Resonator and resonant device

Abstract

The present invention provides a resonator and a resonant device, which improve the limiting property of vibration. The resonator (10) comprises: a vibration part (120), which comprises a Si substrate (F2), a metal layer (E1) formed on one main surface of the Si substrate (F2), and a piezoelectric film (F3) arranged between the Si substrate (F2) and the metal layer (E1), wherein the vibration part (120) vibrates mainly by contour vibration; a holding part (140) formed to surround at least a part of the vibration part (120); and a supporting unit (110) connecting the vibration part (120) and the holding part (140), wherein the vibration part (120) has a concave part (121) formed by removing the piezoelectric film (F3) from one main surface.

Description

Technical Field

[0001] The present invention relates to a resonator and a resonant device vibrating in a contour vibration mode. Background Art

[0002] In the past, resonant devices using MEMS (Micro Electro Mechanical Systems) technology were used, for example, as timing devices. The resonant device is mounted on a printed circuit board assembled in electronic devices such as smartphones. The resonant device includes: a lower substrate, an upper substrate forming a cavity between the lower substrate and the upper substrate, and a resonator arranged in the cavity between the lower substrate and the upper substrate.

[0003] For example, Patent Document 1 discloses a vibrating body utilizing a broadened mode, wherein the vibrating body has a resonance portion, the resonance portion having a rectangular piezoelectric body, and a plurality of resonance electrodes formed on the outer surface of the piezoelectric body, wherein when the length of the short side of a pair of rectangular surfaces on both sides of the polarization direction of the piezoelectric body is set to a, the length of the long side is set to b, and the Poisson's ratio of a material constituting the piezoelectric body is set to σ, the length ratio b / a of the long side to the short side is within a range of ±10% centered on a specified value, and when an AC voltage is applied between the plurality of resonance electrodes, a broadened mode having the short side direction as the width direction is excited.

[0004] Patent Document 1: Japanese Patent No. 3139274

[0005] Since the vibrator described in Patent Document 1 has electrodes formed on both principal surfaces of the piezoelectric body, the structure of the vibrator in the thickness direction can be symmetrical.

[0006] However, when an electrode is formed on one main surface of the substrate, the structure of the vibrating portion in the thickness direction, for example, the Z-axis direction, becomes asymmetric, so the vibrating portion bends in the Z-axis direction, and the supporting portion connecting the vibrating portion and the holding portion is displaced in the Z-axis direction. As a result, the vibration of the vibrating portion leaks to the holding portion through the supporting portion, and there is a case where the vibration restriction is reduced. Summary of the invention

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resonator and a resonance device capable of improving the limiting property of vibration.

[0008] A resonator according to one aspect of the present invention comprises:

[0009] A vibration unit including a substrate, a first electrode formed on one main surface of the substrate, and a piezoelectric layer disposed between the substrate and the first electrode, wherein the vibration unit vibrates mainly by contour vibration;

[0010] a holding portion formed to surround at least a portion of the vibration portion; and

[0011] The supporting part connects the vibration part and the holding part,

[0012] The vibration portion has a recessed portion formed by removing the piezoelectric layer from one main surface.

[0013] A resonance device according to one aspect of the present invention comprises:

[0014] The resonator as described above; and

[0015] Cover body.

[0016] According to the present invention, the vibration limiting performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a perspective view schematically showing the appearance of a resonance device according to one embodiment of the present invention.

[0018] Figure 2 It is schematically indicated Figure 1 An exploded perspective view of the structure of the resonance device shown.

[0019] Figure 3 It is schematically indicated Figure 2 A top view of the resonator configuration is shown.

[0020] Figure 4 is a schematic representation of the Figure 3 The cross-sectional view of the structure of the cross section taken along line IV-IV is shown.

[0021] Figure 5 is a schematic representation of the Figure 3 The cross-sectional view of the structure of the cross section taken along the line VV is shown.

[0022] Figure 6 This is a graph showing an example of the relationship between the displacement in the longitudinal direction (Y-axis direction) of the support unit and the aspect ratio of the vibration part.

[0023] Figure 7 : is a graph showing an example of the relationship between the displacement in the thickness direction (Z-axis direction) of the support unit and the aspect ratio of the vibration part.

[0024] Figure 8 This is a graph showing an example of the relationship between the magnitude of displacement in the thickness direction (Z-axis direction) of the support unit and the aspect ratio of the vibration portion.

[0025] Fig. 9 This is a graph showing an example of the relationship between the evaluation index in the thickness direction (Z-axis direction) of the support unit and the aspect ratio of the vibration portion.

[0026] Fig.10 Yes means Figure 3 FIG. 1 is a perspective view of a first modified example of the structure of the periphery of the vibrating portion.

[0027] Fig.11 Yes means Figure 3 1 is a perspective view of a second modified example of the structure of the periphery of the vibrating portion shown. DETAILED DESCRIPTION

[0028] The following is an explanation of the embodiments of the present invention. In the following drawings, the same or similar reference numerals are used to represent the same or similar components. The drawings are illustrative, and the size and shape of each part are schematic, and should not be understood as limiting the technical scope of the present invention to the embodiments.

[0029] [Implementation Method]

[0030] First, refer to Figure 1 and Figure 2 A schematic structure of a resonance device according to one embodiment of the present invention will be described. Figure 1 It is a perspective view schematically showing the appearance of a resonance device 1 according to one embodiment of the present invention. Figure 2 It is schematically indicated Figure 1 The structure of the resonance device 1 is shown in an exploded perspective view.

[0031] The resonance device 1 includes a resonator 10, a lower cover 20, and an upper cover 30. That is, the resonance device 1 is configured by sequentially stacking the lower cover 20, the resonator 10, and the upper cover 30. The lower cover 20 and the upper cover 30 of this embodiment correspond to an example of the "cover body" of the present invention.

[0032] Hereinafter, each structure of the resonance device 1 will be described. In the following description, the side of the resonance device 1 provided with the upper cover 30 is referred to as the upper side (or the front side), and the side provided with the lower cover 20 is referred to as the lower side (or the back side).

[0033] The resonator 10 is a MEMS oscillator manufactured using MEMS technology. The resonator 10 is bonded to the lower cover 20 and the upper cover 30. In addition, the resonator 10, the lower cover 20, and the upper cover 30 are respectively formed using a silicon (Si) substrate (hereinafter referred to as a "Si substrate"), and the Si substrates are bonded to each other. In addition, the resonator 10 and the lower cover 20 can also be formed using an SOI substrate.

[0034] The upper cover 30 extends in a flat plate shape along the XY plane, and a flat rectangular concave portion 31 is formed on the back of the upper cover 30, for example. The concave portion 31 is surrounded by a side wall 33, and forms a space for the resonator 10 to vibrate, that is, a part of the vibration space. In addition, the upper cover 30 may not have the concave portion 31, but may have a flat plate-like structure. In addition, a getter layer may be formed on the surface of the concave portion 31 of the upper cover 30 on the side of the resonator 10.

[0035] The lower cover 20 has a bottom plate 22 in the shape of a rectangular plate arranged along the XY plane, and a side wall 23 extending from the edge of the bottom plate 22 in the Z-axis direction, that is, the stacking direction of the lower cover 20 and the resonator 10. In the lower cover 20, a recess 21 formed by the surface of the bottom plate 22 and the inner surface of the side wall 23 is formed on the surface opposite to the resonator 10. The recess 21 forms a part of the vibration space of the resonator 10. In addition, the lower cover 20 may not have the recess 21, but may have a flat plate-like structure. In addition, a getter layer may be formed on the surface of the recess 21 of the lower cover 20 on the resonator 10 side.

[0036] The vibration space of the resonator 10 is hermetically sealed and maintained in a vacuum state by the upper cover 30 and the lower cover 20. Alternatively, the vibration space may be filled with a gas such as an inert gas.

[0037] Next, refer to Figure 3 A schematic structure of a resonator 10 according to one embodiment of the present invention will be described. Figure 3 It is schematically indicated Figure 2 The structure of the resonator 10 is shown in a top view.

[0038] like Figure 3 As shown, the resonator 10 is a MEMS oscillator manufactured using MEMS technology. The resonator 10 includes a vibrating portion 120, a holding portion 140, and a supporting unit 110. The supporting unit 110 of this embodiment corresponds to an example of the "supporting portion" of the present invention.

[0039] When the surface facing the upper cover 30 is viewed from above, the vibration part 120 has a Figure 3 The outline of the rectangle extending in the XY plane in the orthogonal coordinate system shown in FIG. The vibrating portion 120 is provided inside the holding portion 140 , and a space is formed between the vibrating portion 120 and the holding portion 140 at a predetermined interval.

[0040] like Figure 3 As shown, in a plan view, the vibration part 120 has a main surface with a length L along the Y-axis direction and a width W along the X-axis direction. In addition, the aspect ratio (dimension ratio) of the vibration part 120 is expressed by the length L relative to the width W, that is, L / W. For example, the length L is about 171 μm and the width W is about 120 μm. In this case, the aspect ratio L / W is about 1.425.

[0041] The vibration part 120 includes a metal layer E1. The metal layer E1 has a shape along the contour of the vibration part 120. When viewed from above, the length of the metal layer E1 along the Y-axis direction is substantially the same as the length L of the vibration part 120, and the width along the X-axis direction is substantially the same as the width W of the vibration part 120. In addition, the metal layer E1 is not limited to a shape along the contour of the vibration part 120, and can be formed from one end to the other end of the vibration part 120 in the Y-axis direction. In addition, the metal layer E1 of this embodiment corresponds to an example of the "first electrode" of the present invention.

[0042] In addition, a protective film 125 is formed on the surface of the vibration part 120 (the surface facing the upper cover 30) so as to cover the entire surface. The details of the protective film 125 will be described later.

[0043] The vibration part 120 has, for example, four recessed parts 121. In a plan view, each recessed part 121 has a square shape, and the length of one side is about 9 μm.

[0044] In addition, each recess 121 is arranged at a position offset from the center of the vibration part 120 in a plan view. That is, each recess 121 is formed at a position separated by a length Loff from a center line CL1 in the Y-axis direction of the vibration part 120. In addition, each recess 121 is formed at a position separated by a width Woff from a center line CL2 in the X-axis direction of the vibration part 120.

[0045] The offset ratio of the Y-axis direction in each concave portion 121 is represented by the length Loff relative to the length L of the vibration portion 120, that is, Loff / L. The offset ratio in the Y-axis direction is, for example, about 0.4. In addition, the offset ratio of the X-axis direction in each concave portion 121 is represented by the width Woff relative to the width W of the vibration portion 120, that is, Woff / W. The offset ratio in the X-axis direction is, for example, about 0.2.

[0046] The holding portion 140 is formed in a rectangular frame shape so as to surround the outer side of the vibration portion 120 along the XY plane. In addition, the holding portion 140 is not limited to a frame shape as long as it is provided to surround at least a portion of the periphery of the vibration portion 120. For example, the holding portion 140 is provided around the vibration portion 120 to hold the vibration portion 120 and to an extent that it can be joined to the upper cover 30 and the lower cover 20.

[0047] In this embodiment, the holding portion 140 includes integrally formed prism-shaped frames 140a to 140d. Figure 3As shown, the frames 140a and 140b are opposite to the short sides of the vibration part 120, and the long sides are arranged in parallel with the X-axis direction. In addition, the frames 140c and 140d are opposite to the long sides of the vibration part 120, and the long sides are arranged in parallel with the Y-axis direction, and the two ends of the frames 140c and 140d are connected to the two ends of the frames 140a and 140b respectively. The frame 140b is connected to the support unit 110 near its center.

[0048] The support unit 110 is provided inside the holding portion 140 and in a space between the short side of the vibration portion 120 and the frame 140b. The support unit 110 connects the short side of the vibration portion 120 and the frame 140b of the holding portion 140. Although not shown in the figure, the metal layer E1 described above is formed on the surface of the support unit 110 from the vibration portion 120 to the frame 140b.

[0049] The support unit 110 of this embodiment includes a node generation part 130. The node generation part 130 is connected to the short side of the vibration part 120 through the arm 111a, and is connected to the frame 140b of the holding part 140 through the arm 111b. In addition, the node generation part 130 has a side 131 opposite to the short side of the vibration part 120, and is connected to the arm 111a at this side 131.

[0050] The node generating portion 130 has a shape in which the width along the X-axis direction becomes narrower as it moves from the arm 111a toward the arm 111b. In addition, the node generating portion 130 has a shape that is line-symmetrical with respect to the perpendicular bisector of the side 131. The node generating portion 130 has a portion with the largest width along the X-axis direction on the side of the arm 111a relative to the center in the Y-axis direction. In the present embodiment, the width of the node generating portion 130 along the X-axis direction is the largest on the side 131, and gradually narrows as it moves from the arm 111a toward the arm 111b, and is the narrowest at the connection portion between the vertex of the node generating portion 130 and the arm 111b. In addition, the width of the node generating portion 130 along the X-axis direction does not need to be narrowed continuously, for example, even if it is narrowed in stages or a part has a widened portion, it is sufficient as long as the whole gradually narrows. In addition, the edges of the node generating portion 130 are not limited to smooth shapes, and may also have concave and convex shapes.

[0051] In the present embodiment, the node generating portion 130 is, for example, in the shape of a semicircle with a radius of about 30 μm and a side 131 as a diameter. In this case, the center of the circle forming the arc of the node generating portion 130 is located at the center of the side 131. In addition, the center of the circle forming the arc of the node generating portion 130 may also be located at the center of the arm 111b. In addition, the side 131 is not limited to a straight line shape, but may also be an arc shape. In this case, the arm 111a is connected to the vertex of the side 131. And, in this case, the center of the circle forming the arc of the side 131 may be located on the arm 111a side or on the arm 111b side. It is preferred that the length of the side 131 is larger than the width of the arm 111a along the X-axis direction and smaller than the short side of the vibration portion 120.

[0052] The node generating portion 130 of the support unit 110 in the present embodiment is a structure in which the width along the X-axis direction gradually narrows from the arm 111a toward the arm 111b. Therefore, even when the propagation state of the vibration propagated from the vibration portion 120 changes, a portion with small displacement is formed in the node generating portion 130 adjacent to the portion with large displacement caused by the vibration. Thus, the node generating portion 130 can adjust the displacement portion for the vibration leaked from the vibration portion 120 and form a node of vibration on the node generating portion 130. The node generating portion 130 is connected to the arm 111a at the formed node, thereby suppressing the propagation of vibration from the vibration portion 120 to the holding portion 140. As a result, the anchor loss of the resonator 10 can be reduced and the Q value can be improved.

[0053] Next, refer to Figure 4-5 The stacked structure of the resonator 10 according to one embodiment of the present invention will be described. Figure 4 is a schematic representation of the Figure 3 The cross-sectional view of the structure of the cross section taken along line IV-IV is shown. Figure 5 is a schematic representation of the Figure 3 The cross-sectional view of the structure of the cross section taken along the line VV is shown.

[0054] The vibration part 120, the holding part 140, and the support unit 110 in the resonator 10 are integrally formed by the same process. Figure 4 As shown, the vibration part 120 in the resonator 10 is, for example, laminated with a metal layer E2 on one main surface, i.e., the upper surface, of a silicon (Si) substrate (hereinafter referred to as "Si substrate") F2 having a thickness of about 24 μm. Moreover, a piezoelectric film F3 is laminated on the metal layer E2 to cover the metal layer E2, and a metal layer E1 is laminated on the piezoelectric film F3. In addition, a protective film 125 is laminated on the metal layer E1 to cover the metal layer E1. In addition, the Si substrate F2 of this embodiment is equivalent to an example of the "substrate" of the present invention, and the piezoelectric film F3 of this embodiment is equivalent to an example of the "piezoelectric body layer" of the present invention.

[0055] The vibration part 120 includes a piezoelectric thin film F3 disposed between the Si substrate F2 and the metal layer E1 formed on the upper surface of the Si substrate F2.

[0056] As described above, the material of the substrate of the vibration part 120 is silicon (Si), so that the mechanical strength of the vibration part 120 can be improved.

[0057] The Si substrate F2 may also be formed of a degenerate n-type silicon (Si) semiconductor. Degenerate silicon (Si) may contain phosphorus (P), arsenic (As), antimony (Sb), etc. as n-type dopants. The resistance value of the degenerate silicon (Si) used in the Si substrate F2 is, for example, less than 16 mΩ·cm, and more preferably less than 1.2 mΩ·cm.

[0058] As described above, the material of the substrate of the vibration part 120 is degenerate silicon (Si), so that the frequency-temperature characteristics of the vibration part 120 can be improved.

[0059] Furthermore, a modified layer F1 is formed on the other main surface, that is, the lower surface, of the Si substrate F2. The modified layer F1 has a thickness of about 0.5 μm and is made of, for example, silicon dioxide (SiO 2 ) is formed.

[0060] In the present embodiment, the correction layer F1 is a layer having a function of reducing the temperature coefficient of the frequency in the vibration part 120 when the correction layer is formed on the Si substrate F2, that is, the rate of change per unit temperature, at least at room temperature, compared to the case where the correction layer F1 is not formed on the Si substrate F2. When the vibration part 120 includes the correction layer F1, for example, in the resonance frequency of the stacked structure including the Si substrate F2, the metal layer E1, the piezoelectric film F3, and the correction layer F1, the change accompanying the temperature can be reduced, and the temperature characteristics of the vibration part 120 can be improved.

[0061] The metal layers E1 and E2 have a thickness of, for example, about 0.2 μm or less, and are patterned into a desired shape by etching or the like after film formation. The metal layers E1 and E2 are made of a body-centered cubic crystal structure. Specifically, the metal layer E1 is formed using Mo (molybdenum), tungsten (W), or the like.

[0062] The metal layer E1 is formed on the vibration part 120 to function as an upper electrode, for example. Also, the metal layer E1 is formed on the support unit 110 and the holding part 140 to function as a wiring for connecting the upper electrode to an AC power source provided outside the resonator 10 .

[0063] On the other hand, the metal layer E2 is formed on the vibration part 120 to function as a lower electrode. In addition, the metal layer E2 is formed on the support unit 110 and the holding part 140 to function as a wiring for connecting the lower electrode to a circuit provided outside the resonator 10.

[0064] In addition, the Si substrate F2 itself can also serve as the lower electrode, and the metal layer E2 can be omitted.

[0065] The piezoelectric film F3 is a piezoelectric film that converts an applied voltage into vibration. The piezoelectric film F3 is formed of a material having a wurtzite hexagonal crystal structure, and can be composed mainly of nitrides and oxides such as aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), gallium nitride (GaN), and indium nitride (InN). In addition, scandium aluminum nitride is a material in which a portion of the aluminum in aluminum nitride is replaced with scandium, and scandium can also be replaced with two elements such as magnesium (Mg) and niobium (Nb), magnesium (Mg), and zirconium (Zr). In addition, the piezoelectric film F3 has a thickness of, for example, 0.8 μm, but a thickness of about 0.2 μm to 2 μm can also be used.

[0066] In addition, the piezoelectric film F3 is oriented along the c-axis, that is, the thickness direction (Z-axis direction) of the Si substrate F2.

[0067] The protective film 125 may be made of, for example, silicon nitride (SiN), silicon dioxide (SiO2), or a piezoelectric film such as aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), gallium nitride (GaN), or indium nitride (InN). 2 ), aluminum oxide (Al 2 O 3 ) or the like. The thickness of the protective film 125 is, for example, about 0.2 μm. When the vibration part 120 includes the protective film 125, for example, oxidation of the metal layer E1 as the upper electrode for piezoelectric vibration can be prevented.

[0068] Each recessed portion 121 is formed by removing a portion of the piezoelectric thin film F3 , the metal layer E1 , and the protective film 125 stacked on the metal layer E2 in the vibration portion 120 by etching or the like.

[0069] In other words, the metal layer E2 is exposed at the bottom surface of each recess 121 .

[0070] As described above, when the Si substrate F2 is also used as the lower electrode and the metal layer E2 is omitted, the recesses 121 are formed by removing a portion of the piezoelectric film F3, the metal layer E1, and the protective film 125 stacked on the Si substrate F2 by etching or the like. In other words, each recess 121 exposes the upper surface of the Si substrate F2 at its bottom surface.

[0071] The vibration part 120 has a vibration region corresponding to the metal layer E1 as an upper electrode. Figure 4 As shown, in the vibration region, the piezoelectric film F3 expands and contracts along the in-plane direction of the XY plane, that is, the Y-axis direction, according to the electric field applied to the piezoelectric film F3 through the metal layers E1 and E2. Specifically, since the piezoelectric film F3 is oriented along the thickness direction, if a predetermined electric field is applied to the metal layers E1 and E2, a predetermined potential difference is formed between the metal layers E1 and E2, and the piezoelectric film F3 vibrates in the XY plane according to the potential difference. That is, in the vibration region of the vibration part 120, in the longitudinal direction (Y-axis direction), a vibration of a stretching mode that repeats the state of the vibration part 120 extending and the state of the vibration part 120 contracting is generated.

[0072] The vibration part 120 vibrates mainly by contour vibration. On the other hand, due to the fact that one main surface ( Figure 4 The metal layer E1 and the metal layer E2 are formed on the upper surface of the structure (in the thickness direction (Z-axis direction)), and the structure is asymmetric. Therefore, bending in the thickness direction is easily generated due to contour vibration.

[0073] In view of this, the vibration part 120 of this embodiment has the recessed part 121 formed by removing the piezoelectric film F3, the metal layer E1, and the protective film 125 from one main surface of the Si substrate F2, so that the displacement shape in the thickness direction generated in the vibration part 120 can be adjusted. Therefore, the vibration leakage to the holding part 140 can be suppressed, and the restrictiveness can be improved.

[0074] In addition, if Figure 3 As shown, when looking down on one main surface of the Si substrate F2 (hereinafter referred to as "looking down"), the recess 121 is formed at a position deviating from the center line CL2 in the X-axis direction orthogonal to the Y-axis direction in the Si substrate F2. Thus, the displacement shape in the thickness direction generated in the vibration part 120 can be easily adjusted.

[0075] In this specification, “contour vibration” is used as a general term for extension vibration, stretching vibration of dimensional change in the width direction (X-axis direction), and stretching vibration of stretching in the length direction (Y-axis direction).

[0076] Next, refer to Figure 6 and Figure 7 The displacement of the support unit caused by the vibration of the vibrating part is described. Figure 6 and Figure 7 In the embodiment, the vibration unit 120 does not include Figure 4 and Figure 5The metal layer E2 shown includes a correction layer F1 with a thickness of 0.5 μm, a Si substrate F2 with a thickness of 24 μm, a piezoelectric film F3 with a thickness of 0.8 μm, a metal layer E1 with a thickness of 0.2 μm, and a protective film 125 with a thickness of 0.2 μm. Figure 6 : is a graph showing an example of the relationship between the displacement in the longitudinal direction (Y-axis direction) of the support unit 110 and the aspect ratio AR of the vibration part 120 . Figure 7 : is a graph showing an example of the relationship between the displacement in the thickness direction (Z-axis direction) of the support unit 110 and the aspect ratio AR of the vibration part 120. Figure 6 In FIG. 1 , the horizontal axis is the aspect ratio AR (L / W) of the vibration part 120 . The vertical axis is the displacement of the joint portion of the support unit 110 with the vibration part 120 in the length direction (hereinafter, also referred to as “displacement in the length direction”). Figure 7 In FIG. 1 , the horizontal axis is the aspect ratio AR (L / W) of the vibration part 120 . The vertical axis is the displacement of the joint portion of the support unit 110 with the vibration part 120 in the thickness direction (hereinafter, also referred to as “displacement in the thickness direction”). Figure 6 and Figure 7 In FIG. 1 , for comparison, black circles are used to indicate the respective displacement amounts when the vibration portion has no concave portion.

[0077] like Figure 6 As shown, no significant difference was found between the vibration part 120 having the recess 121 and the vibration part without the recess in the longitudinal direction displacement of the support unit 110. For example, in either case, the longitudinal displacement of the support unit 110 was zero around the aspect ratio of 1.425.

[0078] On the other hand, Figure 7 As shown, the displacement amount in the thickness direction of the support unit 110 is zero around the aspect ratio of 1.425 in the case of the vibration part 120 having the recess 121, whereas it is not zero around the aspect ratio of 1.425 in the case of the vibration part without the recess.

[0079] In fact, in the vibration part without the recess, the displacement amount of the support unit 110A' in the thickness direction shows a negative value at the connection part (arm 111b') with the holding part, and the vibration in the thickness direction leaks from the vibration part to the holding part. In contrast, in the vibration part 120 having the recess 121, the displacement amount of the support unit 110A in the thickness direction shows a value of substantially zero around the connection part (arm 111b) with the holding part, and it can be seen that the vibration in the thickness direction is suppressed from leaking from the vibration part 120 to the holding part 140.

[0080] Next, refer to Figure 8 and Fig. 9The displacement in the thickness direction of the support unit caused by the vibration of the vibrating part is described using other indicators. Figure 8 and Fig. 9 In the embodiment, the vibration unit 120 and the above Figure 6 and Figure 7 The vibration unit 120 in FIG. 1 is described in the same manner. Figure 8 : is a graph showing an example of the relationship between the magnitude of displacement in the thickness direction (Z-axis direction) of the support unit 110 and the aspect ratio AR of the vibration part 120 . Fig. 9 : is a graph showing an example of the relationship between the evaluation index in the thickness direction (Z-axis direction) of the support unit 110 and the aspect ratio AR of the vibration part 120. Figure 8 In FIG. 1 , the horizontal axis is the aspect ratio AR (L / W) of the vibration part 120 . The vertical axis is the cross-sectional area integral value of the displacement magnitude in the thickness direction of the support unit 110 . Fig. 9 In FIG. 1 , the horizontal axis is the aspect ratio AR (L / W) of the vibration part 120 . The vertical axis is the performance index FOM1 (Figure Of Merit) which represents the cross-sectional area integral value of the displacement in the thickness direction of the support unit 110 relative to the maximum displacement in the thickness direction of the vibration part 120 . Figure 8 and Fig. 9 In FIG. 1 , for comparison, the cross-sectional area integral value and the performance index FOM1 when the vibration portion has no recessed portion are indicated by black circles.

[0081] like Figure 8 As shown, both the vibration part 120 having the concave portion 121 and the vibration part without the concave portion have the minimum value around the aspect ratio of 1.425. The vibration part 120 having the concave portion 121 has a smaller value than the vibration part without the concave portion at the aspect ratio of 1.425.

[0082] like Fig. 9 As shown, at an aspect ratio of 1.425, the performance index FOM1 of the vibration part without the recessed portion is 2.4, while the performance index FOM1 of the vibration part 120 having the recessed portion 121 is 40.6. Thus, it can be seen that the performance index FOM1 of the vibration part 120 having the recessed portion 121 can be improved by about 17 times compared with the vibration part without the recessed portion.

[0083] In this embodiment, the vibration part 120 has four recesses 121, and each recess 121 has a square shape when viewed from above, but the present invention is not limited thereto. For example, the vibration part 120 may have one, two, three, or more than five recesses 121, and the shape of the recess 121 when viewed from above may be other than a square.

[0084] (First Modification)

[0085] Fig.10 Yes means Figure 3 1 is a perspective view of a first modified example of the structure of the vibrating portion 120 and its surroundings. Figure 3 The same structures around the vibrating part 120 are denoted by the same reference numerals, and the description thereof is omitted as appropriate. In addition, the same functions and effects caused by the same structures are not described in order.

[0086] like Fig.10 As shown, the vibration part 120 is connected by two support units 110A and 110B. The support unit 110A includes a node generation unit 130A connecting the short side of the vibration part 120 on the negative side of the Y axis and the frame 140b of the holding part 140. The support unit 110B includes a node generation unit 130B connecting the short side of the vibration part 120 on the positive side of the Y axis and the frame 140a of the holding part 140. The node generation unit 130A and the node generation unit 130B are connected to Figure 2 and Figure 3 The node generation unit 130 shown is the same.

[0087] The vibration part 120 has two recesses 121A, each of which has a semicircular shape when viewed from above. In addition, each recess 121A is removed by etching or the like in the same manner as the recess 121. Figure 4 The piezoelectric film F3, the metal layer E1, and a portion of the protective film 125 are shown, and the metal layer E2 is exposed on the bottom surface of the recessed portion 121A.

[0088] In addition, the two recesses 121A are respectively arranged at positions symmetrical with respect to the center line CL1 in the Y-axis direction of the vibration part 120. That is, the recess 121A on the negative side of the Y-axis and the recess 121A on the positive side of the Y-axis are respectively formed at positions symmetrical with respect to the center line CL1. Thus, the displacement shape in the thickness direction generated in the vibration part 120 can be easily adjusted.

[0089] (Second Modification)

[0090] Fig.11 Yes means Figure 3 120 shown in FIG. 1 is a perspective view of a second modified example of the structure of the vibrating portion 120 and its surroundings. Figure 3 The same structures around the vibrating portion 120 are denoted by the same reference numerals, and the description thereof is omitted as appropriate. In addition, the same functions and effects caused by the same structures are not described in order.

[0091] like Fig.11 As shown, the vibration part 120 has two recesses 121B, and each recess 121B has a strip shape extending in the Y-axis direction when viewed from above. In addition, each recess 121B is removed by etching or the like in the same manner as the recess 121. Figure 4 The piezoelectric film F3, the metal layer E1, and a portion of the protective film 125 are shown, and the metal layer E2 is exposed on the bottom surface of the recessed portion 121B.

[0092] The two recesses 121B are arranged at positions symmetrical about the center line CL2 in the X-axis direction of the vibration unit 120. That is, the recess 121B on the negative X-axis side and the recess 121B on the positive X-axis side are formed at positions symmetrical about the center line CL2.

[0093] In addition, Fig.10 and Fig.11 In the modification shown, one concave portion and the other concave portion are formed at positions symmetrical with respect to one of the center line CL1 in the Y-axis direction and the center line CL2 in the X-axis direction of the vibration portion 120, but the present invention is not limited thereto. Figure 3 As shown, one concave portion and the other concave portion may be formed at positions symmetrical with respect to both the center line CL1 in the Y-axis direction and the center line CL2 in the X-axis direction of the vibration portion 120 .

[0094] The above is an explanation of an exemplary embodiment of the present invention. The vibration part of the resonator of one embodiment of the present invention has a recessed portion formed by removing a piezoelectric film from one main surface of a Si substrate. Thus, the displacement shape in the thickness direction generated in the vibration part can be adjusted. Therefore, the vibration leakage to the holding part can be suppressed, and the restrictiveness can be improved.

[0095] In the above-mentioned resonator, the recessed portion exposes one main surface. This makes it possible to easily realize a vibrating portion that suppresses vibration leakage to the holding portion.

[0096] In the above-mentioned resonator, the metal layer is exposed in the recessed portion. Thus, it is possible to easily realize a vibrating portion that suppresses vibration leakage to the holding portion.

[0097] In the resonator, the recess is formed at a position offset from the center line of the Si substrate in the X-axis direction orthogonal to the Y-axis direction when looking down at one main surface of the Si substrate. This makes it easy to adjust the shape of the displacement in the thickness direction generated in the vibrating portion.

[0098] In the resonator, one of the plurality of recesses and the other recesses are formed at positions symmetrical to the center line in the Y-axis direction and / or the X-axis direction of the Si substrate, thereby making it easy to adjust the shape of the displacement in the thickness direction generated in the vibration part.

[0099] In the above resonator, the support unit is connected to the end of the vibrating portion in the longitudinal direction. This makes it possible to easily connect the vibrating portion and the holding portion that expand and contract in the longitudinal direction.

[0100] In the above resonator, the material of the substrate is silicon (Si), thereby increasing the mechanical strength of the vibration part.

[0101] In the above resonator, the material of the substrate is degenerate silicon (Si), thereby improving the frequency-temperature characteristics of the vibration part.

[0102] In addition, the resonator described above further includes a protective film formed so as to cover the metal layer, thereby, for example, preventing the metal layer as an upper electrode for piezoelectric vibration from being oxidized.

[0103] In the resonator, the vibration part further includes a correction layer formed on the other main surface of the Si substrate. Thus, for example, the change in the resonance frequency of the stacked structure including the Si substrate, the metal layer, the piezoelectric film, and the correction layer due to temperature can be reduced, and the temperature characteristics of the vibration part can be improved.

[0104] A resonance device according to one embodiment of the present invention includes the above-described resonator, an upper cover, and a lower cover. Thus, a resonance device with improved restrictiveness can be easily realized.

[0105] In addition, the above-described embodiments are for easy understanding of the content of the present invention, and are not for limiting the interpretation of the content of the present invention. The present invention can be changed / improved without departing from its purport, and its equivalents are also included in the present invention. That is, as long as the structure obtained by appropriately applying design changes to the embodiments and / or variations by those skilled in the art has the features of the present invention, it is also included in the scope of the present invention. For example, the various elements and their configurations, materials, conditions, shapes, sizes, etc. possessed by the embodiments and / or variations are not limited to the contents shown in the examples, but can be appropriately changed. In addition, the embodiments and variations are illustrative, and of course, partial replacement or combination of the structures shown in different embodiments and / or variations can be performed, and these structures are included in the scope of the present invention as long as they include the features of the present invention.

[0106] Description of Reference Numerals

[0107] 1…resonance device; 10…resonator; 20…lower cover; 21…recess; 22…bottom plate; 23…side wall; 30…upper cover; 31…recess; 33…side wall; 110…support unit; 110A…support unit; 110A′…support unit; 110B…support unit; 111a…arm; 111b…arm; 111b′…arm; 120…vibration unit; 121…recess; 121A…recess; 121B…recess; 125…protective film; 130…node generating unit; 130A…node generating unit; 130B…node generating unit; 131…edge; 140…holding unit; 140a…frame; 140b…frame; 140c…frame; 140d…frame; AR…aspect ratio; CL1…center line; CL2…center line; E1…metal layer; E2…metal layer; F1…correction layer; F2…Si substrate; F3…piezoelectric film; FOM1…performance index; L…length; Loff…length; W…width; Woff…width.

Claims

1. A resonator, comprising: A vibration unit including a substrate, a first electrode formed on one main surface of the substrate, and a piezoelectric layer disposed between the substrate and the first electrode, wherein the vibration unit vibrates mainly by contour vibration; a holding portion formed to surround at least a portion of the vibration portion; and a supporting part connecting the vibrating part and the holding part, The vibration part has a recessed portion penetrating through the piezoelectric layer on the one main surface. The recessed portion exposes the one main surface.

2. The resonator according to claim 1, wherein The vibration part vibrates mainly by stretching vibration along the first direction. The recessed portion is formed at a position offset from a center line of the substrate in a second direction orthogonal to the first direction when the one main surface is viewed in plan.

3. The resonator according to claim 2, wherein: The vibration part includes a plurality of the concave parts. One of the plurality of recesses and the other recesses are formed at positions symmetrical with respect to a center line of the substrate in the first direction and / or the second direction, respectively.

4. The resonator according to claim 2 or 3, wherein: The support portion is connected to an end portion of the vibrating portion in the first direction.

5. The resonator according to any one of claims 1 to 4, wherein: The material of the above-mentioned substrate is silicon.

6. The resonator according to any one of claims 1 to 4, wherein: The material of the substrate is degenerate silicon.

7. The resonator according to any one of claims 1 to 6, wherein: The vibration part further includes a protection layer, and the protection layer is formed to cover the first electrode.

8. The resonator according to any one of claims 1 to 7, wherein: The vibration portion further includes a correction layer formed on the other main surface of the substrate.

9. A resonator, comprising: A vibration unit including a substrate, a first electrode formed on one main surface of the substrate, and a piezoelectric layer disposed between the substrate and the first electrode, wherein the vibration unit vibrates mainly by contour vibration; a holding portion formed to surround at least a portion of the vibration portion; and a supporting part connecting the vibrating part and the holding part, The vibration part has a recessed portion penetrating through the piezoelectric layer on the one main surface. The vibration part further includes a second electrode, and the second electrode is arranged between the substrate and the piezoelectric layer. The recessed portion exposes the second electrode.

10. The resonator according to claim 9, wherein The vibration part vibrates mainly by stretching vibration along the first direction. The recessed portion is formed at a position offset from a center line of the substrate in a second direction orthogonal to the first direction when the one main surface is viewed in plan.

11. The resonator according to claim 10, wherein The vibration part includes a plurality of the concave parts. One of the plurality of recesses and the other recesses are formed at positions symmetrical with respect to a center line of the substrate in the first direction and / or the second direction, respectively.

12. The resonator according to claim 10 or 11, wherein: The support portion is connected to an end portion of the vibrating portion in the first direction.

13. The resonator according to any one of claims 9 to 12, wherein: The material of the above-mentioned substrate is silicon.

14. The resonator according to any one of claims 9 to 12, wherein: The material of the substrate is degenerate silicon.

15. The resonator according to any one of claims 9 to 14, wherein: The vibration part further includes a protection layer, and the protection layer is formed to cover the first electrode.

16. The resonator according to any one of claims 9 to 15, wherein: The vibration portion further includes a correction layer formed on the other main surface of the substrate.

17. A resonance device comprising: The resonator according to any one of claims 1 to 16; and Cover body.

Images