KR100795012B1 - MEMS having electrodes consisting of multiple layers and manufacturing method thereof - Google Patents

Abstract

The present invention is a substrate; An insulating layer on the substrate; A structure layer, the center portion of which is spaced apart at a predetermined interval so as to secure a driving space between the insulating layer and the movable layer, which can move up and down through the driving space; A lower electrode positioned on the structure layer; A piezoelectric layer disposed on the lower electrode, the piezoelectric layer generating a driving force to contract and expand according to a predetermined voltage so that the central portion of the structure layer may move up and down; And an upper electrode disposed on the piezoelectric layer and applying a predetermined voltage formed between the lower electrodes to the piezoelectric layer, wherein the lower electrode or the upper electrode is formed of a plurality of layers having different crystal distributions for each layer, and It relates to a manufacturing method. According to the present invention, an electrode film having a small characteristic deterioration due to stress or the like can be formed even in a subsequent high temperature device fabrication process through an electrode film formation process in which a plurality of layers having different crystal distributions are stacked. There is an effect that can prevent the deterioration of the characteristics of the entire structure, and maximize its reliability.

MEMS structure, piezoelectric drive body, bottom electrode, crystal distribution.

Description

MEMS having electrodes consisting of multiple layers and manufacturing method

1 is a perspective view showing a general structure of the optical modulator element of the MEMS structure used in the present invention.

Figure 2 is a cross-sectional view showing the structure of an electrode film having a different crystal distribution for each layer according to an embodiment of the present invention.

3 is a table showing a method of controlling the crystal distribution of each layer of the electrode film.

4 is a cross-sectional view illustrating a process of manufacturing a MEMS structure including an electrode having a different crystal distribution for each layer according to an exemplary embodiment of the present invention.

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

110: substrate

120: insulation layer

130: sacrificial layer

140: structure layer

150: piezoelectric drive body

151: lower electrode

152: piezoelectric layer

153: upper electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to MEMS structures and methods of fabricating the same, and in particular, to optical modulator devices manufactured using semiconductor processes.

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 structures (elements) require floating portions to be able to swing on the substrate for mechanical operation. 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. Hereinafter, the optical modulator device of the MEMS structure will be described.

 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 device is largely 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.

The optical modulator element necessarily requires an electrode for generating a driving force regardless of its driving method. That is, in the case of the electrostatic method, a driving force capable of mechanically moving according to a predetermined voltage applied between the common electrode located on the substrate side and the driving electrode spaced apart from the common electrode (electrostatic attraction or electrostatic force between the electrodes in the electrostatic method). In the case of the piezoelectric method, and generates a driving force (in the piezoelectric method, the contraction or expansion force of the piezoelectric layer) according to a predetermined voltage applied between the upper and lower electrodes positioned on the upper and lower parts of the piezoelectric layer. do. Therefore, in order to improve the optical diffraction efficiency of the optical modulator device, the film characteristics of the electrode should be maximized.

However, the electrode has a problem in that the stress of the electrode film is greatly increased while the device manufacturing process proceeds after the electrode film formation process. In particular, in the case of the piezoelectric method, the stress of the lower electrode film is greatly increased while undergoing a high temperature rapid thermal annealing (RTA) during the deposition of the piezoelectric layer that is performed after the lower electrode film formation process. The stress of the electrode film causes a hillock phenomenon or a delamination phenomenon on the electrode film, resulting in deterioration of characteristics of the piezoelectric actuator as well as the electrode. The degradation of the characteristics of the piezoelectric driving body adversely affects the optical diffraction characteristics of the optical modulator device, and has a problem of deteriorating the reliability of the optical modulator device.

Accordingly, the present invention has been made to solve the above problems, and provides a MEMS structure with a small stress change of the electrode film even in a high temperature device fabrication process performed after the electrode film formation process and a method of manufacturing the same.

In addition, the present invention provides a MEMS structure and its manufacturing method capable of maximizing optical diffraction characteristics and reliability thereof in an optical modulator device.

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, the center portion of which is spaced apart at a predetermined interval so as to secure a driving space between the insulating layer and the movable layer, which can move up and down through the driving space; A lower electrode positioned on the structure layer; A piezoelectric layer disposed on the lower electrode, the piezoelectric layer generating a driving force to contract and expand according to a predetermined voltage so that the central portion of the structure layer may move up and down; And an upper electrode disposed on the piezoelectric layer and applying a predetermined voltage formed between the lower electrodes to the piezoelectric layer, wherein the lower electrode or the upper electrode includes a plurality of layers having different crystal distributions for each layer. can do.

In addition, the MEMS structure according to the present invention is formed on the upper portion of the insulating layer and the lower portion of the structure layer, the portion located on the lower surface of the center portion of the structure layer is etched to secure a driving space, and the sacrificial layer for supporting the structure layer It may further include. In this case, the insulating layer serves as an etch stop layer during the etching of the sacrificial layer.

Here, the plurality of layers constituting the lower electrode or the upper electrode may be configured such that the grain size of the crystal is larger as the upper layer, or conversely, the grain size of the crystal is smaller as the upper layer.

Here, the plurality of layers constituting the lower electrode or the upper electrode may be configured to have a higher density as the upper layer, or, conversely, to have a lower density as the upper layer.

According to another aspect of the invention, (a) forming an insulating layer on the substrate; (b) forming a sacrificial layer on the insulating layer; (c) forming a structure layer on the sacrificial layer; (d) forming a bottom electrode on the structure layer; (e) forming a piezoelectric layer on the lower electrode to contract and expand in response to a predetermined voltage to generate a vertical driving force; (f) forming an upper electrode on the piezoelectric layer to apply a predetermined voltage formed in the piezoelectric layer between the lower electrodes; And (g) etching the sacrificial layer to form a drive space between the insulating layer and the central portion of the structure layer and to be spaced at a predetermined interval, wherein the lower electrode in step (d) or the upper in step (f) The electrode may provide a method of manufacturing a MEMS structure, which is formed of a plurality of layers having different crystal distributions for each layer.

Here, the crystal distribution may be different for each layer by adjusting the size of the crystal grains or the density of the film.

Further, in step (d) the lower electrode or in step (f) the upper electrode is formed by sputtering deposition, the crystal distribution of which is caused by adjusting the pressure of the sputtering gas or by pulling the sputtered particles in the direction of the substrate plate. By adjusting the bias power that controls the degree of loss, it can be different from floor to floor.

The following merely illustrates the principles of the invention. Therefore, those skilled in the art, although not explicitly described or shown herein, can embody the principles of the present invention and invent various methods and apparatus using the same that are included in the concept and scope of the present invention. In addition, it is to be understood that all detailed descriptions, including the principles, aspects, and embodiments of the present invention, as well as listing specific embodiments, are intended to include structural and functional equivalents.

In describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Numbers (eg, first, second, etc.) used in the description of the present specification are merely identification symbols for sequentially distinguishing identical or similar entities.

Hereinafter, with reference to the accompanying drawings will be described in detail a MEMS structure and a method for manufacturing the same according to a preferred embodiment of the present invention, the present invention is a driving method (for example, electrostatic method or piezoelectric method of the MEMS structure (element) It can be applied regardless of the type)-will be described below with reference to the optical modulator device of the piezoelectric MEMS structure (element).

1 is a perspective view showing the general structure of the optical modulator element of the MEMS structure used in the present invention. In the drawings below Figure 1 will be described with reference to the optical modulator device having an open hole in the central portion of the structure layer to be described later, but this is only an example and does not limit the scope of the invention. That is, the present invention shrinks and expands in accordance with the voltage applied between electrodes in order to realize the optical diffraction characteristics, so that the ribbon can move a predetermined portion of the structure layer which can be moved up and down by the driving force generated by the piezoelectric driving body. Any term may be used in the present invention as long as the optical modulator element includes a piezoelectric driver for generating a vertical driving force.

Referring to FIG. 1, the optical modulator device includes a substrate 110, an insulating layer 120, a sacrificial layer 130, a structure layer 140, and a piezoelectric driver 150.

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 ) and the like, and the bottom surface and the upper layer of the substrate may be formed using different heterogeneous materials.

The insulating layer 120 is formed on the substrate 110. The insulating layer 120 serves as an etch stop layer, and has a high selectivity with respect to an etchant (in which the etchant is an etching gas or an etching solution) for etching the material used as the sacrificial layer 130. Is formed. In this case, the material used as the insulating layer 120 may be silica (SiO ₂ ).

In this case, a light reflection layer (hereinafter, referred to as a “lower mirror”) that may reflect or diffract light may be formed on the insulating layer 120. When the lower mirror (not shown) is formed on the insulating layer 120, various light reflecting materials, for example, metal materials (Al, Pt, Cr, Ag, etc.) may be used as the lower mirror (not shown).

The sacrificial layer 130 is formed on the insulating layer 120. 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 later process (see FIG. 4G). In the subsequent etching process, the center portion of the insulating layer 120 and the structure layer 140 to be described later is a driving space (where the driving space means a space for allowing the center portion of the structure layer 140 to move up and down). It secures and can be spaced at predetermined intervals. In this case, the material used as the sacrificial layer 130 may be silicon (Si) or polysilicon (Poly-Si).

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

In this case, a light reflection layer (hereinafter referred to as an “upper mirror”) capable of reflecting or diffracting light may be formed on the center portion of the structure layer 140, that is, the ribbon, and various light reflections as the upper mirror (not shown). Materials For example, metal materials (Al, Pt, Cr, Ag, etc.) may be used.

 In the optical modulator device illustrated in FIG. 1, only a part of the sacrificial layer 130 is etched so that both side ends of the structure layer 140 are supported by the sacrificial layer 13. Although the ribbon is confined to the central portion of the structure layer 140, as the position of the drive space where the sacrificial layer 130 is fully etched or secured varies, the position of the ribbon in the structure layer 140 may also change accordingly. Of course. However, in the following description, the center portion of the structure layer 140 will be abbreviated as a ribbon by limiting the case of the optical modulator device illustrated in FIG. 1.

In addition, the structure layer 140 may be selectively etched to form a specific shape (in this example, having a plurality of open holes in the ribbon) through a later process (see FIG. 4G).

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

The piezoelectric driving body 150 is formed on the lower electrode 151 and the lower electrode 151, and when the predetermined voltage is applied, the piezoelectric driving body 150 contracts and expands to generate vertical driving force. The upper electrode 153 is formed on the lower electrode 151 and applies a predetermined voltage formed on the piezoelectric layer 152 between the lower electrodes 151. That is, when a predetermined voltage is applied to the lower electrode 151 and the upper electrode 153, the piezoelectric layer 153 contracts and expands to generate vertical movement of the ribbon. In this case, the total path difference between the light reflected from the ribbon and the insulating layer 120 may vary according to the height of the gap between the ribbon on which the upper mirror is formed and the insulation layer 120 on which the lower mirror is formed.

That is, when the wavelength of the light is λ, the distance between the ribbon on which the upper mirror is formed and the insulating layer 120 on which the lower mirror is formed in the state in which the optical modulator element is not deformed (no voltage is applied) is λ / Same as 2. Therefore, in the case of zero-order diffracted light, the total path difference between the ribbon and the light reflected from the insulating layer 120 is equal to λ so that light interferes constructively.

In addition, when a predetermined voltage is applied to the piezoelectric driver 150, the interval between the ribbon on which the upper mirror is formed and the insulating layer 120 on which the lower mirror is formed is equal to λ / 4. Therefore, in the case of zero-order diffracted light, the total path difference between the ribbon and the light reflected from the insulating layer 120 is equal to λ / 2, so that light interferes with each other. Through the above-described process, the optical modulator device performs light modulation by diffracting and interfering incident light to load a signal on light.

2 is a cross-sectional view showing the structure of an electrode film having a different crystal distribution for each layer according to an exemplary embodiment of the present invention. FIG. 2 is an enlarged view of a portion A (ie, the structure layer 140, the lower electrode 151, the piezoelectric layer 152, and the upper electrode 153) of FIG. 1. However, in FIG. 2, the structure of the electrode film according to the present invention is described by taking the case of the lower electrode 151 as an example, and the portion corresponding to the lower electrode 151 of part A of FIG. 1 is larger than other portions. Doing. In addition, hereinafter, the lower electrode 151 composed of three layers is exemplified, but any electrode having two or more layers having different crystal distributions for each layer may be used regardless of the number of layers, and also applies to the upper electrode 153. It is easy to see that it is possible.

Hereinafter, a structure of an electrode film having a different crystal distribution for each layer according to the present invention will be described in detail with reference to FIGS. 2A to 2C, but the overlapping contents in each example will be omitted.

Referring to FIG. 2A, the lower electrode 151 has a total of three layers (hereinafter referred to as 'first layer', 'second layer' and 'third layer' in order from the layers constituting the lower part). It consists of. Herein, 'layer' refers to an array of one or more rows in which crystal grains have the same crystal distribution, and also having the same crystal distribution means the conditions of various crystal distributions, for example, the types of crystal grains constituting the electrode film, It means that the size of crystal grains, the density (density) of a film | membrane, etc. are the same. That is, when any one of the above conditions is different, even if the arrangement stacked in a single column constitutes a separate layer, on the contrary, when all of the above conditions are the same, it is regarded as configuring the same layer even when stacked in several rows. In addition, circles having various sizes shown in the drawings represent crystal particles having various sizes, respectively, and do not limit the shape.

In the case of (a) of FIG. 2, there are three arrays each having different sizes of crystal grains, one row, and the three arrays constitute first to third layers, each of which is a separate layer. That is, the lower electrode 151 is composed of three layers, and as the size of crystal grains increases toward the upper layer, the lower electrode 151 has a different crystal distribution for each layer. As described above, the electrode film according to the present invention is composed of a plurality of layers having different crystal distributions for each layer, and various methods such as sputtering and e-beam evaporation may be used when forming the electrode. Detailed description thereof will be provided later with reference to FIG. 3.

Referring to FIG. 2B, unlike the case of FIG. 2A, the lower electrode 151 is composed of crystal particles having the same size. However, the spacing between the crystal grains in the arrangement in which the crystal grains are stacked varies from array to array. At this time, the spacing between crystal grains determines the density of the film. That is, the larger the gap between the crystal grains, the smaller the film density, and the smaller the gap between the crystal grains, the larger the film density.

Therefore, in the case of FIG. 2B, there are three arrays each having a different density from each other, and each of the three arrays constitutes the first to third layers. As a result, the lower electrode 151 is composed of three layers, and the density of the film increases as the upper layer increases, and thus, the lower electrode 151 has a different crystal distribution for each layer.

Referring to FIG. 2C, a total of three arrays in which the size of the crystal grains and the inter-crystal grain spacing (that is, the film density) differ from each other constitute the first to third layers. Accordingly, the lower electrode 151 is composed of three layers. In the case of FIG. 2C, the lower electrode 151 has a different crystal distribution for each layer as the size of the crystal grains and the film density increase toward the upper layer.

In (a) to (c) of FIG. 2, the electrode is made of a single material (that is, the types of crystal grains are the same), but it is explained that different crystal distributions are made by different kinds of crystal grains constituting the electrode. You can also have In addition, although not illustrated in the present example, it is a matter of course that the electrode film can be made to have a different crystal distribution by making the upper layer the smaller the size of the crystal grains or the film density, if necessary.

3 is a table illustrating a method of controlling the crystal distribution of each layer of the electrode film. 3 is a table in which platinum (Pt) is used as an electrode material, and the sputtering method is used as an electrode vapor deposition method. Before describing the table shown in FIG. 3, the terminology used for the sputtering deposition method and the table will be briefly described.

Sputtering is a kind of physical vapor deposition (PVD), and depositing material (hereinafter referred to as 'target material') is deposited using kinetic energy of a sputtering gas (which is an inert gas such as Ar) in a plasma state. Vapor deposition by sticking to the substrate. The deposition process in the sputtering method is made into a vacuum state by applying a high voltage in a chamber containing a target plate (hereinafter referred to as a "target plate") and a substrate plate covered with a target material, and then inert gas in the vacuum chamber. For example, when argon (Ar) gas is injected, the argon (Ar) gas becomes a plasma state in a high voltage chamber. At this time, the high energy and ionized argon (Ar +) gas in the plasma state is accelerated to the target plate which is maintained as a cathode compared to the substrate plate, and the target material is separated from the target plate by the collision by argon ions (Ar +). Deposition is performed on the substrate plate.

Referring to the terminology used in the table of FIG. 3, 'Fix' refers to deposition conditions fixed during deposition of the sputtering method. In addition, the conditions fixed in common in FIGS. 3A and 3B include '1kw' and 'RT'. Here, '1kw' means that the power of the power supply (usually DC power is used for metal deposition) is fixed to 1kw, and 'RT' means that the temperature in the chamber is room temperature. '' Means the force of attracting sputtered particles (ie, the target material released by collision between argon ions (Ar +) and the target plate) in the direction of the substrate plate, which is a relative force formed between the target plate and the substrate plate. 'Ra' means the surface roughness of the electrode film to be laminated, that is, the surface roughness. There are various ways to measure the degree of unevenness on the surface, but the surface roughness in this table is the difference between the highest and lowest of each unevenness in the cross section of the surface cut perpendicular to it. Is the average of the numbers. In addition, 'stress' may also be applied to various measurement criteria, in this table is used to quantify the pressure applied to the surface of the electrode film. At this time, the value of 'stress' is a positive value means that the electrode film is subjected to a tensile stress (tensile stress). That is, this means that the surface of the electrode film is subjected to downward pressure, and the larger the value is, the deeper the concave surface of the film becomes. On the contrary, the negative value of 'stress' means that the electrode film is subjected to compressive stress. In other words, this means that the surface of the electrode film is subjected to upward pressure, and the larger the value is, the more the surface becomes convex upward.

Referring to (a) of FIG. 3, where the pressure of argon (Ar) gas is fixed at 10 mTorr, the surface roughness ('Ra' is increased by increasing 'Bias power' from 60W to 150W to 300W. ) Is reduced from 28.85Å-> 15.36Å-> 12Å, and the stress ('stress') is 1083.5Mpa-> 409.5Mpa-> -2095.8Mpa and the pressure value and direction are changing. In other words, the increase in the 'bias power' decreases the surface roughness (Ra), and at the same time the stress of the film is changed from the tensile direction to the compressive direction (i.e., the surface of the electrode film is convex gradually in a convex shape). To).

Here, the small value of the surface roughness 'Ra' generally means that the size of the crystal grains or the density of the film in the electrode film is increased. This is because as the size of the crystal grains increases or the density of the film increases, the voids in the film decrease, and as a result, the degree of irregularities on the surface of the film, that is, the surface roughness, will decrease. In addition, the change of the 'stress' of the film from the tensile direction to the compressive direction means that the density of the particles constituting the film is increased.

As a result, obtaining the desired surface roughness (Ra) and stress in the electrode film formation process properly adjusts the bias power. In this case, the bias power is a relative potential formed between the plates. You can do this by adjusting it. In addition, adjusting the surface roughness (Ra) and the stress (stress) also means that the size of the crystal grains or the film density in the electrode film can be selected by adjusting the bias power. That is, 'Bias power' may be increased when depositing an electrode film having a large crystal grain size or a film density, and conversely, 'Bias power' may be decreased when depositing an electrode film having a small crystal grain size or a film density.

Referring to (b) of FIG. 3, where 'Bias power' is fixed at 40 W, the surface roughness is reduced by reducing the pressure of argon (Ar) gas from 6 mTorr-> 3 mTorr-> 2 mTorr-> 1 mTorr. 'Ra') decreases from 18.18Å-> 13.35Å-> 11.2Å-> 8.55Å, and the stress ('stress') is 1061.9Mpa-> 478.9Mpa-> 123.1Mpa-> -431.9Mpa. And direction are changing. That is, the decrease in the pressure of argon (Ar) gas reduces the surface roughness (Ra), and at the same time the stress ('stress') is gradually convex in the compressive direction in the tensile direction (that is, the surface of the electrode film is concave). It shows how to change to).

As a result, in order to obtain desired surface roughness 'Ra' and 'stress' in the electrode film formation process as described above, the pressure adjustment of argon (Ar) gas is such that the pressure adjustment of such argon (Ar) gas is This can also be achieved by adjusting the amount of argon (Ar) gas that is injected into the vacuum chamber. Therefore, the pressure of argon (Ar) gas is reduced when depositing an electrode film having a large crystal grain size or film density, and conversely, when an electrode film having a small crystal size or film density is deposited, an argon (Ar) gas is reduced. You just need to increase the pressure.

Using the methods described with reference to FIGS. 3A and 3B, different crystals are formed by differently adjusting the bias power or the pressure of argon (Ar) gas on a layer-by-layer basis in stacking electrode films. It is possible to form an electrode composed of a plurality of layers having a distribution. Through this, an electrode corresponding to the stress of the electrode film (that is, the pressure value of the electrode film and the direction of the pressure) required in the high temperature device fabrication process can be formed, and as a result, the operating characteristics of the entire piezoelectric drive body 150 as well as the electrode. It can be improved. In addition, the characteristics and reliability of the entire optical modulator device may be improved by improving the operating characteristics of the piezoelectric driver 150.

4 is a cross-sectional view illustrating a process of manufacturing a MEMS structure including an electrode having a different crystal distribution for each layer according to an exemplary embodiment of the present invention.

Referring to FIG. 4A, an insulating layer 120 is formed on the substrate 110. The insulating layer 120 serves as an etch stop layer.

Referring to FIG. 4B, a sacrificial layer 130 is formed on the insulating layer 120. Here, the sacrificial layer 130 may be etched in part or all of the sacrificial layer 130 to be spaced apart by securing a driving space between the ribbon and the insulating layer 120 through a later process (see FIG. 4G). have.

Referring to FIG. 4C, the structure layer 140 is formed on the sacrificial layer 130. The structure layer 140 may be selectively etched to form a specific shape (for example, a shape having a plurality of open holes) through a later process (see FIG. 4G).

Referring to FIG. 4D, lower electrodes 151 are formed on both side ends of the structure layer 140. At this time, the lower electrode 151 is composed of a plurality of layers having a different crystal distribution for each layer as described above.

Referring to FIG. 4E, the piezoelectric layer 152 is formed on the lower electrode 151. As the piezoelectric layer 152, piezoelectric materials such as PZT, PNN-PT, PLZT, AlN, and ZnO may be used.

Referring to FIG. 4F, the upper electrode 153 is formed on the piezoelectric layer 152. In this case, like the lower electrode 151, the upper electrode 153 may be configured of a plurality of layers having different crystal distributions for each layer.

Here, the lower electrode 151, the piezoelectric layer 152, and the upper electrode 153 formed in FIGS. 4D to 4F may have the same amount of the structure layer 140 as in the MEMS structure illustrated in FIG. 4. It is not possible to form only on the side end, it may be formed on the front surface or a partial surface on the structure layer 140, depending on the structure of the MEMS structure used, of course.

Referring to FIG. 4G, the sacrificial layer 130 may be spaced at predetermined intervals by securing an operating space between the ribbon and the insulating layer 120 by an etchant (where the etchant is an etching gas or an etching solution). 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, the etching process is performed to form a plurality of open holes in the ribbon before the etching process of the sacrificial layer 130. In this case, a part of the sacrificial layer 130 may be etched through the formed holes. have.

As described above, according to the MEMS structure according to the present invention and a method for manufacturing the same, the characteristics of stress due to stress or the like in a subsequent high temperature device manufacturing process through an electrode film forming process of stacking a plurality of layers having different crystal distributions The deterioration of the electrode film can be formed, thereby improving the operating characteristics of the entire piezoelectric drive body.

In addition, through the improvement of the operating characteristics of the piezoelectric drive body there is an effect that can prevent the deterioration of the characteristics of the entire MEMS structure, and maximize its reliability.

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 (11)

Board; An insulating layer on the substrate; A structure layer, the center portion of which is spaced apart at a predetermined interval so as to secure a driving space between the insulating layer and movable up and down through the driving space; A lower electrode on the structure layer; A piezoelectric layer disposed on the lower electrode and configured to generate a driving force to contract and expand according to a predetermined voltage so that the central portion of the structure layer may move up and down; And Located on the piezoelectric layer, including an upper electrode for applying the predetermined voltage formed in the piezoelectric layer between the lower electrode, The lower electrode or the upper electrode is a MEMS structure consisting of a plurality of layers having a different crystal distribution for each layer. The method of claim 1, The sacrificial layer is formed on the upper portion of the insulating layer and the lower portion of the structure layer, and the portion located on the bottom surface of the central portion of the structure layer is etched to secure the driving space and to support the structure layer. , The insulating layer is a MEMS structure that serves as an etch stop layer during the etching of the sacrificial layer. The method of claim 1, The plurality of layers of the MEMS structure, characterized in that the larger the grain size of the upper layer. The method of claim 1, The plurality of layers of the MEMS structure, characterized in that the smaller the grain size of the upper layer. The method of claim 1, The plurality of layers are MEMS structure, characterized in that the higher the upper layer. The method of claim 1, The plurality of layers of the MEMS structure, characterized in that the lower the density. (a) forming an insulating layer on the substrate; (b) forming a sacrificial layer on the insulating layer; (c) forming a structure layer on the sacrificial layer; (d) forming a lower electrode on the structure layer; (e) forming a piezoelectric layer on the lower electrode to contract and expand according to a predetermined voltage to generate a vertical driving force; (f) forming an upper electrode on the piezoelectric layer to apply the predetermined voltage formed in the piezoelectric layer between the lower electrodes; And (g) etching the sacrificial layer to form a drive space between the insulating layer and the central portion of the structure layer and to be spaced at a predetermined interval, The lower electrode in the step (d) or the upper electrode in the step (f) is formed of a plurality of layers having a different crystal distribution for each layer. The method of claim 7, wherein The crystal distribution is a method for producing a MEMS structure, characterized in that the different by adjusting the size of the crystal grains for each layer. The method of claim 7, wherein The crystal distribution is a method of manufacturing a MEMS structure, characterized in that different by adjusting the density for each layer. The method of claim 7, wherein The lower electrode in the step (d) or the upper electrode in the step (f) is formed by a sputtering deposition method, The crystal distribution is a method for producing a MEMS structure, characterized in that the layer is different by adjusting the pressure of the sputtering gas. The method of claim 7, wherein The lower electrode in the step (d) or the upper electrode in the step (f) is formed by a sputtering deposition method, Wherein the crystal distribution is varied from layer to layer by adjusting a bias power that controls the extent to which the sputtered particles are attracted in the direction of the substrate plate.

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