial layer 45 is removed with an etching solution such as hydrofluoric acid (HF). Then, it is washed with deionized water to remove the etching solution on the actuator and dried to remove the deionized water. The protective layer 59 prevents the side of the deformable part 55 from being etched by contact with the etching solution when the sacrificial layer 45 is etched, and the bridge 61 is dried by the surface tension of the cleaning solution. The lowering of the membrane 47 prevents the phenomenon of sticking to the surface of the driving substrate 41. In the above, the space from which the sacrificial layer 45 is removed becomes the air gap 63. Next, the protective film 59 and the bridge 61 are removed. In the above, the protective film 59 and the bridge 61 are burned or removed by dry etching such as plasma.

As described above, the present invention forms a protective film on the surface of the upper electrode and the side surfaces generated when separating the actuators, and at the same time mechanically connects the protective film formed on the actuators adjacent to a predetermined portion of the exposed driving substrate. Forming a long to remove the sacrificial film with an etching solution to prevent the flow of the actuators when cleaning and drying.

Therefore, the present invention has the advantage of preventing the sticking phenomenon caused by the surface tension of the cleaning solution during cleaning and drying.

Claims (9)

Forming a sacrificial layer 45 on top of the driving substrate 41 having the pads 43 embedded therein in a matrix state and electrically connected to the transistors on a surface thereof; Removing the sacrificial layer 45 at a portion to expose the driving substrate 41, and forming a membrane 47 on the exposed driving substrate 41 and the sacrificial layer 45; Removing a portion of the membrane 47 so that the pad 43 is exposed to form an opening 49 and forming a plug 51 in the opening 49, and the upper portion of the membrane 47 Forming a lower electrode 53 in electrical contact with the plug 51, sequentially forming a deformable portion 55 and an upper electrode 57 on the lower electrode 53; The sacrificial layer 45 exposes a predetermined portion from the electrode 57 to the membrane 47. Separating the actuators to form a protective film 59 on the surface of the upper electrode 57 and the actuator, and adjoining the protective film 59 at a predetermined portion of the exposed driving substrate 41. Forming a bridge 61 to mechanically connect the protective film of the actuator; removing the sacrificial film 45; and removing the protective film 59 and the bridge 61; Method of manufacturing the device. The method of claim 1, wherein the deformable portion (55) is formed of piezoelectric ceramics of BaTiO ₃ , PZT or PLZT. The method of manufacturing an optical path control device according to claim 1, wherein the deformation part (55) is formed of a total distortion ceramic of PMN. The method according to claim 2 or 3, wherein the deformable portion (55) is formed by a rotary coating method, a spraying method or a chemical vapor deposition method. The method of manufacturing an optical path control device according to claim 4, wherein the deformation part (55) is formed to a thickness of 1 to 2 mu m. The method of manufacturing an optical path control device according to claim 1, wherein the protective film (59) and the bridge (61) are formed of photoresist. The method of claim 1, wherein the sacrificial layer is removed by a wet etching method. The method of claim 1, further comprising: cleaning and drying the sacrificial layer after removing the sacrificial layer (45). The method of claim 1, wherein the passivation layer (59) and the bridge (61) are burned or removed by a dry etching method using plasma.