Oscillator

Abstract

To provide an oscillator capable of reducing a temperature difference between a vibration element and a circuit element.SOLUTION: An oscillator includes a package including an accommodation space, a resonator element bonded to the package via a first bonding member, a temperature sensitive element flip-chip mounted on the package via a second bonding member, a circuit element including an oscillation circuit and a temperature compensation circuit, and a third bonding member bonding the resonator element and the circuit element to each other, and the circuit element is located between the second bonding member and the resonator element. The resonator element includes a resonator substrate having a first surface located on the circuit element side and a second surface having a front-back relationship with the first surface, a first excitation electrode disposed on the first surface, a second excitation electrode disposed on the second surface and disposed so as to be opposed to the first excitation electrode via the resonator substrate, and a conductor pattern disposed on the first surface and disposed around the first excitation electrode, and the conductor pattern is coupled to the first bonding member and the third bonding member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an oscillator. [Background technology]

[0002] The crystal oscillator described in Patent Document 1 has a package including a base with a recessed portion opening on its top surface and a lid bonded to the top surface of the base to seal the opening of the recessed portion. The recessed portion has a first recessed portion opening on the top surface of the base and a second recessed portion opening on the bottom surface of the first recessed portion. The crystal oscillator further includes a piezoelectric diaphragm bonded to the bottom surface of the first recessed portion and an integrated circuit element bonded to the bottom surface of the second recessed portion. The integrated circuit element is bonded to the bottom surface of the second recessed portion using face-down bonding technology, with its wiring surface facing the bottom surface of the second recessed portion. The piezoelectric diaphragm is bonded at its base end to the bottom surface of the first recessed portion using a conductive resin adhesive and at its tip end to the back surface of the integrated circuit element using a silicone-based resin adhesive. By bonding the tip end of the piezoelectric diaphragm to the integrated circuit element in this way, the gap dimension between the piezoelectric diaphragm and the integrated circuit element can be reliably maintained as designed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-142946 Summary of the Invention [Problem to be solved by the invention]

[0004] Although not specifically mentioned in Patent Document 1, if the oscillator is a TCXO (temperature-compensated crystal oscillator), bonding the piezoelectric diaphragm and the integrated circuit element with a silicone-based resin adhesive can be expected to reduce the temperature difference between the piezoelectric diaphragm and the integrated circuit element through heat exchange between the piezoelectric diaphragm and the integrated circuit element via the silicone-based resin adhesive. However, in the oscillator of Patent Document 1, the portions of the piezoelectric diaphragm where no electrodes are formed are bonded to the integrated circuit element, resulting in poor heat exchange efficiency between the piezoelectric diaphragm and the integrated circuit element. As a result, the effect of reducing the temperature difference between the piezoelectric diaphragm and the integrated circuit element cannot be fully achieved, and there is room for improvement. [Means for solving the problem]

[0005] The oscillator of the present invention comprises: a package having an accommodating space; a vibration element joined to the package via a first joining member in the accommodation space; a circuit element that is disposed in the accommodating space and flip-chip mounted to the package via a second bonding member, the circuit element including a temperature sensing element, an oscillation circuit that oscillates the vibration element to generate an oscillation signal, and a temperature compensation circuit that compensates for the frequency temperature characteristics of the oscillation signal based on a signal from the temperature sensing element; a third bonding member bonding the vibration element and the circuit element together, the circuit element is located between the second bonding member and the vibration element, The vibration element has a vibration substrate having a first surface located on the circuit element side and a second surface opposite the first surface, a first excitation electrode arranged on the first surface, a second excitation electrode arranged on the second surface and facing the first excitation electrode via the vibration substrate, and a conductor pattern arranged on the first surface and surrounding the first excitation electrode, and the conductor pattern is connected to the first joining member and the third joining member. [Brief explanation of the drawings]

[0006] [Figure 1]1 is a cross-sectional view showing an oscillator according to a first embodiment. [Figure 2] FIG. [Figure 3] FIG. 2 is a perspective view showing the bottom surface of the vibration element. [Figure 4] FIG. 10 is a perspective view showing a modified example of the vibration element. [Figure 5] 3 is a top view showing a state in which a vibration element is bonded to a base substrate and a circuit element. FIG. [Figure 6] FIG. 10 is a cross-sectional view of an oscillator according to a second embodiment. [Figure 7] FIG. 11 is a top view of a circuit element included in an oscillator according to a third embodiment. [Figure 8] FIG. 8 is a cross-sectional view taken along line AA in FIG. [Figure 9] FIG. 10 is a cross-sectional view showing a modified example of the oscillator. [Figure 10] FIG. 10 is a cross-sectional view of an oscillator according to a fourth embodiment. [Figure 11] FIG. 2 is a cross-sectional view of a vibration element. [Figure 12] FIG. 2 is a top view of a device layer included in the vibration element. [Figure 13] FIG. 2 is a perspective view showing the lower surface of a device layer of the vibration element. [Figure 14] FIG. 2 is a perspective view showing the lower surface of a lower lid layer of the vibration element. DETAILED DESCRIPTION OF THE INVENTION

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the oscillator of the present invention will now be described in detail with reference to the accompanying drawings.

[0008] First Embodiment Fig. 1 is a cross-sectional view showing an oscillator according to a first embodiment. Fig. 2 is a top view of a vibration element. Fig. 3 is a perspective view showing the bottom surface of the vibration element. Fig. 4 is a perspective view showing a modified example of the vibration element. Fig. 5 is a top view showing the bonding state of the vibration element, the base substrate, and the circuit element.

[0009] For ease of explanation, FIGS. 1 to 5 illustrate an X-axis, a Y-axis, and a Z-axis that are perpendicular to each other. For ease of explanation, the direction along the X-axis will be referred to as the X-axis direction, the direction along the Y-axis as the Y-axis direction, and the direction along the Z-axis as the Z-axis direction. The arrowed side of each axis will be referred to as the "plus side," and the opposite side as the "minus side." The arrowed side of the Z-axis, which is the thickness direction of oscillator 1, will be referred to as the "upper" side, and the opposite side as the "lower" side.

[0010] The oscillator 1 shown in FIG. 1 is a TCXO (temperature compensated crystal oscillator), and has a package 2 having an accommodation space S, and a resonator element 5 and a circuit element 6 accommodated in the accommodation space S of the package 2.

[0011] The package 2 has a base substrate 3. The base substrate 3 is made of ceramics such as alumina. The base substrate 3 has an upper surface and a lower surface, which are opposite sides of the base substrate 3. The base substrate 3 also has a recess 31 with a bottom that opens on the upper surface. The recess 31 is made up of multiple recesses, and has a first recess 311 that opens on the upper surface, and a second recess 312 that opens on the bottom of the first recess 311 and has a smaller opening than the first recess 311.

[0012] Furthermore, a pair of internal terminals 321 are arranged on the bottom surface of the first recess 311, a plurality of internal terminals 322 are arranged on the bottom surface of the second recess 312, and a plurality of external terminals 323 are arranged on the lower surface of the base substrate 3. Each of the internal terminals 321 and each of the external terminals 323 is electrically connected to the corresponding internal terminal 322 via internal wiring (not shown) formed in the base substrate 3.

[0013] The vibration element 5 is bonded to the bottom surface of the first recess 311 via a first bonding member B1 and is electrically connected to each of the internal terminals 321, while the circuit element 6 is bonded to the bottom surface of the second recess 312 via a second bonding member B2 and is electrically connected to each of the internal terminals 322. The vibration element 5 is located above the circuit element 6, i.e., on the positive side in the Z-axis direction. In other words, the circuit element 6 is disposed between the second bonding member B2 and the vibration element 5. In addition, in a plan view from the Z-axis direction, the tip end (the end on the positive side in the X-axis direction) of the vibration element 5 overlaps with the circuit element 6, and the base end (the end on the negative side in the X-axis direction) located opposite the tip end overlaps with the bottom surface of the first recess 311 without overlapping with the circuit element 6.

[0014] The package 2 also has a lid 4. The lid 4 is made of a metal material such as Kovar. The lid 4 is bonded to the upper surface of the base substrate 3 via a bonding member and closes the opening of the recess 31. By closing the opening of the recess 31 with the lid 4 in this way, an airtight storage space S is formed inside the package 2. The resonator element 5 and the circuit element 6 are then housed in the storage space S. The storage space S is in a reduced pressure state, preferably a state closer to a vacuum. This reduces the CI (crystal impedance) value of the resonator element 5 and improves the oscillation characteristics. However, the atmosphere of the storage space S is not particularly limited.

[0015] 1, the circuit element 6 has a semiconductor substrate 60 having a wiring surface 6a as its lower surface and a back surface 6b as its upper surface opposite to the wiring surface 6a. A plurality of various circuit elements (not shown) for configuring the necessary circuits are formed on the wiring surface 6a. A wiring layer 600 is formed on the wiring surface 6a to electrically connect the circuit elements to each other so that predetermined functions are performed. Furthermore, a plurality of connection terminals 69 are arranged on the wiring layer 600 to electrically connect the circuit element 6 to the internal terminals 322.

[0016] The circuit element 6 configured as above is flip-chip mounted on the bottom surface of the second recess 312. Specifically, the circuit element 6 is bonded to the bottom surface of the second recess 312 via a plurality of conductive second bonding members B2, with the wiring surface 6a facing downward, i.e., toward the bottom surface of the second recess 312. Furthermore, each connection terminal 69 is electrically connected to a corresponding internal terminal 322 via the second bonding members B2. The second bonding members B2 are various metal balls such as gold balls and copper balls. However, the configuration of the second bonding members B2 is not particularly limited as long as it is capable of flip-chip mounting.

[0017] The circuit element 6 also has a temperature sensing element 61, an oscillation circuit 62, and a temperature compensation circuit 63 arranged on the wiring surface 6a side. The temperature sensing element 61 is formed on the wiring surface 6a, and the oscillation circuit 62 and the temperature compensation circuit 63 are formed by electrically connecting the circuit elements formed on the wiring surface 6a via the wiring layer 600.

[0018] The temperature-sensing element 61 is, for example, a resistor (thin-film thermistor) whose resistance value changes according to temperature, and can detect temperature from the magnitude of the resistance value. The oscillation circuit 62 is electrically connected to the vibration element 5, amplifies the output signal of the vibration element 5, and feeds back the amplified signal to the vibration element 5, causing the vibration element 5 to oscillate and generate an oscillation signal. The temperature compensation circuit 63 compensates for the frequency-temperature characteristics of the oscillation signal generated by the oscillation circuit 62 based on the temperature detected by the temperature-sensing element 61. In other words, temperature compensation is performed so that the frequency fluctuation of the oscillation signal is smaller than the frequency-temperature characteristics of the vibration element 5 itself. With this configuration, frequency fluctuation of the oscillation signal due to temperature changes is suppressed, resulting in oscillator 1 with excellent oscillation characteristics.

[0019] The oscillator circuit 62 may be, for example, a Pierce oscillator circuit, an inverter oscillator circuit, a Colpitts oscillator circuit, a Hartley oscillator circuit, etc. The temperature compensation circuit 63 may be, for example, a circuit that adjusts the oscillation frequency of the oscillator circuit 62 by adjusting the capacitance of a variable capacitance circuit connected to the oscillator circuit 62, or a circuit that adjusts the frequency of the oscillation signal generated by the oscillator circuit 62 using a PLL circuit or a direct digital synthesizer circuit.

[0020] 1, the circuit element 6 has an insulating film 68 disposed on the rear surface 6b and a first electrode pad 67 disposed on the insulating film 68. By disposing the first electrode pad 67 on the insulating film 68 in this manner, it is possible to easily insulate the first electrode pad 67 from the rear surface 6b, which is the ground surface. The insulating film 68 is not particularly limited, but can be, for example, a silicon oxide film formed by thermal oxidation, sputtering, or the like.

[0021] Furthermore, the first electrode pad 67 overlaps the tip of the vibration element 5 in plan view from the Z-axis direction. The first electrode pad 67 also overlaps the temperature-sensitive element 61 in plan view from the Z-axis direction. The circuit element 6 also has a first via 66 that penetrates the wiring surface 6a and the back surface 6b and thermally connects the first electrode pad 67 and the temperature-sensitive element 61. Although not shown, an insulating film is formed between the first via 66 and the semiconductor substrate 60, insulating them from each other.

[0022] The first electrode pads 67 and the first vias 66 are made of a material having a thermal conductivity higher than at least the constituent material of the semiconductor substrate 60. In this embodiment, the first electrode pads 67 and the first vias 66 are made of a conductive material, specifically, various metal materials such as gold (Au), copper (Cu), and aluminum (Al). This results in the first electrode pads 67 and the first vias 66 having high thermal conductivity. However, the constituent materials of the first electrode pads 67 and the first vias 66 are not particularly limited. Furthermore, since the first electrode pads 67 and the first vias 66 are not used for electrical connection, they may be made of an insulating material.

[0023] The vibration element 5 is an AT-cut quartz crystal vibration element. AT-cut quartz crystal vibration elements have third-order frequency-temperature characteristics, resulting in excellent frequency stability. As shown in Figures 2 and 3, the vibration element 5 has a rectangular plate-shaped vibration substrate 51 cut out from quartz crystal using an AT cut method, and having a bottom surface 51a as a first surface and a top surface 51b as a second surface, which are opposite sides of the vibration substrate 51, and electrodes and conductor patterns 55 arranged on the surface of the vibration substrate 51.

[0024] The electrodes include a first excitation electrode 521 arranged on the lower surface 51a of the vibrating substrate 51, and a second excitation electrode 531 arranged on the upper surface 51b of the vibrating substrate 51 and facing the first excitation electrode 521 across the vibrating substrate 51. The electrodes also include a first connection terminal 522 and a second connection terminal 532 arranged side by side in the Y-axis direction at the base end of the lower surface of the vibrating substrate 51, a first escape wiring 523 electrically connecting the first excitation electrode 521 and the first connection terminal 522, and a second escape wiring 533 electrically connecting the second excitation electrode 531 and the second connection terminal 532.

[0025] The conductor pattern 55 is not in contact with the electrodes and is insulated from the electrodes. The conductor pattern 55 has a thermal conductivity that is significantly higher than that of the vibration substrate 51. The conductor pattern 55 is disposed along the edge of the lower surface 51a of the vibration substrate 51. Specifically, the conductor pattern 55 is U-shaped and disposed so as to surround three sides of the first excitation electrode 521 excluding the base end side, that is, both sides in the Y-axis direction and the positive side in the X-axis direction. Such a conductor pattern 55 is formed collectively with the electrodes, for example, by patterning a metal film formed on the vibration substrate 51 by etching or the like.

[0026] However, the configuration of the vibration element 5 is not particularly limited. For example, the shape of the conductor pattern 55 is not particularly limited, and may be an L-shape surrounding two sides (the positive side in the X-axis direction and the negative side in the Y-axis direction) of the first excitation electrode 521, as shown in FIG. 4. The conductor pattern 55 and the electrodes may be made of different materials. For example, the planar shape of the vibration substrate 51 is not limited to a rectangle, and may be a circle. As the vibration element 5, in addition to an AT-cut quartz crystal vibration element, an SC-cut quartz crystal vibration element, a BT-cut quartz crystal vibration element, or a tuning fork-type quartz crystal vibration element may also be used. Furthermore, a surface acoustic wave resonator, other piezoelectric vibration elements, piezoelectric vibration elements made of piezoelectric materials other than a quartz crystal vibration element, a MEMS (Micro Electro Mechanical Systems) resonator element, etc. may also be used.

[0027] As shown in FIG. 5 , the vibration element 5 has a base end (the end on the negative side in the X-axis direction) joined to the bottom surface of the first recess 311 via four conductive first bonding members B1. The first connection terminal 522 is electrically connected to one of the internal terminals 321 via one first bonding member B1, and the second connection terminal 532 is electrically connected to the other internal terminal 321 via one first bonding member B1. This electrically connects the vibration element 5 and the circuit element 6 via the base substrate 3. Furthermore, the remaining two first bonding members B1 connect both ends of the conductor pattern 55 to the bottom surface of the first recess 311. This thermally connects the conductor pattern 55 to the base substrate 3 via the two first bonding members B1, allowing heat from the base substrate 3 to be efficiently transferred to the conductor pattern 55.

[0028] The first bonding member B1 is a conductive resin adhesive. In particular, in this embodiment, an epoxy-based conductive adhesive is used, in which a metal filler such as Ag (silver) filler is dispersed in an epoxy-based resin. This results in the first bonding member B1 having sufficiently high thermal conductivity. Furthermore, compared to, for example, a metal bump, the first bonding member B1 is softer, and can effectively absorb and relieve stress generated between the vibration element 5 and the base substrate 3. However, the configuration of the first bonding member B1 is not particularly limited. Furthermore, of the four first bonding members B1, the two first bonding members B1 that bond the conductor pattern 55 to the bottom surface of the first recess 311 may be made of an insulating material because they are not used for electrical connection.

[0029] 1 and 5, the oscillator 1 further includes a third bonding member B3 located between the tip of the vibration element 5 and the circuit element 6 and bonding them together. With this configuration, both ends of the vibration element 5 are fixed, stabilizing the posture of the vibration element 5 and effectively suppressing fluctuations in the oscillation characteristics of the vibration element 5. However, the bonding location of the third bonding member B3 is not limited to the tip of the vibration element 5.

[0030] The third bonding member B3 has an upper end that contacts the center of the conductor pattern 55 arranged on the lower surface 51a of the vibration substrate 51, that is, the portion located at the tip of the vibration element 5, and is not in contact with the electrodes on the vibration substrate 51. The third bonding member B3 has a lower end that contacts the first electrode pad 67 of the circuit element 6.

[0031] The third bonding member B3 is electrically conductive. This ensures that the third bonding member B3 has sufficiently high thermal conductivity. The third bonding member B3 is made of a conductive resin adhesive. In particular, in this embodiment, similar to the first bonding member B1, an epoxy-based conductive adhesive is used, in which a metal filler such as Ag (silver) filler is dispersed in an epoxy resin. This makes the third bonding member B3 softer than, for example, a metal bump, and can effectively absorb and alleviate stress generated between the vibration element 5 and the circuit element 6. However, the configuration of the third bonding member B3 is not particularly limited. Furthermore, since the third bonding member B3 is not used for electrical connection, it may be made of an insulating material.

[0032] As described above, in the oscillator 1, the conductor pattern 55 is connected to the first bonding member B1 and the third bonding member B3. Therefore, heat from the base substrate 3 is efficiently transferred to the vibration element 5 via the first bonding member B1, and further, the heat is efficiently transferred to the circuit element 6 via the third bonding member B3. This reduces the temperature difference between the vibration element 5 and the circuit element 6, particularly the temperature difference between the vibration element 5 and the temperature sensing element 61. As a result, the error between the actual temperature of the vibration element 5 and the compensation temperature (the temperature detected by the temperature sensing element 61) used in the temperature compensation circuit 63 is reduced, thereby improving the temperature compensation accuracy. This results in a highly accurate oscillator 1.

[0033] In particular, in this embodiment, a conductive resin adhesive is used for the first and third bonding members B1 and B3. The conductive resin adhesive spreads and is crushed during bonding, increasing its diameter. For example, the diameter of the first and third bonding members B1 and B3 is approximately 200 μm, whereas if metal bumps were used, the diameter would be approximately 50 μm. Therefore, by using a conductive resin adhesive for the first and third bonding members B3, more heat can be transferred per unit time to the vibration element 5 and the circuit element 6. This reduces the temperature difference between the vibration element 5 and the temperature-sensing element 61.

[0034] Furthermore, in this embodiment, the vibration element 5 and the temperature sensitive element 61 are thermally connected via the third bonding member B3, the first electrode pad 67, and the first via 66. This further reduces the temperature difference between the vibration element 5 and the temperature sensitive element 61, allowing temperature compensation by the temperature compensation circuit 63 to be performed more accurately. In particular, in this embodiment, the center of the conductor pattern 55, the first electrode pad 67, the first via 66, and the temperature sensitive element 61 overlap with each other in a plan view from the Z-axis direction. This effectively minimizes the heat path between the vibration element 5 and the temperature sensitive element 61, further reducing the temperature difference between the vibration element 5 and the temperature sensitive element 61.

[0035] The above has described the oscillator 1. As described above, such oscillator 1 includes a package 2 having an accommodation space S, a vibration element 5 bonded to the package 2 within the accommodation space S via a first bonding member B1, a circuit element 6 disposed within the accommodation space S and flip-chip mounted to the package 2 via a second bonding member B2, the circuit element 6 including a temperature sensitive element 61, an oscillation circuit 62 that oscillates the vibration element 5 to generate an oscillation signal, and a temperature compensation circuit 63 that compensates for the frequency-temperature characteristics of the oscillation signal based on a signal from the temperature sensitive element 61, and a third bonding member B3 that bonds the vibration element 5 and the circuit element 6. The circuit element 6 is located between the second bonding member B2 and the vibration element 5. The vibration element 5 includes a vibration substrate 51 having a lower surface 51a, which is a first surface located on the circuit element 6 side, and an upper surface 51b, which is a second surface opposite to the lower surface 51a, a first excitation electrode 521 disposed on the lower surface 51a, a second excitation electrode 531 disposed on the upper surface 51b and facing the first excitation electrode 521 across the vibration substrate 51, and a conductor pattern 55 disposed on the lower surface 51a and surrounding the first excitation electrode 521, the conductor pattern 55 being connected to the first bonding member B1 and the third bonding member B3. This configuration allows heat from the base substrate 3 to be efficiently transferred to the circuit element 6 via the conductor pattern 55. This allows the temperature difference between the vibration element 5 and the thermosensitive element 61 to be kept small, resulting in an oscillator 1 that can perform temperature compensation by the temperature compensation circuit 63 with greater accuracy.

[0036] As described above, the vibration element 5 is joined at its base end to the package 2 via the first bonding member B1, and at its tip end opposite the base end to the circuit element 6 via the third bonding member B3. The conductor pattern 55 is U-shaped, surrounding the first excitation electrode 521 on three sides except for the base end, and is joined at both ends to the package 2 via the first bonding member B1, and at its center to the circuit element 6 via the third bonding member B3. With this configuration, heat from the base substrate 3 is efficiently transferred to the circuit element 6 via the conductor pattern 55. As a result, the temperature difference between the vibration element 5 and the temperature sensing element 61 can be further reduced.

[0037] As described above, the circuit element 6 includes a semiconductor substrate 60 having a wiring surface 6a on the second bonding member B2 side and on which the temperature-sensing element 61 is disposed, and a back surface 6b opposite the wiring surface 6a and located on the vibration element 5 side, and a first electrode pad 67 disposed on the back surface 6b of the semiconductor substrate 60 and connected to the conductor pattern 55 via the third bonding member B3. The semiconductor substrate 60 also includes a first via 66 that penetrates the wiring surface 6a and the back surface 6b and connects the temperature-sensing element 61 and the first electrode pad 67. With this configuration, the vibration element 5 and the temperature-sensing element 61 are thermally connected via the third bonding member B3, the first electrode pad 67, and the first via 66. This further reduces the temperature difference between the vibration element 5 and the temperature-sensing element 61.

[0038] As described above, the third bonding member B3 is electrically conductive. This configuration provides the third bonding member B3 with sufficiently high thermal conductivity. This reduces the temperature difference between the vibration element 5 and the temperature sensing element 61.

[0039] Second Embodiment FIG. 6 is a cross-sectional view of the oscillator according to the second embodiment.

[0040] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except for the configuration of the circuit element 6. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in the drawings of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0041] 6, in the oscillator 1 of this embodiment, the insulating film 68, the first electrode pad 67, and the first via 66 are omitted from the circuit element 6. The third joint member B3 is joined to the rear surface 6b. Because the rear surface 6b is the ground surface, the conductor pattern 55 is connected to the ground potential of the circuit element 6 via the third joint member B3. Therefore, the potential of the conductor pattern 55 is stabilized.

[0042] As described above, in the oscillator 1 of this embodiment, the conductor pattern 55 is connected to the ground potential of the circuit element 6. With this configuration, the potential of the conductor pattern 55 is stabilized.

[0043] The second embodiment can also achieve the same effects as the first embodiment described above.

[0044] <Third embodiment> Fig. 7 is a top view of a circuit element included in an oscillator according to a third embodiment, Fig. 8 is a cross-sectional view taken along line AA in Fig. 7, and Fig. 9 is a cross-sectional view showing a modified example of the oscillator.

[0045] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except that the orientation of the vibration element 5 is different. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in each drawing of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0046] 7, in the oscillator 1 of this embodiment, the vibration element 5 is rotated 180° around the Z axis relative to the first embodiment described above, that is, the tip end faces the negative side of the X axis direction and the base end faces the positive side of the X axis direction. In plan view from the Z axis direction, the base end of the vibration element 5 overlaps with the circuit element 6, and the tip end overlaps with the bottom surface of the first recess 311. The tip end of such a vibration element 5 is bonded to the bottom surface of the first recess 311 via one first bonding member B1, and the base end is bonded to the top surface of the circuit element 6 via four third bonding members B3.

[0047] 8, the circuit element 6 has a pair of second electrode pads 65 arranged on the insulating film 68. By arranging the pair of second electrode pads 65 on the insulating film 68 in this way, each second electrode pad 65 can be easily insulated from the rear surface 6b, which is the ground surface.

[0048] In addition, in a plan view from the Z-axis direction, the pair of second electrode pads 65 overlap the base ends of the vibration elements 5 and are arranged side by side in the Y-axis direction. The circuit element 6 also has a pair of second vias 64 that penetrate the wiring surface 6a and the back surface 6b and electrically connect each second electrode pad 65 to the oscillation circuit 62. Although not shown, an insulating film is formed between the second vias 64 and the semiconductor substrate 60, insulating them from each other. The second electrode pads 65 and the second vias 64, like the first electrode pads 67 and the first vias 66, are made of various metal materials such as gold (Au), copper (Cu), aluminum (Al), etc.

[0049] As shown in FIG. 8 , the vibrating element 5 is bonded at its base end (the end on the positive side in the X-axis direction) to the upper surface of the circuit element 6 via four conductive third bonding members B3. The first connection terminal 522 is electrically connected to one of the second electrode pads 65 via one third bonding member B3, and the second connection terminal 532 is electrically connected to the other of the second electrode pads 65 via one third bonding member B3. This electrically connects the vibrating element 5 and the oscillation circuit 62 via the third bonding member B3. This configuration shortens the electrical path between the vibrating element 5 and the oscillation circuit 62 compared to, for example, the first embodiment, in which the vibrating element 5 and the oscillation circuit 62 are electrically connected via the base substrate 3. This reduces parasitic capacitance accordingly. This oscillator 1 is therefore suitable for increasing the frequency of oscillation signals.

[0050] Furthermore, both ends of the conductive pattern 55 are thermally connected to the circuit element 6 via the remaining two third joint members B3. In particular, one of these third joint members B3 is in contact with the first electrode pad 67, thermally connecting the conductive pattern 55 and the temperature sensing element 61.

[0051] As shown in FIG. 7 , the vibration element 5 is bonded at its tip (the end on the negative side in the X-axis direction) to the bottom surface of the first recess 311 via a single conductive first bonding member B1. The internal terminal 321 is omitted from the base substrate 3 of this embodiment. The center of the conductor pattern 55 is thermally connected to the base substrate 3 via the first bonding member B1. This configuration efficiently transfers heat from the base substrate 3 to the vibration element 5 via the first bonding member B1, and then efficiently transfers the heat to the circuit element 6 via the third bonding member B3. This reduces the temperature difference between the vibration element 5 and the circuit element 6. This reduces the error between the actual temperature of the vibration element 5 and the compensation temperature (the temperature detected by the temperature-sensing element 61) used in the temperature compensation circuit 63, thereby improving the temperature compensation accuracy. This results in a highly accurate oscillator 1.

[0052] As described above, in the oscillator 1 of this embodiment, the vibration element 5 is joined at its base end to the circuit element 6 via the third bonding member B3, and at its tip end opposite the base end to the package 2 via the first bonding member B1. The conductor pattern 55 is U-shaped, surrounding the first excitation electrode 521 on three sides except for the base end, and is joined at both ends to the circuit element 6 via the third bonding member B3, and at its center to the package 2 via the first bonding member B1. With this configuration, heat from the base substrate 3 is efficiently transferred to the circuit element 6 via the conductor pattern 55. As a result, the temperature difference between the vibration element 5 and the temperature sensing element 61 can be further reduced.

[0053] As described above, the circuit element 6 includes a semiconductor substrate 60 having a wiring surface 6a on the second bonding member B2 side and on which the temperature-sensing element 61 is disposed, a back surface 6b opposite the wiring surface 6a and located on the vibration element 5 side, and a second electrode pad 65 disposed on the back surface 6b side of the semiconductor substrate 60. The semiconductor substrate 60 also includes a second via 64 that penetrates the wiring surface 6a and the back surface 6b and electrically connects the oscillation circuit 62 disposed on the wiring surface 6a side to the second electrode pad 65. With this configuration, the electrical path between the vibration element 5 and the oscillation circuit 62 can be shortened, and parasitic capacitance can be reduced accordingly, compared to the configuration in which the vibration element 5 and the circuit element 6 are electrically connected via the base substrate 3, as in the first embodiment described above. This configuration therefore provides an oscillator 1 suitable for increasing the frequency of the oscillation signal.

[0054] As described above, the first bonding member B1 is electrically conductive. This configuration provides the first bonding member B1 with sufficiently high thermal conductivity. This allows the heat of the base substrate 3 to be efficiently transferred to the vibration element 5, thereby further reducing the temperature difference between the vibration element 5 and the temperature sensing element 61.

[0055] The third embodiment can also achieve the same effects as the first embodiment described above.

[0056] However, the present invention is not limited to this, and for example, as shown in FIG. 9, the first electrode pad 67 and the first via 66 may be omitted.

[0057] <Fourth embodiment> Fig. 10 is a cross-sectional view of an oscillator according to a fourth embodiment. Fig. 11 is a cross-sectional view of a vibration element. Fig. 12 is a top view of a device layer 71 included in the vibration element. Fig. 13 is a perspective view showing the bottom surface of the device layer included in the vibration element. Fig. 14 is a perspective view showing the bottom surface of a lower lid layer included in the vibration element.

[0058] The oscillator 1 according to this embodiment is similar to the oscillator 1 of the first embodiment described above, except that it uses a vibration element 7 instead of the vibration element 5. Therefore, in the following description, differences between the oscillator 1 of this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in each drawing of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0059] As shown in Fig. 10, the oscillator 1 of this embodiment has a vibrating element 7 housed in a package 2. As shown in Fig. 11, the vibrating element 7 has a device layer 71, and a lower lid layer 72 and an upper lid layer 73 that sandwich the device layer 71 from above and below. These three layers 71, 72, and 73 are each made of an AT-cut quartz crystal substrate.

[0060] 12 and 13, the device layer 71 has a rectangular frame portion 711, a vibration substrate 712 arranged inside the frame portion 711, and three connection portions 713 that connect the frame portion 711 and the vibration substrate 712. A first excitation electrode 751 and a U-shaped conductor pattern 77 that surrounds the first excitation electrode 751 are formed on the lower surface, which is the first surface, of the vibration substrate 712, and a second excitation electrode 761 that is arranged opposite the first excitation electrode 751 is formed on the upper surface, which is the second surface.

[0061] 11, the lower lid layer 72 is bonded to the lower surface of the frame portion 711. The lower lid layer 72 has an opening on its upper surface and a recess 721 for avoiding contact with the vibration substrate 712. As shown in FIG. 14, a first electrode pad 752, a second electrode pad 762, and three third electrode pads 772 are formed on the lower surface of the lower lid layer 72. The first excitation electrode 751 is led to the frame portion 711 through a connection portion 713 and is then electrically connected to the first electrode pad 752 by a via (not shown). The second excitation electrode 761 is led to the frame portion 711 through the connection portion 713 and is then electrically connected to the second electrode pad 762 by a via (not shown). Both end portions and a central portion of the conductor pattern 55 are led to the frame portion 711 through the connection portion 713 and are then electrically connected to the third electrode pad 772 by a via (not shown).

[0062] 11, the upper lid layer 73 is bonded to the upper surface of the frame portion 711. The upper lid layer 73 has an opening on its upper surface and a recess 731 for avoiding contact with the vibration substrate 712.

[0063] The inside of the vibration element 7 is in a reduced pressure state, preferably a state closer to a vacuum. This reduces the CI (crystal impedance) value of the vibration element 7, improving the oscillation characteristics. However, the atmosphere of the accommodation space S is not particularly limited.

[0064] The vibration element 7 is bonded to the bottom surface of the first recess 311 at the base end of the lower lid layer 72 via four first bonding members B1. The first electrode pad 752 is electrically connected to one of the internal terminals 321 via one first bonding member B1, and the second electrode pad 762 is electrically connected to the other internal terminal 321 via one first bonding member B1. Furthermore, both ends of the conductor pattern 55 are thermally connected to the base substrate 3 by the remaining two first bonding members B1. The vibration element 7 is bonded to the first electrode pad 67, which is disposed on the upper surface of the circuit element 6, at the tip end of the lower lid layer 72 via a third bonding member B3. The center of the conductor pattern 55 is thermally connected to the temperature-sensitive element 61 by the third bonding member B3.

[0065] In the oscillator 1 of the first embodiment described above, the oscillation characteristics of the vibrating element 5 cannot be inspected until the vibrating element 5 and the circuit element 6 are mounted on the base substrate 3, and if the vibrating element 5 does not pass the inspection, not only the vibrating element 5 but also the circuit element 6 and the base substrate 3 are wasted. In contrast, according to the oscillator 1 of this embodiment, the vibration characteristics of the vibrating element 7 can be inspected before the vibrating element 7 and the circuit element 6 are mounted on the base substrate 3. Therefore, only non-defective products that pass the inspection can be bonded to the base substrate 3. Therefore, the package 2 and the circuit element 6 are less likely to be wasted, and the manufacturing cost of the oscillator 1 can be reduced and the yield can be improved.

[0066] The fourth embodiment can also achieve the same effects as the first embodiment.

[0067] Although the oscillator of the present invention has been described above based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part can be replaced with any configuration having a similar function. Also, other arbitrary components may be added to the present invention. Furthermore, the above-described embodiments may be combined as appropriate. [Explanation of symbols]

[0068] 1...oscillator, 2...package, 3...base substrate, 31...recess, 311...first recess, 312...second recess, 321...internal terminal, 322...internal terminal, 323...external terminal, 324...internal terminal, 4...lid, 5...vibration element, 51...vibration substrate, 51a...bottom surface, 51b...top surface, 521...first excitation electrode, 522...first connection terminal, 523...first lead-out wiring, 531...second excitation electrode, 532...second connection terminal, 533...second lead-out wiring, 55...conductor pattern, 6...circuit element, 6a...wiring surface, 6b...back surface, 60...semiconductor substrate, 600...wiring layer, 61...thermosensitive element, 62...oscillation Circuit, 63...temperature compensation circuit, 64...second via, 65...second electrode pad, 66...first via, 67...first electrode pad, 68...insulating film, 69...connection terminal, 7...vibration element, 71...device layer, 711...frame portion, 712...vibration substrate, 713...connection portion, 72...lower lid layer, 721...recess, 73...upper lid layer, 731...recess, 751...first excitation electrode, 752...first electrode pad, 761...second excitation electrode, 762...second electrode pad, 77...conductor pattern, 772...third electrode pad, B1...first bonding member, B2...second bonding member, B3...third bonding member, S...accommodation space

Claims

1. a package having a storage space; a vibration element joined to the package via a first joining member in the accommodation space; a circuit element disposed in the accommodation space and flip-chip mounted to the package via a second bonding member, the circuit element including a temperature sensing element, an oscillation circuit that oscillates the vibration element to generate an oscillation signal, and a temperature compensation circuit that compensates for the frequency temperature characteristics of the oscillation signal based on a signal from the temperature sensing element; a third bonding member bonding the vibration element and the circuit element together, the circuit element is located between the second bonding member and the vibration element, The oscillator is characterized in that the vibration element has a vibration substrate having a first surface located on the circuit element side and a second surface that is opposite to the first surface, a first excitation electrode arranged on the first surface, a second excitation electrode arranged on the second surface and arranged opposite the first excitation electrode via the vibration substrate, and a conductor pattern arranged on the first surface and arranged around the first excitation electrode, and the conductor pattern is connected to the first bonding member and the third bonding member.

2. the vibration element is joined to the package at a base end portion via the first bonding member, and is joined to the circuit element at a tip end portion located opposite to the base end portion via the third bonding member, 2. The oscillator according to claim 1, wherein the conductor pattern is U-shaped and surrounds the first excitation electrode on three sides except for the base end side, and is joined to the package at both ends via the first joining member and to the circuit element at a center via the third joining member.

3. the circuit element is located on the second bonding member side, and the semiconductor substrate has a wiring surface on which the temperature-sensing element is arranged, and a back surface opposite to the wiring surface and located on the vibration element side; a first electrode pad disposed on the rear surface side of the semiconductor substrate and connected to the conductor pattern via the third bonding member; The oscillator according to claim 2 , wherein the semiconductor substrate has a first via that penetrates the wiring surface and the back surface and connects the temperature sensing element and the first electrode pad.

4. The oscillator according to claim 3 , wherein the third joining member is electrically conductive.

5. the vibration element is joined to the circuit element at a base end portion via the third bonding member, and is joined to the package at a tip end portion located opposite to the base end portion via the first bonding member, 2. The oscillator according to claim 1, wherein the conductor pattern is U-shaped and surrounds the first excitation electrode on three sides except for the base end side, and is joined to the circuit element at both ends via the third joining member and to the package at a center via the first joining member.

6. the circuit element is located on the second bonding member side, and the semiconductor substrate has a wiring surface on which the temperature-sensing element is arranged, and a back surface opposite to the wiring surface and located on the vibration element side; a second electrode pad disposed on the rear surface side of the semiconductor substrate, 6. The oscillator according to claim 5, wherein the semiconductor substrate has a second via that penetrates the wiring surface and the back surface and electrically connects the oscillation circuit arranged on the wiring surface side to the second electrode pad.

7. The oscillator according to claim 6 , wherein the first joining member is electrically conductive.

8. 2. The oscillator according to claim 1, wherein the conductor pattern is connected to the ground potential of the circuit element.

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