KR100258105B1 - Apparatus for actuated mirror arrays - Google Patents

Abstract

PURPOSE: A thin film actuated mirror arrays is to uniformly distribute the stress of a mirror and a membrane by forming an auxiliary layer having the same material as a mirror on the lower part of the membrane. CONSTITUTION: An active substrate(510) has an MxN transistor provided therein and a drain pad(520) formed on one side thereof. A passivation layer(530) is formed on the active substrate. An etching stop layer(540) is formed on the passivation layer. A sacrificial layer is formed on the etching stop layer. An auxiliary layer(650) having the same material as a mirror(610) is formed on the sacrificial layer. The mirror is formed on a membrane(570) having a rectangular shape. The auxiliary layer uniformly distributes the stress generated between the membrane and the mirror. A part of the etching stop layer is exposed by etching the auxiliary layer and the sacrificial layer with the drain pad formed thereon, thereby forming a supporting region of an actuator(640).

Description

Thin film type optical path controller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film type optical path control device, and more particularly, to a thin film type optical path control device capable of stabilizing a structure by uniformly distributing stress between the membrane and the mirror by forming an auxiliary layer of the same material as the mirror at the bottom of the membrane. It is about.

In general, a spatial light modulator, which is an apparatus for projecting optical energy onto a screen, may be variously applied to optical communication, image processing, and information display apparatus. 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 image display device includes a CRT (Cathod Ray Tube), and the projection 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 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 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 this 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, Figure 2a is a perspective view of the device shown in Figure 1, Figure 2b is a cross-sectional view taken along the line AA 'of the device shown in Figure 2a. It is.

1, 2A and 2B, the conventional thin film type optical path control apparatus includes a driving substrate 10 and an actuator 140 and a mirror 110 formed thereon. The driving substrate 10 includes a drain pad 20, a protective layer 30, and an etch stop layer 40.

Referring to FIG. 2B, the actuator 140 has one side in contact with a portion in which the drain pad 20 is formed in the lower portion of the etch stop layer 40 and the other side is parallel to the etch stop layer 40 through the air gap 60. The formed membrane 70, the lower electrode 80 formed on one side of the membrane 70, the strained layer 90 formed on the lower electrode 80, and the upper electrode 100 formed on the strained layer 90. And a distribution hole vertically formed from the other side of the strained layer 90 to the drain pad 20 through the strained layer 90, the lower electrode 80, the membrane 70, the etch stop layer 40, and the protective layer 30. 120, a distributor 130 vertically formed such that the lower electrode 80 and the drain pad 20 are electrically connected to each other in the distribution hole 120, and the mirror 110 formed on one side of the membrane 70. Include.

Also, referring to FIG. 2A, the membrane 70 has two rectangular arms formed in parallel in the support region, and has a rectangular shape in the driving region. The mirror 110 is formed on the rectangular flat plate of the membrane 70. Thus, the mirror 110 has a rectangular shape.

However, the above-described conventional thin film type optical path control device has a mirror formed on the upper part of the membrane, and the membrane and the mirror have a problem of bending because the stress of the membrane and the mirror is asymmetric.

The present invention has been made to solve the conventional problems as described above, the object of the present invention is to provide an auxiliary layer of the same material as the mirror at the bottom of the membrane thin film type optical path control that can evenly distribute the stress of the membrane and the mirror In providing a device.

In order to achieve the above object, the present invention includes a driving substrate in which M × N (M, N is an integer) transistors are built and a drain pad is formed on one side thereof; An auxiliary layer formed on the top of the driving substrate in a 'c' shape having two arms in the supporting region, having a rectangular shape in the driving region and integrally formed with the arms, and smaller than the auxiliary layer in the supporting region. A membrane having a 'c' shape and having a rectangular shape having the same size as the auxiliary layer in the driving region, a lower electrode having a 'c' shape smaller than the membrane in the supporting region, and a 'c' shape smaller than the lower electrode in the supporting region. M x N actuators each including an upper electrode having a 'c' shape smaller than the strained layer in the strained layer and the support region; And a mirror formed on the membrane having a rectangular shape of the driving region.

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 conventional thin film type optical path control device,

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

FIG. 2B is a cross-sectional view of the device shown in FIG. 2A taken along line A-A ',

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

4a is a perspective view of the device shown in FIG.

4B is a cross-sectional view of the device shown in FIG. 4A taken along line B-B ';

5A to 5F are manufacturing process diagrams of the apparatus shown in FIG. 4B;

6A-6D are manufacturing process diagrams of the device shown in FIG. 4A.

<Description of the symbols for the main parts of the drawings>

510: driving substrate 520: drain pad

530: protective layer 540: etching prevention layer

550: sacrificial layer 560: air gap

570: membrane 580: lower electrode

590 strain layer 600 upper electrode

610: mirror 620: power distribution hall

630: distributor 640: actuator

650: auxiliary layer

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.

Figure 3 is a plan view of a thin film type optical path control apparatus according to the present invention, Figure 4a is a perspective view of the device shown in Figure 3, Figure 4b is a cross-sectional view taken along the line BB 'of the device shown in Figure 4a. will be.

The thin film type optical path adjusting device of FIGS. 3, 4A, and 4B may substantially use the thin film type optical path adjusting device of FIGS. 1, 2A, and 2B.

In the thin film type optical path control apparatus according to the present invention of FIGS. 3, 4A and 4B, the membrane 570 and the mirror 610 are provided with an auxiliary layer 650 made of the same material as the mirror 610 under the membrane 570. The stress is uniformly distributed.

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

5a to 6d illustrate a method of manufacturing a thin film type optical path control device according to the present invention.

Referring to FIG. 5A, the driving substrate 510 includes M × N transistors (not shown) where M and N are integers, and a drain pad 520 is formed on one side.

The protective layer 530 is formed on the driving substrate 510. The protective layer 530 is formed to have a thickness of about 0.1 μm to 1.0 μm using phosphorus silicate glass (PSG) using a chemical vapor deposition (CVD) method. The protective layer 530 prevents the driving substrate 510 containing the transistor from being damaged during the subsequent process.

An etch stop layer 540 is formed on the passivation layer 530. The etch stop layer 540 is formed to have a thickness of about 1000 to 2000 GPa using a low pressure chemical vapor deposition (LPCVD) method. The etch stop layer 540 prevents the protective layer 530 and its lower portion from being damaged by the subsequent etching process.

The sacrificial layer 550 is formed on the etch stop layer 540. The sacrificial layer 550 is formed to have a thickness of about 0.1 to 1.0 μm of the silicate glass (PSG) by atmospheric chemical vapor deposition (APCVD). In this case, since the sacrificial layer 550 covers the upper portion of the driving substrate 510 in which the transistor is embedded, the surface flatness is very poor. Therefore, the surface of the sacrificial layer 550 is planarized by using a spin on glass (SOG) method or a chemical mechanical polishing (CMP) method.

Subsequently, the auxiliary layer 650 is formed of the same material as the material forming the mirror 610 that is subsequently formed on the sacrificial layer 550. In this case, the auxiliary layer 650 is formed to have the same thickness as the mirror 610. The auxiliary layer 650 is formed of the same material as the mirror 610 to uniformly distribute the stress generated between the membrane 570 and the mirror 610. Accordingly, the membrane 570 and the mirror 610 are prevented from being bent by the non-uniform stress because the uniform stress is applied by the auxiliary layer 650.

Subsequently, a supporting region of the actuator 640 may be formed by etching a portion of the auxiliary layer 650 and the sacrificial layer 550 in which the drain pad 520 is formed at the bottom to expose a portion of the etch stop layer 540. Make a part

Referring to FIG. 5B, a membrane material layer 570 ′ is formed on the exposed etch stop layer 540 and on the auxiliary layer 650. The membrane material layer 570 ′ is formed to have a thickness of about 0.1 μm to about 1.0 μm using a low pressure chemical vapor deposition (LPCVD) method. Subsequently, a lower electrode material layer 580 'is formed on the membrane material layer 570' using a metal such as platinum or platinum-tantalum. The lower electrode material layer 580 ′ is formed to have a thickness of about 0.1 μm to about 1.0 μm using a sputtering method.

A strained material layer 590 'is formed on the lower electrode material layer 580'. The deformable material layer 590 ′ has a piezoelectric material such as PZT or PLZT so as to have a thickness of about 0.1 μm to 1.0 μm using a sol-gel method, a sputtering method, or a chemical vapor deposition (CVD) method. Form. The strained material layer 590 ′ is phase shifted using a rapid heat treatment (RTA) method.

The upper electrode material layer 600 'is formed on the strained material layer 590'. The upper electrode material layer 600 ′ 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.

5C and 6A, after the first photoresist (not shown) is applied on the upper electrode material layer 600 ′ by spin coating, the upper electrode material layer 600 ′ is applied. The upper electrode 600 is formed by patterning the pattern to have a '-' shape. Next, after the first photoresist is removed, a second photoresist (not shown) is applied on the patterned upper electrode 600 and the strained material layer 590 'by spin coating, and then the strained material layer ( 590 ') is patterned to have a'-'shape slightly wider than that of the upper electrode 600 to form a strained layer 590. Subsequently, the second photo register is removed.

Next, after applying a third photoresist (not shown) on the strain layer 590 and the lower electrode material layer 580 ′ by spin coating, the lower electrode material layer 580 ′ is deformed layer 590. The lower electrode 580 is formed by patterning the substrate to have a '-' shape that is slightly wider than). Then, the third photoresist is removed.

5D and 6B, the strained layer 590, the lower electrode 580, the membrane material layer 570 ′, the etch stop layer 540, from the portion where the drain pad 520 is formed in the strained layer 590. After the protective layer 530 is sequentially etched to form the distribution hole 620, a drain pad 520 and a lower electrode (filled with metal such as tungsten, platinum, aluminum, or titanium) are filled in the distribution hole 620. The distributor 630 is formed to electrically connect the 580. The distributor 630 is vertically formed from the lower electrode 580 to the top of the drain pad 520 in the distribution hole 620.

5E and 6C, after applying a fourth photoresist (not shown) to the patterned lower electrode 580 and the distribution hole 620 by spin coating, the membrane material layer 570 ′ is applied. Patterned to form membrane 570. In this case, the membrane 570 is patterned in a 'c' shape in the supporting region, and patterned to have a rectangular flat plate shape in the driving region formed integrally therewith. That is, as shown in FIG. 6C, the membrane 570 has rectangular arms in the supporting region, and a rectangular flat plate having a larger area than the arms in the driving region. Next, the fourth photoresist is removed.

As such, after the fifth photoresist (not shown) is applied on the patterned membrane 570 by spin coating, the auxiliary layer 650 is patterned, so that 'c' is slightly wider than the membrane 570 in the supporting region. The auxiliary layer 650 has a ruler shape and has a rectangular flat plate shape in the same size as the membrane 570 in the driving region formed integrally therewith. That is, as shown in FIG. 12B, the auxiliary layer 650 has rectangular arms in the support region, and has a rectangular shape having a larger area than the arms in the driving region. Subsequently, a portion of the sacrificial layer 550 is exposed by removing the fifth photoresist.

5F and 6D, after depositing the mirror 610 on the membrane 570 of the driving region having a rectangular shape, the sacrificial layer 550 is removed with hydrofluoric acid to form an air gap 560. This completes the thin film type optical path control device.

As described above, the thin film type optical path control device according to the present invention forms an auxiliary layer of the same material as the mirror constituting the lower part of the membrane, so that the stress between the auxiliary layer, the membrane and the mirror is symmetrically uniform along the vertical direction. Distribution makes it possible to prevent the membrane and mirror from bending.

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 (3)

A driving substrate 510 having M × N (M, N is an integer) transistors and a drain pad 520 formed on one side thereof; An auxiliary layer 650 formed on the driving substrate 510 in a 'c' shape having two arms in a support region, having a quadrangular shape in the driving region, and integrally formed with the arms; A membrane 570 having a smaller 'c' shape than the auxiliary layer 650 in the support region and a square shape having the same size as the auxiliary layer 650 in the driving region, and the membrane 570 in the support region. A lower electrode 580 having a smaller 'c' shape, a strained layer 590 having a smaller 'c' shape than the lower electrode 580 in the support region, and a lower layer 590 having a smaller 'c' shape than the lower electrode 580 in the support region, M × N actuators 640 each including an upper electrode 600 having a small 'c' shape; And Thin film type optical path control device including a mirror (610) formed on top of the membrane (570) having a rectangular shape of the drive area. The apparatus of claim 1, wherein the mirror (610) is made of aluminum and has a thickness of 0.1 to 1.0 μm. The apparatus of claim 1, wherein the auxiliary layer (650) is formed to have the same material and the same thickness as the mirror (610).

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