JP3893892B2 - Manufacturing method of vibrating piece - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a resonator element made of, for example, crystal.
[0002]
[Prior art]
The tuning fork type crystal vibrating piece 10 which is a vibrating piece is configured as shown in FIG. 6, for example. That is, the tuning fork type crystal vibrating piece 10 has a base portion 11 and two vibrating arm portions 12 and 13 that are formed to protrude from the base portion 11. As shown in FIG. 6, grooves 12a and 13a are formed on the front and back surfaces of the two vibrating arm portions 12 and 13, respectively. For this reason, as shown in FIG. 7 which is an AA ′ sectional view of FIG. 6, the vibrating arm portions 12 and 13 have a substantially H-shaped sectional shape.
[0003]
On the tuning-fork type crystal vibrating piece 10 having such grooves 12a and 13a in the arm portions 12 and 13, a film of Cr and Au is formed by sputtering or the like, and is etched by a photolithography technique. As shown in FIG. , 13a and excitation electrodes 12d and 13d are formed outside the arm portions 12 and 13, respectively.
[0004]
[Problems to be solved by the invention]
In the manufacture of such a conventional resonator element, a photoresist is applied by using a general spray coating to form the electrode pattern. However, there is a problem that resist hardly enters the groove and the side surface of the vibrating arm and uneven coating of the resist occurs. FIG. 8 schematically shows the uneven coating of the photoresist, and the resist film 14 applied to the shoulder portion of the vibrating arm portion, the side surface portion of the vibrating arm portion, the side surface portion of the groove, and the bottom surface portion of the groove is thinned. Yes. For this reason, if etching is performed using this resist film as an etching mask, a defect that holes are formed in the excitation electrodes 12c and 13c inside the groove and the excitation electrodes 12d and 13d on the side surface of the vibrating arm portion is generated, which in turn reduces the manufacturing yield. There was also a problem of incurring an increase in production costs.
[0005]
Accordingly, in view of the above problems, the present invention provides a highly accurate method for manufacturing a resonator element that suppresses defective hole formation of an excitation electrode by reducing resist coating unevenness without increasing production cost. Objective.
[0006]
[Means for Solving the Problems]
The method for manufacturing a vibrating piece according to the present invention is a method for manufacturing a vibrating piece having a base and a vibrating arm formed so as to protrude from the base, and forming an electrode on the base and the vibrating arm.
Etching the substrate, forming the outer shape of the base and the vibrating arm, and forming a groove or a through groove provided in the vibrating arm;
Forming an electrode layer on the substrate surface;
Applying a voltage to a photoresist composed of fine particles, and applying the photoresist particles to the surface of the substrate;
And performing a photolithographic process using the photoresist as an etching mask to form an electrode on the side surface of the base and the vibrating arm portion and on the inner surface of the groove or the through groove.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.
[0008]
FIG. 1 is a diagram showing a tuning-fork type crystal vibrating piece 100 which is a vibrating piece according to an embodiment of the present invention. The tuning fork type crystal vibrating piece 100 is formed by cutting out a single crystal of quartz at a specific cutting angle (cut angle) so as to form a so-called crystal Z plate, for example. Further, since the tuning-fork type crystal vibrating piece 100 shown in FIG. 1 is a vibrating piece that oscillates at a frequency of 32.768 kHz, for example, it is an extremely small vibrating piece. Such a tuning-fork type crystal vibrating piece 100 has a base 110 as shown in FIG. Two tuning fork arms 121 and 122 which are vibrating arm portions are arranged so as to protrude upward from the base portion 110 in the drawing.
[0009]
Further, grooves 123 and 124 are formed on the front and back surfaces of the tuning fork arms 121 and 122 as shown in FIG. The groove portions 123 and 124 are similarly formed on the back side of the tuning fork arms 121 and 122 not shown in FIG. 1, and as shown in FIG. 2, in the cross-sectional view taken along the line FF ′, the grooves 123 and 124 are formed. The cross-sections of the tuning fork arms 121 and 122 in which are formed are substantially H-shaped. By the way, as shown in FIG. 1, excitation electrodes 123a and 124a are respectively formed in the grooves 123 and 124 formed in the tuning fork arms 121 and 122 shown in FIG. The excitation electrodes 123a and 124a are also disposed on the side surfaces of the tuning fork arms 121 and 122 as shown in FIG. A power supply electrode 112 that performs power supply and the like is also disposed on the base 110 of the tuning fork type crystal vibrating piece 100 and the like.
[0010]
Thus, the excitation electrodes 123a and 124a are disposed in the groove portions 123 and 124, and the excitation electrodes 123a and 124a are also disposed on the side surfaces of the tuning fork arms 121 and 122. Therefore, when a voltage is applied to the excitation electrodes 123a and 124a, the tuning fork An electric field is efficiently generated in the arms 123 and 124, and vibration is generated in a state where the vibration loss of the tuning fork arms 123 and 124 is low and the CI value (crystal impedance or equivalent series resistance) is also low. In particular, as described above, the tuning-fork type crystal vibrating piece 100 shown in FIG. 1 is a small vibrating piece having a frequency of 32.768 kHz. Even with such a vibrating piece, the vibration loss is low and the CI value is low. It is a vibrating piece.
[0011]
By the way, as shown in FIG. 1, the whole base 110 of the tuning fork type crystal vibrating piece 100 is formed in a substantially plate shape. The base 110 is provided with two cut portions 125 on both sides of the base 110 as shown in FIG. The position of the notch 125 is arranged below the lower ends of the grooves 123 and 124 of the tuning fork arms 121 and 122 as shown in FIG. The vibration is not hindered.
[0012]
Further, a region that is actually fixed when the tuning fork type crystal vibrating piece 100 is fixed in the package is a fixing region 113 in FIG. As shown in FIG. 1, the lower end portion of the cut portion 125 is arranged in the information of FIG. 1 from the fixed region 113, so that the cut portion 125 does not affect the fixed region 113 and the tuning fork type crystal vibrating piece 100. It is configured so as not to adversely affect the fixed state with respect to the package.
[0013]
Since the notch 125 is disposed at such a position, the leakage vibration leaking from the grooves 123 and 124 due to the vibration of the tuning fork arms 121 and 122 is not easily transmitted to the fixed region 113 of the base 110 by the notch 125. Become. As described above, since the leakage vibration is hardly transmitted to the fixed region 113, it is difficult for energy to escape. Specifically, the conventional CI value has a variation of 10 kΩ or more in the standard deviation, but by providing the notch 125, the standard deviation is drastically reduced to 1 kΩ. did.
[0014]
By the way, in order for such a tuning fork type crystal vibrating piece 100 to operate at a stable frequency, the excitation electrodes 121a and 122a for vibrating the tuning fork arms 123 and 124 shown in FIG. Hereinafter, a method for forming a highly accurate electrode pattern will be described together with a method for manufacturing the tuning-fork type crystal vibrating piece 100.
[0015]
3 and 4 are flowcharts illustrating a method for manufacturing the resonator element according to the present embodiment. First, in FIG. 3, the base 110, the tuning fork arms 121 and 122, and the grooves 123 and 124 as shown in FIG. 1 are formed on the quartz wafer by anisotropic etching (step ST1). Next, Cr and Au are formed by sputtering or the like (step ST2). Then, a resist film is formed in the photolithography process for forming an electrode pattern (step ST3).
[0016]
This resist film is formed as shown in the flowchart of FIG. That is, in the photoresist fine particle generator 131 of the ultrafine particle generator 130 shown in FIG. 4, the photoresist 132 is submicron (0.1 μm to less than 1.0 μm) fine particles 132a (hereinafter referred to as resist fine particles) containing a solvent. ) (Step ST21).
[0017]
Then, the resist fine particles 132a are conveyed to the nozzle 134 of the coating chamber 133 by using an inert gas carrier gas such as air or nitrogen (step ST22).
[0018]
Then, a negative high voltage (30 kV to 100 kV) electrode 135 is disposed on the nozzle 134, thereby charging the resist fine particles 132a negatively (step ST23).
[0019]
On the other hand, the substrate 1 is placed on the positive electrode 136 having the ground potential so as to face the nozzle 134, and the negatively charged resist fine particles 132 b are caused to fly toward the substrate 1 having the ground potential to perform the above operation. It adheres efficiently and evenly to the surface of the substrate 1 (step ST24). In this way, the resist fine particles 132b can be applied to the surface of the substrate 1 with a uniform thickness to form the resist film 137.
[0020]
In this embodiment, an aerocoat system manufactured by Nordson Co., Ltd. was used as the ultrafine particle generator 130. The high voltage applied to the resist fine particles 132a is not limited to a negative high voltage, and may be a positive high voltage.
[0021]
Returning to the flowchart of FIG. 3, using this resist film 137 as an etching mask, wet etching of Au and Cr by photolithography is performed to form an electrode pattern (step ST4). Specifically, the excitation electrodes 123a and 124a of FIG. 1 are disposed on the groove portions 123 and 124, the side surfaces of the tuning fork arms 121 and 122, and the power supply electrode 112 is disposed on the base portion 110 and the like. Further, as shown in FIG. 1, a frequency adjustment electrode 114 is disposed at the tip of the tuning fork arms 121 and 122.
[0022]
Thus, after each electrode is formed, the frequency adjustment is performed by irradiating the frequency adjustment electrode 114 formed on the tuning fork arms 121 and 122 with a laser or the like through other predetermined processes (step ST5). ).
[0023]
As described above, the tuning-fork type crystal vibrating piece 100 as shown in FIG. 1 is manufactured. According to the method for manufacturing a vibrating piece according to the present invention, the vibrating piece having a groove or a through groove in the vibrating arm portion. On the other hand, by applying the photoresist 132 using an electrostatic coating method, the resist fine particles 132a containing the solvent adhere almost uniformly to the quartz substrate to form a resist film 137 with little film thickness unevenness. be able to. In particular, by making the photoresist 7 into submicron ultrafine particles, the thickness of the resist film 137 can be made more uniform.
[0024]
An etching mask formed by exposing and developing the resist film 137 has a small size variation, and an electrode formed by etching using the etching mask has a small finished size variation. In addition, since there is no uneven application of resist, defects such as perforations in the electrode pattern after etching are remarkably reduced, and the manufacturing yield can be increased and a resonator element having a highly accurate electrode can be manufactured.
[0025]
In each of the above-described embodiments, the tuning fork type crystal vibrating piece of 32.768 kHz has been described as an example. However, it is obvious that the tuning fork type crystal vibrating piece of 15 kHz to 155 kHz can be applied. Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the claims. And the structure of the said embodiment can abbreviate | omit a part, or can be changed into the other arbitrary combinations which are not mentioned above.
[0026]
【The invention's effect】
As described above, according to the present invention, the method of forming a resist film, which is particularly important for forming an electrode pattern with high accuracy, is a resist electrostatic coating method using submicron ultrafine particles. Since the resist can be applied almost uniformly on the base and the vibrating arm, the photolithographic accuracy can be increased and the excitation electrode can be formed with high accuracy, and the hole defect of the excitation electrode can be remarkably reduced to increase the production cost. Therefore, it is possible to provide a method for manufacturing a resonator element that can be manufactured with a high yield.
[0027]
[Brief description of the drawings]
FIG. 1 is a schematic view of a tuning-fork type crystal vibrating piece manufactured by a method for manufacturing a vibrating piece according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view taken along line FF ′ of FIG.
FIG. 3 is a flowchart showing an embodiment of a method for manufacturing a resonator element according to an embodiment of the invention.
FIG. 4 is a flowchart showing a resist film manufacturing process which is one process of the vibrating piece manufacturing method according to the embodiment of the present invention.
FIG. 5 is an explanatory view showing a simple structure of an ultrafine particle generator used for producing a resist film, which is one step of a method for producing a resonator element according to an embodiment of the present invention.
FIG. 6 is a schematic view showing a conventional tuning fork type crystal vibrating piece.
7 is a schematic cross-sectional view taken along line AA ′ of FIG.
FIG. 8 is a schematic view of a resist film formed in a conventional vibrating piece manufacturing process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Tuning fork type crystal vibrating piece 110 ... Base 112 ... Feeding electrode 113 ... Fixed region 114 ... Frequency adjustment electrode 121, 122 ... Tuning fork arm 123, 124 ... Groove 123a, 124a ... excitation electrode 125 ... notch 131 ... ultrafine particle generator 132 ... photoresist 132a ... resist fine particle 132b ... negatively charged resist fine particle 133 ... coating chamber 134 .... Nozzle 135 ... Negative electrode 136 ... Positive electrode 137 ... Resist film

Claims (1)

A method of manufacturing a resonator element having a base and a vibrating arm formed protruding from the base, and forming an electrode on the base and the vibrating arm,
Etching the substrate, forming the outer shape of the base and the vibrating arm, and forming a groove or a through groove provided in the vibrating arm;
Forming an electrode layer on the substrate surface;
Applying a voltage to a photoresist composed of fine particles, and applying the photoresist particles to the surface of the substrate;
A step of forming an electrode on the side surface of the base and the vibrating arm portion and on the inner surface of the groove or through groove by performing photolithography using the photoresist as an etching mask. Production method.

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