JP2008035013A - Manufacturing method of piezoelectric vibrator, piezoelectric vibrator, and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of deformation of the outward appearance of a crystal vibrator chip or an increase in the number of ridgelines of the crystal vibrator chip because of formation after a metallic film with a decreased size in the case of forming a groove on the crystal vibrator chip by using the metallic film for a mask because the outer circumferential part of the metallic film is etched to decrease the size of the metallic film when an opening corresponding to the groove of the crystal vibrator chip is formed on the metallic film acting like the mask of the crystal vibrator chip by etching. <P>SOLUTION: The groove is formed before forming the outward appearance of the crystal vibrator chip and the metallic film is formed on the groove when the outward appearance of the crystal vibrator chip is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for manufacturing a piezoelectric vibrator made of, for example, quartz.

  The tuning fork type crystal resonator is small, inexpensive, and has low power consumption, so that it has been conventionally employed as a signal source for engraving the rate of a wristwatch, and its application is going to expand. Recently, there is a strong demand for a smaller CI value (crystal impedance), and a crystal vibrating piece having a groove is used.

  As shown in FIG. 10, the tuning fork type crystal resonator 100 includes a base 1 and a pair of vibrating arm portions 2 a and 2 b provided on the base 1. Groove parts 31 and 32 are provided on both main surfaces of the vibrating arm parts 2a and 2b, respectively, and the groove parts 31 and 32 and the vibrating arm parts 2a and 2b excite tuning fork vibration based on flexural vibration. An excitation electrode (not shown) is formed. By causing a current to flow through the excitation electrode, the crystal unit 100 is vibrated.

  The crystal unit 100 is manufactured by the following process (see Patent Document 1). 11 to 12 are cross-sectional views of the crystal unit 100 taken along the line A-A ′ in FIG. 10. First, after polishing and cleaning the cut crystal wafer 10, a metal film 11 is formed by sputtering (FIG. 11A). The metal film 11 is a film in which gold (Au) is formed on a chromium (Cr) base film, for example.

  Subsequently, after a resist film 12 is applied to the surface of the metal film 11 (FIG. 11B), exposure and development processes are performed to form a crystal piece 17 shape, that is, a tuning fork pattern in the resist film 12 (FIG. 11). 11 (c)). Then, after a pattern corresponding to the pattern of the resist film 12 is formed on the metal film 11 by etching, the resist film 12 is peeled off (FIG. 11D).

  Next, a resist film 13 is formed on the entire surface of the quartz wafer 10 (FIG. 11E), and the resist film 13 corresponding to the openings of the pattern of the metal film 11 and the grooves 31 and 32 shown in FIG. It peels (FIG.12 (f)). Then, the crystal wafer 10 is immersed in hydrofluoric acid, and the outer shape of the crystal piece 17 is formed using the metal film 11 as a mask (FIG. 12G). At this time, the crystal piece 17 is etched so as to be slightly smaller than the outer shape of the metal film 11, and the end of the metal film 11 is exposed. Subsequently, the portion of the metal film 11 corresponding to the groove 31 in FIG. 10 is etched (FIG. 12H). By this etching, the metal film 11 exposed by the etching of the crystal wafer 10 described above is etched at the end from the crystal piece 17 side, and the size is reduced. Then, the crystal piece 17 is immersed in hydrofluoric acid, and the groove portions 31 are formed on both main surfaces of the crystal piece 17 using the metal film 11 as a mask (FIG. 12 (i)). Since the outer dimension of the metal film 11 is reduced by the etching of the metal film 11, the outer shape of the crystal piece 17 is the same as the etching of the crystal wafer 10 in FIG. Etching is performed to be slightly smaller than the outer shape. Thereafter, the metal film 11 and the resist film 13 are removed (FIG. 12 (j)).

  Thereafter, a metal pattern is formed on the crystal piece 17 as follows. First, the metal film 14 and the resist film 15 are laminated in this order on the surface of the crystal piece 17 (FIG. 13K), and a metal wiring pattern is formed on the resist film 15 (FIG. 13L). Next, a metal wiring pattern is formed on the metal film 14 by etching using the resist film 15 as a mask (FIG. 13 (m)), and the resist film 15 is removed (FIG. 13 (n)). Thereafter, the crystal unit 100 is manufactured through cutting, cleaning, inspection, and the like of the crystal unit 100. However, this manufacturing method has the following problems.

  In the etching of the metal film 11 in FIG. 12H described above, the metal film 11 has an outer shape of the crystal piece 17 as shown in FIG. Smaller than. When the crystal piece 17 is etched in FIG. 12 (i), the corner portion of the crystal piece 17 is etched, and the corner portion of the crystal piece 17 is chamfered as shown in FIG. 14B. It will be in a state. When such a corner portion is formed, it becomes difficult to balance the vibration direction between the vibrating arm portions 2a and 2b, so that the electric field efficiency is lowered and the CI value is increased.

  13K, when the resist film 15 is formed on the surface of the metal film 14, the resist film 15 is difficult to get on the ridge line 16 (corner) of the crystal piece 17 due to surface tension. Etching of the film 14 may cause poor conduction or disconnection of the electrode pattern. Therefore, as shown in FIG. 14B, when the ridgeline 16 is increased to two places, poor conduction or disconnection is likely to occur.

  Patent Documents 2 and 3 describe a method of manufacturing a crystal resonator for the purpose of reducing defects in the piezoelectric element pieces, accurate etching, or reducing the number of processes. However, no consideration should be given to the problems described above. It has not been.

JP-A-2002-76806 ((0094) to (0113), FIGS. 12 to 11) JP-A-2004-104365 ((0031) to (0037), FIGS. 7 and 10) JP-A-2005-65234 ((0017), (0019))

  The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a favorable shape for the outer shape of the piezoelectric vibrating piece, and as a result, reduce the conduction failure of the electrodes formed on the piezoelectric vibrator. Another object of the present invention is to provide a piezoelectric vibrator manufacturing method capable of suppressing an increase in CI value, a piezoelectric vibrator manufactured by the method, and an electronic component including the piezoelectric vibrator.

The method for manufacturing the piezoelectric vibrator of the present invention includes:
In the method of manufacturing a piezoelectric vibrating piece in which a groove is formed in each of the plurality of vibrating arms extending from the base,
Forming a metal film on the surface of the substrate which is a piezoelectric substrate;
Forming a resist film having an opening corresponding to the groove of the vibrating arm on the surface of the metal film, and forming a pattern on the metal film by etching; and
Next, the substrate is brought into contact with an etching solution, and using the metal film as a mask, grooves are respectively formed in portions corresponding to the plurality of vibrating arm portions;
Removing all of the metal film and the resist film;
Forming a metal film on the surface of the substrate;
Forming a patterned resist film on the surface of the metal film so that a shape portion of the piezoelectric vibrating piece remains, and forming a pattern on the metal film by etching;
Contacting the substrate with an etchant and forming an outer shape of the piezoelectric vibrating piece using the metal film as a mask;
And thereafter forming an electrode pattern made of a metal film on the piezoelectric vibrating piece.

In addition, the method of manufacturing the piezoelectric vibrator of the present invention includes
After the step of bringing the substrate into contact with an etching solution and forming the outer shape of the piezoelectric vibrating piece using the metal film as a mask,
Removing the resist film;
Forming a resist film on the surface of the substrate so that the resist remains at the tip portion of the vibrating arm serving as a region for forming a metal film for frequency adjustment, and removing the metal film by etching;
And then peeling off the resist film remaining on the tip of the vibrating arm, and then forming a metal film on the entire surface of the quartz crystal vibrating piece and then forming an electrode pattern made of the metal film using a resist mask. It is characterized by performing the process to do.

In addition, the method of manufacturing the piezoelectric vibrator of the present invention includes
Instead of the step of peeling all the metal film and resist film,
Removing the resist film;
Forming a resist film on the surface of the substrate so that the resist remains at the tip portion of the vibrating arm serving as a region for forming a metal film for frequency adjustment, and removing the metal film by etching;
Next, removing the resist film remaining on the tip of the vibrating arm, and
The step of forming the electrode pattern is a step of forming an electrode pattern made of a metal film using a resist mask after forming a metal film on the entire surface of the quartz crystal vibrating piece.

The piezoelectric vibrator of the present invention is manufactured by the manufacturing method described above.
The electronic component of the present invention includes the piezoelectric vibrator, a container for housing the piezoelectric vibrator, and an external electrode formed on the outer surface of the container and electrically connected to the electrode of the piezoelectric vibrator. And.

  According to the present invention, for example, when a tuning fork type piezoelectric vibrating piece is formed by etching, a groove is formed in a portion corresponding to the arm portion of the piezoelectric vibrating piece before the outer shape of the piezoelectric vibrating piece is formed on the piezoelectric substrate. Therefore, etching of the corners of the outer shape of the piezoelectric vibrating piece can be suppressed, and conduction failure and an increase in CI value can be suppressed.

Next, an embodiment of the present invention will be described with reference to FIG. Since the crystal unit 5 according to this embodiment has the same structure as the crystal unit 100 described above shown in FIG. 10, the description of the overlapping parts is omitted.
As shown in FIG. 1, the crystal resonator 5 is formed with a pair of excitation electrodes 41 and the other excitation electrode 51. The entire inner surface of the two groove portions 31 and 32 of the vibrating arm portion 2a and the so-called bridge portion between the groove portions 31 and 32, and both side surfaces 21 and 21 and the main surfaces 22 and 22 (front side and back side) of the vibrating arm portion 2b. One excitation electrode 41 is formed at a position above the groove 31. Further, the entire inner surface of the two groove portions 31 and 32 of the vibrating arm portion 2b and between the groove portions 31 and 32, and the groove portions 31 on both side surfaces 21 and 21 and the main surfaces 22 and 22 (front side and back side) of the vibrating arm portion 2a. The other excitation electrode 51 is formed in the upper part.

On the surface of the base portion 1, an electrode pattern composed of extraction electrodes 42 is formed so that the one excitation electrodes 41 are electrically connected to each other, and the other excitation electrodes 51 are electrically connected to each other. Thus, an electrode pattern composed of the lead electrodes 52 is formed.
Further, adjustment weights 50 and 40 made of a metal film are formed at the tips of the vibrating arms 2a and 2b, respectively, and by adjusting the weight (film thickness), the oscillation frequency of the crystal resonator 5 can be adjusted. Can be adjusted. The adjustment weights 50 and 40 form a part of the excitation electrodes 51 and 41, but are different in thickness and material from other parts of the electrode, for example. The hatched area in FIG. 1 is a section used to make the electrode pattern easy to see, and does not represent a cross section.

Next, a manufacturing method of the crystal unit 5 shown in FIG. 1 will be described with reference to FIGS. 2 to 5 show a cut surface of the crystal unit 5 in a plane A passing through the groove 31 parallel to the XZ plane in FIG.
First, after polishing and cleaning the crystal wafer 60 which is the cut substrate, a metal film 61 is formed by sputtering (FIG. 2A). The metal film 61 is a film in which gold (Au) is formed on a base film of, for example, chromium (Cr).

Subsequently, after a resist film 62 is formed on the metal film 61 by, for example, a spray method (FIG. 2B), exposure and development processing are performed, and the resist film 62 is patterned so as to have the shape of the groove 31. (FIG. 2 (c)). Then, the quartz wafer 60 is immersed in a potassium iodide (KI) solution, which is a metal etching solution, and an opening corresponding to the groove 31 is formed in the metal film 61 (FIG. 2D).
Next, this crystal wafer 60 is immersed in hydrofluoric acid as an etching solution to form the groove 31 in the crystal wafer 60 (FIG. 3E). The dimension of the groove 31 is formed following the pattern of the metal film 61. However, since the etching solution spreads inside the opening, the dimension is slightly larger than the opening dimension of the metal film 61 as shown in FIG.

  Thereafter, the resist film 62 and the metal film 61 are removed (FIG. 3F). Then, a metal film 63 is formed on the surface of the quartz wafer 60 by, for example, sputtering, and a resist film 64 is formed on the surface by, for example, spraying (FIG. 3G). Next, exposure and development processes are performed, and the resist film 64 is patterned so as to have a crystal piece 65 shape, that is, a tuning fork shape (FIG. 3 (h)), and then the crystal wafer 60 is immersed in a potassium iodide solution. Then, a pattern corresponding to the pattern of the resist film 64 is formed on the metal film 63 (FIG. 3I).

  Next, this crystal wafer 60 is immersed in hydrofluoric acid to form the outer shape of the crystal piece 65 (FIG. 4 (j)). At this time, a metal film 63 is formed in the groove portion 31 formed in the above-described FIG. 3E, and the crystal piece 65 in the groove portion 31 is not eroded by this etching, and the depth of the groove portion 31 is reduced. No change or etching of the corner (projection) of the groove 31 occurs. The external dimensions of the crystal piece 65 are formed following the pattern of the metal film 63. However, since the etching solution spreads inside the opening, the dimension of the opening of the metal film 63 is larger than that shown in FIG. Slightly smaller dimensions.

  Next, after peeling off the resist film 64 and the metal film 63 (FIG. 4K), an electrode pattern is formed. First, a metal film 71 to be an electrode and a resist film 72 are laminated in this order on the surface of the crystal piece 65 by using, for example, sputtering (FIG. 4L). The metal film 71 is a film in which gold (Au) is formed on the surface of a base film of chromium (Cr), for example. The resist film 72 is formed by, for example, a spray method in the same manner as described above. Thereafter, the resist film 72 is patterned so as to correspond to the electrode patterns on the main surfaces 22 and 22 of the vibrating arm portions 2a and 2b (FIG. 5M). Then, an electrode pattern is formed on the metal film 71 by etching using the resist film 72 as a mask (FIG. 5 (n)), and then the resist film 72 is peeled off (FIG. 5 (o)). Then, as shown in FIG. 6, the crystal resonator 5 is cut out from the substrate on which the plurality of crystal resonators 5 are formed. A line formed so as to surround the plurality of crystal resonators 5 in FIG. 6 indicates the boundary between the substrate and the recess formed by etching.

  According to the above-described embodiment of the present invention, since the groove portion 31 is formed before the crystal wafer 60 is etched into the shape of the crystal piece 65, the etching of the corner portion of the crystal piece 65 can be suppressed. The variation in the direction of vibration between the vibrating arm portions 2a and 2b can be suppressed, an increase in CI value can be suppressed, and an increase in the number of ridge lines of the crystal piece 65 can be suppressed, and the corner of the crystal piece 65 can be reduced. It is possible to suppress an increase in energization failure or disconnection due to the etching of the metal film 71 in the portion.

  Further, when the crystal wafer 60 is etched into the shape of the crystal piece 65, the metal film 63 is formed on the surface of the groove 31, so that the outer shape of the crystal unit 5 can be uniquely determined. That is, in the conventional process (after forming the outer shape of the crystal piece 65 first, the groove portion 31 is formed), the outer shape of the crystal piece 65 is etched simultaneously with the formation of the groove portion 31, so The depth and the width of the crystal piece 65 are simultaneously reduced, and it is very difficult to control the shape of the crystal unit 5. However, the shape of the crystal unit 5 can be easily controlled by forming the width of the crystal piece 65 and the depth of the groove 31 while suppressing the interference. In addition, when forming the width of the crystal piece 65 and the depth of the groove portion 31 while suppressing the interference, it is not necessary to increase the number of steps such as forming a mask for protecting the crystal wafer 60 separately. The shape of the crystal unit 5 can be easily controlled without sacrificing the performance.

  Next, the case of forming the adjustment weights 50 and 40 at the tips of the vibrating arm portions 2a and 2b in FIG. 1 will be described with reference to FIGS. 7 and 8 in FIG. 1, the crystal resonator 5 in the plane A passing through the groove 31 parallel to the XZ plane and the plane B passing through the adjustment weights 50 and 40 parallel to the plane A in FIG. Represents a cut surface.

  First, after the outer shape of the crystal piece 65 is formed in FIG. 4J (FIG. 7J), the resist film 64 is peeled off, and a resist film 66 is formed on the surface of the crystal piece 65 by, for example, a spray method (see FIG. FIG. 7 (j ′)). Then, the resist film 66 other than the formation region of the adjustment weights 50 and 40 which are the tip portions of the vibrating arm portions 2a and 2b is removed by exposure and development processing (FIG. 7 (j ″)). Next, the crystal piece 65 is immersed in a potassium iodide (KI) solution to remove the metal film 61 other than the tip portions of the vibrating arm portions 2a and 2b, and then the resist film 66 is peeled off (FIG. 7 (k)). ). Through the above steps, the crystal piece 65 in which no electrode pattern is formed is manufactured.

  Thereafter, an electrode pattern is formed on the surface of the crystal piece 65 (FIGS. 8 (l) to (o)) in the same manner as in FIGS. 4 (l) to 5 (o). First, a metal film 71 serving as an electrode and a resist film 72 are stacked in this order on the surface of the crystal piece 65 (FIG. 8L). Thereafter, the resist film 72 is patterned so as to correspond to the electrode patterns of the main surfaces 22 and 22 of the vibrating arm portions 2a and 2b (FIG. 8 (m)). Then, an electrode pattern is formed on the metal film 71 by etching using the resist film 72 as a mask (FIG. 8 (n)), and then the resist film 72 is peeled off (FIG. 8 (o)). Then, after adjusting the vibration frequency of the crystal unit 5 by adjusting the film thickness of the adjustment weights 50 and 40, the crystal unit 5 is cut out from the substrate of FIG.

  In this example, the metal film 63 is used to form the adjustment weights 50 and 40, but the metal film 61 may be used. That is, in FIG. 3E, after the resist film 62 is peeled off, a resist mask is formed so as to cover the formation regions of the adjustment weights 50 and 40, and a metal film other than the formation regions of the adjustment weights 50 and 40 is formed. The metal film 61 may be used as the adjustment weights 50 and 40 by removing 61 and performing the steps after FIG.

  As described above, since the metal film 63 that is a mask for etching the crystal piece 65 is left at the tip of the crystal unit 5 and the metal film 71 that is an electrode pattern is formed, Since the film thickness of the metal at the tip of the vibrating arms 2a and 2b is increased, the range in which the film thickness of the metal film (adjustment weights 50 and 40) can be adjusted after the crystal resonator 5 is manufactured is expanded. The adjustment range of the vibration frequency of the child 5 can be widened, and a decrease in yield can be suppressed. Further, when, for example, gold is used as the metal films 61 and 63, the material cost of the adjustment weights 50 and 40 can be saved.

  For example, as shown in FIG. 9, the above-described crystal resonator 5 is housed in a package 8 made of ceramics having a surface mounted device (SMD) structure, and constitutes an electronic component. The package 8 includes a case body 8a made of, for example, a ceramic whose upper surface is open, and a lid body 8b made of, for example, a metal. The case body 8a and the lid body 8b are seam welded via a sealing material 8c made of, for example, a welding agent, and the inside thereof is in a vacuum state. The crystal resonator 5 has a lateral posture in which the base 1 is fixed to the base 81 in the package 8 by the conductive adhesive 8d, and the vibrating arms 2a and 2b extend into the space inside the package 8. Further, the lead electrodes 42 and 52 of the base 1 are connected to the conductive paths 82 and 83 (83 is a conductive path on the back side of the drawing) formed on the surface of the base 81 by the conductive adhesive 8d described above. ing. The conductive paths 82 and 83 are respectively connected to electrodes 84 and 85 formed at both ends in the longitudinal direction of the outer bottom surface of the case body 8a, and the electrodes 84 and 85, the conductive paths 82 and 83, and the conductive adhesive 8d are connected to each other. The crystal resonator 5 is configured to vibrate when a current flows through the extraction electrodes 42 and 52 through the crystal resonator 5. FIG. 9A shows a cross-sectional view of the package 8, and FIG. 9B shows a plan view seen from below the package 8 (case body 8a side). This electronic component is installed on a wiring board (not shown) on which circuit components of the oscillation circuit are mounted, thereby forming a crystal oscillator.

It is a perspective view which shows an example of the tuning fork type | mold crystal resonator based on embodiment of this invention. It is sectional drawing which shows an example of the manufacturing method of the above-mentioned tuning fork type crystal resonator. It is sectional drawing which shows an example of the manufacturing method of the above-mentioned tuning fork type crystal resonator. It is sectional drawing which shows an example of the manufacturing method of the above-mentioned tuning fork type crystal resonator. It is sectional drawing which shows an example of the manufacturing method of the above-mentioned tuning fork type crystal resonator. It is a top view which shows an example of the above-mentioned tuning fork type crystal resonator. It is sectional drawing which shows an example of the manufacturing method of the above-mentioned tuning fork type crystal resonator. It is sectional drawing which shows an example of the manufacturing method of the above-mentioned tuning fork type crystal resonator. It is explanatory drawing which shows an example of the package which stored the above-mentioned tuning fork type crystal resonator. It is a schematic plan view which shows an example of a tuning fork type crystal resonator. It is sectional drawing which shows the manufacturing method of the conventional tuning fork type crystal resonator. It is sectional drawing which shows the manufacturing method of the conventional tuning fork type crystal resonator. It is sectional drawing which shows the manufacturing method of the conventional tuning fork type crystal resonator. It is sectional drawing of the vibration arm part of the conventional tuning fork type crystal resonator.

Explanation of symbols

5 Crystal oscillator 41 One excitation electrode 51 The other excitation electrode 60 Crystal wafer 61 Metal film 62 Resist film 63 Metal film 64 Resist film 65 Crystal piece 66 Resist film 71 Metal film 72 Resist film

Claims (5)

In the method for manufacturing a piezoelectric vibrator in which a groove is formed in each of the plurality of vibrating arms extending from the base,
Forming a metal film on the surface of the substrate which is a piezoelectric substrate;
Forming a resist film having an opening corresponding to the groove of the vibrating arm on the surface of the metal film, and forming a pattern on the metal film by etching; and
Next, the step of bringing the substrate into contact with an etching solution, and using the metal film as a mask, forming grooves in portions corresponding to the plurality of vibrating arms,
Removing all of the metal film and the resist film;
Forming a metal film on the surface of the substrate;
Forming a patterned resist film on the surface of the metal film so that the shape portion of the piezoelectric vibrating piece remains, and forming a pattern on the metal film by etching;
Contacting the substrate with an etchant and forming an outer shape of the piezoelectric vibrating piece using the metal film as a mask;
And subsequently forming an electrode pattern made of a metal film on the piezoelectric vibrating piece. After the step of bringing the substrate into contact with an etching solution and forming the outer shape of the piezoelectric vibrating piece using the metal film as a mask,
Removing the resist film;
Forming a resist film on the surface of the substrate so that the resist remains at the tip portion of the vibrating arm portion, which is a region for forming a metal film for frequency adjustment, and removing the metal film by etching;
And then peeling off the resist film remaining on the tip of the vibrating arm, and then forming a metal film on the entire surface of the quartz crystal vibrating piece and then forming an electrode pattern made of the metal film using a resist mask. The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the step of: Instead of the step of peeling all the metal film and resist film,
Removing the resist film;
Forming a resist film on the surface of the substrate so that the resist remains at the tip portion of the vibrating arm serving as a region for forming a metal film for frequency adjustment, and removing the metal film by etching;
Next, removing the resist film remaining on the tip of the vibrating arm, and
The step of forming the electrode pattern is a step of forming an electrode pattern made of a metal film using a resist mask after forming a metal film on the entire surface of the quartz crystal vibrating piece. A method of manufacturing a piezoelectric vibrator.   A piezoelectric vibrator manufactured by the method according to any one of claims 1 to 3. A piezoelectric vibrator according to claim 4, a container for housing the piezoelectric vibrator, and an external electrode formed on an outer surface of the container and electrically connected to an electrode of the piezoelectric vibrator. An electronic component characterized by comprising.

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