JP4357970B2 - Structure of electromagnetic actuator and manufacturing method thereof - Google Patents

Description

  The present invention relates to a structure of an electromagnetic actuator manufactured using a microfabrication technique and a manufacturing method thereof.

  Various devices have been developed using MEMS (microelectromechanical system) technology due to advantages such as downsizing and cost reduction. Among MEMS devices, optical devices such as optical switches and optical attenuators can switch optical paths and control light transmittance by driving a mirror or shutter using a small actuator. As an actuator, an electrostatic actuator using a Coulomb force generated by applying a voltage between electrodes, or an electromagnetic actuator driven by applying an external magnetic field to a magnetic material is used.

Since the electromagnetic actuator generates a larger force than the electrostatic actuator, it is easy to make the moving distance of the movable part relatively large. For example, as described in Patent Document 1, it is used as an actuator that drives a movable mirror of an optical switch. FIG. 8 shows an electromagnetic actuator disclosed in Patent Document 1 as a conventional electromagnetic actuator. In Patent Document 1, a magnetic body 39 is formed on a cantilever beam 37 by using an electroplating method or a sputtering method, and is attracted to or repelled by using an electromagnet composed of a permanent magnet 41 and a coil 46. The movable reflecting member 38 positioned at the free end 37 is moved (see, for example, Patent Document 1).
JP 2000-137177 A

  However, as described in Patent Document 1, when the magnetic material is formed by electroplating or sputtering, it is possible to form the magnetic material in a small range, but the magnetic permeability of the magnetic material is reduced, In order to obtain a desired attractive force, it was necessary to pass a large current through the electromagnet. On the other hand, in the structure of Patent Document 1, when a cantilever and a plate-like magnetic body are pasted using an adhesive or the like, a magnetic body having a high magnetic permeability can be pasted. As a result, the adhesive body may stick out of the magnetic body and / or the cantilever beam. If the bonded body protrudes, there is a possibility that the movable part will stick between the movable part including the spring structure and the fixed part, and the movable part may be fixed. An attachment margin can be provided so that the adhesive does not penetrate between the movable part and the fixed part. However, in this case, there is a limit to downsizing the electromagnetic actuator. In order to fix the magnetic material with high positional accuracy, it is effective to use a photocurable resin as an adhesive. However, in the case of a photocurable resin, the magnetic material and the surface to which the magnetic material is attached are very narrow. Since the light could be directly irradiated only to the part, there were problems such as a long bonding time and a decrease in bonding strength. As described above, the conventional electromagnetic actuator has a problem that it is difficult to attach a magnetic material having a high magnetic permeability with high accuracy, so that power consumption increases and miniaturization is difficult.

  Accordingly, an object of the present invention is to provide a small and high-performance electromagnetic actuator and a manufacturing method thereof.

  In order to achieve the above-described object, an electromagnetic actuator according to the present invention is fixed to a fixed portion, a spring connected to the fixed portion, a movable portion connected to the spring, and the movable portion via an adhesive. In the electromagnetic actuator in which the movable part moves relative to the fixed part by a magnetic field generation source provided outside, the magnetic substance is fixed to at least a part of the movable part. A through hole penetrating the fixing surface and a surface opposite to the fixing surface, and at least a part of the inside of the through hole, at least a part of the fixing surface, and at least a part of the magnetic body. The electromagnetic actuator is coated with the adhesive.

  The electromagnetic actuator configured as described above has a through-hole formed in the fixed portion even when the amount of adhesive applied between the fixed surface and the magnetic material is large when the magnetic material is bonded to the fixed portion. The adhesive does not flow out of the magnetic body and / or the fixed surface when the adhesive body flows into the inside.

  Further, the electromagnetic actuator is characterized in that the shape of the through hole is a polygonal column. In addition, the electromagnetic actuator is characterized in that the shape of the through hole is a regular hexagonal column, and the honeycomb structure in which the regular hexagonal column is densely arranged. The electromagnetic actuator according to claim 1, wherein the shape of the through hole is a cylinder.

  As a result, the movable part of the electromagnetic actuator becomes light.

  A step of forming an etching mask on the front surface and the back surface of the substrate; a step of forming the movable portion and a part of the through hole by dry etching using the etching mask; and the etching mask. An electromagnetic actuator comprising: a step of forming a part of the spring and the through hole by dry etching; a step of completing the through hole; and a step of bonding the magnetic body to the movable portion using the adhesive body In the manufacturing method, the adhesive body is a photo-curing resin, and the photo-curing resin is bonded by irradiating light through the through hole, and the electromagnetic actuator manufacturing method, To do.

  According to the electromagnetic actuator manufacturing method described above, light can be directly applied to the photocurable resin through the through hole.

  As described above, according to the present invention, when the magnetic body is bonded to the fixing surface, the adhesive body does not protrude from the magnetic body and / or the fixing surface by flowing the excess adhesive body into the through hole. The pasting allowance can be reduced, and the electromagnetic actuator can be easily downsized. In addition, since a magnetic material with high magnetic permeability can be used, the power consumption of the electromagnetic actuator can be reduced.

  In addition, since the through hole is formed in the movable part and the weight is reduced, the resonance frequency of the movable part of the electromagnetic actuator is increased, and the movable part can be stably operated at high speed. In addition, when the structure constituted by the through holes is a honeycomb structure, it is possible to improve the reliability and durability of the electromagnetic actuator because it can reduce the weight and increase the mechanical strength. Become.

  In addition, since light can be directly applied to the photocurable resin through the through-hole, adhesion with high adhesion strength can be performed in a short time.

  FIG. 1 is a perspective view of the electromagnetic actuator 1000 according to the first embodiment of the present invention as viewed from above. The electromagnetic actuator 1000 according to the first embodiment is an optical device that includes the light control unit 11 and can block, transmit, or reflect light by movement of the light control unit 11. FIG. 2 is a perspective view of the electromagnetic actuator 1000 shown in FIG. 1 as viewed from below. The electromagnetic actuator 1000 includes a fixed portion 1, a spring portion 2, a movable body 3, a magnetic body 5, and an adhesive body 6. The movable body 3 is connected to the fixed body 1 or the fixed layer 9 integrated with the fixed body 1 via the spring portion 2. Further, the magnetic body 5 is fixed to the movable body 3 via the adhesive body 6. The movable body 3 is formed with a through hole 4 that penetrates the movable body 3. By applying an attractive force to the magnetic body 5 fixed to the movable body 3 by an electromagnet (not shown) arranged so as to face the magnetic body 5, the movable body 3 and the light control unit 11 fixed to the movable body. Can be moved in the direction indicated by arrow C in the figure. Moreover, when the attraction force by the electromagnet is lost, the movable body 3 and the light control unit 11 can return to the original positions by the restoring force of the spring portion 2.

  The material of the fixed part 1, the spring part 2, the movable body 3, and the fixed layer 9 is a semiconductor material such as silicon, silicon nitride, silicon dioxide, or a dielectric material. The magnetic body 5 is made of a magnetic material such as cobalt nickel alloy or permalloy. The material of the adhesive 6 is a resin material such as an acrylic resin or an epoxy resin, or a solder such as a gold-tin alloy. When the material of the adhesive body 6 is solder, an adhesion reinforcing layer having a structure in which titanium, nickel, gold, or titanium and nickel are sequentially laminated in the inside of the through hole 4 or a portion where the adhesive body and the movable body are in contact with each other. (Not shown) may be provided. The light control unit 11 is made of the same material as the movable body 3. Note that the surface of the light control unit 11 may be coated with a metal such as aluminum or gold in order to reflect or absorb light.

  3 is a top view of FIG. 1, and FIG. 4 is a cross-sectional view at a position indicated by A-A ′ in FIG. FIG. 5 is an enlarged view of a portion indicated by a circle B in FIG. FIG. 6 is a perspective view of the electromagnetic actuator 1000 viewed obliquely from above when the shape of the through hole 4 is a cylinder. The thickness D1 of the movable body 3 is 100 to 600 μm. Under the movable body 3, there is a buried oxide film layer (hereinafter referred to as a BOX layer) 7, and the thickness D5 of the BOX layer 7 is 1 to 20 μm. Further, under the BOX layer 7, there is an active layer 8 made of silicon, and the thickness D4 of the active layer 8 is 1 to 50 μm. The thickness D4 of the active layer 8 is equal to the thickness of the spring part 2. The thickness D2 of the magnetic body 5 is several tens to several hundreds μm. The thickness D3 of the adhesive body 6 in the portion of the through hole 4 is several μm to several tens of μm. Further, the thickness D6 of the adhesive body between the active layer 8 and the magnetic body 5 is several tens of μm or less. The width W1 of the through hole 4 is several tens of μm to several hundreds of μm. The value obtained by dividing the thickness D1 by the width W1 is 20 or less. The shape of the through hole 4 may be a prism as shown in FIG. 1 or a cylinder as shown in FIG. Further, the arrangement of the through holes 4 may be regularly arranged or irregularly arranged. In particular, as shown in FIG. 1, the structure in which the through-holes 4 are hexagonal columns and the hexagonal columns are densely arranged is known as a honeycomb structure, and is lightweight while maintaining mechanical strength. Is possible. In addition, the size of the part in which the through hole 4 is formed may be a size that allows a sufficient adhesion area with the magnetic body 5.

  Next, the manufacturing method of the electromagnetic actuator 1000 concerning Embodiment 1 of this invention is demonstrated using FIG. An SOI wafer is prepared as a start substrate. The SOI wafer includes a support substrate 101 made of silicon, a BOX layer 103 made of silicon dioxide formed on the support substrate, and an active layer 102 made of silicon formed on the BOX layer 103. First, as shown in FIG. 7A, a mask 104 and a mask 105 are formed on the support substrate 101 and the active layer 102 by a photolithography process. The material of the mask 104 and the mask 105 is a photoresist, silicon dioxide, and a metal such as chromium or aluminum.

  Next, as shown in FIG. 7B, the support substrate 101 is etched to the BOX layer 103 by dry etching such as deep reactive ion etching (DRIE). Next, as shown in FIG. 7C, the active layer 102 is etched to the BOX layer 103 by dry etching such as reactive ion etching (RIE) or DRIE, and then a mixed aqueous solution of hydrofluoric acid and ammonium fluoride. The BOX layer 103 is removed by wet etching using, for example, hydrofluoric acid. Note that in the case where the mask 104 and the mask 105 are silicon dioxide, the mask 104 and the mask 105 can be simultaneously removed in this step. With this process, the movable assembly 108 is completed.

  Next, as shown in FIG. 7D, an adhesive 106 is applied to the magnetic body 107 and aligned with the movable assembly 108. The magnetic body 107 is obtained by processing a bulk material such as a cobalt nickel alloy or permalloy.

  Next, as shown in FIG. 7E, the magnetic body 107 and the active layer 102 are brought into close contact with each other. At this time, a portion of the adhesive body 106 sandwiched between the active layer 102 and the magnetic body 107 is pushed out in the horizontal direction in the figure by pressure. However, since the through-hole 4 is formed, the amount of the adhesive 106 that is pushed out is small. Further, since most of the extruded adhesive body 106 is confined in the through hole 4, it is difficult to spread in the lateral direction in the figure. In the case where a photo-curing resin is used as the bonding body 106 in order to improve the positioning accuracy of the magnetic body 107, the bonding is completed by irradiating the bonding body 106 with light through the through hole 4 from the side opposite to the magnetic body 107. In the case where the adhesive body 106 is a thermosetting adhesive body, the adhesion is completed by heating the magnetic body 107 and the active layer 102 in close contact with each other.

  As described above, according to the first embodiment of the present invention, a magnetic body having a high magnetic permeability can be bonded to the movable body as the magnetic body 5. At that time, since the adhesive 106 can flow in the depth direction of the through hole 4, the spread of the adhesive layer 6 in the width direction is very small. Therefore, the pasting allowance for adhering the magnetic body can be reduced. In addition, the size of the magnetic body 107 to be attached can be increased with respect to the area of the attachment portion. The pasting allowance is, for example, about 100 μm. Since the pasting allowance can be reduced, the size of the movable body 3 can be reduced, and the entire electromagnetic actuator can be easily downsized. In addition, since a magnetic material with high magnetic permeability can be attached, power consumption of the electromagnetic actuator can be reduced. Further, by providing the through hole 4 together with downsizing, the movable part of the electromagnetic actuator can be reduced in weight. Therefore, since the resonance frequency of the electromagnetic actuator can be increased, the dynamic characteristics including the improvement of the response speed of the electromagnetic actuator can be improved. Further, in the case of a honeycomb structure in which the shape of the through hole 4 is a hexagonal column and is densely arranged, the mechanical strength can be improved in addition to the weight reduction, thereby improving the reliability of the electromagnetic actuator. I can do it.

  In addition, when a photo-curing resin is used as the adhesive body 106, light can be irradiated to the entire adhesive body 106 through the through-hole 4, so that strong adhesion can be performed in a shorter time. And since it can harden | cure in the state which aligned, the positioning accuracy of the magnetic body 107 can be improved. Further, when the adhesive body 106 is a thermosetting resin, the solvent contained in the adhesive body can be efficiently removed through the through hole 4, so that strong adhesion can be performed in a short time. I can do it. Further, by providing the through-hole 4, the area where the bonded body 106 is in contact with the movable portion can be increased, so that stronger bonding can be performed.

  As described above, according to the first embodiment of the present invention, it is possible to provide a small and high performance electromagnetic actuator and a manufacturing method thereof.

  In the above description, the step of bonding the magnetic body 107 to the active layer 102 side has been described. However, the same effect can be obtained by bonding the magnetic body 107 to the support substrate 101 side.

It is the perspective view which looked at the electromagnetic actuator 1000 which concerns on Embodiment 1 of this invention from upper direction. It is the perspective view which looked at the electromagnetic actuator 1000 which concerns on Embodiment 1 of this invention from the downward direction. FIG. 2 is a top view of FIG. 1. FIG. 4 is a cross-sectional view at a position indicated by A-A ′ in FIG. 3. FIG. 5 is an enlarged view of a portion indicated by a circle B in FIG. It is the perspective view which looked at the electromagnetic actuator 1000 when the shape of the through-hole 4 is a cylinder from diagonally upward. It is a figure explaining the manufacturing method of the electromagnetic actuator concerning Embodiment 1 of this invention. It is a figure explaining a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fixed part 2 ... Spring 3 ... Movable part 4 ... Through-hole 5 ... Magnetic body 6 ... Adhesive body 7 ... BOX layer 8 ... Active layer 11 ... ·shutter

Claims (7)

A fixed portion, and a spring connected to the fixed portion, a movable portion connected to the spring, made from a fixed via the adhesive member and the magnetic body on the movable portion, the magnetic field generation source disposed outside In the electromagnetic actuator in which the movable portion reciprocates in a direction facing the magnetic body relative to the fixed portion,
The adhesive is a photocurable resin,
A through-hole that passes through the surface of the movable part that contacts the adhesive body and the surface on the opposite side and opens toward the surface on the opposite side ;
The adhesive body is provided on a part of a surface facing the magnetic body, the adhesive body is provided on a part of an inner wall of the through hole by extending to the adhesive body provided on a part of the facing surface. Electromagnetic actuator. The movable part is supported by the four springs,
The spring has a portion that forms a band-shaped structure that is bent and folded, and a portion that forms a plate-like structure,
The part forming the band-shaped structure is connected to the fixed part, the part forming the plate-like structure is connected to the movable part,
4. The electromagnetic actuator according to claim 1, wherein the four springs are arranged symmetrically with respect to the center line in the planar direction of the movable part and are not symmetrical with each other. The through hole is, the electromagnetic actuator according to any one of claims 1 2, characterized in that the polygonal prism. The electromagnetic actuator according to claim 3 , wherein the through hole is a regular hexagonal column, and has a honeycomb structure in which the regular hexagonal column is densely arranged. The through hole is, the electromagnetic actuator according to any one of claims 1 to 2, characterized in that a cylindrical. A light control unit that is formed integrally with the fixed unit and absorbs or reflects light;
The electromagnetic actuator according to any one of claims 1 to 5 ,
Optical device, characterized in that that have a. Forming an etching mask on at least one of the front surface and the back surface of the substrate, or both surfaces;
Forming the movable part, the spring part and the through hole by an etching process using the etching mask;
In the method of manufacturing an electromagnetic actuator including the step of bonding the magnetic body to the movable part using the adhesive,
The adhesive is a photocurable resin,
Method of manufacturing an electromagnetic actuator according to claim 1, any one of 4, characterized in that the adhesive by irradiating light to the photocurable resin through the through hole.

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