JP5618078B2 - Method for manufacturing piezoelectric vibrating piece - Google Patents

Description

  The present invention relates to a method for manufacturing a piezoelectric vibrating piece.

  As a method for confining energy of main vibration in a piezoelectric vibrating piece having thickness shear vibration as main vibration, a method of processing a piezoelectric substrate into a shape such as a bevel or mesa is known.

  For example, Patent Document 1 discloses a piezoelectric vibrating piece that can efficiently confine energy of main vibration by using multiple mesas.

  Such a piezoelectric vibrating piece is generally formed by processing a substrate made of a piezoelectric material such as quartz by machining or photolithography.

  In Patent Document 2, patterning on a photoresist layer formed on a quartz substrate is performed in separate steps on the front surface side and the back surface side, and patterning on the front surface side and the back surface side is performed using the same exposure lens. There is disclosed a method for manufacturing a piezoelectric vibrator capable of accurately patterning the outer shape of the piezoelectric vibrator and the shape of the groove. Patent Document 1 discloses a technique for performing patterning of an outer shape and a groove shape by using the same photoresist layer.

  In Patent Document 3, the metal film exposed by the first patterning of the photoresist layer is not completely removed, but only the surface layer metal film is removed to leave the base layer metal film. A method for manufacturing a vibrator is disclosed in which the film can be patterned again without changing the quality of the remaining photoresist film. Thereby, the vibrator having the concave portion can be manufactured by a simple process.

  In Patent Document 4, a photoresist film formed first is used as it is without peeling off, and a new photo is produced during the manufacturing process by processing the outer shape of the piezoelectric vibrating piece and the recessed shape of the vibrating portion. There has been disclosed a technique capable of simplifying the manufacturing process and improving work efficiency without the need to form and peel a resist film. In Patent Document 4, the surface layer of the photoresist film remaining after the first patterning is removed by dry etching using oxygen plasma, so that the photoresist film formed first is used as it is without being peeled off.

  In Patent Document 5, by using the same photoresist film for forming the outer shape of the piezoelectric vibrating piece and forming the shape of the central portion, it is not necessary to form and peel off a new photoresist film, thereby simplifying the process. A technique that can be realized is disclosed. In Patent Document 5, for a photoresist film that has been exposed to an etching solution and has a reduced sensitivity, the exposure time is made longer than usual or the exposure power is made higher than usual to compensate for the reduced sensitivity of the photoresist film. ing. Further, the sensitivity of the photoresist film is restored to its original state by removing the surface layer of the photoresist film formed by being exposed to the etching solution with an alkaline solution such as a developer.

  In the manufacturing process of the piezoelectric vibrating piece, as an apparatus used for the photolithography method, for example, an exposure apparatus disclosed in Patent Documents 6 to 7 can be used.

Japanese Patent Laid-Open No. 02-57009 JP 2008-109648 A JP 2006-86925 A JP 2002-261557 A JP 2001-77647 A JP-A-7-220990 JP-A-57-153433

  As described in Patent Documents 2 to 5, in the manufacturing process of the piezoelectric vibrating piece, it is desirable that the number of steps of forming and peeling the photoresist film is small in order to increase the working efficiency. However, when the photoresist film is exposed to an etching solution, a surface layer may be formed and the sensitivity may be lowered. Therefore, for example, in the method of manufacturing a piezoelectric vibrating piece described in Patent Document 4, the surface layer of the photoresist film is removed by dry etching using oxygen plasma, and the photoresist film formed first is peeled off as it is. We are using without.

  By the way, in the manufacturing process of the piezoelectric vibrating piece having a multi-stage mesa structure, as disclosed in Patent Document 4, in order to use the photoresist film formed first without being peeled off, The process of removing the surface layer by dry etching using oxygen plasma must be repeated. However, when the surface layer of the photoresist film is repeatedly removed by dry etching using oxygen plasma, there is a problem that the corrosion resistant film used as a mask during the etching of the quartz substrate is seized.

  Therefore, in the manufacturing process of the piezoelectric vibrating piece having a multistage mesa structure, the technique disclosed in Patent Document 3 is not effective, and the work efficiency is high in the manufacturing process of the piezoelectric vibrating piece having a multistage mesa structure, There is a need for technology that can improve productivity.

  One of the objects according to some aspects of the present invention is a method of manufacturing a piezoelectric vibrating piece having a multi-stage mesa structure, and provides a method of manufacturing a piezoelectric vibrating piece having high work efficiency and improved productivity. There is.

A method for manufacturing a piezoelectric vibrating piece according to the present invention includes:
A method of manufacturing a piezoelectric vibrating piece having a multistage mesa structure on at least one main surface of a substrate,
Forming a corrosion-resistant film on the main surface of the substrate;
Forming a resist film on the surface of the corrosion-resistant film;
First exposing the resist film so as to correspond to the outer peripheral shape of the piezoelectric vibrating piece;
First developing the first exposed resist film;
Using the first developed resist film as a mask, first patterning the corrosion-resistant film so as to correspond to an outer peripheral shape of the piezoelectric vibrating piece;
A second exposure of the first developed resist film so as to correspond to the outer peripheral shape of the first-stage mesa portion;
Etching the substrate using the first patterned corrosion-resistant film as a mask to form an outer periphery of the piezoelectric vibrating piece;
Immersing the second exposed resist film in a stripping solution to remove the first surface layer of the resist film;
Second developing the resist film from which the first surface layer has been removed;
Using the second developed resist film as a mask, second patterning the corrosion-resistant film patterned first so as to correspond to the outer peripheral shape of the first-stage mesa portion;
Performing a third exposure on the second developed resist film so as to correspond to the outer peripheral shape of the second-stage mesa portion;
Etching the substrate halfway through the thickness of the substrate using the second patterned corrosion-resistant film as a mask, and forming an outer periphery of the first mesa portion;
Immersing the third exposed resist film in a stripping solution to remove the second surface layer of the resist film;
Third developing the resist film from which the second surface layer has been removed;
Using the third developed resist film as a mask, performing a third patterning on the second patterned corrosion-resistant film so as to correspond to an outer peripheral shape of the second-stage mesa portion;
Etching halfway through the thickness of the substrate using the third patterned corrosion-resistant film as a mask, and forming an outer periphery of the second-stage mesa portion;
including.

  According to such a method for manufacturing a piezoelectric vibrating piece, the resist film used to form the outer periphery (outer shape) of the piezoelectric vibrating piece is applied to the outer periphery of the first-stage mesa portion and the outer periphery of the second-step mesa portion. Can be used to form. This eliminates the need for film formation / peeling of the resist film for forming the outer periphery of the first-stage mesa portion and the outer periphery of the second-stage mesa portion, thereby reducing the steps of film formation / peeling of the resist film. . Therefore, work efficiency can be increased and productivity can be improved.

  Furthermore, according to such a method of manufacturing a piezoelectric vibrating piece, the resist film can be repeatedly exposed and developed by immersing it in a stripping solution and removing the surface layer of the resist film. For example, if the surface layer of the resist film is repeatedly removed by dry etching using oxygen plasma, the corrosion resistant film may be seized. According to the method for manufacturing a piezoelectric vibrating piece according to the present invention, such a problem does not occur because the surface layer of the resist film is removed by dipping in a stripping solution. Therefore, the resist film can be repeatedly exposed and developed.

In the method of manufacturing a piezoelectric vibrating piece according to the present invention,
The stripping solution may be an organic solution.

In the method of manufacturing a piezoelectric vibrating piece according to the present invention,
The stripping solution may be a solution containing N-methylpyrrolidone as a main component.

In the method of manufacturing a piezoelectric vibrating piece according to the present invention,
In the step of etching the substrate, the substrate may be etched with a solution containing hydrofluoric acid.

FIG. 3 is a plan view schematically showing the piezoelectric vibrating piece according to the first embodiment. FIG. 3 is a cross-sectional view schematically showing the piezoelectric vibrating piece according to the first embodiment. FIG. 3 is a cross-sectional view schematically showing the piezoelectric vibrating piece according to the first embodiment. 6 is a flowchart showing a manufacturing process of the piezoelectric vibrating piece according to the first embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric vibrating piece which concerns on 1st Embodiment. Chemical formula of material used as resist film. FIG. 6 is a plan view schematically showing a piezoelectric vibrating piece according to a second embodiment. Sectional drawing which shows typically the piezoelectric vibrating piece which concerns on 2nd Embodiment. Sectional drawing which shows typically the piezoelectric vibrating piece which concerns on 2nd Embodiment. The top view which shows typically the piezoelectric vibrating piece which concerns on 3rd Embodiment. Sectional drawing which shows typically the piezoelectric vibrating piece which concerns on 3rd Embodiment. The top view which shows typically the piezoelectric vibrating piece which concerns on 3rd Embodiment. Sectional drawing which shows typically the piezoelectric vibrating piece which concerns on 3rd Embodiment.

  Several embodiments of the present invention will be described below. The embodiments described below illustrate examples of the present invention. The present invention is not limited to the following embodiments at all, and includes various modifications that are carried out within the scope not changing the gist of the present invention. Note that not all of the configurations described in the following embodiments are indispensable constituent requirements of the present invention.

1. 1. First embodiment 1.1. First, the piezoelectric vibrating piece according to the first embodiment will be described with reference to the drawings. FIG. 1 is a plan view schematically showing a piezoelectric vibrating piece 100 according to the present embodiment. 2 and 3 are cross-sectional views schematically showing the piezoelectric vibrating piece 100. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG.

  As illustrated in FIGS. 1 to 3, the piezoelectric vibrating piece 100 can include a piezoelectric substrate 10 and an excitation electrode 20. The piezoelectric vibrating piece 100 has a multistage mesa structure.

  The piezoelectric substrate 10 is made of, for example, an AT cut quartz substrate. Piezoelectric materials such as quartz are generally trigonal and have crystal axes (X, Y, Z). The X axis is an electrical axis, the Y axis is a mechanical axis, and the Z axis is an optical axis. The AT-cut quartz substrate is a flat plate cut out from a piezoelectric material (for example, artificial quartz) along a plane obtained by rotating the XZ plane around the X axis by, for example, 35 ° 15 ′. The Y axis and the Z axis are also rotated around the X axis by 35 ° 15 ′ to be the Y ′ axis and the Z ′ axis, respectively. That is, the piezoelectric substrate 10 has an X-axis as a Y-axis centered on an X-axis of an orthogonal coordinate system including an X-axis as an electric axis, a Y-axis as a mechanical axis, and a Z-axis as an optical axis. The axis tilted in the Y direction is the Z ′ axis, the axis tilted in the + Z direction of the Z axis is the Y ′ axis, and is composed of planes parallel to the X axis and the Z ′ axis, and is parallel to the Y ′ axis. It consists of an AT-cut quartz substrate with a thickness in a certain direction. The AT-cut quartz substrate has a main surface (excitation surface) as an XZ ′ plane (surface including the X axis and Z ′ axis) orthogonal to the Y ′ axis, and can vibrate with thickness shear vibration as the main vibration. The piezoelectric substrate 10 can be obtained by processing the AT-cut quartz substrate. The piezoelectric substrate 10 is not limited to the AT cut crystal substrate, and may be another crystal substrate such as a BT cut crystal substrate.

  For example, as shown in FIG. 1, the piezoelectric substrate 10 has a rectangular shape in a plan view (as viewed from the direction perpendicular to the main surface). The piezoelectric substrate 10 has a peripheral part 12 and an excitation part 14.

  As shown in FIG. 1, the peripheral portion 12 is formed so as to surround the excitation portion 14 in a plan view. The thickness of the peripheral part 12 is smaller than the thickness of the excitation part 14.

  The excitation unit 14 has a two-stage mesa structure, and includes a first-stage first mesa section 14a and a second-stage second mesa section 14b. Since the excitation unit 14 has a multi-stage (two-stage) mesa structure, the coupling with the bending mode can be suppressed by the energy confinement effect. The first mesa unit 14 a and the second mesa unit 14 b are formed on both sides of the excitation unit 14. That is, the piezoelectric substrate 10 has a mesa structure on both main surfaces. The planar shape of the first mesa portion 14a and the second mesa portion 14b has a rectangular shape having a long side and a short side, as shown in FIG. As shown in FIG. 2, a step is formed between the short-side end surface 15a of the first mesa portion 14a and the short-side end surface 15b of the second mesa portion 14b. Further, the end surface 16a on the long side of the first mesa portion 14a and the end surface 16b on the long side of the second mesa portion 14b are located in one plane as shown in FIG. That is, no step is formed between the long side end surface 16a of the first mesa portion 14a and the long side end surface 16b of the second mesa portion 14b.

  Here, the piezoelectric vibrating piece 100 has a two-stage mesa structure, but the number of mesa stages is not particularly limited, and may be three or more.

  The planar shape of the peripheral part 12 is a rectangle as shown in FIG. The second mesa portion 14 b is formed inside the outer edge of the first mesa portion 14 a, and the first mesa portion 14 a is formed inside the outer edge of the peripheral portion 12.

  The excitation electrode 20 is formed in the excitation unit 14. As shown in FIGS. 2 and 3, the excitation electrode 20 is formed with the excitation unit 14 interposed therebetween. The excitation electrode 20 can apply a voltage to the excitation unit 14. By applying a voltage to the excitation unit 14, the excitation unit 14 can vibrate with thickness shear vibration as the main vibration. The excitation electrode 20 is connected to the pad 24 via the extraction electrode 22, for example. The pad 24 is electrically connected to, for example, an IC chip (not shown) for driving the piezoelectric vibrating piece 100. As the material of the excitation electrode 20, the extraction electrode 22, and the pad 24, for example, a material obtained by laminating chromium and gold in this order from the piezoelectric substrate 10 side can be used.

1.2. Next, a method for manufacturing a piezoelectric vibrating piece according to the first embodiment will be described. FIG. 4 is a flowchart showing a manufacturing process of the piezoelectric vibrating piece 100 according to this embodiment. 5 to 20 are cross-sectional views schematically showing the manufacturing process of the piezoelectric vibrating piece 100. 5 to 20 correspond to FIG.

  As shown in FIG. 5, a corrosion resistant film 30 is formed on the surface (main surface) of the substrate 101 (step S1). In the illustrated example, the corrosion resistant film 30 is formed on both the front and back surfaces of the substrate 101. The substrate 101 is a quartz substrate such as an AT cut quartz substrate. The corrosion resistant film 30 is formed by, for example, a sputtering method or a vacuum deposition method. The corrosion resistant film 30 has, for example, a laminated structure in which chromium and gold are laminated in this order. The corrosion-resistant film 30 has corrosion resistance against buffered hydrofluoric acid that becomes an etching solution when the substrate 101 is etched.

  As shown in FIG. 6, a resist film 40 is formed on the surface of the corrosion resistant film 30 (step S2). The resist film 40 is, for example, a positive type photoresist film. The resist film 40 is formed by, for example, a spin coat method.

  As shown in FIG. 7, the resist film 40 is exposed (first exposure) so as to correspond to the outer peripheral shape of the piezoelectric vibrating piece 100 (step S3). The exposure is performed using a mask M1 corresponding to the outer peripheral shape of the piezoelectric vibrating piece 100. Here, the outer peripheral shape of the piezoelectric vibrating piece 100 is the shape of the piezoelectric vibrating piece 100 in plan view (see FIG. 1). By exposing the resist film 40 using the mask M <b> 1, a photosensitive portion 42 is formed on a part of the resist film 40.

  As shown in FIG. 8, the exposed (first exposed) resist film 40 is developed (first developed) (step S4). As a result, the photosensitive portion 42 is removed, and the resist film 40 remains only in a region corresponding to the inside of the outer edge of the piezoelectric vibrating piece 100, and the corrosion-resistant film 30 outside the region is exposed. The development is performed, for example, by immersing the exposed resist film 40 in a developer (alkaline solution).

  As shown in FIG. 9, using the developed (first developed) resist film 40 as a mask, the corrosion-resistant film 30 is patterned (first patterning) so as to correspond to the outer peripheral shape of the piezoelectric vibrating piece 100 (step S5). The patterning of the corrosion-resistant film 30 is performed, for example, by first etching gold using an iodine-based etching solution and then etching chromium using an etching solution containing cerium ammonium nitrate. Thereby, the exposed corrosion-resistant film 30 is removed.

  As shown in FIG. 10, the developed (first developed) resist film 40 is exposed (second exposure) so as to correspond to the outer peripheral shape of the first-stage mesa portion 14a (see FIGS. 1 to 3). (Step S6). Here, the outer periphery shape of the 1st mesa part 14a is a shape of the 1st mesa part 14a in planar view (refer FIG. 1). The exposure is performed using a mask M2 corresponding to the outer peripheral shape of the first-stage mesa portion (first mesa portion) 14a. Further, the exposure is performed on the resist film 40 formed on both the front and back surfaces of the substrate 101.

  As shown in FIG. 11, the substrate 101 is etched using the patterned (first patterning) corrosion-resistant film 30 as a mask to form the outer periphery (outer shape) of the piezoelectric vibrating piece 100 (step S7). Etching of the substrate 101 is performed using, for example, a mixed liquid of hydrofluoric acid and ammonium fluoride (buffered hydrofluoric acid) as an etching liquid.

  Here, when the resist film 40 is immersed in an etching solution (for example, a solution containing hydrofluoric acid) used for etching the substrate 101, the surface of the resist film 40 is altered and the surface layer 50 is formed. FIG. 21 is a chemical formula of a material used as the resist film 40. The material of the resist film 40 is not limited to the material shown in FIG. As shown in FIG. 21, it is considered that when the resist film 40 is immersed in an etching solution, OH is replaced with F and a surface layer 50 is formed. Therefore, the surface layer 50 is formed on the surface of the resist film 40 in contact with the etching solution. Due to the influence of the surface layer 50, the dissolution phenomenon of the resist film 40 is hindered in the developing process of the resist film 40.

  As shown in FIG. 12, the exposed resist film 40 is immersed in a stripping solution to remove the surface layer (first surface layer) 50 of the resist film 40 (step S8). As the stripper, for example, an organic solution can be used. Specifically, as the stripping solution, for example, a solution containing N-methylpyrrolidone as a main component can be used.

  As shown in FIG. 13, the resist film 40 from which the surface layer (first surface layer) 50 has been removed is developed (second development) (step S9). As a result, the photosensitive portion 42 is removed, and the resist film 40 remains only in the region corresponding to the inside of the outer edge of the first mesa portion 14a, and the corrosion-resistant film 30 outside the region is exposed. Further, since the surface layer 50 is removed in the above-described step S8, the dissolution phenomenon of the resist film 40 is not hindered, and good development is possible. Development is performed in the same manner as in step S4 described above.

  As shown in FIG. 14, the first-stage mesa portion 14a (see FIGS. 1 and 2) is formed on the corrosion-resistant film 30 patterned (first patterning) using the developed (second developed) resist film 40 as a mask. Patterning (second patterning) is performed so as to correspond to the outer peripheral shape (step S10). Patterning is performed in the same manner as in step S5 described above.

  As shown in FIG. 15, the developed (second developed) resist film 40 is exposed (third exposure) so as to correspond to the outer peripheral shape of the second-stage mesa portion 14b (see FIGS. 1 to 3). (Step S11). Here, the outer peripheral shape of the second mesa portion 14b is the shape of the second mesa portion 14b in plan view (see FIG. 1). The exposure is performed using a mask M3 corresponding to the outer peripheral shape of the second-stage mesa portion (second mesa portion) 14b. Further, the exposure is performed on the resist film 40 formed on both the front and back surfaces of the substrate 101.

  As shown in FIG. 16, the substrate 101 is half-etched to a predetermined depth using the patterned (second patterned) corrosion-resistant film 30 as a mask to form the outer periphery (outer shape) of the first-stage mesa portion 14a (step S12). ). Half etching of the substrate 101 is performed using, for example, buffered hydrofluoric acid as an etchant. Also in this step, the surface layer 52 is formed on the resist film 40 because the resist film 40 is immersed in an etching solution used for etching the substrate 101 as in step S7. Half-etching is a technique for etching halfway through the thickness of the substrate.

  As shown in FIG. 17, the exposed resist film 40 is immersed in a stripping solution to remove the surface layer (second surface layer) 52 of the resist film 40 (step S13). The removal of the surface layer 52 is performed in the same manner as in step S8 described above.

  As shown in FIG. 18, the resist film 40 from which the surface layer 52 has been removed is developed (third development) (step S14). As a result, the photosensitive portion 42 is removed, and the resist film 40 remains only in the region corresponding to the inside of the outer edge of the second mesa portion 14b (see FIGS. 1 to 3), and the corrosion-resistant film 30 outside the region is exposed. To do. Further, since the surface layer 52 is removed in the above-described step S13, the dissolution phenomenon of the resist film 40 is not hindered, and good development is possible. Development is performed in the same manner as in steps S4 and S9 described above.

  As shown in FIG. 19, using the developed (third developed) resist film 40 as a mask, the patterned (second patterned) corrosion-resistant film 30 is formed on the second-stage mesa portion 14b (see FIGS. 1 to 3). Patterning (third patterning) is performed so as to correspond to the outer peripheral shape (step S15). The patterning of the corrosion resistant film 30 is performed in the same manner as in steps S5 and S10.

  As shown in FIG. 20, the substrate 101 is half-etched to a predetermined depth using the patterned (third patterned) corrosion-resistant film 30 as a mask to form the outer periphery (outer shape) of the second-stage mesa portion 14b (step S16). ). Half etching of the substrate 101 is performed using, for example, buffered hydrofluoric acid as an etchant.

  Through the above steps, the piezoelectric substrate 10 including the peripheral portion 12 and the excitation portion 14 having the mesa portions 14a and 14b can be formed.

  As shown in FIGS. 1 to 3, after removing the resist film 40 and the corrosion-resistant film 30, the excitation electrode 20, the extraction electrode 22, and the pad 24 are formed. The excitation electrode 20, the extraction electrode 22, and the pad 24 are formed by, for example, laminating chromium and gold in this order by sputtering or vacuum deposition, and then patterning the chromium and gold.

  Through the above steps, the piezoelectric vibrating piece 100 according to this embodiment can be manufactured.

  According to the method for manufacturing the piezoelectric vibrating piece 100, the resist film 40 used to form the outer periphery (outer shape) of the piezoelectric vibrating piece 100 is applied to the outer periphery of the first-stage mesa portion 14 a and the second-stage mesa portion 14 b. It can be used to form the outer periphery. This eliminates the need for film formation / peeling of the resist film for forming the outer peripheries of the mesa portions 14a, 14b, thereby reducing the steps for film formation / peeling of the resist film. Therefore, work efficiency can be increased and productivity can be improved. In addition, the step of forming and peeling the resist film gives stress to the substrate 101, and thus the step of forming and peeling the resist film may be repeated, so that the substrate 101 may be damaged and productivity is lowered. . According to the method for manufacturing the piezoelectric vibrating piece 100, the number of steps of forming and peeling the resist film can be reduced, so that productivity can be improved.

  According to the method for manufacturing the piezoelectric vibrating piece 100, the resist film 40 can be repeatedly exposed and developed by immersing it in a stripping solution and removing the surface layers 50 and 52 of the resist film 40. For example, if the surface layer of the resist film is repeatedly removed by dry etching using oxygen plasma, the corrosion resistant film may be seized. In the method of manufacturing the piezoelectric vibrating piece 100, such a problem does not occur because the surface layers 50 and 52 of the resist film 40 are removed by being immersed in a stripping solution. Therefore, the resist film 40 can be repeatedly exposed and developed.

Here, the case where the number of mesa stages is two has been described, but the number of mesa stages may be three or more. Even a piezoelectric vibrating piece having three or more mesas can be manufactured in the same manner as the piezoelectric vibrating piece 100 by repeating Steps S6 to S16. Also in the manufacturing process of the piezoelectric vibrating piece having three or more mesas, the resist film can be repeatedly used by using the method for manufacturing a piezoelectric vibrating piece according to the present embodiment, and the working efficiency can be improved.
Here, a case where the first mesa portion 14a and the second mesa portion 14b are simultaneously formed on both main surfaces of the substrate 101 by performing photolithography and etching on both main surfaces of the substrate 101 simultaneously. explained. On the other hand, after the mesa portions 14a and 14b are formed on one main surface (for example, the upper side) of the substrate 101, the mesa portions 141 and 14b are formed on the other main surface (for example, the lower side) of the substrate 101. Good.

2. Second Embodiment 2.1. Next, a piezoelectric vibrating piece according to a second embodiment will be described with reference to the drawings. FIG. 22 is a plan view schematically showing the piezoelectric vibrating piece 200 according to this embodiment. 23 and 24 are cross-sectional views schematically showing the piezoelectric vibrating piece 200 according to this embodiment. 23 is a sectional view taken along line XXIII-XXIII in FIG. 22, and FIG. 24 is a sectional view taken along line XXIV-XXIV in FIG. Hereinafter, in the piezoelectric vibrating piece 200, members having the same functions as those of the constituent members of the piezoelectric vibrating piece 100 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the example of the piezoelectric vibrating piece 100, as illustrated in FIGS. 1 to 3, the case where the mesa portions 14 a and 14 b are formed on both sides of the excitation portion 14 of the piezoelectric substrate 10 has been described. On the other hand, in the piezoelectric vibrating piece 200, mesa portions 14 a and 14 b are formed on one side (upper side in the illustrated example) of the excitation portion 14. Therefore, the coupling with the bending mode can be suppressed by the energy confinement effect.

2.2. Next, a method for manufacturing the piezoelectric vibrating piece 200 according to the second embodiment will be described.

  In the manufacturing process of the piezoelectric vibrating piece 200, in the manufacturing process of the piezoelectric vibrating piece 100 shown in FIGS. 4 to 20, the resist film 40 is exposed so as to correspond to the outer peripheral shape of the first-stage mesa portion 14a (second exposure). Step S6, Step S9 for developing the resist film 40 (second development), Step S10 for patterning the corrosion-resistant film 30 (second patterning), and the resist film 40 so as to correspond to the outer peripheral shape of the second mesa portion 14b. Step S11 for performing exposure (third exposure), step S14 for developing the resist film 40 (third development), and step S15 for patterning the corrosion-resistant film 30 (third patterning) are performed on one side of the main surface of the substrate 101 (illustrated). In this example, the resist film 40 and the corrosion-resistant film 30 formed on the upper side are performed. Further, the step S12 of forming the first-stage mesa portion 14a by half-etching the substrate 101 and the step S16 of forming the second-stage mesa portion 14b by half-etching the substrate 101 are performed on one of the main surfaces of the substrate 101. To the side. The other steps S1 to S5, S7, S8, and S13 are performed in the same manner as the manufacturing process of the piezoelectric vibrating piece 100. Thereby, the piezoelectric vibrating piece 200 can be manufactured.

3. Third Embodiment Next, a piezoelectric vibrating piece according to a third embodiment will be described with reference to the drawings. FIG. 25 is a plan view schematically showing the piezoelectric vibrating piece 300 according to this embodiment. FIG. 26 is a cross-sectional view schematically showing the piezoelectric vibrating piece 300. 26 is a cross-sectional view taken along line XXVI-XXVI in FIG. Hereinafter, in the piezoelectric vibrating piece 300, members having the same functions as the constituent members of the piezoelectric vibrating piece 100 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the example of the piezoelectric vibrating piece 100, as shown in FIGS. 1 and 3, the end surface 16a on the long side of the first mesa portion 14a and the end surface 16b on the long side of the second mesa portion 14b are within one plane. Was located at. On the other hand, in the piezoelectric vibrating piece 300, as shown in FIGS. 25 and 26, the end face 16a of the first mesa portion 14a and the end face 16b of the second mesa portion 14b are not located in one plane. First, a step is formed between the end face 16a of the first mesa portion 14a and the end face 16b of the second mesa portion 14b.

  The method for manufacturing the piezoelectric vibrating piece 300 is a process (step S11) in which exposure is performed so as to correspond to the outer peripheral shape of the second mesa portion 14b in the manufacturing process of the piezoelectric vibrating piece 100 shown in FIGS. Except for using a mask corresponding to the outer peripheral shape of the second mesa portion 14b shown, it is the same as the piezoelectric vibrating piece 100, and detailed description thereof is omitted.

4). Fourth Embodiment Next, a piezoelectric vibrating piece according to a fourth embodiment will be described with reference to the drawings. FIG. 27 is a plan view schematically showing the piezoelectric vibrating piece 400 according to the present embodiment. FIG. 28 is a cross-sectional view schematically showing the piezoelectric vibrating piece 400. 28 is a sectional view taken along line XXVIII-XXVIII in FIG. Hereinafter, in the piezoelectric vibrating piece 400, members having the same functions as those of the constituent members of the piezoelectric vibrating piece 100 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the example of the piezoelectric vibrating piece 100, as illustrated in FIGS. 1 to 3, the excitation electrode 20 is formed so as to cover the entire exposed portion of the excitation unit 14. On the other hand, in the piezoelectric vibrating piece 400, it is formed in the second mesa portion 14b. That is, the excitation electrode 20 is formed so as to cover a part of the exposed portion of the excitation unit 14.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

10 piezoelectric substrate, 12 peripheral portion, 14 excitation portion, 14a first mesa portion,
14b 2nd mesa part, 15a, 15b, 16a, 16b end face, 20 excitation electrode,
22 extraction electrode, 24 pad, 30 corrosion-resistant film, 40 resist film, 42 photosensitive part,
50, 52 Surface layer, 100 piezoelectric vibrating piece, 101 substrate, 200 piezoelectric vibrating piece,
M1, M2, M3 mask

Claims (4)

A method of manufacturing a piezoelectric vibrating piece that forms a multistage mesa structure by processing at least one main surface of a substrate,
Forming a corrosion-resistant film on the main surface of the substrate;
Forming a resist film on the surface of the corrosion-resistant film;
A first exposure step of exposing the resist film to an outer peripheral shape of the piezoelectric vibrating piece;
A first development step of developing the resist film exposed in the first exposure step ;
As a mask the resist film developed by the first developing step, a first patterning step of patterning the corrosion-resistant film on the outer peripheral shape of the piezoelectric vibrating piece,
After the first patterning step, a second exposure step of exposure light of the resist film developed by the first developing step to the outer peripheral shape of the mesa portion of the first stage,
Etching the substrate using the corrosion-resistant film patterned in the first patterning step as a mask after the second exposure step, and forming an outer periphery of the piezoelectric vibrating piece;
After the step of forming the outer periphery of the piezoelectric vibrating piece, the step of removing the first surface layer of the resist film by immersing the resist film exposed in the second exposure step in a stripping solution;
A second developing step of current image the resist film in which the first surface layer has been removed,
As a mask the resist film developed by the second developing step, a second patterning step of patterning the corrosion-resistant film that is patterned in the first patterning step in the outer peripheral shape of the mesa portion of the first stage,
After the second patterning step, the resist film which has been developed by the second developing step, a third exposure step of exposure light to the outer peripheral shape of the mesa portion of the second stage,
After the third exposure step, the substrate is half-etched using the corrosion-resistant film patterned in the second patterning step as a mask to form an outer periphery of the first mesa portion;
After the step of forming the outer periphery of the first-stage mesa portion, the step of immersing the resist film exposed in the third exposure step in a stripping solution to remove the second surface layer of the resist film;
A third developing step of current image the resist film in which the second surface layer has been removed,
As the third masking the resist film developed by the developing step, and a third patterning step of patterning the corrosion-resistant film that is patterned in the second patterning step the outer circumference shape of the mesa portion of the second stage,
Half etching the substrate using the corrosion-resistant film patterned in the third patterning step as a mask, and forming an outer periphery of the second-stage mesa portion;
A method for manufacturing a piezoelectric vibrating piece, comprising: In claim 1,
The method for manufacturing a piezoelectric vibrating piece, wherein the stripping solution is an organic solution. In claim 1 or 2,
The method for manufacturing a piezoelectric vibrating piece, wherein the stripping solution is a solution containing N-methylpyrrolidone as a main component. In claim 1 or 2,
In the step of etching the substrate, the piezoelectric vibrating piece manufacturing method, wherein the substrate is etched with a solution containing hydrofluoric acid.

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