WO2019230552A1 - Physical quantity sensor - Google Patents

Abstract

Provided is a physical quantity sensor which outputs, when a physical quantity is applied, a signal according to the physical quantity and is provided with: a support substrate (11) having one surface (11a); a fixing member (20) partially fixed to the support substrate on one surface thereof; an operation unit (30) having driving spindles (33, 34), detection spindles (35, 36), and a detection unit (60); and a driving unit 50 which vibrates the driving spindles, wherein the detection unit generates, when a physical quantity is applied while the driving spindles are driving-vibrated, an electrical output based on the movement of the detection spindles accompanied by the application of the physical quantity. The fixing member comprises: a fixing part (21) connected to the support substrate; and floating parts (22) extending from the fixing part to both sides of the fixing part, with the fixing part therebetween. The floating parts are disposed to be spaced apart from the support substrate with a gap therebetween in a normal direction to one surface thereof and are in a floated state, and the operation unit is supported by portions of both end sides of at least the floating parts with the fixing part therebetween.

Description

Physical quantity sensor Cross-reference to related applications

This application is based on Japanese Patent Application No. 2018-104714 filed on May 31, 2018, the contents of which are incorporated herein by reference.

This disclosure relates to a physical quantity sensor.

2. Description of the Related Art Conventionally, a spring mass type physical quantity sensor that detects a physical quantity applied based on a displacement of a weight supported by a spring with the application of a physical quantity is known. An example of this type of physical quantity sensor is disclosed in Patent Document 1.

The physical quantity sensor described in Patent Document 1 is applied to a vibration-type angular velocity sensor or the like, and is supported by a fixed portion and a fixed electrode supported by a substrate, and supported by a fixed portion via a spring (beam portion). And a movable part provided with a detection electrode. This movable part is arranged with a gap from the substrate, and has a plurality of weights and beams, and a ladder-like structure in which a plurality of weights opposed to each other at a predetermined interval are connected by beams at both ends. The so-called ladder structure is used. In this physical quantity sensor, the distance between the fixed electrode and the detection electrode changes due to the displacement of the weight supported by the beam and the detection electrode in accordance with the application of the physical quantity, and the capacitance formed between them changes. Based on this, a physical quantity is detected.

JP 2014-6238 A

In the physical quantity sensor, since the movable part is supported by the fixed part via a plurality of beams, when distortion occurs in a direction twisting the substrate to which the fixed part is connected (hereinafter referred to as “twist distortion”), This distortion is transmitted to the movable part, thereby causing a physical quantity detection error.

Specifically, in the physical quantity sensor, when a distortion occurs in the substrate, the fixed portion is displaced by the displacement of the substrate, and the movable portion supported by the fixed portion via the beam is also twisted similarly to the substrate. It will be in the state. In this physical quantity sensor, in a state where the movable part is twisted in this way, even if a physical quantity is applied, the influence of the physical quantity is not accurately transmitted to the detection part, and an error occurs in detection, resulting in a characteristic error.

This disclosure is intended to provide a physical quantity sensor in which occurrence of a characteristic error is suppressed even when a twist distortion occurs in a substrate.

In order to achieve the above object, the physical quantity sensor according to the first aspect is a physical quantity sensor that outputs a signal corresponding to a physical quantity when the physical quantity is applied, and is supported on a supporting substrate having one side and on one side. A fixing member that is partially fixed to the substrate, a drive weight, a detection weight, a movable portion having a detection portion, and a drive portion that vibrates the drive weight. In such a configuration, when a physical quantity is applied while driving the drive weight, the detection unit generates an electrical output based on the movement of the detection weight accompanying the application of the physical quantity, and the fixing member is It is composed of a fixed part connected to the support substrate and floating parts extending from the fixed part on both sides of the fixed part. The floating part is arranged with a gap from the support substrate in the normal direction to one surface. The movable portion is supported through at least the portions on both ends of the floating portion sandwiching the fixed portion.

Thus, the movable part including the detection part is supported via the floating part arranged with a gap from the substrate among the fixed members fixed to the substrate. Therefore, even if a torsional distortion occurs in the substrate, the torsional distortion of the movable part due to the torsional distortion of the substrate is reduced as compared with the conventional case, and the physical quantity sensor is suppressed in the characteristic error.

Note that reference numerals with parentheses attached to each component and the like indicate an example of a correspondence relationship between the component and the like and specific components described in the embodiments described later.

It is a plane schematic diagram which shows the vibration type angular velocity sensor of 1st Embodiment. It is a schematic sectional drawing which shows the cross-sectional structure between II-II shown in FIG. It is the schematic diagram which showed the mode at the time of basic operation | movement of the vibration type angular velocity sensor of FIG. It is the schematic diagram which showed the mode when an angular velocity was applied to the said vibration type angular velocity sensor during the basic operation | movement of FIG. In a conventional vibration type angular velocity sensor, it is a mimetic diagram showing the state where twist distortion occurred in a substrate. In the vibration type angular velocity sensor of the first embodiment, it is a schematic diagram showing a state in which twist distortion occurs in a substrate. It is a plane schematic diagram which shows the vibration type angular velocity sensor of 2nd Embodiment. It is the schematic diagram which showed the mode at the time of basic operation | movement of the vibration type angular velocity sensor of FIG. FIG. 8 is a schematic diagram showing a state when an angular velocity is applied to the vibration type angular velocity sensor during the basic operation of FIG. 7. It is the enlarged view which showed the mode of the displacement of the 1st detection beam in FIG. It is a plane schematic diagram which shows the vibration type angular velocity sensor of 3rd Embodiment. It is a plane schematic diagram which shows the other example of a fixing member. It is a schematic sectional drawing which shows the other example of a fixing member. It is a plane schematic diagram which shows the other example of a fixing member.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
As an example of the physical quantity sensor of the first embodiment, an example applied to a vibration type angular velocity sensor, that is, a gyro sensor will be described with reference to FIG. In FIG. 1, in order to make the configuration easy to understand, a boundary portion between a fixing portion 21 and a floating portion 22 constituting a fixing member 20 described later is indicated by a broken line for convenience.

For simplification of the following description, as shown in FIG. 1, the left-right direction in FIG. 1 is the “x-axis direction” and the direction perpendicular to the x-axis direction in the plane of the paper is “y-axis direction”. And a direction perpendicular to the xy plane is referred to as a “z-axis direction”.

The vibration type angular velocity sensor of the present embodiment is a sensor for detecting an angular velocity, and is used for detecting a rotational angular velocity around a center line parallel to the vertical direction of the vehicle, for example. In this case, the vibration type angular velocity sensor of the present embodiment is mounted on the vehicle such that the normal direction to the paper surface of FIG. 1 coincides with the vertical direction of the vehicle. Of course, the vibration type angular velocity sensor of the present embodiment can be applied to uses other than those for vehicles.

The vibration type angular velocity sensor of the present embodiment is formed on one surface side of a plate-like substrate 10 as shown in FIG. The substrate 10 is composed of an SOI substrate having a structure in which a buried oxide film 13 serving as a sacrificial layer is sandwiched between a support substrate 11 and a semiconductor layer 12. SOI stands for Silicon on insulator. Such a sensor structure is configured by etching the semiconductor layer 12 side into the pattern of the sensor structure, and then partially removing the buried oxide film so that a part of the sensor structure is released. .

The semiconductor layer 12 is patterned on the fixed member 20, the movable part 30 and the beam part 40. The fixing member 20 has a buried oxide film remaining at least on a part of the back surface thereof, and is not released from the support substrate 11, but partially on the one surface 11 a of the support substrate 11 through the buried oxide film. It is in a fixed state. The movable portion 30 and the beam portion 40 constitute a vibrator in the vibration type angular velocity sensor. The movable portion 30 is in a state where the buried oxide film on the back surface side is removed and released from the support substrate 11. The beam portion 40 supports the movable portion 30 and displaces the movable portion 30 in the x-axis direction and the y-axis direction in order to detect angular velocity. The drive unit 50 and the detection unit 60 are connected to the fixed portion fixed to the support substrate 11 via the buried oxide film, and are connected to the fixed portion, and are released from the support substrate 11 after the buried oxide film is removed. An electrode. The drive unit 50 is used to drive the movable unit 30. The detection unit 60 detects an external force when an external force is applied in a state where the movable unit 30 is driven by the drive unit 50. Hereinafter, the fixed member 20, the movable unit 30, the beam unit 40, the drive unit 50, and the detection unit 60 will be described in order.

As shown in FIG. 1, two fixed members 20 are provided as a pair, are arranged along the x-axis direction, are opposed to each other with the movable portion 30 interposed therebetween, and are supported by the movable portion 30. It is connected via a member 43. The fixing member 20 has, for example, a rectangular shape in a top view, and includes a fixing portion 21 and a floating portion 22.

As shown in FIG. 2, the fixing portion 21 is connected to the support substrate 11 via the buried oxide film 13 and is fixed to the support substrate 11. As shown in FIG. 1, a part of the plurality of support members 43 that support the movable portion 30 is connected to the fixed portion 21.

The floating part 22 blocks the propagation of the distortion to the movable part 30 when the torsional distortion occurs in the support substrate 11. In this embodiment, as shown in FIG. Thus, it extends along the direction parallel to the x-axis direction from both ends sandwiching the fixed portion 21. In the present embodiment, the floating portion 22 is, for example, removed from the connection with the support substrate 11 by removing the buried oxide film 13 by etching and, as shown in FIG. Is in a floating state. That is, the floating portion 22 is in a state of floating from the support substrate 11 in the normal direction to the one surface 11 a of the support substrate 11. Note that the suppression of torsional distortion propagation to the movable part 30 by the floating part 22 will be described later.

As shown in FIG. 1, the remaining support member 43 is connected to the floating portion 22, and a plurality of through holes 22 a penetrating in the thickness direction of the floating portion 22 are formed. The through-hole 22a efficiently removes the buried oxide film 13 that exists immediately below the portion of the fixing member 20 that becomes the floating portion 22 when the buried oxide film 13 that becomes the sacrificial layer is removed by etching. For example, it is formed by dry etching or the like. The number, shape, and arrangement of the through holes 22a are arbitrary.

The movable portion 30 is a portion that is displaced in response to the application of the angular velocity, and includes an outer drive weight 31, 32, an inner drive weight 33, 34, and detection weights 35, 36 as shown in FIG. It is said that. The movable portion 30 has a layout in which an outer drive weight 31, an inner drive weight 33 including a detection weight 35, an inner drive weight 34 including a detection weight 36, and an outer drive weight 32 are arranged in this order along the x-axis direction. Yes. In other words, the movable portion 30 has two inner drive weights 33 and 34 provided with detection weights 35 and 36 inside, and is arranged on both outer sides so as to sandwich the two inner drive weights 33 and 34. Further, the outer drive weights 31 and 32 are arranged one by one.

The outer drive weights 31 and 32 are extended in the y-axis direction. The outer driving weight 31 is disposed to face the inner driving weight 33. The outer drive weight 32 is disposed to face the inner drive weight 34. These outer drive weights 31 and 32 function as mass parts, are thicker than various beams included in the beam part 40, and are the y-axis that is the vibration direction when drive vibration is performed by the drive beam 42 and the drive part 50 described later. It is possible to move in the direction. As shown in FIG. 1, the outer drive weights 31 and 32 have comb-shaped drive movable electrodes 31a and 32a formed on the inner drive weights 33 and 34 side of the sides along the y-axis direction. .

The driving movable electrode 31a is arranged at a distance from the comb-shaped driving fixed electrode 52 formed on the side of the driving unit 50 described later on the side of the outer driving weight 31. As shown in FIG. 1, the portion of the driving movable electrode 31 a that extends along the y-axis direction alternates with the portion of the driving fixed electrode 52 that extends along the y-axis direction. When a voltage is applied to the driving fixed electrode 52, an electrostatic force is generated. The outer drive weight 31 vibrates along the y-axis direction by the action of the electrostatic force.

As shown in FIG. 1, the driving movable electrode 32a is arranged at a distance from the comb-shaped driving fixed electrode 54 formed on the side of the driving unit 50 on the outer driving weight 32 side. Since the arrangement relationship between the drive movable electrode 32a and the drive fixed electrode 54 is the same as the arrangement relationship between the drive movable electrode 31a and the drive fixed electrode 52, the description thereof is omitted. When a voltage is applied to the driving fixed electrode 54, the outer driving weight 32 vibrates along the y-axis direction.

As shown in FIG. 1, the inner drive weights 33 and 34 have a rectangular frame shape when viewed from above, and surround one of the detection weights 35 and 36. These inner drive weights 33 and 34 function as mass parts, are thicker than the various beams included in the beam part 40, and are movable in the y-axis direction. As shown in FIG. 1, the inner drive weights 33 and 34 configured in a quadrangular shape are arranged such that two opposite sides are parallel to the x-axis direction and the y-axis direction, respectively. The inner driving weights 33 and 34 are arranged such that one of the two sides parallel to the y-axis direction is opposed to the outer driving weights 31 and 32 and the other side is arranged to face the other of the inner driving weights 33 and 34. Yes. As shown in FIG. 1, the inner drive weights 33 and 34 are formed with comb-like drive movable electrodes 33a and 34a on the sides on the outer drive weights 31 and 32 side among the sides parallel to the y-axis direction. ing.

The driving movable electrode 33a is arranged at a distance from the driving fixed electrode 52 formed on the side of the driving unit 50 on the inner driving weight 33 side. As shown in FIG. 1, the portion of the driving movable electrode 33 a that extends along the y-axis direction alternates with the portion of the driving fixed electrode 52 that extends along the y-axis direction. When a voltage is applied to the driving fixed electrode 52, an electrostatic force is generated. The inner drive weight 33 vibrates along the y-axis direction by the action of the electrostatic force.

The driving movable electrode 34a is arranged at a distance from the driving fixed electrode 54 formed on the side of the driving unit 50 on the inner driving weight 34 side. Since the arrangement relationship between the driving movable electrode 32a and the driving fixed electrode 54 is the same as the arrangement relationship between the driving movable electrode 33a and the driving fixed electrode 52, the description thereof is omitted. When a voltage is applied to the driving fixed electrode 54, the inner driving weight 34 vibrates along the y-axis direction.

As shown in FIG. 1, the detection weights 35 and 36 have, for example, a quadrangular frame shape when viewed from the top, and the inside of the inner drive weights 33 and 34 through a detection beam 41 described later in the beam portion 40. It is supported on the wall. Like the driving weights 31 to 34, the detection weights 35 and 36 function as mass parts and are moved in the y-axis direction together with the inner driving weights 33 and 34 by driving vibration. However, when the angular velocity is applied, the detection weights 35 and 36 are moved in the x-axis direction. It is done.

For example, as shown in FIG. 1, the detection weights 35 and 36 have detection movable electrodes 35a and 36a formed on sides of the inner wall surface parallel to the x-axis direction. The detection movable electrodes 35a and 36a extend along the y-axis direction and are arranged at a distance from the detection fixed electrodes 62 and 64 described later in the detection unit 60.

The detection movable electrode 35a is arranged so as to alternate with the detection fixed electrode 62 extending along the y-axis direction on the side along the x-axis direction of the outer wall surface of the detection base 61. The detection movable electrode 36a is alternately arranged with the detection fixed electrode 64 extending along the y-axis direction on the side along the x-axis direction of the outer wall surface of the detection base 63.

The beam portion 40 is configured to include a detection beam 41, a drive beam 42, and a support member 43 shown in FIG.

As shown in FIG. 1, the detection beam 41 is a linear beam extending along the y-axis direction, which is the vibration direction of the drive weights 31 to 34, and x of the inner wall surfaces of the inner drive weights 33 and 34. A side parallel to the axial direction is connected to a side parallel to the x-axis direction of the outer wall surfaces of the detection weights 35 and 36. The detection beam 41 has an arrangement in which the y-axis direction, which is a vibration direction at the time of driving vibration, is a longitudinal direction, and the detection beam 41 is a direction that intersects the vibration direction when an angular velocity is applied. Can be displaced in the axial direction. Due to the displacement of the detection beam 41 in the x-axis direction, the detection weights 35 and 36 can be moved in the x-axis direction.

As shown in FIG. 1, the drive beam 42 connects the outer drive weights 31 and 32 and the inner drive weights 33 and 34, and the outer drive weights 31 and 32 and the inner drive weights 33 and 34 in the y-axis direction. It is possible to move. Specifically, the drive beam 42 connects the drive weights 31 to 34 arranged in order of one outer drive weight 31, one inner drive weight 33, the other inner drive weight 34, and the other outer drive weight 32. doing. In other words, the movable portion 30 includes a ladder in which driving weights 31 to 34 are arranged side by side along the x-axis direction, and these are sandwiched between the pair of driving beams 42 at both ends in the y-axis direction and connected by the driving beams 42. It is structured.

More specifically, the drive beam 42 is a straight beam having a predetermined width in the y-axis direction. As shown in FIG. 1, one drive beam 42 is disposed on each side of the outer drive weights 31 and 32 and the inner drive weights 33 and 34 in the y-axis direction. 32 and inner drive weights 33 and 34. The driving beam 42 may be directly connected to the outer driving weights 31 and 32 and the inner driving weights 33 and 34. For example, in this embodiment, the driving beam 42 and the inner driving weights 33 and 34 are connected to the connecting portion 42a. Connected through.

As shown in FIG. 1, a plurality of support members 43 are arranged between the fixed member 20 and the movable portion 30 to support the movable portion 30. Specifically, in the present embodiment, as shown in FIG. 1, six support members 43 are arranged, two of which are connected to the fixing portion 21 and the remaining four are connected to the floating portion 22. . In other words, the movable part 30 is mainly supported by the floating part 22 via the support member 43.

As shown in FIG. 1, the support member 43 is configured to include a rotating beam 43a, a supporting beam 43b, and a connecting portion 43c. The rotating beam 43a is a linear beam having a predetermined width in the y-axis direction. The supporting beam 43b is connected to both ends of the rotating beam 43a, and the connecting portion 43c is connected to the center position opposite to the supporting beam 43b. Has been. The rotating beam 43a bends in an S shape around the connecting portion 43c when the sensor is driven. The support beam 43b is configured such that both ends of the rotating beam 43a are connected to predetermined portions of the fixing member 20, and is a linear member in the present embodiment. The support beam 43b also serves to allow the weights 31 to 36 to move in the x-axis direction when an impact or the like is applied. The connecting portion 43 c serves to connect the support member 43 to the drive beam 42.

The drive unit 50 is for driving and vibrating a sensor structure such as the movable unit 30 and the beam unit 40. For example, as shown in FIG. 1, between the outer drive weight 31 and the inner drive weight 33 and outside The drive weight 32 and the inner drive weight 34 are respectively disposed.

Specifically, a driving unit 50 including a base 51 and a driving fixed electrode 52 is disposed between the outer driving weight 31 and the inner driving weight 33. Between the outer driving weight 32 and the inner driving weight 34, a driving unit 50 including a base 53 and a driving fixed electrode 54 is disposed.

In the present embodiment, for example, as shown in FIG. 1, the base portions 51 and 53 are formed in a rectangular plate shape that extends along the y-axis direction in a top view and has the y-axis direction as a longitudinal direction. On the two sides in the longitudinal direction of the base portions 51 and 53, fixed driving electrodes 52 and 54 are provided.

The driving fixed electrodes 52 and 54 are comb-like like the driving movable electrodes 31a to 34a, and an electrostatic force is generated between the driving movable electrodes 31a to 34a by applying a voltage, Used to drive the movable part 30. For example, the driving fixed electrodes 52 and 54 are connected to electrode pads (not shown) formed on the bases 51 and 53 of the driving unit 50 and are configured to be applied with a voltage from the outside. The driving fixed electrode 52 faces the driving movable electrodes 31a and 33a. The driving fixed electrode 54 faces the driving movable electrodes 32a and 34a.

The detection unit 60 is a part that outputs an electrical signal corresponding to the displacement of the detection beam 41 due to the application of the angular velocity, and is arranged inside the detection weights 35 and 36, respectively, as shown in FIG. Specifically, the detection unit 60 including the detection base 61 and the detection fixed electrode 62 is disposed inside the detection weight 35, and the detection unit 60 including the detection base 63 and the detection fixed electrode 64 is the detection weight. 36 is disposed inside.

The detection bases 61 and 63 have a buried oxide film (not shown) left behind and are fixed to the support substrate 11.

For example, as shown in FIG. 1, the detection fixed electrodes 62 and 64 are formed on the sides along the x-axis direction of the outer wall surfaces of the detection bases 61 and 63, and extend along the y-axis direction. Has been. The fixed electrodes 62 and 64 for detection are released from the support substrate 11 after the buried oxide film (not shown) on the back side is removed.

With the above structure, a vibration type angular velocity sensor having a pair of angular velocity detecting structures each including two outer driving weights 31 and 32, two inner driving weights 33 and 34, and two detection weights 35 and 36 is configured. ing.

Next, the basic operation of the vibration type angular velocity sensor will be described with reference to FIG.

When an AC voltage added to the DC voltage is applied to the driving fixed electrodes 52 and 54 to generate a potential difference between the outer driving weights 31 and 32 and the inner driving weights 33 and 34, the potential difference is based on the potential difference. An electrostatic force is generated along the y-axis direction. Based on this electrostatic force, for example, as shown in FIG. 3, each of the drive weights 31 to 34 is vibrated in the y-axis direction. At this time, the vibration in the y-axis direction of each of the drive weights 31 to 34 is monitored while changing the frequency of the AC voltage, and the frequency of the AC voltage is adjusted to be a predetermined drive resonance frequency. For example, a monitoring electrode is provided so as to face the outer driving weights 31 and 32, and the displacement of the outer driving weights 31 and 32 is detected based on a change in capacitance formed therebetween.

At this time, when the capacitance change is large, the drive resonance frequency fd is detected by circuit processing. The drive resonance frequency fd is determined by the structure of the vibrator such as the width of the drive beam 42.

As shown in FIG. 3, the outer driving weight 31 and the inner driving weight 33 are arranged by the arrangement of the driving fixed electrode 52, the driving movable electrode 31 a of the outer driving weight 31, and the driving movable electrode 33 a of the inner driving weight 33. Are oscillated in mutually opposite phases in the y-axis direction, that is, in opposite directions. Further, due to the arrangement of the driving fixed electrode 54, the driving movable electrode 32a of the outer driving weight 32 and the driving movable electrode 34a of the inner driving weight 34, as shown in FIG. , They are vibrated in opposite phases in the y-axis direction. Furthermore, the two inner drive weights 33 and 34 are vibrated in opposite phases in the y-axis direction. Thereby, the vibration type angular velocity sensor is driven in the drive mode shape.

At this time, the movable unit 30 allows the weights 31 to 34 to move in the y-axis direction by the driving beam 42 undulating in an S shape, but connects the rotating beam 43a and the driving beam 42. The connecting portion 43c is a structure having a node of amplitude, that is, a fixed point and hardly displaced.

When the angular velocity around the z-axis is applied to the vibration-type angular velocity sensor during the basic operation as shown in FIG. 3, the detection weights 35 and 36 cause the x-axis as shown in FIG. Displace in the direction. Due to this displacement, the capacitance value of the capacitor constituted by the detection movable electrode 35 a of the detection weight 35 and the detection fixed electrode 62 of the detection base 61, and the detection movable electrode 36 a and the detection base 63 of the detection weight 36 are detected. The capacitance value of the capacitor composed of the detection fixed electrode 64 changes.

Therefore, the angular velocity can be detected by reading the change in the capacitance value of the capacitor based on the signal extraction from the bonding pads (not shown) of the detection bases 61 and 63. For example, in the case of the configuration of the present embodiment, it is possible to read the change in the capacitance value of the capacitor by differentially amplifying signals extracted from the two angular velocity detection structures, so that the angular velocity is detected more accurately. It becomes possible. In this way, the applied angular velocity can be detected by the vibration type angular velocity sensor of the present embodiment.

By the operation as described above, the vibration type angular velocity sensor of the present embodiment can detect the applied angular velocity.

Next, the effect of the fixing member 20 including the floating portion 22 will be described with reference to FIGS. 5A and 5B. 5A and 5B, in order to make it easier to understand the displacement of the fixing member 20 when the torsional distortion occurs in the support substrate 11, a part of the area in the vicinity of the fixing member 20 is shown enlarged, and other areas are also shown. Omitted. Further, in FIGS. 5A and 5B, the state before twist distortion is indicated by broken lines.

Here, the conventional vibration type angular velocity sensor has a structure in which almost all of the fixed member 70 that supports the movable portion 30 is connected to the support substrate 11 through the buried oxide film 13. In such a structure, when the torsional distortion occurs in the support substrate 11, the fixing member 70 is dragged by the torsional distortion of the support substrate 11 and twisted similarly to the support substrate 11 as shown in FIG. 5A. It becomes the state. Along with this, this twist is also propagated to the movable portion 30 connected to the fixed member 70 via the support member 43, and the movable portion 30 is also in a state in which the twist is generated. As a result, the torsional distortion propagates to the detection unit 60 of the movable unit 30, thereby causing a deviation in displacement when an angular velocity is applied, causing a characteristic error.

On the other hand, in this embodiment, a part of the fixed member 20 is a floating portion 22 that is released from the connection with the support substrate 11 by removing the buried oxide film 13, and the movable portion 30 is It is mainly connected to the floating portion 22 through a support member 43. In the present embodiment, even if the support substrate 11 is twisted and strained, the floating portion 22 is in a state of floating from the support substrate 11 as shown in FIG. The torsional distortion of the substrate 11 is difficult to propagate. Similarly, the movable part 30 supported mainly by the floating part 22 is also less likely to transmit the torsional distortion, so that the occurrence of characteristic errors due to the torsional distortion of the support substrate 11 is suppressed.

Further, as shown in FIG. 1, the fixing portion 21 is a straight line perpendicular to one side constituting the outline of the support substrate 11 and passes through the central portion of the one side (hereinafter referred to as “central axis” for convenience). It is preferably arranged along the top). In particular, when the support member 43 is connected not only to the floating portion 22 but also to the fixed portion 21, the fixed portion 21 is preferably disposed on the central axis of the support substrate 11.

This is because when the support substrate 11 is distorted by twisting, the fixing portion 21 is disposed on the portion of the support substrate 11 on the central axis that is hard to be twisted, so that the twisting distortion of the fixing portion 21 can also be reduced. This is because torsional distortion propagation to the movable portion 30 can be further suppressed.

In other words, the floating portion 22 is disposed on a region of the support substrate 11 where the twisting distortion is large, for example, on a region near the four corners when the support substrate 11 has a rectangular plate shape. Is preferred. For example, when the outline of the movable part 30 is substantially rectangular, at least four support members 43 are connected to the movable part 30, and one end of the support member 43 is near each of the four corners of the outline of the movable part 30. In addition, the other end of the support member 43 is connected to the floating portion 22. In other words, the vibration type angular velocity sensor of the present embodiment has an arrangement in which the four support members 43 connected to the floating part 22 are respectively connected to the vicinity of the four corners of the outline of the movable part 30, that is, a diagonal arrangement. Structure.

In the present embodiment, in the pair of fixed members 20 that are disposed opposite to each other with the movable portion 30 interposed therebetween, the fixed portion 21 is disposed on a central axis that is orthogonal to the fixed member 20. And the floating part 22 is arrange | positioned at each both ends of the fixing | fixed part 21, and it is set as the structure where the total four floating parts 22 were diagonally arranged.

According to the present embodiment, even when a twist distortion occurs in the support substrate 11, the floating portion 22 is arranged in a portion of the support substrate 11 where the influence of the twist is large, and the support member is provided in the floating portion 22. The physical quantity sensor has a structure in which the movable unit 30 is supported via 43. In addition, by using a so-called ladder structure, the physical quantity sensor is provided with characteristics of impact resistance and energy leakage prevention while suppressing characteristic errors due to torsional distortion of the support substrate 11.

(Second Embodiment)
An example in which the physical quantity sensor according to the second embodiment is applied as a vibration type angular velocity sensor will be described with reference to FIGS.

The physical quantity sensor of the first embodiment is an electrostatic vibration-type angular velocity sensor, whereas the physical quantity sensor of the present embodiment is a piezoelectric vibration-type angular velocity sensor. Is different. In the present embodiment, mainly the differences, in particular, the differences and operations of the weights 31 to 36, the detection beam 41, the drive unit 50, and the detection unit 60 from the first embodiment will be briefly described. .

In the present embodiment, the driving weights 31 to 34 are driven and vibrated using a driving piezoelectric film 55 described later, and thus are not provided with the driving movable electrodes 31a to 34a.

In this embodiment, for example, as shown in FIG. 6, the detection weights 35 and 36 have a quadrangular shape in a top view, and the inner drive weights 33, 34 is supported by the inner wall surface. Like the driving weights 31 to 34, the detection weights 35 and 36 function as mass parts and are moved in the y-axis direction together with the inner driving weights 33 and 34 by driving vibration. However, when the angular velocity is applied, the detection weights 35 and 36 are moved in the x-axis direction. It is done.

The detection weights 35 and 36 are not provided with the detection movable electrodes 35a and 36a in the present embodiment because the detection unit 60 described later is a piezoelectric type and the detection unit 60 is formed on the detection beam 41. It is configured.

As shown in FIG. 6, the detection beam 41 is parallel to the side parallel to the y-axis direction on the inner wall surfaces of the inner drive weights 33 and 34 and parallel to the y-axis direction on the outer wall surfaces of the detection weights 35 and 36. Are connected to each other. In the present embodiment, the detection beam 41 extends linearly along the y-axis direction, which is the vibration direction of the drive weights 31 to 34, and is shifted in the x-axis direction to detect the detection weight 35 at both ends in the vibration direction. , 36 to support the beam. The detection beams 41 are arranged on both sides of the detection weights 35 and 36 in the x-axis direction. One is the first detection beam 41a and the other is the second detection beam 41b, and the detection weights 35 and 36 are in the x-axis direction. The structure is supported on both sides. The first detection beam 41a and the second detection beam 41b are both connected to the inner walls of the inner drive weights 33 and 34 at the connection portion 41c with the central portion in the y-axis direction as the connection portion 41c. Then, both ends of the detection weights 35 and 36 in the y-axis direction are supported by the detection beams 41 on both sides centering on the connecting portion 41c.

As shown in FIG. 6, the first detection beam 41a and the second detection beam 41b may have different spring constants by changing the dimensions in the x-axis direction, and the dimensions in the x-axis direction may be different. The spring constants may be the same in the same state.

In this embodiment, the drive unit 50 is configured by a drive piezoelectric film 55, a drive wiring 56, and the like provided at both ends of each drive beam 42.

The driving piezoelectric film 55 is composed of a PZT thin film or the like, and generates a force for driving and vibrating the sensor structure when a driving voltage is applied through the driving wiring 56. PZT is an abbreviation for lead zirconate titanate. Two drive piezoelectric films 55 are provided at each end of each drive beam 42, and the one located on the outer edge side of the sensor structure is located on the inner side of the outer piezoelectric film 55a and the outer piezoelectric film 55a. The inner piezoelectric film 55b is provided. The outer piezoelectric film 55a and the inner piezoelectric film 55b extend in the x-axis direction, and are formed side by side in parallel at each arrangement location.

The driving wiring 56 is a wiring for applying a driving voltage to the outer piezoelectric film 55a and the inner piezoelectric film 55b. Although only a part of the drive wiring 56 is shown in the drawing, the drive wiring 56 is actually extended from the drive beam 42 to the fixed member 20 through the support member 43. The drive wiring 56 is electrically connected to the outside by wire bonding or the like through a pad (not shown) formed on the fixing member 20. Thereby, a drive voltage can be applied to the outer piezoelectric film 55a and the inner piezoelectric film 55b through the drive wiring 56.

In this embodiment, the detection unit 60 is formed on the first detection beam 41a of the detection beam 41, and includes a detection piezoelectric film 65a to 65d, a dummy piezoelectric film 66a to 66d, and a detection wiring 67. Yes.

The detection piezoelectric films 65a to 65d are formed of a PZT thin film or the like, and are formed at positions where tensile stress is applied when the first detection beam 41a is displaced by application of angular velocity in the first detection beam 41a. Specifically, on both ends of the first detection beam 41a, the detection weights 35 and 36 in the x-axis direction, and on the connecting portion 41c side, the detection piezoelectric films 65a to 65a are disposed on the side away from the detection weights 35 and 36 in the x-axis direction. 65d is arranged.

The dummy piezoelectric films 66a to 66d are composed of a PZT thin film or the like, and are arranged symmetrically with the detection piezoelectric films 65a to 65d in order to maintain the symmetry of the detection beam 41. That is, the dummy piezoelectric films 66a to 66d are formed in positions where compressive stress is applied when the first detection beam 41a is displaced by application of angular velocity in the first detection beam 41a. Specifically, the dummy piezoelectric films 66a to 66d are formed on the opposite sides of the first detection beam 41a on the side away from the detection weights 35 and 36 in the x-axis direction, and on the connecting portion 41c side in the x-axis direction. It is arranged on the 36 side.

The detection piezoelectric films 65a to 65d and the dummy piezoelectric films 66a to 66d are both extended in the y-axis direction, which is the direction of the driving vibration of the detection weights 35 and 36, and are formed in parallel at each arrangement location. . Here, the example in which the detection piezoelectric films 65a to 65d are formed at the site where the tensile stress at which the displacement becomes the largest is described, but the detection piezoelectric films 65a to 65d may be formed at the site where the compressive stress is generated. You may form in both the site | part which generate | occur | produces and the site | part which a compressive stress generate | occur | produces.

For example, the detection piezoelectric films 65a to 65d are formed in a portion where compressive stress is generated in the first detection beam 41a on the left side in the x-axis direction in FIG. 6 when the angular velocity is applied, and the first detection beam 41a on the right side in the x-axis direction in FIG. Then, it may be formed at a site where tensile stress occurs or vice versa.

Also, the dummy piezoelectric films 66a to 66d are not essential, and at least the detection piezoelectric films 65a to 65d may be formed in the detection unit 60.

The detection wiring 67 is connected to the detection piezoelectric films 65a to 65d and takes out electrical outputs of the detection piezoelectric films 65a to 65d accompanying the displacement of the detection beam 41. Although only a part of the detection wiring 67 is omitted in the drawing, the detection wiring 67 is actually extended from the inner drive weights 33 and 34 and the drive beam 42 to the fixed member 20 through the support member 43. The detection wiring 67 is electrically connected to the outside by wire bonding or the like through a pad (not shown) formed on the fixing member 20. As a result, changes in the electrical output of the detection piezoelectric films 65a to 65d can be transmitted to the outside through the detection wiring 67.

Next, the operation of the piezoelectric vibration type angular velocity sensor configured as described above will be described with reference to FIGS.

First, the basic operation of the vibration type angular velocity sensor of the present embodiment will be described with reference to FIG. A desired drive voltage is applied to the drive units 50 arranged at both ends of each drive beam 42, and the drive weights 31 to 34 are vibrated in the y-axis direction based on the drive voltage.

Specifically, with respect to the drive unit 50 provided at the left end portion of the drive beam 42 on the upper side of the paper surface, tensile stress is generated in the outer piezoelectric film 55a, and compressive stress is generated in the inner piezoelectric film 55b. To be able to. On the other hand, for the drive unit 50 provided at the right end of the drive beam 42 on the upper side of the paper surface, compressive stress is generated in the outer piezoelectric film 55a, and tensile stress is generated in the inner piezoelectric film 55b. To. This can be realized by applying voltages having opposite phases to the outer piezoelectric films 55a or the inner piezoelectric films 55b of the driving unit 50 disposed on the left and right sides of the driving beam 42 on the upper side of the drawing.

On the other hand, with respect to the drive unit 50 provided at the left end portion of the drive beam 42 on the lower side of the page, compressive stress is generated by the outer piezoelectric film 55a, and tensile stress is generated by the inner piezoelectric film 55b. To do. On the other hand, for the drive unit 50 provided at the right end of the drive beam 42 on the lower side of the page, tensile stress is generated in the outer piezoelectric film 55a, and compressive stress is generated in the inner piezoelectric film 55b. To. This can also be realized by applying voltages having opposite phases to the outer piezoelectric films 55a or the inner piezoelectric films 55b of the driving unit 50 disposed on the left and right sides of the driving beam 42 on the lower side of the drawing.

Next, each of the outer piezoelectric films 55a so that the stress generated in the outer piezoelectric film 55a and the inner piezoelectric film 55b of each drive unit is switched to a compressive stress for the tensile stress and switched to the tensile stress for the compressive stress. And the voltage applied to the inner piezoelectric film 55b is controlled. Thereafter, these operations are repeated at a predetermined drive frequency.

Accordingly, as shown in FIG. 7, in the y-axis direction, the outer drive weight 31 and the inner drive weight 33 are in opposite phases with each other, the outer drive weight 32 and the inner drive weight 34 are in opposite phases with each other, and the two inner drive weights 33 and 34 are vibrated in opposite phases, and the two outer drive weights 31 and 32 are vibrated in opposite phases. As a result, the vibration type angular velocity sensor is driven in the same drive mode shape as in the first embodiment.

At this time, for the same reason as the vibration type angular velocity sensor of the first embodiment, the connecting portion 43c becomes a node of amplitude, that is, a fixed point, hardly displaces, and when an impact or the like is applied, The output change due to is reduced, and impact resistance is obtained.

Next, a state when an angular velocity is applied to the vibration type angular velocity sensor will be described with reference to FIG. When the angular velocity around the z-axis is applied to the vibration type angular velocity sensor during the basic operation as shown in FIG. 7, the Coriolis force causes the detection weights 35 and 36 to be moved to the y-axis as shown in FIG. It is displaced in the intersecting direction, here the x-axis direction. Specifically, since the detection weights 35 and 36 and the inner drive weights 33 and 34 are connected via the detection beam 41, the detection weights 35 and 36 are displaced based on the elastic deformation of the detection beam 41. Along with the elastic deformation of the detection beam 41, tensile stress is applied to the detection piezoelectric films 65a to 65d provided in the first detection beam 41a. Therefore, the output voltage of the detection piezoelectric films 65a to 65d changes according to the applied tensile stress, and this is output to the outside through the detection wiring 67. By reading this output voltage, the applied angular velocity can be detected.

In particular, since the detection piezoelectric films 65a to 65d are arranged in the vicinity of the connection portion of the detection beam 41 with the detection weights 35 and 36 and the connection portion with the inner drive weights 33 and 34, as shown in FIG. In addition, the largest tensile stress is applied to the detection piezoelectric films 65a to 65d. For this reason, it is possible to further increase the output voltage of the detection piezoelectric films 65a to 65d.

By the operation as described above, the vibration type angular velocity sensor of the present embodiment can detect the applied angular velocity.

Even in the case where the movable portion 30 has a structure adapted to the piezoelectric method as described above as in the present embodiment, the movable portion 30 is supported by the floating portion 22 of the fixed member 20. The torsional distortion of the substrate 11 does not propagate to the movable part 30. Therefore, also in this embodiment, the same effect as the first embodiment can be obtained.

(Third embodiment)
An example in which the physical quantity sensor of the third embodiment is applied as a vibration type angular velocity sensor will be described with reference to FIG. In FIG. 10, the boundary between the fixed portion 21 and the floating portion 22 of the fixed member 20 is indicated by a broken line for easy understanding of the configuration.

The physical quantity sensor of the first embodiment has a ladder structure in which a plurality of drive weights 31 to 34 are sandwiched between two drive beams 42 and connected at both ends in the y-axis direction, so-called ladder structure. . On the other hand, the vibration type angular velocity sensor of the present embodiment is different from the first embodiment in that it is not a ladder structure. In the present embodiment, this difference will be mainly described.

The fixing member 20, the drive weights 33 and 34, the detection weights 35 and 36, the drive beam 42, the drive unit 50, and the detection unit 60 constituting the present embodiment are the same as those in the first embodiment or the second embodiment. Since the configuration is the same, the spring structure will be mainly described as shown in FIG.

As shown in FIG. 10, the vibration-type angular velocity sensor according to the present embodiment includes a pair of fixed members 20, a movable portion 30 sandwiched between the pair of fixed members 20, and a connection between the fixed member 20 and the movable portion 30. The drive beam 42 is provided.

As shown in FIG. 10, the fixing member 20 is arranged on both sides with the movable portion 30 interposed therebetween, and one driving beam 42 is connected to each floating portion 22 arranged on both sides with the fixing portion 21 in between. ing.

For example, as shown in FIG. 10, the movable unit 30 includes a pair of drive weights 33 and 34, detection weights 35 and 36 surrounded by the drive weights 33 and 34, drive weights 33 and 34, and detection weights 35 and 36. And a detection beam 41 connecting the detection weights 35 and 36 at both ends.

For example, as shown in FIG. 10, the driving weight 33 has a rectangular frame shape surrounding the detection weight 35 and supports the detection weight 35 via two detection beams 41. For example, as shown in FIG. 10, the driving weight 34 has a rectangular frame shape surrounding the detection weight 36 and supports the detection weight 35 via two detection beams 41. The drive weights 33 and 34 are arranged facing each other in the left-right direction on the paper surface in FIG. 10, are connected by a drive coupling beam 45, are provided with a drive unit 50 (not shown), and the extending direction of the floating unit 22 Drive vibration along the direction parallel to the. The drive coupled beam 45 is a beam that couples the two drive weights 33 and 34, and is configured to be deformable along with the displacement of the drive weights 33 and 34.

The detection beam 41 is provided with a detection unit 60 (not shown), and when the driving weights 33 and 34 are driven to vibrate, when the angular velocity is applied, the detection unit 60 outputs an electrical output corresponding to the displacement. It is set as the structure.

The above is the basic structure of the vibration type angular velocity sensor of the present embodiment, and the drive weights 33 and 34 are connected by the single drive coupling beam 45 at the center position in the direction perpendicular to the left and right direction in FIG. The structure is different from the so-called ladder structure. In the present embodiment, the movable part 30 may be disposed between the pair of fixed members 20 and may be configured to be connected to the floating part 22 via the driving beam 42. The structure may be changed as appropriate.

According to the present embodiment, since the movable part 30 is supported by the floating part 22 via the drive beam 42, even if the support substrate 11 is distorted by twisting, the movable part 30 has its structure. Propagation of torsional distortion is suppressed. Therefore, similarly to the first embodiment, the vibration type angular velocity sensor with less characteristic error due to torsional distortion of the support substrate 11 is obtained compared to the conventional one.

(Other embodiments)
In addition, the vibration-type angular velocity sensor shown in each embodiment described above is an example of the physical quantity sensor of the present disclosure, and is not limited to each embodiment described above, and can be changed as appropriate.

(1) For example, in each of the above embodiments, the example in which the fixing member 20 has a substantially rectangular plate shape has been described. However, the fixing member 20 is not limited thereto, and the fixing member 20 has a substantially T-shaped or trapezoidal shape, Other shapes may be used.

Specifically, as shown in FIG. 11, the floating portion 22 has a width in the intersecting direction, with the direction extending from the fixed portion 21 as the extending direction and the direction intersecting the extending direction as the intersecting direction. Is preferably set to a predetermined value or more. Further, when the width of the floating portion 22 in the crossing direction is increased, the width in the extending direction of the portion on the movable portion 30 side (hereinafter referred to as “extended width”) is the extension of the portion on the opposite side of the movable portion 30. The shape is preferably larger than the installation width.

This is to increase the rigidity of the tip portion in the extending direction of the floating portion 22, that is, the portion to which the support member 43 is connected to make it difficult to bend, and to reduce the strength reduction due to the floating state. . As a result, a decrease in resonance frequency due to the floating portion 22 can be suppressed, and a characteristic error can be reduced.

Specifically, as shown in FIG. 11, the floating portion 22 is constrained to a region having a small extension width, that is, the fixed portion 21, as shown in FIG. 11, rather than the rectangular plate shape. More areas that are difficult to bend. The floating portion 22 has a normal direction relative to the one surface 11a as the one surface normal direction, and the rigidity in the one surface normal direction of the tip portion is relatively large. That is, the floating portion 22 is in a state in which the tip portion is difficult to bend by increasing rigidity in the one-surface normal direction, that is, in a state in which unnecessary vibration is suppressed in the one-surface normal direction.

Therefore, not only the torsional distortion of the support substrate 11 is suppressed from propagating to the movable part 30, but also the unnecessary vibration due to the floating part 22 is suppressed from propagating. Therefore, unintentional distortion and unnecessary vibration are suppressed from being generated in the movable part 30, and the physical quantity sensor is further suppressed in characteristic error as compared with the above embodiments.

(2) In the first embodiment, the example in which the through hole 22a is formed in the floating portion 22 has been described, but the through hole 22a may not be formed. For example, when a physical quantity sensor is manufactured by bonding the support substrate 11 and the semiconductor layer 12, as shown in FIG. 12, the recess 14 is formed in advance on the one surface 11 a side of the support substrate 11, thereby floating. The part 22 can be in a floating state. As described above, when the floating portion 22 is floated by a method other than the etching of the buried oxide film 13, the floating portion 22 has a structure in which the through hole 22 a is not formed, and further increases the rigidity and lowers the resonance frequency. It is expected to exert a suppression effect.

(3) In the first embodiment and the second embodiment, the example in which the support member 43 is connected to the fixed portion 21 has been described. However, the support member 43 is connected to at least the floating portion 22. It is sufficient that it is not connected to the fixing portion 21. Specifically, as shown in FIG. 13, the floating portion 22 extends between the fixed portion 21 and the movable portion 30, and a support member 43 is connected to the extended floating portion 22. May be. In the above structure, the same effect as in the first and second embodiments can be obtained.

(4) In each of the above embodiments, the example in which the physical quantity sensor is applied as the vibration type angular velocity sensor has been described. However, the present invention is not limited to this, and the present invention can be applied to, for example, an acceleration sensor.

Claims (3)

When a physical quantity is applied, the physical quantity sensor outputs a signal corresponding to the physical quantity,
A support substrate (11) having one surface (11a);
A fixing member (20) partially fixed to the support substrate on the one surface side;
A movable part (30) having a drive weight (33, 34), a detection weight (35, 36), and a detection part (60);
A drive unit (50) for vibrating the drive weight,
When the physical quantity is applied when the driving weight is driven to vibrate, the detection unit generates an electrical output based on the movement of the detection weight accompanying the application of the physical quantity,
The fixing member includes a fixing portion (21) connected to the support substrate, and a floating portion (22) extending from the fixing portion on both sides of the fixing portion.
The floating portion is arranged in a normal direction with respect to the one surface with a gap from the support substrate, and is in a floating state.
The movable part is a physical quantity sensor supported via at least both ends of the floating part sandwiching the fixed part. The direction in which the floating portion extends from the fixed portion is defined as the extending direction.
2. The floating portion according to claim 1, wherein a width of the portion on the movable portion side in the extending direction is larger than a width of the portion on the opposite side of the movable portion in the extending direction when viewed from the normal direction. The physical quantity sensor described. A driving beam (42) connected to the floating portion via a support member (43) and connecting the driving weight;
The fixing members are provided as a pair by being provided with two, and are arranged on both sides of the movable part as seen from the normal direction,
The two detection weights are provided as a pair,
The drive weight surrounds one of the detection weights and is connected to the detection weight via a detection beam (41) and a pair of inner drive weights (33, 34) and a pair of the inner sides Outer drive weights (31, 32) disposed on both sides of the drive weight, respectively,
The drive beam connects the inner drive weight and the outer drive weight,
The physical quantity sensor according to claim 1, wherein the driving unit vibrates the inner driving weight and the outer driving weight in opposite directions.

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