JP2009178816A - Micromachine apparatus and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micromachine apparatus capable of reducing the noise of an output signal by suppressing the vibration of the micromachine, and a method for manufacturing the same. <P>SOLUTION: The micromachine apparatus 1 includes: substrates 11, 12 mounted with signal wiring 15 on the main face; a MEMS element 16 mounted on the main face, equipped with a beam portion 16a straddling the signal wiring 15 and elastically deformed so as to engage with and separate from the signal wire 15 with the application of an electric field, and having electric characteristics varying with the deformation; restricting bridges 18 disposed on the side opposite to the signal wiring 15 of the beam portion 16a and having one end apart from the signal wiring 15 to be coupled to the MEMS element 16 and supported and the other end formed in a cantilever shape so as to overhang toward the signal wiring 15 to restrict the deformation of the beam portion 16a spaced from the signal wiring 15; and a sealing body 20 mounted on the main face of the substrates 11, 12 and for covering the MEMS element 16 through a hollow portion 17. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a micromachine device such as packaging of micro-electromechanical components and a method of manufacturing the micromachine device.

  As an example of a micromachine device, as shown in FIGS. 10 to 12, a micro electro mechanical component (MEMS: Micro−) in which a MEMS element 104 as a micromachine accompanied by an operation is mounted on a substrate 102 and sealed in a hollow state. Electro-Mechanical-Systems) 101 is known (see, for example, Patent Document 1 or 2). The microelectromechanical component 101 includes a substrate 102, an insulating layer 103, a MEMS element 104, a signal wiring (signal line) 105, a drive electrode 106, a lower electrode 107, a first sealing body 108, and a second sealing body 109. The hollow portion 110 is formed inside. The MEMS element 104 has a dual-supported beam structure, and the central portion of the beam is formed with a gap of about several μm from the signal wiring 105. In the insulating layer 103 immediately below the MEMS element 104, a signal wiring 105 is formed of Au or the like. The MEMS element 104 is made of poly-Si (polysilicon) or Al (aluminum) having high spring characteristics, and is brought closer to the signal wiring 105 by applying a driving force such as electrostatic force. When the driving force is unloaded, the MEMS element 104 returns to a position having a gap with the signal wiring 105 due to its own spring characteristics. By changing the gap between the MEMS element 104 and the signal wiring 105 in this manner, functions such as variable capacitance and switching are achieved.

  In order to operate and protect the MEMS element 104, it is necessary to seal it in a hollow state. A method of manufacturing a micromachine device by a film forming process is provided for the purpose of reducing manufacturing cost and downsizing. As shown in FIG. 13, first, a sacrificial layer 111 that is completely removed in a later step is formed on the substrate 102 in order to provide a gap between the MEMS element 104 and the substrate. Next, the MEMS element 104 is formed on the sacrificial layer 111. A second sacrificial layer 112 is formed on the MEMS element 104 formed on the sacrificial layer 111. A first sealing body 108 is formed on the second sacrificial layer 112. An opening shape portion 108 a is formed in the first sealing body 108 for introducing an etching material when removing the sacrificial layers 111 and 112 around the MEMS element 104 during or after film formation. An etching material for removing the sacrificial layer is introduced from the opening shape portion 108a, and all the sacrificial layers 111 and 112 are completely removed. Finally, the second sealing body 109 is formed on the first sealing body 108 until the opening shape portion 108a is completely closed.

As described above, as shown in FIG. 10, the MEMS element 104 can be sealed in a hollow state by the sealing body configured by the first and second sealing bodies 108 and 109. The hollow part 110 has a reduced pressure atmosphere. Here, when the second sealing body 109 is formed by a film forming method such as CVD or sputtering, the film material is deposited immediately below the opening shape portion 108 a, so that the film material is not deposited on the MEMS element 104. An opening shape portion 108 a is provided at a position away from the MEMS element 104.
JP 2005-207959 A U.S. Patent No. 70008812B1

  However, the above technique has the following problems. In other words, the beam-shaped MEMS element is less likely to stabilize the vibration when the electrostatic force is unloaded due to its spring characteristics, which causes noise in the output signal. In particular, since the fluid resistance is small in the decompressed atmosphere in the hollow portion 110, it is difficult to stabilize the vibration of the MEMS element.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a micromachine device that can reduce noise of an output signal by facilitating the vibration of the micromachine.

  A micromachine device according to an aspect of the present invention includes a substrate having a signal wiring provided on a main surface, and a beam portion provided on the main surface of the substrate and straddling the signal wiring. The micro-machine that is elastically deformed so as to be in contact with and separated from the signal wiring by the action of an electric field, and that changes electrical characteristics in accordance with the deformation, and is disposed on the side opposite to the signal line of the beam portion, One end away from the signal wiring is supported by being coupled to the micromachine, and the other end forms a cantilever beam projecting toward the signal wiring side, and the beam portion is separated from the signal line. And a sealing member that is provided on the main surface of the substrate and covers the micromachine via a hollow portion.

  A manufacturing method of a micromachine device according to an aspect of the present invention includes a beam portion having a doubly-supported beam shape that is deformed by the action of an electric field on a main surface of a substrate on which a signal line is provided. A step of disposing a micromachine that changes electrical characteristics by changing a relative relationship with the wire, and a micromachine that is disposed on the opposite side of the signal line across the micromachine, and the beam portion is separated from the signal line. A step of disposing a regulating member that regulates deformation; a step of forming a sacrificial layer on the micromachine and the regulating member; and covering the micromachine on the sacrificial layer and a main surface of the substrate via the sacrificial layer. A step of forming a first sealing body having an opening shape portion communicating with the sacrificial layer, and removing the sacrificial layer by introducing a sacrificial layer removing fluid from the opening shape portion. A step, on the first sealing body, characterized by comprising a step of forming a second sealing member, the.

  The present invention can provide a micromachine device in which noise of an output signal is reduced.

  A micromachine device 1 according to a first embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In each figure, the configuration is schematically shown by appropriately enlarging, reducing, or omitting it. In the figure, X, Y, and Z indicate three directions orthogonal to each other.

  The micromachine device 1 is, for example, a microelectromechanical component (MEMS), and includes a base substrate 11 and an insulating layer 12, a signal wiring 15, a MEMS element 16 (micromachine), and a plurality of regulating bridges 18 (regulating members) that constitute the substrate. ) And the like, and the sealing body 20 is hermetically sealed in a state where a hollow portion 17 is formed in which an atmosphere filled with a normal-pressure gas is formed. The sealing body 20 is configured by sequentially laminating a first sealing body 21 and a second sealing body 22 that define the hollow portion 17.

The base substrate 11 is a silicon (Si) substrate, a glass substrate, or a sapphire substrate, and is formed in a predetermined plate shape.
The insulating layer 12 is formed on the base substrate 11 and is made of, for example, a silicon oxide film (SiO ₂ ). The base substrate 11 and the insulating layer 12 constitute a substrate.

  On the upper surface of the insulating layer 12, a lower electrode 13, a drive electrode 14, a signal wiring 15 and a MEMS element 16 are formed. The signal wiring 15 is formed of Au (gold) or the like and extends in the Y direction in FIG. The drive electrode 14 is provided on both sides in the X direction in the drawing on the insulating layer 12 with the signal wiring 15 interposed therebetween.

  A MEMS element 16 is formed on the upper surface of the insulating layer 12. The MEMS element 16 is connected to the lower electrode 13 that communicates with the outside of the sealing body 20. A signal wiring 15 is disposed on the surface of the insulating layer 12 immediately below the MEMS element 16.

  The MEMS element 16 is a movable mechanism part of a micromachine, has a double-supported beam shape having a step, its both end portions are connected to the lower electrode 13, and the central beam part 16 a is about several μm from the signal wiring 15. They are spaced apart with a gap. For example, as will be described later, the gap structure can be secured through a manufacturing process in which the MEMS element 16 is formed on the sacrificial layer 23a having a thickness of about several μm.

The MEMS element 16 is formed by connecting a rectangular plate member made of, for example, Poly-Si or Al through a connection joint 19 made of an insulating SiO ₂ or SiN into a rectangular plate shape. It is structured like a cantilever. This beam-like MEMS element 16 has a spring characteristic, and can be elastically bent and deformed in the thickness direction so that a central portion thereof is displaced in the vertical direction, and has an elastic restoring force.

  For example, when a driving force such as an electrostatic force is applied from the driving electrode 14 as an action of an electric field, the MEMS element 16 is elastically deformed so that the central portion approaches the signal wiring 15 and the driving force is removed. , It returns to its original position again due to its own spring characteristics. That is, the MEMS element 16 is deformed so that the space between the MEMS element 16 and the signal wiring 15 is changed according to the driving force when a driving force such as an electrostatic force is applied and unloaded. Change the electrical characteristics of the device 1. Depending on how it is changed, it performs functions such as variable capacitance and switching.

  In the beam portion 16a of the MEMS element 16, a plurality of openings 16b penetrating in the thickness direction are formed. For this reason, it becomes possible to etch the sacrificial layer 23 in a short time. The opening 16b is disposed directly below a regulation bridge 18 described later. By forming the opening 16b, the area is locally small, and the rigidity is lower than other parts. Therefore, the beam portion 16a is easily deformed downward during pull-in. Further, a sacrificial layer removing dry etching gas, which will be described later, passes through the opening 16b, whereby the sacrificial layer 18 can be etched in a short time.

  The plurality of restriction bridges 18 can be made of the same material as the MEMS element 16 such as TiN or Al, but is preferably made of an insulating material (SiO, SiN) that hardly affects the electrical characteristics of the MEMS element 16.

  The restriction bridge 18 is elongated in the Y direction in the figure, and a plurality of restriction bridges 18 are formed in parallel in the X direction in the figure.

  For example, as shown in FIG. 3, three openings arranged in parallel in the Y direction so as to cover the left and right openings 16b formed in three rows in the Y direction and two rows in the X direction as shown in FIG. One restriction bridge 18 is provided corresponding to 16b. Here, as shown in FIG. 3, six restriction bridges 18 are arranged in the X direction, three on each of the left and right sides.

  The regulating bridge 18 is coupled to the vicinity of the outside of the opening 16b on the MEMS element 16 and extends in the Z direction in the drawing, and is bent from the upper end of the supporting portion 18a and is centered in the X direction in the drawing. That is, it is integrally provided with a rectangular beam-like portion 18b that is long in the Y direction and extends toward the signal wiring 15, and is formed in an L-shaped vertical section.

  That is, the regulation bridge 18 is disposed on the opposite side to the signal wiring 15 with the MEMS element 16 interposed therebetween, that is, on the upper side in the figure, and is separated from the signal wiring 15 when the electrostatic force of the MEMS element 16 is unloaded. Is deformed by contacting the MEMS element 16. Note that, as described above, the beam portion 16a is likely to be locally deformed by the opening 16b in the vicinity of the restriction bridge 18, so that collision at the time of pull-out is promoted.

  Since the MEMS element 16 is covered from the upper side by the restriction bridge 18, an opening shape portion 21 a for introducing a dry etching gas for removing the sacrificial layer 23 is added to the periphery of the MEMS element 16 as described later. It is possible to dispose the upper part of the control bridge 18 above the restriction bridge 18.

  The first sealing body 21 is bonded to the upper surface of the surrounding insulating layer 12 at a position where the edge portion is separated from the MEMS element 16, and the central portion is located above the MEMS element 16 via the hollow portion 17. It is formed so as to cover from. That is, the first sealing body 21 is separated from the MEMS element 16.

The first sealing body 21 is a film having a thickness of about 1 to 2 μm, and is installed at a distance of about several to several tens of μm from the MEMS element 16. For example, as will be described later, the hollow portion 17 can be formed by forming the first sealing body 21 after forming the sacrificial layer having a thickness of about several tens of μm and removing the sacrificial layer 18. The first sealing body 21 is a thin film having a thickness of about 1 to 2 μm, and is installed at a distance of about several to several tens of μm from the MEMS element 16. For example, as will be described later, the hollow portion 17 can be formed by forming the first sealing body 21 after forming the sacrificial layer having a thickness of about several tens of μm and removing the sacrificial layer 23. .

In the manufacturing process, the first sealing body 21 is provided with a plurality of first opening shape portions 21a that are openings provided for introducing a dry etching gas (O ₂ plasma gas or the like) for removing a sacrificial layer. Yes. The first opening shape portion 21 a is disposed at a plurality of positions including the position directly above the MEMS element 16 and corresponding to the position directly above the plurality of restriction bridges 18. The outside of the first sealing body 21 including the opening shape portion 21 a is covered with the second sealing body 22.

  The 2nd sealing body 22 is a film | membrane which has a thickness of about 1-2 micrometers, and is comprised from inorganic materials, such as SiN (silicon nitride). The second sealing body 22 is formed so as to hermetically close the first opening shape portion 21 a and seal the hollow portion 17.

  In the micromachine device 1 having such a configuration, at the time of pull-in when a drive current is applied, the beam portion 16a is deformed so that the central portion thereof is displaced downward as shown in FIG. In addition to contact, the left and right neighborhoods of the central portion are in contact with the drive electrodes 14 respectively.

  When pulling out the drive current, as shown in FIG. 5, an elastic restoring force is generated so that the deformation at the time of pull-in is restored, whereby the central portion is away from the signal wiring 15 and the drive electrode 14. That is, the beam portion 16a is deformed so as to be displaced upward. This elastic restoring force causes the beam portion 16a to vibrate in the thickness direction.

  At this time, when the gap between the vicinity of the opening 16b of the MEMS element 16 and the restriction bridge 18 is reduced and the deformation of the MEMS element 16 proceeds, the beam portion 16a displaced upward comes into contact with the restriction bridge 18 disposed above, collide.

  At this time, since the opening 16b is formed in the vicinity of the restriction bridge 18, the area of the beam portion 16a is locally small and soft by the opening 16b. Therefore, it is easy to be deformed after unloading in the vicinity of the restriction bridge 18, and the gap is likely to be reduced, thereby promoting the collision. By this collision, the significant vibration of the MEMS element 16 can be reduced, and the time until vibration attenuation can be suppressed.

Next, a method for manufacturing the micromachine device 1 according to the present embodiment will be described with reference to FIGS.
First, as shown in FIG. 6, the insulating layer 12 is formed on the base substrate 11, and the signal wiring 15 is formed on the insulating layer 12. Next, as the MEMS element 16, for example, an electrostatic drive type high frequency switch having a cantilever structure using Au as a constituent material is formed.

  At this time, first, in order to provide a gap between the signal wiring 15 and the MEMS element 16, a sacrificial layer 23 a having a predetermined shape to be completely removed in a later process is formed on the signal wiring 15 to form a step. After the formation, the MEMS element 16 is formed on the sacrificial layer 23a. As described above, the MEMS element 16 is formed in a predetermined both-end supported beam shape having the stepped portion and the beam portion 16 a that is separated from the signal wiring 15.

  In particular, when the openings 16b are two-dimensionally arranged, etching can be performed in a short time when the sacrifice layer 23a is removed.

  Next, a beam-shaped regulating bridge 18 having a step is formed on the MEMS element 16 using an inorganic material. At this time, first, in order to provide a gap with the MEMS element 16, a sacrificial layer 23b having a predetermined shape to be completely removed in a later step is formed on the MEMS element 16 to form a step, A restriction bridge 18 is formed on the sacrificial layer 23b. As described above, the support portion 18a on the one end side is supported by the MEMS element 16, and a plurality of predetermined cantilever-shaped restriction bridges 18 that form the beam-shaped portion 18b that is separated from the MEMS element 16 and extends toward the center. It is formed.

  Further, as shown in FIG. 7, a sacrificial layer 23 c is formed on the state where the MEMS element 16 and the regulation bridge 18 are formed so as to cover the MEMS element 16.

  The sacrificial layers 23a, 23b, and 23c are formed by, for example, forming a polyimide film by a spin coating method, forming a predetermined shape by patterning, and curing as shown in FIG.

As shown in FIG. 8, after the formation of the sacrificial layers 23a and 23b, SiO ₂ is formed as a first sealing body 21 with a predetermined thickness by a plasma CVD apparatus.

  Further, a sacrificial layer for introducing a removal material to the first sealing body 21 when removing the sacrificial layers 23a, 23b, and 23c around the MEMS element 16 during or after film formation by photolithography processing or the like. A plurality of opening-shaped portions 21a which are openings for removal and are closed after the sacrifice layer is removed are formed.

Next, an etching material for removing the sacrificial layer is introduced from the opening shape portion 21a, and as shown in FIG. 9, all the sacrificial layers 23a, 23b, and 23c are completely removed. For example, by introducing XeF ₂ gas for selectively removing polycrystalline silicon from the opening shape portion 21a, all the sacrificial layers are removed. As a result, the hollow portion 17 communicating with the outside is formed inside the first sealing body 21 covered.

  Next, low moisture-permeable SiN is formed on the first sealing body 21 with a thickness of, for example, several μm or more so as to cover the first sealing body 21 by, for example, a plasma CVD apparatus or a sputtering apparatus. Then, the second sealing body 22 is formed. By forming the second sealing body 22 by a thin film process, the opening shape portion 21a of the first sealing body 21 is sealed, so that the airtightness of the hollow portion 17 is maintained and leakage of internal air is prevented. Is done.

  Thus, the micromachine device 1 shown in FIGS. 1 and 2 is completed. The package as the micromachine device 1 thus configured can be used for a driver IC chip, for example.

  The micromachine device 1 and the manufacturing method of the micromachine device 1 according to the present embodiment have the following effects. That is, by providing the restriction bridge 18 above the MEMS element 16 toward the central portion where the displacement at the time of vibration is large, the vibration caused by the elastic restoring force of the MEMS element 16 when driving power is unloaded is suppressed. Can do. In addition, since the restriction bridge 18 is provided only on the upper side, there is little influence on the characteristics at the time of pull-in that contacts the signal wiring 15 by being deformed downward.

  For example, the vibration at the center of the beam portion 16a shown in FIGS. 4 and 5 can have an attenuation factor of three times or more as compared with the hollow sealing structure in the case where the restriction bridge 18 is not provided. Therefore, the noise of the output signal can be suppressed and the accuracy as a part can be improved.

  Even if a large number of openings 21 a including the vicinity of the MEMS element 16 corresponding to the upper part of the MEMS element of the first sealing body are provided by covering the upper part of the MEMS element 16 with the restriction bridge 18, the second sealing body Is not deposited on the MEMS element 16, the position of the opening shape portion 21a is not limited. Therefore, it is possible to avoid sacrificing the electrical characteristics and shorten the sacrificial layer 23 removal time.

By providing a large number of openings penetrating the beam portion 16a of the MEMS element 16, the structure is easy to be deformed during pull-in when a driving current is applied, and the etching gas can be removed when the sacrificial layer 23 is removed. Time can be shortened.
Furthermore, since the sealing body 20 is made of an insulating material such as SiO ₂ or SiN, no electric capacitance is formed between the sealing body 20 and the MEMS element 16 having conductivity. Therefore, it is possible to achieve performance having a high capacity change in an electromechanical component that uses a variable electric capacity by avoiding the formation of a capacity between the MEMS element 16 and surrounding conductors.

  Since the opening 16b is disposed in the vicinity of the restriction bridge 18 and is configured to be easily deformed after unloading in the vicinity of the restriction bridge 18, the collision with the restriction bridge 18 at the time of vibration is promoted, and significant vibration can be restricted. And the time until vibration attenuation can be suppressed.

  In addition, this invention is not limited to the said embodiment, The material, shape, arrangement | positioning, size, structure, operation | movement, etc. of each component can be changed suitably and can be implemented.

  For example, although the case where the beam portion 16a is connected via an insulating joint has been described, the same applies to the case where the beam portion 16a is formed by one plate-like member.

  Examples of the patterning method and the sacrificial layer removal method include dry etching with an etching gas and wet etching with a chemical solution. The plurality of sacrificial layers 23a, 23b, and 23c may not be the same material. Further, the structure in which the insulating layer 12 is provided on the base substrate 11 as the substrate has been described. However, the insulating layer 12 is omitted, and the substrate is configured only by the base substrate 11, and the MEMS element 16 and the signal signal are formed on the base substrate 11. The wiring 15 may be formed.

  In addition, the present invention can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The top view which shows the micromachine apparatus concerning one Embodiment of this invention. Sectional drawing of the micromachine apparatus. The top view which expands and shows the principal part of the micromachine apparatus. Sectional drawing which shows the operation | movement at the time of pull-in of the micromachine apparatus. Sectional drawing which shows the operation | movement at the time of pull-out of the micromachine apparatus. Sectional drawing which shows the manufacturing process of the micromachine apparatus. Sectional drawing which shows the manufacturing process of the micromachine apparatus. Sectional drawing which shows the manufacturing process of the micromachine apparatus. Sectional drawing which shows the manufacturing process of the micromachine apparatus. Sectional drawing of an example of a micromachine apparatus. The perspective view of the micromachine apparatus. The top view of the micromachine apparatus. Sectional drawing which shows the manufacturing process of the micromachine apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Micromachine apparatus, 11 ... Base substrate, 12 ... Insulating layer,
14 ... Driving electrode, 15 ... Signal wiring, 16 ... MEMS element (micromachine),
16a ... Beam part, 16b ... Opening, 17 ... Hollow part, 18 ... Restriction bridge (regulation member),
DESCRIPTION OF SYMBOLS 19 ... Connection joint, 20 ... Sealing body, 21 ... 1st sealing body, 21a ... Opening shape part,
22 ... 2nd sealing body, 23a. 23b, 23c ... sacrificial layers.

Claims (8)

A substrate provided with signal wiring on the main surface;
The beam portion is provided on the main surface of the substrate and straddles the signal wiring, and the beam portion is elastically deformed so as to contact and separate from the signal wiring by the action of an electric field. Micromachines that change electrical characteristics
The beam portion is disposed on the opposite side to the signal line, and one end away from the signal line is supported by being coupled to the micromachine, and the other end is a cantilever beam projecting toward the signal line side. And a regulating member that regulates deformation of the beam portion that is separated from the signal line,
A sealing body which is provided on the main surface of the substrate and covers the micromachine through a hollow portion;
A micromachine device comprising: The micromachine device according to claim 1, wherein the displacement is regulated by contacting the regulating member when the beam portion is displaced to the side opposite to the signal line. The electromechanical element according to claim 1, wherein the beam portion of the micromachine is configured such that the vicinity of the regulating member is more easily bent and deformed than other portions.   4. The micromachine device according to claim 1, wherein the beam portion is configured by connecting a plurality of plate-like members via an insulating connecting member. 5. The sealing body is provided on the main surface of the substrate, covers the micromachine via a hollow portion containing gas, and has a first opening shape portion that communicates the hollow portion with the outside. And a second sealing body that is formed on the second sealing body and seals the opening shape portion and the outside.
5. The micromachine device according to claim 1, wherein the opening shape portion is disposed above the micromachine and above the restriction member. 6.   6. The micromachine device according to claim 1, wherein the sealing body is an inorganic material containing SiO or SiN.   The micromachine device according to claim 1, wherein the regulating member is made of an inorganic material. On the main surface of the substrate on which the signal line is provided, there is a beam portion of a doubly supported beam shape that is deformed by the action of an electric field, and the electrical characteristics are changed by changing the relative relationship with the signal line along with the deformation. A step of arranging a micromachine, and a step of disposing a regulating member on the micromachine on the opposite side of the signal line with the micromachine interposed therebetween, and restricting deformation in which the beam portion separates from the signal line;
Forming a sacrificial layer on the micromachine and the regulating member;
Forming a first sealing body on the main surface of the sacrificial layer and the substrate, covering the micromachine via the sacrificial layer and having an opening shape portion communicating with the sacrificial layer;
Introducing a sacrificial layer removing fluid from the opening shape portion to remove the sacrificial layer;
Forming a second sealing body on the first sealing body;
A method of manufacturing a micromachine device, comprising:

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