JP2014039235A - Vibrator and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibrator consisting of two vibration bodies coupled by a coupling part each configured so as to cause a contour vibration expanding and contracting between the center and outer edge of a piezoelectric thin film in full circumferential direction to occur mutually in the same phase, in which the contour vibration is restrained from being obstructed by the coupling part, and vibration energy is restrained from leaking via the coupling part.SOLUTION: A tuning-fork type vibration body 11 provided with a pair of vibration arms 14 is interposed between two vibration bodies 31. Then, the width dimension and/or the thickness dimension of the vibration arms 14 at opposite edges is made smaller than at a connection with the vibration bodies 31.

Description

  The present invention relates to a vibrator in which a vibrator is disposed on a substrate and an electronic component including the vibrator.

  For example, as a vibrator using the piezoelectric / reverse piezoelectric effect of a piezoelectric thin film such as aluminum nitride (AlN), the piezoelectric thin film is formed as, for example, a disk-shaped diaphragm, and, for example, molybdenum (Mo) is formed on the upper and lower surfaces of the diaphragm. A structure in which a conductive material such as is formed as an excitation electrode is known. In such a diaphragm, when a voltage is applied between the excitation electrodes, the diaphragm vibrates in a high-order vibration mode in which nodes are formed at, for example, three locations along the outer peripheral edge of the disk.

On the other hand, when the vibrator is configured so that the vibration of the diaphragm expands and contracts in the radial direction with the center of the diaphragm as a node when viewed in a plane, when trying to support the diaphragm so as not to inhibit this vibration, That is, if the diaphragm is supported so as to suppress the attenuation of vibration energy, the diaphragm is supported by the support portion from the back side at the center, for example. However, in such a support method, the characteristics of the vibrator vary depending on the accuracy of alignment (positioning) between the diaphragm and the support part and the size of the contact area between the diaphragm and the support part. For this reason, when the vibrator is manufactured industrially, a configuration in which the diaphragm is supported at the center is not suitable.
Patent Documents 1 to 5 describe a contour vibration type vibrator, but the above-described problems are not studied.

JP2008-124747 JP-A-2005-159620 Special table 2007-535275 JP-A-2005-348222 JP 2006-41911 A

  The present invention has been made in view of such circumstances, and an object of the present invention is to suppress vibration that the diaphragm expands and contracts in the radial direction with the center of the diaphragm as a node when viewed in a plane while suppressing the inhibition of vibration. An object of the present invention is to provide a vibrator and an electronic component that can be formed in the circumferential direction.

The vibrator of the present invention is
A base substrate;
A tuning fork type vibrating body having a pair of vibrating arm portions each extending so as to be separated from a base portion disposed on the base substrate, and an excitation electrode for vibrating each vibrating arm portion;
Out of the pair of vibrating arm portions, one vibrating arm portion and the other vibrating arm portion respectively support the outer edge portions and have diaphragms formed with excitation electrodes, respectively, so that contour vibrations occur in phase with each other. A first vibrating body and a second vibrating body configured in
An input / output port formed on the base and configured to input / output an electric signal to / from the pair of vibrating arms, the first vibrating body, and the second vibrating body;
The tuning fork type vibrating body is bent in a phase opposite to the vibration of the first vibrating body and the second vibrating body so as to absorb the contour vibration of the first vibrating body and the second vibrating body. Configured to vibrate,
The one vibrating arm portion and the other vibrating arm portion have a dimension at a connection portion with the base portion smaller than a dimension at a connection portion with the diaphragm with respect to at least one of a thickness dimension and a thickness dimension. It is formed so that it may become.

The one vibrating arm portion and the other vibrating arm portion are symmetrical to each other via a line extending along the length direction of the vibrating arm portion at an intermediate position between the vibrating arm portions when viewed in a plane. Each may be formed.
The vibrating arm portion, the diaphragm in the first vibrating body, and the diaphragm in the second vibrating body are simultaneously formed by dry etching using a resist mask,
The pair of vibrating arm portions may be formed such that a connecting portion with the base portion is thinner than a connecting portion with the diaphragm.
Each of the vibrating arm portions may be formed so as to gradually become thinner from the connecting portion side with the diaphragm toward the connecting portion side with the base portion.
The base portion may be formed on one end side and the other end side in the length direction of the pair of vibrating arm portions.
The electronic component of the present invention is
The vibrator according to any one of the above is provided.

  In the present invention, a tuning fork type vibration body having a base portion supported by a base substrate and a pair of vibration arm portions is interposed between two vibration bodies each configured so that contour vibrations occur in phase with each other. Yes. In addition, each vibrating arm portion is configured to bend and vibrate in a phase opposite to the vibration of the vibrating body so as to absorb the contour vibration of these vibrating bodies. And about the dimension of at least one of the thickness dimension of each vibration arm part and thickness dimension, the dimension in the connection part with a base is made smaller than the dimension in the connection part with a vibrating body. Therefore, it is possible to suppress the vibration of the vibrating body from being obstructed and the vibration of the vibrating arm portion from leaking to the base side, and when supporting the vibrating body on the base substrate, not the center of the vibrating body but the outer edge. Since it supports, deterioration of the electrical characteristic in a vibrating body can be suppressed, suppressing the dispersion | variation in a characteristic.

It is a perspective view which shows an example of the vibrator | oscillator of this invention. It is a top view which shows the said vibrator | oscillator. FIG. 3 is an enlarged plan view showing a part of the vibrator. It is a longitudinal cross-sectional view showing the vibrator. It is a longitudinal cross-sectional view showing the vibrator. It is a perspective view which shows the middle of the process which manufactures the said vibrator | oscillator. It is a schematic diagram which shows a mode that the said vibrator vibrates. It is a schematic diagram which shows a mode that the said vibrator vibrates. It is a characteristic view showing a simulation result obtained for the vibrator of the present invention. It is a characteristic view which shows the simulation result obtained about the conventional vibrator | oscillator. It is a characteristic view showing a simulation result obtained for the vibrator of the present invention. It is a characteristic view which shows the simulation result performed for the comparison with the vibrator | oscillator of this invention. FIG. 10 is an enlarged plan view showing a part of another example of the vibrator. It is a top view which expands and shows a part of another example of the vibrator. It is a top view which expands and shows a part of other example of the vibrator. FIG. 10 is an enlarged plan view showing a part of still another example of the vibrator. FIG. 10 is an enlarged plan view showing a part of another example of the vibrator. FIG. 10 is an enlarged plan view showing a part of another example of the vibrator. It is a perspective view which expands and shows a part of other examples of the vibrator. It is a perspective view which expands and shows a part of other examples of the vibrator. FIG. 6 is a plan view showing a part of another example of the vibrator. FIG. 6 is a plan view showing a part of another example of the vibrator. It is a perspective view which expands and shows a part of other examples of the vibrator. It is the schematic which shows the electric circuit where the said vibrator | oscillator is used.

  An example of a vibrator according to an embodiment of the present invention will be described with reference to FIGS. This vibrator is provided on a base substrate 1 made of silicon (Si), for example, and as shown in FIG. 1, a tuning fork type vibration supported by the base substrate 1 (detailed below is a nitride film 4). And a substantially disk-shaped vibrating body 31, 31 connected to both the left and right sides (X direction in FIG. 1) of the tuning fork type vibrating body 11. As shown in FIGS. 4 and 5, the vibrating bodies 31 and 31 are supported by the tuning fork type vibrating body 11 so as to float from the base substrate 1. As will be described later, when the contour vibration that expands and contracts between the center portion and the outer edge portion occurs in each of the vibrating bodies 31 and 31 in the circumferential direction, the vibrator is obstructed. In addition, the vibration energy is prevented from leaking to the base substrate 1 side through the tuning fork type vibrator 11. Hereinafter, the tuning fork type vibrating body 11 and the vibrating bodies 31 and 31 will be described in detail. 4 and 5 show longitudinal sections in which the vibrator is cut along lines AA and BB in FIG. 1, respectively. 1 to 5, the base substrate 1 is notched and drawn.

  On the base substrate 1, an oxide film 2 made of silicon oxide or the like and a nitride film 4 made of silicon nitride or the like are laminated in this order from the lower side, and the tuning fork vibrator 11 described above is The central portion in the length direction (Y direction in FIG. 2) is supported (fixed) on the nitride film 4 so as to float from the oxide film 2 and the nitride film 4. That is, the oxide film 2 and the nitride film 4 are formed with a substantially rectangular recess 3 that is slightly larger than the vibrator, and the tuning fork vibrator 11 has one end in the length direction as shown in FIG. The side and the other end extend to the back side and the near side from the recess 3, respectively, and the extended portions are fixed as base portions 12 and 12 on the nitride film 4, respectively.

  When “12a” and “12b” are added to the front side base portion 12 and the back side base portion 12 in FIG. 1, respectively, the tuning fork type vibrating body 11 and the vibration on the surface of the base portions 12a and 12b. Input / output ports 20a and 20b for inputting / outputting electric signals to / from the bodies 31 and 31 are formed. Specifically, the base portion 12a on the front side extends from the tuning fork-type vibrating body 11 side toward the front side and is enlarged in a trapezoidal shape when viewed in a plane. In addition, an opening 21 for exposing a metal film 16 (described later) formed integrally with the vibrating bodies 11, 31, 31 and the back surfaces of the base portions 12 a, 12 b is provided in the expanded diameter portion. . In addition, the aforementioned input / output port 20a made of a metal film is formed on the surface of the base 12a at a position spaced from the opening 21 toward the front side. The above-described metal film 16 exposed on the bottom surface side of the opening 21 and the input / output port 20a are formed through a mask after a series of processes for manufacturing a vibrator, for example. It is electrically connected by a metal film (not shown). The input / output port 20a is formed integrally with the vibration film 11, 31, 31 and the metal film 16 formed on the surface side of the base 12a, 12b, and then between the base 12a and the input / output port 20a. By removing the metal film 16, the metal film 16 on the surface side of the vibrating body 11 is electrically insulated.

  Further, of the two base parts 12a and 12b, the base part 12b on the back side extends while expanding in a substantially trapezoidal shape from the tuning fork-type vibrator 11 side to the back side, and branches so that the tip part is divided into left and right. ing. Then, as shown in FIG. 2, the tip portion branched right and left is bent toward the front side so as to wrap around the lateral sides of the vibrating bodies 31 and 31, and the side of the input / output port 20a described above. It extends to each position. Metal films 16 formed integrally (by a single film formation process) are respectively disposed on the surfaces of the base 12b and the vibrators 11, 31, and 31, and are formed at the two tip portions of the base 12b. The metal films 16 and 16 form input / output ports 20b and 20b, respectively. Thus, the central input / output port 20a among the three input / output ports 20a, 20b, and 20b arranged in the left-right direction is connected to the metal film 16 on the back surface side of the vibrating bodies 11, 31, and 31, and the left and right sides of the input / output port 20a. The input / output ports 20b, 20 are connected to the metal film 16 on the surface side of the vibrating bodies 11, 31, 31. In FIG. 2, the tuning fork type vibrator 11 and the vibrators 31 and 31 are hatched in the region where the metal film 16 is formed.

  An opening 13 extending in the length direction of the tuning fork type vibrator 11 extends in the central part of the tuning fork type vibrator 11 in a portion held in a state of being floated from the nitride film 4 between the base portions 12a and 12b. It is formed so as to penetrate in the vertical direction. Accordingly, the regions extending in the front-rear direction so as to connect the base portions 12 a and 12 b on the left and right sides of the opening portion 13 respectively constitute the vibrating arm portions 14 and 14 in the tuning fork type vibrator 11. As will be described later, these vibrating arm portions 14 and 14 are made of a piezoelectric thin film such as aluminum nitride (AlN). Therefore, a voltage is applied between the metal films 16 and 16 formed on the upper and lower surfaces of the piezoelectric thin film. When applied, the vibrating arm portions 14 and 14 bend and vibrate in the left-right direction. Specifically, the oscillation frequency f1 (for example, 30 to 200 MHz) in the bending vibration is f1 ≦ ± f2 × 1.2 so as to be the same frequency as the resonance frequency f2 in the vibrating bodies 31 and 31 and in the opposite phase. As described above, the length dimension and the width dimension of each of the vibrating arm portions 14 and 14 are adjusted. The metal films 16 and 16 on the upper and lower surfaces of the vibrating arm portions 14 and 14 form excitation electrodes for the vibrating arm portions 14 and 14 and input / output electric signals to and from the vibrating bodies 31 and 31 as will be described later. This is also used as a lead electrode.

  One end side of support portions 33 and 33 extending horizontally toward the vibrating bodies 31 and 31 is connected to the center portion in the length direction of each of the vibrating arm portions 14 and 14. And these vibrating arm parts 14 and 14 are enlarged in the lower side of FIG. 2, when viewed in a plane, compared to the connection parts of the support parts 33 and 33, both end parts in the length direction (base part) 12a and 12b side portions) are configured to be thin. Regarding the shape of the vibrating arm portions 14 and 14, of the vibrating arm portions 14 and 14, one vibrating arm portion 14 positioned on the right side when viewed from the input / output ports 20a and 20b on the near side is referred to FIG. I will explain.

  The vibrating arm portion 14 is formed in a substantially prismatic shape in a region in the vicinity of the connection portion with the vibrating body 31, and the width dimension W1 in the region is 5% to 30% of the diameter size of the vibrating body 31 in this example. It is 15 μm. And in the area | region of the front-end | tip part (end part by the side of the base 12b in FIG. 3) side of the vibration arm part 14, the vibration arm part 14 is a line which spaced apart 5-7 micrometers front side with respect to the connection surface with the base 12b. The diameter is reduced to a substantially trapezoidal shape from L toward the tip. That is, the vibrating arm portion 14 has a vibrating arm on the distal end side so that the width dimension W2 of the connection surface with the base portion 12b when viewed in a plane is 3% to 15% of the diameter dimension of the vibrating body 31. The angles θ formed between both side surfaces of the portion 14 and the line L are 45 °. Therefore, the vibrating arm portion 14 is symmetric with respect to a straight line passing through the center position of the vibrating arm portion 14 along the length direction of the vibrating arm portion 14 when viewed in a plane.

The front end portion (base portion 12a side) of the vibrating arm portion 14 is also formed in the same manner as the front end portion on the base portion 12b side described above, as shown in the lower side of FIG. The arm portion 14 is symmetric in the front-rear direction via straight lines passing through the center positions of the two vibrating bodies 31 when viewed in a plane.
The left vibrating arm portion 14 of the pair of vibrating arm portions 14 and 14 is also formed to have the same shape as the right vibrating arm portion 14. Thus, when seen in a plane, the pair of vibrating arm portions 14 and 14 are symmetrical with each other via a line extending along the length direction of the vibrating arm portions 14 and 14 at an intermediate position between the vibrating arm portions 14 and 14. ing.

  Here, the reason why the shape of the vibrating arm portion 14 is configured as described above will be described in detail. The vibrating arm portion 14 is configured to bend and vibrate at the same frequency as the contour vibration in the vibrating body 11 and in the opposite phase. The frequency of flexural vibration in the vibrating arm portion 14 is uniquely determined by the length dimension and the width dimension W1 of the vibrating arm portion 14. Accordingly, when the vibrator (vibrating body 11) is vibrated at a certain frequency, the vibrating arm portion 14 has to adopt a shape (dimension) corresponding to this frequency. However, if the vibrating arm portion 14 is formed in a uniform prismatic shape over the length direction, vibration energy propagates from both ends of the vibrating arm portion 14 to the base portions 12a and 12b, and the characteristics deteriorate. End up.

  Further, when the vibrating arm portion 14 is configured in a uniform prismatic shape in the length direction as described above, the both end portions are fixed by the base portions 12a and 12b, so that the both end portions are less likely to vibrate. Therefore, in order to vibrate the vibrating arm portion 14 at a frequency corresponding to the vibration frequency of the vibrator, it is necessary to lengthen the length of the vibrating arm portion 14 so that both ends are less likely to vibrate. Accordingly, the vibrator becomes large. Further, the metal film 16 for inputting / outputting signals to / from the vibrating bodies 11, 31, 31 also increases in length and increases in electrical resistance by the length of the vibrating arm portion 14. It will lead to deterioration of characteristics. Further, with respect to the width dimension W2 at both ends of the vibrating arm portion 14, for example, if it is attempted to make the width dimension W1 larger than the width dimension W1 in order to improve the strength of the vibrating arm portion 14, the both end portions are further less likely to vibrate. Will become even more prominent.

  On the other hand, when the width dimension W2 described with reference to FIG. 3 is set along the length direction of the vibration arm section 14, for example, the vibration arm section 14 is formed so as to be as thin as both ends along the length direction. Then, the frequency of the bending vibration of the vibrating arm portion 14 is shifted from the frequency of the vibrator, and the strength for supporting the vibrating body 11 while bending vibration is insufficient.

  Therefore, in the present invention, the both ends of the vibrating arm portion 14 are made thinner than the central portion while setting the frequency of the bending vibration in the vibrating arm portion 14 to a value corresponding to the frequency of the vibrator. Accordingly, while the frequency shift in the vibrating arm portion 14 is suppressed, leakage of vibration of the vibrating arm portion 14 toward the base portions 12a and 12b is suppressed. That is, the smaller the contact area between the vibrating arm portion 14 and the base portions 12a and 12b, the harder the vibration is physically propagated.

  In addition, since the both end portions of the vibrating arm portion 14 are thinned, the both end portions are supported so as to be able to vibrate, so that the inhibition of vibration is suppressed at both end portions. Therefore, when bending the vibrating arm portion 14 at a certain frequency, the length of the vibrating arm portion 14 is set when the both end portions are set to the same thickness as the central portion or when both end portions are thicker than the central portion. Shorter than that. Therefore, electrical resistance in the metal film 16 that inputs and outputs signals to and from the vibrators 11, 31, and 31 is also suppressed, and deterioration of characteristics is suppressed.

  The outer edge portions of the vibrating bodies 31 and 31 each formed in a substantially disc shape having a diameter of, for example, 50 μm are connected to the distal ends of the support portions 33 and 33 extending from the vibrating arm portions 14 and 14, respectively. The vibrating bodies 31 and 31 are composed of piezoelectric thin films (vibrating plates) such as aluminum nitride, and the above-described metal films 16 and 16 are formed on the upper and lower surfaces as excitation electrodes. The vibrating bodies 31 and 31 are configured such that contour vibration that expands and contracts in the radial direction occurs in the circumferential direction with the central portion of the vibrating bodies 31 and 31 as a node. At this time, the vibrating bodies 31 and 31 vibrate in phase with each other, that is, when one vibrating body 31 expands, the other vibrating body 31 expands in the same manner and when one vibrating body 31 contracts. The other vibrating body 31 is also formed so that the diameters and the like are aligned with each other so as to contract.

  Next, a method of manufacturing a vibrator including the tuning fork type vibrator 11 and the vibrators 31 and 31 will be briefly described by taking a technique using a MEMS (Micro Electro Mechanical System) method as an example. First, an oxide film 2 is formed on the base substrate 1, and patterning (etching) is performed on the oxide film 2 so as to correspond to the shape of the recess 3. Next, a nitride film 4 is formed along the inner wall surface of the recess 3 formed in the oxide film 2, and a sacrificial film (not shown) is stacked so as to be thicker than the depth of the recess 3. Then, CMP (Chemical Mechanical Policing) is performed so that the inner region of the recess 3 on the nitride film 4 is filled with the sacrificial film and the nitride film 4 in the region outside the recess 3 is exposed. Subsequently, a metal film 16 made of molybdenum (Mo) or the like is formed on the base substrate 1 (nitride film 4), and the metal film 16 is formed so as to have the shapes of the vibrators 11, 31, 31 and the base portions 12a, 12b. Perform patterning. Note that the above series of steps includes the formation of a photoresist film, pattern transfer to the photoresist film, and dry etching treatment of the lower layer film of the photoresist film in patterning each film. Is explained.

  Next, on the metal film 16, a piezoelectric thin film 41 made of aluminum nitride (AlN) constituting the vibrators 11, 31, 31 and the like, and a metal film 16 made of molybdenum or the like are laminated in this order from the lower side. The metal film 16 is patterned so that a portion corresponding to 1 remains. In this patterning, in order to prevent a pattern shift between the piezoelectric thin film 41 and the metal film 16 on the upper surface side of the piezoelectric thin film 41, only a region corresponding to the opening 21 and a portion around the region are removed. You may make it.

  Then, an insulating film 42 made of a silicon oxide film or the like and a resist mask 43 made of an organic material are stacked on the base substrate 1 in this order from the lower side, and the vibrators 11, 31 are formed on the resist mask 43. , 31 and the base portions 12a, 12b, etc., patterning is performed so that portions other than the regions corresponding to the openings are opened. FIG. 6 shows the resist mask 43 after patterning, and the resist mask 43 on the upper side of the vibrating arm portions 14, 14 has both ends in the length direction so as to correspond to the shape of the vibrating arm portions 14, 14. The portion is formed so that the width dimension is smaller than the central region between the both end portions. Accordingly, when the insulating film 42 on the lower side is etched through the resist mask 43, and then the resist mask 43 is peeled off and the piezoelectric thin film 41 is etched using the insulating film 42 as a mask, the vibrating body 11 having a shape corresponding to FIG. , 31, 31 and the like are obtained.

  Subsequently, in order to form the opening 21, after patterning the insulating film 42, another mask is formed on the upper side of the insulating film 42, and the piezoelectric thin film 41 is etched to form a lower metal film. 16 is exposed. Thereafter, for example, a resist film (not shown) patterned so as to expose the sacrificial film embedded in the recess 3 is formed, and exposed on the base substrate 1 by wet etching using a hydrofluoric acid-based etchant. The silicon oxide film is removed. Thus, after passing through the cleaning process and the like, the vibrator shown in FIG. 1 is obtained. After that, for example, by dicing, the vibrators formed in large numbers in the vertical and horizontal directions on the base substrate 1 are separated into pieces.

  For example, when an electric signal is input from the outside to the vibrator formed by the above steps via the input / output ports 20a and 20b, the vibrators 31, 31 and the tuning fork vibrator 11 oscillate at the respective resonance frequencies ( The electric signal based on this oscillation is taken out via the input / output ports 20a and 20b. Specifically, for example, in the vibrating bodies 31, 31, contour vibration that expands and contracts in the radial direction occurs in the circumferential direction. Further, in the tuning fork type vibrating body 11, bending vibration occurs so that the vibrating arm portions 14, 14 are close to or away from each other. Accordingly, when each vibrating body 31 is viewed in a plane, the contour vibration is symmetric in the left and right and front and rear directions through the center of the vibrating body 31.

  At this time, since the vibrating bodies 31 and 31 have the same diameter and the like, the contour vibrations occur in phase with each other. Further, in the tuning fork type vibrating body 11, the dimensions are adjusted so that bending vibrations occur at the same frequency and in the opposite phase as the vibrating bodies 31 and 31. Therefore, as shown in FIG. 7, when the vibrating bodies 31 and 31 contract, the vibrating arms 14 and 14 bend and vibrate so as to be separated from each other, while when the vibrating bodies 31 and 31 expand, FIG. As shown in FIG. In this way, in the tuning fork type vibrating body 11, bending vibration is generated so that the expansion and contraction vibrations of the vibrating bodies 31 and 31 are absorbed, that is, the center positions of the vibrating bodies 31 and 31 are not displaced due to the contour vibration. . 7 and 8, the state of vibration of the tuning fork type vibrating body 11 and the vibrating bodies 31 and 31 is exaggerated.

  Further, when the vibrating arm portion 14 is bent and vibrated, both end portions of the vibrating arm portion 14 are made thinner than the center side, so that the energy of the bending vibration is less likely to leak to the base portions 12a and 12b. Yes. That is, the smaller the area of the connecting surface between the vibrating arm portion 14 and the base portions 12a and 12b, the more difficult the vibration in the vibrating arm portion 14 propagates to the base portions 12a and 12b side. Therefore, attenuation of the vibration level in the vibrating arm portion 14 is suppressed.

  Here, FIG. 9 shows the result of analyzing the vibration mode of the vibrator of the present invention by simulation. In addition to the vibrators 31, 31, the tuning fork type vibrator 11 vibrates (deforms) so that each vibrator In 31 and 31, a node (region where the amount of deformation is small) is formed at the center of each vibrating body 31, 31, and the amount of deformation increases toward the outer peripheral side, and further uniform deformation over the circumferential direction. It was an ideal vibration mode. In this simulation, the vibrating arm portions 14 and 14 are each formed in a prismatic shape (both ends are not thinned).

On the other hand, when, for example, a rectangular connecting portion is provided between the vibrating bodies 31 and 31 instead of the tuning fork type vibrating body 11, a node is formed at the approximate center of the vibrating bodies 31 and 31, as shown in FIG. However, the amount of deformation was not uniform in the radial direction and the circumferential direction. Therefore, it can be seen that the Q value is deteriorated in FIG. 10 than in the case of FIG.
FIG. 11 shows the result of analyzing the stress when resonance occurs in the case where both end portions of the vibrating arm portions 14 and 14 are thinner than the center portion. Although stress is generated in the base portions 12a and 12b, it can be seen that the stress is extremely small. On the other hand, when both ends of the vibrating arm portion 14 are made thinner than the central portion without making the both ends narrow, stress is generated over a wide range of the base portions 12a and 12b, as shown in FIG. Therefore, the vibration of the vibrating arm portion 14 is largely propagated to the base portions 12a and 12b.

  According to the above-described embodiment, when the tuning fork type vibrating body 11 is interposed between the two vibrating bodies 11, 11, the vibrating arm portion 14 is made narrower than the center portion, so that the vibrating arm portion 14 Since the vibration energy of 14 is prevented from leaking to the base portions 12a and 12b, deterioration of characteristics can be suppressed. Further, by making the both end portions of the vibrating arm portion 14 thinner than the central portion, the length dimension of the vibrating arm portion 14 can be suppressed as described above, so that the electrical resistance of the vibrator is suppressed. Thus, a vibrator having a small size and good characteristics can be obtained. The resistance value calculated for the vibrator shown in FIG. 11 was 20Ω, whereas it was 30Ω for the vibrator shown in FIG. 12, confirming a great improvement of 30%. That is, if the tuning fork type vibrating body 11 is to be vibrated at a certain frequency, in FIG. 12, it is necessary to increase the length dimension so that the vibration is inhibited at both ends of the vibrating arm portion 14, and therefore the vibration of FIG. The electrical resistance is larger than that of the child.

  Further, when making the both end portions of the vibrating arm portion 14 thinner than the center portion side, a process of forming the outer shape of the vibrating arm portion 14 by etching the piezoelectric thin film 41 is used. Compared with the case where a process different from the series of processes is provided, a decrease in throughput can be suppressed. Therefore, in suppressing the leakage of the vibration energy of the vibrating arm portion 14, the method of the present invention is higher in productivity than the case of constricting the side surfaces of the base portions 12a and 12b, for example.

  Further, the tuning fork type vibrating body 11 is interposed between the vibrating bodies 31 and 31 that generate contour vibrations in phase with each other, and the vibration of the tuning fork type vibrating body 11 is absorbed so that the expansion and contraction of the vibrating bodies 31 and 31 is absorbed. The bodies 31 and 31 are vibrated in opposite phases. Therefore, since it can suppress that the vibration in each vibrating body 31 and 31 is inhibited, deterioration of an electrical property can be suppressed. Since the outer edge of the vibrating body 31 is supported instead of the center of the vibrating body 31 when viewed in a plane, the aforementioned contour vibration can be formed while suppressing the inhibition of vibration. Therefore, even when a large amount of vibrators are manufactured industrially, variation in characteristics between the vibrators can be suppressed.

  As described above, according to the present invention, in addition to this role, the two vibrating bodies 31 and 31 are coupled to each other and supported by the base substrate 1. It has a role as a vibrating body. On the other hand, conventionally, attention has not been paid to the function as a vibrating body for the connecting portion, and thus the shape and dimensions of the connecting portion have not been studied. That is, in the configuration as in Patent Document 1 described in the background section above, since the connecting portion is extremely smaller in size than the diaphragm, even if the connecting portion vibrates, the vibration of the diaphragm The frequency is much higher than the frequency, so that it can be said that it is not oscillating when viewed from the diaphragm.

In contrast, in the present invention, as described above, the connecting portion between the vibrating bodies 31 and 31 is configured as the tuning fork type vibrating body 11 so as to vibrate in the opposite phase of the vibrating bodies 31 and 31. At this time, the bending vibration has a lower oscillation frequency than the contour vibration described above even if the vibrating body (tuning fork type vibrating body 11 or vibrating body 31) has the same dimensions. In other words, when the tuning fork type vibrating body 11 is oscillated at the same frequency as the vibrating body 31, the tuning fork type vibrating body 11 may be smaller in size than the vibrating body 31. Therefore, when the tuning fork type vibrating body 11 is oscillated at the same frequency and in the opposite phase as the vibrating bodies 31 and 31, it is not necessary to increase the size to the same level as the vibrating body 31. Deterioration of electrical characteristics can be suppressed.
Further, since the base portions 12 and 12 are provided on both sides of the vibrating arm portions 14 and 14, the vibrating arm portions 14 and 14 can be firmly held with respect to the base substrate 1 when the vibrating arm portions 14 and 14 vibrate.

  Other examples of the vibrator described above are listed below. 13 and 14 show an example in which the width dimension W1 is reduced in a curved line instead of linearly decreasing the width dimension W1 from the center side toward the end side at both ends of the vibrating arm portion 14. Show. In FIG. 13, the vibrating arm portions 14 at both ends are formed in an arc shape so that the outer edge portion swells outward, while in FIG. 14, the vibrating edge portions 14 are formed in an arc shape so that the outer edge portion narrows inward.

  FIG. 15 shows an example in which a plurality of step portions 51 are provided at both ends of the vibrating arm portion 14 so that the width dimension W1 of the vibrating arm portion 14 is reduced in a stepwise manner. FIG. 16 is a schematic triangular view of one vibrating arm portion 14 of the pair of vibrating arm portions 14 on the side surface on the other vibrating arm portion 14 side (inner side) at both ends, for example, when viewed in a plane. In the example, the notch portions 52 are respectively formed, and the side surfaces of both end portions on the vibrating body 11 side (outside) are linearly formed from the central portion side to the base portions 12a and 12b. Accordingly, the one vibrating arm portion 14 is asymmetric through a straight line passing through the center of the vibrating arm portion 14 along the length direction when the vibrating arm portion 14 is viewed in a plane. The other vibrating arm portion 14 is symmetric with respect to the vibrating arm portion 14 on one side via a straight line passing along the length direction of the vibrating arm portion 14 at an intermediate position between the vibrating arm portions 14 and 14. It is formed to become.

  Further, FIG. 17 shows an example in which the vibrating arm portion 14 is formed so as to bulge outward as it goes from the central portion side to the end portion side, and then shrinks to the above-mentioned width dimension W2. Furthermore, FIG. 18 shows that the vibrating arm portion 14 is positioned closer to the base portions 12a and 12b than the previously described line L than the vibrating arm portion 14 instead of reducing both ends linearly or curvedly. An example in which columnar portions each having a slightly thinner width (width dimension W2) are provided is shown.

  Furthermore, FIG. 19 shows an example in which both end portions of the vibrating arm portion 14 are made thinner instead of making the both end portions thinner than the center portion side. In this case, after forming the piezoelectric thin film 41 on the base substrate 1 and before forming the upper metal film 16, the both end portions are etched through a resist film (not shown), and then the metal film 16. Form. Furthermore, the both end portions may be thinned as described above and may be thinned as described above.

  In summary, the vibrating arm portion 14 of the present invention is connected to the base portions 12a and 12b with respect to at least one of the width dimension (thickness dimension) and the thickness dimension rather than the dimension at the connection portion with the vibrating body 11. What is necessary is just to form so that the dimension in a site | part may become small. In FIG. 19, drawing of the metal film 16 is omitted, and the base portions 12a and 12b are partially cut away.

  In FIG. 20, approximately columnar support portions 55 are arranged at two positions in the left-right direction above the base portions 12 a and 12 b so that the vibrating arm portion 14 is supported by the support portions 55 from below. A configured example is shown. The vibrating arm portion 14 is formed in a prismatic shape so that the width dimension W1 is constant over the length direction. Further, the surface area of the support portion 55 when viewed in a plane is formed to be smaller than the cross-sectional area when the vibrating arm portion 14 is cut along a plane orthogonal to the length direction. Since the support portion 55 is for supporting the vibrating arm portion 14 and thus can be said to be a part of the base portions 12a and 12b, and may vibrate together with the vibrating arm portion 14, the vibrating arm It can also be said that it forms part of the part 14. Therefore, in the present invention, it can be said that the width dimension and the thickness dimension of the portion on the base substrate 1 side in the vibrating arm portion 14 are smaller than the connecting portion with the vibrating body 11.

  20 will be briefly described. The outer shape of the vibrating arm portion 14 is not formed in the insulating film 42 and the resist mask 43 for etching the piezoelectric thin film 41. As shown in FIG. That is, patterning is performed so that the space between the two base portions 12a and 12b is exposed. Then, after the base portions 12a and 12b and the vibrating body 11 are formed, the support portion 55 is formed by forming and etching the piezoelectric thin film again. Next, similarly, the piezoelectric thin film is formed and etched to form the vibrating arm portion 14 above the support portion 55. For example, when a masking agent patterned so as to expose a portion where the upper-layer metal film 16 is disposed is applied to the structure thus formed, for example, electroless plating is performed on the structure. A metal film 16 is formed.

  Further, the tuning fork type vibrating body 11 may be configured to oscillate in a phase opposite to that of the vibrating bodies 31, 31. For example, as shown in FIG. 21, the opening 13 may be formed in a substantially elliptical shape. Furthermore, as shown in FIG. 22, the opening 13 may be formed in a substantially circular shape, and the vibrating arm portions 14 and 14 may be formed in a substantially arc shape along the periphery of the opening 13. Furthermore, as shown in FIG. 23, for example, the configuration may be adopted in which the vibrating arm portions 14 and 14 are each supported in a cantilever manner by the base portion 12b on the back side without providing the base portion 12a on the near side. In FIG. 23, the input / output port 20a and the opening 21 are each formed on the base 12b side.

  An example of an electric circuit of an electronic component (oscillator) in which the vibrator of the present invention described above is incorporated in an oscillation circuit will be briefly described with reference to FIG. FIG. 24 shows an example in which a Colpitts circuit including two capacitors C and C connected in series with each other and a transistor 101 is provided, and the base terminal of the transistor 101 is connected to the vibrator 100 of the present invention and the variable capacitor. A series circuit consisting of C1 is connected. A power supply unit 102 is connected to a connection point between the base terminal and the vibrator 100, and an output port 103 for extracting an electric signal is connected to a collector terminal of the transistor 101. In FIG. 25, 104 is a resistor, and 105 is an inductance.

  If the width dimension W2 at the connecting portion between the vibrating arm section 14 and the base parts 12a and 12b is too large (too close to the width dimension W1 on the center side of the vibrating arm section 14), the vibration of the vibrating arm section 14 is reduced. The role of suppressing leakage becomes small, while if it is too small, it becomes difficult to physically support the vibrating arm portion 14 and the vibrating body 11, and therefore it is preferably in the range described above. Further, the smaller the diameter dimension of the vibrating body 11 (the higher the vibration frequency of the vibrating body 11), the thinner the width dimension W1 of the vibrating arm 14 corresponding to the vibration frequency of the vibrating body 11 (or thicker). Accordingly, the difference between the width dimensions W1 and W2 is difficult to be obtained. On the other hand, when the diameter of the vibrating body 11 is increased, the etching time is increased and the number of vibrators that can be formed on the base substrate 1 is reduced when the above-described MEMS method is used. Therefore, the diameter of the vibrating body 11 is preferably 60 μm to 390 μm, for example, and is 100 MHz to 14 MHz in terms of the vibrator frequency.

  Further, the length dimension (dimension between the line L and the base portion 12b in FIG. 3) d of the region in which the width dimension or the thickness dimension is reduced with respect to the central portion in the length direction of the vibrating arm section 14 is small. If it is too large, patterning becomes difficult. On the other hand, if it is too large, the electrical loss increases and leads to an increase in electrical resistance. Further, the pair of vibrating arm portions 14 and 14 are formed so as to be symmetric with each other, but the vibrating arm portions 14 and 14 are formed so as to be asymmetric with each other, and the vibrating arm portions 14 and 14 have the same frequency and The thickness dimension and the width dimension may be adjusted so as to bend and vibrate in the same phase. The vibrating bodies 31 and 31 described above may be oval, triangular, quadrangular or the like instead of being formed in a circular shape.

Further, in the tuning fork type vibrator 11, a metal film includes an excitation electrode for vibrating the tuning fork type vibrator 11 and an extraction electrode for connecting the excitation electrodes of the vibrators 31, 31 and the input / output ports 20a, 20b. However, the excitation electrode and the extraction electrode may be arranged separately.
In the above example, an example in which the vibrator of the present invention is incorporated in an oscillation circuit has been described. However, this vibrator may be used as a filter (electronic component). In this case, the electrical signal input to the input / output port 20a (20b) is taken out from the input / output port 20b (20a) after unnecessary electrical signals are removed from the vibrator.

  Here, the difference between the present invention described above and Japanese Patent Application Laid-Open No. 2008-124747, which is a known example described in the above background, will be described again. In this publicly known example, it is described that this vibration becomes a “radial extension mode with a node at the center (Radial Extension mode)”. However, when the present inventors are connected and supported by the “schematic box-shaped connecting portion”, as can be seen from the above-described FIG. 10, “the higher-order non-ideal in which a plurality of nodes are generated on the outer peripheral portion. It was found by numerical analysis that the vibration mode was achieved. In this vibration mode, electrical characteristics are deteriorated due to vibration leakage or the like. On the other hand, in this embodiment, as shown in FIG. 9, the “vibration arm portion” is formed on the support portion to eliminate “influence by the support portion”, and the “center of the diaphragm” that could not be realized in the conventional configuration. It is possible to form an “ideal vibration” in which the diaphragm expands and contracts in the radial direction with the node as a node over the circumferential direction.

DESCRIPTION OF SYMBOLS 1 Base substrate 11 Tuning fork type vibrating body 12 Base 14 Vibrating arm 20 Input / output port 31 Vibrating body 43 Resist mask

Claims (6)

A base substrate;
A tuning fork type vibrating body having a pair of vibrating arm portions each extending so as to be separated from a base portion disposed on the base substrate, and an excitation electrode for vibrating each vibrating arm portion;
Out of the pair of vibrating arm portions, one vibrating arm portion and the other vibrating arm portion respectively support the outer edge portions and have diaphragms formed with excitation electrodes, respectively, so that contour vibrations occur in phase with each other. A first vibrating body and a second vibrating body configured in
An input / output port formed on the base and configured to input / output an electric signal to / from the pair of vibrating arms, the first vibrating body, and the second vibrating body;
The tuning fork type vibrating body is bent in a phase opposite to the vibration of the first vibrating body and the second vibrating body so as to absorb the contour vibration of the first vibrating body and the second vibrating body. Configured to vibrate,
The one vibrating arm portion and the other vibrating arm portion have a dimension at a connection portion with the base portion smaller than a dimension at a connection portion with the diaphragm with respect to at least one of a thickness dimension and a thickness dimension. Each of the vibrators is formed so as to be.   The one vibrating arm portion and the other vibrating arm portion are symmetrical to each other via a line extending along the length direction of the vibrating arm portion at an intermediate position between the vibrating arm portions when viewed in a plane. The vibrator according to claim 1, wherein each vibrator is formed. The vibrating arm portion, the diaphragm in the first vibrating body, and the diaphragm in the second vibrating body are simultaneously formed by dry etching using a resist mask,
3. The vibrator according to claim 1, wherein the pair of vibrating arm portions are formed such that a connection portion with the base portion is narrower than a connection portion with the vibration plate.   4. Each of the vibrating arm portions is formed so as to be gradually narrowed from the connecting portion side to the diaphragm toward the connecting portion side to the base portion. The vibrator according to one.   5. The vibrator according to claim 1, wherein the base portion is formed on each of one end side and the other end side in the length direction of the pair of vibrating arm portions.   An electronic component comprising the vibrator according to claim 1.