JP2008118264A - Tuning fork vibrator and manufacturing method thereof - Google Patents

Abstract

A tuning fork vibrator capable of suppressing deterioration is provided.
A tuning fork vibrator 100 according to the present invention includes a base 1, a tuning fork type vibration part 10 composed of at least a part of the base, a drive part 20 that generates bending vibration of the vibration part, A porous layer 80 formed above and not in contact with the driving unit; a cavity 72 formed between the driving unit and the porous layer; and a sealing layer 90 formed above the porous layer. The vibrating section includes a support section 12 and two beam sections 14a formed in a cantilever shape with the support section as a base end, and the drive section is paired above each beam section. Each of the drive units formed includes a first electrode 22, a piezoelectric layer 24 formed above the first electrode, and a second electrode 26 formed above the piezoelectric layer.
[Selection] Figure 2

Description

  The present invention relates to a tuning fork vibrator and a manufacturing method thereof.

Generally, in information equipment such as a clock and a microcomputer, a tuning fork vibrator is used as an oscillator part of a clock module. For the tuning fork vibrator, a system driven by a piezoelectric effect is widely used. Recently, a tuning fork vibrator having a drive unit in which a piezoelectric thin film is sandwiched between upper and lower electrodes on a silicon substrate has been developed (see, for example, Patent Document 1). In this tuning fork vibrator, moisture in the atmosphere may adversely affect the drive unit, and the tuning fork vibrator may deteriorate.
JP 2005-249395 A

  An object of the present invention is to provide a tuning fork vibrator capable of suppressing deterioration and a manufacturing method thereof.

The tuning fork vibrator according to the present invention is
A substrate;
A tuning-fork type vibration part comprising at least a part of the base;
A drive unit that generates bending vibration of the vibration unit;
A porous layer formed above the substrate and not in contact with the drive unit;
A cavity formed between the drive unit and the porous layer;
A sealing layer formed above the porous layer,
The vibrating part is
A support part;
Two beam portions formed in a cantilever shape with the support portion as a base end, and
The drive unit is formed in a pair above each beam unit,
Each said drive part is
A first electrode;
A piezoelectric layer formed above the first electrode;
A second electrode formed above the piezoelectric layer.

  In the tuning fork vibrator according to the present invention, the drive unit is provided in the hollow portion sealed by the porous layer and the sealing layer, and does not come into contact with outside air. For this reason, deterioration of the piezoelectric layer of the driving unit can be suppressed. As a result, deterioration of the tuning fork vibrator can be suppressed.

  In the description according to the present invention, the word “upward” refers to, for example, “another specific thing (hereinafter referred to as“ B ”) formed“ above ”a specific thing (hereinafter referred to as“ A ”)”. Etc. In the description of the present invention, in the case of this example, there are a case where B is directly formed on A and a case where B is formed on A via another. The word “above” is used as included.

In the tuning fork vibrator according to the present invention,
The substrate may be an SOI (Silicon On Insulator) substrate.

In the tuning fork vibrator according to the present invention,
The porous layer may be made of a metal oxide.

In the tuning fork vibrator according to the present invention,
The porous layer can be made of aluminum oxide.

In the tuning fork vibrator according to the present invention,
The sealing layer can be made of silicon nitride.

In the tuning fork vibrator according to the present invention,
The inside of the hollow portion may be at a pressure lower than atmospheric pressure.

A method for manufacturing a tuning fork vibrator according to the present invention includes:
Providing a substrate, a base having an insulating layer formed above the substrate, and a semiconductor layer formed above the insulating layer;
Forming a drive unit above the substrate;
Patterning the semiconductor layer to form a vibrating portion;
Patterning the insulating layer to form an opening below the vibrating portion;
Forming a sacrificial layer covering the driving unit;
Forming a porous layer covering the sacrificial layer;
Supplying a gas through the pores of the porous layer and reacting with the sacrificial layer to gasify and remove the sacrificial layer;
Forming a sealing layer covering the porous layer, and
The step of forming the driving unit includes:
Forming a first electrode above the substrate;
Forming a piezoelectric layer above the first electrode;
Forming a second electrode above the piezoelectric layer,
The vibrating part is
A support part;
Two beam portions formed in a cantilever shape with the support portion as a base end, and
One pair of the drive units is formed above each beam unit.

In the method for manufacturing a tuning fork vibrator according to the present invention,
The sacrificial layer is a resist layer;
In the step of removing the sacrificial layer, the resist layer may be removed by ashing.

In the method for manufacturing a tuning fork vibrator according to the present invention,
In the step of forming the sealing layer, the sealing layer may be formed under a pressure lower than atmospheric pressure.

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

  1. First, the tuning fork vibrator 100 according to the present embodiment will be described. FIG. 1 is a plan view schematically showing a tuning fork vibrator 100 according to this embodiment, and FIG. 2 is a cross-sectional view schematically showing the tuning fork vibrator 100. 2 is a cross-sectional view taken along the line II-II in FIG.

  As shown in FIGS. 1 and 2, the tuning fork vibrator 100 includes a base body 1, a vibrating unit 10, a driving unit 20 (20 a to 20 d), a porous layer 80, a cavity 72, and a sealing layer 90. And including. In FIG. 1, for the sake of convenience, the porous layer 80 and the sealing layer 90 are seen through.

  For example, as shown in FIG. 2, the base 1 can include a substrate 2, an insulating layer 3 formed on the substrate 2, and a semiconductor layer 4 formed on the insulating layer 3. As the substrate 1, for example, an SOI substrate can be used. Examples of the SOI substrate include a SIMOX (silicon implanted oxide) substrate and a bonded SOI substrate. For example, a silicon substrate can be used as the substrate 2, a silicon oxide layer can be used as the insulating layer 3, and a silicon layer can be used as the semiconductor layer 4. The thickness of the semiconductor layer 4 is desirably 20 μm or less in order to reduce the size of the tuning fork vibrator 100. Various semiconductor circuits can be formed in the semiconductor layer 4. The use of a silicon layer as the semiconductor layer 4 is advantageous in that a general semiconductor manufacturing technique can be used.

  The vibration unit 10 is composed of at least a part of the base body 1. The planar shape of the vibration part 10 is a tuning fork type as shown in FIG. As shown in FIG. 2, the vibrating portion 10 is formed on an opening 3 a formed by removing a part of the insulating layer 3 of the base 1. A gap 4 a that allows vibration of the vibration unit 10 is formed around the vibration unit 10. The vibration part 10 includes a support part 12 and two beam parts 14 (14a, 14b) formed in a cantilever shape with the support part 12 as a base end. The first beam portion 14a and the second beam portion 14b are arranged at a predetermined interval in parallel to the longitudinal direction (X direction in FIG. 1).

  The support part 12 includes a first support part 12a made of a part of the semiconductor layer 4, and a second support part 12b having a width wider than the first support part 12a. The first support portion 12a is continuous with the fixed portion 4b formed of a part of the semiconductor layer 4, and connects the fixed portion 4b and the second support portion 12b. The second support portion 12b has a function of supporting the first beam portion 14a and the second beam portion 14b and a function of not propagating vibrations of these beam portions 14a and 14b to the first support portion 12a. For example, as shown in FIG. 1, the second support portion 12 b can have an uneven shape on the side portion.

  The drive unit 20 (20a to 20d) generates bending vibration of the vibration unit 10. As shown in FIG. 1, the drive unit 20 is formed in pairs on the first beam unit 14a and the second beam unit 14b. That is, on the first beam portion 14a, the first drive portion 20a and the second drive portion 20b are formed in parallel to each other along the longitudinal direction of the first beam portion 14a. Similarly, a third drive unit 20c and a fourth drive unit 20d are formed in parallel to each other along the longitudinal direction of the second beam unit 14b on the second beam unit 14b. The first driving unit 20a arranged outside the first beam unit 14a and the third driving unit 20c arranged outside the second beam unit 14b are electrically connected by wiring (not shown). Yes. The second drive unit 20b arranged inside the first beam unit 14a and the fourth drive unit 20d arranged inside the second beam unit 14b are electrically connected by wiring (not shown). Yes.

  As shown in FIG. 2, the drive unit 20 (20a to 20d) includes a first electrode 22 formed above the beam units 14a and 14b, a piezoelectric layer 24 formed on the first electrode 22, and a piezoelectric element. And a second electrode 26 formed on the body layer 24. The driving unit 20 can further include an underlayer 5 formed between the beam units 14 a and 14 b and the first electrode 22.

The underlayer 5 is an insulating layer such as a silicon oxide (SiO ₂ ) layer or a silicon nitride (Si ₃ N ₄ ) layer. The underlayer 5 may be composed of two or more composite layers, for example.

  The first electrode 22 can be made of an electrode material such as Pt, for example. The thickness of the 1st electrode 22 should just be the thickness from which a sufficiently low electrical resistance value is acquired, for example, can be 10 nm or more and 5 micrometers or less.

  The piezoelectric layer 24 can be made of a piezoelectric material such as lead zirconate titanate (PZT). The thickness of the piezoelectric layer 24 is desirably about 1/10 times or more and equal to or less than the thickness of the semiconductor layer 4. When the thickness is within this range, it is possible to secure a driving force that sufficiently vibrates the beam portions 14a and 14b. For example, when the thickness of the semiconductor layer 4 is 1 μm to 20 μm, the thickness of the piezoelectric layer 24 can be 0.1 μm to 20 μm.

  The second electrode 26 can be made of an electrode material such as Pt, for example. The thickness of the second electrode 26 may be any thickness that provides a sufficiently low electrical resistance value, and may be, for example, 10 nm or more and 5 μm or less.

  In the illustrated example, in the drive unit 20, only the piezoelectric layer 24 exists between the first electrode 22 and the second electrode 26, but a layer other than the piezoelectric layer 24 is provided between the electrodes 22 and 26. You may have. The film thickness of the piezoelectric layer 24 can be appropriately changed according to the resonance condition.

  In the tuning fork vibrator 100 according to the present embodiment, by applying an alternating electric field to the first to fourth drive units 20a to 20d, the first and second beams 14a and 14b bend and vibrate in a mirror-symmetric manner, respectively. Vibration can be realized.

  As shown in FIG. 2, the porous layer 80 is formed on the substrate 1 and is not in contact with the drive unit 20. The shape of the porous layer 80 reflects the shape of the sacrificial layer 70 described later. A cavity 72 is formed inside the porous layer 80. The drive unit 20 is formed inside the cavity 72. That is, the cavity 72 is formed between the drive unit 20 and the porous layer 80.

The porous layer 80 has a large number of fine through holes. Gas can move through the through hole. As the porous layer 80, it is desirable to have a high mechanical strength and to maintain its shape independently. The thickness of the porous layer 80 is, for example, about 0.2 μm to 2 μm. As the porous layer 80, a material that becomes porous when it is formed and has high mechanical strength can be used. The porous layer 80 can be made of an oxide, nitride, organic material, or the like. The porous layer 80 is preferably made of a metal oxide, more preferably aluminum oxide (Al ₂ O ₃ ).

The sealing layer 90 is formed on the porous layer 80 as shown in FIG. The sealing layer 90 can seal the through hole of the porous layer 80 to keep the cavity 72 airtight, and can reinforce the mechanical strength of the porous layer 80. As will be described later, since the sealing layer 90 is formed under a pressure lower than the atmospheric pressure, when the tuning fork vibrator 100 is placed in the atmosphere, the cavity 72 is in a negative pressure state. According to the tuning fork vibrator 100 of the present embodiment, since the porous layer 80 and the sealing layer 90 have high mechanical strength, the shape of the cavity 72 can be maintained even when the cavity 72 is in a negative pressure state. The thickness of the sealing layer 90 is, for example, about 0.1 μm to 1.5 μm. The sealing layer 90 is made of a dense material that can maintain the airtightness of the cavity 72. The sealing layer 90 can be made of silicon nitride (Si ₃ N ₄ ), silicon oxide, aluminum oxide, or the like.

  2. Next, an example of a method for manufacturing the tuning fork vibrator 100 according to the present embodiment will be described with reference to the drawings. 3 to 8 are cross-sectional views schematically showing one manufacturing process of the tuning fork vibrator 100 of the present embodiment shown in FIGS. 1 and 2, each corresponding to the cross-sectional view shown in FIG.

  (1) First, as shown in FIG. 3, a base 1 in which an insulating layer 3 and a semiconductor layer 4 are arranged in this order on a substrate 2 is prepared.

  (2) Next, the drive unit 20 is formed on the substrate 1. Specifically, the base layer 5, the first electrode 22, the piezoelectric layer 24, and the second electrode 26 constituting the driving unit 20 are sequentially formed on the base 1.

  The underlayer 5 is formed by a thermal oxidation method, a CVD method, a sputtering method, or the like. The underlayer 5 can be formed into a desired shape by patterning using, for example, a photolithography technique and an etching technique.

  The first electrode 22 is formed by vapor deposition, sputtering, or the like. The first electrode 22 can be formed into a desired shape by patterning using, for example, a photolithography technique and an etching technique.

The piezoelectric layer 24 is formed by laser ablation, vapor deposition, sputtering, CVD (Chemical Vapor Deposition), or the like. For example, when the piezoelectric layer 24 made of lead zirconate titanate (PZT) is formed by laser ablation, laser light is used as a target for PZT, for example, Pb _1.05 Zr _0.52 Ti _0.48 NbO. ₃ target is irradiated. Then, lead atoms, zirconium atoms, titanium atoms, and oxygen atoms are released from the target by ablation, a plume is generated by laser energy, and the plume is irradiated toward the substrate 1. Thereby, the piezoelectric layer 24 made of PZT is formed on the first electrode 22. The piezoelectric layer 24 can be formed into a desired shape by patterning using, for example, a photolithography technique and an etching technique.

  The second electrode 26 is formed by vapor deposition, sputtering, CVD, or the like. The second electrode 26 can be formed into a desired shape by patterning using, for example, a photolithography technique and an etching technique.

  (3) Next, as shown in FIG. 4, the vibration layer 10 is formed by patterning the semiconductor layer 4 of the substrate 1 into a desired shape. The vibration part 10 is obtained by penetrating the semiconductor layer 4 to form a gap 4a (see FIG. 1). The semiconductor layer 4 is patterned using a photolithography technique and an etching technique. As an etching technique, a dry etching method or a wet etching method can be used. In this patterning step, the insulating layer 3 of the substrate 1 can be used as an etching stopper layer.

  (4) Next, as shown in FIG. 5, the insulating layer 3 of the base 1 is patterned to form an opening 3 a under the vibrating part 10. When the insulating layer 3 is made of silicon oxide, the insulating layer 3 can be patterned by wet etching using, for example, hydrofluoric acid. In this patterning step, for example, the insulating layer 3 can be patterned without using a photolithography technique by using the substrate 2 and the semiconductor layer 4 as an etching stopper layer.

  (5) By providing the gap 4a and the opening 3a by the above-described steps, the mechanical restraint force on the tuning-fork type vibration unit 10 is reduced, and the vibration unit 10 can sufficiently vibrate.

  (6) Next, as shown in FIG. 6, a sacrificial layer 70 that covers the drive unit 20 is formed. Specifically, first, a sacrificial layer 70 is provided on the entire surface of the base 1 so as to cover the drive unit 20. The sacrificial layer 70 can be made of, for example, an organic resist material. Next, using a photolithography technique, the sacrificial layer 70 is patterned as shown in FIG. The shape of the patterned sacrificial layer 70 is reflected in the shape of the porous layer 80 formed in the next step. Therefore, in order to prevent the porous layer 80 from coming into contact with the driving unit 20, the sacrificial layer 70 is provided so that the driving unit 20 is entirely buried. Further, as shown in FIG. 6, the sacrificial layer 70 can embed the gap 4a and the opening 3a (see FIG. 5). Note that the sacrificial layer 70 does not have to fill the gap 4a and the opening 3a.

  (7) Next, as shown in FIG. 7, a porous layer 80 that covers the sacrificial layer 70 is formed. The porous layer 80 is formed along the surface of the sacrificial layer 70. The porous layer 80 is formed using, for example, a CVD method or a sputtering method. For example, when an aluminum oxide layer is used as the porous layer 80, it is preferable to use a CVD method for forming the porous layer 80. In this case, a suitable porous layer is obtained by using trimethylaluminum as a raw material, adjusting spraying of the raw material, introducing ozone into the reaction furnace, and repeating thermal oxidation at 400 ° C. or lower (eg, 200 ° C.). 80 can be formed. The formation method and formation conditions of the porous layer 80 can be changed as appropriate according to the material of the porous layer 80 and the like.

  (8) Next, as shown in FIG. 8, a gas (for example, plasma) is supplied through the pores of the porous layer 80 to react with the sacrificial layer 70, and the sacrificial layer 70 is gasified and removed. When a resist layer is used as the sacrificial layer 70, the sacrificial layer 70 is removed by, for example, ashing using oxygen plasma. Specifically, first, oxygen gas is introduced into the chamber, and the oxygen gas is turned into plasma by a known method. The pressure in the chamber is, for example, about 200 Pa to 300 Pa. The generated oxygen plasma (gas) passes through the through hole of the porous layer 80 and reacts with the sacrificial layer 70 inside the porous layer 80. The resulting gas passes through the through hole of the porous layer 80 and is released to the outside. The substrate temperature in this step can be about 200 ° C., for example, and the processing time can be about 10 minutes, for example. In this step, the gas to be reacted with the sacrificial layer 70 is not limited to oxygen plasma, and any gas that can remove the sacrificial layer 70 may be used.

  By removing the sacrificial layer 70 as described above, the cavity 72 can be formed inside the porous layer 80 while maintaining the shape of the porous layer 80 as shown in FIG.

  (9) Next, as shown in FIGS. 1 and 2, a sealing layer 90 that covers the porous layer 80 is formed. The sealing layer 90 is formed along the surface of the porous layer 80. The sealing layer 90 is formed using, for example, a sputtering method or a CVD method. The sealing layer 90 is formed under a pressure lower than atmospheric pressure. For this reason, the inside of the cavity 72 is sealed with a pressure (vacuum state) lower than the atmospheric pressure. The film forming conditions of the sealing layer 90 are appropriately set so that the sealing layer 90 has a denseness capable of maintaining the airtightness of the cavity 72. In the manufacturing method of the present embodiment, for example, the process from the formation of the porous layer 80 to the formation of the sealing layer 90 can be performed consistently in a vacuum apparatus.

  (10) Through the above steps, the tuning fork vibrator 100 of this embodiment is formed as shown in FIGS.

  3. In the tuning fork vibrator 100 of the present embodiment, the drive unit 20 is provided in the cavity 72 sealed by the porous layer 80 and the sealing layer 90 and does not come into contact with the outside air. For this reason, deterioration of the piezoelectric layer 24 of the drive unit 20 can be suppressed. As a result, the deterioration of the tuning fork vibrator 100 can be suppressed.

  Further, in the tuning fork vibrator 100 of the present embodiment, the cavity 72 is in a reduced pressure state, and there are few substances (for example, moisture) that adversely affect the piezoelectric layer 24 in the cavity 72. For this reason, deterioration of the tuning fork vibrator 100 can be further suppressed.

  Moreover, in the manufacturing method of the tuning fork vibrator 100 of this embodiment, the structure for sealing the drive part 20 can be formed consistently in a vacuum apparatus. For this reason, it is possible to prevent the drive unit 20 from coming into contact with the atmosphere in the formation process of the structure. Therefore, according to the manufacturing method of the present embodiment, the tuning fork vibrator 100 can be manufactured under a condition where there are few substances (for example, moisture) that adversely affect the piezoelectric layer 24 of the driving unit 20.

  Further, according to the method for manufacturing the tuning fork vibrator 100 of the present embodiment, the cavity 72 can be obtained in the vacuum apparatus, so that the cavity 72 can be in a reduced pressure state without any other special process. Can do.

Further, in the tuning fork vibrator 100 of the present embodiment, since the vibration unit 10 is configured by the semiconductor layer 4 of the base 1 (for example, an SOI substrate), the thickness of the vibration unit 10 can be reduced. Thereby, in the tuning fork vibrator 100 that generates the resonance frequency of the oscillator used in the clock module, the length of the vibrating section 10 (more specifically, the beam sections 14a and 14b) can be shortened. That is, for example, the tuning fork vibrator 100 according to the present embodiment can be downsized as compared with a tuning fork vibrator using quartz. For example, when a resonance frequency in the 32 kHz band is used, the thickness of the vibration part 10 can be 20 μm or less, the length of the vibration part 10 can be 2 mm or less, and the package length of the tuning fork vibrator 100 can be 3 mm or less. The resonance frequency in the 32 kHz band is, for example, in the range of 16 kHz to 66 kHz. This requires 2 ¹⁵ = 32.768 kHz in order to generate a signal of 1 Hz by dividing by a 15-stage flip-flop circuit, but 14 and 16 stages are also possible from the viewpoint of power consumption. Therefore, the range from 2 ¹⁴ = 16.384 kHz to 2 ¹⁶ = 65.536 kHz can be set.

  A specific example of the tuning fork vibrator 100 according to this embodiment is as follows. For example, the thickness of the first electrode 22 is 0.1 μm, the thickness of the piezoelectric layer 24 is 1 μm, the thickness of the second electrode 26 is 0.1 μm, the thickness of the driving unit 20 is 1.2 μm, and the thickness of the semiconductor layer 4 is 2 μm. The beam lengths of the beam portions 14a and 14b are 410 μm and the beam width is 4 μm. The vibration part 10 is contained in the gap 4a having a long side of 1 mm and a short side of 10 μm. When the tuning fork vibrator 100 having this configuration was simulated by solving the equation of motion by the finite element method, the resonance frequency of the bending vibration was 32 kHz.

  Note that the tuning fork vibrator 100 according to the present embodiment can be used as a trigger generator even in a circuit that originally does not require a timing device such as an asynchronous circuit.

  In the tuning fork vibrator 100 according to the present embodiment, a tuning fork vibrator module can be formed by using an SOI substrate as the base 1 and mounting the semiconductor integrated circuit and the tuning fork vibrator 100 on the insulating layer 3. Thereby, a module package can be reduced in size.

  Further, in the tuning fork vibrator 100 of the present embodiment, an oscillation circuit and the tuning fork vibrator 100 can be mounted on the insulating layer 3 by using an SOI substrate as the base 1. In a device using an SOI substrate, the operating voltage can be lowered. Therefore, according to the tuning fork vibrator 100 of this embodiment, a one-chip clock module with low power consumption can be provided.

  4). Although the embodiments of the present invention have been described in detail as described above, those skilled in the art will readily understand that many modifications are possible without substantially departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention.

FIG. 2 is a plan view schematically showing a tuning fork vibrator according to the embodiment. FIG. 3 is a cross-sectional view schematically showing a tuning fork vibrator according to the embodiment. Sectional drawing which shows roughly one manufacturing process of the tuning fork vibrator of this embodiment. Sectional drawing which shows roughly one manufacturing process of the tuning fork vibrator of this embodiment. Sectional drawing which shows roughly one manufacturing process of the tuning fork vibrator of this embodiment. Sectional drawing which shows roughly one manufacturing process of the tuning fork vibrator of this embodiment. Sectional drawing which shows roughly one manufacturing process of the tuning fork vibrator of this embodiment. Sectional drawing which shows roughly one manufacturing process of the tuning fork vibrator of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base | substrate, 2 Substrate, 3 Insulating layer, 4 Semiconductor layer, 5 Underlayer, 10 Vibration part, 12 Support part, 14 Beam part, 20 Driving part, 22 1st electrode, 24 Piezoelectric layer, 26 2nd electrode, 70 Sacrificial layer, 72 cavity, 80 porous layer, 90 sealing layer, 100 tuning fork vibrator

Claims (9)

A substrate;
A tuning-fork type vibration part comprising at least a part of the base;
A drive unit that generates bending vibration of the vibration unit;
A porous layer formed above the substrate and not in contact with the drive unit;
A cavity formed between the drive unit and the porous layer;
A sealing layer formed above the porous layer,
The vibrating part is
A support part;
Two beam portions formed in a cantilever shape with the support portion as a base end, and
The drive unit is formed in a pair above each beam unit,
Each said drive part is
A first electrode;
A piezoelectric layer formed above the first electrode;
A tuning fork vibrator having a second electrode formed above the piezoelectric layer. In claim 1,
The base is a tuning fork vibrator, which is an SOI (Silicon On Insulator) substrate. In claim 1 or 2,
The porous layer is a tuning fork vibrator made of a metal oxide. In any one of Claims 1 thru | or 3,
The porous layer is a tuning fork vibrator made of aluminum oxide. In any one of Claims 1 thru | or 4,
The sealing layer is a tuning fork vibrator made of silicon nitride. In any one of Claims 1 thru | or 5,
A tuning fork vibrator having a pressure smaller than atmospheric pressure in the hollow portion. Providing a substrate, a base having an insulating layer formed above the substrate, and a semiconductor layer formed above the insulating layer;
Forming a drive unit above the substrate;
Patterning the semiconductor layer to form a vibrating portion;
Patterning the insulating layer to form an opening below the vibrating portion;
Forming a sacrificial layer covering the driving unit;
Forming a porous layer covering the sacrificial layer;
Supplying a gas through the pores of the porous layer and reacting with the sacrificial layer to gasify and remove the sacrificial layer;
Forming a sealing layer covering the porous layer, and
The step of forming the driving unit includes:
Forming a first electrode above the substrate;
Forming a piezoelectric layer above the first electrode;
Forming a second electrode above the piezoelectric layer,
The vibrating part is
A support part;
Two beam portions formed in a cantilever shape with the support portion as a base end, and
A method of manufacturing a tuning fork vibrator, wherein the drive unit is formed in a pair above each beam unit. In claim 7,
The sacrificial layer is a resist layer;
A method for manufacturing a tuning fork vibrator, wherein in the step of removing the sacrificial layer, the resist layer is removed by ashing. In claim 7 or 8,
The method for manufacturing a tuning fork vibrator, wherein in the step of forming the sealing layer, the sealing layer is formed under a pressure lower than atmospheric pressure.

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