JP5936438B2 - Method for manufacturing piezoelectric vibration device - Google Patents

Description

  The present invention relates to a method for manufacturing a piezoelectric vibration device used as a reference signal source for electronic devices such as mobile communication devices and smart meters and watches. Specifically, the present invention relates to a method for manufacturing a piezoelectric vibration device having an electrode having a structure in which gold (Au) and nickel (Ni) are laminated.

  Piezoelectric vibration devices such as vibrators, resonators, and oscillators are widely used as reference signal sources for watches and mobile communication devices. Among such piezoelectric vibration devices, in particular, crystal resonators, crystal resonators, and crystal oscillators that use quartz as a piezoelectric material are in great demand because of their good temperature characteristics and high accuracy.

  Generally, vibrators and resonators that are one form of piezoelectric vibration device are roughly classified into three types depending on the frequency band.

  The first is a tuning fork type vibrator that uses bending vibration and torsional vibration used in a low frequency band (several hundreds of kHz or less). Bending vibration is one of the vibration modes, and refers to a vibration mode in which the outer shape of the vibrating body is bent. On the other hand, torsional vibration refers to a vibration mode in which the outer shape of the vibrating body undergoes torsional motion.

Hereinafter, the structure of the most common tuning fork type crystal resonator will be described as a resonator using bending vibration or torsional vibration. FIG. 3 is a diagram showing the structure of a general tuning fork type crystal resonator.

  As shown in FIG. 3, a general tuning-fork type crystal resonator 10 includes an electrode 510 patterned in a desired shape on a vibrating piece 100 including a base 110 and a plurality of vibrating legs 120 protruding from the base 110. Is formed.

The vibrating piece 100 is formed into a tuning fork shape by processing a quartz wafer cut from a quartz crystal at a cutting angle called Z-cut. In recent years, there has been a strong demand for downsizing of the resonator element 100, and for this reason, it is often processed by wet etching that allows fine and precise processing.

  The electrode 510 is formed to apply a voltage to the vibration leg 120 as a vibration part to excite the vibration leg 120, and is also formed on the front and back surfaces and side surfaces of the vibration piece 100. Since the electrode 510 must be formed on the front and back surfaces and side surfaces of the fine vibrating leg 120, the electrode 510 is generally patterned by a photolithography method suitable for forming a fine shape.

  Usually, in the tuning fork type crystal resonator 10, as a material used for the electrode 510, a laminated film of gold (Au) and chromium (Cr) is often used. Gold (Au) is used because it has excellent conductivity and good corrosion resistance. Chromium (Cr) is used for the purpose of improving the adhesion between the vibrating piece 100 made of quartz and gold (Au).

FIG. 6 is a flowchart showing an electrode forming method of a general tuning fork type crystal resonator. Hereinafter, a method for forming the electrode 510 will be described in detail with reference to FIGS. First, a laminated film in which the lower layer is made of chromium (Cr) and the upper layer is made of gold (Au) is formed on the entire surface of the resonator element 100 (FIG. 6 -ST1: laminated film forming step). Next, a resist made of a photosensitive material is applied on the laminated film made of gold (Au) and chromium (Cr) (FIG. 6-ST2: resist coating process). Thereafter, the resist is patterned into a desired electrode shape by photolithography (FIG. 6-ST3: resist patterning step). Thereafter, the gold (Au) in the upper layer of the laminated film that is not covered with the patterned resist is wet-etched with an etching solution dedicated to gold (Au) (FIG. 6-ST4: Au etching process). Next, the lower layer of chromium (Cr) that appears on the surface after etching the upper layer of gold (Au) is wet-etched with an etchant dedicated to chromium (Cr) (FIG. 6-ST5: Cr etching step). Finally, the resist is removed with a stripping solution (FIG. 6-ST6: stripping step), and the electrode 510 patterned in a desired shape is completed.

  The second is a vibrator that utilizes thickness-shear vibration used in the mid-frequency band (several hundred kHz to 100 MHz). Thickness shear vibration is one of vibration modes, and refers to a vibration mode in which the upper and lower surfaces of the piezoelectric substrate in the thickness direction slide in opposite directions. The frequency f is a function of the thickness t of the resonator element, and the fundamental wave is a relational expression of f = k / t (k: constant). In general, a quartz crystal vibrating piece cut out from a rough quartz stone at a cutting angle called AT cut is used, and hence it is called an AT vibrator.

The structure of a typical AT vibrator as a vibrator using thickness shear vibration will be described below. FIG. 4 is a diagram showing the structure of a general AT vibrator.

  As shown in FIG. 4, a general AT vibrator 20 has a structure in which electrodes 520 patterned in a desired shape are formed on the front and back surfaces of a plate-like vibrating piece 200 cut out from an original quartz crystal by AT cut. I am doing.

  In general, the resonator element 200 used in the AT vibrator 20 is processed so that the outer peripheral portion of the resonator element 200 is thin in order to reduce generation of unnecessary vibration modes as much as possible.

  In addition, in order to stabilize the temperature characteristics of the AT vibrator 20, the electrode 520 is often a laminated film in which gold (Au) and nickel (Ni) are formed by a sputtering method. However, since it was difficult to process nickel (Ni) by wet etching in the past, it was shielded with a metal plate opened in a desired shape during film formation by sputtering, and only a predetermined portion opened was formed. In many cases, a film forming method was employed.

  Several methods have been devised for wet etching of a laminated film of gold (Au) and nickel (Ni). For example, Patent Document 1 describes an example of etching with an iodine-based etchant. However, details of the etching solution are not described.

  Further, in Patent Document 2, as an etchant for wet-etching a laminated film of gold (Au) and nickel (Ni), etching in which a phosphate pH buffer or a citric acid pH buffer is mixed with iodine and an iodine compound. Liquid has been proposed.

  In Patent Document 3, an etching solution in which an inorganic acid or a solid organic acid is mixed with iodine and an iodine compound, a nitrogen-containing five-membered ring compound, an organic sulfur compound, an alcohol compound, and a ketone compound in an iodine and iodine compound. An etching solution in which an organic solvent composed of an amide compound or the like is mixed has been proposed.

  The third is a resonator using a surface acoustic wave used in a high frequency band (100 MHz or higher). The surface acoustic wave refers to a wave that vibrates and propagates on the surface of the substrate. In general, a resonator using a surface acoustic wave is referred to as a SAW resonator by abbreviating Surface Acoustic Wave, which is an English translation of the surface acoustic wave.

The structure of a SAW resonator using surface acoustic waves will be described below. FIG. 5 is a diagram showing the structure of a general SAW resonator.

As shown in FIG. 5, the SAW resonator 30 has a structure in which electrodes 530 are alternately arranged on the surface of a vibrating piece 300 made of a piezoelectric material, and the surface of the vibrating piece 300 vibrates in a wave shape. The oscillation frequency is determined by the distance between the electrodes and the speed of propagation through the substrate material, and the higher the frequency, the higher the frequency that can be achieved.

Usually, the SAW resonator 30 often has electrodes 530 formed at intervals of 10 μm or less in order to obtain a high frequency characteristic. Thus, conventionally, the electrode 530 is often formed by processing aluminum (Al) or the like by a dry etching method capable of fine processing.

In the SAW resonator 30, not only quartz but also piezoelectric ceramic materials (lithium niobate single crystal, lithium tantalate single crystal, etc.) are often used as the resonator element 300.

  As described above, the vibration mode to be used differs depending on the frequency band, and various forms are employed for each electrode material and electrode formation method.

JP-A-8-203844 Patent 4696565 JP 2010-229429

  In the case of the tuning-fork type crystal resonator 10 used in a low frequency band (100 kHz or less), the electrodes 510 must be formed on the front and back surfaces and the side surfaces of the fine vibrating legs 120 that are the vibrating portions. Therefore, a wet etching method that can pattern a plurality of surfaces simultaneously and finely has been used. However, materials capable of wet etching are limited, and among them, a laminated film of gold (Au) and chromium (Cr) having good wet etching properties is often used as an electrode material.

  However, chromium (Cr) has a characteristic of being diffused between gold (Au) atoms when heated (generally referred to as thermal diffusion), and is unstable to heat. In the vibrator, when this thermal diffusion occurs, the vibration characteristics change, and a vibrator with low reliability is formed.

  As an electrode material that hardly causes thermal diffusion and is stable against heat, a laminated film of gold (Au) and nickel (Ni) is known, but nickel (Ni) is difficult to wet etch, and tuning fork type quartz crystal It was not used as the electrode 510 of the vibrator 10.

Etching solutions that wet-etch the laminated film of gold (Au) and nickel (Ni) include etching solutions in which iodine and iodine compounds are mixed with phosphoric acid pH buffering agents or citric acid pH buffering agents, and iodine and iodine. Etching solution in which inorganic acid or organic acid that is solid at room temperature is mixed with compound, organic solvent consisting of nitrogen-containing five-membered ring compound, organic sulfur compound, alcohol compound, ketone compound, amide compound, etc. is mixed with iodine and iodine compound Etching solutions and the like that have been proposed have been proposed, but none of them has a processing accuracy enough to pattern a fine shape, and is not suitable for forming the electrode 510 of the tuning-fork type crystal resonator 10.

  In addition, these etching solutions contain acids and organic solvents, and damage the piezoelectric materials and resists other than gold (Au) and nickel (Ni). .

  In the case of the AT vibrator 20 using the thickness-shear vibration used in the middle frequency band (100 kHz to 1 MHz), patterning with a fine shape was not necessary conventionally, so the electrode 520 is formed by a method other than wet etching. It was patterned. However, in recent years, there is an increasing demand for miniaturization of the AT vibrator 20, and it has become difficult to pattern the electrode 520 by the conventional method. Therefore, it has become necessary to pattern the electrode 520 in the AT vibrator 20 by the wet etching method.

However, the laminated film of gold (Au) and nickel (Ni) that has been conventionally used as the electrode 520 of the AT vibrator 20 has a drawback that it is difficult to wet-etch nickel (Ni).

In the case of the SAW resonator 30 using a surface acoustic wave used in a high frequency band (1 MHz or higher), the electrode 530 must be accurately patterned at an interval of 10 μm or less. Conventionally, patterning is performed by a dry etching method. Has been made.

However, the dry etching method is difficult to process in large quantities at a time, and the apparatus becomes large, so that the productivity is poor.

In order to solve the above-described problems, a method for manufacturing a piezoelectric vibration device according to the present invention is characterized in that an electrode is formed by the following manufacturing method.

Specifically, a method for manufacturing a piezoelectric vibrating device in which an electrode is formed of a laminated film containing at least nickel (Ni) on a vibrating piece made of a piezoelectric material, wherein nickel (Ni) formed on the vibrating piece is made of iodine and The electrode is formed by etching with an etching solution containing an iodine compound and potassium chloride.

  Furthermore, the multilayer film includes at least gold (Au) and nickel (Ni), and is characterized by etching gold (Au) and nickel (Ni) with the etching solution.

Furthermore, the iodine compound is characterized by being potassium iodide or ammonium iodide.

A method for manufacturing a piezoelectric vibration device comprising 0.1 wt% or more of potassium chloride and 10.0 wt% or more of an iodine compound .

  Further, the vibrating piece is made of quartz.

  Further, the piezoelectric vibration device is a tuning fork-shaped piezoelectric vibrator having a base portion and the leg-shaped vibration portion protruding from the base portion.

A method of manufacturing a piezoelectric vibrating device in which an electrode is formed of a laminated film containing at least nickel (Ni) on a vibrating piece made of a piezoelectric material, wherein the vibrating piece is made of gold (Au) on at least nickel (Ni). A laminated film forming step for forming the formed laminated film, a mask layer forming step for forming a mask layer of a desired shape on the laminated film, and nickel (Ni) of the laminated film in a portion not covered with the mask layer And a gold film (Au) with a single layer of etching solution, and a peeling process for peeling the mask layer.

  Further, the mask layer forming step includes a resist coating step of applying a resist made of a photosensitive material on the laminated film and a resist patterning step of patterning the resist into a desired shape.

Furthermore, in the laminated film etching step, gold (Au) and nickel (Ni) in the laminated film are continuously etched with an etching solution.

  Furthermore, the etching solution is characterized by containing iodine, an iodine compound, and potassium chloride.

  Furthermore, the iodine compound is characterized by being potassium iodide or ammonium iodide.

A method for manufacturing a piezoelectric vibration device comprising 0.1 wt% or more of potassium chloride and 10.0 wt% or more of an iodine compound .

  Further, the vibrating piece is made of quartz.

  Further, the vibrating piece is a tuning fork-shaped piezoelectric vibrator having a base and the leg-shaped vibrating portion protruding from the base.

  The method for manufacturing a piezoelectric vibrating device according to the present invention can form gold (Au) and nickel (Ni) laminated film electrodes with little thermal diffusion on the front and back surfaces and side surfaces of the vibrating portion. High piezoelectric vibrator can be provided.

  Furthermore, since the electrode of the laminated film of gold (Au) and nickel (Ni) can be formed finely and with high accuracy, a small piezoelectric vibrator can be provided.

  Furthermore, since the electrode of the laminated film of gold (Au) and nickel (Ni) is formed by a wet etching method, it can be processed in large quantities at a time, and thus a piezoelectric vibrator having excellent productivity can be provided. Is possible.

3 is a flowchart showing a method for forming an electrode of a piezoelectric vibrator of the present invention. It is a 2nd flowchart which shows the electrode formation method of the piezoelectric vibrator of this invention. It is the figure which showed the structure of the general tuning fork type crystal resonator. It is the figure which showed the structure of the general AT vibrator. It is the figure which showed the structure of the general SAW resonator. It is a flowchart which shows the electrode formation method of a general tuning fork type crystal resonator.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In this example, the method for manufacturing a piezoelectric vibrating device of the present invention was used for manufacturing a tuning fork type crystal resonator. FIG. 3 is a diagram showing the structure of a general tuning fork type crystal resonator. This will be described below with reference to FIG.

  As shown in FIG. 3, a general tuning-fork type crystal resonator 10 includes an electrode 510 patterned in a desired shape on a vibrating piece 100 including a base 110 and a plurality of vibrating legs 120 protruding from the base 110. Is formed.

The vibrating piece 100 is formed into a tuning fork shape by processing a quartz wafer cut from a quartz crystal at a cutting angle called Z-cut. In recent years, there has been a strong demand for downsizing of the resonator element 100, and for this reason, it is often processed by wet etching that allows fine and precise processing.

  The electrode 510 is formed to apply a voltage to the vibration leg 120 as a vibration part to excite the vibration leg 120, and is also formed on the front and back surfaces and side surfaces of the vibration piece 100.

  In this example, the electrode 510 having a two-layer structure in which the upper layer is made of gold (Au) and the lower layer is made of nickel (Ni) is formed on the vibrating piece 100. Gold (Au) is used because it has excellent conductivity and good corrosion resistance, and nickel (Ni) is used for the purpose of increasing the adhesion between the vibrating piece 100 made of quartz and gold (Au).

  In addition, the electrode 510 having a laminated structure of gold (Au) and nickel (Ni) has less thermal diffusion even when heated, compared to the laminated structure of gold (Au) and chromium (Cr), and is thus stable against heat. ing. Therefore, it is possible to manufacture a highly reliable crystal resonator 10 with stable vibration characteristics against thermal fluctuations.

The electrode 510 having a laminated structure of gold (Au) and nickel (Ni) shown in this example was formed by the following method. FIG. 1 is a flowchart showing an electrode forming method of a piezoelectric vibrator according to the present invention.

First, a laminated film having a lower layer made of nickel (Ni) and an upper layer made of gold (Au) is formed on the entire surface of the resonator element 100 (FIG. 1-ST1: laminated film forming step). In this embodiment, after nickel (Ni) is formed in a thickness of 0.3 μm on the vibrating piece 100 made of quartz by sputtering, gold (Au) is subsequently deposited on the nickel (Ni) by sputtering. The film was formed to a thickness of 2 μm. In addition, since the film formation of gold (Au) was performed in a vacuum atmosphere after the film formation of nickel (Ni), the film formation is performed without generating an oxide layer at the boundary between nickel (Ni) and gold (Au). I was able to.

In this embodiment, nickel (Ni) and gold (Au) are formed by sputtering, but the effect of the present invention can be sufficiently achieved by using other vacuum film formation methods such as vapor deposition. can get.

Next, a resist made of a photosensitive material is applied on the laminated film made of gold (Au) and nickel (Ni) (FIG. 1-ST2: resist coating step). In this example, a resist (trade name: PEPR2400) manufactured by Rohm and Haas Electronic Materials Co., Ltd. was applied on gold (Au) with a thickness of 5 μm by an electrodeposition method.

In this embodiment, the resist is applied by the electrodeposition method. However, the effects of the present invention can be sufficiently obtained even by applying other coating methods such as spray coating and dip coating.

Thereafter, the resist is patterned into a desired electrode shape by photolithography (FIG. 1-ST3: resist patterning step). In this example, in order to pattern not only the front and back surfaces of the resonator element 100 but also the side surfaces, exposure was performed by an oblique exposure method, and the resist was patterned by being immersed in hungry water at 25 ° C. for about 20 minutes and developed. .

After that, a part of the laminated film that is not covered with the resist, that is, a part of the laminated film that has been exposed by removing the resist in the resist patterning process is applied to both gold (Au) and nickel (Ni) with one kind of etching solution. Wet etching is performed (FIG. 1-ST4: laminated film etching process). The present invention is characterized by the composition of the etching solution used at this time. We have found that gold (Au) and nickel (Ni) can be wet etched together using an etchant containing iodine, iodine compounds and potassium chloride.

In this example, an etching solution comprising 1.8 wt% iodine, 10.0 wt% potassium iodide, 5.0 wt% potassium chloride, and 83.2 wt% water, gold (Au) and nickel (Ni). As a result of wet etching, the laminated film could be patterned with very high processing accuracy with a dimensional error of 0.3 μm or less with respect to the resist shape formed in the resist patterning step. In this embodiment, wet etching is performed by the immersion method, but wet etching may be performed by a spray method or a paddle method.

The etching solution used in the production method of the present invention preferably does not contain an organic solvent as in this embodiment. This is because if the organic solvent is contained, the resist is attacked by the organic solvent, and patterning may not be performed with high accuracy.

Finally, the resist is removed with a stripping solution such as an organic solvent (FIG. 1-ST5: stripping step) to complete an electrode 510 having a laminated structure of gold (Au) and nickel (Ni) patterned in a desired shape. It was.

In the above manufacturing method, in ST4: laminated film etching step, it is desirable that the etching of gold (Au) and the etching of nickel (Ni) are continuously performed without interposing another step in the middle. This is because, after etching gold (Au), if nickel (Ni) is etched after sandwiching water washing and drying operations, the surface of nickel (Ni) is altered and it becomes difficult to etch. In addition, by completing the etching of gold (Au) and the etching of nickel (Ni) in one process, the number of processes can be reduced as compared with the conventional process, and the productivity is improved.

  In this example, in manufacturing the tuning-fork type crystal resonator 10 similar to that in Example 1, etching was performed with an etching solution in which the ratio of iodine, potassium iodide, and potassium chloride was changed, and gold (Au) and nickel ( An electrode 510 made of a laminate of Ni) was formed.

  First, etching is performed on a stacked film of gold (Au) and nickel (Ni) by changing iodine from 1.8 wt% and potassium iodide to 10.0 wt% and potassium chloride from 0.05 wt% to 50.0 wt%. The sex was confirmed. The results are shown in Table 1.

  In the etching solution having a composition containing 0.05 wt% of potassium chloride, nickel (Ni) was slightly discolored and remained, but by containing 0.1 wt% or more, nickel (Ni) could be etched. Furthermore, nickel (Ni) could be etched accurately in a short time by containing 0.2 wt% or more of potassium chloride. In addition, when an experiment was conducted in which the amount of potassium chloride added was increased and 50.0 wt% of potassium chloride was added, nickel (Ni) could be etched, but the potassium chloride remained undissolved. It was. Therefore, it was confirmed that even when 50.0 wt% or more of potassium chloride was added, only the use efficiency of the material was deteriorated and no further effect was obtained.

  Next, the iodine (1.8 wt%), potassium chloride (5.0 wt%), and potassium iodide (0.2 wt% to 35.0 wt%) were changed to change the gold (Au) and nickel (Ni) laminated film. The etching property was confirmed. The results are shown in Table 2.

  As a result of experimenting by changing the content of potassium iodide, etching was not performed when 0.2 wt% of potassium iodide was contained, but gold (Au) was also nickel when containing 1.0 wt% or more of potassium iodide. (Ni) could also be etched.

  In this example, in manufacturing the tuning-fork type crystal resonator 10 similar to that in Example 1, an etching solution containing 1.0 wt% iodine, 10.0 wt% ammonium iodide, and 5.0 wt% potassium chloride. The electrode 510 made of a laminate of gold (Au) and nickel (Ni) was formed.

As a result, even with an etching solution containing ammonium iodide which is a kind of iodine compound, gold (Au) and nickel (Ni) can be etched in the same manner as an etching solution containing potassium iodide. ) And nickel (Ni) laminated structure 510 could be formed.

  This embodiment is a tuning fork type quartz crystal resonator 10 shown in FIG. 3, which has an electrode 510 having a three-layer structure in which an upper layer is gold (Au), an intermediate layer is nickel (Ni), and a lower layer is chromium (Cr). In this example, the child 10 is manufactured. Each of these three types of materials used for the electrode 510 has an individual role. Chromium (Cr) has a role to make the quartz crystal vibrating piece 100 more firmly attached, and nickel (Ni) has a role to prevent chromium (Cr) from diffusing into gold (Au). Gold (Au) has a role of efficiently applying voltage to the resonator element by utilizing its low resistivity.

The present embodiment will be described below with reference to the flowchart shown in FIG. First, a laminated film having a three-layer structure is formed on the entire surface of the resonator element 100 (FIG. 1-ST1: laminated film forming step). In this embodiment, chromium (Cr) is first formed to a thickness of 0.5 μm on the resonator element 100 made of quartz by a sputtering method, and then nickel (Ni) is added to the chromium (Cr) to a thickness of 0.5 μm. A film was formed to a thickness of 3 μm, and finally, gold (Au) was formed to a thickness of 1.2 μm on nickel (Ni). Since chromium film formation, nickel (Ni) film formation, and gold (Au) film formation were continuously performed in a vacuum atmosphere, each of chromium (Cr), nickel (Ni), and gold (Au) It was possible to form a film without forming an oxide layer at the boundary.

Next, a resist made of a photosensitive material is applied onto the three-layered film (FIG. 1-ST2: resist coating process). In this example, a resist (PEPR2400) manufactured by Rohm and Haas Electronic Materials Co., Ltd. was applied on gold (Au) with a thickness of 5 μm by an electrodeposition method.

Thereafter, the resist is patterned into a desired electrode shape by photolithography (FIG. 1-ST3: resist patterning step). In this example, in order to pattern not only the front and back surfaces of the resonator element 100 but also the side surfaces, exposure was performed by an oblique exposure method, and the resist was patterned by being immersed in hungry water at 25 ° C. for about 20 minutes and developed. .

Thereafter, the portion of the laminated film not covered with the resist, that is, the portion of the laminated film exposed by removing the resist in the resist patterning step is etched (FIG. 1-ST4: laminated film etching step). Since the upper layer is gold (Au) and the middle layer is nickel (Ni), the laminated film in this embodiment is an etching solution containing iodine, iodine compound and potassium chloride. Both gold (Au) and nickel (Ni) are wet etched. did. Then, the underlying chromium (Cr) was exposed in the etched portion, so this time, the chromium (Cr) was etched with a nitric acid-based etchant.

Finally, the resist is removed with a stripping solution such as an organic solvent (FIG. 1-ST5: stripping step), and a three-layer structure of gold (Au), nickel (Ni), and chromium (Cr) patterned in a desired shape The electrode 510 was completed.

  By doing so, the present invention can also form the electrode 510 having three or more layers.

  In this example, the piezoelectric vibrating device manufacturing method of the present invention was used for manufacturing the AT vibrator shown in FIG.

FIG. 2 is a second flowchart illustrating the electrode forming method of the piezoelectric vibrator of the present invention. The present embodiment will be described below with reference to the second flowchart shown in FIG.

  FIG. 4 is a diagram showing the structure of a general AT vibrator. In manufacturing the AT vibrator 20 having the configuration as shown in FIG. 4, first, a laminated film having a lower layer made of nickel (Ni) and an upper layer made of gold (Au) was formed on the resonator element 200 (FIG. 2-ST1: (Laminated film forming step). In this embodiment, first, nickel (Ni) is formed in a thickness of 0.3 μm on a vibrating piece 200 made of quartz by a sputtering method, and then gold (Au) is formed on nickel (Ni) with a thickness of 1.0 μm. A film was formed with a thickness.

  Next, an organic ink was drawn in a desired shape on the laminated film by an ink jet method capable of drawing a fine pattern to form a mask layer made of the organic ink (FIG. 2-ST2: Mask layer forming step).

  In this embodiment, the mask layer is drawn and formed by the ink jet method, but the mask layer may be formed by using a screen printing method, a tako printing method, or the like.

After that, the laminated film of the part not covered with the mask layer of the organic ink drawn in a desired shape, that is, the laminated film of the exposed part is etched with an etching solution containing iodine, potassium iodine and potassium chloride. Both gold (Au) and nickel (Ni) were wet-etched (FIG. 2-ST3: laminated film etching process). Then, the shape of the mask layer is transferred to the laminated film.

Finally, the mask layer made of organic ink is removed with a stripping solution such as an organic solvent (FIG. 2-ST4: stripping step), and gold (Au) and nickel (Ni) laminated in a desired shape are laminated. An electrode 520 having a structure was completed.

  According to this embodiment, since the electrode 520 having a laminated structure made of gold (Au) and nickel (Ni) can be formed even in a minute region, the AT vibrator 20 can be downsized.

  In this example, the method for manufacturing a piezoelectric vibration device of the present invention was used for manufacturing a SAW resonator. FIG. 5 is a diagram showing the structure of a general SAW resonator. This will be described below with reference to FIG.

  In manufacturing the SAW resonator 30 having the configuration shown in FIG. 5, first, a laminated film made of nickel (Ni) as a lower layer and gold (Au) as an upper layer is formed on a vibrating piece 300 as a vibrating portion (see FIG. 5). 1-ST1: Laminated film forming step). In this embodiment, first, a nickel (Ni) film having a thickness of 0.3 μm is formed on the vibrating piece 300 made of quartz by a sputtering method, and then gold (Au) is formed on the nickel (Ni) with a thickness of 1.0 μm. A film was formed with a thickness.

Next, a resist made of a photosensitive material is applied on the laminated film made of gold (Au) and nickel (Ni) (FIG. 1-ST2: resist coating step). In this example, a resist (trade name: TSMR8900) manufactured by Tokyo Ohka Kogyo Co., Ltd. was applied on gold (Au) with a thickness of 0.5 μm by spin coating.

In this embodiment, the resist is applied by a spin coating method, but the effects of the present invention can be sufficiently obtained even by applying other coating methods such as a spray coating method and a roll coating method.

Thereafter, the resist is patterned into a desired electrode shape by photolithography (FIG. 1-ST3: resist patterning step). In this embodiment, since a very fine electrode shape is required, the resist was patterned by a photolithography method using a reduction exposure method widely used in the LSI field.

In addition to the patterning method using the reduced exposure method, the patterning method using the electron beam exposure method, the nanoimprint method, and the like are also suitable for patterning a fine electrode shape as in this embodiment.

Thereafter, both the gold (Au) and nickel (Ni) are wet-etched with a single type of etching solution in the laminated film that is not covered with the resist, that is, the exposed laminated film (FIG. 1-ST4). : Laminated film etching step).

In this example, an etching solution comprising 1.8 wt% iodine, 10.0 wt% potassium iodide, 5.0 wt% potassium chloride, and 83.2 wt% water, gold (Au) and nickel (Ni). The laminated film consisting of was wet etched.

Finally, the resist is removed with a stripping solution such as an organic solvent (FIG. 1-ST5: stripping step), and a lamination of gold (Au) and nickel (Ni) patterned in a very fine shape with a line width of 5 μm. An electrode 530 having a structure was completed.

  In this embodiment, the resonator element 300 made of quartz is used. However, the resonator element 300 is made of a piezoelectric material other than that, for example, a lithium niobate single crystal, a lithium tantalate single crystal, a langasite single crystal, or the like. However, the manufacturing method of the present invention is applicable.

  According to the present embodiment, it is possible to pattern the electrode 530 having a fine shape by a wet etching method capable of performing a large amount of etching processing at a time. Therefore, the productivity is higher than patterning the electrode 530 by a dry etching method. It is possible to provide an excellent SAW resonator 30.

DESCRIPTION OF SYMBOLS 10 Crystal resonator 20 AT resonator 30 SAW resonator 100, 200, 300 Vibrating piece 110 Base 120 Vibrating leg 510, 520, 530 Electrode

Claims (14)

A method of manufacturing a piezoelectric vibration device in which an electrode is formed of a laminated film containing at least nickel (Ni) on a vibration piece made of a piezoelectric material,
A method of manufacturing a piezoelectric vibrating device, wherein the electrode is formed by etching nickel (Ni) formed on the vibrating piece with an etching solution containing iodine, an iodine compound and potassium chloride. The laminated film includes at least gold (Au) and nickel (Ni),
2. The method of manufacturing a piezoelectric vibration device according to claim 1, wherein gold (Au) and nickel (Ni) are etched with the etching solution.   The method for producing a piezoelectric vibration device according to claim 1 or 2, wherein the iodine compound is potassium iodide or ammonium iodide. 4. The method for manufacturing a piezoelectric vibration device according to claim 1 , wherein potassium chloride is contained in an amount of 0.1 wt% or more and iodine compound is contained in an amount of 10.0 wt% or more.   The method of manufacturing a piezoelectric vibrating device according to claim 1, wherein the vibrating piece is made of quartz.   6. The piezoelectric vibrator according to claim 1, wherein the piezoelectric vibration device is a tuning fork-shaped piezoelectric vibrator having a base portion and the leg-shaped vibration portion protruding from the base portion. A method for manufacturing a piezoelectric vibration device. A method of manufacturing a piezoelectric vibration device in which an electrode is formed of a laminated film containing at least nickel (Ni) on a vibration piece made of a piezoelectric material,
A laminated film forming step of forming a laminated film in which gold (Au) is formed on at least nickel (Ni) on the vibrating piece;
A mask layer forming step of forming a mask layer of a desired shape on the laminated film;
A laminated film etching step of etching nickel (Ni) and gold (Au) of a portion of the laminated film that is not covered with the mask layer with one kind of etching solution;
A method for manufacturing a piezoelectric vibration device, comprising: a peeling step of peeling the mask layer. In the mask layer forming step,
A resist coating step of applying a resist made of a photosensitive material on the laminated film;
The method of manufacturing a piezoelectric vibration device according to claim 7, further comprising: a resist patterning step of patterning the resist into a desired shape. In the laminated film etching step,
9. The method of manufacturing a piezoelectric vibration device according to claim 7, wherein gold (Au) and nickel (Ni) in the laminated film are continuously etched with the etching solution.   The method for manufacturing a piezoelectric vibration device according to claim 7, wherein the etching solution contains iodine, an iodine compound, and potassium chloride.   The method for manufacturing a piezoelectric vibration device according to claim 10, wherein the iodine compound is potassium iodide or ammonium iodide. The method for manufacturing a piezoelectric vibration device according to claim 10 or 11, wherein potassium chloride is contained at 0.1 wt% or more and iodine compound is contained at 10.0 wt% or more.
  The method of manufacturing a piezoelectric vibrating device according to claim 7, wherein the vibrating piece is made of quartz.   The piezoelectric vibrating device according to any one of claims 7 to 13, wherein the vibrating piece is a tuning fork-shaped piezoelectric vibrator having a base and the leg-shaped vibrating portion protruding from the base. Manufacturing method.

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