KR20000031348A - Thin film type device for adjusting optical path having two layer structure capable of easily realizing high definition - Google Patents

Abstract

PURPOSE: An adjusting device is to extend the number of unit pixel to an XGA(extended graphics array) grade while maintaining a length of actuator of unit pixel to the extent that does not affect a contrast. CONSTITUTION: In a device for adjusting optical path of thin film type having two layer structure wherein a unit pixel including a driving substrate, an actuator(65) connected to the driving substrate and having a cantilever shape supported at its one end, and a mirror surface(60) supported on a terminal end of the actuator is arranged in a matrix structure with M by N(wherein M and N are integer), the actuator comprises a pair of first driving end(65a) extending in one direction from one side thereof supported to the driving substrate, a connecting end(65c) connecting other side of the pair of first driving end, and at least one second driving end(65b) extending in the one direction from a given area of the connecting end, the mirror surface being supported on the given area of the second driving end.

Description

2-layer thin film type optical path control device for high resolution

The present invention relates to a two-layer thin film type optical path control apparatus and a method for manufacturing the same. More specifically, it is easy to implement a high resolution that can maintain the actuator length of a unit pixel so as not to affect the contrast while expanding the number of unit pixels. It relates to a layer structure thin film type optical path control device.

In general, a display device capable of forming an image by adjusting a light flux has a direct view type image display device such as a CRT (Cathod Ray Tube) or a projection type image display device according to a method of projecting a light beam incident from a light source on a screen. There is a liquid crystal display (hereinafter referred to as "LCD"), a DMD (Deformable Mirror Device), or AMA (Actuated Mirror Array).

Although CRT devices have excellent image quality, as the screen size increases, the weight and volume of the device increase, and the manufacturing cost thereof increases. In contrast, a liquid crystal display (LCD) can be formed of a flat plate, but the incident light flux Due to the polarization of the light having a low light efficiency of 1 to 2%, there was a disadvantage that the response speed of the liquid crystal material therein is slow.

In order to solve such LCD problems, a display 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.

The AMA is classified into a bulk type and a thin film type. Currently, AMA is a thin film optical path control device, and in particular, a thin film AMA is called a thin film micromirror array-actuated (hereinafter referred to as TMA).

Each of the actuators formed inside the TMA causes deformation depending on the electric field generated by the applied image signal and the 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.

1 is a cross-sectional view showing an example of a conventional two-layer thin film type optical path control device, Figure 2 is a cross-sectional view taken along the line A-A of FIG.

As shown in the drawing, the two-layer thin film type optical path control device applied in advance has a two-layer structure including a driving substrate 5 and an actuator 65 formed thereon and a mirror surface 60 formed on the actuator 65. This is easy.

The above-described actuator 65 includes a membrane 30, a lower electrode 35, a strained layer 40, and an upper electrode 45, and a drain pad (not shown in the drawing) of the driving substrate 5. The lower electrode 35 includes a via contact 55 to be electrically connected to the lower electrode 35.

The above-described mirror surface 60 is supported at its center by a post 75 formed at the center of the end of the membrane 30.

In the conventional thin film type optical path control apparatus, an image signal voltage is applied to the lower electrode 35, which is a signal electrode, and when a bias voltage is applied to the upper electrode 45, which is a common electrode, the upper electrode 45 and the lower electrode 35. An electric field is generated between them. The deformed layer 40 between the upper electrode 45 and the lower electrode 35 causes deformation by the electric field, and the deformed layer 40 contracts in a direction perpendicular to the electric field. Accordingly, the actuator 65 including the deformable layer 40 is bent at a predetermined angle, and the mirror surface 60 mounted on the driving tip of the actuator 65 is inclined by the bent membrane 30 to be incident from the light source. Reflect the light beam. The light beam reflected by the mirror surface 60 is projected onto the screen through the slit of the TMA optical system. Such a two-layer thin film type optical path control apparatus forms a unit pixel to form an image by forming a TMA module arranged in a matrix structure of M × N (M and N are integers).

On the other hand, the VGA (video graphics array) TMA module has a unit pixel count of 640 × 480.

However, as XGA (extended graphics array) TMA module is expanded to 1,024 × 768 unit pixel size, unit pixel size is about half smaller than VGA size pixel size.

That is, XGA class TMA module increases the number of unit pixels more than 2.56 times than VGA class TMA module, and pixel size and actuator size correspond to 1: 1 to form XGA class TMA module in VGA class TMA module. Therefore, as the size of the unit pixel is reduced, the length of the actuator is shortened.

However, when the length of the actuator is shortened by reducing the size of the unit pixel as described above, the driving angle becomes smaller in proportion to the length, thereby causing a problem of lowering the contrast.

Therefore, the present invention is to solve such a conventional problem, a two-layer structure that is easy to implement a high resolution of the shape that can maintain the actuator length of the unit pixel so as not to affect the contrast while extending the number of unit pixels to XGA class It is an object of the present invention to provide a thin film type optical path control device and a method of manufacturing the same.

The present invention for achieving the above object is a matrix structure of a unit pixel consisting of a drive substrate, an actuator electrically connected to the drive substrate and supported on one side thereof, having a cantilever shape, and a mirror surface supported at an end of the actuator. In the two-layer thin film type optical path control device arranged in M × N (M, N is an integer), the actuator is a pair of first drive stage extending in one direction from one side supported on the drive substrate and the first drive And a connection end for connecting the other side of the pair to each other, and at least one second driving end formed in the one direction from a predetermined portion of the connection end, wherein the mirror surface is supported at a predetermined portion of the second driving end. It is done.

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 perspective view of a conventional two-layer thin film type optical path control device,

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

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

4 is a cross-sectional view taken along line BB ′ of FIG. 3.

<Explanation of symbols for main parts of the drawings>

5; Drive substrate 10; Drain pad

25; First air gap 30; Membrane

35; Lower electrode 40; Strained layer

45; Upper electrode 55; Via Contact

60; Mirror surface 65; Actuator

70; 2nd air gap

Hereinafter, with reference to the accompanying drawings it will be described in detail a two-layer structure thin film type optical path control device easy to implement a high resolution according to the present invention.

Figure 3 is a plan view showing a planar shape of a two-layer thin film type optical path control device easy to implement a high resolution according to the present invention, Figure 4 is a cross-sectional view taken along line BB 'of FIG.

The two-layer thin film type optical path control apparatus according to the present invention is intended to be applied to an extended graphics array (XGA) class in which the number of pixels of a TMA module is standardized to 1,024 × 768.

It is well known that the XGA (extended graphics array) TMA module increases the number of unit pixels approximately 2.56 times more than the video graphics array (VGA) TMA module having 640 x 480 unit pixels.

The two-layer structure of the optical path adjusting device, which is easy to implement high resolution according to the present invention, includes a driving substrate 5, an actuator 65 electrically connected to the driving substrate 5 and supported on one side thereof, and having a cantilever shape. The unit pixels formed of the mirror surface 60 supported at the end of the actuator 65 are arranged in M × N (M and N are integers) in a matrix structure.

In particular, as shown in FIGS. 3 to 4, the actuator 65 includes a pair of first driving stages 65a extending in one direction from one side supported by the driving substrate 5, and the first driving stage ( 65a) a connection end 65c connecting the other side of the pair to each other, and at least one second drive end 65b formed in one direction from a predetermined portion of the connection end 65c, and the second drive end ( 65b) is characterized in that the mirror surface 60 is supported.

Here, the length of the mirror surface is (l _m ), the length of the first driving stage is (l _a1 ), and the length of the second driving stage is (l _a2 ).

Substantially, the length of the length of the mirror surface (l _m) and the second drive stage (l _a2) has a similar length, size of a unit pixel is defined by the length of the mirror surface (l _m).

According to the present invention, the drive length of the actuator 65 is the length l _a1 of the first drive stage 65a + the length l _a2 of the second drive stage 65b, and thus the length of the mirror surface 60. It is easier to implement the length extending by the length l _a2 of the second drive end 65b than l _m .

This is because the second drive end 65b of the actuator 65 is inserted into the recess 67 'of the first drive end 65a' of the other actuator 65 'adjacent to the second drive end 65b. This is because the first drive end 65a 'of the other actuator 65' is overlapped.

As described above, according to the present invention, the length of the actuator 65 and the size of the unit pixel may have a ratio of about 2: 1.

Such a feature of the present invention is to reduce the size of the unit pixel by about half while maintaining the length of the actuator applied to the conventional VGA-class TMA module to implement an XGA-class TMA module that increases the number of unit pixels approximately 2.56 times or more do.

On the other hand, as shown in Figure 4, the driving substrate 5 is a drain pad 10 formed on one side of the substrate containing M × N (M, N is an integer) transistor (not shown in the figure) is embedded , An etch stop layer 20 formed of an in-silicate glass (PSG) material laminated on top of the substrate and a drain pad (not shown in the drawing), and a nitride layer stacked on the passivation layer 15. It includes.

The protective layer 15 prevents the transistor embedded in the driving substrate 5 from being damaged by a subsequent process.

The etch stop layer 20 prevents the driving substrate 5 and the protective layer 15 from being damaged by an etch process that proceeds to a subsequent process.

The first air gap 25 is formed through the formation and etching of the first sacrificial layer (not shown).

The actuator 65 has a cantilever shape in which one side is supported by the first air gap 25. The actuator 65 includes a membrane 30 made of nitride, a lower electrode 35 made of a metal such as platinum having excellent electrical conductivity, a platinum-tantalum metal, a strained layer 40 made of a piezoelectric material such as PZT or PZLT, and aluminum, The upper electrode 45 made of platinum or silver is sequentially formed.

As described above, the actuator 65 has a recess 67 formed at a side surface at which the first driving end 65a is supported by the driving substrate 5, and the other actuator adjacent to the second driving end 65b is formed. Inserted into the recess 67 'of the first drive end 65a' of 65 ', the second drive end 65b overlaps with the first drive end 65a' of the other actuator 65 'adjacent to it. It is formed to be.

A via contact 55 is formed at one end of the actuator 65 supported by the driving substrate 5 to electrically connect the drain pad 10 and the lower electrode 35 by a lift-off process.

At the end of the second drive end 65b of the actuator 65, a mirror surface 60 is formed, the center of which is supported by the post 75. As shown in FIG. The second air gap 70 is formed through the formation and etching process of the second sacrificial layer (not shown).

The size of the mirror surface 60 is about half the length of the actuator 65 because the second drive end 65b overlaps with the neighboring actuator 65.

In the above description, it should be understood that those skilled in the art can make modifications and changes to the present invention without changing the gist of the present invention as it merely illustrates a preferred embodiment of the present invention.

As described above, according to the present invention, it is possible to obtain an effect of maintaining the actuator length of the unit pixel to the extent that the unit pixel number is extended to XGA level but does not affect the contrast.

Claims (1)

A unit pixel consisting of a driving substrate, an actuator electrically connected to the driving substrate and supported on one side thereof, having a cantilever shape, and a mirror surface supported at the end of the actuator, has a matrix structure M × N (M and N are integers). In the two-layer thin film type optical path control device arranged in pieces, The actuator may include a pair of first driving ends extending in one direction from one side supported by the driving substrate, a connection end connecting the other side of the pair of first driving ends to each other, and at least one portion formed in the one direction from a predetermined portion of the connection end. A two-layer thin film type optical path control device, comprising one or more second driving stages, wherein the mirror surface is supported at a predetermined portion of the second driving stage.