KR19990035329A - Manufacturing method of thin film type optical path control device - Google Patents

Abstract

Disclosed is a method of manufacturing a thin film type optical path control device capable of improving the ferroelectric properties of a strained layer. A first layer, a lower electrode layer, a second layer, and an upper electrode layer are sequentially formed on an active matrix including M × N (M and N are integers) MOS transistors and including a drain pad formed on one side. After the upper electrode layer and the second layer are patterned to form the upper electrode and the strain layer, the strain layer is polarized by maintaining a potential difference of 10 V for 10 minutes at a temperature of 120 to 140 ° C. The lower electrode layer and the first layer are patterned to form the lower electrode and the support layer, and then a mirror is formed on the support layer. By polarizing the strained layer, the ferroelectric characteristics of the strained layer can be improved, and the change in residual polarization caused during driving can be reduced to suppress the initial tilt of the actuator.

Description

Manufacturing method of thin film type optical path control device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an Actuated Mirror Array (AMA), which is a thin film type optical path control device. It relates to a manufacturing method of a thin film type optical path control device that can improve the.

Optical path control devices or spatial light modulators for projecting optical energy onto a screen may be applied to various fields such as optical communication, image processing, and information display devices. An image processing apparatus using such an optical modulator is generally divided into a direct-view image display device and a projection-type image display device according to a method of displaying optical energy on a screen. do.

An example of a direct-view image display device is a CRT (Cathode Ray Tube). The CRT device is called a CRT, which has excellent image quality but increases in weight and volume as the screen is enlarged, leading to an increase in manufacturing cost. There is. Projection type image display apparatuses include a liquid crystal display (LCD), a deformable mirror device (DMD), and an AMA. Such projection image display devices can be further divided into two groups according to their optical characteristics. That is, devices such as LCDs can be classified as transmissive spatial light modulators, while DMD and AMA can be classified as reflective spatial light modulators.

Transmission optical modulators, such as LCDs, have a very simple optical structure, which makes them thinner, lighter in weight, and smaller in volume. However, due to the polarity of the light, the light efficiency is low, there is a problem inherent in the liquid crystal material, for example, there is a disadvantage that the response speed is slow and the inside is easy to overheat. In addition, the maximum light efficiency of existing transmission light modulators is limited to a range of 1-2%, requiring dark room conditions to provide acceptable display quality. Therefore, optical modulators such as DMD and AMA have been developed to solve the above problems.

Although DMD shows a relatively good light efficiency of about 5%, the hinge structure employed in the DMD not only causes serious fatigue problems, but also requires a very complicated and expensive driving circuit. The AMA reflects the light incident from the light source at each angle installed in the mirrors, and the reflected light is projected on the screen through an aperture such as a slit or pinhole to be imaged. The device can adjust the luminous flux to bear. Therefore, its structure and operation principle are simple, and high light efficiency (more than 10% light efficiency) can be obtained compared to LCD or DMD. In addition, the contrast of the image projected on the screen is improved to obtain a brighter and clearer image.

Each actuator of the AMA generates a deformation in accordance with the electric field generated by the applied electric picture signal and the bias signal. As the actuator deforms, each of the mirrors mounted on top thereof is inclined. Therefore, the inclined mirrors reflect the light incident from the light source at a predetermined angle to form an image on the screen. As an actuator for driving the respective mirrors, piezoelectric materials such as PZT (Pb (Zr, Ti) O ₃ ) or PLZT ((Pb, La) (Zr, Ti) O ₃ ) are used. It is also possible to configure the actuator as electrostrictive material such as PMN (Pb (Mg, Nb) O 3).

These AMA devices are largely divided into bulk type and thin film type. Bulk light path control devices are disclosed in US Pat. No. 5,085,497 to Gregory Um et al. The bulk optical path adjusting device is made by thinly cutting a multilayer ceramic to mount a ceramic wafer having a metal electrode formed therein in an active matrix in which a transistor is embedded, and then processing by a sawing method and installing a mirror thereon. However, the bulk optical path control device requires very high precision in design and manufacture, and has a disadvantage in that the response of the deformable part is slow.

Accordingly, a thin film type optical path control apparatus that can be manufactured using a semiconductor manufacturing process has been developed. The thin film type optical path control device is a patent application No. 96-42197 filed by the applicant of the Korean Patent Office on September 24, 1996 (name of the invention: thin film type optical path control device that can control the stress of the membrane and its manufacturing method) Is disclosed.

1A and 1B are cross-sectional views illustrating a method of manufacturing a thin film type optical path adjusting device described in the preceding application.

First, the structure of the thin film type optical path control device is as follows.

The thin film type optical path control device includes an active matrix 1 and an actuator 60. An active matrix 1 having an MxN (M, N is an integer) MOS transistor therein and having a drain pad 5 extending from a drain region of the MOS transistor includes an active matrix 1 and a drain pad ( 5) a protective layer 10 stacked on top of the protective layer 10 and an etch stop layer 15 stacked on top of the protective layer 10.

The actuator 60 contacts one side of a portion of the etch stop layer 15 in which the drain pad 5 is formed, and the other side of the actuator 60 is horizontally laminated through the air gap 25. Of the lower electrode 35 stacked on top of the lower electrode 35, the strained layer 40 stacked on top of the lower electrode 35, the upper electrode 45 stacked on top of the strained layer 40, and the strained layer 40. The lower electrode 35 and the drain in the via hole 50 formed vertically from one side to the drain pad 5 through the lower electrode 35, the membrane 30, the etch stop layer 15, and the protective layer 10. The pad 5 includes a via contact 55 formed to be connected to each other.

A stripe 46 is formed on a part of the upper electrode 45. The stripe 46 operates the upper electrode 45 uniformly so that the light incident from the light source is diffusely reflected at the boundary between the portion of the upper electrode 45 that is deformed and the portion that is not deformed due to the deformation of the deforming layer 40. prevent.

Hereinafter, the manufacturing method of the said thin film type optical path control apparatus is demonstrated.

Referring to FIG. 1A, an active matrix made of an n-type doped silicon wafer, in which M × N (M, N is an integer) P-MOS transistors are formed and a drain pad 5 extending from the drain region of the transistor is formed. The protective layer 10 is formed on (1) using phosphorus silicate glass PSG. The protective layer 10 is formed to have a thickness of about 1.0 μm using a chemical vapor deposition (CVD) method. The protective layer 10 protects the active matrix 1 in which the transistor is embedded during subsequent processing.

An etch stop layer 15 made of nitride is formed on the protective layer 10. The etch stop layer 15 is formed to have a thickness of about 1000 to 2000 kPa using a low pressure chemical vapor deposition (LPCVD) method. The etch stop layer 15 prevents the protective layer 10 and the active matrix 1 from being etched and damaged during the subsequent etching process.

The sacrificial layer 20 is formed on the etch stop layer 15. The sacrificial layer 20 is formed of phosphorous silicate glass (PSG) having a high concentration of phosphorus (PG) to have a thickness of about 1.0 to 3.0 µm using the atmospheric pressure chemical vapor deposition (APCVD) method. In this case, since the sacrificial layer 20 covers the upper portion of the active matrix 1 in which the MOS transistors are embedded, the surface flatness is very poor. Accordingly, the surface of the sacrificial layer 20 is planarized by using spin on glass (SOG) or chemical mechanical polishing (CMP). Subsequently, a portion of the sacrificial layer 20 in which the drain pad 5 is formed is etched to expose a portion of the etch stop layer 15, thereby forming a support of the actuator 60.

The membrane 30 is stacked on the exposed etch stop layer 15 and on the sacrificial layer 20. The membrane 30 is formed by depositing nitride to a thickness of about 0.01 to 1.0 mu m using a low pressure chemical vapor deposition (LPCVD) method.

The lower electrode 35 is stacked on top of the membrane 30. The lower electrode 35 is formed to have a thickness of about 0.01 to 1.0 μm by sputtering a metal such as platinum (Pt), tantalum (Ta), or platinum-tantalum (Pt-Ta). Subsequently, the lower electrode 35 is separated for each pixel through a photolithography process so that a unique first signal (image signal) is applied to each pixel (Iso­Cut process). A first signal (image signal) is applied to the lower electrode 35 through a transistor built in the active matrix 1 from the outside.

A deformation layer 40 made of a piezoelectric material such as PZT or PLZT is stacked on the lower electrode 35. The strained layer 40 is formed to have a thickness of 0.1 to 1.0 탆 using a sol-gel method, a sputtering method, or a chemical vapor deposition method. Preferably, the strained layer 40 is formed so that PZT has a thickness of about 0.4 µm using the sol-gel method. In addition, the piezoelectric material constituting the strained layer 40 is subjected to heat treatment by a rapid heat treatment (RTA) method to cause phase shift. In the strained layer 40, a second signal (bias signal) is applied to the upper electrode 45, and a first signal is applied to the lower electrode 35, according to a potential difference between the upper electrode 45 and the lower electrode 35. It is deformed by the generated electric field.

The upper electrode 45 is stacked on top of the strained layer 40. The upper electrode 45 is formed so as to have a thickness of about 0.01 to 1.0 탆 by sputtering a metal such as aluminum (Al), silver (Ag), or platinum (Pt). The second signal is applied to the upper electrode 45 through a common electrode line (not shown) from the outside. Since the upper electrode 45 has both electrical conductivity and reflectivity at the same time, the upper electrode 45 functions not only as a bias electrode for generating an electric field but also as a mirror for reflecting incident light.

Referring to FIG. 1B, the upper electrode 45, the deformation layer 40, and the lower electrode 35 are sequentially patterned from a top of the upper electrode 45 into a predetermined pixel shape. At this time, a portion of the upper electrode 45 is formed with a stripe 46 to uniformly operate the upper electrode 45 to prevent diffuse reflection of light incident from the light source.

Subsequently, the via hole 50 is formed by sequentially etching the strained layer 40, the lower electrode 35, the membrane 30, the etch stop layer 15, and the protective layer 10 from one side of the strained layer 40. do. Therefore, the via hole 50 is formed from one side of the strained layer 40 to the drain pad 5. Subsequently, a metal having electrical conductivity such as tungsten (W), aluminum (Al), or titanium (Ti) is deposited using a sputtering method to form the via contact 55. The via contact 55 connects the drain pad 5 and the lower electrode 35. Therefore, the first signal applied from the outside is applied to the lower electrode 35 through the transistor, the drain pad 5, and the via contact 55 embedded in the active matrix 1. Then, the membrane 30 is patterned into a predetermined pixel shape.

Subsequently, the sacrificial layer 20 is etched using hydrogen fluoride (HF) vapor to form an air gap 25 at the position of the sacrificial layer 20, followed by a rinse and dry treatment. Complete the AMA device.

In the above-described thin film type optical path adjusting device, the first signal is applied to the lower electrode 35 through the MOS transistor, the drain pad 5, and the via contact 55 embedded in the active matrix 1. At the same time, a second signal is applied to the upper electrode 45 to generate an electric field between the upper electrode 45 and the lower electrode 35. Due to this electric field, the strained layer 40 stacked between the upper electrode 45 and the lower electrode 35 causes deformation. The strained layer 40 contracts in a direction perpendicular to the generated electric field, and the actuator 60 including the strained layer 40 is bent upward at a predetermined angle. Therefore, the upper electrode 45 on the actuator 60 is also inclined in the same direction. Light incident from the light source is reflected by the upper electrode 45 at a predetermined angle, and then is projected onto the screen to form an image.

However, in the thin film type optical path adjusting device described in the preceding application, PZT (Pb (Zr, Ti) O ₃ ), or PLZT ((Pb, La) (Zr, Ti) O ₃ ) used as a constituent material of the strained layer. Piezoelectric materials such as the more the number of driving is increased the fatigue (fatigue) is accelerated (polarization) is gradually reduced. This fatigue causes the upper electrode to undergo tensile stress due to shrinkage that is inherently present during the fabrication of the strained layer when the dipoles inside the piezoelectric material are continuously applied with no voltage. This is generated because the amount of polarization remaining in the strained layer changes as a result of compensation while switching in a direction parallel to the electric field generated between the lower and lower electrodes. As a result, the actuator may have an initial deflection even when no voltage is applied, thereby lowering the contrast of the image.

Accordingly, an object of the present invention is to improve the ferroelectric properties of the strained layer by applying a voltage to the piezoelectric material constituting the strained layer at low temperature, thereby improving the ferroelectric characteristics of the strained layer, and reducing the change in the amount of residual polarization caused during driving. The present invention provides a method for manufacturing a thin film type optical path control apparatus capable of suppressing an initial tilt of the film and preventing a decrease in contrast of an image.

1A and 1B are cross-sectional views illustrating a method of manufacturing a thin film type optical path adjusting device described in the applicant's prior application.

2 is a plan view of a thin film type optical path control apparatus according to the present invention.

3 is a cross-sectional view of the device shown in FIG. 2 taken along line A′A ′.

4A and 4D are manufacturing process diagrams of the apparatus shown in FIG. 3.

<Explanation of symbols for main parts of drawing>

100: active matrix 105: first metal layer

110: first protective layer 115: second metal layer

120: second protective layer 125: etch stop layer

135: sacrificial layer 140: support layer

145: lower electrode 150: strained layer

155: upper electrode 160: via hole

165: beer contact 180: mirror

185: air gap 200: actuator

In order to achieve the above object, the present invention provides a method comprising the steps of providing an active matrix comprising a first metal layer having M x N (M, N is an integer) MOS transistor embedded therein and having a drain pad extending from the drain of the transistor; i) sequentially forming a first layer, a lower electrode layer, a second layer and an upper electrode layer on top of the active matrix, ii) patterning the upper electrode layer to form an upper electrode, and iii) patterning the second layer to deform it. Forming a layer, iii) applying a voltage of 10V at a temperature of 120 to 140 ° C. for 10 minutes to polarize the strained layer, and iii) patterning the lower electrode layer to form a lower electrode and patterning the first layer. Forming an actuator including forming a support layer; And it provides a method of manufacturing a thin film type optical path control device comprising the step of forming a mirror on top of the support layer.

According to the manufacturing method of the thin film type optical path control device according to the present invention, after forming a strained layer composed of PZT, PLZT, etc., about 10 minutes at a temperature of 120 ~ 140 ℃ while applying a voltage of about 10V to the upper electrode and lower electrode layer Keep it on. The resultant is then cooled to room temperature to polarize the piezoelectric material constituting the strained layer. Therefore, since the polarization direction of each grain of the piezoelectric material can be made in one direction as possible, it is possible to polarize linearly with respect to the applied voltage and to minimize the change in the residual polarization amount. As a result, the ferroelectric properties of the strained layer can be improved and the initial tilt of the actuator can be minimized. In addition, the polarization process of the strained layer is carried out at a low temperature of 120 ~ 140 ℃ does not affect the subsequent process.

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

FIG. 2 is a plan view of a thin film type optical path adjusting device according to the present invention, and FIG. 3 is a cross-sectional view taken along line A′A ′ of the device shown in FIG. 2.

2 and 3, the thin film type optical path adjusting apparatus according to the present invention includes an active matrix 100, an actuator 200, and a mirror 180.

The active matrix 100 having M x N (M, N is an integer) embedded therein includes a first metal layer 105 and an upper portion of the first metal layer 105 extending from a source and a drain of the MOS transistor. The first protective layer 110, the second metal layer 115 formed on the first protective layer 110, the second protective layer 120 formed on the second metal layer 115, and the second protective layer 120. It includes an etch stop layer 125 formed on the top. The first metal layer 105 includes a drain pad extending from the drain of the MOS transistor, and the second metal layer 115 is formed of a titanium (Ti) layer and a titanium nitride (TiN) layer.

Referring to FIG. 3, the actuator 200 has one side in contact with a portion of the etch stop layer 125 at which a drain pad of the first metal layer 105 is formed and the other side is horizontally formed through the air gap 185. The support layer 140, the lower electrode 145 formed on the support layer 140, the strained layer 150 formed on the lower electrode 145, the upper electrode 155 formed on the strained layer 150, and From one side of the strained layer 150 through the strained layer 150, the lower electrode 145, the support layer 140, the etch stop layer 125, the second protective layer 120 and the first protective layer 110. The via contact 160 includes a via contact 165 formed to connect the lower electrode 145 and the drain pad to the via hole 160 vertically up to the drain pad of the metal layer 105. The support layer 140 performs the function of a membrane supporting the actuator of the thin film optical path control device described in the previous application.

The support layer 140 has a shape in which a rectangular flat plate is integrally formed with the arms on the same plane between two rectangular arms formed in parallel from both support portions. The mirror 180 is formed on the rectangular flat plate of the support layer 140. Thus, the mirror 180 has the shape of a rectangular flat plate.

Hereinafter, a method of manufacturing a thin film type optical path control device according to the present invention will be described in detail with reference to the drawings.

4A to 4D show a manufacturing process chart of the thin film type optical path control apparatus according to the present invention.

Referring to FIG. 4A, after preparing an active matrix 100, which is an n-type doped silicon (Si) wafer, the active matrix 100 is prepared using a conventional device isolation process, for example, silicon partial oxidation (LOCOS). An isolation layer for forming an active region and a field region is formed on the substrate. Subsequently, after forming a gate made of a conductive material such as polysilicon doped with impurities on top of the active region, p ⁺ sources and drains are formed by an ion implantation process, thereby forming M x N (M and N are integers) MOS. Form a transistor.

After forming an insulating film made of an oxide on top of the resultant MOS transistor is formed, openings for exposing the top of one side of the source and the drain, respectively, by a photolithography process. Subsequently, a first metal layer 105 made of a metal such as titanium, titanium nitride, or tungsten (W) is deposited on the resultant, on which the openings are formed, and then the first metal layer 105 is patterned by a photolithography process. The patterned first metal layer 105 includes a drain pad extending from the drain of the MOS transistor to one side of the support of the actuator 200.

The first passivation layer 110 is formed on the first metal layer 105. The first passivation layer 110 is formed to have a thickness of about 8000 GPa by using the silicate glass (PSG) chemical vapor deposition (CVD) method. The first protective layer 110 prevents damage to the active matrix 100 in which the MOS transistor is embedded during the subsequent process.

The second metal layer 115 is formed on the first protective layer 110. In order to form the second metal layer 115, first, a titanium layer is formed by sputtering titanium (Ti) to a thickness of about 300 μm. Subsequently, titanium nitride is deposited on top of the titanium layer using a physical vapor deposition (PVD) method to form a titanium nitride layer. The second metal layer 115 prevents light leakage current from flowing through the active matrix 100 because light incident from the light source is incident not only on the mirror 180 but also on a portion other than the portion where the mirror 180 is formed. . Subsequently, a portion of the second metal layer 115 in which the via contact 165 is to be formed in a subsequent process is etched through a photolithography process to form an opening in the second metal layer 115.

The second passivation layer 120 is formed on the second metal layer 115. The second protective layer 120 is formed to have a thickness of about 2000 GPa using in-silicate glass (PSG). The second protective layer 120 also prevents damage to the active matrix 100 in which the MOS transistor is embedded and the results formed on the active matrix 100 during the subsequent process.

An etch stop layer 125 is formed on the second passivation layer 120. The etch stop layer 125 prevents the active matrix 100 and the second passivation layer 120 from being etched due to the subsequent etching process. The etch stop layer 125 is formed to have a thickness of about 1000 to 2000 kPa by depositing nitride (Si ₃ N ₄ ) by low pressure chemical vapor deposition (LPCVD).

The sacrificial layer 135 is formed on the etch stop layer 125. The sacrificial layer 135 is formed by depositing phosphorus silicate glass (PSG) to a thickness of about 2.0 to about 3.0 μm using the atmospheric pressure chemical vapor deposition (APCVD) method. In this case, since the sacrificial layer 135 covers the upper portion of the active matrix 100 in which the MOS transistor is embedded, the surface flatness is very poor. Therefore, the surface of the sacrificial layer 135 is planarized by polishing the surface of the sacrificial layer 135 using a spin on glass (SOG) method or a chemical mechanical polishing (CMP) method so that the thickness of the sacrificial layer 135 is about 1 .mu.m. .

Subsequently, the portion of the sacrificial layer 135 having the opening of the second metal layer 115 formed thereon and an adjacent portion thereof are etched to expose a portion of the etch stop layer 125, thereby anchoring an anchor which is a support of the actuator 200. Make a position to form.

Referring to FIG. 4B, a first layer 139 is formed on the exposed etch stop layer 125 and on the sacrificial layer 135. The first layer 139 is formed to have a thickness of about 0.1 to 1.0 탆 using low pressure chemical vapor deposition (LPCVD). The first layer 139 is later patterned into the support layer 140.

The lower electrode layer 144 is formed on the first layer 139 by using a metal such as platinum, tantalum, or platinum-tantalum (Pt-Ta), which is a metal having excellent electrical conductivity. The lower electrode layer 144 is formed to have a thickness of about 0.01 to 1.0 탆 using a sputtering method. Subsequently, the lower electrode layer 144 is separated for each pixel so that an independent first signal is applied to each pixel (Iso­Cut process). The lower electrode layer 144 is later patterned into the lower electrode 145. The first signal transferred from the transistor embedded in the active matrix 100 is applied to the lower electrode 145.

The second layer is stacked on the lower electrode layer 144. The second layer is formed using a piezoelectric material such as PZT or PLZT so as to have a thickness of 0.1 to 1.0 mu m, preferably about 0.4 mu m. The second layer is formed using a sol-gel method, a sputtering method, or a chemical vapor deposition (CVD) method, and then subjected to a phase change by heat treatment using a rapid heat treatment (RTA) method. The second layer is later patterned into strained layer 150. The deforming layer 150 is applied to an electric field generated by a second signal applied to the upper electrode 155 and a first signal applied to the lower electrode 145 according to a potential difference between the upper electrode 155 and the lower electrode 145. Cause deformation.

An upper electrode layer is stacked on top of the second layer. The upper electrode layer is formed of a metal having electrical conductivity and reflectivity, such as platinum, aluminum, or silver, to have a thickness of about 0.01 to 1.0 탆 using a sputtering method.

After the first photoresist (not shown) is coated on the upper electrode layer by spin coating, the upper electrode layer is patterned to have a mirror-shaped 'C' shape as shown in FIG. An electrode 155 is formed. The second signal is applied to the upper electrode 155 through a common electrode line (not shown) from the outside. Subsequently, after the first photoresist is removed, a second photoresist (not shown) is applied on the patterned upper electrode 155 and the second layer by spin coating, and then the second layer is the upper electrode 155. The strained layer 150 is formed to have a shape of a 'c' of a slightly larger mirror image (see FIG. 2). Subsequently, the second photoresist is removed and the strained layer 150 is polarized. Preferably, the resultant is maintained at a temperature of 120 to 140 ° C., more preferably at a temperature of 130 ° C., for about 10 minutes while applying a voltage of about 10 V to the upper electrode 155 and the lower electrode layer 144. Cool down. Therefore, since the polarization direction of each grain of the piezoelectric material can be made in one direction as possible, it is possible to polarize linearly with respect to the applied voltage and to minimize the change in the residual polarization amount. Conventional polarization process is carried out at a temperature of about 200 ℃ but in the present invention, since the polarization process of the strained layer was carried out at a low temperature of 120 ~ 140 ℃ does not affect the subsequent process.

Referring to FIG. 4C, after the third photoresist (not shown) is coated on the upper electrode 155, the deformation layer 150, and the lower electrode layer 144 by a spin coating method, the lower electrode layer 144 is applied. The lower electrode 145 is formed by patterning the optical layer to have a shape of 'c' slightly wider than the strained layer 150. Next, the strained layer 150, the lower electrode 145, the first layer 139, the etch stop layer 125, and the first layer are formed from a portion of the strained layer 150 in which an opening of the second metal layer 115 is formed below. The protective layer 120 and the first protective layer 110 are sequentially etched to form the via hole 160 from one side of the strained layer 150 to the drain pad of the first metal layer 105. The via contact 165 is formed in the inside of the 160 to connect the drain pad of the first metal layer 105 and the lower electrode 145 by sputtering a metal such as tungsten (W), platinum, aluminum, or titanium. do. Therefore, the via contact 165 is formed from the lower electrode 145 to the top of the drain pad in the via hole 160. The first signal transmitted from the outside is applied to the lower electrode 145 through the transistor embedded in the active matrix 100, the drain pad of the first metal layer 105, and the via contact 165.

Subsequently, after the fourth photoresist (not shown) is applied to the patterned lower electrode 145 and the via hole 160 by the spin coating method, a portion extending from both supporting portions of the first layer 139. Silver has a slightly wider rectangular shape than the lower electrode 145, and the center portion of the first layer 139 formed integrally with the lower electrode 145 is patterned to have a rectangular flat plate shape to form the support layer 140. That is, as shown in FIG. 2, the support layer 140 has a shape in which rectangular arms extend from both support portions, and a rectangular flat plate having a larger area between these arms is formed integrally with the arms on the same plane. Have Then, the fourth photoresist is removed. As a result of the patterning of the support layer 140 as described above, a portion of the sacrificial layer 135 is exposed.

After applying a fifth photoresist (not shown) on the exposed sacrificial layer 135 and the support layer 140 by spin coating, patterning is performed so that a rectangular flat plate, which is the center of the support layer 140, is exposed. do. In addition, a sputtering method or a chemical vapor deposition method is used to form a metal having reflective properties such as silver, platinum, or aluminum on the upper portion of the central portion of the rectangular exposed support layer 140 in a thickness of about 0.3 to 2.0 µm. By deposition. Subsequently, the deposited metal is patterned so that the deposited metal has the same shape as the center portion of the rectangular exposed support layer 140 to form the mirror 180, and then the fifth photoresist is removed.

Referring to FIG. 4D, the sacrificial layer 135 is etched using hydrogen fluoride (HF) vapor to form an air gap 185 at the position of the sacrificial layer 135, followed by rinse and dry. The process is performed to complete the AMA device.

In the above-described thin film type optical path control device according to the present invention, a second signal is applied to the upper electrode 155 through a common electrode line from the outside. At the same time, a first signal is applied to the lower electrode 145 from the outside through the transistor embedded in the active matrix 100, the drain pad of the first metal layer 115, and the via contact 165. An electric field is generated between the electrodes 145 according to the potential difference. Due to this electric field, the deformation layer 150 formed between the upper electrode 155 and the lower electrode 145 causes deformation. At this time, since the strained layer 150 has undergone a polarization process, the ferroelectric characteristics are improved to linearly deform the electric field according to the applied potential difference. The strained layer 150 contracts in a direction orthogonal to the generated electric field, and thus the actuator 200 including the strained layer 150 and the support layer 140 is bent at a predetermined angle. Since the mirror 180 reflecting the light incident from the light source is formed above the central portion of the support layer 140, the mirror 180 is bent at the same angle as the actuator 200. Accordingly, the mirror 180 reflects the incident light at a predetermined angle, and the reflected light passes through the slit and is projected onto the screen to form an image.

As described above, according to the manufacturing method of the thin film type optical path control device according to the present invention, the piezoelectric material is polarized by applying a voltage to the piezoelectric material constituting the strained layer. As a result, the direction of polarization of each grain of the piezoelectric material can be made as straight as possible, thereby linearly polarizing the applied voltage and minimizing the change in the amount of residual polarization. As a result, the ferroelectric characteristics of the strained layer are improved, and the initial tilting of the actuator can be suppressed to prevent the contrast decrease of the image. In addition, the polarization process of the strained layer is carried out at a low temperature of 120 ~ 140 ℃ does not affect the subsequent process.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited thereto and may be improved or modified by those skilled in the art within the scope of the technical idea of the present invention.

Claims (1)

Providing an active matrix comprising a first metal layer with M × N (M, N is an integer) embedded therein and having drain pads extending from the drain of the transistor; i) sequentially forming a first layer, a lower electrode layer, a second layer and an upper electrode layer on top of the active matrix, ii) patterning the upper electrode layer to form an upper electrode, i) forming the second layer Patterning to form a strained layer, iii) polarizing the strained layer by applying a voltage of 10V at a temperature of 120 to 140 ° C. for 10 minutes, and iii) patterning the lower electrode layer to form a lower electrode; and Forming an actuator comprising patterning the first layer to form a support layer; And Method of manufacturing a thin film type optical path control device comprising the step of forming a mirror on top of the support layer.