JP2008092112A - Tuning fork type crystal diaphragm frequency adjustment method - Google Patents

Abstract

In a tuning fork type quartz diaphragm having an electrode film for coarse frequency adjustment and fine frequency adjustment, the area of the metal film for frequency adjustment is further reduced as the size of the tuning fork crystal diaphragm is reduced, and a sufficient frequency adjustment amount is obtained. There is a risk that it will be difficult to ensure.
A step of forming a crystal vibrating piece on a quartz substrate, a step of forming an electrode film on each quartz vibrating piece to form a tuning fork type quartz vibrating plate, and a crystal substrate main surface on the second main surface side A mask in which a through-hole is formed is disposed, a step of depositing metal on the second main surface and performing rough frequency adjustment, a step of separating each tuning-fork type quartz diaphragm from the quartz substrate, and a recess space are formed. Prepare the container body, place and fix the tuning fork type quartz diaphragm on the electrode pad for connecting the vibrator formed on the bottom surface in the concave space, and laser or ion etch the tuning fine fork type quartz diaphragm Adjusting the resonance frequency value of the tuning fork type crystal diaphragm so as to be a desired frequency value.
[Selection] Figure 3

Description

  The present invention relates to a frequency adjustment method for a tuning-fork type crystal diaphragm made by a photolithography technique and a chemical etching technique.

  Quartz resonators are used in home appliances, computers, office automation equipment, automobiles, mobile phones and the like as sources of stable frequencies. In particular, a quartz resonator having a tuning fork-shaped outer shape and having a quartz diaphragm having an electrode film formed on the surface is used in large quantities as a time reference source for various electronic devices including wristwatches. A conventional frequency adjusting method in such a tuning fork type crystal diaphragm will be described.

  On the surface of each tuning-fork type crystal vibrating piece made in the quartz substrate by photolithography and etching techniques, an excitation electrode film made of a metal film mainly made of Au, Ag, etc., an electrode film for container body connection, In addition to the conductive wiring for electrically connecting the exciting electrode film and the container body connecting electrode film, a frequency adjusting metal film is formed on the surface of the tip of each vibrating arm portion constituting the tuning fork type crystal vibrating piece. ing. In the frequency adjusting method using the frequency adjusting metal film, first, rough adjustment is performed to match the resonance frequency of each tuning fork type quartz diaphragm formed in the quartz substrate to the vicinity of a desired frequency value. This removes the coarse adjustment metal film of the frequency adjustment electrode in a dot shape by using a laser while vibrating the individual tuning fork type crystal diaphragms. At this time, since the weight of the metal film is reduced, the frequency of the tuning fork type quartz diaphragm is increased and adjustment is performed. Then, the removal is stopped at a predetermined coarse adjustment frequency value. This adjustment is sequentially performed on each tuning-fork type quartz diaphragm in the quartz substrate. A dot-shaped recess is formed in the coarse adjustment metal film after the coarse adjustment.

  Next, the tuning-fork type quartz diaphragm removed from the support frame of the quartz substrate is mounted on the diaphragm connection electrode pad formed in the container body made of ceramics or the like, after the tip of the base is mounted. Then, the frequency fine adjustment is performed so that the desired resonance frequency value is obtained. This is performed in the same manner as the coarse adjustment method described above using a laser. In the fine adjustment metal film after fine adjustment, dot-shaped concave portions are formed. After that, the mounting space opening of the container body on which the tuning fork type crystal diaphragm whose frequency has been adjusted is mounted is covered with a flat lid body, and the lid body and the container body are hermetically sealed, so that the crystal resonator is can get.

  Other frequency adjustment methods include rough frequency adjustment of a plurality of tuning fork type quartz diaphragms formed in the quartz substrate by photolithography and etching techniques, and individual tuning fork type quartz diaphragms mounted in the container body. Are disclosed in which fine adjustment of the frequency is performed by ion etching.

The frequency adjustment method of the tuning fork type quartz diaphragm as described above is disclosed in the following prior art documents.
Japanese Patent No. 3460694 JP 2003-133879 A In addition, the applicant has not found any prior art documents related to the present invention by the time of the filing of the application other than the prior art documents specified by the above prior art document information. .

  However, it has become necessary to significantly reduce the size of the crystal unit, which is an electronic component, and at the same time, it is necessary to reduce the size of the tuning fork type crystal diaphragm mounted in the crystal unit. As miniaturization progressed, the area of the frequency adjusting metal film formed on the surface of the tuning-fork type quartz diaphragm had to be reduced. In particular, in a tuning fork type quartz diaphragm in which a metal film for coarse frequency adjustment and fine frequency adjustment is formed on one main surface of the quartz crystal vibrating piece, the area of each metal film for frequency adjustment is further reduced. It may be difficult to ensure the frequency adjustment amount.

  Further, in the frequency adjustment method as described above, the metal film for rough frequency adjustment is performed by removing a part of the metal film with a laser, but with the laser, in order to remove the metal film in a dot shape, it is performed once. There is a limit to the frequency value that can be adjusted by laser irradiation, and when the adjustment amount is large, multiple laser irradiations are required, and the frequency adjustment process may take a long time. In the conventional method, it takes 10 seconds or more for the frequency adjustment process of one tuning fork type quartz diaphragm, and 360 / hour or more per frequency adjustment process. Such man-hours cannot cope with the mass production of tuning-fork type quartz diaphragms, and there is a problem that a large amount of capital investment is required when trying to cope with them.

The present invention has been made to solve the above problems,
A quartz crystal resonator element in which a main surface is a square and a flat plate-like base portion and a plurality of vibrating arm portions extending in the same direction from one side of the base portion are formed on the surface of the vibrating arm portion. The electrode film for excitation and the metal film for frequency adjustment, the electrode film for connecting the container body formed on the surface of the base, and the electrode film for excitation and between the electrode film for excitation and the electrode film for connecting the container body are electrically connected. In the frequency adjustment method of the tuning fork type quartz diaphragm constituted by the conductive wiring connected to
A step A of performing a photolithography process and an etching process on the quartz substrate to form a quartz crystal vibrating piece having a plurality of tuning fork-shaped external shapes;
Each electrode film in a desired pattern having a metal film for fine frequency adjustment only on the first main surface in the vicinity of the tip of the vibrating arm of the quartz crystal vibrating piece on the surface of each quartz crystal vibrating piece formed on the quartz substrate Forming a tuning fork type quartz diaphragm,
A mask in which a through-hole is formed in a portion corresponding to the vicinity of the tip of the vibrating arm portion of each tuning-fork type quartz diaphragm is disposed on at least the quartz substrate principal surface on the second principal surface side facing the first principal surface, A metal is vapor-deposited on the second main surface of the vibrating arm portion of each tuning-fork type quartz diaphragm in the quartz substrate from above the mask, and the resonance frequency value of each tuning-fork type quartz diaphragm at this time is a desired resonance frequency value. In contrast, a step C for performing rough frequency adjustment within a range from a frequency value lower than a desired frequency value by a certain amount to a desired resonance frequency value;
Step D for separating each tuning-fork type quartz diaphragm subjected to coarse frequency adjustment from the quartz substrate;
Prepare a container body with a concave space having an opening on one main surface, and individually tune the tuning fork type crystal diaphragm separated in the previous process on the electrode pad for connecting the vibration body formed on the bottom surface of the concave space The first main surface is arranged so as to face the opening, and the vibrator connecting electrode pad and the container connecting electrode film are electrically and mechanically connected, and at the same time, the frequency fine tuning metal on the first main surface And a step E for adjusting the resonance frequency value of the tuning-fork type quartz diaphragm to a desired frequency value by laser or ion etching of the film. .

  Further, in the above-described step C, the range of the frequency value adjusted in the frequency coarse adjustment step of the tuning fork type quartz diaphragm is set to a range from a frequency value that is −200 ppm lower than a desired resonance frequency value to a desired frequency value. This is also the frequency adjusting method of the tuning fork type quartz diaphragm described above.

  In the above-described tuning fork type crystal diaphragm frequency adjusting method, the rough frequency adjustment is performed by adjusting the second main surface (tuning fork type) in the vicinity of the tips of the individual vibrating arm portions of the plurality of tuning fork type crystal diaphragms formed in the quartz substrate. Compared to the conventional coarse frequency adjustment method, when a quartz plate is mounted in the concave space of the container body, the metal is added to the main surface facing the bottom surface of the concave space simultaneously by vapor deposition. Thus, the adjustment time can be remarkably shortened, and the process time as a whole frequency adjustment process can be shortened.

  In addition, since the frequency coarse adjustment is performed by simultaneously adding metal to each tuning fork type quartz diaphragm by vapor deposition, the tuning fork type quartz diaphragm has been downsized, and the frequency adjustment area on the surface of the tuning fork type quartz diaphragm Even when the area is small, a sufficient frequency adjustment amount can be ensured as compared with the conventional frequency adjustment method of removing the frequency adjustment metal film.

  Therefore, according to the present invention, there is an effect that it is possible to provide a method for manufacturing a tuning fork type crystal diaphragm that can shorten the frequency adjustment process time and can cope with downsizing.

Hereinafter, an embodiment of a frequency adjustment method for a tuning-fork type crystal diaphragm according to the present invention will be described with reference to the drawings.
FIG. 1 is an exploded perspective view showing a crystal resonator on which a tuning fork type crystal diaphragm subjected to a frequency adjusting method according to the present invention is mounted. FIG. 2 is a process explanatory view showing the first half of the steps of the method of adjusting the frequency of the tuning-fork type quartz diaphragm according to the present invention using a plan view of the quartz substrate. FIG. 3 is a process explanatory diagram showing the latter half of the process of the frequency adjustment method for the tuning-fork type quartz diaphragm following the process shown in FIG. 2 using the plan view of the crystal substrate and the crystal resonator. In each of the drawings, a part of the structure is not shown, and some dimensions are exaggerated for the sake of clarity. In particular, the thickness dimension of each part is exaggerated.

  That is, as shown in FIG. 1, a rectangular parallelepiped container body 101 made of an insulating material such as ceramics or a resin material has a recess having an opening on one main surface thereof. A space 102 is formed. In addition, a pair of diaphragm connection electrode pads 103 is formed in the vicinity of one short side of the bottom surface in the recess space 102 along the one short side. Electrically connected to a predetermined electrode terminal among the plurality of external connection electrode terminals 104 formed on the other main surface of the container body 101 by a conductive wiring or via hole formed inside or on the surface of the container body 101. It is connected.

  In the recessed space 102 of the container body 101 having such a configuration, a base portion 105 having a substantially rectangular main surface and a flat plate-like shape, and two vibrating arm portions 106 extending in the same direction from one side of the base portion, Are integrally formed on the surface of the vibrating arm portion 106 of the quartz crystal vibrating piece, the excitation fine film 107, the fine frequency adjustment metal film 108a, and the rough frequency adjustment metal film 108b (in FIG. 1, the rough frequency adjustment metal film 108b is (Not shown) is formed, and the container body connecting electrode film 109 is formed on the surface of the base portion 105. Further, an electrical connection is made between the excitation electrode film 107 and between the excitation electrode film 107 and the container body connecting electrode film 109. The tuning-fork type quartz diaphragm 111 constituted by the conductive wiring 110 connected to the electrode has one main surface on which the fine frequency-adjusting metal film 108a is formed facing the opening side of the recessed space 102, and the container body connecting electrode. Membrane 10 It is placed in a form arranging the on respective diaphragm connecting electrode pads 103. The container connecting electrode film 109 and the diaphragm connecting electrode pad 103 are electrically and mechanically connected by a conductive adhesive, and the attitude of the tuning fork type quartz diaphragm is maintained in the recessed space 102. .

  On the opening side top surface of the side wall of the container body 101 that surrounds the recessed space 102 of the container body 101 on which such a tuning fork type crystal vibrating plate 111 is placed, a metal is formed so as to cover the opening of the recessed space 102. A flat plate-shaped lid body 112 is disposed, and a sealing conductor pattern 113 formed over the entire circumference on the opening side top surface of the side wall portion of the container body 101 and a seal formed on the container body-side main surface of the lid body 112. The quartz resonator 100 is configured by hermetically sealing the inside of the recessed space 102 by joining a stopper (not shown).

A method for adjusting the frequency of the tuning-fork type crystal diaphragm 111 used in such a crystal unit 100 will be described with reference to FIGS.
First, as shown in FIG. 2A as a process A, a quartz crystal vibrating piece having a plurality of tuning fork-shaped external shapes is obtained by subjecting a quartz crystal substrate 201 cut out from an artificial crystalline lens and subjected to an external shape process to a photolithography process and an etching process. 202 is formed. Each of the quartz crystal vibrating pieces 202 is supported on a beam portion 203 formed in the quartz crystal substrate 201 by a support portion 204 formed on the base portion 105 of the quartz crystal vibrating piece 202. In addition, as each processing method in the photolithography process and the etching process used for this formation, a conventionally used method is used, and the resonance frequency value of the crystal vibrating piece 202 at this time is finally a tuning fork type. It is processed so as to be higher than the resonance frequency desired for the quartz diaphragm.

  Next, as shown in FIG. 2B as Step B, at least a first portion near the tip of the vibrating arm portion 106 of the crystal vibrating piece 202 is formed on the surface of each crystal vibrating piece 202 formed on the crystal substrate 201. An excitation electrode film 107, a container body connection electrode film 109, and a conductive wire 110 having a desired pattern having a frequency fine adjustment metal film 108a only on the main surface 205 are formed by vapor deposition, and a tuning fork type is formed in the quartz substrate 201. A plurality of crystal diaphragms 111 are formed. The resonance frequency value of the tuning fork type quartz diaphragm 111 in this process B is formed so as to be still higher than the resonance frequency desired as a tuning fork type quartz diaphragm.

  FIG. 2 (c) shows the quartz substrate 201 shown in FIG. 2 (b) reversed and shown from the back side of the one shown in FIG. 2 (b). As shown in FIG. 2 (c), In the vicinity of the distal end portion of the vibrating arm portion 106 of the second main surface 206 corresponding to the back side of the first main surface 205, no electrode film is formed in FIG.

  Next, as shown in FIG. 3D as step C, the vibrating arms of the individual tuning-fork type crystal vibrating plates 111 are formed on at least the main surface of the crystal substrate 201 on the second main surface 206 side facing the first main surface 205. A mask 208 in which a through hole 207 is formed is disposed in the vicinity of the tip of the portion 106, and Au + Cr or Au + Cr metal is placed on the mask 208 from the top of the mask 208 and the vibration arm portion of each tuning-fork type crystal diaphragm in the quartz substrate. The main surface of 2 is vapor-deposited to form a laminated structure with Cr as a base, and the resonance frequency value of each tuning-fork type quartz diaphragm 111 at this time is a desired resonance frequency from −200 ppm or more with respect to the desired resonance frequency value. While measuring the resonance frequency value of at least one tuning-fork type quartz diaphragm in the quartz substrate 201 so as to be within the range of the frequency value or less, rough frequency adjustment is performed to lower the resonance frequency. For example, when the desired resonance frequency value is 32.768 kHz, the resonance frequency value before coarse adjustment is higher than 32.768 kHz. By this frequency coarse adjustment step, the resonance frequency value after coarse adjustment is set to 32.11264. The frequency is roughly adjusted to be within the range of ˜32.768 kHz. The time spent for this rough frequency adjustment is 4 to 6 seconds when converted to one tuning fork type quartz diaphragm formed on the quartz substrate 201.

  Note that the mask 208 and the through-hole 207 as described above can be finely formed by an existing processing method. Therefore, even if the outer shape of the tuning-fork type quartz diaphragm 111 is reduced, the tuning-fork type quartz vibration is reduced. It is possible to form a mask 208 having a through-hole 207 capable of depositing a metal for rough frequency adjustment at a predetermined location on the vibrating arm portion of the plate. In addition, since the rough frequency adjustment in the present invention is a method in which metal is uniformly deposited by vapor deposition, the outer shape of the tuning fork type quartz diaphragm 111 is reduced, and the formation region of the tip of the vibrating arm 106 is reduced. However, a relatively large adjustment amount can be ensured, and it is possible to prevent the occurrence of defective products due to insufficient frequency adjustment amount.

  Next, as shown in FIG. 3E, as the process D, each tuning fork type crystal subjected to frequency coarse adjustment by attaching a metal to the second main surface 206 in the vicinity of the tip of the vibrating rod 106 by vapor deposition. The diaphragm 111 is separated from the quartz substrate 201 by cutting the support portions 204. At this time, it is possible to easily perform the separation work by forming a groove in a place where it is desired to cut the support portion 204 in advance.

  Next, as shown in FIG. 3F, as process E, a container body 101 in which a concave space 102 having an opening is formed on one main surface is prepared, and the tuning fork type crystal diaphragm 111 separated in the previous process is prepared. The first main surface 205 on which the frequency fine adjustment metal film 108a is formed is arranged on the diaphragm connection electrode pad 103 formed on the inner bottom surface of the recessed space 102 so that the first main surface 205 faces the opening. The electrode pad 103 for connecting the plate and the electrode film 109 for connecting the container body are electrically and mechanically connected, and at the same time, the frequency fine tuning metal film 108a on the first main surface 205 is subjected to laser or ion etching, so that the frequency fine By removing a part of the adjustment metal film 108a, the resonance frequency value of the tuning-fork type crystal diaphragm 111 is adjusted to a desired frequency value (32.768 kHz according to the above example). The time spent for fine frequency adjustment is within 3 seconds for one tuning-fork type quartz diaphragm, and when combined with the coarse frequency adjustment, the frequency adjustment process can be performed within 9 seconds at the longest.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the resonance frequency value of the tuning fork type quartz diaphragm is −200 ppm or more to a desired resonance frequency value or less with respect to the desired resonance frequency value in Step C of the frequency adjustment method of the tuning fork type quartz diaphragm. The frequency coarse adjustment is performed so that it falls within the range. This is based on the ratio of the time for coarse frequency adjustment within this resonance frequency range and the time spent for fine frequency adjustment in the subsequent process so that the overall process time can be shortened as much as possible in the overall frequency adjustment process. The frequency adjustment amount for fine adjustment is determined. Therefore, as long as the effects of the present invention are exhibited, the present invention is not limited to the range of the resonance frequency value after the adjustment in the frequency coarse adjustment step described above.

FIG. 1 is an exploded perspective view showing a crystal resonator on which a tuning fork type crystal diaphragm subjected to a frequency adjusting method according to the present invention is mounted. FIG. 2 is a process explanatory view showing the first half of the steps of the method of adjusting the frequency of the tuning-fork type quartz diaphragm according to the present invention using a plan view of the quartz substrate. FIG. 3 is a process explanatory diagram showing the latter half of the process of the frequency adjustment method for the tuning-fork type quartz diaphragm following the process shown in FIG. 2 using the plan view of the crystal substrate and the crystal resonator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Container body 102 ... Recessed space 103 ... Electrode pad for diaphragm connection 105 ... Base 106 ... Vibration arm 107 ... Excitation electrode film 108a ... For fine frequency adjustment Metal film 108b ... Rough frequency adjusting metal film 109 ... Container connection electrode film 110 ... Conducting wiring 111 ... Tuning fork type quartz crystal plate 201 ... Quartz crystal substrate 202 ... Crystal vibrating piece 205 ... first main surface 206 ... second main surface 207 ... through hole 208 ... mask

Claims (2)

A quartz crystal vibrating piece in which a main surface is a quadrangle and has a flat plate-like base and a plurality of vibrating arms extending in the same direction from one side of the base, and
An excitation electrode film and a frequency adjustment metal film formed on the surface of the vibrating arm;
A container body connecting electrode film formed on the base surface;
In the frequency adjustment method for a tuning-fork type quartz diaphragm constituted by the conductive electrode electrically connected between the excitation electrode film and between the excitation electrode film and the container body electrode film,
A step A of performing a photolithography process and an etching process on the quartz substrate to form a quartz crystal vibrating piece having a plurality of tuning fork-shaped external shapes;
A desired pattern having a frequency fine tuning metal film on at least the first main surface in the vicinity of the tip of the vibrating arm portion of the quartz crystal vibrating piece on the surface of each quartz crystal vibrating piece formed on the quartz substrate. A step B of forming each of the electrode films and the metal film to form a tuning fork type quartz diaphragm; and
A mask in which a through hole is formed in a portion corresponding to the vicinity of the tip of the vibrating arm portion of each tuning-fork type quartz diaphragm is disposed on at least the quartz substrate principal surface on the second principal surface side facing the first principal surface. Then, metal is deposited on the second main surface of the vibrating arm portion of each tuning-fork type quartz diaphragm in the quartz substrate from above the mask, and the resonance frequency value of each tuning-fork type quartz diaphragm at this time is desired A step C for performing rough frequency adjustment to make the resonance frequency value within a range from a frequency value lower than the desired frequency value by a certain amount to the desired resonance frequency value,
Step D for separating each tuning-fork type quartz diaphragm subjected to coarse frequency adjustment from the quartz substrate;
A container body in which a concave space having an opening is formed on one main surface is prepared, and the tuning-fork type crystal diaphragm separated in the previous step is individually placed on the electrode pad for connecting the vibrator formed on the bottom surface in the concave space. The first main surface is arranged so as to face the opening, and the vibrator connecting electrode pad and the container connecting electrode film are electrically and mechanically connected to the first main surface at the same time. A tuning fork type crystal vibration comprising adjusting the resonance frequency value of the tuning fork type crystal diaphragm to a desired frequency value by laser or ion etching the metal film for fine frequency adjustment. How to adjust the frequency of the board.   The tuning fork type according to claim 1, wherein the range of the frequency value adjusted in the frequency coarse adjustment step of the tuning fork type quartz diaphragm is within a range from a frequency value -200 ppm lower than a desired resonance frequency value to a desired frequency value. How to adjust the frequency of the quartz diaphragm.

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