JP4064420B2 - Manufacturing method of crystal unit - Google Patents

Description

  The present invention relates to a manufacturing method of a bonded crystal unit for high frequency use, and more particularly to a manufacturing method of a crystal unit in which bonding is performed directly.

BACKGROUND OF THE INVENTION Quartz resonators are often used in various electronic devices including communication devices as oscillators and filter elements as frequency and time reference sources. In recent years, with the increase in communication frequency and the like, the thickness of a commonly used AT-cut crystal resonator (crystal piece) is processed to be small. Note that the vibration frequency of the crystal resonator is inversely proportional to the thickness of the crystal piece that is AT-cut. The smaller the thickness, the higher the vibration frequency. One of these is the one in which a reinforcing plate is provided to increase the strength.

(Description of Prior Art) FIGS. 7 and 8 are diagrams for explaining a conventional example (see Patent Document 1), FIG. 7 is an exploded view of a crystal resonator, and FIG. 8 is a sectional view.
The quartz crystal unit is formed by adhering a quartz crystal piece 1 and a reinforcing plate 2 each having an AT cut. The quartz crystal piece 1 for a vibrator has an excitation electrode 3 and an extraction electrode 4 extending therefrom on one main surface. The reinforcing plate 2 is formed by integrating a body 6 having a through-hole 5 and an excitation electrode plate 7 having an excitation electrode 3 and an extraction electrode 4 on one main surface facing the through-hole 5. In short, the other main surface side of the crystal piece 1 for vibrator is an excitation mode in which an air gap method (space electric field method) is used.

  Specifically, the reinforcing plate 2 is first formed. Next, the opening side of the reinforcing plate 2 is bonded to the other main surface of the crystal piece 1 for vibrator. And after sticking, both main surfaces are grind | polished and the quartz crystal piece 1 for vibrator | oscillators is set to prescribed thickness. Finally, the excitation electrode 3 and the extraction electrode 4 are extended on one main surface of the crystal piece 1 for vibrator.

In such a case, since the vibrator crystal piece 1 is polished by being integrated with the reinforcing plate 2, it is easier to handle and prevents breakage during operation as compared with the case where the vibrator crystal piece 1 is used alone. . For example, when the vibration frequency is 100 MHz, the thickness of the crystal piece 1 for vibrator becomes about 17 μm, and the effect becomes larger as the frequency becomes higher.
JP-A-3-139912 JP 49-90497 JP 2000-269106 A JP 2000-228618 A

(Problems of the prior art) However, since the crystal resonator having the above-mentioned structure basically has a three-layer structure by sticking using an adhesive or the like, there is a problem that the bonding strength is low and the manufacturing is complicated. .

  Further, in Patent Document 2, both main surfaces are polished after depositing a metal or non-metallic material on the crystal piece 1 for vibrator by plating or vapor deposition, and then the central portion is removed by etching to remove the reinforcing layer 8 on the outer periphery. (FIG. 9). However, in this case, since the reinforcing layer 8 is provided by plating, vapor deposition, or the like, there is a problem that the bonding strength is further reduced. If the bonding strength is low, for example, when the thickness is reduced by polishing, the operation becomes difficult.

  In addition, there is a quartz plate formed by etching the central portion from one main surface or both main surfaces of the quartz plate (not shown), but in such a case, the flatness and parallelism of the vibration region are impaired. There was a problem.

(Object of the Invention) An object of the present invention is to provide a method for manufacturing a crystal resonator which is easy to manufacture by increasing the bonding strength.

The present invention relates to a method of manufacturing a crystal unit comprising an AT-cut crystal unit for a crystal unit and a reinforcing plate provided with a through-hole formed by etching, as indicated in the claims (Claim 1). Both main surfaces facing the through-holes of the vibratory crystal wafer by directly bonding a crystal wafer for vibrators made of AT cut and a reinforcing crystal wafer having a plurality of through-holes formed by etching And forming an extraction electrode connected to the excitation electrode on the quartz crystal wafer for reinforcement and the quartz crystal wafer for reinforcement, and then the individual crystal oscillations in which the quartz crystal piece for the vibrator and the reinforcement plate are joined. dividing the child, is formed on the inclined surface extraction electrode is obliquely intersect the axis Z 'of the reinforcing crystal wafer produced by anisotropic etching in forming the through hole of the reinforcing crystal wafer , Wherein Z 'axis is a manufacturing method which is the length direction of the crystal oscillator.

  With such a configuration (manufacturing method), the crystal wafer for vibrator and the reinforcing wafer are directly bonded, so that the bonding strength is basically increased by interatomic bonding. Further, the reinforcing wafer is provided with a through hole in advance, and the crystal wafer for vibrator is directly bonded. Therefore, for example, after bonding a crystal wafer for a vibrator and a reinforcing wafer and then forming a through hole in the reinforcing wafer, bubbles generated at the interface between the two can easily escape and increase the bonding strength to facilitate manufacture. To do.

The reinforcing wafer is an AT-cut reinforcing crystal wafer, and the lead-out electrode of the reinforcing crystal wafer obliquely intersects the Z ′ axis of the reinforcing crystal wafer generated by etching when the through hole is formed. Formed on the inclined surface (so-called etching anisotropy). Thereby, disconnection can be prevented compared with the case where the extraction electrode is formed on a steep slope. And since the position of the inclined surface in the wafer state is formed in the same direction, for example, as compared with the case where the extraction electrode is formed after the division, an operation such as positioning is not required and the electrode formation is facilitated.

(First embodiment)
FIG. 1 is a diagram for explaining a method for manufacturing a crystal resonator according to a first embodiment of the present invention. In addition, the same number is attached | subjected to the same part as a prior art example figure, and the description is abbreviate | omitted or abbreviate | omitted.

  The quartz crystal resonator is, for example, rectangular, and includes the quartz crystal piece 1 and the reinforcing plate 2 as described above. In this example, the vibrator crystal piece 1 and the reinforcing plate 2 are both AT cuts. As shown in FIG. 2, the AT cut has a main surface (YZ plane) of 35 degrees 15 minutes from the Z axis to the Y axis centering on the X axis with respect to the Y axis of the crystal axis (XYZ) (that is, The cutting angle at which the normal to the main surface is inclined from the Y axis to the Z axis direction by 35 degrees 15 minutes). The new tilted axes are defined as the Y ′ axis and the Z ′ axis.

  Specifically, first, the quartz crystal wafer 1A for vibrator and the quartz crystal wafer 2A for reinforcement, both of which are AT-cut, are directly bonded (see FIG. 3). Here, a plurality of through holes 5 are previously formed in the reinforcing crystal wafer 2A by etching with hydrofluoric acid or the like. In this case, the reinforcing crystal wafer 2A exposes only the region to be the through hole 5 on one main surface side and masks the other.

  In direct bonding, the quartz crystal wafer 1A for vibrator and the quartz crystal wafer 2A for reinforcement are mirror-polished to make them hydrophilic (OH base). Then, the main surfaces are brought into contact with each other and heat-treated to remove H 2 O to form Si—O—Si bonds. Alternatively, one is hydrophilized (OH grouped) and the other is hydrophobized (H grouped) and heat-treated to form a Si—Si bond (see FIG. 4 (ab), Patent Document 3).

  Next, both main surfaces are polished to reduce the thickness of the crystal wafer 1A for vibrators. Alternatively, the vibratory crystal wafer 1A processed within a specified thickness by mirror polishing is controlled by etching. Then, a plurality of excitation electrodes 3 and extraction electrodes 4 are formed on both main surfaces of the crystal wafer 1A for vibrator by vapor deposition or the like. However, the extraction electrode 4 on the through-hole 5 side is also formed on the reinforcing crystal wafer 2A. Then, the crystal unit 1 and the reinforcing plate 2 having the through holes 5 are individually divided into crystal units.

  In such a case, since the vibratory crystal wafer 1A and the reinforcing crystal wafer 2A are directly connected to each other, it becomes an atomic bond and the bonding strength is increased. Therefore, handling is facilitated and, for example, when the thickness is reduced by polishing after joining, the operation is facilitated. Since the vibrator crystal piece 1 and the reinforcing plate 2 are two layers, the manufacturing is simplified.

  Further, since the reinforcing crystal wafer 2A is etched from one main surface side as an AT cut to form the through-hole 5, the Z′-axis, for example, the length direction is set by the etching rate, that is, the Z-axis >> X-axis> Y-axis. An inclined surface 9 with a surface exposed is formed on one of the inner side surfaces in the direction. The inner surface in the width direction (X-axis direction) is a steep slope. From this, by extending the extraction electrode 4 to the inclined surface 9 that is one of the inner side surfaces in the Z′-axis direction, for example, disconnection during vapor deposition can be prevented (see FIGS. 1 and 6; Patent Document 4). reference).

  Further, the reinforcing crystal wafer 2A is provided with a through-hole 5 in advance to directly bond the vibrator crystal wafer 1A. Therefore, for example, after bonding the crystal wafer for vibration 1A and the crystal wafer for reinforcement 2A and then forming a through hole in the crystal wafer for reinforcement 2A, bubbles generated at the interface between them are easily escaped and the bonding strength is increased. It is done.

  In this case, the excitation electrode 3 and the extraction electrode 4 are formed particularly when the crystal crystal wafer 1A for vibrator and the crystal wafer 2A for reinforcement are directly bonded. Since the position of the surface 9 is in a fixed direction, it is easy to manufacture without requiring alignment or the like.

(Second embodiment , reference )
FIG. 6 is a cross-sectional view of a crystal resonator illustrating a second embodiment of the present invention. In addition, description of the same part as the previous embodiment is omitted or simplified.

  As described above, the quartz crystal resonator is composed of the quartz crystal piece 1 and the reinforcing plate 2 that are AT-cut. Here, the reinforcing plate 2 is a glass plate. Then, the vibratory crystal wafer 1A and the reinforcing glass wafer are directly joined to form the excitation electrode 3 and the extraction electrode 4, and then divided into individual crystal vibrators (previous FIG. 3). However, as described above, only the region to be the through-hole 5 on the one main surface side is exposed and masked on the reinforcing glass wafer.

  In such a thing, since only the area | region used as the through-hole 5 is exposed and etched in the glass wafer for reinforcement, an isotropic inclined surface is obtained toward the other main surface from one main surface side. Therefore, it is easy to lead out the extraction electrode 4 not only from one direction as in the first embodiment but from any position regardless of the directionality, and disconnection can be prevented. Further, since the reinforcing glass wafer is provided with the through holes 5 in advance to directly bond the crystal wafer for vibrators, bubbles generated at the interface between the two easily escape from the through holes, and the bonding strength is increased. In each of the above embodiments, the crystal resonator and the through hole 5 are rectangular, but may be, for example, a disk.

It is sectional drawing of the crystal oscillator explaining 1st Embodiment of this invention. It is a cutting direction figure of an AT cut quartz plate explaining a 1st embodiment of the present invention. FIG. 3 is a bonding diagram of a vibratory crystal wafer and a reinforcing crystal wafer for explaining the first embodiment of the present invention. It is a schematic diagram of the direct joining explaining 1st Embodiment of this invention. It is a figure of the reinforcement board explaining 1st Embodiment of this invention. It is sectional drawing of the crystal oscillator explaining 2nd Embodiment of this invention. It is an exploded view of a crystal resonator explaining a conventional example. It is sectional drawing of the crystal oscillator explaining a prior art example. It is sectional drawing of the crystal piece for vibrator | oscillators which demonstrates a prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Crystal piece for vibrators, 2 Reinforcement plate, 3 Excitation electrode, 4 Extraction electrode, 5 Through-hole, 6 Reinforcement plate main body, 7 Excitation electrode plate, 8 Reinforcement layer, 9 Inclined surface.

Claims (1)

In a crystal resonator manufacturing method in which an AT-cut crystal piece for crystal and a reinforcing plate provided with a through-hole by etching are joined, the crystal wafer for crystal made of AT-cut and a plurality of through-holes are etched a reinforcing crystal wafer which is provided joined directly by the vibrator crystal wafer and said reinforcing crystal wafer so as to form the excitation electrodes on both principal surfaces of the through hole facing the vibrator crystal wafer After forming an extraction electrode to be connected to the excitation electrode, the crystal unit for crystal and the reinforcing plate are divided into individual crystal units bonded to each other, and the extraction electrode of the reinforcing crystal wafer forms the through hole. 'formed on the inclined surface obliquely intersect the axis, the Z' wherein Z of reinforcing crystal wafer produced by anisotropic etching when the shaft is the length direction of the crystal oscillator The method for manufacturing a quartz oscillator and butterflies.

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