JP5504927B2 - Piezoelectric vibrating piece, piezoelectric vibrating device, and method of manufacturing piezoelectric vibrating device - Google Patents

Description

  The present invention relates to a piezoelectric vibrating piece made of a piezoelectric material, a piezoelectric vibrating device on which the piezoelectric vibrating piece is mounted, and a method for manufacturing the piezoelectric vibrating device.

  Currently, examples of piezoelectric vibrating devices include tuning fork type crystal resonators (hereinafter referred to as crystal resonators). In this type of piezoelectric vibration device, a package which is a casing is composed of a base and a lid, and the inside of the casing is hermetically sealed. Further, inside the housing, a piezoelectric vibrating piece (quartz crystal vibrating piece) is bonded to an electrode pad on the base via a conductive adhesive or a conductive bump.

  In this quartz crystal resonator element, the substrate is composed of a base portion and two leg portions protruding from the base portion, and excitation electrodes configured with different potentials are formed on the leg portions. In addition, an extraction electrode for electrically connecting the excitation electrode to the electrode pad is formed on the base (see, for example, Patent Document 1).

  In the above-mentioned Patent Document 1, the extraction electrode of the crystal vibrating piece and the electrode pad of the base are ultrasonically bonded by the FCB method through the plating bump, and the crystal vibrating piece is mounted on the base and then mounted on the base. After performing the final frequency adjustment to finely adjust the frequency of the crystal vibrating piece, the lid was joined to the base via a sealing material by a technique such as heat fusion bonding, and the crystal vibrating piece was composed of the base and the lid A method of manufacturing a crystal resonator that is hermetically sealed in an internal space is disclosed.

  In such a crystal resonator manufacturing process, the crystal resonator element is subjected to an annealing process before final frequency adjustment. In addition, after the final frequency adjustment, a manufacturing process such as a sealing process, a reflow process, and an aging process is performed on the crystal vibrating piece mounted on the base. In such a manufacturing process after the final frequency adjustment, a thermal history is applied to the crystal vibrating piece. That is, when manufacturing the crystal resonator, the crystal resonator element is subjected to a total of two or more heat treatments including the heat treatment by annealing.

JP 2009-284073 A

  By the way, at present, it is necessary to reduce the size of the piezoelectric vibrating piece as the piezoelectric vibrating device on which the piezoelectric vibrating piece is mounted. However, when the size of the piezoelectric vibrating piece is reduced, the series resonance resistance value (CI value) is reduced. Is disadvantageous.

  Therefore, in the above-described manufacturing process of the piezoelectric vibrating device, the CI value is reduced by performing an annealing process on the piezoelectric vibrating piece. However, as described above, after the final frequency adjustment performed after the annealing process, it is necessary to apply a thermal history to the piezoelectric vibrating piece directly or indirectly in a sealing process, a reflow process, an aging process, etc. With a good thermal history, the CI value increases significantly.

  That is, in the manufacture of the piezoelectric vibrating device, even if annealing is performed to reduce the CI value of the piezoelectric vibrating piece, the CI value has been greatly increased by further heat treatment after the annealing.

  The present invention has been made in view of such a situation, and in manufacturing a piezoelectric vibration device, the CI value decreased by the annealing treatment is suppressed from being significantly increased by the further heat treatment after the annealing treatment. Another object of the present invention is to provide a piezoelectric vibrating piece, a piezoelectric vibrating device on which the piezoelectric vibrating piece is mounted, and a method of manufacturing the piezoelectric vibrating device.

The piezoelectric vibrating piece of the present invention is a piezoelectric vibrating piece made of a piezoelectric material, and an excitation electrode is formed by a first metal bonded to the piezoelectric material and a second metal bonded to the first metal, In the excitation electrode, the second metal has higher conductivity than the first metal, and the weight ratio of the first metal to the second metal is more than 5.9% to less than 12.9%. It is characterized by being.

  According to this configuration, the weight ratio of the first metal to the second metal constituting the excitation electrode formed on the piezoelectric vibrating piece is more than 5.9% and not more than 30.3%. It is possible to reduce the degree of increase in the CI value due to further heat treatment after the annealing treatment that occurs when the piezoelectric vibration device is manufactured using the piece. That is, it is possible to suppress the CI value decreased by the annealing process from being significantly increased by the heat treatment after the annealing process. In this specification, the weight ratio (%) of the first metal to the second metal is obtained by dividing the weight of the first metal constituting the excitation electrode by the weight of the second metal constituting the excitation electrode. The numerical value converted into percentage.

  In the piezoelectric vibrating piece of the present invention, the first metal may be chromium, nickel, molybdenum, titanium, or tungsten.

  According to this configuration, sufficient bondability between the piezoelectric material and the first metal can be ensured. Moreover, film formation by vapor deposition of the first metal on the piezoelectric material can be easily performed.

  In the piezoelectric vibrating piece of the present invention, the second metal may be gold.

  According to this configuration, deterioration of the excitation electrode due to oxidation of the electrode film can be prevented. Further, the CI resistance can be lowered by lowering the conduction resistance of the second metal.

  The piezoelectric vibrating device of the present invention is a piezoelectric vibrating device on which the above-described piezoelectric vibrating piece of the present invention is mounted, and hermetically seals the piezoelectric vibrating piece and the excitation electrode of the piezoelectric vibrating piece. The first sealing member and the second sealing member are provided.

  According to this configuration, since the piezoelectric vibrating device is manufactured using the above-described piezoelectric vibrating piece of the present invention, the CI value by the further heat treatment after the annealing process that occurs when the piezoelectric vibrating device is manufactured. The degree of increase is reduced. That is, the CI value decreased by the annealing process is substantially maintained.

The method for manufacturing a piezoelectric vibrating device of the present invention is a manufacturing method for manufacturing the above-described piezoelectric vibrating device of the present invention, wherein the mounting step of mounting the piezoelectric vibrating piece on the first sealing member;
An annealing process for annealing the piezoelectric vibrating piece, a frequency adjusting process for adjusting the final frequency of the piezoelectric vibrating piece, after the mounting process and the annealing process, and before the frequency adjusting process And a pre-heat treatment step for heat-treating the piezoelectric vibrating piece, and a post-heat treatment step for heat-treating the piezoelectric vibrating piece after the frequency adjusting step.

According to such a manufacturing method, since the annealing process is provided, the CI value can be reduced by the annealing process. Since the preliminary heat treatment step is provided after the annealing treatment step and before the frequency adjustment step, it is possible to suppress the CI value from fluctuating due to the heat treatment after the final frequency adjustment. In addition, since the piezoelectric vibrating piece according to the present invention described above is used, it is possible to suppress the CI value decreased by the annealing process from being significantly increased by the further heat treatment after the annealing process.
According to another method of manufacturing a piezoelectric vibrating device of the present invention, a piezoelectric vibrating piece made of a piezoelectric material, and a first sealing member and a second sealing member for hermetically sealing an excitation electrode of the piezoelectric vibrating piece, A mounting method for mounting the piezoelectric vibrating piece on the first sealing member, an annealing process for annealing the piezoelectric vibrating piece, and the piezoelectric vibrating piece A frequency adjusting step for performing final frequency adjustment, a pre-heat treatment step for performing heat treatment on the piezoelectric vibrating piece after the mounting step and the annealing treatment step and before the frequency adjustment step, and the frequency adjustment step And a post-heat treatment step of performing a heat treatment on the piezoelectric vibrating piece, and as the piezoelectric vibrating piece, a first metal bonded to the piezoelectric material, and a second metal bonded to the first metal, By The excitation electrode is formed. In the excitation electrode, the second metal has higher conductivity than the first metal, and the weight ratio of the first metal to the second metal is 5. Using a piezoelectric vibrating piece that is more than 9% to 30.3% or less, the temperature of heat applied to the piezoelectric vibrating piece in the pre-heat treatment step is lower than the temperature of the annealing treatment step, and the post-heat treatment step The temperature is higher than the temperature applied to the piezoelectric vibrating piece.

  According to the present invention, when the piezoelectric vibration device is manufactured, it is possible to suppress the CI value decreased by the annealing process from being significantly increased by the further heat treatment after the annealing process.

FIG. 4 is a schematic side view showing the inside of a crystal resonator on which a crystal resonator element according to an embodiment of the invention is mounted. It is a top view which shows schematic structure of the quartz crystal vibrating piece which concerns on embodiment of this invention. It is a graph which shows the relationship between weight ratio (Cr / Au) and the increase rate of CI value by the pre-heat processing after annealing. It is a graph which shows the relationship between weight ratio (Cr / Au) and the decreasing rate of CI value by annealing treatment. It is a graph which shows the relationship between a weight ratio (Cr / Au) and the fluctuation rate of CI value by a sealing process. It is a top view which shows schematic structure of the quartz crystal vibrating piece which concerns on other embodiment of this invention. FIG. 7 is a diagram illustrating a schematic configuration of a crystal resonator on which the crystal resonator element illustrated in FIG. 6 is mounted, and is a cross-sectional view illustrating a state in which the crystal resonator element is cut along line AA in FIG. 6.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiment described below, a case where the present invention is applied to a crystal vibrating piece as a piezoelectric vibrating piece is shown. However, this is a preferred example, and the piezoelectric vibrating piece of the present invention is not limited to the quartz vibrating piece, and may be a piezoelectric vibrating piece using a piezoelectric material.

  FIG. 1 is a schematic side view showing the inside of a crystal resonator on which a crystal resonator element according to an embodiment of the present invention is mounted, and FIG. 2 is an outline of the crystal resonator element according to the embodiment of the present invention. It is a top view which shows a structure.

  As shown in FIGS. 1 and 2, the crystal resonator 1 according to the present embodiment (which is a piezoelectric resonator device according to the present invention, and hereinafter referred to as a crystal resonator) includes first and second electrodes each having a different potential. A quartz crystal vibrating piece on which a second excitation electrode (the first excitation electrode is denoted by 26 and the second excitation electrode is denoted by 27. If there is no need to distinguish between the two, the quartz oscillation piece is formed). 2 (piezoelectric vibrating piece according to the present invention), a base 3 (first sealing member according to the present invention) on which the crystal vibrating piece 2 is mounted, and excitation electrodes 26 and 27 of the crystal vibrating piece 2 mounted on the base 3 And a lid 4 (second sealing member referred to in the present invention) for hermetic sealing.

  In this crystal unit 1, a base 3 and a lid 4 are joined to constitute a main body casing. The base 3 and the lid 4 are joined together via a sealing material 33, and the interior space 11 of the main body housing is formed by this joining. The crystal vibrating piece 2 is held and bonded to the base 3 in the internal space 11 of the main body casing via the metal bumps 5 and the internal space 11 of the main body casing is hermetically sealed. In addition, the metal bump 5 referred to in this specification includes plated bumps and the like that are plated in addition to stud bumps made from wires.

  As shown in FIG. 1, the base 3 is formed in a box-like body including a bottom portion 31 and a wall portion 32 extending upward from the bottom portion 31. The base 3 is formed into a concave shape by laminating a rectangular parallelepiped plate having a hollow shape made of a ceramic material on a single plate having a rectangular shape in a plan view made of a ceramic material and firing it integrally. The wall portion 32 is formed along the outer periphery of the bottom portion 31 in plan view. The upper surface of the wall portion 32 is a bonding region with the lid 4, and a metallized layer (for example, on the tungsten metallized layer) constituting a part of the sealing material 33 for bonding with the lid 4 is formed in this bonding region. A structure in which nickel and gold are plated in this order, or a structure composed of tin and gold and tin and silver). A glass layer may be provided instead of the metallized layer. The base 3 is formed with a plurality of electrode pads (not shown) that are electrically joined to the excitation electrodes 26 and 27 of the crystal vibrating piece 2. These electrode pads are respectively electrically joined to terminal electrodes (not shown) formed on the outer peripheral back surface of the base 3. These terminal electrodes are connected to external parts and external devices. These terminal electrodes and electrode pads are formed by printing integrally with the base 3 after printing a metallized material such as tungsten or molybdenum. Some of these terminal electrodes and electrode pads are formed by forming nickel plating on the metallized upper portion and forming gold plating on the upper portion thereof.

  The lid 4 is made of a metal material and formed into a single plate having a rectangular shape in plan view. A part of the sealing material 33 is formed on the lower surface of the lid 4. The lid 4 is joined to the base 3 through the sealing material 33 by a technique such as seam welding, beam welding, and heat fusion joining, and the body housing of the crystal unit 1 is configured by the lid 4 and the base 3. The

  In the present embodiment, a ceramic material is used as the material of the base 3. However, the base 3 is not limited to the one configured using the ceramic material, and for example, a material such as quartz or glass. It may be configured using. In the present embodiment, a metal material is used as the material of the lid 4, but the lid 4 is not limited to a material made of a metal material, and is made of, for example, a ceramic material or a glass material. May be.

  Next, a specific configuration of the crystal resonator element according to the embodiment of the invention will be described.

  As shown in FIG. 2, the piezoelectric vibrating piece according to the present embodiment is a tuning-fork type quartz vibrating piece 2 formed by photolithography. Specifically, the crystal vibrating piece 2 is a crystal Z plate formed by wet etching from a crystal element plate (not shown) that is a crystal piece of anisotropic material.

  As shown in FIG. 2, the substrate 20 of the quartz crystal resonator element 2 includes two legs 21 and 22 and a base 23, and the two legs 21 and 22 are formed so as to protrude from the base 23. Has been. Further, groove portions 25 are formed on both main surfaces of the two leg portions 21 and 22 in order to improve the CI value.

  The leg portions 21 and 22 are electrically connected to first and second excitation electrodes 26 and 27 configured at different potentials, and the excitation electrodes 26 and 27 to an electrode pad (not shown) of the base 3. For this purpose, an extraction electrode 28 is formed, and the extraction electrode 28 is extracted from the excitation electrodes 26 and 27 to the base 23.

  The first excitation electrode 26 is formed on both main surfaces of one leg portion 21 and both side surfaces of the other leg portion 22. Similarly, the second excitation electrode 27 is formed on both main surfaces of the other leg portion 22 and both side surfaces of the one leg portion 21.

  These excitation electrodes 26 and 27 are thin films formed of a first metal and a second metal. More specifically, the excitation electrodes 26 and 27 are formed of a first metal on both main surfaces and both side surfaces of the legs 21 and 22. A thin film is formed by forming a base electrode layer and forming an upper electrode layer made of a second metal on the base electrode layer. This thin film is formed on the entire surface by a technique such as vacuum deposition or sputtering, and then formed into a desired shape by metal etching by photolithography.

  Here, as the first metal, a metal having good bondability to quartz (a piezoelectric material referred to in the present invention) is used. Preferable specific examples of the first metal include chromium, nickel, molybdenum, titanium, and tungsten. According to these first metals, it is easy to form a film by vapor deposition of the first metal on quartz. Can be done.

  As the second metal, a metal that has good bondability to the first metal and higher conductivity than the first metal is used. Further, as the second metal, a metal that is difficult to oxidize is preferably used, and gold can be given as a specific example. When gold is used as the second metal, the conduction resistance of the second metal can be lowered and the CI value can be lowered.

  The weight ratio of the first metal to the second metal constituting the excitation electrodes 26 and 27 is in the range of more than 5.9% to 30.3%. In the case where the weight ratio of the first metal to the second metal is 5.9% or less, even if the CI value is reduced by applying annealing treatment to the quartz crystal vibrating piece 2, the CI is reduced by further heat treatment after the annealing treatment. The value may increase significantly. On the other hand, when the weight ratio of the first metal to the second metal exceeds 30.3%, the electrical characteristics are reduced (for example, the CI value is increased) due to the decrease in conductivity.

  Furthermore, in order to sufficiently obtain the CI value reduction effect by the annealing treatment, the weight ratio of the first metal to the second metal constituting the excitation electrodes 26 and 27 is more than 5.9% and not more than 12.9%. It is preferably 7.1% or more and 10.7% or less.

  In addition, the thickness of the base electrode layer made of the first metal is not particularly limited, but when the thickness is 10 nm to 26 nm, the amount of increase in CI value due to further heat treatment after annealing is reduced. Can do.

  Furthermore, the thickness of the upper electrode layer made of the second metal is not particularly limited, but if the thickness is 30 nm to 72 nm, the amount of increase in CI value due to further heat treatment after the annealing treatment should be reduced. In addition, good conduction can be obtained.

  In the quartz crystal resonator element 2 according to the present embodiment, the layer structure of the excitation electrodes 26 and 27 is the first metal layer on the first metal layer as described above when no heat treatment such as annealing is performed. Although the two metal layers are laminated, the first metal is diffused into the second metal layer by the heat treatment, and the excitation electrode 26 composed of the first metal and the second metal, The 27 layer structure varies.

  Further, the extraction electrode 28 of the quartz crystal vibrating piece 2 may be formed of a thin film similar to the excitation electrodes 26 and 27 described above or may be formed of a different thin film. For example, a base electrode layer of chromium, a gold The upper electrode layer may be a laminated thin film. This thin film is formed on the entire surface by a technique such as vacuum deposition or sputtering, and then formed into a desired shape by metal etching by photolithography.

  If the upper electrode layer of the extraction electrode 28 is made of gold and a gold bump is used as the metal bump 5, good adhesion between the metal bump 5 and the extraction electrode 28 can be secured.

  Next, a method for manufacturing the crystal resonator 1 having the above-described configuration will be schematically described.

  First, the frequency of the crystal vibrating piece 2 is roughly adjusted. Specifically, the amount of metal is increased or decreased by laser removal, ion milling, metal deposition, or the like with respect to the metal films 211 and 221 formed at the tip portions of the legs 21 and 22.

  After the rough adjustment of the frequency to the crystal vibrating piece 2 is thus completed, the extraction electrode 28 of the crystal vibrating piece 2 and the electrode pad of the base 3 are ultrasonically bonded through the metal bump 5 by the FCB method. Then, the extraction electrode 28 and the electrode pad are electrically bonded by the metal bump 5, and the crystal vibrating piece 2 is mounted on the base 3 by this bonding (mounting process referred to in the present invention).

  Then, after the crystal vibrating piece 2 is mounted on the base 3, an annealing process is performed to stabilize the electrode configuration (an annealing process referred to in the present invention) and reduce the CI value. In order to sufficiently reduce the CI value, it is preferable to perform an annealing treatment at a temperature of 250 to 400 ° C. for about 1 to 4 hours under a high vacuum.

  Next, heat treatment is further performed before the final frequency adjustment (frequency adjustment step described later) and the post heat treatment described later (pre-heat treatment step referred to in the present invention). This heat treatment is performed in a nitrogen atmosphere, and the temperature of the heat applied to the quartz crystal vibrating piece 2 is lower than the temperature of the annealing process and higher than the temperature applied to the quartz crystal vibrating piece 2 in the post-heat treatment process described later. It is said to be temperature. Although the CI value is slightly increased by such heat treatment, the amount of fluctuation of the CI value due to the heat treatment after the final frequency adjustment is suppressed by performing the heat treatment prior to the final frequency adjustment described later.

  Next, the final frequency adjustment to the crystal vibrating piece 2 mounted on the base 3, that is, fine adjustment of the frequency is performed (frequency adjustment step in the present invention). Specifically, the amount of metal is increased or decreased by an ion milling method or a metal vapor deposition method with respect to the metal films 211 and 221 formed at the tips of the legs 21 and 22.

  Then, after finishing the final frequency adjustment to the crystal vibrating piece 2 mounted on the base 3, the lid 4 is joined to the base 3 via the sealing material 33, and the crystal vibrating piece 2 is hermetically sealed in the internal space 11. Then, a post-heat treatment process such as a sealing process in which heat is applied, a reflow process in which heat is applied, and an aging process in which aging characteristics are measured is performed to manufacture the crystal unit 1.

  The post-heat treatment step in the present invention refers to a step in which heat is directly or indirectly applied to the piezoelectric vibrating piece after the final frequency adjustment for the piezoelectric vibrating piece mounted on the first sealing member. It is not limited to a sealing process, a reflow process, and an aging process. The pre-heat treatment step in the present invention refers to a step of directly or indirectly applying heat to the piezoelectric vibrating piece after the annealing treatment step and before the final frequency adjustment step and the post-heat treatment step.

  In the present embodiment, in the sealing process, the reflow process, and the aging process after the final frequency adjustment to the crystal vibrating piece 2 mounted on the base 3, the crystal vibrating piece 2 is indirectly connected to the crystal vibrating piece 2 via the base 3 and the lid 4. Heat is being applied to.

Below, using the piezoelectric vibrating piece of Examples 1 to 8 according to the present invention and the piezoelectric vibrating piece of Comparative Examples 1 to 3, the results of the experiment on the variation of the CI value that occurs when manufacturing the piezoelectric vibrating device, explain.
<Examples 1-8, Comparative Examples 1-3>
Each of the piezoelectric vibrating pieces according to Examples 1 to 8 and Comparative Examples 1 to 3 is the quartz vibrating piece 2 having the configuration shown in FIG. 2 described above. In the quartz crystal resonating pieces according to Examples 1 to 8 and Comparative Examples 1 to 3, the excitation electrodes 26 and 27 are ground electrode layers made of chromium (Cr) on both main surfaces and both side surfaces of the legs 21 and 22. Layer), and an upper electrode layer (Au layer) made of gold is formed on the base electrode layer, and the Cr layer and the Au layer are not subjected to any heat treatment. The thickness is as shown in Table 1 and Table 2 below. In Tables 1 and 2, the weight ratio of chromium (first metal) to gold (second metal) constituting the excitation electrodes 26 and 27 is shown as a weight ratio (Cr / Au). Further, Comparative Examples 2 and 3 are quartz crystal vibrating pieces that are generally applied as conventional piezoelectric vibrating pieces.

  The quartz crystal resonator element 2 according to Examples 1 to 8 and Comparative Examples 1 to 3 were each mounted on the base 3 by the FCB method as shown in FIG. Then, the quartz crystal vibrating piece 2 mounted on the base 3 was subjected to an annealing process (high vacuum, at 350 ° C. for 1 hour). Further, after the annealing treatment, the crystal vibrating piece 2 mounted on the base 3 was subjected to heat treatment (in a nitrogen atmosphere at 300 ° C. for 2 hours). Then, after finely adjusting the frequency (final frequency adjustment) with respect to the crystal vibrating piece 2, the lid 4 is heated and melt bonded to the base 3 to hermetically seal the crystal vibrating piece 2 and perform a sealing process. It was.

  From the above steps, the increase rate (%) of the CI value after the pre-heat treatment with respect to the CI value after the annealing treatment, the decrease rate (%) of the CI value after the annealing treatment with respect to the CI value immediately after mounting the base, the CI value after the pre-heat treatment The fluctuation rate (%) of the CI value after the sealing treatment with respect to was calculated. These calculation results are respectively expressed as an increase rate (%) of the CI value by the pre-heat treatment after the annealing treatment, a decrease rate (%) of the CI value by the annealing treatment, and a variation rate (%) of the CI value by the sealing treatment. Tables 1 and 2 show.

  Further, FIG. 3 shows the relationship between the above-described weight ratio (Cr / Au) and the increase rate (%) of the CI value due to the pre-heat treatment after the annealing treatment, and FIG. 4 shows the above-described weight ratio (Cr / Au). And the reduction rate (%) of the CI value due to the annealing treatment. FIG. 5 shows the relationship between the weight ratio (Cr / Au) and the variation rate (%) of the CI value due to the sealing process.

  As shown in the reduction rate (%) of the CI value due to the annealing process in Tables 1 and 2, in any of the quartz crystal vibrating reeds 2 of Examples 1 to 8 and Comparative Examples 1 to 3, the CI value was increased by the annealing process. A decrease was observed. Furthermore, it is recognized that the CI value decreased by the annealing treatment increases by the pre-heat treatment before the frequency adjustment after the annealing treatment in any of the quartz crystal vibrating pieces 2 of Examples 1 to 8 and Comparative Examples 1 to 3. It was recognized that the increase rate of the quartz crystal vibrating piece 2 according to Examples 1 to 8 was smaller than that of the conventional quartz vibrating piece 2 according to Comparative Examples 2 and 3.

  More specifically, from the graph shown in FIG. 3, the increase rate of the CI value after the pre-heat treatment with respect to the CI value after the annealing treatment is maximized when the weight ratio (Cr / Au) is 5.9%, It was recognized that when it exceeds 5.9%, it tends to decrease.

  Moreover, from the graph shown in FIG. 4, when the above-mentioned weight ratio (Cr / Au) is more than 5.9% to 12.9%, it is recognized that the CI value can be reduced by 15% or more by annealing treatment. When the weight ratio (Cr / Au) is 7.1% to 10.7%, it was found that the CI value can be reduced by approximately 25% or more by annealing.

  Furthermore, from the graph shown in FIG. 5, when the above-mentioned weight ratio (Cr / Au) exceeds 12.5%, the CI value after the sealing treatment (post-heat treatment) with respect to the CI value after the pre-heat treatment suddenly increases. It is recognized that the fluctuation rate increases, and the fluctuation rate of the CI value by this sealing process (post heat treatment) is particularly small when the weight ratio (Cr / Au) is 7.1% to 8.3%. Was recognized.

  From the above, in order to suppress the variation of the CI value due to further heat treatment (pre-heat treatment) after the annealing treatment, the weight ratio of the first metal to the second metal constituting the excitation electrodes 26 and 27 is 5.9%. It was recognized that it needed to be super. Also, the effect of reducing the CI value by the annealing treatment is sufficiently obtained when the weight ratio of the first metal to the second metal is more than 5.9% to 12.9%, and more than 7.1% to 10.7. It was found that the maximum was reached when the percentage was less than%. Furthermore, the variation in CI value due to the final frequency-adjusted heat treatment (post heat treatment) from the CI value after pre-heat treatment is reliably suppressed by limiting the weight ratio (Cr / Au) to less than 12.5%. It was recognized that it could be done.

  As mentioned above, although the fluctuation | variation of CI value produced at the time of manufacture of a piezoelectric vibration device was demonstrated using Examples 1-8, this invention is not limited to these Examples.

  In the present embodiment described above, as described above, quartz is used as the piezoelectric material constituting the piezoelectric vibrating piece. However, this is a preferred example and is not limited to this. The piezoelectric vibrating piece may be made of a piezoelectric material such as lithium tantalate or lithium niobate.

  In the above-described embodiment, as described above, the piezoelectric vibrating piece is a tuning-fork type quartz vibrating piece. However, the piezoelectric vibrating piece of the present invention is not limited to this, and is an AT-cut. A piezoelectric vibrating piece may be used.

  Further, in the above embodiment, the crystal resonator 1 is bonded to the electrode pad on the base 3 via the metal bump 5, but the piezoelectric vibration device of the present invention is not limited to this, For example, the piezoelectric vibrating piece may be bonded to the base electrode pad via a conductive adhesive.

  Further, in the above embodiment, the crystal resonator 1 is configured such that the crystal vibrating piece 2 (excitation electrodes 26 and 27) is hermetically sealed in the internal space 11 formed by the base 3 and the lid 4. However, the piezoelectric vibrating device according to the present invention includes the piezoelectric vibrating piece according to the present invention, and a first sealing member and a second sealing member for hermetically sealing the excitation electrode of the piezoelectric vibrating piece. As long as the configuration is provided, it is not particularly limited, and other forms may be used. More specifically, the crystal vibrating piece 2a is formed by sandwiching the crystal vibrating piece 2a having the vibrating portion 25a between the first sealing member 3a and the second sealing member 4a as shown in FIGS. The crystal resonator 1a may be configured such that the excitation electrode thus formed is hermetically sealed.

  FIG. 6 is a schematic configuration diagram illustrating a quartz crystal resonator element according to another embodiment of the present invention. FIG. 7 is a diagram showing a schematic configuration of a crystal resonator on which the crystal vibrating piece shown in FIG. 6 is mounted, and a cross section showing a state where the crystal vibrating piece is cut along the line AA in FIG. FIG. In FIG. 7, the hatching of the cross section is omitted in consideration of the visibility of the drawing.

  The quartz crystal vibrating piece 2a shown in FIG. 6 has a configuration in which a vibrating portion 25a is formed on a rectangular parallelepiped substrate 20a made of quartz which is a piezoelectric material. The vibration part 25a is composed of two leg parts 21a and 22a and a base part 23a, and the two leg parts 21a and 22a are formed so as to protrude from the base part 23a. Moreover, the area | region 26a adjacent to other parts except the part 24a of the outer periphery of the vibration part 25a is formed hollow. And the planar view main surface outer periphery of both the main surfaces of the crystal vibrating piece 2a is made into the junction parts 27a and 28a with the 1st sealing member 3a and the 2nd sealing member 4a, respectively.

  The leg portions 21a and 22a of the vibrating portion 25a are formed with first and second excitation electrodes (not shown) and extraction electrodes (not shown) configured with different potentials. Here, the first excitation electrode is formed on both main surfaces of one leg portion 21a and both side surfaces of the other leg portion 22a. Similarly, the second excitation electrode is formed on both main surfaces of the other leg portion 22a and on both side surfaces of the one leg portion 21a. In addition, the excitation electrode is composed of a first metal and a second metal in the same manner as the excitation electrodes 26 and 27 formed on the quartz crystal vibrating piece 2 shown in FIG. 2, and the second electrode with respect to the second metal constituting the excitation electrode is formed. The weight ratio of one metal is more than 5.9% and not more than 30.3%.

  Moreover, the 1st sealing member 3a is a rectangular parallelepiped board | substrate formed from the glass wafer, as shown in FIG. 7, One main surface 31a of this 1st sealing member 3a is set as a flat smooth surface (mirror surface process). Molded. The outer periphery of the main surface 31a of the first sealing member 3a in plan view is a joint 32a with the crystal vibrating piece 2a. Furthermore, the first sealing member 3a is provided with an electrode pad (not shown) that is electrically connected to the excitation electrode of the crystal vibrating piece 2a.

  Moreover, the 2nd sealing member 4a is a rectangular parallelepiped board | substrate formed from the glass wafer, as shown in FIG. 7, One main surface 41a of this 2nd sealing member 4a is used as a flat smooth surface (mirror surface process). Molded. The outer periphery of the main surface 41a of the second sealing member 4a in plan view is a joint 42a with the crystal vibrating piece 2a.

  Then, the crystal vibrating piece 2a is mounted on the first sealing member 3a by bonding the bonding portion 27a of the crystal vibrating piece 2a to the bonding portion 32a of the first sealing member 3a via the sealing material 6a. Further, the vibrating portion 25a (excitation electrode) of the crystal vibrating piece 2a is hermetically sealed by bonding the bonding portion 28a of the crystal vibrating piece 2a to the bonding portion 42a of the second sealing member 4a via the sealing material 7a. Thus, the crystal resonator 1a is configured.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. For this reason, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

1 Crystal resonator (piezoelectric resonator)
11 Internal space 2 Crystal vibrating piece (piezoelectric vibrating piece)
20 Substrate 21, 22 Leg 211, 221 Metal film 23 at the tip of the leg 23 Base 25 Groove 26, 27 Excitation electrode 28 Extraction electrode 3 Base (first sealing member)
31 Bottom 32 Wall 33 Sealing material 4 Lid (second sealing member)
5 Metal bump 1a Crystal resonator (piezoelectric resonator)
2a Quartz vibrating piece (piezoelectric vibrating piece)
20a Substrate 21a, 22a Leg 23a Base 24a Part of outer peripheral area 25a Vibrating part 26a Outer peripheral area 27a, 28a Quartz vibrating piece joint 3a First sealing member 31a First sealing member One main surface 32a First sealing member joint 4a Second sealing member 41a Second sealing member one main surface 42a Second sealing member joint 6a, 7a Sealing material

Claims (7)

A piezoelectric vibrating piece made of a piezoelectric material,
An excitation electrode is formed by a first metal bonded to the piezoelectric material and a second metal bonded to the first metal,
In the excitation electrode, the second metal has higher conductivity than the first metal, and the weight ratio of the first metal to the second metal is more than 5.9% to less than 12.9%. A piezoelectric vibrating piece characterized by that. The piezoelectric vibrating piece according to claim 1,
The piezoelectric vibrating piece, wherein the first metal is chromium, nickel, molybdenum, titanium, or tungsten. The piezoelectric vibrating piece according to claim 1 or 2,
The piezoelectric vibrating piece, wherein the second metal is gold. A piezoelectric vibrating device on which the piezoelectric vibrating piece according to any one of claims 1 to 3 is mounted,
The piezoelectric vibrating piece;
A piezoelectric vibration device comprising: a first sealing member and a second sealing member for hermetically sealing the excitation electrode of the piezoelectric vibrating piece. A method of manufacturing a piezoelectric vibration device according to claim 4 ,
A mounting step of mounting the piezoelectric vibrating piece on the first sealing member;
An annealing process for annealing the piezoelectric vibrating piece;
A frequency adjustment step of performing a final frequency adjustment on the piezoelectric vibrating piece;
After the mounting step and the annealing step, and before the frequency adjustment step, a pre-heat treatment step for performing a heat treatment on the piezoelectric vibrating piece,
A method of manufacturing a piezoelectric vibration device comprising: a post-heat treatment step of performing a heat treatment on the piezoelectric vibrating piece after the frequency adjusting step. A method of manufacturing a piezoelectric vibration device according to claim 5 ,
The temperature of the heat applied to the piezoelectric vibrating piece in the preliminary heat treatment step is set to be lower than the temperature of the annealing treatment step and higher than the temperature applied to the piezoelectric vibrating piece in the post heat treatment step. Manufacturing method of vibration device. A method of manufacturing a piezoelectric vibrating device comprising a piezoelectric vibrating piece made of a piezoelectric material, and a first sealing member and a second sealing member for hermetically sealing an excitation electrode of the piezoelectric vibrating piece,
A mounting step of mounting the piezoelectric vibrating piece on the first sealing member;
An annealing process for annealing the piezoelectric vibrating piece;
A frequency adjustment step of performing a final frequency adjustment on the piezoelectric vibrating piece;
After the mounting step and the annealing step, and before the frequency adjustment step, a pre-heat treatment step for performing a heat treatment on the piezoelectric vibrating piece,
After the frequency adjustment step, a post-heat treatment step of performing a heat treatment on the piezoelectric vibrating piece;
With
As the piezoelectric vibrating piece, the excitation electrode is formed by a first metal bonded to the piezoelectric material and a second metal bonded to the first metal. In the excitation electrode, the second metal is the first metal. A piezoelectric vibrating piece having a conductivity higher than that of one metal and having a weight ratio of the first metal to the second metal of more than 5.9% and not more than 30.3%;
The temperature of the heat applied to the piezoelectric vibrating piece in the preliminary heat treatment step is set to be lower than the temperature of the annealing treatment step and higher than the temperature applied to the piezoelectric vibrating piece in the post heat treatment step. Manufacturing method of vibration device.

Images