JP4218672B2 - Piezoelectric resonator, piezoelectric filter, communication device - Google Patents

Description

  The present invention relates to a piezoelectric resonator, a piezoelectric filter, and a piezoelectric filter that are used in a filter, an oscillator, a communication device, and the like and can exhibit a filter function by vibrating in thickness and longitudinal in a VHF band, a UHF band, and a higher frequency band. The present invention relates to a duplexer using communication and a communication device.

  In recent years, a filter used in a high frequency (RF, particularly GHz band or higher) stage of a communication device such as a mobile phone has been developed using a piezoelectric resonator having excellent characteristics. Each of the above characteristics is small and lightweight, excellent in vibration resistance and shock resistance, low product variation and high reliability, and it is possible to automate and simplify mounting because circuit adjustment is not required. In addition, even if the frequency is increased, the manufacturing is easy.

  The piezoelectric resonator includes a substrate having an opening or a recess, a diaphragm made of an insulating thin film formed on the opening or the recess of the substrate, and one or more piezoelectric layers formed on the insulating thin film. The thing of the structure which has the vibration part of the structure which sandwiches the upper and lower surfaces of the thin film part which has a thin film at least with a pair of upper electrode and lower electrode facing each other is mentioned (for example, refer patent document 1). In such a piezoelectric resonator, since the piezoelectric body of the piezoelectric resonator is made into a thin film, the high frequency limit can be extended to several hundred MHz to several thousand MHz.

In such a piezoelectric resonator, it is necessary to limit the electrode dimensions within a predetermined range in order to reduce unnecessary vibration. In addition, in order to confine the vibration energy in the vibration part, it is necessary to make the electrode dimensions smaller than the diaphragm dimensions. For this reason, when a large amount of electric power is applied, the electric power is concentrated on the vibrating portion having a small size, and relatively large heat is generated in the vibrating portion.
Japanese Patent Laid-Open No. 2001-168673, date of publication, June 22, 2001

  However, in the above-described conventional case, the diaphragm forming the vibration part is thin and has a small heat capacity, so that the generated heat is difficult to dissipate, and most of the heat is accumulated in the vibration part, leading to an increase in temperature of the vibration part. . The rise in temperature of the vibration part may affect the destruction of the vibration part, which causes a problem that the operation stability deteriorates.

In order to solve the above problems, a piezoelectric resonator according to the present invention is provided on a substrate having an opening or a recess and a thin film portion having one or more piezoelectric thin films formed on the opening or the recess. In a piezoelectric resonator having a vibrating portion having a structure in which at least a pair of upper and lower electrodes are sandwiched between the lower surface, the shape of the vibrating portion as viewed in the thickness direction is a polygon having sides with different lengths, and At least the longest side of the vibration part is formed along the end of the opening or recess in the piezoelectric thin film, and the distance between the end and the point of the vibration part farthest from the end, The longest side of the vibrating part is long .

According to the above configuration, at least the longest side of the vibration part that is a polygon having sides with different lengths as viewed in the thickness direction of the vibration part, along the end of the opening or the recess , and the end Since the length of the longest side of the vibration part is longer than the distance between the part and the point of the vibration part farthest from the end, the heat dissipation of the vibration part can be improved and a large amount of power can be generated. Even if it adds, degradation of a resonance characteristic can be avoided and operational stability can be improved.

  In the piezoelectric resonator, it is preferable that the distance between the longest side of the vibration part and the end of the opening or the recess is about ½ times the vibration wavelength of the vibration part.

  In the piezoelectric resonator, all the sides of the vibrating part are formed along the end of the opening or the recess, and the distance between all the sides of the vibrating part and the end of the opening or the recess is vibrated. It may be about ½ times the vibration wavelength of the part.

  In the piezoelectric resonator, the sum W of the lengths of all sides formed along the end of the opening or the recess of the vibration unit and the point farthest from the end of the opening or the recess of the vibration unit It is desirable that the distance L between the opening and the recess satisfies L / W ≦ 0.8.

  In the piezoelectric resonator, the shape of the vibrating portion as viewed in the thickness direction may be an isosceles triangle. In the piezoelectric resonator, the piezoelectric thin film may contain ZnO or AlN as a main component.

  In order to solve the above problems, a piezoelectric filter of the present invention is characterized by having the piezoelectric resonator described in any of the above. In the piezoelectric filter, it is preferable that the piezoelectric resonator has a ladder configuration.

  In order to solve the above problems, a duplexer of the present invention is characterized by having the piezoelectric resonator described in any of the above. In order to solve the above problems, a communication device of the present invention is characterized by having the piezoelectric resonator described in any of the above.

  The above-described piezoelectric filter, duplexer, and communication device have a piezoelectric resonator that has excellent heat dissipation and improved operational stability, so that operation over time can be stabilized and durability can be improved.

  As described above, the piezoelectric resonator of the present invention has at least a pair of upper and lower electrodes facing the upper and lower surfaces of a thin film portion having one or more piezoelectric thin films formed on an opening or a recess. In the piezoelectric resonator having the sandwiching vibration part, the shape of the vibration part as viewed in the thickness direction is a polygon having sides having different lengths, and at least the longest side of the vibration part is an opening or a recess. It is the structure formed along the edge part.

  According to the above configuration, at least the longest side of the vibrating part, which is a polygon having sides with different lengths as viewed in the thickness direction of the vibrating part, is formed along the end of the opening or the recess. It is possible to improve the heat dissipation of the part, to avoid deterioration of the resonance characteristics even when a large amount of power is applied, and to improve the operational stability.

  Each embodiment of the present invention will be described with reference to FIGS. 1 to 17 as follows.

[First embodiment]
The piezoelectric resonator according to the first embodiment of the present invention will be described with reference to its manufacturing method. As shown in FIGS. 1 and 2, the surface orientation is made of silicon having a plane orientation of (1 0 0). Silicon dioxide (SiO ₂ ) films 11 and 12 are formed on both surfaces of the support substrate 10 by thermal oxidation or sputtering, respectively.

Subsequently, the SiO ₂ film 12 on one surface (back surface) side, (1 1 0) direction to form a rectangular window 12a having parallel sides, the SiO ₂ film 12 having the window 12a as a mask Etching is performed on silicon of the support substrate 10 at about 90 ° C. in a TMAH solution (tetramethylammonium aqueous solution).

  Since this TMAH liquid has a large crystal orientation dependence of the etch rate, the (1 1 1) plane forms an angle of about 55 ° with the (1 0 0) plane 10b which is the surface direction of the support substrate 10 as the etching progresses. 10a appears, and an opening that penetrates the support substrate 10 in the thickness direction is formed.

The etching stops when it reaches the SiO ₂ film 11 on the surface side. Since the etching completely stops at the SiO ₂ film 11 in this way, a smooth (smooth) resonator surface can be obtained, and the thickness of the entire resonator can be set more accurately. In the first embodiment, the SiO ₂ film 12 remaining in the manufacturing stage is finally removed, but may be left.

At this time, an alumina (Al ₂ O ₃ ) film or an aluminum nitride (AlN) film is further formed on the SiO ₂ film 11 opposite to the support substrate 10 by vacuum deposition or sputtering to form two or more layers. It is good also as a laminated body. Therefore, the diaphragm 11a faces the opening (cavity) of the support substrate 10 formed by the (1 1 1) surface 10a.

In the diaphragm 11a, the SiO ₂ film 11 generally has a positive resonance frequency temperature characteristic and generates compressive stress, while the Al ₂ O ₃ film generally has a negative resonance frequency temperature characteristic. In addition, tensile stress is generated. The insulator forming such a diaphragm 11a is preferably one having high thermal conductivity in order to improve heat dissipation.

  Subsequently, a lower electrode 14 made of Al, a piezoelectric thin film 15 made of zinc oxide (ZnO), aluminum nitride (AlN), etc., and an upper electrode 16 made of Al are sequentially deposited on the diaphragm 11a by vacuum deposition or sputtering and etching. Form. The piezoelectric thin film 15 has negative resonance frequency temperature characteristics and generates compressive stress.

  The lower electrode 14 is formed in a band shape, and the longitudinal direction of the lower electrode 14 is formed such that the longitudinal end portion of the support substrate 10 is a base portion 14a and the central portion of the diaphragm 11a is a distal end portion 14b.

  Further, in the lower electrode 14, wings extending in the width direction of the lower electrode 14 from both side portions so as to cover a part of the opening 11 a located on both sides of the lower electrode 14 and a peripheral portion of the part. 14c is formed. Therefore, it can be said that the lower electrode 14 has a substantially cross shape on the diaphragm 11a and in the vicinity of the periphery thereof.

  On the other hand, the upper electrode 16 is formed in a strip shape, and the longitudinal direction of the upper electrode 16 is opposite to the base portion 14a of the lower electrode 14. The longitudinal end portions of the support substrate 10 are the base portion 16a and the base portion 16a. And a distal end portion 16b that reaches the center of the diaphragm 11a.

  Further, the tip portion 16 b of the upper electrode 16 faces the tip portion 14 b of the lower electrode 14, and covers a part of the opening 11 a located on both sides of the upper electrode 16 and a part of the periphery thereof. Further, they are formed so as to extend in the width direction of the upper electrode 16 from the both side portions, respectively. Therefore, it can be said that the upper electrode 16 is substantially T-shaped on the diaphragm 11a and in the vicinity of the periphery thereof.

  Further, both the wing portions 14 c of the lower electrode 14 and the tip portion 16 b of the upper electrode 16 are arranged at positions that do not face each other with the piezoelectric thin film 15 interposed therebetween. With such an arrangement, it is possible to improve the strength of the vibration part while avoiding unnecessary vibrations other than the vibration part 11b.

In such a piezoelectric resonator, when the resonance frequency is 2 GHz, the total thickness of the SiO ₂ film 11, the lower electrode 14, the piezoelectric thin film 15, and the upper electrode 16 can be set to about 3 μm.

In the piezoelectric resonator, the thickness of the SiO ₂ film 11, the area of the lower electrode 14, the thickness of the piezoelectric thin film 15, and the area of the upper electrode 16 are set according to the vibration mode (for example, secondary mode). . In addition, by using a multilayer structure in which an Al ₂ O ₃ film is further formed on the SiO ₂ film 11, it is easy to set the temperature coefficient (ppm / ° C.) of the resonance frequency to almost zero in the piezoelectric resonator. Can be

  In addition, in the piezoelectric resonator, the lower electrode 14, the piezoelectric thin film 15, and the upper electrode 16 are preferably set so that the piezoelectric thin film resonator is an energy confinement type. As a result, it is possible to prevent vibration energy from leaking along the diaphragm into the support substrate 10 and to generate resonance with a high Q.

As described above, since the thickness of the SiO ₂ film 11 as the insulating film (support film) can be very thin, the piezoelectric resonator has a basic or low-order (for example, secondary) overtone and a high frequency of 100 MHz or more. An operating piezoelectric resonator can be realized. Furthermore, in the piezoelectric resonator, since the temperature characteristics and internal stress of each film can be set to cancel each other, adverse effects due to temperature changes and internal stress can be avoided.

  In addition, the piezoelectric resonator can have a very small diaphragm size of several hundred μm or less, and can be incorporated in a semiconductor integrated circuit. Further, the piezoelectric resonator does not require sub-micron patterning like a surface acoustic wave device (SAW device) even at several GHz, and can be easily and easily manufactured.

  In the piezoelectric resonator of the present invention, the heat radiating film 18 is, for example, Si-shaped so as to cover the opening 11a on the piezoelectric thin film 15 and the upper electrode 16 except on the vibrating portion 11b. It is formed with the insulator. Therefore, the heat radiating film 18 is formed with a window portion 18 a for removing the vibration portion 11 b on the substantially central portion of the heat radiating film 18.

  In the above configuration, by providing the heat dissipation film 18, the heat dissipation from the vibrating portion 11 b to the support substrate 10 can be improved, the power durability can be improved, and the operational stability over time can be increased.

  The heat radiating film 18 is not limited to the Si, but may be an insulator such as AlN or diamond, a metal film such as Cu, A1, Au or Ag, or Cu, Al, Au or Ag as a main component. And an electrical conductor such as an alloy.

  The heat dissipating body 18 desirably has a high thermal conductivity from the viewpoint of improving the heat dissipating property, but may have any thermal conductivity of 150 W / (m · K) or more. The thermal conductivity (unit: W / (m · K)) of each material described above is Si = 168, AlN = 150, diamond = 1600, Cu = 403, Al = 236, Au = 319, Ag = 428. . The optimum material for the heat dissipation film 18 is diamond because its thermal conductivity is significantly higher than that of other substances from the viewpoint of thermal conductivity alone, but considering the ease of manufacturing and cost, Cu, Al and Si are preferred.

  However, when a metal film such as Cu or Al is used for the heat dissipation film 18 and the heat dissipation film 18 is in electrical contact with the lower electrode 14 and the upper electrode 16, a short circuit between the lower electrode 14 and the upper electrode 16 is prevented. In order to avoid this, the heat dissipation film 18 in contact with the lower electrode 14 and the heat dissipation film 18 in contact with the upper electrode 16 are formed apart from each other.

  Further, as shown in FIG. 3, the narrower (smaller) gap is better as the gap between the vibration part 11b and the heat radiation film 18 is. However, in order to prevent the adverse effect on the vibration of the vibration part 11b, the vibration wavelength (λ ) Is preferably set to about 1/2. The gap is a distance in the surface direction of each of the films 14, 15, and 16 forming the vibration part 11 b between the inner peripheral part of the window part 18 a of the heat radiation film 18 and the outer edge part of the vibration part 11 b.

  In FIG. 3, the temperature when the gap is 0 μm is T0, the temperature when each gap is provided is T, and the smaller the T / T0, the higher the heat dissipation. 3 to 6 show examples in which Si is used as the material of the heat dissipation film 18.

  Furthermore, as shown in FIG. 4, it is preferable that the pattern width of the heat dissipation film 18 is set to be wide and large so that the heat dissipation film 18 covers the entire diaphragm 11a as much as possible. In FIG. 4, the time when the heat dissipation film 18 just covers the entire diaphragm 11a is described as solid, and the temperature is T0. The temperature when the pattern width of the heat dissipation film is smaller than that of solid is T, and the smaller T / T0 is, the higher the heat dissipation is.

  In addition, as shown in FIG. 5, since the heat dissipation performance deteriorates when the heat dissipation film 18 does not protrude outward from the diaphragm 11a in the surface direction, the diaphragm is considered in consideration of manufacturing variations when the heat dissipation film 18 is formed. It is preferable to set so as to protrude outward from the surface direction from 11a. In FIG. 5, the vertical (Y) axis indicates the heat generation temperature ratio, and the reference indicates the temperature when the amount of protrusion is 0 μm.

  Further, as shown in FIG. 6, the thickness of the heat dissipation film 18 is preferably as thick as possible in terms of heat dissipation. However, even if it is thicker than 5 μm, the heat dissipation effect is saturated and the heat dissipation effect is not improved much. First, when Si is used for the heat dissipation film 18, the thickness is preferably 1 or more, more preferably 2 to 5 μm. In FIG. 6, the vertical (Y) axis indicates the heat generation temperature ratio, and the reference indicates the temperature (T0) when the film thickness is 0 μm.

  As shown in FIGS. 7A to 7C, the piezoelectric resonator 1 according to the present invention may be used for a piezoelectric filter according to the present invention having an L-type, π-type, or T-type ladder configuration. Furthermore, it can be suitably used for a modified example in which the number of stages is increased.

  In the piezoelectric filter having the ladder configuration, a pass band formed between the anti-resonance frequency and the resonance frequency of each piezoelectric resonator 1 serving as an attenuation pole can be made highly selective. Therefore, the ladder-structured piezoelectric filter is provided with a stop region having a steep attenuation characteristic including each attenuation pole on both sides of the pass region. In addition, it withstands heat generation during continuous use, and the stability over time is improved.

  Such a piezoelectric filter of the present invention can be used for a duplexer 20 as shown in FIG. The duplexer 20 is provided with a transmission-side piezoelectric filter and a reception-side piezoelectric filter, the transmission-side and reception-side passbands are close to each other, have steep attenuation characteristics, and thermal stability. In addition, the piezoelectric filter of the present invention, which is excellent, is also preferably used.

  In the first embodiment, an example in which an opening that penetrates the support substrate 10 in the thickness direction is provided. However, the present invention is not limited to the above, and instead of the opening, as shown in FIG. Alternatively, the support substrate 10 may be provided with a recess 10c that does not penetrate the support substrate 10 in the thickness direction, and the diaphragm 11a may be formed on the recess 10c.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. In each of the following embodiments, members having the same functions as those in the first embodiment are assigned the same member numbers and are not described.

In the piezoelectric resonator according to the second embodiment, as shown in FIGS. 10 and 11, the difference from the first embodiment is that the heat radiating film 18 is omitted (can be used in combination as described later), The shape of the diaphragm or the vibration part is a long and thin shape, for example, an isosceles triangle (including a polygonal deformation) in the diaphragm 11c and the vibration part 11d, and the longitudinal direction of the vibration part 11d. One of the long sides extending along the line is set along the edge of the diaphragm 11c.

  In the shape of the vibration part 11d, the long sides W1 and W2 are preferably 20 times or more of the vibration wavelength (λ) of the vibration part 11d, and the short side W3 is preferably 5 times or less of the vibration wavelength (λ). In such a configuration, as will be described later, the thermal resistance between the vibrating portion 11d and the support substrate 10 can be reduced, that is, the heat dissipation can be improved.

  At this time, the diaphragm 11c has a distance between the edge facing the vibration part 11d and the vibration part 11d in order to avoid the influence on the vibration of the vibration part 11d (for example, the vibration wavelength (λ of the vibration part 11d) About 1/2 of the above) is desirable. Such a shape of the vibrating portion 11d is possible by forming the lower electrode 14 in a trapezoidal plate shape, making the upper electrode 16 a substantially parallelogram shape, and adjusting the facing position between the lower electrode 14 and the upper electrode 16. .

  Thus, in the above configuration, by forming the shape of the diaphragm 11c along the shape of the vibration part 11d, the length (W1 + W2 + W3) of the vibration part 11d adjacent to the edge of the diaphragm 11c is increased, and heat dissipation is improved. it can. Moreover, by making the vibration part 11d have a long and narrow shape, the distance L of the heat transfer path is shortened, and heat dissipation is facilitated. Furthermore, if the shape of the vibrating part 11d is long and thin, it is possible to reduce spurious vibrations of the piezoelectric resonator, and thus it is possible to achieve both improvement in characteristics due to spurious reduction and improvement in heat dissipation.

  In another piezoelectric filter of the present invention, the above-described piezoelectric resonator is arranged in two elements in an L-type ladder structure shown in FIG. At this time, it is desirable in terms of miniaturization that the vibrating portions 11d of the piezoelectric resonators are arranged so that their longitudinal directions are substantially parallel to each other. Furthermore, it is preferable from the viewpoint of miniaturization that each vibration part 11d of each piezoelectric resonator is point-symmetric with respect to the center position of an imaginary line connecting the centers thereof.

Next, the theory of heat conduction will be described. The amount of heat Q transmitted from the A surface to the B surface of the individual shown in FIG. 12 is expressed by the following equation.
Q = λ · W · t · (TA−TB) / L (1)
λ: Thermal conductivity W: Width of heat transfer path cross section t: Heat transfer path cross section thickness TA: Temperature of surface A (K)
TB: B surface temperature (K)
L: Thermal resistance R indicating the difficulty of heat transfer through the heat transfer path is expressed by the following equation.
R = L / (λ · W · t) (2)
From this equation (2), it can be seen that the larger the λ · W · t and the smaller the L, the larger the heat dissipation amount Q (the smaller the thermal resistance). In the second embodiment, λ: the thermal conductivity of the diaphragm, W: W1 + W2 + W3 in FIG. 10, t: the thickness of the diaphragm, L: L shown in FIG. 10 (the center of the shape in the thickness direction in the vibrating part 11d) And the distance from the edge of the diaphragm 11c).

Further, from equation (1), λ = Q · L / {W · t · (TA−TB)}, and the unit of lambda is λ = W · m / (m ² · K) = W / (m · K).

  In the second embodiment, the distance between the longest side of the vibration part 11d and the edge of the diaphragm 11c is zero at the lower limit, ideally 1 / 2λ that can avoid the vibration inhibition of the vibration part 11d. However, the upper limit value is a design target value, and actually there are variations in the manufacturing process. It is necessary to add a process margin to the upper limit.

  The reason for setting the distance is as follows. From the viewpoint of heat dissipation, the distance between the longest side of the vibration part 11d and the edge of the diaphragm 11c should be as short as possible (zero is ideal). However, when the distance is set to zero, the vibration of the vibration part 11d is affected and the characteristics are deteriorated. From the viewpoint of characteristics, it is better that the distance between the longest side of the vibration part 11d and the edge of the diaphragm 11c is increased to some extent. (The relationship between characteristics and heat dissipation is a trade-off) The distance at which the characteristics are not affected is 1 / 2λ.

  The ideal distance between the longest side of the vibration part 11d and the edge of the diaphragm 11c is 1 / 2λ in consideration of both heat dissipation and vibration characteristics. The distance is significantly different from the set value. Therefore, “about” 1 / 2λ. For reference, the process margin is about 35 μm for wet etching and about 20 μm for dry etching.

For example, the condition is 1.9 GHz band, double wave, film configuration “upper electrode (Al: 0.18 μm) / ZnO film (1.6 μm) as piezoelectric thin film / lower electrode (Al: 0.18 μm) / AlN In the case of “film (1.8 μm) / SiO ₂ film (0.6 μm)”, λ = 4.3 μm, 35 μm = 8.1λ, and 20 μm = 4.7λ. That is, there is a margin of 35 μm = 8.1λ and 20 μm = 4.7λ with respect to the ideal 1 / 2λ = 2.15 μm. The vibration wavelength λ varies depending on the frequency band, the film configuration, the material used, the order of the vibration wave to be used (fundamental wave, second harmonic wave, etc.), and the like. On the other hand, the process margin is constant regardless of the frequency. (However, the margin changes as the processing method changes.) As the frequency band increases, the shift increases.

  The amplitude of leakage / vibration becomes smaller as the vibration wavelength becomes 1 / 2λ away. If the fixed end (the edge of the diaphragm 11c) is placed at a distance of 1 / 2λ from the vibration portion, the influence on the vibration is small, and the deterioration of the characteristics is also small. Further, if the vibration part 11d is too far away from the edge (fixed end) of the diaphragm 11c, the other vibration part 11d, etc., the heat dissipation is deteriorated, and even if the influence on the vibration characteristic is reduced or eliminated, the dimension is large. Turn into.

  With such a configuration, sufficient heat dissipation can be obtained, but in combination with this, heat is radiated on the piezoelectric thin film 15 and the upper electrode 16 excluding the vibrating portion 11d as in the first embodiment. A film may be formed, which further improves heat dissipation.

[Third embodiment]
In the third embodiment, as shown in FIGS. 13 and 14, a piezoelectric filter having an L-type ladder structure including two piezoelectric resonators is formed on one diaphragm 11e formed in a rectangular shape when viewed in the thickness direction. Has been. At this time, the vibration part 11f is formed in an isosceles triangle like the second embodiment, and is arranged so that one long side of the vibration part 11f is along the edge of the diaphragm 11e. .

  Thereby, in the piezoelectric resonator and the piezoelectric filter of the third embodiment, the same effect as in the second embodiment is obtained, and the area of the entire element is compared with the case where a diaphragm is formed for each piezoelectric resonator. Can be reduced, and downsizing can be achieved.

  Next, the relationship between the L / W ratio (L / W) and the heat generation temperature (temperature ratio) shown in FIG. 13 was examined. The results are shown in FIG. The L corresponds to the height of the vibration part 11f with the long side of the vibration part 11f facing the diaphragm 11e as the bottom, that is, the distance between the point farthest from the edge of the diaphragm 11e and the edge in the vibration part 11f. To do. Said W is the length of the long side of the vibration part 11f which faces the diaphragm 11e. In the graph of the temperature ratio and L / W in FIG. 15, the ratio to the temperature at this time is defined as the temperature ratio with reference to the case where L / W is 1.19 (a shape close to an equilateral triangle).

  As can be seen from FIG. 15, the smaller the L / W is, the lower the temperature is. When L / W is 0.8 or less, the exothermic temperature decreases greatly.

[Fourth embodiment]
In the fourth embodiment, as shown in FIGS. 16 and 17, one diaphragm 11g is provided in the same manner as in the third embodiment, and the third embodiment is shown on the diaphragm 11g. Each vibration part 11h corresponding to each of the two vibration parts 11f is formed, and the diaphragm 11g is formed along each side facing outward of each vibration part 11h.

  Therefore, in the fourth embodiment, as in the second and third embodiments, it is possible to reduce the size while improving the heat dissipation.

[Fifth embodiment]
In the fifth embodiment, as shown in FIG. 18, two diaphragms 11e similar to those in the third embodiment are provided side by side on the support substrate 10, and the third embodiment described above is provided on these diaphragms 11e. Each of the two vibrating portions 11f, that is, two piezoelectric resonators shown in the form is formed. The diaphragms 11e are formed side by side along a direction substantially perpendicular to the longitudinal direction of the vibrating portions 11f.

  Thus, in the fifth embodiment, since each of the four vibrating portions 11f is used to connect the piezoelectric resonators 1a and 1b and the piezoelectric resonators 1c and 1d in series with each other, the L-type ladder A piezoelectric filter is formed by stacking two stages of piezoelectric filters.

  In the fifth embodiment, the piezoelectric resonator 1a is provided with the lower electrode 14a serving as an input terminal, and the piezoelectric resonators 1a, 1b, and 1c are provided with the upper electrode 16a serving as a common terminal. A lower electrode 14b serving as a GND terminal of the child 1b is formed. Further, a lower electrode 14c serving as an output terminal is provided at a common terminal of the piezoelectric resonators 1c and 1d, and an upper electrode 16b serving as a GND terminal of the piezoelectric resonator 1d is formed.

  Therefore, in the fifth embodiment, as in the second to fourth embodiments, it is possible to reduce the size while improving the heat dissipation.

  The piezoelectric resonators according to the first to fifth embodiments and the piezoelectric filter using the same can be suitably used for the duplexer 20 shown in FIG. In the above description, the first embodiment of the present invention and the second to fifth embodiments of the present invention have been described individually. However, the first embodiment of the present invention and the second to fifth embodiments of the present embodiment are described. Each may be combined.

  Next, a communication device using the piezoelectric resonator and the piezoelectric filter of the present invention will be described with reference to FIG. 19. As shown in FIG. 19, the communication device 200 has an antenna as a receiver side (Rx side) for receiving. 201, antenna sharing unit / RFTop filter 202, amplifier 203, Rx interstage filter 204, mixer 205, 1stIF filter 206, mixer 207, 2ndIF filter 208, 1st + 2nd local synthesizer 211, TCXO (temperature compensated crystal oscillator) )) 212, a divider 213, and a local filter 214. It is preferable to transmit from the Rx interstage filter 204 to the mixer 205 by each balanced signal in order to ensure balance, as shown by the double line in FIG.

  In addition, the communication device 200 shares the antenna 201 and the antenna sharing unit / RFTop filter 202 as a transceiver side (Tx side) that performs transmission, and also includes a TxIF filter 221, a mixer 222, a Tx interstage filter 223, and an amplifier. 224, a coupler 225, an isolator 226, and an APC (automatic power control) 227.

  Further, the above-described antenna sharing unit / RFTop filter 202, Rx interstage filter 204, 1stIF filter 206, TxIF filter 221, and Tx interstage filter 223 include the piezoelectric resonance described in the first to fifth embodiments. A child or a piezoelectric filter can be preferably used.

  In order to solve the above problems, a piezoelectric resonator according to the present invention is provided on a substrate having an opening or a recess and a thin film portion having one or more piezoelectric thin films formed on the opening or the recess. In a piezoelectric resonator having a lower surface sandwiching at least a pair of upper electrode and lower electrode, and at a position excluding the vibrating portion and on at least one of the upper electrode and the thin film portion The heat dissipation film is formed.

  According to the above configuration, by providing the heat dissipation film, unnecessary vibration of the piezoelectric resonator can be reduced, and at the same time, heat dissipation and power durability can be improved so that deterioration of the resonance characteristics can be avoided even when large power is applied. , Can improve the operational stability.

  In the piezoelectric resonator, the heat dissipation film preferably has a thermal conductivity of about 150 W / (m · K) or more.

  In the piezoelectric resonator, the heat dissipation film may be made of an insulating material such as Si, AlN, or diamond.

  In the piezoelectric resonator, the heat dissipation film may be made of a metal material such as Cu, A1, Au, or Ag, or an alloy containing Cu, Al, Au, or Ag as a main component.

  In the piezoelectric resonator, it is preferable that a distance between the heat dissipation film and the vibration part is about ½ times a vibration wavelength of the vibration part.

  In the piezoelectric resonator, the opening or the entire recess may be covered with the heat dissipation film except for the vibrating portion.

  In the piezoelectric resonator, it is preferable that the periphery of the opening or the recess is covered with the heat dissipation film.

  In the piezoelectric resonator, the shape of the vibrating portion as viewed in the thickness direction is a polygon having sides with different lengths, and at least the longest side of the vibrating portion is formed along the end of the opening or the recess. It is preferable.

In the above piezoelectric resonator, the length of the longest side of the vibrating portion, and a point farthest from said end of the opening or recess in the vibrating section, longer desirable than the distance between said end portion .

  In the piezoelectric resonator, it is preferable that the distance between the longest side of the vibration part and the end of the opening or the recess is about ½ times the vibration wavelength of the vibration part.

  In the piezoelectric resonator, all the sides of the vibrating part are formed along the end of the opening or the recess, and the distance between all the sides of the vibrating part and the end of the opening or the recess vibrates. It may be about ½ times the vibration wavelength of the part.

  In the piezoelectric resonator, the sum W of the lengths of all sides formed along the end of the opening or the recess of the vibration unit and the point farthest from the end of the opening or the recess of the vibration unit It is desirable that the distance L between the opening and the recess satisfies L / W ≦ 0.8.

  In the piezoelectric resonator, it is preferable that the shape of the vibrating portion viewed in the thickness direction is 20 times or more the vibration wavelength of the vibration portion in the longitudinal direction and 5 times or less the vibration wavelength in the short direction.

  In the piezoelectric resonator, the shape of the vibrating portion as viewed in the thickness direction may be an isosceles triangle.

  As described above, the piezoelectric resonator of the present invention is a piezoelectric resonator having a vibrating portion, an upper electrode, and a lower electrode of a thin film portion having one or more piezoelectric thin films formed on an opening or a recess. The heat dissipation film is formed at a position excluding the vibration part and on at least one of the upper electrode and the thin film part.

  Therefore, the above configuration improves heat dissipation and power durability so that unnecessary vibration of the piezoelectric resonator can be reduced by providing a heat dissipation film, and at the same time, deterioration of resonance characteristics can be avoided even when large power is applied. And the operational stability can be improved.

1 is a plan view showing a piezoelectric resonator according to a first embodiment of the present invention. It is A-A 'arrow sectional drawing of the said piezoelectric resonator. It is a graph which shows the relationship between the gap of a vibration part and a thermal radiation film, and heat dissipation in the said piezoelectric resonator. It is a graph which shows the relationship between the heat dissipation film width | variety in the said piezoelectric resonator, and heat dissipation. It is a graph which shows the relationship between the protrusion amount from a diaphragm, and heat dissipation in the said piezoelectric resonator. It is a graph which shows the relationship between the thermal radiation film thickness in the said piezoelectric resonator, and heat dissipation. It is a circuit block diagram which shows the example which applied the said piezoelectric resonator to the ladder-type piezoelectric filter, (a) is an L-type ladder, (b) is a (pi) -type ladder, (c) shows a T-type ladder. It is a block diagram of the duplexer using the said piezoelectric filter. It is sectional drawing which shows one modification of the said piezoelectric resonator. It is a top view which shows the piezoelectric resonator and piezoelectric filter of 2nd Embodiment which concern on this invention. It is B-B 'arrow sectional drawing of the said piezoelectric resonator and a piezoelectric filter. FIG. 3 is a perspective view of a rectangular parallelepiped solid for explaining heat conduction in the piezoelectric resonator and the piezoelectric filter. It is a top view which shows the piezoelectric resonator and piezoelectric filter of 3rd Embodiment which concern on this invention. It is sectional drawing of the said piezoelectric resonator and a piezoelectric filter. It is a graph which shows the relationship between L / W of the said piezoelectric resonator and a piezoelectric filter, and heat dissipation. It is a top view which shows the piezoelectric resonator and piezoelectric filter of 4th Embodiment which concern on this invention. It is sectional drawing of the said piezoelectric resonator and a piezoelectric filter. The piezoelectric filter of Embodiment 5 which concerns on this invention is shown, (a) is a circuit block diagram, (b) is a top view, (c) is DD 'arrow cross section of said (b). FIG. It is a circuit block diagram of the communication apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Support substrate 11b Vibrating part 14 Lower electrode 15 Piezoelectric thin film 16 Upper electrode 18 Heat dissipation film

Claims (10)

A structure having a substrate having an opening or a recess and an upper and lower surfaces of a thin film portion having one or more piezoelectric thin films formed on the opening or the recess, with at least a pair of upper and lower electrodes facing each other. In a piezoelectric resonator having a vibrating part,
The shape in the thickness direction of the vibration part is a polygon having sides with different lengths, and at least the longest side of the vibration part is formed along the end of the opening or the recess in the piezoelectric thin film ,
The length of the longest side of the vibration part is longer than the distance between the end part and the point of the vibration part farthest from the end part . 2. The piezoelectric resonator according to claim 1 , wherein a distance between a longest side of the vibration part and an end of the opening or the recess is about ½ times a vibration wavelength of the vibration part. All the sides of the vibrating part are formed along the end of the opening or the recess, and the distance between all the sides of the vibrating part and the end of the opening or the recess is about 1 of the vibration wavelength of the vibrating part. The piezoelectric resonator according to claim 2 , wherein the piezoelectric resonator is / 2 times. A structure having a substrate having an opening or a recess and an upper and lower surfaces of a thin film portion having one or more piezoelectric thin films formed on the opening or the recess, with at least a pair of upper and lower electrodes facing each other. In a piezoelectric resonator having a vibrating part,
The shape in the thickness direction view of the vibration part is a polygon having sides with different lengths, and at least the longest side of the vibration part is formed along the end of the opening or the recess,
The sum W of the lengths of all sides formed along the end of the opening or recess of the vibration part, the point farthest from the end of the opening or recess in the vibration part, and the opening or recess The piezoelectric resonator is characterized in that the distance L between and satisfies L / W ≦ 0.8. A structure having a substrate having an opening or a recess and an upper and lower surfaces of a thin film portion having one or more piezoelectric thin films formed on the opening or the recess, with at least a pair of upper and lower electrodes facing each other. In a piezoelectric resonator having a vibrating part,
The shape in the thickness direction view of the vibration part is a polygon having sides with different lengths, and at least the longest side of the vibration part is formed along the end of the opening or the recess,
The piezoelectric resonator according to claim 1, wherein a shape of the vibrating portion as viewed in the thickness direction is an isosceles triangle. The piezoelectric resonator according to any one of claims 1 to 5, wherein the piezoelectric thin film is mainly composed of ZnO or AlN. Piezoelectric filter characterized by using a piezoelectric resonator according to any one of claims 1 to 6. A piezoelectric filter comprising the piezoelectric resonator according to any one of claims 1 to 6 in a ladder configuration. Duplexer characterized by using a piezoelectric resonator according to any one of claims 1 to 6. Communication apparatus characterized by having a piezoelectric resonator according to any one of claims 1 to 6.

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