Vibration Device

Abstract

To provide a vibration device that outputs an accurate oscillatory frequency.SOLUTION: A vibration device 1 has a vibration element 60, a first package 31 that accommodates the vibration element 60, and a second package 10 that accommodates and fixes the first package 31. The first package 31 includes a base substrate 32 that has a first surface 32a on which the vibration element 60 is arranged and a second surface 32b in the front-and-back relationship with the first surface 32a and includes single crystal silicon, an integrated circuit 40 that is provided on the first surface 32a or the second surface 32b and includes a temperature sensor circuit 46 and a heater circuit 47, and a lid 33 that is joined to the base substrate 32 to accommodate the vibration element 60 together with the base substrate 32.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vibration device. [Background technology]

[0002] Conventionally, as an example of a vibration device, an oscillator has been known in which the temperature of a vibration element is stabilized by heating the vibration element, thereby stabilizing the resonance frequency. For example, Patent Document 1 discloses an oven-controlled crystal oscillator (OCXO) that contains a vibration element, a heating element, and a circuit element as an oscillation unit in a package made of ceramic or the like, and outputs a stable resonance frequency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-28360 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the vibration device described in Patent Document 1 has a problem in that one end of the vibration element is connected to the heating element, making it difficult for the heat from the heating element to be transmitted evenly throughout the vibration element, resulting in a temperature difference within the vibration element and degrading the accuracy of the oscillation frequency. [Means for solving the problem]

[0005] The vibration device has a vibration element, a first package that houses the vibration element, and a second package that houses and fixes the first package, and the first package has a first surface on which the vibration element is arranged and a second surface that is in a front-back relationship with the first surface, and includes a base substrate made of single crystal silicon, an integrated circuit provided on the first surface or the second surface and including a temperature sensor circuit and a heater circuit, and a lid joined to the base substrate so as to house the vibration element together with the base substrate. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view showing a schematic structure of a vibration device according to a first embodiment. [Diagram 2] Cross-sectional view taken along line AA in Figure 1. [Diagram 3] FIG. 1 is a cross-sectional view showing a schematic structure of an oscillator. [Figure 4] FIG. 1 is a functional block diagram of an integrated circuit. [Diagram 5] FIG. 11 is a cross-sectional view showing a schematic structure of a vibration device according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view showing a schematic structure of a vibration device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] 1. First embodiment First, a vibration device 1 according to a first embodiment will be described with reference to FIGS. In FIG. 1, for convenience of explanation of the internal configuration of the vibration device 1, the lid 16 is removed. Also, for convenience of explanation, each of the following figures except for FIG. 4 illustrates an X-axis, a Y-axis, and a Z-axis as three mutually perpendicular axes. Also, the direction along the X-axis is called the "X-direction", the direction along the Y-axis is called the "Y-direction", and the direction along the Z-axis is called the "Z-direction". Also, the arrow side of each axis is called the "positive side", and the side opposite the arrow is called the "negative side". Also, the positive side of the Z direction is called the "upper side", and the negative side of the Z direction is called the "lower side".

[0008] 1 and 2, the resonator device 1 includes an oscillator 30 having a first package 31 that houses a resonator element 60, a second package 10 that houses and fixes the first package 31, and a lid 16 that forms an internal space 18 between the second package 10 and the lid 16. Therefore, the resonator device 1 of this embodiment corresponds to an oven-controlled crystal oscillator (OCXO) with a double package structure.

[0009] The first package 31 includes a base substrate 32 and a lid 33, and houses the vibration element 60 between the base substrate 32 and the lid 33. The base substrate 32 has a first surface 32a on which the vibration element 60 is arranged and a second surface 32b on the opposite side to the first surface 32a. The first surface 32a of the base substrate 32 is provided with an integrated circuit 40 including a temperature sensor circuit 46, a heater circuit 47, etc., and the vibration element 60 is fixed via a conductive member 73 such as a metal bump. Therefore, since the distance between the vibration element 60 and the temperature sensor circuit 46 or the heater circuit 47 is short, the temperature of the vibration element 60 can be detected with higher accuracy, and the vibration element 60 can be kept at a constant temperature more stably. In addition, an external connection terminal 50 for joining the first package 31 to the second package 10 is formed on the second surface 32b of the base substrate 32. The material of the first package 31 is a semiconductor containing single crystal silicon, for example, silicon.

[0010] The second package 10 is formed by stacking a flat plate-shaped first substrate 11 and a frame-shaped second substrate 12. The second package 10 also has an internal space 18 that is open upward.

[0011] The first package 31 is housed in the internal space 18. The first package 31 is fixed onto a bonding surface 11a, which is the upper surface of the first substrate 11, via a conductive member 72 such as a metal bump. Note that the state in which the first package 31 is fixed to the second package 10 means that the connection terminals 14 formed on the bonding surface 11a of the second package 10 to which the first package 31 is bonded, and the external connection terminals 50 formed on the second surface 32b of the base substrate 32 constituting the first package 31 are mechanically and electrically bonded via the conductive member 72.

[0012] External terminals 15 are formed on the bottom surface of the second package 10. The external terminals 15 are electrically connected to connection terminals 14 formed on the first substrate 11 via through electrodes and wiring (not shown).

[0013] The second package 10 is made of various ceramics, such as oxide ceramics, nitride ceramics, and carbide ceramics, which have a thermal conductivity lower than that of the first package 31. Therefore, the thermal conductivity of the first package 31 is higher than that of the second package 10, so that heat from the heater circuit 47 is easily transferred to the entire first package 31, and by covering the first package 31 with the second package 10, which has a low thermal conductivity, external temperature fluctuations can be effectively suppressed.

[0014] The lid 16 is flat and is joined to the upper surface of the second package 10 via a joining member 17. As a result, an airtight internal space 18 is formed between the second package 10 and the lid 16, and the first package 31 is housed in this internal space 18. The internal space 18 is in a reduced pressure state, preferably in a state closer to a vacuum. This reduces convection heat transfer from the first package 31 to the second package 10, and the internal space 18 can be maintained at a more constant temperature.

[0015] Next, the configuration of the oscillator 30 will be described with reference to FIG. The oscillator 30 of this embodiment is used, for example, as a temperature compensated crystal oscillator (TCXO) or an oven-controlled crystal oscillator (OCXO) having a single package structure. As shown in FIG. 3, such an oscillator 30 has a first package 31 composed of a base substrate 32 and a lid 33, and a vibration element 60 housed in an internal space 57 of the first package 31.

[0016] The first package 31 has a base substrate 32 and a lid 33 joined to the base substrate 32, and houses a vibration element 60 in an internal space 57 formed between the base substrate 32 and the lid 33. The base substrate 32 is a semiconductor substrate containing single crystal silicon, and in particular, is a silicon substrate in this embodiment. Note that the base substrate 32 is not particularly limited, and may be a semiconductor substrate other than silicon, such as a germanium substrate, a gallium arsenide substrate, a gallium phosphide substrate, a gallium nitride substrate, or a silicon carbide substrate, or may be a substrate other than a semiconductor substrate, such as a ceramic substrate.

[0017] The base substrate 32 is plate-shaped and has a first surface 32a on which the vibration element 60 is disposed, and a second surface 32b opposite the first surface 32a. An insulating film 37 is formed on the surface of the base substrate 32. An integrated circuit 40 electrically connected to the vibration element 60 and wiring 36 electrically connecting functional elements such as a temperature sensor circuit 46 and a heater circuit 47 formed on the integrated circuit 40 are formed on the first surface 32a of the base substrate 32. However, the integrated circuit 40 and wiring 36 may be formed on the second surface 32b of the base substrate 32 instead of the first surface 32a.

[0018] A passivation film 35 is formed on the integrated circuit 40, and an internal connection terminal 49 is formed on the passivation film 35, electrically connected to the wiring 36 and for bonding the vibration element 60. An external connection terminal 50 is formed on the insulating film 37 formed on the second surface 32b of the base substrate 32 for outputting a frequency signal or the like output from the integrated circuit 40 to the outside. The base substrate 32 has a through hole 51 penetrating the base substrate 32 in the Z direction, which is the thickness direction, and a conductive material is filled in the through hole 51 to form a through electrode 52. Therefore, the through electrode 52 can electrically connect the wiring 36 formed on the first surface 32a of the base substrate 32 to the external connection terminal 50 formed on the second surface 32b of the base substrate 32.

[0019] The vibration element 60 stored in the internal space 57 has a quartz substrate 61, an excitation electrode 62 that vibrates the quartz substrate 61, a connection terminal 63 that outputs a vibration signal to the outside and fixes the vibration element 60 to the first package 31, and a lead electrode (not shown) that electrically connects the excitation electrode 62 and the connection terminal 63. The vibration element 60 is disposed and fixed on the first surface 32a of the first package 31 via a conductive member 72 such as a metal bump. The state in which the vibration element 60 is fixed to the first package 31 means that the internal connection terminals 49 formed on the base substrate 32 of the first package 31 and the connection terminals 63 formed on the quartz substrate 61 of the vibration element 60 are mechanically and electrically joined via the conductive member 72. The quartz substrate 61 may be an AT-cut quartz substrate, an SC-cut quartz substrate, a BT-cut quartz substrate, or the like.

[0020] The lid 33 is a silicon substrate, like the base substrate 32. This makes the linear expansion coefficients of the base substrate 32 and the lid 33 equal, suppressing the generation of thermal stress due to thermal expansion, and resulting in an oscillator 30 with excellent vibration characteristics. In addition, since the oscillator 30 can be formed by a semiconductor process, the oscillator 30 can be manufactured with high precision and can be made compact. However, the lid 33 is not particularly limited, and a semiconductor substrate other than silicon, such as germanium, gallium arsenide, gallium phosphide, gallium nitride, silicon carbide, or the like, may be used. In addition, a substrate other than a semiconductor substrate, such as a metal substrate such as kovar, or a glass substrate, may be used.

[0021] The lid 33 has an opening on the side opposite to an outer surface 55, which is the upper surface of the lid 33, and has a bottomed recess 56 therein for accommodating the vibration element 60. The lid 33 is joined at its lower surface to the first surface 32a of the base substrate 32 via a joining member 34. As a result, the lid 33, together with the base substrate 32, forms an internal space 57 for accommodating the vibration element 60. Note that the method for joining the base substrate 32 and the lid 33 may be a joining method such as diffusion bonding that utilizes diffusion between metals contained in the base substrate 32 and the lid 33, without using the joining member 34.

[0022] Moreover, the internal space 57 is airtight and in a reduced pressure state, preferably in a state closer to a vacuum, which reduces viscous resistance and improves the oscillation characteristics of the vibration element 60. However, the atmosphere of the internal space 57 is not particularly limited, and may be, for example, an atmosphere filled with an inert gas such as nitrogen or argon, or may be in an atmospheric pressure state or a pressurized state instead of a reduced pressure state.

[0023] Next, the configuration of the integrated circuit 40 will be described with reference to FIG. As shown in FIG. 4, the integrated circuit 40 of this embodiment has an oscillation circuit 41, a multiplier circuit 42, an output circuit 43, a temperature compensation circuit 44, a temperature control circuit 45, a temperature sensor circuit 46, and a heater circuit 47.

[0024] The oscillation circuit 41 is electrically connected to the vibration element 60, amplifies the output signal of the vibration element 60, and causes the vibration element 60 to oscillate by feeding back the amplified signal to the vibration element 60. The multiplication circuit 42 multiplies the frequency signal output from the oscillation circuit 41. The output circuit 43 outputs the multiplied frequency signal from the external connection terminal 50 to the outside.

[0025] The temperature compensation circuit 44 performs temperature compensation based on the temperature information output from the temperature sensor circuit 46 so that the frequency variation of the oscillation signal of the oscillation circuit 41 is smaller than the frequency temperature characteristic of the vibration element 60 itself. This allows excellent temperature characteristics to be exhibited. Note that the temperature compensation circuit 44 may be, for example, one that adjusts the oscillation frequency of the oscillation circuit 41 by adjusting the capacitance of a variable capacitance circuit connected to the oscillation circuit 41, or one that adjusts the frequency of the output signal of the oscillation circuit 41 by a PLL (Phase Locked Loop) circuit or a direct digital synthesizer circuit.

[0026] The temperature control circuit 45 is a circuit for keeping the vibration element 60 at a constant temperature by controlling the amount of current flowing through the heater circuit 47 based on temperature information output from the temperature sensor circuit 46. For example, the temperature control circuit 45 controls the heater circuit 47 to pass a desired current when the current temperature determined from the output signal of the temperature sensor circuit 46 is lower than a set reference temperature, and controls the heater circuit 47 so that no current flows when the current temperature is higher than the reference temperature.

[0027] Also, for example, the temperature control circuit 45 may control the amount of current flowing through the heater circuit 47 to increase or decrease depending on the difference between the current temperature and the reference temperature. Here, the temperature sensor circuit 46 serves as both a temperature sensor for the temperature compensation circuit 44 and a temperature sensor for the temperature control circuit 45. This reduces the number of components, and allows the oscillator 30 to be made more compact. However, this is not limiting, and the temperature sensor for the temperature compensation circuit 44 and the temperature sensor for the temperature control circuit 45 may be provided separately.

[0028] The temperature sensor circuit 46 is an element that detects temperature, and can be formed by providing a Si diode or a PNP transistor in the integrated circuit 40. In addition, by forming platinum, it is possible to detect temperature based on the characteristic that the resistance value changes depending on the temperature. The temperature sensor circuit 46 is disposed at a position overlapping with the vibration element 60 in a plan view from the Z direction.

[0029] The heater circuit 47 is a heat generating element, and is formed by providing a resistor made of ITO (indium tin oxide) in the integrated circuit 40. The heater circuit 47 generates heat when current is applied, and the amount of heat generated can be adjusted by adjusting the current flowing through the resistor. The heater circuit 47 is disposed at a position overlapping with the vibration element 60 in a plan view from the Z direction.

[0030] As described above, in the resonator device 1 of the present embodiment, the resonator element 60 is housed in the first package 31 having high thermal conductivity in which the heater circuit 47 is formed, and therefore heat from the heater circuit 47 is transferred to the resonator element 60 by thermal radiation from the entire first package 31 heated by the heater circuit 47, thereby suppressing temperature unevenness in the resonator element 60. In addition, since the temperature sensor circuit 46 is formed in the first package 31, the temperature difference between the resonator element 60 and the temperature sensor circuit 46 can be suppressed, enabling highly accurate temperature control, and improving the accuracy of the oscillation frequency output from the resonator device 1.

[0031] Furthermore, since the conductive members 72 such as metal bumps are used for electrical connection between the first package 31 and the second package 10, the resonator device 1 can be made smaller in size than when bonding wires are used.

[0032] 2. Second embodiment Next, a vibration device 1a according to a second embodiment will be described with reference to FIG.

[0033] The resonator device 1a of this embodiment is similar to the resonator device 1 of the first embodiment, except that the position of the first package 31 joined to the first substrate 13 of the second package 10a is different, and the external connection terminal 50 and the connection terminal 14a are electrically connected to each other by a conductive wire 72a. Note that the following description will focus on the differences from the first embodiment, and similar items will be denoted by the same reference numerals and their description will be omitted.

[0034] 5, in the resonator device 1a, an outer surface 55 of the lid 33 of the first package 31 and a bonding surface 11a of the first substrate 13 of the second package 10a are mechanically connected via a bonding member 74. That is, the first package 31 is fixed to the bonding surface 11a upside down compared to the resonator device 1 of the first embodiment. In addition, the external connection terminal 50 formed on the second surface 32b of the first package 31 and the connection terminal 14a formed on the bonding surface 11a of the first substrate 13 are electrically connected via a conductive wire 72a.

[0035] With this configuration, the base substrate 32 on which the heater circuit 47 is formed can be located away from the joint between the first package 31 and the second package 10a, so that the first package 31 can be heated effectively. Also, the effect of external temperature fluctuations on the temperature sensor circuit 46 can be suppressed, thereby obtaining the same effect as the vibration device 1 of the first embodiment.

[0036] 3. Third embodiment Next, a vibration device 1b according to a third embodiment will be described with reference to FIG.

[0037] The resonator device 1b of this embodiment is similar to the resonator device 1 of the first embodiment, except that the position of the first package 31 joined to the first substrate 13b of the second package 10b is different, the external connection terminal 50 and the connection terminal 14b are electrically connected by a conductive wire 72b, and a heat insulating member 80 is provided between the first package 31 and the first substrate 13b of the second package 10b. The following description will focus on the differences from the first embodiment, and similar items are denoted by the same reference numerals and their description will be omitted.

[0038] 6, in the resonation device 1b, a heat insulating member 80 is provided between an outer surface 55 of the lid 33 of the first package 31 and a bonding surface 11a of the first substrate 13b of the second package 10b. The heat insulating member 80 is fixed to the first substrate 13b via a bonding member 75, and the first package 31 is fixed on the heat insulating member 80 via a bonding member 76. In addition, the external connection terminal 50 formed on the second surface 32b of the first package 31 and the connection terminal 14b formed on the bonding surface 11a of the first substrate 13b are electrically connected via a conductive wire 72b.

[0039] The heat insulating member 80 is made of a material having a lower thermal conductivity than the second package 10b. The heat insulating member 80 is not particularly limited, and may be, for example, various resin materials, particularly porous resin materials such as porous polyimide, and may be, in addition to resin materials, various glass materials, inorganic porous materials such as silica aerogel, and the like. The heat conductivity of the heat insulating member 80 is not particularly limited, but is preferably 1.0 W / m·K or less. This results in a heat insulating member 80 with a sufficiently low thermal conductivity. Furthermore, the heat insulating member 80 may contain a gap material with sufficiently low thermal conductivity, such as silica gel, which allows the thickness of the heat insulating member 80 to be controlled, and the heat insulating effect can be more reliably exhibited.

[0040] With this configuration, the heat from the heater circuit 47 formed in the integrated circuit 40 of the first package 31 can be sufficiently prevented from being transmitted to the second package 10b, thereby obtaining the same effect as the vibration device 1 of the first embodiment. [Explanation of symbols]

[0041] Reference Signs List 1, 1a, 1b... resonator device, 10... second package, 11... first substrate, 11a... bonding surface, 12... second substrate, 14... connection terminal, 15... external terminal, 16... lid, 17... bonding member, 18... internal space, 30... oscillator, 31... first package, 32... base substrate, 32a... first surface, 32b... second surface, 33... lid, 34... bonding member, 35... passivation film, 36... wiring, 37... insulating film, 40... collection Integration circuit, 41...oscillating circuit, 42...multiplier circuit, 43...output circuit, 44...temperature compensation circuit, 45...temperature control circuit, 46...temperature sensor circuit, 47...heater circuit, 49...internal connection terminal, 50...external connection terminal, 51...through hole, 52...through electrode, 55...outer surface, 56...recess, 57...internal space, 60...vibration element, 61...quartz substrate, 62...excitation electrode, 63...connection terminal, 72, 73...conductive member, 80...thermal insulating member.

Claims

1. A vibration element; a first package housing the vibration element; a second package that houses and fixes the first package; The first package comprises: a base substrate which is a semiconductor substrate including single crystal silicon and has a first surface on which the vibration element is disposed and a second surface which is opposite to the first surface; an integrated circuit formed on the first surface, the integrated circuit including an oscillator circuit, a temperature sensor circuit, and a heater circuit; a lid joined to the base substrate so as to house the vibration element together with the base substrate; an external connection terminal provided on the second surface of the base substrate; the second package has a connection terminal on a joining surface to which the first package is joined; the external connection terminal and the connection terminal are electrically connected via a conductive wire, an outer surface of the lid and the joining surface of the second package are mechanically connected to each other via a joining member; The vibration element is attached to the side opposite to the first surface side of the integrated circuit. Vibration devices.

2. The vibrating device of claim 1 , wherein the lid is made of a silicon substrate.

3. The thermal conductivity of the first package is higher than the thermal conductivity of the second package. The vibration device according to claim 1 or 2.

4. the first package has an external connection terminal on the second surface; the second package has a connection terminal on a joining surface to which the first package is joined; The external connection terminal and the connection terminal are mechanically and electrically joined via a conductive member. A vibration device according to any one of claims 1 to 3.

5. The first package is fixed to the second package via a heat insulating member. A vibration device according to any one of claims 1 to 4.

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