JP2011234072A - Piezoelectric vibration piece and piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibration piece having a configuration that suppresses vibration leakage.SOLUTION: A crystal vibration piece 1 as a piezoelectric vibration piece includes: a base 2 having a width in an x-axis direction and a thickness in a z'-axis direction; arms 3 extending from the base 2 in a y'-axis direction; and a support 4 extending from the base 2 in a direction opposite to the arms 3. The base 2 is provided with a protrusion 5 protruding therefrom in the z'-axis direction.

Description

  The present invention relates to a piezoelectric vibrating piece having a vibrating arm and a piezoelectric device including the piezoelectric vibrating piece.

  Conventionally, a configuration for suppressing so-called vibration leakage in a piezoelectric vibrating piece is disclosed in Patent Document 1. According to this, the piezoelectric vibrating piece has a base (the bottom in Patent Document 1), an arm (arm) extending from the base, and a support (support substrate) for supporting the base, The support portion is provided with constricted portions and wide portions alternately. Since the piezoelectric vibrating piece has the constricted portion, the vibration from the base portion is attenuated by the constricted portion, and is difficult to be transmitted to the wide portion for supporting the piezoelectric vibrating piece. That is, it is possible to suppress vibration leakage to the support portion. In this case, the base part, the arm part, and the support part have the same thickness.

  Further, in Patent Document 2, in addition to the constricted portion, the piezoelectric vibration having a configuration in which the thickness of the support portion (fixed portion in Patent Document 2) is set to be thicker than the thickness of the arm portion (arm portion) other than the support portion. A piece is disclosed. According to this, since the piezoelectric vibrating piece has a support part thicker than the other part, it is difficult for vibration from the base part to be transmitted to the support part. It is possible to suppress leakage.

JP-A-8-128830 JP 2008-224628 A

  However, there are cases where it is difficult to reliably suppress vibration leakage in the piezoelectric vibrating piece simply by providing a constricted portion as in the prior art, and in particular, as the piezoelectric vibrating piece is downsized, It has been found that unless the setting of the shape and arrangement of the constricted portion is appropriately optimized, it will not lead to the effect of reliably suppressing vibration leakage. In addition, when suppressing the vibration leakage by setting the support part thicker than the arm part etc., if the thickness of the support part is reduced, in order to obtain the same suppression effect, the arm part from the base to the support part Due to the relationship that the length, that is, the length of the base portion must be increased, there is a problem that it is difficult to reduce the size including both the thickness and length of the piezoelectric vibrating piece.

  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 or forms.

  Application Example 1 A piezoelectric vibrating piece according to this application example includes a base portion whose width direction is the X-axis direction and a thickness direction that is the Z-axis direction, an arm portion extending from the base portion in the Y-axis direction, A support portion extending in a direction opposite to the arm portion from the base portion, and a protrusion portion protruding in the Z-axis direction is provided on the base portion.

  According to this piezoelectric vibrating piece, the X-axis, Y-axis, and Z-axis that are orthogonal to each other are the width direction, the extending direction, and the thickness direction, respectively, and the arm portion, the base portion, and the support portion are along the extending direction. Are arranged in order. In addition, the piezoelectric vibrating piece has a protrusion provided at the base so as to form a protrusion, and this protrusion resonates with vibration transmitted from the arm due to a mass change in the protrusion. It has become difficult. In other words, the protruding portion plays a role of suppressing vibration leakage, which substantially blocks transmission of vibration from the arm portion and makes it difficult for vibration to be transmitted to the support portion. Compared with the conventional configuration that suppresses vibration leakage to the support portion by increasing the thickness of the support portion, the piezoelectric vibration piece having such a configuration transmits vibrations at the base position close to the arm portion. Since it is almost cut off, it is possible to maintain the effect of suppressing vibration leakage even if the thickness of the support portion is made thinner than before. In other words, the piezoelectric vibrating piece has been conventionally required to increase the length from the base of the arm portion to the support portion, that is, the length of the base portion, even if the thickness of the support portion is smaller than the conventional thickness. Is unnecessary. From these facts, the piezoelectric vibrating piece having the protrusion at the base can effectively suppress vibration leakage at a position closer to the arm part with respect to the support part, and is small in size, including both the thickness and length of the piezoelectric vibrating piece. It is possible to respond flexibly to the conversion.

  Application Example 2 In the piezoelectric vibrating piece according to the application example described above, a plurality of the arm portions extend along the width direction of the base portion, and the protrusions extend along the width direction of the base portion. It is preferable.

  According to this configuration, the piezoelectric vibrating piece has a plurality of arm portions, and in this case, the protrusions are provided along the same width direction with respect to the arm portions arranged along the width direction of the base portion. It has been. That is, the protrusion and the arm are substantially parallel and are arranged so as to extend facing each other. Thereby, since the vibration transmitted from each arm part to the support part is almost interrupted by the protrusions existing between the arm part and the support part, it is suppressed from being transmitted to the support part as vibration leakage. Therefore, the configuration in which vibration leakage is suppressed by the protrusions can be easily and effectively applied to various piezoelectric vibrating reeds having a plurality of arm portions.

  Application Example 3 In the piezoelectric vibrating piece according to the application example, the base portion on which the protrusion is provided has a thickness on a side of the support portion with respect to the protrusion, on a side of the arm portion with respect to the protrusion. It is preferable that the thickness is set larger than the thickness.

  According to this configuration, in the base portion where the protrusion is provided, the thickness of the base located closer to the support portion than the protrusion, that is, the thickness of the support portion with respect to the protrusion is higher than the protrusion. Compared with the thickness of the base part located on the side of the part, the setting is thick and the rigidity is high. This piezoelectric vibrating piece is configured to vibrate with the support portion supported, and when the arm portion vibrates, the base portion having high rigidity on the support portion side supports the arm portion and the projection portion, so that more reliable support is provided. Is possible. In addition, for example, when the protrusion is formed by etching, the gap between the protrusion and the support is a narrow groove compared to the arm portion side of the protrusion, and thus the etching progress in the thickness direction is slow. As a result, even with the same etching time, the thickness of the base between the protrusion and the support is greater than the thickness of the base on the arm side of the protrusion. If etching is used in this manner, there is an advantage that processing for setting the base portion thickness on the support portion side can be easily performed.

  Application Example 4 A piezoelectric device according to this application example includes a base portion in which the X-axis direction is a width direction and a Z-axis direction is a thickness direction, an arm portion extending from the base portion in the Y-axis direction, It comprises at least a piezoelectric vibrating piece having a support portion extending from the base portion in a direction opposite to the arm portion and a protrusion portion provided on the base portion and protruding in the Z-axis direction.

  According to this piezoelectric device, the piezoelectric vibrating piece is provided, and the protruding portion of the piezoelectric vibrating piece is less likely to resonate with vibration transmitted from the arm portion due to a mass change in the protruding portion. In order to substantially block the transmission of vibration, it is difficult to transmit the vibration to the support portion. That is, the protrusion plays a role of suppressing vibration leakage. Compared with the conventional configuration that suppresses vibration leakage to the support portion by increasing the thickness of the support portion, the piezoelectric vibration piece having such a configuration transmits vibration at the base portion closer to the arm portion. Even if the thickness of the support part is made thinner than before, the effect of suppressing vibration leakage can be maintained, and it is possible to flexibly cope with downsizing. A piezoelectric device in which the piezoelectric vibrating piece is packaged can be reduced in size while suppressing vibration leakage. In addition to the piezoelectric vibrating piece, the piezoelectric device may further include an oscillation circuit for causing the piezoelectric vibrating piece to oscillate.

The perspective view which shows the external appearance seen from the surface side of the crystal vibrating piece which concerns on this embodiment. (A) Sectional drawing which shows the structure of a quartz crystal vibrating piece, (b) The schematic diagram which shows the bending principle of a quartz crystal vibrating piece. (A) The top view which shows the state which opened the cover body of the piezoelectric device, (b) Sectional drawing which shows a piezoelectric device. The flowchart which shows the manufacturing process of a piezoelectric device. (A) And (b) The perspective view which shows the modification of a crystal vibrating piece. (C) And (d) The perspective view which shows the modification of a crystal vibrating piece.

Hereinafter, specific embodiments of the piezoelectric vibrating piece and the piezoelectric device will be described with reference to the drawings. In the present embodiment, as a specific example of the piezoelectric vibrating piece, a crystal vibrating piece in which three arm portions perform so-called out-of-plane vibration will be described. Note that, in the drawings, each part of the drawn quartz crystal vibrating piece is partially emphasized for easy understanding, and is partially reduced in scale.
(Embodiment)

  FIG. 1 is a perspective view showing an external appearance of the quartz crystal resonator element according to the present embodiment as viewed from the surface side. In this crystal vibrating piece (piezoelectric vibrating piece) 1, as shown in FIG. 1, the side that is the same plane is the front side, and the side that is stepped is the back side. 2A is a cross-sectional view showing the configuration of the quartz crystal vibrating piece, and FIG. 2B is a schematic diagram showing the bending principle of the quartz crystal vibrating piece.

  First, the crystal forming the crystal vibrating piece 1 will be briefly described. The quartz crystal resonator element 1 is cut out from a hexagonal quartz crystal column, and the quartz crystal column is a hexagonal side in the xy plane of the z axis which is the optical axis in the longitudinal direction of the column and the hexagonal surface perpendicular to the z axis. X axis which is an electric axis parallel to the x axis and y axis which is a mechanical axis perpendicular to the x axis. In addition, there are three x-axes parallel to the hexagonal sides at an equal angle of 120 degrees, and the three surfaces formed in the xy plane by these x-axes have an etching progress rate depending on the etching direction. It has the trigonal nature that the differences are the same on each side. In such a quartz crystal column, the quartz crystal vibrating piece 1 is cut out from a quartz crystal z plate along a plane inclined at an angle of 5 degrees around the x axis when viewed from the intersection (coordinate origin) of the x axis and the y axis. It has been.

  As shown in FIG. 1, the quartz crystal resonator element 1 has a base portion 2 whose width direction is the x-axis (X-axis direction in the claims) and extends from the base portion 2 in the y′-axis (Y-axis direction in the claims) direction. Three arm portions 3 (3a, 3b, 3c) and a support portion 4 that extends from the base portion 2 in the direction opposite to the arm portion 3 and supports the crystal vibrating piece 1. Three arm portions 3 are arranged in order along the x axis with the arm portion 3b at the center. Further, as can be seen with reference to FIG. 2A, the crystal vibrating piece 1 has a predetermined thickness in the z′-axis (Z-axis in the claims) direction, and the thickness of the support portion 4. The thickness is set to be thicker than the base 2 and the arm 3.

  Further, on the back surface side of the base portion 2, a protruding portion 5 extending in a protruding shape along the x-axis direction is provided at a substantially central position in the y′-axis direction of the base portion 2. The protrusion 5 has the same length in the x-axis direction as the length in the x-axis direction of the base 2, and the shape in plan view is a rectangle whose longitudinal direction is the x-axis direction, and is along the y′-axis. The cross-sectional shape is rectangular. Further, the combined thickness of the base portion 2 provided with the protruding portion 5 and the protruding portion 5 is substantially the same as the thickness of the support portion 4. The base 2 on which the protrusion 5 is provided has a thickness of a portion located between the protrusion 5 and the support 4, that is, a thickness on the side of the support 4 with respect to the protrusion 5. It is thicker than the thickness on the arm 3 side. As a result, the base 2 has a rigid portion connected to the support 4, and can reliably support the arm 3 and the protrusion 5.

  Next, a metal film for applying a driving current to bend the arm portion 3 will be described with reference to FIG. These metal films are electrodes composed of two layers of a Cr film and an Au film, and are electrically connected to the two electrode terminals 10 and 20 provided on the support portion 4 and the electrode terminal 10 to the arm portion 3a. An excitation electrode 12a provided on the arm portion 3c, an excitation electrode 12c provided on the arm portion 3c, and an excitation electrode 22b provided independently on the arm portion 3b and not electrically connected to the electrode terminal 10 are provided on the surface side of the crystal vibrating piece 1. It has been. The excitation electrodes 12 a, 22 b and 12 c provided on the arm 3 are not formed at the tip of the arm 3.

  A piezoelectric film 9 is formed on the surface side of the quartz crystal vibrating piece 1 excluding the tips of the support portion 4 and the arm portion 3 so as to cover the excitation electrode 12a, the excitation electrode 22b, and the excitation electrode 12c. In this case, the piezoelectric film 9 is made of piezoelectric zinc oxide (ZnO) and has two through holes 7 and 8. The through hole 7 is provided so as to face the electrode terminal 10, the excitation electrode 12a of the arm portion 3a, and the portion of the metal film that is electrically connected to the excitation electrode 12c of the arm portion 3c, and the through hole 8 excites the arm portion 3b. It is provided to face the portion of the metal film that is electrically connected to the electrode 22b.

  Further, the piezoelectric film 9 is electrically connected to the electrode terminal 20, and the excitation electrode 22 a positioned opposite to the excitation electrode 12 a provided on the arm portion 3 a with the piezoelectric film 9 interposed therebetween, and the electrode terminal 20. Is electrically connected to the excitation electrode 12c provided on the arm portion 3c, and is opposed to the excitation electrode 22c provided on the arm portion 3b. Excitation electrodes 12b that are opposed to each other with the film 9 interposed therebetween and are not electrically connected to the electrode terminal 20 are provided. Here, the metal film that is electrically connected to the electrode terminal 20, the excitation electrode 22 a of the arm portion 3 a, and the excitation electrode 22 c of the arm portion 3 c is formed up to the hole wall of the through hole 8, via the through hole 8. It is electrically connected to the excitation electrode 22b of the arm 3b. Similarly, the metal film electrically connected to the excitation electrode 12b is formed up to the hole wall of the through-hole 7, and the excitation electrode 12a of the arm portion 3a, the excitation electrode 12c of the arm portion 3c, and It is electrically connected to the electrode terminal 10.

  The principle that the quartz crystal vibrating piece 1 having the configuration described above bends and vibrates will be described with reference to FIG. A driving current is applied to the crystal vibrating piece 1 from the electrode terminal 10 or the electrode terminal 20. For example, when a drive current is applied from the electrode terminal 10 to the electrode terminal 20, the drive current in the arm portion 3a is in a direction from the excitation electrode 12a to the electrode terminal 20 via the excitation electrode 22a. Similarly, the drive current in the arm 3c is in the direction from the excitation electrode 12c to the electrode terminal 20 via the excitation electrode 22c. That is, in the arm part 3a and the arm part 3c, since the drive current is applied from the back surface side to the front surface side, an electric field is generated in the direction from the back surface side to the front surface side. On the other hand, the drive current in the arm portion 3b is in the direction from the excitation electrode 12b to the electrode terminal 20 via the excitation electrode 22b. That is, in the arm portion 3b, a driving current is applied in the direction from the front surface side to the back surface side, so that an electric field directed from the front surface side to the back surface side is generated.

  Therefore, an electric field directed in the same direction is generated in the arm 3a and the arm 3c, and an electric field in a direction different from that of the arm 3a and the arm 3c is generated in the arm 3b. As a result, when the arm portion 3a and the arm portion 3c are bent in the front surface direction along the z 'axis, the arm portion 3b is bent in the back surface direction along the z' axis. When the direction of the drive current applied to the electrode terminal 10 and the electrode terminal 20 is changed, each arm 3 is bent in the opposite direction. That is, by alternately changing the direction of the drive current applied to the arm part 3, the arm part 3 vibrates repeatedly by bending. That is, the quartz crystal vibrating piece 1 causes so-called out-of-plane vibration by bending adjacent arm portions 3 with phases opposite to each other.

  In this case, the quartz crystal resonator element 1 has the protrusion 5 on the base 2, and the protrusion 5 is unlikely to resonate with vibration transmitted from the arm 3 due to a mass change in the protrusion 5. Yes. That is, the protrusion 5 plays a role of suppressing vibration leakage by substantially blocking the vibration transmitted from the arm portion 3 and making it difficult for the vibration to be transmitted to the support portion 4. Therefore, the quartz crystal resonator element 1 having the protrusion 5 on the base 2 has a thickness of the support 4 as compared with the conventional configuration in which the protrusion 5 is not provided and the support 4 is thicker than the base 2 to suppress vibration leakage. Can be made thinner. Further, the quartz crystal resonator element 1 has a longer length from the base of the arm 3 to the support 4, that is, the length of the base 2, which is conventionally required even if the thickness of the support 4 is reduced. Setting such as this is unnecessary, and it is possible to reduce both the thickness and the length of the quartz crystal vibrating piece 1 to reduce the size.

  Further, the crystal vibrating piece 1 is arranged such that the protrusion 5 is substantially parallel to the arrangement of the three arms 3 a, 3 b, 3 c and extends between the arm 3 and the support 4. . With this arrangement, vibrations transmitted from the arm portions 3 to the support portion 4 are almost blocked by the protrusions 5, and vibration leakage from the arm portions 3 to the support portion 4 can be suppressed. Thus, if the projection 5 is provided on the base 2 and extends along the arm 3, vibration leakage can be easily and effectively suppressed with respect to the plurality of arms 3. In addition, the protruding portion 5 also has an effect like a reinforcing bar that improves the rigidity of the base portion 2, and can suppress the arm portion 3 from being twisted and vibrated other than in the z′-axis direction.

  Next, a piezoelectric device including the quartz crystal resonator element 1 described above will be described. Fig.3 (a) is a top view which shows the state which opened the cover body of the piezoelectric device. FIG. 3B is a cross-sectional view showing the piezoelectric device, and is a cross section taken along T-T ′ in FIG. As shown in FIG. 3, the piezoelectric device 30 includes a crystal vibrating piece 1 and a package 40 that houses the crystal vibrating piece 1 in this case. The package 40 includes a package base 41 having a box shape and a sealing hole 46 at the bottom, a lid 43 for sealing the box-shaped interior of the package base 41, a seam ring 42, a sealing material 47, and the like. Has been.

  The package base 41 is formed in a box shape so as to accommodate the crystal vibrating piece 1, and a connection pad 48 for mounting and connecting the crystal vibrating piece 1 is provided in the box shape. The electrode pad 10 and the electrode terminal 20 of the crystal vibrating piece 1 are bonded and fixed to the connection pad 48 via a conductive adhesive 44. The connection pad 48 is connected to the wiring in the package base 41 and is configured to be electrically connected to the external connection terminal 45 provided on the outer periphery of the package base 41.

  In the package 40 containing the crystal resonator element 1, the opening of the box-shaped portion of the package base 41 and the lid 43 covering the opening are welded by the seam ring 42, and the package 40 is sealed in the sealing hole 46 of the package base 41. Is filled with a sealing material 47 made of a metal material or the like. The sealing material 47 is solidified after being melted in a reduced pressure atmosphere, and the sealing hole 46 is hermetically sealed so that the inside of the package base 41 can be kept in a reduced pressure state.

  In the piezoelectric device 30 having such a configuration, the quartz crystal vibrating reed 1 is excited by an external drive signal via the external connection terminal 45, and vibrates at a predetermined frequency to oscillate. As shown in FIG. 3A, the piezoelectric device 30 is formed by a rectangular columnar projection 5 provided on the back side of the base 2 of the crystal vibrating piece 1 and extending substantially parallel to the arrangement direction of the arms 3. Propagation of vibration leakage to the support portion 4 in the vibration piece 1 can be suppressed. Therefore, the piezoelectric device 30 includes the crystal vibrating piece 1 that can be downsized while maintaining the vibration characteristics, and can have stable vibration characteristics while being small.

  Next, the manufacturing process of the piezoelectric device 30 including the manufacturing process of the crystal vibrating piece 1 will be described. FIG. 4 is a flowchart showing the manufacturing process of the piezoelectric device. In this manufacturing process, since the crystal vibrating piece 1 is manufactured based on a wafer-like base material, a crystal wafer as a wafer-like base material is prepared. The quartz wafer is obtained by polishing the surface of the quartz z-plate described above into a flat plate shape.

  First, in step S1, etching is performed on the projection, base, and arm portions. In the quartz crystal resonator element 1, the back surface side to be the base portion 2 and the arm portion 3 is thinner than the support portion 4, and the protruding portion 5 is formed on the portion that becomes the back surface side of the base portion 2. Therefore, first, a resist film is applied to the back surface of the crystal wafer, and the resist film is patterned so that the back surfaces of the base portion 2 and the arm portion 3 can be removed by etching except for the portion to be the tip surface of the protrusion portion 5. I do. The exposed quartz surface corresponds to the back side of the arm portion 3 and the base portion 2 which are thinner than the support portion 4 and the projection portion 5, and the resist film remains on the other surface. In this state, the exposed portion of the quartz wafer is etched with hydrofluoric acid for a predetermined time, and the arm portion 3 and the base portion 2 are formed thin until a predetermined thickness is reached. At this time, a protrusion 5 is formed on the base 2. Then, the resist film is removed and the process proceeds to step S2.

  Here, when the protrusion 5 is formed on the back side of the base 2 by etching, the gap between the protrusion 5 and the support 4 is narrower than the arm 3 side of the protrusion 5. Etching progresses slowly in the thickness direction. Therefore, even if etching is performed for the same time, the thickness of the base portion 2 between the protrusion portion 5 and the support portion 4, that is, the thickness of the support portion 4 side with respect to the protrusion portion 5 is the arm portion 3 of the protrusion portion 5. There is a tendency to be thicker than the thickness of the base 2 on the side. Thereby, even if it is the setting by which the projection part 5 was provided in the base part 2, the base part 2 between the projection part 5 and the support part 4 can support the arm part 3 and the projection part 5 reliably. become.

  In step S2, outer shape etching including the arm portion 3 is performed. First, after applying a resist film on the surface of the quartz wafer, the resist film is formed into a connecting portion shape that connects the outer shape and the outer shape including the shape of the arm portion 3 of the crystal vibrating piece 1 by photolithography. Pattern. In this state, the exposed portion of the crystal wafer is etched with hydrofluoric acid to form the outer shape and the connecting portion of the crystal vibrating piece 1. As a result, a large number of externally finished products to be the quartz crystal resonator element 1 connected to the quartz wafer by the thin coupling portions are obtained. After the etching, the resist film is peeled off and the process proceeds to step S3.

  In step S3, electrodes are formed on the crystal surface. First, in this case, an electrode made of a metal film of a Cr film and an Au film is formed on the entire surface of the quartz wafer. Then, a resist film is formed on the electrode, and this resist film is patterned corresponding to the electrode terminal 10, the excitation electrodes 12a and 12c that are electrically connected to the electrode terminal 10, and the excitation electrode 22b. After the resist film is formed, the electrode portion without the resist film is etched to form the electrode terminal 10 and the excitation electrodes 12a, 12c, and 22b. In this case, an electrode is left as a weight metal film (not shown) at the tip of the arm 3. After forming the electrode, the resist film is peeled off and the process proceeds to step S4.

  In step S4, the piezoelectric film 9 is formed. The piezoelectric film 9 is formed by sputtering to cover the excitation electrodes 12a, 12c, and 22b of the arm 3 and to have a thickness of about 0.1 to 0.5 μm on the base 2 and the arm 3. In this case, the piezoelectric film 9 is piezoelectric zinc oxide (ZnO). After the formation of the piezoelectric film 9, the resist film is peeled off and the process proceeds to step S5.

  In step S5, an electrode is formed on the surface of the piezoelectric film 9 or the like. The electrodes formed here are an electrode terminal 20 provided on the crystal surface of the support portion 4, and an excitation electrode that is electrically connected to the electrode terminal 20 and is opposed to the excitation electrode 12 a of the arm portion 3 a with the piezoelectric film 9 interposed therebetween. 22a is electrically connected to the electrode terminal 20, and is opposed to the excitation electrode 12c of the arm portion 3c with the piezoelectric film 9 interposed therebetween, and opposed to the excitation electrode 22b of the arm portion 3b with the piezoelectric film 9 interposed therebetween. An excitation electrode 12b that is not electrically connected to the electrode terminal 20 and is provided alone. These electrodes are formed by the same method as the electrode formation in step S3. The electrode is also formed on the hole wall of the through-hole 7 and electrically connects the excitation electrode 12a and the excitation electrode 12c, which are electrically connected to the electrode terminal 10, and the excitation electrode 12b. The electrodes are also formed on the hole wall of the through-hole 8 and electrically connect the excitation electrode 22a and the excitation electrode 22c, which are electrically connected to the electrode terminal 20, and the excitation electrode 22b. After forming the electrodes on the piezoelectric film 9 and the like, the process proceeds to step S6.

  In step S6, the crystal vibrating piece is separated. That is, the thin connection part in the crystal wafer is broken, and the crystal resonator element 1 that has been connected is made into a single piece. This is the manufacturing process of the quartz crystal vibrating piece 1. After the separation, the process proceeds to step S7 in order to manufacture the piezoelectric device 30.

  In step S <b> 7, the crystal vibrating piece 1 is fixed by mounting on the package. That is, as shown in FIG. 3A, the crystal vibrating piece 1 is attached to the package base 41. After mounting the crystal vibrating piece 1, the process proceeds to step S8.

  In step S8, the frequency is adjusted. In this adjustment, a driving current is applied to the quartz crystal vibrating piece 1 and an ion beam, a laser beam, or the like is applied to the weight metal film at the tip of each arm 3 while observing the frequency, and the mass of the arm 3 is respectively determined. adjust. Thereby, the arm part 3 of the crystal vibrating piece 1 is adjusted to vibrate accurately at a predetermined frequency. After adjustment, the process proceeds to step S9.

  In step S9, the package is sealed. As shown in FIG. 3B, the lid 43 is welded to the package base 41, the sealing hole 46 is filled with the sealing material 47, and the crystal vibrating piece 1 is sealed in the package 40. Thus, the piezoelectric device 30 including the crystal vibrating piece 1 is completed. The piezoelectric device 30 includes the crystal vibrating piece 1 configured to suppress propagation of vibration leakage to the support portion 4 by providing the protrusion portion 5 on the base portion 2, and can maintain stable vibration. It is possible to improve the accuracy of mounted electronic devices and the like.

  In addition, the piezoelectric vibrating piece and the piezoelectric device are not limited to the above-described embodiment, and the same effects as those of the embodiment can be obtained even in the following modifications.

  (Modification 1) In the quartz crystal resonator element 1, the protrusion 5 is in the form of one rectangular column extending substantially parallel to the arrangement of the three arms 3a, 3b, 3c. For example, a form in which a plurality of protrusions extend substantially parallel to the arrangement of the arm portions 3 may be used. FIG. 5A is a perspective view showing a modification of the quartz crystal vibrating piece. In this case, the quartz crystal vibrating piece (piezoelectric vibrating piece) 100 has two protrusions 51 (51a and 51b). Except for the protrusion 51, the configuration is the same as that of the quartz crystal resonator element 1 of the embodiment. As shown in FIG. 5A, in the crystal vibrating piece 100, two projecting portions 51 a and 51 b are provided on the back surface side of the base portion 2 in place of the projecting portion 5 in the crystal vibrating piece 1. The protrusions 51 a and 51 b have the same length in the x-axis direction as the length in the x-axis direction of the base 2, and the cross-sectional shapes along the y′-axis are each rectangular and are combined with the provided base 2. The thickness is substantially the same as the thickness of the support portion 4. These protrusions 51a and 51b have a combined mass that is smaller than that of the protrusion 5 of the embodiment, but to suppress vibration leaking from the arm 3 to the support 4 in two steps with two protrusions, The vibration leakage suppressing effect substantially similar to that of the protruding portion 5 of the embodiment can be exhibited. In addition, since the crystal vibrating piece 100 has a smaller mass of the protrusion 51 than the protrusion 5 of the embodiment, the stress generated at the connecting portion between the base 2 and the support 4 is reduced compared to the case of the crystal vibrating piece 1. You can also

  (Modification 2) Further, the protrusion 5 of the quartz crystal vibrating piece 1 extends substantially parallel to the arrangement of the arm portions 3, and the shape in plan view is a substantially elliptical shape having the x-axis direction as the longitudinal direction. Also good. FIG. 5B is a perspective view showing a modification of the quartz crystal vibrating piece. In this case, the quartz crystal vibrating piece (piezoelectric vibrating piece) 200 has a protruding portion 52 that is substantially elliptical in plan view. The length in plan view along the y′-axis direction is the longest in the vicinity of the position of the arm portion 3b, and becomes shorter in the direction of the arm portion 3a or the arm portion 3c. If the protruding portion 52 has such an approximately elliptical shape, the maximum mass portion of the protruding portion 52 is located at the central portion in the x-axis direction of the base portion 2 where vibration leakage from the three arm portions 3 is concentrated. Thus, the crystal vibrating piece 200 can effectively suppress vibration leakage by balancing the mass of the protrusion 52 and vibration leakage.

  (Modification 3) The protrusion 5 of the crystal vibrating piece 1 may have a length in the x-axis direction shorter than a length of the base 2 in the x-axis direction. FIG. 6C is a perspective view showing a modified example of the crystal vibrating piece. In this case, the crystal vibrating piece (piezoelectric vibrating piece) 300 has a protrusion 53 that is different from the protrusion 5 of the embodiment in plan view. Although it is a similar rectangle, the length of the projection 53 in the x-axis direction is shorter than the length of the base 2 in the x-axis direction. That is, the protrusion 53 is not formed in the vicinity of the end portion in the width direction of the base 2 where vibration leakage hardly occurs. The quartz crystal vibrating piece 300 having the projection 53 having such a configuration can effectively suppress vibration leakage while suppressing the mass of the projection 53.

  (Modification 4) Further, the protrusions 5 of the quartz crystal vibrating piece 1 may be in the form of islands scattered substantially parallel to the arrangement of the arm portions 3. FIG. 6D is a perspective view showing a modification of the quartz crystal vibrating piece. In this case, the quartz crystal vibrating piece (piezoelectric vibrating piece) 400 has three island-shaped protrusions 54a, 54b, and 54c. The protrusions 54a, 54b, and 54c are configured such that the protrusion 53 shown in FIG. 6C is divided into three islands. By disposing the island-shaped protrusions 54 at positions where vibration leakage is likely to occur, the quartz crystal vibrating piece 400 can effectively suppress vibration leakage while further suppressing the mass of the protrusions 54.

  (Modification 5) Further, the protrusions 51, 52, 53, and 54 shown in the above-described modification may be combined with each other. For example, the protrusion shown in FIG. 51a and 51b may have a substantially elliptical shape in plan view like the protrusion 52 shown in FIG. The protrusions 51a and 51b and the protrusion 52 may be divided into a plurality of islands such as the protrusion 54 shown in FIG. 6D.

  (Modification 6) The crystal vibrating piece 1 is not limited to the protrusion 5 being provided only on the back surface side of the base 2, and is provided only on the front surface side of the base 2, or both the front and back surfaces of the base 2 The form etc. which were provided in may be sufficient. Further, the combined thickness of the protrusion 5 and the base 2 is not substantially the same as the thickness of the support 4, but may be set such that the thickness of the support 4 is thinner.

  (Modification 7) The quartz crystal resonator element 1 may have a configuration in which the protrusion 5 is not integrally formed with the base 2 but is attached to the base 2 as a separate body.

  (Modification 8) The crystal vibrating piece 1 has three arm portions 3 (3a, 3b, 3c), and the arm portion 3 is configured to vibrate out of plane, but has arm portions other than three. It may be a thing. Moreover, the structure which performs what is called in-plane vibration other than the arm part 3 bending and performing an out-of-plane vibration may be sufficient. Further, the quartz crystal vibrating piece 1 may be in a form of so-called thickness shear vibration in which the arm 3 is not bent and vibrates, but is not bent.

  (Modification 9) The crystal resonator element 1 may have a configuration in which a constriction is provided on the base 2 in addition to the protrusion 5. In the case of this configuration, the base 2 is elongated in the y′-axis direction.

  (Modification 10) In the base portion 2 of the crystal vibrating piece 1, the thickness of the support portion 4 side is thicker than that of the arm portion 3 side, and the base portion 2 is rigid so that the arm portion 3 and the protruding portion 5 are securely attached. However, as long as rigidity is ensured, the base 2 may have the same thickness on both sides.

(Modification 11) The electrode terminals 10 and 20, the piezoelectric film 9, and the excitation electrodes 12 and 22 of the crystal vibrating piece 1 show an example of an arrangement provided on the surface side of the base 2 and the arm 3. A configuration in which a piezoelectric film and an excitation electrode are also provided on the back surface side of the arm 3 may be employed. Further, an insulating film such as silicon oxide (SiO ₂ ) is provided between the excitation electrode 22 a and the piezoelectric film 9, between the excitation electrode 12 b and the piezoelectric film 9, and between the excitation electrode 22 c and the piezoelectric film 9. It may be.

  (Modification 12) The width, thickness, and extending direction of the piezoelectric vibrating reed described in the claims, and the x-axis that is the electric axis in the quartz, the y-axis that is the mechanical axis, and the z-axis that is the optical axis The X-axis, Y-axis, and Z-axis for clarity are taken as an example when the quartz crystal resonator element 1 is cut out from a crystal z-plate in which the x-axis and the X-axis coincide. However, the quartz crystal resonator element is not limited to this, and may have a form cut out from the quartz crystal column in various setting directions according to the application.

(Modification 13) The piezoelectric vibrating piece is not limited to the quartz vibrating piece 1 using quartz, but a piezoelectric body such as lithium niobate (LiNbO ₃ ) or lead zirconate titanate (PZT) other than quartz is used. It may be a thing. Furthermore, the piezoelectric vibrating piece having the piezoelectric film 9 is not limited to using a piezoelectric material such as quartz for the arm portion 3 or the like, and may be a non-piezoelectric material such as silicon or germanium.

  (Modification 14) The piezoelectric film 9 of the crystal vibrating piece 1 is zinc oxide (ZnO) formed by sputtering, but is not limited to this. For example, piezoelectric aluminum nitride (AlN), Zircon lead titanate (PZT) or the like may be used.

  (Modification 15) Although the inside of the package 40 of the piezoelectric device 30 is sealed in a reduced pressure state, an inert gas such as nitrogen, helium, or argon may be enclosed instead of the reduced pressure state.

  The quartz crystal resonator element 1 as a piezoelectric resonator element can maintain a stable vibration by suppressing the propagation of vibration leakage to the support section 4 by providing a protrusion 5 on the base 2 and can be downsized. It is. Therefore, the piezoelectric device 30 in which the crystal resonator element 1 is packaged is widely used as a timing device or the like in electronic devices such as digital mobile phones, personal computers, electronic watches, video recorders, and televisions, and the accuracy of these electronic devices is improved. This can contribute to downsizing and the like.

  DESCRIPTION OF SYMBOLS 1 ... Crystal vibrating piece as a piezoelectric vibrating piece, 2 ... Base part, 3 ... Arm part, 4 ... Support part, 5 ... Projection part, 7, 8 ... Through-hole, 9 ... Piezoelectric film, 10 ... Electrode terminal, 12 ... Excitation Electrode, 20 ... electrode terminal, 22 ... excitation electrode, 30 ... piezoelectric device, 51,52,53,54 ... projection, 100,200,300,400 ... crystal vibrating piece as piezoelectric vibrating piece.

Claims (4)

A base having the X-axis direction as the width direction and the Z-axis direction as the thickness direction;
An arm portion extending in the Y-axis direction from the base portion;
A support portion extending in a direction opposite to the arm portion from the base portion,
The base is provided with a protruding portion protruding in the Z-axis direction. The piezoelectric vibrating piece according to claim 1,
A plurality of arms extending along the width direction of the base,
The projecting portion extends along the width direction of the base portion. The piezoelectric vibrating piece according to claim 1 or 2,
Piezoelectric vibrations characterized in that the base portion on which the protrusions are provided is set such that the thickness of the support portion side with respect to the protrusion portions is thicker than the thickness of the arm portion side with respect to the protrusion portions. Piece. A base having the X-axis direction as the width direction and the Z-axis direction as the thickness direction;
An arm portion extending in the Y-axis direction from the base portion;
A support portion extending in a direction opposite to the arm portion from the base portion;
A piezoelectric device comprising at least a piezoelectric vibrating piece having a protrusion provided in the base and protruding in the Z-axis direction.

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