KR20000004787A - Method for manufacturing a thin film actuated mirror array - Google Patents

Abstract

PURPOSE: A method for manufacturing a thin film actuated mirrors array in an optical projection system is provided to improve a light efficiency of a mirror and a quality of an image projected on a screen by minimizing a bend of a mirror occurred due to a stress. CONSTITUTION: The method for manufacturing a thin film actuated mirrors array comprising the steps of: providing an active matrix (200) including a first metal layer (235), which a MOS transistor is built-in and a drain pad extending from a drain of the transistor; forming and patterning a first sacrificial layer (260) onto the active matrix; forming a first layer (240), a lower electrode layer (300), a second layer (250), and a upper electrode layer (301) on the active matrix; forming a actuator (310) including a lower electrode layer, a first and a second deformable layers (290, 291) and a first and a second upper electrodes(300,301) by patterning the upper electrode layer, the second layer and the lower electrode layer; forming a supporter (275) including a support line, a support layer, a first anchor and a second anchor by patterning the first layer; and forming a second sacrificial layer(400) onto the supporter and the actuator; forming a photoresist and a hard mask (420) onto the second sacrificial layer and then patterning the second sacrificial layer using the photoresist and the hard mask; depositing a mirror(360) by depositing an aluminum on the patterned second sacrificial layer and the hard mask.

Description

Manufacturing method of thin film type optical path control device

The present invention relates to a method for manufacturing a thin film type optical path control device using an Actuated Mirror Array (AMA), and more particularly, to a thin film type optical path control device capable of improving image quality of an image projected on a screen by improving the flatness of a mirror. It relates to a manufacturing method.

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. Typically, image processing apparatuses using such optical modulators are classified 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 in the range of 1-2% and requires 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.

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 control device cuts a thin layer of multilayer ceramic, mounts a ceramic wafer having a metal electrode therein in an active matrix including a transistor, and then processes it using a sawing method and mirrors the upper portion thereof. By installing. However, the bulk optical path control device requires very high precision in design and manufacturing, and has a disadvantage in that the response of the strained layer is slow.

Accordingly, a thin film type optical path control apparatus that can be manufactured using a semiconductor manufacturing process has been developed. Such a thin film type optical path control device is disclosed in Korean Patent Application No. 98-16545 (name of the invention: thin film type optical path control device and its manufacturing method) filed by the applicant of the Korean Patent Office on May 8, 1998.

FIG. 1 shows a perspective view of a thin film type optical path adjusting device described in the above prior application, and FIG. 2 shows a cross-sectional view of the device of FIG. 1 taken along line A ₁ -A ₂ .

Referring to FIG. 1, the thin film type optical path adjusting device includes an active matrix 11, a support element 75 formed on the active matrix 11, and first and second sides formed side by side on the support element 75. Actuating unit (110, 111), and the mirror 160 formed on the first and second actuating unit (110, 111).

Referring to FIG. 2, the active matrix 11 includes a substrate 1 in which M × N (M, N is a natural number) MOS transistors 20 and a drain pad extending from the drain of the MOS transistors. The first protective layer 40 stacked on the first metal layer 35, the substrate 1, and the first metal layer 35, the second metal layer 45 formed on the first protective layer 40, and the first metal layer 35. The second protective layer 50 formed on the upper portion of the second metal layer 45 and the etch stop layer 55 stacked on the second protective layer 50 are included.

Referring to FIG. 1, the support element 75 is integrally formed with the support line 74 and the support line 74 formed through the first air gap 65 on the active matrix 11 and has a rectangular ring shape. First anchor 71 and second anchors respectively attached to the support layer 73 of the support layer 73 and the etch stop layer 55 below the portion adjacent to the support line 74 of the support layer 73 to support the support layer 73. 72a, 72b).

Referring to FIG. 2, the first and second actuating parts 110 and 111 may have a quadrangle on top of two arms of the support layer 73 extending horizontally in a direction orthogonal to the support line 74, respectively. It is formed parallel to each other in the shape of. The first actuating part 110 includes a first lower electrode 80, a first deformable layer 90, and a first upper electrode 100, and the second actuating part 111 includes a second lower electrode ( 81, a second strained layer 91, and a second upper electrode 101.

The mirror 160 formed on the first and second actuating parts 110 and 111 is supported by a central part by the post 150, and both sides of the mirror 160 are provided by the first and second actuating parts through the second air gap 170. It is formed horizontally on the upper portion of the gating portion (110, 111).

Hereinafter, a method of manufacturing the above-described thin film type optical path control apparatus will be described with reference to the drawings.

3A to 3D are views for explaining a method of manufacturing the apparatus shown in FIGS. 1 and 2. Referring to FIG. 3A, after forming a separator 25 for separating an active region and a field region using a silicon partial oxidation method (LOCOS) on a substrate 1 which is an n-type doped silicon wafer, the active region is formed on the active region. The gate 15 made of polysilicon is formed on the substrate, and the p ⁺ source 10 and the drain 5 are formed by an ion implantation process, whereby M x N (M, N is a natural number) P − The MOS transistor 20 is formed.

After the insulating film is formed on the substrate 1 on which the P-MOS transistor 20 is formed, openings are formed to expose the upper portions of one side of the source 10 and the drain 5 by photolithography. Subsequently, a metal layer made of titanium, titanium nitride, tungsten, nitride, or the like is deposited and patterned on the upper portion of the resultant product formed with the openings, and extends from the drain 5 of the MOS transistor 20 to the bottom of the first anchor 71. The first metal layer 35 including the drain pad is formed.

A first protective layer 40 having a thickness of about 8000 kPa is formed on the first metal layer 35 and the substrate 1 by phosphorus silicate glass PSG by chemical vapor deposition (CVD). The first protective layer 140 prevents damage to the substrate 1 in which the transistor 20 is embedded during the subsequent process.

A second metal layer 145 including a titanium layer and a titanium nitride layer is formed on the first protective layer 40. The titanium layer is formed to have a thickness of 300 kW by the sputtering method, and the titanium nitride layer is formed to have a thickness of 1200 kW using 1200 kW by the physical vapor deposition method (PVD). The second metal layer 45 prevents the device from malfunctioning due to photocurrent flowing through the active matrix 11 due to incident light. Subsequently, a portion of the second metal layer 45 where the via hole 120 is to be formed later is etched to form holes (not shown) in the second metal layer 45.

On the upper part of the second metal layer 45, a second protective layer 50 having a thickness of 2000 kPa is deposited on the silicate glass PSG by chemical vapor deposition. The second protective layer 50 prevents the substrate 1 and the resulting products formed on the substrate 1 from being damaged during subsequent processing.

An etch stop layer 55 is stacked on the second passivation layer 50 to prevent the second passivation layer 150 and the products on the substrate 1 from being etched during the subsequent etching process. The etching prevention layer 55 is a low-temperature oxide (LTO) such as silicon oxide (SiO ₂ ) or phosphorus pentoxide (P ₂ O ₅ ) at a temperature of 350 to 450 ° C. using a low pressure chemical vapor deposition (LPCVD) method. It is formed to have a thickness of μm.

The first sacrificial layer 60 having a thickness of 2.0 to 3.0 μm is deposited on the etch stop layer 55 by low pressure chemical vapor deposition (LPCVD). Subsequently, the surface of the first sacrificial layer 60 is polished using a chemical mechanical polishing (CMP) method to planarize the surface of the first sacrificial layer 60 to have a thickness of about 1.1 μm.

Subsequently, after applying and patterning a first photoresist (not shown) on the top of the first sacrificial layer 60, the second photoresist is used as a mask to form a second bottom of the first sacrificial layer 60. The first anchor 71 and the second anchors supporting the supporting layer 70 to be formed later by etching the portion where the hole of the metal layer 45 and the portions adjacent to both sides are etched to expose a portion of the etch stop layer 55. The positions 72a and 72b are to be formed and the first photoresist is removed. Accordingly, the etch stop layer 55 is exposed in the shape of three squares spaced apart by a predetermined distance.

Referring to FIG. 3B, the first layer 69 is stacked on the etch stop layer 55 and the first sacrificial layer 60 exposed in the quadrangular shape. The first layer 69 is formed to have a thickness of 0.1 to 1.0 mu m by low pressure chemical vapor deposition (LPCVD).

The lower electrode layer 79 is stacked on top of the first layer 69. The lower electrode layer 79 is formed to have a thickness of 0.1 to 1.0 μm by sputtering or chemical vapor deposition of metals such as platinum (Pt), tantalum (Ta), or platinum-tantalum (Pt-Ta).

A second layer 89 made of a piezoelectric material such as PZT or PLZT is stacked on the lower electrode layer 79. The second layer 89 is formed by spin coating PZT prepared by the sol-gel method to have a thickness of about 0.4 μm, and then heat-treating the piezoelectric material constituting the second layer 89 by rapid thermal treatment (RTA). Phase change

The upper electrode layer 99 is formed to have a thickness of 0.1 to 1.0 μm by sputtering or chemical vapor deposition of a metal such as platinum, tantalum, silver (Ag), or platinum-tantalum of the second layer 89.

Referring to FIG. 3C, after applying and patterning a second photoresist (not shown) on the upper electrode layer 99, each of the upper electrode layers 99 is formed in a rectangular flat plate using the second photoresist as a mask. The first and second upper electrodes 100 and 101 are formed side by side and separated by a predetermined distance, and the second photoresist is removed. A second signal (image signal) is applied to the first and second upper electrodes 100 and 101 through the common electrode line 140 formed later from the outside, respectively.

Subsequently, the second layer 89 is patterned in the same manner as the patterning of the upper electrode layer 99 to form a rectangular flat plate, and each of the first and second strained layers 90 formed side by side by a predetermined distance is formed. 91). The first strained layer 80 is caused by the first electric field generated between the first upper electrode 100 and the first lower electrode 80, and the second strained layer 81 is the second upper electrode 101. And the second electric field generated between the second lower electrode 81 and the second lower electrode 81.

Subsequently, the lower electrode layer 79 is patterned by the above-described method to form first and second lower electrodes 80 and 81, each having a rectangular flat plate shape and spaced apart by a predetermined distance. In addition, when the lower electrode layer 79 is patterned, the common electrode line 140 is first and second in a direction perpendicular to the first and second lower electrodes 80 and 81 on one side of the first layer 69. It is formed simultaneously with the lower electrodes 80 and 81. The common electrode line 140 is formed on the support line 74 formed later, and is spaced apart from the first and second lower electrodes 80 and 81 by a predetermined distance. Accordingly, the first actuating part 110 including the first upper electrode 100, the first strained layer 90, and the first lower electrode 80, the second upper electrode 101, and the second strained layer ( The second actuating part 111 including the second lower electrode 81 and the second lower electrode 81 is completed.

The first layer 69 is patterned with a support element 75 comprising a support layer 73, a support line 74, a first anchor 71 and second anchors 72a, 72b. At this time, both sides of the portion of the first layer 69 contacting the etch stop layer 55 exposed in the three quadrangles are second anchors 72a and 72b, and the center portion of the first anchor 69 is do. The first anchor 71 and the second anchors 72a and 72b each have a rectangular box shape, and a drain pad is formed under the first anchor 71.

Subsequently, a third photoresist (not shown) is applied on the support element 75 and the first and second actuators 110 and 111 and patterned to form a common electrode line formed on the support line 74. A portion of the first and second upper electrodes 100 and 101 is exposed from 140. At this time, a part of the first and second lower electrodes 80 and 81 are also exposed together from the first anchor 71.

The first strained layer 90 and the first lower electrode 80 are formed from a portion of the first upper electrode 100 by depositing and patterning amorphous silicon or low temperature oxide silicon oxide or phosphorus pentoxide on the exposed portion. The first insulating layer 130 is formed up to a part of the support layer 73, and at the same time, the support layer is formed through the second strained layer 91 and the second lower electrode 81 from a part of the second upper electrode 101. The second insulating layer 131 is formed up to a part of 73. The first and second insulating layers 130 and 131 are formed to have a thickness of 0.2 to 0.4 µm, respectively, by low pressure chemical vapor deposition (LPCVD).

Subsequently, a portion of the first anchor 71, the etch stop layer 55, the second passivation layer 50, and the first passivation layer 40 are formed from a central upper portion of the first anchor 71, which is a portion where the drain pad is formed below. To form a via hole 120 to a drain pad, and then form a via contact 125 in the via hole 120, and form the first and second lower electrodes 80 and 81 from the via hole 120. ) To form first and second lower electrode connection members 188 and 189, respectively. At the same time, the first and second upper electrode connecting members 180 and 181 are formed from the first and second upper electrodes 100 and 101 to the common electrode line 140, respectively.

The via contact 125, the first and second lower electrode connecting members 188 and 189, and the first and second upper electrode connecting members 180 and 181 are respectively sputtered platinum or platinum-tantalum. After the deposition to have a thickness of 0.1 ~ 0.2㎛ by the deposition method, the deposited metal is formed by patterning. The first and second upper electrode connecting members 180 and 181 connect the first and second upper electrodes 100 and 101 to the common electrode line 140, respectively. The first lower electrode 80 is connected to the drain pad through the first lower electrode connecting member 188 and the via contact 125, and the second lower electrode 81 is connected to the second lower electrode connecting member 189 and the via. It is connected with the drain pad through the contact 125.

Referring to FIG. 3D, a second sacrificial layer 165 is formed using a fourth photoresist on the first and second actuating portions 110 and 111 and the support element 75. Subsequently, by patterning the second sacrificial layer 165 to form the mirror 160 and the post 150, the second sacrificial layer 165 is formed in parallel without being adjacent to the support line 74 of the support layer 70 having the shape of the rectangular ring. Expose part of the part.

Next, aluminum (Al) is deposited on the exposed support layer 70 and the second sacrificial layer 165 using a sputtering method or a chemical vapor deposition method, and the deposited metal is patterned to form a rectangular plate. The mirror 160 and the post 150 for supporting the mirror 160 are formed at the same time. In this case, the aluminum is deposited at a rate of about 110 sccm under room temperature and argon (Ar) gas atmosphere. In addition, the deposition pressure at this time is maintained at about 2.5mTorr.

Then, the second sacrificial layer 165 and the first sacrificial layer 60 are removed, and cleaning and drying are performed to complete the AMA device as shown in FIG. 1. As described above, when the second sacrificial layer 165 is removed, the second air gap 170 is formed at the position of the second sacrificial layer 165, and when the first sacrificial layer 60 is removed, the first sacrificial layer 60 is removed. The first air gap 65 is formed at the position of.

However, in the manufacturing method of the above-described thin film type optical path control apparatus, the process conditions for depositing aluminum on top of the second sacrificial layer to form a mirror are generated during deposition of aluminum on top of the second sacrificial layer. Stress causes a problem in that both ends of the mirror are bent upwards. When both sides of the mirror are bent upward, interference of incident light occurs near the curved portion of the mirror, resulting in a decrease in the light efficiency of the mirror, which results in deterioration of the image quality of the image projected on the screen.

Accordingly, it is an object of the present invention to provide a method of manufacturing a thin film type optical path control apparatus which can form a flat mirror without warpage, thereby improving the optical efficiency of the mirror and improving the image quality of the image projected on the screen.

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

FIG. 2 is a cross-sectional view of the apparatus shown in FIG. _{1 taken along} lines A ₁ -A ₂ .

3A to 3D are manufacturing process diagrams of the apparatus shown in FIG. 2.

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

5 is a cross-sectional view of the apparatus of FIG. 4 taken along line B ₁ -B ₂ .

6A to 6E are manufacturing process diagrams of the apparatus shown in FIGS. 4 and 5.

<Explanation of symbols for main parts of the drawings>

200: active matrix 201: substrate

220: transistor 235: first metal layer

240: first protective layer 245: second metal layer

250: second protective layer 255: etch stop layer

260: first sacrificial layer 270: support layer

271: first anchor 272a and 272b: second anchor

274 support line 275 support element

280: lower electrode 290, 291: first and second strained layers

300, 301: first and second upper electrodes 310: actuator

320, 321: first and second insulating layers

330 and 331: first and second upper electrode connecting members

350: Post 360: Mirror

370: Beer Hall 380: Beer Contact

400: second sacrificial layer 420: hard mask

According to the manufacturing method of the thin film type optical path control apparatus according to the present invention in order to achieve the above object of the present invention, the upper portion of the active matrix including a first metal layer having a MOS transistor embedded and extending from the drain of the transistor After forming and patterning a first sacrificial layer on the substrate, a first layer, a lower electrode layer, a second layer, and an upper electrode layer are formed on the first sacrificial layer. Patterning the upper electrode layer, the second layer and the lower electrode layer to form an actuator including a lower electrode, a first strained layer, a second strained layer, a first upper electrode, and a second upper electrode, and then the first layer Is patterned to form a support line, a support layer and a support means comprising first and second anchors. A photoresist and a hard mask are formed on the second sacrificial layer to form a second sacrificial layer on the support means and the actuator, and to form a mirror and a post. After patterning the second sacrificial layer, a mirror is formed on the hard mask using aluminum.

According to the manufacturing method of the thin film type optical path control apparatus according to the present invention, after forming a photoresist and a hard mask on the second sacrificial layer to pattern the second sacrificial layer, aluminum is formed on the top of the hard mask to form a mirror. When formed in, it is possible to minimize the stress generated in the mirror through the improvement of the deposition process conditions of aluminum, it is possible to form a flat mirror without bending. Accordingly, the light efficiency of the mirror can be improved, and the image quality of the image projected on the screen can be improved.

Hereinafter, a thin film type optical path adjusting apparatus according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

Figure 4 shows a perspective view of a 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 B ₁ -B ₂ .

4 and 5, the thin film type optical path adjusting device according to the present invention includes an active matrix 200, a support element 275 formed on the active matrix 200, and an actuator formed on the support element 275. 310, and a mirror 360 formed on the actuator 310.

The active matrix 200 includes a substrate 201 in which M × N (M, N is a natural number) P-MOS transistors 220, a drain 205 and a source of the P-MOS transistors 220. A first metal layer 235 formed above the substrate 201, a first passivation layer 240 formed on the first metal layer 235, and a first passivation layer 240 formed on the first metal layer 235. The second metal layer 245, the second protective layer 250 formed on the second metal layer 245, and the etch stop layer 255 formed on the second protective layer 250 are included.

The first metal layer 235 includes a drain pad extending from the drain 205 of the P-MOS transistor 220 to transmit a first signal (image signal), and the second metal layer 245 includes a titanium layer and nitride. It consists of a titanium layer.

Referring to FIG. 4, the support element 275 includes a support line 274, a support layer 270, a first anchor 271 and second anchors 272a, 272b. The support line 274 and the support layer 270 are horizontally formed on the etch stop layer 255 through the first air gap 265. The common electrode line 340 is formed on the support line 274, and the support line 274 functions to support the common electrode line 340.

The support layer 270 has a rectangular ring shape, preferably a rectangular ring shape, and is integrally formed with the support line 274 in a direction orthogonal to the support line 274 in the same plane. A first anchor 271 is integrally formed with the two arms in a lower portion between two arms horizontally extending in a direction orthogonal to the support line 274 of the rectangular ring-shaped support layer 270 to form an etch stop layer ( 255, and two second anchors 272a and 272b are formed integrally with the two arms at an outer lower portion of the two arms and attached to the etch stop layer 255. The first anchor 271 and the second anchors 272a and 272b each have a rectangular box shape.

The support layer 270 is centrally supported by the first anchor 271, and both sides are supported by the second anchors 272a and 272b, so that the support layer 270 and the first and second anchors 271, 272a, The cross section of 272b) has a shape of 'T' as shown in FIG.

The first anchor 271 is formed on a portion of the etch stop layer 255 where the drain pad of the first metal layer 235 is formed. In the central portion of the first anchor 271, the first metal layer may be formed through the etch stop layer 255, the second passivation layer 250, the holes (not shown) of the second metal layer 245, and the first passivation layer 240. The via hole 370 is formed to the drain pad of 235.

The actuator 310 has a mirror-shaped 'c' shape with respect to the support line 274 and is formed on the support layer 270. The actuator 310 includes a lower electrode 280, a first strained layer 290, a second strained layer 291, a first upper electrode 300, and a second upper electrode 301. The lower electrode 280 has a mirror-shaped 'c' shape spaced apart from the support line 274 by a predetermined distance, and protrudes stepped toward the first anchor 271 on one side of the lower electrode 280. Are formed corresponding to each other. The protrusions of the lower electrode 280 extend to the circumference of the via hole 370 formed in the first anchor 271, respectively.

The via contact 380 is formed from the drain pad to the protrusion of the lower electrode 280 through the via hole 380 to electrically connect the drain pad and the lower electrode 280.

The two arms of the mirror-shaped 'c' shaped lower electrode 280 each have the shape of a rectangular flat plate, and the first and second deformable layers 290 and 291 are respectively more than two arms of the lower electrode 280. It has a narrow rectangular plate shape and is formed on top of two arms of the lower electrode 280. In addition, the first and second upper electrodes 300 and 301 have a shape of a rectangular plate having a smaller area than the first and second deformable layers 290 and 291, respectively, and the first and second deformable layers 290 and 291. It is formed at the top of the.

The first insulating layer 320 is formed from one side of the first upper electrode 300 to a part of the support layer 270 through the first strained layer 290 and the lower electrode 280, and the first upper electrode 300. The first upper electrode connecting member 330 is formed from one side of the second electrode to a common electrode line 340 through a portion of the first insulating layer 320 and the support layer 270. The first upper electrode connecting member 330 connects the first upper electrode 300 and the common electrode line 340 to each other, and the first insulating layer 320 may include the first upper electrode 300 and the lower electrode 280. It is connected to each other to prevent electrical shorts.

In addition, a second insulating layer 321 is formed from one side of the second upper electrode 301 to a part of the support layer 270 through the second deformable layer 291 and the lower electrode 280. The second upper electrode connecting member 331 is formed from one side of the second upper electrode 301 to the common electrode line 340 through a portion of the second insulating layer 321 and the support layer 270. The second insulating layer 321 and the second upper electrode connecting member 331 are formed to be parallel to the first insulating layer 320 and the first upper electrode connecting member 330, respectively. The second upper electrode connecting member 331 connects the second upper electrode 301 and the common electrode line 340 to each other, and the second insulating layer 321 is formed by the second upper electrode 301 and the lower electrode 280. They are connected to each other to prevent electrical shorts.

The mirror 360 is formed on a portion of the mirror-shaped lower electrode 280 in which the first and second upper electrodes 300 and 301 are not formed, that is, a portion formed parallel to the support line 274. Posts 350 are formed. The mirror 360 is centrally supported by the post 350, and both sides thereof are horizontally formed on the upper portion of the actuator 310 via the second air gap 410. A hard mask 420 is formed below the mirror 360 to accurately pattern the post 350. The mirror 360 reflects light incident from a light source (not shown) at a predetermined angle so that the image is projected onto the screen.

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 are diagrams for describing a method of manufacturing the apparatus shown in FIGS. 4 and 5. In Figs. 6A to 6E, the same reference numerals are used for the same members as Figs. 4 and 5.

Referring to FIG. 6A, a device isolation layer 225 is formed on an n-type doped silicon wafer by using a silicon partial oxidation method (LOCOS), which is a conventional device isolation process. do. Subsequently, a gate 215 made of a conductive material such as polysilicon doped with impurities is formed on the active region, and then p ⁺ source 210 and drain 205 are formed using an ion implantation process. M × N (M and N are natural numbers) P-MOS transistors 220 are formed on the substrate 201.

After the insulating film 230 made of oxide is formed on the P-MOS transistor 220 formed thereon, the source 210 and one side of the drain 205 of the transistor 220 are respectively formed by a photolithography method. Form openings that expose. Subsequently, after depositing a first metal layer 235 made of titanium, titanium nitride, tungsten, nitride, or the like on the resultant, the first metal layer 235 is patterned by photolithography. The patterned first metal layer 235 includes a drain pad extending from the drain 205 of the P-MOS transistor 220 to the bottom of the first anchor 271 supporting the support layer 270.

The first passivation layer 240 is stacked on the substrate 201 where the first metal layer 235 and the transistor 220 are formed. The first passivation layer 240 is formed to have a thickness of about 8000 GPa by chemical vapor deposition (CVD) using phosphorus silicate glass (PSG). The first protective layer 240 prevents the substrate 201 having the P-MOS transistor 220 from being damaged due to a subsequent process.

The second metal layer 245 is formed on the first passivation layer 240. The second metal layer 245 is composed of a titanium layer and a titanium nitride layer. The titanium layer is formed to a thickness of about 300 kW using a sputtering method, and the titanium nitride layer is formed to have a thickness of about 1200 kW using a physical vapor deposition method (PVD) on top of the titanium layer. Since the light incident from the light source (not shown) is incident on the second metal layer 245 not only to the mirror 360 but also to a portion other than the portion covered by the mirror 360, a light leakage current is generated in the active matrix 200. (photo leakage current) flows to prevent the device from malfunctioning. Subsequently, a portion of the second metal layer 245 in which the via hole 370 is to be formed in a subsequent process, that is, a portion in which the drain pad of the first metal layer 235 is formed is etched to the second metal layer 245. Form a hole (not shown).

The second passivation layer 250 is stacked on the second metal layer 245. The second passivation layer 250 is formed of a silicate glass (PSG) to have a thickness of about 2000 kPa using a chemical vapor deposition method. The second protective layer 250 prevents damage to the substrate 201 and the products formed on the substrate 201 during subsequent processing.

An etch stop layer 255 is stacked on the second passivation layer 250. The etch stop layer 255 prevents the second passivation layer 250 and the products on the substrate 201 from being etched and damaged during the subsequent etching process. The etch stop layer 255 is formed using a low temperature oxide (LTO) such as silicon oxide (SiO ₂ ) or phosphorus pentoxide (P ₂ O ₅ ). The etch stop layer 255 is formed to have a thickness of about 0.2 to 0.8 μm at a temperature of about 350 to 450 ° C. using a low pressure chemical vapor deposition (LPCVD) method. Accordingly, the substrate 201, the first metal layer 235, the first protective layer 240, the second metal layer 245, the second protective layer 250, and the etch stop layer 255 having the transistor 220 built therein may be disposed. The active matrix 200 is completed.

The first sacrificial layer 260 is stacked on the etch stop layer 255. The first sacrificial layer 260 serves to facilitate stacking of the thin films constituting the actuator 310. The first sacrificial layer 260 is formed to have a thickness of about 2.0 to 3.0 μm by using a low pressure chemical vapor deposition (LPCVD) method at a temperature of about 500 ° C. or less. Subsequently, the surface of the first sacrificial layer 260 is polished using a chemical mechanical polishing (CMP) method to planarize the surface of the first sacrificial layer 260 to have a thickness of about 1.1 μm.

6B is a plan view illustrating a state in which the first sacrificial layer 260 is patterned. 6A and 6B, after applying and patterning a first photoresist (not shown) on the first sacrificial layer 260, the first sacrificial layer (using the first photoresist as a mask) The first anchor supporting the support layer 270 formed later by etching a portion of the second metal layer 245 formed at a lower portion of the second metal layer 245 and portions adjacent to both sides thereof to expose a portion of the etch stop layer 255. 271 and where the second anchors 272a, 272b are to be formed. Accordingly, the etch stop layer 255 is exposed in the shape of three squares spaced apart by a predetermined distance. Then, the first photoresist is removed.

Referring to FIG. 6C, the first layer 269 is stacked on the upper portion of the etch stop layer 255 and the first sacrificial layer 260 exposed in the shape of a rectangle as described above. The first layer 269 is formed of a hard material such as nitride or metal to have a thickness of about 0.1 to 1.0 μm by low pressure chemical vapor deposition (LPCVD). The first layer 269 is later patterned with a support element 275 comprising a support layer 270, a support line 274 and anchors 271, 272a, 272b.

The lower electrode layer 279 is stacked on top of the first layer 269. The lower electrode layer 279 is formed of a metal having electrical conductivity such as platinum, tantalum or platinum-tantalum to have a thickness of about 0.1 to 1.0 μm using a sputtering method or a chemical vapor deposition method. The lower electrode layer 279 is subsequently applied with a first signal (image signal) from the outside, and is patterned into a mirror-shaped 'c' shaped lower electrode 280 having stepped protrusions formed on one side thereof.

The second layer 289 is formed on the lower electrode layer 279 using a piezoelectric material such as PZT or PLZT. Preferably, the second layer 289 is formed by spin coating PZT prepared by the sol-gel method to have a thickness of about 0.4 μm. Subsequently, the piezoelectric material constituting the second layer 289 is subjected to heat treatment by a rapid heat treatment (RTA) method to perform phase change. The second layer 289 may be formed by the first strained layer 290 and the second upper electrode 301 and the lower portion, which are later deformed by a first electric field generated between the first upper electrode 300 and the lower electrode 280. The second strained layer 291 is patterned by the second electric field generated between the electrodes 280.

The upper electrode layer 299 is stacked on top of the second layer 289. The upper electrode layer 299 is formed to have a thickness of about 0.1 μm to 1.0 μm using a sputtering method or a chemical vapor deposition method on an electrically conductive metal such as platinum, tantalum, silver, or platinum-tantalum. The upper electrode layer 299 is later patterned with a first upper electrode 300 and a second upper electrode 301 which are each applied with a second signal (bias signal) and are spaced apart by a predetermined distance.

Referring to FIG. 6D, after applying and patterning a second photoresist (not shown) on the upper electrode layer 299, the upper electrode layer 299 may be squared using the second photoresist as a mask. The first upper electrode 300 and the second upper electrode 301 have a shape of a flat plate, preferably a rectangular flat plate, and are formed to be spaced apart from each other by a predetermined distance. The second signal is applied to the first upper electrode 300 and the second upper electrode 301 through a common electrode line 340 formed later from outside. Then, the second photoresist is removed.

Subsequently, the second deforming layer 290 is patterned in the same manner as the method of patterning the upper electrode layer 299, each having a shape of a rectangular flat plate, and separated from each other by a predetermined distance to form a first deformable layer 290. And a second strained layer 291. In this case, as shown in FIG. 5, the first strained layer 290 and the second strained layer 291 may be formed of rectangular plates having a slightly larger area than the first upper electrode 300 and the second upper electrode 301, respectively. Patterned to have a shape.

Subsequently, the lower electrode layer 279 is patterned in the same manner as the patterning of the upper electrode layer 299 to have a mirror-shaped 'c' shape for the supporting line 274 formed later, and the first anchor 271 may be formed. Toward the bottom electrode 280 having protrusions formed in a stepped manner. In this case, the two arms of the lower electrode 280 have the shape of a rectangular plate having a larger area than the first strained layer 290 and the second strained layer 291, respectively.

In addition, when the lower electrode layer 279 is patterned, the common electrode line 340 is formed simultaneously with the lower electrode 280 in a direction perpendicular to the lower electrode 280 on one side of the first layer 269. The common electrode line 340 is formed to be spaced apart from the lower electrode 280 by a predetermined distance on the support line 274 formed later. Accordingly, the actuator 310 including the first and second upper electrodes 300 and 301, the first and second strained layers 290 and 291, and the lower electrode 280 is completed.

Subsequently, the first layer 269 is patterned to form a support element 275 comprising a support layer 270, a support line 274, a first anchor 271 and second anchors 272a and 272b. . At this time, both sides of the portion of the first layer 269 contacting the etch stop layer 255 exposed in the shape of the three quadrangles become second anchors 272a and 272b, and the center portion of the first anchor 271 ) Each of the first anchor 271 and the second anchors 272a and 272b has a rectangular box shape, and a hole of the second metal layer 245 and a hole of the first metal layer 235 are disposed below the first anchor 271. A drain pad is formed.

The first strained layer 290 and the second strained layer 291 are each formed side by side on two arms horizontally extending in a direction orthogonal to the support line 274 of the support layer 270. Accordingly, the first anchor 271 is formed below the mirror-shaped 'c' shaped lower electrode 280, and the second anchors 272a and 272b are formed below the outer electrode 280, respectively. do.

Subsequently, a support line 274 is applied by applying and patterning a fourth photoresist (not shown) on top of the actuator 310 and on the support element 275 including the support layer 270 and the support line 274. A portion of the first upper electrode 300 and the second upper electrode 301 are exposed from the common electrode line 340 formed thereon. At this time, the protrusions of the lower electrode 280 are also exposed together from the first anchor 271.

Subsequently, the first strained layer 290 and the lower electrode 280 are removed from a part of the first upper electrode 300 by depositing and patterning amorphous silicon or silicon oxide or phosphorus pentoxide, which is a low temperature oxide, on the exposed portion. The first insulating layer 320 is formed up to a part of the support layer 270, and at the same time, the support layer 270 is formed from the part of the second upper electrode 301 through the second deformable layer 291 and the lower electrode 280. The second insulating layer 321 is formed to a part. The first insulating layer 320 and the second insulating layer 321 are formed to have a thickness of about 0.2 to 0.4 μm, and preferably about 0.3 μm, respectively, using a low pressure chemical vapor deposition (LPCVD) method.

The first anchor 271, the etch stop layer 255, and the first anchor 271 may be formed from an upper portion of the center of the first anchor 271, which is a portion where the hole of the second metal layer 245 and the drain pad of the first metal layer 235 are formed. 2, a portion of the protective layer 250 and the first protective layer 240 are etched to form a via hole 370 up to the drain pad of the first metal layer 235, and then a lower portion of the protective layer 250 and the first protective layer 240 is formed through the via hole 370. The via contact 380 is formed up to the protrusions of the electrode 280 (see FIG. 4). At the same time, the first upper electrode connecting member 330 is formed from the first upper electrode 300 to the common electrode line 340 through a portion of the first insulating layer 320 and the support layer 270, and the second upper electrode The second upper electrode connecting member 331 is formed from the 301 to the common electrode line 340 through a portion of the second insulating layer 321 and the support layer 270.

The via contact 380, the first and second upper electrode connecting members 330 and 331 may each have a thickness of about 0.1 μm to 0.2 μm by sputtering or chemical vapor deposition using platinum, tantalum or platinum-tantalum. After deposition to have, the deposited metal is formed by patterning. The first and second upper electrode connecting members 330 and 331 connect the first and second upper electrodes 300 and 301 and the common electrode line 340, respectively, and the lower electrode 280 connects the via contact 380. It is connected to the drain pad of the first metal layer 235 through.

Referring to FIG. 6E, an acuflo having a high viscosity on top of the actuator 310 and the support element 275 has an excellent deposition flatness compared to a conventional photoresist second sacrificial layer. ) To form the second sacrificial layer 400. The second sacrificial layer 400 made of accucu is applied on top of the actuator 310 and the support element 275 by using a spin coating method, thereby actuating the actuator 310 and the support element on the active matrix 200. 275) can easily overcome the step between the formed portion and the non-formed portion. In addition, the second sacrificial layer 400 composed of the acuflo may achieve planarization without a separate chemical mechanical polishing (CMP) process required when the conventional second sacrificial layer is formed using polysilicon. In addition, the second sacrificial layer 400 made of the accucu has an advantage of being removed without residues by using a plasma ashing method.

Subsequently, a hard mask made of a fifth photoresist 415 and aluminum or silicon oxide (SiO ₂ ) on top of the second sacrificial layer 400 to form the mirror 360 and the post 350. 420 is applied and the fifth photoresist 415 and the hard mask 420 are patterned by a conventional photolithography method, and then the second sacrificial layer 400 is patterned along the hard mask 420 pattern. A portion of the lower electrode 280 of the mirror-shaped 'C' that is not adjacent to and parallel to the support line 274 (that is, a portion where the first and second upper electrodes 300 and 301 are not formed thereon). ). When the material of the hard mask 420 is the same aluminum as the mirror 360 formed later, the hard mask 420 may be formed by a sputtering method or a chemical vapor deposition method, the material of the hard mask 420 In the case of silicon oxide, the hard mask 420 may be formed using a plasma enhanced chemical vapor deposition method (PECVD).

Next, a portion of the exposed lower electrode 280 and a metal such as aluminum (Al) having reflectivity on the top of the hard mask 420 may be sputtered or chemical vapor deposition using about 0.1 to 1.0 μm. Deposition to a thickness, and patterning the deposited metal to form a mirror 360 having a rectangular flat plate shape and a post 350 for supporting the mirror 360 at the same time. At this time, in order to form the mirror 360 and the post 350, the aluminum is about 30 to 70 sccm, preferably in an argon (Ar) gas atmosphere and a temperature of about 50 to 150 ℃, preferably about 100 ℃ , Deposited at a rate of about 50 sccm. Also in this case, the aluminum is deposited under a deposition pressure of about 1.0 to 1.5 mTorr, preferably about 1.2 to 1.3 mTorr.

After the fifth photoresist 415 and the second sacrificial layer 300 are removed by the plasma ashing method, the first sacrificial layer 160 is made of xenon fluoride (XeF ₂ ) or bromine fluoride (BrF ₂ ). Removal, and washing and drying treatments are completed to complete the AMA device as shown in FIG. As described above, when the second sacrificial layer 400 is removed, the second air gap 410 is formed at the position of the second sacrificial layer 400. When the first sacrificial layer 260 is removed, the first sacrificial layer 260 is removed. The first air gap 265 is formed at the position of.

In the above-described thin film type optical path control device according to the present invention, the first signal transmitted from the outside is the MOS transistor 220, the drain pad of the first metal layer 235 and the via contact 380 embedded in the active matrix 200. Is applied to the lower electrode 280, and at the same time, a second signal is applied to the first and second upper electrodes 300 and 301 through the common electrode line 340 from the outside, respectively, so that the first upper electrode 300 The first electric field is generated between the and the lower electrode 280 according to the potential difference, and the second electric field is generated between the second upper electrode 301 and the lower electrode 280 according to the potential difference. The first strained layer 290 formed between the first upper electrode 300 and the lower electrode 280 causes deformation by the first electric field, and at the same time, the second upper electrode 301 and the lower part by the second electric field. The second strained layer 291 formed between the electrodes 280 causes deformation.

As the first and second strained layers 290 and 291 contract in a direction perpendicular to the first and second electric fields, respectively, the actuator 310 including the first and second strained layers 290 and 291 may be formed. It is bent at a predetermined angle. The mirror 360 reflecting light incident from the light source is inclined together with the actuator 310 because the mirror 360 is supported by the post 350 and is formed on the actuator 310. Accordingly, the mirror 360 reflects the incident light at a predetermined angle, and the reflected light passes through the slit to form an image on the screen.

According to the manufacturing method of the thin film type optical path control apparatus according to the present invention, after forming a photoresist and a hard mask on the second sacrificial layer to pattern the second sacrificial layer, aluminum is formed on the top of the hard mask to form a mirror. When formed in, it is possible to minimize the stress generated in the mirror through the improvement of the aluminum deposition process conditions, it is possible to form a flat mirror without bending. Accordingly, the light efficiency of the mirror can be improved, and the image quality of the image projected on the screen can be improved.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be modified in various ways without departing from the spirit and scope of the invention described in the claims below. And can be changed.

Claims (1)

Providing an active matrix including a first metal layer having a MOS transistor embedded therein and having a drain pad extending from the drain of the transistor; Forming and patterning a first sacrificial layer on top of the active matrix; Forming a first layer, a lower electrode layer, a second layer, and an upper electrode layer on the first sacrificial layer; Patterning the upper electrode layer, the second layer and the lower electrode layer to form an actuator including a lower electrode, a first strained layer, a second strained layer, a first upper electrode, and a second upper electrode; Patterning the first layer to form a support line comprising a support line, a support layer and first and second anchors; Forming a second sacrificial layer on top of said support means and said actuator; Forming a photoresist and a hard mask on the second sacrificial layer, and patterning the second sacrificial layer using the photoresist and the hard mask; And On top of the patterned second sacrificial layer and the hard mask, aluminum is deposited under an argon (Ar) gas atmosphere, a temperature of about 50 to 150 ° C., a deposition rate of about 50 sccm, and a deposition pressure of about 1.0 to 1.5 mTorr. Method of manufacturing a thin film type optical path control device comprising the step of forming a mirror.