JP6163404B2 - Method for manufacturing piezoelectric element - Google Patents

Description

  The present invention relates to a method for manufacturing a piezoelectric element used in an electronic device or the like. Hereinafter, a quartz crystal vibration element is taken as an example of a piezoelectric element.

  In an electronic device such as a computer, a mobile phone, or a small information device, a crystal resonator or a crystal oscillator is mounted as one of electronic components. This crystal resonator or crystal oscillator is used as a reference signal source or a clock signal source. In addition, a crystal resonator element is included inside the crystal resonator and the crystal oscillator. As an example of the crystal resonator element, a tuning fork-type bent crystal resonator element (hereinafter abbreviated as “vibrator element”) will be described. This vibration element includes a base, two vibration arm portions extending from the base, and a groove portion provided in each vibration arm portion. Hereinafter, the manufacturing method of the vibration element is simply referred to as “manufacturing method”.

  Here, the manufacturing method of the prior art (see, for example, Patent Document 1) will be described with reference to FIGS. 11 to 14 show cross sections of one vibrating arm portion and base portion.

  First, as shown in FIG. 11D, a corrosion resistant film 102 made of chromium is formed on the front and back surfaces of a substrate 101 made of a quartz Z plate, a photoresist film 103a is formed on the corrosion resistant film 102, and a vibrating arm is formed. The external patterning is performed by removing a part of the photoresist film 103a so that the photoresist film 103a remains only in the region 104 serving as a portion and the region 106 serving as a base.

  Subsequently, as shown in FIG. 11E, the portion of the corrosion-resistant film 102 where the photoresist film 103a is not formed in FIG. 11D is removed by etching. Therefore, the substrate 101 appears in the portion where the corrosion-resistant film 102 has been removed.

  Subsequently, as shown in FIG. 11F, all of the photoresist film 103a remaining in FIG. 11E is removed.

  Subsequently, as illustrated in FIG. 12G, a photoresist film 103b is formed on the entire surface of the substrate 101 including the corrosion-resistant film 102.

  Subsequently, as shown in FIG. 12H, a part of the photoresist film 103b is removed. At this time, not only the portion of the photoresist film 103b other than the region 104 serving as the vibrating arm portion and the region 106 serving as the base portion is removed, but also the photoresist film 103b in the region 105 serving as the groove portion is removed, thereby patterning the groove portion. Do.

  Subsequently, as shown in FIG. 12 [I], outer shape etching is performed. That is, in the substrate 101 made of a quartz Z plate, the etching is performed leaving only the region 104 to be the vibrating arm portion and the region 106 to be the base portion.

  Subsequently, as shown in FIG. 13J, the corrosion-resistant film 102 in the region 105 to be the groove is removed.

  Subsequently, as shown in FIG. 13 [K], groove etching is performed. That is, in the substrate 101 made of a quartz Z plate, the region 105 to be a groove is etched to a certain depth.

  Subsequently, as shown in FIG. 13L, all of the corrosion-resistant film 102 and the photoresist film 103b are removed.

  Subsequently, as shown in FIG. 14M, an electrode film 108 is formed on the entire front and back surfaces of the substrate 101.

  Subsequently, as shown in FIG. 14N, a photoresist film 103c is formed on the entire surface of the electrode film 108 by electrodeposition, and the electrode pattern is exposed and developed. At this time, in the region 106 serving as the base, the region 107 serving as the pad electrode is covered with the photoresist film 103c. Note that in order to form the photoresist film 103c so as to have fine unevenness as in the region 105 to be a groove, it is necessary to use an electrodeposition method.

  Finally, as shown in FIG. 14 [O], the electrode film 108 not covered with the photoresist film 103b is removed by etching, and then the photoresist film 103b is also removed. Thereby, excitation electrodes 122a and 122b are formed on the vibrating arm portion 112a and the groove portion 113a, and a pad electrode 121b is formed on the base portion 111, thereby completing the vibration element.

  FIG. 15 is a plan view showing the substrate 101 after the outer shapes of the base 111 and the vibrating arm portions 112a and 112b are formed by etching. The substrate 101 is separated into a large number of vibrating pieces 131, and each vibrating piece 131 is connected to the frame 133 via the connection portion 132. The vibrating piece 131 has the outer shape of the base portion 111 and the vibrating arm portions 112a and 112b, and is separated from the frame 133 by the connecting portion 132 as a vibrating element after the electrodes are formed.

Japanese Patent No. 3729249

National Astronomical Observatory, “Science Chronology 2005”, Maruzen Co., Ltd., issued on November 30, 2004, p. 492

  However, the conventional manufacturing method has the following problems.

  In the conventional manufacturing method, the outer shape of the base 111 and the vibrating arm 112a and the groove 113a are formed by etching (FIG. 12 [I], FIG. 13 [K]), and then the electrode film 108 is formed (FIG. 14 [ M]), and further, a photoresist film 103c is formed by using an electrodeposition method, and an electrode pattern is exposed and developed on this (FIG. 14 [N]).

  At this time, after the outer shapes of the base portion 111 and the vibrating arm portion 112a are formed by etching, one substrate 101 is separated into a large number of vibrating pieces 131 as shown in FIG. When exposure is performed in this state, the vibrating piece 131 is easy to move, so that the exposure accuracy is likely to drop. In addition, the vibration piece 131 is likely to drop off from the frame 133 due to vibration or impact when transported to the exposure apparatus. That is, these problems have contributed to a decrease in yield.

  Accordingly, an object of the present invention is to provide a method for manufacturing a piezoelectric element that can solve various problems in exposure after external etching of the piezoelectric element.

The manufacturing method according to the present invention includes:
Forming a corrosion-resistant film on a substrate made of a piezoelectric material and patterning the same;
A resist groove pattern forming step of forming a positive photoresist film pattern on the corrosion-resistant film;
After the resist groove pattern forming step, a latent image forming step of forming a latent image portion on the photoresist film by exposing a part of the photoresist film;
After the latent image forming step, an outer shape etching step for forming an outer shape of the base and an outer shape of the vibration portion extending from the base by removing the exposed portion of the substrate not covered with the corrosion-resistant film by etching; ,
Corrosion-resistant film groove pattern forming step for removing the corrosion-resistant film not covered with the photoresist film after the outer shape etching process,
After this corrosion-resistant film groove pattern forming step, a groove portion etching step for forming a groove portion in the vibrating portion by removing an exposed portion of the substrate not covered with the corrosion-resistant film to a certain depth by etching,
A latent image developing step for developing the latent image portion after the groove etching step or the corrosion-resistant film groove pattern forming step;
An electrode film forming step of forming an electrode film on the exposed portion of the substrate and the corrosion-resistant film and on the photoresist film after the latent image developing step and the groove etching step;
A lift-off step of removing the electrode film formed on the photoresist film together with the photoresist film;
A corrosion-resistant film removing step of removing the corrosion-resistant film exposed by removing the photoresist film;
including.

  In the prior art, the electrode pattern was exposed and developed on the photoresist film after the outer shape etching, and in the present invention, the electrode pattern was exposed on the photoresist film before the outer shape etching to form a latent image portion. Then, after the outer shape etching, the latent image portion is developed, and an electrode is formed by lift-off using a photoresist film at the time of outer shape etching. Therefore, according to the present invention, since the exposure after the outer shape etching becomes unnecessary, all the problems caused by the exposure after the outer shape etching can be solved.

FIG. 3 is a perspective view showing a vibration element obtained by the manufacturing method of Embodiment 1. It is the II-II line longitudinal cross-sectional view in FIG. It is a schematic sectional drawing which shows the state which mounted the vibration element of FIG. 1 on the element mounting member. It is sectional drawing which shows each process in the manufacturing method of Embodiment 1, and a process progresses in order of FIG. 4 [A], FIG. 4 [B], and FIG. 4 [C]. It is sectional drawing which shows each process in the manufacturing method of Embodiment 1, and a process progresses in order of FIG. 5 [D], FIG. 5 [E], and FIG. 5 [F]. It is sectional drawing which shows each process in the manufacturing method of Embodiment 1, and a process progresses in order of FIG. 6 [G], FIG. 6 [H], and FIG. 6 [I]. It is sectional drawing which shows each process in the manufacturing method of Embodiment 1, and a process progresses in order of FIG. 7 [J], FIG. 7 [K], and FIG. 7 [L]. It is sectional drawing which shows each process in the manufacturing method of Embodiment 1, and a process progresses in order of FIG. 8 [M], FIG. 8 [N], and FIG. 8 [O]. It is sectional drawing which shows each process in the manufacturing method of Embodiment 1, and a process progresses in order of FIG. 9 [P] and FIG. 9 [Q]. 10 [B1] is a cross-sectional view showing a part of the corrosion-resistant film outer shape pattern forming process in the manufacturing method of Embodiment 2, and FIG. 10 [K1] is one of the corrosion-resistant film groove pattern forming process in the manufacturing method of Embodiment 2. FIG. 10 [K2] is a cross-sectional view showing a part of the corrosion-resistant film groove pattern forming step in the manufacturing method of the comparative example. It is sectional drawing which shows each process in the manufacturing method of a prior art, and a process progresses in order of FIG. 11 [D], FIG. 11 [E], and FIG. 11 [F]. It is sectional drawing which shows each process in the manufacturing method of a prior art, and a process progresses in order of FIG. 12 [G], FIG. 12 [H], and FIG. 12 [I]. It is sectional drawing which shows each process in the manufacturing method of a prior art, and a process progresses in order of FIG. 13 [J], FIG. 13 [K], and FIG. 13 [L]. It is sectional drawing which shows each process in the manufacturing method of a prior art, and a process progresses in order of FIG. 14 [M] and FIG. 14 [N]. It is a top view which shows the board | substrate after the external shape etching in the manufacturing method of a prior art.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the accompanying drawings. In the present specification and drawings, the same reference numerals are used for substantially the same components. Moreover, since the shape drawn on drawing is drawn so that those skilled in the art can understand easily, it does not necessarily correspond with an actual dimension and ratio.

  FIG. 1 is a plan view illustrating a vibration element obtained by the manufacturing method according to the first embodiment. 2 is a longitudinal sectional view taken along line II-II in FIG. FIG. 3 is a schematic cross-sectional view illustrating a state where the vibration element of FIG. 1 is mounted on an element mounting member. Hereinafter, description will be given based on these drawings.

  The vibration element 10 according to the first embodiment includes a base portion 11, two vibration arm portions 12a and 12b as vibration portions extending from the base portion 11, and groove portions 13a provided in the vibration arm portions 12a and 12b. , 13b.

  The vibrating arm portions 12a and 12b extend from the base portion 11 in the same direction. The base 11 and the vibrating arm portions 12 a and 12 b constitute a crystal vibrating piece 15. In addition to the crystal vibrating piece 15, the vibration element 10 includes pad electrodes 21a and 21b, excitation electrodes 22a and 22b, frequency adjusting metal films 23a and 23b, wiring patterns 24a and 24b, and the like.

  Next, the configuration of the vibration element 10 will be described in more detail.

  The base 11 is a flat plate having a substantially rectangular shape in plan view. The quartz crystal resonator element 15 has a tuning fork shape in which the base portion 11 and the vibrating arm portions 12a and 12b are integrated, and is manufactured by a film forming technique, a photolithography technique, and a wet etching technique.

  The groove portions 13a, 13b vibrate from the boundary portion with the base 11 toward the tips of the vibrating arm portions 12a, 12b, two on the front and back surfaces of the vibrating arm portion 12a and two on the front and back surfaces of the vibrating arm portion 12b. The arm portions 12a and 12b are provided with a predetermined length parallel to the length direction of the arms 12a and 12b. In the first embodiment, two grooves 13a and 13b are provided on the front and back surfaces of the vibrating arm 12a and two grooves on the front and back surfaces of the vibrating arm 12b. However, the number of the grooves 13a and 13b is not limited. For example, one may be provided on the front and back surfaces of the vibrating arm portion 12a and one on each of the front and back surfaces of the vibrating arm portion 12b, or may be provided on only one side of the front and back surfaces.

  The vibrating arm 12a is provided with excitation electrodes 22a on both side surfaces so that the planes facing each other across the crystal have the same polarity, and an excitation electrode 22b is provided inside the groove 13a on the front and back surfaces. Similarly, the vibrating arm portion 12b is provided with excitation electrodes 22b on both side surfaces so that the planes facing each other across the crystal have the same polarity, and the excitation electrode 22a is provided inside the groove portion 13b on the front and back surfaces. . Accordingly, in the vibrating arm portion 12a, the excitation electrode 22a provided on both side surfaces and the excitation electrode 22b provided in the groove portion 13a have different polarities, and in the vibrating arm portion 12b, the excitation electrode 22b provided on both side surfaces. And the excitation electrode 22a provided in the groove 13b have different polarities.

  The base 11 is provided with pad electrodes 21a and 21b and wiring patterns 24a and 24b that electrically connect the pad electrodes 21a and 21b and the excitation electrodes 22a and 22b. The pad electrode 21a, the excitation electrode 22a, the frequency adjusting metal film 23a, and the wiring pattern 24a are electrically connected to each other. The pad electrode 21b, the excitation electrode 22b, the frequency adjusting metal film 23b, and the wiring pattern 24b are also electrically connected to each other.

  The vibration element 10 is fixed and electrically connected to the pad electrode 33 on the element mounting member 32 side via the pad electrodes 21 a and 21 b and the conductive adhesive 31.

  Quartz crystals are trigonal. A crystal axis passing through the crystal apex is defined as a Z axis, three crystal axes connecting ridge lines in a plane perpendicular to the Z axis are defined as an X axis, and a coordinate axis orthogonal to the X axis and the Z axis is defined as a Y axis. Here, when the coordinate system consisting of these X, Y, and Z axes is rotated within a range of ± 5 degrees around the X axis, the rotated Y axis and Z axis are respectively represented as Y ′ axis and Z axis. 'As axis. In this case, in the first embodiment, the extending direction of the two vibrating arm portions 12a and 12b is the Y′-axis direction, and the direction in which the two vibrating arm portions 12a and 12b are arranged is the X-axis direction. .

  Next, the operation of the vibration element 10 will be described. When the tuning fork type vibration element 10 is vibrated, an alternating voltage is applied to the pad electrodes 21a and 21b. When an electrical state after application is instantaneously captured, the excitation electrodes 22b provided in the groove portions 13a on the front and back of the vibrating arm portion 12a have a positive potential, and the excitation electrodes 22a provided on both side surfaces of the vibrating arm portion 12a are A negative electric potential is generated, and an electric field is generated from positive to negative. At this time, the excitation electrode 22a provided in the groove 13b on the front and back sides of the vibrating arm portion 12b has a negative potential, and the excitation electrode 22b provided on both side surfaces of the vibrating arm portion 12b has a positive potential, and is generated in the vibrating arm portion 12a. The polarity is opposite to the polarity, and an electric field is generated from plus to minus. The electric field generated by the alternating voltage causes a stretching phenomenon in the vibrating arm portions 12a and 12b, and a flexural vibration mode having a predetermined resonance frequency is obtained.

  4 to 9 are cross-sectional views showing each step in the manufacturing method of the first embodiment. Hereinafter, the manufacturing method of the first embodiment will be described with reference to FIGS. 1 to 3 and FIGS. 4 to 9.

  The vibrating arm portion 12a and the vibrating arm portion 12b have the same structure symmetrically, and the vibrating arm portion 12a side and the vibrating arm portion 12b side of the base 11 have the same symmetrical structure. 4 to 9 show a manufacturing process only on the vibrating arm portion 12a side and only on the vibrating arm portion 12a side of the base 11 in the longitudinal section taken along the line IV-IV in FIG.

  The manufacturing method of Embodiment 1 includes the following steps.

  Corrosion-resistant film outer pattern forming step (FIGS. 4A to 5F) in which a corrosion-resistant film 51 is formed and patterned on a substrate 41 made of a piezoelectric material.

  A resist groove pattern forming step for forming a pattern of a positive photoresist film 54 on the corrosion-resistant film 51 (FIGS. 6G to 6H).

  After the resist groove pattern forming step (FIG. 6G to FIG. 6H), a latent image forming step of forming a latent image portion 55 on the photoresist film 54 by exposing a part of the photoresist film 54. (FIG. 6 [I]).

  After the latent image forming step (FIG. 6 [I]), the exposed portion of the substrate 41 that is not covered with the corrosion-resistant film 51 is removed by wet etching, thereby forming the outer shape of the base portion 11 and the outer shape of the vibrating arm portion 12a. Outline etching process (FIG. 7 [J]).

  After the outer shape etching process (FIG. 7 [J]), a corrosion-resistant film groove pattern forming process (FIG. 7 [K]) for removing the corrosion-resistant film 51 not covered with the photoresist film 54.

  After the corrosion-resistant film groove pattern forming step (FIG. 7 [K]), the groove portion etching process for forming the groove portion 13a by removing the exposed portion of the substrate 41 not covered with the corrosion-resistant film 51 to a certain depth by wet etching. (FIG. 7 [L]).

  A latent image developing step (FIG. 8 [M]) for developing the latent image portion 55 after the groove etching step (FIG. 7 [L]) or the corrosion-resistant film groove pattern forming step (FIG. 7 [K]).

  An electrode film for forming an electrode film 56 on the exposed portion of the substrate 41 and the corrosion-resistant film 51 and on the photoresist film 54 after the latent image developing step (FIG. 8 [M]) and the groove etching step (FIG. 7 [L]). Formation step (FIG. 8 [O]).

  A lift-off process of removing the electrode film 56 formed on the photoresist film 54 together with the photoresist film 54 (FIG. 9 [P]).

  Corrosion-resistant film removing step for removing the corrosion-resistant film 51 exposed by removing the photoresist film 54 (FIG. 9 [Q]).

  In addition, before the electrode film forming step (FIG. 8 [O]), a step (FIG. 8 [N]) of removing the corrosion-resistant film 51 exposed by removing the latent image portion 55 may be included.

  Here, the photoresist film 54 is made of a positive type photoresist. When exposed to a negative photoresist, the solubility in the developer decreases, and the exposed portion remains after development. In contrast, a positive photoresist, contrary to a negative photoresist, has increased solubility in a developer when exposed to light, and the exposed portion is removed after development.

  Next, the above steps will be described in more detail.

  First, as shown in FIG. 4A, a substrate 41 such as a crystal Z plate is prepared.

  Subsequently, as shown in FIG. 4B, a corrosion-resistant film 51 is formed on the substrate 41. The corrosion-resistant film 51 is made of a metal having corrosion resistance against the crystal etching solution, and may be a single layer or a plurality of layers.

  Subsequently, as shown in FIG. 4C, a photoresist film 53 is formed on the corrosion resistant film 51. The photoresist film 53 may be either a negative type or a positive type, and is formed by, for example, a spin coating method.

  Subsequently, as shown in FIG. 5D, the pattern of the first mask 43 to be formed on the corrosion-resistant film 51 is exposed and developed on the photoresist film 53. This pattern is a pattern of the vibration part enlarged region 42 and the base part enlarged region 47 and is slightly larger than the outer shape pattern.

  Subsequently, as shown in FIG. 5E, the corrosion resistant film 51 is etched using the developed photoresist film 53. For example, the corrosion-resistant film 51 not covered with the photoresist film 53 is removed by wet etching using a dedicated etching solution.

  Subsequently, as shown in FIG. 5F, the remaining photoresist film 53 is peeled off to form a first mask 43 made of the corrosion-resistant film 51.

  Subsequently, as shown in FIG. 6G, a photoresist film 54 is formed on the corrosion-resistant film 51. The photoresist film 54 is a positive type and is formed by, for example, a spin coating method.

  Subsequently, as shown in FIG. 6H, the pattern of the second mask 45 to be formed on the corrosion-resistant film 51 is exposed and developed on the photoresist film 54. This pattern is a region 44 to be a vibrating arm excluding the groove 13a and a region 48 to be a base, which is slightly smaller than the vibration portion enlarged region 42 and the base enlarged region 47, and the region 46 to be a groove is omitted. Yes.

  Subsequently, as shown in FIG. 6 [I], a part of the photoresist film 54 is exposed to form a latent image portion 55. The latent image portion 55 corresponds to a region 49 to be an electrode. The region 49 serving as an electrode includes the region serving as the pad electrode 21a and the wiring patterns 24a and 24b illustrated in FIG. 1 in addition to the region serving as the pad electrode 21b illustrated in FIG. The exposure in this step is the second exposure for the same photoresist film 54, that is, “double exposure”.

  Subsequently, as shown in FIG. 7J, the substrate 41 that is not covered with the first mask 43, that is, the exposed surface of the crystal, is completely removed using buffered hydrofluoric acid (HF + NH4F), so that the vibration portion The outer shapes of the enlarged region 42 and the base enlarged region 47 are formed.

  Subsequently, as shown in FIG. 7 [K], the first mask 43 that is not covered with the second mask 45, that is, the corrosion-resistant film 51 is etched with the above-mentioned mixed solution.

  Subsequently, as shown in FIG. 7L, the substrate 41 that is not covered with the etched first mask 43, that is, the exposed surface of the crystal is etched using buffered hydrofluoric acid (HF + NH4F). At this time, the region 46 to be the groove is etched to a certain depth so as not to penetrate, and the region 44 to be the vibrating arm and the region 48 to be the base are etched so as to completely remove the outside of the outer shape. Since the region 44 serving as the vibrating arm and the region 48 serving as the base are also etched from the side surfaces, the substantial etching rate is higher than that of the region 46 serving as the groove.

  Subsequently, as shown in FIG. 8 [M], the latent image portion 55 is developed. As a result, the latent image portion 55 is removed in the region 49 to be an electrode, and the corrosion-resistant film 51 is exposed. Note that the order of the step in FIG. 7 [L] and the step in FIG. 8 [M] may be interchanged.

  Subsequently, as shown in FIG. 8N, the corrosion-resistant film 51 exposed by removing the latent image portion 55 is removed by the etching described above. Thereby, in the region 49 to be an electrode, the corrosion resistant film 51 is removed and the substrate 41 is exposed. This step is not always necessary. If this step is omitted, the corrosion-resistant film 51 remains in the region 49 to be an electrode, so that the pad electrode 21b is a laminated film of the corrosion-resistant film 51 and the electrode film 56.

  Subsequently, as shown in FIG. 8 [O], an electrode film 56 is formed on the exposed portion of the substrate 41 and on the photoresist film 54. The electrode film 56 is, for example, a single layer film of chromium or titanium, a laminated film in which palladium or gold is formed thereon, and is formed by sputtering or vapor deposition, for example.

  Subsequently, as shown in FIG. 9P, the electrode film 56 formed on the photoresist film 54 is removed together with the photoresist film 54. In other words, the second mask 45 formed on the front and back of the substrate 41 and the electrode film 56 formed thereon are peeled off. This can be easily removed by immersing them in a solution for dissolving the photoresist (for example, acetone). However, the corrosion resistant film 51 under the second mask 45 remains. This electrode forming method is a lift-off method.

  Finally, as shown in FIG. 9 [Q], the corrosion-resistant film 51 exposed by removing the photoresist film 54 is removed by the etching described above. As a result, excitation electrodes 22 a and 22 b are formed in the vibrating arm portion 12 a and the groove portion 13 a, and a pad electrode 21 b is formed in the base portion 11. At this time, as shown in FIG. 1, the pad electrode 21a and the wiring patterns 24a and 24b are also formed, and the vibration element 10 is completed. The frequency adjusting metal films 23a and 23b may be formed in the same manner as the pad electrode 21b or the like by forming the latent image portion 55 in the regions to be the frequency adjusting metal films 23a and 23b. You may form by a metal mask and vapor deposition.

  Next, the operation and effect of the manufacturing method of Embodiment 1 will be described.

  (1) In the prior art, the electrode pattern was formed by exposing and developing the electrode pattern on the photoresist film 103c after the outer shape etching (FIG. 14 [M] [N] [O]). In contrast, in the first embodiment, the photoresist film 54 is exposed to an electrode pattern before the outer shape etching to form a latent image portion 55 (FIG. 6 [I]), and the latent image portion 55 is developed after the outer shape etching. (FIG. 8 [M]), an electrode is formed by lift-off using the photoresist film 54 at the time of outer shape etching (FIG. 8 [O] and FIG. 9 [P]). More specifically, the latent image portion 55 is formed by exposing a part of the photoresist film 54 on which the outer pattern is formed (FIG. 6 [I]), and the pattern of the corrosion-resistant film 51 for the groove 13a. (FIG. 7 [K]), and then developing the latent image portion 55 (FIG. 8 [M]), the region 49 protected by the latent image portion 55 during the etching of the groove 13a (FIG. 7 [K]). L]), the pad electrode 21b can be formed (FIG. 9 [Q]).

  Therefore, according to the first embodiment, since the exposure after the outer shape etching becomes unnecessary, all the problems caused by the exposure after the outer shape etching can be solved. For example, since the single substrate 41 is not separated into a large number of vibrating pieces before the outer shape etching, by performing all processes that require alignment such as exposure before the outer shape etching, the vibrating pieces can be swung. It is possible to prevent a decrease in exposure accuracy due to this. In addition, it is possible to prevent the vibrating piece from falling off due to vibrations when transported to the exposure apparatus.

  Specifically, after the outer shape etching process (FIG. 7J), one substrate 41 is separated into a large number of crystal vibrating pieces 15, and a part of each crystal vibrating piece 15 is a frame (see FIG. 15). It will be in a fixed state. For this reason, if the substrate 41 after the outer shape etching process (FIG. 7 [J]) is carelessly handled, the crystal vibrating piece 15 may fall off the frame. Therefore, as in the first embodiment, the step of exposing a part of the photoresist film 54 (FIG. 6 [I]) is performed before the outer shape etching step (FIG. 7 [J]), and then performed. Compared to, exposure workability can be improved.

  (2) In the first embodiment, in the outer shape etching step (FIG. 7 [J]), the outer shape of the base 11 and the outer shape of the vibrating arm portion 12a are formed larger than the final dimensions, and the groove portion etching step (FIG. 7 [J] L]), the groove 13a is formed in the vibrating arm 12a, and at the same time, the outer shape of the base 11 and the outer shape of the vibrating arm 12a are formed to final dimensions. In other words, in the first embodiment, the substrate 41 is etched using the first mask 43 that covers the vibrating portion enlarged region 42 including the outer shape of the vibrating arm portion 12a and the base enlarged region 47 including the outer shape of the base portion 11 (FIG. 7 [J]), the substrate 41 is further etched by using the second mask 45 covering the region 44 to be the vibrating arm portion and the region 48 to be the base portion excluding the groove portion 13a, and the outer shape of the vibrating arm portion 12a and the base portion 11 And the groove part 13a is formed simultaneously (FIG. 7 [L]).

  The first effect in this case is that the outer mask and the groove pattern are drawn on the photomask that is the basis of the second mask 45, so that no alignment error occurs between these patterns. is there. In the prior art, since the outer shape pattern and the groove pattern are drawn on different photomasks, an alignment error occurs between these patterns (FIG. 11 [D] and FIG. 12 [H]).

  The second effect is that the influence of the positional deviation between the pattern of the first mask 43 and the pattern of the second mask 45 can be eliminated by providing the vibrating portion enlarged region 42 and the base enlarged region 47. . This is because the region 44 serving as the vibrating arm and the region 48 serving as the base are formed on the vibrating unit enlarged region 42 and the base enlarged region 47 so that the vibrating unit enlarged region 42 and the base enlarged region are formed. This is because even if the region 44 and the region 48 are shifted within the range 47, the vibrating arm portion 12a and the base portion 11 having a desired shape can be obtained. In the prior art, in the outer shape etching step (FIG. 12 [I]), the outer shape of the base 111 and the outer shape of the vibrating arm portion 112a are formed to the final dimensions, and the groove portion etching step (FIG. 13 [K]) is also performed. The groove 113a is formed in the vibrating arm portion 112a, and at the same time, the outer shape of the base 111 and the outer shape of the vibrating arm portion 112a are formed according to final dimensions. Therefore, if these etching patterns are misaligned, the substrate 101 is excessively etched by the misalignment in the groove etching process (FIG. 13 [K]).

  (3) In the first embodiment, wet etching is used, but dry etching can also be used. However, when the substrate 41 is made of quartz, wet etching with a high etching rate is desirable.

  10 [B1] is a cross-sectional view showing a part of the corrosion-resistant film outer shape pattern forming process in the manufacturing method of Embodiment 2, and FIG. 10 [K1] is one of the corrosion-resistant film groove pattern forming process in the manufacturing method of Embodiment 2. FIG. 10 [K2] is a cross-sectional view showing a part of the corrosion-resistant film groove pattern forming step in the manufacturing method of the comparative example. Hereinafter, the manufacturing method of the second embodiment will be described with reference to FIGS. 1 to 9 and FIG.

  The second embodiment is different from the first embodiment in the following configuration.

  First, as shown in FIG. 10 [B1], the corrosion-resistant film 51 has a first layer 511 in contact with the substrate 41 and an ionization tendency smaller than the ionization tendency of the first layer 511 in contact with the first layer 511. It has the 2nd layer 512 which has.

  Second, as shown in FIG. 10 [K1], in the anti-corrosion film groove pattern forming step (FIG. 7 [K]), after removing the second layer 512 not covered with the photoresist film 54, the second layer The first layer 511 is removed by wet etching while leaving all the photoresist film 54 on 512. Similarly, after removing the second layer 512 not covered with the photoresist film 53 in the corrosion-resistant film outer shape pattern forming step (FIG. 5E), all the photoresist films 53 on the second layer 512 are removed. The first layer 511 may be removed by wet etching while remaining.

  Next, the above steps will be described in more detail.

  First, as shown in FIG. 4A, a substrate 41 such as a crystal Z plate is prepared. Subsequently, as shown in FIG. 10 [B1], a corrosion-resistant film 51 including a first layer 511 and a second layer 512 is formed on the substrate 41. In Embodiment 2, chromium is used as the first layer 511, gold is used as the second layer 512, and sputtering or vapor deposition is used as the film formation method. Chromium has better adhesion to the substrate 41 than gold, and gold has better corrosion resistance to the crystal etching solution than chromium. That is, the corrosion-resistant film 51 has the advantages of both the chromium first layer 511 and the gold second layer 512, and is excellent in adhesion and corrosion resistance.

  Thereafter, steps similar to those of the first embodiment are continued from FIG. 4C to FIG. 7J. Subsequently, as shown in FIG. 10 [K1], the second layer 512 made of gold that is not covered with the photoresist film 54 is etched with, for example, a mixed solution of iodine and potassium iodide. This mixture does not etch chromium. Then, as shown in FIG. 7 [K], the first layer 511 made of chromium which is not covered with the photoresist film 54 and the second layer 512 is etched with, for example, a mixed solution of ceric ammonium nitrate and perchloric acid. To do. In this mixed solution, gold is not etched. Thereafter, steps similar to those of the first embodiment are continued from FIG. 7 [L] to FIG. 9 [Q].

  On the other hand, in the comparative example shown in FIG. 10 [K2], as shown in FIG. 10 [K1], the second layer 512 made of gold not covered with the photoresist film 54 is mixed with, for example, a mixed solution of iodine and potassium iodide. After the etching, the photoresist film 54 is removed as shown in FIG. In this state, the first layer 511 made of chromium that is not covered with the second layer 512 is etched with, for example, a mixed solution of ceric ammonium nitrate and perchloric acid.

  Here, the standard electrode potential of chromium (Cr) is −0.424 [V], and the standard electrode potential of gold (Au) is +1.52 [V] or +1.83 [V]. That is, the ionization tendency of chromium is larger than the ionization tendency of gold. In such a combination of metals, when the first chromium layer 511 is wet-etched in the state shown in FIG. 10 [K2] of the comparative example, so-called “electric corrosion” occurs, so that the first chromium layer 511 is generated. Is abnormally etched, so that the etching accuracy is lowered. “Electrical corrosion” is an abbreviation for “electrochemical corrosion”. When two different metals come into contact with an electrolyte solution (etching solution) at the same time, a metal with a high tendency to ionize due to a potential difference between the metals is changed into a small metal. This refers to a phenomenon in which a metal corrodes due to the movement of electrons and dissolution of metal atoms that have lost their charge as ions into the solution.

  On the other hand, according to the second embodiment, the first layer 511 is wet-etched in the corrosion-resistant film 51 having a structure in which the second layer 512 having a low ionization tendency is stacked on the first layer 511 having a high ionization tendency. At this time, the entire second layer 512 is covered with the photoresist film 54. Therefore, since the second layer 512 does not substantially contact the etching solution of the first layer 511, it is possible to suppress a decrease in etching accuracy due to the occurrence of electrolytic corrosion.

  Further, the metal types of the first layer 511 and the second layer 512 may be any combination as long as the magnitude relationship of the ionization tendency is satisfied. For example, the first layer 511 may be titanium (Ti: standard electrode potential−1.63 [V]), and the second layer 512 may be platinum (Pt: standard electrode potential + 1.188 [V]). The standard electrode potential referred to in this specification is based on a standard hydrogen electrode in an aqueous solution at 25 ° C. and pH = 0 (see Non-Patent Document 1).

  Other configurations, operations, and effects in the second embodiment are the same as those in the first embodiment.

  Next, the manufacturing method of Embodiment 3 is demonstrated. Since the third embodiment has many parts in common with the first embodiment, the following description will be given with reference to FIGS.

  In the third embodiment, in the anti-corrosion film outer pattern forming step (FIGS. 4A to 5E), the photoresist film 53 used when patterning the anti-corrosion film 51 is made of a positive photoresist. . In the resist groove pattern forming step (FIG. 6 [H]), the photoresist film 53 used in the corrosion-resistant film outer shape pattern forming step (FIGS. 4A to 5E) is used as it is without being peeled off. . That is, after the process of FIG. 6 [H], the process proceeds to the process of FIG. 9 [Q] with the photoresist film 54 replaced with the photoresist film 53. Therefore, the photoresist film 53 is exposed and developed three times in total, that is, “triple exposure”.

  According to the third embodiment, the step of peeling off the photoresist film 53 (FIG. 5 [F]) and the step of applying the photoresist film 54 (FIG. 6 [G]) are not required, and therefore, compared with the first embodiment. Manufacturing process can be simplified.

  Other configurations, operations, and effects in the third embodiment are the same as those in the first embodiment.

  Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention. Further, the present invention includes a combination of some or all of the configurations of the above-described embodiments as appropriate.

  The present invention can be applied to any piezoelectric element including a base, a vibration part, and a groove part. For example, a piezoelectric element made of crystal or ceramics, a tuning fork type bending vibrator, a thickness shear vibrator, a gyro sensor It can also be used for sensor elements such as.

DESCRIPTION OF SYMBOLS 10 Vibration element 11 Base part 12a, 12b Vibration arm part 13a, 13b Groove part 15 Crystal vibrating piece 21a, 21b Pad electrode 22a, 22b Excitation electrode 23a, 23b Frequency adjustment metal film 24a, 24b Wiring pattern 31 Conductive adhesive 32 Element mounting Member 33 Pad electrode 41 Substrate 42 Vibrating part enlarged region 43 First mask 44 Visible arm part 45 Second mask 46 Groove part 47 Base enlarged area 48 Base part 49 Electrode area 51 Corrosion resistant film 511 First layer 512 Second layer 53 Photoresist film 54 Photoresist film 55 Latent image portion 56 Electrode film

DESCRIPTION OF SYMBOLS 111 Base part 112a, 112b Vibrating arm part 113a Groove part 121b Pad electrode 122a, 122b Excitation electrode 101 Substrate 102 Corrosion-resistant film 103a Photoresist film 103b Photoresist film 103c Photoresist film 104 Area | region used as a vibrating arm part 105 Area | region used as a groove part 106 Base part The area 107 The area that becomes the pad electrode 108 The electrode film 131 The vibrating element 132 The connecting portion 133 The frame

Claims (5)

Forming a corrosion-resistant film on a substrate made of a piezoelectric material and patterning the same;
A resist groove pattern forming step of forming a positive photoresist film pattern on the corrosion-resistant film;
After the resist groove pattern forming step, a latent image forming step of forming a latent image portion on the photoresist film by exposing a part of the photoresist film;
After the latent image forming step, an outer shape etching step for forming an outer shape of the base and an outer shape of the vibration portion extending from the base by removing the exposed portion of the substrate not covered with the corrosion-resistant film by etching; ,
Corrosion-resistant film groove pattern forming step for removing the corrosion-resistant film not covered with the photoresist film after the outer shape etching process,
After this corrosion-resistant film groove pattern forming step, a groove portion etching step for forming a groove portion in the vibrating portion by removing an exposed portion of the substrate not covered with the corrosion-resistant film to a certain depth by etching,
A latent image developing step for developing the latent image portion after the groove etching step or the corrosion-resistant film groove pattern forming step;
An electrode film forming step of forming an electrode film on the exposed portion of the substrate and the corrosion-resistant film and on the photoresist film after the latent image developing step and the groove etching step;
A lift-off step of removing the electrode film formed on the photoresist film together with the photoresist film;
A corrosion-resistant film removing step of removing the corrosion-resistant film exposed by removing the photoresist film;
The manufacturing method of the piezoelectric element containing this. The corrosion resistant film comprises a first layer in contact with the substrate and a second layer in contact with the first layer and having an ionization tendency smaller than the ionization tendency of the first layer,
At least one of the corrosion-resistant film outer shape pattern forming step and the corrosion-resistant film groove pattern forming step, after removing the second layer not covered with the photoresist film, all the photoresist films on the second layer The first layer is removed by wet etching while leaving
The method for manufacturing a piezoelectric element according to claim 1. The first layer is made of chromium, the second layer is made of gold, the substrate is made of quartz,
In the outer shape etching step and the groove portion etching step, wet etching is used.
A method for manufacturing a piezoelectric element according to claim 2. In the corrosion resistant film outer shape pattern forming step, when patterning the corrosion resistant film, a photoresist film made of a positive photoresist is used,
In the resist groove pattern forming step, the photoresist film used in the corrosion-resistant film outer shape pattern forming step is used as it is.
The method for manufacturing a piezoelectric element according to claim 1. In the outer shape etching step, the outer shape of the base and the outer shape of the vibrating portion are formed larger than the final dimensions,
In the groove portion etching step, simultaneously with forming the groove portion in the vibration portion, the outer shape of the base portion and the outer shape of the vibration portion are formed in final dimensions.
The manufacturing method of the piezoelectric element as described in any one of Claims 1 thru | or 4.

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