JP4978030B2 - Piezoelectric device - Google Patents

Description

The present invention relates to a piezoelectric device in which a piezoelectric vibrating piece is hermetically accommodated in a package.

  Conventionally, piezoelectric vibrators such as crystal vibrators have been used in various information / communication equipment, OA equipment, and electronic equipment such as consumer equipment. In particular, these electronic devices have become increasingly smaller and thinner along with higher functionality, and with this, the demand for smaller and thinner piezoelectric vibrators has also increased, making them suitable for mounting on circuit boards. Often used are surface mount types. In general, surface-mount type piezoelectric vibrators are widely employed in a structure in which a piezoelectric vibrating piece is sealed in a package made of an insulating material such as ceramic. In the conventional package structure, the package base and the lid are joined by melting low-melting glass or seam welding. Therefore, the frequency characteristics of the piezoelectric vibrating piece are deteriorated or deteriorated due to the high temperature in the joining or the outer gas generated. There is a risk of causing it.

  As a piezoelectric vibrator that solves these problems, a crystal piece (intermediate piezoelectric plate), in which a crystal vibrating piece and a frame are integrally formed, and a pair of lids made of crystal are optically bonded (surface activation) There has been proposed a crystal resonator bonded using a bonding method (for example, Patent Document 1). Optical bonding is performed by, for example, mirror-polishing the bonding-corresponding surfaces of two glasses mainly composed of Si (silicon), then abutting them and applying pressure to bond them by Si bonding (interatomic bonding) on the abutting surfaces. Therefore, it is possible to join them with little heating. The crystal resonator described in Patent Document 1 has excitation electrodes on both main surfaces of a crystal resonator element, and each excitation electrode is drawn out to the outer peripheral portion of the frame body in the opposite direction to form a lead electrode. On the other hand, the pair of lids has a recess provided so that the excitation electrode and each lid do not touch, and a through hole provided at a position corresponding to the lead electrode on the outer peripheral portion of the crystal plate. Each has a hole (through hole). The bonding surfaces of the pair of lids and crystal pieces are polished to a mirror surface state, and then bonded to each other by bringing them into contact with each other and applying pressure. Then, by embedding a conductive bonding material such as solder in the through hole and connecting it to each lead electrode of the crystal piece, and simultaneously sealing the through hole (through hole), the crystal vibrating piece is hermetically sealed by a pair of lids. A sealed crystal unit is formed.

JP 2000-269775 A

However, in the structure of the crystal resonator (piezoelectric resonator) described in Patent Document 1, a gap is formed by a concave portion of the lid body between the through hole (through hole) of the lid body and the lead electrode of the crystal plate. . For this reason, when a conductive bonding material such as solder is embedded in the through hole, there is a possibility that the solder is not sufficiently embedded up to the lead electrode and a conduction failure is caused. In addition, when the molten solder spreads from the extraction electrode to the excitation electrode, there is a problem that the vibration characteristics of the quartz crystal resonator element deteriorate.
The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the size and thickness by joining the upper and lower substrates to an intermediate piezoelectric plate in which the piezoelectric vibrating piece and the frame are integrally formed. In a piezoelectric vibrator that has been made possible, it is possible to suppress warpage by reducing the temperature at the time of bonding, or to suppress deterioration of frequency characteristics, to ensure airtightness, and to make electrical connection between the piezoelectric vibrating piece and the upper and lower substrates. It is an object of the present invention to provide a piezoelectric vibrator that realizes a structure that can be surely taken and a manufacturing method thereof.

In order to achieve the above object, a piezoelectric device according to a first aspect of the present invention includes an intermediate piezoelectric element having a piezoelectric vibrating piece provided with an excitation electrode and a frame body disposed so as to surround the piezoelectric vibrating piece. A plate, an upper substrate laminated on the upper main surface of the intermediate piezoelectric plate and bonded by direct bonding, and a lower substrate laminated on the lower main surface of the intermediate piezoelectric plate and bonded by direct bonding. A first recess is provided on a main surface of the upper substrate on the side laminated with the intermediate piezoelectric plate so as to include a region facing the piezoelectric vibrating piece, and the intermediate piezoelectric plate of the lower substrate The main surface on the side laminated with the piezoelectric resonator element is provided with a second recess so as to include a region facing the piezoelectric vibrating piece, and both the main surfaces of the frame body of the intermediate piezoelectric plate have the excitation electrode and The first and second lead electrodes electrically connected to each other are arranged, and the frame body The first lead electrode disposed on the main surface on which the upper substrate is laminated includes a first conductive film provided on an inner wall of a first through hole disposed in the frame body, and the first conductive electrode. The first and second through holes are filled with a second conductive film provided on the inner wall of the second through hole disposed in the thick part of the lower substrate so as to communicate with the through hole By electrically connecting with the conductive material made, it is electrically joined to the first external connection terminal arranged on the opposite side of the surface to be joined to the frame body of the thick part of the lower substrate, The second lead electrode disposed on the main surface of the frame on the side where the lower substrate is laminated has both main holes of two frame through-holes penetrating the frame and provided with a conductive film on the inner wall. among the openings of the surface, connecting the opening portions located on the main surface of the frame of the first lead-out electrode is disposed side Electrically connected with poles of the opening of the two frame bodies through hole of said second lead electrodes are arranged side causes the one opening connected to the second lead electrode in electrical The second opening provided on the lower substrate is electrically connected to the third conductive film provided on the inner wall of the third through hole disposed in the thick portion of the lower substrate. The external connection terminal is electrically connected to the second lead electrode by being electrically connected to the third conductive film, and is connected to the thick portion of the upper substrate on the side in contact with the frame body. The inner bottom surface of the first recess is disposed in a region facing the first extraction electrode and the connection electrode, and the first extraction electrode and the connection electrode of the thick portion of the upper substrate The main surface outside the facing region is joined to the frame body by direct joining, and the lower base An inner bottom surface of the second recess is disposed in a region facing the second extraction electrode in a thick portion of the plate that contacts the frame body, and the thick portion of the lower substrate The main surface outside the region facing the second extraction electrode is bonded to the frame body by direct bonding.
The piezoelectric device according to a second aspect of the present invention is characterized in that the intermediate piezoelectric plate and the upper and lower substrates are made of quartz.
The piezoelectric device according to a third aspect of the present invention is characterized in that the upper and lower substrates are made of glass material or silicon.
[Application Example 1] A piezoelectric vibrator according to Application Example 1 includes an intermediate piezoelectric plate integrally formed with a piezoelectric vibrating piece having excitation electrodes provided on both main surfaces and a frame, and an upper surface and a lower surface of the intermediate piezoelectric plate. The piezoelectric vibrating piece is held in a cavity defined by the intermediate piezoelectric plate and the upper and lower substrates, and each of the upper and lower substrates and the intermediate piezoelectric plate. Each of the bonding surfaces is mirror-polished and hermetically bonded by direct bonding to each other, and each excitation electrode is connected to a connection portion with the upper and lower substrates provided on the frame body via an extraction electrode, and is connected to the upper and lower surfaces. Substrate through holes electrically connected to external connection terminals provided on at least one of the upper and lower substrates are provided at positions corresponding to the connecting portions of the side substrates, and each substrate through hole is provided in each of the substrate through holes. Conductive contact A piezoelectric vibrator having a structure in which each excitation electrode and an external connection terminal are electrically connected by embedding a material, and each connection portion of the frame is opposed by a frame through-hole formed through the frame The main purpose is to conduct with the excitation electrode formed on the side.

  According to this configuration, the connection for connecting each of the excitation electrodes provided on both main surfaces of the piezoelectric vibrator of the intermediate piezoelectric plate to the external connection electrode provided on at least one of the upper and lower substrates Are provided on each joint surface of the intermediate piezoelectric plate with the upper and lower substrates. The substrate through-holes of the upper and lower substrates formed corresponding to the respective connecting portions are provided as separate spaces that do not communicate with the recesses of the upper and lower substrates in the piezoelectric vibrator. In addition, each substrate through hole of the upper and lower substrates is in a state of surrounding each connection portion at the joint surface with the intermediate piezoelectric plate. Thereby, by burying a conductive bonding material in each substrate through-hole, it is possible to achieve a good electrical connection with each of the connection portions, and the conductive bonding material is not originally desired for each excitation electrode or the like. It does not spread over the area. Accordingly, it is possible to provide a piezoelectric vibrator that ensures airtightness and enables reliable electrical connection with the excitation electrode.

Application Example 2 A piezoelectric vibrator according to Application Example 2 includes an intermediate piezoelectric plate in which a piezoelectric vibrating piece provided with excitation electrodes on both main surfaces and a frame are integrally formed, and an upper surface and a lower surface of the intermediate piezoelectric plate. And the piezoelectric vibrating piece is held in a cavity defined by the intermediate piezoelectric plate and the upper and lower substrates, and the upper and lower substrates and the intermediate piezoelectric plate are connected to each other. Each bonding surface is mirror polished, and is airtightly bonded by direct bonding to each other, and each excitation electrode is connected to a connection portion with either the upper or lower substrate provided in the frame body via a lead electrode, A substrate through hole electrically connected to an external connection terminal provided on at least one of the upper and lower substrates is provided at a position corresponding to at least one of the connection portions of the upper and lower substrates. Conductive contact A piezoelectric vibrator having a structure in which each excitation electrode and an external connection terminal are electrically connected by embedding a material, wherein one connection portion of the frame is formed by a frame through-hole formed through the frame Conduction with one excitation electrode formed on the opposite side, and the other connection portion is connected with the other excitation electrode side by reciprocating through an even number of frame through holes formed through the frame Is desirable.

  According to this configuration, the excitation electrodes provided on both main surfaces of the piezoelectric vibrator of the intermediate piezoelectric plate are electrically connected to the main surface opposite to the formation surface of each excitation electrode through the frame through-hole. One of them is directly connected to a connection portion formed on the frame body, and the other is connected to a connection portion formed on the frame body through an even number of through holes provided in the frame body. . That is, one connection portion is provided on the main surface opposite to the corresponding excitation electrode formation surface, and the other connection portion is provided on the frame on the corresponding excitation electrode formation surface side. Thus, the substrate through-hole for connecting to the external connection electrode may be provided in either one of the upper and lower substrates, and a wafer in which a large number of intermediate piezoelectric plates, upper and lower substrates are formed. Since the batch manufacturing can be easily performed in the state, the manufacturing efficiency of the piezoelectric vibrator can be improved. The substrate through-hole is provided as another space that does not communicate with the concave portions of the upper and lower substrates inside the piezoelectric vibrator. In addition, each substrate through hole of the upper and lower substrates is in a state of surrounding each connection portion at the joint surface with the intermediate piezoelectric plate. Thus, by burying the conductive bonding material in each substrate through hole, it is possible to achieve good electrical connection with each of the connection portions. In addition, since the conductive bonding material does not wet and spread to parts that are not originally desired such as the respective excitation electrodes, it is possible to prevent the deterioration of the vibration characteristics due to the conductive bonding material. Therefore, it is possible to provide a highly reliable piezoelectric vibrator having desired vibration characteristics.

Application Example 3 In the piezoelectric vibrator according to Application Example 3, it is preferable that the intermediate piezoelectric plate and the upper and lower substrates are made of quartz.

  According to this configuration, since the intermediate piezoelectric plate made of quartz widely used as the material of the piezoelectric vibrator and the upper and lower substrates are made of the same material, there is no problem of residual stress due to the difference in thermal expansion coefficient. The interatomic bond is easily formed. Thereby, a favorable joining state can be obtained at normal temperature or a relatively low joining temperature. Therefore, the dimensional change and warpage during bonding can be reduced, the shift of the bonding position of each substrate can be suppressed, and high bonding strength can be ensured.

Application Example 4 The piezoelectric vibrator according to Application Example 4 may be configured such that the upper and lower substrates are made of glass material or silicon.

  Quartz can be bonded directly by the interatomic bonding of silicon (Si), which is the main component, even in combination with different glass materials or silicon. It is possible to secure a good bonding state by suppressing warping due to the difference in rate. Moreover, since glass material or silicon is relatively inexpensive, cost reduction can be achieved.

Application Example 5 In the piezoelectric vibrator manufacturing method according to Application Example 5, excitation electrodes are formed on the upper and lower surfaces of the piezoelectric vibrating piece integrated with the frame, and the upper and lower surfaces of the frame are not joined. The lead electrodes connected to the respective excitation electrodes are respectively formed, the frame through holes penetrating the frame body are formed from the respective lead electrodes, and the connection portions connected to the lead electrodes through the frame through holes are respectively formed. Forming an intermediate piezoelectric plate and forming a substrate through hole corresponding to a joint provided on the upper surface side of the intermediate piezoelectric plate to form an upper substrate bonded to the upper surface of the intermediate piezoelectric plate Forming a substrate through hole corresponding to a joint provided on the lower surface side of the intermediate piezoelectric plate to form a lower substrate to be bonded to the lower surface side of the intermediate piezoelectric plate; Side board and A step of mirror-polishing each bonding surface, a step of activating each bonding surface between the mirror-polished upper and lower substrates and the intermediate piezoelectric plate, and an intermediate piezoelectric plate and the upper and lower substrates. , The step of superposing the piezoelectric vibrating reeds in the cavity defined by them, pressurizing them and airtightly bonding them by direct bonding, and conductive bonding material in each substrate through hole of the upper and lower substrates And the step of embedding.

  According to this configuration, the upper and lower substrates and the intermediate piezoelectric plate are directly bonded to each other, so that the size and thickness can be reduced, airtightness can be secured, and the electrical connection with the excitation electrode can be ensured. The vibrator can be manufactured relatively easily and at low cost.

Application Example 6 A method for manufacturing a piezoelectric vibrator according to Application Example 6 includes a step of forming an intermediate piezoelectric wafer having a plurality of intermediate piezoelectric plates, and a plurality of upper substrates corresponding to the intermediate piezoelectric plates of the intermediate piezoelectric wafer. A step of forming a disposed upper wafer, a step of forming a lower wafer in which a plurality of lower substrates are disposed in correspondence with the intermediate piezoelectric plate of the intermediate piezoelectric wafer, and the intermediate piezoelectric wafer, the upper and lower wafers, A step of mirror-polishing each bonding surface, a step of activating each bonding surface between the mirror-polished upper and lower wafers and the intermediate piezoelectric wafer, and upper and lower surfaces on the upper and lower surfaces of the intermediate piezoelectric wafer. A step of superimposing the side wafers, pressurizing them and joining them together directly by direct bonding to form a wafer laminate, a step of embedding a conductive bonding material in each through-hole of the upper and lower wafers, and a wafer laminate Turn off It is preferable that a step of singulating the piezoelectric vibrator by.

  According to this configuration, since a large number of piezoelectric vibrators can be manufactured at the same time, productivity can be improved and costs can be reduced.

Application Example 7 In the piezoelectric vibrator manufacturing method according to Application Example 7, in each process of forming the upper and lower substrates, a conductive bonding material is embedded in the through holes provided in the upper and lower substrates. A process may be included.

  According to this configuration, when a material that requires heating, such as solder, is used as the conductive bonding material, temperature stress due to solder reflow is applied after the intermediate piezoelectric substrate, the upper and lower substrates are bonded. Therefore, it is possible to avoid problems such as deterioration of the bondability. Also, when the upper and lower substrates and the intermediate piezoelectric plate are made of different materials, each substrate warps due to reflow heating due to the difference in thermal expansion coefficient, stress is applied to the joint, and the bonding strength is changed. We can suppress trouble.

Application Example 8 In the method for manufacturing a piezoelectric vibrator according to Application Example 8, it is preferable that the plasma treatment is performed in an oxygen-free atmosphere using CF ₄ , Ar, or N ₂ gas.

  According to this configuration, by performing plasma treatment in an inert atmosphere, surface activation by the plasma treatment is performed better, and oxidation of the surface of each surface activated substrate is suppressed. Therefore, good bondability can be secured when the substrates are directly bonded.

Application Example 9 In the piezoelectric vibrator manufacturing method according to Application Example 9, the plasma treatment is performed using O ₂ gas, a mixed gas of CF ₄ and O ₂ , or a mixed gas of N ₂ and O ₂ . It may be performed in an oxygen-mediated atmosphere.

  According to this configuration, surface activation necessary and sufficient for direct bonding between the substrates is possible even in an oxygen-mediated atmosphere, and is less expensive than a gas used when plasma processing is performed in an oxygen-free atmosphere. Since a simple gas can be used, the cost of the manufacturing process can be reduced.

Application Example 10 In the method of manufacturing the piezoelectric vibrator according to Application Example 10, it is desirable that the upper and lower substrates are superposed on the upper and lower surfaces of the intermediate piezoelectric plate, and pressed at room temperature to be airtightly bonded.

  According to this configuration, each substrate whose surface is activated by plasma treatment can be directly bonded even at room temperature, and even when the intermediate piezoelectric plate and the upper and lower substrates are made of different materials, due to the difference in thermal expansion coefficient. Since warpage and dimensional change of each substrate can be suppressed, a good bonding state can be obtained. In addition, the intermediate piezoelectric plate and the upper and lower substrates can be bonded in a good state regardless of whether they are the same material or different materials, even if they are the same or different. . When three sheets are joined at the same time, the number of steps in the joining process can be reduced, and when joining one by one, alignment is easy and the accuracy can be improved.

Application Example 11 In the piezoelectric vibrator manufacturing method according to Application Example 11, the upper and lower substrates may be superposed on the upper and lower surfaces of the intermediate piezoelectric plate, and heated and pressed in a heated state to be airtightly bonded.

  According to this configuration, it is possible to improve the bonding strength.

Application Example 12 In the piezoelectric vibrator manufacturing method according to Application Example 12, the upper and lower substrates can be superposed on the upper and lower surfaces of the intermediate piezoelectric plate, and pressurized in an N ₂ atmosphere to be airtightly bonded. .

According to this configuration, by bonding in an inert atmosphere with N ₂ , for example, even when pressing is performed in a heated state, oxidation of each bonding surface of the intermediate piezoelectric plate, upper and lower substrates is suppressed. Therefore, a better bonded state can be obtained.

Application Example 13 In the piezoelectric vibrator manufacturing method according to Application Example 13, it is preferable that the upper and lower substrates are superposed on the upper and lower surfaces of the intermediate piezoelectric plate, and the pressure is applied in a reduced-pressure atmosphere so as to be airtightly bonded.

  According to this configuration, it is possible to improve the bonding strength by reducing the pressure in the cavity defined by overlapping the intermediate piezoelectric plate and the upper and lower substrates.

[Application Example 14] In the method of manufacturing a piezoelectric vibrator according to Application Example 14, the upper and lower surfaces of the laminated body are integrated by superimposing the upper and lower substrates on the upper and lower surfaces of the intermediate piezoelectric plate and temporarily joining them. It is preferable to pressurize and to airtightly join.

  According to this configuration, the surfaces of the substrates activated by the plasma treatment can be easily bonded just by being bonded together, so that they can be easily and accurately aligned, and the assembly accuracy is improved. be able to.

Hereinafter, embodiments of a piezoelectric vibrator according to the present invention will be described with reference to the drawings.
(First embodiment)

  1 to 4 are structural views showing the structure of an embodiment in which the piezoelectric vibrator of the present invention is embodied in a quartz crystal vibrator. FIG. 1A is a top view of the quartz crystal vibrator, and FIG. Is a cross-sectional view taken along line AA in FIG. 4A, and FIG. 2A and 2B are structural views of an intermediate piezoelectric plate constituting the crystal resonator, in which FIG. 2A is a top view and FIG. 2B is a bottom view. 3 and 4 are structural views of the upper and lower substrates constituting the crystal resonator, FIG. 3 is a bottom view of the upper substrate, and FIG. 4 is a top view of the lower substrate.

  As shown in FIG. 1B, the crystal resonator 10 has a structure in which an upper substrate 2 and a lower substrate 3 are integrally laminated on an upper surface and a lower surface of an intermediate crystal plate 11, respectively. The upper and lower substrates 2 and 3 of this embodiment are formed of the same crystal as the intermediate crystal plate. The intermediate crystal plate 11 and the upper and lower substrates 2 and 3 are directly and hermetically bonded to each other by surface activation bonding described later.

  As shown in FIGS. 1B, 2A, and 2B, the intermediate crystal plate 11 has recesses 19a and 19b formed on both main surfaces of a substantially central portion of a rectangular thin plate that is an AT-cut crystal plate. The quartz crystal vibrating piece 12 provided on the frame and the frame 13 surrounding it are integrally formed. An excitation electrode 14 a is formed on the upper surface side of the quartz crystal vibrating piece 12, and an extraction electrode 15 b is formed from one base end portion thereof toward the upper surface of the frame body 13. Similarly, an excitation electrode 14 b is formed on the lower surface side of the quartz crystal vibrating piece 12, and is extracted toward the lower surface of the frame body 13 from the base end opposite to the extraction electrode 15 b formed on the excitation electrode 14 a on the upper surface side. An electrode 15a is formed. The outer terminal portion of the extraction electrode 15 a formed on the lower surface of the frame body 13 includes a through hole 16 that penetrates the upper and lower sides of the intermediate crystal plate 11 and a conductive film 16 P formed on the inner wall surface of the through hole 16. A frame through hole 50a is provided. The conductive film 16P forms a connection portion 18a electrically connected to the excitation electrode 14b via the extraction electrode 15a and the frame body through hole 50a on the upper surface of the frame body 13. Similarly, a frame body through hole 50b composed of the through hole 17 and the conductive film 17P is provided at the outer end portion of the extraction electrode 15b formed on the upper surface of the frame body 13, and the conductive film 17P is formed on the lower surface of the frame body 13. The connection part 18b which consists of is formed, and is electrically connected with the excitation electrode 14a. In this embodiment, each of the conductive electrodes 16P and 17P including the excitation electrodes 14a and 14b, the extraction electrodes 15a and 15b, and the connection portions 18a and 18b is formed of Cr / Au (chromium / gold). Not exclusively. Various conductive materials such as conventionally known Cr / Ag (chromium / silver), Ti / Au (titanium / gold), Ni / Au (nickel / gold), and aluminum can be used.

  As shown in FIGS. 1A to 1C, FIG. 3 and FIG. 4, the upper substrate 2 and the lower substrate 3 are formed with a recess 29 and a recess 39 on the surface facing the intermediate crystal plate 11, respectively. Yes. The concave portion 29 of the upper substrate 2 is formed at a position corresponding to the crystal vibrating piece 12, the extraction electrode 15 b, and the frame through hole 50 b of the intermediate crystal plate 11. Similarly, the concave portion 39 of the lower substrate 3 is formed at a position corresponding to the crystal vibrating piece 12, the extraction electrode 15a, and the frame through hole 50a of the intermediate crystal plate 11. A cavity is formed between the concave portions 29 and 39 and the crystal vibrating piece 12, and the crystal vibrating piece 12 is supported by a frame body 13 that does not hinder vibration excited by the crystal vibrating piece 12.

In addition, a substrate through made of a through hole 5 and a conductive film 5P formed on the inner wall surface of the through hole 5 is located at a position corresponding to the connecting portion 18a of the upper substrate 2 facing the intermediate crystal plate 11. A hole 60a is provided. From the upper substrate 2 on the upper surface side of the substrate through-hole 60a, a lead electrode 7 is formed through the side surfaces of the upper substrate 2, the intermediate crystal plate 11, and the lower substrate 3 toward the bottom surface of the lower substrate 3. The routing electrode 7 is connected to an external connection terminal 8 a provided on the bottom surface of the lower substrate 3.
On the other hand, a substrate made of a through hole 6 and a conductive film 6P formed on the inner wall surface of the through hole 6 at a position corresponding to the connecting portion 18b on the lower substrate 3 facing the intermediate crystal plate 11. A through hole 60b is provided. The substrate through hole 60b is electrically connected to the external connection terminal 8b provided at the end on the bottom surface of the lower substrate 3.

A solder 90 as a conductive bonding material is embedded in the substrate through hole 60a of the upper substrate 2 so as to be in contact with the connecting portion 18a on the upper surface of the intermediate crystal plate 11 and to seal the substrate through hole 60a. Similarly, solder 90 is embedded in the substrate through hole 60b of the lower substrate 3 so as to be in contact with the connecting portion 18b on the lower surface of the intermediate crystal plate 11 and to seal the substrate through hole 60b. With the configuration described above, the external connection electrode 8a of the crystal resonator 10 is electrically connected to the excitation electrode 14b, and the external connection terminal 8b is connected to the excitation electrode 14a. Further, the crystal vibrating piece 12 held in the space formed by the concave portions 29 and 39 of the upper and lower substrates 2 and 3 is hermetically sealed.
In this embodiment, solder is embedded in the substrate through holes 60a and 60b. However, the present invention is not limited to this. For example, a low melting point metal material such as Au-Sn is melted by laser irradiation, or a conductive adhesive is embedded. An embedding method using other conductive materials such as curing can be used.

(Second Embodiment)
Next, a process for manufacturing the crystal resonator 10 of the present embodiment will be described with reference to the drawings. FIG. 5 is a perspective view showing an outline of three crystal wafers to be bonded in the manufacturing process of the crystal unit 10, and FIG. 6A is a conceptual view of the surface activated bonding used as a bonding method in the present embodiment. FIG. 2B is a schematic perspective view showing a laminated body of crystal wafers.

In the present embodiment, a large-sized wafer is prepared in which a plurality of intermediate crystal plates 11, upper and lower substrates 2, 3 described in FIGS. 1 to 4 are arranged at equal intervals in the vertical and horizontal directions. A method for manufacturing the quartz resonator 10 in a lump will be described. FIG. 5 shows a configuration in which six intermediate crystal plates 11 and six upper and lower substrates 2 and 3 are arranged on one wafer. The intermediate crystal wafer 111 for the intermediate crystal plate 11 and the upper substrate 2 are used. The upper crystal wafer 102 and the lower crystal wafer 103 for the lower substrate 3 are shown.
In the present embodiment, first, a step of creating an intermediate crystal wafer 111 in which a plurality of intermediate crystal plates 11 are arranged at equal intervals in the vertical and horizontal directions will be described.
First, both main surfaces of the crystal wafer 211 for the AT-cut intermediate crystal wafer 111 are mirror-polished. This mirror polishing process is preferably performed so that the surface roughness of each bonding surface is about several nanometers to several tens of nanometers in order to satisfactorily perform surface activated bonding described later.
Subsequently, the concave portion 19a and the unillustrated 19b that become the quartz crystal vibrating piece 12 and the through holes 16 and 17 are formed in the quartz wafer 211 by etching with hydrofluoric acid or the like using a photolithography technique. The through holes 16 and 17 can be formed by a sand blast method. Next, for example, by using a sputtering method and a photolithography technique together to form a conductive material such as Cr / Au (chrome / gold) in a desired shape and thickness, the excitation electrodes 14a and 14b, the extraction electrodes 15a, 15b, conductive films 16P and 17P on the inner walls of the through holes 16 and 17 and connection portions 18a and 18b are formed.
Then, the intermediate crystal wafer 111 after the completion of the above processing removes contaminants in the portion to be bonded by pure water cleaning or the like, and keeps the surface state optimal for surface activated bonding.

  At the same time, an upper crystal wafer 102 in which a plurality of upper substrates 2 are arranged at equal intervals is formed. First, the crystal wafer 202 for the upper crystal wafer 102 is mirror-polished like the above. Subsequently, a plurality of recesses 29 are formed at positions corresponding to the excitation electrodes 14a, the extraction electrodes 15b, and the frame body through holes 50b of the intermediate crystal wafer 111 on the side facing the intermediate crystal wafer 111 of the crystal wafer 202. Form. Each recess 29 can be formed, for example, by etching the surface of the crystal wafer 202 with hydrofluoric acid or by sandblasting. In addition, a plurality of through holes 5 are formed by etching with hydrofluoric acid or the like using a photolithographic technique at a position corresponding to each through hole 50a of the intermediate crystal wafer 111 of the crystal wafer 202. This through hole 5 can also be formed by sandblasting. Next, a conductive film 5P is formed in each through hole 5 by sputtering a conductive material such as Cr / Au (chromium / gold) to a desired thickness, and a substrate through hole 60a is formed. Then, the upper quartz wafer 102 after the above processing is removed by removing the contaminants in the portion to be bonded by pure water cleaning or the like, and kept in a surface state optimal for surface activated bonding.

  Similarly, a lower crystal wafer 103 in which a plurality of lower substrates 3 are arranged at equal intervals in the vertical and horizontal directions on the crystal wafer 203 is formed. First, the crystal wafer 203 for the lower crystal wafer 103 is mirror-polished as described above. Next, on the surface of the lower crystal wafer 103 facing the intermediate crystal wafer 111, a plurality of recesses 39 and through holes 6 are made to correspond to the crystal vibrating pieces 12, the excitation electrode 14b, and the extraction electrode 15a of the intermediate crystal wafer 111. Form. Subsequently, a conductive film 6P is formed in each through hole 6 by sputtering a conductive material such as Cr / Au (chromium / gold) to a desired thickness, and a substrate through hole 60b is formed. The through-hole 6 can also be formed by a sand blast method. At the same time, a plurality of pairs of external connection electrodes 8a and 8b are formed on the surface of the lower crystal wafer 103 opposite to the surface facing the intermediate crystal wafer 111. Then, the lower crystal wafer 103 after the completion of the above processing removes contaminants in the portion to be bonded by pure water cleaning or the like, and keeps the surface state optimal for surface activated bonding.

Next, the respective bonding surfaces of the upper and lower crystal wafers 102 and 103 and the intermediate crystal wafer 111 prepared as described above are surface-activated by plasma processing. The plasma processing is performed, for example, using a known SWP type RIE plasma type plasma processing apparatus. First, the intermediate crystal wafer 111, the upper and lower crystal wafers 102 and 103 to be processed are placed on a stage in a processing chamber in a high vacuum atmosphere of a plasma processing apparatus. A reactive gas such as CF ₄ gas is supplied into the processing chamber. Next, when microwaves are radiated into the processing chamber and a standing wave is formed in the waveguide provided in the processing chamber, the microwaves are the upper and lower sides, which are dielectrics disposed below the microwaves. A surface wave that propagates along the surfaces of the quartz wafers 102 and 103 and the intermediate quartz wafer 111 is generated. This surface wave generates a uniform and high-density plasma over the entire surface of the derivative, thereby exciting the reactive gas introduced into the processing chamber and generating active species such as fluorine ions and excited species. To do. When a predetermined voltage is applied to the stage from a high-frequency power source while continuously supplying the reaction gas, the reactive species generated in the processing chamber flow downward from the top toward the stage, Each wafer is plasma treated. As the reactive gas, in addition to CF ₄ gas, Ar single gas, N ₂ single gas, CF ₄ and O ₂ mixed gas, O ₂ and N ₂ mixed gas, O ₂ single gas are used. Similarly, the surface of each wafer can be activated.
By this plasma treatment, the surface of each wafer is exposed to the reactive gas active species and uniformly activated. That is, organic substances, contaminants, and the like are removed from the surfaces of the bonding surfaces of the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103, and atoms having bonds of substances that form the bonding surfaces are exposed. And the surface is activated. Since the active state of the plasma-treated wafer surface is maintained for at least about one hour, the subsequent temporary bonding and main bonding processes can be sufficiently performed.

After the plasma processing, as shown in FIG. 6A, the upper and lower crystal wafers 102 and 103 are superposed on the upper and lower surfaces of the intermediate crystal wafer 111, respectively. First, the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103 are aligned, and the respective bonding surfaces are overlapped to be temporarily bonded to form the wafer laminated body 100. Next, the wafer laminated body 100 is subjected to main bonding by pressing from above and below at room temperature. In this embodiment, three crystal wafers are bonded at the same time, but they can be bonded one by one. For example, after the upper crystal wafer 102 is bonded to the upper surface of the intermediate crystal wafer 111, the lower crystal wafer 103 is bonded to the lower surface thereof.
The intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103 are bonded to each other in the temporary bonding process described above because the atoms having bonding hands are exposed on the plasma-treated bonding surfaces. Can only be glued. The temporarily bonded wafer stack 100 uniformly applies a pressing force of up to about 20 kg to the upper and lower surfaces thereof, and integrally and firmly joins the bonded surfaces. In this embodiment, the main bonding step is performed at room temperature, but can be performed more satisfactorily by performing it at a relatively low temperature of about 200 ° C. Further, the temporary bonding and the main bonding of the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103 can be similarly performed in an atmospheric pressure atmosphere or in a vacuum.

  Next, a predetermined amount of solder paste is filled into each substrate through hole 60a of the upper crystal wafer 102 of the wafer laminate 100 and each substrate through hole 60b of the lower crystal wafer 103 by a dispenser, screen printing or the like. Next, the wafer laminate 100 is put into a reflow furnace set at a solder reflow temperature for a predetermined time to reflow the solder, and the solder 90 is embedded in each of the substrate through holes 60a and 60b. Thus, the conductive films adjacent to each connection portion 18 a of the intermediate crystal wafer 111 and each substrate through hole 60 a of the upper crystal wafer 102, and each of the connection portions 18 b of the intermediate crystal wafer 111 and each substrate through hole 60 b of the lower crystal wafer 103 are adjacent. They are electrically connected to each other by solder, and the substrate through holes 60a and 60b are sealed.

  As shown in FIG. 6B, the wafer laminated body 100 bonded in this way is cut and divided into pieces by dicing or the like along the outline 150 of the quartz crystal unit orthogonal to the vertical and horizontal directions. Each of the separated crystal resonators (10) is connected to the upper surface side of the upper substrate (2) substrate through hole 60a by sputtering or the like, and the other end is provided on the bottom surface of the lower substrate 3 A lead electrode (7) connected to the connection terminal 8a is formed.

Finally, an electrical characteristic test or a desired test is performed to confirm whether the frequency characteristics and other electrical characteristics of the individual crystal resonators (10) that are separated are within a predetermined range. When the frequency characteristic deviates from a predetermined range, the frequency can be adjusted with a laser beam or the like. Since the upper and lower substrates 2 and 3 are mirror-polished and transparent, laser light or the like can be easily irradiated from the outside, and the frequency can be adjusted accordingly.
Further, in the present embodiment, before the crystal resonator 10 is singulated, it is possible to measure and adjust the frequency in the state of the wafer laminate 100 or to perform a desired test.

  Next, the effect of the said embodiment is described below.

  (1) In the first embodiment, first, the crystal vibrating piece 12 is configured by forming the excitation electrodes 14 a and 14 b in the recesses 19 a and 19 b formed on both main surfaces of the intermediate crystal plate 11. The excitation electrodes 14a and 14b were respectively drawn out to the conducting portions 18a and 18b provided on the opposite surface by the lead electrodes 15a and 15b and the frame through holes 50a and 50b. On the upper and lower surfaces of the intermediate crystal plate 11, upper and lower substrates 2, 3 respectively provided with substrate through holes 60a, 60b at positions corresponding to the conductive portions 18a, 18b of the joint surface with the intermediate crystal plate 11, They were laminated together by direct bonding. The upper and lower substrates 2 and 3 are respectively provided with concave portions 29 and 39 on the joint surfaces with the intermediate crystal plate 11 to provide spaces between the crystal vibrating pieces 12 and the lead electrodes 15a and 15b. I tried not to touch it. Then, solder 90 is embedded in the substrate through holes 60a and 60b of the upper and lower substrates 2 and 3, respectively, and electrically connected to the conductive portions 18a and 18b of the intermediate crystal plate 11, and the substrate through holes 60a and 60b are electrically connected. Each 60b was blocked. Then, from the upper surface side of the upper substrate 2 of the substrate through hole 60a, the routing electrode 7 connected to the external connection terminal 8a formed on the bottom surface of the lower substrate 3 was formed. On the other hand, the substrate through hole 60b of the lower substrate 3 is electrically connected to the external connection electrode 8b formed on the bottom surface of the lower substrate 3 by the conductive film 6P. With the above configuration, the excitation electrodes 14a and 14b of the crystal vibrating piece 12 and the external connection electrodes 8a and 8b on the bottom surface of the lower substrate 3 are electrically connected to each other, and the upper and lower substrates 2 and 3 are respectively connected. A crystal resonator 10 that hermetically seals the quartz crystal vibrating piece 12 held in the cavity formed by the recesses 29 and 39 was obtained.

  According to this configuration, in the crystal resonator 10, the substrate through holes 60 a and 60 b of the upper and lower substrates 2 and 3, the recesses 19 a and 19 b (the crystal vibrating piece 12) of the intermediate crystal plate 11, and the upper and lower The concave portions 29 and 39 of the side substrates 2 and 3 are provided as separate spaces that do not communicate with each other. The substrate through holes 60a and 60b of the upper and lower substrates 2 and 3 surround the connection portions 18a and 18b at the bonding surface with the intermediate crystal plate 11, and the bonding surfaces around the substrate through holes 60a and 60b are It becomes a sealed state. Thus, by embedding the solder 90 in the substrate through holes 60a and 60b, it is possible to achieve good electrical connection with the conductive portions 18a and 18b, respectively, so that airtightness is ensured and the excitation electrodes 14a and 14b Reliable electrical connection is possible. Further, when the solder 90 is embedded, the melted solder 90 can be prevented from changing the vibration characteristics of the quartz crystal vibrating piece 12 by spreading to the originally undesired parts such as the excitation electrodes 14a and 14b. . Therefore, it is possible to obtain the crystal resonator 10 having excellent frequency characteristics and high reliability.

  (2) In the second embodiment, as a method of integrally bonding the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103 in the manufacture of the crystal resonator 10, the surface of each bonded surface is obtained by plasma treatment. Direct bonding by activating (surface activated bonding) was used. The same crystal was used as the material for each wafer.

  According to this method, since the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103 can be bonded at room temperature or at a relatively low bonding temperature, dimensional changes and warpage of each wafer can be reduced. Therefore, it is possible to suppress a deviation in the bonding position of each wafer and a decrease in bonding strength. In addition, it is possible to suppress changes in the vibration characteristics of the quartz crystal vibrating piece that are likely to occur when the bonding temperature is high. Furthermore, by forming the material of each wafer with the same crystal, there is a remarkable effect that stable bonding can be secured at a lower temperature.

(Third embodiment)
In the first embodiment, the excitation electrodes 14a and 14b formed on both main surfaces of the intermediate crystal plate 11 are formed on the opposite frame 13 via the frame through holes 50a and 50b. It was set as the structure electrically connected with the connection parts 18a and 18b. On the other hand, in the third embodiment, one connection portion of the frame body is electrically connected to one excitation electrode formed on the opposite side by the frame body through-hole, and the other connection portion has an even number of connection portions. It is configured to conduct with the other excitation electrode side by reciprocating through the frame through hole.

  FIG. 7 is a perspective view illustrating a schematic configuration of the crystal resonator according to the third embodiment. FIG. 8 is an explanatory view for explaining the configuration of an intermediate crystal plate constituting the crystal resonator. FIG. 8A is a top view, FIG. 8B is a bottom view, and FIG. It is BB 'sectional view taken on the line in Fig.8 (a), (b). Note that, among the basic configurations of the crystal resonator 310 and the intermediate crystal plate 311 in the third embodiment, the description of the same configurations as in the first embodiment is omitted.

  As shown in FIG. 7, the crystal resonator 310 has a structure in which an upper substrate 302 and a lower substrate 303 are laminated integrally on the upper and lower surfaces of an intermediate crystal plate 311 by surface activation bonding, respectively. .

  As shown in FIGS. 8A to 8C, excitation electrodes 314 a and 314 b are formed in the recesses 319 a and 319 b formed on both main surfaces of the intermediate crystal plate 311, respectively. Yes. A lead electrode 315 b is formed from one base end portion of the excitation electrode 314 a formed on the upper surface side of the crystal vibrating piece 312 toward the upper surface of the frame 313. Similarly, an excitation electrode 314 b is formed on the lower surface side of the crystal vibrating piece 312, and an extraction electrode 315 a is formed from the base end opposite to the extraction electrode 315 b formed on the upper surface side toward the lower surface of the frame 313. Has been. A conductive film 317P is formed on the inner wall surface of the through hole 317 penetrating from the outer end portion of the extraction electrode 315b formed on the upper surface of the frame body 313 toward the connection portion 318b formed on the lower surface of the frame body 313. A frame through hole 350b is provided. Thereby, the connection part 318b is electrically connected with the excitation electrode 314a. Similarly, a frame body through-hole 350a including a through-hole 316 and a conductive film 316P penetrating the upper surface of the frame body 313 is provided from an outer end portion of the extraction electrode 315a formed on the lower surface of the frame body 313. Further, a frame body through hole 380 including a through hole 381 that vertically penetrates the frame body 313 and a conductive film 381P is provided at a position that is a predetermined distance along the crystal vibrating piece 312 from the frame body through hole 350a. ing. A connection portion 318a formed of the same material as that of the conductive film 381P is provided on the lower surface side of the frame body 313 of the frame body through hole 380. The frame body through hole 350a and the frame body through hole 380 are electrically connected by the connection electrode 370 on the upper surface side of the frame body 313, and the connection portion 318a and the excitation electrode 314b are electrically connected.

  As shown in FIG. 7, the crystal vibrating piece 312, the extraction electrode 315 b, the frame through hole 350 b, the frame through holes 350 a and 380, and these are connected to the surface of the upper substrate 302 facing the intermediate crystal plate 311. A recess 329 is formed at a position corresponding to the connection electrode 370. Similarly, a concave portion 339 is formed on the surface of the lower substrate 303 facing the intermediate crystal plate 311 at a position corresponding to the crystal vibrating piece 312 and the extraction electrode 315a. A cavity is formed between the concave portions 329 and 339 between the crystal vibrating piece 312 and the crystal vibrating piece 312 is supported by the frame body 313.

  Substrate through-holes 360a and 360b each having a conductive film formed on the surface of the inner wall are provided at positions corresponding to the connection portions 318a and 318b on the lower substrate 303 facing the intermediate crystal plate 311. Each of the substrate through holes 360a and 360b is electrically connected to two external connection terminals (not shown) provided at both ends of the bottom surface of the lower substrate 303, respectively. In these substrate through holes 360a and 360b, solder (not shown) is buried so as to contact the connection portions 318a and 318b on the lower surface of the intermediate crystal plate 311 and to seal the substrate through holes 360a and 360b. With the configuration described above, the two external connection electrodes of the crystal unit 310 are electrically connected to the excitation electrodes 314a and 314b, respectively.

  According to this configuration, the excitation electrode 314b formed on the lower main surface of the intermediate crystal plate 311 is pulled out to the upper surface side of the frame body 313 via the extraction electrode 315a and the frame body through hole 350a, and then connected. The electrode 370 and the frame body through hole 380 are connected to a connection portion 318a provided on the lower surface side of the frame body 313. As a result, the excitation electrodes 314a and 314b formed on both main surfaces of the intermediate crystal plate 311 are electrically connected to the connection portions 318a and 318b provided on the surface facing the lower substrate 303 of the frame 313. Pulled out. In addition, the substrate through hole 360a connected to each of the two external connection electrodes formed on the bottom surface of the lower substrate 303 at a position corresponding to each of the connection portions 350a and 350b of the intermediate diaphragm 311 of the lower substrate 303. 360b. In the crystal resonator 310 in which the upper and lower substrates 302 and 303 are bonded to the upper and lower surfaces of the intermediate crystal plate 311, substrate through holes 360 a and 360 b in the lower substrate 303 and a recess 319 b (crystal vibration) in the intermediate crystal plate 311. The piece 312) and the recess 339 of the lower substrate 303 are provided as separate spaces that do not communicate with each other. Further, the substrate through holes 360a and 360b of the lower substrate 303 surround the connection portions 318a and 318b at the bonding surface with the intermediate crystal plate 311, and the bonding surfaces around the substrate through holes 360a and 360b are sealed. . By embedding solder in the substrate through holes 360a and 360b, good electrical connection with the connection portions 318a and 318b can be achieved, so that airtightness is ensured and provided at both ends of the bottom surface of the lower substrate 303. Reliable electrical connection between the two external connection electrodes thus formed and the corresponding excitation electrodes 314a and 314b becomes possible. Further, when the solder 90 is embedded, it is possible to prevent the melted solder from spreading to the originally desired portions such as the respective excitation electrodes 314a and 314b, thereby changing the vibration characteristics of the crystal vibrating piece 312. Further, unlike the crystal resonator 10 described in the first and second embodiments, it is not necessary to provide the through hole 60a in the upper substrate 2 and further form the routing electrode 7. In addition, it is possible to manufacture each of the intermediate crystal plate 311, the upper and lower substrates 302 and 303, and manufacture the crystal unit 310 by bonding them together in a wafer state. Therefore, it is possible to obtain the quartz resonator 10 having excellent frequency characteristics and high reliability, and the manufacturing efficiency can be improved.

  The present invention is not limited to the above-described embodiments, and the following modifications can also be implemented.

  (Modification 1) In the above embodiment, the upper and lower crystal wafers 102 and 103 are made of the same crystal as the intermediate crystal plate 111, but the present invention is not limited to this. A material other than quartz that can be directly bonded to quartz by the plasma treatment of the present invention can be used for at least one of the upper and lower quartz wafers. As such dissimilar materials, glass materials such as soda glass mainly composed of silicon, or silicon, etc., has a coefficient of thermal expansion that is relatively close to that of quartz in addition to the bonding property with quartz. preferable. When such upper and lower wafers (substrates) of different materials are used, in the present invention, bonding can be performed at room temperature, so that it is possible to suppress warping due to a difference in thermal expansion coefficient. Moreover, if the method of joining three wafers simultaneously is taken, the curvature by the difference in a thermal expansion coefficient can be suppressed even if it heats at the time of joining.

  According to this configuration, the choice of wafer material for forming the upper and lower substrates is widened and the material can be obtained at a relatively low cost, so that the piezoelectric vibrator can be manufactured at a low cost.

(Modification 2) In the first and second embodiments, the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103 are directly bonded to each other, and then the solder 90 is embedded in the substrate through holes 60a and 60b. However, the present invention is not limited to this. The upper and lower crystal wafers 102 and 103 in which the solder 90 is embedded in the substrate through holes 60a and 60b in advance may be prepared and bonded to the intermediate crystal wafer 111.
For example, first, the concave portions, the through holes, and the conductive film pattern are formed on the upper and lower crystal wafers 102 and 103 shown in FIG. 5 in the same manner as in the above embodiment, and then the substrate through holes 60a and 60b. A solder 90 is embedded in each of the above. Similarly, as the method of embedding the solder 90, a method of reflowing the solder paste embedded in the substrate through holes 60a and 60b with a dispenser or the like can be used. At this time, each of the upper and lower crystal wafers 102 and 103 is processed with the surface facing the intermediate crystal wafer 111 facing down, so that the solder 90 is at least the intermediate crystal of each of the substrate through holes 60a and 60b. The same surface as the surface facing the wafer 111 is formed. Next, in the same manner as in the above embodiment, the upper and lower crystal wafers 102 and 103 are mirror-polished on the opposing surfaces (bonding surfaces) of the upper and lower crystal wafers 102 and 103, and are embedded in the substrate through holes 60a and 60b. The joining surface including the solder 90 is made flat and smooth. Next, the bonding surfaces of the upper and lower crystal wafers 102 and 103 and the intermediate crystal wafer 111 are activated by plasma processing. Then, the upper and lower crystal wafers 102 and 103 are overlapped with each other on the upper and lower surfaces of the intermediate crystal wafer 111 and bonded together by pressing from above and below, and separated by dicing. Thus, the crystal resonator 10 is obtained.

  According to this configuration, after joining the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103, it is possible to avoid problems such as deterioration of the bonding property without applying temperature stress due to solder reflow. . Further, when the upper and lower wafers 102 and 103 shown in Modification 1 are made of a material different from the crystal that is the material of the intermediate crystal wafer 111, each reflow heating is performed due to the difference in thermal expansion coefficient. There is a remarkable effect that it is possible to suppress problems such as warping of the wafer and stress applied to the joint.

(Modification 3) In the second embodiment, the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103 are joined to form a wafer laminated body 100, which is diced into individual pieces and then routed electrodes 7 are formed. However, it is not limited to this. The routing electrode 7 can also be formed in the state of the wafer laminate 100.
For example, first, castellation (in front of the intermediate crystal wafer 111, the upper crystal wafer 102, and the lower crystal wafer 102, 103 in FIG. A circular through hole) is provided. The castellation can be formed by etching a crystal with hydrofluoric acid or the like using a photolithography technique. Next, the intermediate crystal wafer 111 and the upper and lower crystal wafers 102 and 103 are directly bonded in the same manner as in the above embodiment to obtain a wafer laminate 100 illustrated in FIG. 6B. Then, the castellation penetrates up and down of the wafer stack 100. Next, the inner wall of each castellation penetrating through the wafer laminate 100 is coated by sputtering or the like, and each substrate through hole 60a of the upper crystal wafer 102 is connected to the castellation. A conductive film pattern such as Cr / Au (chromium / gold) is formed so as to connect the external connection electrode 8a formed on the bottom surface and the castellation. By the above method, before dicing wafer laminated body 100, each excitation electrode 14a electrically drawn to upper crystal wafer 102 side and each external connection electrode 8a formed on the bottom surface of lower crystal wafer 103 are connected. Can be electrically connected.
In addition to this, each wafer is bonded to each wafer without providing a castellation in advance, and then a through hole penetrating the wafer laminate 100 is formed, and a conductive film is similarly formed on the inner wall of the through hole. Thus, it is possible to electrically connect the upper surface of the upper crystal wafer 102 and the external connection electrodes 8 a formed on the bottom surface of the lower crystal wafer 103.

  According to this configuration, the lead-out electrode 14 a that is drawn out to the upper substrate 2 side of the crystal resonator 10 and the external connection electrode 8 a that is formed on the bottom surface of the lower substrate 3 can be formed. Since it can be performed in a lump in the wafer state, it is possible to improve manufacturing efficiency.

  (Modification 4) In the first and second embodiments, the crystal vibrating piece 12 of the intermediate crystal plate 11 is formed thinner than the frame body 13. However, the present invention is not limited to this, and the crystal vibrating piece 12 and the frame body 13 are combined. You may form with the same thickness. According to this configuration, it is possible to omit the step of forming the recess for forming the crystal vibrating piece 12 in the intermediate crystal wafer 111.

  (Modification 5) In the first embodiment, the plasma processing for surface activation when bonding the intermediate crystal wafer 111 and the upper and lower wafers 102 and 103 is performed by the SWP RIE method. However, the present invention is not limited to this, and other plasma methods such as an atmospheric pressure plasma method may be used.

  (Modification 6) In the first embodiment, the plasma processing for surface activation when bonding the intermediate crystal wafer 111 and the upper and lower wafers 102 and 103 is performed by the SWP RIE method. However, the present invention is not limited to this, and other plasma methods such as an atmospheric pressure plasma method may be used.

The structure of the crystal resonator of 1st Embodiment is shown, (a) is a top view of a crystal resonator. (B) is the sectional view on the AA line of the same figure (a). (C) is a bottom view. (A) is a top view of the intermediate piezoelectric plate constituting the crystal resonator according to the present invention. (B) is also a bottom view. The bottom view of the upper side board which constitutes the crystal oscillator concerning the present invention. The top view of the lower board | substrate which comprises the crystal oscillator based on this invention. The perspective view explaining the outline of the three quartz wafers joined in the manufacturing method of the crystal oscillator concerning the present invention. (A) is explanatory drawing which shows notionally the point of the surface activation joining used as a joining method in the manufacturing method of the crystal oscillator based on this invention. (B) is a schematic perspective view which shows the laminated body of a crystal wafer. The perspective view explaining the structure of the crystal oscillator of 3rd Embodiment. (A) is a top view of the intermediate piezoelectric plate of the third embodiment. (B) is also a bottom view. (C) is the sectional view on the B-B 'line of the same figure (a) (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 2,302 ... Upper board | substrate, 3,303 ... Lower board | substrate, 8a, 8b ... External connection electrode 10, 310 ... Quartz crystal | crystallization vibrator as a piezoelectric vibrator, 11, 311 ... Intermediate crystal board, 12, 312 ... Piezoelectric vibration Quartz vibrating piece as a piece, 13, 313 ... Frame, 14a, 14b, 314a, 314b ... Excitation electrode, 15a, 15b, 315a, 315b ... Extraction electrode, 18a, 18b, 318a, 318b ... Junction, 29, 39 , 329, 339... Recesses on the upper and lower substrates, 50a, 50b, 350a, 350b, 380 ... Frame substrate through hole in the intermediate piezoelectric plate, 60a ... Substrate through hole in the upper substrate, 60b, 360a, 360b ... Below Substrate through-hole of side substrate, 90... Solder as conductive bonding material, 100... Wafer laminate, 102... Upper crystal wafer as upper piezoelectric wafer, 03 ... lower crystal wafer as bottom piezoelectric wafer, 111 ... intermediate crystal wafer as an intermediate piezoelectric wafer.

Claims (3)

An intermediate piezoelectric plate having a piezoelectric vibrating piece provided with an excitation electrode and a frame disposed so as to surround the piezoelectric vibrating piece;
An upper substrate laminated on the upper main surface of the intermediate piezoelectric plate and bonded by direct bonding;
A lower substrate laminated on the lower main surface of the intermediate piezoelectric plate and bonded by direct bonding;
With
The main surface of the upper substrate on the side laminated with the intermediate piezoelectric plate is provided with a first recess so as to include a region facing the piezoelectric vibrating piece,
The main surface of the lower substrate on the side laminated with the intermediate piezoelectric plate is provided with a second recess so as to include a region facing the piezoelectric vibrating piece,
First and second lead electrodes electrically connected to the excitation electrode are disposed on both main surfaces of the frame body of the intermediate piezoelectric plate, respectively.
The first extraction electrode disposed on the main surface of the frame on the side where the upper substrate is laminated,
A first conductive film provided on the inner wall of the first through hole disposed in the frame;
A second conductive film provided on an inner wall of the second through hole disposed in the thick part of the lower substrate so as to communicate with the first through hole;
Are electrically connected by a conductive material filled in the first and second through holes,
Electrically connected to the first external connection terminal disposed on the opposite side of the surface of the thicker portion of the lower substrate to be bonded to the frame,
The second lead electrode disposed on the main surface of the frame on the side where the lower substrate is laminated,
Among the openings of the both main surfaces of the two frame bodies through holes conductive film on the inner wall through said frame member is provided, positioned on the main surface of the frame of the first lead-out electrode is disposed side Electrically connect the openings to be connected with connection electrodes,
Of the openings of the two frame body through holes on the side where the second lead electrode is disposed, one opening is electrically connected to the second lead electrode, and the other opening is connected to the lower part. Electrically connected to the third conductive film provided on the inner wall of the third through hole disposed in the thick part of the side substrate;
The second external connection terminal provided on the lower substrate is electrically connected to the second lead electrode by being electrically connected to the third conductive film,
An inner bottom surface of the first recess is disposed in a region facing the first extraction electrode and the connection electrode in a thick portion on the side of the upper substrate that contacts the frame body,
The main surface outside the region facing the first extraction electrode and the connection electrode of the thick part of the upper substrate is bonded to the frame body by direct bonding,
An inner bottom surface of the second recess is disposed in a region facing the second extraction electrode in a thick portion on the side of the lower substrate that comes into contact with the frame body,
The main surface outside the region facing the second extraction electrode of the thick part of the lower substrate is joined to the frame body by direct joining,
A piezoelectric device characterized by that.   The piezoelectric device according to claim 1, wherein the intermediate piezoelectric plate and the upper and lower substrates are made of quartz. The piezoelectric device according to claim 1 , wherein the upper and lower substrates are made of a glass material or silicon.

Images