JP5051446B2 - Method for manufacturing piezoelectric vibrator - Google Patents

Description

  The present invention relates to a method of manufacturing a piezoelectric vibrator in which a thickness-shear vibration mode or tuning-fork type piezoelectric vibrating piece is hermetically sealed in a package.

  In general, a surface mount type piezoelectric device widely adopts a structure in which a piezoelectric vibrating piece is mounted in a package formed of an insulating material such as ceramic. In this conventional package, a lid is joined to a base on which a piezoelectric vibrating piece is mounted by low melting glass, seam welding, or the like, and hermetically sealed. Gas generated from low melting point glass and high heat of seam welding may reduce or deteriorate the frequency characteristics of the crystal resonator element, so the crystal resonator element and the outer frame are respectively formed above and below the crystal plate. A quartz resonator having a structure that is miniaturized and thinned by bonding substrates is proposed.

  As a crystal resonator having such a structure, for example, a metal layer is provided on the upper and lower surfaces of an outer frame that is integrated with the crystal resonator, and the metal layer and a lid and case made of glass are joined by anodic bonding. (For example, see Patent Documents 1 and 2). In addition, the mirror-polished piezoelectric plate and substrate mutual bonding surface is cleaned by removing dirt and the like at the atomic level by exposure to ultraviolet radiation or oxygen plasma in an oxygen-containing atmosphere, and is formed by moisture adsorption. A piezoelectric device bonded by OH group hydrogen bonding is known (see, for example, Patent Document 3). Furthermore, there is known a crystal resonator in which a quartz plate is sandwiched between two glass plates in a sandwich structure and directly joined firmly without warping (see, for example, Patent Document 4).

  In addition, a piezoelectric vibrator such as a quartz vibrator is proposed in which a quartz plate on which an electrode film is formed and a quartz protective substrate on both sides thereof are hermetically bonded by diffusion bonding at a bonding portion having gold and silver ( For example, see Patent Document 5). Similarly, there is known a crystal resonator package in which a metal layer is formed on each bonding surface of a quartz crystal substrate and a lid in which a crystal vibrating piece and an outer frame are integrally formed, and the metal layers are closely bonded to each other. (For example, see Patent Document 6). In these quartz crystal resonators, the quartz film and the lid are satisfactorily bonded after the metal film on each bonding surface is cleaned by plasma treatment or the like.

  FIGS. 16A to 16C show an example of a conventional crystal resonator in which a crystal plate integrally formed with a crystal vibrating piece and an outer frame and an upper and lower substrate are joined by diffusion bonding of metal films. Show. The crystal resonator 1 has a laminated structure in which an intermediate crystal plate 2, an upper substrate 3 serving as a lid, and a lower substrate 4 serving as a package base are integrally and airtightly joined. The upper and lower substrates 3 and 4 are also preferably formed of quartz thin plates.

  As shown in FIGS. 17 (A) and 17 (B), the intermediate crystal plate 2 has a thickness-shear mode crystal vibrating piece 5 and an outer frame 6 integrally coupled at the base end portion 5a. Excitation electrodes 7 and 8 are formed on the upper and lower surfaces of the crystal vibrating piece 5, respectively, and are formed over the entire circumference of the upper and lower surfaces of the outer frame 6 by being drawn out from the base end portion 5 a by the wiring films 7 a and 8 a. The conductive metal thin films 9 and 10 are electrically connected. A through-hole 11 is provided at the longitudinal end of the outer frame 6 on the side where the crystal vibrating piece 5 is coupled, and the lower surface of the longitudinal end is separated from the conductive metal thin film 10 by the region 12 of the crystal face. A conductive metal thin film 13 is formed, and is electrically connected to the conductive metal thin film 9 on the upper surface through a conductive film inside the through hole 11.

  As shown in FIG. 18, a metal thin film 14 corresponding to the conductive metal thin film 9 is formed on the lower surface of the upper substrate 3 in a bonding region with the outer frame 6. On the upper surface of the lower substrate 4, as shown in FIG. 19, a metal thin film 15 corresponding to the conductive metal thin film 10 and a metal thin film 17 separated from the metal thin film in a region 16 on the crystal face are formed with the outer frame 6. It is formed in the junction region. The crystal vibrating piece 5 is held and accommodated in a cavity 18 defined between the bonded intermediate crystal plate and the upper and lower substrates in a cantilevered state at the base end portion 5a.

  The outer frame 6 of the intermediate crystal plate 2 and the upper and lower substrates 3 and 4 are bonded by diffusion bonding between the metal thin films. The upper and lower surfaces of the outer frame 6 and the bonding surfaces of the upper and lower crystal substrates 3 and 4 are cleaned and activated by plasma processing, ion beam processing, etc., and then aligned and overlapped with each other. A predetermined pressure is applied while heating in accordance with the above, and airtight, good and stable bonding is performed.

  On the lower surface of the lower quartz substrate 4, external electrodes 19 and 20 are provided at the respective corners as shown in FIG. Furthermore, casters (circular through holes) provided at intersections of vertical and horizontal cutting lines for cutting individual crystal plates from large crystal plates by dicing, for example, remain at each corner of the lower crystal substrate 4. / 4 circular chips 21 and 22 are formed. A conductive film is formed on the inner surface of each chip, and the external electrodes 19 and 20 adjacent thereto are electrically connected to the conductive metal thin films 10 and 13 on the lower surface of the intermediate crystal plate 2 viewed from each chip.

In addition, there is known a crystal resonator in which a resonator crystal piece made of an AT-cut crystal plate and a reinforcing plate are directly joined (see, for example, Patent Document 7). In this direct bonding, the main surface of the crystal wafer for vibrator and the main surface of the crystal wafer for reinforcement are mirror-polished to make them hydrophilic (OH base), and heat treatment is performed by contacting them to remove H ₂ O. The Si—O—Si bond is used. Alternatively, one of the main surfaces is hydrophilized (OH group) and the other main surface is hydrophobized (H group), and a heat treatment is performed by bringing them into contact with each other to form Si—Si bonds. . Such interatomic bonding increases the bonding strength.

JP 2000-68780 A JP 2002-76826 A JP 7-154177 A JP-A-7-86106 International Publication Number WO00 / 76066 Pamphlet JP 2006-157369 A JP 2006-67631 A

  In the conventional crystal resonator described above with reference to FIG. 12, the excitation electrode of the crystal resonator element is dry-etched in a state where the intermediate crystal plate and the lower substrate are joined in the manufacturing process or in the state of the intermediate crystal plate alone. It is customary to adjust the frequency by partially removing the electrode material by attaching the electrode material by sputtering or vapor deposition. Then, plasma is applied to the frequency-adjusted intermediate crystal plate to clean and activate the bonding surface, and the upper substrate is bonded and sealed by diffusion bonding between metal thin films.

  However, in order to activate the bonding surface, for example, when a known SWP type RIE plasma processing apparatus is used, not only the outer frame of the target intermediate crystal plate but also the entire upper surface including the excitation electrode of the crystal vibrating piece Will be irradiated with plasma. As a result, the surface of the excitation electrode is etched, and the frequency of the quartz crystal resonator element that has been previously adjusted is greatly shifted, and as a result, desired characteristics may not be obtained. Furthermore, it is practically difficult to adjust the frequency of the crystal unit again after sealing.

Further, in the case of direct bonding between quartz crystals, there is a possibility that electrode material scattered by etching of the excitation electrode by plasma irradiation or the like adheres to the crystal bonding surface. As a result, there arises a problem that the crystal plate is poorly bonded and the hermetic sealing of the crystal resonator is impaired.

  Accordingly, the present invention has been made in view of the above-described conventional problems. An object of the present invention is to provide a piezoelectric substrate in which a piezoelectric vibrating piece and an outer frame are integrally formed, and to seal the base plate and the base plate of the package by direct bonding or diffusion bonding on the upper and lower surfaces of the outer frame, respectively. An object of the present invention is to provide a method capable of easily and effectively preventing a frequency shift caused by plasma treatment for surface activation of each bonding surface of a piezoelectric substrate and upper and lower substrates in the manufacture of a piezoelectric vibrator to be stopped. A further object of the present invention is to ensure a good bonding state when the piezoelectric substrate and the base and / or the lid are directly bonded in such a piezoelectric vibrator.

  According to the present invention, in order to achieve the above object, for example, a step of forming an intermediate piezoelectric plate in which a piezoelectric vibrating piece made of, for example, quartz and an outer frame are integrally coupled, and a lower surface having a joint surface with the lower surface of the outer frame. A step of forming a side substrate, a step of forming an upper substrate having a bonding surface with the upper surface of the outer frame, a step of bonding one of the lower substrate and the upper substrate to the intermediate piezoelectric plate in the outer frame, and the lower substrate Or, adjusting the frequency of the piezoelectric vibrating piece of the intermediate piezoelectric plate to which one of the upper substrates is bonded, and after adjusting the frequency of the piezoelectric vibrating piece, bonding the other of the lower substrate or the upper substrate to the intermediate piezoelectric plate at the outer frame A piezoelectric vibrator manufacturing method for hermetically sealing a piezoelectric vibrating piece in a cavity defined between the intermediate piezoelectric plate and the upper and lower substrates. Join it before the process of joining the other An intermediate piezoelectric plate in which the upper or lower surface of the outer frame of the intermediate piezoelectric plate is surface-activated by, for example, plasma irradiation or ion beam irradiation, and one of the lower substrate and the upper substrate is bonded before the surface activation step. The step of placing the electrode cover on the piezoelectric vibrating piece and the step of removing the electrode cover from the piezoelectric vibrating piece before the step of bonding the other of the lower substrate and the upper substrate after the surface activation step A method for manufacturing a piezoelectric vibrator is further provided.

  By using the detachable electrode cover in this way, it is possible to reliably prevent the excitation electrode of the piezoelectric vibrating piece from being etched by the surface activation process after adjusting the frequency, and without changing the frequency inadvertently. Frequency characteristics can be ensured.

  Furthermore, the possibility that the electrode material scatters from the excitation electrode by etching and adheres to the upper or lower surface of the outer frame is eliminated, so that the outer frame and the lower and / or upper substrate can be satisfactorily bonded. Particularly in the case of direct bonding between quartz crystals, it is possible to always ensure the cleanness of the bonding surface and guarantee a good bonding state.

  The piezoelectric vibrating piece of the intermediate piezoelectric plate is a vibrating piece in a thickness-shear vibration mode in one embodiment, and is a tuning fork type vibrating piece in another embodiment, and can be similarly applied in any case.

  The present invention can be similarly applied to crystal resonators having various configurations. In an embodiment, the intermediate piezoelectric plate has a metal thin film on the upper surface and the lower surface of the outer frame, the lower substrate has a metal thin film on the joint surface with the lower surface of the outer frame, and the upper substrate has an upper surface of the outer frame. The intermediate piezoelectric plate and the upper and lower substrates are directly bonded or diffused between the upper and lower metal thin films and the upper and lower metal thin films. Joined by joining.

  In another embodiment, the intermediate piezoelectric plate has metal thin films on the upper and lower surfaces of the outer frame, the lower substrate is made of crystal, the bonding surface with the lower surface of the outer frame is a crystal element surface, and the upper substrate is made of crystal. And the bonding surface with the upper surface of the outer frame is a crystal element surface, and the intermediate piezoelectric plate and the upper substrate and the lower substrate are formed by the metal thin film on the upper surface and the lower surface of the outer frame and the crystal element surfaces of the upper substrate and the lower substrate. Are joined by direct joining.

  In still another embodiment, the lower substrate, the intermediate piezoelectric plate, and the upper substrate are made of crystal, one of the upper surface or the lower surface of the outer frame of the intermediate piezoelectric plate has a metal thin film, and the other of the upper surface or the lower surface of the outer frame is The crystal element surface, the bonding surfaces of the upper and lower substrates with the outer frame lower surface and the upper surface are crystal element surfaces, and the intermediate piezoelectric plate and the upper and lower substrates are the metal thin film and the crystal element surface on the upper and lower surfaces of the outer frame. Bonding is performed by direct bonding between the crystal surfaces of the upper and lower substrates.

  In still another embodiment, the lower substrate, the intermediate piezoelectric plate, and the upper substrate are made of quartz, and the upper and lower surfaces of the outer frame of the intermediate piezoelectric plate are crystal surfaces, and the lower and upper surfaces of the outer frame and upper substrate of the upper and lower substrates. The intermediate piezoelectric plate and the upper and lower substrates are bonded by direct bonding between the upper and lower crystal element surfaces and the upper and lower substrate crystal elements.

  In one embodiment, the lower substrate, the intermediate piezoelectric plate, and the upper substrate are made of quartz and are bonded to each other with the same crystal plane orientation, so that the bonded state of the crystal unit can be better maintained.

  In one embodiment, the outer cover of the intermediate piezoelectric plate, the upper substrate, or the lower substrate is disposed on a surface of the piezoelectric vibrating piece opposite to the excitation electrode when the electrode cover is placed on the piezoelectric vibrating piece. A metal film of the same kind as the metal thin film formed on the substrate. As a result, even if the material etched from the surface of the electrode cover in the surface activation step is scattered around and adhered to the outer frame of the intermediate piezoelectric plate, it is the same kind of metal material as the metal thin film of the outer frame. When bonding the upper substrate or the lower substrate in a later step, there is little influence on diffusion bonding between the metal thin films, and a decrease in bonding strength can be suppressed.

  In another embodiment, the electrode cover has a recess with a planar dimension on the side of the excitation electrode that is the same as or larger than that of the excitation electrode. As a result, the electrode cover can be placed on the piezoelectric vibrating reed so that its lower surface does not come into contact with the excitation electrode. This prevents the surface of the excitation electrode from being contaminated by dirt or dust from the lower surface of the electrode cover, thereby preventing the piezoelectric vibration. The possibility of affecting the frequency characteristics of the piece can be eliminated.

  In one embodiment, forming an intermediate piezoelectric wafer having a plurality of intermediate piezoelectric plates, and forming an upper wafer in which a plurality of upper substrates are arranged corresponding to the intermediate piezoelectric plates of the intermediate piezoelectric wafer, Forming a lower wafer in which a plurality of lower substrates are arranged in correspondence with the intermediate piezoelectric plate of the intermediate piezoelectric wafer, and one of the lower and upper wafers superimposed on the lower or upper surface of the intermediate piezoelectric wafer. A step of bonding, a step of individually adjusting the frequency of the piezoelectric vibrating piece of each intermediate piezoelectric plate of the intermediate piezoelectric wafer, and a step of integrally bonding the other of the upper and lower wafers on the upper surface or the lower surface of the intermediate piezoelectric wafer. And a step of cutting a laminated body of bonded wafers to divide a plurality of piezoelectric vibrators into individual pieces, and before the step of bonding the lower wafer or the other of the upper wafer, intermediate piezoelectric bonding them Upper surface of each outer frame of the wafer On the surface of each piezoelectric vibrating piece of the intermediate piezoelectric wafer to which one of the lower wafer and the upper wafer is bonded before the surface activation process. , Each of the piezoelectric vibrating reeds before the step of placing the plurality of electrode covers covering the excitation electrodes of the piezoelectric vibrating reed and the step of bonding the other of the lower wafer or the upper wafer after the surface activation step. There is provided a method of manufacturing a piezoelectric vibrator further comprising a step of removing the electrode cover from above.

As a result, a large number of piezoelectric vibrators can be manufactured at the same time, and productivity can be improved and costs can be reduced. In particular, when crystal wafers are directly bonded to each other with crystal faces, the possibility that the electrode material scatters from the excitation electrode of the intermediate piezoelectric wafer due to etching by plasma irradiation or the like and adheres to the upper or lower surface of each outer frame is eliminated. The piezoelectric wafer and the upper and / or lower wafer can be bonded satisfactorily.

  In another embodiment, the electrode cover placed on the intermediate piezoelectric wafer is not an individual piece that is separated and separated for each piezoelectric vibrating piece, but a large number of pieces are separated from each piezoelectric vibrating piece of the intermediate piezoelectric wafer. The structure may be arranged in accordance with the position and integrally connected. In that case, since the surface activation by plasma irradiation or the like may be insufficient when the adjacent electrode covers are connected to the outer frame of each intermediate piezoelectric plate, it is disposed sufficiently above the outer frame. By using such an integrated electrode cover, it is possible to easily place the piezoelectric cover on each piezoelectric vibrating piece in a short time.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
1A to 1D show a process of manufacturing the above-described thickness-shear mode AT-cut quartz crystal resonator of FIG. 16 according to the method of the present invention in the order of steps. In FIG. 1A, an intermediate crystal plate 2 is formed by processing the crystal vibrating piece 5 and the outer frame 6 of FIG. 17 by, for example, photoetching, excitation electrodes 7 and 8, wiring films 7a and 8a, conductive metal thin film 9, 10, 13 and a conductive film in the through hole are formed. The lower substrate 4 is processed into a desired outer shape shown in FIG. 19, and metal thin films 15 and 17 are formed on the upper surface of the lower substrate 4 in a region to be joined to the outer frame 6 of the intermediate crystal plate 2. In the present embodiment, the lower substrate 4 is made of quartz as in the case of the intermediate quartz plate 2 or can be made of a glass material.

  The conductive metal thin films 9, 10, 13 on the outer frame 6 of the intermediate crystal plate 2 and the conductive film in the through hole and the metal thin films 15, 17 on the lower substrate 4 are, for example, a Cr film, a Ni / Cr film, a Ti film, It is preferable to form a Ni—Cr film or a TiW film as a base film and an uppermost layer as an Au film. In particular, when the film thickness of these Au films is set to 5000 mm or more, bonding can be performed with high airtightness in a relatively short time under a low temperature condition of, for example, about 200 ° C. by diffusion bonding between the Au films. These metal thin films are easily formed by a known method such as sputtering, vapor deposition, plating, direct plating, or a combination thereof.

The lower surface of the intermediate crystal plate 2 and the upper surface of the lower substrate 4 are subjected to plasma processing using, for example, a known SWP RIE type plasma processing apparatus. This plasma processing apparatus generates plasma using, for example, microwaves of 13.56 MHz to 2.45 GHz, excites a reactive gas introduced into the processing chamber, and activates reactive species such as ions and excited species of the reactive gas. Is generated. As the reaction gas, Ar alone, CF ₄ , N ₂ alone, O ₂ alone, a mixed gas of O ₂ and N ₂ , or the like can be used.

  By this plasma treatment, the lower surface of the intermediate crystal plate 2 and the upper surface of the lower substrate 4 are exposed to the reactive gas active species to be uniformly cleaned and activated. That is, the metal thin films on the lower surface of the intermediate crystal plate 2 and the upper surface of the lower substrate 4 are etched and removed from the surfaces by organic substances, contaminants, dust, and the like by ions contained in the plasma, and further by radicals in the plasma. The surface state is improved so that it can be directly joined.

The plasma treatment can be performed by an atmospheric pressure plasma method or the like other than the SWP type RIE method described above. In another embodiment, each metal thin film can be surface activated by irradiating with an ion beam instead of plasma treatment. This ion beam treatment is performed by a known method using an inert gas such as Ar. For example, the bonding surface is irradiated with an Ar ₊ ion beam in a vacuum atmosphere of about 1.33 × 10 ₋₆ Pa.

  The intermediate crystal plate 2 and the lower substrate 4 subjected to the surface activation process are aligned and joined as shown in FIG. The bonding may be performed by simply bonding the intermediate crystal plate and the lower substrate, or by applying pressure with a weaker force than when the upper substrate 3 is bonded in a later step.

  Next, in this state, the frequency of the crystal vibrating piece 5 is measured, and the frequency is adjusted in accordance with the target frequency or frequency range (FIG. 1B). The frequency adjustment is performed by partially removing the electrode film of the excitation electrode 7 by dry etching that irradiates an ion beam or laser light, or by attaching a conductive material by vapor deposition or the like. At this time, if the outer frame is protected with an appropriate cover or the like, it is possible to prevent a part of the vapor deposition particles to be attached to the electrode material or the excitation electrode deleted from the electrode film from adhering to the joint surface of the outer frame.

  Next, as shown in FIG. 1C, the electrode cover 23 is placed on the excitation electrode 7 of the crystal vibrating piece 5. The electrode cover 23 is formed of a glass material such as quartz glass, borosilicate glass, or soda glass, or a thin plate of quartz so as to completely cover the excitation electrode 7 and at least in the same plane size and shape. In this state, the upper surface of the intermediate crystal plate 2 is plasma-treated in the same manner as described above with reference to FIG. Since the excitation electrode 7 covered with the electrode cover 23 is not subjected to plasma irradiation by this plasma treatment, the conductive metal thin film 9 on the upper surface of the outer frame 6 of the intermediate crystal plate 2 is not shifted without shifting the frequency of the crystal vibrating piece 5. It can be uniformly cleaned and activated, and modified to a surface state that facilitates direct bonding or diffusion bonding.

  Next, the electrode cover 23 is removed from the excitation electrode 7, and the upper substrate 4 is aligned and joined on the intermediate crystal plate 2 as shown in FIG. In the same manner as the bonding of the intermediate crystal plate 2 and the lower substrate 4, the intermediate crystal plate and the upper substrate are simply bonded together or pressed together with a weak force and laminated together, and then a strong pressing force is applied from above and below. In addition, the intermediate crystal plate and the bonding surfaces of the upper and lower substrates are bonded firmly and airtightly. At this time, when the pressure is applied in a state of being heated to a relatively low temperature of about 200 ° C., better bonding can be achieved. In addition, this bonding step can be similarly performed in an atmospheric pressure atmosphere or in a vacuum.

  When the upper substrate 3 and the lower substrate 4 are formed of the same crystal material as that of the intermediate crystal plate, they are formed and bonded so that their crystal plane orientations are the same. By matching the crystal plane orientations in this way, the bonded state of the crystal resonator can be maintained better.

  FIG. 2 shows a modification of the electrode cover used in the method of the present invention. The electrode cover 24 of this modification has a metal film 25 formed on the upper surface of the electrode cover 23 of FIG. 1 made of a glass material or a thin plate of quartz. The metal film 25 is formed by sputtering, vapor deposition, plating, or the like of the same metal material as the metal thin film on the lower surface of the intermediate crystal plate 2.

  In the process of FIG. 1C, since the electrode cover 23 is also subjected to plasma irradiation, the surface thereof is also etched, and the material removed thereby scatters around and adheres to the conductive metal thin film 9 on the upper surface of the intermediate crystal plate 2. There is a risk of doing. Therefore, when the upper substrate 3 is bonded to the intermediate crystal plate 2, the glass material attached to the conductive metal thin film 9 may affect the diffusion bonding between the metal thin films and reduce the bonding strength.

  In this embodiment, the same metal material adheres to the conductive metal thin film 9 by plasma irradiation, so that it has little influence on the diffusion bonding between the metal thin films, and a decrease in bonding strength can be suppressed. Furthermore, since the electrode cover 24 is opaque due to the metal film 25, the presence or absence and accurate alignment can be easily confirmed with eyes when the electrode cover 24 is placed on the excitation electrode 7 of the crystal vibrating piece 5.

  FIG. 3 shows another variation of the electrode cover used in the method of the present invention. The electrode cover 26 of this modification has the same or slightly larger plane dimension as that of the excitation electrode 7, and at least the same plane dimension as that of the excitation electrode 7, leaving a downward projection 27 on the lower surface on the lower surface. A recess 28 is formed. The protrusion 27 can be formed over the entire circumference of the lower surface of the electrode cover 26, and the inside thereof can be inclined downwardly in a tapered shape to reduce the contact area with the surface of the crystal vibrating piece 5.

  The electrode cover 26 of this embodiment can be placed on the crystal vibrating piece 5 so that the lower surface thereof does not contact the excitation electrode 7 by the recess 28. Thereby, it is possible to prevent the surface of the excitation electrode 7 from being contaminated by direct contact with the electrode cover 26 due to dirt or dust from the lower surface thereof, and to eliminate the possibility of affecting the frequency characteristics of the crystal vibrating piece 5. Can do.

  In still another modification, the metal film 25 shown in FIG. 2 can be formed on the surface of the electrode cover 26 shown in FIG.

  Next, a process of manufacturing a large number of crystal resonators shown in FIG. 16 in a batch using the method of the present invention will be described. First, as shown in FIG. 4, a large intermediate crystal wafer 30 is prepared in which a plurality of intermediate crystal plates 2 of FIG. 17 are continuously arranged in the vertical and horizontal directions. The shapes of the crystal vibrating piece 5 and the outer frame 6 of each intermediate crystal plate 2 are formed by, for example, photoetching the crystal wafer. The excitation electrode, the wiring film, and the conductive metal thin film are formed on the surfaces of the crystal vibrating pieces 5 and the outer frame 6 by forming a conductive material into a film by vapor deposition, sputtering, and patterning.

  In parallel with this, a large upper crystal wafer 31 is prepared in which a plurality of upper substrates 3 of FIG. 18 are continuously arranged in the vertical and horizontal directions. A metal thin film (not shown) corresponding to the metal thin film 14 on the lower surface of each upper substrate 3 is formed on the upper crystal wafer 31 on the surface facing the intermediate crystal wafer 30 by vapor deposition, sputtering, or the like.

  Similarly, a large lower crystal wafer 32 in which a plurality of lower substrates 4 in FIG. 19 are continuously arranged in the vertical and horizontal directions is prepared. On the lower crystal wafer 32, a metal thin film 33 corresponding to the metal thin film 14 on the upper surface of each lower substrate 4 is formed on the surface facing the intermediate crystal wafer 30 by vapor deposition, sputtering or the like. Furthermore, circular through-holes 35 are formed in the lower crystal wafer 32 at the intersections of the outlines of the lower substrate 4 perpendicular to the vertical and horizontal directions, respectively. On the lower surface of the lower crystal wafer 32, a conductive material is formed and patterned to form external electrodes 19 and 20 on the lower surface of the lower substrate 4.

  Next, the lower surface of the intermediate crystal wafer 30 and the upper surface of the lower crystal wafer 32 are subjected to plasma treatment, and the bonded surfaces thereof are uniformly cleaned and surface activated. As in the embodiment of FIG. 1, this plasma processing is performed using a known SWP type RIE plasma processing apparatus suitable for processing a large area of a wafer or the like. By this plasma treatment, the intermediate and lower quartz wafers are etched to remove organic substances, contaminants, dusts, and the like from their bonding surfaces, and modified to a surface state that facilitates direct bonding. The plasma treatment can also be performed by an atmospheric pressure plasma method or the like. In still another embodiment, each of the bonding surfaces can be surface activated by irradiation with an ion beam instead of the plasma treatment.

  The intermediate crystal wafer 30 and the lower crystal wafer 32 subjected to the surface activation treatment are bonded and bonded together as shown in FIG. This bonding is performed by simply bonding these wafers together or by applying pressure with a weaker force than when bonding the upper crystal wafer 31 in a later step.

  In this state, the frequency of each crystal vibrating piece 5 is measured. Therefore, the intermediate crystal wafer 30 is patterned so as to remove the conductive metal thin films on the upper surface and the lower surface of the outer frame 6 for each crystal resonator by the line width that is diced along the outline of the intermediate crystal plate 2. Similarly, the lower crystal wafer 32 is patterned so as to remove the metal thin films 15 and 17 of the lower substrate 4 for each crystal resonator by the line width to be diced along the outline. As a result, the excitation electrode of each crystal resonator can be electrically separated and independent from the excitation electrode of the adjacent crystal resonator in the wafer state, and the frequency can be measured and adjusted for each crystal resonator in that state. it can.

  Thus, the frequency of each crystal vibrating piece 5 is adjusted in the state of FIG. 5A in which the two crystal wafers 30 and 32 are joined. As in the embodiment of FIG. 1, the frequency adjustment is performed by partially removing the electrode film of the excitation electrode 7 by dry etching that irradiates an ion beam, laser light, or the like, or by attaching a conductive material by vapor deposition or the like. .

  Next, as shown in FIG. 5 (B), the electrode cover 23 of FIG. 1 (C) is disposed in each recess 36 of the tray 35. The recesses 36 are arranged on the upper surface of the tray 35 in accordance with the positions of the excitation electrodes 7 of the intermediate crystal wafer 30. The bonded quartz crystal wafers 30 and 32 of FIG. 5A are placed on the tray 35 and the intermediate quartz wafer 30 is placed downward, and the excitation electrodes 7 are aligned with the electrode cover 23 and overlapped. Then, when these are turned upside down and the tray is removed from the top of the intermediate crystal wafer 30, the electrode cover 23 is accurately placed on each excitation electrode 7 of the intermediate crystal wafer 30 as shown in FIG. The

  In the state of FIG. 5B, the upper surface of the intermediate crystal wafer 30 is subjected to plasma processing. This plasma treatment uniformly cleans and activates the conductive metal thin film 9 on the upper surface of the outer frame 6 of each intermediate crystal plate 2 without irradiating each excitation electrode 7 covered with the electrode cover 23 with plasma. It can be modified to a surface state that facilitates bonding.

  Next, the electrode cover 23 is removed from the intermediate crystal wafer 30 and, as shown in FIG. 5D, the upper crystal wafer 31 is aligned and bonded to the intermediate crystal wafer. In the same manner as the bonding of the intermediate crystal wafer 30 and the lower crystal wafer 32, the intermediate crystal wafer and the upper crystal wafer are simply bonded together or pressed together with a weak force and laminated together, and then the upper and lower surfaces thereof. A strong pressing force is evenly applied to firmly and airtightly bond the bonding surfaces. At this time, when the pressure is applied in a state of being heated to a relatively low temperature of about 200 ° C., better bonding can be achieved. In addition, this bonding step can be similarly performed in an atmospheric pressure atmosphere or in a vacuum.

  Finally, the crystal wafer laminate 37 bonded in this way is cut and divided by dicing or the like along the outline 38 of the crystal unit orthogonal to the length and width as shown in FIG. Turn into. After singulation, a conductive film is formed on the inner surfaces of the chips 21 and 22 of each lower substrate 4, and the external electrodes 19 and 20 on the lower surface of the lower substrate and the conductive metal thin films 10 and 13 on the lower surface of the intermediate crystal plate 2 are formed. Connect electrically. Thereby, the crystal unit 1 shown in FIG. 1 is completed. In another embodiment, the external electrodes on the bottom surface of the lower substrate 4 can be formed by sputtering or the like in a wafer laminated body state before dicing, thereby simplifying the process.

  In another embodiment, the electrode cover placed on the intermediate crystal wafer 30 is arranged in correspondence with the position of each piezoelectric vibration piece of the intermediate crystal wafer instead of the individual pieces separated for each piezoelectric vibration piece, and The structure can be integrally connected. In that case, if the portion connecting adjacent electrode covers overlaps the outer frame of each intermediate crystal plate, surface activation by plasma irradiation may be insufficient. For this reason, it is preferable that the connecting portion between the electrode covers is arranged so that a sufficient gap is provided above the intermediate crystal plate so that the active species and ion beam by plasma irradiation sufficiently wrap around. With the electrode cover having the integrated structure, mounting on the intermediate crystal wafer can be performed easily and in a short time.

  The method of the present invention can be similarly applied to a crystal resonator in which the intermediate crystal plate and the upper and / or lower substrate in the configuration of FIG. FIG. 6 shows an example of such an AT-cut crystal resonator in the thickness sliding mode. The crystal resonator 41 shown in FIG. 1 is formed by laminating upper and lower substrates 43 and 44 on the upper and lower surfaces of an intermediate crystal plate 42 and integrally and airtightly bonding the intermediate crystal plate. And an outer frame 46 integrally joined at the end 45a.

  As shown in FIG. 7A, the intermediate crystal plate 42 is joined to the upper substrate 43, including the longitudinal end of the outer frame 46 on the side where the crystal vibrating piece base end 45a is coupled. As it is, the crystal face is left as it is. The lower surface of the intermediate crystal plate 42 is configured in the same manner as in FIG. 17B, as shown in FIG. The excitation electrodes 47 and 48 of the quartz crystal vibrating piece 45 are respectively drawn out to the end portions in the longitudinal direction. One of the excitation electrodes 47 and 48 is the conductive metal thin film 49 on the upper surface of the outer frame 46, and the other 48 is Electrically connected. A through hole 51 is provided at the longitudinal end portion of the outer frame 46, and a conductive metal thin film 52 formed separately from the conductive metal thin film 50 on the lower surface of the longitudinal end portion through a conductive film inside the through hole. Are electrically connected to the conductive metal thin film 49 on the upper surface in the longitudinal direction.

  As shown in FIG. 8, a recess 53 is formed on the lower surface of the upper crystal substrate 43, that is, the surface facing the intermediate crystal plate 42. The peripheral portion surrounding the recess 53 on the lower surface of the upper crystal substrate 43 is made of a crystal element surface, and forms a bonding surface with the intermediate crystal plate 42. As shown in FIG. 9, a recess 54 is formed on the upper surface of the lower crystal substrate 44, that is, the surface facing the intermediate crystal plate 42. A peripheral portion surrounding the concave portion 15 of the lower crystal substrate 4 is made of a crystal element surface and constitutes a bonding surface with the intermediate crystal plate 42. The quartz crystal vibrating piece 45 is held and cantilevered at a base end portion 45a in a cavity 55 defined by the laminated intermediate crystal plate and the upper and lower substrates.

  Similarly, the crystal unit 41 is manufactured according to the same steps as those shown in FIGS. The lower surface of the intermediate crystal plate 42 and the upper surface of the lower substrate 44 are subjected to plasma treatment, cleaned and activated, and modified to a surface state that facilitates direct bonding. Next, the intermediate crystal plate 42 and the lower substrate 44 are aligned and overlapped, and airtightly bonded between the crystal element surface and the metal thin film. This bonding is performed by simply bonding the intermediate crystal plate and the lower substrate, or applying a weaker pressure than when bonding the upper substrate 43 in a later step.

  In this state, after measuring the frequency of the crystal vibrating piece 45, the electrode film of the excitation electrode 47 is partially deleted with an ion beam, laser light, or the like, or a conductive material is attached by vapor deposition or the like, so that the target frequency or Adjust the frequency to the frequency range. At this time, if the outer frame 46 of the intermediate crystal plate is protected by a suitable cover or the like, a part of the conductive material that is to be attached to the electrode material or excitation electrode that has been removed from the electrode film adheres to the joint surface of the outer frame. Can be prevented.

  Next, an electrode cover made of a glass material or a crystal thin plate is placed thereon so as to completely cover the excitation electrode 47 of the crystal vibrating piece 45 as in FIG. In this state, the upper surface of the intermediate crystal plate 42 is subjected to plasma treatment. By this plasma treatment, the upper surface of the outer frame 46 of the intermediate crystal plate 42 is uniformly cleaned and activated without shifting the frequency of the crystal vibrating piece 45, so that the surface state is improved to facilitate direct bonding.

  Next, the electrode cover is removed from the vibrating arm 47, and the upper substrate 43 is aligned and superposed on the intermediate crystal plate 42 in the same manner as in FIG. In the present embodiment, since the same quartz crystal is bonded, a more stable bonded state can be obtained. In this bonding, the intermediate crystal plate and the upper substrate are simply bonded or laminated together by applying a weak pressure, and then a strong pressing force is applied from above and below to bond firmly and airtightly. When heated and pressurized to a relatively low temperature of about 200 ° C., better bonding can be achieved. This bonding step can be performed similarly in an atmospheric pressure atmosphere or in a vacuum. Further, when the upper and lower substrates and the intermediate crystal plate are formed so as to have the same crystal plane orientation of the crystal, they can be maintained better than the bonded state.

  In another embodiment, in the embodiment of FIG. 6, the peripheral portion of the upper surface of the lower substrate 44, that is, the joint surface with the intermediate crystal plate 42 is covered with a metal thin film as in FIG. can do. In yet another embodiment, the lower surface of the outer frame 46 of the intermediate crystal plate 42 shown in FIG. 7B can be constituted by a crystal element surface, and the lower substrate 44 and the crystals can be bonded to each other.

  Of course, the electrode cover of FIG. 2 or 3 can also be used in the manufacture of the crystal unit of FIG. Also, as described above with reference to FIGS. 4 and 5, intermediate, upper and lower crystal wafers, each having a plurality of intermediate crystal plates 42, an upper substrate 43 and a lower substrate 44, are prepared, and these are converted into plasma. A large number of crystal resonators can be manufactured in a lump by separating them after surface activation and bonding by treatment.

  The method of the present invention can be similarly applied to a crystal resonator having a configuration different from the configurations of FIGS. 16 and 6 described above. For example, the quartz crystal vibrating piece 5 of the intermediate crystal plate 2 may be a tuning fork type vibrating piece instead of the thickness-slip mode vibrating piece.

  FIG. 10 shows a tuning fork type crystal resonator to which the method of the present invention can be applied. The tuning fork crystal unit 61 has a structure in which upper and lower substrates 63 and 64 are integrally laminated on the upper and lower surfaces of a flat intermediate crystal plate 62, respectively. The upper and lower substrates 63 and 64 are made of the same crystal as the intermediate crystal plate 62, and are directly and airtightly joined to the intermediate crystal plate.

  As shown in FIGS. 11A and 11B, the intermediate crystal plate 62 includes a tuning fork type crystal vibrating piece 65 and an outer frame 66 integrally coupled at the base end portion 65a. Excitation electrodes 68 and 69 are formed on the surfaces of a pair of vibrating arms 67 and 67 extending from the base end portion 65a of the quartz crystal vibrating piece 65, and are respectively pulled out from the base end portions, and the upper surface of the outer frame 66 and The conductive metal thin films 70 and 71 on the lower surface are electrically connected. A conductive metal thin film 72 separated from the conductive metal thin film 71 is formed on the lower surface of the end of the outer frame 66 on the side where the crystal vibration piece base end 65a is coupled, and a through hole 73 at the longitudinal end is formed. It is electrically connected to the conductive metal thin film 70 on the upper surface through an internal conductive film.

  As shown in FIGS. 12 and 13, the upper and lower substrates 63 and 64 of this embodiment are formed with recesses 74 and 75 on the surface facing the intermediate crystal plate 62, respectively, and surrounding portions, that is, intermediate portions surrounding these recesses. The joint surfaces 63a and 64a with the crystal plate 62 are crystal surfaces. The lower substrate 64 has a sealing hole 76 penetrating substantially at the center thereof. Other configurations are the same as those of the upper and lower substrates 3 and 4 in FIGS. The crystal vibrating piece 65 is held and cantilevered at the base end portion 65a in the cavity 77 defined by the concave portion.

  The crystal unit 61 can be manufactured by the same steps as those shown in FIGS. 1A to 1D according to the method of the present invention. First, the lower surface of the intermediate crystal plate 62 and the upper surface of the lower substrate 64 are subjected to plasma processing by a known plasma processing apparatus, cleaned and activated, and modified to a surface state that is easy to directly bond. Next, the intermediate crystal plate 62 and the lower substrate 64 are aligned and overlapped, and airtightly bonded between the crystal element surface and the metal thin film. This bonding is performed by simply bonding the intermediate crystal plate and the lower substrate, or by applying a weaker pressure than when bonding the upper substrate 63 in a later step.

  In this state, after measuring the frequency of the crystal vibrating piece 65, the frequency is adjusted according to the target frequency or frequency range. The frequency adjustment is performed by partially deleting the weight made of the electrode film formed at the tip of the vibrating arm 67 with an ion beam, laser light, or the like. At this time, if the outer frame 66 of the intermediate crystal plate is protected with a suitable cover or the like, the electrode material removed from the weight can be prevented from adhering to the joint surface of the outer frame.

  Next, an electrode cover made of a glass material or a crystal thin plate is placed thereon so as to completely cover the vibrating arm 67 of the crystal vibrating piece 65 as in FIG. In this state, the upper surface of the intermediate crystal plate 62 is plasma-treated as described above. By this plasma treatment, the conductive metal thin film 70 on the upper surface of the outer frame 66 of the intermediate crystal plate 62 is uniformly cleaned and activated without shifting the frequency of the crystal vibrating piece 65, so that the surface state is improved to facilitate direct bonding. Quality.

  Next, the electrode cover is removed from the vibrating arm 67, and the upper substrate 63 is aligned and superimposed on the intermediate crystal plate 62 in the same manner as in FIG. 1D, and the crystal face and the metal thin film are hermetically bonded. To do. In this bonding, the intermediate crystal plate and the upper substrate are simply bonded or laminated together by applying a weak pressure, and then a strong pressing force is applied from above and below to bond firmly and airtightly. When heated and pressurized to a relatively low temperature of about 200 ° C., better bonding can be achieved. This bonding step can be performed similarly in an atmospheric pressure atmosphere or in a vacuum. Further, when the upper substrate 63 and the lower substrate 64 and the intermediate crystal plate 62 are formed and bonded so that the crystal plane orientations of the crystals are the same, they can be maintained better than the bonded state.

  After the upper and lower substrates 63 and 64 and the intermediate crystal plate 62 are joined, a sealing material 78 made of a low melting point metal material such as Au—Sn is welded to close the sealing hole 76. Thereby, the inside of the cavity 77 of the crystal unit 61 is hermetically sealed and maintained in a desired vacuum state or atmosphere.

  FIG. 14 shows tuning fork type crystal resonators of different configurations to which the method of the present invention can be applied. As in the embodiment of FIG. 10, the crystal resonator 81 has upper and lower substrates 83 and 84 integrally laminated on the upper and lower surfaces of the intermediate crystal plate 82. As shown in FIGS. 15A and 15B, the intermediate crystal plate 82 includes a tuning fork type crystal vibrating piece 85 and an outer frame 86 integrally coupled at the base end portion 85a. This is different from the configuration of FIG.

  In the intermediate crystal plate 82, the upper surface of the outer frame 86 is left as it is, and the conductive film as shown in FIG. 11A is not formed. At the end in the longitudinal direction of the outer frame 86 on the side where the crystal vibrating piece base end 85 a is coupled, a region of the crystal element surface is left with a sufficient width as a bonding surface with the upper substrate 83 along the periphery. One of the excitation electrodes 88 and 89 formed on the vibrating arm 87 of the crystal vibrating piece 85 is drawn to the end in the longitudinal direction on the upper surface of the outer frame 86, and is electrically connected to the conductive metal thin film 90 formed inside the crystal element surface region. Connected.

  The lower surface of the intermediate crystal plate 82 is configured in the same manner as in FIG. 11B, and the other excitation electrode 89 is drawn out to the end in the longitudinal direction and electrically connected to the conductive metal thin film 91 on the lower surface of the outer frame. ing. A conductive metal thin film 92 separated from the conductive metal thin film 91 is formed on the lower surface of the outer edge 86 in the longitudinal direction. The conductive metal thin film 90 and the conductive metal thin film 90 are interposed through the conductive film inside the through hole 93 at the longitudinal end. Electrically connected.

  The upper and lower substrates 83 and 84 have the same configuration as the upper and lower substrates 63 and 64 in FIGS. The quartz crystal vibrating piece 85 is held and cantilevered at the base end portion 85a in the cavity 96 defined by the concave portions 94 and 95 of the upper and lower substrates 83 and 84.

  Similarly, the crystal resonator 81 can be manufactured according to the same steps as those in FIGS. The lower surface of the intermediate crystal plate 82 and the upper surface of the lower substrate 84 are subjected to plasma processing by a known plasma processing apparatus, cleaned and activated, and modified to a surface state that can be easily joined directly. Next, the intermediate crystal plate 82 and the lower substrate 84 are aligned and overlapped, and airtightly bonded between the crystal element surface and the metal thin film. This bonding is performed by simply bonding the intermediate crystal plate and the lower substrate, or by applying a weaker pressure than when bonding the upper substrate 83 in a later step.

  In this state, after measuring the frequency of the crystal vibrating piece 85, the weight made of the electrode film at the tip of the vibrating arm 87 is partially deleted with an ion beam, laser light, or the like, so that the frequency is adjusted to the target frequency or frequency range. adjust. At this time, if the outer frame 86 of the intermediate crystal plate is protected with a suitable cover or the like, the electrode material removed from the weight can be prevented from adhering to the joint surface of the outer frame.

  Next, an electrode cover made of a glass material or a quartz crystal plate is placed on the vibrating arm 87 of the quartz crystal vibrating piece 85 in the same manner as in FIG. In this state, the upper surface of the intermediate crystal plate 82 is plasma-treated as described above. By this plasma treatment, the upper surface of the outer frame 86 of the intermediate crystal plate 82 is uniformly cleaned and activated without shifting the frequency of the crystal vibrating piece 65, so that the surface state is improved to be easily joined.

  Next, the electrode cover is removed from the vibrating arm 87, and the upper substrate 83 is aligned and superimposed on the intermediate crystal plate 82 in the same manner as in FIG. In the present embodiment, since the same quartz crystal is bonded, a more stable bonded state can be obtained. In this bonding, the intermediate crystal plate and the upper substrate are simply bonded or laminated together by applying a weak pressure, and then a strong pressing force is applied from above and below to bond firmly and airtightly. When heated and pressurized to a relatively low temperature of about 200 ° C., better bonding can be achieved. This bonding step can be performed similarly in an atmospheric pressure atmosphere or in a vacuum. Further, when the upper substrate 83 and the lower substrate 84 and the intermediate crystal plate 82 are formed and bonded so that the crystal plane orientations of the crystals are the same, they can be maintained better than the bonded state.

  After the upper and lower substrates 83, 84 and the intermediate crystal plate 82 are joined, a sealing material 98 made of a low melting point metal material such as Au-Sn is welded to the sealing hole 97 provided in the lower substrate 84. Obstruction. As a result, the inside of the cavity 96 of the crystal resonator 81 is hermetically sealed and maintained in a desired vacuum state or atmosphere.

  Further, in another embodiment, in the embodiment of FIG. 14, the peripheral portion surrounding the recess 95 of the lower substrate 84, that is, the bonding surface with the intermediate crystal plate 82 is not a crystal face but a metal thin film as in FIG. It can be coated and bonded between thin metal films. In yet another embodiment, in the intermediate crystal plate 82 of FIG. 15B, the lower surface of the outer frame 86 to be joined to the lower substrate 84 can be composed of a crystal face, and the crystals can be joined together.

  Naturally, the electrode cover of FIG. 2 or 3 can also be used in the production of the tuning fork type crystal resonator of FIGS. Further, as described above with reference to FIGS. 4 and 5, the middle, upper and lower crystal wafers in which the plurality of intermediate crystal plates 62 and 82, the upper substrates 63 and 83 and the lower substrates 64 and 84 are arranged, respectively. A plurality of tuning fork type crystal resonators can be manufactured in a lump by preparing them, surface-activating them by plasma treatment and joining them, and then separating them into individual pieces.

  In another embodiment, the present invention can be applied to a crystal resonator having a different structure. For example, the outer frame of the intermediate crystal plate is thicker than the quartz crystal vibrating piece on one of the upper surface side or the lower surface side, the upper or lower substrate on the opposite side is formed of a flat plate, and the lower or upper side opposite to it A quartz resonator having a structure in which a cavity for accommodating a quartz crystal resonator element is defined by forming a concave portion on the surface of the substrate facing the intermediate quartz plate can also be manufactured by applying the present invention in the same manner.

  The preferred embodiments of the present invention have been described in detail above. However, as will be apparent to those skilled in the art, the present invention can be implemented by adding various changes and modifications to the above embodiments within the technical scope thereof. For example, in the above embodiment, the intermediate crystal plate and the lower substrate are bonded first, but in another embodiment, the intermediate crystal plate and the upper substrate are bonded in the previous step, and the intermediate crystal plate and the lower substrate are bonded. Can be joined in a later step. Further, the intermediate crystal plate can be formed of various other known piezoelectric materials such as lithium tantalate and lithium niobate.

FIGS. 4A to 4D are cross-sectional views showing a process of manufacturing a crystal resonator by the method of the present invention in the order of steps. The expanded sectional view which shows the modification of an electrode cover in the use condition. The expanded sectional view which shows another modification of an electrode cover in the use condition. The schematic perspective view which shows three crystal wafers bonded together in the manufacturing process of the crystal oscillator by the method of this invention. (A)-(E) is a schematic diagram showing the process of bonding three quartz wafers in the order of steps by the method of the present invention. FIG. 17 is a cross-sectional view showing a crystal resonator different from FIG. 16 to which the method of the present invention can be applied. (A) is a top view of the intermediate crystal plate of FIG. 6, and (B) is a bottom view thereof. FIG. 7 is a bottom view of the upper crystal substrate of FIG. 6. FIG. 7 is a top view of the lower crystal substrate of FIG. 6. Sectional drawing which shows the tuning fork type | mold crystal resonator which can apply the method of this invention. (A) is a top view of the intermediate crystal plate of FIG. 10, and (B) is a bottom view thereof. FIG. 11 is a bottom view of the upper crystal substrate of FIG. 10. FIG. 11 is a top view of the lower crystal substrate of FIG. 10. Sectional drawing which shows the tuning fork type | mold crystal resonator of another structure which can apply the method of this invention. (A) is a top view of the intermediate crystal plate of FIG. 14, and (B) is a bottom view thereof. (A) is a side view showing a conventional crystal resonator, (B) is a longitudinal sectional view thereof, and (C) is a bottom view thereof. (A) is a top view of the intermediate crystal plate of FIG. 16, and (B) is a bottom view thereof. FIG. 17 is a bottom view of the upper crystal substrate of FIG. 16. FIG. 17 is a top view of the lower crystal substrate of FIG. 16.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,41,61,81 ... Crystal oscillator, 2,42,62,82 ... Intermediate crystal plate, 3,43,63,83 ... Upper substrate, 4,44,64,84 ... Lower substrate, 5,45 , 65, 85... Crystal vibrating piece, 5a, 45a, 65a, 85a... Base end portion, 6, 46, 66, 86. Outer frame, 7, 8, 47, 48, 68, 69, 88, 89. 7a, 8a ... wiring film, 9, 10, 13, 33, 49, 50, 52, 70-72, 90-92 ... conductive metal thin film, 11, 51, 53, 73, 93 ... through hole, 12, 16 ... region 14, 15, 17, 33 ... metal thin film, 19, 20 ... external electrode, 21, 22 ... chip, 23, 24, 26 ... electrode cover, 25 ... metal film, 27 ... projection, 28 ... dent, 30 ... Intermediate crystal wafer, 31 ... Upper crystal wafer, 32 ... Lower crystal wafer, 34 ... Through hole 35 ... Tray, 36 ... Recess, 37 ... Wafer laminated body, 38 ... Outline, 67,87 ... Vibrating arm, 74,75,94,95 ... Recess, 76,97 ... Sealing hole, 53,77,96 ... cavity, 78, 98 ... seal material.

Claims (12)

A step of forming an intermediate piezoelectric plate integrally bonding the piezoelectric vibrating piece and the outer frame; a step of forming a lower substrate having a bonding surface with the lower surface of the outer frame; and a bonding surface between the upper surface of the outer frame and Forming an upper substrate having: a step of bonding one of the lower substrate or the upper substrate to the intermediate piezoelectric plate at the outer frame; and the intermediate piezoelectric bonding the one of the lower substrate or the upper substrate. Adjusting the frequency of the piezoelectric vibrating piece of the plate, and after adjusting the frequency of the piezoelectric vibrating piece, joining the other of the lower substrate or the upper substrate to the intermediate piezoelectric plate in the outer frame. In the method of manufacturing a piezoelectric vibrator in which the piezoelectric vibrating piece is hermetically sealed in a cavity defined between the intermediate piezoelectric plate and the upper and lower substrates.
Before the step of bonding the other of the lower substrate and the upper substrate, the step of surface activating the upper surface or the lower surface of the outer frame of the intermediate piezoelectric plate to be bonded, and before the surface activation step A step of placing an electrode cover on the piezoelectric vibrating piece of the intermediate piezoelectric plate to which the one of the lower substrate or the upper substrate is bonded, and the lower substrate or the upper substrate after the surface activation step. A method of manufacturing a piezoelectric vibrator, further comprising a step of removing the electrode cover from the top of the piezoelectric vibrating piece before the step of bonding the other of the substrates. Forming an intermediate piezoelectric wafer having a plurality of the intermediate piezoelectric plates; forming an upper wafer in which the plurality of upper substrates are arranged corresponding to the intermediate piezoelectric plates of the intermediate piezoelectric wafer; A step of forming a lower wafer in which a lower substrate is disposed corresponding to the intermediate piezoelectric plate of the intermediate piezoelectric wafer, and one of the lower or upper wafers is overlapped on the lower surface or the upper surface of the intermediate piezoelectric wafer. A step of individually bonding the frequency of the piezoelectric vibrating piece of each of the intermediate piezoelectric plates of the intermediate piezoelectric wafer, and the other of the upper and lower wafers overlaid on the upper surface or the lower surface of the intermediate piezoelectric wafer. And integrally bonding, and cutting the bonded laminate of the wafers to singulate a plurality of piezoelectric vibrators,
Before the step of bonding the lower wafer or the other of the upper wafers, surface activation of the upper surface or the lower surface of each outer frame of the intermediate piezoelectric wafer to be bonded; and the surface activation step A step of placing an electrode cover on each of the piezoelectric vibrating reeds of the intermediate piezoelectric wafer to which the one of the lower wafer or the upper wafer is bonded, and the lower side after the surface activation step. 2. The method of manufacturing a piezoelectric vibrator according to claim 1, further comprising a step of removing the electrode cover from above each of the piezoelectric vibrating reeds before the step of bonding the other of the wafer and the upper wafer. Method.   The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrating piece is made of quartz. The intermediate piezoelectric plate has a metal thin film on the upper surface and the lower surface of the outer frame, the lower substrate has a metal thin film on the bonding surface with the lower surface of the outer frame, and the upper substrate has an outer frame of the outer frame. A metal thin film on the joint surface with the upper surface;
The intermediate piezoelectric plate and the upper substrate and the lower substrate are bonded by direct bonding or diffusion bonding between the metal thin film on the upper and lower surfaces of the outer frame and the metal thin film on the upper substrate and the lower substrate. The method for manufacturing a piezoelectric vibrator according to any one of claims 1 to 3. The intermediate piezoelectric plate has metal thin films on the upper and lower surfaces of the outer frame, the lower substrate is made of crystal, the bonding surface with the lower surface of the outer frame is a crystal element surface, and the upper substrate is made of crystal. And the joint surface with the upper surface of the outer frame is a crystal face,
The intermediate piezoelectric plate and the upper substrate and the lower substrate are bonded by direct bonding between the metal thin films on the upper surface and the lower surface of the outer frame and the crystal surfaces of the upper substrate and the lower substrate. A method for manufacturing a piezoelectric vibrator according to any one of claims 1 to 3. The lower substrate, the intermediate piezoelectric plate, and the upper substrate are made of crystal, one of the upper surface or the lower surface of the outer frame of the intermediate piezoelectric plate has a metal thin film, and the other of the upper surface or the lower surface of the outer frame is a crystal. Is a raw surface, and the bonding surface with the lower surface and the upper surface of the outer frame of the upper and lower substrates is a crystal surface,
The intermediate piezoelectric plate and the upper and lower substrates are bonded by direct bonding between the metal thin film and the crystal element surfaces on the upper and lower surfaces of the outer frame and the crystal element surfaces of the upper and lower substrates. The method for manufacturing a piezoelectric vibrator according to claim 1, wherein: The lower substrate, the intermediate piezoelectric plate, and the upper substrate are made of crystal, the upper and lower surfaces of the outer frame of the intermediate piezoelectric plate are crystal surfaces, and the lower and upper surfaces of the outer frame of the upper and lower substrates The bonding surface is a quartz surface,
The intermediate piezoelectric plate and the upper and lower substrates are bonded by direct bonding between the crystal elements on the upper and lower surfaces of the outer frame and the crystal elements on the upper and lower substrates. The method for manufacturing a piezoelectric vibrator according to claim 1.   The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the lower substrate, the intermediate piezoelectric plate, and the upper substrate are made of quartz and are bonded to each other in the same crystal plane orientation.   The method of manufacturing a piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrating piece is a vibration piece in a thickness-shear vibration mode.   9. The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrating piece is a tuning fork type vibrating piece.   The electrode cover has a metal film of the same type as the metal thin film of the outer frame, the upper substrate or the lower substrate on a surface opposite to the excitation electrode when placed on the piezoelectric vibrating piece. The method for manufacturing a piezoelectric vibrator according to claim 1, wherein:   The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the electrode cover has a recess having a planar dimension equal to or larger than that of the excitation electrode on a surface on the excitation electrode side.

Images