vibrating device

Abstract

Vibration device. A small vibration device having stable frequency characteristics is provided. A vibration device (1) has: a vibration element (60); a first package (31) that houses the vibration element (60); a heater (20) that is joined to the first package (31); and a second package (10) that houses the first package (31) and the heater (20), the first package (31) including: a base substrate (32) having a first surface (32a) on which the vibration element (60) is disposed and a second surface (32b) in an opposite relationship to the first surface (32a), the base substrate (32) including a single crystal silicon; an integrated circuit (40) provided on the first surface (32a) or the second surface (32b), the integrated circuit (40) including a temperature sensor (46); and a cap (33) joined to the base substrate (32) in a manner that houses the vibration element (60) together with the base substrate (32).

Description

TECHNICAL FIELD

[0001] The present application relates to a vibration device. BACKGROUND

[0002] As an example of a vibration device, an oscillator that stabilizes the temperature of a vibration element and the like by heating the vibration element and thereby stabilizes the resonance frequency is known. For example, Patent Literature 1 discloses a quartz oscillator (OCXO) with a thermostat that houses a vibration element, a heating element, and a circuit element that is an oscillation section in a package made of ceramic or the like, and outputs a stable oscillation frequency.

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2017-28360

[0004] However, in the vibration device described in Patent Literature 1, one end of the vibration element is connected to the heating element, and therefore there is a problem in that the heat of the heating element does not easily uniformly transfer to the entire vibration element and a temperature difference is generated in the vibration element, thereby degrading the precision of the oscillation frequency. SUMMARY

[0005] A vibration device includes a vibration element, a first package that houses the vibration element, a heater that is joined to the first package, and a second package that houses the first package and the heater, the first package including a base substrate that has a first surface on which the vibration element is disposed and a second surface that is in an opposite relationship to the first surface and includes a single crystal silicon, an integrated circuit that is disposed on the first surface or the second surface and includes a temperature sensor, and a lid that is joined to the base substrate in a manner that houses the vibration element together with the base substrate. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 is a plan view that shows the outline structure of the vibration device of the first embodiment.

[0007] Figure 2 is a cross-sectional view taken along line A-A in Figure 1

[0008] Figure 3 is a cross-sectional view that shows the outline structure of the oscillator.

[0009] Figure 4 is a functional block diagram of the integrated circuit.

[0010] Figure 5 is a cross-sectional view that shows the outline structure of the vibration device of the second embodiment.

[0011] Figure 6 is a cross-sectional view that shows the outline structure of the vibration device of the third embodiment.

[0012] ​Figure 7 is a sectional view showing a schematic structure of a vibration device according to the fourth embodiment.

[0013] Explanation of Reference Numerals

[0014] 1, 1a, 1b, 1c vibration device; 10 second package; 11 first substrate; 12 second substrate; 13 third substrate; 14 internal terminal; 15 external terminal; 16 cover; 17 joining member; 18 internal space; 20 heater; 21a joining surface; 21b surface; 22 first connection terminal; 23 second connection terminal; 30 oscillator; 31 first package; 32 base substrate; 32a first surface; 32b second surface; 33 cover; 34 joining member; 35 passivation film; 36 wiring; 37 insulating film; 40 integrated circuit; 41 oscillation circuit; 42 frequency multiplication circuit; 43 output circuit; 44 temperature compensation circuit; 45 temperature control circuit; 46 temperature sensor; 47 through-hole; 48 through-electrode; 49 internal connection terminal; 50 external connection terminal; 55 outer surface; 56 recessed portion; 57 internal space; 60 vibration element; 61 quartz substrate; 62 excitation electrode; 63 connection terminal; 71 conductive lead; 72, 73 conductive member; 80 heat insulating member. DETAILED DESCRIPTION

[0015] 1. First Embodiment

[0016] First, with reference to Figure 1 and Figure 2 the vibration device 1 of the first embodiment will be described.

[0017] In Figure 1 , in order to facilitate explanation of the internal structure of the vibration device 1, a state in which the cover 16 is removed is illustrated. Also, in order to facilitate explanation, in each of the following drawings other than Figure 4 , the X axis, the Y axis, and the Z axis are illustrated as three axes orthogonal to each other. Also, the direction along the X axis is referred to as the "X direction", the direction along the Y axis is referred to as the "Y direction", and the direction along the Z axis is referred to as the "Z direction". Also, the arrow side of each axis is referred to as the "positive side", and the side opposite the arrow is referred to as the "negative side". Also, the Z direction positive side is referred to as the "up", and the Z direction negative side is referred to as the "down".

[0018] As Figure 1 and Figure 2As shown, the vibration device 1 has an oscillator 30 having a first package 31 that houses a vibration element 60, a heater 20 that is joined to the first package 31, a second package 10 that houses the first package 31 of the oscillator 30 and the heater 20, and a lid 16 that forms an internal space 18 with the second package 10. Thus, the vibration device 1 of the present embodiment corresponds to a quartz oscillator with oven (OCXO) that takes the second package 10 as an oven.

[0019] The first package 31 is composed of a base substrate 32 and a lid 33, and the vibration element 60 is housed between the base substrate 32 and the lid 33.

[0020] The base substrate 32 has a first face 32a on which the vibration element 60 is disposed, and a second face 32b that is in an opposite relationship to the first face 32a. An integrated circuit 40 including an oscillation circuit 41 and a temperature sensor 46, and the like is provided on the first face 32a of the base substrate 32, and the vibration element 60 is fixed via a conductive member 73 such as a metal bump. Thus, the vibration element 60 is in close proximity to the temperature sensor 46, and thus the temperature of the vibration element 60 can be detected with high accuracy. Further, an external connection terminal 50 for joining the first package 31 to the heater 20 is formed on the second face 32b of the base substrate 32.

[0021] The material of the first package 31 is a semiconductor such as silicon that includes single-crystal silicon.

[0022] The heater 20 functions to maintain the first package 31 that houses the vibration element 60 at a constant temperature. The heater 20 has a joining face 21a to which the first package 31 is joined, and a face 21b on the opposite side of the joining face 21a is fixed to the second package 10.

[0023] The second package 10 is formed by laminating a first substrate 11 that is flat, a second substrate 12 that is frame-shaped, and a third substrate 13 that is frame-shaped and has a larger inner dimension than the second substrate 12. Further, the second package 10 has an internal space 18 that is open upward.

[0024] The first package 31 and the heater 20 are housed in the internal space 18. The face 21b on the opposite side of the joining face 21a of the heater 20 is fixed to the first substrate 11 via a joining member that is not shown, and the first package 31 is fixed to the joining face 21a that is the upper face of the heater 20 via a conductive member 72 such as a metal bump. Further, the state in which the first package 31 is fixed to the heater 20 is a state in which a first connection terminal 22 that is formed on the joining face 21a of the heater 20 to which the first package 31 is joined, and the external connection terminal 50 that is formed on the second face 32b of the base substrate 32 that constitutes the first package 31 are joined mechanically and electrically via the conductive member 72.

[0025] Furthermore, within the internal space 18, the internal terminal 14 formed on the second substrate 12 of the second package 10 and the second connection terminal 23 formed on the mating surface 21a of the heater 20 are electrically connected via conductive leads 71, such as metal solder wires. Additionally, the first connection terminal 22 and the second connection terminal 23 formed on the mating surface 21a of the heater 20 are electrically connected via wiring (not shown).

[0026] An external terminal 15 is formed on the lower surface of the second package 10. The external terminal 15 is electrically connected to an internal terminal 14 formed on the second substrate 12 via a through electrode (not shown) and interlayer wiring.

[0027] The second package 10 is made of various ceramics, such as oxide ceramics, nitride ceramics, and carbide ceramics, which have a lower thermal conductivity than the first package 31. Therefore, the first package 31 has a higher thermal conductivity than the second package 10, allowing heat from the heater 20 to be more easily transferred to the first package 31, thus effectively heating it. Furthermore, it effectively suppresses the effects of external temperature fluctuations on the second package 10.

[0028] The cover 16 is flat and is joined to the upper surface of the second package 10 via the joining member 17. This forms an airtight internal space 18 between the second package 10 and the cover 16, within which the first package 31 and the heater 20 are housed. Furthermore, the internal space 18 is in a depressurized state, preferably closer to a vacuum. This reduces convective heat transfer from the first package 31 or the heater 20 to the second package 10, further maintaining the internal space 18 at a constant temperature.

[0029] Next, refer to Figure 3 Explain the structure of oscillator 30.

[0030] The oscillator 30 in this embodiment is, for example, used as a temperature-compensated quartz oscillator (TCXO). Figure 3 As shown, such an oscillator 30 has a first package 31 consisting of a base substrate 32 and a cover 33, and a vibrating element 60 housed in the internal space 57 of the first package 31.

[0031] The first package 31 has a base substrate 32 and a cover 33 that is engaged with the base substrate 32, and a vibrating element 60 is housed in an internal space 57 formed between the base substrate 32 and the cover 33.

[0032] The base substrate 32 is a semiconductor substrate containing single-crystal silicon, and in this embodiment, is a silicon substrate. Note that the base substrate 32 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, or a substrate other than a semiconductor substrate, such as a ceramic substrate, can be used.

[0033] 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 that is in a front-rear relationship with the first surface 32a. Note that an insulating film 37 is formed on the front surface of the base substrate 32. Further, an integrated circuit 40 that is electrically connected to the vibration element 60, a wiring 36 that electrically connects functional elements such as an oscillation circuit 41 and a temperature sensor 46 formed on the integrated circuit 40 to each other, are formed on the first surface 32a of the base substrate 32. However, the integrated circuit 40 and the wiring 36 can be formed on the second surface 32b instead of the first surface 32a of the base substrate 32.

[0034] A passivation film 35 is formed on the integrated circuit 40, and further, an internal connection terminal 49 that is electrically connected to the wiring 36 and bonds the vibration element 60 is formed on the passivation film 35. Further, an external connection terminal 50 for outputting a frequency signal or the like output from the integrated circuit 40 to the outside is formed on the insulating film 37 formed on the second surface 32b of the base substrate 32. Moreover, the base substrate 32 has a through-hole 47 that penetrates the base substrate 32 in a Z direction that is a thickness direction, and a through electrode 48 is formed by filling a conductive material in the through-hole 47. Thus, the wiring 36 formed on the first surface 32a of the base substrate 32 and the external connection terminal 50 formed on the second surface 32b of the base substrate 32 can be electrically connected by the through electrode 48.

[0035] The vibration element 60 housed 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 that electrically connects the excitation electrode 62 and the connection terminal 63, which are not shown.

[0036] 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. Note that the state in which the vibration element 60 is fixed on the first package 31 means that the internal connection terminal 49 formed on the base substrate 32 of the first package 31 and the connection terminal 63 formed on the quartz substrate 61 of the vibration element 60 are mechanically and electrically bonded via the conductive member 72. Note that the quartz substrate 61 is an AT-cut quartz substrate, an SC-cut quartz substrate, a BT-cut quartz substrate, or the like.

[0037] The lid 33 is also a silicon substrate like the base substrate 32. Thus, the coefficients of linear expansion of the base substrate 32 and the lid 33 are equal, and generation of thermal stress due to thermal expansion is suppressed, resulting in an oscillator 30 having excellent vibration characteristics. In addition, the oscillator 30 can be formed by a semiconductor process, and thus the oscillator 30 can be manufactured with high precision, and can be miniaturized. 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, can be used. In addition, a metal substrate such as Kovar, a glass substrate, or a substrate other than a semiconductor substrate can be used.

[0038] The lid 33 is open on the side opposite to the outer surface 55 which is the upper surface of the lid 33, and has a bottomed recess 56 in which the vibration element 60 is housed. The lid 33 is joined to the first surface 32a of the base substrate 32 via the joining member 34 on the lower surface thereof. Thus, the lid 33 forms an internal space 57 in which the vibration element 60 is housed together with the base substrate 32. In addition, the joining method of the base substrate 32 and the lid 33 can not be via the joining member 34, but a diffusion joining method or the like which utilizes diffusion of metals contained in the base substrate 32 or the lid 33 to each other can be used.

[0039] In addition, the internal space 57 is airtight, and is in a reduced pressure state, and preferably a state closer to a vacuum. Thus, viscous resistance is reduced, and the oscillation characteristics of the vibration element 60 are improved. However, the environment of the internal space 57 is not particularly limited, and can be an environment in which an inert gas such as nitrogen or argon is sealed, or can not be a reduced pressure state but an atmospheric pressure state or a pressurized state.

[0040] Next, the structure of the integrated circuit 40 will be described with reference to Figure 4

[0041] As shown in FIG. 1, the integrated circuit 40 of the present embodiment has an oscillation circuit 41, a frequency multiplication circuit 42, an output circuit 43, a temperature compensation circuit 44, a temperature control circuit 45, and a temperature sensor 46. Figure 4 The oscillation circuit 41 is electrically connected to the vibration element 60, amplifies an output signal of the vibration element 60, and feeds back the amplified signal to the vibration element 60, thereby causing the vibration element 60 to oscillate. The frequency multiplication circuit 42 frequency-multiplies a frequency signal output from the oscillation circuit 41. The output circuit 43 outputs the frequency-multiplied frequency signal to the outside from the external connection terminal 50.

[0042]

[0043] ​​The temperature compensation circuit 44 performs temperature compensation based on temperature information output from the temperature sensor 46 so that the frequency of the oscillation signal of the oscillation circuit 41 varies less than the frequency temperature characteristics of the vibration element 60 itself. Thus, excellent temperature characteristics can be exhibited. In addition, the temperature compensation circuit 44 can adjust the oscillation frequency of the oscillation circuit 41, for example, by adjusting the capacitance of a variable capacitance circuit connected to the oscillation circuit 41, or can adjust the frequency of the output signal of the oscillation circuit 41 by a PLL (Phase Locked Loop) circuit or a direct digital synthesizer circuit.

[0044] The temperature control circuit 45 is a circuit that maintains the vibration element 60 at a constant temperature by controlling the amount of current flowing through the heater 20 based on temperature information output from the temperature sensor 46. For example, the temperature control circuit 45 controls so that the required current flows through the heater 20 when the current temperature judged based on the output signal of the temperature sensor 46 is lower than a set reference temperature, and so that the current does not flow through the heater 20 when the current temperature is higher than the reference temperature.

[0045] In addition, for example, the temperature control circuit 45 can also be controlled in a manner that the amount of current flowing through the heater 20 is increased or decreased depending on the difference between the current temperature and the reference temperature. Here, the temperature sensor 46 functions as both the temperature sensor for the temperature compensation circuit 44 and the temperature sensor for the temperature control circuit 45. Thus, the number of components can be reduced, and the oscillator 30 can be downsized. However, the temperature sensor for the temperature compensation circuit 44 and the temperature sensor for the temperature control circuit 45 can be provided separately.

[0046] The temperature sensor 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.

[0047] As described above, the vibration device 1 of the present embodiment houses the vibration element 60 in the first package 31 having high thermal conductivity that is joined to the heater 20, and thus the heat of the heater 20 is transferred to the vibration element 60 by thermal radiation from the entire first package 31, and thus temperature unevenness in the vibration element 60 can be suppressed. In addition, the temperature sensor 46 is provided on the first package 31, and thus the temperature difference between the vibration element 60 and the temperature sensor 46 can be suppressed, high-precision temperature control can be performed, and the precision of the oscillation frequency output from the vibration device 1 can be improved.

[0048] Further, a conductive member 72 such as a metal bump is used in the electrical connection of the first package 31 to the heater 20, and thus the vibration device 1 can be downsized compared to the case where a wire is used.

[0049] 2. Second Embodiment

[0050] Next, referring to Figure 5 The vibration device 1a of the second embodiment will be described.

[0051] The vibration device 1a of the present embodiment is the same as the vibration device 1 of the first embodiment except for the position of the first package 31 engaged with the heater 20a. The same matters are denoted by the same reference numerals and the description thereof will be omitted, with the focus on the difference from the first embodiment.

[0052] As shown in FIG. 1, the outer surface 55 of the lid 33 of the first package 31 of the vibration device 1a is mechanically connected to the engagement surface 21a of the heater 20a via the engagement member 72a. That is, the first package 31 is fixed to the engagement surface 21a in an upside-down manner compared to the vibration device 1 of the first embodiment. In addition, the external connection terminal 50 formed on the second surface 32b of the first package 31 is electrically connected to the first connection terminal 22a formed on the engagement surface 21a of the heater 20a via the conductive lead 71a. Figure 5 By adopting such a structure, the engagement area of the first package 31 with the heater 20a can be increased, and thus the heat conductivity from the heater 20a to the first package 31 can be improved, thereby achieving the same effect as the vibration device 1 of the first embodiment.

[0053] 3. Third Embodiment

[0054] Next, referring to

[0055] The vibration device 1b of the third embodiment will be described. Figure 6 The vibration device 1b of the present embodiment differs from the vibration device 1 of the first embodiment in that a heat insulating member 80 is provided between the heater 20 and the first substrate 11 of the second package 10, and is the same as the vibration device 1 of the first embodiment except for this. The same matters are denoted by the same reference numerals and the description thereof will be omitted, with the focus on the difference from the first embodiment.

[0056] As shown in FIG. 1, the vibration device 1b is provided with the heat insulating member 80 between the heater 20 and the first substrate 11 of the second package 10. The heat insulating member 80 is fixed to the first substrate 11 via an engagement member not shown. In addition, the heater 20 is fixed to the heat insulating member 80 via an engagement member not shown.

[0057] Figure 6 By adopting such a structure, the engagement area of the first package 31 with the heater 20a can be increased, and thus the heat conductivity from the heater 20a to the first package 31 can be improved, thereby achieving the same effect as the vibration device 1 of the first embodiment.

[0058] ​The heat insulation component 80 is made of a material with a lower thermal conductivity than the second encapsulation 10. There are no particular limitations on such a heat insulation component 80; for example, various resin materials can be preferably used, particularly porous resin materials such as porous polyimide. Besides resin materials, various glass materials, inorganic porous materials such as silica aerogel, etc., can also be used. Furthermore, the thermal conductivity of the heat insulation component 80 is not particularly limited, but is preferably 1.0 W / m·K or less. Thus, it becomes a heat insulation component 80 with sufficiently low thermal conductivity.

[0059] In addition, the insulation component 80 may also contain a gap material with sufficiently low thermal conductivity, such as silicone. This allows for control of the thickness of the insulation component 80, resulting in a more reliable insulation effect.

[0060] By adopting this structure, the heat transfer from the heater 20 to the second package 10 can be effectively suppressed, thereby achieving the same effect as the vibration device 1 in the first embodiment.

[0061] 4. Fourth Implementation Method

[0062] Next, refer to Figure 7 The vibration device 1c of the fourth embodiment will be described.

[0063] The vibration device 1c of this embodiment is the same as the vibration device 1 of the first embodiment, except that the mounting method of the heater 20 on the second package 10c is different. In addition, the description focuses on the differences from the first embodiment, and the same reference numerals are used for the same items and their descriptions are omitted.

[0064] like Figure 7 As shown, the heater 20c of the vibrating device 1c is fixed to the second package 10c via a conductive component 72c such as a metal bump. More specifically, the second connection terminal 23c formed on the surface 21b opposite to the mating surface 21a of the heater 20c and the third connection terminal 14c formed on the first substrate 11 of the second package 10c are mechanically and electrically connected via the conductive component 72c.

[0065] By adopting this structure, wire bonding is not used in the electrical connection between the heater 20c and the second package 10c. Therefore, miniaturization of the vibration device 1c can be achieved, and the same effect as the vibration device 1 of the first embodiment can be obtained.

Claims

1. A vibration device, comprising: a vibration element; a first package that houses the vibration element; a heater that is joined to the first package; and a second package that houses the first package and the heater, wherein the first package includes: a base substrate that is a semiconductor substrate, has a first surface on which the vibration element is disposed and a second surface that is in an opposite relationship to the first surface, and includes a single crystal silicon; an integrated circuit that is formed on the first surface, includes a temperature sensor and an oscillation circuit; an external connection terminal that is disposed on the second surface; and a cap that is joined to the base substrate in a manner that houses the vibration element together with the base substrate, wherein the vibration element is mounted on a side of the integrated circuit that is opposite to the first surface side, the heater has a first connection terminal on a joining surface that joins the first package, the external connection terminal is electrically connected to the first connection terminal via a conductive lead, and an outer surface of the cap and the joining surface of the heater are mechanically connected via a joining member.

2. The vibration device according to claim 1, wherein the cap is composed of a silicon substrate.

3. The vibration device according to claim 1 or 2, wherein the heater is fixed to the second package, and a thermal conductivity of the first package is higher than a thermal conductivity of the second package.

4. The vibration device according to claim 1, wherein the heater further has a second connection terminal on a surface that is opposite to the joining surface, the second package has a third connection terminal, and the second connection terminal and the third connection terminal are mechanically and electrically connected via a conductive member.

5. The vibration device according to claim 1 or 2, wherein the heater is fixed to the second package via a heat insulating member. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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