JP2009192379A - Acceleration sensor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acceleration sensor capable of reducing its instrument size, and a manufacturing method of the same. <P>SOLUTION: The acceleration sensor 1 is provided with a board, a vibratory weight section 11 arranged in opposition to the surface of the board with a gap between, and elastically-deformable beam sections 12 supporting the weight section 11. The acceleration sensor 1 detects a displacement of the weight section 11 and measures an acceleration from the detection result. Movable electrodes 15, 22 which are displaced with the vibration of the weight section 11 are provided in the weight section 11, while fixed electrodes 16, 23 which face the movable electrodes 15, 22 with predetermined intervals inbetween are provided on the board, and at least the weight section 11 is made of metallic glass. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an acceleration sensor and a method for manufacturing the acceleration sensor.

  Conventionally, acceleration sensors are used in various fields such as vehicle control of automobiles, airbags, game machines, and fall detection. As these acceleration sensors, there are sensors in which a weight portion is suspended and supported by a flexible beam portion. In this acceleration sensor, when a mechanical amount is applied to the weight portion from the outside, the weight portion is displaced, the displacement of the weight portion is detected, and the acceleration is measured from the detection result. Various methods are known as a method for detecting the displacement of the weight, and one of them is an acceleration sensor using capacitance (for example, see Non-Patent Document 1).

FIG. 8 is a cross-sectional view showing a conventional acceleration sensor.
As shown in FIG. 8, a conventional acceleration sensor 100 includes a flexible beam portion 103 provided on a substrate 101 via a base portion 102, and a weight portion 104 supported by being suspended from the beam portion 103. And. In addition, on the opposite side of the weight portion 104 with the beam portion 103 interposed therebetween, a plurality of movable electrodes 105 that follow the variation of the weight portion 104 are provided, and a fixed electrode 106 is disposed opposite to each movable electrode 105. ing. A plurality of movable electrodes 105 and each fixed electrode 106 disposed opposite to each movable electrode 105 are configured to detect acceleration in three axes in the X, Y, and Z directions.
The acceleration sensor 100 is in a state in which an electrostatic attractive force is generated between each movable electrode 105 and each fixed electrode 106 and excited in advance with a predetermined input waveform. In this state, when receiving a force such as acceleration from the outside, the weight portion 104 is displaced so as to be twisted about the beam portion 103. Then, the gap between each movable electrode 105 and each fixed electrode 106 changes, and the electrostatic capacitance between each movable electrode 105 and each fixed electrode 106 changes. This change in capacitance is detected and the magnitude of acceleration is measured.
Kazuhiro Okada, “Measurement Technology”, 25 (1), Nippon Kogyo Publishing Co., Ltd., January 1997, p. 50-53

  By the way, in the above-described acceleration sensor, in order to detect a change in capacitance with high sensitivity, it is common to form the weight portion with silicon. However, since silicon has a small specific gravity and light weight, there is a problem that when the weight portion is formed of silicon, the size of the weight portion must be ensured. In particular, in the acceleration sensor 100 that performs triaxial acceleration detection in the X, Y, and Z directions, as shown in FIG. The displacement of the weight portion 104 must be ensured. As a result, there is a problem that the apparatus is increased in size.

  Therefore, the present invention has been made to solve the above-described problems, and provides an acceleration sensor and a method of manufacturing the acceleration sensor that can reduce the size of the apparatus.

The present invention provides the following means in order to solve the above problems.
An acceleration sensor according to the present invention includes a substrate, a vibratable weight portion disposed opposite to the surface of the substrate with a gap, and an elastically deformable beam portion supporting the weight portion, In an acceleration sensor that detects displacement of a weight portion and measures acceleration based on the detection result, at least the weight portion is made of a metallic substance.

  In the acceleration sensor according to the present invention, since the weight portion is made of a metallic substance, the specific gravity is larger than that of a conventional weight portion made of silicon. That is, even if the weight portion is reduced, the weight portion can be maintained and the displacement of the weight portion can be ensured to be large, so that the apparatus can be downsized.

  In the acceleration sensor according to the present invention, in the acceleration sensor, the weight portion is provided with a movable electrode that is displaced along with the vibration of the weight portion, while the substrate is separated from the movable electrode by a predetermined distance. The fixed material which opposes is provided, and the said metallic substance consists of metallic glass.

Here, metallic glass is a kind of amorphous alloy, and has three principles: a multi-component system with three or more elements, a diameter of each atom that differs by 12% or more, and that each element is easily compounded. And has the characteristics of high toughness, rigidity, springiness, and conductivity.
In the acceleration sensor according to the present invention, the specific gravity is larger than that of the conventional weight portion made of silicon by using metallic glass as the metallic substance. In other words, even if the weight portion is made smaller, the weight portion can be maintained and the displacement of the weight portion can be ensured to be large. Therefore, the change in the capacitance between the movable electrode and the fixed electrode is increased, and the electrostatic capacity is increased. Capacitance change can be detected with high sensitivity.
Further, since the internal stress is small, there is no warping or deformation of the weight portion. Therefore, the gap between the movable electrode and the fixed electrode becomes uniform, and the change in capacitance can be detected with high accuracy.
Therefore, it is possible to detect a change in capacitance between the movable electrode and the fixed electrode with high accuracy and high sensitivity while reducing the size of the device, thereby realizing a high-performance acceleration sensor. be able to.

  The acceleration sensor according to the present invention is characterized in that, in the acceleration sensor, the metallic substance is made of metal.

  In the acceleration sensor according to the present invention, by using a metal as the metallic substance, the specific gravity is larger than that of a conventional weight portion made of silicon. In other words, the weight of the weight can be maintained even when the weight is reduced, and the displacement of the weight can be ensured to be large, so that the apparatus can be downsized.

  The acceleration sensor according to the present invention is characterized in that, in the acceleration sensor, the beam portion is made of the metallic glass.

In the acceleration sensor according to the present invention, since the beam portion is made of metal glass, the spring property of the beam portion can be improved. Thus, the elastic deformation of the beam portion allows the weight portion to follow the elastic force of the beam portion, thereby ensuring a large displacement of the weight portion. Therefore, the change in capacitance between the movable electrode and the fixed electrode becomes large. Therefore, acceleration can be detected with high sensitivity.
Furthermore, since the beam portion is made of metal glass, the beam portion can be integrally formed with the weight portion. Therefore, manufacture of a weight part and a beam part becomes easy, and manufacturing efficiency can be improved.

  The acceleration sensor according to the present invention is characterized in that, in the acceleration sensor, the movable electrode is made of the metallic glass.

  In the acceleration sensor according to the present invention, since the movable electrode is made of metal glass, the movable electrode and the weight portion can be integrally formed, and the manufacturing efficiency can be improved.

  In the acceleration sensor according to the present invention, in the acceleration sensor, the weight portion includes a first movable electrode extending in one direction and a second movable electrode extending in another direction orthogonal to the one direction. And a first fixed electrode and a second fixed electrode facing each of the first and second movable electrodes with a predetermined distance therebetween, and a predetermined distance from the weight portion. A third fixed electrode that is opposed to each other in a state where a gap is left is provided.

  In the acceleration sensor according to the present invention, since the weight portion is made of metal glass, the weight portion can be used as a movable electrode facing the third fixed electrode. Then, accelerations orthogonal to each other can be detected by each movable electrode and each fixed electrode opposed to each movable electrode. Therefore, it is possible to easily manufacture an acceleration sensor capable of detecting triaxial acceleration in the X, Y, and Z directions.

  On the other hand, a method for manufacturing an acceleration sensor according to the present invention includes a substrate, a vibrated weight portion that is opposed to the surface of the substrate with a gap, and an elastically deformable beam portion that supports the weight portion. , A method of manufacturing an acceleration sensor that detects displacement of the weight part and measures acceleration from the detection result, and forms the weight part and the beam part made of metal glass on the substrate. A film forming process and a heat treatment process for heating the metal glass to flatten the weight portion after the film forming process are provided.

Here, when the metal glass is heated, the metal glass softens in a semi-solid state in a certain temperature region called a supercooled liquid region, and exhibits a viscous flow similar to that of the oxide glass. In this supercooled liquid region, the metallic glass is deformed and cooled, so that it can be fixed while maintaining the deformation (so-called heating deformation method). By using this method, internal stress is relieved, so that a planar structure with high flatness and a ternary structure by fine molding can be easily manufactured.
In the method for manufacturing an acceleration sensor according to the present invention, the metal glass exhibits a supercooled liquid region by heating the metal glass in the heat treatment step. Thereby, processing of metal glass becomes easy and the weight part after a film-forming process can be flattened easily.

  The acceleration sensor manufacturing method according to the present invention is characterized in that, in the acceleration sensor manufacturing method, the heat treatment step includes a compression step of compressing the beam portion.

  In the method for manufacturing the acceleration sensor according to the present invention, the beam portion can be formed in a shape corresponding to the compression force by applying a compression force to the beam portion in the supercooled liquid region. The part can be easily deformed into a predetermined shape. Thereby, since a highly springy beam part can be formed easily, a highly sensitive acceleration sensor can be manufactured.

  According to the acceleration sensor of the present invention, the weight of the weight portion can be maintained and the displacement of the weight portion can be ensured greatly even if the weight portion is made small, so that the apparatus can be downsized.

(Acceleration sensor)
Next, the acceleration sensor of the present invention will be described with reference to FIGS.
In each of the drawings shown below, the scale of each layer and each member is different in order to make each layer and each member recognizable on the drawing.

FIG. 1 is a plan view of the acceleration sensor. 2 is a cross-sectional view of the acceleration sensor, and is a cross-sectional view taken along the line AA ′ of FIG.
As shown in FIGS. 1 and 2, the acceleration sensor 1 includes a substrate (see FIG. 2) 10, a weight portion 11 provided on the substrate 10, and a beam portion 12. The substrate 10 is a rectangular flat plate member made of silicon or the like, and has a rigidity that does not cause deformation or vibration that affects the detection of acceleration even if it receives an inertial force caused by acceleration within a detectable range. Have.

  On the substrate 10, a plurality of (for example, four) posts 13 a to 13 d made of metal glass (metallic substance) to be described later are provided. Each of the posts 13 a to 13 d has a prismatic shape provided so as to rise vertically to the surface of the substrate 10, and is disposed so as to surround the periphery of the weight portion 11. Specifically, two posts 13a and 13c whose longitudinal direction is the direction along the X direction and two posts 13b and 13d whose longitudinal direction is the direction along the Y direction sandwich the weight part 11, respectively. They are arranged in pairs.

  One ends of beam portions 12 made of metal glass are connected to the tips of the posts 13a to 13d. Each beam portion 12 is formed in a spring shape that is bent and folded several times in a direction (Y direction) orthogonal to an extending direction (X direction) from one end to the other end. Thereby, each beam part 12 is comprised so that elastic deformation is possible with respect to the triaxial direction of X, Y, and Z direction.

  The weight portion 11 is a rectangular (square) flat plate member made of metal glass, and is integrally formed with the beam portion 12. Specifically, the weight portion 11 has both sides of the two axes along the X direction and the Y direction connected to the other ends of the pair of beam portions 12, and is opposed to each other with a gap on the surface of the substrate 10. Has been. Thereby, the weight part 11 is comprised so that a vibration is possible with respect to the three-axis directions of X, Y, and Z direction.

A first movable electrode 14 made of metal glass is integrally formed with the weight portion 11 on one side surface along the Y direction of the weight portion 11. The first movable electrode 14 includes a plurality of electrode pieces 15 extending in the X direction orthogonal to the side surface of the weight portion 11 along the Y direction. Each electrode piece 15 extends in parallel, and is configured as a comb-shaped first movable electrode 14 by a plurality of electrode pieces 15.
A first fixed electrode 16 is provided on the substrate 10 so as to face the first movable electrode 14 with a predetermined distance. The first fixed electrode 16 includes a base portion 17 having a rectangular shape in plan view, and an extending portion 18 extending from the base portion 17 in the Y direction. A plurality of electrode pieces 19 are formed on the side surface along the longitudinal direction of the extending portion 18 so as to extend perpendicularly to the side surface along the Y direction of the weight portion 11 from this side surface. The electrode pieces 19 are arranged so as to be sandwiched between the electrode pieces 15 of the first movable electrode 14 described above, and each of them is arranged alternately with a predetermined gap. The first movable electrode 14 and the first fixed electrode 16 constitute a first detector 20 that detects the displacement of the weight 11 in the Y direction.

On the other hand, the second movable electrode 21 made of metal glass is integrally formed with the weight part 11 on the side surface along the X direction of the weight part 11. The second movable electrode 21 includes a plurality of electrode pieces 22 extending in the Y direction orthogonal to the side surface along the X direction of the weight portion 11. Each electrode piece 22 extends in parallel, and is configured as a comb-like second movable electrode 21 by a plurality of electrode pieces 22.
A second fixed electrode 23 is provided on the substrate 10 so as to face the second movable electrode 21 with a predetermined distance. The second fixed electrode 23 includes a base portion 24 having a rectangular shape in plan view, and an extending portion 25 extending from the base portion 24 in the X direction. On the side surface along the longitudinal direction of the extending portion 25, a plurality of electrode pieces 26 extending from the side surface orthogonal to the side surface along the X direction of the weight portion 11 are formed. The electrode pieces 26 are arranged so as to be sandwiched between the electrode pieces 22 of the second movable electrode 21 described above, and each of them is arranged alternately with a predetermined gap. The second movable electrode 21 and the second fixed electrode 23 constitute a second detector 27 that detects the displacement of the weight 11 in the X direction.

Further, an etching stop layer 36 made of aluminum or the like is formed on the lower surfaces of the weight part 11 and the beam part 12. The etching stop layer 36 is a flat plate having substantially the same shape as the weight portion 11 and the beam portion 12, and is configured as a third movable electrode facing the third fixed electrode 28 with a predetermined distance. Yes.
Further, a third fixed electrode 28 made of a conductive material such as aluminum is provided on the surface of the substrate 10 at a position facing the lower surface of the etching stop layer 36. The third fixed electrode 28 is a flat plate formed in substantially the same shape as the weight portion 11, and is disposed with a gap from the lower surface of the weight portion 11. The etching stop layer 36 and the third fixed electrode 28 constitute a third detector 29 that detects the displacement of the weight 11 in the Z direction.

  As described above, the acceleration sensor 1 of the present embodiment is configured such that accelerations in directions orthogonal to each other can be detected by the first to third detection units 20, 27, and 29. That is, it is configured such that three-axis acceleration in the X, Y, and Z directions can be detected. The movable electrodes 14 and 21 and the etching stop layer 36 and the fixed electrodes 16, 23, and 28 described above are connected to an external power source via an electric circuit (not shown).

  Here, the weight part 11 and the beam part 12, the posts 13a to 13d, the movable electrodes 14, 21 and the fixed electrodes 16, 23, 28 are all made of metal glass. Metallic glass is a kind of amorphous alloy, and it has three principles: the composition is a multi-element system with three or more elements, the diameter of each atom is different by 12% or more, and each element is easily compounded. It has the characteristics of high toughness, rigidity, springiness, and conductivity. Specific examples of such a metal glass material include PdCuSi and CuZrTi.

Next, the operation will be described.
First, the movable electrodes 14 and 21 and the etching stop layer 36 and the fixed electrodes 16, 23 and 28 facing the movable electrodes 14, 21 and the etching stop layer 36 are preliminarily set to each other through an electric circuit (not shown). Excited with input waveform. Specifically, a voltage is applied to each movable electrode 14, 21 and etching stop layer 36 and each fixed electrode 16, 23, 28 from an external power source (not shown), and each movable electrode 14, 21 and etching stop layer 36 is Then, an electrostatic attractive force is generated on each of the fixed electrodes 16, 23 and 28.

  In this state, when the acceleration sensor 1 receives acceleration from the outside, the beam portion 12 is elastically deformed along the direction in which the acceleration is received, and the weight portion 11 vibrates so as to follow the elastic deformation of the beam portion 12. Accordingly, the movable electrodes 14 and 21 integrally formed with the etching stop layer 36 and the weight portion 11 and the fixed electrodes 16, 23, and 28 are relatively moved. Specifically, the weight 11 and the electrode pieces 15 and 22 of the movable electrodes 14 and 21 and the electrode pieces 19 and 26 of the fixed electrodes 16, 23, and 28 approach and separate from each other.

  Then, the gap between each movable electrode 14, 21 and etching stop layer 36 and each fixed electrode 16, 23, 28 changes, and each movable electrode 14, 21 and etching stop layer 36, each fixed electrode 16, The capacitance between 23 and 28 changes. This change in capacitance is detected and converted into an electrical signal corresponding to the acceleration. Thereby, the acceleration received by the acceleration sensor 1 can be measured.

(Acceleration sensor manufacturing method)
Next, the manufacturing method of the acceleration sensor of this embodiment is demonstrated. 3 to 7 are process diagrams of the acceleration sensor. 3 to 5 are sectional views corresponding to the line AA ′ in FIG. 1, FIG. 6 is a plan view of the acceleration sensor corresponding to the step of FIG. 4A, and FIG. The process drawing of is shown.
The acceleration sensor 1 (see FIG. 1) of the present embodiment is a so-called MEMS (Micro Electro Mechanical Systems) technology that uses a high-precision three-dimensional processing technology based on a semiconductor manufacturing technology to produce a high-functional device in μ size. It is manufactured using. Specifically, the MEMS technology is manufactured using a so-called surface micromachining technology in which a high-functional device is manufactured by repeatedly forming a thin film on a substrate, photolithography, and etching.

  First, as shown in FIG. 3A, the third fixed electrode 28 is formed on the substrate 10. Specifically, after forming a metal layer (not shown) made of aluminum or the like on the entire surface of the substrate 10 by sputtering or vacuum deposition, etc., a resist mask (not shown) exposed and developed by photolithography technology on the metal layer. Form. Then, by performing dry etching through a resist mask, the metal layer is patterned to form the third fixed electrode 28 having the shape described above. Note that photosensitive polyimide or the like can be used for the resist mask described above.

Next, as shown in FIG. 3B, a resin layer 33 is formed on the substrate 10 on which the third fixed electrode 28 is formed. Specifically, a resin material such as polyimide is applied to the entire surface of the substrate 10 by spin coating.
And as shown in FIG.3 (c), the resin layer 33 of the area | region which should form post 13a-13d mentioned above, the 1st fixed electrode 16, and the 2nd fixed electrode 23 (refer FIG. 1) is removed, and it is an opening part. 33a is formed. Specifically, when a photosensitive resin material such as photosensitive polyimide is used as a constituent material of the resin layer 33, the opening 33a is formed by performing dry etching through the resin layer exposed and developed by a photolithography technique. Is formed. When a resin material other than the photosensitive resin material is used as a constituent material of the resin layer 33, the opening 33a is irradiated by irradiating the excimer laser to the resin layer 33 in a region where the opening 33a is to be formed. Is formed. The wavelength of the excimer laser is preferably about 248 nm.

Next, the posts 13 a to 13 d, the first fixed electrode 16, and the second fixed electrode 23 are formed on the substrate 10. Specifically, first, as shown in FIG. 3D, a metallic glass film 35 is formed on the entire surface of the substrate 10 by sputtering or the like. Then, the surface of the metal glass film 35 formed on the resin layer 33 is polished to leave only the metal glass film 35 formed in the opening 33a.
Thereby, as shown in FIGS. 4A and 6, posts 13 a to 13 d having a predetermined shape, the first fixed electrode 16, and the second fixed electrode 23 (see FIG. 1) are formed. In FIG. 6, the resin layer 33 is not shown for easy understanding. Thus, in this embodiment, since the posts 13a to 13d, the first fixed electrode 16, and the second fixed electrode 23 can be integrally formed of metal glass, the manufacturing becomes easy and the manufacturing efficiency can be improved. it can.

  Next, as shown in FIG. 4B, an etching stop layer 36 is formed on the resin layer 33. Specifically, after forming a metal layer (not shown) made of aluminum or the like on the entire surface of the substrate 10 by sputtering or vacuum deposition, etc., a resist mask (not shown) exposed and developed by photolithography technology on the metal layer. Form. Then, by performing dry etching through a resist mask, the metal layer is patterned to form an etching stop layer 36 having a predetermined shape.

Next, as shown in FIG. 4C, a resin layer 37 made of a resin material such as polyimide is formed on the substrate 10 on which the etching stop layer 36 is formed. Specifically, first, a resin material is applied to the entire surface of the substrate 10 by spin coating.
Then, as shown in FIG. 4D, the resin layer 37 is irradiated with an excimer laser to form the weight part 11 and the beam part 12, the first movable electrode 14, and the second movable electrode 21 (see FIG. 1). The resin layer 37 in the region is removed to form an opening 37a. The wavelength of the excimer laser is preferably about 248 nm. When an excimer laser having a wavelength of 248 nm is used, the resin layer 37 in the region where the weight part 11 and the beam part 12, the first movable electrode 14, and the second movable electrode 21 (see FIG. 1) are to be formed is efficiently removed by ablation. The At this time, since the etching stop layer 36 is formed between the resin layer 33 and the resin layer 37, the excimer laser is transmitted through the etching stop layer 36 (for example, the resin layer 33 and the posts 13 a to 13 d). Instead, the resin layer 37 can be removed by a predetermined depth.

Next, as shown in FIG. 5A, the weight part 11, the beam part 12, and the movable electrodes 14 and 21 are formed on the substrate 10 on which the opening part 37a is formed. Specifically, first, a metal glass film 39 is formed on the entire surface of the substrate 10 by sputtering or the like (film formation process).
Then, as shown in FIG. 5B, the surface of the metal glass film 39 is polished to leave only the metal glass film 39 formed in the opening 37a.

Next, a heat treatment step for heating the metallic glass film 39 is performed.
Here, when the above-described metal glass is heated, the metal glass softens in a semi-solid state in a certain temperature region called a supercooled liquid region, and exhibits a viscous flow similar to that of oxide glass. In this supercooled liquid region, the metallic glass can be deformed and cooled to be fixed in a state where the deformation is maintained (so-called heating deformation method). By using this method, relaxation of internal stress is relieved, so that a planar structure with high flatness and a ternary structure by fine molding can be easily manufactured.

The metallic glass film 39 formed in the formation region of the weight part 11, the first movable electrode 14, and the second movable electrode 21 is flattened using the heating deformation method described above. Specifically, the substrate 10 on which the metal glass film 39 is formed is placed on a hot plate (not shown) and heated to about 200 ° C. to hold the metal glass film 39 in the supercooled liquid region. Then, by pressing the surface of the metal glass film 39 with a pressing plate (not shown), the metal glass film 39 is planarized following the surface of the etching stop layer 36 and the like formed under the metal glass film 39.
In the heat treatment step, the metal glass film 39 can be softened at a relatively low temperature by holding the metal glass film 39 in the supercooled liquid region. Thereby, the processing of the metal glass film 39 is facilitated, and the weight part 11 (see FIG. 1) after the film forming process can be easily flattened.

  Subsequently, the metal glass film 39 formed in the region where the beam portion 12 is formed is compressed in a state where the metal glass film 39 is held in the supercooled liquid region (compression step). As shown in FIG. 7A, in the compression step, the metal glass film 39 formed in the region where the beam portion 12 is formed is compressed using the press device 40. The press device 40 includes a pair of molding parts 41a and 41b in which corrugated irregularities are formed.

And as shown in FIG.7 (b), the metal glass film | membrane 39 formed in the formation area of the beam part 12 is pinched | interposed from the both sides of the width direction by a pair of molding part 41a, 41b. Then, since the metallic glass film 39 held in the supercooled liquid region is deformed according to the magnitude of the compressive force acting from the press device 40, the metal glass film 39 is stretched following the shapes of the molding parts 41a and 41b.
In the compression step, with the metallic glass film 39 held in the supercooled liquid region, a compressive force is applied to the beam portion 12 (see FIG. 1), so that the beam portion 12 is shaped into a shape corresponding to the compressive force. Since it can be formed, the beam portion 12 can be easily deformed into a predetermined shape. Thereby, since the beam part 12 with a high spring property can be formed easily, since the displacement of the weight part 11 can be ensured more largely, the highly sensitive acceleration sensor 1 can be manufactured.

  In the heat treatment step, the posts 13a to 13d and the beam portions 12 are also connected at the same time. Thus, in this embodiment, since the weight part 11, the beam part 12, and the movable electrodes 14 and 21 can be integrally formed by metal glass, manufacture becomes easy and manufacturing efficiency can be improved.

Then, after finishing the heat treatment step, the substrate 10 is cooled to fix the metallic glass film 39. Thereby, the weight part 11 and the beam part 12, the 1st movable electrode 14, and the 2nd movable electrode 21 of a predetermined shape are formed. Thereafter, the resin layers 33 and 37 formed around and below the weight portion 11 are removed using wet etching or the like.
Thus, the acceleration sensor (see FIGS. 1 and 2) 1 of the present embodiment is completed.

  Thus, in the manufacturing method of the acceleration sensor 1 of the present embodiment, the posts 13a to 13d, the fixed electrodes 16, 23, the weight part 11, the beam part 12, and the movable electrodes 14, 21 using the surface micromachining technique described above. Can be collectively formed of metallic glass, and therefore, the acceleration sensor 1 capable of detecting the three-axis directions of the X, Y, and Z directions can be easily manufactured.

Therefore, according to this embodiment, since the weight part 11 is comprised with the metal glass, specific gravity is large compared with the weight part which consists of conventional silicon | silicone. That is, even if the weight part 11 is made small, the weight part 11 can be maintained and the displacement of the weight part 11 can be kept large, so that the movable electrodes 14, 21 and the fixed electrodes 16, 23, 28 can be The change in capacitance between the two increases. Thereby, the change in capacitance can be detected with high sensitivity. Further, since the internal stress is small, there is no warping or deformation of the weight portion. Therefore, the gap between each movable electrode 14, 21 and each fixed electrode 16, 23, 28 becomes uniform, and the change in capacitance can be detected with high accuracy.
Furthermore, since the beam part 12 is also comprised with the metal glass, the spring property of the beam part 12 can be improved. Thereby, since the weight part 11 follows the elastic force of the beam part 12, when the beam part 12 elastically deforms, the displacement of the weight part 11 can be ensured more largely.
Moreover, since each movable electrode 14 and 21 is also comprised with the metal glass, the highly conductive movable electrodes 14 and 21 can be formed, and the change of an electrostatic capacitance can be detected with higher sensitivity.
Therefore, after miniaturizing the apparatus, the change in capacitance between the movable electrodes 14 and 21 and the etching stop layer 36 and the fixed electrodes 16, 23, and 28 can be made with high accuracy and high sensitivity. Since it can detect, the high-performance acceleration sensor 1 is realizable.

  The accelerations orthogonal to each other can be detected by the movable electrodes 14 and 21 and the etching stop layer 36 and the fixed electrodes 16, 23 and 28 facing the movable electrodes 14 and 21. Therefore, it is possible to easily manufacture the acceleration sensor 1 that can detect the triaxial acceleration in the X, Y, and Z directions.

In addition, this invention is not necessarily limited to the thing of the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the present embodiment, the case where metallic glass is used as the metallic substance has been described, but it is also possible to use a metal such as aluminum. Also in this configuration, the weight of the weight can be maintained even if the weight is made smaller than the weight made of conventional silicon. Thereby, since the displacement of the weight part can be secured largely, the apparatus can be miniaturized.
Moreover, in this embodiment, although the case where all of a weight part, a beam part, a movable electrode, a fixed electrode, and a post was comprised with metal glass was demonstrated, at least a weight part should just be comprised with metal glass. Silicon or the like can be used as a material other than the metal glass.
In this embodiment, the side surface along the X direction and the Y direction of the weight portion is supported by four beam portions arranged in two directions orthogonal to each other, but the corner portions of the weight portion are supported respectively. Thus, even if the beam portion is arranged, the acceleration in the triaxial direction can be detected. Moreover, you may arrange | position four or more beam parts.

  In the present embodiment, the acceleration sensor has been described as an example of a configuration that can detect acceleration in three axes. However, the acceleration sensor may be modified to detect acceleration in one axis and two axes. . For example, if it is the structure which supports one direction of a weight part using a pair of beam part, the acceleration of a uniaxial direction can be detected.

  In the present embodiment, the case where the etching stop layer is formed on the lower surfaces of the weight portion and the beam portion has been described. However, a configuration in which the etching stop layer is not provided may be employed. According to this configuration, as described above, the weight portion is made of metal glass, and the weight portion itself has conductivity, so that the weight portion serves as the third movable electrode facing the third fixed electrode with a predetermined distance therebetween. Can be configured. Accordingly, the weight portion and the third fixed electrode can be configured as a third detection portion that detects the displacement of the weight portion in the Z direction. The accelerations orthogonal to each other can be detected by the first and second movable electrodes and the etching stop layer and the fixed electrodes facing the first and second movable electrodes and the etching stop layer. Therefore, it is possible to easily manufacture an acceleration sensor that can detect three-axis acceleration in the X, Y, and Z directions while simplifying the manufacturing process.

In the present embodiment, the planar view shape of the weight portion is a square and each beam portion has the same shape. However, for example, the planar view shape of the weight portion is, for example, a circular shape. It is possible to change the set as appropriate.
Furthermore, the design of the shape of the beam portion and the compression method can be changed as appropriate. Thereby, the elasticity modulus of a beam part can be determined easily.
In the present embodiment, the beam portion and the post are formed in separate steps, but the beam portion and the post can be formed integrally. Specifically, it is possible to manufacture by bending one end of the beam portion toward the substrate while holding the beam portion in the supercooled liquid region, and connecting one end of the beam portion to the surface of the substrate. is there.

It is a top view of the acceleration sensor in the embodiment of the present invention. It is sectional drawing which follows the A-A 'line of FIG. It is process drawing of an acceleration sensor. It is process drawing of an acceleration sensor. It is process drawing of an acceleration sensor. FIG. 5 is a plan view of an acceleration sensor corresponding to FIG. It is process drawing which shows a compression process. It is sectional drawing which shows the conventional acceleration sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Acceleration sensor 10 ... Board | substrate 11 ... Weight part 12 ... Beam part 14 ... 1st movable electrode 16 ... 1st fixed electrode 21 ... 2nd movable electrode 23 ... 2nd fixed electrode 28 ... 3rd fixed electrode

Claims (8)

A substrate,
A vibrable weight portion disposed opposite to the surface of the substrate with a gap;
An elastically deformable beam portion that supports the weight portion,
In the acceleration sensor that detects the displacement of the weight portion and measures the acceleration from the detection result,
An acceleration sensor, wherein at least the weight portion is made of a metallic substance. The weight part is provided with a movable electrode that is displaced along with the vibration of the weight part, whereas the substrate is provided with a fixed electrode facing the movable electrode with a predetermined distance therebetween,
The acceleration sensor according to claim 1, wherein the metallic substance is made of metallic glass.   The acceleration sensor according to claim 1, wherein the metallic substance is made of metal.   The acceleration sensor according to claim 2, wherein the beam portion is made of the metal glass.   The acceleration sensor according to claim 2, wherein the movable electrode is made of the metallic glass. The weight portion is provided with a first movable electrode extending in one direction and a second movable electrode extending in another direction orthogonal to the one direction,
On the substrate, there are provided first and second fixed electrodes that face the first and second movable electrodes with a predetermined distance, respectively, and face the weight portion with a predetermined distance. The acceleration sensor according to any one of claims 1 to 5, wherein a third fixed electrode is provided. A substrate,
A vibrable weight portion disposed opposite to the surface of the substrate with a gap;
An elastically deformable beam portion that supports the weight portion,
A method of manufacturing an acceleration sensor for detecting displacement of the weight part and measuring acceleration from the detection result,
A film forming step of forming the weight part and the beam part made of metal glass on the substrate;
A method of manufacturing an acceleration sensor, comprising: a heat treatment step of flattening the weight portion by heating the metal glass after the film formation step.   The method of manufacturing an acceleration sensor according to claim 7, wherein the heat treatment step includes a compression step of compressing the beam portion.

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