JP2018093553A - Electronic device, electronic apparatus, and movable body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic device suppressing reduction in vibration characteristics of a vibration piece and achieving reduction in size, and to provide an electronic apparatus provided with the electronic device, and a movable body.SOLUTION: A vibrator (electronic device) 1 includes: a vibration piece 2 including vibration arms 28, 29, and 30; a base portion 3 supporting the vibration piece 2 and having a rectangular shape as viewed in a plan view; and a lid body 7 provided at an opposite side of the vibration piece 2 to the base portion 3. Directions where long sides 302 and short sides 303 of the base portion 3 extend and a direction where the vibration arms 28, 29, and 30 extend intersect with one another. When an angle formed by the vibrating arms 28, 29, 30 and a Y axis direction is represented by θ, the angle θ is more than 0° and less than 90°.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electronic device, an electronic apparatus, and a moving object.

  As an electronic device such as an oscillator or a gyro sensor, an electronic device including a tuning fork type vibrator having a plurality of vibrating arms is known.

  For example, the vibrator described in Patent Document 1 includes a single crystal silicon substrate on which a vibrating arm is formed, a reference electrode, a piezoelectric body, a drive electrode, and a detection electrode. In this vibrator, when a voltage is applied between the reference electrode and the drive electrode, the piezoelectric body is expanded and contracted, and the vibrating arm is vibrated in the thickness direction of the single crystal silicon substrate. When an angular velocity is applied in the longitudinal direction of the vibrating arm in such a state, a Coriolis force is generated in a direction perpendicular to the vibrating direction of the vibrating arm. The applied angular velocity can be detected by outputting the charge generated in the piezoelectric body by the Coriolis force as a signal from the detection electrode.

  In recent years, there has been a strong demand for downsizing of such electronic devices. However, there is a concern that the vibration characteristics of the vibrator deteriorate as the miniaturization progresses.

JP-A-2005-241382

  An object of the present invention is to provide an electronic device in which a reduction in vibration characteristics of a resonator element is suppressed and downsizing, and an electronic apparatus and a moving body including the electronic device.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following application examples.

[Application Example 1]
The electronic device of this application example includes a vibrating piece including a vibrating arm;
A base portion for supporting the vibrating piece,
In a plan view, a direction in which the side of the base portion extends intersects with a direction in which the vibrating arm extends.

  As a result, a reduction in vibration characteristics of the resonator element is suppressed, and an electronic device with a reduced size can be obtained.

[Application Example 2]
In the electronic device according to this application example, it is preferable that the vibrating arm is supported by the base portion at one end thereof.

  Thereby, since the vibrating arm can be reliably supported, it is possible to prevent the vibration excited by the vibrating arm from becoming unstable.

[Application Example 3]
In the electronic device of this application example, it is preferable that the vibrating arm bend and vibrate in the thickness direction.
Thereby, stable vibration can be realized.

[Application Example 4]
In the electronic device according to this application example, it is preferable that the vibrating piece includes the three vibrating arms.

  Accordingly, by causing the two adjacent vibrating arms to bend and vibrate in directions opposite to each other, leakage vibrations generated from the two sets of the two adjacent vibrating arms can be canceled out from each other. As a result, an electronic device capable of preventing vibration leakage and outputting a signal with high frequency accuracy is obtained.

[Application Example 5]
In the electronic device of this application example, the constituent material of the vibrating arm preferably includes silicon.
Thereby, a vibrating arm having excellent vibration characteristics can be realized at a relatively low cost.

[Application Example 6]
In the electronic device according to this application example, the constituent material of the base portion preferably includes silicon.
Thereby, a base part can be formed with high dimensional accuracy by etching.

[Application Example 7]
In the electronic device of this application example, the constituent material of the base portion includes single crystal silicon,
The base portion has a side extending along the crystal orientation <110> of the single crystal silicon, and a direction in which the vibrating arm extends is along the crystal orientation <100> of the single crystal silicon. Preferably it is.

  As a result, a state where the direction in which the side of the base portion extends and the direction in which the vibrating arm extends can be easily and accurately created using the etching anisotropy of single crystal silicon. For this reason, it is possible to obtain an electronic device in which the dimensional accuracy of each part is high and the vibration characteristics are sufficiently close to the design value. As a result, a small and highly reliable electronic device can be obtained.

[Application Example 8]
In the electronic device of this application example, it is preferable to have a terminal portion that is aligned with the resonator element in plan view.
Thereby, an electronic device with high mountability is obtained.

[Application Example 9]
In the electronic device according to this application example, it is preferable that the electronic device includes a lid portion that covers the vibrating piece and is connected to the base portion.
Thereby, a vibrating piece can be protected.

[Application Example 10]
An electronic apparatus according to this application example includes the electronic device according to the application example described above.
As a result, a highly reliable electronic device can be obtained.

[Application Example 11]
The moving body of this application example includes the electronic device of the application example described above.
Thereby, a mobile body with high reliability is obtained.

It is a perspective view showing a vibrator to which an embodiment of an electronic device of the present invention is applied. FIG. 2 is a transmission top view of the vibrator shown in FIG. 1. It is the sectional view on the AA line in FIG. It is the BB sectional view taken on the line in FIG. FIG. 8 is a cross-sectional view for explaining the method for manufacturing the vibrator shown in FIG. 1 and the like. FIG. 8 is a cross-sectional view for explaining the method for manufacturing the vibrator shown in FIG. 1 and the like. FIG. 8 is a cross-sectional view for explaining the method for manufacturing the vibrator shown in FIG. 1 and the like. FIG. 14 is a perspective view illustrating a configuration of a mobile (or notebook) personal computer to which an electronic apparatus including the electronic device of the invention is applied. It is a perspective view which shows the structure of the mobile telephone (PHS is also included) to which the electronic device provided with the electronic device of this invention is applied. It is a perspective view which shows the structure of the digital still camera to which the electronic device provided with the electronic device of this invention is applied. 1 is a perspective view schematically showing an automobile as an example of a moving object of the present invention.

  Hereinafter, an electronic device, an electronic apparatus, and a moving body of the present invention will be described in detail based on embodiments shown in the accompanying drawings.

[Vibrator]
First, a vibrator to which an embodiment of the electronic device of the present invention is applied will be described.

  FIG. 1 is a perspective view showing a vibrator to which an embodiment of an electronic device of the present invention is applied. FIG. 2 is a transparent top view of the vibrator shown in FIG. 3 is a cross-sectional view taken along line AA in FIG. 4 is a cross-sectional view taken along line BB in FIG.

  In each figure, for convenience of explanation, an X axis, a Y axis, and a Z axis are illustrated as three axes orthogonal to each other. Hereinafter, a direction parallel to the X axis is referred to as an X axis direction, a direction parallel to the Y axis is referred to as a Y axis direction, and a direction parallel to the Z axis is referred to as a Z axis direction. In the following description, for convenience of explanation, the upper side in FIG. 3 is referred to as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”. In FIG. 3, for convenience of explanation, illustration of a part of the part included in the vibrator is omitted.

  A vibrator (electronic device) 1 shown in FIG. 1 includes a vibrating piece 2, a base portion 3 provided below the vibrating piece 2, and an intermediate layer 6 provided between the vibrating piece 2 and the base portion 3. And a lid 7 provided above the vibrating piece 2.

Hereinafter, each part which comprises the vibrator | oscillator 1 is demonstrated in detail sequentially.
(Vibration piece)
The vibrating substrate 21 shown in FIG. 2 has a substantially plate shape with the Z-axis direction as the thickness direction, and includes a base portion 27, three vibrating arms 28, 29, and 30, and a frame portion 26. .

  The resonator element 2 is a three-leg tuning fork type resonator element as shown in FIG. The resonator element 2 includes piezoelectric bodies 22, 23, 24 and terminal portions 41, 42 provided on the vibration substrate 21, and mass portions 51, 52, 53.

  The constituent material of the vibration substrate 21 is not particularly limited as long as it can exhibit desired vibration characteristics, and various piezoelectric materials and various non-piezoelectric materials can be used.

  Examples of the piezoelectric material include crystal, lithium tantalate, lithium niobate, lithium borate, and barium titanate. In particular, the piezoelectric material constituting the vibration substrate 21 is preferably quartz (X-cut plate, AT-cut plate, Z-cut plate, etc.). When the vibration substrate 21 is made of quartz, the vibration characteristics (particularly the frequency temperature characteristic) of the vibration substrate 21 can be made excellent. Further, the vibration substrate 21 can be formed with high dimensional accuracy by etching.

  Examples of the non-piezoelectric material include silicon, ceramics, and glass. In particular, as the non-piezoelectric material constituting the vibration substrate 21, various types of silicon such as single crystal silicon, polycrystalline silicon, and amorphous silicon are preferable. When the vibration substrate 21 is made of silicon, the vibration substrate 21 having excellent vibration characteristics can be realized at a relatively low cost. In addition, it is easy to integrate the resonator element 2 and other circuit elements by forming an integrated circuit on the base 27. In particular, in the case of single crystal silicon, the vibration substrate 21 can be formed with high dimensional accuracy by etching.

(Base part)
The base portion 3 has a substantially plate shape with the Z-axis direction as the thickness direction, and includes a recess 31 that opens to the + Z side. Specifically, the base portion 3 includes a flat plate body 32 and a frame body 33 provided on the outer peripheral portion of the upper surface of the plate body 32, and a space inside the frame body 33 is a recess 31. It corresponds to. In addition, the outer shape of the frame 33 may be different from the outer shape of the vibration substrate 21, but in the present embodiment, the outer shape of the frame body 33 is the same.

  The constituent material of the base portion 3 is not particularly limited as long as it has mechanical strength necessary to support the vibration substrate 21. For example, various silicon materials, various ceramic materials, various glass materials, and the like are used. Can do.

  Of these, silicon is particularly preferably used, and single crystal silicon is more preferably used. According to silicon, the base part 3 can be efficiently formed with high dimensional accuracy by etching.

  The base portion 3 according to the present embodiment is made of single crystal silicon. The base portion 3 has a rectangular shape (rectangular shape) in plan view, and its major axis is parallel to the Y-axis direction and its minor axis is parallel to the X-axis direction. In addition, the crystal orientation <110> of the single crystal silicon constituting the base portion 3 is parallel to each of the X axis direction and the Y axis direction. That is, the long side 302 and the short side 303 of the base part 3 are parallel to the crystal orientation <110> of the single crystal silicon constituting the base part 3, respectively. The crystal orientation <110> is a collective expression of the crystal orientation [110] and the equivalent crystal orientation.

  In addition, the base part 3 should just be a rectangle in planar view. In addition to the rectangle, the rectangle includes a square, a shape conforming to the rectangle and the square, and the like. A shape conforming to a rectangle or square is a quadrangle whose inner angle is shifted from 90 ° (for example, a quadrangle whose inner angle is shifted within the range of about 90 ± 5 °), or a rectangle whose corners are chamfered or rounded. And so on.

  Further, the concave portion 31 is provided corresponding to a region inside the frame portion 26 of the vibration substrate 21. That is, the recess 31 is provided so as to include the base 27 and the vibrating arms 28, 29, 30 in a plan view from a direction parallel to the Z axis. As a result, the vibrating arms 28, 29, 30 can be displaced downward in FIG.

(Lid)
The lid body 7 (lid body portion) has a substantially plate shape with the Z-axis direction as the thickness direction, and includes a recess 71 that opens to the −Z side. Specifically, the lid body 7 includes a flat plate body 72 and a frame body 73 provided on the outer peripheral portion of the lower surface of the plate body 72, and a space inside the frame body 73 is a recess 71. It corresponds to.

  The constituent material of the lid 7 is not particularly limited as long as it has a mechanical strength necessary to protect the resonator element 2. For example, various silicon materials, various ceramic materials, various glass materials, various metal materials Etc. can be used.

  Of these, single crystal silicon is particularly preferably used. According to the single crystal silicon, the lid 7 can be efficiently formed with high dimensional accuracy by etching.

  Further, the recess 71 is provided corresponding to a region inside the frame portion 26 of the vibration substrate 21. That is, the recess 71 is provided so as to correspond to the recess 31 in a plan view from a direction parallel to the Z axis. Thereby, the vibrating arms 28, 29, and 30 can be displaced upward in FIG.

  In addition, the cover body 7 has comprised the hexagon in planar view, as shown in FIG. The lid body 7 is configured to be smaller than the vibration substrate 21 and the base portion 3, and a part of the vibration substrate 21 protrudes from the lid body 7 when the vibrator 1 is viewed from above. Terminal portions 41 and 42 are provided at the protruding portion.

(Middle layer)
The intermediate layer 6 is provided between the vibration substrate 21 and the base portion 3. The frame portion 26 and the base portion 3 of the vibration substrate 21 are joined by the intermediate layer 6. Thereby, the frame part 26 and the base part 3 of the vibration substrate 21 are hermetically sealed.

  Further, the lid body 7 is bonded to the frame portion 26 of the vibration substrate 21. Thereby, the frame part 26 and the lid body 7 of the vibration substrate 21 are hermetically sealed. A method for joining the lid 7 and the vibration substrate 21 is not particularly limited, and examples thereof include direct joining, anodic joining, metal joining using a brazing material or solder, welding, and caulking.

  By joining the base portion 3, the vibration substrate 21 and the lid body 7 in this manner, the space S defined by the recessed portion 31, the recessed portion 71 and the frame portion 26 is isolated from the outside. In addition, by joining the intermediate layer 6 and the vibration substrate 21 and joining the vibration substrate 21 and the base portion 3 under reduced pressure or an inert gas atmosphere, the space S is in a reduced pressure state or filled with an inert gas. Can be kept in a state.

(Vibration substrate)
Here, the vibration substrate 21 has a substantially plate shape whose thickness direction is the Z-axis direction. Further, vibrating arms 28, 29, and 30 extend from the base portion 27 in the same direction.

  The extending direction of the vibrating arms 28, 29, 30 intersects with the extending direction of the long side 302 of the base portion 3. In the present embodiment, when the angle between the extending direction of the vibrating arms 28, 29, and 30 and the Y-axis direction is θ, the angle θ is greater than 0 ° and less than 90 °. By setting the extending direction of the vibrating arms 28, 29, and 30 and the extending direction of the long side 302 of the base portion 3 so as to satisfy such conditions, vibration can be performed without increasing the outer size of the base portion 3. The lengths of the arms 28, 29, and 30 can be secured relatively long. In other words, since the diagonal line of the base portion 3 is longer than the long side 302, the length of the vibrating arms 28, 29, 30 is shortened by extending the vibrating arms 28, 29, 30 along that direction. Therefore, the base 3 can be downsized. As a result, the small vibrator 1 can be realized while suppressing deterioration of vibration characteristics such as an increase in crystal impedance (CI value) and a decrease in resonance sharpness (Q value).

  The angle θ formed by the extending direction of the vibrating arms 28, 29, and 30 and the Y axis direction may be more than 0 ° and less than 90 ° as described above, but is preferably 40 ° or more and 50 ° or less, and more preferably Is between 44 ° 30 'and 45 ° 30'. By setting the angle θ within the above range, the lengths of the vibrating arms 28, 29, and 30 can be secured sufficiently long without increasing the outer size of the base portion 3, so that the vibration characteristics are deteriorated. Suppression and downsizing of the vibrator 1 can be made more highly compatible.

  In the above description, the angle is defined by θ being the angle formed by the extending direction of the vibrating arms 28, 29, 30 and the Y-axis direction, but this angle θ is defined by the extending of the vibrating arms 28, 29, 30. It may be an angle formed by the direction and the X-axis direction. Even in this case, the angle θ is preferably within the above range.

  In the present embodiment, the extending direction of the vibrating arms 28, 29, and 30 is parallel to the crystal orientation <100> of single crystal silicon constituting the base portion 3. The crystal orientation <100> collectively represents the crystal orientation [100] and the equivalent crystal orientation (for example, [010] and [001]).

  Therefore, in this embodiment, the angle θ formed by the extending direction of the vibrating arms 28, 29, 30 and the Y-axis direction is the crystal orientation <110> and crystal orientation <100> of the single crystal silicon constituting the base portion 3. It can be said that it is equal to the angle formed by. As described above, the direction in which the long side 302 and the short side 303 of the base part 3 extend is parallel to the crystal orientation <110> of the single crystal silicon constituting the base part 3, and the vibrating arms 28, 29, and 30 extend. By making the direction parallel to the crystal orientation <100> of the single crystal silicon constituting the base portion 3, the state where the former direction and the latter direction intersect can be obtained using the etching anisotropy of the single crystal silicon. It can be created easily and accurately. For this reason, in the vibrator 1 according to the present embodiment, the dimensional accuracy of each part is increased, and the vibration characteristics are easily brought close to the design value. As a result, a small and highly reliable vibrator 1 can be realized.

  The vibrating arms 28, 29, and 30 are extended in parallel to each other and aligned in a direction orthogonal to the extending direction of the vibrating arms 28, 29, and 30. Among these, the vibrating arm 30 is located between the vibrating arm 28 and the vibrating arm 29.

  In these vibrating arms 28, 29, and 30, the end portion (base end portion) on the base portion 27 side is a fixed end, and the end portion (tip end portion) opposite to the base portion 27 is a free end. Further, the end portion of the base portion 27 opposite to the vibrating arms 28, 29, and 30 is connected to the frame portion 26. The frame portion 26 has a frame shape in plan view, and a base portion 27 and vibrating arms 28, 29, and 30 are disposed therein. The frame portion 26, the base portion 27, and the vibrating arms 28, 29, and 30 are integrally formed. As described above, since the frame portion 26 is supported so as to be sandwiched between the base portion 3 and the lid body 7, the base end portions of the vibrating arms 28, 29, and 30 are connected to the base portion 27 and the frame portion 26. It will be supported by the base part 3 via this. Thereby, since the vibrating arms 28, 29, and 30 can be reliably supported, it is possible to suppress the vibration excited by the vibrating arms 28, 29, and 30 from becoming unstable.

  In addition, each of the vibrating arms 28, 29, and 30 has a constant width over the entire region in the longitudinal direction. In addition, each vibrating arm 28, 29, 30 may have portions with different widths.

  The vibrating arms 28, 29, and 30 are formed to have the same length. The lengths of the vibrating arms 28, 29, and 30 are set according to the width and thickness of the vibrating arms 28, 29, and 30, and may be different from each other.

  In addition, you may provide the mass part (hammer head) with a larger cross-sectional area than a base end part in each front-end | tip part of the vibrating arms 28, 29, and 30 as needed. In this case, the vibrating piece 2 can be made smaller, and the bending vibration frequency of the vibrating arms 28, 29, and 30 can be further reduced.

(Parts by mass)
As shown in FIGS. 2 and 3, a mass part 51 is provided on the upper surface 281 of the vibrating arm 28. The mass portion 51 is for adjusting the resonance frequency of the resonating arm 28 by reducing the mass, for example, by removing part or all of the mass portion 51 by irradiation with energy rays. Similarly, a mass part 52 is provided on the upper surface 291 of the vibrating arm 29, and a mass part 53 is provided on the upper surface 301 of the vibrating arm 30.

(Piezoelectric element)
As shown in FIGS. 2 to 4, the piezoelectric body 22 is provided on the vibrating arm 28, the piezoelectric body 23 is provided on the vibrating arm 29, and the vibrating arm 30 is further provided. Is provided with a piezoelectric body 24. As a result, when the vibrating arms 28, 29, 30 themselves do not have piezoelectricity, or the vibrating arms 28, 29, 30 have piezoelectricity, the direction of the polarization axis or crystal axis is the Z axis. Even if it is not suitable for bending vibration in the direction, each vibrating arm 28, 29, 30 can be bent and vibrated in the Z-axis direction relatively easily and efficiently. Thereby, stable vibration can be realized. In addition, since the vibrating arms 28, 29, and 30 have piezoelectricity and the directions of the polarization axis and the crystal axis are not limited, the selection range of the materials of the vibrating arms 28, 29, and 30 is widened. Therefore, the resonator element 2 having desired vibration characteristics can be realized relatively easily.

  The piezoelectric body 22 has a function of expanding and contracting by energization to bend and vibrate the vibrating arm 28 in the Z-axis direction. In addition, the piezoelectric body 23 has a function of expanding and contracting by energization to bend and vibrate the vibrating arm 29 in the Z-axis direction. In addition, the piezoelectric body 24 has a function of expanding and contracting by energization to bend and vibrate the vibrating arm 30 in the Z-axis direction.

  As shown in FIG. 4, such a piezoelectric body 22 includes an insulating layer 221, a first electrode layer 222, a piezoelectric layer (piezoelectric thin film) 223, and a second electrode layer 224 on the vibrating arm 28. They are stacked in order. Similarly, the piezoelectric body 23 is configured by laminating an insulator layer 231, a first electrode layer 232, a piezoelectric layer (piezoelectric thin film) 233, and a second electrode layer 234 on the vibrating arm 29 in this order. ing. In addition, the piezoelectric body 24 is configured by laminating an insulating layer 241, a first electrode layer 242, a piezoelectric layer (piezoelectric thin film) 243, and a second electrode layer 244 in this order on the vibrating arm 30. Yes.

  Hereinafter, each layer constituting the piezoelectric body 22 will be sequentially described in detail. Note that the configuration of each layer of the piezoelectric bodies 23 and 24 is the same as that of the piezoelectric body 22, and thus the description thereof is omitted.

(First electrode layer)
The first electrode layer 222 is provided from the base 27 to the vibrating arm 28 along the extending direction of the vibrating arm 28.

  In the present embodiment, the length of the first electrode layer 222 is shorter than the length of the vibrating arm 28 on the vibrating arm 28.

  Such a first electrode layer 222 includes gold (Au), gold alloy, platinum (Pt), aluminum (Al), aluminum alloy, silver (Ag), silver alloy, chromium (Cr), chromium alloy, copper ( Cu), molybdenum (Mo), niobium (Nb), tungsten (W), iron (Fe), titanium (Ti), titanium nitride (TiN), cobalt (Co), zinc (Zn), zirconium (Zr), etc. It can be formed of a transparent electrode material such as ITO or ZnO.

  The average thickness of the first electrode layer 222 is not particularly limited, but is preferably about 1 nm to 300 nm, for example, and more preferably about 10 nm to 200 nm. This prevents the first electrode layer 222 from adversely affecting the drive characteristics of the piezoelectric body 22 and the vibration characteristics of the vibrating arm 28, and has excellent conductivity of the first electrode layer 222 as described above. It can be.

(Insulator layer)
Depending on the constituent material of the vibration substrate 21, it is necessary to electrically insulate between the first electrode layer 222 and the vibration substrate 21. Therefore, when the vibration substrate 21 is made of silicon as a semiconductor as in the present embodiment, it is preferable to provide the insulator layer 221 between the first electrode layer 222 and the vibration substrate 21.
The insulator layer 221 is made of, for example, silicon oxide, silicon nitride, aluminum nitride, or the like.

  The average thickness of the insulator layer 221 is not particularly limited as long as it is a thickness that can electrically insulate between the first electrode layer 222 and the vibration substrate 21, but for example, about 1 nm to 10 μm. Is preferred. If the thickness is less than the lower limit, depending on the constituent material of the insulator layer 221, the effect of preventing a short circuit may be reduced. On the other hand, if the thickness exceeds the upper limit, the insulator layer Depending on the constituent material 221, the characteristics of the piezoelectric body 22 may be adversely affected.

(Piezoelectric layer)
The piezoelectric layer 223 is provided on the first electrode layer 222 along the extending direction of the vibrating arm 28. The length of the piezoelectric layer 223 in the extending direction of the vibrating arm 28 is preferably substantially equal to the length of the first electrode layer 222 in the same direction. Thereby, the piezoelectric layer 223 can be homogenized in the longitudinal direction of the vibrating arm 28.

  In addition, an end portion on the base portion 27 side of the piezoelectric layer 223 (that is, a base end portion of the piezoelectric layer 223) is provided so as to straddle the boundary portion between the vibrating arm 28 and the base portion 27. Thereby, the driving force of the piezoelectric body 22 can be efficiently transmitted to the vibrating arm 28. In addition, a sudden change in rigidity at the boundary between the vibrating arm 28 and the base 27 can be mitigated. Therefore, the Q value of the resonator element 2 can be increased.

Examples of the constituent material (piezoelectric material) of the piezoelectric layer 223 include zinc oxide (ZnO), aluminum nitride (AlN), lithium tantalate (LiTaO ₃ ), lithium niobate (LiNbO ₃ ), and niobic acid. Examples include potassium (KNbO ₃ ), lithium tetraborate (Li ₂ B ₄ O ₇ ), barium titanate (BaTiO ₃ ), and PZT (lead zirconate titanate), but it is preferable to use AlN or ZnO.

  Among them, it is preferable to use ZnO or AlN as a constituent material of the piezoelectric layer 223. ZnO (zinc oxide) and aluminum nitride (AlN) are excellent in c-axis orientation. Therefore, the CI value of the resonator element 2 can be reduced by configuring the piezoelectric layer 223 with ZnO as a main material. Moreover, these materials can be formed into a film, for example by the reactive sputtering method.

  The average thickness of the piezoelectric layer 223 is preferably about 50 nm to 3000 nm, and more preferably about 200 nm to 2000 nm. Accordingly, it is possible to improve the drive characteristics of the piezoelectric body 22 while preventing the piezoelectric body layer 223 from adversely affecting the vibration characteristics of the vibrating arm 28.

(Second electrode layer)
The second electrode layer 224 is provided along the extending direction of the vibrating arm 28.

  Further, the length of the second electrode layer 224 in the extending direction of the vibrating arm 28 is substantially equal to the length of the piezoelectric layer 223. Accordingly, the entire region of the piezoelectric layer 223 can be expanded and contracted in the extending direction of the vibrating arm 28 by an electric field generated between the second electrode layer 224 and the first electrode layer 222 described above. Therefore, vibration efficiency can be increased.

  Such a second electrode layer 224 can be formed using a material appropriately selected from the materials listed as the constituent materials of the first electrode layer 222.

  The average thickness of the second electrode layer 224 is not particularly limited, but is preferably about 1 nm to 300 nm, for example, and more preferably about 10 nm to 200 nm. Accordingly, the second electrode layer 224 is made excellent in conductivity while preventing the second electrode layer 224 from adversely affecting the driving characteristics of the piezoelectric body 22 and the vibration characteristics of the vibrating arm 28. it can.

(Terminal part)
Further, the terminal portions 41 and 42, the connection wirings 43 and 44, and the like can be formed using a material appropriately selected from those mentioned as the constituent materials of the first electrode layer 222 described above. Further, these can be formed simultaneously with the first electrode layers 222, 232, 242 or the second electrode layers 224, 234, 244.

  In the present embodiment, the base portion 3 has a rectangular shape in plan view, while the lid body 7 has a hexagonal shape. Since the lid body 7 only needs to cover the space S, it is not necessary to match the outer shape of the lid body 7 to the base portion 3. Can be secured. In other words, the two terminal portions 41 and 42 and the resonator element 2 are arranged so as to be aligned when viewed in plan while seeing through the vibrator 1. As a result, in the vibrator 1, since the terminal portions 41 and 42 can be arranged on the upper surface, the mountability can be improved. In addition, since the distance between the terminal portion 41 and the terminal portion 42 can be ensured naturally, it is easy to prevent a short circuit between the terminal portion 41 and the terminal portion 42, and wiring or the like (not shown) is connected to the terminal portions 41 and 42. Can be easily performed.

  In the resonator element 2 having such a configuration, when a voltage (voltage for vibrating the vibrating arms 28, 29, 30) is applied between the terminal portion 41 and the terminal portion 42, the first electrode layer 222, 232 and the second electrode layer 244, and the first electrode layer 242 and the second electrode layer 224, 234 have opposite polarities, and the piezoelectric layers 223, 233, 243 are each provided with Z An axial voltage is applied. Thereby, the vibrating arms 28, 29, and 30 can be flexibly vibrated at a certain frequency (resonance frequency) by the inverse piezoelectric effect of the piezoelectric material. At this time, the vibrating arms 28 and 29 bend and vibrate in the same direction, and the vibrating arm 30 bends and vibrates in the direction opposite to the vibrating arms 28 and 29.

  In this way, by causing the two adjacent vibrating arms to bend and vibrate in the opposite directions, leakage vibrations generated by the two adjacent vibrating arms 28, 30 and 29, 30 can be canceled out. As a result, it is possible to obtain the vibrator 1 that can prevent vibration leakage and output a signal with high frequency accuracy.

  Further, when the vibrating arms 28, 29, and 30 are bent and vibrated, a voltage is generated between the terminal portions 41 and 42 at a certain frequency due to the piezoelectric effect of the piezoelectric material. Utilizing these properties, the resonator element 2 can generate an electrical signal that vibrates at a resonance frequency.

[Method of manufacturing vibrator]
Next, a method for manufacturing the vibrator shown in FIG.

  5 to 7 are cross-sectional views for explaining a method of manufacturing the vibrator 1 shown in FIG. In the following description, for convenience of explanation, the upper part of FIGS. 5 and 6 is referred to as “upper” and the lower part is referred to as “lower”. Also, in FIGS. 5 to 7, illustration of electrodes, wirings, terminal portions, and the like is omitted in order to prevent the drawings from becoming complicated.

  The method of manufacturing the vibrator 1 includes: [A] a step of forming the vibration substrate 21, [B] a step of etching the substrate for forming the base portion 3 to obtain the base portion 3, and [C] a lid. Joining the body 7 and the vibration substrate 21. Hereinafter, each step will be described.

[A]
First, a substrate for forming the vibration substrate 21 is prepared, and the vibration substrate 21 is formed by etching the substrate.

  Here, by using an SOI (Silicon On Insulator) substrate, a laminated substrate in which a substrate for forming the vibration substrate 21 and a substrate for forming the base portion 3 are bonded via an intermediate layer can be easily obtained. Can be prepared.

The SOI substrate 9 shown in FIG. 5A has a first Si layer (handle layer) 91, a SiO ₂ layer (box layer) 92, and a second Si layer (device layer) 93 stacked in this order. It is a substrate. In the present embodiment, the base portion 3 is formed from the first Si layer 91, the intermediate layer 6 is formed from the SiO ₂ layer 92, and the vibration substrate 21 is formed from the second Si layer 93. This procedure will be described below.

  First, piezoelectric bodies 22, 23 and 24 are formed on the SOI substrate 9. In FIG. 5, the insulator layer is not shown.

  Next, the vibrating arms 28, 29, 30 and the like are formed on the second Si layer 93 of the SOI substrate 9 by etching. This etching process may be a wet etching process, but is preferably a dry etching process. As a result, the etching process can be performed without being affected by the etching anisotropy when the second Si layer 93 is subjected to wet etching, so that the vibrating arms 28, 29, 30 and the like with high dimensional accuracy are formed. be able to. Further, in this etching process, as shown in FIG. 5B, a region 921 around the vibrating arms 28, 29, 30 and the like is dug out in the second Si layer 93.

  In addition, when performing the etching process with respect to the SOI substrate 9, a photolithography technique is used together. In the photolithographic technique, a projection exposure apparatus such as a stepper or a scanner is used to perform exposure processing on a pattern corresponding to a processing pattern. In the case of the present embodiment, it is necessary when a plurality of vibration substrates 21 are produced from one silicon wafer by scanning the exposure mask pattern in parallel with <110> in the projection exposure apparatus (multiple picking). Divided exposure processing can be performed efficiently. That is, when performing a divided exposure process with a general projection exposure apparatus, the scanning direction of the exposure mask pattern is often limited to a direction parallel or perpendicular to the crystal orientation of the silicon wafer. For this reason, the manufacturing method of the vibrator 1 according to the present embodiment is useful as a method capable of performing the divided exposure process efficiently even when a general projection exposure apparatus is used.

Next, an oxide film is formed on the SOI substrate 9. Thus, an oxide film 931 as shown in FIG. 5C is formed on the surface of the second Si layer 93 and on the SiO ₂ layer 92 in the region 921. This oxide film 931 functions as a protective film for protecting the second Si layer 93 in an etching process described later.
For example, a sputtering method is used for forming the oxide film.

Next, the oxide film 931 and the SiO ₂ layer 92 in the region 921 are partially etched. Thereby, as shown in FIG. 6D, the oxide film 931 and the SiO ₂ layer 92 in the region 921 are partially removed.

  For this etching process, for example, a region other than the region 921 is masked, and then a dry etching method or a wet etching method is used.

[B]
Next, an etching process is performed on the first Si layer 91 of the SOI substrate 9 subjected to the oxidation treatment. This etching process is performed using the second Si layer 93 and the SiO ₂ layer 92 as a mask. In other words, a portion of the first Si layer 91 corresponding to the region 921 is etched. Then, by appropriately adjusting the etching processing conditions, it is possible to perform processing so as to go under the second Si layer 93 and the SiO ₂ layer 92. As a result, the recess 31 shown in FIG. 6E can be formed.

  In the vibrator 1 according to the present embodiment, as shown in FIG. 7, the long side 302 and the short side 303 of the base part 3 are parallel to the crystal orientation <110> of the single crystal silicon constituting the base part 3. . On the other hand, the extending directions of the vibrating arms 28, 29, and 30 are parallel to the crystal orientation <100> of the single crystal silicon constituting the base portion 3.

  Here, in the case of anisotropic wet etching, the etching rate of the crystal plane {111} of Si is much slower than the etching rate of the crystal plane {100} and the crystal plane {110}. For this reason, in the etching process by anisotropic wet etching, when the crystal plane {111} appears, the etching process substantially stops at that time.

  As shown in FIG. 7, when the extending directions of the vibrating arms 28, 29, 30 are parallel to the crystal orientation <100> of the single crystal silicon constituting the base portion 3, the vibrating arms 28, 29, 30, etc. By performing anisotropic wet etching through a mask having the surrounding region 921 as an opening, the processing marks do not stay below the region 921, but the vibrating arms 28, 29, until the crystal plane {111} appears. 30 and the lower part of the frame part 26 are formed. As a result, the recess 31 provided in the base portion 3 extends not only below the region 921 but also below the vibrating arms 28, 29, 30 and the frame portion 26 located behind the mask. In this way, the concave portion 31 shown in FIG. 6E is formed, and the base portion 3 is obtained.

  According to such a method, the vibrating arms 28, 29, and 30 can be formed with high processing accuracy while using an SOI substrate with high dimensional accuracy. Therefore, the vibrator 1 having excellent vibration characteristics is efficiently manufactured. be able to.

  Examples of the etchant used for anisotropic wet etching include tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH), ethylenediamine-pyrocatechol-water (EDP), and hydrazine.

Next, the oxide film 931 is removed.
For removing the oxide film 931, for example, a wet etching method using buffered hydrofluoric acid (BHF) or the like is used.
Thereafter, wiring, terminal portions and the like (not shown) are formed.

[C]
Next, the lid body 7 is prepared. Then, the lid body 7 and the vibration substrate 21 are joined. Thereby, the vibrator 1 shown in FIG. 6F is obtained.

  Although the configuration and the manufacturing method of the vibrator 1 have been described above, the configuration of the vibrator 1 is not limited to the present embodiment.

  For example, the number of vibrating arms 28, 29, and 30 included in the vibrating piece 2 is not limited to three, and may be two or four or more.

  The vibrator 1 may be used as a sensor device that detects physical quantities such as acceleration, angular velocity, and pressure.

  Further, the vibrator 1 can be manufactured without using the SOI substrate 9. In this case, for example, a Si substrate is prepared as a substrate for forming the base portion 3, and an oxide film is formed by performing an oxidation treatment thereon. Next, a Si film is formed on the oxide film. Thereby, a substrate substantially equivalent to the SOI substrate can be manufactured. Examples of the Si film include a polycrystalline silicon film and an amorphous silicon film. Thereafter, the vibrator 1 can be manufactured as described above.

  Further, the vibration substrate 21 may not include the frame portion 26. For example, a structure in which the space S is defined by the base portion 3 and the lid 7 and the vibration substrate 21 is enclosed therein may be employed.

  Further, the positions of the terminal portions 41 and 42 are not limited to the upper surface of the vibration substrate 21, and may be, for example, the upper surface of the lid 7 or the lower surface of the base portion 3.

[Electronics]
Next, an electronic apparatus including the electronic device of the present invention (electronic apparatus of the present invention) will be described in detail with reference to FIGS.

  FIG. 8 is a perspective view illustrating a configuration of a mobile (or notebook) personal computer to which an electronic apparatus including the electronic device of the present invention is applied. In this figure, a personal computer 1100 includes a main body portion 1104 provided with a keyboard 1102 and a display unit 1106 provided with a display portion 100. The display unit 1106 is rotated with respect to the main body portion 1104 via a hinge structure portion. It is supported movably. Such a personal computer 1100 has a built-in vibrator 1 that functions as a filter, a resonator, a reference clock, and the like.

  FIG. 9 is a perspective view illustrating a configuration of a mobile phone (including PHS) to which an electronic apparatus including the electronic device of the present invention is applied. In this figure, a cellular phone 1200 includes a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206, and the display unit 100 is disposed between the operation buttons 1202 and the earpiece 1204. Such a cellular phone 1200 incorporates the vibrator 1 that functions as a filter, a resonator, and the like.

  FIG. 10 is a perspective view showing a configuration of a digital still camera to which an electronic apparatus including the electronic device of the present invention is applied. In this figure, connection with an external device is also simply shown. Here, an ordinary camera sensitizes a silver halide photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an imaging device such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.

  A display unit 100 is provided on the back of a case (body) 1302 in the digital still camera 1300, and is configured to display based on an imaging signal from the CCD. The display unit 100 displays a subject as an electronic image. Functions as a viewfinder. A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side (the back side in the drawing) of the case 1302.

  When the photographer confirms the subject image displayed on the display unit and presses the shutter button 1306, the CCD image pickup signal at that time is transferred and stored in the memory 1308. In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the figure, a television monitor 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the input / output terminal 1314 for data communication as necessary. Further, the imaging signal stored in the memory 1308 is output to the television monitor 1430 or the personal computer 1440 by a predetermined operation. Such a digital still camera 1300 incorporates a vibrator 1 that functions as a filter, a resonator, or the like.

  In addition to the personal computer (mobile personal computer) of FIG. 8, the mobile phone of FIG. 9, and the digital still camera of FIG. Inkjet printers), laptop personal computers, televisions, video cameras, video tape recorders, car navigation devices, pagers, electronic notebooks (including those with communication functions), electronic dictionaries, calculators, electronic game devices, word processors, workstations, televisions Telephone, crime prevention TV monitor, electronic binoculars, POS terminal, medical equipment (for example, electronic thermometer, blood pressure monitor, blood glucose meter, electrocardiogram measuring device, ultrasonic diagnostic device, electronic endoscope), fish detector, various measuring devices, instruments Class (eg vehicle, aviation , Gauges of a ship), can be applied to a flight simulator or the like.

[Moving object]
Next, a mobile body (the mobile body of the present invention) including the electronic device of the present invention will be described.

  FIG. 11 is a perspective view schematically showing an automobile as an example of the moving object of the present invention. A vibrator 1500 is mounted on the automobile 1500. The vibrator 1 is a keyless entry, immobilizer, car navigation system, car air conditioner, anti-lock brake system (ABS), air bag, tire pressure monitoring system (TPMS), engine control, hybrid car, The present invention can be widely applied to electronic control units (ECUs) such as battery monitors for electric vehicles and body posture control systems.

As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to this, The structure of each part can be substituted by the thing of the arbitrary structures which have the same function. .
Moreover, in this invention, arbitrary structures may be added to embodiment mentioned above.

DESCRIPTION OF SYMBOLS 1 Vibrator 2 Vibrating piece 3 Base part 6 Intermediate | middle layer 7 Lid body 9 SOI substrate 21 Vibrating board 22 Piezoelectric body 23 Piezoelectric body 24 Piezoelectric body 26 Frame part 27 Base 28 Vibrating arm 29 Vibrating arm 30 Resonating arm 31 Recessed part 32 Plate body 33 Frame body 41 Terminal section 42 Terminal section 43 Connection wiring 44 Connection wiring 51 Mass section 52 Mass section 53 Mass section 71 Recess 72 Plate body 73 Frame body 91 First Si layer 92 SiO ₂ layer 93 Second Si layer 100 Display section 221 Insulator layer 222 First electrode layer 223 Piezoelectric layer 224 Second electrode layer 231 Insulator layer 232 First electrode layer 233 Piezoelectric layer 234 Second electrode layer 241 Insulator layer 242 First electrode layer 243 Piezoelectric layer 244 Second electrode layer 281 Upper surface 291 Upper surface 301 Upper surface 302 Long side 303 Short side 921 Region 931 Oxide film 1100 Personal computer 1102 Keyboard 1104 Main unit 1106 Display unit 1200 Mobile phone 1202 Operation button 1204 Earpiece 1206 Earpiece 1300 Digital still camera 1302 Case 1304 Light receiving unit 1306 Shutter button 1308 Memory 1312 Video signal output terminal 1314 Input / output terminal 1430 Television monitor 1440 Personal computer 1500 Car S Space θ Angle

Claims (11)

A vibrating piece having a vibrating arm;
A base portion for supporting the vibrating piece,
An electronic device characterized in that a direction in which the side of the base portion extends and a direction in which the vibrating arm extends intersect in a plan view.   The electronic device according to claim 1, wherein the vibrating arm is supported by the base portion at one end thereof.   The electronic device according to claim 1, wherein the vibrating arm bends and vibrates in a thickness direction thereof.   The electronic device according to claim 1, wherein the vibrating piece includes three vibrating arms.   The electronic device according to claim 1, wherein the constituent material of the vibrating arm includes silicon.   The electronic device according to claim 1, wherein the constituent material of the base portion includes silicon. The constituent material of the base portion includes single crystal silicon,
The base portion has a side extending along the crystal orientation <110> of the single crystal silicon, and a direction in which the vibrating arm extends is along the crystal orientation <100> of the single crystal silicon. The electronic device according to claim 6.   The electronic device according to claim 1, further comprising a terminal portion that is aligned with the vibrating piece in a plan view.   The electronic device according to claim 1, further comprising a lid portion that covers the vibrating piece and is connected to the base portion.   An electronic apparatus comprising the electronic device according to claim 1.   A moving body comprising the electronic device according to claim 1.

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