JP2004184120A - Frequency regulation method for piezoelectric oscillating type inertia sensor element, and piezoelectric oscillating type inertia sensor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frequency regulation method for a piezoelectric oscillation type inertia sensor element, and a piezoelectric oscillation type inertia sensor element. <P>SOLUTION: In this piezoelectric oscillation type inertia sensor element using a tuning fork type oscillator having at least two leg parts protruded in parallel to a Y-axis from a base part, a width W of the leg part along a quartz X-axis direction of the piezoelectric oscillation type inertia sensor element is thinner than that T of the leg part along a quartz Z-axis direction thereof. In this frequency regulation method for the piezoelectric oscillation type inertia sensor element having at least the two leg parts protruded in parallel to the Y-axis from the base part, other part other than an electrode is etched to regulate a frequency while measuring the frequency by a frequency measuring instrument provided with the electrode and connected to the electrode. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of adjusting the frequency of a piezoelectric vibration type inertial sensor element using a tuning fork type vibrator, and to the piezoelectric vibration type inertial sensor element.
[0002]
[Prior art]
A conventional piezoelectric vibrating inertial sensor element using a tuning-fork type vibrator processed by a wet etching method utilizing anisotropy of wet etching of quartz is disclosed in Japanese Patent Application Laid-Open No. 49-10691. As shown in FIG. 1A, a piezoelectric vibratory inertial sensor element is cantilevered on a plate-like support made of ceramic or the like, and one main surface of the piezoelectric vibratory inertial sensor element is placed on the preceding plate. The shape of the piezoelectric vibration type inertial sensor element is such that it is fixed on a support having a shape through an adhesive.
[0003]
Generally, in the piezoelectric vibrating inertial sensor element using a tuning-fork oscillator, and the excitation frequency f ₁ and the detection frequency f _2, the following is in the difference Δf of the frequency of the both relationships.
Δf = f ₂ - f ₁
[0004]
This Δf is a value that significantly affects the sensitivity of the piezoelectric vibration type inertial sensor element using the tuning fork type vibrator, and this Δf is a very small value of approximately 100 Hz to 200 Hz.
[0005]
In the conventional tuning fork type X-axis direction of the thickness of the piezoelectric vibrating inertial sensor device using a vibrator, and the Z-axis direction of the actually measured by the thickness following the excitation from the two formulas frequency f ₁ and the detection frequency f _2, and a difference Δf between the two frequencies is set.
f ₁ = kf ₁ × ω ₁ / l ² And f ₂ = kf ₂ × ω ₂ / l ²
Here, kf ₁ and kf ₂ : frequency constant (sound speed of vibrator), f ₁ : excitation frequency, ω ₁ : thickness in the X-axis direction, f ₂ : detection frequency, ω ₂ : thickness in the Z-axis direction, l: Here, kf ₁ and kf ₂ are extremely close values (kf ₁ ｋkf ₂ ).
[0006]
However, the interval between the two legs in the piezoelectric vibration type inertial sensor element is very narrow, for example, about 0.5 mm as shown in a schematic perspective view of FIG. When there is a measurement error of, for example, 1 μm when actually measuring the thickness of the piezoelectric vibration type inertial sensor element in the X-axis direction and the thickness in the Z-axis direction, a deviation between the excitation frequency and the detection frequency of about several tens Hz is generated. As a result, there is a problem that the value of Δf, which is the difference between the two frequencies, which is a value that significantly affects the sensitivity of the piezoelectric vibrating inertial sensor element using the tuning fork vibrator described above, greatly fluctuates. Was.
[0007]
In addition, making the excitation frequency and the detection frequency very close (f ₁ ｆf ₂ ) can improve the sensitivity by improving the resonance Q value between them, but when f ₁ = f ₂ , both vibrations become higher. The mode degenerates, making it impossible to obtain sensitivity. To maintain the sensitivity of a piezoelectric vibrating inertial sensor element using a tuning fork vibrator as high as possible and to accurately control the above-mentioned Δf so that degeneration does not occur, a piezoelectric vibrating inertial sensor element is required. It is necessary to accurately adjust the thickness ω _{1 in} the X-axis direction and the thickness ω ₂ in the Z-axis direction.
[Patent Document 1]
JP-A-49-10691 [Patent Document 2]
JP-A-11-325911
The applicant has not found any prior art documents related to the present invention other than the prior art documents specified by the above-mentioned prior art document information by the time of filing the present application.
[Problems to be solved by the invention]
[0009]
The present invention has been made in view of the technical background as described above, and accordingly, has as its object to provide a method of adjusting the frequency of a piezoelectric vibration type inertial sensor element and a piezoelectric vibration type inertial sensor element. That is.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to a piezoelectric vibration type inertial sensor element using a tuning fork type vibrator having at least two legs projecting from a base parallel to a Y axis. The width of the leg of the crystal in the direction along the X axis is smaller than the thickness of the leg in the direction of the crystal along the Z axis.
[0011]
Further, in the frequency adjusting method of the piezoelectric vibration type inertial sensor element using the tuning fork type vibrator having at least two legs protruding from the base in parallel with the Y axis, an electrode is provided and a frequency measuring device connected to the electrode is provided. The frequency is adjusted by etching the portions other than the electrodes while measuring the frequency.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Note that the same reference numerals in each drawing indicate the same objects. However, the following description is merely an exemplification of the present invention, and the technical scope of the present invention is not limited by the following description.
[0013]
FIG. 1 is a schematic perspective view of a piezoelectric vibration type inertial sensor element 3 according to the present invention in which an electrode 8 is formed on a leg 2 by vapor deposition. Conventionally, as shown in FIG. 5, the electrode 8 is deposited on the leg 2 of the piezoelectric vibration type inertial sensor element 3 after the piezoelectric vibration type inertial sensor element 3 is formed. The thickness T1 of the element in the electrode part of the leg part 2 of No. 3 was equal to the thickness T2 of the element around the electrode part. As shown in the schematic perspective view of FIG. 3, the piezoelectric vibration type inertial sensor element is very small, and the thickness of the piezoelectric vibration type inertial sensor element using the tuning fork type vibrator in the X-axis direction and the Z-axis direction When there is a measurement error of, for example, 1 μm in the actual measurement of the thickness of the piezoelectric vibrator, a deviation between the excitation frequency and the detection frequency of about several tens Hz occurs, and as a result, the piezoelectric vibration using the tuning fork vibrator described above occurs. There is a problem in that the value of Δf, which is the difference between the two frequencies, which significantly affects the sensitivity of the inertial sensor element, greatly fluctuates. In this embodiment, as shown in FIG. 1, a metal such as gold (Au) which is not affected by an etchant in the legs 2 of the piezoelectric vibration type inertial sensor element 3 is vapor-deposited on the electrode 8 in advance. The dimensions of the piezoelectric vibration type inertial sensor element 3 are processed by performing wet etching or the like while the frequency measuring device is connected to. Therefore, since the processing is performed while measuring the frequency with the frequency measuring device, it is possible to perform the processing for obtaining the frequency difference that maximizes the sensitivity of the piezoelectric vibration type inertial sensor element.
[0014]
FIG. 2 is a schematic side view of the piezoelectric vibrating inertial sensor element 3 in which the electrode 8 is deposited on the leg 2 when the present invention is viewed from the X-axis direction. Since the etching of the portion on which the electrode 8 is deposited does not progress, in the piezoelectric vibration type inertial sensor element 3 using the frequency adjustment method of the present invention, the thickness T1 of the electrode portion in the leg portion 2 of the element is the thickness T1 around the electrode portion. It becomes larger than the thickness T2 of the element. Note that not all electrodes of the piezoelectric vibration type inertial sensor element are illustrated in FIGS. 1 and 2, and are schematic diagrams illustrating a part of the electrodes.
[0015]
FIG. 3 is a schematic perspective view of a piezoelectric vibration type inertial sensor element according to the present invention in a state where electrodes are not deposited on the legs. FIG. 4 is a view as seen from above. In the present invention, the width W of the leg 2 of the piezoelectric vibration type inertial sensor element 3 in the direction along the X axis of the crystal is smaller than the thickness T of the leg 2 in the direction along the Z axis of the crystal. In the piezoelectric vibration type inertial sensor element 3 of the present invention, when the frequency is adjusted using wet etching or the like, the degree of progress of the etching (etching rate) in the thickness direction along the Z axis depends on the anisotropy of the crystal. Since it is larger than the axial direction, adjustment by processing such as wet etching can be performed efficiently.
[0016]
In dry etching or ion beam etching, the above-described selective etching can be performed in a similar manner.
[0017]
In the drawings in the embodiment, an example using a two-legged tuning fork vibrator is shown. However, the present invention is not limited to the two-legged one and may be a three-legged or four-legged one. Advantageously, it is needless to say that these cases are also included in the technical scope of the present invention.
[0018]
【The invention's effect】
According to the present invention, it is possible to obtain a piezoelectric vibration type inertial sensor element having good sensitivity and high accuracy.
[0019]
Further, according to the present invention, the piezoelectric vibration type inertial sensor element can be efficiently processed by wet etching or the like, and the production yield of the piezoelectric vibration type inertial sensor element can be significantly increased.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a piezoelectric vibration type inertial sensor element according to the present invention in which electrodes are deposited on legs.
FIG. 2 is a schematic side view of a piezoelectric vibration type inertial sensor element in which an electrode is deposited on a leg, when the present invention is viewed from the X-axis direction.
FIG. 3 is a schematic perspective view of a piezoelectric vibrating inertial sensor element according to the present invention in which electrodes are not deposited on legs.
FIG. 4 is a schematic top view of the leg of the piezoelectric vibratory inertial sensor element with no electrode deposited on the leg according to the present invention.
FIG. 5 is a schematic side view of a conventional piezoelectric vibrating inertial sensor element having electrodes deposited on legs, as viewed from the X-axis direction.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base 2 Leg 3 Piezoelectric vibration type inertial sensor element 4 Leg width W
5 Leg thickness T
6 Thickness of element of electrode part T1
7 Thickness of element around electrode part T2
8 electrodes

Claims (2)

A piezoelectric vibrating inertial sensor element using a quartz tuning fork vibrator having at least two legs protruding from a base parallel to the Y axis,
A piezoelectric vibratory inertial sensor element, wherein the width of the leg of the piezoelectric vibratory inertial sensor element in the direction along the X axis of the crystal is smaller than the thickness of the leg in the direction of the crystal along the Z axis. In a frequency adjustment method of a piezoelectric vibrating inertial sensor element using a quartz tuning fork vibrator having at least two legs protruding from a base parallel to a Y axis,
A frequency adjustment method for a piezoelectric vibration type inertial sensor element, characterized in that a frequency is adjusted by etching a portion other than the electrode while measuring a frequency with a frequency measuring device connected to the electrode.

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