JP5007522B2 - Piezoelectric vibrator and manufacturing method thereof - Google Patents

Description

  The present invention relates to a piezoelectric vibrator used in a small electronic device and a manufacturing method thereof.

Small electronic devices are required to be further miniaturized, and piezoelectric vibrators used in small electronic devices are also required to be miniaturized.
Here, since the resonator element used in the piezoelectric vibrator has a smaller crystal impedance (CI) value and easily vibrates as the vibration area is larger, it is necessary to increase the vibration area as much as possible. Therefore, in order to reduce the size of the piezoelectric vibrator while securing the vibration area of the vibration piece, it is necessary to reduce the size of the package that houses the vibration piece. In reducing the size of the package, it is necessary to devise measures such as routing the electrodes provided in the package.
The connection electrodes corresponding to the two vibration electrodes are arranged in the package so that the wiring from the vibration electrodes provided on the opposing surfaces of the vibration pieces can be made compact and the package can be miniaturized and can be connected to the mounting substrate with a minimum area. Various ingenuity has been made to consolidate on one side.
An external electrode is provided in an arc-shaped cutout formed at a corner of the base substrate that supports the vibrator substrate including the resonator element, and the connection electrode and the vibration electrode on the back surface of the base substrate are provided via the external electrode. What is known to connect The piezoelectric vibrator is obtained by forming an aggregate of piezoelectric vibrators using three substrates, which are large substrates, and separating the piezoelectric vibrator from the aggregate. The arc-shaped notch is formed in a state corresponding to a corner portion of each piezoelectric vibrator in the state of the base, and then an external electrode is formed in the hole, and the hole is cut by tracing the hole when separating. (See, for example, Patent Document 1).

JP 2001-267875 A (pages 5 and 6, paragraph number [0033], FIG. 8)

The stress applied when the individual piezoelectric vibrators are separated from the piezoelectric vibrator assembly causes peeling between the external electrode and the connection electrode, the base body, and the vibration electrode. For example, when the piezoelectric vibrator is attached to the mounting substrate The peel strength of the connection electrode cannot be obtained. Moreover, disconnection is likely to occur due to peeling, and electrical reliability cannot be obtained.
SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric vibrator having a high electrical reliability with little peeling between the external electrode and the connection electrode and the substrate when separating the individual piezoelectric vibrators from the aggregate of piezoelectric vibrators, and the production thereof. It is to provide a method.

  The piezoelectric vibrator of the present invention is formed on a vibrator substrate, a base substrate that supports the vibrator substrate, a lid substrate that is stacked on the vibrator substrate, and a surface of the vibrator substrate that faces the lid substrate. The first vibration electrode formed, the second vibration electrode formed on the surface of the vibrator substrate facing the base substrate, and the surface of the vibrator substrate facing the base substrate, And a connection electrode on the bottom surface of the base substrate, the connection electrode including the base electrode Electrically connected to the third vibrating electrode and the second vibrating electrode via an external electrode formed in a notch provided on the outer periphery of the substrate, and the connecting electrode and the external electrode Table of formed surface The piezoelectric vibrator, wherein the average roughness of 0.1 m to 10 m.

  According to the present invention, since the surface on which the external electrode and the connection electrode are formed is roughened, adhesion is obtained by the anchor effect. Therefore, even when the piezoelectric vibrator is mounted on the mounting substrate via the connection electrode, peeling hardly occurs, mounting strength is obtained, and electrical reliability is high. Further, since the surface average roughness of the roughened surface is 0.1 μm or more, the anchor effect is sufficiently obtained, and since it is 10 μm or less, there is little influence on the smoothness of the film formed on the surface. .

  According to the method of manufacturing a piezoelectric vibrator of the present invention, a vibrator substrate provided with a vibrating piece, a base substrate that supports the vibrator substrate, and a lid substrate stacked on the vibrator substrate are joined, and the vibrator A first vibration electrode formed on a surface of the substrate facing the lid substrate; a second vibration electrode formed on a surface of the vibrator substrate facing the base substrate; and the base of the vibrator substrate. A surface facing the substrate is provided on the outer periphery of the base substrate and a third vibration electrode electrically connected to the first vibration electrode by a recess formed on a side surface of the vibrator substrate. A method of manufacturing a piezoelectric vibrator comprising a connection electrode electrically connected via an external electrode formed in a notch, wherein the vibrator base includes a plurality of the vibration pieces and the first vibration. Electrically connecting the electrode and the third vibrating electrode Forming the recess hole for forming, and providing the base substrate with a notch hole for electrically connecting the second vibration electrode and the third vibration electrode to the connection electrode A bonding step of bonding the lid substrate, the vibrator substrate, and the base substrate; and after the bonding step, the second surface at a position corresponding to the non-bonded surface of the base substrate and the notch hole. A roughening step of roughening the surface of the vibration electrode and the third vibration electrode, and a side surface of the notch hole, and after the roughening step, the connection electrode on the bottom surface of the base substrate, Forming an external electrode on the second vibration electrode, the third vibration electrode, and a side surface of the notch hole to form an assembly of the piezoelectric vibrators; and The recess hole and the notch hole Tracing and cutting the formed outs recess and the cutting, characterized in that it comprises a step of separating the piezoelectric vibrator.

  According to the present invention, since the surface on which the external electrode and the connection electrode are formed is roughened, the adhesion of these electrodes can be obtained by the anchor effect. Therefore, even when a force is applied to these electrodes in the step of separating the piezoelectric vibrator from the aggregate of piezoelectric vibrators, the piezoelectric vibrator is obtained with little peeling and high electrical reliability.

In the present invention, it is preferable that the surface average roughness Ra of the surface on which the external electrode and the connection electrode to be roughened in the roughening step are 0.1 μm to 10 μm.
In this invention, since the surface average roughness is 0.1 μm or more, the anchor effect is sufficiently obtained, and since it is 10 μm or less, the influence on the smoothness of the film formed on the surface is small.

In the present invention, the roughening method is preferably roughening by sandblasting.
In this invention, the surface average roughness is easily controlled by selecting the particle size of the abrasive particles used.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
FIG. 1 shows a piezoelectric vibrator 1 according to an embodiment of the present invention.
1A is a perspective view of the piezoelectric vibrator 1, FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. 1C is a bottom view.
FIG. 2 is an exploded perspective view of the piezoelectric vibrator 1. The piezoelectric vibrator 1 includes a lid substrate 2, a vibrator substrate 3, and a base substrate 4.
3A is a plan view of the transducer substrate 3 viewed from the lid substrate 2 side, and FIG. 3B is a plan view of the transducer substrate 3 viewed from the base substrate 4 side.

1A and 2, the piezoelectric vibrator 1 is configured by sequentially stacking a lid substrate 2 on a vibrator substrate 3 supported by a base substrate 4. The vibrator substrate 3 is sandwiched and bonded between the lid substrate 2 and the base substrate 4.
1 (a) and 1 (c), the base substrate 4 is a substantially rectangular plate, and its outer periphery (FIGS. 1 (a) and 1 (c) shows an example of four corners where the side surfaces intersect). Is provided with external electrodes 41 and 42 on the side surfaces of the notch. A connection electrode 43 that is electrically connected to the external electrode 41 and a connection electrode 44 that is electrically connected to the external electrode 42 are formed on the bottom surface of the base substrate 4.
The vibrator substrate 3 is a plate having substantially the same outer shape as the base substrate 4. One of the side surfaces is provided with two recesses 35.
The lid substrate 2 is also a plate having substantially the same outer shape as the base substrate 4. The side surface of the lid substrate 2 is not processed.

In FIG. 1B and FIG. 2, the vibrator substrate 3 includes a frame portion 30 and a vibrating piece 33 surrounded by the frame portion 30. The vibrator substrate 3 is made of quartz, and the vibration piece 33 has a rectangular parallelepiped shape with a main surface being square. Here, the main surface is a surface orthogonal to the Y axis, which is the crystal axis of quartz, and the side surface of the vibrator substrate 3 is formed to be approximately orthogonal to the X axis and the Z axis (see FIG. 2). .
The vibration piece 33 is formed thinner than the thickness of the vibrator substrate 3 and is supported by two opposing support portions 34 extending from the Z-axis direction of the frame portion 30. Therefore, the vibrating piece 33 is sealed in a space sandwiched between the lid substrate 2 and the base substrate 4 (see FIG. 1B).
The two concave portions 35 are formed on the side surface of the vibrator substrate 3 made of crystal indicated by the arrow in FIG.

3A and 3B, the portions of the first vibrating electrode 31, the second vibrating electrode 32, and the third vibrating electrode 36 formed on the vibrator substrate 3 are indicated by hatching.
In FIG. 3A, the first vibrating electrode 31 is provided on the surface of the vibrator substrate 3 that faces the lid substrate 2. More specifically, the vibration piece 33, the two support portions 34, and the frame portion 30 are continuously provided on the surface facing the lid substrate 2. The vibration electrode 31 is also provided on the side surface of the recess 35.
In FIG. 3B, the second vibrating electrode 32 is provided on the surface of the vibrator substrate 3 that faces the base substrate 4. More specifically, the vibration piece 33, the two support portions 34, and the frame portion 30 are provided on the surface facing the base substrate 4. Here, the vibrating electrode 32 is not provided up to the vicinity of the recess 35. A third vibrating electrode 36 is provided on the surface in the vicinity of the recess 35 in a state where it is electrically cut across a surface 37 on which no electrode is provided. The vibrating electrode 36 is also provided on the side surface of the recess 35.

  The first vibrating electrode 31 and the third vibrating electrode 36 provided on the side surface of the recess 35 are electrically connected at the side surface. Accordingly, the first vibration electrode 31 formed on the surface of the vibrator substrate 3 facing the lid substrate 2 is drawn out to the surface of the vibrator substrate 3 facing the base substrate 4, and the first vibration electrode 31 and the first vibration electrode 31 are formed. The second vibrating electrode 32 is electrically cut by a surface 37.

  In a state where the vibrator substrate 3 and the base substrate 4 are bonded, the third vibrating electrode 36 is connected to the external electrode 41, and the second vibrating electrode 32 is connected to the external electrode 42. Therefore, the first vibration electrode 31 and the second vibration electrode 32 formed on both main surfaces of the vibration piece 33 are connected to the connection electrodes 43, formed on the bottom surface of the base substrate 4 via the external electrodes 41, 42. 44 can be connected to a mounting board or the like.

Below, the manufacturing method of the piezoelectric vibrator 1 is demonstrated based on drawing.
FIG. 4 is a schematic view showing a manufacturing process. The piezoelectric vibrator 1 can be obtained by forming a large number of substrates using a substrate which is a large substrate and then separating them individually.
FIG. 4A shows a process of preparing a lid substrate 200, a vibrator substrate 300, and a base substrate 400, which are large substrates.
FIG. 4B shows a step of forming the vibrator substrate 310 by forming a plurality of vibrating pieces 33 and the like, and a recess hole 305 in which a part thereof later becomes the recess 35 by the photolithography process. A process of forming a notch hole 420 to be a notch in which the external electrode 41 will be formed later on the base substrate 400 to form the base substrate 410 is shown.
FIG. 4C shows a first vibration electrode 321 (vibration electrode 31) indicated by a large number of dots in the drawing on one side of the vibrator substrate 310, and a second vibration electrode 32 (not shown) on the other side. ) And a third vibrating electrode 36 (not shown) to form the vibrator substrate 320.
FIG. 4D shows a process of bonding the lid base 200, the vibrator base 320, and the base base 410.
FIG. 4E shows the assembly 100 of the piezoelectric vibrator 1 after bonding.
FIG. 4F shows a process of obtaining the piezoelectric vibrator 1 by separating the aggregate 100 of the piezoelectric vibrators 1 into individual piezoelectric vibrators 1.

In FIG. 4A, a glass substrate or a quartz substrate can be used for the lid substrate 200 and the base substrate 400. As the vibrator substrate 300, a quartz substrate is used. The vibrator substrate 300 is obtained by forming a main surface orthogonal to the Y axis, which is the crystal axis of quartz, and a side surface orthogonal to the X axis and the Z axis.
In FIG. 4B, the mask 30 is masked on the frame portion 30, the vibrating piece 33, and the support portion 34 (see FIG. 2) on both surfaces of the vibrator base 300, and wet etching is performed. And a support portion 34 (not shown). Further, two recess holes 305 are formed by wet etching at a position near the positive direction side of the X axis of the vibrating piece 33. By performing wet etching from both main surfaces, a recess hole 305 having a small opening diameter can be obtained. The side surface of the recess hole 305 has a tapered shape that narrows from the opening toward the back due to anisotropy with respect to the crystal axis. The wet etching is performed using hydrofluoric acid or the like.
In the base substrate 400, a notch hole 420 to be a notch in which the external electrodes 41 and 42 are formed is formed by wet etching to form the base substrate 410.
In FIG. 4C, the first vibration electrode 321 (vibration electrode 31), the second vibration electrode 32, and the third vibration electrode 36 can be formed by vapor deposition, sputtering, or the like. Here, since the side surface of the recess hole 305 has a tapered shape that narrows from the opening toward the back, an electrode is also formed on the side surface of the recess hole 305, and vapor deposition, sputtering, etc. are performed from both main surface sides. By doing so, electrical connection between the first vibrating electrode 31 and the third vibrating electrode 36 is performed on the side surface of the recess hole 305.
These vibrating electrodes can be formed of a laminated film of a chromium film and a gold film.

  In FIG. 4D, eutectic gold bonding such as gold tin, anodic bonding, or plasma bonding can be used for bonding the lid base 200, the vibrator base 320, and the base base 410.

In FIG. 4E, external electrodes 41 and 42 and connection electrodes 43 and 44 are simultaneously formed on the bottom surface 411 of the base substrate 410 and the side surfaces of the notch holes 420 by vapor deposition, sputtering, or the like.
Hereinafter, a method of forming the external electrodes 41 and 42 and the connection electrodes 43 and 44 will be described in detail with reference to FIG. The external electrodes 41 and 42 and the connection electrodes 43 and 44 are formed by a plating method.
FIG. 5 shows in detail the method of forming the external electrodes 41 and 42 and the connection electrodes 43 and 44 by enlarging the vicinity of the notch hole 420.
FIG. 5A shows a state before the external electrodes 41 and 42 and the connection electrodes 43 and 44 are formed. FIG. 5B shows a state in which the surfaces on which the external electrodes 41 and 42 and the connection electrodes 43 and 44 are formed are roughened. FIG. 5C shows a state where a base electrode 450 for plating is formed. FIG. 5D shows a state after the plating process.

  In FIG. 5A, the lid base 200, the vibrator base 320, and the base base 410 are joined. In anodic bonding and plasma bonding, smoothness is required for the bonding surfaces in order to improve the adhesion. These substrates are polished smoothly on both sides. A first vibrating electrode 321 and a third vibrating electrode 322 are formed on the polished surface 415 of the vibrator substrate 320. Therefore, the surface 416 of the vibrating electrode 322 formed by vapor deposition and sputtering is also a smooth surface like the surface 415. The side surface 421 of the notch hole 420 is formed by wet etching. The bottom surface 411 of the base substrate 410 is also a polished smooth surface.

  In FIG. 5B, the bottom surface 411, the surface 416, and the side surface 421 are roughened to form roughened surfaces 418, 419, and 422. The roughening can be performed using a sandblasting method or the like. The surface average roughness Ra of the roughened surface is preferably 0.1 μm to 10 μm.

  In FIG. 5C, a base electrode 450 for plating is formed by vapor deposition and sputtering. The base electrode 450 can be formed of a laminated film of a chromium film and a gold film.

  In FIG. 5D, a nickel / gold plating film 460 is formed on the base electrode 450 to form external electrodes 41 and 42 and connection electrodes 43 and 44.

  In FIG. 4F, the piezoelectric vibrator 1 is obtained by separating the aggregate 100 of the piezoelectric vibrators 1 into individual piezoelectric vibrators 1.

6 and 7 are detailed views showing the process of separating the piezoelectric vibrator 1.
6A is a partial plan view of the aggregate 100 of the piezoelectric vibrator 1, and FIG. 6B is a cross-sectional view taken along the line BB.
FIG. 7 is a partial enlarged cross-sectional view of FIG.

  6A, 6 </ b> B, and 7, a portion indicated by a two-dot chain line is cut by the blade 600 so as to cross the recess hole 305 and the notch hole 420. Here, the shape of the side surface of the recess hole 305 is not symmetric due to the anisotropy of quartz wet etching. The side surface etched in the positive direction of the X axis has a gentle slope, and the side surface in the negative direction of the X axis has a steep slope.

In FIG. 7, the cutting position by the blade 600 will be described in detail. The blade 600 is positioned at the center of the notch hole 420, and the width of the blade 600 is set to be narrower than the width of the bottom surface 425 of the hole formed by the notch hole 420.
After the piezoelectric vibrator 1 is separated, the base electrode 450 and the nickel / gold plating film 460 become the external electrodes 41 and 42 and the connection electrodes 43 and 44, respectively.
Through the above steps, the piezoelectric vibrator 1 can be obtained.

Hereinafter, effects of the embodiment will be described.
(1) Since the surfaces on which the external electrodes 41 and 42 and the connection electrodes 43 and 44 are formed are roughened, adhesion can be obtained by the anchor effect. Therefore, even when the piezoelectric vibrator 1 is mounted on the mounting substrate via the connection electrodes 43 and 44, peeling can be hardly caused, mounting strength can be obtained, and electrical reliability can be increased.

  (2) Since the surfaces on which the external electrodes 41 and 42 and the connection electrodes 43 and 44 are formed are roughened, the adhesion of these electrodes can be obtained by the anchor effect. Therefore, even when a force is applied to these electrodes in the process of separating the piezoelectric vibrator 1 from the aggregate of the piezoelectric vibrators 1, the piezoelectric vibrator with high electrical reliability can be obtained with little peeling.

  (3) Since the surface average roughness Ra is 0.1 μm or more, the anchor effect can be sufficiently obtained, and since it is 10 μm or less, the influence on the smoothness of the film formed on the surface can be reduced.

  (4) The surface average roughness Ra can be easily controlled by selecting the particle size of the abrasive particles to be used.

  It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

(A) is a perspective view of the piezoelectric vibrator in the embodiment of the present invention, (b) is a cross-sectional view taken along line AA in (a), and (c) is a bottom view. The exploded perspective view of a piezoelectric vibrator. FIG. 5A is a plan view of the transducer substrate viewed from the lid substrate side, and FIG. 5B is a plan view of the transducer substrate viewed from the base substrate side. Schematic which showed the manufacturing process in embodiment of this invention. The expanded sectional view which shows the formation method of an external electrode and a connection electrode. (A) is a fragmentary top view of the aggregate | assembly in embodiment of this invention, (b) is BB sectional drawing in (a). The partial expanded sectional view in FIG.6 (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator, 2 ... Lid board | substrate, 3 ... Vibrator board | substrate, 4 ... Base board | substrate, 31 ... 1st vibration electrode, 32 ... 2nd vibration electrode, 35 ... Recessed part, 36 ... 3rd vibration electrode, 43, 44 ... connection electrode, 41, 42 ... external electrode, 418, 419, 422 ... surface on which the connection electrode is formed, 33 ... vibrating piece, 300 ... vibrator base, 305 ... hole for recess, 420 ... notch Holes for use 200... Lid substrate, 400. Base substrate, 421.

Claims (3)

A plurality of vibration pieces, a first vibration electrode on one main surface side with respect to each of the vibration pieces, a second vibration electrode and a third on the other main surface which is the back surface side with respect to one main surface A recess hole having a vibration electrode and a wiring penetrating between the one main surface side and the other main surface side and electrically connecting the first vibration electrode and the third vibration electrode Preparing a vibrator substrate comprising:
Preparing a base substrate in which a plurality of notch holes are formed by wet etching;
The other main surface of the front SL cutting the through-outs hole second vibrating electrode the third so that the vibrating electrode is exposed, and the plurality of the resonator element overlaps way the vibrator base The lid base is placed so that one main surface of the base base is directed to the side, and further, the lid base is placed on the one main surface of the vibrator base so as to overlap the plurality of vibrating pieces, and the lid base and the vibrator A bonding step of bonding the base body and the base base body;
After the bonding step, the base back surface side other main surface of said one main surface of the substrate, said cutting said exposed from lack hole second vibrating electrode and said surface of the third vibration electrode, and A roughening step of roughening the inner wall surface of the notch hole;
Wherein after the roughening step, the base substrate to form the connection electrode roughened other main surface, roughness of the second said the roughened surface of the vibrating electrode of the third vibration electrode forming an assembly of the piezoelectric vibrator and the inner wall surface of the roughened surface and roughened the notch hole to form the external electrodes,
It comprises a sequence of the piezoelectric vibrator plurality of said recesses hole the collection of, was cut by tracing the sequence of a plurality of the notch hole, the recess and the outer electrode has the wiring on the side surface and a step of separating the pressure electrostatic vibrator are, a,
A method of manufacturing a piezoelectric vibrator. In the manufacturing method of the piezoelectric vibrator according to claim 1 ,
The piezoelectric vibrator, wherein the average surface roughness Ra of the front by the roughening process Kigaibu electrode and the connection electrode is roughened is made form surface is 0.1μm~10μm Production method. In the manufacturing method of the piezoelectric vibrator according to claim 1 or 2 ,
The method of manufacturing a piezoelectric vibrator, wherein the roughening method is roughening by sandblasting.

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