JP2008131462A - Method of manufacturing piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibration chip in which, even if the piezoelectric vibration chip is miniaturized or super-miniaturized, an electrode film can precisely be formed, and a method of manufacturing a piezoelectric device using the same. <P>SOLUTION: The method of manufacturing the piezoelectric vibration chip includes an external shape forming stage of wet-etching a piezoelectric substrate and a subsequent electrode forming stage of forming an electrode for driving. In the electrode forming stage performed after the etching of the external shape forming stage, a metal film 55 being the electrode film is formed using a mask 53 for electrode film formation and after the electrode film is formed, its surface is coated with a resist 56. The electrode film is etched after being exposed and developed to form the electrode for driving which has a necessary final external shape size, and the mask for electrode film formation has an opening 53a having a predetermined area larger than the required final external shape DE of the electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement in a piezoelectric vibrating piece formed by etching a piezoelectric substrate and a method for manufacturing a piezoelectric device formed using the piezoelectric vibrating piece.

A piezoelectric vibrating piece used for a conventional piezoelectric device is formed by, for example, forming a driving electrode on an element piece (blank) made of a piezoelectric material cut into a rectangular shape, for example, in order to form a quartz vibrating piece. Yes.
FIG. 8 shows a part of a conventional electrode forming process (see Patent Document 1 and FIG. 9).
In the figure, the element piece 1 is shown as a sectional view in the thickness direction. A mask 2 is arranged on the main surface of the element piece 1, that is, the front and back surfaces to cover a portion to be shielded on the main surface. Thereafter, using the targets 3 and 3, a conductive metal film is formed on the main surfaces 4 and 4 exposed from the mask 2 by sputtering.

JP 2002-217675 A

However, such a method has the following problems.
FIG. 9 is a schematic plan view of the element piece 1. The element piece 1 is a rectangular plate formed by wet etching a piezoelectric material such as quartz.
Here, when wet etching is performed on crystal, etching anisotropy is observed, and the etching progress speed varies depending on the crystal axis orientation.

FIG. 10 shows a state in which the end face of the element piece 1 is deformed due to the etching anisotropy. FIG. 10A is a schematic end view taken along the line AA of FIG. 9, and FIG. It is a BB schematic end view of.
As described above, the size of the deformed portion due to the etching anisotropy is relatively large compared to the size of the element piece 1, even though the element piece 1 has conventionally not changed its thickness. It also depends on the fact that the external dimensions are getting smaller.
For this reason, if an electrode film is formed by masking and photolithography using the same method as in the prior art, a shadowed area cannot be exposed due to the influence of the irregular shape as shown in FIG. There was a problem that could not.
In addition, not only those with etching anisotropy such as quartz, but also in isotropic materials, depending on the shape and exposure conditions, there may be places where exposure is difficult at the outer edge of the plate-like body, Even in that case, the electrode pattern may not be formed accurately.

  The present invention has been made to solve the above problems, and uses a piezoelectric vibrating piece capable of accurately forming an electrode film even when a small or ultra-small piezoelectric vibrating piece is formed. An object of the present invention is to provide a method for manufacturing a piezoelectric device.

  According to the first aspect of the present invention, there is provided an outer shape forming step of forming an element piece of a piezoelectric vibrating piece by etching a piezoelectric substrate, and an electrode forming step of forming a driving electrode after the outer shape is formed. In the electrode forming step, a metal film to be an electrode film is formed using a mask for electrode film formation, and a resist is applied to the surface of the electrode film. Then, after exposure / development, etching is performed to form a driving electrode having a required final outer dimension, and the electrode film-forming mask is the required electrode. This is achieved by a method for manufacturing a piezoelectric vibrating piece having an opening having a predetermined area larger than the final outer shape of the piezoelectric vibrating piece.

According to the configuration of the first invention, in the electrode forming step, first, a metal film to be an electrode film is formed using an electrode film forming mask. As a result, a mask is disposed in a portion that is likely to be deformed due to the influence of etching anisotropy so that the electrode film is not formed. For this reason, it is possible to form the electrode film more accurately than a technique in which an electrode film is formed over the entire surface and then a mask is provided to expose and etch the electrode film in unnecessary regions.
In other words, after forming an electrode film on the whole, arranging a photoresist, exposing and developing, removing the exposed electrode film, and performing the necessary electrode separation, the above-mentioned etching anisotropy is There may be a case where it is not possible to sufficiently expose at the spot. For this reason, when an electrode remains in such a region, electrode separation is not sufficiently performed, and there is a possibility of short-circuiting.
Therefore, it is possible to separate the electrodes precisely by not forming an electrode film from the beginning especially in such a region.
Further, this electrode deposition mask is provided with an opening having a predetermined area larger than the final shape of the required electrode. This is because, for example, when a metal film is formed as an electrode film by vapor deposition or sputtering using a metal mask as a mask, the inner periphery of the opening edge of the metal mask depends on the thickness of the metal mask. This is because a non-uniform film formation occurs. If such a region is used as an electrode, electrode separation or the like may be inaccurate. In addition, if the excitation electrode includes a portion where the film is formed unevenly, the frequency variation of the resonator element becomes large due to the film thickness variation in the peripheral portion of the electrode film. Therefore, according to the inventor's knowledge that it is necessary to exclude a portion where the film is formed unevenly from the region used as the electrode, such a region is removed in the subsequent photolithography process. Therefore, the opening area of the mask for electrode film formation can be expected in advance for such a non-uniform film formation region. The electrode can be precisely formed.

  According to the second aspect of the present invention, in the second invention, an outer shape forming step of etching the piezoelectric substrate to form an element piece of the piezoelectric vibrating piece, and an electrode forming step of forming a driving electrode after the outer shape is formed. In the electrode forming step, a metal film to be an electrode film is formed using a mask for electrode film formation, and a resist is applied to the surface of the electrode film. Then, after the exposure / development, etching is performed to form a drive electrode having a required final outer dimension, and the electrode film formation mask is formed after the exposure / development. This is achieved by a method for manufacturing a piezoelectric vibrating piece having an opening having a predetermined area larger than that of the resist pattern.

According to the configuration of the second invention, the electrode film is not formed from the beginning in a region where a deformed portion due to etching anisotropy is likely to be formed on the basis of the same principle as described in the first invention. Electrodes can be separated.
In addition, the electrode deposition mask has an opening with a predetermined area larger than the resist pattern after exposure and development. As a result, as in the case of the first invention, it is possible to anticipate in advance the region where the film is formed unevenly in the opening area of the electrode film forming mask. Thereby, even if such a region is removed in the subsequent photolithography process, an electrode having a necessary area as a piezoelectric vibrating piece can be accurately formed.

  According to a third aspect of the present invention, there is provided an outer shape forming step of forming an element piece of a piezoelectric vibrating piece by etching a piezoelectric substrate, and an electrode forming step of forming a driving electrode after the outer shape is formed. In the electrode forming step, a metal film to be an electrode film is formed using a mask for electrode film formation, and a resist is applied to the surface of the electrode film. Then, after the exposure / development, etching is performed to form a driving electrode having the required final outer dimensions, and the electrode film-forming mask is used during the exposure. This is achieved by a method of manufacturing a piezoelectric vibrating piece having an opening having a predetermined area larger than the pattern of the drive electrode drawn on the mask to be used.

According to the configuration of the third invention, the electrode film is not formed from the beginning in a region where the deformed portion due to the etching anisotropy is likely to be formed on the basis of the same principle as described in the first invention. Electrodes can be separated.
In addition, the electrode deposition mask has an opening having a predetermined area larger than the pattern of the drive electrode drawn on the mask during the exposure and development. As a result, as in the case of the first invention, it is possible to anticipate in advance the region where the film is formed unevenly in the opening area of the electrode film forming mask. Thereby, even if such a region is removed in the subsequent photolithography process, an electrode having a necessary area as a piezoelectric vibrating piece can be accurately formed.

According to a fourth aspect of the present invention, in the configuration of any one of the first to third aspects, a dimensional difference between the opening edge of the electrode film forming mask and the outer edge of the final outer shape of the driving electrode is: It is characterized by being not less than the thickness dimension of the electrode deposition mask.
According to the structure of 4th invention, the range of the area | region in which the non-uniform | heterogenous film-forming part is formed in the location close | similar to the opening peripheral part differs with the thickness of the mask for electrode film-forming. For this reason, in considering the dimensional difference between the opening edge of the electrode deposition mask and the outer edge of the final outer shape of the driving electrode, the dimension is set to be equal to or larger than the thickness of the mask. As a result, it is possible to secure a sufficient range for removing an electrode having a necessary area as a piezoelectric vibrating piece by removing such a region in a subsequent photolithography process.

  A fifth invention is a method of manufacturing a piezoelectric device in which a piezoelectric vibrating piece is accommodated in a package or a case, and after forming a plurality or a plurality of the piezoelectric vibrating pieces on a piezoelectric substrate, the individual piezoelectric vibrating pieces are Separating the piezoelectric substrate from the piezoelectric substrate, and joining the piezoelectric resonator element to a connection electrode portion formed on a package or an electrode of a plug attached to the case. It is characterized in that it is formed by any one of the methods of the invention of (4).

  According to the configuration of the fifth invention, it is possible to accommodate the piezoelectric vibrating piece in which the electrode is precisely formed according to the same principle as the first to third inventions, so that a piezoelectric device with excellent performance can be obtained. .

1 and 2 show an embodiment of the piezoelectric device of the present invention. FIG. 1 is a schematic plan view of the piezoelectric device, and FIG. 2 is a schematic cross-sectional view of the piezoelectric device of FIG.
In FIG. 1, the piezoelectric device 30 shows an example in which a piezoelectric vibrator is configured, and a piezoelectric vibrating piece 40 is accommodated in a package 31 of the piezoelectric device 30.
As will be described later, the package 31 can be formed by stacking and sintering green sheets formed into the shape of FIG. In this case, the electrode part 33 is formed on the substrate constituting the bottom part of the package 31.
The package 31 is a box-shaped container having an internal space S. Using this internal space S, the piezoelectric vibrating piece 40 is accommodated. A lid 35 made of a metal such as ceramic, glass, or kovar is joined to the package 31 via low-melting glass, nickel, or the like. Thereby, the package 31 is hermetically sealed.

As shown in FIG. 1, electrode portions 33, 33 are formed near both ends in the width direction at end portions in the length direction of the inner surface of the package 31.
The electrode portion 33 is connected to mounting terminals 32 and 32 exposed on the bottom surface of the package 31 by a conductive pattern (not shown).

As the piezoelectric vibrating piece 40, a so-called AT cut vibrating piece obtained by processing a wafer formed of a piezoelectric material so as to become a thin rectangular substrate is used. That is, as will be described later, an element piece that is a piezoelectric chip is first formed as will be described later, and a piezoelectric vibrating piece 40 that is an AT-cut vibrating piece is formed by forming an excitation electrode 41 for driving on this element piece. .
The piezoelectric vibrating piece 40 uses, for example, quartz as a piezoelectric material. In addition to quartz, piezoelectric materials such as lithium tantalate and lithium niobate can be used, and further have etching anisotropy. Not only isotropic materials can be used. In addition, the piezoelectric vibrating piece 40 is not limited to a flat type, and may be any piezoelectric element that forms an electrode on an element piece obtained by wet etching a piezoelectric substrate, such as a convex type, an inverted mesa type vibrating piece, or a circular vibrating piece. It can be applied to a vibrating piece.

That is, the excitation electrode 41 is formed on the surface of the piezoelectric chip as the element piece 51 as a driving electrode. The excitation electrode 41 is formed in a region of the piezoelectric chip that actively vibrates, and applies a driving voltage to the piezoelectric material, thereby efficiently generating an electric field in the material and exciting the material. The excitation electrode 41 is also formed in the same form on the back surface of the element piece 51.
In addition, as shown in FIG. 2, the excitation electrodes 41 are respectively connected to the extraction electrodes 42, which are connection electrodes respectively formed at both ends in the width direction, at the end portions in the length direction of the piezoelectric vibrating reed 40. Connected separately. Each extraction electrode 42 is also formed on the back surface around the side surface of the piezoelectric chip.

As shown in FIG. 1, such a piezoelectric vibrating piece 40 is joined to the electrode portion 33 on the package 31 side in a cantilever manner.
As a result, the drive voltage supplied from the outside of the package 31 via the mounting terminals 32 is applied to the conductive adhesive 43 and the piezoelectric vibrating piece 40 from the electrode portion 33 on the package 31 side. Therefore, the main surface of the piezoelectric vibrating piece 40 is driven by a thickness-shear vibration caused by a piezoelectric action.

  Note that the package 31 is not a box shape but a simple insulating substrate, electrodes are formed thereon, and the piezoelectric vibrating piece 40 is hermetically sealed by a shallow box-shaped lid (not shown). May be used. Alternatively, a plug connected to an external drive voltage source is connected to the piezoelectric vibrating piece 40, the piezoelectric vibrating piece 40 is inserted into a metal cylindrical case with one end closed, and the case is hermetically sealed with this plug. You may make it (not shown).

(Piezoelectric vibrating piece and piezoelectric device manufacturing method)
Next, an embodiment of a method for manufacturing the piezoelectric device 30 will be described.
First, the package for the piezoelectric device and the piezoelectric vibrating piece 40 are formed separately.
The package 31 described with reference to FIGS. 1 and 2 is suitably made of ceramic, and has a thermal expansion coefficient that matches or is very close to the thermal expansion coefficient of the piezoelectric vibrating piece 40 and the lid described later as a preferable material. In this embodiment, for example, a ceramic green sheet is used.

This green sheet is obtained by, for example, dispersing a ceramic powder in a predetermined solution, forming a kneaded product formed by adding a binder into a sheet-like long tape shape, and cutting it into a predetermined length. It is what
That is, the package 31 is formed by laminating and sintering green sheets formed in the shape of FIG.

Here, an electrode portion 33 is formed on the substrate constituting the bottom portion of the package 31.
As shown in FIG. 2, the green sheet stacked on the substrate is a frame shape from which the inner material is removed, and by stacking this on the substrate, the package 31 has a box shape having an internal space S. It is a container.
On the ceramic material forming the package 31, for example, after forming a required conductive pattern using a conductive paste such as silver or palladium or a conductive paste such as tungsten metallization, and after sintering, Nickel and gold or silver are sequentially plated to form the electrode portion 33 described above.

The electrode portion 33 is connected to mounting terminals 32 and 32 exposed on the bottom surface of the package 31 by a conductive pattern (not shown). The conductive pattern for connecting the electrode portion 33 and the mounting terminal 32 may be formed on the surface of a castellation (not shown) used when the package 31 is formed, and the outer surface of the package 31 may be drawn around. Alternatively, the connection may be made by a conductive through hole penetrating an insulating substrate constituting the bottom of the package 31.
The piezoelectric vibrating piece 40 is accommodated in the internal space S as will be described later.
A lid 35 made of a metal such as ceramic, glass, or kovar is bonded to the package 31 via a low melting point glass, nickel, or the like in a sealing process described later. Thereby, the package 31 is hermetically sealed.

Next, a method of forming the piezoelectric vibrating piece will be described with reference to the flowchart of FIG.
(Outline forming process)
FIG. 4A is a schematic plan view showing a crystal wafer 45 as a piezoelectric substrate for cutting out an element piece for producing the piezoelectric vibrating piece 40.
In this case, the crystal wafer is cut out from the crystal single crystal so that the crystal axis of the crystal is the electric axis, the Y axis is the mechanical axis, and the Z axis is the optical axis. In addition, when cutting from a single crystal of quartz, an AT-cut quartz plate cut out at a predetermined angle, for example, 35.15 degrees from the Z axis in the above-described orthogonal coordinate system consisting of the X, Y, and Z axes. obtain.

Next, the main surface of the AT-cut quartz plate, which is the piezoelectric element piece, is polished to have flatness to form a so-called quartz wafer, which is wet-etched to obtain an element piece assembly to be described later.
That is, by wet-etching the crystal wafer, a large number of element pieces are simultaneously formed in the vertical and horizontal directions of the crystal wafer 45. In this case, the outer periphery of each element piece is separated, and a thin support portion is connected to the frame-shaped quartz material remaining after etching.
4 (b) to 4 (d) and FIG. 5 (a) show DD cross sections in the order of processing in a region where one element piece of the crystal wafer 45 of FIG. 4 (a) is formed.

  As shown in FIG. 4B, the crystal wafer 45 is washed with pure water (ST11), and then a base layer 61 is provided on the surface of the crystal wafer 45. This is made up to compensate for the fact that the metal serving as the corrosion-resistant film has a weak adhesion to a piezoelectric material such as quartz, and the underlayer 61 is made of, for example, Cr (chromium) by sputtering or vapor deposition. . On top of this, gold (Au) is formed as a corrosion-resistant layer 62 by sputtering or vapor deposition. In addition, since the same film | membrane is formed in the front and back of the quartz wafer 45, only the upper code | symbol is shown in a cross section.

Next, as shown in FIG. 4C, a resist 63 is applied to the entire surface of the corrosion-resistant layer 62, and exposed and developed to form a mask (ST13).
Subsequently, as shown in FIG. 4D, gold, which is the corrosion-resistant layer 62 exposed from the mask opening, is wet-etched using, for example, a potassium iodide solution, and then is etched using a 2 ceric ammonium nitrate solution. The chromium 61 that is the formation is etched (ST14).
Next, the quartz exposed from the mask opening is wet etched using, for example, an ammonium fluoride solution (ST15). Thereby, the element piece 51 is formed as shown in FIG.
Subsequently, the resist 63 is peeled off, and all of the corrosion-resistant layer 62 and the underlying layer 61 are removed using the solution used for each etching (ST16).
In the outer shape forming process, the outer shape of the element piece is formed by wet etching, so that the outer shape is easily formed. In particular, the process efficiency is high by performing wet etching instead of dry etching. It is.

(Electrode formation process)
FIG. 5B is a schematic plan view showing the element piece assembly 50 in a state where a large number of element pieces 51 are formed on the crystal wafer 45 through the above-described steps.
A large number of element pieces 51 are formed on the crystal wafer 45 of the element piece assembly 50 in the vertical and horizontal directions. Each element piece 51 is separated in outer shape and surrounded by a crystal wafer 45 in a frame shape. Only the thin frame portions 52 and 52 are integrally connected to the frame-shaped portion.
The frame portions 52 and 52 are folding portions, and the individual piezoelectric vibrating pieces are separated by folding the folding portions in a later step.
The folding part is composed of two frame parts 52, 52 per element piece 51, but may be one, or three or more.

FIG. 5C is a schematic plan view showing an enlarged part of one element piece 51 formed in the element piece assembly 50.
Next, an electrode film-forming mask 53 is placed (ST17). The mask 53 is, for example, a metal mask, is set for the entire element piece assembly 50, and has the same number of mask openings 53 a as the element pieces 51.
With this mask 53, the regions 54-1, 54-1 and 54-2, 54-3, which are deformed due to the etching anisotropy of the element piece 51 and do not require electrode formation, are blocked. Yes.
Among these, in FIG. 5C, with respect to the crystal axis of the crystal, when the X axis is the electric axis, the Y axis is the mechanical axis, and the Z axis is the X axis, the Y axis, and the Z axis, the optical axis, An orthogonal coordinate system is shown in which the Y and Z axes after rotating 35.15 degrees around the X axis are designated as “Y ′ axis and Z ′ axis”. In this case, due to the etching anisotropy of quartz, for example, the region 54-1 has an irregular end surface as shown in FIG. 10A, and the region 54-2 has an irregular shape as shown in FIG. Corresponds to the location of the end face.

In FIG. 6A, an electrode film 55 is formed in a region exposed from the mask 53 (ST18). Here, in FIGS. 6D and 7, the left side is a plan view, and the right side is a cross-sectional view taken along line EE.
The electrode film 55 includes, for example, a base layer and an electrode layer, and chromium or nickel is suitable for the base layer, and gold is suitable for the electrode layer. That is, if the base layer and the electrode layer are made the same as the base layer and the corrosion-resistant layer formed in ST14, there is an advantage that they can be formed using, for example, the same sputtering apparatus and target.
FIG. 6B is a partially enlarged cross-sectional view showing the relationship between the size of the mask opening 53 a of the electrode film forming mask 53 and the thickness of the mask 53.

From here, only the element piece 51 is illustrated and described for convenience of understanding, but the frame portions 52 and 52 which are the folding portions are still connected to the crystal wafer.
The electrode film 55 formed inside the mask opening 53a using the electrode film forming mask 53 is formed larger than the range that will eventually become the excitation electrode, as an electrode for driving the piezoelectric vibrating piece. (FIG. 6C).
That is, as shown in FIG. 6B, the electrode film 55 formed by using the electrode film forming mask 53 is a film of the electrode film in the peripheral portion of the region W1 close to the mask opening 53a. The thickness becomes uneven.
This is because in the vicinity of the mask opening 53a, the adhesion of the metal material is hindered during film formation. As a result, the film formation is non-uniform, and the film thickness in the region W1 is too thin and partial separation may occur. Such a portion is inferior in reliability and cannot be used as a driving electrode.
In addition, when a non-uniformly deposited portion is used as an electrode, frequency variation occurs.
The inventor of the present invention pays attention to such a phenomenon, forms a mask opening 53a larger, and removes the W1 region, which is the peripheral portion of the electrode film 55 to be formed, in a process described later, thereby driving. Therefore, the electrode for use is precisely formed.

Specifically, in the electrode film forming mask 53, the mask opening 53a is formed larger than the area DE used as the excitation electrode, which is actually the driving electrode, by the area W1. Yes. As a result, the formed electrode film 55 has a large excitation electrode which is a finally required driving electrode.
Preferably, the dimension of W1 is equal to or larger than the thickness dimension t1 of the electrode deposition mask 53 (W1 ≧ t1).
That is, the range W1 of a region where a non-uniform film formation portion is formed at a location close to the peripheral edge of the opening varies depending on the dimension of the thickness t1 of the electrode film formation mask 53. For this reason, in considering the dimensional difference between the edge portion of the opening 53a of the electrode film forming mask 53 and the outer edge portion of the final outer shape of the driving electrode, the dimension W1 is set to the mask thickness dimension t1 or more. As a result, it is possible to secure a sufficient range for removing an electrode having a necessary area as a piezoelectric vibrating piece by removing such a region in a subsequent photolithography process.
Here, when W1 is the smallest, it is the same as the thickness dimension t1 of the electrode film forming mask 53. However, if it is larger than this, there is no theoretical limit. However, of course, it is not preferable to make a useless area to be deleted later larger than necessary. Therefore, when W1 is slightly larger than the thickness dimension t1 of the electrode film forming mask 53, unnecessary electrode film formation can be minimized and a precise electrode can be reliably formed.

Next, a subsequent photolithography process will be described.
Next, as shown in FIG. 6D, a resist 56 is applied over the entire surface (ST20).
In FIG. 7A, the resist 56 is patterned by exposure and development using a mask (not shown) to expose an unnecessary portion (W1) of the electrode film 55 (ST21).
Next, as shown in FIG. 7B, the exposed unnecessary electrode film 55 is removed by etching (ST22), and the resist 56 is removed (ST23). As shown in FIG. In 51, an excitation electrode 41 and extraction electrodes 42 and 42 are formed.
Subsequently, the piezoelectric vibrating reed 40 is cut off by bending the individual piezoelectric vibrating reeds 40 from the element piece assembly 50.
Thus, the piezoelectric vibrating piece 40 described in FIGS. 1 and 2 is completed.
As is apparent from the above description, the mask opening 53a of the electrode film forming mask 53 in ST17 described above is larger than the resist pattern after exposure and development (see reference numeral 56 in FIG. 7A). An opening having a predetermined area is provided.
Therefore, the mask opening 53a of the electrode film forming mask 53 is larger than the pattern of the drive electrode drawn on the mask at the time of exposure and development performed in the step of leaving the resist 56 in FIG. It can be seen that an opening having a predetermined area is provided.

Thus, in the above-described method for manufacturing a piezoelectric vibrating piece, the mask 53 is disposed in a portion that is deformed due to the influence of etching anisotropy so that the electrode film 55 is not formed. For this reason, compared with the conventional method in which an electrode film is formed on the entire surface and then a mask is provided to expose an electrode film in an unnecessary region and etching is performed, an electrode at a location that is deformed due to the influence of etching anisotropy Separation is ensured and the electrode film can be formed more precisely.
This manufacturing method can also be applied to an isotropic piezoelectric material, and is formed nonuniformly in the electrode film forming step (ST12) in the opening area of the electrode film forming mask 53. Thus, an area having a necessary area as the piezoelectric vibrating piece 40 can be precisely formed by removing it later by photolithography in ST22.

(Joining process)
Next, a conductive adhesive 43 is applied on the electrode portion 33 on the package 31 side of FIGS. 1 and 2 formed separately from the piezoelectric vibrating piece.
Then, on the conductive adhesive 43, the base end portion or one end portion of each of the piezoelectric vibrating reeds 40 on which the respective extraction electrodes 42 described with reference to FIG.
The piezoelectric adhesive piece 40 is joined to the inner bottom surface of the package 31 in a cantilever manner by heating and curing the conductive adhesive 43.
Here, as the conductive adhesive 43, a binder component made of a predetermined synthetic resin to which conductive particles such as silver particles are added can be used. Further, the piezoelectric vibrating piece 40 is not necessarily a cantilever type, and may be configured such that a part of the tip side is placed on a convex part (pillow part) formed on the inner bottom surface of the package 31.

Then, a driving voltage is applied to the piezoelectric vibrating piece 40 from the mounting terminal 32 of the package 31, the piezoelectric vibrating piece 40 is driven to measure its frequency, and one of the excitation electrodes 41 is measured based on the measurement result. By reducing the number of parts, the weight is reduced and the frequency is adjusted.
In this frequency adjustment step, the drive voltage is applied by changing the ambient temperature environment, the frequency corresponding to the temperature change is measured, and the temperature-frequency characteristics of the piezoelectric vibrating piece 40 are measured together. Make adjustments accordingly.

Next, the package 31 is moved into a vacuum chamber, and a lid 35 formed of a metal such as ceramic, glass, or kovar is bonded in a vacuum atmosphere via low melting point glass, nickel, or the like. Thereby, the package 31 is hermetically sealed.
Finally, through the necessary inspection, the piezoelectric device 30 is completed.

The present invention is not limited to the above-described embodiment. In the above embodiment, each region of 54-1, 54-2, and 54-3 in FIG. 5C is shown as a region covered with a mask because it becomes irregular due to etching anisotropy. It is not necessary to cover all of these regions with a mask, and if etching anisotropy occurs in addition to these depending on etching conditions, an electrode film may be formed by covering such regions with a mask. Of course.
Further, as described above, the present invention can also be applied to a piezoelectric vibrating piece formed by using an isotropic piezoelectric material in etching.
Furthermore, each configuration of the above-described embodiment can be appropriately combined or omitted, and can be combined with other configurations not shown.
The present invention can be applied to all piezoelectric devices regardless of the names of piezoelectric vibrators, piezoelectric oscillators, etc., as long as they use a package or a case and accommodate a piezoelectric vibrating piece therein.

1 is a schematic plan view of a piezoelectric device according to an embodiment of the present invention. CC schematic sectional drawing of FIG. The flowchart which shows an example of the manufacturing method of the piezoelectric vibrating piece accommodated in the piezoelectric device of FIG. FIG. 2 is a process diagram sequentially illustrating an example of a manufacturing process of the piezoelectric vibrating piece of FIG. 1. FIG. 2 is a process diagram sequentially illustrating an example of a manufacturing process of the piezoelectric vibrating piece of FIG. 1. FIG. 2 is a process chart sequentially illustrating an example of a manufacturing process of the piezoelectric vibrating piece of FIG. FIG. 2 is a process diagram sequentially illustrating an example of a manufacturing process of the piezoelectric vibrating piece of FIG. 1. The figure which shows a part of manufacturing process of the conventional piezoelectric vibrating piece. The schematic plan view of the element piece before forming a drive electrode in a piezoelectric vibrating piece. FIG. 10 is a partial cross-sectional view of FIG. 9.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 30 ... Piezoelectric device, 31 ... Package, 40 ... Piezoelectric vibrating piece, 41 ... Excitation electrode, 50 ... Element piece assembly, 51 ... Element piece, 53 ... Mask

Claims (5)

A method of manufacturing a piezoelectric vibrating piece, comprising: an outer shape forming step of etching a piezoelectric substrate to form an element piece of a piezoelectric vibrating piece; and an electrode forming step of forming a driving electrode after the outer shape is formed,
In the electrode forming step,
Using a mask for electrode film formation, a metal film to be an electrode film is formed,
A resist is applied to the surface of the electrode film, and after exposure / development, etching is performed to form a driving electrode having a required final outer dimension,
In addition, the method for manufacturing a piezoelectric vibrating piece, wherein the electrode deposition mask includes an opening having a predetermined area larger than a final outer shape of the required electrode. A method of manufacturing a piezoelectric vibrating piece, comprising: an outer shape forming step of etching a piezoelectric substrate to form an element piece of a piezoelectric vibrating piece; and an electrode forming step of forming a driving electrode after the outer shape is formed,
In the electrode forming step,
Using a mask for electrode film formation, a metal film to be an electrode film is formed,
A resist is applied to the surface of the electrode film, and after exposure / development, etching is performed to form a driving electrode having a required final outer dimension,
The method of manufacturing a piezoelectric vibrating piece, wherein the electrode film forming mask has an opening having a predetermined area larger than the resist pattern after the exposure and development. A method of manufacturing a piezoelectric vibrating piece, comprising: an outer shape forming step of etching a piezoelectric substrate to form an element piece of a piezoelectric vibrating piece; and an electrode forming step of forming a driving electrode after the outer shape is formed,
In the electrode forming step,
Using a mask for electrode film formation, a metal film to be an electrode film is formed,
A resist is applied to the surface of the electrode film, and after exposure / development, etching is performed to form a driving electrode having a required final outer dimension,
The method of manufacturing a piezoelectric vibrating piece, wherein the electrode film forming mask has an opening having a predetermined area larger than a pattern of a driving electrode drawn on the mask used for the exposure.   The dimensional difference between the opening edge of the electrode deposition mask and the outer edge of the final outer shape of the driving electrode is equal to or greater than the thickness dimension of the electrode deposition mask. A method for manufacturing a piezoelectric vibrating piece according to any one of claims 1 to 3. A method of manufacturing a piezoelectric device in which a piezoelectric vibrating piece is accommodated in a package or case,
After forming a plurality or a plurality of the piezoelectric vibrating pieces on the piezoelectric substrate, the individual piezoelectric vibrating pieces are separated from the piezoelectric substrate,
A bonding step of bonding the piezoelectric vibrating piece to a connecting electrode portion formed on a package or an electrode of a plug attached to the case;
The method for manufacturing a piezoelectric device, wherein the piezoelectric vibrating piece is formed by the method according to any one of claims 1 to 4.

Images