KR100782001B1 - Spatial optical modulator with a protective layer - Google Patents

Abstract

Board; An insulating layer on the substrate; A structure layer having a central portion spaced apart from the insulating layer by a predetermined distance; Located on the structure layer, the piezoelectric drive body for moving the central portion of the structure layer up and down; And a protective layer positioned on the piezoelectric driving body and including a first protective layer protecting the piezoelectric driving body. According to the present invention, it is possible to improve the operating characteristics of the piezoelectric drive body through the protective layer formed on the piezoelectric drive body, thereby maximizing the optical diffraction efficiency and reliability of the optical modulator element.

Optical modulator element, piezoelectric driver, protective layer.

Description

Spatial optical modulator with a protective layer

1 is a perspective view showing one embodiment of a piezoelectric type optical modulator element applicable to a preferred embodiment of the present invention.

Figure 2 is a perspective view showing another form of the piezoelectric optical modulator device applicable to the preferred embodiment of the present invention.

3 is a plan view of an array of optical modulator elements composed of the optical modulator elements of FIG.

4 is a view for explaining a principle of light modulation in the optical modulator element array of FIG.

Figure 5 is a perspective view showing the structure of an optical modulator element having a protective layer according to an embodiment of the present invention.

6 is a cross-sectional view showing the structure of a protective layer in the optical modulator element shown in FIG.

FIG. 7 is a cross-sectional view illustrating a process of manufacturing the optical modulator device having the protective layer shown in FIG. 5. FIG.

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

110: substrate 120: insulating layer

130: sacrificial layer 140: structure layer

150: piezoelectric drive body 151: lower electrode

152: piezoelectric layer 153: upper electrode

160: protective layer 160a: first protective layer

160b: second protective layer

The present invention relates to a MEMS structure and a method of manufacturing the same, and more particularly, to an optical modulator device and a method of manufacturing the same.

MEMS (Micro Electro Mechanical System) refers to a micro electromechanical system or device, and MEMS technology is a technology for forming a three-dimensional structure on a silicon substrate using semiconductor manufacturing technology. MEMS is applied to the optical field as one of various application fields. MEMS technology enables the fabrication of optical components smaller than 1mm, enabling ultra-compact optical systems. Micro-optical components such as optical modulator elements and micro lenses, which are miniature optical systems, have been adopted and applied to communication devices, displays, and recording devices due to advantages such as fast response speed, small loss, and ease of integration and digitization.

 An optical modulator element is a circuit or device for transmitting a signal to light (optical modulation) in a transmitter when a free space of an optical fiber or an optical frequency band is used as a transmission medium. The optical modulator element is divided into a direct method of directly controlling the on / off of light and an indirect method using reflection and diffraction of light, and the indirect method is divided into an electrostatic method and a piezoelectric method according to the method of being driven again.

In this case, the indirect optical modulator device performs the optical modulation through interference generated by the path difference of the reflected light reflected by the incident light regardless of the driving method. In particular, in the piezoelectric type optical modulator device, a path difference of reflected light is generated by using a driving force of a piezoelectric driver that contracts and expands according to a predetermined voltage applied (see description of FIGS. 3 and 4 to be described later). Therefore, in the piezoelectric optical modulator device, the role of the piezoelectric driver is particularly important for realizing optical diffraction characteristics.

However, according to the related art, as the manufacturing process of the optical modulator device proceeds, there is a problem in that the operating characteristics of the piezoelectric driving body are changed due to the influence of moisture absorption of the surrounding moisture. When the operating characteristics of the piezoelectric actuator are changed, the height (interval) between the ribbon and the insulating layer in the optical modulator element is also changed, and the optical diffraction characteristics and reliability of the entire optical modulator element are deteriorated by such a change in height. .

Accordingly, the present invention provides an optical modulator device and a method of manufacturing the same that can maximize the light diffraction characteristics and reliability thereof of the optical modulator device.

In addition, in order to prevent deterioration of the characteristics of the optical modulator device, an optical modulator device and a method of manufacturing the same that can minimize the malfunction of the piezoelectric drive body due to moisture absorption of the surroundings.

Other objects of the present invention will be readily understood through the following description.

According to an aspect of the invention, the substrate; An insulating layer on the substrate; A structure layer having a central portion spaced apart from the insulating layer by a predetermined distance; Located on the structure layer, the piezoelectric drive body for moving the central portion of the structure layer up and down; And a protective layer disposed on the piezoelectric driving body and including a first protective layer protecting the piezoelectric driving body.

In addition, the optical modulator device having a protective layer according to the present invention may further include a sacrificial layer positioned on the upper portion of the insulating layer and the lower portion of the structure layer, and supporting the structure layer. The sacrificial layer may be etched away from the insulating layer by a predetermined distance from the lower portion of the center portion of the structure layer.

In addition, the piezoelectric drive body of the present invention; A piezoelectric layer disposed on the lower electrode and contracting and expanding according to a predetermined voltage to generate vertical driving force in a central portion of the structure layer; And an upper electrode disposed on the piezoelectric layer and applying a predetermined voltage formed on the piezoelectric layer between the lower electrodes.

Here, the first protective layer may be made of an insulating material, and any one of Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , SiO ₂ , SiN, and SiBN may be used as the insulating material.

In addition, the optical modulator device having the protective film according to the present invention may further include a second protective layer positioned on the first protective layer and protecting the first protective layer.

Here, the second protective layer may be made of an insulating material, and any one of Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , SiO ₂ , SiN, and SiBN may be used as the insulating material.

Hereinafter, an optical modulator element having a protective layer according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings, wherein the same or corresponding components are denoted by the same reference numerals and overlapped therewith. The description will be omitted. In describing the present invention, when it is determined that the detailed description of the related well-known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, the piezoelectric optical modulator device applied to the present invention will be described first before describing preferred embodiments of the present invention.

1 is a perspective view showing one embodiment of a piezoelectric optical modulator device applicable to a preferred embodiment of the present invention, Figure 2 is a perspective view showing another embodiment of a piezoelectric optical modulator device applicable to a preferred embodiment of the present invention. to be.

1 and 2, a piezoelectric optical modulator device applied to the present invention includes a substrate 110, an insulating layer 120, a sacrificial layer 130, a structure layer 140, and a piezoelectric driver 150. It includes. In addition, a plurality of holes 140 (b) and 140 (d) are provided at the central portion of the structure layer 140. In this case, upper light reflection layers 140 (a) and 140 (c) may be formed on a central portion of the structure layer 140 in which holes are not formed, and lower light may be formed on the insulating layer 120 corresponding to the position of the holes. Reflective layers 120 (a) and 120 (b) may be formed. In addition, the piezoelectric driver 150 controls the structure layer 140 to move up and down in accordance with the degree of contraction or expansion of up and down or left and right caused by the voltage difference between the upper and lower electrodes.

In addition, each part of the optical modulator device will be described in detail in the description of FIG. 5 to be described later. In FIGS. 3 and 4, the optical modulation principle according to the height change between the structure layer 140 and the insulating layer 120 will be described. The explanation is centered.

3 is a plan view of an optical modulator element array including the optical modulator element of FIG. 1, and FIG. 4 is a view for explaining a principle of optical modulation in the optical modulator element array of FIG. 3. 4 is a cross-sectional view taken along line BB ′ of FIG. 3 as a reference line.

Referring to FIG. 3, the optical modulator element array includes the first pixel (pixel # 1), the second pixel (pixel # 2),. And m optical modulator elements 100-1, 100-2,..., 100-m that are responsible for the m-th pixel (pixel #m). The optical modulator element array is responsible for image information of a 1D image of a vertical scan line or a horizontal scan line (assuming that the vertical scan line or the horizontal scan line is composed of m pixels), and each optical modulator element 100-1, 100-2, ..., 100-m) are in charge of any one of m pixels constituting the vertical scan line or the horizontal scan line. Thus, the reflected and diffracted light in each optical modulator element is then projected onto the screen by a light scanning device in a two dimensional image. For example, in the case of VGA 640 * 480 resolution, 640 modulations are performed on one surface of an optical scanning device (not shown) for 480 vertical pixels, thereby generating one frame of one screen per surface of the optical scanning device. Here, the optical scanning device may be a polygon mirror, a rotating bar, a galvano mirror, or the like.

Hereinafter, the principle of light modulation will be described based on the first pixel (pixel # 1), but the same may be applied to other pixels.

In the present embodiment, as shown in FIG. 1, it is assumed that two holes 140 (b)-1 are formed in the structure layer 140. Due to the two holes 140 (b)-1, three upper light reflection layers 140 (a)-1 are formed on the structure layer 140. Two lower light reflection layers are formed in the insulating layer 120 to correspond to the two holes 140 (b)-1. In addition, another lower light reflection layer is formed on the insulating layer 120 to correspond to a portion of the gap between the first pixel (pixel # 1) and the second pixel (pixel # 2). Therefore, the number of upper light reflecting layers 140 (a) -1 and lower light reflecting layers 120 (a) -1 per pixel becomes the same, thereby modulating using zero-order diffraction light or ± first-order diffraction light. The brightness of the light can be adjusted.

Referring to FIG. 4, when the wavelength of light is λ, the distance between the structure layer 140 on which the upper light reflection layer 140 (a) is formed and the insulating layer 120 on which the lower light reflection layer 120 (a) is formed ( A first voltage is applied to the piezoelectric drive body 150 such that 2n) λ / 4 (n is a natural number) (see Fig. 4A). In this case, in the case of the zero-order diffracted light (reflected light), the total path difference between the light reflected from the upper light reflecting layer 140 (a) and the light reflected from the lower light reflecting layer 120 (a) is equal to nλ, which causes constructive interference. The diffracted light has maximum brightness. Here, in the case of + 1st and -1st diffraction light, the brightness of light has a minimum value due to destructive interference.

In addition, the distance between the structure layer 140 on which the upper light reflection layer 140 (a) is formed and the insulating layer 120 on which the lower light reflection layer 120 (a) is formed is (2n + 1) λ / 4 (n is a natural number. Is applied to the piezoelectric drive body 150 (see FIG. 4B). In this case, in the case of zero-order diffracted light (reflected light), the total path difference between the light reflected by the upper light reflecting layer 140 (a) and the light reflected by the lower light reflecting layer 120 (a) is (2n + 1) λ / As in 2, the destructive light has minimum luminance due to destructive interference. In the case of the + 1st and -1st diffracted light, the luminance of light has a maximum value due to constructive interference.

As a result of such interference, the optical modulator element can load a signal on light by adjusting the amount of reflected or diffracted light. In the above, the distance between the structure layer 140 on which the upper light reflection layer 140 (a) is formed and the insulating layer 120 on which the lower light reflection layer 120 (a) is formed is (2n) λ / 4 or (2n + 1). Although the case of λ / 4 has been described, it will be apparent that various embodiments capable of driving with an interval capable of adjusting the intensity interfered by diffraction or reflection of incident light may be applied to the present invention.

5 is a perspective view showing the structure of an optical modulator element having a protective layer according to an embodiment of the present invention. In FIG. 5 and below, an optical modulator device having a hole in a central portion of the structure layer 140 will be described. However, this is only an example and does not limit the scope of the present invention. That is, any optical modulator device including a piezoelectric drive body that contracts and expands in accordance with a voltage applied between electrodes in order to implement optical diffraction characteristics to generate a vertical driving force on a ribbon can be used in the present invention. Here, the ribbon is used as a generic term for a predetermined portion of the structure layer 140 that can be moved up and down by the driving force generated by the piezoelectric drive body 150, in this example, the center portion of the structure layer 140 This is the case here.

Referring to FIG. 5, the optical modulator device includes a substrate 110, an insulating layer 120, a sacrificial layer 130, a structure layer 140, a piezoelectric driver 150, and a protective layer 160.

The substrate 110 is a commonly used semiconductor substrate, and materials constituting the substrate 110 include silicon (Si), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), quartz, and silica (SiO). ₂ ) materials such as these may be used.

The insulating layer 120 is positioned on the substrate 110. The insulating layer 120 serves as an etch stop layer and is a material having a higher selectivity than an etchant for etching the material used as the sacrificial layer 130, where the etchant is an etching gas or an etching solution. Is formed. In this case, the material used as the insulating layer 120 may be silica (SiO ₂ ).

In this case, a lower light reflection layer (for example, 120 (a) of FIG. 1 or 120 (b) of FIG. 2) capable of reflecting or diffracting light may be formed on the insulating layer 120. The lower light reflecting layer may use various light reflecting materials, for example, metal materials (Al, Pt, Cr, Ag, etc.).

The sacrificial layer 130 is positioned on the insulating layer 120. In this case, a material such as silicon (Si) or polysilicon (Poly-Si) may be used as the sacrificial layer 130.

After the sacrificial layer 130 is stacked on the insulating layer 120, some or all of the sacrificial layer 130 may be etched through a process (see FIG. 7F) to be described later. By the etching process, the central portion of the structure layer 140 may be spaced apart by a predetermined interval while securing a driving space between the insulating layer 120 and the insulating layer 120. Here, the driving space means an empty space between the structure layer 140 and the insulating layer 120, the center portion of the structure layer 140, that is, the ribbon is the driving force of the piezoelectric drive body 150 through the secured drive space. It can move up and down correspondingly. In addition, the sacrificial layer 130 that is not removed through the etching process serves to support the structure layer 140.

Here, in the optical modulator device illustrated in FIG. 5, only a part of the sacrificial layer 130 is etched, so that the sacrificial layer 130 is positioned on both side ends of the insulating layer 120 to support the structure layer 140. The layer 130 may be etched in its entirety through a process to be described later (see FIG. 7F). In this case, the sacrificial layer 130 does not support the structure layer 140, but may only serve to secure a driving space in which the structure layer 140 may move up and down. That is, the position of the driving space secured corresponding to the etching process of the sacrificial layer 130 may vary. In addition, when the position of the secured driving space is changed, the position of the ribbon in the structure layer 140 may also be changed accordingly.

The structure layer 140 is positioned on the sacrificial layer 130. Here, as the structure layer 140, a material of silicon nitride series (Si _X N _Y ) such as Si ₃ N ₄ may be used.

In this case, an upper light reflection layer (for example, 140 (a) of FIG. 1 or 140 (c) of FIG. 2) capable of reflecting or diffracting light may be formed on the center portion of the structure layer 140, that is, the ribbon. have. The upper light reflecting layer may use various light reflecting materials, for example, metal materials (Al, Pt, Cr, Ag, etc.).

In addition, the structure layer 140 may be selectively formed to have a specific shape (in this example, having one or more holes in the center portion of the structure layer 140) through a process to be described later (see FIG. 7F). Can be etched. In this case, the upper light reflection layer is formed at a portion where the hole is not formed in the central portion of the structure layer 140.

The piezoelectric driver 150 is positioned on the structure layer 140. The piezoelectric drive member 150 generates a driving force for allowing the ribbon to move up and down according to the piezoelectric method.

The piezoelectric driver 150 is formed on the lower electrode 151 and the lower electrode 151, and contracts and expands when a predetermined voltage is applied to generate the up and down driving force. And an upper electrode 153 that is formed in the upper electrode 151 to apply a predetermined voltage formed in the piezoelectric layer 152 between the lower electrodes 151.

In this case, platinum (Pt), nickel (Ni), gold (Au), aluminum (Al), titanium (Ti), IrO ₂ , RuO _2, and the like may be used as electrode materials of the lower or upper electrodes 151 and 153. Any one of the above-described combinations of electrode materials may be used. The lower or upper electrodes 151 and 153 may be formed by a method such as sputtering or vacuum evaporation in the range of 0.01 to 3 μm.

The piezoelectric layer 152 may be formed on the lower electrode 151 in the range of 0.01 to 20.0 μm by wet (screen printing, Sol-Gel coating, etc.) and dry methods (sputtering, Evaporation, MOCVD, Vapor Deposition, etc.). As the piezoelectric layer 152, piezoelectric materials such as PZT, PNN-PT, PLZT, AlN, and ZnO may be used, and elements such as lead (Pb), zirconium (Zr), zinc (Zn), or titanium (Ti) may be used. It is also possible to use a piezoelectric electrolytic material comprising one or more.

The protective layer 160 is positioned on the piezoelectric driver 150 (in this example, the upper portion of the upper electrode 153). The protective layer 160 serves to protect the piezoelectric driver 150 from moisture absorption of the surrounding moisture. In this case, the protective layer 160 may be composed of a single film or a double film as necessary. The structure of the protective layer 160 according to the present invention will be described in detail with reference to FIG.

6 is a cross-sectional view illustrating a structure of a protective layer in the optical modulator device shown in FIG. 5. FIG. 6 is an enlarged view of portion A of FIG. 5, and FIGS. 6A and 6B show the protective layer 160 shown in FIG. 5 in more detail in the form of a single film or a double film.

Here, the protective layer 160 illustrated in FIGS. 6A and 6B is formed only on the upper electrode 153, but is also protected on the lower electrode 151 according to the shape of the piezoelectric driver 150. Of course, layer 160 may be formed. That is, when the piezoelectric driver 150 has a shape different from that of the optical modulator device illustrated in FIG. 5, for example, when the piezoelectric layer 152 is formed only on some surfaces of the lower electrode 151, It is apparent that the protective layer 160 may be formed on the upper portion of the electrode 153 as well as on the lower electrode 151 on which the piezoelectric layer 152 is not formed.

Referring to FIG. 6A, the protective layer 160 according to the exemplary embodiment of the present invention is composed of a single film (hereinafter, referred to as a 'first protective layer 160a').

Here, various dielectric materials such as Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , SiO ₂ , SiN, SiBN, and the like may be used as the first protective layer 160a. Particularly, among these insulating materials, Al ₂ O ₃ has a very good adhesion to the electrode, and is excellent in moisture absorption prevention function. Accordingly, by forming the first protective layer 160a using the above-described insulating material on the piezoelectric driver 150, the piezoelectric driver 150 may be absorbed from moisture absorption of ambient moisture generated in the manufacturing process of the optical modulator device or in actual driving. ) Can be protected.

At this time, as the deposition method of the first protective layer 160a, PVD (Physical Vapor Deposition) deposition methods such as sputtering deposition method, electron beam evaporation method (E-beam evaporation), MOCVD (Metal Organic CVD), PECVD CVD (Chemical Vapor Deposition) deposition method such as (Plasma Enhanced CVD) or ALD (Atomic Layer Deposition) deposition method and the like can be used.

Here, the sputtering deposition method of the PVD deposition method is deposited by using the kinetic energy of the sputtering gas (inert gas such as Ar, etc.) in the plasma state to adhere the deposition material to the substrate to be deposited. In the electron beam deposition method, a deposition material is melted by heating a substrate to be deposited using an electron beam and deposited on the substrate to be deposited.

In addition, the CVD deposition method is a method of mixing two or more deposition materials in a reaction chamber so that deposition (reaction) occurs on the surface of the substrate to be deposited. In this case, the MOCVD deposition method uses a solid or liquid deposition material in the form of a metal organic material, and the PECVD deposition method uses a deposition material in a plasma state.

In particular, the ALD deposition method alternates the chemical adsorption and desorption processes between the elements (hereinafter, referred to as 'sources') constituting the material to be deposited. A film can also be formed, which is an advantageous method for the deposition of ultra-thin films. The ALD deposition method sequentially injects a source (for example, aluminum (Al) and oxygen (O ₂ ) when the material to be deposited is Al ₂ O ₃ ) one by one so that a chemical reaction occurs on the surface of the substrate to be deposited. . For this reason, using the ALD deposition method, it is possible to deposit an ultrafine thin film corresponding to a monoatomic layer on a substrate to be deposited, and to form a film having a uniform thickness regardless of the area of the substrate to be deposited and the irregularities of the substrate to be deposited. . That is, there is an advantage in that a film made of a deposition material having excellent adhesion or coating property can be formed on the substrate to be deposited.

Therefore, by depositing the first protective layer 160a using any one of the above-described deposition methods including the ALD deposition method, the film (i.e., the piezoelectric driver 150) and the film made of the deposition material (i.e. That is, the adhesion between the first passivation layer 160a) may be improved, resulting in an interface problem between the substrate to be deposited and the deposition material, for example, the piezoelectric driver 150 and the first passivation layer 160a. It is possible to prevent the formation of voids in the boundary surface of the liver.

Referring to Figure 6 (b), the protective layer 160 according to another preferred embodiment of the present invention is a double layer (hereinafter referred to as 'first protective layer 160a', the upper layer of the double layer of the double layer) Film is referred to as a 'second protective layer 160b'. That is, the protective layer 160 illustrated in FIG. 6B is formed by further stacking the second protective layer 160b on top of the first protective layer 160a of FIG. 6A. will be.

In particular, when the first passivation layer 160a is deposited by ALD deposition, the thickness of the deposited first passivation layer 160a may be small and thus may not serve as the passivation layer 160. For example, the protective layer 160 composed of a single film has a reduced breakdown voltage, which is a reference point for breaking the insulating effect of the protective layer 160, or an unwanted leakage current in the protective layer 160. Problems such as an increase in leakage current may occur.

In this case, the operating characteristics of the piezoelectric driver 150 to be protected by the protective layer 160 also affects, and the degradation of the operating characteristics of the piezoelectric driver 150 is caused by the ribbon and the insulating layer (the optical modulator element). 120) results in a change in height of the gap between. In addition, the change in the height of the gap between the ribbon and the insulating layer 120 is a factor for reducing the optical diffraction efficiency of the entire optical modulator element.

Therefore, the protective layer 160 of FIG. 6B has a second protective layer 160b for protecting the first protective layer 160a on the first protective layer 160a in order to overcome the above-mentioned problem. By further laminating, a stronger protective layer 160 can be formed. In other words, the second protective layer 160b indirectly protects the piezoelectric driver 150 by protecting the first protective layer 160a which directly protects the piezoelectric driver 150.

Here, as the second protective layer 160b, various dielectric materials, for example, Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , SiO ₂ , SiN, SiBN, or the like may be used.

In this case, as the deposition method of the second protective layer 160b, various deposition methods including an ALD deposition method may be used in the same manner as in the first protective layer 160a of FIG. 6A, but the entire protective layer is deposited. Considering the thickness of the 160, physical vapor deposition, physical vapor deposition (PVD) deposition such as sputtering deposition, e-beam evaporation, metal organic CVD (MOCVD), plasma enhanced CVD (PECVD), etc. It is preferable to use CVD (Chemical Vapor Deposition) vapor deposition method or the like.

As described above, the present invention prevents a change in operating characteristics of the piezoelectric drive body 150 through the protective layer 160 formed on the piezoelectric drive body 150, and shortens the life of the piezoelectric drive body 150. You can prevent it. In addition, by improving the operating characteristics of the piezoelectric drive member 150 to prevent the change in the height of the gap between the ribbon and the insulating layer 120 in the optical modulator device, thereby maximizing the optical diffraction efficiency and reliability of the entire optical modulator device You can.

FIG. 7 is a cross-sectional view illustrating a manufacturing process of an optical modulator device having a protective layer illustrated in FIG. 5.

Referring to FIG. 7A, an insulating layer 120 is formed on the substrate 110. The insulating layer 120 serves as an etch stop layer.

Referring to FIG. 7B, a sacrificial layer 130 is formed on the insulating layer 120. Here, the sacrificial layer 130 may be etched in part or in whole so that the ribbon may secure a driving space through a later process (see FIG. 7F) and may be spaced apart from the insulating layer 120 by a predetermined distance. .

Referring to FIG. 7C, the structure layer 140 is formed on the sacrificial layer 130. The structure layer 140 may be selectively etched to form a specific shape (eg, a shape having one or more holes) through a later process (see FIG. 7F).

Referring to FIG. 7D, the piezoelectric driver 150 is formed on both side ends of the structure layer 140. The piezoelectric driver 150 stacks a lower electrode 151 on the structure layer 140, a piezoelectric layer 152 on the lower electrode 151, and an upper electrode 153 on the piezoelectric layer 152. ) And the upper electrode 153 and the piezoelectric layer stacked on portions except the upper electrode 153, the piezoelectric layer 152, and the lower electrode 151 stacked on both side ends of the structure layer 140. The 152 and the lower electrode 151 are formed by etching.

However, unlike the case of the optical modulator device illustrated in FIG. 7, the piezoelectric driver 150 may be formed on the front surface of the structure layer 140 instead of on both sides of the structure layer 140. Of course, one etching process may be unnecessary.

In addition, although not shown in FIG. 7, between the upper portion of the structure layer 140 and the lower portion of the lower electrode 151 in order to protect the upper portion of the structure layer 140 positioned on the lower surface thereof during the etching of the lower electrode 151. Forming a SiO ₂ layer of a certain thickness may be further included.

Referring to FIG. 7E, the protective layer 160 is formed on the piezoelectric driver 150. In this case, the protective layer 160 is formed of a single film composed of only the first protective layer 160a as described above (see FIG. 6A), or the first protective layer 160a and the second protective layer 160b. Can be formed into a double film (see FIG. 6B).

In this case, when the protective layer 160 is formed as a double layer, the first protective layer 160a is laminated on the piezoelectric driver 150, and then the second protective layer 160b is formed on the first protective layer 160a. ) Can be formed by laminating. Here, the process of laminating the second passivation layer 160b is preferably performed successively after the process of laminating the first passivation layer 160a, but may be performed after the step (f) of FIG. 7 to be described later. Of course there is.

In this case, when the protective layer 160 is formed of a single film, as the deposition method of the first protective layer 160a, PVD (Physical Vapor Deposition, Physical Evaporation, etc.), such as sputtering deposition and E-beam evaporation, may be used. Vapor Deposition (CVD) deposition, MOCVD (Metal Organic CVD), PECVD (Plasma Enhanced CVD), such as CVD (Chemical Vapor Deposition, Chemical Vapor Deposition) deposition or ALD (Atomic Layer Deposition) deposition method and the like can be used.

When the protective layer 160 is formed of a double film, the first protective layer 160a is formed by ALD deposition, and the second protective layer 160b is formed by sputtering deposition, electron beam evaporation, or the like. It is preferable to use PVD (Physical Vapor Deposition) deposition method or CVD (Chemical Vapor Deposition) deposition method such as MOCVD (Metal Organic CVD), PECVD (Plasma Enhanced CVD). However, the deposition method of the protective layer 160 is not necessarily limited thereto, and various deposition methods may be used.

Referring to FIG. 7F, the sacrificial layer 130 may be spaced apart from the insulating layer 120 by a predetermined space by an etchant (where the etchant is an etching gas or an etching solution) to secure a driving space. Some or all of them are etched so that they can be etched.

In this case, a process of selectively etching the structure layer 130 may be preceded by an etching process of the sacrificial layer 130. That is, in this example, an etching process of forming a plurality of holes in the ribbon is preceded by an etching process of the sacrificial layer 130, and in this case, the etching process of the sacrificial layer 130, which is subsequently performed, is a holo etchant formed in the ribbon. It can be done by the method of injecting.

As described above, according to the optical modulator element having the protective layer and the manufacturing method thereof according to the present invention, the adhesion between the piezoelectric driver and the protective layer can be improved by laminating the protective layer using ALD deposition or the like. Can be. Therefore, it is possible to prevent voids from being formed at the interface between the piezoelectric drive body and the protective layer, thereby reducing defects in operating characteristics of the piezoelectric drive body.

In addition, it is possible to minimize the malfunction of the piezoelectric drive body due to the ambient moisture absorption through the protective layer. Through this, it is possible to prevent deterioration of operating characteristics of the piezoelectric driving body and to prevent shortening of the life of the piezoelectric driving body.

In addition, by preventing the deterioration of the characteristics of the piezoelectric drive body, the height of the gap between the ribbon and the insulating layer in the optical modulator element can be kept constant, and the effect of maximizing the optical diffraction characteristics and reliability of the entire optical modulator element can be achieved. have.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

Claims (8)

Board; An insulating layer on the substrate; A structure layer having a central portion spaced apart from the insulating layer by a predetermined distance; Located on the structure layer, the piezoelectric drive body for moving the central portion of the structure layer up and down; And A first protective layer on the piezoelectric driving body and protecting the piezoelectric driving body Optical modulator device having a protective layer comprising a. The method of claim 1, Further comprising a sacrificial layer positioned on the upper portion of the insulating layer and the lower portion of the structure layer, and supporting the structure layer, The sacrificial layer has an optical modulator device having a protective layer to etch a portion located on the lower surface of the central portion of the structure layer to be spaced apart from the insulating layer by the predetermined interval. The method of claim 1, The piezoelectric drive body Lower electrode; A piezoelectric layer disposed on the lower electrode and contracting and expanding according to a predetermined voltage to generate a vertical driving force in a central portion of the structure layer; And An upper electrode disposed on the piezoelectric layer and applying the predetermined voltage formed in the piezoelectric layer between the lower electrodes; Optical modulator device having a protective layer comprising a. The method according to any one of claims 1 to 3, And the first protective layer has a protective layer made of an insulating material. The method of claim 4, wherein The insulating material is an optical modulator device having a protective layer of any one of Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , SiO ₂ , SiN and SiBN. The method according to any one of claims 1 to 3, And a protective layer on the first protective layer, the protective layer further comprising a second protective layer protecting the first protective layer. The method of claim 6, And the second protective layer has a protective layer made of an insulating material. The method of claim 7, wherein The insulating material constituting the second protective layer is an optical modulator device having a protective layer of any one of Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , SiO ₂ , SiN and SiBN.

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