JP5120201B2 - Method for adjusting frequency of piezoelectric diaphragm - Google Patents

Description

  The present invention relates to a method for adjusting the frequency of a piezoelectric diaphragm mounted on a piezoelectric vibrating device used in communication equipment or the like.

  With the recent miniaturization of piezoelectric vibration devices, the miniaturization of crystal resonators widely used in mobile communication devices such as mobile phones is also progressing. In order to cope with ultra-miniaturization, the crystal unit is also equipped with a quartz plate inside a conventional box-shaped ceramic package and hermetically sealed with a flat lid (handled as a single unit) From the form where a large number of lid members are joined to each of the front and back main surfaces of the wafer where a large number of crystal diaphragms are linked (handled in a state where a large number of lid members are linked, and finally to the individual To be split). A crystal resonator according to this embodiment is disclosed in Patent Document 1, for example.

JP 2007-306434 A

  Electrode films (metal films) for exciting the crystal diaphragm are formed oppositely on the front and back main surfaces of the crystal diaphragm of the above-described form. The frequency of the crystal diaphragm is changed by reducing the mass of the electrode film by irradiating the electrode film, and the frequency is adjusted so as to be within the target frequency range. However, when frequency adjustment is performed on a wafer in which a large number of crystal diaphragms are aligned, the conventional method of reducing the mass of each electrode film by irradiating each crystal diaphragm with a one-to-one ion beam. A lot of time is required, causing a reduction in production efficiency.

  The present invention has been made in view of this point, and an object of the present invention is to provide a frequency adjustment method for a piezoelectric diaphragm capable of performing efficient frequency adjustment.

In order to achieve the above object, according to the first aspect of the present invention, in a wafer in which a large number of piezoelectric diaphragms are integrally formed, electrode films are formed on the front and back main surfaces of each piezoelectric diaphragm. A method for adjusting the frequency of the piezoelectric diaphragm by adjusting the frequency of the piezoelectric diaphragm by reducing the mass of the piezoelectric diaphragm, wherein all of the electrode films of the wafer are intermittently collectively irradiated with an energy beam. The mass is reduced, the frequency of the piezoelectric diaphragm is measured when the irradiation of the energy beam is stopped, and a shield covering the electrode film of the piezoelectric diaphragm is formed on the piezoelectric diaphragm that has reached the target frequency range. This is a method of adjusting the frequency of the piezoelectric diaphragm, characterized in that the mass of the film is not reduced.

  According to the above frequency adjustment method, the energy beam (ion beam, laser beam, etc.) is collectively irradiated to all the electrode films in the wafer, so that the energy beam is applied one-on-one to each piezoelectric diaphragm. The frequency adjustment of the piezoelectric diaphragm can be performed more efficiently than the method of reducing the electrode film by irradiation.

  Further, with the frequency adjustment method described above, a shield covering the electrode film of the piezoelectric diaphragm is formed on the piezoelectric diaphragm that has reached the target frequency range (frequency standard), and the mass of the electrode film is not reduced. Therefore, the frequency adjustment can be performed by collectively irradiating the energy beam to the piezoelectric diaphragm requiring additional adjustment. In other words, since the shield is formed in one-to-one with respect to the piezoelectric diaphragm that has reached the frequency standard, the piezoelectric diaphragm that has reached the frequency standard even when the energy beam is collectively irradiated, further increases the mass of the electrode film. Will not be reduced. Therefore, it is not necessary to select a piezoelectric diaphragm other than the piezoelectric diaphragm that has reached the frequency standard and adjust the frequency by irradiating each piezoelectric diaphragm with an energy beam.

The invention according to claim 1 is a method of adjusting the frequency of the piezoelectric diaphragm, wherein the collective irradiation is intermittent irradiation, and the frequency of the piezoelectric diaphragm is measured when the irradiation of the energy beam is stopped. With such a frequency adjustment method, the energy beam is not always radiated, but intermittent irradiation that alternately irradiates and stops, and the frequency of the piezoelectric diaphragm is measured with the energy beam irradiation stopped. Therefore, the frequency can be measured more accurately. Therefore, the frequency can be adjusted with higher accuracy.

  In the frequency adjustment method described above, for the piezoelectric diaphragm whose frequency after the batch irradiation does not reach the target frequency range, the batch irradiation is performed for the energy beam irradiation time corresponding to the necessary adjustment amount up to the frequency standard. It is possible to adjust the frequency. That is, it is possible to control the amount of frequency change due to the energy beam batch irradiation by managing the energy beam irradiation time. Specifically, by acquiring and feeding back the correlation between the irradiation condition (irradiation time, irradiation angle, etc.) and the amount of frequency change, the number of frequency measurements during frequency adjustment can be reduced. Thereby, it is not always necessary to check the frequency of the piezoelectric diaphragm every time the energy beam is collectively irradiated, and the work time can be reduced, so that the production efficiency can be improved.

In order to achieve the above object, as in the invention of claim 2 , in the collective irradiation, the energy beam is irradiated obliquely above and below the wafer front and back surfaces, and substantially opposite positions across the wafer. Relationship may be. By irradiating the energy beam from both sides of the wafer in this way, the adjustment time can be shortened compared to the case of irradiating the energy beam only from one side of the wafer.

  Furthermore, the energy density of the irradiated region in the wafer can be made uniform by irradiating the front and back surfaces of the wafer with an energy beam obliquely from above and obliquely below, so that the wafers are positioned substantially opposite to each other. it can. That is, when the energy beam is irradiated only on one main surface (one side) of the wafer from obliquely above the wafer, an energy density distribution is likely to occur in the irradiated region (a high-density region and a low-density region are generated). On the other hand, if the other main surface (one side) of the wafer is irradiated obliquely below the wafer and in a direction that is substantially opposed across the wafer, a high-density region is unevenly distributed in the irradiated region on one side of the wafer. Even if it does, it will be buffered by the front and back of a wafer, and the said energy density can be made uniform. That is, when viewed from the entire wafer, variations in the electrode film mass reduction rate (frequency adjustment rate) can be suppressed.

  Further, when the energy beam is irradiated onto the wafer from the vertical direction, a part of the reduced electrode film (metal material) reattaches to the electrode film, or a part of the reduced electrode film moves in the irradiation direction. The frequency adjustment rate may be reduced by rebounding. However, according to the invention of claim 3, since the energy beam is irradiated to the main surface of the wafer from an oblique direction, the reattachment or the frequency adjustment rate is performed. Can be prevented.

  The frequency adjustment rate can be varied by using the above-described shield formation pattern and the substantially opposite irradiation with the energy beam wafer interposed therebetween. That is, (A) When a shield is formed on both front and back main surfaces of a wafer, (B) When a shield is formed only on one main surface side, (C) When a shield is not formed on both main surfaces of a wafer Theoretically, there are three patterns, and (B) can be varied by a factor of 1 and (A) by a factor of 2 compared to the frequency adjustment rate of the pattern of (C) in theory. In reality, the theoretical rate does not always follow the conditions such as the energy beam irradiation conditions and the frequency variation of the piezoelectric diaphragms in the wafer. The frequency adjustment can be performed by selecting the formation pattern of the shields. As a result, efficient frequency adjustment can be performed with a smaller number of irradiations, and production efficiency can be improved.

  A fine through hole may be formed in the shield. Here, the formation position of the minute through hole is, for example, a position corresponding to the position immediately above the electrode film when the shield is attached to the piezoelectric diaphragm (for example, above the vicinity of the approximate center of the electrode film). At this time, the mass reduction rate of the electrode film by the energy beam irradiation can be set to be very small as compared with the piezoelectric diaphragm having no shield (the entire area of the electrode film is exposed). That is, when the energy beam is irradiated from above the shield, the mass of the electrode film of the piezoelectric diaphragm is slightly reduced through the minute through hole. This fine through-hole can further increase the frequency adjustment rate pattern described above, and perform finer frequency adjustment, so that frequency adjustment with a smaller number of irradiations can be expected. The number of minute through holes formed is not limited to one, and a plurality of minute through holes may be formed. Furthermore, the formation position of the minute through hole is not limited to the upper part of the electrode film, but may be above the position away from the center of the electrode film. That is, the formation number and formation position of the minute through holes can be arbitrarily set.

  The shield may be a lid member of a piezoelectric vibration device that covers the electrode films on the front and back main surfaces of the piezoelectric vibration plate. By using the constituent member of the piezoelectric device for the shield, it can be used as it is without replacing the shield with the lid member in the steps after the frequency adjustment step. That is, the number of steps can be reduced, and the piezoelectric device can be efficiently manufactured.

  Further, the shield may be a metal shutter that covers the electrode film of the piezoelectric diaphragm. In this case, for example, the wafer is placed in an apparatus that adjusts the frequency by ion beam irradiation, and a plurality of metal pieces having outer dimensions that can cover the electrode films of all the piezoelectric diaphragms in the wafer above (or below) the wafer. A shutter is attached, and attached to the piezoelectric diaphragm that has reached the frequency standard so as to cover the electrode film by lowering (raising) the shutter from above (or below) the wafer. With such a configuration, the shield can be formed in the apparatus, and the number of times of removal from the apparatus can be reduced. Therefore, the metal film (electrode film) activated by ion beam irradiation is used. Surface oxidation can be prevented and a more stable electrode film can be formed. It is also possible to coat (coat) the electrode film with a resist solution or the like on the shield.

  In the present invention, when the energy beam is irradiated onto the wafer, an integrated mask that covers the region other than the electrode films of all the piezoelectric diaphragms in the wafer may be used.

  As described above, according to the present invention, it is possible to provide a frequency adjustment method for a piezoelectric diaphragm capable of performing efficient frequency adjustment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiment, a case where a crystal resonator is applied to the present invention as a piezoelectric vibration device is shown. FIG. 1 is a schematic cross-sectional view in the long side direction of a crystal resonator showing an embodiment of the present invention, FIG. 2 is an exploded cross-sectional view of FIG. 1, and FIG. 3 is a schematic perspective view of a wafer in the embodiment of the present invention. 4 is a conceptual diagram showing frequency adjustment in the embodiment of the present invention, FIG. 5 is a plan view showing frequency distribution in the wafer in the embodiment of the present invention, FIG. 6 is a perspective view showing frequency adjustment in the embodiment of the present invention, FIG. 7 is a side view showing frequency adjustment in the embodiment of the present invention, and FIG. 8 is a perspective view showing frequency adjustment in the embodiment of the present invention. Hereinafter, first, the main constituent members of the crystal resonator will be described, and then the frequency adjustment method will be mainly described.

  As shown in FIG. 1, the crystal resonator 1 includes a crystal diaphragm 2 (a piezoelectric diaphragm referred to in the present invention) and an excitation electrode 23 (see below) formed on one main surface 21 of the crystal diaphragm 2. The first lid member 3 that is hermetically sealed and the second lid member 4 that hermetically seals the excitation electrode 23 (see below) formed on the other main surface 22 of the quartz crystal vibration plate 2 are main constituent members. In the crystal resonator 1, the crystal diaphragm 2 and the first lid member 3 are joined by the joining material 5, and the crystal diaphragm 2 and the second lid member 4 are joined by the joining material 5, thereby forming the package 11. Is done. Then, the first lid member 3 and the second lid member 4 are joined to each other through the crystal diaphragm 2, thereby forming two internal spaces 12 of the package 11, and crystal vibrations in the internal space 12 of the package 11. Excitation electrodes 23 formed on both main surfaces 21 and 22 of the plate 2 are hermetically sealed in the respective internal spaces 12. The first lid member and the second lid member have the same shape and the same outer dimensions, and the first lid member 3 has an external connection formed on the bottom surface (other main surface) 37 of the lid member. A conduction path (via) electrically connected to the terminal 34 is formed penetrating in the thickness direction of the lid member.

  In FIG. 2, the quartz diaphragm 2 is an AT-cut quartz plate cut out at a predetermined angle, and the central portions of both main surfaces 21 and 22 are thin portions 27 (so-called reverse mesa shape). The thin portion 27 is formed by wet etching. Excitation electrodes 23 are oppositely formed on the front and back surfaces (one main surface 21 and the other main surface 22) of the thin portions 27 of both main surfaces 21 and 22 by vapor deposition. In this embodiment, the excitation electrode 23 is formed by vapor deposition on the front and back main surfaces of the quartz crystal diaphragm 3 in order from the bottom in the film configuration of chromium, gold, and chromium. The film configuration of the electrode is not limited to this, and other film configurations may be used. An extraction electrode 24 is led out from the excitation electrode 23, and the extraction electrode 24 is electrically connected to an electrode pad 33 formed on the first lid member 3.

  Both main surfaces 21 and 22 of the crystal diaphragm 2 have a mirror finish and are formed as flat smooth surfaces. In the crystal diaphragm 2, the outer peripheral end portion 26 in plan view of both main surfaces 21, 22 is configured as a joint surface 25 between the first lid member 3 and the second lid member 4, and the center in plan view of both main surfaces 21, 22. The part is configured as a vibration region. A first bonding material 51 for bonding to the first lid member 3 is formed on the bonding surface 25 of the one main surface 21 of the crystal diaphragm 2. A second bonding material 52 for bonding to the second lid member 4 is formed on the bonding surface 25 of the other main surface 22 of the crystal diaphragm 2. Here, the formation widths of the first bonding material 51 and the second bonding material 52 are substantially the same. The first bonding material 51 and the second bonding material 52 have the same configuration. The first bonding material 51 and the second bonding material 52 are configured by laminating a plurality of layers on the bonding surface 25 of the outer peripheral end portion 26 in plan view of both the main surfaces 21 and 22, and chromium (Cr ) Layer (not shown) and a gold (Au) layer (not shown) are formed by vapor deposition, and a gold plating layer (not shown) is laminated thereon.

  In FIG. 2, the first lid member 3 is a flat plate having a rectangular shape in plan view, and quartz that is a translucent material is used. In plan view, the outer dimensions of the first lid member 3 are substantially the same as the outer dimensions of the crystal diaphragm 2, and one main surface 31 of the first lid member 3 (joint surface 32 with the crystal diaphragm 2 described below). Is formed as a flat smooth surface (mirror finish). A third bonding material 53 is formed in a circumferential shape on the periphery of the first lid member 3 on the side of the bonding surface with the crystal diaphragm 2. Here, the formation width of the third bonding material 53 is formed to be substantially the same as the formation width of the first bonding material 51.

  The first lid member 3 includes an electrode pad 33 that is electrically connected to the excitation electrode 23 of the crystal vibrating plate 2, a bonding portion (specifically, a bonding surface 32) that is bonded to the crystal vibrating plate 2, and an external and electrical connection. And an external connection terminal 34 to be connected. The joint surface 32 with the crystal diaphragm 2 is provided on the outer periphery of the main surface 31 of the first lid member 3 in plan view.

  On the bonding surface 32 of the first lid member 3, a third bonding material 53 for bonding to the crystal diaphragm 2 is formed. Specifically, a plurality of layers of the third bonding material 53 are laminated on the bonding surface 32, and a chromium (Cr) layer (not shown) and a gold (Au) layer 531 are formed by vapor deposition from the lowermost layer side. An Au—Sn alloy layer 532 is formed on the substrate, and an Au flash plating layer 533 is formed thereon. Alternatively, the third bonding material 53 may be formed by vapor-depositing a Cr layer and an Au layer from the lower surface side, and sequentially laminating an Sn plating layer and an Au plating layer thereon. The third bonding material 53 and the electrode pad 33 are formed at the same time, and the electrode pad 33 has the same configuration as the third bonding material 53. Further, as shown in FIG. 2, the first lid member 3 is formed with a through hole 35 for electrically connecting the excitation electrode 23 of the crystal diaphragm 2 to the outside. An electrode pattern 36 is formed through the through hole 35 from the electrode pad 33 on the one main surface 31 of the first lid member 3 to the external connection terminal 34 on the other main surface 37.

  In FIG. 2, the second lid member 4 is a flat plate having a rectangular shape in plan view, and crystal is used in the same manner as the first lid member 3. The external dimensions of the second lid member 4 in plan view are substantially the same as the external dimensions of the crystal diaphragm 2. One main surface 41 of the second lid member 4 (a bonding surface 42 with the crystal diaphragm 2 described below) is formed as a flat smooth surface (mirror finish). A fourth bonding material 54 is formed on the periphery of the second lid member 4 on the side of the bonding surface with the crystal diaphragm 2. Here, the formation width of the fourth bonding material 54 is substantially the same as the formation width of the second bonding material 52.

  The second lid member 4 is provided with a joint portion (specifically, a joint surface 42) that joins the crystal diaphragm 2. The joint surface 42 is provided on the outer periphery of the main surface 41 of the second lid member 4 in plan view. A fourth bonding material 54 for bonding to the crystal diaphragm 2 is formed on the bonding surface 42 of the second lid member 4. Specifically, in the fourth bonding material 54, a plurality of layers are laminated on the bonding surface 42, a Cr layer (not shown) and an Au layer 541 are formed by vapor deposition from the lowermost layer side, and an Au—Sn alloy is formed thereon. The layer 542 is laminated and formed, and the Au flash plating layer 543 is laminated thereon. Alternatively, the fourth bonding material 54 may be formed by vapor-depositing a Cr layer and an Au layer from the lower surface side, and sequentially laminating an Sn plating layer and an Au plating layer thereon. Note that the bonding region (seal path) of the first bonding material 51 on the bonding surface 25 of the crystal diaphragm 2 and the bonding region (seal path) of the third bonding material 53 on the bonding surface 32 of the first lid member 3 are the same. Have a width. In addition, the bonding region (seal path) of the second bonding material 52 on the bonding surface 25 of the crystal diaphragm 2 and the bonding region (seal path) of the fourth bonding material 54 on the bonding surface 42 of the second lid member 3 have the same width. Have.

  The above is a description of the main members constituting the crystal unit 1. However, the first lid member 3, the second lid member 4, and the crystal diaphragm 2 described above are collectively formed from the wafer state, and finally After a plurality of crystal resonators are formed, they are separated into pieces by dividing and cutting. By such a method, it becomes possible to handle the members (the first lid member, the second lid member, and the crystal diaphragm) constituting the crystal unit 1 in a wafer state, and the handling becomes simple, thereby improving the production efficiency. be able to.

  Hereinafter, the frequency adjustment process will be mainly described. In this embodiment, as shown in FIG. 3, a quartz crystal wafer 200 (hereinafter abbreviated as “wafer”) having a rectangular shape in plan view in which a large number of quartz crystal diaphragms 2 are integrally aligned inside the frame portion is used. Has been. In this embodiment, the wafer is an AT-cut quartz plate having a rectangular shape in plan view, and 768 quartz diaphragms are formed on one wafer. After depositing a metal film on the front and back surfaces of the wafer by vapor deposition and forming a resist, a desired electrode pattern is formed by exposure and development, and a thin portion 27 is formed in the central portion of each crystal diaphragm by etching. To do. The first bonding material 51 and the second bonding material 52 are formed on the surface of the bonding surface 25 of the crystal diaphragm by an electrolytic plating method. In FIG. 3 (the same applies to FIG. 6 described later), the description of the extraction electrodes, the first bonding material and the second bonding material formed on the front and back surfaces of each crystal diaphragm, and the metal wiring necessary for electrolytic plating is omitted. is doing.

  The frequency adjustment of the crystal diaphragm is performed by an ion milling method. That is, the frequency of the crystal diaphragm is adjusted by irradiating the entire wafer 200 with an Ar ion beam irradiated from an ion gun and reducing the mass of the electrode film of each crystal diaphragm. Specifically, by reducing the mass of the electrode film, the frequency of the crystal diaphragm is adjusted in the increasing direction.

First, before starting the frequency adjustment, the frequencies of all the quartz diaphragms in the wafer are measured in advance. Frequency data obtained by the measurement is stored in a storage device (not shown) connected to an ion milling device (not shown). The frequency data is classified into a plurality of groups according to a predetermined frequency classification width. The frequency distribution measured in the state before frequency adjustment is almost a normal distribution state as shown in FIG. In this embodiment, the nominal frequency of the crystal resonator is 54.000 MHz in the fundamental vibration mode, and the frequency variation before frequency adjustment is about 50 kHz. The frequency classification width is 10 kHz, and the frequency is classified into five groups (A, B, C, D, and E. The frequencies are increased in order from E to A ).

FIG. 5 is a diagram showing the frequency distribution in the wafer before frequency adjustment in the above five groups. In FIG. 5, for convenience of explanation, the number of crystal diaphragms formed on one wafer 200 is reduced to 42 (6 rows × 7 columns), and the group distribution state based on the frequency before frequency adjustment in the wafer is shown. Represents. In addition, the frequency adjustment process referred to in the present embodiment is a target frequency range (frequency range on the right side in FIG. 4) of a frequency distribution before frequency adjustment as shown in FIG. Hereinafter, it is a process of reducing and adjusting the mass of the electrode film of the crystal diaphragm using an ion beam so as to fall within the abbreviation of the frequency standard. In other words, when the target frequency (target frequency) is set in the frequency standard, the E group with the lowest frequency requires the maximum amount of adjustment up to the target frequency, and conversely, the A group with the highest frequency reaches the target frequency. The amount of adjustment required is minimal.

  In the frequency adjustment, first, the wafer 200 before the frequency adjustment is accommodated in a vacuum chamber of an ion milling apparatus. Thereafter, the vacuum chamber is evacuated to a high vacuum state. In the vacuum chamber, two ion guns (G1, G2) are installed obliquely above the wafer and obliquely below the wafer as shown in FIGS. The relative positional relationship between these two ion guns (G 1, G 2) is a substantially opposing relationship with the wafer 200 interposed therebetween. By irradiating the ion beam from both sides of the wafer in this way, the adjustment time can be shortened compared to the case of irradiating the ion beam only from one side of the wafer.

  Further, the energy density of the irradiated region in the wafer is made uniform by irradiating the front and back surfaces of the wafer 200 from the upper and lower sides of the wafer 200 so as to have a substantially opposite positional relationship across the wafer. Can do. That is, when the ion beam is irradiated only on one main surface (one surface) of the wafer from obliquely above the wafer, an energy density distribution is likely to occur in the irradiated region (a high-density region and a low-density region are generated). On the other hand, if the other main surface (one side) of the wafer is irradiated obliquely below the wafer and in a direction that is substantially opposed across the wafer, a high-density region is unevenly distributed in the irradiated region on one side of the wafer. Even if it does, it will be buffered by the front and back of a wafer, and the said energy density can be made uniform. That is, when viewed from the entire wafer, variations in the electrode film reduction rate (frequency adjustment rate) can be suppressed.

  In addition, when the ion beam is irradiated onto the wafer from the vertical direction, a part of the reduced electrode film (metal material) reattaches to the electrode film, or a part of the reduced electrode film moves in the irradiation direction. The frequency adjustment rate may decrease due to rebounding. However, according to the present invention, the ion beam is applied to the main surface of the wafer from an oblique direction, so that the reattachment and the frequency adjustment rate are reduced. Can be prevented.

First, of the A~E groups classified measured before frequency adjustment, since the necessary amount of adjustment of the high A group of the most frequency to the target frequency (the frequency adjustment amount) is minimized adjustment amount, the minimum amount of adjustment The entire wafer is simultaneously irradiated from the two ion guns for an ion beam irradiation time that is close to. At this time, a shielding mask having a one-to-one opening is arranged above and below the wafer so that only the electrode film portions of the entire crystal diaphragm in the wafer are exposed, and the ion beam is transmitted through the shielding mask (not shown). Irradiated on the electrode film. In the present embodiment, the above-described shielding mask is used, but the present invention can be applied without using the shielding mask.

  Thus, the mass of the electrode films of a large number of crystal diaphragms in the wafer is collectively reduced by collectively irradiating the entire wafer with the ion beam for the irradiation time. After the ion beam is irradiated for the irradiation time, the ion beam irradiation is stopped. That is, the collective irradiation is intermittent irradiation. If intermittent irradiation is performed, the ion beam is not always irradiated, and the frequency of the quartz diaphragm is measured in a state where the irradiation of the energy beam is stopped. Therefore, the frequency can be measured more accurately. Therefore, the frequency can be adjusted with higher accuracy.

Then, the frequency is measured for a part of the crystal diaphragms of the A group and other groups. The frequency measurement may be performed only for the A group.

The result of the frequency measurement, for example, if a portion of the quartz plate of the A group falls within the frequency standard, is taken out from the wafer from the vacuum chamber as shown in FIG. 8, the A group was within the frequency standard quartz The shield 6 is attached to the diaphragm. Here, the above-described second lid member (piece) 4 and first lid member (piece) 3 are used for the shield 6. Specifically, on the bonding material (second bonding material) formed on the outer peripheral portion of the A group crystal vibrating plate within the frequency standard, the bonding surface side of the second lid member with the quartz vibrating plate is down. In this way, the second lid member is positioned and placed so that the bonding material (fourth bonding material) of the second lid member substantially matches in plan view. The positioning is performed using an image recognition means. Then, after the positioning and placement, the quartz diaphragm 2 and the second lid member 4 are temporarily bonded to each other by ultrasonic bonding through the above-described bonding material for the quartz diaphragm and the lid member. On the other hand, after the wafer is turned upside down, the first lid is formed on the bonding material (first bonding material) formed on the outer peripheral portion of the A group crystal diaphragm within the frequency standard by the same procedure as described above. Positioning and mounting so that the bonding surface (third bonding material) of the first lid member substantially coincides in a plan view with the bonding surface side of the member with the crystal vibrating plate facing down, crystal vibration by ultrasonic bonding Temporary bonding of the plate 2 and the first lid member 3 is performed. The electrode film of the crystal diaphragm is shielded by the temporary bonding.

Next, among the A to E groups measured and classified before the frequency adjustment, the B group having the second highest frequency is the minimum adjustment amount because the necessary adjustment amount (frequency adjustment amount) up to the target frequency is the minimum adjustment amount. The entire wafer is simultaneously irradiated from the two ion guns for an ion beam irradiation time that is close to the minimum adjustment amount. Here, the irradiation time of the ion beam can be controlled by managing the amount of frequency change due to the batch irradiation of the ion beam by the irradiation time of the ion beam. Specifically, the correlation between the irradiation condition (irradiation time, irradiation angle, etc.) and the amount of frequency change is acquired and fed back, thereby reducing the number of frequency measurements during frequency adjustment. Thereby, it is not always necessary to check the frequency of the piezoelectric diaphragm every time the batch irradiation of the ion beam is completed, and the working time can be reduced, so that the production efficiency can be improved.

  Next, the shield 6 is temporarily bonded to the quartz crystal plate within the frequency standard after the ion beam irradiation in the same manner as described above. As described above, the frequency measurement for frequency confirmation is not necessarily performed by the ion beam irradiation time management, and the frequency measurement may be omitted.

In the above manner, the entire wafer is simultaneously irradiated from two ion guns for the time corresponding to the necessary adjustment amount (frequency adjustment amount) up to the target frequency in the order of C group → D group → E group. The frequency is adjusted so that the frequency of the crystal diaphragm converges within the standard. In the frequency adjustment according to the present invention, it is not always necessary to temporarily attach two shields 6 to the front and back surfaces of the quartz diaphragm that has reached the frequency standard. In other words, the shield may be temporarily bonded to either one of the front and back surfaces of the crystal diaphragm that has reached the frequency standard according to the necessary adjustment amount. Thus, by forming the shield on only one side of the quartz diaphragm, the adjustment rate can be reduced as compared to the case where no shield is formed. As a result, the frequency adjustment rate pattern increases, and more efficient frequency adjustment can be performed by selecting a shield formation pattern according to the necessary adjustment amount.

  Specifically, (A) When a shield is formed on both the front and back main surfaces of a wafer, (B) When a shield is formed only on one main surface, (C) A shield is formed on both main surfaces of the wafer There are three patterns in the case of not performing, and theoretically, (B) can be varied by 1 time and (A) can be varied by 2 times compared to the frequency adjustment rate of the pattern of (C). Actually, the theoretical rate does not always meet the above-mentioned theoretical rate depending on conditions such as ion beam irradiation conditions and frequency fluctuations of the piezoelectric diaphragms in the wafer. The frequency adjustment can be performed by selecting the formation pattern of the shields. As a result, efficient frequency adjustment can be performed with a smaller number of irradiations, and production efficiency can be improved.

  A fine through hole may be formed in the shield 6. Here, the formation position of the minute through hole is, for example, a position corresponding to the position immediately above the electrode film when the shield is attached to the crystal diaphragm (for example, above the vicinity of the approximate center of the electrode film). At this time, the mass reduction rate (frequency adjustment rate) of the electrode film by ion beam irradiation is set to be very small as compared with a quartz diaphragm (where the entire area of the electrode film is exposed) in which no shield is formed. be able to. That is, when the ion beam is irradiated from above the shield, the mass of the electrode film of the quartz crystal plate is slightly reduced through the minute through hole. This fine through-hole can further increase the frequency adjustment rate pattern described above, and perform finer frequency adjustment, so that frequency adjustment with a smaller number of irradiations can be expected. The number of minute through holes formed is not limited to one, and a plurality of minute through holes may be formed. Furthermore, the formation position of the minute through hole is not limited to the upper part of the electrode film, but may be above the position away from the center of the electrode film. That is, the formation number and formation position of the minute through holes can be arbitrarily set.

  In this embodiment, a lid member, which is a constituent member of a crystal resonator, is used as the shield 6, but the present invention is not limited to this. For example, a metal shutter that covers the electrode film of the crystal diaphragm is used. There may be. In this case, for example, the wafer is placed in an apparatus that performs frequency adjustment by ion beam irradiation, and a plurality of metal pieces having an external dimension that can cover the electrode films of all the crystal diaphragms in the wafer above (or below) the wafer. A shutter is attached, and attached to the piezoelectric diaphragm that has reached the frequency standard so as to cover the electrode film by lowering (raising) the shutter from above (or below) the wafer. With such a configuration, the shield can be formed in the apparatus, and the number of times of removal from the apparatus can be reduced. Therefore, the metal film (electrode film) activated by ion beam irradiation is used. Surface oxidation can be prevented and a more stable electrode film can be formed. It is also possible to coat (coat) the electrode film with a resist solution or the like on the shield.

  In the embodiment of the present invention, quartz is used as a material for the two lid members (first lid member, second lid member), but borosilicate glass or sapphire may be used in addition to quartz. Further, in the embodiment of the present invention, gold is used as the metal film used for joining the first lid member and the second lid member to the piezoelectric diaphragm. However, the present invention is not limited to this, and other than gold. In addition, other metals such as a gold-tin alloy (Au—Sn alloy), a tin-silver alloy (Sn—Ag alloy), and a gold-germanium (Au—Ge alloy) can be used.

  Further, in the embodiment of the present invention, the batch irradiation of the energy beam is performed by intermittent irradiation, but the present invention can be applied even by continuous irradiation.

  In the embodiment of the present invention, two flat lid members having a rectangular shape in plan view are used. However, the present invention is not limited to this embodiment, and the excitation electrode formed on the piezoelectric diaphragm by the two lid members. As long as can be hermetically sealed, the shape of the lid member may be arbitrarily set. For example, a form in which the concave portions of the two lid members formed in a concave shape are hermetically bonded so as to face the piezoelectric diaphragm may be employed. Or the form comprised by the flat cover member, the piezoelectric diaphragm, and the cover member formed in the concave shape by the box-shaped body may be sufficient.

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

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

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

The schematic sectional drawing of the long side direction of the crystal oscillator which shows embodiment of this invention. The exploded sectional view of the long side direction of the crystal oscillator showing the embodiment of the present invention. 1 is a schematic perspective view of a wafer showing an embodiment of the present invention. The conceptual diagram showing the frequency adjustment in embodiment of this invention. The top view which shows the frequency distribution in the wafer in embodiment of this invention. The perspective view which shows the frequency adjustment in embodiment of this invention. The side view which shows the frequency adjustment in embodiment of this invention. The perspective view which shows the frequency adjustment in embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Crystal oscillator 2 Crystal diaphragm 200 Crystal wafer 21 One main surface of crystal diaphragm 22 Other main surface of crystal diaphragm 23 Excitation electrode 3 1st cover member 4 2nd cover member 5 Bonding material 6 Shielding body

Claims (2)

In a wafer in which a large number of piezoelectric diaphragms are integrally formed, electrode films are formed on the front and back main surfaces of each piezoelectric diaphragm, and the frequency of the piezoelectric diaphragm can be adjusted by reducing the mass of the electrode films. A method for adjusting the frequency of a piezoelectric diaphragm,
All the electrode films on the wafer were intermittently irradiated with an energy beam to reduce the mass of the electrode film, and when the energy beam irradiation was stopped, the frequency of the piezoelectric diaphragm was measured to reach the target frequency range. A method of adjusting a frequency of a piezoelectric diaphragm, comprising: forming a shield covering the electrode film of the piezoelectric diaphragm so as not to reduce a mass of the electrode film. 2. The piezoelectric diaphragm according to claim 1 , wherein in the collective irradiation, the energy beam is irradiated obliquely from above and obliquely below the front and back surfaces of the wafer and has a substantially opposed positional relationship across the wafer. Frequency adjustment method.

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