JP2006214779A - Manufacturing method of vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly accurate vibrator having a characteristic unchanging with the passage of time and excellent reliability, and a manufacturing method of the vibrator suitable for miniaturization. <P>SOLUTION: This manufacturing method of the vibrator, wherein an electrode is formed on the vibrator having a base part and a vibration leg formed protrusively from the base, part has a process for forming a protection film patterned on the electrode by a photolithography method; a process for adjusting a vibration mode of the vibration leg by balancing the weight of the vibration leg by removing especially a part of the vibration leg of the vibrator; and a process for removing dust adhering in the adjustment process of the vibration mode simultaneously by dissolving and removing the protection film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a tuning fork type vibration body including a base and a plurality of vibration legs formed to protrude from the base, and more particularly to a method for manufacturing a vibration body having a vibration mode adjustment step.

  In recent years, vibratory gyroscopes are used in a wide range of fields such as attitude control of aircraft, vehicles, etc., angular velocity detection of navigation systems, and camera shake control of video cameras. Among such vibrating gyroscopes, a piezoelectric gyro using a vibrating body of a piezoelectric material is becoming mainstream.

  As described above, in a situation where the piezoelectric gyro is used in a wide range of fields, there is an increasing demand for higher reliability and higher accuracy of the vibrator.

  Ideally, by achieving a vibrating body that vibrates at the designed resonant frequency and has a stable vibration balance, a highly reliable and highly accurate piezoelectric gyro can be obtained as a result. Due to the processing accuracy and the variation in the electrical characteristics of the piezoelectric material, it is not always possible to manufacture the vibrator in an ideal state.

  Therefore, in the past, vibration adjustment processing for adjusting the resonance frequency and adjusting the vibration balance was always performed in the manufacturing process of the vibrating body. This process is generally referred to as a vibration mode adjustment process.

  Hereinafter, a conventional method for manufacturing a vibrating body will be described (for example, see Patent Document 1). FIG. 6 is a perspective view showing the structure of a general vibrator. As shown in FIG. 6, the vibrating body 10 is composed of a tuning fork type piezoelectric body 100 having two vibrating legs 11 protruding from a base 12, and a vibration is applied to the piezoelectric body 100 by applying a voltage to the piezoelectric body 100. The electrode 200 for making it form is formed.

  When the conventional vibrating body 10 having such a configuration is used in a piezoelectric gyro, the angular velocity is detected using the Coriolis principle. The Coriolis principle is a principle that a vibration f0 in a certain direction is given to the vibrating leg 11 in a steady state, and a vibration fs is generated in a direction perpendicular to the vibration f0 when a rotation ω is added thereto. The vibrating body 10 detects the angular velocity by electrically detecting the vibration fs.

  Usually, crystal, piezoelectric ceramics, or the like is used for the piezoelectric body 100, and the outer shape thereof is formed by etching or mechanical cutting. However, regardless of which processing method is used, variations in processing dimensions always occur, and therefore, the weight balance of the vibrating legs 11 is unbalanced. If an imbalance occurs in the weight balance, the vibration f0 in the steady state vibrates differently from the designed vibration mode, and an accurate angular velocity cannot be detected.

  Therefore, conventionally, as shown in FIG. 6, a part of the vibration leg 11 is subjected to removal processing, and the removal unit 101 is provided to balance the weight balance of the vibration leg 11 and adjust the vibration mode of the vibration f0. It was.

FIG. 7 is a diagram showing a process for adjusting the vibration mode of a conventional vibrator. FIG. 8 is a perspective view showing a method for adjusting a vibration mode by grinding. In the conventional vibration mode adjustment process, first, as shown in FIG. 7A, the electrode 200 is formed on the piezoelectric body 110, and a predetermined electric field is applied to the piezoelectric body 110 to examine the vibration mode of the vibration legs. In most cases, the weight balance of the vibrating legs is lost at this stage, so that a vibration f1 that vibrates in a direction different from the desired direction is generated as shown in FIGS. .

  Therefore, in order to balance the weight balance, a process of removing a part of the piezoelectric body 100 is performed as shown in FIG. Conventionally, a processing method in which a predetermined portion of the vibrating leg 11 is ground by sliding a polishing tape 600 containing an abrasive as shown in FIG. By this grinding method, the vibration f1 is adjusted to the desired vibration f0.

  At that time, a part of the dust 500 generated by grinding always adheres to the vibrating leg 11. If the dust 500 adheres, even if the weight balance is adjusted, there is a risk that the dust 500 gradually peels off over time and the weight balance gradually collapses. Therefore, conventionally, in order to ensure reliability, as shown in FIG. 7C, the dust 500 reattached to the vibrating leg 11 is removed by cleaning, and the vibrating body 10 that generates the vibration f0 that is a desired vibration mode is obtained. I was getting.

  As a method for cleaning impurities such as dust 500 adhering to the vibrating body 10, a method using an ultrasonic cleaning method has been proposed (for example, see Patent Document 2). According to this cleaning method, ultrasonic cleaning was first performed with isopropyl alcohol (IPA), then steam cleaning was performed with a fluorine-based cleaning agent, and finally, the cleaning process was completed by drying.

Japanese Patent Laid-Open No. 2002-243451 (page 7, FIG. 3, FIG. 10) JP 2001-292046 A (5th page, FIG. 8)

  In the conventional manufacturing method of a vibrating body, in order to obtain a vibration mode as designed, a vibration mode adjustment step is essential. In addition, this vibration mode adjustment process was performed by cutting the vibration leg by a grinding method or the like, but a part of the dust generated at that time is reattached to the vibration leg, so a cleaning process using ultrasonic cleaning is used. , Adhered dust was removed.

  However, since a sufficiently strong ultrasonic vibration is required for complete delamination of the dust, a defect that the vibration leg breaks due to the ultrasonic vibration may occur. In addition, it has been found that such breakage failure of the vibration legs occurs more frequently as the vibration body is downsized and the vibration legs become thinner.

  On the other hand, if the output of the ultrasonic vibration is reduced in order to eliminate the breakage failure of the vibration leg, a failure that dust cannot be completely removed occurs. If there is dust removal residue, the dust gradually peels off over time, and the balance of the vibration mode that has been adjusted is lost. As a result, the angular velocity detection accuracy may be deteriorated.

  An object of the present invention is to provide a highly accurate and reliable method for manufacturing a vibrating body, and further to provide a method for manufacturing a vibrating body suitable for downsizing.

In order to solve the above problems, a method of manufacturing a vibrating body according to the present invention is a method of manufacturing a vibrating body in which an electrode is formed on a vibrating body having a base and a vibrating leg that protrudes from the base. ,
The method includes a step of forming a protective film on the electrode, a step of adjusting a vibration mode of the vibration leg by a process of removing a part of the vibrating body, and a step of removing the protective film.

  Further, it is desirable to use a photolithography method in the step of forming the protective film.

  Furthermore, it is desirable to use an electrodeposition resist in the step of forming the protective film.

  In the step of forming the protective film, it is desirable to apply a resist by a spray method.

  Furthermore, it is desirable to remove the protective film by dissolving it with a predetermined chemical solution.

  Further, it is desirable that the chemical solution is a developer.

  Alternatively, it is desirable that the chemical liquid is an etching liquid.

  Further, the protective film is preferably made of a material having conductivity and different from that of the electrode.

  Furthermore, the protective film is desirably a material containing any of copper (Cu), aluminum (Al), and nickel (Ni).

  The protective film is preferably a photosensitive material.

  Furthermore, it is desirable that the protective film is formed in the same shape as the electrode.

  Further, in the step of adjusting the vibration mode of the vibration leg, it is desirable that the vibrating body be removed by machining.

  Alternatively, in the step of adjusting the vibration mode of the vibration leg, it is desirable that the vibrating body is removed by laser ablation processing.

  Furthermore, it is desirable to have a process of removing a part of the vibration leg in the step of adjusting the vibration mode of the vibration leg.

  Furthermore, it is desirable that the vibrator is made of quartz.

(Function)
In the above means of the present invention, the step of adjusting the vibration mode of the vibration leg is performed after the protective film is formed. Normally, the vibration mode adjustment process is performed by removing a part of the vibrating body by machining, laser ablation processing, or the like. At that time, dust always adheres to the vibrating body. However, as described above, in the present invention, since the protective film is already formed, dust adheres on the protective film. After that, by dissolving and removing the protective film, the attached dust can be removed at the same time. Also, by removing the protective film, dust can be lifted and removed from the vibrating body, so there is almost no dust removal residue.

  Further, the above-described means of the present invention eliminates the need for ultrasonic cleaning as conventionally performed, so that it is possible to reduce the failure of the vibrating body due to ultrasonic vibration, and in particular, a failure failure has occurred. Even small and easy-to-use vibrators can be manufactured with good yield.

  According to the method for manufacturing a vibrating body of the present invention, the dust adhering to the vibration mode adjustment process can be completely removed, so that the vibration mode can be adjusted with high accuracy. Now you can get a body.

  Further, according to the method for manufacturing a vibrating body of the present invention, dust adhering to the adjustment process of the vibration mode can be completely removed, so that there is a risk that the dust will be peeled off over time after the vibrating body is completed as in the past. As a result, a highly reliable vibrator was obtained.

  In addition, according to the method for manufacturing a vibrating body of the present invention, the cleaning step by ultrasonic vibration can be eliminated, and even a small vibrating body can be manufactured without being damaged.

(First embodiment)
In the present invention, a piezoelectric body 100 that is a tuning-fork type vibrating body having two vibrating legs 11 projecting from a base 12 as shown in FIG. 6 and a voltage applied to the piezoelectric body 100 formed on the piezoelectric body 100 are applied. A vibration body having a general structure including the electrode 200 for vibrating was manufactured.

  When such a tuning-fork type vibrating body is used for a piezoelectric gyro, the angular velocity is detected using the Coriolis principle. The Coriolis principle is a principle in which a vibration f0 in a certain direction is given to the vibrating leg 11 in a steady state, and when a rotation ω is added thereto, a vibration fs is generated in a direction perpendicular to the vibration f0. By detecting fs electrically, angular velocity can be detected. Therefore, the vibration f0 generated in the steady state cannot be detected with high accuracy unless the vibration f0 is stably oscillated in a certain direction.

  A method for manufacturing a vibrating body capable of generating a stable vibration f0 will be described below. FIG. 2 is a diagram showing the first half of the photolithography process in the method of manufacturing a vibrating body according to the present invention. FIG. 3 is a view showing the latter half of the photolithography process in the method of manufacturing a vibrating body according to the present invention. FIG. 4 is a diagram showing an electrode forming step in the method for manufacturing a vibrator according to the present invention. In the present embodiment, quartz is used as the piezoelectric body 110, and the tuning fork type outer shape is formed by etching with a 10% hydrofluoric acid aqueous solution. The processing by the etching method of quartz that is a piezoelectric material is a technique that is generally used to manufacture crystal resonators, crystal oscillators, and the like, and extremely fine and highly accurate processing is possible.

  Thereafter, as shown in FIG. 2A, an electrode film 210 was formed on the entire surface of the piezoelectric body 110 made of quartz, and a protective film 310 was further formed thereon. In this embodiment, the electrode film 210 having a two-layer structure in which the lower layer is made of chromium (Cr) and the upper layer is made of gold (Au) is deposited by a vapor deposition method so that the Cr film has a thickness of 0.03 μm and the Au film has a thickness of 0.15 μm. A film was formed. As the protective film 310, copper (Cu) was formed to a thickness of 0.15 μm by a vapor deposition method. Note that the Cr film is for increasing the adhesion between the Au film and the crystal, and may be formed very thin. Therefore, in FIG. 2, the Cr film layer is not shown. The electrode film 210 and the protective film 310 may be formed by any film formation method other than the vapor deposition method, for example, sputtering method, plating method, etc., and there is no problem in the present invention.

Next, as shown in FIG. 2B, a photosensitive material layer 410 is formed on the protective film 310 made of Cu. In this embodiment, an electrodeposition resist is used for the photosensitive material layer 410 and is formed on the protective film 310 with a thickness of about 8 μm. The electrodeposition resist is a resist that is formed on the surface of the electrode by applying an electric current to the base as in the case of electroplating. Therefore, it was very suitable for forming on the protective film 310 made of Cu having excellent conductivity, and was able to be formed with high adhesion and a stable surface state. In this embodiment, Cu is employed as the protective film 310, but is not limited to Cu in forming the electrodeposition resist. Aluminum (Al), nickel (Ni), etc., which are excellent in electrical conductivity, are also suitable for forming an electrodeposition resist.

  Next, as shown in FIG. 3A, the piezoelectric body 110 is exposed using two exposure masks 61 and 62 on which desired patterns 611 and 621 are drawn. At this time, as shown in FIG. 3A, ultraviolet rays (UV) are incident on the surfaces of the masks 61 and 62 from an oblique direction, and are irradiated on the piezoelectric body 110, so that not only on the surface of the piezoelectric body 110 but also on the side surfaces. A photosensitive material layer 410 was also exposed at the same time. Such an exposure method is generally called an oblique exposure method.

  Thereafter, the photosensitive material layer 410 made of an electrodeposition resist is developed with a developer dedicated to the electrodeposition resist, and a photosensitive material layer 400 having a desired shape is formed as shown in FIG.

  2 and FIG. 3 is a patterning method generally called a photolithography method, and is a method widely used for manufacturing ICs, liquid crystal displays, and the like. If this photolithography method is used, patterning with very high accuracy of micron level is possible, and it is suitable for downsizing of the vibrator.

  Next, portions of the protective film 310 and the electrode film 210 that are not covered with the photosensitive material layer 400 are removed by an etching method, and the patterned protective film 300 and the electrode 200 are formed as shown in FIG. Form. In this embodiment, the protective film 300 made of Cu was etched with an etching solution made of 10% ammonium persulfate aqueous solution, and the electrode 200 made of Au and Cr was etched with aqua regia and a nitric acid-based etching solution.

  Thereafter, as shown in FIG. 4B, the photosensitive material layer 400 is peeled off, and a structure in which the electrode 200 and the protective film 300 are laminated in the same shape at a desired position of the piezoelectric body 110 is formed. In this embodiment, the photosensitive material layer 400 is peeled off with a 4% aqueous sodium hydroxide solution.

  In this state, the weight balance between the two vibrating legs 11 is not balanced due to variations in processing accuracy that occur when the outer shape of the piezoelectric body 110 is formed. Therefore, as shown in FIG. 6, it is necessary to balance the weight balance of the vibration legs 11 and adjust the vibration mode of the vibration f <b> 0 by performing removal processing on a part of the vibration legs 11 and providing the removal unit 101. This process is referred to as a vibration mode adjustment process.

The vibration mode adjustment process of the present invention will be described below. FIG. 1 is a diagram showing a vibration mode adjustment process in the method of manufacturing a vibrator according to the present invention. First, as shown in FIG. 1A, by applying a current to the electrode 200, a predetermined electric field is applied to the piezoelectric body 110, and the vibration mode of the vibration leg at that time is examined. At this stage, since the vibration leg has lost its weight balance, a vibration f1 that vibrates in a direction different from the desired direction as shown in FIG.

  Therefore, in order to balance the weight balance, a process of removing a part of the piezoelectric body 100 is performed as shown in FIG. For this removal processing, machining by grinding or laser ablation processing is generally used. However, whichever processing method is used, the dust 500 generated at that time always adheres to the vibrating leg 11 again. In the present embodiment, a part of one vibrating leg of the piezoelectric body 100 is removed by machining by grinding.

Thereafter, as shown in FIG. 1C, the protective film 300 is dissolved and removed. Then, the dust 500 adhering to the protective film is also removed at the same time, and the dust can be completely removed. In the present embodiment, an etching solution made of 10% ammonium persulfate aqueous solution is used for dissolving and removing the protective film 300. As described above, the vibration f1 caused by the vibration mode caused by the loss of the weight balance can be adjusted to the vibration f0 which is the predetermined vibration mode.

  According to the present invention, since dust can be completely removed as described above, the accuracy of vibration mode adjustment is improved, and as a result, a highly accurate vibrating body can be obtained. Further, there is no risk of the dust falling off with the passage of time after completion of the vibrating body as in the prior art, and as a result, a highly reliable vibrating body could be obtained.

  Further, as described above, according to the method for manufacturing a vibrating body of the present invention, it is possible to completely eliminate the conventional cleaning process using ultrasonic vibration. For this reason, it was possible to greatly reduce the damage such as breaking of the thin vibration leg generated by the ultrasonic vibration. As a result, the vibrator can be further reduced in size.

(Second Embodiment)
FIG. 5 is a view showing another example of the method for manufacturing a vibrator according to the present invention. In the method for manufacturing a vibrating body according to the present invention, a photosensitive material may be used as the protective film. An example is shown below. First, as shown in FIG. 5A, an electrode film 210 is formed on the surface of the piezoelectric body 110, and a protective film 320 made of a photosensitive material is further formed thereon. In this embodiment, a resist (trade name: OFPR800) manufactured by Tokyo Ohka Co., Ltd. was applied as a protective film 320 on the electrode film 210 made of Cr as a lower layer and Au as an upper layer by a spray method. The film thicknesses of the Cr film were 0.03 μm, the Au film was 0.15 μm, and the resist was 3 μm.

  Next, the protective film 320 made of a photosensitive material (resist) is exposed and developed to form a protective film 300 having a desired pattern as shown in FIG. In the present embodiment, after the protective film 320 is exposed by an oblique exposure method (FIG. 3A) for oblique exposure, development is performed using a developer dedicated to resist (OFPR800).

  Next, a portion of the electrode film 210 that is not covered with the protective film 300 is removed by an etching method to form a patterned electrode 200 as shown in FIG. In this embodiment, the electrode 200 made of Au and Cr was etched with aqua regia and a nitric acid-based etchant, respectively. In this manner, the electrode 200 and the protective film 300 are stacked at the desired position of the piezoelectric body 110 in the same shape.

Thereafter, as shown in FIG. 1A, by applying a current to the electrode 200, a predetermined electric field is applied to the piezoelectric body 110, the vibration mode of the vibration leg at that time is examined, and the weight balance is balanced. As in 1 (b), a process for removing a part of the piezoelectric body 100 is performed. In the present embodiment, a part of one vibrating leg of the piezoelectric body 100 is removed by machining by grinding.

  Finally, as shown in FIG. 1C, the protective film 300 is dissolved and removed. Then, the dust 500 adhering to the protective film is also removed at the same time, and the dust can be completely removed. In this embodiment, the protective film made of a photosensitive material is dissolved and removed with acetone. As described above, the vibration f1 caused by the vibration mode caused by the loss of weight balance can be adjusted to the vibration f0 which is the predetermined vibration mode.

  Also by the manufacturing method as described above, dust can be completely removed, so that the accuracy of vibration mode adjustment is improved, and as a result, a highly accurate vibrating body can be obtained. Further, there is no risk of the dust falling off with the passage of time after completion of the vibrating body as in the prior art, and as a result, a highly reliable vibrating body could be obtained. In addition, since the cleaning process by ultrasonic vibration can be completely eliminated, it is possible to greatly reduce the damage such as breaking of the thin vibration leg generated by the ultrasonic vibration.

  In addition, although it demonstrated using the vibrating body which has two vibrating legs as embodiment of this invention, it cannot be overemphasized that this invention is applicable even when the number of vibrating legs is one or three or more. In addition, although the piezoelectric body is used as the vibrating body, a material other than the piezoelectric body, such as metal or silicon, may be used.

It is the figure which showed the adjustment process of the vibration mode in the manufacturing method of the vibrating body of this invention. It is the figure which showed the first half of the photolithography process in the manufacturing method of the vibrating body of this invention. It is the figure which showed the second half of the photolithography process in the manufacturing method of the vibrating body of this invention. It is the figure which showed the electrode formation process in the manufacturing method of the vibrating body of this invention. It is the figure which showed another example of the manufacturing method of the vibrating body of this invention. It is the perspective view which showed the structure of the general vibration body. It is the figure which showed the adjustment process of the vibration mode of the conventional vibrating body. It is the perspective view which showed the adjustment method of the vibration mode by grinding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vibrating body 11 Vibrating leg 12 Base 61, 62 Exposure mask 100, 110 Piezoelectric body 101 Removal part 200 Electrode 210 Electrode film 300, 310, 320 Protective film 400, 410 Photosensitive material layer 500 Dust 600 Polishing tape 610 Rollers 611, 621 pattern

Claims (15)

A method of manufacturing a vibrating body in which an electrode is formed on a vibrating body having a base and a vibrating leg formed protruding from the base,
A method of manufacturing a vibrating body, comprising: forming a protective film on the electrode; adjusting a vibration mode of the vibrating leg by a process of removing a part of the vibrating body; and removing the protective film. . The method for manufacturing a vibrating body according to claim 1, wherein a photolithography method is used in the step of forming the protective film. 3. The method for manufacturing a vibrator according to claim 1, wherein an electrodeposition resist is used in the step of forming the protective film. The method for manufacturing a vibrating body according to claim 1, wherein a resist is applied by a spray method in the step of forming the protective film. The method for manufacturing a vibrating body according to any one of claims 1 to 4, wherein the protective film is dissolved and removed by a predetermined chemical solution. The method for manufacturing a vibrator according to claim 5, wherein the chemical solution is a developer. The method for manufacturing a vibrating body according to claim 5, wherein the chemical liquid is an etching liquid. The method for manufacturing a vibrating body according to any one of claims 1 to 7, wherein the protective film is conductive and is made of a material different from that of the electrode. The method for manufacturing a vibrating body according to claim 1, wherein the protective film is a material containing any one of copper (Cu), aluminum (Al), and nickel (Ni). The method for manufacturing a vibrator according to claim 1, wherein the protective film is a photosensitive material. The method for manufacturing a vibrating body according to claim 1, wherein the protective film is formed in the same shape as the electrode. The method of manufacturing a vibrating body according to claim 1, wherein in the step of adjusting a vibration mode of the vibrating leg, the vibrating body is removed by machining. The method of manufacturing a vibrating body according to any one of claims 1 to 11, wherein in the step of adjusting a vibration mode of the vibrating leg, the vibrating body is removed by laser ablation processing. The method for manufacturing a vibrating body according to any one of claims 1 to 13, further comprising a step of removing a part of the vibrating leg in the step of adjusting a vibration mode of the vibrating leg. The method for manufacturing a vibrating body according to claim 1, wherein the vibrating body is made of quartz.

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