KR100262736B1 - Apparatus of actuated mirror arrays - Google Patents

Abstract

PURPOSE: A thin film actuated mirror array is to prevent a mirror from being damaged by a fluorine gas in the course of removing a sacrificial layer. CONSTITUTION: A substrate(100) has an MxN transistor installed therein and a drain pad(105) formed on one side thereof. A passivation layer(110) is formed on the substrate, using PSG(phosphor-silicate glass). An etching stop layer(115) is formed on the passivation layer, using nitride. A sacrificial layer is formed on the etching stop layer, using PSG. A part of the etching stop layer is exposed by etching the sacrificial layer with the drain pad formed thereon. A membrane(120) is formed on the exposed etching stop layer and on the sacrificial layer, using nitride. A lower electrode(125) is formed on the membrane. A deformation layer(130) is formed and annealed on the lower electrode, using a piezoelectric material. An upper electrode(140) is formed and patterned on the deformation layer. When a bias voltage is applied to the upper electrode, the field is generated between the upper electrode and the lower electrode.

Description

Thin film type optical path controller {APPARATUS OF ACTUATED MIRROR ARRAYS}

The present invention relates to a thin-film optical path control apparatus, and more particularly to a thin-film optical path control apparatus that can prevent the mirror from being damaged by the hydrofluoric acid solution in the process of removing the victim.

In general, a spatial light modulator, which is a device for projecting optical energy onto a screen, may be variously applied to optical communication, image processing, and information display devices. Such devices are classified into a direct view type image display device and a projection type image display device according to a method of projecting a light beam incident from a light source onto a screen. The direct view type image display device includes a CRT (Cathod Ray Tube), and the projection type image display device includes a liquid crystal display (hereinafter referred to as an LCD), a DMD (deformable mirror device), or an AMA (Actuated). Mirror Arrays).

The above-described CRT apparatus is an excellent display apparatus which is guaranteed an average brightness of 100 ft-L (white display) or more, a contrast ratio of 30: 1 or more, a lifetime of 10,000 hours or more. However, since the CRT has a large weight and volume and maintains high mechanical strength, it is difficult to make the screen completely flat, which causes distortion of the peripheral part. In addition, since CRTs excite phosphors with an electron beam to emit light, there is a problem that a high voltage is required to produce an image.

Therefore, LCDs have been developed to solve the above-mentioned problems of CRT. The advantages of such LCDs are explained in comparison with CRTs. LCDs operate at low voltages, consume less power, and provide images without distortion.

However, despite the above-mentioned advantages, the LCD has a low light efficiency of 1 to 2% due to the polarization of the light beam, and has a problem in that the response speed of the liquid crystal material therein is slow.

Accordingly, in order to solve the problems of the LCD as described above, a device such as a DMD or an AMA has been developed. Currently, AMA can achieve a light efficiency of 10% or more, while DMD has a light efficiency of about 5%. In addition, the AMA is not only affected by the polarity of the incident luminous flux but also does not affect the polarity of the luminous flux.

Typically, the respective actuators formed inside the AMA cause deformation depending on the electric field generated by the applied image signal and bias voltage. When this actuator causes deformation, each of the mirrors mounted on top of the actuator is inclined in proportion to the magnitude of the electric field.

Thus, these inclined mirrors can reflect light incident from the light source at a predetermined angle. Piezoelectric ceramics such as PZT (Pb (Zr, Ti) O ₃ ) or PLZT (Pb, La) (Zr, Ti) O ₃ ) are used as a constituent material of the actuator for driving the respective mirrors. As the constituent material of the actuator, electrodistorted ceramics such as PMN (Pb (Mg, Nb) O ₃ ) can be used.

The AMA is classified into a bulk type and a thin film type. Currently, AMA is the main trend of the thin-film optical path control device. This thin film type optical path control device is disclosed in Korean Patent Application No. 95-59191 (Applicant Name: Thin film type optical path control device that can improve the light efficiency), which is filed by the applicant of the Korean Patent Office on November 28, 1996.

FIG. 1 shows a plan view of the thin film type optical path adjusting device described by the prior application, FIG. 2 shows a perspective view of the device shown in FIG. 1, and FIG. 3 shows the AA 'line of the device shown in FIG. It shows a cross-sectional view cut into.

Referring to FIGS. 1, 2 and 3, the thin film type optical path adjusting device described by the prior application includes a substrate 5 and an actuator 65 and a mirror 60 formed thereon. The substrate 5 includes a drain pad 10 formed thereon, a protective layer 15 formed on the substrate 5 and the drain pad 10, and an etch stop layer 20 formed on the protective layer 15. It includes.

Referring to FIG. 3, the actuator 65 may be in contact with a portion of the etch stop layer 20 in which the drain pad 10 is formed at the bottom thereof, and the other side thereof may be contacted with the etch stop layer 20 through the air gap 28. The membrane 30 formed in parallel, the lower electrode 35 formed on the membrane 30, the strained layer 40 formed on the lower electrode 35, the upper electrode 45 formed on the strained layer 40 And a vertical distribution from the other side of the strained layer 40 to the drain pad 10 through the strained layer 40, the lower electrode 35, the membrane 30, the etch stop layer 20, and the protective layer 15. The hole 50, and a power distribution unit 55 formed vertically to electrically connect the lower electrode 35 and the drain pad 10 in the distribution hole 50.

In addition, referring to FIG. 2, the membrane 30 has a shape in which a rectangular flat plate is integrally formed with the above-described arms on the same plane between two rectangular arms formed in parallel from both support portions. Has The mirror 60 is formed on the rectangular flat plate of the membrane 30. Thus, the mirror 60 has a rectangular flat plate shape.

However, the above-described conventional thin film type optical path adjusting device has a problem that the mirror is damaged by hydrofluoric acid in the process of removing the sacrificial layer because the mirror and the membrane are formed in the same size.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a thin film type optical path control apparatus that can prevent the mirror from being damaged by the hydrofluoric acid gas in the process of removing the sacrificial layer.

In order to achieve the above object, the present invention provides a substrate in which M × N (M, N is an integer) transistor is built and a drain pad is formed on one side and i) formed on the substrate in parallel from both sides. A membrane having a shape in which a rectangular flat plate is integrally formed with the arms on the same plane between two rectangular arms, ii) two rectangular arms larger than the membrane are formed at both support portions, A lower electrode having sidewalls with a rectangular flat plate between the arms, iii) a strained layer formed on top of the lower electrode to cause deformation according to an electric field, and iv) an upper electrode formed on top of the strained layer and applied with a bias voltage M x N actuators each including a thin film type optical path having a mirror formed in the concave portion surrounded by the side wall of the lower electrode Provide an adjusting device.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

1 is a plan view of a thin film-type optical path control device according to the applicant's prior application.

2 is a perspective view of the apparatus shown in FIG.

3 is a cross-sectional view taken along line A-A 'of the apparatus shown in FIG.

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

5 is a perspective view of the apparatus shown in FIG.

6 is a cross-sectional view taken along line B-B 'of the apparatus shown in FIG.

7 to 12b are manufacturing process diagrams of the apparatus shown in FIGS. 5 and 6;

13 is a cross-sectional view taken along line C-C 'of the device shown in FIG.

* Explanation of symbols for main parts of the drawings

100: substrate 105: drain pad

110: protective layer 115: etch stop layer

120 membrane 125 lower electrode

130: strained layer 140: upper electrode

145 power distribution hall 150 power distribution

160 mirror

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

4 is a plan view of a thin film type optical path control apparatus according to the present invention, FIG. 5 is a perspective view of the apparatus shown in FIG. 4, and FIG. 6 is a cross-sectional view taken along line BB 'of the apparatus shown in FIG. It is shown.

The thin film type optical path control apparatus of FIGS. 4, 5, and 6 can be said to use the thin film type optical path control apparatus of FIGS. 1, 2, and 3.

In the thin film type optical path adjusting device according to the present invention of FIGS. 4, 5 and 6, the lower electrode 125 is formed in a '凹' shape having a sidewall on the top of the membrane 120 having a rectangular shape. The mirror 160 is formed on the concave portion of the lower electrode 125.

Hereinafter, the manufacturing method of the thin film type optical path control apparatus which concerns on this invention is demonstrated in detail with reference to drawings.

7 to 12b also show a manufacturing process of the thin film type optical path control apparatus according to the present invention.

Referring to FIG. 7, a substrate in which M × N (M and n are integers) MOS (Metal Oxide Semiconductor) transistors (not shown) are embedded and a drain pad 105 is formed on one side thereof. The protective layer 110 is formed on the upper portion of the 100. The protective layer 110 is formed to have a thickness of about 0.1 to 10 μm of the silicate glass (PSG) using a chemical vapor deposition (CVD) method, so that the substrate 100 having the transistor embedded therein is damaged during a subsequent process. Prevent it.

An etch stop layer 115 is formed on the passivation layer 110. The etch stop layer 115 is formed to have a thickness of about 1000 to 2000 microns by using a low pressure chemical vapor deposition (LPCVD) method, and the substrate 100 and the protective layer 110 are damaged by a subsequent etching process. To prevent them.

The sacrificial layer 117 is formed on the etch stop layer 115. The sacrificial layer 117 is formed to have a thickness of about 0.5 to 4.0 μm of the phosphorous silicate glass (PSG) by atmospheric chemical vapor deposition (APCVD). In this case, since the sacrificial layer 117 covers the upper portion of the substrate 100 in which the transistor is embedded, the flatness of the surface thereof is very poor. Therefore, the surface of the sacrificial layer 117 is planarized by using a spin on glass (SOG) method or a chemical mechanical polishing (CMP) method. Subsequently, a portion of the sacrificial layer 117 on which the drain pad 105 is formed is etched to expose a portion of the etch stop layer 115, thereby forming a portion on which the support portion of the actuator 170 is to be formed.

Referring to FIG. 8, the membrane 120 is formed on the exposed etch stop layer 115 and on the sacrificial layer 117. The membrane 120 is formed to have a thickness of about 0.1 to 1.0 μm using a low pressure chemical vapor deposition (LPCVD) method. Subsequently, a lower electrode 125, which is a signal electrode made of a metal such as platinum or platinum-tantalum, is formed on the membrane 120. The lower electrode 125 is formed to have a thickness of about 0.1 μm to about 1.0 μm using a sputtering method. An image signal is applied to the lower electrode 125 through the drain pad 105 from a transistor embedded in the substrate 100.

The strained layer 130 is formed on the lower electrode 125. The strained layer 130 is formed to have a thickness of about 0.1 to 1.0 μm by using a sol-gel method, a sputtering method, or a chemical vapor deposition (CVD) method for piezoelectric materials such as PZT or PZLT. . In addition, the strained layer 130 is phase shifted by using a rapid heat treatment (RTA) method.

The upper electrode 140 is formed on the strained layer 130. The upper electrode 140 is formed to have a thickness of about 0.1 μm to about 1.0 μm by using a sputtering method of aluminum, platinum, or silver. The upper electrode 140 is applied with a bias voltage as a common electrode. Therefore, when an image signal is applied to the lower electrode 125 and a bias voltage of the upper electrode 140 is applied, an electric field is generated between the upper electrode 140 and the lower electrode 125. The strained layer 130 causes deformation by this electric field.

9A and 9B, after the first photoresist (not shown) is coated on the upper electrode 140 by spin coating, the upper electrode 140 is formed with 'c'. Pattern to have a child shape. Next, after the first photoresist is removed, a second photoresist (not shown) is applied on the patterned upper electrode 140 and the strained layer 130 by spin coating, and then the strained layer 130 is It is patterned to have a '-' shape slightly wider than the upper electrode (140). Subsequently, the second photo register is removed.

Referring to FIGS. 10A and 10B, the strained layer 130, the lower electrode 125, the membrane, the etch stop layer 115, and the protective layer may be formed from the portion where the drain pad 105 is formed in the strained layer 130. After the 110 is sequentially etched to form the distribution hole 145, the drain pad 105 and the lower electrode (eg, tungsten, platinum, aluminum, or titanium) are sputtered inside the distribution hole 145 using a sputtering method. The distributor 150 is formed to electrically connect 125. The distributor 150 is vertically formed from the lower electrode 125 to the upper portion of the drain pad 105 in the distribution hole 145. Accordingly, the image signal is applied to the lower electrode 125 through the drain pad 105 and the distributor 150 from the transistor embedded in the substrate 100.

11A and 11B, after the third photoresist (not shown) is applied to the patterned strained layer 130 and the distribution hole 145 by spin coating, the lower electrodes of both support portions The 125 may have a rectangular shape slightly wider than that of the strained layer 130, and the lower electrode 125 formed at the center thereof may be patterned to form a rectangular flat plate. That is, as shown in FIG. 11B, the lower electrode 125 has rectangular arms formed from both supporting portions, and a rectangular flat plate having a larger area than the arms is integrated with the above-described arms on the same plane. It has a shape formed by. Subsequently, the third photoresist is removed.

As described above, after the fourth photoresist (not shown) is coated on the patterned lower electrode 125 by spin coating, the membrane 120 of both supporting parts has a rectangular shape slightly wider than the lower electrode 125. The membrane 120 of the central portion formed integrally therewith is patterned to form a rectangular flat plate. In this case, the membrane 120 of the central portion is formed to have the same size as the lower electrode 125 of the central portion described above. That is, as shown in FIG. 12B, the membrane 120 has rectangular arms formed from both sides of the support, and a rectangular flat plate having a larger area than the arms is formed integrally with the above-described arms on the same plane. It has a formed shape. Subsequently, when the fourth photoresist is removed, part of the sacrificial layer 117 is exposed.

Referring to FIGS. 12A and 12B, a rectangular flat plate in the center of the lower electrodes 125 is formed in a '凹' structure having sidewalls around it, as shown in FIG. 13. Subsequently, the mirror 160 is formed in the concave portion of the lower electrode 125 surrounded by the sidewall by a lift-off method. At this time, the mirror 160 is formed at a height lower than the sidewall of the lower electrode 125. Subsequently, the sacrificial layer 117 is removed using hydrofluoric acid gas. At this time, the mirror 160 is not affected by the fluorine gas by the sidewall of the lower electrode 125.

Next, after completing the M × N AMA elements by cleaning and drying, a metal such as chromium, nickel, or gold is deposited on the bottom of the substrate 100 using a sputtering method or a deposition method to form a resistive contact (not shown). Form. Subsequently, the substrate 100 is prepared in preparation for bonding (Tape Carrier Package) bonding for applying a bias voltage to a subsequent upper electrode 140 which is a common electrode and an image signal to the lower electrode 125 which is a signal electrode. Truncate At this time, the substrate 100 is cut only to a predetermined thickness in preparation for the subsequent process. Subsequently, the pad (not shown) of the AMA panel and the pad (not shown) of the TCP are connected to complete the manufacture of the thin film module.

In the above-described thin film type optical path control apparatus according to the present invention, a bias voltage is applied to the upper electrode 140 through a pad of a TCP pad and an AMA panel. At the same time, the image signal transmitted through the pad of the TCP and the pad of the AMA panel is applied to the lower electrode 125 through the transistor and drain pad 105 and the distributor 150 built in the substrate 100. Therefore, the strained layer 130 between the upper electrode 140 and the lower electrode 125 causes deformation.

The strained layer 13 contracts in a direction perpendicular to the electric field, and the actuator 170 including the strained layer 130 and the membrane 120 is bent at a predetermined angle. Since the mirror 160 reflecting the light beam incident from the light source is formed in the concave portion of the membrane 120, the mirror 160 is bent at the same angle as the actuator 170. Accordingly, the mirror 160 reflects the incident light flux at a predetermined angle, and reflects the reflected light flux through the slit to form an image.

As described above, the thin film type optical path adjusting device according to the present invention makes the lower electrode a '凹' shape having a sidewall and forms a mirror in the concave portion of the lower electrode surrounded by the sidewall. This has the advantage of preventing the mirror from being damaged.

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

Claims (5)

A substrate 100 having M × N (M, N is an integer) transistors and a drain pad 105 formed on one side thereof; On the substrate 100, i) a membrane having a shape in which a rectangular flat plate is formed integrally with the arms on the same plane between two rectangular arms formed in parallel from both support portions ( 120), ii) two rectangular arms larger than the membrane 120 are formed at both sides of the bark, and a lower electrode 125 having a sidewall around the quadrangular plate between the arms, and iii) the lower portion. M formed on the electrode 125 and causing deformation according to an electric field; and iv) M formed on the deformation layer 130 and including an upper electrode 140 to which a bias voltage is applied. N actuators 170; And a mirror (160) formed in a concave portion surrounded by the sidewall of the lower electrode (125). The drain pad of claim 1, wherein the actuator 170 is formed from the deformation layer 130 through the lower electrode 125, the membrane 120, the etch stop layer 115, and the protective layer 110. Further comprising a power distribution hole 145 vertically formed up to 105 and a power distribution 150 vertically formed such that the lower electrode 125 and the drain pad 105 are electrically connected in the power distribution hole 145. Thin film type optical path control device characterized by. The apparatus of claim 1, wherein the lower electrode (125), the deformable layer (130), and the upper electrode (140) each have a mirror-shaped 'C' shape at both support parts. The apparatus of claim 1, wherein the mirror (160) is made of aluminum and has a thickness of 0.1 to 1.0 μm. The thin film type optical path control device according to claim 1, wherein a cross section of the lower electrode (125) has a '凹' shape by the sidewalls.

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