KR100273899B1 - Apparatus and fabricating method of actuated mirror arrays - Google Patents

Abstract

PURPOSE: A thin film actuated mirror array is provided to prevent the crack generated at an active layer and a top electrode by forming an insulation part in an insulation window so as to remove a step difference. CONSTITUTION: A passivation layer(530) is formed on a drive substrate(510) in which M by N transistors are embedded in a matrix. An etch preventing layer(540) is formed on the passivation layer(530) and prevents the passivation layer(530) and a lower part thereof from being damaged during a post process. A membrane(560) has a bridge(670) connected with a pixel adjacent in a row or column direction. A region adjacent to the bridge(670) is contact with the etch preventing layer(540), and a region extended from the bridge(670) is spaced from the etch preventing layer(670). A bottom electrode(570) is formed on the membrane(560), and a pixel and an insulation part(645) are interposed in the bottom electrode(570). The bottom electrode(570) is supplied with an image signal from the transistor. An active layer(580) is formed on the bottom electrode(570) and the insulation part(645), and is changed in proportion to the magnitude of an electric field. A top electrode(590) is formed on the active layer(580) so as to be connected to a pixel adjacent in the row or column direction.

Description

Thin film type optical path control device and its manufacturing method {APPARATUS AND FABRICATING METHOD OF ACTUATED MIRROR ARRAYS}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film type optical path adjusting device and a method of manufacturing the same. In particular, cracks may be prevented in the strained layer and the upper electrode due to the step difference between the insulating windows formed on the bridge of the actuator. A thin-film optical path control device and its manufacturing method.

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. CRT (Cathod Ray Tube) is a direct view type display device, and a projection type image display device is a liquid crystal display device (hereinafter referred to as LCD), Deformable Mirror Device (DMD) or Actuated Mirror Arrays (AMA). ).

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 problems of CRT. The advantages of such LCDs are explained in comparison with CRTs.

Firstly, the LCD operates at low voltage, consumes little power and provides an image without distortion.

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

Accordingly, in order to solve the problems of the LCD, 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.

1 is a plan view of a conventional thin film type optical path control device.

As can be seen in Figure 1, one side of the actuator 130 has a concave portion of the rectangular shape in the center, the concave portion is formed in a shape that widens stepwise toward both edges. The other side of the actuator 130 has a rectangular protrusion which narrows down stepwise toward the center portion corresponding to the concave portion. Therefore, the concave portion of the actuator 130 is fitted with a rectangular protrusion of the adjacent actuator, and the rectangular protrusion is fitted with the concave portion of the adjacent actuator.

The actuator 130 is divided into a driver 150 and a bridge 170. The driving unit 150 is formed to be spaced apart from the etch stop layer 40 of the driving substrate 10 shown in FIG. 2 by a predetermined distance, and is deformed when an image signal is applied to change the path of the light beam incident through the optical system to the slit. Reflect. At this time, the amount of luminous flux passing through the slit is changed according to the angle at which the driving unit 150 is deformed to implement various color screens.

The bridge 170 connects neighboring pixels in a row (or column) direction for each pixel. The bridge 170 is in contact with the etch stop layer 40 of the driving substrate 10 shown in FIG. 2, and the driving unit 150 extending from the bridge 170 is formed to be spaced apart from the etch stop layer 40 by a predetermined distance. Accordingly, the bridge 170 allows the driving unit 150 to operate stably when an image signal is applied. In addition, an insulating window 140 is formed at a predetermined portion of the bridge 170 to electrically separate the neighboring actuator.

FIG. 2 is a cross-sectional view of the apparatus shown in FIG. 1 taken along line A-A '.

Referring to FIG. 2, the apparatus for controlling a thin film type optical path includes a driving substrate 10 having a drain 20 formed on one side thereof, and an actuator 130 formed thereon.

M × N (M, N is an integer) transistors are built in a matrix form in the driving substrate 130. In addition, the driving substrate 10 includes a protective layer 30 formed on the upper portion and the drain 20 and an etch stop layer 40 formed on the upper portion.

The actuator 130 is formed such that one side of the etch stop layer 40 is in contact with a portion where the drain 20 is formed, and the other side thereof is parallel to the etch stop layer 40 via an air gap 50. (membrane) 60, the lower electrode 70 formed on the membrane 60, the strained layer 80 formed on the lower electrode 70, and the upper electrode formed on the strained layer 80. 90, the stripe 100 formed on a predetermined portion of the upper electrode 90, and the lower electrode 70, the membrane 60, the etch stop layer 40, and the protective layer 30 from the other side of the strained layer 80. And a distribution hole 110 formed vertically through the drain 20 to the drain 20, and the distribution electrode 120 formed to electrically connect the lower electrode 70 and the drain 20 to each other in the distribution hole 110.

3 is a cross-sectional view of the apparatus shown in FIG. 1 taken along line B-B '.

Referring to FIG. 3, the bridge 170 may include a driving substrate 10, a protection layer 30 formed on the driving substrate 10, an etch stop layer 40 formed on the protection layer 30, The membrane 60 formed on the etch stop layer 40, the lower electrode 70 formed on the membrane 60, the insulating window 140 formed by removing a predetermined portion of the lower electrode 70, and the lower part thereof. And a strained layer 80 formed on the electrode 70 and the insulating window 140, and an upper electrode 90 formed on the strained layer 80.

The insulating window 140 in which the predetermined portion of the lower electrode 70 is removed from the bridge 170 is electrically separated from the actuator 130 and the neighboring actuator to provide a separate image signal from the transistor. Therefore, each actuator 130 is driven independently since the image signal is provided separately.

However, the conventional thin film type optical path adjusting device has a problem that cracks occur in the strained layer and the upper electrode due to a step generated by an insulating window electrically separating the neighboring actuators to provide individual image signals for each pixel.

The present invention has been made to solve the conventional problems as described above, an object of the present invention is to form an insulating portion inside the insulating window to remove the step by removing the cracks generated in the strained layer and the upper electrode It is an object of the present invention to provide an optical path control device and a method of manufacturing the same.

In order to achieve the above object, the present invention includes a protective layer formed on an upper portion of a driving substrate in which M x N transistors corresponding to M x N (M, N is an integer) pixels are embedded in a matrix form; An etch stop layer formed on top of the passivation layer to prevent damage to the passivation layer and its bottom during subsequent processing; Each pixel has a bridge on the top of the etch stop layer connected to neighboring pixels in a row (or column) direction, and an area adjacent to the bridge contacts the etch stop layer, and another area extending from the bridge is spaced apart from the etch stop layer by a predetermined distance. A formed membrane; A lower electrode formed on the membrane via a neighboring pixel and an insulator and receiving an image signal from a transistor for each pixel; A strained layer formed on the lower electrode and the insulating part and deformed in proportion to the magnitude of the electric field; An upper electrode is formed on the strained layer so as to be connected to neighboring pixels in a row (or column) direction for each pixel.

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

1 is a plan view of a conventional thin film type optical path control device,

2 is a cross-sectional view taken along line AA ′ of the apparatus of FIG. 1;

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

4 is a plan 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 C-C ';

6 is a cross-sectional view taken along line D-D 'of the apparatus of FIG. 5,

7A to 7C are manufacturing process diagrams of the apparatus shown in FIG. 6.

<Explanation of symbols for main parts of drawing>

510: driving substrate 530: protective layer

540: etch stop layer 560: membrane

570: lower electrode 580: strained layer

590: upper electrode 640: insulating window

645: insulation

Hereinafter, with reference to the accompanying drawings will be described in detail the thin-film optical path control apparatus according to the present invention.

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

Referring to FIG. 4, one side of the actuator 630 has a concave portion having a rectangular shape at a center thereof, and the concave portion is formed to have a stepped shape toward both edges. The other side of the actuator 630 has a rectangular protrusion that narrows stepwise toward the center portion corresponding to the concave portion. Accordingly, the concave portion of the actuator 630 is fitted with a rectangular protrusion of the adjacent actuator, and the rectangular protrusion is fitted with the concave portion of the adjacent actuator.

The actuator 630 is divided into a driver 650 and a bridge 670. The driving unit 650 is formed to be spaced apart from the etch stop layer 540 of the driving substrate 510 of FIG. 5 by a predetermined distance, and is deformed when an image signal is applied to change the path of the light beam incident through the optical system to reflect the slit. do. At this time, the amount of luminous flux passing through the slit is changed according to the angle at which the driving unit 650 is deformed to implement various color screens.

The bridge 670 is connected to neighboring pixels in a row (or column) direction for each pixel. The bridge 670 is in contact with the etch stop layer 540 of the driving substrate 510, and the driving unit 650 extending from the bridge 670 is formed to be spaced apart from the etch stop layer 540 by a predetermined distance. Accordingly, the bridge 670 allows the driving unit 650 to operate stably when an image signal is applied. In addition, an insulating window 640 is formed at a predetermined portion of the bridge 670 to electrically separate the neighboring actuators. An insulating part 645 is formed inside the insulating window 640 as a material constituting the strained layer 570 shown in FIG. 5. Since the step generated by the insulating window 640 is removed through the insulating part 645, cracks do not occur in the deformation layer 580 and the upper electrode 590.

FIG. 5 is a cross-sectional view of the apparatus shown in FIG. 4 taken along line C-C '.

Referring to FIG. 5, the thin film type optical path control apparatus includes a driving substrate 510 having a drain 520 formed on one side thereof, and an actuator 630 formed thereon.

Inside the driving substrate 510, M × N transistors (M and N are integers) are built in a matrix. In addition, the driving substrate 510 has a protective layer 530 and an etch stop layer 540 sequentially formed on the top and the drain 520.

The actuator 630 may have a membrane 560 formed to be in contact with a portion of the etch stop layer 540 formed at a lower portion thereof and to be parallel to the etch stop layer 540 through the air gap 550. The lower electrode 570 formed on the membrane 560, the strained layer 580 formed on the lower electrode 570, the upper electrode 590 formed on one side of the strained layer 580, and the upper portion A stripe 600 formed on a predetermined portion of the electrode 590 and a drain 520 through the lower electrode 570, the membrane 560, the etch stop layer 540, and the protective layer 530 on the other side of the strained layer 580. The distribution hole 610 formed up to) and the lower electrode 570 and the drain 520 in the distribution hole 610 are formed to be electrically connected to each other.

FIG. 6 is a cross-sectional view of the apparatus shown in FIG. 4 taken along the line D-D '.

Referring to FIG. 6, the bridge 670 may include a driving substrate 510, a protective layer 530 formed on the driving substrate 510, an etch stop layer 540 formed on the protective layer 530, The membrane 560 formed on the etch stop layer 540, the lower electrode 570 formed on the membrane 560, and the insulating window 640 formed vertically from the lower electrode 570 to the upper part of the membrane 560. And an insulating part 645 formed filling the inside of the insulating window 640, a strained layer 580 formed on the lower electrode 570, and an insulating part 645, and formed on the strained layer 580. The upper electrode 590 is included.

7A to 7C are manufacturing process diagrams of the apparatus shown in FIG. 6.

Referring to FIG. 7A, the driving substrate 510 includes M × N transistors (not shown) where M is an integer, and is formed in a matrix form.

The protective layer 530 is formed of a silicate glass on top of the driving substrate 510 to a thickness of about 0.1 to 1.0 μm by a chemical vapor deposition (CVD) method, and the driving substrate 510 having a transistor embedded therein during a subsequent process. ) To prevent damage.

An etch stop layer 540 is formed on the passivation layer 530 to have a thickness of 1000 to 2000 GPa by nitride low pressure chemical vapor deposition (LPCVD). This etch stop layer 540 prevents the protective layer 530 and its bottom from being damaged during subsequent etching processes.

The membrane material layer 560 ′ is stacked on the etch stop layer 540. The membrane material layer 560 'is formed of a nitride by low pressure chemical vapor deposition and has a thickness of 0.1 to 1.0 mu m.

The lower electrode material layer 570 ′ is stacked on the membrane material layer 560 ′. The lower electrode material layer 570 ′ is formed to have a thickness of about 1000 to 1200 Å by sputtering a metal having excellent electrical conductivity such as platinum or platinum-tantalum.

Next, a portion of the lower electrode material layer 570 ′ is removed to expose the membrane material layer 560 ′ to form an insulating window 640. The insulating window 640 allows a separate image signal to be supplied to the respective actuators 630.

Referring to FIG. 7B, a piezoelectric material such as PZT or PLZT, which is a material constituting the strained layer 580, described later on the inside of the insulating window 640 and the lower electrode material layer 570 ′, or a chemical vapor phase. It is formed to have a thickness of 1000 to 1200 kPa by the vapor deposition method.

At this time, since the inside of the insulating window 640 is filled with a piezoelectric material such as PZT or PLZT, the step is removed.

Referring to FIG. 7C, piezoelectric materials such as PZT or PLZT stacked on the lower electrode material layer 570 ′ are removed.

Subsequently, the strain material layer 580 ′ is stacked on the lower electrode material layer 570 ′ and the insulating portion 645. The deformable material layer 580 'is formed using a piezoelectric material such as PZT or PLZT. The deformable material layer 580 ′ is formed to have a thickness of 0.1 μm to 1.0 μm by a sol-gel method, a sputtering method, or a chemical vapor deposition (CVD) method. Subsequently, the strained material layer 580 ′ is subjected to rapid thermal treatment (RAT) for phase transformation.

An upper electrode material layer 590 'is formed on top of the strained material layer 580'. The upper electrode material layer 590 'is, for example, a metal having excellent electrical conductivity and reflective properties. It forms by sputtering method using aluminum, platinum, silver, etc.

Lastly, the upper electrode material layer 590 ', the modifying material layer 580', the lower electrode material layer 570 ', and the membrane material layer 560 are patterned in pixel units to form the upper electrode 590 and the modifying layer ( 580, the lower electrode 570, and the membrane 560 are formed.

As described above, the thin film type optical path control device according to the present invention, by removing the step by filling the inside of the insulating window with the constituent material of the strained layer, it is possible to prevent the cracks caused by the step between the strained layer and the upper electrode. There is.

As described above, although the present invention has been described with reference to the drawings, those skilled in the art may variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can.

Claims (4)

A protective layer 530 formed on an upper portion of the driving substrate 510 in which M × N transistors (not shown) corresponding to M × N (M and N are integers) pixels are formed in a matrix form; An etch stop layer 540 formed on top of the passivation layer 530 to prevent the passivation layer 530 and the bottom thereof from being damaged during a subsequent process; The etch stop layer 540 has a bridge 670 connected to neighboring pixels in a row (or column) direction for each pixel, and an area adjacent to the bridge 670 has an etch stop layer 540. Contact with the other area extending from the bridge 670 includes a membrane 560 formed spaced apart from the etch stop layer 670 by a predetermined distance; A lower electrode 570 formed on the membrane 560 via a neighboring pixel and an insulator 645 to receive an image signal from the transistor for each pixel; A strained layer 580 formed on the lower electrode 570 and the insulating part 645 and deformed in proportion to the magnitude of the electric field; And an upper electrode (590) formed on the deformable layer (580) so as to be connected to neighboring pixels in a row (or column) direction for each pixel. The apparatus of claim 1, wherein the insulation portion is formed of a piezoelectric material such as PZT or PLZT. Sacrifice to have a pattern for exposing a portion of the driving substrate 510 for each pixel on the driving substrate 510 having a transistor, a protective layer 530 protecting the upper portion thereof, and an etch stop layer 540 at the top thereof. Forming a layer (not shown); Sequentially stacking a membrane material layer (560 ') and a lower electrode material layer (570') on the sacrificial layer and the exposed driving substrate (510); Forming an insulating window (640) by removing a predetermined portion of a region in which the bridge (670) connected to neighboring pixels in the row (or column) direction of the lower electrode material layer (570 ') is to be formed; Filling the inside of the insulating window 640 with a piezoelectric material such as PZT or PLZT to form an insulating part 645; Stacking a strain material layer (580 ') on the lower electrode material layer (570') and the insulating portion (645); Forming an upper electrode material layer (590 ') on top of the strain material layer (580'); The upper electrode material layer 590 ', the deformable material layer 580', the lower electrode material layer 570 ', and the membrane material layer 560' are patterned in pixel units to form the upper electrode 590 and deformable. A method of manufacturing a thin film type optical path control device comprising the step of forming a layer (580), a lower electrode (570), a membrane (560). The method of claim 3, wherein the forming of the insulating part comprises laminating a piezoelectric material such as PZT or PLZT on the inside of the insulating window and on the lower electrode material layer, and the piezoelectric material stacked on the lower electrode material layer. Etching to remove the lower electrode material layer so that the height of the piezoelectric material inside the insulating window is the same.

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