KR19990039330A - Manufacturing method of thin film type optical path control device - Google Patents

Abstract

Disclosed is a thin film type optical path control apparatus capable of improving optical efficiency by preventing the bending of a mirror due to stress generated when forming the mirror. After forming an actuator on top of the active matrix, a mirror is formed on top of the actuator. The mirror is formed by depositing and patterning a reflective metal such as aluminum or silver using a sputtering method or a chemical vapor deposition method under a pressure of about 3 to 5 mTorr. When depositing a reflective metal to form a mirror, a stress free condition can be satisfied by depositing the metal under a pressure of about 3 to 5 mTorr, which is a portion of the compressive stress that transitions from tensile stress to tensile stress. In other words, by controlling the deposition pressure to minimize the stress on the metal constituting the mirror to prevent the bending of the mirror, thereby increasing the light efficiency of the light incident from the light source can be improved the image quality of the image projected on the screen eventually .

Description

Manufacturing method of thin film type optical path control device

The present invention relates to a method for manufacturing AMA (Actuated Mirror Array), which is a thin film type optical path control device, and more particularly, a thin film type optical path which can improve optical efficiency by preventing the mirror from being warped due to stress generated when forming a mirror. It relates to a manufacturing method of the adjusting device.

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. In the AMA, each of the mirrors installed therein reflects light incident from the light source at a predetermined angle, and the reflected light is projected on the screen through an aperture such as a slit or a pinhole. It is a device that can adjust the speed of light to form an image. 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 thereon is tilted. Accordingly, the inclined mirrors reflect light incident from the light source at a predetermined angle to form an image on the screen. Piezoelectric materials such as PZT (Pb (Zr, Ti) O ₃ ) or PLZT ((Pb, La) (Zr, Ti) O ₃ ) are used as actuators for driving the respective mirrors. The actuator may also be configured as a warping material such as PMN (Pb (Mg, Nb) O ₃ ).

These AMA devices are largely divided into bulk type and thin film type. The bulk optical path control device is 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 disclosed in Korean Patent Application No. 96-64440 (name of the invention: a method of manufacturing a thin film type optical path control device) filed by the applicant of the Korean Patent Office on December 11, 1996.

Figure 1 shows a cross-sectional view of the thin film type optical path control device described in the preceding application. Referring to FIG. 1, the thin film type optical path adjusting device includes an active matrix 1, an actuator 25, and a mirror 29. The active matrix 1 in which M x N (M, N is an integer) MOS transistors and a drain pad 7 extending from the drain of the transistor is formed. The active matrix 1 and the drain pad ( 7) a protective layer 3 stacked on top of the protective layer 3 and an etch stop layer 5 stacked on the protective layer 3.

The actuator 25 has a membrane 13 and a membrane 13 in which one side is in contact with a portion where the drain pad 7 is formed in the lower portion of the etch stop layer 5, and the other side is horizontally formed through the air gap 11. ), The lower electrode 15 stacked on top of the bottom electrode 15, the strained layer 17 stacked on top of the lower electrode 15, the upper electrode 19 stacked on top of the strained layer 17, and the strained layer 17. In the via hole 21 formed perpendicularly to the drain pad 7 through the strained layer 17, the lower electrode 15, the membrane 13, the etch stop layer 5, and the protective layer 3 from one side of the The lower electrode 15 and the drain pad 7 include a via contact 23 formed to be connected to each other. The mirror 29 has one side bent at a right angle to contact the upper electrode 19 and the other side is formed horizontally. Preferably, the mirror 29 has a shape of 'a'.

Hereinafter, the manufacturing method of the above-mentioned thin film type optical path control apparatus will be described. 2A to 2D are manufacturing process diagrams of the apparatus shown in FIG.

Referring to FIG. 2A, a silicate glass (PSG) is used on top of an active matrix 1 in which M × N MOS transistors (not shown) are embedded and a drain pad 7 extending from the drain of the transistor is formed. The protective layer 3 is laminated. The protective layer 3 is formed to have a thickness of about 1.0 μm using a chemical vapor deposition (CVD) method. The protective layer 3 protects the active matrix 1 in which the MOS transistor is embedded during subsequent processing.

An etch stop layer 5 is stacked on the protective layer 3. The etch stop layer 5 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 5 prevents the active matrix 1 and the protective layer 3 from being etched during the subsequent etching process.

The first sacrificial layer 9 is stacked on the etch stop layer 5. The first sacrificial layer 9 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 an atmospheric chemical vapor deposition (APCVD) method. In this case, since the first sacrificial layer 9 covers the upper portion of the active matrix 1 in which the transistor is embedded, the flatness of the surface thereof is very poor. Accordingly, the surface of the first sacrificial layer 9 is planarized by using spin on glass (SOG) or chemical mechanical polishing (CMP). Subsequently, an anchor, which is a support of the actuator 25, is formed by etching a portion of the first sacrificial layer 9 in which the drain pad 7 is formed below to expose a portion of the etch stop layer 5. Make a location.

Referring to FIG. 2B, the membrane 13 is stacked on the exposed etch stop layer 5 and on the first sacrificial layer 9. The membrane 13 is formed so that the nitride has a thickness of about 0.1 to 1.0 mu m using a low pressure chemical vapor deposition (LPCVD) method. At this time, the membrane 13 is formed while varying the ratio of the reaction gas in the low pressure reaction vessel to control the stress in the membrane 13.

The lower electrode 15 made of a metal such as platinum (Pt), tantalum (Ta), or platinum-tantalum (Pt-Ta) is stacked on the membrane 13. The lower electrode 15 is formed to have a thickness of about 0.1 to 1.0 μm using a sputtering method. A first signal (image signal) is applied to the lower electrode 15 through an MOS transistor built in the active matrix 1 from the outside.

A deformation layer 17 made of a piezoelectric material such as PZT or PLZT is stacked on the lower electrode 15. The strained layer 17 is formed to have a thickness of about 0.1 μm to about 1.0 μm, preferably about 0.4 μm using a sol-gel method, and then subjected to a phase change by heat treatment using a rapid heat treatment (RTA) method. In the strained layer 17, a second signal (bias signal) is applied to the upper electrode 19, and a first signal is applied to the lower electrode 15, according to a potential difference between the upper electrode 19 and the lower electrode 15. It is deformed by the generated electric field.

The upper electrode 19 is formed on the strained layer 17. The upper electrode 19 uses a sputtering method for a metal having electrical conductivity and reflectivity, such as aluminum or platinum. It is formed to have a thickness of about 0㎛. The second signal is applied to the upper electrode 19 through a common electrode line (not shown) from the outside.

Referring to FIG. 2C, after patterning the upper electrode 19, the strained layer 17, and the lower electrode 15 to have a predetermined pixel shape, the drain pad 7 is formed from one side of the strained layer 17. The strained layer 17, the lower electrode 15, the membrane 13, the etch stop layer 5, and the protective layer 3 are sequentially etched so as to vertically pass from the strained layer 17 to the drain pad 7. The hole 21 is formed. Subsequently, a via contact 23 is formed in the via hole 21 so that the drain pad 7 and the lower electrode 15 are electrically connected by sputtering a metal such as tungsten, platinum, or tantalum. Thus, the via contact 23 is vertically formed from the lower electrode 15 to the drain pad 7 in the via hole 21. Therefore, the first signal is applied from the outside to the lower electrode 15 through the transistor, the drain pad 7 and the via contact 23 embedded in the active matrix 1. Then, the first sacrificial layer 9 is etched with hydrogen fluoride (HF) vapor to form the air gap 11 at the first sacrificial layer 9 to complete the actuator 25.

Referring to FIG. 2D, after forming the air gap 11 as described above, the second sacrificial layer 27 is formed on the entire surface of the resultant. The second sacrificial layer 27 is formed to completely cover the actuator 25 while filling the air gap 11 with a polymer having good fluidity by using a spin coating method. Subsequently, one side of the upper electrode 19 is exposed by patterning the second sacrificial layer 27. Subsequently, aluminum (Al) or silver (Ag) having good reflectivity was deposited on the second sacrificial layer 27 and the exposed upper electrode 19 by using a sputtering method. It is deposited to a thickness of about 0 μm and patterned to form a mirror 29. In this case, one side of the mirror 29 is bent at a right angle to contact the upper electrode 19 and the other side has a shape of the 'b' formed horizontally. Then, the second sacrificial layer 27 is removed using an oxygen plasma (O ₂ plasma), and rinsing and drying are performed to complete the thin film type AMA device as shown in FIG. 1.

In the above-described thin film type optical path adjusting device, when the first signal is applied to the lower electrode 15 and the second signal is applied to the upper electrode 19, the potential difference between the upper electrode 19 and the lower electrode 15 depends on the potential difference. Electric field is generated. Due to this electric field, the deformation layer 17 formed between the upper electrode 19 and the lower electrode 15 causes deformation. The strain layer 17 contracts in a direction orthogonal to the electric field, so that the actuator 25 including the strain layer 17 is bent at a predetermined angle, and the upper portion of the upper electrode 19 of the actuator 25 is bent. The mounted mirror 29 is tilted by moving its axis by the curved upper electrode 19 to reflect light incident from the light source. The light reflected by the mirror 29 is projected onto the screen through the slit to form an image.

In the manufacturing method of the above-described thin film type optical path control apparatus, as shown in FIG. 3, when a mirror is deposited with a reflective metal such as aluminum or platinum using a sputtering method, stress generated in the mirror according to the deposition pressure The change of is represented by 'A', 'B' and 'C' part. In FIG. 3, the portion 'A' having a relatively low deposition pressure is a portion where the compressive stress is dominant, and the portion 'C' having a relatively high deposition pressure is a portion where the tensile stress is dominant. Therefore, when the mirror is formed under the pressures of the 'A' and 'C' portions, a problem arises in that the mirror is bent due to compressive stress or tensile stress occurring in the mirror. However, the 'B' part, which transitions from compressive stress to tensile stress, which is a relatively stress-free part during the deposition of the mirror, has a narrow range of deposition pressure, so it is accurately identified and the mirror is deposited under the pressure of the 'B' part. Difficult to make As a result, bending occurs in the mirror, which causes a problem that the light efficiency of the incident light falls.

Accordingly, it is an object of the present invention to provide a method of manufacturing a thin film type optical path control apparatus that can improve the light efficiency by preventing the mirror from bending by forming the mirror under a pressure that does not relatively stress the mirror.

1 is a cross-sectional view of a thin film type optical path adjusting device described in the applicant's prior application.

2A to 2D are manufacturing process diagrams of the apparatus shown in FIG. 1.

3 is a stress change diagram according to the deposition pressure of the metal deposition film.

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

FIG. 5 is a cross-sectional view taken along line D′ D ′ of the apparatus of FIG. 4. FIG.

6A to 6E are manufacturing process diagrams of the apparatus shown in FIG.

<Explanation of symbols for main parts of drawing>

100: active matrix 125: first metal layer

135: first protective layer 140: second metal layer

145: second protective layer 150: etch stop layer

155: first sacrificial layer 160: air gap

165 support layer 170 lower electrode

175 strain layer 180 upper electrode

185: Beer Hall 190: Beer Contact

195: lower electrode connecting member 200: common electrode line

205: upper electrode connecting member 210: actuator

215: second sacrificial layer 220: post

230: mirror

In order to achieve the object of the present invention described above, the present invention provides an active matrix comprising a first metal layer having a M x N (M, N is an integer) MOS transistor embedded therein and having a drain pad extending from the drain of the transistor. Providing a; After forming and patterning a first sacrificial layer on the active matrix, forming an actuator including forming a support layer, a lower electrode, a strain layer, and an upper electrode on the patterned first sacrificial layer. ; Forming a second sacrificial layer on top of the actuator and patterning the second sacrificial layer to expose a portion of the upper electrode; And depositing aluminum or silver on the exposed upper electrode and the second sacrificial layer by a sputtering method or a chemical vapor deposition method under a pressure of about 3 to 5 mTorr to form a mirror. Provide a method.

Therefore, according to the present invention, when depositing a reflective metal to form a mirror, it is possible to satisfy the stress free condition by depositing the metal under a pressure of about 3 to 5 mTorr, which is the portion of the transition from compressive stress to tensile stress have. In other words, by controlling the deposition pressure to minimize the stress on the metal constituting the mirror to prevent the bending of the mirror, thereby increasing the light efficiency of the light incident from the light source can be improved the image quality of the image projected on the screen eventually .

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

Figure 4 shows a plan view of the thin film type optical path control apparatus according to the present invention, Figure 5 shows a cross-sectional view of the device of Figure 4 cut along the line D'D '.

4 and 5, the thin film type optical path adjusting apparatus according to the present invention includes an active matrix 100, an actuator 210 formed on the active matrix 100, and a mirror 230 formed on the actuator 210. ).

The active matrix 100 is formed with an isolation layer 120 for dividing the active matrix 100 into an active region and a field region, and a gate 115, a source 110, and a drain 105 in the active region. M x N (M and N are integers) P-MOS transistors. In addition, the active matrix 100 is formed on the first metal layer 130 and the first metal layer 130 stacked on the MOS transistor and patterned to be connected to the source 110 and the drain 105, respectively. The first passivation layer 135, the second metal layer 140 formed on the first passivation layer 135, the second passivation layer 145 formed on the second metal layer 140, and the second passivation layer ( The etch stop layer 150 is formed on the upper portion of the 145.

The first metal layer 130 includes a drain pad extending from the drain 105 of the MOS transistor to transfer a first signal (image signal), and the second metal layer 140 includes a titanium (Ti) layer and titanium nitride. It consists of a (TiN) layer.

The actuator 210 has a support layer 165 in which one side is in contact with a portion in which the drain pad of the first metal layer 130 is formed below the etch stop layer 150, and the other side is horizontally formed through the air gap 160. , A lower electrode 170 formed on the support layer 165, a strained layer 175 formed on the lower electrode 170, an upper electrode 180 formed on the strained layer 175, and the strained layer ( One side of the first metal layer through the strained layer 175, the lower electrode 170, the support layer 165, the etch stop layer 150, the second protective layer 145, and the first protective layer 135 from one side of the 175. The via contact 190 is formed to connect the lower electrode 170 and the drain pad of the first metal layer 130 to each other in the via hole 185 vertically up to the drain pad of the 130.

The support layer 165 functions as a membrane supporting the actuator of the thin film type optical path adjusting device described in the previous application. Preferably, the support layer 165 has a 'T' shape, and the lower electrode 170 has a quadrangular shape and is formed on a central portion of the support layer 165. The strained layer 175 has a rectangular shape with a smaller area than the lower electrode 170, and the upper electrode 180 has a rectangular shape with a smaller area than the strained layer 175.

In addition, the actuator 210 is formed from the via contact 190 to the lower electrode 170 to connect the via contact 190 and the lower electrode 170 to the lower electrode connecting member 170 and the support layer 165. ) Includes a common electrode line 200 formed on an upper side of a 'T' shape head, and an upper electrode connecting member 205 connecting the upper electrode 180 and the common electrode line 200. The first signal is applied to the lower electrode 170 through the MOS transistor, the via contact 190, and the lower electrode connection member 195 embedded in the active matrix 100 from the outside. At the same time, a second signal (bias signal) is applied to the upper electrode 180 from the outside through the common electrode line 200 and the upper electrode connecting member 205.

The mirror 230 has a lower shape supported by a post 220 formed on one side of the upper electrode 200 and has a rectangular flat plate formed on both sides of the mirror 230.

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.

6a to 6e is a manufacturing process chart of the thin film type optical path control apparatus according to the present invention. Referring to FIG. 6A, after preparing an active matrix 100, which is an n-type doped silicon (Si) wafer, the active matrix 100 may be formed using a conventional device isolation process, for example, silicon partial oxidation (LOCOS). ) To form an isolation layer 120 for dividing the active region and the field region. Subsequently, a gate 115 made of a conductive material such as polysilicon doped with impurities is formed on the active region, and then p ⁺ source 110 and drain 105 are formed by an ion implantation process. N (M, N is an integer) P-MOS transistors are formed.

After forming the insulating layer 125 made of oxide on the top of the resultant P-MOS transistor is formed, openings for exposing the top of one side of the source 110 and the drain 105, respectively by a photolithography process. Subsequently, the first metal layer 130 is formed by depositing a metal such as titanium, titanium nitride, tungsten, or the like on the resultant material on which the openings are formed. The first metal layer 130 patterned as described above includes a drain pad extending from the drain 105 of the P-MOS transistor to an anchor 182 that is a support of the actuator 210.

A first protective layer 135 is formed on the first metal layer 130 to protect the active matrix 100 having the P-MOS transistor. The first passivation layer 135 is formed to have a thickness of about 8000 인 by depositing phosphorus silicate glass (PSG) by chemical vapor deposition (CVD).

A second metal layer 140 including a titanium layer and a titanium nitride layer is formed on the first passivation layer 135. The second metal layer 140 is formed by sputtering titanium (Ti) to form a titanium layer having a thickness of about 300 GPa, and then forming a titanium nitride layer on the titanium layer using physical vapor deposition (PVD). It is completed by forming. Since the light incident from the light source is incident not only to the mirror 230 but also to a portion other than the portion where the mirror 230 is formed, light leakage current flows into the active matrix 100 so that the device malfunctions. To prevent it. In addition, in consideration of a position where the via contact 190 is to be formed in a subsequent process, a portion of the second metal layer 140 formed on the drain pad of the first metal layer 130 is etched through the photolithography process to open the opening 143. By forming a portion of the first protective layer 135.

The second passivation layer 145 is formed on the exposed first passivation layer 135 and the second metal layer 140. The second passivation layer 145 is formed to have a thickness of about 2000 GPa using in-silicate glass (PSG). The second protective layer 145 prevents damage to the active matrix 100 and the results formed on the active matrix 100 during subsequent processing.

An etch stop layer 150 is formed on the second passivation layer 145. The etch stop layer 145 prevents the second protective layer 145 and the like from being etched and damaged by the subsequent etching process. The etch stop layer 150 is formed by depositing nitride by low pressure chemical vapor deposition (LPCVD) to have a thickness of about 1000 to 2000 kPa.

The first sacrificial layer 155 is formed on the etch stop layer 150. The first sacrificial layer 155 facilitates the stacking of thin films for forming the actuator 210, and is removed by hydrogen fluoride (HF) vapor after the stacking of the actuator 210 is completed. . The first sacrificial layer 155 is formed of phosphorous silicate glass (PSG) using an atmospheric pressure chemical vapor deposition (APCVD) method. It is formed to have a thickness of about 0㎛. In this case, since the first sacrificial layer 155 covers the top of the active matrix 100 in which the P-MOS transistor is embedded, the flatness of the surface thereof is very poor. Therefore, the first sacrificial layer 155 may be about 1.1 μm thick by using spin on glass (SOG) or chemical mechanical polishing (CMP). The surface of the substrate is ground by polishing. Subsequently, the actuator 210 may be exposed by etching a portion adjacent to a portion of the first sacrificial layer 155 formed below the opening 143 of the second metal layer 140 to expose a portion of the etch stop layer 150. Anchor 182 is formed to support the.

Referring to FIG. 6B, a first layer 164 is formed on the exposed etch stop layer 175 and on the first sacrificial layer 180. The first layer 164 is formed to have a thickness of about 0.01 to 1.0 탆 using a hard material such as nitride or metal. The first layer 164 is formed using a low pressure chemical vapor deposition (LPCVD) method. In this case, the stress inside the first layer 164 is controlled by forming the first layer 164 while changing the ratio of the reactive gas by time in the low pressure reaction vessel. The first layer 164 is later patterned into a support layer 165 having the shape of a 'T'.

After the first photoresist 167 is formed on the first layer 164 by using a spin coating method, the first photoresist 167 is patterned to form a lower portion of the first layer 164. The portion adjacent to the portion where the opening 143 of the second metal layer 140 is formed is exposed in a quadrangular shape along a direction orthogonal to the direction in which the drain pad of the first metal layer 130 is formed. After forming the lower electrode layer 169 on the exposed first layer 164 and on the first photoresist 167 by using a sputtering method or a chemical vapor deposition method, the common electrode line 200 is subsequently By patterning the lower electrode layer 169 in consideration of the position to be formed, the lower electrode 170 having a rectangular shape is formed on the exposed first layer 164. Accordingly, the lower electrode 170 is formed only on the center portion of the first layer 164. The lower electrode 170 may have a thickness of about 0.1 to 1.0 μm using a metal having electrical conductivity such as platinum (Pt), tantalum (Ta), or platinum-tantalum (Pt-Ta). Form.

A second layer 174 is formed on the lower electrode 170 and the first photoresist 167. The second layer 174 is a piezoelectric material ZrO ₂ , PZT or PLZT using a sol-gel, a sputtering method, or a chemical vapor deposition (CVD) method of 1.0. Preferably, it is formed to have a thickness of about 0.4 μm. Subsequently, the piezoelectric material constituting the second layer 174 is subjected to heat treatment using a rapid heat treatment (RTA) method to phase change. The second layer 174 is later patterned into the strained layer 175.

An upper electrode layer 179 is formed on the second layer 174. The upper electrode layer 179 is formed using aluminum (Al), platinum (Pt), or tantalum (Ta), which is a metal having electrical conductivity. The upper electrode layer 179 is formed to have a thickness of about 0.01 to 1.0 mu m using a sputtering method. The upper electrode layer 179 is patterned into an upper electrode 180 to which a second signal is later applied.

Referring to FIG. 6C, after the second photoresist (not shown) is coated on the upper electrode layer 179 by a spin coating method, the upper electrode layer 179 may be squared using the second photoresist as an etching mask. Patterned as the upper electrode 180 having a shape of. As a result, the upper electrode 180 is formed on the center of the first layer 164.

The second layer 174 is patterned into a strained layer 175 having a rectangular shape having a larger area than the upper electrode 180 using the same method as the patterning of the upper electrode layer 179. In this case, the strained layer 175 has a smaller area than the lower electrode 170 already formed. In addition, the first photoresist 167 is removed.

The first layer 164 is also patterned into the support layer 165 in the same manner as above. Unlike the shape of the lower electrode 170, the support layer 165 has a 'T' shape, and the lower electrode 170 is formed only on the center portion of the support layer 165. Next, the common electrode line 200 is formed on one side of the head portion of the 'T' of the support layer 165. That is, by applying and patterning a third photoresist (not shown) on the support layer 165 by spin coating, one side of the support layer 165 is exposed, and then platinum, tantalum, platinum-tantalum, aluminum, Alternatively, silver is used to form the common electrode line 200. The common electrode line 200 uses a sputtering method or a chemical vapor deposition method. It is formed to have a thickness of about 0㎛. In this case, the common electrode line 200 is spaced apart from the lower electrode 170 by a predetermined distance. Subsequently, the upper electrode connecting member 205 connecting the common electrode line 200 and the upper electrode 180 is formed using the same material and the same method as the common electrode line 200. Therefore, the common electrode connecting member 205 is spaced apart from the lower electrode 170 by a predetermined distance and does not contact the lower electrode 205.

In addition, when the third photoresist is patterned, a portion of the supporting layer 165 at which the opening 143 of the second metal layer 140 is formed is exposed at the same time. Subsequently, the via hole 185 is vertically etched from the support layer 165 to the drain pad of the first metal layer 130 by etching the etch stop layer 150, the second passivation layer 145, and the first passivation layer 135. After forming the via contact 204, a via contact 190 is formed from the drain pad to the support layer 165 in the via hole 185. At the same time, the lower electrode connecting member 195 is formed to be connected to the via contact 190 from the lower electrode 170 to the via hole 185. The via contact 190 and the lower electrode connecting member 195 form platinum, tantalum, or platinum-tantalum, which is a metal having electrical conductivity, using a sputtering method or a chemical vapor deposition method. In this case, the lower electrode connecting member 195 is 0.5 to 1. It is formed to have a thickness of about 0㎛. Accordingly, the first signal is externally connected to the lower electrode 170 through the MOS transistor embedded in the active matrix 100, the drain pad of the first metal layer 130, the via contact 190, and the lower electrode connecting member 195. Is applied to. The third photoresist and the first sacrificial layer 155 may be removed to form an actuator 210 including an upper electrode 180, a deformation layer 175, a lower electrode 170, and a support layer 165. do.

Referring to FIG. 6D, as described above, the first sacrificial layer 155 is removed to form the second sacrificial layer 215 using a polymer having fluidity on the actuator 210 having the air gap 160 formed thereon. do. The second sacrificial layer 215 is formed using a spin coating method to completely cover the upper electrode 180 while filling the air gap 160. Subsequently, one side of the upper electrode 180 is exposed by patterning the second sacrificial layer 215 in consideration of the position where the post 220 of the mirror 230 is to be formed.

Referring to FIG. 6E, aluminum, platinum, or silver, which is a reflective metal, is disposed on one side of the exposed upper electrode 180 and on the second sacrificial layer 215 by using a sputtering method or a chemical vapor deposition method. The deposition forms the mirror 230 and the post 220 at the same time. At this time, the deposition pressure of the reflective metal is adjusted to about 3 to 5 mTorr, which produces relatively less compressive stress and tensile stress, so that the metal is about 0.01 to 1. It is to be deposited with a thickness of about 0㎛. That is, in the graph shown in FIG. 3, the mirror 230 is controlled by controlling the deposition pressure by depositing the metal under a pressure range of 3 to 5 mTorr, which is a pressure range of the 'B' portion, which is a portion that transitions from compressive stress to tensile stress. It is possible to minimize the stress on the metal constituting. Accordingly, by preventing the mirror 230 from bending, the horizontal degree of the mirror 230 may be improved to increase the light efficiency of light incident from the light source.

Subsequently, after the mirror 230 is patterned to have a rectangular shape, the second sacrificial layer 215 is removed using an oxygen plasma, cleaned, and dried to complete the thin film type optical path control device.

In the above-described thin film type optical path control apparatus according to the present invention, the first signal transmitted from the outside is lowered through the MOS transistor embedded in the active matrix 100, the drain pad of the first metal layer 130, and the via contact 190. Is applied to the electrode 170. At the same time, a second signal is applied to the upper electrode 180 from the outside to generate an electric field according to the potential difference between the upper electrode 180 and the lower electrode 170. Due to this electric field, the deformation layer 175 formed between the upper electrode 180 and the lower electrode 170 causes deformation. The strained layer 175 contracts in a direction orthogonal to the electric field, whereby the actuator 210 is bent at a predetermined angle. Since the mirror 230 is formed on the actuator 210, the mirror 230 is tilted at the same angle as the actuator 210. Therefore, the mirror 230 reflects the light incident from the light source at a predetermined angle, and the reflected light passes through the slit and is projected onto the screen to form an image.

According to the present invention, when depositing a reflective metal to form a mirror, it is possible to satisfy the stress free condition by depositing the metal under a pressure of about 3 to 5mTorr, which is a part of transition from compressive stress to tensile stress. In other words, by controlling the deposition pressure to minimize the stress on the metal constituting the mirror to prevent the bending of the mirror, thereby increasing the light efficiency of the light incident from the light source can be improved the image quality of the image projected on the screen eventually .

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 a drain pad extending from the drain of the transistor; After forming and patterning a first sacrificial layer on the active matrix, forming an actuator including forming a support layer, a lower electrode, a strain layer, and an upper electrode on the patterned first sacrificial layer. ; Forming a second sacrificial layer on top of the actuator and patterning the second sacrificial layer to expose a portion of the upper electrode; And And depositing aluminum or silver on the exposed upper electrode and the second sacrificial layer by a sputtering method or a chemical vapor deposition method under a pressure of about 3 to 5 mTorr to form a mirror. Method of manufacturing the device.