JP4893602B2 - Piezoelectric vibration device and hermetic sealing method of piezoelectric vibration device - Google Patents

Description

  The present invention relates to a piezoelectric vibration device used for electronic equipment and the like, and a hermetic sealing method for the piezoelectric vibration device.

  Piezoelectric vibration devices typified by quartz resonators are widely used in mobile communication devices such as mobile phones. The surface-mount type crystal resonator is a crystal resonator having a form corresponding to the demand for low profile and space saving, and is mounted in a container body having a recess (hereinafter abbreviated as a base) and the recess. A quartz plate and a flat lid for hermetically sealing the recess are configured as main components.

  With the recent miniaturization, for example, when the vertical and horizontal dimensions of a crystal resonator are reduced to about 2.0 × 1.6 mm, it is difficult to handle the crystal resonator individually. Therefore, a substrate-like base assembly in which a plurality of bases are connected in a matrix, a quartz substrate in which a large number of crystal pieces are integrally formed, and a lid assembly in which a plurality of lids are connected in a matrix are used. A method of manufacturing a large number of crystal resonators in a batch is known. In such a manufacturing method, for example, when the lid assembly is formed of a translucent material, the laser beam is transmitted through the lid assembly and the joint between the lid and the base is locally heated. And can be airtightly joined. Such a sealing method is not handled by a large number, but is disclosed in Patent Document 1, for example.

JP 2001-326290 A

  However, in Patent Document 1, the base is formed of ceramic, and the limit of the ceramic package (ceramic base) approaches as electronic component elements become smaller. In addition, it is difficult to cope with a low profile.

  Further, for example, two aggregates of lids made of a translucent material having a concave portion, the front and back surfaces of an aggregate of crystal pieces (so-called inverted mesa shape) that are thicker at the periphery than at the center. There is a method of forming a quartz crystal vibration device by bonding to the substrate. In the case of such a configuration, the concave portions of the two lid assemblies are positioned so as to face the quartz substrate, and laser is irradiated from the outside of the lid assemblies via a bonding material (metal film). Then, the quartz substrate and the two lid aggregates are joined. At this time, the formation region of one crystal resonator will be described with reference to FIG. 5. The bonding regions (laser beam irradiation regions) on the front and back surfaces of the crystal substrate are overlapped in a plan view. Then, the laser beam is directed toward the bonding material from two directions (from above the first package substrate 2 and from the bottom of the second package substrate 4 and on the same straight line in a sectional view). By irradiation, the quartz resonator 1 is hermetically sealed. First, the upper bonding materials 201 and 301 are irradiated with a laser beam, and a part of the upper bonding materials 201 and 301 is melted to bond the first package base 2 and the quartz substrate 3. Then, the lower bonding materials 302 and 401 are irradiated with a laser beam to bond the second package base 4 and the crystal substrate 3. However, at this time, the laser beam passes through the lower bonding material (302, 401) and reaches the upper bonding material (201, 301), and enters the bonding region between the first package base material and the quartz substrate. There is a risk of defects (voids). Such a problem is that after the upper bonding material is bonded by the laser beam, the bonded body of the first package base material and the crystal substrate is turned upside down so that the second package base material is not bonded to the unbonded surface of the crystal substrate. The same applies to the case of joining. From the above, it becomes difficult to perform stable hermetic sealing.

  The present invention has been made in view of the above points, and an object thereof is to provide a piezoelectric vibration device capable of performing stable hermetic sealing and a hermetic sealing method of the piezoelectric vibration device corresponding to a reduction in height. It is what.

  In order to achieve the above object, the invention of claim 1 is directed to a piezoelectric substrate and first and second packages made of a translucent material, which are bonded to each of the front and back surfaces of the piezoelectric substrate via a metal film. A piezoelectric vibration device comprising a base material, wherein a bonding region between the first and second package base materials and the piezoelectric substrate does not overlap in a plan view. Therefore, for example, when the first and second package base materials are irradiated with an energy beam such as a laser beam or an electron beam from the outside of the piezoelectric vibration device to melt the metal film and perform hermetic sealing. Even if it exists, stable airtight sealing can be performed. That is, since the bonding area (the irradiation area of the energy beam) between the first and second package base materials and the piezoelectric substrate (for example, a translucent material such as crystal) does not overlap in a plan view, When performing hermetic sealing by irradiating a laser beam, the laser beam passes through the inside of the piezoelectric substrate and does not reach the bonding region of the opposite metal film. Accordingly, stable airtight sealing can be performed without damaging the bonding region between the two package base materials and the quartz substrate.

  Further, when a non-translucent material is used for the piezoelectric substrate, the laser beam is irradiated in two directions (from above the first package substrate and from below the second package substrate) instead of from one direction. It is also possible. Even in such a case, a stable hermetic sealing is performed by irradiating the laser beam in a state shifted on the front and back (up and down) of the piezoelectric vibration device so that the joining region of the metal film by the laser beam does not overlap in a plan view. be able to.

  In order to achieve the above object, according to the invention of claim 2, the first package base is formed with a smaller outer dimension than the second package base, and the first package base is Since it is in a state of being included in the second package base material in a plan view, highly reliable airtight sealing can be performed. For example, even when an energy beam such as a laser beam or an electron beam is irradiated from one direction of the piezoelectric device, the energy region is not overlapped in a plan view. Even if it penetrates the inside of the piezoelectric substrate and reaches the metal film, it does not damage the bonding region of the metal film that contributes to the bonding of each of the first and second package base materials to the piezoelectric substrate.

  In addition, with such a configuration, if the metal film is formed in the peripheral regions of the first and second package base materials, it is possible to form a structure in which the joining regions do not overlap in plan view. Also, a structure that does not overlap in plan view can be obtained. Therefore, it is suitable for joining the first and second package base materials and the piezoelectric substrate from one direction using an energy beam. As described above, a simpler sealing process can be realized as compared with the case where bonding is performed by irradiating an energy beam from two directions. Alternatively, after joining one package substrate and one side of the piezoelectric substrate, a method of turning the front and back (up and down) for joining the other package substrate and one side of the piezoelectric substrate is also possible. Compared with a simple method, the piezoelectric vibration device of the present invention can reduce the number of work steps in the sealing process and improve the production efficiency.

  According to the above configuration, the first and second package base materials are formed of a light-transmitting material. Specifically, by using quartz or glass and using, for example, quartz for the piezoelectric substrate, laser beams or electrons are used. The beam can be transmitted efficiently, and more accurate hermetic sealing can be performed.

  In order to achieve the above object, according to a third aspect of the present invention, there is provided a translucent piezoelectric substrate and a translucent material comprising a translucent material bonded to each of the front and back surfaces of the piezoelectric substrate via a metal film. 1 and a second package base material, wherein the first package base material is formed with a smaller outer dimension than the second package base material. In addition, the first and second package substrates are disposed on each of the front and back surfaces of the piezoelectric substrate, and the metal film is disposed so that the first package substrate is included in the second package substrate in a plan view. A step of performing temporary bonding, and irradiating the temporarily bonded portion with a laser beam or an electron beam from one direction, thereby providing a book of the first and second package base materials and the piezoelectric substrate. The process of joining and the pressure comprising Since in hermetic sealing method for a vibration device, it is possible to prevent positional deviation between the package substrate and the piezoelectric substrate can be realized an efficient and accurate hermetic sealing.

  The temporary bonding can be performed by, for example, ultrasonic welding, but can also be performed by using a jig. In other words, a jig having an opening having substantially the same external dimensions as the piezoelectric substrate and slightly larger than the external dimensions of the first package base material is prepared, and the periphery of the piezoelectric substrate and the periphery of the jig are substantially coincident. In this way, after the jig is placed on the piezoelectric substrate, the first package base material is housed and placed in the opening and temporarily fixed. By irradiating the first package substrate with a laser beam or an electron beam in this state, the first package substrate and the piezoelectric substrate can be joined. Similarly, the piezoelectric substrate and the second package substrate can be bonded by a laser beam or an electron beam. At this time, if the jig is formed of a translucent material, by irradiating the jig with a laser beam or an electron beam from above the jig and transmitting the inside of the jig, Bonding can also be performed by reaching the metal film on the opposite surface of the piezoelectric substrate. Alternatively, the package base material and the piezoelectric substrate may be temporarily bonded using a laser beam or an electron beam without using the jig.

  Further, since an energy beam such as a laser beam or an electron beam is used as a sealing means, it is possible to cope with a metal film having a high melting point and, for example, processing compared to a heat sealing method such as a seam welding method. Time can be shortened.

  Further, since the metal film at the bonding interface can be melted through the first and piezoelectric substrates made of a light-transmitting material, a laser using a member made of a conventional non-light-transmitting material can be used. Compared to the case where the metal film at the bonding interface is melted by an energy beam such as, the sealing trace is smooth and the sealing trace can be narrowed.

  Normally, the surface state of a metal film formed by resistance heating vapor deposition or the like is microscopically uneven, and has a surface state in which “mountains” and “valleys” are continuous. When such metal films are joined to each other by ultrasonic welding, the joining interface is in a state where the “peaks” are in point contact with each other and the “valley” is a void. Thus, the airtightness is incomplete. However, according to the second aspect of the present invention, since the metal film is melted by the energy beam in the temporary bonding by the ultrasonic welding method, the molten metal flows in so as to fill the “valley” portion so that the bonding interface is formed. It can be smoothed and close to a flat state. As a result, poor airtightness can be prevented and stable airtight sealing can be performed.

  As described above, according to the present invention, it is possible to provide a piezoelectric vibrating device and a hermetic sealing method for a piezoelectric vibrating device that can perform stable hermetic sealing in response to a reduction in height.

-First embodiment-
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. 1, taking a crystal resonator using a crystal substrate as a piezoelectric substrate as an example. FIG. 1 is a cross-sectional view in the long side direction of a crystal resonator showing a first embodiment of the present invention. In FIG. 1, the external connection terminals formed on the bottom surface (back surface) of the crystal resonator and the wiring conductors that electrically connect the external connection terminals and the electrodes formed on the front and back surfaces of the crystal substrate are described. Omitted.

  As shown in FIG. 1, a crystal resonator 1 applied in the present embodiment includes a first package base 2 having a rectangular shape in plan view, and a crystal resonator element 3 having a biconcave shape in a sectional view with a thin central portion. The second package base 4 is rectangular in plan view. Hereinafter, after describing the components of the crystal unit 1 alone, a method for manufacturing the crystal unit 1 will be described.

  In FIG. 1, the quartz crystal resonator element 3 is an AT-cut quartz plate having a rectangular shape in plan view, and a concave portion 31 having a thin central region, and an annular thick portion 32 is formed around the concave portion. Yes. The recessed portion 31 is formed by wet etching by forming a resist in a region other than the portion where the quartz vibrator piece 3 is thinned.

  A pair of excitation electrodes 33 for driving the crystal vibrating piece 3 are formed on the front and back surfaces of the recessed portion 31 so as to face each other. Here, the excitation electrode 33 is formed on the main surface (front and back surfaces) of the quartz crystal vibrating piece 3 in order from the bottom by a vapor deposition method or the like with a film configuration of chromium, gold, and chromium. The film configuration of the electrode is not limited to this, and other film configurations may be used. The excitation electrode 33 is connected to a lead electrode (not shown), and a part of the lead electrode includes a conduction path (not shown) vertically passing through the crystal resonator element 3 in the thickness direction and a second package. It is electrically connected to an external connection terminal (not shown) finally formed on the lower surface of the second package substrate 4 via a wiring conductor (not shown) inside the substrate 4. The crystal resonator 1 is used by fixing the external connection terminals to a conductor (land pattern) formed on a substrate in various devices by solder or the like. The electrical connection method between the excitation electrode 33 and the external connection terminal is an example, and is not limited to the present embodiment.

  A second metal film 301 and a third metal film 302 are formed on the front and back surfaces of the thick portion 32 of the crystal vibrating piece 3, and the metal films (301 and 302) are made of the same material. . Gold is used for the second and third metal films, and is formed in a circumferential shape by a vacuum deposition method at each position of the front and back surfaces (peripheral regions) of the thick portion 32 of the crystal vibrating piece 3. . Here, the second metal film 301 and the third metal film 302 are in a positional relationship in which they overlap in a plan view. However, the irradiation position on the metal film at the time of sealing with a laser beam (described later) is different. In other words, the bonding region by the energy beam has a positional relationship that does not overlap in plan view. Note that the junction region here refers to a region irradiated with an energy beam on a metal film. The positional relationship between the second metal film 301 and the third metal film 302 is an example, and the positional relationship is not limited to this embodiment. For example, the second metal film 301 and the third metal film 302 may have a positional relationship in which only a part thereof overlaps in plan view.

  In FIG. 1, the first package substrate 2 is a flat plate having a rectangular shape in plan view, and quartz that is a light-transmitting material is used. In plan view, as shown in FIG. 1, the external dimensions of the first package base 2 are substantially the same as the external dimensions of the crystal vibrating piece 3, and the crystal vibrating piece 3 of the first package base 2 is A first metal film 201 is circumferentially formed by a vacuum evaporation method on the periphery of the bonding surface side. Here, the first metal film 201 is made of gold, and is formed so that the formation width is substantially the same as the formation width of the second metal film 301.

  As the material of the second package substrate 4, quartz is used as in the case of the first package substrate 2. The second package base 4 is also a flat plate having a rectangular shape in plan view, and the external dimensions of the second package base 4 are substantially the same as the external dimensions of the crystal vibrating piece 3. A fourth metal film 401 is formed on the periphery of the second package substrate 4 on the side of the joint surface with the crystal vibrating piece 3. Here, the fourth metal film 401 is made of gold in this embodiment. The formation width of the fourth metal film 401 is substantially the same as the formation width of the third metal film 302.

  The above is a description of the main members constituting the crystal unit 1. However, the first and second package base materials 2 and 4 and the crystal vibrating piece 3 described above are collectively formed from the wafer state, respectively. After a plurality of crystal resonators are formed, they are separated into pieces by dividing into pieces. By such a method, it becomes possible to handle all the members (first and second package base materials, crystal vibrating pieces) constituting the crystal unit 1 in a wafer state. Compared with the method of handling the structural members, the handling becomes very simple. Furthermore, the size can be reduced as compared with a conventional ceramic package. Hereinafter, a method for manufacturing a crystal resonator constituting one unit will be described.

  First, the first metal film 201 formed on the first package base 2 is used as the second metal formed on the upper surface of the crystal vibrating piece 3 (on the side of the joint surface with the first package base 2). The film is positioned and placed on the film 301 so as to substantially coincide with each other in plan view. In the positioning and mounting, an appropriate mounting position is recognized by the image recognition means. The first package base 2 and the quartz crystal vibrating piece 3 are temporarily bonded. At this time, the temporary bonding is preferably performed near the inner periphery of the formation region of the metal films 201 and 301 (inside the center in the width direction of the metal film).

  A laser beam is irradiated to the portion where the temporary fixing is performed from above (specifically, at a position higher than the first package base material 2) in a vacuum atmosphere using a green laser. The laser beam is transmitted through the inside of the first package base material 2 that is a light-transmitting material, reaches the metal film at the temporary bonding portion, and melts the metal film. As a result, the main bonding between the first package base 2 and the crystal vibrating piece 3 is completed.

  Next, the crystal vibrating piece 3 bonded to the first package substrate 2 is turned upside down, and the third metal formed on the bonding surface side of the crystal vibrating piece 3 with the second package substrate 4 is formed. On the film | membrane 302, the 4th metal film | membrane 401 formed in the 2nd package base material 4 is positioned and mounted so that it may correspond substantially by planar view. In the positioning and mounting, an appropriate mounting position is recognized by the image recognition means. Then, after the positioning and mounting, the quartz crystal vibrating piece 3 and the second package base 4 are bonded by gold diffusion bonding by the ultrasonic welding method through the third metal film 302 and the fourth metal film 401 described above. And temporarily fixing. At this time, the temporary bonding is preferably performed near the outer peripheral edge of the formation region of the metal films 302 and 401 (outside the center in the width direction of the metal film).

  In the vacuum atmosphere, the portion where the third metal film 302 and the fourth metal film 401 are temporarily bonded is disposed above the crystal vibrating piece 3 (specifically, the third metal film). A laser beam is irradiated using a green laser from above (from the upper side in the vertical direction with respect to the temporarily fixed joint portion between 302 and the fourth metal film 401). The laser beam passes through the inside of the crystal vibrating piece 3 that is a translucent material, reaches the metal film at the temporary bonding joint portion between the third metal film 302 and the fourth metal film 401, and the metal Melt the membrane. As a result, the crystal resonator element 3 and the second package base 4 are joined together. As described above, according to the hermetic sealing method of the present invention, since the bonding region does not overlap in plan view when the first and second package base materials and the crystal vibrating piece are bonded together, one of the metals is irradiated during laser beam irradiation. There is no damage to the junction area of the membrane. Therefore, stable hermetic sealing can be performed. In addition, since the package substrate is formed of a light-transmitting material in the present invention as compared with the conventional case where the package substrate is formed of an insulating material (non-light-transmitting material) such as ceramic, the energy of the laser beam Since the loss can be suppressed and the temporarily bonded joint portion is visualized, the joined state after the beam irradiation can be easily visually confirmed.

  Since the irradiation diameter of the laser beam is smaller than the formation width of the metal films 201, 301, 302, 401, the irradiation position can be selected. In the present embodiment, the formation width of the metal film is about 150 μm, and the irradiation diameter of a laser beam (described later) is 80 μm or less. In the present embodiment, the main bonding is performed in a vacuum atmosphere. However, the bonding is not limited to a vacuum atmosphere, and may be performed in an inert gas atmosphere such as nitrogen.

  Microscopically, very small voids (voids) may be generated at the bonding interface of the temporary bonding joint portion by ultrasonic welding. However, the metal itself of the temporary bonding joint portion may be removed using a laser beam. By melting, the hollow portion can be filled and smoothed. Therefore, airtight failure can be prevented and stable airtight sealing can be performed.

  In the present embodiment, after the main bonding of the first package base 2 and the crystal vibrating piece 3 is performed, the temporary bonding and the main bonding by ultrasonic welding between the crystal vibrating piece 3 and the second package base 4 are performed. Yes, but not limited to this order. For example, the temporary bonding of the crystal vibrating piece 3 and the first and second package bases 2 and 4 may be performed first, and then the main bonding using a laser beam may be performed. In this case, the main bonding between the crystal vibrating piece 3 and the second package base 4 may be performed before the main bonding between the first package base 1 and the crystal vibrating piece 3. Alternatively, by using two laser irradiation apparatuses, it is possible to simultaneously perform the main bonding of the first and second package bases 2 and 4 and the crystal vibrating piece 3 simultaneously. In this case, since the time required for the hermetic sealing process can be shortened, it contributes to the improvement of the production efficiency of the crystal unit 1. In the present embodiment, a green laser is used at the time of main bonding, but the present invention is not limited to this, and the present invention can be applied to a so-called energy beam. For example, the main bonding may be performed using an electron beam instead of the green laser. In the present embodiment, gold is used as the metal film material. However, since the green laser (wavelength) has a good absorption rate for gold, the sealing efficiency can be improved. Note that the combination of green laser and gold is an example, and is not limited to this combination, and it is possible to select a metal material that provides a good absorption rate according to the laser wavelength.

  In the present embodiment, a metal film is formed on each of the first and second package base materials and the crystal vibrating piece. However, the first and second package base materials are not formed on the crystal vibrating piece. The structure which formed the metal film only in the 2nd package base material may be sufficient. Alternatively, the metal film may be formed only on the crystal vibrating piece and the metal film may not be formed on the first and second package base materials.

  In the embodiment of the present invention, quartz is used as the material for the two package substrates, but glass or sapphire may be used in addition to quartz.

-Second Embodiment-
A second embodiment of the present embodiment will be described with reference to FIGS. 2 to 3, taking a crystal resonator using a crystal substrate as a piezoelectric substrate as an example. FIG. 2 is a cross-sectional view in the long side direction of a crystal resonator showing a second embodiment of the present invention. FIG. 3 is a plan view of the crystal resonator showing the second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and a part of the description is omitted. Has the same effect.

  As shown in FIG. 2, a second metal film 301 and a third metal film 302 are formed on the front and back surfaces of the thick portion 32 of the crystal vibrating piece 3, and the metal films (301 and 302). Is made up of gold. The second metal film 301 is spaced inward from the peripheral edge on the upper surface side of the quartz crystal vibrating piece 3 and is formed in a circumferential shape at a position on the upper surface of the thick portion 32 by a vacuum deposition method. The third metal film 302 is formed in a circumferential shape by a vacuum vapor deposition method in a region including the peripheral edge on the lower surface side of the quartz crystal vibrating piece 3. Here, the second metal film 301 and the third metal film 302 are in a positional relationship that does not overlap in a plan view. That is, the metal film is in a positional relationship in which the bonding region by the energy beam does not overlap.

  When the piezoelectric vibration device having such a configuration is manufactured, the first metal film 201 formed on the first package base 2 is bonded to the upper surface of the crystal vibrating piece 3 (the bonding surface with the first package base 2). On the second metal film 301 formed on the side) so as to substantially coincide with each other in plan view. In the positioning and mounting, an appropriate mounting position is recognized by the image recognition means. The first package base material 2 is included in the crystal vibrating piece 3 in a plan view in the state of being positioned and mounted. After the positioning and mounting, the first package substrate 2 and the quartz crystal vibrating piece 3 are bonded by gold diffusion bonding by ultrasonic welding via the first metal film 201 and the second metal film 301 described above. Perform temporary bonding.

  As described above, according to the present embodiment, the temporarily bonded joint portion is irradiated with the laser beam from one direction to perform the main joining of the package base material and the quartz crystal vibrating piece. There is no defect (void) in the metal film on the front and back surfaces of the piece. That is, since the joining region between the first and second package base materials and the piezoelectric base material does not overlap in plan view, the energy beam is transmitted through the inside of the first package base material and the piezoelectric substrate, so that the second Even if it reaches the metal film on the package substrate side, the bonding region of the third and fourth metal films is not damaged. Therefore, stable hermetic sealing can be performed.

  In addition, as in the present embodiment, the first to fourth metal films are formed in the peripheral regions of the first and second package bases, and the first package base is second in plan view. If it is in a state of being included in the package base material, it is possible to make the structure in which the joining regions do not overlap in a plan view, and it is also possible to make the structure in which the joining regions do not overlap in a plan view. Therefore, it is suitable for joining the first and second package base materials and the piezoelectric substrate from one direction using an energy beam. Thereby, a simpler sealing process can be realized as compared with the case where bonding is performed by irradiating energy beams from two directions. In addition, after joining one package base material and one surface of the piezoelectric substrate 3, a method of turning the front and back (up and down) in order to join another package base material and one surface of the piezoelectric substrate 3 is possible. Compared with such a method, if the piezoelectric vibration device of the present invention is used, the number of work steps in the sealing process can be reduced, and the production efficiency is improved.

  As shown in FIG. 3, the position away from the inner side (recess 31) of the crystal vibrating piece, that is, the position close to the peripheral edge of the metal films 201, 301, 302, 401 (circumferential shape indicated by L in FIG. 3). When the laser beam is irradiated to the line (2), it is preferable because the effect of suppressing the splash (spattering of the molten metal) during melting of the metal film can be expected. In the present embodiment, the main bonding is performed in a vacuum atmosphere. However, the bonding is not limited to a vacuum atmosphere, and may be performed in an inert gas atmosphere such as nitrogen.

-Third embodiment-
A second embodiment of the present embodiment will be described with reference to FIG. 4, taking a piezoelectric thin film resonator (FBAR) as an example. FIG. 4 is a cross-sectional view of the crystal resonator according to the second embodiment in the long side direction. The same components as those in the previous embodiment are denoted by the same reference numerals and part of the description is omitted. This has the same effect as the embodiment.

  Both the first and second package base materials are rectangular flat plates made of crystal, and the first package base material 2 is formed with an outer dimension smaller than that of the crystal substrate 5. The second package base 4 has substantially the same outer dimensions as the quartz substrate 5.

  In this embodiment, as shown in FIG. 4, a piezoelectric thin film 34 of aluminum nitride (AlN) is formed on the upper surface of the quartz substrate 5 so as to be sandwiched between the lower electrode 36 and the upper electrode 35. Note that zinc oxide (ZnO) can be used instead of the aluminum nitride. A cavity (cavity) is formed by etching under the lower electrode 36 of the quartz substrate 5. The upper electrode 35 and the lower electrode 36 are connected to each other through a conduction path (not shown) penetrating the quartz substrate 5 in the thickness direction and a wiring conductor (not shown) inside the second package base 4. Finally, it is electrically connected to an external connection terminal (not shown) formed on the lower surface side of the second package substrate 4. The upper electrode 35 and the lower electrode 36 are made of (Mo). Here, aluminum (Al) or ruthenium (Ru) may be used in addition to molybdenum.

  Similar to the first embodiment, a second metal film 301 and a third metal film 302 are circumferentially formed on the front and back surfaces of the quartz substrate 5 by a vacuum deposition method. As shown in FIG. 4, the metal films 301 and 302 are partially overlapped in plan view. That is, the outer peripheral edge portion of the second metal film 301 and the region including the inner peripheral edge portion of the third metal film 302 overlap each other in plan view. However, it corresponds to a bonding region (specifically, a partial region of the first metal film 201 and the fourth metal film 401) by the laser beam between the first package base material 2 and the second package base material 4. The portions are not overlapped in plan view. By arranging such a metal film, for example, the external dimensions of the quartz crystal substrate 5 and the second package base 4 can be reduced, so that the piezoelectric vibration device can be further reduced in size.

  The first metal film 201 and the fourth metal film 401 are also circumferentially formed by vacuum deposition on the bonding surface side of each of the first package base material 2 and the second package base material 4 with the crystal substrate 5. Is formed.

  The first package base 2 is ultrasonically welded to the surface side of the crystal substrate 5 via the first metal film 201 and the second metal film 301 so as to be included in the crystal substrate 5 in plan view. Temporary bonding is performed. After the first package base 2 and the quartz substrate 5 are temporarily bonded, the green package is irradiated onto the temporary bond portion to perform the main bonding between the first package substrate 2 and the crystal substrate 5. Similarly, temporary bonding and main bonding of the crystal substrate 5 and the second package base 4 are performed. According to such a configuration, since it is a hermetic sealing method for performing the main bonding between the package base material and the quartz substrate by irradiating the temporarily bonded portion with a laser beam from one direction, the package base The positional deviation between the material and the quartz substrate can be prevented.

  In addition, by melting the metal film in the portion temporarily bonded by the laser beam, it is possible to fill the void in the bonding interface with the molten metal. Thereby, the space | gap in the said joining interface can be suppressed and it can approximate to a flat state. As a result, a piezoelectric thin film device having good hermeticity can be provided.

  In addition, although gold is used as the metal film used for sealing in the embodiment of the present invention, the present invention is not limited to this. In addition to gold, a gold-tin alloy (Au-Sn alloy), Other metals such as a tin-silver alloy (Sn—Ag alloy) and gold-germanium (Au—Ge alloy) can also be used. For example, when a gold-tin alloy is used as the metal film, since the melting point of the metal film is lowered, it can be dealt with by adjusting the output of the laser to be lowered.

  In the embodiment of the present invention, two package base materials having a rectangular shape in plan view and a flat plate shape are used. However, the present invention is not limited to this, and the crystal vibration piece is formed by two package base materials. As long as the excitation electrode can be hermetically sealed, the shape of the package substrate may be arbitrarily set. For example, a form in which the concave portions of the two package bases formed in a concave shape are airtightly bonded so as to face the crystal vibrating piece may be employed. Or the form comprised with the flat package base material and the quartz crystal vibrating piece, and the package base material formed in the concave shape by the box-shaped body may be sufficient.

  In the embodiment of the present invention, a surface-mount type crystal resonator is taken as an example, but other surface-mount type used in electronic devices such as a crystal oscillator in which a crystal resonator is incorporated in an electronic component such as a crystal filter or an integrated circuit. This method can also be applied to a method for manufacturing a piezoelectric vibration device.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  It can be applied to mass production of piezoelectric vibration devices.

Sectional drawing of the long side direction of the crystal oscillator which shows the 1st Embodiment of this invention. Sectional drawing of the long side direction of the crystal oscillator which shows the 2nd Embodiment of this invention. The top view of the crystal oscillator which shows the 2nd Embodiment of this invention. Sectional drawing of the long side direction of the crystal oscillator which shows the 3rd Embodiment of this invention. Sectional drawing of the long side direction of the crystal oscillator which shows conventional embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Quartz crystal resonator 2 1st package base material 201 1st metal film 3 Quartz vibration piece 31 Recessed part 32 Thick part 33 Excitation electrode 34 Piezoelectric thin film 35 Upper electrode 36 Lower electrode 37 Cavity 301 2nd metal film 302 2nd 3 Metal film 4 Second package substrate 401 Fourth metal film 5 Crystal substrate

Claims (3)

A piezoelectric vibration device composed of a piezoelectric substrate and first and second package base materials made of a translucent material bonded to each of the front and back surfaces of the piezoelectric substrate via a metal film,
A piezoelectric vibration device characterized in that a bonding region between the first and second package base materials and the piezoelectric substrate does not overlap in a plan view.   The first package base is formed with a smaller outer dimension than the second package base, and the first package base is included in the second package base in a plan view. The piezoelectric vibration device according to claim 1. A piezoelectric vibration device comprising: a translucent piezoelectric substrate; and first and second package base members made of a translucent material bonded to each of the front and back surfaces of the piezoelectric substrate via a metal film. An airtight sealing method,
The first package base is formed with a smaller outer dimension than the second package base,
The first and second package substrates are temporarily attached to the front and back surfaces of the piezoelectric substrate via the metal film so that the first package substrate is included in the second package substrate in a plan view. A process of stopping and joining;
Irradiating a laser beam or an electron beam from one direction to the temporarily bonded portion to perform a main bonding between the first and second package base materials and the piezoelectric substrate;
A hermetic sealing method for a piezoelectric vibration device comprising:

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