Resonator device and method of manufacturing the same

Abstract

A resonator device (1) includes: a first substrate (50) including a first silicon substrate (P10) and a resonator (10); a second substrate (30) facing the first substrate (50); and a frame-shaped joining portion (H) joining the first substrate (50) and the second substrate (30) to seal a vibration space of the resonator (10), the resonator (10) including: a single-crystal silicon film (F2); and a first silicon oxide film (F21) sandwiched by the single-crystal silicon film (F2) and the first silicon substrate (P10), the first silicon oxide film (F21) being divided by a first barrier member (B11) formed in a frame shape surrounding a vibration portion (110) of the resonator (10) when the first substrate (50) is viewed in plan, the resonator (10) of the first substrate (50) being provided with a through-hole penetrating the single-crystal silicon film (F2) and the first silicon oxide film (F21) in the first substrate (50) and the second substrate (30), the first barrier member (B11) being provided inside the through-hole, and the helium permeability of the first barrier member (B11) being lower than that of the first silicon oxide film (F21).

Description

Technical Field

[0001] This invention relates to a resonant device and its manufacturing method. Background Technology

[0002] Resonant devices are used in various electronic devices such as mobile communication terminals, communication base stations, and home appliances, and in various applications such as timing devices, sensors, and oscillators. As one type of such resonant device, there is a so-called MEMS (Micro-Electro-Mechanical Systems) resonant device, which includes: a lower cover, an upper cover forming a vibration space between the upper cover and the lower cover, and a resonator having a vibrating arm that is held to vibrate in the vibration space.

[0003] Patent Document 1 discloses a resonant device comprising: a first substrate including a resonator, a second substrate, and a joint for joining the first substrate and the second substrate. The first substrate and the second substrate each have a silicon oxide film on their opposing surfaces. A frame-shaped through hole surrounding the vibrating portion of the resonator is formed in each silicon oxide film, and the interior of each through hole is filled with metal constituting the joint.

[0004] Patent document 2 discloses a MEMS comprising: a silicon handle wafer, a bottom oxide disposed on the silicon handle wafer, a silicon device layer disposed on the bottom oxide, an intermediate oxide disposed on the silicon device layer, a capping silicon disposed on the intermediate oxide, a first barrier layer that blocks hydrogen and helium with the bottom oxide as the invasion path, and a second barrier layer that blocks hydrogen and helium with the intermediate oxide as the invasion path. The first barrier layer penetrates the bottom oxide, and the second barrier layer penetrates the intermediate oxide. The first and second barrier layers are formed to form a MEMS cavity surrounding the silicon device layer.

[0005] Patent Document 1: International Publication No. 2020 / 194810

[0006] Patent Document 2: US Patent No. 10800650

[0007] According to the invention described in Patent Document 1, the silicon oxide film disposed on the opposing surfaces of the first and second substrates is interrupted by a metal forming the junction, thereby suppressing the intrusion of helium gas through the silicon oxide film. Therefore, the degradation of vibrational characteristics such as the Q value caused by the decrease in vacuum level in the resonator's vibration space is suppressed.

[0008] However, when silicon oxide films are present not only on the opposing surfaces of the first and second substrates, but also inside them, the resonant device described in Patent Document 1 cannot adequately suppress the intrusion of helium gas.

[0009] In the invention described in Patent Document 2, for example, a silicon device layer is disposed on the bottom oxide and the first barrier layer by bonding or growth.

[0010] In the case of a silicon device layer being bonded together, during the stage of forming a first barrier layer on the bottom oxide, the surfaces of the bottom oxide and the first barrier layer are planarized by grinding or the like. However, due to the difference in hardness between the bottom oxide and the first barrier layer, there are cases where the surface of the first barrier layer becomes concave or convex relative to the surface of the bottom oxide. In this case, gaps may be generated between the bottom oxide and the silicon device layer or between the first barrier layer and the silicon device layer, creating a problem where these gaps become pathways for helium intrusion.

[0011] Furthermore, when a silicon device layer is grown and formed from polycrystalline or amorphous silicon, there is a risk that the frequency-temperature characteristics may be worse than those of a silicon device layer formed from monocrystalline silicon. Summary of the Invention

[0012] The present invention was made in view of the following situation, and the object of the present invention is to provide a resonant device and a method thereof that can suppress the reduction of vacuum and have good frequency-temperature characteristics.

[0013] One aspect of the resonant device according to the present invention includes: a first substrate including a first silicon substrate and a resonator; a second substrate facing the first substrate; and a frame-shaped joint for joining the first substrate and the second substrate to seal the vibration space of the resonator. The resonator has: a monocrystalline silicon film; and a first silicon oxide film sandwiched between the monocrystalline silicon film and the first silicon substrate. The first silicon oxide film is divided by a frame-shaped first barrier member that surrounds the vibration portion of the resonator when viewed from above the first substrate. A through-hole penetrating the monocrystalline silicon film and the first silicon oxide film is provided on the resonator of the first substrate in the first substrate and the second substrate. The first barrier member is provided inside the through-hole. The helium permeability of the first barrier member is lower than that of the first silicon oxide film.

[0014] Another aspect of the present invention relates to a resonant device comprising: a first substrate including a resonator; a second substrate facing the first substrate; and a frame-shaped joint that joins the first substrate and the second substrate to seal the vibration space of the resonator. The second substrate has: a silicon substrate; a through electrode penetrating the silicon substrate; an internal terminal disposed on the first substrate side of the through electrode; an external terminal disposed on the side of the through electrode opposite to the first substrate; and a silicon oxide film continuously disposed across a region between the silicon substrate and the through electrode, an inner region between the silicon substrate and the internal terminal, and an outer region between the silicon substrate and the external terminal. In the inner region, the silicon oxide film is interrupted by a frame-shaped barrier member surrounding the through electrode when viewed from above. The barrier member has lower helium permeability than the silicon oxide film.

[0015] Another aspect of the present invention relates to a method for manufacturing a resonant device, comprising the following steps: preparing a first substrate including a silicon substrate and a resonator; preparing a second substrate; and joining the first substrate and the second substrate to seal the vibration space of the resonator, the resonator having: a monocrystalline silicon film; and a silicon oxide film sandwiched between the monocrystalline silicon film and the silicon substrate, the silicon oxide film being divided by a barrier member formed in the shape of a frame surrounding the vibration portion of the resonator when viewed from above the first substrate, a through hole penetrating the monocrystalline silicon film and the silicon oxide film being provided on the resonator of the first substrate and the second substrate, the barrier member being provided inside the through hole, the barrier member having a lower helium permeability than the first silicon oxide film.

[0016] According to the present invention, a resonant device capable of suppressing the reduction of vacuum and having good frequency-temperature characteristics, and a method thereof for manufacturing the same, can be provided. Attached Figure Description

[0017] Figure 1 This is a perspective view that schematically shows the appearance of the resonant device according to the first embodiment.

[0018] Figure 2 This is an exploded perspective view that schematically shows the structure of the resonant device according to the first embodiment.

[0019] Figure 3 This is a top view that schematically shows the structure of the resonator according to the first embodiment.

[0020] Figure 4 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the first embodiment.

[0021] Figure 5 This is a flowchart that schematically illustrates the manufacturing method of the MEMS substrate according to the first embodiment.

[0022] Figure 6 This diagram schematically illustrates the process of setting up the first barrier component.

[0023] Figure 7 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the second embodiment.

[0024] Figure 8 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the third embodiment.

[0025] Figure 9 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the fourth embodiment.

[0026] Figure 10 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the fifth embodiment. Detailed Implementation

[0027] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The drawings in this embodiment are illustrative, and the dimensions and shapes of the parts are schematic. They should not be interpreted as limiting the technical scope of the present invention to this embodiment.

[0028] <First Embodiment>

[0029] First, refer to Figure 1 and Figure 2 The structure of the resonant device 1 according to the first embodiment of the present invention will be described. Figure 1 This is a perspective view that schematically shows the appearance of the resonant device according to this embodiment. Figure 2 This is an exploded perspective view that schematically illustrates the structure of the resonant device according to this embodiment.

[0030] The following describes the various structures of the resonant device 1. In the various figures, an orthogonal coordinate system consisting of the X-axis, Y-axis, and Z-axis is sometimes provided for convenience, to clarify the relationships between the figures and to aid in understanding the positional relationships between the components. The directions parallel to the X-axis, Y-axis, and Z-axis are respectively referred to as the X-axis direction, Y-axis direction, and Z-axis direction. The plane defined by the X-axis and Y-axis is called the XY plane; the YZ plane and ZX plane are defined in the same way.

[0031] The resonant device 1 includes: a resonator 10; and a lower cover 20 and an upper cover 30 arranged opposite each other with respect to the resonator 10. The lower cover 20, the resonator 10, and the upper cover 30 are stacked sequentially along the Z-axis. The resonator 10 and the lower cover 20 are joined to form a MEMS substrate 50. The upper cover 30 is joined to the resonator 10 side of the MEMS substrate 50. In other words, the upper cover 30 is joined to the lower cover 20 via the resonator 10. The lower cover 20 and the upper cover 30 constitute a package structure having a vibration space inside. The MEMS substrate 50 corresponds to an example of the "first substrate" according to the present invention, and the upper cover 30 corresponds to an example of the "second substrate" according to the present invention.

[0032] The resonator 10 is a MEMS resonant element manufactured using MEMS technology. The frequency band of the resonator 10 is, for example, above 1 kHz and below 1 MHz. The resonator 10 includes a resonating part 110, a holding part 140, and a holding arm 150.

[0033] The vibrating part 110 is maintained in a vibration space provided between the lower cover 20 and the upper cover 30, enabling it to vibrate. When not vibrating (without applied voltage), the vibrating part 110 extends along the XY plane, and when vibrating (with applied voltage), it buckles along the Z-axis. That is, the vibrating part 110 vibrates using an out-of-plane buckling vibration mode. Additionally, when not vibrating, the vibrating part 110 can also deflect along the Z-axis due to its own weight.

[0034] For example, when viewed from above in the XY plane (hereinafter referred to as "top view"), the retaining part 140 is arranged in a frame shape and surrounds the vibrating part 110. The retaining part 140, together with the lower cover 20 and the upper cover 30, forms a vibration space of the encapsulation structure.

[0035] When viewed from above, the retaining arm 150 is positioned between the vibrating part 110 and the retaining part 140. The retaining arm 150 connects the vibrating part 110 and the retaining part 140.

[0036] The lower cover 20 has: a rectangular flat base plate 22 having a main surface extending along the XY plane; and a side wall 23 extending from the periphery of the base plate 22 toward the upper cover 30. The side wall 23 engages with the holding portion 140 of the resonator 10. On the lower cover 20, on the side facing the vibrating portion 110 of the resonator 10, a cavity 21 surrounded by the base plate 22 and the side wall 23 is formed. The cavity 21 is an upward-opening cuboid opening.

[0037] The upper cover 30 has: a rectangular flat base plate 32 with a main surface extending along the XY plane; and a side wall 33 extending from the periphery of the base plate 32 toward the lower cover 20. The side wall 33 engages with the holding portion 140 of the resonator 10. On the upper cover 30, a cavity 31 surrounded by the base plate 32 and the side wall 33 is formed on the side facing the vibrating portion 110 of the resonator 10. The cavity 31 is a downwardly opening cuboid. The cavity 21 and the cavity 31 face each other across the vibrating portion 110 of the resonator 10, forming a vibration space of the encapsulation structure.

[0038] Next, refer to Figure 3 The structure of the resonator 10 (vibrating part 110, holding part 140 and holding arm 150) when viewed from the top cover 30 side will be described in more detail. Figure 3 This is a top view that schematically illustrates the structure of the resonator according to this embodiment. Here, the dimension along the Y-axis is referred to as "length", and the dimension along the X-axis is referred to as "width".

[0039] The resonator 10 is formed, for example, in a planar symmetrical manner with respect to an imaginary plane P parallel to the YZ plane. That is, the vibrating part 110, the holding part 140, and the holding arm 150 are each formed approximately in a planar symmetrical manner with respect to the imaginary plane P.

[0040] Viewed from the top cover 30 side, the vibrating part 110 is disposed inside the holding part 140. A space is formed between the vibrating part 110 and the holding part 140 at a predetermined interval. The vibrating part 110 has an excitation part 120 composed of four vibrating arms 121A, 121B, 121C, and 121D, and a base 130 connected to the excitation part 120. In addition, the number of vibrating arms is not limited to four, and can be set to any number of more than one. In this embodiment, the excitation part 120 and the base 130 are integrally formed.

[0041] Vibrating arms 121A to 121D extend along the Y-axis and are arranged sequentially at predetermined intervals along the X-axis. Each vibrating arm 121A to 121D has a fixed end connected to the base 130 and an open end furthest from the base 130. Each vibrating arm 121A to 121D has: end portions 122A to 122D, located on the side of the open end where the displacement in the vibrating section 110 is relatively large; and arm portions 123A to 123D, connecting the base 130 to the end portions 122A to 122D. An imaginary plane P is located between vibrating arms 121B and 121C.

[0042] Of the four vibrating arms 121A to 121D, vibrating arms 121A and 121D are outer vibrating arms positioned on the outer side in the X-axis direction, while vibrating arms 121B and 121C are inner vibrating arms positioned on the inner side in the X-axis direction. Inner vibrating arms 121B and 121C are symmetrically configured with respect to the imaginary plane P, as are outer vibrating arms 121A and 121D.

[0043] Each of the end portions 122A to 122D has a metal film 125A to 125D on the surface of the upper cover 30 side. The metal films 125A to 125D function as mass-increasing films, which increase the mass per unit length (hereinafter referred to as "mass") of each of the end portions 122A to 122D compared to the mass of each of the arm portions 123A to 123D. By increasing the mass of the end portions compared to the mass of the arm portions, the vibrating part 110 can be miniaturized and the amplitude can be increased. In addition, the metal films 125A to 125D can also be used as so-called frequency-adjusting films, which adjust the resonant frequency by cutting off a portion of them.

[0044] The distal end 122A protrudes equally from the arm 123A in both the positive and negative directions along the X-axis. Therefore, the width of the distal end 122A is greater than the width of the arm 123A. The same applies to the distal ends 122B to 122D and the arms 123B to 123D. This allows for a further increase in the weight of each of the distal ends 122A to 122D. If the weight of each of the distal ends 122A to 122D is greater than the weight of each of the arms 123A to 123D, then the width of each of the distal ends 122A to 122D can be less than or equal to the width of each of the arms 123A to 123D.

[0045] Each of the end portions 122A to 122D is a generally rectangular shape with rounded corners (e.g., a so-called R-shape). Each of the arm portions 123A to 123D is a generally rectangular shape with an R-shape near the root portion connecting to the base 130 and near the connection portion connecting to each of the end portions 122A to 122D. However, the shapes of the end portions 122A to 122D and the arm portions 123A to 123D are not limited to the above. For example, the shapes of the end portions 122A to 122D can also be trapezoidal or L-shaped. Furthermore, the shapes of the arm portions 123A to 123D can also be trapezoidal, or they can be formed with slits, etc.

[0046] Vibrating arms 121A to 121D are roughly the same in shape and size. The length of each vibrating arm 121A to 121D is, for example, approximately 450 μm. For example, the length of each arm portion 123A to 123D is approximately 300 μm, and the width is approximately 50 μm. For example, the length of each end portion 122A to 122D is approximately 150 μm, and the width is approximately 70 μm.

[0047] The base 130 has a front end portion 131A, a rear end portion 131B, a left end portion 131C, and a right end portion 131D. The front end portion 131A, rear end portion 131B, left end portion 131C, and right end portion 131D are portions of the outer edge of the base 130. The front end portion 131A is the end portion extending along the X-axis on the side of the vibrating arms 121A to 121D. The rear end portion 131B is the end portion extending along the X-axis on the side opposite to the vibrating arms 121A to 121D. When viewed from the vibrating arm 121D, the left end portion 131C is the end portion extending along the Y-axis on the side of the vibrating arm 121A. When viewed from the vibrating arm 121A, the right end portion 131D is the end portion extending along the Y-axis on the side of the vibrating arm 121D. The vibrating arms 121A to 121D are connected to the front end portion 131A.

[0048] The base 130 is approximately rectangular with the front end 131A and rear end 131B as its long sides and the left end 131C and right end 131D as its short sides. An imaginary plane P is defined along the perpendicular bisectors of the front end 131A and rear end 131B. The base 130 is not limited to the above-described configuration if it is approximately planar symmetrical with respect to the imaginary plane P; for example, it could be a trapezoidal shape where one of the front end 131A or rear end 131B is longer than the other. Furthermore, at least one of the front end 131A, rear end 131B, left end 131C, and right end 131D could be bent or folded.

[0049] As an example, the maximum distance in the Y-axis direction between the front end portion 131A and the rear end portion 131B, i.e., the base length, is approximately 35 μm. Furthermore, as an example, the maximum distance in the X-axis direction between the left end portion 131C and the right end portion 131D, i.e., the base width, is approximately 265 μm. Additionally, in... Figure 3 In the structural example shown, the base length is equivalent to the length of the left end 131C or the right end 131D, and the base width is equivalent to the width of the front end 131A or the rear end 131B.

[0050] The retaining part 140 is used to retain the vibrating part 110 in the vibration space formed by the lower cover 20 and the upper cover 30, for example, by surrounding the vibrating part 110 in a frame shape. Figure 3As shown, when viewed from the top cover 30 side, the holding part 140 has a front frame 141A, a rear frame 141B, a left frame 141C, and a right frame 141D. The front frame 141A, rear frame 141B, left frame 141C, and right frame 141D are each part of a generally rectangular frame surrounding the vibrating part 110. Specifically, when viewed from the base 130, the front frame 141A is the portion extending along the X-axis direction on the side of the excitation part 120. When viewed from the excitation part 120, the rear frame 141B is the portion extending along the X-axis direction on the side of the base 130. When viewed from the vibrating arm 121D, the left frame 141C is the portion extending along the Y-axis direction on the side of the vibrating arm 121A. When viewed from the vibrating arm 121A, the right frame 141D is the portion extending along the Y-axis direction on the side of the vibrating arm 121D. The front frame 141A and the rear frame 141B are each bisected by an imaginary plane P.

[0051] The two ends of the left frame 141C are each connected to one end of the front frame 141A and one end of the rear frame 141B. The two ends of the right frame 141D are each connected to the other end of the front frame 141A and the other end of the rear frame 141B. The front frame 141A and the rear frame 141B face each other in the Y-axis direction, separated by the vibrating part 110. The left frame 141C and the right frame 141D face each other in the X-axis direction, separated by the vibrating part 110.

[0052] A retaining arm 150 is disposed inside the retaining portion 140, connecting the base 130 to the retaining portion 140. Figure 3 In the structural example shown, when viewed from the top cover 30 side, the retaining arm 150 has a left retaining arm 151A and a right retaining arm 151B. An imaginary plane P is located between the right retaining arm 151B and the left retaining arm 151A, and the right retaining arm 151B and the left retaining arm 151A are planar symmetrical to each other.

[0053] The left retaining arm 151A connects the rear end portion 131B of the base 130 to the left frame 141C of the retaining portion 140. The right retaining arm 151B connects the rear end portion 131B of the base 130 to the right frame 141D of the retaining portion 140. The left retaining arm 151A has a retaining rear arm 152A and a retaining side arm 153A, and the right retaining arm 151B has a retaining rear arm 152B and a retaining side arm 153B.

[0054] The retaining rear arms 152A and 152B extend from the rear end 131B of the base 130 between the base 130 and the retaining portion 140. Specifically, the retaining rear arm 152A extends from the rear end 131B of the base 130 toward the rear frame 141B, and extends toward the left frame 141C after flexion. The retaining rear arm 152B extends from the rear end 131B of the base 130 toward the rear frame 141B, and extends toward the right frame 141D after flexion. The width of each of the retaining rear arms 152A and 152B is smaller than the width of each of the vibrating arms 121A to 121D.

[0055] The retaining side arm 153A extends along the outer vibrating arm 121A between the outer vibrating arm 121A and the retaining portion 140. The retaining side arm 153B extends along the outer vibrating arm 121D between the outer vibrating arm 121D and the retaining portion 140. Specifically, the retaining side arm 153A extends from the end of the retaining rear arm 152A on the left frame 141C side toward the front frame 141A, and connects to the left frame 141C after bending. The retaining side arm 153B extends from the end of the retaining rear arm 152B on the right frame 141D side toward the front frame 141A, and connects to the right frame 141D after bending. The widths of the retaining side arms 153A and 153B are approximately the same as the widths of the retaining rear arms 152A and 152B.

[0056] Furthermore, the retaining arm 150 is not limited to the structure described above. For example, the retaining arm 150 may also be connected to the left end 131C and the right end 131D of the base 130. In addition, the retaining arm 150 may also be connected to the front frame 141A or the rear frame 141B of the retaining part 140. Furthermore, the number of retaining arms 150 may be one or more.

[0057] like Figure 3 As shown, a blocking member B11 is provided in the resonator 10.

[0058] Viewed from above, the blocking member B11 is formed in a frame shape surrounding the vibrating part 110. Furthermore, the blocking member B11 is disposed in the holding part 140 and surrounds the chamber 21. The blocking member B11 is continuous in the circumferential direction. Specifically, the portion of the blocking member B11 disposed in the front frame 141A connects one end of the portions of the blocking member B11 disposed in the left frame 141C and the right frame 141D, respectively, and the portion of the blocking member B11 disposed in the rear frame 141B connects the other end of the portions of the blocking member B11 disposed in the left frame 141C and the right frame 141D, respectively. Viewed from above, the blocking member B11 is disposed in the region surrounded by the joint H described later, i.e., inside the joint H. The blocking member B11 may also be configured to overlap with the joint H. Alternatively, the blocking member B11 may be disposed in the region closer to the outer edge of the resonator 10 than the joint H, i.e., outside the joint H.

[0059] Next, refer to Figure 4 The stacked structure of the resonant device 1 according to the first embodiment will be described. Figure 4 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the first embodiment. Additionally, Figure 4 This diagram is used to conceptually illustrate the stacked structure of the resonant device 1. Figure 4The structural components shown are not necessarily located on the same plane section. Here, the direction from the lower cover 20 to the upper cover 30 is referred to as "upper" and the direction from the upper cover 30 to the lower cover 20 is referred to as "lower".

[0060] The resonator 10 is held between the lower cover 20 and the upper cover 30. Specifically, the holding portion 140 of the resonator 10 is respectively joined to the sidewall 23 of the lower cover 20 and the sidewall 33 of the upper cover 30. In this way, a vibration space in which the vibrating portion 110 can vibrate is formed by the lower cover 20, the upper cover 30, and the holding portion 140. As an example, the resonator 10, the lower cover 20, and the upper cover 30 are each formed using a silicon (Si) substrate. Alternatively, the resonator 10, the lower cover 20, and the upper cover 30 can also be formed using an SOI (Silicon On Insulator) substrate obtained by stacking silicon layers and silicon oxide films, respectively. Furthermore, the resonator 10, the lower cover 20, and the upper cover 30 can each be formed using substrates other than silicon substrates, such as compound semiconductor substrates, glass substrates, ceramic substrates, resin substrates, etc., as long as the substrates can be processed based on microfabrication technology.

[0061] The vibrating part 110, the holding part 140, and the holding arm 150 are integrally formed using the same process. The resonator 10 has a silicon oxide film F21, a silicon substrate F2, a metal film E1, a piezoelectric film F3, a metal film E2, and a protective film F5. The resonator 10 also has the aforementioned metal films 125A to 125D at the end portions 122A to 122D. The resonator 10 is formed by patterning a stack composed of the silicon substrate F2, the metal film E1, the piezoelectric film F3, the metal film E2, and the protective film F5 using a removal process. This removal process is, for example, dry etching by irradiating an argon (Ar) ion beam.

[0062] A silicon oxide film F21 is disposed on the lower surface of a silicon substrate F2 and sandwiched between the silicon substrate P10 and the silicon substrate F2. The silicon oxide film F21 is formed of silicon oxide, for example, containing SiO2. A portion of the silicon oxide film F21 is exposed relative to the cavity 21 of the lower cover 20, i.e., relative to the vibration space of the resonator 10. The silicon oxide film F21 functions as a temperature characteristic correction layer that reduces the temperature coefficient of the resonant frequency of the resonant 10, i.e., the rate of change of the resonant frequency per unit temperature, at least near room temperature. Therefore, the silicon oxide film F21 improves the temperature characteristics of the resonator 10. Alternatively, the silicon oxide film may be formed on the upper surface of the silicon substrate F2, or on both the upper and lower surfaces of the silicon substrate F2. The silicon oxide film F21 corresponds to an example of the "first silicon oxide film" according to the present invention.

[0063] The silicon substrate F2 is a single crystal of silicon, for example, formed from a degenerate n-type silicon (Si) semiconductor with a thickness of about 6 μm. The silicon substrate F2 can contain phosphorus (P), arsenic (As), or antimony (Sb) as n-type dopants. The resistivity of the degenerate silicon (Si) used in the silicon substrate F2 is, for example, less than 16 mΩ·cm, more preferably less than 1.2 mΩ·cm. The silicon substrate F2 corresponds to an example of the "single-crystal silicon film" involved in this invention.

[0064] Metal film E1 is stacked on silicon substrate F2, piezoelectric film F3 is stacked on metal film E1, and metal film E2 is stacked on piezoelectric film F3. Each of metal films E1 and E2 has a portion that functions as an excitation electrode for exciting vibration arms 121A-121D, and a portion that functions as a lead-out electrode for electrically connecting the excitation electrode to an external power source. The portions of metal films E1 and E2 that function as excitation electrodes face each other across the piezoelectric film F3 in the arm portions 123A-123D of vibration arms 121A-121D. The portions of metal films E1 and E2 that function as lead-out electrodes are, for example, led from base 130 to holding portion 140 via holding arm 150. Metal film E1 is electrically continuous across the entire resonator 10. Metal film E2 is electrically separated at portions formed in the outer vibration arms 121A and 121D and portions formed in the inner vibration arms 121B and 121C. Metal film E1 corresponds to an example of the "lower electrode" involved in this invention, and metal film E2 corresponds to an example of the "upper electrode" involved in this invention.

[0065] The thicknesses of metal films E1 and E2 are, for example, approximately 0.1 μm to 0.2 μm. After deposition, metal films E1 and E2 are patterned by etching or other methods to form excitation electrodes and lead-out electrodes. Metal films E1 and E2 are formed, for example, from a metal material with a body-centered cubic crystal structure. Specifically, metal films E1 and E2 are formed from materials such as Mo (molybdenum) or tungsten (W). When the silicon substrate F2 is a degenerate semiconductor substrate with high conductivity, metal film E1 can be omitted, and the silicon substrate F2 can function as the lower electrode. Furthermore, from the viewpoint of suppressing the generation of parasitic capacitance and suppressing the generation of short circuits at the end of the resonant device 1, an insulating film can be provided between metal film E1 and silicon substrate F2. Such an insulating film can be formed from the same material as silicon oxide film F21, or from the same material as piezoelectric film F3.

[0066] The piezoelectric film F3 is a thin film formed by a piezoelectric material that converts electrical energy into mechanical energy. The piezoelectric film F3 expands and contracts in the Y-axis direction within the XY plane according to the electric field applied by the metal films E1 and E2. This expansion and contraction of the piezoelectric film F3 causes the vibrating arms 121A to 121D to buckle, displacing their open ends toward the base plate 22 of the lower cover 20 and the base plate 32 of the upper cover 30. Anti-phase alternating voltages are applied to the upper electrodes of the outer vibrating arms 121A and 121D and the upper electrodes of the inner vibrating arms 121B and 121C. Therefore, the outer vibrating arms 121A and 121D vibrate in opposite phase to the inner vibrating arms 121B and 121C. For example, when the open ends of the outer vibrating arms 121A and 121D displace toward the lower cover 20, the open ends of the inner vibrating arms 121B and 121C displace toward the upper cover 30. Through such opposite-phase vibrations, the vibrating part 110 generates a torsional moment centered on a rotation axis extending along the Y-axis. The base 130 buckles due to this torsional moment, and the left end 131C and the right end 131D are displaced toward the lower cover 20 or the upper cover 30. That is, the vibrating part 110 of the resonator 10 vibrates in an out-of-plane buckling vibration mode.

[0067] The piezoelectric film F3 is formed from a material with a wurtzite-type hexagonal crystal structure. For example, it can be primarily composed of nitrides or oxides such as aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), gallium nitride (GaN), or indium nitride (InN). Additionally, scandium aluminum nitride is a structure where a portion of the aluminum in aluminum nitride is replaced by scandium; it can also be replaced by two elements such as magnesium (Mg) and niobium (Nb) or magnesium (Mg) and zirconium (Zr). The thickness of the piezoelectric film F3 is, for example, about 1 μm, but can also be about 0.2 μm to 2 μm.

[0068] A protective film F5 is stacked on top of the metal film E2. The protective film F5, for example, protects the metal film E2 from oxidation. The material of the protective film F5 is, for example, an oxide, nitride, or oxynitride containing aluminum (Al), silicon (Si), or tantalum (Ta). A parasitic capacitance reduction film, which reduces the parasitic capacitance formed between the internal wirings of the resonator 10, may also be stacked on top of the protective film F5.

[0069] Metal films 125A to 125D are stacked on top of the protective film F5 at the end portions 122A to 122D. Metal films 125A to 125D function as both mass-increasing films and frequency-adjusting films. From the viewpoint of serving as frequency-adjusting films, it is preferable that the metal films 125A to 125D are formed of a material whose mass reduction rate based on etching is faster than that of the protective film F5. The mass reduction rate is expressed as the product of the etching rate and the density. The etching rate is the thickness removed per unit time. Regarding the protective film F5 and the metal films 125A to 125D, if the relationship of the mass reduction rates is as described above, the magnitude relationship of the etching rates is arbitrary. Furthermore, from the viewpoint of serving as mass-increasing films, it is preferable that the metal films 125A to 125D are formed of a material with a high specific gravity. From both of these viewpoints, the material of the metal films 125A to 125D can be, for example, a metallic material such as molybdenum (Mo), tungsten (W), gold (Au), platinum (Pt), nickel (Ni), or titanium (Ti). Alternatively, when the metal films 125A to 125D are used as frequency tuning films, a portion of the protective film F5 may also be removed during the finishing process of the metal films 125A to 125D. In this case, the protective film F5 also functions as a frequency tuning film.

[0070] Localized areas of each of the metal films 125A to 125D are removed through a finishing process in which the frequency is adjusted. The finishing process for the metal films 125A to 125D is, for example, dry etching by irradiation with an argon (Ar) ion beam. While the ion beam can irradiate a wide area, resulting in excellent processing efficiency, there is a concern that the metal films 125A to 125D may become charged. To prevent the vibration characteristics of the resonator 10 from deteriorating due to changes in the vibration trajectory of the vibrating arms 121A to 121D caused by the charging of the metal films 125A to 125D, it is preferable to ground the metal films 125A to 125D. Therefore, metal film 125A is electrically connected to metal film E1 via a through electrode through which the piezoelectric film F3 and the protective film F5 pass. Similarly, metal films 125B to 125D, which are not shown in the figure, are also electrically connected to metal film E1 via a through electrode. Alternatively, metal films 125A to 125D can also be electrically connected to metal film E1 via, for example, side electrodes provided on the sides of the end portions 122A to 122D. Metal films 125A to 125D can also be electrically connected to metal film E2.

[0071] Lead wires C1 and C2 are formed on the protective film F5 of the holding part 140. Lead wire C1 passes through the through hole formed in the piezoelectric film F3 and the protective film F5 and is electrically connected to the metal film E1. Lead wire C2 passes through the through hole formed in the protective film F5 and is electrically connected to the portion of the metal film E2 formed on the outer vibrating arms 121A and 121D. Although not shown in the figure, lead wires are also formed on the protective film F5 and are electrically connected to the portion of the metal film E2 formed on the inner vibrating arms 121B and 121C. Lead wires C1 and C2 are formed of a metallic material such as aluminum (Al), germanium (Ge), gold (Au), or tin (Sn).

[0072] The bottom plate 22 and sidewall 23 of the lower cover 20 are integrally formed by a silicon substrate P10. The silicon substrate P10 is formed of a non-degenerate silicon semiconductor with a resistivity of, for example, 10 Ω·cm or higher. The thickness of the lower cover 20 is greater than the thickness of the silicon substrate F2, for example, about 150 μm. The silicon substrate P10 corresponds to an example of the "first silicon substrate" involved in this invention.

[0073] When the resonator 10 and the lower cover 20 are regarded as MEMS substrate 50, for example, the silicon substrate P10 of the lower cover 20 is equivalent to the support substrate (processing layer) of the SOI substrate, the silicon oxide film F21 of the resonator 10 is equivalent to the BOX layer of the SOI substrate, and the silicon substrate F2 of the resonator 10 is equivalent to the active layer (device layer) of the SOI substrate.

[0074] A barrier member B11 is disposed on the MEMS substrate 50. The barrier member B11 is disposed in the resonator 10 and on the side opposite to the top cover 30 in the stacked structure composed of metal films E1, E2, and piezoelectric film F3. The barrier member B11 penetrates the silicon substrate F2 and the silicon oxide film F21, with its bottom surface disposed inside a through-hole located at the silicon substrate P10. The barrier member B11 covers the bottom and inner sides of the inner surface of the through-hole. In other words, the barrier member B11 is disposed across the silicon substrate F2, the silicon oxide film F21, and the silicon substrate P10. The thickness of the barrier member B11 is greater than the thickness of the silicon oxide film F21. In other words, the portion of the barrier member B11 formed on the bottom surface of the through-hole covers the end of the silicon oxide film F21 exposed through the through-hole. The internal space of the through-hole can also be filled by the barrier member B11, or the space surrounded by the barrier member B11 formed along the inner surface of the through-hole can be filled by other members. The lower end of the barrier member B11 is surrounded by the silicon substrate P10, and the upper end of the barrier member B11 is covered by the piezoelectric film F3. As described above, the barrier member B11 surrounds the vibrating part 110 and is formed in a frame shape on the holding part 140. Therefore, the barrier member B11 divides the silicon oxide film F21. Specifically, the silicon oxide film F21 is divided into a portion located inside the barrier member B11 and partially exposed in the vibration space, and a portion located outside the barrier member B11 and partially exposed in the external space.

[0075] The barrier member B11 only needs to cover at least the inner surface of the through-hole. That is, it only needs to cover the end of the silicon oxide film F21 exposed through the through-hole, thereby preventing the intrusion of helium and other gases through the silicon oxide film F21. Figure 4 In the example shown, the through hole with the internal barrier member B11 is covered by the piezoelectric film F3, but it can also be covered by the metal film E1 or other components.

[0076] Alternatively, the barrier member B11 may also break the silicon oxide film disposed between layers other than the silicon oxide film F21. For example, when the MEMS substrate 50 has a silicon oxide film between the silicon substrate F2 and the metal film E1 or between the silicon substrate F2 and the piezoelectric film F3, the barrier member B11 may break the silicon oxide film. Furthermore, when the MEMS substrate 50 has a silicon oxide film between the metal film E2 and the protective film F5 or between the piezoelectric film F3 and the protective film F5, the barrier member B11 may also break the silicon oxide film.

[0077] Furthermore, the barrier member B11 is not limited to the structure described above, as long as it is a structure that divides the silicon oxide film F21. For example, the barrier member B11 may be provided inside the through-hole formed only at the silicon oxide film F21, or it may be provided inside the through-hole formed at the silicon oxide film F21 extending from the upper surface of the MEMS substrate 50 (the surface on the side of the upper cover 30). In addition, it may be provided inside the through-hole formed at the silicon oxide film F21 extending from the lower surface of the MEMS substrate 50 (the surface opposite to the upper cover 30), i.e., the lower surface of the silicon substrate P10.

[0078] The helium permeability (hereinafter referred to as "helium permeability") of the barrier member B11 is lower than that of the silicon oxide film F21. Furthermore, among the components constituting the MEMS substrate 50, the silicon oxide film F21 has higher helium permeability compared to silicon substrates P10 and F2, piezoelectric film F3, or metal films E1 and E2. Therefore, by using the barrier member B11 to interrupt the silicon oxide film F21, the intrusion of helium into the vibration space of the resonator 10 via the silicon oxide film F21 is prevented, thus suppressing the decrease in the vacuum level of the vibration space of the resonator 10. In addition, the barrier member B11 similarly suppresses the intrusion into the vibration space of the resonator 10 for gases with small atomic radii other than helium.

[0079] The material of the barrier member B11 is not particularly limited if its helium permeability is lower than that of silicon oxide. The barrier member B11 is formed of a metallic material, for example, with aluminum (Al), germanium (Ge), gold (Au), silver (Ag), copper (Cu), or tin (Sn) as its main components. However, the barrier member B11 is not limited to the above-mentioned methods; it can also be formed of semiconductor materials such as silicon or ceramic materials such as silicon nitride, or a combination thereof. When the barrier member B11 is formed of a metallic material, it can effectively prevent the intrusion of helium into the vibration space. When the barrier member B11 is formed of silicon or silicon nitride, it can prevent the intrusion of helium into the vibration space without generating metal diffusion from the barrier member B11 towards the silicon substrates P10 and F2.

[0080] The bottom plate 32 and sidewall 33 of the top cover 30 are integrally formed from a silicon substrate Q10. A silicon oxide film Q11 is provided on the surface of the silicon substrate Q10. Specifically, it is provided in the regions between the silicon substrate Q10 and the through electrodes V1, V2 (described later), the regions between the silicon substrate Q10 and the internal terminals Y1, Y2 (described later), and the regions between the silicon substrate Q10 and the external terminals T1, T2 (described later). The silicon oxide film Q11 prevents short circuits of electrodes formed through the silicon substrate Q10. Alternatively, since no electrodes that would cause short circuits are provided on the inner wall of the cavity 31 on the surface of the silicon substrate Q10, the silicon substrate Q10 is exposed at the inner wall of the cavity 31. The silicon oxide film Q11 is formed, for example, by thermal oxidation of the silicon substrate Q10 or chemical vapor deposition (CVD). The thickness of the top cover 30 is, for example, about 150 μm. The silicon substrate Q10 corresponds to an example of the "second silicon substrate" according to the present invention.

[0081] The lower surface of the base plate 32 of the top cover 30 has a metal film 70. The metal film 70 is a degassing agent that adsorbs gas from the vibrating space formed by the chambers 21 and 31 to improve the vacuum level, for example, adsorbing hydrogen gas. The metal film 70 may contain, for example, titanium (Ti), zirconium (Zr), vanadium (V), niobium (Nb), tantalum (Ta), or an alloy containing at least one of these metals. The metal film 70 may also contain oxides of alkali metals or alkaline earth metals. Alternatively, a layer (not shown) may be provided between the silicon substrate Q10 and the metal film 70, such as a layer to prevent hydrogen from diffusing from the silicon substrate Q10 to the metal film 70, or a layer to improve the adhesion between the silicon substrate Q10 and the metal film 70.

[0082] Through electrodes V1 and V2 are provided on the upper cover 30. Through electrodes V1 and V2 are disposed inside through holes penetrating the sidewall 33 along the Z-axis direction. Through electrodes V1 and V2 are surrounded by a silicon oxide film Q11 and are mutually insulated. Through electrodes V1 and V2 are formed, for example, by filling the through holes with polycrystalline silicon (Poly-Si), copper (Cu), or gold (Au).

[0083] Internal terminals Y1 and Y2 are provided on the lower surface of the upper cover 30, and external terminals T1 and T2 are provided on the upper surface of the upper cover 30. Internal terminal Y1 is connected to the lower end of the through electrode V1, and external terminal T1 is connected to the upper end of the through electrode V1. Internal terminal Y2 is connected to the lower end of the through electrode V2, and external terminal T2 is connected to the upper end of the through electrode V2. Internal terminal Y1 is a connection terminal that electrically connects the through electrode V1 to the lead wire C1, and external terminal T1 is a mounting terminal that grounds the metal film E1. Internal terminal Y2 is a connection terminal that electrically connects the through electrode V2 to the lead wire C2, and external terminal T2 is a mounting terminal that electrically connects the metal film E2 of the outer vibrating arms 121A and 121D to an external power supply. Additionally, although not shown in the figure, the upper cover 30 also has through holes, internal terminals, and external terminals that are electrically connected to the metal film E2 of the inner vibrating arms 121B and 121C.

[0084] Multiple internal terminals, including internal terminals Y1 and Y2, are electrically insulated from each other by a silicon oxide film Q11. Multiple external terminals, including external terminals T1 and T2, are also electrically insulated from each other by a silicon oxide film Q11. The multiple internal and external terminals are formed by plating nickel (Ni), gold (Au), silver (Ag), or copper (Cu) onto a metallization layer (substrate) such as chromium (Cr), tungsten (W), or nickel (Ni). Alternatively, to balance parasitic capacitance and mechanical strength, the multiple external terminals may include dummy terminals electrically insulated from the resonator 10.

[0085] A joint H is formed between the side wall 33 of the upper cover 30 and the holding portion 140 of the resonator 10. In plan view, the joint H surrounds the vibrating portion 110 in a circumferentially continuous frame shape, sealing the vibration space formed by the chambers 21 and 31 in a vacuum state. The joint H is formed, for example, by sequentially stacking aluminum (Al) films, germanium (Ge) films, and aluminum (Al) films from the resonator 10 side and eutectic bonding them. The joint H may also contain gold (Au), tin (Sn), copper (Cu), titanium (Ti), aluminum (Al), germanium (Ge), silicon (Si), and alloys containing at least one of these materials. Furthermore, to improve the tightness between the resonator 10 and the upper cover 30, the joint H may also contain an insulator composed of metal compounds such as titanium nitride (TiN) or tantalum nitride (TaN). Although each metal film of the joint H is illustrated as an independent layer, they actually form a eutectic alloy, and therefore, clear boundaries are not necessarily present.

[0086] Next, refer to Figure 5 and Figure 6 The manufacturing method of the resonant device 1 according to the first embodiment will be described. Figure 5 This is a flowchart that schematically illustrates the manufacturing method of the MEMS substrate according to the first embodiment. Figure 6 This diagram schematically illustrates the process of setting the barrier member. Furthermore, the manufacturing processes of the upper cover 30 and the bonding process between the MEMS substrate 50 and the upper cover 30 in the manufacturing process of the resonant device can utilize existing manufacturing methods, therefore, descriptions are omitted here.

[0087] First, an SOI substrate is prepared (S10). First, silicon substrates P10 and F2, both having undergone single-sided mirror polishing, are prepared. A cavity 21 is formed on the mirror side of silicon substrate P10, and a silicon oxide film F21 is formed on the mirror side of silicon substrate F2. Next, the mirror sides of silicon substrate P10 and silicon substrate F2 are bonded together and subjected to heat treatment to directly bond silicon substrate P10 and silicon oxide film F21.

[0088] Next, a frame-shaped through-hole HL is formed (S20). The through-hole HL is formed from the upper surface of the silicon substrate F2 by an etching-based removal process. The through-hole HL penetrates the silicon substrate F2 and the silicon oxide film F21, forming a recess on the silicon substrate P10. When viewed from above, the through-hole HL is formed as a frame shape that surrounds the cavity 21 and is continuous in the circumferential direction. In addition, the removal process used to form the through-hole HL is not limited to etching; for example, it can also be formed by cutting, grinding, electrical discharge machining, or laser machining.

[0089] Next, the barrier member B11 is deposited (S30). The barrier member B11 is deposited, for example, by vapor deposition methods such as PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition). The barrier member B11 is disposed inside the through-hole HL, covering the upper surface of the silicon substrate F2. In order to fill the interior of the through-hole HL with the barrier member B11, it is preferable to deposit the barrier member B11 by plasma CVD, which is capable of forming a thick-walled film.

[0090] Next, the excess barrier member B11 is removed (S40). Specifically, while leaving the barrier member B11 disposed inside the through hole HL, the barrier member B11 disposed on the upper surface of the silicon substrate F2 is removed, exposing the upper surface of the silicon substrate F2. The excess barrier member B11 is removed, for example, by grinding.

[0091] Subsequently, metal film E1, piezoelectric film F3, metal film E2, and protective film F5 are sequentially formed on silicon substrate F2. Patterns are then etched onto the vibrating part 110, holding part 140, and holding arm 150 of resonator 10. Furthermore, the mass-increasing film is adjusted while monitoring the frequency of resonator 10 to regulate its frequency. The MEMS substrate 50 thus manufactured is then joined to the prepared top cover 30 via bonding part H in a vacuum environment. This process creates a resonant device 1 in which the vibration space of resonator 10 is vacuum-sealed.

[0092] As described above, the resonant device 1 includes a silicon substrate P10, a silicon substrate F2, and a barrier member B11 sandwiched between the silicon substrates P10 and F2, which breaks the silicon oxide film F21. This prevents helium and other gases from entering through the silicon oxide film F21, thus suppressing the decrease in the vacuum level of the vibration space.

[0093] Furthermore, the silicon oxide film F21, separated by the barrier member B11, is sandwiched between the silicon substrate P10 and the silicon substrate F2. The silicon oxide film F21 is equivalent to the BOX layer of the SOI substrate, and the silicon substrate F2 is equivalent to the active layer of the SOI substrate. The silicon substrate F2 constituting the resonator 10 is made of monocrystalline Si, thus achieving better frequency-temperature characteristics compared to cases where the silicon substrate F2 is formed of polycrystalline Si or amorphous Si. However, when the barrier member is placed inside the through-hole that only penetrates the silicon oxide film, and the silicon substrates are bonded together via the silicon oxide film and the barrier member, the surfaces of the silicon oxide film and the barrier member need to be polished before the silicon substrates are bonded together. However, due to the difference in hardness, the surface of the barrier member becomes concave or convex relative to the surface of the silicon oxide film. Therefore, gaps that can become intrusion paths for helium or the like are sometimes generated between the silicon substrate and the silicon oxide film or between the silicon substrate and the barrier member. In contrast, in the resonant device 1 of this embodiment, a through hole is formed after the silicon substrate P10 and the silicon substrate F2 are bonded together via the silicon oxide film F21. A barrier member B11 is provided inside the through hole. Therefore, gaps that can become intrusion paths for helium or the like are not easily generated, and the reduction of the vacuum level of the vibration space can be suppressed.

[0094] After the silicon substrate P10 is bonded to the silicon substrate F2 via the silicon oxide film F21 and before the stacked structure consisting of the lower electrode, the piezoelectric film F3, and the upper electrode is formed, a through-hole with a barrier member B11 disposed inside is formed. Therefore, compared to forming the through-hole after the stacked structure is formed, the through-hole can be made shallower. Therefore, even if the inclination of the inner side surface relative to the bottom surface of the through-hole is increased to facilitate the covering of the inner side surface of the through-hole by the barrier member B11, the enlargement of the resonant device 1 can be suppressed. In addition, by making the through-hole shallower, the reduction in the mechanical strength of the MEMS substrate 50 can be suppressed.

[0095] The thickness of the barrier member B11 is greater than the thickness of the silicon oxide film F21. Therefore, the barrier member B11, which covers the bottom surface of the through hole, fully covers the end of the silicon oxide film F21 exposed on the inner side of the through hole, preventing helium and other gases from entering through the silicon oxide film F21. In particular, even when the through hole is deep or the inner side of the through hole is approximately perpendicular to the bottom surface, making it difficult to form a film of the barrier member B11 on the inner side of the through hole, the barrier member B11, which forms a film on the bottom surface of the through hole, can still fully cover the end of the silicon oxide film F21 exposed on the inner side of the through hole.

[0096] The barrier member B11 covers at least the inner side of the inner surface of the through hole, so that the end of the silicon oxide film F21 exposed at the inner side of the through hole can be prevented from entering through the silicon oxide film F21 by the barrier member B11 covering the end of the silicon oxide film F21.

[0097] When the barrier member B11 is made of silicon or silicon nitride, it can prevent the intrusion of helium and the like without causing metal diffusion to the silicon substrate P10 and the silicon substrate F2.

[0098] When the barrier component B11 is made of metal, it can effectively prevent the intrusion of helium and other gases.

[0099] Other implementation methods will be described below. Additionally, regarding... Figures 1 to 6 Structures that are identical or similar to those shown are labeled with the same or similar reference numerals, and their descriptions are omitted where appropriate. Furthermore, identical effects based on the same structures are not mentioned sequentially.

[0100] <Second Implementation>

[0101] Next, refer to Figure 7 The structure of the resonant device 2 according to the second embodiment will be described. Figure 7 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the second embodiment.

[0102] In the second embodiment, when viewed from above, the barrier member B12 overlaps with the junction H. The barrier member B12 is disposed inside a through-hole extending from the uppermost layer of the MEMS substrate 50 to the silicon oxide film F21. Accordingly, when the uppermost layer of the MEMS substrate 50 is provided with silicon oxide, it is possible to prevent helium and other gases from intruding into the vibration space through the uppermost layer. Furthermore, the barrier member B12 is made of the same material constituting the junction H. Accordingly, the barrier member B12 can be provided during the process of providing the junction H, thus simplifying the manufacturing process. Moreover, even when the MEMS substrate 50 has a silicon oxide film other than the silicon oxide film F21 sandwiched between the silicon substrate P10 and the silicon substrate F2, according to this embodiment, the barrier member B12 can provide the same level of barrier as the silicon oxide film F21.

[0103] <Third Implementation>

[0104] Next, refer to Figure 8 The structure of the resonant device 3 according to the third embodiment will be described. Figure 8 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the third embodiment.

[0105] In the third embodiment, the resonant device 3 further includes blocking members B21 and B22. Blocking member B21 is disposed in the region between the silicon substrate Q10 of the upper cover 30 and the internal terminal Y1, and blocking member B22 is disposed in the region between the silicon substrate Q10 of the upper cover 30 and the internal terminal Y2. Blocking members B21 and B22 are disposed inside a through-hole that penetrates the silicon oxide film Q11 and forms a recess in the silicon substrate Q10. In plan view, blocking member B21 is configured as a frame surrounding the through electrode V1 and is continuous in the circumferential direction. Similarly, blocking member B22 is configured as a frame surrounding the through electrode V2 and is continuous in the circumferential direction. Blocking members B21 and B22 divide the silicon oxide film Q11 in the region surrounded by blocking members B21 and B22 and in other regions. The helium permeability of blocking members B21 and B22 is lower than that of the silicon oxide film Q11. By providing barrier components B21 and B22, helium and other gases can be prevented from entering the vibration space through the silicon oxide film Q11 surrounding the through electrodes V1 and V2. Barrier components B21 and B22 are formed of non-metallic materials such as silicon nitride. This is to prevent short circuits between the internal terminals Y1 and Y2 of the silicon substrate Q10.

[0106] <Fourth Implementation>

[0107] Next, refer to Figure 9 The structure of the resonant device 4 according to the fourth embodiment will be described. Figure 9 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the fourth embodiment.

[0108] In the fourth embodiment, the resonant device 4 further includes blocking members B23 and B24. Blocking member B23 is disposed in the region between the silicon substrate Q10 of the upper cover 30 and the external terminal T1, and blocking member B24 is disposed in the region between the silicon substrate Q10 of the upper cover 30 and the external terminal T2. Blocking members B23 and B24 are disposed inside a through-hole that penetrates the silicon oxide film Q11 and forms a recess in the silicon substrate Q10. In plan view, blocking member B23 is configured as a frame surrounding the through electrode V1 and is continuous in the circumferential direction. Similarly, blocking member B24 is configured as a frame surrounding the through electrode V2 and is continuous in the circumferential direction. Blocking members B23 and B24 divide the silicon oxide film Q11 in the region surrounded by blocking members B23 and B24 and in other regions. The blocking members B23 and B24 according to the fourth embodiment are formed of the same non-metallic material as the blocking members B21 and B22 according to the third embodiment. The barrier member can also be disposed in both the area between the silicon substrate Q10 of the upper cover 30 and the internal terminals Y1 and Y2, and the area between the silicon substrate Q10 of the upper cover 30 and the external terminals T1 and T2.

[0109] <Fifth Implementation>

[0110] Next, refer to Figure 10 The structure of the resonant device 5 according to the fifth embodiment will be described. Figure 10 This is a cross-sectional view conceptually representing the stacked structure of the resonant device according to the fifth embodiment.

[0111] In the fifth embodiment, the MEMS substrate 50 has a silicon oxide film on the surface facing the top cover 30, and the ends of the silicon oxide film are covered by the material constituting the bonding portion H. Furthermore, the top cover 30 also has a silicon oxide film on the surface facing the MEMS substrate 50, and the ends of the silicon oxide film are covered by the material constituting the bonding portion H. Accordingly, helium and other gases can be prevented from entering the vibration space via the silicon oxide films provided on the opposing surfaces of the MEMS substrate 50 and the top cover 30.

[0112] The following describes some or all of the embodiments of the present invention. However, the present invention is not limited to the following description.

[0113] According to one aspect of the present invention, a resonant device is provided, comprising: a first substrate including a first silicon substrate and a resonator; a second substrate facing the first substrate; and a frame-shaped joint that joins the first substrate and the second substrate to seal the vibration space of the resonator, the resonator having: a monocrystalline silicon film; and a first silicon oxide film sandwiched between the monocrystalline silicon film and the first silicon substrate, wherein the first silicon oxide film is divided by a frame-shaped first barrier member that surrounds the vibration portion of the resonator when viewed from above the first substrate, a through hole penetrating the monocrystalline silicon film and the first silicon oxide film is provided on the resonator of the first substrate and the second substrate, and the first barrier member is provided inside the through hole, the first barrier member having lower helium permeability than the first silicon oxide film.

[0114] Alternatively, the thickness of the first barrier member can be greater than the thickness of the first silicon oxide film.

[0115] Alternatively, the first barrier member may cover at least the inner side of the inner surface of the through hole.

[0116] Alternatively, the resonator may have: a lower electrode disposed on the second substrate side of the first silicon oxide film; a piezoelectric film disposed on the second substrate side of the lower electrode; and an upper electrode disposed on the second substrate side of the piezoelectric film.

[0117] Alternatively, the first barrier component may be made of silicon or silicon nitride.

[0118] Alternatively, the first barrier member can be made of metal.

[0119] Alternatively, when viewed from above, the first barrier member may be disposed in the area surrounded by the joint.

[0120] Alternatively, when viewed from above, the first barrier member overlaps with the joint, and the first barrier member is made of the material constituting the joint.

[0121] Alternatively, the second substrate may have: a second silicon substrate; a through electrode penetrating the second silicon substrate; an internal terminal disposed on the first substrate side of the through electrode; an external terminal disposed on the side of the through electrode opposite to the first substrate; and a second silicon oxide film continuously disposed across a region between the second silicon substrate and the through electrode, an inner region between the second silicon substrate and the internal terminal, and an outer region between the second silicon substrate and the external terminal. In at least one of the inner and outer regions, the second silicon oxide film is divided by a second barrier member formed in a frame shape surrounding the through electrode when the second substrate is viewed from above. The helium permeability of the second barrier member is lower than that of the second silicon oxide film.

[0122] Alternatively, the second barrier component may be made of silicon nitride.

[0123] Alternatively, the first substrate may have a third silicon oxide film on the surface facing the second substrate, and the ends of the third silicon oxide film may be covered by a material constituting the joint.

[0124] Alternatively, the second substrate may have a fourth silicon oxide film on the surface facing the first substrate, and the ends of the fourth silicon oxide film may be covered by a material constituting the joint.

[0125] According to another aspect of the present invention, a resonant device is provided, comprising: a first substrate including a resonator; a second substrate facing the first substrate; and a frame-shaped joint that joins the first substrate and the second substrate to seal the vibration space of the resonator, the second substrate having: a silicon substrate; a through electrode penetrating the silicon substrate; an internal terminal disposed on the first substrate side of the through electrode; an external terminal disposed on the side of the through electrode opposite to the first substrate; and a silicon oxide film continuously disposed across a region between the silicon substrate and the through electrode, an inner region between the silicon substrate and the internal terminal, and an outer region between the silicon substrate and the external terminal, wherein in the inner region, the silicon oxide film is interrupted by a frame-shaped barrier member surrounding the through electrode when viewed from above the second substrate, the barrier member having lower helium permeability than the silicon oxide film.

[0126] According to another aspect of the present invention, a method for manufacturing a resonant device is provided, comprising the following steps: preparing a first substrate including a silicon substrate and a resonator; preparing a second substrate; and joining the first substrate and the second substrate to seal the vibration space of the resonator, the resonator having: a monocrystalline silicon film; and a silicon oxide film sandwiched between the monocrystalline silicon film and the silicon substrate, wherein the silicon oxide film is divided by a barrier member formed in a frame shape surrounding the vibration portion of the resonator when viewed from above the first substrate, a through hole penetrating the monocrystalline silicon film and the silicon oxide film is provided on the resonator of the first substrate and the second substrate, and a barrier member is provided inside the through hole, the barrier member having a lower helium permeability than the silicon oxide film.

[0127] Alternatively, the steps of preparing the first substrate may include the following steps: setting a silicon substrate; setting a monocrystalline silicon film; bonding the silicon substrate and the monocrystalline silicon film via a silicon oxide film; forming a through hole that penetrates the silicon oxide film from the side of the monocrystalline silicon film; covering the inner surface of the through hole with a barrier member; and setting a stacked structure having a lower electrode, a piezoelectric film and an upper electrode on the monocrystalline silicon film and the barrier member.

[0128] Alternatively, the steps of preparing the first substrate may include the following steps: setting a silicon substrate; setting a single-crystal silicon film; bonding the silicon substrate and the single-crystal silicon film via a silicon oxide film; setting a stacked structure having a lower electrode, a piezoelectric film and an upper electrode on the single-crystal silicon film; forming a through hole penetrating the silicon oxide film from the side of the stacked structure; and covering the inner surface of the through hole with a barrier member.

[0129] The embodiments involved in this invention can be appropriately applied to devices that utilize the frequency characteristics of an oscillator, such as timing devices, sound generators, oscillators, and load sensors, and are not particularly limited thereto.

[0130] As described above, according to one aspect of the present invention, it is possible to provide a resonant device and a method thereof that can suppress the reduction of vacuum and have good frequency-temperature characteristics.

[0131] Furthermore, the embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit the scope of the invention. The present invention can be modified / improved without departing from its spirit, and the present invention includes its equivalents. That is, as long as the features of the present invention are present, any appropriate design modifications made to each embodiment by those skilled in the art are also included within the scope of the present invention. For example, the elements, their configurations, materials, conditions, shapes, and dimensions of each embodiment are not limited to the examples shown and can be appropriately modified. Moreover, the elements of each embodiment can be combined as long as it is technically feasible, and any combination thereof that includes the features of the present invention is included within the scope of the present invention.

[0132] Explanation of reference numerals in the attached figures

[0133] 1…Resonant device; 10…Resonator; 20…Lower cover; 30…Upper cover; 50…MEMS substrate; 110…Vibration part; 140…Holding part; 150…Holding arm; H…Joint part; B11, B12, B21, B22, B23, B24…Barrier members; P10, Q10F2…Silicon substrate; F21, Q11…Silicon oxide film; F3…Piezoelectric film; F5…Protective film; V1, V2…Through electrode; Y1, Y2…Internal terminal; T1, T2…External terminal.

Claims

1. A resonator device, characterized by, have: The first substrate includes a first silicon substrate and a resonator; The second substrate, which faces the first substrate; and A frame-shaped joint joins the first substrate and the second substrate to seal the vibration space of the resonator. The resonator has: a single-crystal silicon film; And a first silicon oxide film sandwiched between the single-crystal silicon film and the first silicon substrate, The first silicon oxide film is divided by a first barrier member formed in a frame shape that surrounds the vibrating part of the resonator when viewed from above the first substrate. In the first substrate and the second substrate, the resonator of the first substrate is provided with a through hole that penetrates the single-crystal silicon film and the first silicon oxide film. The first barrier member is provided inside the through hole. The helium permeability of the first barrier component is lower than that of the first silicon oxide film. The first silicon oxide film is divided by the first barrier member into: a first portion located inside the first barrier member and partially exposed to the vibration space; and a second portion located outside the first barrier member and partially exposed to the external space.

2. The resonant device according to claim 1, characterized in that, The thickness of the first barrier member is greater than the thickness of the first silicon oxide film.

3. The resonant device according to claim 1 or 2, characterized in that, The first barrier member covers at least the inner side of the inner surface of the through hole.

4. The resonant device according to claim 1 or 2, characterized in that, The resonator has: a lower electrode disposed on the second substrate side of the first silicon oxide film; and a piezoelectric film disposed on the second substrate side of the lower electrode. And an upper electrode, which is disposed on the second substrate side of the piezoelectric film.

5. The resonant device according to claim 1 or 2, characterized in that, The first barrier component is made of silicon or silicon nitride.

6. The resonant device according to claim 1 or 2, characterized in that, The first barrier component is made of metal.

7. The resonant device according to claim 1 or 2, characterized in that, When viewed from above, the first barrier member is disposed in the area surrounded by the joint.

8. The resonant device according to claim 1 or 2, characterized in that, When viewed from above, the first barrier member overlaps with the joint. The first barrier member is made of the material constituting the joint.

9. The resonant device according to claim 1 or 2, characterized in that, The second substrate has: Second silicon substrate; A through electrode that penetrates the second silicon substrate; An internal terminal is disposed on the first substrate side of the through electrode; External terminals, which are disposed on the side of the through electrode opposite to the first substrate; and A second silicon oxide film is continuously disposed across the region between the second silicon substrate and the through electrode, the inner region between the second silicon substrate and the inner terminal, and the outer region between the second silicon substrate and the outer terminal. In at least one of the inner and outer regions, the second silicon oxide film is interrupted by a second barrier member formed in a frame shape surrounding the through electrode when viewed from above the second substrate. The helium permeability of the second barrier member is lower than that of the second silicon oxide film.

10. The resonant device according to claim 9, characterized in that, The second barrier component is made of silicon nitride.

11. The resonant device according to claim 1 or 2, characterized in that, The first substrate has a third silicon oxide film on the surface facing the second substrate. The end of the third silicon oxide film is covered by the material constituting the junction.

12. The resonant device according to claim 1 or 2, characterized in that, The second substrate has a fourth silicon oxide film on the surface facing the first substrate. The end of the fourth silicon oxide film is covered by the material constituting the joint.

13. A resonant device, characterized in that, have: The first substrate includes a resonator; The second substrate, which faces the first substrate; and A frame-shaped joint joins the first substrate and the second substrate to seal the vibration space of the resonator. The second substrate has: Silicon substrate; A through electrode that penetrates the silicon substrate; An internal terminal is disposed on the first substrate side of the through electrode; An external terminal is disposed on the side of the through electrode opposite to the first substrate; as well as A silicon oxide film is continuously disposed across the region between the silicon substrate and the through electrode, the inner region between the silicon substrate and the internal terminal, and the outer region between the silicon substrate and the external terminal. In the inner region, the silicon oxide film is interrupted by a frame-shaped barrier member surrounding the through electrode when viewed from above the second substrate. The barrier component has lower helium permeability than the silicon oxide film. A through-hole is provided in the inner region, penetrating the silicon oxide film and forming a recess in the silicon substrate. The barrier component is disposed inside the through hole. The barrier component is continuous in the circumferential direction. The barrier component divides the silicon oxide film into: a first portion located inside the barrier component and partially exposed to the vibration space; and a second portion located outside the barrier component and partially exposed to the external space.

14. A method for manufacturing a resonant device, characterized in that, Includes the following steps: Prepare a first substrate including a silicon substrate and a resonator; Prepare the second substrate; and The first substrate and the second substrate are joined together to seal the vibration space of the resonator. The resonator has: a single-crystal silicon film; And the silicon oxide film sandwiched between the single-crystal silicon film and the silicon substrate, The silicon oxide film is divided by a frame-shaped barrier member that surrounds the vibrating part of the resonator when viewed from above the first substrate. In the first substrate and the second substrate, the resonator of the first substrate is provided with a through hole that penetrates the single-crystal silicon film and the silicon oxide film. The barrier component is provided inside the through hole. The barrier component has lower helium permeability than the silicon oxide film. The silicon oxide film is divided by the barrier member into: a first portion located inside the barrier member and partially exposed to the vibration space; and a second portion located outside the barrier member and partially exposed to the external space. The steps for preparing the first substrate include: The silicon substrate is configured; The single-crystal silicon film is configured; The silicon substrate is bonded to the monocrystalline silicon film via the silicon oxide film; After the bonding, the through hole is formed from the side of the monocrystalline silicon film through the monocrystalline silicon film and the silicon oxide film; The inner surface of the through hole is covered by the barrier member; and A stacked structure comprising a lower electrode, a piezoelectric film, and an upper electrode is disposed on the single-crystal silicon film and the barrier member.

15. A method for manufacturing a resonant device, characterized in that, Includes the following steps: Prepare a first substrate including a silicon substrate and a resonator; Prepare the second substrate; and The first substrate and the second substrate are joined together to seal the vibration space of the resonator. The resonator has: a single-crystal silicon film; And the silicon oxide film sandwiched between the single-crystal silicon film and the silicon substrate, The silicon oxide film is divided by a frame-shaped barrier member that surrounds the vibrating part of the resonator when viewed from above the first substrate. In the first substrate and the second substrate, the resonator of the first substrate is provided with a through hole that penetrates the single-crystal silicon film and the silicon oxide film. The barrier component is provided inside the through hole. The barrier component has lower helium permeability than the silicon oxide film. The silicon oxide film is divided by the barrier member into: a first portion located inside the barrier member and partially exposed to the vibration space; and a second portion located outside the barrier member and partially exposed to the external space. The steps for preparing the first substrate include the following: The silicon substrate is configured; The single-crystal silicon film is configured; The silicon substrate is bonded to the monocrystalline silicon film via the silicon oxide film; A stacked structure having a lower electrode, a piezoelectric film, and an upper electrode is formed on the single-crystal silicon film; Forming the through-hole extending through the silicon oxide film from this side of the stacked structure; and The barrier member covers the inner surface of the through hole.

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