JP2009083018A - Micro-structure manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro-structure manufacturing method suitable for forming a separate opposite portion separated from a substrate and opposed to the substrate via void into a prescribed shape, regardless of an unevenness mode of a sacrificial layer forming region on the substrate. <P>SOLUTION: This manufacturing method includes processes of: forming a metal sacrificial portion having a laminated structure constituted of a plurality of metal sacrificial layers 33 and 35 on the substrate 10' by a plating method; forming a structure portion 14 having a portion spread on the metal sacrificial portion and separated from the substrate 10' and supported by the substrate 10'; and eliminating the metal sacrificial portion. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a microstructure having a minute structure formed by a micromachining technique, and more particularly to a method for manufacturing a microstructure having a structure portion having a portion separated from a substrate.

  In recent years, in various technical fields, application of a microstructure having a microstructure formed by a micromachining technique has been attempted. Examples of such a microstructure include a variable capacitor element having a movable capacitor electrode as a movable part and a switching element having a predetermined movable part. In general, the movable portion of the microstructure has a portion (separation facing portion) that is separated from the substrate and faces the substrate via a gap, and is supported by the substrate. The microstructure with the movable part is described in, for example, the following Patent Documents 1 and 2.

JP 2001-347500 A JP 2006-128912 A

  In the conventional formation process of a microstructure with a movable part, for example, a step of forming a sacrificial layer as a single-layer film body on a substrate, and a part that spreads on the sacrificial layer and separates from the substrate, and A step of forming a structure portion (movable portion) supported by the substrate and a step of etching away the sacrificial layer are included. As the sacrificial layer, a silicon oxide film, a PSG film, or a resin film is often employed. The silicon oxide sacrificial layer and the PSG sacrificial layer are formed by a CVD method or a sputtering method. The resin sacrificial layer is formed through a spin coating method.

  However, since the sacrificial layer made of the silicon oxide film and the sacrificial layer made of the PSG film are conformally formed in a shape following the uneven shape of the base surface, for example, a wiring pattern is provided in the sacrificial layer forming region on the substrate. For this reason, when unevenness is present, the surface of the silicon oxide sacrificial layer and the PSG sacrificial layer formed so as to cover the wiring pattern has unevenness due to the presence of the wiring pattern. When such irregularities occur, there may be a case where the structure portion having the above-described spaced-apart portions to be further stacked on the sacrificial layer cannot be appropriately formed. In addition, the silicon oxide sacrificial layer and the PSG sacrificial layer tend to be difficult to increase in thickness. This is because it takes a long time to grow the silicon oxide film and the PSG film, and the internal stress of the silicon oxide film and the PSG film is large. The sacrificial layer may have to be formed sufficiently thick depending on the design dimensions of the above-described movable part or structure part.

  The sacrificial layer made of a resin film has a flat growth end side surface even when there are irregularities because, for example, a wiring pattern is provided in the sacrificial layer forming region on the substrate. However, since the resin sacrificial layer is relatively soft, if the above-described separated facing portion is formed on the resin sacrificial layer with a material having a large internal stress, the resin sacrificial layer cannot resist the internal stress of the spaced facing portion. As a result, the separation facing part may be formed by being deformed unreasonably.

  Further, the surface of the sacrificial layer formed by the conventional method is flat or uneven due to the presence of the uneven shape in the sacrificial layer forming region on the substrate. That is, according to the conventional sacrificial layer forming method, it is difficult to positively and accurately form the uneven shape on the surface of the sacrificial layer.

  The present invention has been conceived under such circumstances, and a remote-facing portion that is spaced from the substrate and faces the substrate via a gap is concerned with the unevenness of the sacrificial layer forming region on the substrate. It is an object of the present invention to provide a microstructure manufacturing method suitable for forming in a predetermined shape.

  The microstructure manufacturing method provided by the first aspect of the present invention includes a step of forming a first metal sacrificial layer on a substrate by a plating method, and a layer above the first metal sacrificial layer by a plating method. A step of forming a second metal sacrificial layer, a step of forming a structure having a portion extending on the second metal sacrificial layer and separated from the substrate and supported by the substrate, and first and second And a removal step of removing the metal sacrificial layer (metal sacrificial portion). By passing through this removal step, a spaced-apart portion that is spaced from the substrate and faces the substrate through a gap is formed.

  In the case where unevenness exists because, for example, a wiring pattern is provided in the sacrificial layer forming region on the substrate, according to the present method, the first metal sacrifice is first performed so as to fill the concave-convex shape by plating. Layers can be formed. By forming such a first metal sacrificial layer, the lower ground of the second metal sacrificial layer is flattened. When the second metal sacrificial layer is formed as a film having a uniform thickness above the first metal sacrificial layer, the growth end side surface of the second metal sacrificial layer becomes flat. Instead of such a second metal sacrificial layer formation method, when a second metal sacrificial layer is formed in a predetermined pattern above the first metal sacrificial layer, a metal composed of the first and second metal sacrificial layers is formed. The surface of the sacrificial part has a predetermined uneven shape. In this way, according to the present method, the surface of the metal sacrificial part can be flattened when there is unevenness because, for example, a wiring pattern is provided in the sacrificial layer forming region on the substrate. It is also possible to form a predetermined uneven shape on the surface of the metal sacrificial part. On the metal sacrificial portion having a flat surface, a flat separation facing portion can be formed. On the surface of the metal sacrificial part having a predetermined uneven shape on the surface, it is possible to form a spaced-apart portion associated with at least the uneven shape corresponding to the uneven shape on the substrate side.

  On the other hand, when the sacrificial layer forming region on the substrate is flat, according to this method, first, the first metal sacrificial layer can be formed as a film body having a uniform thickness by plating. Next, when a second metal sacrificial layer is formed in a predetermined pattern above the first metal sacrificial layer, the surface of the metal sacrificial portion made of the first and second metal sacrificial layers has a predetermined uneven shape. Will have. Thus, according to this method, when the sacrificial layer forming region on the substrate is flat, it is possible to form a predetermined uneven shape on the surface of the metal sacrificial portion. On the surface of the metal sacrificial part having a predetermined uneven shape on the surface, it is possible to form a spaced-apart portion associated with at least the uneven shape corresponding to the uneven shape on the substrate side.

  Further, the metal sacrificial layer formed in this method is formed by a plating method having a high material growth rate. Therefore, it is easy to increase the thickness of the metal sacrificial layer or metal sacrificial portion in this method.

  In addition, the metal sacrificial layer or metal sacrificial portion formed by the present method is sufficiently hard because it is made of metal. For this reason, it is possible to prevent the distantly facing portion that is laminated on the metal sacrificial portion from being unduly deformed.

  As described above, the method according to the first aspect of the present invention provides a predetermined distance-opposed portion that is spaced apart from the substrate and faces the substrate through the gap regardless of the unevenness of the sacrificial layer forming region on the substrate. It is suitable for forming in shape.

  The microstructure manufacturing method provided by the second aspect of the present invention includes a step of forming a metal sacrificial portion having a laminated structure composed of a plurality of metal sacrificial layers on a substrate by a plating method, and spreading on the metal sacrificial portion. A step of forming a structure portion having a portion separated from the substrate and supported by the substrate, and a removal step of removing the metal sacrificial portion.

  In the case where there are irregularities because, for example, a wiring pattern is provided in the sacrificial layer formation region on the substrate, according to this method, first, the first-stage metal sacrifice is performed so as to fill the concave portions of the irregularities by plating. Layers can be formed. By forming such a metal sacrificial layer, the lower ground of the second-stage metal sacrificial layer is flattened. Then, when a predetermined number of metal sacrificial layers are formed as film bodies of uniform thickness above the first metal sacrificial layer, the growth end side surface of the uppermost metal sacrificial layer becomes flat. When the uppermost metal sacrificial layer is formed in a predetermined pattern instead of forming the uppermost metal sacrificial layer as a film body having a uniform thickness, the surface of the metal sacrificial portion composed of the plurality of metal sacrificial layers Will have a predetermined concavo-convex shape. In this way, according to the present method, the surface of the metal sacrificial part can be flattened when there is unevenness because, for example, a wiring pattern is provided in the sacrificial layer forming region on the substrate. It is also possible to form a predetermined uneven shape on the surface of the metal sacrificial part. On the metal sacrificial portion having a flat surface, a flat separation facing portion can be formed. On the surface of the metal sacrificial part having a predetermined uneven shape on the surface, it is possible to form a spaced-apart portion associated with at least the uneven shape corresponding to the uneven shape on the substrate side.

  On the other hand, when the sacrificial layer formation region on the substrate is flat, according to the present method, the first-stage metal sacrificial layer can be formed as a film body having a uniform thickness by plating. Next, a predetermined number of metal sacrificial layers are formed as film bodies of uniform thickness above the first-stage metal sacrificial layer. Next, when the uppermost metal sacrificial layer is formed in a predetermined pattern, the surface of the metal sacrificial portion composed of the plurality of metal sacrificial layers has a predetermined uneven shape. Thus, according to this method, when the sacrificial layer forming region on the substrate is flat, it is possible to form a predetermined uneven shape on the surface of the metal sacrificial portion. On the surface of the metal sacrificial part having a predetermined uneven shape on the surface, it is possible to form a spaced-apart portion associated with at least the uneven shape corresponding to the uneven shape on the substrate side.

  Further, the metal sacrificial layer formed in this method is formed by a plating method having a high material growth rate. Therefore, it is easy to increase the thickness of the metal sacrificial layer or metal sacrificial portion in this method.

  In addition, the metal sacrificial layer or metal sacrificial portion formed by the present method is sufficiently hard because it is made of metal. For this reason, it is possible to prevent the distantly facing portion that is laminated on the metal sacrificial portion from being unduly deformed.

  As described above, the method according to the second aspect of the present invention provides a predetermined distance-opposed portion that is spaced apart from the substrate and faces the substrate through a gap regardless of the unevenness of the sacrificial layer forming region on the substrate. It is suitable for forming in shape.

  In the first and second aspects of the present invention, preferably, the metal sacrificial layer is made of a metal selected from the group consisting of Cu, Ni, Al, Ti, Cr, Au, and Pt, or an alloy containing the metal. .

  Preferably, the plating method is an electroplating method and / or an electroless plating method. In the electroplating method, Cu or Ni is preferably deposited and grown. In the electroless plating method, Cu, Ni, Ni—P, Ni—B, or Au is preferably deposited and grown.

  When the metal sacrificial layer is made of Cu or a Cu alloy, it is preferable that an etching solution containing an ammonia copper complex salt acts on the metal sacrificial layer in the removing step. In this case, the etching solution is preferably an aqueous solution containing ammonia copper complex salt, ammonium chloride, and ammonia. Such an etchant has a high etching rate with respect to the Cu sacrificial layer or the Cu alloy sacrificial layer, low erosion with respect to other materials, and low viscosity, so that the permeability between the substrate and the remote facing portion is high. There are features.

  1 to 3 show a microstructure X1 according to the first embodiment of the present invention. FIG. 1 is a plan view of the microstructure X1. 2 and 3 are enlarged sectional views taken along lines II-II and III-III in FIG.

  The microstructure X1 is configured as a variable filter element. Specifically, the microstructure X1 includes a substrate 10, a signal line 11, two ground lines 12, four shunt inductors 13, five movable capacitor electrodes 14, and two drive electrodes 15. , Two electrode pads 16 and configured as a frequency variable resonator filter that allows passage of electromagnetic waves or electrical signals in a specific high frequency band. FIG. 4 is an equivalent circuit diagram showing a distributed constant transmission line formed by the microstructure X1 as a resonator filter.

  The substrate 10 is made of quartz or glass. The signal line 11, the ground line 12, the shunt inductor 13, the movable capacitor electrode 14, the drive electrode 15, and the electrode pad 16 are provided on the substrate 10.

The signal line 11 has a terminal portion 11a (incident end) and a terminal portion 11b (exit end) at both ends thereof, and is a conductor pattern through which an electric signal passes between the terminal portions 11a and 11b. Includes an inductor component. This element is connected to a circuit other than the figure or another element via the terminal portions 11a and 11b. Such a signal line 11 is a distributed constant line having an impedance of 50Ω, for example, and is made of a low resistance metal such as Cu, Ag, Au, Al, W, or Mo. The thickness of the signal line 11 is, for example, 0.5 to 20 μm. Dielectric dots 17 are provided on such signal lines 11 as shown in FIGS. The dielectric dots 17 are made of a dielectric material such as Al ₂ O ₃ , SiO ₂ , SixNy, or SiOC, for example, and contribute to preventing the signal line 11 and the movable capacitor electrode 14 from being short-circuited. And it contributes to increasing the capacitance of the capacitor constituted by the movable capacitor electrode 14. The increase in the capacitance is preferable for securing a wide frequency variable range for the element.

  Each ground line 12 is a conductor pattern extending along the signal line 11 and connected to the ground. Such a ground line 12 forms a fixed capacitor in cooperation with the signal line 11. The signal line 11 and each ground line 12 are connected via a shunt inductor 13. The ground line 12 and the shunt inductor 13 are made of a low resistance metal such as Au, Cu, Al, or Ag. The thickness of the ground line 12 and the shunt inductor 13 is, for example, 0.5 to 20 μm.

  As shown in FIG. 2, each movable capacitor electrode 14 bridges between the ground lines 12 (and is therefore grounded). The movable capacitor electrode 14 has a separation facing portion 14A that is separated from the substrate 10 and faces the substrate 10 through a gap between the ground lines 12, and faces the signal line 11 as a part of the separation facing portion 14A. It has a thick portion 14a. In order to ensure sufficient joining of the both ends of the movable capacitor electrode 14 to the ground line 12, anchor portions 18 are provided. Specifically, each end of the movable capacitor electrode 14 is sandwiched between the anchor portion 18 and the ground line 12 that are partially joined to the ground line 12 outside the figure. Such a movable capacitor electrode 14 is made of a low-resistance metal such as Au, Cu, or Al, for example, and constitutes a variable capacitance capacitor in cooperation with the signal line 11 described above. The gap G1 between the signal line 11 and the movable capacitor electrode 14 is, for example, 0.1 to 10 μm.

  Each drive electrode 15 is for generating an electrostatic attractive force between the movable capacitor electrode 14 and displacing the movable capacitor electrode 14. The drive electrode 15 is disposed between the signal line 11 and the ground line 12 to be movable capacitor electrode. 14 is opposed to a part. The drive electrode 15 is made of a predetermined metal thin film (a relatively high resistance SiCr thin film is desirable from the viewpoint of preventing leakage of high-frequency signals). In order to avoid a so-called pull-in phenomenon between the movable capacitor electrode 14 and the drive electrode 15, the gap G2 between the movable capacitor electrode 14 and the drive electrode 15 is set to be three times or more the gap G1. Is done.

Each electrode pad 16 is a terminal for applying a driving voltage, and is separated from the ground line 12 through a gap. As shown in FIG. 2, the electrode pad 16 and the drive electrode 15 are connected by a wiring 19 that passes between the substrate 10 and the ground line 12. The wiring 19 and the ground line 12 are electrically separated by an insulating film 20 interposed therebetween. The insulating film 20 is made of, for example, SiO ₂ .

Or eggplant variable capacitor element of microstructure X1 having a structure as an equivalent made of, as shown in FIG. 4, and K ₀₁ inverter, a K ₁₂ inverter, a resonance circuit portion R disposed therebetween It can be represented by a circuit diagram. The K ₀₁ inverter is composed of a pair of shunt inductors 13 connected to the signal line 11 on the terminal portion 11a (incident end) side. K ₁₂ inverter is comprised of a pair of shunt inductors 13, which are connected to the signal line 11 at the terminal portion 11b (outgoing end) side. The resonance circuit unit R includes an inductor L (inductor component in the entire resonance circuit unit R) and a variable capacitance capacitor C (capacitor component in the entire resonance circuit unit R), and mainly includes the substrate 10, the signal line 11, and the ground. Line 12. The capacitor C includes the above-described capacitance fixed capacitor configured by the signal line 11 and the ground line 12 formed on the substrate 10, and the above-described variable capacitance configured by the signal line 11 (non-moving capacitor electrode) and the movable capacitor electrode 14. It consists of a capacitor.

  In the microstructure X1 as such a variable capacitor element, the spatial length L shown in FIG. 1 is such that the transmission path length of the resonance circuit section R shown in FIG. 4 (that is, the transmission path length between the two inverters) is, for example, λ. / 2 (λ: a specific high-frequency for extraction purpose, a wavelength in the distributed constant line) is set to be an integral multiple. In such a configuration, in the microstructure X1 which is a variable capacitor element, for example, the mixed electric signal input from the terminal unit 11a is filtered, and an electric signal in a specific high frequency band is extracted and output from the terminal unit 11b.

In the equivalent circuit diagram of FIG. 4, the resonance circuit R is arranged between the K ₀₁ inverter and the K ₁₂ inverter. According to such a configuration, the electromagnetic wave is transmitted from the incident end (K ₀₁ inverter side terminal). or a high-frequency electrical signal to be incident on the reflection without resonance circuit portion R, also, the electromagnetic wave propagating to the exit end (K ₁₂ inverter side terminal) can be emitted without reflection from the exit end. The K ₀₁ inverter has a characteristic impedance K ₀₁ and the K ₁₂ inverter has a characteristic impedance K ₁₂ , each of which functions as a distributed constant line having a length λ / 4 in a predetermined frequency band.

  In the microstructure X1 which is a variable capacitor element, the capacitance of the capacitor C shown in FIG. 4 can be changed by applying a predetermined voltage (drive voltage) between the drive electrode 15 and the movable capacitor electrode 14. . Application of a potential to the drive electrode 15 can be realized via the electrode pad 16 and the wiring 19. When a drive voltage is applied between the drive electrode 15 and the movable capacitor electrode 14, a predetermined electrostatic attractive force is generated between the two electrodes, and the movable capacitor electrode 14 is pulled into the drive electrode 15 side. As a result, the signal line 11 and the movable capacitor electrode 14 have a small gap G1. When the gap G1 is reduced, the capacitance of the capacitor C is increased, the entire transmission path length of the microstructure X1 that is a variable capacitor element is equivalently or substantially increased, and a frequency band that is allowed to pass is low frequency. Shift to the side. In such a variable capacitor element (micro structure X1), the capacitance of the capacitor C shown in FIG. 4 is significantly switched by turning on / off the driving voltage, and the passing frequency band in the high frequency region is appropriately switched (for example, 18 GHz). Switching between 22 GHz). Further, the pass frequency band can be continuously changed by controlling the drive voltage in an analog manner.

  5 to 9 show a manufacturing method of the microstructure X1. 5 to 9, the manufacturing process of the microstructure X1 is represented by a change in cross section. The cross section includes a cross section (a cross section taken along line V-V in FIG. 1) of a single microstructure forming section in the wafer to be processed.

  In the manufacture of the microstructure X1, first, as shown in FIG. 5A, the above-described drive electrode 15 is formed on the wafer 10 '. At the same time, in this step, the above-described wiring 19 is formed on the wafer 10 '. For example, the drive electrode 15 and the wiring 19 can be formed by forming a predetermined metal material on the wafer 10 ′ by sputtering and then patterning the metal film by predetermined wet etching or dry etching. After this step, the insulating film 20 is patterned on the wiring 19 described above. For example, after a predetermined insulating material is formed on the wafer 10 ′ so as to cover at least the wiring 19 by the CVD method, the wiring 19 can be formed by patterning the insulating material film. The insulating film 20 may be formed so as to cover the drive electrode 15.

  Next, as shown in FIG. 5B, the signal line 11 and the ground line 12 are formed on the wafer 10 '. For example, after a resist pattern having openings corresponding to the signal lines 11 and the ground lines 12 is formed on the wafer 10 ′, a predetermined metal material is deposited in the openings by a plating method (electroless plating or electroplating). By growing, the signal line 11 and the ground line 12 can be formed.

  Next, as shown in FIG. 5C, the above-described dielectric dots 17 are formed on the signal lines 11. For example, a dielectric film is formed on the wafer 10 ′ so as to cover the signal line 11, the ground line 12, and the drive electrode 15, and then the dielectric film 17 is patterned to form the dielectric dots 17. be able to.

  Next, as shown in FIG. 6A, a seed layer 31 is formed over the entire surface of the wafer 10 '. The seed layer 31 serves as a base end for depositing and growing a metal material in the plating method, and includes, for example, a Cr layer and a Cu layer thereon.

  Next, a resist pattern 32 is formed as shown in FIG. The resist pattern 32 has an opening 32a for forming a first-stage metal sacrificial layer. Specifically, the resist pattern 32 has an opening 32a at a position corresponding to the region where the plurality of movable capacitor electrodes 14 are formed. In forming the resist pattern 32, a photoresist is formed on the wafer 10 ′ by spin coating, the photoresist film is baked at a predetermined temperature, and the photoresist is exposed using a predetermined mask. The photoresist is developed using a predetermined developer (the resist pattern described later is also formed through such spin coating, baking, exposure, and development).

  Next, as shown in FIG. 6C, a metal sacrificial layer 33 is formed. Specifically, the metal sacrificial layer 33 can be formed by depositing and growing a metal material in the openings 32a of the resist pattern 32 by plating. As the plating method, an electroplating method or an electroless plating method is adopted. Alternatively, the electroplating method may be adopted halfway and the electroless plating method may be adopted halfway, or the electroless plating method may be adopted halfway and the electroplating method may be adopted halfway. The metal sacrificial layer 33 is made of, for example, a metal selected from the group consisting of Cu, Ni, Al, Ti, Cr, Au, and Pt or an alloy containing the metal. When the electroplating method is adopted, the metal material to be deposited and grown is preferably Cu or Ni. When the electroless plating method is adopted, the metal material to be deposited and grown is preferably Cu, Ni, Ni—P, Ni—B, or Au. The thickness of the metal sacrificial layer 33 formed in this step is preferably the same as the thickness of the signal line 11, for example.

  Next, the resist pattern 32 is removed as shown in FIG. The resist pattern 32 can be removed by applying a predetermined stripping solution.

  Next, as shown in FIG. 7B, a resist pattern 34 is formed. The resist pattern 34 has an opening 34a for forming a second-stage metal sacrificial layer.

  Next, a metal sacrificial layer 35 is formed as shown in FIG. Specifically, the metal sacrificial layer 35 can be formed by depositing and growing a metal material in the opening 34a of the resist pattern 34 by plating. As the plating method, an electroplating method or an electroless plating method is adopted. Alternatively, the electroplating method may be adopted halfway and the electroless plating method may be adopted halfway, or the electroless plating method may be adopted halfway and the electroplating method may be adopted halfway. The metal sacrificial layer 35 is made of, for example, a metal selected from the group consisting of Cu, Ni, Al, Ti, Cr, Au, and Pt or an alloy containing the metal. When the electroplating method is adopted, the metal material to be deposited and grown is preferably Cu or Ni. When the electroless plating method is adopted, the metal material to be deposited and grown is preferably Cu, Ni, Ni—P, Ni—B, or Au. The gap G1 between the signal line 11 and the movable capacitor electrode 14 is defined by the thickness of the metal sacrificial layer 35 formed in this step. Further, the gap G <b> 2 between the drive electrode 15 and the movable capacitor electrode 14 is defined by the total thickness of the metal sacrificial layers 33 and 35.

  Next, as shown in FIG. 8A, the resist pattern 34 is removed. In the process drawings after this figure, the seed layer 31 is omitted from the viewpoint of simplifying the drawing. Further, in this step, portions exposed to the outside in the seed layer 31 may be removed. As a method for removing the seed layer 31, an ion milling method can be employed.

  Next, as shown in FIG. 8B, a sheet spring layer 14 ′ is formed on the wafer 10 ′ by, for example, sputtering so as to cover the metal sacrificial layer 35 and the ground line 12.

  Next, as shown in FIG. 8C, a resist pattern 36 is formed. The resist pattern 36 has an opening 36 a for forming the thick portion 14 a and an opening 36 b for forming the anchor portion 18.

  Next, as shown in FIG. 9A, the thick portion 14a and the anchor portion 18 are formed. By depositing and growing a metal material in the openings 36a and 36b of the resist pattern 36 by plating, the thick portion 14a and the anchor portion 18 can be formed. In this step, the seat spring layer 14 'can be used as a seed layer for plating.

  Next, as shown in FIG. 9B, after the resist pattern 36 is removed, the above-described spaced facing portion 14A of the movable capacitor electrode 14 is patterned from the seat spring layer 14 '. In the pattern formation of the separation facing portion 14A, after a predetermined resist pattern is formed on the seat spring layer 14 ', the seat spring layer 14' is patterned into a predetermined shape by, for example, ion milling.

  Next, as shown in FIG. 9C, the metal sacrificial layers 33 and 35 are removed. Specifically, wet etching is performed by applying a predetermined etching solution corresponding to the metal material type constituting the metal sacrificial layers 33 and 35. When the metal sacrificial layers 33 and 35 are made of Cu or a Cu alloy, the etching solution is preferably an aqueous solution containing an ammonia copper complex salt, ammonium chloride, and ammonia. When the metal sacrificial layers 33 and 35 are made of Ni or Ni alloy, an aqueous solution of iron (III) chloride can be used as the etching solution. When the metal sacrificial layers 33 and 35 are made of Au or an Au alloy, an aqueous solution containing ammonium iodide, iodine, and methanol can be used as the etching solution.

  Thereafter, the wafer 10 'is cut to obtain individual pieces. As described above, the microstructure X1 shown in FIG. 1 can be manufactured. According to this method, the microstructure X1 can be appropriately mass-produced by using the wafer 10 'having a large number of microstructure forming sections.

  In this method, before the metal sacrificial layers 33 and 35 are formed, the signal line 11 is provided on the sacrificial layer forming region on the wafer 10 ′ or the substrate 10, and therefore there are irregularities in the sacrificial layer forming region. To do. However, according to this method, first, as shown in FIG. 6C, it is possible to form the metal sacrificial layer 33 so as to fill the concave and convex portions by plating. By forming such a metal sacrificial layer 33, the lower ground of the metal sacrificial layer 35 is flattened. Then, as shown in FIG. 7C, by forming the metal sacrificial layer 35 as a film body having a uniform thickness above the metal sacrificial layer 33, the surface on the growth end side of the metal sacrificial layer 35 is flat. Become. Thus, according to the present method, even when the sacrificial layer forming region on the substrate 10 has irregularities, the surface of the metal sacrificial portion (metal sacrificial layers 33 and 35) can be flattened ( In this embodiment, a metal sacrificial part having a two-layer structure is adopted, but in the present invention, a metal sacrificial part having a multilayer structure of three or more layers may be adopted. Therefore, according to the present method, it is possible to form the separation facing portion 14A having a flat surface at least on the substrate 10 side on the metal sacrifice portion having a flat surface.

  Further, the metal sacrificial layers 33 and 35 formed in this method are formed by a plating method having a high material growth rate. Therefore, it is easy to increase the thickness of the metal sacrificial layers 33 and 35 or the metal sacrificial portion in this method.

  In addition, the metal sacrificial layers 33 and 35 or the metal sacrificial portion formed by this method are made of metal and are sufficiently hard. For this reason, it is possible to prevent the separation facing part 14 </ b> A formed on the metal sacrificial part from being unduly deformed.

  10 and 11 show a microstructure X2 according to the second embodiment of the present invention. FIG. 10 is a plan view of the microstructure X2. 11 is an enlarged cross-sectional view taken along line XI-XI in FIG.

  The microstructure X2 includes a substrate 10, a signal line 11, two ground lines 12, four shunt inductors 13, five movable capacitor electrodes 21, two drive electrodes 15, and two electrode pads. 16 and is configured as a frequency variable resonator filter that allows passage of electromagnetic waves or electrical signals in a specific high frequency band. The microstructure X2 is different from the above-described microstructure X1 according to the first embodiment in that the movable capacitor electrode 21 is provided instead of the movable capacitor electrode 14.

  As shown in FIG. 11, the movable capacitor electrode 21 bridges between the ground lines 12, and has a separation facing portion 21 </ b> A that is separated from the substrate 10 and faces the substrate 10 through a gap between the ground lines 12. And it has the thick part 21a which opposes the signal wire | line 11 as a part of 21 A of space | interval opposing parts. The separation facing portion 21A has an uneven shape 21b as shown in FIG. It is possible to adjust the elasticity of the movable capacitor electrode 21 or the separation facing portion 21A by changing the degree and number of the unevenness in the uneven shape 21b. Further, both end portions of the movable capacitor electrode 21 are sandwiched between the ground line 12 and the anchor portion 18. Such a movable capacitor electrode 21 is made of a low-resistance metal such as Au, Cu, or Al, and constitutes a variable capacitance capacitor in cooperation with the signal line 11.

  The variable capacitor element formed by the microstructure X2 having the above structure can be represented by an equivalent circuit diagram as shown in FIG. The capacitor C in this equivalent circuit diagram is the above-described capacitor fixed capacitor formed by the signal line 11 and the ground line 12 formed on the substrate 10, the signal line 11 (non-moving capacitor electrode) and the movable capacitor electrode 21. The capacitance variable capacitor. Other configurations of the equivalent circuit diagram are the same as those described above with respect to the variable capacitor element formed by the microstructure X1.

  In the microstructure X2 that is a variable capacitor element, the capacitance of the capacitor C shown in FIG. 4 can be changed by applying a predetermined voltage (drive voltage) between the drive electrode 15 and the movable capacitor electrode 21. . Application of a potential to the drive electrode 15 can be realized via the electrode pad 16 and the wiring 19. When a drive voltage is applied between the drive electrode 15 and the movable capacitor electrode 21, a predetermined electrostatic attractive force is generated between the two electrodes, and the movable capacitor electrode 21 is drawn to the drive electrode 15 side. As a result, the signal line 11 and the movable capacitor electrode 21 are reduced in gap G1. When the gap G1 is reduced, the capacitance of the capacitor C is increased, the entire transmission path length of the microstructure X2 that is a variable capacitor element is equivalently or substantially increased, and the frequency band that is allowed to pass is reduced. Shift to the frequency side. In such a variable capacitor element (micro structure X2), the capacitance of the capacitor C shown in FIG. 4 is significantly switched by turning on and off the driving voltage, and the passing frequency band in the high frequency region is appropriately switched (for example, 18 GHz). Switching between 22 GHz). Further, the pass frequency band can be continuously changed by controlling the drive voltage in an analog manner.

  12 to 14 show some steps in the manufacturing method of the microstructure X2. 12 to 14, the manufacturing process of the microstructure X2 is represented by a change in cross section. The cross section includes a cross section (a cross section taken along line XII-XII in FIG. 10) of a single microstructure forming section in the wafer to be processed.

  In the manufacture of the microstructure X2, first, as described above with reference to FIGS. 5A to 7C regarding the manufacture of the microstructure X1, the driving electrode 15 is formed on the wafer 10 ′. And wiring 19, signal line 11 and ground line 12, dielectric dot 17, seed layer 31, resist pattern 32, metal sacrificial layer 33, resist pattern 32 is removed, a resist pattern 34 is formed, a metal sacrificial layer 35 is formed, and the resist pattern 34 is removed, resulting in a state similar to that shown in FIG.

  Next, as shown in FIG. 12B, after forming a resist pattern 37 having a predetermined opening 37a, a metal sacrificial layer 38 is formed as shown in FIG. 12C. Specifically, the metal sacrificial layer 38 can be formed by depositing and growing a metal material in the opening 37a of the resist pattern 37 by plating. As the plating method, an electroplating method or an electroless plating method is adopted. Alternatively, the electroplating method may be adopted halfway and the electroless plating method may be adopted halfway, or the electroless plating method may be adopted halfway and the electroplating method may be adopted halfway. The metal sacrificial layer 37 is made of, for example, a metal selected from the group consisting of Cu, Ni, Al, Ti, Cr, Au, and Pt or an alloy containing the metal. When the electroplating method is adopted, the metal material to be deposited and grown is preferably Cu or Ni. When the electroless plating method is adopted, the metal material to be deposited and grown is preferably Cu, Ni, Ni—P, Ni—B, or Au.

  Next, the resist pattern 37 is removed as shown in FIG. In the process drawings after this figure, the seed layer 31 is omitted from the viewpoint of simplifying the drawing. Further, in this step, portions exposed to the outside in the seed layer 31 may be removed.

  Next, as shown in FIG. 13B, the sheet spring layer 21 ′ with the uneven shape 21b is formed on the wafer 10 ′ so as to cover the metal sacrificial layers 33, 35, and 38 and the ground line 12 by sputtering, for example. Form.

  Next, a resist pattern 39 is formed as shown in FIG. The resist pattern 39 has an opening 39a for forming the thick portion 21a and an opening 39b for forming the anchor portion 18.

  Next, as shown in FIG. 14A, the thick part 21a and the anchor part 18 are formed. By depositing and growing a metal material in the openings 39a and 39b of the resist pattern 39 by plating, the thick portion 21a and the anchor portion 18 can be formed. In this step, the seat spring layer 21 'can be used as a seed layer for plating.

  Next, as shown in FIG. 14B, after the resist pattern 39 is removed, the above-described spaced facing portion 21A of the movable capacitor electrode 21 is patterned from the seat spring layer 21 '. In the pattern formation of the separation facing portion 21A, after a predetermined resist pattern is formed on the seat spring layer 21 ', the seat spring layer 21' is patterned into a predetermined shape by, for example, ion milling.

  Next, as shown in FIG. 14C, the metal sacrificial layers 33, 35, and 38 are removed. Specifically, wet etching is performed by applying a predetermined etching solution corresponding to the metal material type constituting the metal sacrificial layers 33, 35, and 38. When the metal sacrificial layers 33, 35, and 38 are made of Cu or a Cu alloy, the etching solution is preferably an aqueous solution containing an ammonia copper complex salt, ammonium chloride, and ammonia. When the metal sacrificial layers 33, 35, and 38 are made of Ni or a Ni alloy, an iron (III) chloride aqueous solution can be used as the etching solution. When the metal sacrificial layers 33, 35, and 38 are made of Au or an Au alloy, an aqueous solution containing ammonium iodide, iodine, and methanol can be used as the etchant.

  Thereafter, the wafer 10 'is cut to obtain individual pieces. The microstructure X2 can be manufactured as described above. According to this method, the microstructure X2 can be appropriately mass-produced by using the wafer 10 'having a large number of microstructure forming sections.

  In this method, before the metal sacrificial layers 33, 35, and 38 are formed, the signal lines 11 are provided on the sacrificial layer forming region on the wafer 10 ′ or the substrate 10. Exists. However, according to this method, first, the first-stage metal sacrificial layer 33 can be formed by plating so as to fill the concave and convex portions. By forming such a metal sacrificial layer 33, the lower ground of the second stage metal sacrificial layer 35 is flattened. Then, by forming the metal sacrificial layer 35 as a film having a uniform thickness above the metal sacrificial layer 33, the surface of the growth end side of the metal sacrificial layer 35 becomes flat. Then, by forming the uppermost metal sacrificial layer 38 in a predetermined pattern, the surface of the metal sacrificial portion composed of the metal sacrificial layers 33, 35, 38 has a predetermined uneven shape. Thus, according to the present method, even when the sacrificial layer forming region on the substrate 10 has irregularities, a desired irregular shape is formed on the surface of the metal sacrificial portion (metal sacrificial layers 33, 35, 38). (In this embodiment, a three-layer metal sacrificial portion is employed, but in the present invention, a two-layer metal sacrificial portion or a metal sacrificial portion having a multilayer structure of four or more layers may be employed. Good). On the surface of the metal sacrificial part having a predetermined uneven shape on the surface, a separation facing portion 21A with an uneven shape 21b corresponding to the uneven shape can be formed.

  The metal sacrificial layers 33, 35, and 38 formed in this method are formed by a plating method having a high material growth rate. Therefore, it is easy to increase the thickness of the metal sacrificial layers 33, 35, and 37 or the metal sacrificial portion in this method.

  In addition, the metal sacrificial layers 33, 35, and 38 or the metal sacrificial portion formed by this method are made of metal and are sufficiently hard. For this reason, it is possible to prevent the separation facing portion 21 </ b> A formed on the metal sacrificial portion from being unduly deformed.

  As a summary of the above, the configurations of the present invention and variations thereof are listed below as supplementary notes.

(Appendix 1) A step of forming a first metal sacrificial layer on a substrate by a plating method;
Forming a second metal sacrificial layer on top of the first metal sacrificial layer by plating;
Forming a structure having a portion extending on the second metal sacrificial layer and spaced apart from the substrate and supported by the substrate;
A removal step of removing the first and second metal sacrificial layers.
(Appendix 2) A step of forming a metal sacrificial portion having a laminated structure composed of a plurality of metal sacrificial layers on a substrate by a plating method;
Forming a structure that has a portion that spreads over the metal sacrificial portion and is spaced apart from the substrate and is supported by the substrate;
And a removal step of removing the metal sacrificial portion.
(Supplementary note 3) The microstructure according to Supplementary note 1 or 2, wherein the metal sacrificial layer is made of a metal selected from the group consisting of Cu, Ni, Al, Ti, Cr, Au, and Pt or an alloy containing the metal. Body manufacturing method.
(Supplementary note 4) The microstructure manufacturing method according to supplementary note 1 or 2, wherein the plating method is an electroplating method and / or an electroless plating method.
(Supplementary note 5) The microstructure manufacturing method according to supplementary note 4, wherein Cu or Ni is deposited and grown in the electroplating method.
(Supplementary note 6) The microstructure manufacturing method according to supplementary note 4, wherein Cu, Ni, Ni-P, Ni-B, or Au is deposited and grown in the electroless plating method.
(Supplementary note 7) The microstructure manufacturing method according to supplementary note 1 or 2, wherein the metal sacrificial layer is made of Cu or a Cu alloy, and an etching solution containing an ammonia copper complex salt is allowed to act on the metal sacrificial layer in the removing step.
(Supplementary note 8) The microstructure manufacturing method according to supplementary note 7, wherein the etching solution is an aqueous solution containing ammonia copper complex salt, ammonium chloride, and ammonia.

It is a top view of the microstructure concerning a 1st embodiment of the present invention. It is an expanded sectional view along line II-II of FIG. FIG. 3 is an enlarged sectional view taken along line III-III in FIG. 1. FIG. 2 is an equivalent circuit diagram showing a distributed constant transmission line formed by the microstructure (variable filter element) shown in FIG. 1. Part of the steps in the method for manufacturing the microstructure shown in FIG. The process which follows FIG. 5 is represented. The process following FIG. 6 is represented. The process following FIG. 7 is represented. The process following FIG. 8 is represented. It is a top view of the microstructure concerning a 2nd embodiment of the present invention. It is an expanded sectional view along line XI-XI of FIG. FIG. 11 illustrates some steps in the method for manufacturing the microstructure (variable filter element) illustrated in FIG. 10. The process following FIG. 12 is represented. The process following FIG. 13 is represented.

Explanation of symbols

X1, X2 Micro structure 10 Substrate 10 'Wafer 11 Signal line 12 Ground line 14, 21 Movable capacitor electrode 14A, 21A Separation facing part 14a, 21a Thick part 15 Drive electrode 17 Dielectric dot 18 Anchor part 21b Uneven shape 33, 35,38 metal sacrificial layer

Claims (6)

Forming a first metal sacrificial layer on the substrate by plating;
Forming a second metal sacrificial layer on top of the first metal sacrificial layer by plating;
Forming a structure having a portion extending on the second metal sacrificial layer and spaced apart from the substrate and supported by the substrate;
A removal step of removing the first and second metal sacrificial layers. Forming a metal sacrificial portion having a laminated structure composed of a plurality of metal sacrificial layers on a substrate by a plating method;
Forming a structure that has a portion that spreads over the metal sacrificial portion and is spaced apart from the substrate and is supported by the substrate;
And a removal step of removing the metal sacrificial portion.   The microstructure manufacturing method according to claim 1, wherein the plating method is an electroplating method and / or an electroless plating method.   The microstructure manufacturing method according to claim 3, wherein Cu or Ni is deposited and grown in the electroplating method.   The microstructure manufacturing method according to claim 3, wherein Cu, Ni, Ni-P, Ni-B, or Au is deposited and grown in the electroless plating method.   The microstructure manufacturing method according to claim 1, wherein the metal sacrificial layer is made of Cu or a Cu alloy, and an etching solution containing an ammonia copper complex salt is allowed to act on the metal sacrificial layer in the removing step.

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