JP5816707B2 - Angular velocity detector - Google Patents

Description

  The present invention relates to a micro electro mechanical system (MEMS) that measures an angular velocity by detecting a physical quantity related to a Coriolis force generated in a vibrating object formed by a semiconductor microfabrication technique. It is.

  As a conventional technique, an angular velocity detecting device already known based on the specifications of Japanese Patent No. 32622082 (Patent Document 1) and Japanese Patent No. 3327150 (Patent Document 2) is directed to the outside of the excitation element with the excitation element sandwiched between them. The excitation element is supported using a plurality of support beams and fixed beams extending in the detection direction orthogonal to the excitation direction. Since the support beam and the fixed beam are soft in the excitation direction and hard in the detection direction, the excitation element can be easily moved in the excitation direction and difficult to move in the detection direction. The Coriolis element is connected to the excitation element by a beam that is soft in the detection direction and hard in the excitation direction. Therefore, the Coriolis element vibrates together with the excitation element following the movement of the excitation element in the excitation direction.

  In this state, when an angular velocity is applied about an axis orthogonal to the excitation direction and the detection direction, the vibrating excitation element and the Coriolis element are proportional to the angular velocity applied in the detection direction orthogonal to the excitation direction. Coriolis force works. However, since the excitation element is formed so as not to move on the detection axis, only the Coriolis element is displaced in the detection direction. By detecting the displacement or Coriolis force of the Coriolis element, the applied angular velocity can be detected.

  However, when supporting a vibrating body with an excitation element sandwiched between them, the distance between the support points tends to be long, and when distortion due to mounting or distortion due to the heat of the substrate that supports the vibrating body occurs Since the expansion and contraction stress is generated in the fixed beam and the support beam and the spring constant of the beam changes greatly, the angular velocity detection performance is deteriorated.

  An angular velocity detection device already known based on the specification of Japanese Patent Application Laid-Open No. 2000-180174 (Patent Document 3) has four excitation elements and Coriolis elements arranged radially, and is fixed to a support substrate at a point symmetry center point. Has been. For this reason, even if mounting deformation or substrate deformation due to heat or the like occurs, the support beam and the fixed beam do not generate stretching stress, and the original performance can be maintained.

  However, there is a restriction on the shape of a radial shape, the space where the electrode is provided is narrow in the vicinity of the center point, the scale of the provided electrode is far away, the use efficiency of the space is poor, and it is not suitable for miniaturization. . Furthermore, since it is supported and fixed only at the center point, the structure tends to bend due to its own weight and easily vibrates out of the substrate surface, so that it is vulnerable to disturbance. When the thickness of the active layer is thin (for example, 4 μm), there is a possibility that the suspension structure formed on the support substrate and the active layer may be stuck at the manufacturing stage, which causes a decrease in yield.

Japanese Patent No. 3262208 Japanese Patent No. 3327150 JP 2000-180174 A

  In the angular velocity detectors of Patent Document 1 and Patent Document 2, as described above, since the vibrating body is supported with the excitation element sandwiched therebetween, the distance between the support points is long. When a distortion due to changes in the surrounding environment such as the above occurs in the support substrate, the distance between the fixed points of the fixed beam changes, and stress is generated inside the fixed beam and the support beam. Due to this internal stress, the spring constant of the beam changes, and the resonance frequency of the supporting vibrating body changes. The change in resonance frequency with time is an important factor that lowers the stability of the detection sensitivity of the angular velocity detection device.

  In the angular velocity detection device of Patent Document 3, since all the structures are fixed to the support substrate at one point that is the center of point symmetry, there is no problem as in Patent Document 1 and Patent Document 2. However, since the structure of the detection device is arranged in a radial pattern, the scale of the electrode is different between the vicinity of the center point and the distance. For this reason, a complex detection circuit is required in order to perform differential detection with the near and far detection electrodes, for example, to separate an acceleration signal from an angular velocity signal. Further, in the radial space, the vicinity of the center point is narrow, and the distance from the center point becomes wider. Therefore, there are many restrictions on the arrangement of beams, vibrators, drive electrodes, and detection electrodes. In order to eliminate this restriction, it is necessary to increase the size of the angular velocity detection device, and there is a problem that there is a disadvantage in miniaturization because there is a lot of wasted space and the use efficiency of the space is poor. Furthermore, since the point is fixed, there is a concern that the structure may be bent by its own weight.

  An object of the present invention is to provide a high-performance angular velocity detection device.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  The angular velocity detection device according to the present invention includes a support substrate in the thickness direction and a substrate on which a conductor layer (active layer) is formed via an intermediate insulating layer, the x-axis in the direction on the active layer surface, An excitation element disposed so as to be able to vibrate in the x-axis relative to the active layer when the y-axis is perpendicular to the x-axis in the plane of the active layer and the z-axis is perpendicular to the active layer plane; The Coriolis element is arranged so as to be able to vibrate also in the y axis while following the vibration of the element. When the excitation element is vibrated in the x axis and an angular velocity around the z axis is applied, the Coriolis element is arranged. In the angular velocity detection device for detecting a physical quantity related to a Coriolis force generated in an element, at least two fixed beams (first beams) extending in opposite directions in the y-axis direction orthogonal to the vibration direction and sharing a fixed end And connected to the free end of this fixed beam in the x-axis direction A free beam (second beam) provided, and the free beam extending in the y-axis direction at a predetermined interval from the fixed beam, and the other free end thereof is connected to the excitation element in the vicinity of the fixed end. And at least two support beams (third beam).

  The angular velocity detection device according to the present invention is further characterized in that the excitation element is provided inside the Coriolis element.

  The angular velocity detection device according to the present invention is further characterized in that at least two sets of the fixed beam, the free beam, and the support beam are arranged in parallel with the fixed beam or the support beam at a predetermined interval. .

  Further, the angular velocity detection device according to the present invention further includes at least two sensor units as one sensor unit disposed in the active layer in order to reduce the influence of disturbance and further improve the detection performance. These sensor units are connected by link beams so as to be interlocked (tuning fork vibration).

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  In the angular velocity detection device according to the present invention, each fixed beam extends in a direction opposite to each other in a detection direction (y-axis direction) orthogonal to the excitation direction (x-axis direction), and shares a fixed end. The other fixed end is connected to the free beam extending in the x-axis direction. The free beam is shorter and wider than the fixed beam and the support beam described later. The support beam extends in the y-axis direction with a predetermined distance from the fixed beam and connects the free beam and the excitation element, so that it can be easily bent in the x-axis direction, which is the excitation direction. It is difficult to bend in the y-axis direction that is the detection direction. Accordingly, the excitation element vibrates easily in the x-axis direction, but hardly moves in the y-axis direction.

  Since the Coriolis element is connected to the excitation element by a detection beam (fourth beam) that is hard in the x-axis direction and soft in the y-axis direction, it follows the vibration of the excitation element in the excitation direction and the detection direction. When an angular velocity about the orthogonal z-axis is applied, it vibrates by Coriolis force in the y-axis direction that is the detection direction. Therefore, the applied angular velocity can be measured by measuring a physical quantity related to the Coriolis force.

  In the present invention, the excitation element is levitated and vibrated by at least two fixed beams sharing a fixed end. Therefore, even if the substrate is deformed due to mounting or thermal fluctuation, the excitation element is supported by the fixed beam. The internal stress generated in the beam is small and has little effect on detection performance.

  In the angular velocity detection device according to the present invention, the excitation element is provided inside the Coriolis element. Therefore, the distance between the fixed ends of a plurality of sets of drive beams (a set of fixed beams, free beams, and support beams) supporting the excitation element and the Coriolis element can be shortened, and the support substrate can be mounted by mounting or heat fluctuation. Even if it is deformed, it has little effect on detection performance.

  In the angular velocity detection device according to the present invention, at least two sets of the drive beams are arranged in parallel with the fixed beam or the support beam at a predetermined interval. As a result, it is possible to prevent deflection due to the dead weight of the angular velocity detection device, and to perform higher-performance detection. However, having a plurality of sets of fixed beams has fixed ends that are distant from each other. As described above, having fixed ends that are separated from each other causes deterioration in stability because the internal substrate generates stress when the support substrate is deformed due to mounting or thermal fluctuations, and the performance of the angular velocity detector changes. Leads to.

  The internal stress of the beam is caused by the fact that the distortion of the substrate due to mounting or heat is applied to the beam as a force. FIG. 12 shows a simple vibrating body model, which shows the force applied to the beam when the support substrate is similarly deformed in the x- and y-axis directions. If the distance between the fixed ends is L and the distance variation between the fixed ends caused by the deformation of the support substrate is ΔL, the force generated in the x-axis direction (excitation direction) is expressed by Equation 1. Further, the force generated in the y-axis direction (detection direction) is expressed by Equation 2.

Fx = (1/2) · Kx · ΔL = Fy · (b / L1) ^ 2 (Formula 1)
However, it is Kx = E * h * b ^ 3 / L1 ^ 3 = Ky * (b / L1) ^ 2.

Fy = (1/2) · Ky · ΔL (Formula 2)
However, Ky = E · h · b / L1.

  Here, Fx: force generated in the x-axis direction, Fy: force generated in the y-axis direction, E: longitudinal elastic modulus, h: beam height, b: beam width, L: distance between fixed ends, ΔL: change amount of distance between fixed ends, L1: length of beam, Kx: x-axis direction spring constant of beam, Ky: y-axis direction spring constant of beam.

  From the above formulas 1 and 2, when the beam width b is sufficiently smaller than the beam length L1, Fx << Fy. Therefore, when a plurality of fixed ends are provided, the force generated in the direction in which the beam is bent is smaller than the direction in which the beam extends, and the influence on the performance of the angular velocity detection device is small.

  In the present invention, at least two or more sets of fixed beams, free beams, and support beams (driving beams) are arranged in parallel with the fixed beams or support beams at a predetermined interval. In spite of this, high performance can be maintained.

  Furthermore, the angular velocity detection device according to the present invention uses the minimum unit angular velocity detection device as one sensor unit, and at least two sensor units are arranged in the active layer, and each sensor unit is interlocked (tuning fork vibration). They are connected by link beams. With this configuration, the two sensor units can perform so-called tuning fork vibration that vibrates in opposite phases. By oscillating the tuning fork, the angular velocity can be detected by differentially detecting each detection means, and the disturbance component is canceled by the differential detection, and a high-performance angular velocity detector that is robust against the disturbance can be realized. Moreover, since the angular velocity component and the acceleration component can be separated by using tuning fork vibration and differential detection, not only the angular velocity but also acceleration can be detected at the same time.

It is a top view which shows the structure of the angular velocity detection apparatus in Embodiment 1 of this invention. It is sectional drawing which shows the cross section cut | disconnected by the A-A 'line | wire of FIG. It is sectional drawing which shows the cross section cut | disconnected by the B-B 'line | wire of FIG. FIG. 3 is a conceptual diagram of a drive circuit according to the first embodiment. 3 is a conceptual diagram of a detection circuit in the first embodiment. FIG. It is a top view which shows the manufacturing process of the angular velocity detection apparatus in this Embodiment 1. It is sectional drawing which shows the cross section cut | disconnected by the C-C 'line | wire of FIG. It is sectional drawing which shows the manufacturing process of the angular velocity detection apparatus following FIG. It is a top view which shows the structure of the angular velocity detection apparatus in Embodiment 2 of this invention. It is a conceptual diagram of the detection circuit in the present second embodiment. It is a conceptual diagram of a drive beam and a fixing | fixed part. It is a model figure of a vibrating body and the beam which supports it.

  In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other. There are some or all of the modifications, details, supplementary explanations, and the like.

  Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say.

  Similarly, in the following embodiments, when referring to the shape, positional relationship, etc., of components, etc., unless otherwise specified, and in principle, it is considered that this is not clearly the case, it is substantially the same. Including those that are approximate or similar to the shape. The same applies to the above numerical values and ranges.

  In all the drawings for explaining the embodiments, the same members are denoted by the same reference symbols in principle, and the repeated explanation thereof is omitted. In order to make the drawings easy to understand, even a plan view may be hatched.

(Embodiment 1)
An angular velocity detection device 1A according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating in plan view the main components of the angular velocity detection device 1A according to the first embodiment. 2 shows a cross section taken along line AA ′ of FIG. 1, and FIG. 3 shows a cross section taken along line BB ′ of FIG.

First, the configuration of the angular velocity detection device 1A according to the first embodiment will be described. For example, an SOI (Silicon On Insulator) substrate is used for the angular velocity detection device 1A. That is, in the SOI substrate, an intermediate insulating layer 2b is formed on a support substrate 2a, and a conductor layer (active layer) 2c is formed on the intermediate insulating layer 2b. The support substrate 2a is made of, for example, silicon (Si), and the intermediate insulating layer 2b is made of, for example, silicon oxide (SiO ₂ ). Further, the conductor layer 2c formed on the intermediate insulating layer 2b is made of, for example, conductive silicon.

  The total thickness of the support substrate 2a and the intermediate insulating layer 2b is, for example, several tens to several hundreds of micrometers, and the thickness of the conductor layer 2c is, for example, several to several tens of micrometers. Although the SOI substrate is used in the first embodiment, the semiconductor substrate is not limited to the SOI substrate and can be variously changed. For example, conductive polysilicon using surface MEMS technology or plated metal such as nickel (Ni) may be used as the conductor layer.

  An intermediate insulating layer 2b is formed on the support substrate 2a, and a conductor layer 2c is formed on the intermediate insulating layer 2b. A pedestal portion 10 is formed so as to surround the element formation region DA by processing the conductor layer 2c, and components to be described later are formed inside the pedestal portion 10.

  In the element formation region DA surrounded by the pedestal portion 10, the fixed portion 11 is formed by patterning the active layer 2c. The fixing portion 11 is fixed to the support substrate 2a through the intermediate insulating layer 2b. In addition, a driving beam 12 that supports an excitation element 13 to be described later is connected to the fixed portion 11.

  The drive beam 12 extends in opposite directions in the y-axis direction orthogonal to the excitation direction, has a fixed portion 11 as a common fixed end, is soft in the x direction that is the excitation direction, and is in the y axis direction that is the detection direction. Includes at least two rigid fixed beams (first beams) 12a and a free beam (first beam) extending in the x-axis direction at the other end of the fixed beam 12a and hardly deformed in both the x-axis direction and the y-axis direction. 2 beams) 12b, and at least two support beams (third beams) 12c that are spaced apart from the free beams 12b by a predetermined distance in parallel with the fixed beams 12a, soft in the excitation direction, and hard in the detection direction. ing.

  The fixed beam 12a extends in a pair in the y-axis direction symmetrically with the fixed portion 11, and one end of the fixed beam 12a is connected to the fixed portion 11 and the other end is connected to the free beam 12b. The support beam 12c extends in a pair in the y-axis direction symmetrically with respect to the connection portion (connected to the excitation element 13 on the same x-axis as the fixed portion 11). One end of each is connected to the free beam 12b and the other end is connected to the connecting portion. In addition, two sets of the fixed portion 11 and the driving beam 12 are formed on the x-axis at a predetermined interval in the x-axis direction that is the excitation direction.

  The excitation element 13 is formed by patterning the active layer 2c, and the planar shape is a mouth shape. The excitation element 13 is supported by the drive beam 12 that is soft in the excitation direction and hard in the detection direction, and is suspended from the support substrate 2a by being removed from the support substrate 2a by being removed from the support substrate 2a. ing.

  Excitation means 16 and 17 include movable drive electrodes 16a and 17a provided on the excitation element 13, fixed drive electrodes 16b and 17b fixed to the support substrate 2a via the intermediate insulating layer 2b, pads 16c and 17c, It consists of By using the excitation means 16 and 17, the excitation element 13 is vibrated in the excitation direction. The excitation mechanism and the excitation circuit are shown in FIG. 4 and will be described later.

  The Coriolis element 14 is formed by patterning the active layer 2c, and its planar shape is a mouth shape. The Coriolis element 14 is connected to the excitation element 13 by at least four detection beams 15 that are hard in the x-axis direction that is the excitation direction and soft in the y-axis direction that is the detection direction. Therefore, the Coriolis element 14 follows the vibration of the excitation element 13 in the x-axis direction and vibrates in the excitation direction with the same amplitude and the same phase as the excitation element 13.

  The detection means 18 and 19 include movable detection electrodes 18a and 19a connected to the Coriolis element 14, fixed detection electrodes 18b and 19b fixed to the support substrate 2a via the intermediate insulating layer 2b, and pads 18c and 19c. It is configured. The detection circuit is shown in FIG. 5 and will be described later.

  That is, the pedestal 10 formed on the conductor layer (active layer) 2c, the fixed portion 11, the fixed drive electrodes 16b and 17b of the excitation means 16 and 17, the fixed detection electrodes 18b and 19b of the detection means 18 and 19, and the pad 16c. , 17c, 18c, 19c and the like are fixed to the support substrate 2a via an intermediate insulating layer 2b formed in the lower layer.

  On the other hand, the movable elements such as the excitation element 13, the Coriolis element 14, and the beams 12 and 15 are suspended from the fixed portion 11 with the intermediate insulating layer 2 b formed in the lower layer removed. For this reason, the movable element is configured to be movable in a plane of the conductor layer (active layer) 2c parallel to the main surface of the SOI substrate (support substrate 2a).

  As shown in FIGS. 2 and 3, a cap 5 is joined on the pedestal portion 10, and the cap 5 is disposed so as to cover the element formation region DA of the angular velocity detection device 1 </ b> A. The cap 5 is formed of, for example, a glass substrate, and is joined to the base portion 10 made of silicon by anodic bonding. Further, the cap 5 is formed with through electrodes 6, 7, 8 at the portions where the pads 16c, 17c, 18c, 19c are joined, so that electrical signals can be exchanged with the outside of the element. Yes.

  Next, the angular velocity detection device 1A according to the first embodiment is configured as described above, and the features of the present invention will be described.

  As shown in FIG. 1, the detection direction (y-axis direction) orthogonal to the vibration direction is extended in opposite directions, the fixed portion 11 is a common fixed end, and the detection is soft in the x-axis direction that is the excitation direction. At least two fixed beams 12a that are hard in the y-axis direction, and a free beam 12b that extends in the x-axis direction at the other end of the fixed beam 12a and hardly deforms in both the x-axis direction and the y-axis direction. And at least two support beams 12c that are soft in the excitation direction and hard in the detection direction are provided on the free beam 12b at a predetermined interval in parallel with the fixed beam 12a. 13 is connected to 13.

  With this configuration, all the movable elements including the excitation element 13 and the Coriolis element 14 are intermediately insulated from the support substrate 2a by one point of the fixed portion 11 (two points arranged in the x-axis shape in the first embodiment). Since it is fixed via the layer 2b, internal stress generation of the drive beam 12 and the detection beam 15 due to mounting distortion or a change in the surrounding environment (heat), which is a problem of the conventional angular velocity detection device, and the angular velocity detection device thereby The problem of performance degradation can be solved.

  As described above, one-point support is ideal, but in the case of one-point support, the excitation element 13 or the influence of the size of the angular velocity detection device, the thickness of the active layer 2c, the gravity acting on the active layer 2c, or the like. The Coriolis element 14 may be bent in the thickness direction (z-axis direction) of the active layer 2c. This bending means a shift between the movable detection electrodes 18a and 19a of the detection means 18 and 19 and the fixed detection electrodes 18b and 19b, and the deterioration of the performance of the angular velocity detection device such as an offset in which an output is generated even if there is no angular velocity input. One factor.

  Therefore, it is necessary to arrange a plurality of drive beams 12 to prevent the excitation element 13 and the Coriolis element 14 from bending. However, as can be seen from Equations 1 and 2 above, arranging a plurality of fixing portions 11 with a predetermined interval in the y-axis direction that is the detection direction results in a predetermined interval in the x-axis direction that is the excitation direction. By arranging a plurality of fixed portions 11 at a distance, when the support substrate 2a is deformed, the internal stress generated in the drive beam 12 is large, and the influence on the angular velocity detection performance is large.

  Therefore, in the first embodiment, the two fixing portions 11 are arranged in the x-axis line that is the excitation direction. As a result, it is possible to form a high-performance and high-stable angular velocity detection device that has little influence on the performance due to the movable part and the deformation of the substrate.

  Next, the operation of the angular velocity detection device 1A according to the first embodiment will be described. In FIG. 1, the excitation element 13 vibrates at a constant amplitude and a constant frequency in the x-axis direction, which is the excitation direction, by the excitation means 16 and 17.

FIG. 4 shows a drive circuit for driving such excitation means 16 and 17. In FIG. 4, the excitation means 16 and 17 are indicated by capacitors, the excitation element 13 and the drive beam 12 are indicated by wirings, and the same reference numerals are given as equivalent circuits in this figure. _Reference sign V _bias is a direct current bias voltage applied to the excitation means 16 and 17, and reference sign V _drive is an alternating current excitation signal applied to the excitation means 16 and 17. By appropriately applying this AC excitation signal, the excitation element 13 of the angular velocity detection device 1A can be vibrated in the x-axis direction which is the excitation direction. Although not shown here, an electrode for monitoring the amplitude of the excitation element 13 is provided, and a method of adjusting the magnitude of the AC excitation signal according to the result to make the excitation amplitude constant, or a self-excited oscillation circuit is provided. A driving method is known in which the driving frequency is made to follow the fluctuation of the resonance frequency due to a change in the surrounding environment.

  When the excitation means 16 and 17 apply an angular velocity about the z-axis, which is the direction perpendicular to the paper surface, while the excitation element 13 is oscillating at a constant frequency and amplitude, the excitation element 13 and the oscillating element 13 are excited. The Coriolis element 14 connected to the element 13 generates a Coriolis force Fc expressed by Equation 3 in the detection direction (y-axis direction) orthogonal to the excitation direction (x-axis direction).

Fc = 2 · my · Ω · X · ω · cos (ω · t) (Formula 3)
Here, Fc: Coriolis force, my: weight of the Coriolis element, Ω: applied angular velocity, X: excitation direction maximum amplitude, ω: drive frequency, t: time.

  Since the excitation element 13 is supported by the beams 12a and 12c that are soft in the excitation direction and hard in the detection direction, the excitation element 13 hardly moves in the detection direction. On the other hand, since the Coriolis element 14 is supported by the detection beam 15 that is hard in the excitation direction and soft in the detection direction, it is easily displaced in the detection direction by the Coriolis force Fc. Due to this displacement, the distance between the movable detection electrodes 18a and 19a and the fixed detection electrodes 18b and 19b varies, and the capacitance changes. By detecting a change in capacitance of the detection electrodes 18 and 19 that changes in proportion to the applied angular velocity, the applied angular velocity can be measured.

  FIG. 5 shows a detection circuit for extracting an angular velocity signal from the detection means 18 and 19. A carrier wave 101 having a phase difference of 180 degrees from each other is applied to each of the detection means 18 and 19, and the difference is amplified by an amplifier 102 and output as a voltage signal proportional to the applied angular velocity by synchronous detection by a synchronous detection circuit 103. To do. For example, although not shown, when a means for measuring the amplitude of the excitation element 13 is used, a carrier wave having a frequency different from that of the carrier wave 101 is applied, and the signal is detected by synchronous detection at the applied frequency. It is known that they can be distinguished. It is also possible to detect the applied angular velocity by providing the Coriolis element 14 with an electrode that cancels the generated Coriolis force with a rebalancing force due to electrostatic force, and monitoring the voltage applied to this electrode. In FIG. 5, the detection means 18 and 19 are shown as capacitors, and the fixed portion 11 is shown as wiring. The same reference numerals are given as equivalent circuits in the figure.

  Next, a method for manufacturing the angular velocity detection device 1A according to the first embodiment will be described with reference to the drawings. First, as shown in FIG. 6, using a photolithography technique and an etching technique, a pedestal part 10, a fixing part 11, a driving beam 12, an excitation element 13, a Coriolis element 14, a detection beam 15, Excitation means 16 and 17, detection means 18 and 19, and etch hole 20 (above, functional part) are formed.

  To form this functional part, first, as shown in FIG. 7, an SOI substrate is prepared in which an intermediate insulating layer 2b is formed on a support substrate 2a and a conductor layer 2c is formed on the intermediate insulating layer 2b. Then, by using a photolithography technique and an etching technique, the functional part is formed by removing the conductor layer 2c other than the functional part to be formed. As a result, the fixed portion 11, the driving beam 12, the excitation element 13, the Coriolis element 14, the detection beam 15, and the like that constitute the functional unit are provided in the same layer.

  Subsequently, as shown in FIG. 8, the intermediate part 2b formed under the movable part (the driving beam 12, the excitation element 13, the Coriolis element 14, and the detection beam 15) is removed by etching to remove the movable part. Suspend on the fixed part 11. A movable part that can be moved by this process can be formed.

  As shown in FIGS. 6 and 7, the etch hole 20 is formed in the excitation element 13 and the Coriolis element 14 so as to penetrate the conductor layer 2c. Therefore, when removing the conductor layer 2c, the etching gas or the etchant reaches the intermediate insulating layer 2b through the etch hole 20, and the excitation element 13 and the Coriolis element 14 are separated from the support substrate 2a.

  Therefore, the maximum etching width of the intermediate insulating layer 2b is the length of the conductor layer 2c between the two etch holes 20 formed in the direction of 45 degrees from the x-axis or y-axis direction. It must be larger than the length. Considering process variations, a size of about 2 to several times is desirable. Further, when the electrode 6 is formed through the cap 5 as shown in FIGS. 2 and 8, it is necessary to have a size (several hundred μm) corresponding to the electrode 6.

  However, as described in Equations 1 and 2, the increase in the size of the fixed portion 11 in the y-axis direction, which is the detection axis, is limited in view of the sensor performance. At that time, a fixing method as shown in FIG. 11 (a part of the driving beam 12 and the excitation element 13 is shown) may be used. At this time, the width in the detection direction of the fixed portion 11 to which the fixed beam 12a is connected is not affected by the size necessary for forming the electrode 6.

  Although not shown in FIG. 8, the intermediate insulating layer 2b formed under the movable drive electrodes 16a and 17a of the excitation means 16 and 17 and the movable detection electrodes 18a and 19a of the detection means 18 and 19 is also removed. The drive electrode is also suspended in the space. The intermediate insulating layer 2b formed under the other structure is not removed. Thereby, structures other than the movable part and the movable electrode can be fixed (coupled) to the support substrate 2a via the intermediate insulating layer 2b.

  Subsequently, as shown in FIGS. 2, 3 and 8, a cap 5 having predetermined electrodes 6, 7 and 8 (a plurality not shown) is mounted on the angular velocity detection device structure. At this time, the electrodes 6, 7, and 8 are aligned so as to overlap the fixing portion 11 and the plurality of pads 16 c, 17 c, 18 c, and 19 c. That is, a predetermined electrode formed on the cap 5 is electrically connected to the fixing portion 11 and the plurality of pads 16c, 17c, 18c, and 19c. Thereby, even after the cap 5 is formed, it can be electrically connected to an external integrated circuit using a wire or the like.

  In addition, as shown in FIGS. 2, 3, and 8, a cap 5 is formed so as to be joined onto the pedestal portion 10. The cap 5 is formed so as to cover the element forming area DA, and the element forming area DA where the structure of the angular velocity detecting device is formed is hermetically sealed by the cap 5.

  In the first embodiment, a glass substrate is used as the cap 5, but a substrate made of another material such as a silicon substrate may be used. Furthermore, although the example which joins the cap 5 and the base part 10 by anodic bonding is shown as a joining method, normal temperature joining using surface activation by plasma or ions, or using an adhesive such as glass frit or solder. You may make it join the cap 5 and the base part 10 together.

  For example, by using a silicon substrate as the cap 5, the cap 5 and the pedestal portion 10 can be bonded by room temperature bonding. At this time, since the cap 5 and the pedestal portion 10 are made of the same material, the sealing strain due to the difference in the coefficient of thermal expansion between the sealing materials can be eliminated, so that a high-performance angular velocity detection device can be obtained.

  Subsequently, as shown in FIG. 8, the angular velocity detection device 1 </ b> A is separated into pieces by dicing the support substrate 2 a bonded to the cap 5 along the dicing line 21. Thereby, the angular velocity detection apparatus 1A in the first embodiment can be formed.

(Embodiment 2)
In the second embodiment of the present invention, the angular velocity detection device 1B according to the second embodiment will be described with reference to the drawings as in the first embodiment. FIG. 9 is a schematic diagram illustrating in plan view the main components of the angular velocity detection device 1B according to the second embodiment.

  The manufacturing method of the angular velocity detection device 1B in the second embodiment is the same as that of the angular velocity detection device 1A in the first embodiment. The difference from the first embodiment is the configuration of the angular velocity detection device 1B. In the second embodiment, two angular velocity detection devices 1A described in the first embodiment are arranged in the excitation direction, and the excitation element 13 That is, they are connected by a link part 22. Therefore, the two angular velocity detection devices are interlocked with each other and vibrate for tuning.

  First, the configuration of the angular velocity detection device 1B according to the second embodiment will be described with reference to FIG. 9. In the second embodiment, as described above, two of the first embodiments are arranged in the excitation direction. . For this reason, parts that overlap the contents described in the first embodiment will be omitted, and the newly added parts will be described mainly.

  In FIG. 9, an SOI (Silicon On Insulator) substrate is used for the angular velocity detection device 1B as in the first embodiment. As shown in FIGS. 2 and 3, the pedestal portion 10 is formed so as to surround the element formation region DA by processing the conductor layer 2 c, and the constituent elements are formed inside the pedestal portion 10.

  First, the fixing portion 11 is formed in the element forming area DA surrounded by the pedestal portion 10. A driving beam 12 similar to that of the first embodiment is connected to the fixed portion 11 and an excitation element 13 is suspended.

  The excitation element 13 is suspended by the drive beam 12 and includes excitation means 16 and 17. The two excitation elements 13 are connected to each other by a link portion 22 that is soft in the x-axis direction that is the excitation direction and hard in the y-axis direction that is the detection direction. The link portion 22 includes a connecting portion 22a extending from the excitation element 13 in the excitation direction, at least four link beams 22b that are soft in the excitation direction and hard in the detection direction from the connection portion, and a link 22c that connects the link portions 22 to each other. It consists of and. The link 22c is formed wider than the link beam 22b so as not to deform as much as possible.

  Excitation means 16 and 17 cause the tuning fork to vibrate the excitation element 13 in the excitation direction. That is, by using the excitation circuit shown in FIG. 4, the respective excitation elements 13 are vibrated in opposite phases so as to approach each other or move away from each other.

  The Coriolis element 14 is connected to the excitation element 13 by at least four detection beams 15 that are hard in the x-axis direction that is the excitation direction and soft in the y-axis direction that is the detection direction. Therefore, the Coriolis element 14 follows the vibration in the x-axis direction of the excitation element 13 and vibrates with the same amplitude and the same phase as the excitation element 13. Therefore, when an angular velocity is applied around the z-axis, the Coriolis element 14 also vibrates at the vibration frequency of the excitation element 13 in opposite phases.

  The detection means 18, 19, 23, and 24 detect the movement of the Coriolis element 14 using the detection circuit shown in FIG. As described above, the Coriolis elements 14 vibrate in mutually opposite phases due to the applied angular velocity. However, when acceleration is applied, they are displaced in the same direction, that is, in phase. Therefore, the angular velocity and the acceleration can be separated and detected simultaneously by the known detection method described in FIG.

  FIG. 10 schematically shows a method of detecting the values of acceleration and angular velocity from the change in capacitance obtained by such detection means 18, 19, 23, 24. The symbol OP is an operational amplifier. That is, the applied angular velocity can be detected by taking the difference between the value obtained by adding the capacities of the detection means 18 and the detection means 24 and the value obtained by adding the detection means 19 and the detection means 23. Further, by taking the difference between the value obtained by adding the detection means 18 and the detection means 23 and the value obtained by adding the detection means 19 and the detection means 24, the acceleration applied in the detection direction can be taken.

  The feature of the second embodiment is that the drive beam 12 is applied to a tuning fork type angular velocity detection device 1B that can detect acceleration and angular velocity at the same time. As a result, as in the first embodiment, even if the support substrate is deformed due to mounting distortion or changes in the external environment such as heat, it is possible to obtain an angular velocity detection device with little influence on detection performance.

  Subsequently, as in the first embodiment, the cap 5 having a predetermined electrode is mounted on the structure of the angular velocity detection device 1B. At this time, the electrodes are aligned so as to overlap the pads of the fixing portion 11, the excitation means 16 and 17, and the detection means 18 and 19. That is, the predetermined electrode formed on the cap 5 is electrically connected to the fixing portion 11 and the plurality of pads. Thereby, even after the cap 5 is formed, it can be electrically connected to an external integrated circuit using a wire or the like. Further, since the cap 5 is joined to the pedestal 10 and is formed so as to cover the element forming area DA, the element forming area DA in which the structure of the angular velocity detecting device is formed is hermetically sealed by the cap 5. Stopped.

  Subsequently, as in the first embodiment, the angular velocity detection device 1B is separated into pieces by dicing the support substrate 2a to which the cap 5 is bonded. Thereby, the angular velocity detection device 1B according to the second embodiment can be formed.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, in the above-described embodiment, the case where the excitation element is provided inside the Coriolis element has been described, but the present invention can also be applied to the case where the excitation element is provided outside the Coriolis element.

  INDUSTRIAL APPLICABILITY The present invention can be widely used in manufacturing industries for manufacturing inertial force detection devices such as acceleration sensors and angular velocity sensors, and fine electromechanical elements that vibrate such as vibrators and mechanical filters.

1A Angular velocity detector 1B Angular velocity detector 2a Support substrate 2b Intermediate insulating layer 2c Conductive layer (active layer)
DESCRIPTION OF SYMBOLS 5 Cap 6 Electrode 10 Base part 11 Fixed part 12 Drive beam 12a Fixed beam 12b Free beam 12c Support beam 13 Excitation element 14 Coriolis element 15 Detection beam 16 Excitation means 16a Movable drive electrode 16b Fixed drive electrode 16c Pad 17 Excitation means 17a Movable drive Electrode 17b Fixed drive electrode 17c Pad 18 detection means 18a Movable detection electrode 18b Fixed detection electrode 18c Pad 19 detection means 19a Movable detection electrode 19b Fixed detection electrode 19c Pad 20 Etch hole 21 Dicing line 22 Link part 22a Connection part 22b Link beam 22c Link 23 detection means 23a movable detection electrode 23b fixed detection electrode 23c pad 24 detection means 24a movable detection electrode 24b fixed detection electrode 24c pad 101 carrier wave 102 amplifier 103 synchronous detection circuit DA element formation region

Claims (9)

An angular velocity detection device in which an intermediate insulating layer is provided on a support substrate, and an active layer is provided on the intermediate insulating layer,
A fixed end provided on the support substrate via the intermediate insulating layer;
An excitation element suspended on the fixed end;
A Coriolis element suspended on the fixed end via the excitation element and capable of vibrating in a detection direction perpendicular to the excitation direction;
The excitation element is suspended from the fixed end by first to sixth beams,
The excitation element, the Coriolis element, and the first to sixth beams are provided in the active layer,
The first beam and the fourth beam are provided on a straight line extending in the detection direction,
The third beam and the sixth beam are provided on a straight line extending in the detection direction, and are connected to the excitation element,
The second beam is connected to the other end of the first beam and the other end of the third beam, and extends in the excitation direction;
The fifth beam is connected to the other end of the fourth beam and the other end of the sixth beam, and extends in the excitation direction;
The first beam to the third beam and the fourth beam to the sixth beam are arranged symmetrically with respect to an axis extending in the excitation direction through the fixed end,
The fixed end includes a first fixing portion provided on the straight line on which the first beam and the fourth beam are provided, and a second fixing portion provided on a position other than the straight line. A featured angular velocity detection device. An angular velocity detection device in which an intermediate insulating layer is provided on a support substrate, and an active layer is provided on the intermediate insulating layer,
A fixed end connected to the support substrate via the intermediate insulating layer;
An excitation element connected to the fixed end via a plurality of beams and capable of vibrating in the excitation direction;
A Coriolis element connected to the fixed end via the excitation element and capable of vibrating in a detection direction perpendicular to the excitation direction;
In the plurality of beams,
A first beam extending in the detection direction;
A second beam extending in the excitation direction and connected to the first beam;
A third beam extending in the detection direction and connected to the second beam and the excitation element;
At least two sets of beams consisting of
The excitation element, the Coriolis element, and two sets of the first to third beams are provided in the active layer,
The two sets of beams are provided symmetrically with respect to an axis extending in the excitation direction through the fixed end,
The fixed end includes a first fixed portion provided on a straight line in which two sets of the first beams are arranged and extending in the detection direction, and a second fixed portion provided at a position other than the straight line. An angular velocity detection device characterized by that. In claim 1 or 2,
The angular velocity detection device further comprising an electrode connected to the second fixed portion. In claim 3,
The electrode is an electrode used for detection of angular velocity, and the angular velocity detection apparatus characterized by the above-mentioned. In claim 1,
An angular velocity detection apparatus, wherein two or more sets of the first beam to the sixth beam are provided at a predetermined interval in the excitation direction. In claim 1,
The length of the second beam is shorter than the length of the first beam,
The width of the second beam is longer than the width of the first beam,
The length of the fifth beam is shorter than the length of the fourth beam,
The angular velocity detector according to claim 5, wherein a width of the fifth beam is longer than a width of the fourth beam. In claim 2,
Two or more sets of the two beams are provided at predetermined intervals in the excitation direction. In claim 2,
In each of the two sets of beams,
The length of the second beam is shorter than the length of the first beam,
The angular velocity detection device according to claim 1, wherein a width of the second beam is longer than a width of the first beam. The angular velocity detection device according to any one of claims 1 to 8 is used as a unit of sensor unit, and at least two sensor units are provided, and the sensor units are connected by link beams so as to be interlocked. An angular velocity detection device characterized by that.

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