JP2011174940A - Vibration gyro sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect vibration of two axes while realizing miniaturization, enhancement of characteristics and cost reduction. <P>SOLUTION: A vibration gyro sensor includes a base which is formed with a plurality of terminal parts, at least two vibrating elements which detect vibration in each axial direction, a single IC component which drives and detects at least two vibrating elements, and a support substrate which includes a first surface which forms a wiring pattern having the plurality of lands connected to the plurality of terminal parts of each vibrating element and the IC component, and a second surface formed reverse side of the first surface, while countering external substrate, which has the plurality of external connection terminals for reflow surface mounting of the vibration gyro sensor into the external land of the substrate. At least one base among at least two vibrating elements is mounted the corner position of the support substrate. When the first surface of the support substrate is divided into a first quadrant to a fourth quadrant, a part of mounting region of the IC component belongs to each quadrant. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an angular velocity sensor used for, for example, camera shake detection of a video camera, motion detection in a virtual reality device, direction detection in a car navigation system, and more specifically, vibration including a vibration element having a cantilever vibrator. The present invention relates to a type gyro sensor.

  Conventionally, as a commercial angular velocity sensor, a cantilever vibrator is vibrated at a predetermined resonance frequency, and the angular velocity is detected by detecting a Coriolis force generated by the influence of the angular velocity with a piezoelectric element or the like. Vibration type gyro sensors are widely used.

  The vibration-type gyro sensor has advantages such as a simple mechanism, a short start-up time, and low-cost manufacturing. For example, it is mounted on electronic devices such as a video camera, a virtual reality device, and a car navigation system. It is used as a sensor for motion detection and direction detection.

  In the conventional vibration type gyro sensor, the vibration element is manufactured by cutting an appropriate piezoelectric material into a predetermined shape by machining. As the vibration type gyro sensor, further downsizing and high performance are required as the main body equipment to be mounted becomes smaller and lighter and multi-functional high performance, but it is small due to the limit of machining accuracy by machining. Therefore, it was difficult to manufacture a highly accurate vibration element.

  Therefore, in recent years, a device equipped with a cantilever-shaped vibrating element by laminating a pair of electrode layers on a silicon substrate with a piezoelectric thin film layer sandwiched using thin film technology applied to a semiconductor process has been proposed. (For example, refer to Patent Document 1). Such a vibration type gyro sensor is reduced in size and thickness, so that it can be combined with a sensor for other uses or the like to be highly functional.

Japanese Patent Laid-Open No. 7-113643 Japanese Patent Laid-Open No. 7-190783

  By the way, a camera shake correction mechanism such as a video camera needs to detect at least rotation angles in the X-axis direction and the Y-axis direction, and conventionally includes two gyro sensors for detecting the respective rotation angles in the axial direction. It was. Therefore, the conventional camera shake correction mechanism has a limit in miniaturization as a whole even if the gyro sensor itself is miniaturized.

  In the vibration-type gyro sensor, it is considered to form one package by forming a vibration element having a biaxial vibrator on a silicon wafer using the semiconductor technology described above (see Patent Document 2). However, the biaxially integrated vibration element has a problem that a large space is required to form one vibration element on a silicon wafer and the material yield is poor. In addition, the biaxially integrated vibration element also causes a problem of crosstalk characteristics between the biaxial vibrators as the size is reduced.

  In the conventional vibration type gyro sensor, the structure is complicated by addressing the above-described problems, and it is increasingly difficult to realize a small size and a thin shape. In other words, it is more difficult to achieve downsizing when two shakers are provided to support two axes in the camera shake correction mechanism, and one package having the above-described two-axis integrated vibration element. However, it has been difficult to realize a desired size reduction.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a vibration type gyro sensor that can detect vibrations in two axes by reducing the size, improving the characteristics, or reducing the cost.

In solving the above problems, a vibration-type gyro sensor according to an aspect of the present invention includes:
A base having a plurality of terminal portions formed therein, and at least two vibration elements for detecting vibrations in different axial directions,
A single IC component for detecting the drive of the at least two vibrating elements;
A first surface on which a wiring pattern having a plurality of lands connected to the plurality of terminal portions and the IC component of each of the vibration elements is formed; a back side of the first surface; A support substrate having a second surface facing the substrate and having a plurality of external connection terminals formed on the land of the external substrate for reflow surface mounting of the vibration type gyro sensor.
At least one base of the at least two vibration elements is mounted on a corner portion of the support substrate,
When the first surface of the support substrate is divided into first to fourth quadrants, a part of the IC component mounting region belongs to each quadrant.

  The vibration-type gyro sensor can obtain the detection signals in the two-axis directions independently by each vibration element by mounting two vibration elements on the support substrate with different axial directions of the vibrator portion. It becomes possible. As a result, each vibration element can be manufactured efficiently and at low cost, and reliability can be improved by performing stable operation.

  Each vibration element constituting the vibration gyro sensor has a base portion having a mounting surface on which a plurality of terminal portions connected to lands on a support substrate are formed, and a cantilever shape from a side peripheral portion of the base portion. And a vibrator portion having a substrate facing surface that protrudes integrally and forms the same surface as the mounting surface of the base portion. The first electrode layer and the first electrode are formed on the substrate facing surface of the vibrator portion. A piezoelectric layer stacked on the layer and a second electrode layer stacked on the piezoelectric layer are formed. Two vibrating elements are mounted with their vibrator portions arranged on axes different from each other by 90 °.

  In the vibration-type gyro sensor of the present invention, the vibrator unit is caused to vibrate by applying an alternating electric field having a predetermined frequency to each vibration element from the drive detection circuit unit. Then, the vibrator portion is displaced by Coriolis force generated by hand shake or the like, and this displacement is detected by the piezoelectric layer, and detection signals having opposite polarities are output from the pair of detection electrodes. This detection signal is processed by the drive detection circuit unit and output as an angular velocity signal.

  At this time, the crosstalk between the axes can be reduced by separating the operating frequencies of the vibration elements by 1 kHz or more.

  According to the vibration-type gyro sensor of the present invention, the structure is simplified and miniaturized by mounting at least two vibration elements that detect vibrations in different axial directions on one support substrate. The direction detection operation can be performed with high accuracy. Further, since the production efficiency of each vibration element is improved and it is manufactured with high accuracy, cost reduction and high accuracy can be achieved.

It is a whole perspective view when the cover member of the vibration type gyro sensor by the 1st Embodiment of this invention is removed and seen. It is principal part sectional drawing of the vibration element of a vibration type gyro sensor. It is principal part sectional drawing of the vibration element which shows a state when a vibration type gyro sensor is mounted in the control board. It is a bottom view of a vibration element. It is a bottom view of a vibration type gyro sensor. It is a top view of the support substrate which shows the modification of a structure of a load buffering groove part. It is a circuit block diagram of a vibration type gyro sensor. It is the whole perspective view seen from the bottom face side of a vibration element. It is a perspective view of a vibrator part of a vibration element. It is a main process flowchart explaining the manufacturing method of a vibration type gyro sensor. It is a top view of the silicon substrate used for the manufacturing process of a vibration element. It is sectional drawing of the silicon substrate. It is a top view of the silicon substrate which patterned the vibration element formation part in the photoresist layer. It is sectional drawing of the silicon substrate. It is a top view of the silicon substrate which patterned the vibration element formation part in the silicon oxide film. It is sectional drawing of the silicon substrate. It is a top view of the silicon substrate in which the etching recessed part which comprises the diaphragm part which prescribes | regulates the thickness of a vibrator | oscillator part was formed. It is sectional drawing of the silicon substrate. It is an expanded sectional view of an etching recessed part. It is principal part sectional drawing of the state which laminated | stacked and formed the 1st electrode layer, the piezoelectric film layer, and the 2nd electrode layer in the diaphragm part. It is a principal part top view of the state which patterned the drive electrode layer and the detection electrode to the 2nd electrode layer. It is the principal part sectional drawing. It is a principal part top view of the state which patterned the piezoelectric thin film layer on the piezoelectric film layer. It is the principal part sectional drawing. It is a principal part top view of the state which patterned the reference electrode layer in the 1st electrode layer. It is the principal part sectional drawing. It is a principal part top view in the state where the planarization layer was formed. It is the principal part sectional drawing. It is a principal part top view in the state where a lead was formed in a base part formation field. It is the principal part sectional drawing. It is a principal part top view of the state in which the photoresist layer for insulation protective layer formation was formed. It is principal part sectional drawing of the state in which the 1st alumina layer of the insulation protective layer was formed. It is principal part sectional drawing of the state in which the silicon oxide layer of the insulation protective layer was formed. It is principal part sectional drawing of the state in which the 2nd alumina layer and etching stop layer of the insulation protective layer were formed. It is a principal part top view of the state which formed the external shape groove | channel which forms the external shape of a vibrator | oscillator part. FIG. 4 is a cross-sectional view of a main part when viewed from a direction perpendicular to the longitudinal direction of the vibrator unit. It is principal part sectional drawing seen from the longitudinal direction of the vibrator | oscillator part. It is a sectional side view of the vibration element explaining the formation method of a plating bump. It is explanatory drawing of the adjustment process of a vibration element. It is a comparison figure of the number of elements taken from a silicon substrate. It is a characteristic view of the interference between two axes by the arrangement state of a vibration element. It is a histogram of the angular deviation of the vibration element in a mounting process, A shows the case where it mounted by recognizing the alignment mark, and B shows the case where it mounted by external shape recognition. It is a characteristic view which shows the result of having measured the magnitude | size of the interference signal by a frequency difference by changing the operating frequency of two vibration elements. It is a characteristic view which shows the relationship between a laser processing position, a resonant frequency, and a detuning degree. It is a top view of a vibrator part showing typically a laser processing position for detuning degree adjustment, and a laser processing position for resonance frequency adjustment. It is a principal part top view of the conventional vibration type gyro sensor demonstrated in the 2nd Embodiment of this invention. It is a principal part top view of the vibration type gyro sensor by the 2nd Embodiment of this invention. It is a characteristic view which shows the measurement result of the Example demonstrated in the 2nd Embodiment of this invention. It is a schematic diagram which shows the relationship between the vibration element demonstrated in the 3rd Embodiment of this invention, and a drive detection circuit part. It is a figure explaining one effect | action of the said vibration element. It is a figure which shows an example of the relationship between the piezoelectric characteristic of a piezoelectric material, and offset potential. It is a figure which shows the hysteresis loop of a piezoelectric material.

Hereinafter, the vibration type gyro sensor shown in the drawings as an embodiment of the present invention will be described in detail.
In addition, this invention is not limited to this, A various deformation | transformation is possible based on the technical idea of this invention. Further, in the present specification, as described below, specific dimension values are given for each part of the constituent member, but each dimension value is a center reference value. Each part is not limited to be formed with a dimension value limited to the center reference value, but of course, it is formed with a dimension value within a general tolerance range. Further, the vibration type gyro sensor is not limited to the shape of the dimension value, and each part is appropriately formed according to the characteristic specification.

(First embodiment)
[Schematic configuration of vibration gyro sensor]
As shown in FIG. 1, the vibration type gyro sensor 1 includes a support substrate 2 and a cover member 15 that is assembled on the first main surface 2-1 of the support substrate 2 and forms the component mounting space 3. For example, it is mounted on a video camera to constitute a camera shake correction mechanism. The vibration gyro sensor 1 is used for a virtual reality device to constitute an operation detector, or used for a car navigation device to constitute a direction detector.

  In the vibration gyro sensor 1, for example, a ceramic substrate or a glass substrate is used for the support substrate 2. On the first main surface 2-1 of the support substrate 2, a predetermined wiring pattern 5 having a plurality of lands 4 and the like is formed to constitute a component mounting region 6. The component mounting area 6 includes a first and a second pair of vibration elements 20X and 20Y (which will be described below in detail unless otherwise described). The IC circuit element 7 and a large number of external ceramic capacitors and appropriate electronic components 8 are mixedly mounted.

  In the component mounting area 6 of the support substrate 2, the vibration element 20 is mounted together with the IC circuit element 7 and the electronic component 8 by a surface mounting method such as a flip chip method using an appropriate mounting machine. A pair of vibration elements 20X and 20Y formed in the same shape are mounted on opposite corner portions 2C-1 and 2C-2 of the first main surface 2-1 of the support substrate 2 with different axes. ing. As shown in FIG. 2, the vibration element 20 includes a base portion 22 having a mounting surface on which a plurality of terminal portions 25 connected to the land 4 via the gold bumps 26 are formed, and a one-side peripheral portion of the base portion 22. And a vibrator portion 23 that protrudes integrally in a cantilever shape. Details of the configuration of the vibration element 20 will be described later.

  As shown in FIG. 1, one of the first vibration elements 20 </ b> X has a base 22 fixed to a floating island-shaped first vibration element mounting region 13 </ b> A configured in the component mounting region 6 at the corner portion 2 </ b> C- 1 of the support substrate 2. The vibrator portion 23 integrally projecting from the base portion 22 is directed to the adjacent corner portion 2 </ b> C- 3 along the side edge of the support substrate 2. The other second vibration element 20Y has a base portion 22 fixed to a floating island-shaped second vibration element mounting region 13B formed in the component mounting region 6 at the corner portion 2C-2 of the support substrate 2, and protrudes integrally from the base portion 22. The provided vibrator portion 23 is directed along the side edge of the support substrate 2 to the adjacent corner portion 2C-3.

  In other words, the first vibration element 20X and the second vibration element 20Y are mounted on the support substrate 2 at an angle of 90 ° with each vibrator portion 23 facing the corner portion 2C-3. The vibration type gyro sensor 1 detects vibrations of two axes perpendicular to each other by a pair of vibration elements 20X and 20Y, but supports the vibration elements 20X and 20Y with an appropriate angle difference according to the specifications of the main device. Of course, it may be mounted on the substrate 2.

  The vibration type gyro sensor 1 detects an angular velocity around the longitudinal direction applied to the vibrator unit 23 in a state where the vibrator unit 23 of the vibration element 20 is resonated. In the vibration type gyro sensor 1, by mounting the first vibration element 20X and the second vibration element 20Y on the support substrate 2 at different angles, the angular velocities in the X-axis direction and the Y-axis direction are detected simultaneously. A camera shake correction mechanism is configured by outputting a control signal based on a vibration state caused by camera shake.

  Next, details of the configuration of the support substrate 2 will be described.

[Load buffer structure]
Since the vibration-type gyro sensor 1 is reduced in size and thickness by making the support substrate 2 thin, distortion and stress are generated in the support substrate 2 due to external loads such as vibration and impact applied from the outside. Sometimes. Therefore, in the present embodiment, the support substrate 2 is provided with a buffer structure for external loads, so that the influence on the vibration element 20 mounted on the support substrate 2 is reduced even when distortion or stress occurs. Has been.

  As shown in FIGS. 1 to 3, the support substrate 2 includes first load buffering grooves 12 </ b> A and 12 </ b> B (hereinafter described individually) in the corner portions 2 </ b> C- 1 and 2 </ b> C- 2 of the first main surface 2-1. Are collectively referred to as a first load buffering groove portion 12). The above-described vibration element mounting regions 13A and 13B (hereinafter collectively referred to as the vibration element mounting region 13 except when individually described) are configured in a region surrounded by the first load buffering groove 12, and each vibration is mounted. The vibration element 20 is mounted in the element mounting region 13.

  In addition, as shown in FIG. 3, the support substrate 2 is provided with a second load buffering groove 14 on the second main surface 2-2 side mounted on the external control substrate 100 of the main device or the like. As shown in FIG. 5, the second load buffer groove 14 includes a second load buffer groove 14 </ b> A and a second load buffer groove 14 </ b> B. The second load buffer groove 14 is generically referred to as the second load buffer groove 14 unless otherwise described below. . As shown in FIG. 5, the region surrounded by the second load buffer groove 14 is configured as terminal forming regions 115A and 115B (hereinafter collectively referred to as the terminal forming region 115 except when individually described). .

  As shown in FIG. 4, the first load buffer groove 12 is configured by a bottomed groove having an overall frame shape that forms a vibration element mounting region 13 that is larger than the outer dimension of the base portion 22 of the vibration element 20. The first load buffer groove 12 is formed by, for example, mechanical groove processing using a dicer or the like, chemical groove processing using a wet etching method, or dry etching using a laser or the like. The first load buffer groove 12 is formed with a groove depth of 100 μm or more as long as the mechanical strength of the support substrate 2 is not impaired.

  As shown in FIG. 5, the second load buffering groove portions 14 </ b> A and 14 </ b> B are formed in parallel along the outer peripheral side edge portion of the support substrate 2. A plurality of mounting terminal portions 116A and 116B (hereinafter referred to as individual terminal portions for external connection) are formed as terminal forming regions 115A and 115B, respectively, in the regions between the second load buffering groove portions 14A and 14B and the outer peripheral side edge portions. Except for the case described below, they are collectively referred to as a mounting terminal portion 116). The support substrate 2 is mounted on the control substrate 100 by connecting the mounting terminal portion (external connection terminal portion) 116 to the opposing land on the control substrate 100 via the bump 117 provided on each mounting terminal portion 116. Is done.

  Similarly to the first load buffer groove portion 12, the second load buffer groove portion 14 is also formed by, for example, mechanical groove processing using a dicer or the like, chemical groove processing using a wet etching method, dry etching method using a laser, or the like. The main surface 2-2 is formed with a predetermined depth. The second load buffering groove portion 14 forms a floating island-shaped terminal forming region 115 on the second main surface 2-2 of the support substrate 2, and a plurality of mounting terminal portions are formed in the terminal forming region 115 along the outer peripheral side edge portion. 116 are formed in an array. The second load buffering groove 14 is not limited to a straight groove along the outer peripheral side edge, and is formed, for example, in a frame shape surrounding the mounting terminal portion 116 or in a substantially U shape with both ends open to the outer peripheral side edge. You may make it do.

  The support substrate 2 is formed with a plurality of vias penetrating the first main surface 2-1 and the second main surface 2-2, and the first main surface 2-1 is formed through these vias. The wiring pattern 5 on the side and the mounting terminal portion 116 on the second main surface 2-2 side are appropriately connected.

  The vibration type gyro sensor 1 generates strain and stress on the support substrate 2 via the control substrate 100 when an impact or the like is applied to the main device. In the present embodiment, as described above, the vibration element 20 is mounted on the vibration element mounting region 13 that is surrounded by the first load buffer groove portion 12 and is in a floating island state, and thus is generated in the support substrate 2 due to an external load. Strain and stress are absorbed by the first load buffer groove 12. Therefore, the first load buffering groove portion 12 performs a kind of damper action to reduce the influence of an external load on the vibration element 20 mounted on the vibration element mounting region 13, and performs a detection operation while the vibration element 20 is stable. Like that.

  On the other hand, in the vibration type gyro sensor 1, the mounting terminal portion 116 provided in the terminal formation region 115 in which the second load buffering groove portion 14 is provided and is in a floating island state as described above constitutes a fixing portion to the control board 100. . In the present embodiment, the external load transmitted through the control board 100 is absorbed by the second load buffer groove 14. Therefore, the second load buffering groove portion 14 performs a kind of damper action to reduce the influence of an external load on the vibration element 20 mounted on the vibration element mounting region 13, and performs the detection operation in a stable state of the vibration element 20. Like that.

  In addition, although the 1st load buffering groove part 12 is comprised by the groove part of the cross-sectional U shape continuous over the perimeter, it is not limited to this. The first load buffering groove 12 may be configured by arranging, for example, a large number of grooves as a whole on the condition that predetermined characteristics are satisfied. Further, the second load buffering groove portion 14 does not need to be configured by a continuous groove portion, and may be configured by arranging a plurality of groove portions, for example. Further, the first load buffering groove 12 is formed on the first main surface 2-1 of the support substrate 2 and the second load buffering groove 14 is formed on the second main surface 2-2 to provide a load buffering structure on the front and back main surfaces. Although configured, the load buffering structure may be configured by only the first load buffering groove 12 or the second load buffering groove 14 on the condition that it has predetermined characteristics.

  As described above, the frame-shaped first load buffer groove 12 surrounding the vibration element mounting region 13 is formed on the first main surface 2-1 of the support substrate 2, and the configuration of the first load buffer groove 12 is the same. It is not limited to. The vibration type gyro sensor 170 shown in FIG. 6 has frame-shaped first load buffering grooves 172X and 172Y formed on the support substrate 171. Furthermore, a cross-shaped partition groove 173A is formed in the first load buffering groove 172. , 173B are formed to constitute four individual mounting regions 174A to 174D.

  That is, in the vibration type gyro sensor 170, each individual mounting region 174 is individually divided corresponding to the terminal portion 25 formed on the base portion 22 of the vibration element 20, and each mounting terminal portion is provided although not shown. ing. In the vibration type gyro sensor 170, the vibration element 20 mounted on the support substrate 171 with the terminal portions 25 fixed to the mounting terminal portions opposed to each other via the gold bumps 26 as a whole is configured as a first load buffer. In the first floating island surrounded by the groove portion 172, each fixed portion is individually fixed and mounted in the second floating island divided by the dividing groove 173. Therefore, in the vibration type gyro sensor 170, the vibration element 20 can more reliably reduce the influence of distortion and stress of the support substrate 171 generated by an external load, and perform a stable angular velocity detection operation.

[Distance concavity]
Next, in the support substrate 2, recesses 11 </ b> A and 11 </ b> B (hereinafter referred to as individual parts) that constitute a space part that freely vibrates the vibrator part 23 in the thickness direction in the component mounting region 6 corresponding to the vibration elements 20 </ b> X and 20 </ b> Y. Except for the case described in (1), it is generically referred to as an interval constituting concave portion 11). The space | interval structure recessed part 11 is formed in the shape of a rectangular bottomed groove | channel which has a predetermined | prescribed depth and opening dimension by giving an etching process and a grooving process with respect to the 1st main surface 2-1 of the support substrate 2, for example.

  In the vibration type gyro sensor 1, the vibration element 20 in which the base portion 22 and the cantilever-like vibrator portion 23 are integrally formed is formed on the first main surface 2-1 of the support substrate 2 via the gold bump 26. Implemented. The vibration element 20 is designed to be thin as a whole because the opposing distance between the vibrator portion 23 and the first main surface 2-1 of the support substrate 2 is defined by the thickness of the gold bump 26. There may be a case where a sufficient interval cannot be maintained due to the processing limit.

  The vibration element 20 generates an air flow with the first main surface 2-1 of the support substrate 2 in accordance with the vibration operation of the vibrator unit 23. This air flow strikes the first main surface 2-1 of the support substrate 2 and generates a damping effect that pushes up the vibrator portion 23. In the present embodiment, a sufficient distance m is provided between the support substrate 2 and the vibrator portion 23 as shown in FIG. 2 by forming the interval constituting recess 11 in the first main surface 2-1 of the support substrate 2. And the influence of the damping effect acting on the vibration element 20 is reduced.

  The vibration type gyro sensor 1 is thinned by extending the vibrator portion 23 so as to oppose the spacing component recess portion 11 in a state where the vibration element 20 is mounted on the first main surface 2-1 of the support substrate 2. As shown in FIG. 2, a sufficient interval is maintained between the vibrator portion 23 and the support substrate 2. Thereby, when the vibrator part 23 vibrates in the thickness direction, the action of the damping effect is reduced, and a stable detection operation of the vibration element 20 is ensured.

  The interval constituting recess 11 is formed on the support substrate 2 by being optimized according to the size of the vibrator portion 23 of the vibration element 20. In the present embodiment, when the vibration element 20 is formed with a dimension value to be described later and the maximum amplitude amount of the vibrator unit 23 is p, the opening dimension of the spacing component recess 11 is 2.1 mm × 0.32 mm. The depth dimension k (see FIG. 2) is formed such that k ≧ p / 2 + 0.05 (mm). By forming the gap-constituting recess 11 having the configuration related to the support substrate 2, the height dimension is suppressed and the thickness is reduced, and the influence of the damping effect on the vibration element 20 is reduced and the high Q value is maintained. Thus, it is possible to perform a highly sensitive and stable detection operation such as camera shake.

  Next, details of the configuration of the vibration element 20 will be described.

[Gold bump]
As will be described later, in the vibration element 20, the second main surface (22-2) of the base 22 constituted by the second main surface 21-2 of the silicon substrate 21 constitutes a fixed surface (mounting surface) for the support substrate 2. And mounted on the vibration element mounting region 13 described above. As shown in FIG. 4, the mounting surface 22-2 of the base portion 22 is formed with a first terminal portion 25A to a fourth terminal portion 25D (hereinafter collectively referred to as the terminal portion 25 unless otherwise described). In addition, first gold bumps 26A to 4D gold bumps 26D (hereinafter collectively referred to as gold bumps 26 unless otherwise described) are formed on the terminal portions 25 as metal convex portions, respectively.

  Each terminal portion 25 of the vibration element 20 is formed corresponding to each land 4 formed on the wiring pattern 5 on the support substrate 2 side. Each terminal portion 25 is aligned with the corresponding land 4 and combined with the support substrate 2. In this state, ultrasonic waves are applied while pressing the vibration element 20 against the support substrate 2, and the terminal portions 25 and the lands 4 are welded and bonded via the gold bumps 26. Thereby, the vibration element 20 is mounted on the support substrate 2. Thus, by mounting the vibration element 20 via the gold bumps 26 having a predetermined height, the vibrator portion 23 has its second main surface (substrate facing surface) 23-2 as the first main surface 2 of the support substrate 2. -1 is allowed to perform a predetermined vibration operation while being held at a predetermined height position.

  In the present embodiment, the mounting process is made more efficient by mounting the vibration element 20 on the support substrate 2 by the surface mounting method. The connectors in the surface mounting method are not limited to the gold bumps 26 described above, and various other metal protrusions such as solder balls and copper bumps generally employed in semiconductor processes can also be used. In the present embodiment, reflow soldering or the like is performed in the manufacturing process of the main device, and the mounting terminal portion 116 of the support substrate 2 is connected and fixed to each land of the control substrate 100 via the bump 117. A gold bump 26 having high performance and high workability is employed as a connector.

  In the vibration type gyro sensor, the mechanical quality factor Q (Q factor) is determined by the structure in which the vibration element is fixed to the support substrate. In the present embodiment, the vibration element 20 is mounted in a state where the base portion 22 is floated from the first main surface 2-1 of the support substrate 2 via the gold bumps 26, so that, for example, the entire base portion is interposed via the adhesive layer. Compared with the case where it is bonded to the support substrate, the attenuation rate of the tip of the vibrator portion 23 is increased, and a good Q value is obtained. Further, since the base 22 is fixed to the first main surface 2-1 of the support substrate 2 at one place, a structure with a plurality of places can provide better Q value characteristics, and thus the base 22 is supported. Good Q-value characteristics are obtained by fixing the positions of the four corners with respect to the substrate 2.

Each gold bump 26 can be provided so that the entire center of gravity is located in a region within the range of the width dimension t6 (see FIG. 9) with respect to the central axis in the longitudinal direction of the vibrator portion 23. By disposing the gold bumps 26 in this way, the vibrator unit 23 that vibrates in the thickness direction can be vibrated in a stable state without losing the left-right balance.
Further, by forming each gold bump 26 from the proximal end portion of the transducer portion 23 protruding from the base portion 22 in an outer region of a region having a radius of twice the width dimension t6 of the transducer portion 23, It is possible to maintain the high Q value by reducing the action of absorbing the vibration operation of the vibrator portion 23 by the gold bump 26.
Furthermore, at least one gold bump 26 is formed in a region in a range of twice the thickness dimension t1 of the base portion 22 (see FIG. 8) from the base end portion of the vibrator portion 23. This vibration operation is transmitted to the base 22 to prevent the resonance frequency from shifting.

  The gold bumps 26 may be formed by so-called two-stage bumps. Furthermore, a so-called dummy fifth gold bump may be formed on the second main surface of the base portion 22 so as not to be electrically connected. In this case, of course, a dummy terminal portion to which the fifth gold bump is welded and fixed is formed on the support substrate 2 side.

[Element shape]
Now, as shown in FIG. 8, in the resonator element 20 according to the present embodiment, the vibrator portion 23 forms a second main surface (which is the same surface as the second main surface (mounting surface) 22-2 of the base portion 22). Substrate-facing surface) 23-2, one end of which is integrated with the base 22 and protrudes like a cantilever. As shown in FIG. 2, the vibrator portion 23 has a predetermined thickness by being stepped down from the first main surface (upper surface) 22-1 of the base portion 22 as shown in FIG. The vibrator portion 23 is constituted by a cantilever beam having a rectangular section and having a predetermined length and a cross-sectional area and formed integrally with one peripheral portion of the base portion 22.

  As shown in FIG. 8, the base portion 22 of the vibration element 20 is formed with a thickness dimension t1 of 300 μm, a length dimension t2 to the tip of the vibrator section 23 of 3 mm, and a width dimension t3 of 1 mm. As shown in FIG. 9, the vibrator portion 23 of the vibration element 20 is formed with a thickness dimension t4 of 100 μm, a length dimension t5 of 2.5 mm, and a width dimension t6 of 100 μm. As will be described in detail later, the vibration element 20 vibrates with a drive voltage of a predetermined frequency applied from the drive detection circuit unit 50, but vibrates at a resonance frequency of 40 kHz from the above-described shape. In addition, the vibration element 20 is not limited to such a configuration, and variously set according to the frequency to be used and the target overall shape.

  In addition, each part of the base part 22 and the vibrator part 23 can satisfy the following conditions to form the vibration element 20. That is, the base portion 22 has a width dimension t3 larger than twice the width dimension t6 of the vibrator portion 23 and the center of gravity position of the vibrator portion 23 with respect to the longitudinal center axis of the vibrator portion 23. It is formed in a region twice as large as the width dimension t6 of the portion 23. With this configuration, the vibrator unit 23 can be vibrated in a good state without breaking the left-right balance. Further, by forming the thickness dimension t1 of the base portion 22 to be 1.5 times the thickness dimension t4 of the vibrator portion 23, the mechanical strength of the base portion 22 is maintained, and the vibration operation is generated by the vibration operation of the vibrator portion 23. The resonance frequency can be prevented from being shifted.

[Piezoelectric film and various electrode layers]
As shown in FIG. 4, the vibration element 20 is formed on the second main surface (substrate facing surface) 23-2 of the vibrator portion 23 over the substantially entire length in the length direction by a vibration element manufacturing process described later. An electrode layer (first electrode layer) 27, a piezoelectric thin film layer 28, and a drive electrode layer (second electrode layer) 29 are laminated. On the second main surface (substrate facing surface) 23-2 of the vibrator portion 23, a pair of detection electrodes 30R, 30L (hereinafter, unless otherwise described) with the drive electrode layer 29 interposed therebetween. The drive electrode layer 29 and the detection electrode 30 constitute a second electrode layer.

  A reference electrode layer 27 is formed as a first layer on the second main surface (substrate facing surface) 23-2 of the vibrator unit 23, and a piezoelectric thin film layer 28 having substantially the same length is laminated on the reference electrode layer 27. Is done. On the piezoelectric thin film layer 28, a drive electrode layer 29 having substantially the same length and narrow width is laminated and formed at the center in the width direction, and the piezoelectric thin film layer 28 is sandwiched between the drive electrode layers 29. A pair of detection electrodes 30R and 30L are stacked on top of each other.

[Lead / Terminal]
As shown in FIG. 4, the vibration element 20 has a first lead 31 </ b> A that connects the reference electrode layer 27 and the first terminal portion 25 </ b> A on the second main surface (mounting surface) 22-2 of the base portion 22. In addition, a third lead 31C that connects the drive electrode layer 29 and the third terminal portion 25C is formed. Similarly, on the mounting surface 22-2 of the base portion 22, a second lead 31B that connects the first detection electrode 30R and the second terminal portion 25B is formed, and the second detection electrode 30L and the fourth terminal portion are formed. A fourth lead 31D for connecting to 25D is formed. The leads 31A to 31D are hereinafter collectively referred to as leads 31 except when individually described.

  The first lead 31A is integrally extended from the base end portion of the reference electrode layer 27 formed on the vibrator portion 23 to the base portion 22 side, and the second main surface (mounting surface) 22− of the base portion 22 as shown in FIG. 2 is integrated with the first terminal portion 25A formed at one corner portion on the side where the vibrator portion 23 is integrally formed. The drive electrode layer 29 and the detection electrode 30 have their base ends integrally extended from the vibrator portion 23 to the base portion 22 by a slightly wide portion, and these wide portions are covered with the planarizing layer 24.

  The second lead 31B is formed so that one end portion thereof passes over the planarization layer 24, and is guided along the one side portion of the base portion 22 to the rear corner portion facing the first terminal portion 25A. The second terminal portion 25B formed at the corner portion is connected. The third lead 31C is formed so that one end thereof gets over the flattening layer 24, is guided to the rear side across the substantially central portion of the base portion 22, and faces the second terminal portion 25B along the rear end side. By being led to the corner portion to be connected, it is connected to the third terminal portion 25C formed at this corner portion. The fourth lead 31D is also formed so that one end thereof gets over the planarization layer 24, and is guided along the other side portion of the base portion 22 to the other corner portion on the front side facing the third terminal portion 25C. The fourth terminal portion 25D formed at the corner portion is connected.

  Regardless of the configuration described above, the vibration element 20 is formed at an appropriate position and with an appropriate number of terminals 25 on the second main surface (mounting surface) 22-2 of the base portion 22. The In addition, in the vibration element 20, the connection pattern between the lead 31 of each electrode layer and the terminal portion 25 is not limited to the configuration described above, and the base portion 22 depends on the position and number of the terminal portions 25. The second main surface is appropriately formed.

[Insulation protective layer]
As shown in FIGS. 2 and 4, the vibration element 20 includes an insulating protective layer 45 that covers the base portion 22 and the vibrator portion 23 on the second main surface 21-2 side. The insulating protective layer 45 includes a first alumina (aluminum oxide: Al ₂ O ₃ ) layer 46, a second silicon oxide (SiO ₂ ) layer 47, and a third second alumina layer 48. It is comprised by the 3 layer structure which consists of.

  As shown in FIG. 2, terminal openings 49 are formed in the insulating protective layer 45 corresponding to the formation regions of the terminal portions 25, and the terminal portions 25 are externally connected through the terminal openings 49. I face you. As shown in FIG. 2, the vibration element 20 has gold bumps 26 formed on the terminal portions 25 so as to protrude from the terminal openings 49.

  As shown in FIG. 4, the insulating protective layer 45 is formed between the outer peripheral edge of each of the base portion 22 and the vibrator portion 23 and the outermost peripheral portion of the reference electrode layer 27 and the terminal portion 25. The surface 21-2 is formed to be exposed in a frame shape. The insulating protective layer 45 is prevented from being peeled off from the outer peripheral part during the cutting-out process of the vibration element 20 described later by leaving the exposed part of the second main surface 21-2 at the outer peripheral part. The insulating protective layer 45 is formed with a width dimension of, for example, 98 μm in the vibrator portion 23 having a width dimension t6 of 100 μm.

  The insulating protective layer 45 is formed by the first alumina layer 46 having a thickness dimension of, for example, 50 nm. The first alumina layer 46 acts as a base adhesion layer that improves adhesion to the main surface of the base 22 and the vibrator part 23, and the insulating protective layer 45 is firmly formed on the vibrator part 23 that vibrates. In this way, the occurrence of peeling or the like is prevented.

  The silicon oxide layer 47 blocks moisture and the like in the air to prevent adhesion to each electrode layer, etc., suppresses oxidation of each electrode layer, electrically insulates each electrode layer, or each electrode layer of a thin film or piezoelectric thin film The layer 28 has a function for mechanical protection. The uppermost second alumina layer 48 has an effect of improving the adhesion with a resist layer formed when the vibrator portion 23 is formed by performing an outer shape groove forming process described later on the silicon substrate 21, and an etching agent. This prevents the silicon oxide layer 47 from being damaged.

  The silicon oxide layer 47 is at least twice as thick as the second electrode layer 42 and has a thickness of 1 μm or less. The silicon oxide layer 47 is formed on the first alumina layer 46 by sputtering in an argon gas atmosphere of 0.4 Pa or less. The insulation protection layer 45 has a sufficient insulation protection function and prevents generation of burrs during film formation by setting the silicon oxide layer 47 to the above-described film thickness. Further, the silicon oxide layer 47 is formed at a high film density by forming the film under the above-described sputtering conditions.

[Alignment mark]
In the vibration type gyro sensor 1, the support substrate 2 determines the position of each land 4 in order to precisely position and mount the first vibration element 20 </ b> X and the second vibration element 20 </ b> Y having the same shape with respect to the support substrate 2. Recognized by the mounting machine. In order to be positioned and mounted on each land 4 recognized by the mounting machine, the vibration element 20 is positioned on the first main surface (upper surface) 22-1 of the base portion 22A. 32B (hereinafter collectively referred to as the alignment mark 32) is provided.

  As shown in FIGS. 1 and 4, the alignment mark 32 is a pair of rectangular portions made of metal foil or the like formed on the first main surface (upper surface) 22-1 of the base portion 22 so as to be separated in the width direction. Consists of. After the alignment mark 32 is read by the mounting machine and the mounting data of the position and orientation with respect to the support substrate 2 is generated, the vibration element 20 is based on the mounting data and the land 4 data described above. 2 is precisely positioned and mounted.

  The vibration element 20 has the alignment mark 32 formed on the first main surface of the base 22, but is not limited to this configuration. The alignment mark 32 is formed on the second main surface (mounting surface) 22-2 of the base portion 22 with an alignment mark made of a conductor portion in the same process as the wiring process, for example, by avoiding the terminal portion 25 and the lead 31. You may make it form in a position. The alignment mark 32 is a reference marker used in the reactive ion etching process by the inductively coupled plasma apparatus used in the outer groove forming process for forming the electrode layer of the vibration element 20 and the vibrator portion 23 as will be described in detail later. It is preferable to be positioned and formed according to the above. The alignment mark 32 can be formed with an accuracy of 0.1 μm or less with respect to the vibrator portion 23 by using a stepper exposure apparatus.

  The alignment mark 32 is formed by an appropriate method. For example, when the second main surface (mounting surface) 22-2 of the base portion 22 is formed by patterning the first electrode layer 40 made of a titanium layer and a platinum layer as will be described later, reading is performed during the mounting process. When processing is performed, a good contrast is obtained, and the mounting accuracy is improved.

[cover]
Next, details of the cover 15 that shields the first main surface 2-1 of the support substrate 2 from the outside will be described.

  The vibration-type gyro sensor 1 detects the displacement of the vibration element 20 due to Coriolis force generated by hand shake or the like by a piezoelectric thin film layer 28 formed on the vibration element 20 and a detection electrode 30 as will be described in detail later, and generates a detection signal. Output. When the piezoelectric thin film layer 28 is irradiated with light, a voltage is generated due to the pyroelectric effect, and this pyroelectric voltage affects the detection operation and the detection characteristics are deteriorated.

  In the vibration type gyro sensor 1, the component mounting space 3 is shielded from light by the support substrate 2 and the cover member 15, and the characteristic deterioration due to the influence of external light is prevented. As shown in FIG. 1, the support substrate 2 has a light shielding step portion formed of a vertical wall with the outer peripheral portion being stepped down from the first main surface 2-1 so as to rim the component mounting region 6. The cover fixing | fixed part 10 is formed by comprising 9. As shown in FIG. Then, the cover member 15 formed of a thin metal plate is bonded to the support substrate 2 over the entire periphery of the cover fixing portion 10 by resin adhesion, so that the component mounting space portion 3 is hermetically sealed to prevent dust and moisture. In addition, it is configured as a light shielding space.

  As shown in FIG. 1, the cover member 15 has a main surface portion 16 having an outer dimension sufficient to cover the component mounting region 6 of the support substrate 2, and is bent integrally around the outer periphery of the main surface portion 16 over the entire periphery. The entire outer peripheral wall portion 17 is formed in a box shape. The cover member 15 is formed with a height dimension that constitutes the component mounting space portion 3 in which the vibrator portion 23 of the vibration element 20 can perform a vibration operation in a state where the outer peripheral wall portion 17 is assembled to the support substrate 2. Yes. In the cover member 15, an outer peripheral flange portion 18 having a slightly smaller width than the cover fixing portion 10 formed on the support substrate 2 is integrally bent at the opening edge of the outer peripheral wall portion 17 over the entire periphery. . Although not shown, the outer peripheral flange portion 18 forms a ground projection, and is connected to the ground terminal on the control board 100 when the vibration type gyro sensor 1 is mounted on the control board 100.

  The cover member 15 is formed of a thin metal plate to keep the vibration-type gyro sensor 1 small and light. However, the cover member 15 does not exhibit a sufficient light blocking function due to a decrease in light blocking performance with respect to external light having an infrared wavelength. Sometimes. Therefore, in the present embodiment, the entire surface of the main surface portion 16 and the outer peripheral wall portion 17 is coated with, for example, an infrared absorbing paint that absorbs light of an infrared wavelength to form the light shielding layer 19, so that the component mounting space portion 3 is filled. The vibration element 20 performs a stable operation by shielding the radiation of external light having an infrared wavelength. The light shielding layer 19 may be formed by dipping in an infrared absorbing coating solution to form the front and back main surfaces, or by performing black chrome plating treatment, black dyeing treatment or black anodizing treatment.

  As described above, in the vibration type gyro sensor 1, the cover member 15 is assembled to the support substrate 2 by superimposing the outer peripheral flange portion 18 on the cover fixing portion 10 and joining with the adhesive to seal the support substrate 2. And the component mounting space part 3 shielded from light is constituted. However, external light may enter the component mounting space 3 through the adhesive layer interposed in the gap between the cover fixing portion 10 and the outer peripheral flange portion 18 that are overlapped. Therefore, in the present embodiment, as described above, the support substrate 2 is formed by stepping the cover fixing portion 10 with respect to the main surface 2-1 through the light shielding step portion 9, so that the outside that has passed through the adhesive layer is transmitted. The light is shielded by the light shielding step 9.

  In the present embodiment, the assembly process is rationalized by assembling the cover member 15 to the support substrate 2 by the surface mounting method in the same manner as other components. In the vibration type gyro sensor 1, the cover member 15 is fixed on the cover fixing portion 10 that has been stepped down on the support substrate 2, so that the thickness can be reduced and the adhesive can be prevented from flowing into the component mounting region 6. The In addition, since the component mounting space 3 is configured as a dustproof and moistureproof space and as a light-shielding space, the generation of pyroelectric effect in the vibration element 20 is suppressed, and a stable motion detection operation is performed. Make it possible.

[Circuit configuration]
Next, a circuit configuration for driving the vibration gyro sensor 1 will be described with reference to FIG.

  The vibration type gyro sensor 1 includes a first drive detection circuit unit 50X and a second drive detection circuit unit which are connected to the first vibration element 20X and the second vibration element 20Y, respectively, and are configured by the IC circuit element 7, the electronic component 8, and the like. 50Y. Since the first drive detection circuit unit 50X and the second drive detection circuit unit 50Y have the same circuit configuration, the drive detection circuit unit 50 will be collectively described below. The drive detection circuit unit 50 includes an impedance conversion circuit 51, an addition circuit 52, an oscillation circuit 53, a differential amplification circuit 54, a synchronous detection circuit 55, a DC amplification circuit 56, and the like.

  In the drive detection circuit unit 50, as shown in FIG. 7, an impedance conversion circuit 51 and a differential amplifier circuit 54 are connected to the first detection electrode 30R and the second detection electrode 30L of the vibration element 20. An adder circuit 52 is connected to the impedance conversion circuit 51, and an oscillation circuit 53 connected to the adder circuit 52 is connected to the drive electrode layer 29. A synchronous detection circuit 55 is connected to the differential amplifier circuit 54 and the oscillation circuit 53, and a DC amplifier circuit 56 is connected to the synchronous detection circuit 55. The reference electrode layer 27 of the vibration element 20 is connected to the reference potential 57 on the support substrate 2 side.

  In the drive detection circuit unit 50, the vibration element 20, the impedance conversion circuit 51, the addition circuit 52, and the oscillation circuit 53 constitute a self-excited oscillation circuit. Then, by applying an oscillation output Vgo having a predetermined frequency from the oscillation circuit 53 to the drive electrode layer 29, natural vibration is generated in the vibrator unit 23 of the vibration element 20. The output Vgr from the first detection electrode 30R and the output Vgl from the second detection electrode 30L of the vibration element 20 are supplied to the impedance conversion circuit 51. Based on these inputs, the impedance conversion circuit 51 outputs the addition circuit 52 to the addition circuit 52. Outputs Vzr and Vzl are output respectively. The adder circuit 52 outputs an addition output Vsa to the oscillation circuit 53 based on these inputs.

  The output Vgr from the first detection electrode 30R and the output Vgl from the second detection electrode 30L of the vibration element 20 are supplied to the differential amplifier circuit 54. As described later, when the vibration element 20 detects hand shake, the drive detection circuit unit 50 generates a difference between the output Vgr and the output Vgl, so that a predetermined output Vda is obtained by the differential amplifier circuit 54. The output Vda from the differential amplifier circuit 54 is supplied to the synchronous detection circuit 55. The synchronous detection circuit 55 performs synchronous detection on the output Vda to convert it to a DC signal Vsd, supplies it to the DC amplification circuit 56, and outputs a DC signal Vsd subjected to predetermined DC amplification.

  The synchronous detection circuit 55 performs full-wave rectification on the output Vda of the differential amplifier circuit 54 at the timing of the clock signal Vck output in synchronization with the drive signal from the oscillation circuit 53 and then integrates to obtain a DC signal Vsd. As described above, the drive detection circuit unit 50 amplifies the DC signal Vsd in the DC amplifier circuit 56 and outputs the amplified signal, thereby detecting an angular velocity signal caused by camera shake.

  The drive detection circuit unit 50 is configured to obtain a low impedance output Z3 when the impedance conversion circuit 51 is in the high impedance input Z2, and adds the impedance Z1 between the first detection electrode 30R and the second detection electrode 30L. There exists an effect | action which isolate | separates impedance Z4 between the inputs of the circuit 52. FIG. By providing the impedance conversion circuit 51, a large output difference can be obtained from the first detection electrode 30R and the second detection electrode 30L.

  In the drive detection circuit unit 50, the above-described impedance conversion circuit 51 only performs an impedance conversion function between input and output, and does not affect the signal magnitude. Therefore, the output Vgr from the first detection electrode 30R and the output Vzr on one side of the impedance conversion circuit 51, and the output Vgl from the second detection electrode 30L and the output Vzl on the other side of the impedance conversion circuit 51 are the same. That's it. In the drive detection circuit unit 50, even if there is a difference between the output Vgr from the first detection electrode 30 </ b> R and the output Vgl from the second detection electrode 30 </ b> L due to hand vibration detection by the vibration element 20, It is held at the output Vsa.

  In the drive detection circuit unit 50, the noise component superimposed on the output Vgo of the oscillation circuit 53 is equivalent to the band filter in the vibration element 20, even if noise is superimposed due to, for example, a switching operation or the like. By removing components other than those, it is possible to obtain a highly accurate output Vda from which noise components have been removed from the differential amplifier circuit 54. The vibration-type gyro sensor 1 is not limited to the drive detection circuit unit 50 described above, and the displacement due to the hand movement of the vibrator unit 23 that vibrates naturally is detected by the piezoelectric thin film layer 28 and the pair of detection electrodes 30. The detection output may be obtained by performing an appropriate process.

  As described above, the vibration type gyro sensor 1 includes the first vibration element 20X that detects the angular velocity in the X-axis direction and the second vibration element 20Y that detects the angular velocity in the Y-axis direction. A detection output VsdX in the X-axis direction is obtained from the first drive detection circuit unit 50X connected to the first vibration element 20X, and a Y-axis is output from the second drive detection circuit unit 50Y connected to the second vibration element 20Y. A direction detection output VsdY is obtained. In the vibration type gyro sensor 1, the first vibration element 20X and the second vibration element 20Y can set operating frequencies in the range of several kHz to several hundred kHz, respectively. Then, by setting the frequency difference (fx−fy) between the operating frequency fx of the first vibrating element 20X and the operating frequency fy of the second vibrating element 20Y to 1 kHz or more, crosstalk is reduced and precise vibration detection is performed. Will come to be.

  If necessary, the drive detection circuit unit 50 selectively amplifies the detection signals of the operating frequencies fx and fy of the vibration elements 20X and 20Y included in the output of the adder circuit 52 and supplies the detection signals to the oscillation circuit 53. A filter amplifier circuit is provided.

[Manufacturing method of vibration type gyro sensor]
Hereinafter, a manufacturing method of the vibration type gyro sensor 1 of the present embodiment will be described. FIG. 10 is a main process flow diagram illustrating a method for manufacturing the vibration gyro sensor 1.

  In the vibration type gyro sensor 1, the vibration element 20 described above includes, for example, as shown in FIGS. 11 and 12, the azimuth plane of the main surface 21-1 is the (100) plane and the azimuth plane of the side surface 21-3 is (110). ) After a large number of silicon substrates 21 cut out to form a surface are formed as a base material, they are cut into pieces one after another through a cutting process.

[Board preparation process]
The outer dimensions of the silicon substrate 21 are appropriately determined according to the equipment specifications used in the process, and are, for example, 300 × 300 (mm). As shown in FIG. 11, the silicon substrate 21 is not limited to a rectangular substrate in plan view, and may be a wafer having a circular shape in plan view. The thickness dimension of the silicon substrate 21 is determined depending on workability, cost, and the like, but may be a thickness that is at least larger than the thickness dimension of the base portion 22 of the vibration element 20. As described above, since the thickness of the base portion 22 is 300 μm and the thickness of the vibrator portion 23 is 100 μm, the silicon substrate 21 is a substrate having a thickness of 300 μm or more.

  The silicon substrate 21 is subjected to a thermal oxidation process, and as shown in FIG. 12, silicon oxide films (SiO 2 films) 33A and 33B (on the first main surface 21-1 and the second main surface 21-2, respectively). Hereinafter, the silicon oxide film 33 is generically formed unless otherwise described). As will be described later, the silicon oxide film 33 functions as a protective film when the silicon substrate 21 is subjected to crystal anisotropic etching. The silicon oxide film 33 may be formed with an appropriate thickness as long as it has a protective film function. For example, the silicon oxide film 33 is formed with a thickness of about 0.3 μm.

[Etching recess forming step]
The vibration element manufacturing process includes the same process as the thin film process of the semiconductor process, and a portion where the vibrator portion 23 of each vibration element 20 is formed from the first main surface 21-1 side of the silicon substrate 21 has a predetermined thickness dimension. An etching recess forming step for forming the above-described etching recess 37 is provided.

  As shown in FIGS. 13 to 19, the etching recess forming process includes a photoresist layer forming process for forming a photoresist layer 34 on the first main surface 21-1 of the silicon substrate 21, and an etching recess 37 forming site. Correspondingly, a photoresist patterning step of forming a photoresist layer opening 35 in the photoresist layer 34, and a first step of removing the silicon oxide film 33A facing the photoresist layer opening 35 to form a silicon oxide film opening 36. An etching process, a second etching process for forming an etching recess 37 in the silicon oxide film opening 36, and the like.

  In the photoresist layer forming step, a photoresist material is applied over the entire surface of the silicon oxide film 33 </ b> A formed on the first main surface 21-1 of the silicon substrate 21 to form the photoresist layer 34. In the photoresist layer forming step, for example, a photosensitive photoresist material “OFPR-8600” manufactured by Tokyo Ohka Co., Ltd. is used as a photoresist material. After applying this photoresist material, it is heated by microwaves to remove moisture. A baking process is performed to form a photoresist layer 34 on the silicon oxide film 33A.

  In the photoresist patterning step, a masking process is performed with the portion where each silicon oxide film opening 36 is formed on the photoresist layer 34 as an opening, and the photoresist layer 34 is exposed and developed. In the photoresist patterning step, the photoresist layer 34 corresponding to each silicon oxide film opening 36 is removed, and a plurality of photoresists are exposed so that the silicon oxide film 33A faces outward as shown in FIGS. The layer opening 35 is formed collectively. In addition, as shown in FIG. 13, 3 × 5 photoresist layer openings 35 are formed in the silicon substrate 21, so that fifteen vibration elements 20 are manufactured collectively through the following steps. So that

  The first etching process is a process of removing the silicon oxide film 33A facing the outside through the photoresist layer opening 35. The first etching process employs a wet etching method in which only the silicon oxide film 33A is removed in order to maintain the smoothness of the interface of the silicon substrate 21, but is not limited to this method. For example, an ion etching method or the like is used. The appropriate etching process may be used.

  In the first etching process, for example, an ammonium fluoride solution is used as an etchant, and the silicon oxide film 33A is removed to form a silicon oxide film opening 36. Thereby, as shown in FIG.15 and FIG.16, the 1st main surface 21-1 of the silicon substrate 21 is made to face outside. In the first etching process, when etching is performed for a long time, a so-called side etching phenomenon occurs in which the etching proceeds from the side surface of the silicon oxide film opening 36, and therefore, when the silicon oxide film 33A is etched. It is preferable to accurately manage the etching time so that the process ends.

  The second etching process is a step of forming an etching recess 37 in the first main surface 21-1 of the silicon substrate 21 facing the outside through the silicon oxide film opening 36. In the second etching process, the silicon substrate 21 is etched to the thickness of the vibrator portion 23 by a wet etching process with crystal anisotropy utilizing the property that the etching rate depends on the crystal direction of the silicon substrate 21.

  In the second etching process, for example, TMAH (tetramethylammonium hydroxide), KOH (potassium hydroxide) or EDP (ethylenediamine-pyrocatechol-water) solution is used as an etching solution. Specifically, in the second etching process, a TMAH 20% solution that increases the etching rate selectivity of the silicon oxide films 33A and 33B on the front and back surfaces is used as an etchant, and the temperature is raised to 80 ° C. while stirring the etchant. Then, etching is performed for 6 hours to form an etching recess 37 shown in FIGS.

  In the second etching treatment step, utilizing the property of the etching resistance of the side surface 21-3 to the first main surface 21-1 and the second main surface 21-2 of the silicon substrate 21 used as the base material is small, Etching is performed in which the (110) plane appears in a plane orientation of an angle of about 55 ° with respect to the (100) plane. As a result, the opening size gradually decreases with an inclination angle of about 55 ° from the opening toward the bottom surface, and an etching recess 37 having an etching slope 133 with an inclination angle of about 55 ° is formed on the inner peripheral wall.

  The etching concave portion 37 constitutes a diaphragm portion 38 that forms the vibrator portion 23 by being subjected to an outer shape cutting step described later. The etching recess 37 has an opening dimension of a length dimension t8 and a width dimension t9 as shown in FIG. 17, and is formed with a depth dimension t10 as shown in FIG. As shown in FIG. 19, the etching concave portion 37 is configured by a trapezoidal space section whose opening dimension gradually decreases from the first main surface 21-1 toward the second main surface 21-2 side.

  As described above, the etching recess 37 is formed with an inclination angle θ of 55 ° inwardly descending the inner peripheral wall. As will be described later, the diaphragm portion 38 has a width dimension t6 and a length dimension t5 of the vibrator portion 23 and a width dimension t7 of the outer groove 39 formed in the silicon substrate 21 by cutting out the outer peripheral portion thereof (see FIGS. 36 and 36). 37). The width dimension t7 of the outer groove 39 is obtained by (depth dimension t10 × 1 / tan 55 °).

  Therefore, the etching recess 37 has an opening width dimension t9 that defines the width of the diaphragm section 38, (depth dimension t10 × 1 / tan 55 °) × 2 + t6 (width dimension of the transducer section 23) + 2 × t7 (outer groove 39 Width dimension). When the width t9 of the opening portion of the etching recess 37 is t10 = 200 μm, t6 = 100 μm, and t7 = 200 μm, t9 = 780 μm.

  Moreover, the etching recessed part 37 is comprised as an inclined surface whose inclination | tilt angle is each 55 degrees similarly to the width direction also about the length direction by performing the 2nd etching process mentioned above. Therefore, the etching recess 37 has a length dimension t8 that defines the length of the diaphragm part 38: (depth dimension t10 × 1 / tan 55 °) × 2 + t5 (length dimension of the transducer part 23) + t7 (outer groove 39 Width dimension). When the length t8 of the etching recess 37 is t10 = 200 μm, t5 = 2.5 mm, and t7 = 200 μm, t8 = 2980 μm.

[Electrode formation process (film formation)]
By the etching recess forming step described above, a rectangular diaphragm portion 38 having a predetermined thickness is formed on the silicon substrate 21 between the bottom surface of the etching recess 37 and the second main surface 21-2. The diaphragm part 38 constitutes the vibrator part 23 of the vibration element 20. After the etching recess forming step, an electrode forming step is performed with the second main surface 21-2 side of the diaphragm portion 38 as a processed surface.

  In the electrode formation step, each electrode layer is formed on the second main surface 21-2 facing the formation portion of the etching recess 37 by, for example, a magnetron sputtering apparatus via the silicon oxide film 33B. As shown in FIG. 20, the electrode forming step includes a first electrode layer forming step for forming the first electrode layer 40 constituting the reference electrode layer 27 via the silicon oxide film 33B, and a piezoelectric film constituting the piezoelectric thin film layer 28. A piezoelectric film layer forming step for forming the layer 41; and a second electrode layer forming step for forming the second electrode layer 42 constituting the drive electrode layer 29 and the detection electrode 30.

  In the vibration element manufacturing process, each lead 31 and terminal part 25 is formed on the formation part of the base 22 in accordance with the above-described formation process of the first electrode layer 40 and the formation process of the second electrode layer 42 with respect to the vibrator part 23. The step of forming a conductor layer for forming the film is also performed at the same time.

  As shown in FIG. 20, the first electrode layer forming step includes a step of forming a titanium thin film layer by sputtering titanium over the entire surface of the silicon oxide film 33B corresponding to the constituent portion of the vibrator portion 23. The method includes a step of forming a platinum layer by sputtering platinum (platinum) on the titanium thin film layer to form a first electrode layer 40 having a two-layer structure. In the titanium thin film layer forming step, for example, a titanium thin film layer having a thickness of 50 nm or less (for example, 5 nm to 20 nm) is formed on the silicon oxide film 33B under sputtering conditions of a gas pressure of 0.5 Pa and an RF (high frequency) power of 1 kW. In the platinum layer forming step, for example, a platinum thin film layer having a thickness of about 200 nm is formed on the titanium thin film layer under sputtering conditions of a gas thickness of 0.5 Pa and an RF power of 0.5 kW.

  As for the 1st electrode layer 40, while a titanium thin film layer has an effect | action which improves the adhesiveness with the silicon oxide film 33B, a platinum layer acts as a favorable electrode. In the first electrode layer forming step, the conductor layer constituting the first lead 31A and the first terminal portion 25A is also formed by extending from the diaphragm portion 38 to the formation region of the base portion 22 simultaneously with the formation of the first electrode layer 40 described above. Form.

In the piezoelectric film layer forming step, a piezoelectric film layer 41 having a predetermined thickness is formed by sputtering, for example, lead zirconate titanate (PZT) over the entire surface of the first electrode layer 40 described above. The piezoelectric film layer forming step uses the Pb _{(1 + x)} (Zr _0.53 Ti _0.47 ) O _3-y oxide as a target, for example, the first electrode under sputtering conditions of a gas pressure of 0.7 Pa and an RF power of 0.5 kW. A piezoelectric film layer 41 made of a PZT layer having a thickness of about 1 μm is stacked on the layer 40. In the piezoelectric film layer forming step, a crystallization heat treatment is performed by baking the piezoelectric film layer 41 with an electric furnace. For example, the baking process is performed in an oxygen atmosphere at 700 ° C. for 10 minutes. The piezoelectric film layer 41 is formed so as to cover a part of the electrode layer formed in the formation region of the base portion 22 extended from the first electrode layer 40 described above.

  In the second electrode layer forming step, the second electrode layer 42 is formed by laminating platinum over the entire surface of the piezoelectric film layer 41 to form a platinum layer by sputtering platinum. In the second electrode layer forming step, a platinum thin film layer having a thickness of about 200 nm is formed on the piezoelectric film layer 41 under sputtering conditions of a gas pressure of 0.5 Pa and an RF power of 0.5 kW.

[Electrode formation process (patterning)]
Next, a second electrode layer patterning step is performed in which a patterning process is performed on the second electrode layer 42 formed as the uppermost layer. In the second electrode layer patterning step, as shown in FIGS. 21 and 22, a drive electrode layer 29 having a predetermined shape and a pair of detection electrodes 30R and 30L are formed.

  The drive electrode layer 29 is an electrode to which a predetermined drive voltage for driving the vibrator portion 23 is applied as described above, and has a predetermined width in the central region in the width direction of the vibrator portion 23 and almost the entire region in the length direction. It is formed over. The detection electrode 30 is an electrode for detecting the Coriolis force generated in the vibrator unit 23 and is formed on the both sides of the drive electrode layer 29 so as to be insulated from each other over almost the entire length direction in parallel. The

  In the second electrode layer patterning step, the drive electrode layer 29 and the detection electrode 30 are formed on the piezoelectric film layer 41 as shown in FIG. In the second electrode layer patterning step, a resist layer is formed at the corresponding portion of the drive electrode layer 29 and the detection electrode 30, and the resist layer is removed after removing the unnecessary second electrode layer 42 by, for example, ion etching. The drive electrode layer 29 and the detection electrode 30 are pattern-formed through the process of performing such as. The second electrode layer patterning step is not limited to this step, and the drive electrode layer 29 and the detection electrode 30 may be formed using an appropriate conductive layer forming step employed in the semiconductor process. Of course.

  As shown in FIG. 21, the drive electrode layer 29 and the detection electrode 30 are formed so as to be the same at the root portion 43 as the root of the vibrator portion 23 together with the tip portion. In the second electrode layer patterning step, lead connection portions 29-1, 30R-1, and 30L- that are widened at the base end portions of the drive electrode layer 29 and the detection electrode 30 that are matched at the root portion 43, respectively. 1 is integrally patterned.

  In the second electrode layer patterning step, the second electrode layer 42 is patterned to form, for example, the drive electrode layer 29 having a length dimension t12 of 2 mm and a width dimension t13 of 50 μm. Then, as shown in FIG. 21, the first detection electrode 30R and the second detection electrode 30L each having a width dimension t14 of 10 μm are pattern-formed with an interval dimension t15 of 5 μm with the drive electrode layer 29 interposed therebetween. In the second electrode layer patterning step, the lead connection portions 29-1, 30R-1, and 30L-1 having a length dimension of 50 μm and a width dimension of 50 μm are pattern-formed. The drive electrode layer 29 and the detection electrode 30 are not limited to the above-described dimension values, and are appropriately formed as long as they can be formed on the second main surface of the vibrator portion 23.

  Subsequently, the piezoelectric thin film layer 28 having a predetermined shape shown in FIGS. 23 and 24 is formed by a piezoelectric film layer patterning process in which the above-described piezoelectric film layer 41 is patterned. The piezoelectric thin film layer 28 is formed by performing a patterning process on the piezoelectric film layer 41 so as to leave a portion having a larger area than the drive electrode layer 29 and the detection electrode 30 described above. The piezoelectric thin film layer 28 is slightly smaller than the width of the vibrator portion 23 and is formed from the proximal end portion to the vicinity of the distal end portion.

  In the piezoelectric film layer patterning process, a photolithography process is performed on the piezoelectric film layer 41 to form a resist layer at a corresponding portion of the piezoelectric thin film layer 28, and the piezoelectric film layer 41 at an unnecessary portion is made of, for example, a hydrofluoric acid solution. After removal by a wet etching method or the like, the piezoelectric thin film layer 28 shown in FIGS. 23 and 24 is formed through a process such as removing the resist layer. In the above example, the piezoelectric film layer 41 is etched by the wet etching method. However, the present invention is not limited to such a method, and for example, an ion etching method or a reactive ion etching method (RIE: Reactive Ion Etching). Of course, the piezoelectric thin film layer 28 may be formed by applying an appropriate method such as).

  In the piezoelectric film layer patterning step, the base end portion of the piezoelectric thin film layer 28 is made to have substantially the same shape as the drive electrode layer 29 and the detection electrode 30 at the root portion 43 that is the root of the vibrator portion 23 as shown in FIG. Formed. The piezoelectric thin film layer 28 has a slightly larger area than the lead connection portions 29-1, 30R-1, and 30L-1 of the drive electrode layer 29 and the detection electrode 30 from the base end portion, and the terminal receiving portion 28-1. Are integrally formed with a pattern.

  In the piezoelectric film layer patterning step, the piezoelectric thin film layer 28 having a length dimension t18 of 2.2 mm slightly longer than the drive electrode layer 29 and the detection electrode 30 and a width dimension t19 of 90 μm is patterned. The terminal receiving portion 28-1 formed at the base end portion of the piezoelectric thin film layer 28 has a width dimension of 5 μm around the lead connection portions 29-1, 30 </ b> R- 1 and 30 </ b> L- 1 of the drive electrode layer 29 and the detection electrode 30. And is patterned. The piezoelectric thin film layer 28 is not limited to the above-described dimension value, and may be formed on the second main surface 23-2 of the vibrator portion 23 with a larger area than the drive electrode layer 29 and the detection electrode 30. It is suitably formed within the possible range.

  Then, the reference electrode layer 27 is patterned as shown in FIGS. 25 and 26 by the first electrode layer patterning process in which the first electrode layer 40 is subjected to the same patterning process as the second electrode layer patterning process described above. To do. The first electrode layer patterning step includes a step of forming a resist layer at a corresponding portion of the reference electrode layer 27, removing the resist layer after removing the unnecessary first electrode layer 40 by, for example, an ion etching method or the like. Then, the reference electrode layer 27 is patterned. Note that the first electrode layer patterning step is not limited to such a step, and the reference electrode layer 27 may be formed using an appropriate conductive layer forming step employed in the semiconductor process. is there.

  In the first electrode layer patterning step, the reference electrode layer 27 is formed on the second main surface of the vibrator portion 23 and has a width slightly smaller than the width and larger than the piezoelectric thin film layer 28. The base end portion of the reference electrode layer 27 is formed so as to have substantially the same shape as the drive electrode layer 29, the detection electrode 30, and the piezoelectric thin film layer 28 at the root portion 43 that is the root of the vibrator portion 23 as shown in FIG. Is done. In this first electrode layer patterning step, the first lead 31A and the first terminal portion 25A at the distal end thereof are simultaneously patterned on the portion where the base portion 22 is formed by being pulled out integrally from the base end portion. The

  In the first electrode layer patterning step, the length dimension t20 is 2.3 mm, the width dimension t21 is 94 μm, and the reference electrode layer 27 is formed around the piezoelectric thin film layer 28 with a width dimension of 5 μm. The first electrode layer patterning step is not limited to the above-described dimension value, but is appropriately formed as long as the reference electrode layer 27 can be formed on the second main surface of the vibrator portion 23. .

[Planarization layer forming step]
In the vibration element manufacturing process, the drive electrode layer 29 and the lead connection portions 29-1, 30R-1, and 30L-1 of the detection electrode 30 and the terminal portion 25B correspond to the formation portion of the base portion 22 through the above-described steps. ˜25D are formed, and leads 31B to 31D that are integrated with these terminal portions 25 are formed. At this time, in order to smoothly connect the leads 31B to 31D to the lead connecting portions 29-1, 30R-1, and 30L-1, the planarizing layer 24 shown in FIGS. 27 and 28 is formed.

  The leads 31B to 31D that connect the lead connecting portions 29-1, 30R-1, and 30L-1 and the terminal portions 25B to 25D are, as shown in FIGS. 29 and 30, terminal receiving portions 28- of the piezoelectric thin film layer 28. 1 and the end portion of the reference electrode layer 27 so as to route the formation portion of the base portion 22. As described above, since the piezoelectric thin film layer 28 is patterned by subjecting the piezoelectric film layer 41 to wet etching, the end portion of the etched portion is reversely tapered toward the second main surface 21-2 side of the silicon substrate 21. It is a vertical step. Therefore, when the leads 31B to 31D are directly formed in the formation portion of the base portion 22, a break may occur in the stepped portion. In addition, it is necessary to maintain insulation between the first lead 31A and the leads 31B to 31D that are routed around the base 22 formation site.

  In the planarization layer forming step, the resist layer formed on the formation portion of the base portion 22 is subjected to photolithography processing to cover the lead connection portions 29-1, 30R-1, 30L-1 and the first lead 31A. The pattern is formed. The patterned resist layer is cured by, for example, a heat treatment at about 160 ° C. to 300 ° C. to form the planarizing layer 24. In the planarization layer forming step, the planarization layer 24 having a width dimension t24 of 200 μm, a length dimension t25 of 50 μm, and a thickness dimension of 2 μm (highlighted in FIG. 28) is formed. Note that the planarization layer forming step is not limited to this step, and the planarization layer 24 is formed using an appropriate resist layer forming step performed in a semiconductor process or the like or an appropriate insulating material. May be.

[Wiring layer forming process]
Next, the wiring layer forming step for forming the second terminal portion 25B to the fourth terminal portion 25D and the second lead 31B to the fourth lead 31D described above is performed on the formation portion of the base portion 22. In the wiring layer forming step, a photosensitive photoresist layer is formed over the entire surface of the base 22 forming portion, and the photoresist layer is subjected to a photolithography process to form the second terminal portion 25B to the fourth terminal portion. An opening pattern corresponding to 25D and the second lead 31B to the fourth lead 31D is formed, and a conductor layer is formed in each opening by sputtering to form a wiring layer. In the wiring layer forming step, after a predetermined conductor portion is formed, the photoresist layer is removed, and the second terminal portion 25B to the fourth terminal portion 25D and the second lead 31B to the fourth lead 31D shown in FIGS. The pattern is formed.

  In this wiring layer forming step, after a titanium layer or an alumina layer for improving adhesion to the silicon oxide film 33B is formed as a base layer, a low-cost copper layer having a low electrical resistance is formed on the titanium layer. The In this example, for example, the titanium layer is formed with a thickness of 20 nm, and the copper layer is formed with a thickness of 300 nm. Note that the wiring layer forming step is not limited to such a step, and the wiring layer may be formed by various wiring pattern forming techniques widely used in a semiconductor process, for example.

[Insulating protective layer forming process]
Subsequently, the base 22 having the terminal portion 25 and the lead 31 formed on the main surface through the above-described steps, and the three-layer configuration on the main surface of the vibrator portion 23 having the electrode layers and the piezoelectric thin film layer 28 formed thereon. An insulating protective layer forming step for forming the insulating protective layer 45 is performed. The insulating protective layer forming step includes a resist layer forming step, a resist layer patterning forming step, a first alumina layer forming step, a silicon oxide layer forming step, a second alumina layer forming step, and a resist layer removing step. .

  The insulating protective layer forming step undergoes a resist layer forming step and a resist layer patterning forming step, and as shown in FIG. 31, a resist layer 44 having openings for forming the insulating protective layer 45 on the second main surface of the silicon substrate 21. Form. In the resist layer forming step, a photosensitive resist agent is applied over the entire surface of the silicon substrate 21 to form the resist layer 44. In the resist layer patterning formation step, the resist layer 44 is subjected to photolithography to open a portion corresponding to the formation region of the insulating protective layer 45 to form an insulating protective layer forming opening 44A. In addition, although illustration is abbreviate | omitted for the resist layer 44, the corresponding site | part of the terminal part 25 is each left circular.

  In the insulating protective layer forming step, the first alumina layer 46, the silicon oxide layer 47, and the second alumina layer 48 are laminated and formed by sputtering, and unnecessary sputtered films are removed together with the resist layer 44. A desired insulating protective layer 45 is formed by a so-called lift-off method that leaves a sputter forming layer having a three-layer structure in the insulating protective layer forming opening 44A. 32 to 34, only the sputtered films formed in the insulating protective layer forming opening 44A are shown, but the same applies to the resist layer 44 constituting the insulating protective layer forming opening 44A. Of course, sputtered films are formed, and these sputtered films are removed together with the resist layer 44 by the resist layer removing process.

  In the first alumina layer forming step, alumina is sputtered to form the first alumina layer 46 inside the insulating protective layer forming opening 44A described above as shown in FIG. The first alumina layer 46 is formed with a thickness dimension t26 of about 50 nm and is a base for improving the adhesion with the silicon substrate 21, the drive electrode layer 29, or the detection electrode 30 in the insulating protective layer formation opening 44A as described above. Functions as a metal layer.

  In the silicon oxide layer forming step, silicon oxide is sputtered to form a silicon oxide layer 47 on the first alumina layer 46 described above, as shown in FIG. In the silicon oxide layer forming step, since the argon pressure in the sputtering vessel is 0.35 Pa as the lower limit of the discharge limit, the argon pressure is set to 0.4 Pa, which is slightly higher than the lower limit value, and silicon oxide is sputtered. As a result, a high-density silicon oxide film 47 is formed. The silicon oxide film forming step has a thickness of 1 μm or less, which is a thickness within a range in which the thickness of the drive electrode layer 29 and the detection electrode 30 is at least twice that of the insulating electrode, and a sufficient burr generation rate is small in the lift-off method. A silicon oxide layer 47 having a thickness dimension t27 is formed. Specifically, the silicon oxide layer 47 is formed with a thickness dimension t27 of 750 nm.

  In the second alumina layer forming step, alumina is sputtered to form the second alumina layer 48 over the entire surface of the silicon oxide layer 47 described above as shown in FIG. The second alumina layer 48 is formed with a thickness dimension t28 of about 50 nm, and prevents the silicon oxide layer 47 from being damaged by the etching agent by improving the adhesion with the resist layer formed in the outer groove forming process described later. To do.

[Outline groove forming process]
Next, a step of forming an etching stop layer 70 on the first main surface 21-1 of the silicon substrate 21 is performed as shown in FIG. The etching stop layer 70 suppresses the occurrence of a shape defect in which a predetermined edge shape is not formed due to plasma concentration on the first main surface 21-1 side when the outer shape groove forming step described later is performed on the silicon substrate 21. The function to perform. In the etching stop layer forming step, for example, silicon oxide having a thickness of about 500 nm is formed over the entire surface of the first main surface 21-1 of the silicon substrate 21 by sputtering.

  In the outer shape groove forming step, an outer shape groove 39 that penetrates the diaphragm portion 38 and forms the outer peripheral portion of the vibrator portion 23 is formed. In the outer shape groove forming step, as shown in FIGS. 35 to 37, the silicon substrate 21 in which each of the electrode layers described above is laminated is formed from the second main surface 21-2 side of the silicon substrate 21 facing the diaphragm portion 38. An outer groove 39 made of a substantially U-shaped through-groove having a root portion 43 on one side of the vibrator portion 23 as a start end 39A and a root portion 43 on the other side as a terminal end 39B is formed so as to surround the vibrator portion 23. The The outer groove 39 is formed with a width dimension t7 of 200 μm as described above.

  Specifically, the outer shape groove forming step includes a first etching process step of removing the silicon oxide film 33B in a predetermined U-shape to expose the second main surface 21-2 of the silicon substrate 21, and the exposed silicon. And a second etching process step for forming the outer groove 39 in the substrate 21.

  In the first etching step, a photosensitive photoresist layer is formed over the entire surface of the silicon oxide film 33B, and the photoresist layer is subjected to a photolithography process to form the above-described electrode layer formation regions. A U-shaped opening pattern having an opening dimension equal to the outer dimension of the surrounding vibrator portion 23 is formed. In the first etching process, the silicon oxide film 33B exposed through the opening pattern is removed by ion etching. In the first etching process, the silicon oxide film 33B can be removed in a U shape by, for example, wet etching, but ion etching is preferably performed in consideration of the occurrence of dimensional errors due to side etching. .

  In the second etching step, the remaining silicon oxide film 33B is used as a resist film (etching protective film). In the second etching process, the silicon substrate 21 is formed so that a selection ratio with respect to the resist film (silicon oxide film 33B) can be obtained and the outer peripheral part of the vibrator part 23 is constituted by a highly accurate vertical surface. For example, reactive ion etching is performed.

  In the second etching process, a reactive ion etching (RIE) apparatus having a function of generating inductively coupled plasma (ICP) that generates high-density plasma is used. The second etching process is a Bosch (Bosch) process that repeats an etching process for introducing SF6 gas into an etching location and a protective film forming process for protecting the outer peripheral wall at the location etched by introducing C4F8 gas. An external groove 39 having a vertical inner wall is formed in the silicon substrate 21 at a speed of about 10 μm per minute.

  After the second etching treatment step, a step of removing the etching stop layer 70 formed on the first main surface 21-1 of the silicon substrate 21 is performed. In the step of removing the etching stop layer, the etching stop layer 70 made of silicon oxide is removed by a wet etching process using, for example, ammonium fluoride. In the etching stop layer removing step, if the photoresist layer formed in the above-described outer groove forming step is removed, the insulating protective layer 45 is also removed. Therefore, after removing the etching stop layer 70, the photoresist layer is removed. To be removed.

[Polarization process]
Subsequently, a polarization processing step is performed in which the piezoelectric thin film layer 28 of each vibration element 20 formed on the silicon substrate 21 is polarized at once. Cu wiring is used for the polarization wiring for the polarization treatment. The Cu wiring can be removed without damaging each vibration element 20 by being easily dissolved by wet etching after performing polarization processing described later. Of course, the polarization wiring is not limited to the Cu wiring, and may be formed of an appropriate conductor having the above-described function.

  For forming the Cu wiring, for example, a resist layer having a desired shape as an opening is formed by patterning on the second main surface 21-2 of the silicon substrate 21 by photolithography, and then the Cu layer is formed by sputtering. In addition, a lift-off method is used in which the Cu layer adhering to unnecessary portions is removed together with the resist layer. The Cu wiring has a width dimension of 30 μm or more and a thickness of about 400 nm, for example, to ensure conduction during polarization processing.

  The polarization treatment process can be efficiently performed by connecting each vibration element 20 to an external power source collectively through an application side pad and a ground side pad formed on the Cu wiring. In the polarization treatment step, the pads are connected to the external power source by, for example, a wire bonding method, and the polarization treatment is performed by energizing under the condition of 20V-20 min. Of course, the polarization treatment step is not limited to such conditions, and the polarization treatment may be performed according to an appropriate connection method or polarization conditions.

[Gold bump formation process]
Next, a gold bump forming process is performed. Since the vibration element 20 is surface-mounted on the support substrate 2 as described above, the gold bumps 26 are formed on the respective terminal portions 25. In the gold bump formation step, a gold wire bonding tool is pressed against each terminal portion 25 to form stud bumps having a predetermined shape. In the gold bump forming process, so-called dummy bumps are also formed on the base 22 as necessary. In addition, as another formation method of the gold bump 26, there is a plating bump method described later.

  The plating bump method includes a step of forming a plating resist layer 62 having a predetermined opening 61 on the terminal portion 25 as shown in FIG. 38A and a gold plating process as shown in FIG. A gold plating step for growing the plating layer 26 to a predetermined height and a step for removing the plating resist layer 62 are provided. In the gold bump forming step, the thickness (height) of the gold bump 26 formed by the plating process is limited, and the gold bump 26 having a desired height may not be formed. In the gold bump forming process, when a desired gold bump 26 cannot be obtained by a single plating process, a so-called stepped gold bump 26 is formed by performing a twice plating process using the first gold plating layer as an electrode. You may make it form.

  Note that the bump formation step is not limited to the above-described method, and the bump formation may be performed by, for example, a vapor deposition method or a transfer method performed in a semiconductor process. In the vibrating element manufacturing process, although details are omitted, a so-called bump base metal layer such as TiW or TiN is formed in order to improve the adhesion between the gold bump 26 and the terminal portion 25.

[Cutting process]
Subsequently, a cutting process of cutting each vibration element 20 from the silicon substrate 21 is performed. In the cutting step, each vibration element 20 is cut by cutting the corresponding portion of the base 22 with, for example, a diamond cutter. In the cutting process, after the cutting groove is formed by the diamond cutter, the silicon substrate 21 is folded and cut. In the cutting step, cutting may be performed using a surface orientation of the silicon substrate 21 by a grindstone or grinding.

  In the above-described vibration element manufacturing process, for example, the base portion 22 is shared, and the vibrator portion is integrally formed on the adjacent side surface of the base portion 22 so as to obtain a biaxial detection signal. In comparison, it is possible to greatly improve the number of wafers taken from the silicon substrate (wafer) 21.

[Mounting process]
The vibration element 20 manufactured through the above steps is mounted on the first main surface 2-1 of the support substrate 2 by a surface mounting method with the second main surface 21-2 side of the silicon substrate 21 as a mounting surface. . In the vibration element 20, the gold bumps 26 provided on the terminal portions 25 are aligned with the opposing lands 4 on the support substrate 2 side. At this time, the vibration element 20 is positioned with high accuracy by the mounting machine by reading the alignment mark 32 as described above.

  The vibration element 20 is mounted on the first main surface 2-1 of the support substrate 2 by applying ultrasonic waves while being pressed against the support substrate 2 and welding the gold bumps 26 to the opposing lands 4. The On the support substrate 2, the IC circuit element 7 and the electronic component 8 are mounted on the first main surface 2-1, and the cover member 15 is attached after the adjustment process described later is performed on the vibration element 20. Thus, the vibration type gyro sensor 1 is completed.

  As described above, in the present embodiment, a large number of vibration elements 20 formed by integrally forming the vibrator portion 23 on the base portion 22 are collectively manufactured on the silicon substrate 21, and each is individually separated. ing. Then, by mounting the first vibration element 20 </ b> X and the second vibration element 20 </ b> Y having the same shape on two axes different by 90 ° on the first main surface 2-1 of the support substrate 2, the two-axis detection signal The vibration type gyro sensor 1 is obtained.

[Adjustment process]
In the vibration element manufacturing process, the vibrator 23 of each vibration element 20 is cut out from the silicon substrate 21 with high accuracy by performing etching using inductively coupled plasma as described above. Depending on conditions such as yield, it is difficult to form each transducer unit 23 so as to be symmetrically positioned with respect to the plasma emission center line. For this reason, variations in the shape of each vibrator portion 23 may occur due to the displacement of each vibration element 20 and other various process conditions. For example, when the cross-sectional shape of the vibrator portion 23 is formed in a trapezoidal shape or a parallelogram shape, the vibration element 20 deviates from vertical vertical vibration as compared with the normal rectangular shape of the vibrator portion 23 and moves to the central axis. On the other hand, the vibration operation is performed in a state where the mass is inclined to the small side.

  Therefore, an adjustment process for correcting the vibration state is performed by applying laser processing to a predetermined portion of the vibrator unit 23 and grinding the side having a larger mass. In the adjustment step, it is difficult to directly view the cross-sectional shape of the vibrator portion 23 formed with a fine size. Therefore, the vibrator portion 23 is placed at a predetermined longitudinal resonance frequency for each cut vibration element 20. The variation in the cross-sectional shape of the vibrator portion 23 is confirmed by a method of performing a vibration operation and comparing the magnitudes of the left and right detection signals. In the adjustment step, when there is a difference between the left and right detection signals, a part of the vibrator unit 23 on the side that outputs a small detection signal is ground by laser processing.

  In the adjustment step, for example, as shown in FIG. 39A, the oscillation element 20 is driven in a longitudinal resonance state by applying the oscillation output G0 of the oscillation circuit 71 to the drive electrode layer 29 before the adjustment. . In the adjustment step, detection signals G10 and Gr0 obtained from the pair of detection electrode layers 30L and 30R are added by the addition circuit 72, and the addition signal is fed back to the oscillation circuit 71. Then, based on the detection signals G10 and Gr0 obtained from the detection electrodes 30L and 30R, the oscillation frequency of the oscillation circuit 71 is measured as the longitudinal resonance frequency f0, and the difference between the detection signals G10 and Gr0 is measured as a difference signal.

  Further, in the adjustment step, as shown in FIG. 39B, the oscillation element 20 is driven in a lateral resonance state by applying the oscillation output G1 of the oscillation circuit 71 to the detection electrode 30L. In the adjustment step, the detection signal Gr-1 obtained from the detection electrode 30R is fed back to the oscillation circuit 71, and the oscillation frequency of the oscillation circuit 71 is measured as the lateral resonance frequency f1 based on the detection signal Gr-1. Since the lateral resonance frequency f1 obtained from the detection signal Gr-1 and the lateral resonance frequency f2 obtained from the detection signal Gl-1 are equal, the lateral resonance frequency is set in either one of the detection electrodes 30L and 30R. What should I do?

  Further, in the adjustment step, as shown in FIG. 39C, the oscillation element 20 is driven in the lateral resonance state by applying the oscillation output G2 of the oscillation circuit 71 to the detection electrode 30R. In the adjustment step, the detection signal Gl-2 obtained from the detection electrode 30L is fed back to the oscillation circuit 71, and the oscillation frequency of the oscillation circuit 71 is measured as the lateral resonance frequency f2 based on the detection signal Gl-2. In the adjustment step, the frequency difference between the longitudinal resonance frequency f0 and the lateral resonance frequencies f1 and f2 obtained by each measurement described above is used as a detuning degree, and it is determined whether or not the detuning degree is within a predetermined range. Further, the adjustment step determines whether or not the difference signal detected from the detection electrodes 30L and 30R is within a predetermined range.

  In the adjustment step, based on the determination result of the degree of detuning and the difference signal described above, the adjustment processing position with respect to the vibrator unit 23 is determined from the size, and laser irradiation is performed to adjust a part by grinding. In the adjustment process, the same measurement and laser processing are performed until the degree of detuning and the difference signal reach the target values.

  In the adjustment step, a laser device that emits a laser having a wavelength of 532 nm capable of adjusting the spot diameter is used. The adjustment step is performed by irradiating the vibrator portion 23 of the vibration element 20 with a laser at an appropriate place in the length direction with respect to, for example, a ridge line portion straddling the side surface and the first main surface 23-1. . The vibration element 20 performs coarse adjustment on the base end side, since the amount of change in adjustment due to laser irradiation is smaller for both the frequency difference and the detection signal balance from the base end portion of the vibrator unit 23 toward the front end portion. Fine adjustment can be performed on the part side.

Since this adjustment process is performed in a state where the vibration element 20 is mounted on the support substrate 2, readjustment after mounting when the adjustment is performed before mounting becomes unnecessary, and the productivity of the vibration type gyro sensor 1 is improved. Can be enhanced. In this case, since the region irradiated with the adjustment laser is on the upper surface 23-2 side of the vibrator portion 23, the adjustment workability after mounting is excellent. Further, since the upper surface 23-2 of the vibrator portion 23 is a surface on which no piezoelectric layer or electrode layer is formed, the characteristics of the piezoelectric thin film layer 28 change due to heat generated during laser processing, or the polarization state changes. It is possible to prevent the influence such as doing as much as possible.

  By the way, in the vibration type gyro sensor 1, when the vibration element 20 is applied with an AC voltage having a predetermined frequency from the drive detection circuit unit 50 to the drive electrode layer 29, the vibrator unit 23 vibrates with a specific frequency. To do. The vibrator unit 23 resonates at a longitudinal resonance frequency in the longitudinal direction, which is the thickness direction, and also resonates at a lateral resonance frequency in the lateral direction, which is the width direction. The vibration element 20 has higher sensitivity characteristics as the degree of detuning, which is the difference between the longitudinal resonance frequency and the transverse resonance frequency, is smaller. As described above, the vibration type gyro sensor 1 is subjected to the crystal anisotropic etching process and the reactive ion etching process to accurately form the outer peripheral part of the vibrator part 23 so as to achieve a high degree of detuning.

  The vibration element 20 has a great influence on the longitudinal resonance frequency characteristics due to the accuracy of the length dimension t5 of the vibrator portion 23. As described above, in the vibration element 20, the root portion 43 that defines the length dimension t5 of the vibrator portion 23 is formed by performing crystal anisotropic etching treatment on the (100) plane of the diaphragm portion 38 and 55 °. When a “deviation” occurs between the (111) plane that is the etching inclined surface 133 and the boundary line that is a flat surface, the degree of detuning increases according to the amount of this “deviation”.

  That is, in the vibration element 20, the amount of such “deviation” is caused by the positional deviation between the resist film pattern formed on the silicon oxide film 33B during the crystal anisotropic etching process and the resist film pattern during the reactive ion etching process. It becomes. Therefore, for example, the vibration element 20 may be positioned by a double-side aligner that can simultaneously observe the first and second main surfaces 21-1 and 21-2 of the silicon substrate 21 in the process. In addition, the vibration element 20 forms appropriate positioning patterns and marks on the first main surface 21-1 and the second main surface 21-2 of the silicon substrate 21, and restricts the position of the other main surface based on these patterns. You may make it aim at the response | compatibility positioning by the alignment apparatus which performs. The vibration element 20 can be applied to the positioning process on the support substrate 2 in correspondence with the positioning.

  In the vibration element 20, the longitudinal resonance frequency and the transverse resonance frequency substantially coincide with each other if the above-described “deviation” amount is in a range smaller than about 30 μm. Therefore, the vibration element 20 can suppress a decrease in the detuning characteristic due to a substantial “deviation” amount by performing a slightly accurate etching process, and eliminates the need for the above-described alignment apparatus. Manufactured.

[Effect of a pair of vibration elements]
In the vibration element manufacturing process, as described above, a large number of vibration elements 20 formed by integrally forming the vibrator portion 23 on the base portion 22 are collectively manufactured on the silicon substrate 21 and separated from each other. In the vibration element manufacturing process, the first vibration element 20 </ b> X having the same shape and the first vibration element 20 </ b> X provided in the vibration type gyro sensor 1 mounted on the main surface of the support substrate 2 so as to be positioned on two axes and obtaining a detection signal of two axes are provided. The two vibration element 20Y is manufactured.

  In the vibration element manufacturing process, for example, in comparison with a two-axis integrated vibration element that obtains a two-axis detection signal by forming the vibrator 22 integrally on adjacent side surfaces of the base 22 in common. It is possible to greatly improve the number of wafers taken from the silicon substrate (wafer) 21. FIG. 40 shows a comparison of the number of parts obtained when the vibration element 20 having the above-described dimensional values and the two-axis integrated vibration element having the same function are manufactured.

  As is clear from FIG. 40, a total of 60 vibration elements 20 (30 vibration-type gyro sensors 1 are used since two are used) when a 3 cm square silicon substrate is used. When using 4 inch diameter wafers generally used in the mass production process, a total of 1200 pieces (600 pieces) is manufactured, and when using 5 inch wafers, a total of 4000 pieces (2000 pieces). Is produced. On the other hand, a total of 20 biaxially integrated vibrating elements are manufactured when a 3 cm square silicon substrate is used, 300 are manufactured when a 4 inch diameter wafer is used, and a 5 inch diameter wafer is further manufactured. When used, a total of 800 are produced. The vibration element 20 greatly improves the yield of the material and can reduce the cost.

  In the vibration type gyro sensor, as described above, the first vibration element 20X and the second vibration element 20Y that obtain a detection signal of two axes are mounted on the support substrate 2 so as to be positioned on two orthogonal axes. In the vibration-type gyro sensor 1, the vibration operation of one vibration element affects the other vibration element, so that the occurrence of so-called biaxial interference is considered. FIG. 41 shows the result of measuring the crosstalk when the first vibration element 20X and the second vibration element 20Y are mounted on the support substrate 2 with their directions changed.

  In FIG. 41, type 1 indicates that the first vibration element 20X-1 and the second vibration element 20Y-1 are diagonal positions of the support substrate 2 so that the vibrator portions 23X-1 and 23Y-1 face each other. The base portions 22X-1 and 22Y-1 are fixed and mounted on the corner portion. In Type 2, the first vibration element 20X-2 and the second vibration element 20Y-2 fix the base portions 22X-2 and 22Y-2 at the same corner portion and the vibrator portions 23X-2 and 23Y-2. Are mounted on the support substrate 2 so as to extend along side edges orthogonal to each other. In Type 3, the base portion 22X-3 is fixed to the corner portion where the first vibration element 20X-3 is located, and the vibrator portion 23X-3 is mounted on the support substrate 2 toward one of the adjacent corner portions, and the second portion The base portion 22Y-3 is fixed to the corner portion where the vibration element 20Y-3 is adjacent, and the vibrator portion 23Y-3 is mounted on the support substrate 2 toward the first vibration element 20X-3. In addition, the same figure shows the crosstalk value about the biaxially integrated vibration element (type 0) 60 described above as a comparative example. The unit of crosstalk is dbm (decibel effective value).

  As shown in FIG. 41, the crosstalk value of the type 0 vibration element 60 is −50 dbm, the crosstalk value of the type 1 vibration elements 20X-1 and 20Y-1 is −70 dbm, the type 2 vibration element 20X-2, The crosstalk value of 20Y-2 was −60 dbm, and the crosstalk values of the type 3 resonator elements 20X-3 and 20Y-3 were −72 dbm.

  In the vibration type gyro sensor of types 1 to 3 according to the present invention, the improvement of about −10 dbm is achieved at the minimum with respect to the type 0 biaxially integrated vibration element 60 regardless of the mounting state. The vibration type gyro sensor 1 includes two independent vibration elements 20, so that the interference signal between the two axes with respect to the detection signal can be suppressed to about 1 mV. On the other hand, in a vibration type gyro sensor provided with a two-axis integral type vibration element, the interference signal between the two axes with respect to the detection signal becomes about 10 mV, and the detection characteristics are deteriorated.

  Further, in the vibration type gyro sensor 1 of the present embodiment, the first vibration element 20X and the second vibration element 20Y are arranged as in the type 1 and mounted on the support substrate 2, thereby causing interference between the two axes. The smallest result was obtained. In the vibration gyro sensor 1, the first vibration element 20 </ b> X and the second vibration element 20 </ b> Y may be mounted at any position with respect to the support substrate 2. In consideration of the mounting of the component 8 and the routing of the wiring pattern 5, the mounting efficiency is most improved by fixing the base portion 22 to the corner portion of the support substrate 2 as in each type described above.

  In the vibration type gyro sensor 1, each vibration element 20 is provided with an alignment mark 32. The alignment mark 32 is recognized, and the two first vibration elements 20 X and the second vibration element 20 Y are mounted. Thus, mounting is performed in a posture facing each other on two orthogonal axes of the support substrate 2. In the vibration type gyro sensor 1, it is necessary to mount the vibrator portion 23 of each vibration element 20 on the support substrate 2 so as not to be displaced. FIG. 42 is a histogram showing the positional deviation (distribution of deviation angle with respect to the central axis) of each vibration element 20, where the horizontal axis is the deviation angle (deg) and the vertical axis is the quantity. A case in which the positioning mark 32 is recognized and mounted is shown in FIG. A, and a case in which the mounting is recognized by the outer shape of the vibration element 20 is shown in FIG. In the vibration type gyro sensor 1, as is clear from FIG. 5, the highly accurate recognition is performed by the alignment mark 32, so that each vibration element 20 has little variation in the occurrence of angular deviation with respect to the support substrate 2. Mounted with high accuracy in a small angle range. Therefore, in the vibration type gyro sensor 1, each vibration element 20 performs a highly accurate and stable camera shake detection operation.

  In the above-described embodiment, by mounting the pair of vibration elements 20X and 20Y on the first main surface 2-1 of the support substrate 2 so that the vibrator portions 23 face each other in the axial direction perpendicular to each other, The angular velocity in the biaxial direction was detected. Instead, the same angular velocity detection in the two axial directions may be performed by mounting three or more vibrating elements on the common support substrate 2 in different axial directions. For example, three vibration elements may be mounted on a common support substrate so that each vibrator portion has an angle difference of 120 °.

  In addition, if two vibration gyro sensors 1 of the present embodiment configured as described above are prepared and mounted on the surfaces orthogonal to each other inside a main body device such as a video camera, the front and rear It is possible to simultaneously detect angular velocities in the three axial directions of direction, lateral direction, and vertical direction.

[Crosstalk]
The operating frequency of the vibrating element 20 can be set in the range of several kHz to several hundred kHz. In this biaxial angular velocity sensor (vibrating gyro sensor 1), the operating frequencies (fx, fy) of the two vibrating elements 20X, 20Y are set. ) And the magnitude of the interference signal due to the frequency difference (fx−fy) was measured, and the result shown in FIG. 43 was obtained. In FIG. 43, the horizontal axis represents the difference between the operating frequencies (fx−fy) of the vibration elements 20X and 20Y, and the vertical axis represents the AC noise component Vo superimposed on the sensor output (DC) (the upper amplitude peak of the AC waveform representing noise). (Size between lower amplitude peaks), which is referred to herein as inter-axis crosstalk.

If the frequency difference (fx−fy) is less than 1 kHz, the crosstalk value reaches 1500 mVpp or more, and stable angular velocity detection cannot be performed. On the other hand, when the frequency difference is around 1 kHz, the crosstalk value starts to be remarkably reduced to 500 mVpp, and can be lowered to 200 mVpp at a frequency difference of 1.4 kHz and to 100 mVpp at 2 kHz or more. From the results of FIG. 43, it is understood that the crosstalk between the axes is remarkably reduced by setting the frequency difference (fx−fy) to 1 kHz or more. When two types of samples in which the operating frequencies (fx, fy) of the two vibration elements 20X, 20Y were separated by 1 kHz were produced, a biaxial angular velocity sensor that operates extremely stably could be obtained.
Sample 1 The operating frequency of the first vibration element 20X is 37 kHz.
The operating frequency of the second vibration element 20Y is 36 kHz.
Sample 2 The operating frequency of the first vibration element 20X is 40 kHz.
The operating frequency of the second vibration element 20Y is 39 kHz.

  As shown in FIG. 43, by setting the frequency difference (fx−fy) from 2 kHz to 3 kHz, it is possible to avoid the influence of crosstalk between the pair of vibration elements 20X and 20Y. Therefore, by driving the vibration elements 20X and 20Y with a frequency difference of 2 kHz or more, it is possible to further improve the accuracy of the sensor output.

  In addition, the vibration type gyro sensor according to the present embodiment may be affected by crosstalk between the vibration element 20 and other electronic components (sensors, etc.) built in the main device. It is preferable to prepare a plurality of vibration elements having different drive frequencies in advance so that a frequency that does not have a significant influence can be selected as the drive frequency of the vibration element. Specifically, multiple types of vibration elements are prepared in the range of the drive frequency, for example, 35 kHz or more and 60 kHz or less, to avoid crosstalk with other electronic components built into the main unit as well as between a pair of vibration elements. Two elements having two operating frequencies that are separated from each other by 1 kHz or more (preferably 2 kHz or more) are selected.

  The adjustment of the operating frequency of each vibration element 20X, 20Y is performed by adjusting various vibration characteristics such as the degree of detuning (frequency difference between the longitudinal resonance frequency and the transverse resonance frequency) and the left / right detection signal balance in the adjustment process of the vibration element 20, for example. After that, the same laser trimming is performed on the distal end side of the vibrator unit 23 to adjust the resonance frequency.

  Since the vibrator portion 23 of the vibration element 20 is a cantilever-shaped vibrator, the resonance frequency is inversely proportional to the square of the length of the beam as shown by the following equation. Where fn is the resonant frequency of the cantilever, E is the Young's modulus, I is the moment of inertia of the cross section of the beam, ρ is the density, A is the cross sectional area of the beam, L is the length of the beam, and λ is the proportionality factor. . Thus, the resonance frequency of the beam can be increased by laser trimming the tip portion of the vibrator unit 23 to reduce the rigidity and effective length of the beam.

  On the other hand, when the resonance frequency is adjusted, it must be avoided that the previously adjusted detuning degree fluctuates. FIG. 44 is a plot (graph) of data at each point obtained by measuring changes in beam processing position, resonance frequency, and detuning when the laser processing depth is 11 μm and the beam length is 1.9 mm. . The degree of detuning (93 Hz) is changed by laser machining a position that is separated by 1.6 mm or more (4/5 or more of the total length of the transducer part 23) from the base of the beam (base end part of the transducer part 23). The resonance frequency can be increased.

  From the above results, as shown in FIG. 45, on the upper surface 23-1 side of the transducer part 23, the position for the resonance frequency adjustment laser is located at a position away from the root part by 4/5 or more of the entire length of the transducer part 23. A formation region of the processing recess (processing mark) 90 is used, and a region other than this is a formation region of the laser processing recess 80 for adjusting the degree of detuning.

  Thereby, the resonance frequency of each of the vibration elements 20X and 20Y can be adjusted to an arbitrary different frequency without changing the degree of detuning, and crosstalk between axes can be easily avoided. In addition to the crosstalk between these vibration elements, the resonance frequency of each of the vibration elements 20X and 20Y can be adjusted to a frequency band in which the influence of the crosstalk is small between other electronic devices inside the main device. .

(Second Embodiment)
In the present embodiment, the mounting area of the IC circuit element 7 on the support substrate 2 will be examined.

  As shown in FIG. 46, on the support substrate 2, an IC circuit element 7 and other electronic components 8 are mixedly mounted in addition to the pair of vibration elements 20 (20X, 20Y). These parts are often mounted by a reflow soldering method.

  Therefore, when a multi-leg component such as the IC circuit element 7 is reflow-mounted after the vibration element 20 is flip-chip mounted, the support substrate 2 is warped by thermal stress, affecting the vibration element 20 and changing the vibration mode. There is a risk of deteriorating the characteristics. Further, when the support substrate 2 on which the vibration element 20 is mounted is reflow-mounted on the control board on the main device side, the joint portion of the IC circuit element 7 on the support substrate 2 is reflowed again, and the support generated in the mounting process It is conceivable that the warp of the substrate 2 affects the vibration element 20.

  In the first embodiment described above, as shown in FIG. 46, the IC circuit element 7 is mounted in the vicinity of a corner portion different from the corner portion of the support substrate 2 on which the vibration element 20 is mounted. Further, the other electronic components 8 mounted on the support substrate 2 are also concentrated in a biased area. Therefore, thermal stress and thermal distortion during reflow are generated non-uniformly in the surface of the support substrate 2, and this causes no uniform thermal stress or the like to act on the mounting region of the pair of vibration elements 20. There is a risk of variations in detection accuracy.

  Therefore, in the present embodiment, as shown in FIG. 47, the main mounting area of the IC circuit element is defined in an intermediate area of a straight line connecting the mounting areas of the pair of vibration elements 20. As a result, the thermal stress acting on the support substrate 2 during the reflow mounting process of the IC circuit element 7 or the reflow mounting process of the support substrate 2 on the control board can be applied equally to the pair of vibration elements 20. Thus, it is possible to suppress the occurrence of a characteristic difference between the vibration elements.

  Here, as shown in FIG. 47, the mounting area of the IC circuit element 7 is preferably set so that the IC circuit element 7 having a rectangular shape in plan view is set at an intermediate point (symmetrical position) between the pair of vibration elements 20. Specifically, it can be set within a certain area centered on the mounting area of the IC circuit element 7 shown in the figure. In this case, the predetermined area is an area where a part of the mounting area of the IC circuit element 7 belongs to at least each quadrant when the plane of the support substrate 2 is divided into the first to fourth quadrants. If it is.

  In addition to the mounting area of the IC circuit element 7, for the other electronic components 8, as shown in FIG. 47, the number of parts and the component mounting area are set in a distributed manner at equal or symmetrical positions with respect to each vibration element 20. Is preferred. As a result, not only the IC circuit element 7 but also the stress generated in the reflow process of other electronic components 8 can be applied to each vibration element 20 equally.

  FIG. 48 shows the relationship between the number of reflows of the support substrate 2 and the output difference between the pair of vibration elements due to the difference in the mounting area of the IC circuit element 7. It means that the smaller the output difference between the vibrating elements, the more the amount of strain propagated to each vibrating element, and the larger the output difference, the larger the difference in the amount of strain propagated to each vibrating element. Note that the output difference is 0 before reflow. Compared to the configuration of the comparative example (FIG. 46) in which the IC circuit element 7 is arranged at the corner of the support substrate 2, the effect of the embodiment of the present invention shown in FIG. Almost no output difference between the elements was observed.

(Third embodiment)
Next, a third embodiment of the present invention will be described.

  FIG. 49 schematically shows a wiring structure between the vibration element 20 and the drive detection circuit unit 50 (IC circuit element 7). The reference electrode layer 27 is connected to the Ref terminal of the drive detection circuit unit 50, and the drive electrode layer 29 is connected to the Ga terminal of the drive detection circuit unit 50. The pair of detection electrodes 30L and 30R are connected to the Gb and Gc terminals of the drive detection circuit unit 50, respectively.

  In the conventional vibration type gyro sensor, the Ref terminal is set to the same predetermined positive potential (eg, 1.35 V) as the Ga to Gc terminals. That is, the center potential of the AC signal input to the drive electrode layer 29 and the center potential of the detection signals output from the detection electrodes 30L and 30R are both set to the same potential as that of the reference electrode layer 27. For this reason, the detection signals output from the detection electrodes 30L and 30R show values that are large and small (positive and negative) with respect to the reference potential, and as a result, there is a problem that the detection sensitivity decreases as the element becomes smaller. It was.

  Therefore, in the vibration type gyro sensor of the present embodiment, the Ref terminal to which the reference electrode layer 27 of the vibration element 20 is connected is set to the GND (ground) potential. That is, both the center potential of the AC signal input to the drive electrode layer 29 and the center potential of the detection signals output from the detection electrodes 30L and 30R are only a predetermined potential with respect to the reference electrode layer 27 as shown in FIG. It is set to be high. As a result, the vibrator unit 23 is driven in a state where a predetermined DC bias (offset potential) is applied between the Ga to Gc terminals and the Ref terminal, and the detection signals from the detection electrodes 30L and 30R. Can be generated at a potential higher than the reference potential, so that the SN ratio can be increased and the detection sensitivity can be improved.

  The magnitude of the offset potential set between the drive electrode layer 29 (detection electrodes 30L, 30R) and the reference electrode layer 27 greatly affects the piezoelectric characteristics (output sensitivity characteristics) of the piezoelectric thin film layer 28. FIG. 51 shows the relationship between the offset potential and the piezoelectric characteristics. Here, the offset potential is represented by the electric field strength (V / μm) acting on the piezoelectric thin film layer 28.

  As is clear from FIG. 51, when the piezoelectric characteristic when the offset potential is 0 is set to 1, the piezoelectric characteristic is improved as the offset potential is increased, but conversely when the offset potential is about 8 V / μm or more. It shows a tendency for the piezoelectric characteristics to decrease. When the offset potential exceeds 15 V / μm, the piezoelectric characteristics are lower than when the offset potential is 0. From the above, the offset potential at which the piezoelectric characteristics can be improved in the present embodiment is 15 V / μm or less, preferably 8 V / μm or less.

  Here, FIG. 52 shows a hysteresis loop (PE curve) representing a change in the polarization amount with respect to the external electric field strength of the piezoelectric thin film layer 28. When the reference electrode layer 27 and the drive electrode layer 29 are installed at equipotentials, the center potential (operating voltage) of the input signal applied to the drive electrode layer 29 matches the loop center (electric field strength 0) in FIG. To do. On the other hand, in the present embodiment in which the reference electrode layer 27 is connected to the GND terminal, the operating voltage is set to a position shifted from the loop center to the right side (electric field strength positive direction). This shift amount is an offset potential, and is 1.35 V in the present embodiment. As a result, the piezoelectric body is driven in a region having a polarization amount higher than the residual polarization Pr of the piezoelectric body, so that the output voltages of the detection electrodes 30L and 30R can be increased accordingly.

  Note that the piezoelectric body can be driven in a region where the polarization amount is large as the operating voltage shift amount (offset potential or bias potential) increases. However, when the polarization amount is close to the saturation polarization Ps, the driving direction of the piezoelectric body is restricted. This is not preferable. Accordingly, the shift amount is preferably, for example, less than the coercive electric field (+ Ec) of the piezoelectric body.

  As described above, according to the present embodiment, since the detection voltage can be increased as compared with the conventional case, the angular velocity or Coriolis force acting on the vibrator unit 23 can be detected with high sensitivity, and the vibration element 20 It becomes possible to easily cope with downsizing. In addition, since it is possible to cope with further lowering of the operating voltage of the drive detection circuit unit 50, it is possible to contribute to lower power consumption of the vibration type gyro sensor.

As described above, the vibration-type gyro sensor disclosed in the present specification has the following configuration in addition.
1. In a vibration-type gyro sensor including a support substrate on which a wiring pattern having a plurality of lands is formed and a vibration element mounted on the surface of the support substrate,
The vibration element includes a base portion having a mounting surface on which a plurality of terminal portions connected to the land are formed, and a protruding portion integrally formed in a cantilever shape from a side peripheral portion of the base portion, and is the same as the mounting surface of the base portion Having a vibrator portion having a substrate facing surface constituting the surface,
A first electrode layer, a piezoelectric layer laminated on the first electrode layer, and a second electrode layer laminated on the piezoelectric layer are formed on the substrate facing surface of the vibrator unit, respectively. And
The vibrator section vibrates by applying an AC signal between the first electrode layer and the second electrode layer, and the central electric field strength of the AC signal is positive from the center of the hysteresis loop of the piezoelectric layer. A vibration type gyro sensor characterized by being set at a position shifted in the direction.
2. 2. The vibration type gyro sensor according to 1 above, wherein a shift amount of the central electric field intensity of the AC signal is 15 V / μm or less.
3. 2. The vibration type gyro sensor according to 1, wherein the first electrode layer is connected to a ground potential.
4). 2. The vibration type gyro sensor according to 1, wherein a plurality of the vibration elements are mounted on the support substrate with different axial directions of the vibrator portions.
5. 5. The vibration type gyro sensor according to 4, wherein each of the vibration elements is driven with an operating frequency separated by 1 kHz or more.
6). 5. The vibration type gyro sensor according to the above 4, wherein a circuit element and a plurality of electronic components are mounted on the support substrate in addition to the plurality of vibration elements.
7). 7. The vibration type gyro sensor according to 6, wherein the circuit element is an IC component, and an intermediate region of a straight line connecting the mounting regions of the plurality of vibration elements is a main mounting region of the IC component.

  DESCRIPTION OF SYMBOLS 1 ... Vibration type gyro sensor, 2 ... Support substrate, 2-1 ... 1st main surface, 2-2 ... 2nd main surface, 4 ... Land, 5 ... Wiring pattern, 7 ... IC circuit element, 8 ... Electronic component, DESCRIPTION OF SYMBOLS 11 ... Space | interval structure recessed part, 12, 14 ... Load buffering groove part, 15 ... Cover member, 20, 20X, 20Y ... Vibrating element, 21 ... Silicon substrate, 22 ... Base part, 22-2 ... Mounting surface, 23 ... Vibrator part, 23-2 ... substrate facing surface, 25 ... terminal part, 26 ... gold bump, 27 ... reference electrode layer, 28 ... piezoelectric thin film layer, 29 ... drive electrode layer, 30 ... detection electrode, 31 ... lead, 32 ... for alignment Mark, 33 ... Silicon oxide film, 37 ... Etching recess, 38 ... Die or fram part, 39 ... Outline groove, 45 ... Insulating protective layer, 46, 48 ... Alumina layer, 47 ... Silicon oxide layer, 50 ... Drive detection circuit part , 100 ... control substrate, 133 ... etching inclination Surface

Claims (14)

A vibration type gyro sensor,
A base having a plurality of terminal portions formed therein, and at least two vibration elements for detecting vibrations in different axial directions,
A single IC component for detecting the drive of the at least two vibrating elements;
A first surface on which a wiring pattern having a plurality of lands connected to the plurality of terminal portions and the IC component of each of the vibration elements is formed; a back side of the first surface; A support substrate having a second surface facing the substrate and having a plurality of external connection terminals formed on the land of the external substrate for reflow surface mounting of the vibration type gyro sensor.
At least one base of the at least two vibration elements is mounted on a corner portion of the support substrate,
When the first surface of the support substrate is divided into first to fourth quadrants, a vibration type gyro sensor to which a part of the mounting region of the IC component belongs to each quadrant. The vibration type gyro sensor according to claim 1,
Each of the vibration elements is driven at a frequency of 1 kHz or more. The vibration-type gyro sensor according to claim 2,
Each of the vibration elements is driven by a vibration type gyro sensor that is driven with an operating frequency separated from 2 kHz to 3 kHz. The vibration type gyro sensor according to claim 1,
The vibration element includes a vibrator unit that is integrally protruded in a cantilever shape from a side peripheral part of the base part. The vibration type gyro sensor according to claim 1,
A vibration type gyro sensor in which the base portions of the two vibration elements are respectively mounted on opposite corner portions of the support substrate. The vibration type gyro sensor according to claim 4,
The vibrator portion of each vibration element has a substrate facing surface that forms the same surface as the mounting surface of the base portion,
A first electrode layer, a piezoelectric layer stacked on the first electrode layer, and a second electrode layer stacked on the piezoelectric layer are respectively formed on the substrate facing surface. Gyro sensor. The vibration type gyro sensor according to claim 1,
A vibration type gyro sensor in which the two vibration elements are mounted with the vibrator portions arranged on axes different from each other by 90 °. The vibration type gyro sensor according to claim 4,
In each of the vibration elements, metal bumps are provided on a plurality of terminal portions formed on the mounting surface of the base portion, and the plurality of terminal portions are connected to the land via these metal bumps. Gyro sensor. The vibration type gyro sensor according to claim 1,
The support substrate is a ceramic substrate. The vibration type gyro sensor according to claim 1,
A vibration type gyro sensor in which a processing mark for adjusting a resonance frequency is formed on a tip side of the vibrator portion of the vibration element. The vibration type gyro sensor according to claim 1,
Each vibration element is provided with an alignment mark for alignment with the support substrate. The vibration type gyro sensor according to claim 1,
A vibration type gyro sensor in which a concave portion is formed on the support substrate to maintain a distance from the vibrator. The vibration type gyro sensor according to claim 1,
A vibration-type gyro sensor in which the first surface of the support substrate is covered with a light-shielding cover member. The vibration type gyro sensor according to claim 13,
The cover member is bonded to the support substrate by bonding.

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