JP2014150422A - Tuning-fork type crystal vibrator and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a tuning-fork type crystal vibrator with a much better vibration characteristic.SOLUTION: The tuning-fork type crystal vibrator 1 comprises: a tuning-fork type piece 2 that is made of a crystal and in which first and second vibration arm parts 11, 12 are communicated with a base part 3; and excitation electrodes provided to the first and second vibration arm parts 11, 12. Plural through holes 13 are provided on the first and second vibration arm parts 11, 12. An opening of the through hole on a first principal plane 11a and an opening on a second principal plane 11b of the first and second vibration arm parts 11, 12 are displaced in a first direction that is a longitudinal direction of the first and second vibration arm parts 11, 12, so that an effective excitation electrode ratio on a cross section orthogonal to a second direction that is a width direction of the first and second vibration arm parts 11, 12=(a total area of the excitation electrodes)/(an area of regions in which the plural through holes are provided) is larger than that when the openings are not displaced from each other.

Description

  The present invention relates to a tuning fork crystal resonator having a plurality of vibration arm portions, and more particularly to a tuning fork crystal resonator having a plurality of through holes in the vibration arm portion and a method for manufacturing the same.

  Conventionally, a tuning fork type crystal resonator is used for an oscillator or the like. Patent Document 1 below discloses a tuning fork type crystal resonator 1001 shown in a plan view in FIG.

  The tuning fork type crystal resonator 1001 includes a base portion 1002 and vibration arm portions 1003 and 1004 whose first ends are connected to the base portion 1002. The base portion 1002 and the vibrating arm portions 1003 and 1004 are provided by processing a quartz substrate. The vibrating arm portion 1003 is provided with a plurality of through holes 1005 extending in the length direction.

  17 is a cross-sectional view taken along line BB in FIG. The direction of the electric field applied to the vibrating arm portions on both sides of the through-hole 1005 in the vibrating arm portion 1003 is the direction indicated by the arrow in the figure, and has a relationship as shown in FIG. 17 with the crystal axis of the quartz substrate. Further, in this vibration arm portion, the first vibration electrode 1006 is provided on the side surface facing the through hole 1005, and the second vibration electrode 1007 is provided on the outer side surface. By applying an alternating electric field from the first and second vibrating electrodes 1006 and 1007, the vibrating arm portions on both sides of the through hole 1005 in the vibrating arm portion 1003 expand and contract in opposite phases. Accordingly, the vibrating arm portion 1003 vibrates in the bending mode. The same applies to the vibrating arm 1004.

  In the tuning fork type crystal resonator 1001 described in Patent Document 1, a plurality of side bars 1008 are provided in the region where the through hole 1005 is provided.

Japanese Patent No. 3900513

  In the tuning fork type crystal resonator 1001, the vibration arm portions on both sides of the through hole 1005 in the vibration arm portions 1003 and 1004 expand and contract in opposite phases, and the vibration arm portions 1003 and 1004 vibrate in the bending mode. In the vibrating arm portions 1003 and 1004, the mechanical strength that has been lowered due to the provision of the through holes 1005 is reinforced by the provision of the side bars 1008.

  However, in the tuning fork type crystal resonator 1001 described in Patent Document 1, the vibration in the bending mode is broken, and it may not be possible to obtain good vibration characteristics.

  An object of the present invention is to provide a tuning fork type crystal resonator in which a plurality of through holes are provided in a vibration arm portion, and which can obtain even better vibration characteristics. .

  The tuning fork type crystal resonator according to the first to third aspects of the present application includes a tuning fork type resonator element made of crystal and an excitation electrode. The tuning fork type vibration piece has a base portion and a plurality of vibration arm portions. Each of the plurality of vibration arms has a first end, a second end opposite to the first end, and first and second main surfaces facing each other in the thickness direction. . The first end is connected to the base. The excitation electrode is provided in each of the plurality of vibration arms. The length direction connecting the first end and the second end of the vibration arm portion is the first direction, the width direction of the vibration arm portion orthogonal to the first direction is the second direction, and the first direction is the first direction. The thickness direction of the vibrating arm portion orthogonal to the second direction is defined as a third direction. The vibration arm portion is provided with a plurality of through holes arranged along the first direction. The plurality of through holes penetrate the vibration arm portion in the third direction. The excitation electrode is provided at least on the inner surfaces facing each other in the second direction of the plurality of through holes.

  In the tuning fork type crystal resonator according to the first and second inventions of the present application, the opening on the first main surface side and the opening on the second main surface side in the through hole are shifted in the first direction. Has been provided.

  In the tuning fork type crystal resonator according to the first invention of the present application, (total excitation electrode area in a cross section orthogonal to the second direction of the vibrating arm portion) / (plurality in a cross section orthogonal to the second direction of the vibrating arm portion) The opening on the first main surface side so that the effective excitation electrode ratio represented by the area of the region where the through-holes are provided is not shifted in the first direction. And the opening on the second main surface side are provided shifted in the first direction.

  In the tuning fork type crystal resonator according to the second invention of the present application, the opening on the first main surface side and the second main surface side in the through hole are set so that the effective excitation electrode ratio is 0.77 or more. The opening is provided so as to be shifted in the first direction.

  In the tuning fork type crystal resonator according to the third invention of the present application, the shape of the cross section perpendicular to the second direction of the through hole is a substantially parallelogram.

  In a specific aspect of the tuning fork type crystal resonator according to the first to third inventions of the present application, in the cross section orthogonal to the second direction of the through hole, the inner side surface facing in the first direction of the through hole is the vibrating arm. The angle formed by the first main surface and the second main surface of the part is an acute angle. In this case, the through hole can be easily formed by wet etching.

  In another specific aspect of the tuning fork type crystal resonator according to the first to third inventions of the present application, in the cross section orthogonal to the first direction of the through hole, the inner side surface facing in the second direction of the through hole vibrates. The angle formed between the first main surface and the second main surface of the arm portion is an acute angle. In this case, each through hole can be easily formed by wet etching.

  In still another specific aspect of the tuning fork type crystal resonator according to the first to third inventions of the present application, the plurality of through holes are provided close to the first end portion side of the vibrating arm portion.

  In still another specific aspect of the tuning-fork type crystal resonator according to the first to third inventions of the present application, of the plurality of through holes, an end portion on the base side of the through hole closest to the base portion is in the base portion. positioned.

  In still another specific aspect of the tuning fork type crystal resonator according to the first to third inventions of the present application, the vibration fork is connected to the second end of the vibrating arm, and the dimension along the second direction is the vibrating arm. It further has a weight portion larger than the dimension along the second direction of the portion. Preferably, the weight portion has a through hole or a recess.

  The manufacturing method of a tuning fork type crystal resonator according to the invention of the present application includes a base and a plurality of vibration arms, and the plurality of vibration arms are respectively a first end and a first end. A tuning-fork type resonator element made of quartz crystal having a second end portion on the opposite side and first and second main surfaces facing each other in the thickness direction, the first end portion being connected to the base portion; And a method for manufacturing a tuning-fork type crystal resonator including excitation electrodes respectively provided on a plurality of vibration arm portions. In the manufacturing method of the present invention, the length direction connecting the first end and the second end of the vibration arm is the first direction, and the width direction of the vibration arm is perpendicular to the first direction. And the thickness direction of the vibrating arm portion orthogonal to the first and second directions is the third direction. The manufacturing method according to the present invention includes the following steps.

  Forming a tuning fork-type vibrating piece having a base and a plurality of vibrating arms;

  Etching from the first main surface and the second main surface of the vibration arm portion after forming the tuning fork type vibrating piece or prior to forming the tuning fork type vibrating piece, and arranged along the first direction, Forming a plurality of through holes penetrating the vibrating arm portion in the direction of 3;

  Forming an excitation electrode on the vibrating arm;

  In the manufacturing method according to the invention of the present application, when forming the through hole by etching, the etching position on the first main surface side is set so that the effective excitation electrode ratio is larger than the case where the effective excitation electrode ratio is not shifted in the first direction. The etching position on the second main surface side is shifted in the first direction.

  In the manufacturing method according to the present invention, preferably, the etching position on the first main surface side and the etching position on the second main surface side are shifted so that the effective excitation electrode ratio is 0.77 or more. .

  In the tuning fork type crystal resonator according to the present invention, even better vibration characteristics can be obtained.

(A) is a schematic perspective view of the tuning fork type crystal resonator according to the first embodiment of the present invention, and (b) shows the tuning fork type crystal resonator according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a part of a cross section taken along line BB in FIG. 1A in the first vibrating arm section, and FIG. 3C is a tuning fork according to the first embodiment of the present invention. It is typical sectional drawing which shows the cross section orthogonal to the 1st direction of the part in which the through-hole in the 1st vibration arm part which comprises a type | mold crystal oscillator is provided, (d) is effective excitation electrode ratio. It is a typical sectional view for explaining. (A) is a model which shows the cross section orthogonal to the 1st direction of the part in which the through-hole is provided in the 1st vibration arm part which comprises the tuning fork type crystal resonator which concerns on the 1st Embodiment of this invention. FIG. 5B is a schematic cross-sectional view showing a cross section perpendicular to the first direction of a portion where the crosspiece is provided in the first vibrating arm portion. (A) And (b) is orthogonal to the 2nd direction of the part in which the through-hole is provided in the 1st vibration arm part which comprises the tuning fork type crystal resonator which concerns on the modification of 1st Embodiment. It is a typical sectional view showing a section, and a typical sectional view showing a section orthogonal to the 1st direction. (A) And (b) is a typical cross section which shows the cross section orthogonal to the 2nd direction of the part in which the through-hole is provided in the 1st vibration arm part which comprises the tuning fork type crystal resonator which concerns on a comparative example. It is a typical sectional view showing a section orthogonal to a figure and the 1st direction. The relationship between the amount of deviation between the opening on the first main surface side and the opening on the second main surface side of the through hole in the tuning fork type crystal resonator with different numbers of crosspieces and k ² Q indicating the vibration characteristics FIG. It is a figure which shows the relationship between the shift | offset | difference amount of the opening part by the side of the 1st main surface side of a through-hole, and the opening part by the side of a 2nd main surface, and resonance resistance CI in the tuning fork type | mold crystal vibrator in which the number of crosspieces differs. . FIG. 7 is a schematic diagram for explaining the amount of deviation shown in FIG. 5 and FIG. 6, and is a schematic cross-sectional view showing a cross section perpendicular to the second direction of a portion where a through hole is provided in the first vibration arm portion. It is. FIG. 7 is a schematic cross-sectional view showing a cross section orthogonal to a second direction of a portion where a through hole is provided in the first vibrating arm portion when the shift amount in FIGS. 5 and 6 is +0.02 mm. Is a diagram showing the relationship between k ^{2 Q} representing vibration characteristics and effective excitation electrode ratio. FIG. 5 is a schematic plan view of a tuning fork type crystal resonator according to a second embodiment of the present invention. In the tuning fork type crystal resonator according to the second embodiment of the present invention, k represents the distance D between the end portion on the base side of the through hole closest to the base portion and the end portion on the through hole side of the base portion and vibration characteristics. it is a diagram showing a relationship between ^{2 Q.} In the tuning fork type crystal resonator according to the second embodiment of the present invention, the distance D between the end on the base side of the through hole closest to the base and the end on the side of the through hole on the base and the resonance resistance CI It is a figure which shows a relationship. FIG. 6 is a schematic perspective view of a tuning fork type crystal resonator according to a third embodiment of the present invention. FIG. 6 is a schematic perspective view of a tuning fork type crystal resonator according to a fourth embodiment of the present invention. It is a figure which shows the relationship between the processing dimension shift | offset | difference by an etching, and the variation | change_quantity of a resonant frequency in embodiment which has a weight part provided with the through-hole, and the reference example which has a weight part without the through-hole. It is a top view of the conventional tuning fork type crystal resonator. It is sectional drawing in the BB line of FIG.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1A is a schematic perspective view showing a tuning fork type crystal resonator according to the first embodiment of the present invention. The tuning fork type crystal resonator 1 according to the first embodiment of the present invention includes a tuning fork type vibrating piece 2 made of crystal and excitation electrodes 5 and 6 to be described later with reference to FIGS. 2 (a) and 2 (b). Have. In FIG. 1A, the excitation electrodes 5 and 6 are not shown. That is, in FIG. 1A, the tuning fork type vibrating piece 2 of the tuning fork type crystal resonator 1 is shown in a perspective view.

  The tuning fork type vibrating piece 2 is made of a Z-cut crystal. In the present embodiment, the tuning fork type resonator element 2 includes a base 3, first and second vibrating arm portions 11 and 12, and first and second support arms 21 and 22. The base 3 is a part that connects the tuning fork type crystal resonator 1 to the outside. First and second vibrating arm portions 11 and 12 and first and second support arms 21 and 22 are connected to the base portion 3. The first and second vibrating arm portions 11 and 12 have a length direction and are arranged side by side at a distance. Each of the first and second vibrating arm portions 11 and 12 has a first end connected to the base 3 and a second end that is the opposite end and a free end. . A length direction connecting the first end and the second end of the first and second vibrating arm portions 11 and 12 is defined as a first direction. Moreover, let the width direction of the 1st, 2nd vibration arm parts 11 and 12 orthogonal to a 1st direction be a 2nd direction. Furthermore, the thickness direction of the first and second vibrating arm portions 11 and 12 orthogonal to the first and second directions is defined as a third direction. The first direction is the Y-axis direction of the crystal constituting the tuning fork type vibrating piece 2. The second direction is the X-axis direction of the crystal constituting the tuning fork type vibrating piece 2. The third direction is the Z-axis direction of the crystal constituting the tuning fork type vibrating piece 2.

  Since the first vibration arm unit 11 and the second vibration arm unit 12 are configured in the same manner, the first vibration arm unit 11 will be described below.

  FIG. 1B is a schematic cross-sectional view showing a section of the first vibrating arm portion 11 taken along line BB in FIG. 1A, that is, a part of a cross section orthogonal to the second direction. FIG. 1C is a schematic cross-sectional view showing a cross section orthogonal to the first direction of the portion where the through hole 13 is provided in the first vibrating arm portion 11. In FIG. 1C, the excitation electrodes 5 and 6 are not shown.

  As shown in FIGS. 1B and 1C, the first vibrating arm portion 11 has a first main surface 11a and a second main surface 11b that face each other in the third direction.

  The first vibrating arm portion 11 is provided with a plurality of through holes 13 along the first direction. The through hole 13 penetrates the first vibrating arm portion 11 in the third direction, that is, in the thickness direction. A space between adjacent through holes 13 is defined by a crosspiece 14 extending in the second direction.

  As shown in FIGS. 1B and 1C, the plurality of through-holes 13 are respectively in the first direction and the first and second inner side surfaces 13a and 13b facing each other in the second direction. And the third and fourth inner side surfaces 13c and 13d facing each other. In the present embodiment, the plurality of through holes 13 are provided close to the base 3 side in the first and second vibrating arm portions 11 and 12.

  In addition, among the plurality of through holes 13, the end of the through hole 13 closest to the base 3 coincides with the first and second vibrating arm portions 11 and 12 side ends of the base 3.

  FIG. 2A is a schematic cross-sectional view showing a cross section perpendicular to the first direction of the portion where the through hole 13 is provided in the first vibrating arm portion 11, as in FIG. 1C. . FIG. 2B is a schematic cross-sectional view showing a cross section orthogonal to the first direction of a portion where the crosspiece 14 is provided in the first vibrating arm portion 11. As shown in FIG. 2A, the first vibrating arm portion 11 has a first side surface 11c and a second side surface 11d that face each other in the second direction. Further, as shown in FIGS. 2A and 2B, the first vibrating arm portion 11 is provided with excitation electrodes 5 and 6 and a connection electrode 7.

  As shown in FIG. 2A, excitation electrodes 5 and 5 are provided on each of the first and second inner side surfaces 13a and 13b of the through hole 13 facing each other in the second direction. Further, as shown in FIGS. 2A and 2B, the excitation electrodes 6 and 6 are opposed to the first inner side surface 13a of the through hole 13 in the first side surface 11c in the second direction. And a portion facing the second inner side surface 13b of the through hole 13 in the second side surface 11d in the second direction. In the first direction, that is, the length direction of the first vibration arm portion 11, the excitation electrodes 6 and 6 reach the entire region where the plurality of through holes 13 of the first vibration arm portion 11 are provided. Provided on the first and second side faces 11c and 11d, respectively. The excitation electrodes 6 and 6 are opposed to the excitation electrodes 5 and 5 through a part of the first vibration arm portion 11.

  The excitation electrodes 5 and 5 and the excitation electrodes 6 and 6 are provided so as to reach the first and second main surfaces 11a and 11b, respectively.

  As shown in FIG. 2B, the connection electrode 7 is provided on the first and second main surfaces 11 a and 11 b in the portion where the crosspiece 14 is provided in the first vibrating arm portion 11. . The connection electrode 7 is connected to portions provided on the first and second main surfaces 11 a and 11 b of the excitation electrodes 5 and 5. That is, the connection electrode 7 is connected to the excitation electrode 5, and electrically connects adjacent excitation electrodes 5 in the first direction, that is, the length direction of the first vibration arm portion 11, and The excitation electrode 5 provided on the side surface 13a and the excitation electrode 5 provided on the second inner side surface 13b are electrically connected.

  In the first vibrating arm portion 11, an electric field is applied to the portions of the through holes 13 located on both sides in the second direction in the direction indicated by the arrow in FIG. Therefore, when an alternating voltage is applied between the excitation electrode 5 and the excitation electrode 6, the first vibrating arm unit 11 vibrates in the bending mode. The second vibrating arm unit 12 is provided with an excitation electrode and a connection electrode, similarly to the first vibrating arm unit 11.

  The excitation electrodes 5 and 6 can be formed of an appropriate metal or alloy such as Ag, Au, or Cu.

  As shown in FIG. 1A, the support arms 21 and 22 are provided outside the tuning direction fork type vibrating piece 2 in the second direction outside the portion where the first and second vibrating arm portions 11 and 12 are provided. It extends parallel to the first and second vibrating arm portions 11 and 12. In the present embodiment, by providing the support arms 21 and 22, the vibration energy of the first and second vibration arm portions 11 and 12 can be effectively confined. Thereby, loss due to the support structure can be reduced. Therefore, vibration characteristics can be further improved.

  The tuning fork type crystal resonator 1 of the present embodiment is characterized in that the opening on the first main surface 11a side and the opening on the second main surface 11b side are shifted in the first direction in the through hole 13. There is in being. In other words, in the through hole 13, the opening on the first main surface 11 a side and the opening on the second main surface 11 b side are at positions where the end portions on the first direction side are different, and the through hole 13 When viewed from the third direction, an end on the first direction side of the opening on the first main surface 11a side, and an end on the first direction side of the opening on the second main surface 11b side, Are provided so as not to overlap. More specifically, in the through hole 13, the opening on the first main surface 11 a side and the opening on the second main surface 11 b side are provided without being shifted in the first direction. The effective excitation electrode ratio in the cross section orthogonal to the second direction of the first and second vibrating arm portions 11 and 12 is shifted and provided. Here, the effective excitation electrode ratio is (total excitation electrode area in a cross section orthogonal to the second direction of the vibration arm portion) / (a plurality of through holes in a cross section orthogonal to the second direction of the vibration arm portion). The area of the area being expressed).

  The effective excitation electrode ratio will be specifically described with reference to FIG. FIG. 1D is a schematic cross-sectional view showing a part of a cross section orthogonal to the second direction of the portion where the through-hole 13 is provided in the first vibrating arm portion 11. Here, unlike FIG. 1A, the case where three through holes 13, 13, 13 are provided in the first direction and the number of crosspieces 14 is two will be described as an example. In this case, excitation electrodes 5, 5, 5 are provided on the first and second inner side surfaces 13 c, 13 d of the three through holes 13, 13, 13. In FIG. 1 (d), excitation electrodes 5, 5, and 5 provided on one inner surface are shown. The total area of the excitation electrodes 5, 5, 5 is the total area of the excitation electrodes in the cross section orthogonal to the second direction of the first vibration arm portion 11.

  On the other hand, the area of the region provided with the plurality of through holes in the cross section orthogonal to the second direction of the first vibrating arm portion 11 is the area of the region surrounded by the broken line M in FIG. is there. That is, it is an area where all the through holes 13, 13, 13 are provided, and is the total area of the crosspieces 14, 14 included in the area. In other words, in the region where the plurality of through-holes 13 are arranged along the first direction in the first vibrating arm portion 11, the first end in the first direction is connected to the other end. A plurality of through holes 13 are provided in a cross section in which the product of the line segment along the direction 1 and the dimension in the thickness direction of the first vibrating arm unit 11 is orthogonal to the second direction of the first vibrating arm unit 11. It is the area of the area that has been.

  In the present embodiment, the effective excitation is greater than in the case where the first main surface 11a side opening and the second main surface 11b side opening are provided without being shifted in the first direction in the through hole 13. It is shifted in the first direction so as to increase the electrode ratio. Preferably, the opening on the first main surface 11a side and the opening on the second main surface 11b side in the through hole 13 are the first so that the effective excitation electrode ratio becomes 0.8 or more as will be described later. Are shifted in the direction. Therefore, vibration characteristics can be improved with certainty. This will be described in detail below.

  As shown in FIG.1 (c), in the through-hole 13, the opening part by the side of the 1st main surface 11a and the opening part by the side of the 2nd main surface 11b are provided without shifting in the 2nd direction. Yes. In other words, in the through hole 13, the opening on the first main surface 11 a side and the opening on the second main surface 11 b side are in the same position at the end portions on the second direction side. When viewed from the third direction, an end on the first direction side of the opening on the first main surface 11a side, and an end on the second direction side of the opening on the second main surface 11b side, Are provided to overlap.

  The through hole 13 can be formed by etching the quartz substrate. This etching is performed simultaneously from the first main surface 11a side and the second main surface 11b side. In this case, the opening of the mask arranged on the first main surface 11a side and the opening of the mask arranged on the second main surface 11b side are shifted in the first direction. In this state, etching is performed from the first main surface 11a side and the second main surface 11b side.

  For example, when obtaining the through-hole 13 shown in FIG.1 (b), the opening part of the mask arrange | positioned at the 1st main surface 11a side is made rather than the opening part of the mask arrange | positioned at the 2nd main surface 11b side. What is necessary is just to shift to the 2nd edge part side of the 1st vibration arm part 11, ie, the 1st vibration arm part 11, on the drawing. By performing etching in this manner, the through hole 13 can be formed.

  In wet etching, etching proceeds from the opening. Therefore, in the wet etching, if etching is performed simultaneously from the first main surface 11a side and the second main surface 11b side as described above, the third and fourth inner side surfaces 13c facing each other in the first direction of the through hole 13 are formed. The angles θ1 and θ2 formed by 13d with the first main surface 11a or the second main surface 11b are acute angles. Therefore, such an opening can be easily formed by the wet etching.

  Therefore, in the tuning fork type crystal resonator 1 of the present embodiment, the through hole 13 can be easily formed.

  When the wet etching is performed, as shown in FIG. 1B, the third inner side surface 13c of the through hole 13 has an inner side surface portion 13c1 that forms an angle θ1 with the first main surface 11a. It has an inner side surface portion 13c2 that is located on the second main surface 11b side and forms an angle of θ2 with the second main surface 11b. On the other hand, the fourth inner side surface 13d is located on the inner side surface portion 13d1 that forms θ2 with the first main surface 11a and the second main surface 11b side, and the angle between the second main surface 11b and θ1 is set. And an inner side surface portion 13d2. As apparent from FIG. 1B, the inner side surface portion 13c2 occupies most of the third inner side surface 13c, and the inner side surface portion 13d1 occupies most of the fourth inner side surface 13d. In the cross section shown in FIG. 1B, the inner side surface portion 13c2 and the inner side surface portion 13d1 are substantially parallel. Therefore, the cross section orthogonal to the second direction of the through-hole 13 is a substantially parallelogram. This is because the opening on the first main surface 11a side and the opening on the second main surface 11b side of the through-hole 13 are shifted in the first direction as described above.

  On the other hand, as shown in FIG.1 (c), in the cross section orthogonal to the 1st direction of the through-hole 13, the angle which the 1st inner surface 13a makes with the 1st main surface 11a and the 2nd main surface 11b θ3 is 90 °. The angle formed by the second inner surface 13b with the first main surface 11a and the second main surface 11b is θ4. This angle θ4 is an acute angle.

  However, the through hole 13 may be formed so that the angle θ3 is also an acute angle. That is, if at least one of the first and second inner side surfaces 13a and 13b is formed with the first main surface 11a and the second main surface 11b has an acute angle, the through-hole 13 can be easily formed by the wet etching. Can be formed. Therefore, productivity can be improved.

  In the present embodiment, as shown in FIG. 1B, the inner side surface portion 13c2 and the inner side surface portion 13d1 occupy most of the third and fourth inner side surfaces 13c, 13d. On the other hand, as in the modification shown in FIGS. 3A and 3B, the inner side surface portion 13c1 and the inner side surface portion 13d2 occupy most of the third and fourth inner side surfaces 13c and 13d. The through hole 13 may be formed. In order to form the through-hole 13 shown in FIGS. 3A and 3B, the mask opening disposed on the first main surface 11a side is formed on the second main surface 11b side, contrary to the above. What is necessary is just to shift | deviate to the left side on the drawing rather than the opening part of the mask arrange | positioned in (1), ie, the base 3 side.

  Here, only the point that the opening on the first main surface 11a side and the opening on the second main surface 11b side are provided without being shifted in the first direction in the through-hole 13 of the present embodiment. A tuning fork crystal resonator according to a comparative example different from the tuning fork crystal resonator 1 is prepared. 4A and 4B are cross-sectional views orthogonal to the second direction of the portion where the through hole 13 is provided in the first vibrating arm portion 11 constituting the tuning fork type crystal resonator according to the comparative example. It is a typical sectional view showing, and a typical sectional view showing a section orthogonal to the 1st direction. However, in the tuning fork type crystal resonator according to the comparative example, the through hole 13 is formed by performing wet etching from the first main surface 11a side and the second main surface 11b side. The angle formed by the third and fourth inner side surfaces 13c and 13d and the first and second main surfaces 11a and 11b is θ1 or θ2 shown in FIG.

FIG. 5 is a diagram showing the relationship between the amount of deviation between the opening on the first main surface 11a side and the opening on the second main surface 11b side, and k ² Q representing the vibration characteristics. FIG. 6 is a diagram showing the relationship between the shift amount and the resonance resistance CI. 5 and 6 show results when the number of the crosspieces 14 is four, five, or six. That is, the results of the tuning fork type crystal resonator 1 when the number of the through holes 13 is 5, 6, or 7 are shown.

  FIG. 7 is a through hole in the first vibrating arm portion 11 for explaining the amount of deviation between the opening portion on the first main surface 11a side and the opening portion on the second main surface 11b side of the through hole 13. It is typical sectional drawing which shows the cross section orthogonal to the 2nd direction of the part in which 13 is provided. As shown in FIG. 7, the distance in the first direction between the opening on the first main surface 11 a side and the opening on the second main surface 11 b side of the through hole 13, that is, the first of the through hole 13. The distance between the base side end of the opening on the main surface 11a side and the base side end on the second main surface 11b side is defined as the shift amount x.

5 and 6, when the deviation amount is 0.00 mm, k ² Q or CI of the tuning fork type crystal resonator according to the comparative example is shown. The case where the amount of deviation is a positive value means that, as shown in FIG. 1B, the opening on the first main surface 11a side of the through-hole 13 is larger than the opening on the second main surface 11b side. The case where it is located in the 2nd edge part side of the 1 vibration arm part 11 is shown. Moreover, when the deviation | shift amount is a negative value, as shown to Fig.3 (a), the opening part by the side of the 1st main surface 11a of the through-hole 13 is more than the opening part by the side of the 2nd main surface 11b. 1 also shows a case where the first vibration arm portion 11 is located on the first end portion, that is, the base portion 3 side.

  As is apparent from FIGS. 5 and 6, the opening on the first main surface 11a side and the second main surface of the through-hole 13 in any case where the number of crosspieces is four, five, or six. It can be seen that the vibration characteristics and the resonance resistance are changed by providing the opening portion shifted from the opening portion on the 11b side.

As can be seen from FIG. 5, when the deviation amount is +0.05 mm or more or a negative value, k ² Q is higher than when the deviation amount is 0.00 mm. Further, as apparent from FIG. 6, when the deviation amount is a negative value, the CI becomes lower than that when the deviation amount is 0.00 mm, and it can be seen that the size can be reduced.

FIG. 8 is a schematic cross-sectional view showing a cross section perpendicular to the second direction of the portion where the through hole 13 is provided in the first vibrating arm portion 11 when the shift amount is +0.02 mm. . As apparent from FIGS. 5 and 6, when the deviation amount is +0.02 mm, k ² Q is lower and CI is higher than when the deviation amount is 0.00 mm.

  As apparent from FIGS. 5 and 6, the opening on the first main surface 11 a side and the opening on the second main surface 11 b side are provided in the through hole 13 so as to be shifted in the first direction. Thus, it can be seen that the vibration characteristics can be improved and the resonance resistance can be lowered.

FIG. 9 is a diagram showing the relationship between the effective excitation electrode ratio and the vibration characteristic k ² Q described above. As is clear from FIG. 9, when the effective excitation electrode ratio is 0.4 to 0.97, k ² Q representing the vibration characteristics increases as the effective excitation electrode ratio increases, and the effective excitation electrode ratio decreases. It can be seen that if it exceeds 0.97, k ² Q indicating the vibration characteristics decreases rapidly. Therefore, it can be seen that it is desirable to increase the effective excitation electrode ratio within a range of 0.97 or less in order to improve the vibration characteristics.

  Therefore, in the tuning fork crystal resonator 1 of the above embodiment, the opening on the first main surface 11a side and the opening on the second main surface 11b side in the through hole 13 are not shifted in the first direction. It can be seen that the effective excitation electrode ratio may be shifted so as to be larger than the case where the effective excitation electrode ratio is provided. It can be seen that the vibration characteristics can be reliably improved.

  More preferably, it can be seen that if the effective excitation electrode ratio is 0.77 or more and 0.97 or less, vibration characteristics can be effectively improved. Therefore, the opening on the first main surface 11a side and the opening on the second main surface 11b side in the through hole 13 are shifted in the first direction so that the effective excitation electrode ratio is 0.77 or more. It is desirable to provide the effective excitation electrode ratio shifted in the first direction so as to increase the effective excitation electrode ratio. In such a case, when the through hole 13 is formed by the above-described wet etching, as shown in FIGS. 1B and 3A, the cross section perpendicular to the second direction of the through hole 13 is substantially parallel. It has a quadrilateral shape. Therefore, if the through hole 13 is formed so that the cross section perpendicular to the second direction of the through hole 13 has a substantially parallelogram shape, the vibration characteristics can be effectively improved as described above.

  As described above, in the tuning fork type crystal resonator 1 of the present embodiment, the opening on the first main surface 11a side and the opening on the second main surface 11b side in the through hole 13 are shifted in the first direction. The cross-sectional shape orthogonal to the second direction of the through hole 13 is a substantially parallelogram. As a result, the vibration characteristics can be reliably improved. In addition, in the tuning fork type crystal resonator 1 provided with the through hole 13, the resonance frequency can be lowered and the size can be reduced as in the conventional tuning fork type crystal resonator having the through hole. In particular, in the above-described embodiment, by forming the through hole 13 as described above, the resonance resistance CI can be lowered and the size can be further reduced.

  When manufacturing the tuning fork type crystal resonator 1 of the present embodiment, the tuning fork type vibrating piece 2 having the base 3 and the first and second vibrating arm portions 11 and 12 is formed. After the tuning fork-type vibrating piece 2 is formed, the first and second vibrating arm portions 11 and 12 are etched to form the plurality of through holes 13. This etching may be performed at the stage of the quartz substrate prior to the formation of the tuning fork type vibrating piece 2.

  In the etching, as described above, the through hole 13 is formed by shifting the etching position on the first main surface 11a, 12a side and the etching position on the second main surface 11b, 12b side in the first direction. In the first and second vibrating arms, the opening on the first main surface 11a side and the opening on the second main surface 11b side are provided without being shifted in the first direction. The portions 11 and 12 are provided so as to be shifted so that the effective excitation electrode ratio in the cross section orthogonal to the second direction is increased. That is, by shifting the position of the opening of the mask when forming the through hole 13 as described above, the etching position on the first main surfaces 11a and 12a side and the etching on the second main surfaces 11b and 12b side are performed. The position can be shifted in the first direction.

  Thereafter, excitation electrodes are formed on the first and second vibrating arm portions 11 and 12 by a thin film forming method or the like. In this way, the tuning fork type crystal resonator 1 of the present invention can be obtained.

  More preferably, the etching position on the first main surface side is shifted from the etching position on the second main surface side so that the effective excitation electrode ratio is 0.77 or more.

  FIG. 10 is a schematic plan view of a tuning fork type crystal resonator according to the second embodiment of the present invention. In the tuning fork type crystal resonator of the second embodiment, the base 3 side of the through hole 13 closest to the base 3 among the plurality of through holes 13 provided in the first and second vibrating arm portions 11 and 12. Is located at a distance D from the first and second vibrating arm portions 11 and 12 side end portions of the base portion 3. That is, a plurality of through holes 13 are provided in the first vibration arm portion 11, the end portion of the through hole 13 closest to the base portion 3 on the base portion 3 side, and the first and second vibration arm portions of the base portion 3. The distance D between the end portions on the 11 and 12 side, that is, the end portion on the through hole 13 side is set to be larger than zero. In the first embodiment, the distance D is 0.

FIG. 11 is a diagram showing the relationship between the distance D and k ² Q representing vibration characteristics in the tuning fork type crystal resonator according to the present embodiment. FIG. 12 is a diagram illustrating a relationship between the distance D and the resonance resistance CI in the tuning fork type crystal resonator according to the present embodiment. 11 and 12 show the results when the number of crosspieces 14 is 4, 5, or 6. That is, the results when the number of through holes 13 is 5, 6, or 7 are shown.

  When the distance D is a positive value, as shown in FIG. 10, the through hole closest to the base portion 3 among the plurality of through holes 13 provided in the first and second vibrating arm portions 11 and 12 is used. The case where the edge part by the side of the base 3 of the hole 13 exists in the position away from the 1st, 2nd vibration arm part 11 and 12 side edge part of the base 3 is shown. The case where the distance D is a negative value means that among the plurality of through holes 13 provided in the first and second vibrating arm portions 11 and 12, the through hole 13 closest to the base portion 3 is closer to the base 3 side. The case where an edge part is located in the base 3 is shown.

  As apparent from FIGS. 11 and 12, the base 3 side of the through hole 13 closest to the base portion 3 among the plurality of through holes 13 in any case where the number of crosspieces is four, five, or six. And the first and second vibrating arm portions 11 and 12 side end portions of the base portion 3 are in different positions in the first direction, that is, the distance D is other than 0, It can be seen that the vibration characteristics and resonance resistance change.

As can be seen from FIG. 11, when the distance D is a desired negative value, k ² Q increases. As apparent from FIG. 12, when the distance D is a negative value, the CI is lower than when the distance D is 0 or a positive value, and it can be seen that the size can be reduced. FIG. 13 is a schematic perspective view of a tuning-fork type crystal resonator according to the third embodiment of the present invention. The tuning fork type crystal resonator according to the present embodiment is that the tuning fork type quartz crystal according to the first embodiment is provided with the weight portions 31 and 32 and the point without the first and second support arms. Different from the vibrator 1. Specifically, in the present embodiment, in the tuning fork type vibrating piece 2, the weight portions 31 and 32 are connected to the tips of the first and second vibrating arm portions 11 and 12, that is, the second end portion side, respectively. .

  The width direction of the weight parts 31 and 32 is the same as the width direction of the first and second vibrating arm parts 11 and 12, and the width direction dimensions of the weight parts 31 and 32 are the first and second dimensions. It is made longer than the dimension of the vibration arm parts 11 and 12 in the width direction. The weight portions 31 and 32 are not particularly limited, but are preferably made of the above-described crystal and formed integrally with the first and second vibrating arm portions 11 and 12. By providing the weight portions 31 and 32, the resonance frequency can be lowered. As a result, the tuning fork crystal unit can be miniaturized.

  FIG. 14 is a schematic perspective view of a tuning fork type crystal resonator according to the fourth embodiment of the present invention. The tuning fork crystal resonator according to the present embodiment is provided with a plurality of through holes 31a and 32a in the weight portions 31 and 32, respectively, in addition to the configuration of the tuning fork crystal resonator according to the third embodiment. By providing the through holes 31a and 32a, it is possible to suppress fluctuations in the resonance frequency due to processing variations caused by etching.

  FIG. 15 shows the processing dimension deviation due to etching and the fluctuation amount of the resonance frequency in the present embodiment in which the through holes 31a and 32a are provided in the weight portions 31 and 32 and the reference example in which the through hole is not provided in the weight portion. It is a figure which shows the relationship. Here, the processing dimension deviation on the horizontal axis is a deviation amount from a target dimension. As shown in FIG. 15, in the case of the reference example in which the through hole is not provided in the weight portion, it can be seen that the resonance frequency greatly fluctuates with the processing dimension deviation due to etching.

  On the other hand, as shown in FIG. 15, even if the processing dimension deviation due to etching varies, according to the present embodiment, the variation of the resonance frequency can be suppressed. The reason for this is as follows. If the etching amount is too large, the width direction dimensions of the first and second vibrating arm portions 11 and 12 become small. For this reason, the resonance frequency is lowered. In this case, the dimensions of the through holes 31a and 32a provided in the weight portions 31 and 32 are increased, the mass addition effect by the weight portions 31 and 32 is reduced, and the resonance frequency is increased. Accordingly, fluctuations in the resonance frequency can be suppressed. Conversely, when the etching amount is small, the reverse phenomenon occurs, and even in this case, the fluctuation of the resonance frequency can be suppressed.

  That is, fluctuations in the resonance frequency due to increase / decrease in the machining amount can be suppressed by providing the through holes 31a and 32a. As described above, based on the variation direction of the resonance frequency based on the change in the dimension in the width direction of the first and second vibrating arm portions 11 and 12 due to the change in the etching amount, and on the weight portions 31 and 32 due to the change in the etching amount. The direction of resonance frequency changes due to the mass addition effect. Accordingly, it is possible to suppress fluctuations in the resonance frequency due to deviations in outer dimensions due to variations in etching amount, that is, variations in processing.

  In the present embodiment, the weight portions 31 and 32 are provided with the through holes 31a and 32a. However, in place of the through holes 31a and 32a, recesses may be provided on the upper surface and / or the lower surface of the weight portions 31 and 32.

DESCRIPTION OF SYMBOLS 1 ... Tuning fork type crystal resonator 2 ... Tuning fork type vibration piece 3 ... Base part 5, 6 ... 1st, 2nd excitation electrode 7 ... Connection electrode 11 ... 1st vibration arm part 12 ... 2nd vibration arm part 11a, 12a ... 1st main surface 11b, 12b ... 2nd main surface 11c, 11d ... 1st, 2nd side surface 13 ... Through-hole 13a-13d ... 1st-4th inner side surface 13c1, 13c2, 13d1, 13d2 ... Inner side surface part 14 ... Crosspieces 21, 22 ... Support arms 31, 32 ... Weight parts 31a, 32a ... Through holes

Claims (11)

A tuning fork type resonator element having a base and a plurality of vibrating arms and made of crystal;
An excitation electrode provided on each of the plurality of vibration arms,
The plurality of vibration arm portions respectively include a first end portion, a second end portion opposite to the first end portion, and first and second main surfaces facing each other in the thickness direction. And the first end is connected to the base,
A length direction connecting the first end portion and the second end portion of the vibration arm portion is defined as a first direction, and a width direction of the vibration arm portion orthogonal to the first direction is defined as a second direction. When the thickness direction of the vibration arm portion orthogonal to the first and second directions is a third direction, the vibration arm portion is disposed along the first direction. A plurality of through-holes penetrating the vibrating arm portion in the third direction are provided, and the excitation electrodes are formed on inner surfaces of the plurality of through-holes facing each other in the second direction. At least,
In the through hole, the opening on the first principal surface side and the opening on the second principal surface side are (excitation electrode total area in a cross section perpendicular to the second direction of the vibration arm portion) / An effective excitation electrode ratio represented by (area of a region where a plurality of through holes in a cross section perpendicular to the second direction of the vibration arm portion is provided) is provided without being shifted in the first direction. A tuning-fork type crystal resonator provided so as to be shifted in the first direction so as to be larger than the case. A tuning fork type resonator element having a base and a plurality of vibrating arms and made of crystal;
An excitation electrode provided on each of the plurality of vibration arms,
The plurality of vibration arm portions respectively include a first end portion, a second end portion opposite to the first end portion, and first and second main surfaces facing each other in the thickness direction. And the first end is connected to the base,
A length direction connecting the first end portion and the second end portion of the vibration arm portion is defined as a first direction, and a width direction of the vibration arm portion orthogonal to the first direction is defined as a second direction. When the thickness direction of the vibration arm portion orthogonal to the first and second directions is a third direction, the vibration arm portion is disposed along the first direction. A plurality of through-holes penetrating the vibrating arm portion in the third direction are provided, and the excitation electrodes are formed on inner surfaces of the plurality of through-holes facing each other in the second direction. At least,
(Excitation electrode total area in a cross section orthogonal to the second direction of the vibration arm portion) / (Area of a region where a plurality of through holes are provided in a cross section orthogonal to the second direction of the vibration arm portion) In the through hole, the opening on the first main surface side and the opening on the second main surface side in the through hole are such that the effective excitation electrode ratio represented by) is 0.77 or more. A tuning-fork type quartz crystal unit that is shifted in the direction. A tuning fork type resonator element having a base and a plurality of vibrating arms and made of crystal;
An excitation electrode provided on each of the plurality of vibration arms,
The plurality of vibration arm portions respectively include a first end portion, a second end portion opposite to the first end portion, and first and second main surfaces facing each other in the thickness direction. And the first end is connected to the base,
A length direction connecting the first end portion and the second end portion of the vibration arm portion is defined as a first direction, and a width direction of the vibration arm portion orthogonal to the first direction is defined as a second direction. When the thickness direction of the vibration arm portion orthogonal to the first and second directions is a third direction, the vibration arm portion is disposed along the first direction. A plurality of through-holes penetrating the vibrating arm portion in the third direction are provided, and the excitation electrodes are formed on inner surfaces of the plurality of through-holes facing each other in the second direction. A tuning-fork type crystal resonator provided at least and having a cross-sectional shape orthogonal to the second direction of the through hole being a substantially parallelogram.   In a cross section perpendicular to the second direction of the through-hole, an angle formed by an inner side surface of the through-hole facing the first direction with the first main surface and the second main surface of the vibration arm portion. The tuning fork type crystal resonator according to any one of claims 1 to 3, wherein is an acute angle.   In a cross section orthogonal to the first direction of the through hole, an angle formed by an inner side surface of the through hole facing the second direction with the first main surface and the second main surface of the vibration arm portion is The tuning fork type crystal resonator according to any one of claims 1 to 3, which has an acute angle.   The tuning fork type crystal resonator according to any one of claims 1 to 5, wherein the plurality of through holes are provided close to the first end portion side of the vibration arm portion.   The tuning fork type crystal resonator according to any one of claims 1 to 6, wherein an end portion on a base side of a through hole closest to the base portion among the plurality of through holes is located in the base portion.   2. A weight portion connected to the second end portion of the vibration arm portion and further having a weight portion whose dimension along the second direction is larger than the dimension along the second direction of the vibration arm portion. The tuning-fork type crystal resonator according to any one of?   The tuning fork type crystal resonator according to claim 8, wherein the weight portion has a through hole or a concave portion. A base portion and a plurality of vibration arm portions, wherein each of the plurality of vibration arm portions includes a first end portion, a second end portion opposite to the first end portion, and a thickness direction. A tuning fork type vibration piece made of crystal having first and second main surfaces facing each other, the first end portion being connected to the base portion, and each of the plurality of vibration arm portions. A tuning fork type quartz crystal resonator comprising an excitation electrode,
A length direction connecting the first end portion and the second end portion of the vibration arm portion is defined as a first direction, and a width direction of the vibration arm portion orthogonal to the first direction is defined as a second direction. When the thickness direction of the vibrating arm portion orthogonal to the first and second directions is the third direction,
Forming the tuning fork-type vibrating piece having the base and the plurality of vibrating arms; and
Etching from the first main surface and the second main surface of the vibration arm portion after the tuning fork type vibration piece is formed or prior to the formation of the tuning fork type vibration piece, and arranged along the first direction. And forming a plurality of through holes penetrating the vibrating arm portion in the third direction;
Forming an excitation electrode on the vibration arm portion,
When forming the through hole by the etching, (total excitation electrode area in a cross section orthogonal to the second direction of the vibration arm portion) / (a plurality of through holes in a cross section orthogonal to the second direction of the vibration arm portion) The etching position on the first main surface side so that the effective excitation electrode ratio represented by the area of the region in which the hole is provided is larger than the case where the effective excitation electrode ratio is not shifted in the first direction; A method for manufacturing a tuning fork type crystal resonator, wherein the etching position on the second main surface side is shifted in the first direction.   The tuning fork type quartz vibration according to claim 10, wherein an etching position on the first main surface side and an etching position on the second main surface side are shifted so that the effective excitation electrode ratio becomes 0.77 or more. Child manufacturing method.

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