KR100212538B1 - A fabrication method of thin film actuated mirror array - Google Patents

Abstract

The present invention relates to a method of manufacturing a thin film type optical path control device for improving the morphology of an upper electrode which is formed non-uniformly by an oxidation protrusion locally formed between an upper electrode layer and an upper adhesive layer constituting the upper electrode. Instead of being formed of titanium (Ti) or tantalum (Ta), it is formed of an oxide layer such as titanium oxide (Ti-Oxide) or tantalum oxide (Ta-Oxide) to form the surface of the upper metal layer or the upper metal layer and the upper adhesive layer. By preventing the formation of oxidation protrusions locally generated at the interface, the surface of the upper electrode serving as the mirror surface can be formed flat to manufacture a thin film type optical path control device having high thinning efficiency.

Description

Manufacturing method of thin film type optical path control device

1 is a cross-sectional view showing unit pixels of a general thin film type optical path control device.

2 is a cross-sectional view showing a part of an actuator of a general thin film optical path control device.

FIG. 3 shows oxidation projections appearing locally on the top electrode and the top adhesive layer of FIG.

4 (a) to 4 (j) are cross-sectional views sequentially illustrating a method of manufacturing an optical path adjusting apparatus according to the present invention.

* Explanation of symbols for main parts of the drawings

100: drive substrate 200: actuator

105: contact metal 205: plug metal

210: membrane 202: lower electrode

222: lower adhesive layer 224: lower metal layer

230: deformation portion 240: upper electrode

242: upper adhesive layer 244: upper metal layer

250: sacrificial layer 226: etching protective layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin film type optical path adjusting device used in a projection image display device, and in particular, a morphology of an upper electrode which is formed unevenly by an oxidation protrusion locally formed between an upper electrode layer and an upper adhesive layer constituting the upper electrode. It relates to a method of manufacturing a thin film type optical path control device for improving the.

In general, an image display device is classified into a direct view type image display device and a projection type image display device according to a display method.

The direct view type image display device includes a CRT (Cathode Ray Tube). The CRT image display device has a good image quality but has a problem such as an increase in weight and thickness as the screen is enlarged, and a price is expensive. There is.

Projection type image display apparatuses include a large crystal display (hereinafter referred to as an LCD), and such a large LCD can be thinned to reduce the weight. However, such LCDs have a high loss of light due to a polarizing plate, and thin film transistors for driving the LCD are formed for each pixel, so that there is a limit in increasing the aperture ratio (light transmission area).

On the other hand, a projection image display device using AMA separates white light emitted from a light source into red, green and blue light, and then changes the light path by driving an optical path adjusting device made of actuators. That is, the actuators are mounted on the actuators, and the actuators are individually driven to reflect the inclined mirrors, thereby changing the light path, thereby controlling the amount of light to project onto the screen. Therefore, an image appears on the screen.

In the above, the actuator tilts the mirror by using an electric field generated and deformed by a contact pressure to which a deformation part made of piezoelectric or electrodistoric ceramic is applied.

AMA is classified into one-dimensional AMA and two-dimensional AMA according to the driving method. The one-dimensional AMA has mirrors arranged in an M × 1 array, and the two-dimensional AMA has mirrors arranged in an M × N array.

Therefore, the projection type image display apparatus using the one-dimensional AMA pre-scans the M × 1 beams using the scanning mirror, and the projection image display apparatus using the two-dimensional AMA displays the image by projecting the M × N luminous fluxes.

In addition, the actuator is classified into a bulk type and a thin film type according to the shape of the deformable portion.

The bulk type thinly cuts a multilayer ceramic and mounts a ceramic wafer having a metal electrode formed therein on a driving substrate, and then processes a sawing, and mounts a mirror.

However, bulk actuators require a long process time because the actuators must be separated by sawing, and there is a problem that the response speed of the deformation part is slow. Therefore, a thin-film actuator that can be manufactured using a semiconductor process has been developed.

Meanwhile, a conventional general thin film type optical path adjusting device is as shown in FIG. 1, and as shown in FIG. 1, the conventional thin film type optical path adjusting device includes a silicon substrate 110 in which an active element (not shown) is formed in a matrix form. And a passivation layer 120 for preventing physical and chemical damage from active elements from the outside and an etch stop layer 130 for preventing the passivation layer 120 from being damaged by a subsequent etching process. An actuator in which the driving substrate 100, the membrane 210, the lower electrode 220, the deformable portion 230, and the upper electrode 240 are stacked in a predetermined shape to form a cantilever structure on the driving substrate 100. It consists of 200.

FIG. 2 is a cross-sectional view showing a part of the actuator 200 of the conventional thin film type optical path control device. As shown in the same figure, the upper electrode 240 includes the upper metal layer 244 and the upper adhesive layer 242. The lower electrode 220 is composed of a lower metal layer 224 and a lower adhesive layer 222. These adhesive layers are for enhancing the adhesion properties between the upper and lower metal layers and the respective lower layers, and tantalum (Ta) or titanium (Ti) is used as the material of the adhesive layers. On the other hand, platinum (Pt) is used for the material of the upper and lower metal layers.

However, tantalum (Ta) or titanium (Ti) forming the upper adhesive layer 242 has a high reactivity with the oxygen atom (O). Therefore, tantalum (Ta) or titanium (Ti) is a grain boundary of platinum (Pt) forming the upper metal layer 244 during the subsequent oxygen process (for example, reactive ion etching process). Reacts with oxygen atoms (O) that are diffused along the surface, and are local to the interface of the upper metal layer 244 and the upper adhesive layer 242 or the surface of the upper metal layer 244 as shown in FIG. As a result, an oxide protrusion of tantalum oxide (Ta-Oxide) or titanium oxide (Ta-Oxide) is formed, and these oxide protrusions have a poor surface morphology of the upper electrode 240 serving as a mirror surface of the thin film type optical path control device. In other words, the surface of the light path control device to reduce the light efficiency by making the surface uneven.

Accordingly, the present invention has been made to solve this problem, an object of the present invention is to form the upper adhesive layer of the upper electrode of tantalum oxide (Ta-Oxide) or titanium oxide (Ti-Oxide), the upper metal layer and the upper The present invention provides a method for manufacturing a thin film type optical path control device capable of increasing light efficiency by preventing oxidized protrusions from occurring at an interface between an adhesive layer or a surface of an upper metal layer, thereby improving the morphology of an upper electrode used as a mirror surface.

In order to achieve the above object, the manufacturing method of the thin film type optical path control apparatus according to the present invention is a membrane, a lower adhesive layer, a lower metal layer, a deformation on the top of a drive substrate having an active element, a passivation layer and an etch stop layer formed in a matrix form. A thin film type optical path control device for a projection image display device having an actuator formed of a layer, an upper adhesive layer, and an upper metal layer having a cantilever structure is manufactured, wherein the upper metal layer is formed of platinum (Pt), and the etching is performed. It is carried out in an oxygen atmosphere, the upper adhesive layer is formed of titanium oxide (Ti-Oxide) or tantalum oxide (Ta-Oxide).

In the present invention, the upper adhesive layer is also formed by chemical vapor deposition (CVD).

In the present invention, the upper adhesive layer is further formed to a thickness of 200 to 500 kPa.

Hereinafter, a method of manufacturing a thin film type optical path adjusting device according to the present invention will be described in detail with reference to the accompanying drawings, and for the sake of simplicity and convenience of description, the same reference numerals are given to the same components as those in the conventional configurations of FIGS. 1 to 3. I will use it.

First, referring to FIG. 4 (a), an active device (not shown) formed in a matrix structure on a silicon substrate by a semiconductor integrated circuit manufacturing process and the plurality of active devices under a high temperature atmosphere of a deposition process performed thereafter. A passivation layer for preventing chemical or physical damage from the outside and an etch stop layer made of a material having good corrosion resistance to prevent the passivation layer from being chemically damaged from an etching solution of an etching process performed by a subsequent process. After preparing a conventional driving substrate 100 similar to that shown in FIG. 1, phosphorus-containing silicon oxide (PSG) or polycrystalline silicon on top of the driving substrate 100 is subjected to physical vapor deposition (PVD) or chemical vapor deposition. A sacrificial layer 250 is formed by laminating to a predetermined thickness by a deposition process (CVD). Kinda.

Thereafter, the sacrificial layer 250 is formed into a predetermined shape having a pattern having a predetermined line width as shown in FIG. 4B by a fine pattern forming process. In this case, a part of the driving substrate 100 exposed through the pattern of the sacrificial layer 250 is provided as a place for forming the support portion and the bridge of the actuator 200.

Next, an insulating property is provided on the sacrificial layer 250 having a predetermined shape having a line width of a predetermined pattern on the driving substrate 100 and the driving substrate 100 exposed through the pattern of the sacrificial layer 250. An insulating material that is good as well as resistant to an etching solution, such as a hydrofluoric acid (HF) solution, is deposited by a chemical vapor deposition process (CVD) to a predetermined thickness as shown in FIG. To form. The insulating material constituting the membrane 210 is made of a metal or silicon nitride (SiN _x ) having excellent resistance to withstand brittleness due to fatigue stress when the actuator of the actuator 200 having the cantilever structure is repeatedly tilted.

On the other hand, on the membrane 210 in order to expose the metal pad 105 electrically connected to an active element (not shown) embedded in the driving substrate 100 by a contact hole forming process. A contact hole as shown is formed.

In the above, a part of the membrane 210 formed on the driving substrate 100 exposed through the pattern of the sacrificial layer 250 is a support of the actuator 200 formed in the cantilever structure as described above and such a support While acting as a base for forming a bridge for connecting the parts, a portion of the membrane 210 formed on the sacrificial layer 250 forms a drive part in which the actuator 200 is represented by a vertical displacement at a predetermined angle. Acts as a base for.

Thereafter, the contact hole penetrated from the membrane 210 to the metal pad 105 is not only conductive but also not damaged by subsequent thermal processes, and includes metal having platinum (Pt), titanium (Ti), or tantalum (Ta). Is filled in a process such as lift-off and the like, so that the plug metal 205 is formed as shown in FIG. 4E to be electrically connected to the lower electrode 220 to be formed by the subsequent process. do.

In addition, as shown in FIG. 4 (f), the lower adhesive layer 222 and the lower metal layer 224 are sequentially stacked on the membrane 210 to form the lower electrode 220. The lower metal layer 224 is intended to increase the adhesion property between the lower metal layer 224 and the membrane 210 and is made of titanium (Ti) or tantalum (Ta), which is a metal having good adhesion and good thermal properties. It is formed by vapor deposition by a sputtering process.

The lower metal layer 224 on the lower adhesive layer 222 is formed by laminating a conductive metal, such as platinum (Pt), to a predetermined thickness by a vacuum deposition process such as a sputtering deposition process. The lower electrode 220 including the lower adhesive layer 222 and the lower metal layer 224 is connected to the metal pad 105 of the driving substrate 100 by the plug metal 205 as described above. The lower electrode 220 is electrically connected to a plurality of active elements (not shown) embedded in the driving substrate 100. The lower electrode 220 is operated as a signal electrode for driving a subsequent actuator.

In this case, anisotropic etching of a portion of the lower electrode 220, part of the lower electrode 220 constituting a bridge (not shown) of the actuator 200, which is formed in a predetermined shape, is performed like a reactive ion etching process (RIE). Iso-cutting is formed to separate the electric signals flowing into the lower electrode 220 through the plurality of active elements in units of pixels by removing them by a dry etching process having good characteristics.

Subsequently, a portion of the membrane 210 exposed through the iso cutting part (not shown) and a ceramic material exhibiting piezoelectric properties on the upper portion of the lower electrode 220 are laminated to a predetermined thickness by a deposition process to deform the portion. The ceramic material forming the deformable portion 230 is formed of BaTiO ₃ , Pb (Zr, Ti) O ₃ , (Pb, La) (Zr, Ti) O _3, or a piezoelectric ceramic or Pb (Mg). , Nb) O ₃ composition, which is composed of a total distortion ceramic, and the deposition process is formed by a sputtering deposition process or a chemical vapor deposition process or a sol-gel process.

As described above, the deformable portion 230 laminated to a predetermined thickness is heat-treated by a high temperature heat treatment process, in particular, a rapid thermal annealing system, and as a result, the ceramic composition constituting the deformable portion 230. By forming the crystal structure of the Perovskite crystal structure, the deformable portion 230 exhibits a good piezoelectric property.

Thereafter, as shown in FIG. 4 (f), the upper adhesive layer 242 and the upper metal layer 244 are sequentially stacked on the deformable portion 230 to form the upper electrode 240. The upper adhesive layer 242 is to increase the adhesion property between the upper metal layer 244 and the deformation part 230. At this time, as described above, when titanium (Ti) or tantalum (Ta) is used as the material of the upper adhesive layer 242, since the reactivity between tantalum (Ta) or titanium (Ti) and the oxygen atom (O) is large, After the reaction between the tantalum (Ta) or titanium (Ti) and the oxygen atom (O) during the reactive ion etching process in the oxygen atmosphere, which is performed later, the interface between the upper metal layer 244 and the upper adhesive layer 242 or the upper metal layer ( On the surface of 244, an undesirable oxide protrusion of tantalum oxide (Ta-Oxide) or titanium oxide (Ti-Oxide) is formed. Therefore, in the present invention, the upper adhesive layer 242 is formed by stacking tantalum oxide (Ta-Oxide) or titanium oxide (Ti-Oxide) to a predetermined thickness by chemical vapor deposition.

The upper metal layer 244 on the upper adhesive layer 242 is formed by laminating a conductive metal, such as platinum (Pt), to a predetermined thickness by a vacuum deposition process such as a sputtering deposition process, which exhibits good conductivity and reflection characteristics. The upper electrode 240 formed of the upper adhesive layer 242 and the upper metal layer 244 serves as a common electrode for driving the actuator 200 and at the same time serves as a mirror surface of the actuator 200.

At this time, the upper electrode 240 composed of the upper adhesive layer 242 of tantalum oxide (Ta-Oxide) or titanium oxide (Ti-Oxide) and the upper metal layer 244 of platinum (Pt) is different from the conventional configuration described above. The surface of the upper electrode which acts as a mirror surface of the thin film type optical path control device does not have undesirable localized oxide projections at the interface between the upper metal layer 244 and the upper adhesive layer 242 or the surface of the upper metal layer 244. Since flat, the overall light efficiency of the thin film type optical path control device can be improved.

Subsequently, as shown in FIG. 4 (g), in order to form the actuator 200 formed of a plurality of layers on the driving substrate 100 in units of pixels, the upper electrode constituting the actuator 200 ( A portion of the sacrificial layer 250 is exposed by removing a portion of the 240, the deformable portion 230, the lower electrode 240, and the membrane 210 by a reactive ion etching (RIE) process.

On the other hand, such a reactive ion etching (RIE) process is performed by the etching action of the etchant (Etchant) consisting of CF ₄ or CHF ₃ under oxygen plasma.

Subsequently, referring to FIG. 4 (h), the sacrificial layer 250 remaining in a predetermined shape on the driving substrate 100 is etched to form the pixel-type actuator 200 in a cantilever structure. When removed by the etching protective film 260 on the outer surface of the actuator 200 to prevent the side of the actuator 200 is exposed to the etching solution to remove the plurality of layers constituting the actuator 200 ).

In this case, the etch protection layer 260 is formed by applying an insulating material to a predetermined thickness on the outer surface of the actuator 200 to completely block the exposed portion formed on the membrane 210 from the outside. The insulating material constituting the C) is composed of a photoresist (PR) having good corrosion resistance to an etching solution, particularly a hydrofluoric acid (HF) solution, used in an etching process.

Meanwhile, the sacrificial layer 250 exposed through the pattern of the actuator 200 is removed by an etching process in which isotropic etching characteristics are satisfactory as shown in FIG. 4 (i), but the etch stop in the driving substrate 100 is removed. Since the layer (not shown) remains intact, the passivation layer (not shown) provides good protection for the active element, and the etching solution used in the etching process may be formed of phosphorus constituting the sacrificial layer 250. The etching characteristics for the contained silicon oxide (PSG) consist of good hydrofluoric acid (HF) solution.

Thereafter, as shown in FIG. 4 (j) by a dry etching process such as an ion milling process, an etch protection layer 260 remaining on the upper electrode 240 of the actuator 200 at a predetermined thickness. ) Is removed to expose the upper electrode 240 so that it can act as a reflective surface of the actuator 200.

Therefore, when an electrical signal is applied to the upper electrode 240 of the actuator 200 through an active element embedded in the driving substrate 100 from an external control system, it is predetermined between the lower electrode 220 and the upper electrode 240. A potential difference of magnitude is generated, and the deformation part 230 represents piezoelectric deformation by the potential difference generation, thereby driving the plurality of actuators 200 individually.

That is, the white light of the light source incident on the surface of the upper electrode 240 serving as the reflecting surface is reflected along the light path changed by the driving of the actuator 200 to display an image on a screen not shown.

According to the present invention as described above, by forming the upper adhesive layer 242 of the upper electrode 240 made of tantalum oxide (Ta-Oxide) or titanium oxide (Ti-Oxide), unlike the conventional configuration, the upper metal layer 244 ) And the surface of the upper electrode which acts as a mirror surface of the thin film type optical path adjusting device because the surface of the upper adhesive layer 242 or the surface of the upper metal layer 244 does not have undesirable localized oxide projections. The overall light efficiency of the device can be improved.

The foregoing has merely described a preferred embodiment of the present invention with reference to the accompanying drawings, and those skilled in the art can make modifications and changes to the present invention without changing the gist of the invention described in the claims. Can be.

Claims (3)

Forming a sacrificial layer by stacking an insulating material having a predetermined thickness on an upper portion of a driving substrate including an active element, a passivation layer, and an etch stop layer formed in a matrix form, and partially patterning the sacrificial layer by a predetermined shape Forming a membrane by depositing an insulating material having a predetermined thickness on top of the driving substrate and the sacrificial layer exposed by partial removal of the sacrificial layer, and forming a contact hole in the membrane to form a contact metal. Exposing, forming a plug metal made of a conductive material in the contact hole, forming a lower adhesive layer having a predetermined thickness on the plug metal and the membrane, and lowering a predetermined thickness on the upper adhesive layer. Forming a metal layer, and forming a deformation part having a predetermined thickness on the lower metal layer. Forming an upper adhesive layer on the deformable part, forming an upper metal layer on the upper adhesive layer, and sequentially etching the upper metal layer, the upper adhesive layer, the deformable part, the lower metal layer, the lower adhesive layer, and the membrane. Forming an actuator on a pixel basis; applying an etch protective layer to the entire surface of the actuator; removing the sacrificial layer to form the actuator into a cantilever structure; and removing the etch protective layer. Through this, a thin film type optical path control device for a projection type image display device having an actuator having a plurality of layers formed in a cantilever structure on the driving substrate is manufactured, wherein the upper metal layer is formed of platinum (Pt), and the etching is performed by oxygen. In the manufacturing method of the said thin film type optical path control apparatus performed in atmosphere, The said top adhesion It is a method of producing a thin-film optical path control device which comprises a titanium oxide (Ti-Oxide) or tantalum oxide (Ta-Oxide). The method of claim 1, wherein the upper adhesive layer is formed by chemical vapor deposition (CVD). The thin film type optical path adjusting device according to claim 2, wherein the upper adhesive layer is formed to have a thickness of 200 to 500 kPa.