JP2017079438A - Method for manufacturing piezoelectric piece, piezoelectric piece for vibration element, piezoelectric vibration element, and piezoelectric vibration device - Google Patents

Abstract

A method of manufacturing a piezoelectric piece capable of dividing a wafer into piezoelectric pieces by wet etching and improving the accuracy of the shape of the piezoelectric piece is provided. A method of manufacturing a quartz crystal piece 15 involves wet etching by immersing a wafer 31 provided with a first mask 33 in a chemical solution 51. The first mask 33 is partitioned by a plurality of openings 37 that expose the main surface of the wafer 31, whereby a plurality of individual regions 39 that overlap with portions of the wafer 31 that become the plurality of crystal pieces 15, and a plurality of individual pieces. A plurality of connecting regions 41 extending from the region 39 and connecting the plurality of individual regions 39 are provided. Etching is performed by etching portions under the plurality of openings 37 in the wafer 31 to form through holes, and etching portions under the plurality of connection regions 41 in the wafer 31 by side etching. This is continued until the crystal pieces 15 are separated. [Selection] Figure 7

Description

  The present invention relates to a method of manufacturing a piezoelectric piece (piezoelectric blank) used for a piezoelectric vibrator or a piezoelectric oscillator, and also relates to a piezoelectric element for a vibration element formed by the manufacturing method, a piezoelectric vibration element having the piezoelectric piece, and the The present invention relates to a piezoelectric vibration device having a piezoelectric vibration element.

  A piezoelectric vibration element used for a piezoelectric vibration device such as a crystal resonator or a crystal oscillator includes, for example, a piezoelectric piece and an excitation electrode provided on the piezoelectric piece. There are the following two types of methods for manufacturing such a piezoelectric vibration element. One is a method having a step of obtaining a plurality of piezoelectric pieces by dividing the wafer into pieces and a step of forming excitation electrodes on the separated piezoelectric pieces. The other is to etch the wafer to form a plurality of piezoelectric pieces, a connecting portion extending from the plurality of piezoelectric pieces, and a frame portion to which the connecting portion is connected, and so on. A step of forming an excitation electrode on the piezoelectric piece of the wafer having a different shape, and a step of breaking the piezoelectric piece on which the excitation electrode is formed from the frame portion into a plurality of pieces. For example, Patent Document 1). In the former manufacturing method in which the excitation electrode is formed after being separated into individual pieces, the portion corresponding to the connecting portion in the latter manufacturing method is naturally not formed.

JP 2010-178320 A

  In the manufacturing method in which the excitation electrode is formed after being singulated, the wafer is usually singulated by dicing. However, it is conceivable to divide the wafer into pieces by wet etching. As wet etching used for wafer separation, for example, a method of immersing the wafer in a chemical solution is conceivable. In this wet etching, for example, the outer periphery of the wafer is held by a jig, and the wafer is immersed in the chemical solution in the chemical solution tank. In the chemical bath, a relative flow of the chemical solution with respect to the wafer may be positively generated by generating a flow of the chemical solution and / or vibrating the wafer.

  On the other hand, in order to make a piezoelectric piece into a desired shape by wet etching, it is necessary to perform sufficient etching. In particular, since a single crystal piezoelectric piece has anisotropy with respect to etching, it is necessary to perform etching for a long time in order to eliminate residues.

  However, when the wafer is separated into pieces by wet etching, the piezoelectric pieces are separated into pieces before the piezoelectric pieces have a desired shape. Since the separated piezoelectric pieces are not held by the jig, for example, they are submerged, floated, or moved in the chemical solution. Therefore, for example, the etching conditions after being separated into pieces are different from those before being separated into pieces. Further, for example, the plurality of singulated piezoelectric pieces have different postures and the like, and consequently have different etching conditions. As a result, the accuracy of the shape of the piezoelectric piece decreases.

  Accordingly, there is provided a method for manufacturing a piezoelectric piece, a piezoelectric piece for a vibration element, a piezoelectric vibration element, and a piezoelectric vibration device capable of dividing a wafer into piezoelectric pieces by wet etching and improving the accuracy of the shape of the piezoelectric piece. desired.

  According to one aspect of the present invention, there is provided a method for manufacturing a piezoelectric piece, comprising: a first mask forming step of forming a first etching mask on both main surfaces of a wafer; and the wafer provided with the first etching mask is immersed in a chemical solution. An etching step for performing wet etching, and the first etching mask is divided by a plurality of openings exposing the main surface of the wafer, thereby overlapping a plurality of portions of the wafer to be a plurality of piezoelectric pieces. And a plurality of connecting regions that extend from the plurality of individual regions and directly or indirectly connect the plurality of individual regions, and the etching step includes the wafer After the portions under the plurality of openings are etched to form through holes, side etching is performed under the plurality of connection regions of the wafer. Min is continued until the plurality of piezoelectric strips are etched is singulated.

  Preferably, the first etching mask has an outer region overlapping an outer peripheral portion of the wafer, and the plurality of individual regions are directly or indirectly connected to the outer region by the plurality of connecting regions. In the etching step, the wafer is converted into a chemical solution while holding the outer peripheral portion of the wafer and separating a portion of the wafer inside the outer peripheral portion from the bottom surface of the chemical bath and the liquid level of the chemical solution. Immerse.

  Preferably, the method further comprises a second mask forming step of forming a second etching mask on the first etching mask so as to overlap the plurality of individual regions and to expose the plurality of openings. Exposes the plurality of connection regions.

  Preferably, the second etching mask overlaps each of the plurality of individual regions.

  Preferably, the second etching mask overlaps a central portion of each of the plurality of individual regions and exposes an outer peripheral side portion of each of the plurality of individual regions.

  Preferably, the first etching mask is made of a metal film, and the second etching mask is made of a resist film thicker than the metal film.

  Preferably, the plurality of connecting regions include those in which both ends are connected between two opposing sides of the adjacent individual regions and the individual regions are directly connected to each other.

  Preferably, each of the plurality of individual regions has a rectangular shape, and the plurality of connection regions extend from both ends of a short side of the plurality of individual regions.

  A piezoelectric element for a vibration element according to an aspect of the present invention includes a plate-shaped main body portion and a protrusion protruding from an outer peripheral surface of the main body portion, and a tip surface of the protrusion is a crystal plane. It is constituted by.

  A piezoelectric vibration element according to one aspect of the present invention includes the above-described piezoelectric element piezoelectric element and excitation electrodes positioned on both surfaces of the main body.

  It has said vibration element which concerns on 1 aspect of this invention, and the mounting base | substrate with which the said vibration element is mounted.

  According to the above procedure or configuration, the wafer can be separated into piezoelectric pieces by wet etching, and the shape accuracy of the piezoelectric pieces can be improved.

1 is an exploded perspective view showing a configuration of a main part of a crystal resonator according to a first embodiment of the present invention. 2A is a cross-sectional view of the crystal piece taken along line IIa-IIa in FIG. 1, FIG. 2B is a plan view showing the end of the crystal piece, and FIG. 2C is a view showing the end face of the crystal piece. The flowchart which shows an example of the outline | summary of the procedure of the manufacturing method of a crystal oscillation element. 4A and 4B are plan views showing a part of the first mask and the second mask used in the manufacturing method of FIG. Sectional drawing in the VV line | wire of FIG.4 (b). FIG. 6A to FIG. 6D are schematic views for explaining the progress of wet etching. Fig.7 (a)-FIG.7 (d) are the schematic diagrams which show the continuation of FIG.6 (d). FIG. 8A to FIG. 8D are cross-sectional views showing the progress of etching in the opening of the mask. FIG. 9A is a plan view showing a part of a second mask used in the method of manufacturing a crystal piece according to the second embodiment, and FIG. 9B is a cross section taken along the line IXb-IXb in FIG. Figure. FIG. 10A to FIG. 10C are cross-sectional views for explaining an example of the effect of this embodiment. FIG. 11A and FIG. 11B are plan views showing a part of a first mask according to a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the dimensional ratios and the like on the drawings do not necessarily match the actual ones.

  In the second and subsequent embodiments, configurations that are the same as or similar to the configurations of the embodiments that have already been described may be denoted by the same reference numerals as the configurations that have already been described, and the description thereof will be omitted. There is this.

  For the sake of convenience, an orthogonal coordinate system comprising a D1 axis, a D2 axis, and a D3 axis is attached to the drawing. In the piezoelectric device of the embodiment, any direction may be upward or downward. For convenience, terms such as an upper surface or a lower surface may be used with the positive side of the D2 axis as an upper side.

<First Embodiment>
(Schematic structure of crystal unit)
FIG. 1 is an exploded perspective view showing a schematic configuration of a crystal resonator 1 (hereinafter, “crystal” may be omitted) according to a first embodiment of the present invention.

  The vibrator 1 is mainly composed of, for example, three members. That is, the vibrator 1 includes a crystal resonator element 3 that vibrates when a voltage is applied (hereinafter, “crystal” may be omitted), an element mounting member 5 and a lid member for packaging the resonator element 3. 7.

  When the vibration element 3 is accommodated in the box-shaped element mounting member 5 and the element mounting member 5 is covered with the lid member 7, the vibrator 1 has, for example, a generally thin rectangular parallelepiped shape as a whole. The inside of the element mounting member 5 is sealed with, for example, a lid member 7. Moreover, the inside is evacuated, for example, or an appropriate gas (for example, nitrogen) is sealed therein.

  The dimensions of the vibrator 1 may be set as appropriate. For example, in a relatively small one, the width (D3 axis direction) is 0.40 mm to 3.20 mm, the length (D1 axis direction) is 0.65 mm to 5.00 mm, and the thickness (D2 axis direction) is It is 0.2 mm or more and 1.2 mm or less.

  The vibrator 1 is disposed, for example, with its lower surface (the negative surface in the D2 axis direction) facing a mounting surface such as a circuit board (not shown), and is surface-mounted on the mounting surface by bumps made of solder or the like. . The vibrator 1 is applied with a voltage by an oscillation circuit provided on the circuit board, and contributes to generation of an oscillation signal.

(Package structure)
The element mounting member 5 includes, for example, a base body 9 as a main component of the element mounting member 5, a pair of pads 11 for mounting the vibration element 3, and a vibrator 1 for mounting the vibrator 1 on a circuit board (not shown). A plurality of external terminals 13 are provided.

  The base 9 is made of an insulating material and has a recess 5 a that houses the vibration element 3. The insulating material which comprises the base | substrate 9 is a ceramic or resin, for example. The pair of pads 11 is composed of, for example, a conductive layer provided on the bottom surface of the recess 5a. The plurality of external terminals 13 are constituted by, for example, a conductive layer provided on the lower surface of the base body 9 (the surface on the side opposite to the side where the recess 5a is opened). The pair of pads 11 and two of the plurality of external terminals 13 are connected to each other by a wiring conductor (not shown) provided on the base 9.

  The lid member 7 is made of, for example, metal, and is joined to the upper surface of the element mounting member 5 by seam welding or the like.

(Configuration of vibration element)
The vibration element 3 includes, for example, a crystal piece 15, a pair of excitation electrodes 17 for applying a voltage to the crystal piece 15 (one excitation electrode 17 is hidden by the crystal piece 15 and not shown), and the vibration element 3. It has a pair of extraction electrodes 19 for mounting on a pair of pads 11.

  The crystal piece 15 is formed in a substantially rectangular plate shape, for example. The crystal piece 15 is made of, for example, an AT cut crystal piece. In other words, the crystal piece 15 has an angle of 35 ° 15 ′ around the X axis (θ in the figure) in an orthogonal coordinate system consisting of the X axis (electrical axis), Y axis (mechanical axis), and Z axis (optical axis) of the crystal. In the orthogonal coordinate system composed of the X axis, Y ′ axis and Z ′ axis rotated in step (3), the flat plate is cut from the crystal along the XZ ′ plane. The crystal piece 15 has a rectangular shape having a long side parallel to the X axis and a short side parallel to the Z ′ axis, and has a thickness in the Y ′ axis direction.

  The pair of excitation electrodes 17 is provided in a layered manner on the center side of both main surfaces of the crystal piece 15, for example. The pair of extraction electrodes 19 are extracted from the excitation electrode 17 and provided at one end side portion of the crystal piece 15 in the longitudinal direction (X-axis direction). For example, the pair of excitation electrodes 17 and the pair of extraction electrodes 19 pass through the center (for example, the center of gravity) of the crystal piece 15 so that either of the main surfaces of the vibration element 3 may be the bottom surface side of the recess 5a. It is formed in a 180 ° rotationally symmetric shape with respect to a center line (not shown) extending in the longitudinal direction (D1-axis direction) of the crystal piece 15.

  The vibration element 3 is accommodated in the recess 5a with the main surface facing the bottom surface of the recess 5a. The extraction electrode 19 is joined to the pad 11 by a bump (not shown). Thereby, the vibration element 3 is supported by the element mounting member 5 like a cantilever. In addition, the pair of excitation electrodes 17 is electrically connected to the pair of pads 11, and thus is electrically connected to any two of the plurality of external terminals 13. The bump is made of, for example, a conductive adhesive.

  The conductive layer (pad 11, external terminal 13, excitation electrode 17, extraction electrode 19, etc.) is, for example, a metal layer. The conductive layer may be composed of one layer (one kind of material), or may be composed of a plurality of layers.

(Details of crystal shape)
As described above, the crystal piece 15 is formed in a substantially rectangular plate shape, and a pair of main surfaces 21 parallel to each other and a pair of long sides of the crystal piece 15 in a plan view of the main surface 21. It has a side surface 23 and a pair of end surfaces 25 constituting the short side of the crystal piece 15 in plan view of the main surface 21.

  FIG. 2A is a sectional view of the crystal piece 15 taken along the line IIa-IIa in FIG. FIG. 2B is a plan view showing an end portion of the crystal piece 15. FIG. 2C is a view showing the end face 25 of the crystal piece 15.

  The side surface 23 and the end surface 25 are basically constituted by a crystal plane, for example. Here, the roundness (chamfering) caused by the limit of processing accuracy at the corners of the crystal planes is ignored. The crystal plane is a plane formed at an angle unique to the single crystal (crystal) with respect to the orthogonal coordinate system XYZ (ZY′Z ′) due to the geometric regularity of the crystal lattice. For example, the side surface 23 and the end surface 25 may be configured by any crystal plane, for example, an m plane, an r plane, an R plane, or the like.

  Each of the side face 23 or the end face 25 may be constituted by one crystal face or may be constituted by a plurality of crystal faces. FIG. 2A illustrates an example in which each side surface 23 is configured by one crystal plane. Moreover, in FIG.2 (b) and FIG.2 (c), the aspect by which most of each end surface 25 was comprised by one crystal plane is illustrated. Note that each of the side surface 23 and the end surface 25 may include a surface other than the crystal surface by chamfering at a corner with another surface by an appropriate method.

  For example, the end surface 25 is provided with a protrusion 15p that protrudes in a direction in which the end surface 25 faces. In another aspect, the crystal piece 15 has a plate-like main body 15b and a protrusion 15p protruding from the main body 15b. In addition, the protrusion 15p may not be provided, and the entire crystal piece 15 may be configured by the main body 15b.

  For example, the protrusions 15p are provided at both ends of the end face 25 in the D3 axis direction, and two protrusions 15p are provided in total. The surface of each protrusion 15p is constituted by, for example, a plurality of (four in the illustrated example) crystal planes. 2B and 2C, the end of the crystal piece 15 opposite to the extraction electrode 19 is shown, but the end on the extraction electrode 19 side is also a specific crystal plane. It is the same except for various types.

  As will be described later, the protrusion 15p is a portion generated in order to make the method for manufacturing the crystal piece 15 suitable. Accordingly, the presence and absence, size, and the like are basically determined in association with setting of various conditions of a method for manufacturing the crystal piece 15 described later. However, for the purpose of expanding the arrangement area of the extraction electrode 19, the size and the like may be set from a viewpoint different from the manufacturing method. The base thickness (D2 axis direction) of the protrusion 15p is, for example, equal to the thickness between the pair of main surfaces 21.

(Outline of manufacturing method of crystal resonator element)
FIG. 3 is a flowchart showing an example of an outline of the procedure of the method for manufacturing the crystal resonator element 3 (crystal piece 15).

  First, in step ST1, a wafer 31 made of quartz (see FIG. 6B) is prepared. The wafer here may be a plate-like shape in which a large number of crystal pieces 15 are taken, and may not be a disc shape. For example, the planar shape of the wafer 31 may be a rectangle or the like.

  The preparation of the wafer 31 may be similar to a known method, for example. Specifically, for example, by performing lumbard processing and slicing on the artificial quartz, the wafer is cut out at the angle described with reference to FIG. Further, lapping, etching, and / or polishing are performed on the cut wafer, thereby forming a wafer 31 having a surface that becomes the main surface 21.

  In step ST <b> 2, a first mask 33 (see FIGS. 4A and 5) for etching the wafer 31 is formed on both main surfaces of the wafer 31. The first mask 33 is made of, for example, a metal film. The metal film may be composed of two or more layers made of different materials. The material of the metal film is, for example, chromium. The formation method of the 1st mask 33 may be the same as a well-known method except the specific shape of the 1st mask 33, for example. Specifically, for example, the first mask 33 is formed by depositing a conductive material by a sputtering method or a plating method through a resist mask formed by photolithography, or a conductive material is deposited. Later, the conductive film is etched through a resist mask.

  In step ST <b> 3, a second mask 35 (see FIGS. 4B and 5) for etching the wafer 31 is formed on the first mask 33. The second mask 35 is made of a resin such as a photoresist, for example. The photoresist may be either a positive type or a negative type. The method of forming the second mask 35 may be the same as a known method except for the specific shape of the second mask 35, for example. Specifically, for example, the second mask 35 is formed by patterning by photolithography after a photoresist film is formed by spin coating or the like.

  FIG. 3 illustrates the case where the step of forming the first mask 33 and the step of forming the second mask 35 are sequentially performed, but both may partially overlap. For example, after the formation of the conductive film to be the first mask 33 and the formation of the resist film to be the second mask 35, the first mask 33 and the second mask 35 are formed in the order of the resist film patterning and the conductive film patterning. It may be formed.

  In step ST4, wet etching is performed on the wafer 31 through the first mask 33 and the second mask 35 formed in steps ST2 and ST3. Thereby, the wafer 31 is separated into pieces and the crystal piece 15 is formed. Although not particularly illustrated, the first mask 33 and the second mask 35 are removed from the crystal piece 15 after being singulated. For example, the crystal piece 15 is immersed in an appropriate chemical solution for removing these masks.

  In step ST5, a pair of excitation electrodes 17 and a pair of extraction electrodes 19 are formed on the surface of the separated crystal piece 15. The method for forming these conductive layers may be the same as a known method, for example. Specifically, for example, these conductive layers are formed by forming a conductive material through a mask, or formed by etching through a mask after the conductive material is formed. .

  As described above, in the manufacturing method of this embodiment, the wafer 31 is separated into pieces by wet etching to obtain the crystal piece 15, and then the excitation electrode 17 and the extraction electrode 19 are formed on the crystal piece 15. .

(Planar shape of the first mask)
FIG. 4A is a plan view showing a part of the first mask 33 formed in step ST2.

  FIG. 4A shows only one of the two first masks 33 formed on both main surfaces of the wafer 31. However, the two first masks 33 basically have the same shape in plan perspective.

  The first mask 33 is formed with a plurality of openings 37 that expose the main surface of the wafer 31, and is partitioned by the plurality of openings 37, thereby providing a plurality of individual regions 39, a plurality of connection regions 41, and an outer region. 43 is formed.

  The plurality of openings 37 are each formed in a slit shape (groove shape), for example. For example, as will be understood from the description to be described later, the width is relatively lower under the plurality of openings 37 when wet etching is performed on at least both main surfaces of the wafer 31 through the plurality of openings 37. The size is such that the through-hole is quickly formed.

  The plurality of individual regions 39 are regions that overlap portions of the wafer 31 that become the plurality of crystal pieces 15 (main body portions 15b). Therefore, the planar shape and size of each piece region 39 are the same as those of the crystal piece 15 and are rectangular in this embodiment. The plurality of individual regions 39 may be appropriately arranged (arranged) in the wafer 31. In the present embodiment, the plurality of individual regions 39 are arranged vertically and horizontally in a direction parallel to the long side and the short side of the individual region 39.

  The outer region 43 is a region that overlaps the outer peripheral portion of the wafer 31, for example. From another viewpoint, the region is located outside the entire plurality of individual regions 39. Accordingly, the planar shape of the outer region 43 is, for example, a frame shape having the outer edge of the arrangement region of the plurality of individual regions 39 as the inner edge and the outer edge of the wafer 31 as the outer edge.

  Although not particularly illustrated, the first mask 33 may have a partition region 45 (which is a modified example, but see FIG. 11) extending so as to divide the inside of the outer region 43. In each of the plurality of regions divided by the outer region 43 and the partition region 45, a plurality of individual regions 39 may be arranged vertically and horizontally as illustrated.

  The plurality of connection regions 41 are regions for connecting the plurality of individual regions 39 directly or indirectly. In another aspect, the plurality of connection regions 41 are regions for connecting the plurality of individual regions 39 directly or indirectly to the outer region 43. As will be described later, the protrusion 15p is formed by providing the connection region 41.

  Specifically, for example, a part of the plurality of connection regions 41 is located between the individual region 39 adjacent to each other, and both ends thereof are connected to the individual region 39 adjacent to each other. That is, the some connection area | region 41 has connected several piece area | regions 39 directly. Further, the other part of the plurality of connection regions 41 is located between, for example, the outer region 43 (or the partition region 45) and the individual region 39 adjacent to the outer region 43, and both ends thereof are the outer region 43. And an individual region 39 adjacent to the outer region 43. That is, the other partial connection area 41 directly connects the individual area 39 to the outer area 43. In another aspect, the former indirectly connects the individual region 39 to the outer region 43 via the individual region 39 etc. connected to the outer region 43, and the latter via the outer region 43 etc. The individual regions 39 are indirectly connected to each other.

  The connection area 41 may extend from an appropriate position of the piece area 39. In the example shown in the figure, each piece region 39 extends from both ends of a pair of short sides. In another aspect, each piece region 39 is directly or indirectly connected to another piece region 39 (or the outer region 43) at four corners. In addition, the connection region 41 that connects the individual region 39 adjacent to each other is positioned between two short sides facing each other, and both ends thereof are connected to the two short sides.

  The planar shape of the connection region 41 may be set as appropriate. In the illustrated example, the connection region 41 is a rectangle extending with a certain width. Moreover, the extending direction is parallel to, for example, the long side of the individual region 39 (X axis from another viewpoint).

  The width of the connection region 41 may be appropriately set so that the side surface 23 and the end surface 25 of the crystal piece 15 are suitably etched, as will be understood from the description to be described later. The length of the connection region 41 is the same as the width of the opening 37 on the side (short side) where the connection region 41 of the piece region 39 is provided, and is set in association with the setting of the width of the opening 37. However, the length of the connection region 41 may be set preferentially for the purpose of making the protrusion 15p an arbitrary size, and the width of the opening 37 on the short side may be set accordingly.

(Planar shape of the second mask)
FIG. 4B is a plan view showing a part of the second mask 35 formed in step ST3.

  FIG. 4B shows only one of the two second masks 35 formed on both main surfaces of the wafer 31. However, the two second masks 35 basically have the same shape in plan perspective.

  The shape of the second mask 35 is, for example, a shape in which the connection region 41 is eliminated from the shape of the first mask 33. That is, the second mask 35 overlaps the whole of the plurality of individual regions 39 and the outer region 43 (and the partition region 45 when there is a partition region 45) of the first mask 33, and the plurality of the first mask 33. The opening 37 and the plurality of connection regions 41 are exposed.

(Cross sectional shape of the first mask and the second mask)
FIG. 5 is a cross-sectional view taken along line VV in FIG.

  As described above, in the present embodiment, the second mask 35 overlaps the entire individual region 39 of the first mask 33, and the edges of the two masks approximately coincide with each other.

  The second mask 35 is formed thicker than the first mask 33, for example. For example, the thickness of the first mask 33 is not less than 0.1 μm and not more than 0.3 μm, whereas the thickness of the second mask 35 is not less than 0.5 μm and not more than 3 μm. From another viewpoint, for example, the thickness of the second mask 35 is not less than 5 times and not more than 20 times the thickness of the first mask 33.

  The first mask 33 and the second mask 35 constitute a composite mask 47 for etching.

(Progress of wet etching)
With reference to FIG. 6A to FIG. 8D, the progress of wet etching will be described. In the following description, even if the shape changes with the progress of etching, the same symbol may be used before and after the change.

  6A and 6B are a cross-sectional view and a plan view of the wafer 31 when the wet etching is started. FIG. 6A corresponds to a cross-sectional view taken along the line VIa-VIa in FIG. In these drawings, for the sake of convenience, a small number of crystal pieces 15 taken from the wafer 31 are shown. In FIG. 6A, the composite mask 47 is shown without distinguishing the first mask 33 and the second mask 35. In FIG. 6B, only the wafer 31 is shown without showing the composite mask 47.

  As shown in FIG. 6A, the wafer 31 is immersed in the chemical solution 51 in the chemical solution tank 49. At this time, the wafer 31 is held by an appropriate jig 53 (FIG. 6B). As a result, the wafer 31 (the composite mask 47 provided on both main surfaces thereof) is held at an appropriate height in the chemical liquid 51 and is separated from the bottom surface of the chemical liquid tank 49 and away from the liquid surface of the chemical liquid 51. Yes.

  The jig 53 holds, for example, the outer peripheral portion of the wafer 31 (the portion where the outer region 43 (FIG. 4A) of the first mask 33 overlaps). The holding may be performed by an appropriate method such as clamping. The number of holding positions of the jig 53 may also be set as appropriate.

  Although not particularly shown, the wafer 31 may be vibrated by moving the chemical solution 51 and / or moving the jig 53 while the wafer 31 is immersed in the chemical solution 51. . That is, the relative flow of the chemical 51 with respect to the wafer 31 may be positively generated. Further, this relative flow may be formed in an appropriate period of the processes shown in FIGS. 6 (a) to 7 (d).

  FIGS. 6C and 6D are views similar to FIGS. 6A and 6B when the wet etching proceeds to some extent. FIG. 6C corresponds to a cross-sectional view taken along line VIc-VIc in FIG.

  The wafer 31 is etched through the plurality of openings 37 of the first mask 33 (and openings corresponding to the openings 37 of the second mask 35), so that the wafer 31 has a planar shape substantially similar to the plurality of openings 37. Through-holes are formed. Thereby, for example, the outer shape of the crystal piece 15 in plan view is substantially formed.

  However, since the piece region 39 is directly or indirectly connected to the outer region 43 via the connection region 41, the crystal piece 15 is connected via a portion of the wafer 31 below the connection region 41. Directly or indirectly connected to the outer periphery of the wafer 31. Therefore, the crystal piece 15 is indirectly held by the jig 53 continuously before etching, and as a result, is maintained at an appropriate height in the chemical solution tank 49.

  7A and 7B are a sectional view and a plan view showing a part of the wafer 31 when the wet etching further proceeds. Note that FIG. 7A corresponds to a cross-sectional view taken along line VIIa-VIIa in FIG.

  As wet etching progresses, so-called side etching occurs in which the inner peripheral surface of the hole is etched in addition to the normal etching in which a hole is formed below the opening 37. Accordingly, etching is performed around the opening 37 even in the region overlapping the first mask 33.

  As a result, for example, as indicated by an arrow y1, a portion of the wafer 31 located under the connection region 41 of the first mask 33 is etched and becomes thinner. Here, since the second mask 35 does not overlap on the connection region 41, the connection region 41 is more easily peeled off from the wafer 31 than other regions of the first mask 33. As a result, side etching proceeds under the connection region 41 more than under other regions.

  FIGS. 7C and 7D are views similar to FIGS. 6A and 6B when the wet etching further proceeds. FIG. 7C corresponds to a cross-sectional view taken along the line VIIc-VIIc in FIG.

  As the side etching under the connection region 41 of the first mask 33 proceeds as described above, the portion of the wafer 31 below the connection region 41 is interrupted, and the plurality of crystal pieces 15 are separated into pieces. Since the separated crystal pieces 15 are not held by the jig 53, for example, the crystal pieces 15 sink in the chemical solution 51.

  Note that side etching can also occur under a region other than the connection region 41 in the first mask 33. However, for example, since the connection region 41 is formed to be relatively thin, the singulation is performed before the side etching under other regions proceeds excessively. In addition, since the second mask 35 does not overlap the connection region 41 as described above, side etching is more likely to occur under the connection region 41 than under other regions, and side etching under the other region. It is singulated before it progresses excessively.

  Thereafter, the etching is finished. The etching may be terminated immediately after singulation, or may be continued for a certain period of time after singulation. The etching may be terminated by, for example, taking out the crystal piece 15 from the chemical solution tank 49 or by discharging the chemical solution from the chemical solution tank 49. The crystal piece 15 may be taken out from the chemical solution tank 49 as appropriate. For example, the crystal piece 15 may be picked up by a net (not shown) arranged under the chemical solution tank 49.

  As described above, in the wet etching according to the present embodiment, the planar shape of the crystal piece 15 is formed, and the crystal pieces 15 are separated. Further, the singulation is not performed by normal etching in the opening 37 of the first mask 33 but by side etching under the connection region 41 of the first mask 33. Therefore, for example, etching or the like through the opening 37 is sufficiently performed before separation.

  Further, since the planar shape of the crystal piece 15 is formed by wet etching, the side surface 23 and the end surface 25 that appear by the etching are configured by crystal planes as is well known. The protrusion 15p is not formed by breaking the portion of the wafer 31 below the connection region 41, but is formed by separation by side etching, so that the surface thereof is the same as the side surface 23 and the like. , Constituted by crystal planes.

  2B and 2C exemplify a case where a portion of the wafer 31 below the connection region 41 remains even after being singulated to form a protrusion 15p. However, as described above, the etching may be continued even after separation, and in this case, the protrusion 15p may be removed by further etching.

  When the protrusions 15p are formed on the pair of end faces 25 (short sides) of the crystal piece 15, the both end faces 25 are in different directions with respect to the crystal axis (on the AT cut plate, the positive side and the negative side of the X axis) Therefore, the shape of the protrusions 15p is different from each other on the pair of end faces 25. In other words, the positive side and the negative side of the X axis can be specified from the shape of the protrusion 15p.

  Depending on the shape and relative position of the crystal piece 15, the excitation electrode 17 and the extraction electrode 19, the positive and negative of the D1 axis direction defining the shape and relative position is the same as the positive and negative of the X axis direction based on the crystal axis The frequency temperature characteristics and the like may be slightly different in the opposite case. In such a case, the positive / negative in the X-axis direction may be specified based on the shape of the protrusion 15p, and the relationship between the positive / negative in the D1-axis direction and the positive / negative in the X-axis direction may be matched with a predetermined relationship.

  FIG. 8A to FIG. 8D are cross-sectional views showing the progress of etching in the opening 37. As shown in FIG. 5, this cross-sectional view is a cross-section orthogonal to the direction in which the opening 37 extends in a slit shape. However, since these drawings are schematic diagrams, the aspect ratio and the like are different between FIGS. 8A to 8D and FIG.

  FIG. 8A shows a state at the start of etching. This state corresponds to the state shown in FIGS. 6 (a) and 6 (b). As already described, the first mask 33 and the second mask 35 are laminated on both main surfaces of the wafer 31, and both main surfaces of the wafer 31 are exposed from the opening 37.

  FIG. 8B shows a state where the etching has progressed to some extent, but the hole under the opening 37 is still a recess (a state where it is not a through hole). This state corresponds to a state between the state of FIGS. 6A and 6B and the state of FIGS. 6C and 6D.

  Due to the anisotropy of the crystal with respect to wet etching, the inner peripheral surface (inner wall surface) of the recess under the opening 37 is constituted by the crystal surface. As a result, the concave portion does not normally have a shape whose diameter is constant in the depth direction (rectangular in a cross-sectional view). For example, as shown in the drawing, the recess is formed in a trapezoidal shape with the first crystal face 55 and the second crystal face 57 as legs in a cross-sectional view.

  Since the recesses on both main surfaces have etching directions opposite to each other, the crystal planes facing in different directions are usually present on the same side in the width direction (left-right direction on the paper surface) in a sectional view. appear. For example, the crystal plane (55) on the right side of the concave portion above the paper plane and the crystal plane (57) on the right side of the concave section below the paper plane face in different directions.

  In the present embodiment, an AT cut plate is taken as an example, and FIGS. 8A to 8D are cross sections orthogonal to the X-axis direction. Accordingly, the crystal plane on the right side of the concave portion above the paper plane and the crystal plane on the left side of the concave section below the paper plane are the first crystal planes 55 having different surface orientations and the same inclination angle. Further, the crystal plane on the left side of the concave portion above the paper plane and the crystal plane on the right side of the concave section below the paper plane are second crystal planes 57 having different surface orientations and the same inclination angle.

  FIG. 8C shows a state where the etching has further progressed. This state corresponds to, for example, the states of FIGS. 6C and 6D (however, a relatively initial state).

  When the concave portion under the opening 37 becomes deeper so as to extend the trapezoidal leg, the concave portions on both main surfaces of the wafer 31 are connected to each other, and a through hole is formed. Immediately after this connection, a trapezoidal shape remains. And in the recessed part of both main surfaces, as above-mentioned, even if it is the same side of the width direction (paper surface left-right direction), the crystal plane which faces mutually different direction appears in sectional view. Therefore, immediately after the penetration, each surface of the side surface 23 or the end surface 25 is in a state where two or more crystal faces are mixed, and a protrusion is formed as shown in the figure.

  As can be understood from FIGS. 8B and 8C, when the width of the opening 37 is narrow, the legs of the recesses come into contact with each other before the recesses on both main surfaces of the wafer 31 are connected (see FIG. 8B and FIG. 8C). A triangular recess is formed in cross-sectional view.) Then, the etching rate rapidly decreases. Therefore, it is preferable that the width of the opening 37 is set to be relatively wide so that the legs of the recesses do not contact each other.

  FIG. 8D shows a state where the etching has further progressed. This state corresponds to, for example, the state shown in FIGS. 7C and 7D (for example, immediately after singulation).

  As the etching proceeds, the protrusions on the side surface 23 or the end surface 25 shown in FIG. 8C are removed. For example, the side surface 23 or the end surface 25 is configured by one crystal plane (the first crystal plane 55 in the illustrated example). Thereby, for example, the shape of the side surface 23 and the end surface 25 is simplified, and the possibility that unintended unnecessary vibrations are generated is reduced. In addition, for example, it is easy to form the extraction electrode 19 or a wiring (not shown) extending from the extraction electrode 19 on the side surface 23 and / or the end surface 25. Note that the side surface 23 and the end surface 25 may be finally composed of two or more crystal planes as a result of sufficient etching.

  As described above, in the method of manufacturing the crystal blank 15 according to the present embodiment, the first mask forming step (step ST2) for forming the first mask 33 on both main surfaces of the wafer 31 and the first mask 33 are provided. An etching step (step ST4) in which the wafer 31 is immersed in the chemical solution 51 to perform wet etching. The first mask 33 is partitioned by a plurality of openings 37 that expose the main surface of the wafer 31, whereby a plurality of individual regions 39 that overlap with portions of the wafer 31 that become the plurality of crystal pieces 15, and a plurality of individual pieces. A plurality of connecting regions 41 extending from the region 39 and connecting the plurality of individual regions 39 directly or indirectly. The etching step is performed after the portions under the plurality of openings 37 in the wafer 31 are etched to form through holes (after FIG. 6 (c), FIG. 6 (d) and FIG. 8 (c)). The portions under the plurality of connection regions 41 of the wafer 31 are etched by side etching (FIGS. 7A and 7B), and the plurality of crystal pieces 15 are singulated (FIG. 7C). ) And FIG. 7 (d)).

  Therefore, as described above, the time when the portion below the connection region 41 is separated by side etching and the wafer 31 is separated into pieces is around the piece region 39 (except for the connection position with the connection region 41). It is later than the time (FIG. 8C) when the through hole is opened by normal etching. Here, as described with reference to FIGS. 8C and 8D, in order to form the side surface 23 and the end surface 25 in a desired shape, the through-hole is simply opened by ordinary etching. In some cases, it may be preferable to further perform etching. Then, a state in which a plurality of crystal pieces 15 are connected as compared with the case where the connection region 41 is not provided by the time of singulation being delayed from the time when the through hole is opened around the individual region 39. The etching time for the side surface 23 and the end surface 25 of the crystal piece 15 can be increased. In other words, the etching time of the side surface 23 and the end surface 25 of the crystal piece 15 after being singulated can be shortened or eliminated.

  In the etching after being separated into pieces, for example, the manner in which the crystal piece 15 contacts the bottom surface of the chemical solution tank 49, the manner in which the crystal piece 15 flows when there is a flow of the chemical solution 51, etc. There is a high probability of variations. As a result, for example, there is a high probability that the degree of progress of etching varies between the crystal pieces 15, or the surface where the degree of progress of etching among the plurality of surfaces of the crystal piece 15 is different between the plurality of crystal pieces 15. . However, in the present embodiment, as described above, the etching time of the side surface 23 and the end surface 25 after being separated into pieces can be shortened or eliminated, so that such a probability can be reduced.

  In addition, even if the connection area | region 41 is comparatively thin and singulation is made comparatively early, compared with the case where the connection area | region 41 is not provided, said effect is produced somewhat. Further, even if the wafer 31 is not held in the chemical solution 51 by the jig 53, the above-described effects are exhibited because variations in the posture of the crystal pieces 15 with respect to the chemical solution tank 49 are suppressed.

  By providing the connection region 41, the protrusion 15p is formed when etching is immediately finished after separation or when the etching time after separation is relatively short. Here, unlike this embodiment, for example, as in Patent Document 1, the wafer state is maintained by not performing side etching under the connection region 41, and the excitation electrode 17 is formed on the crystal piece 15. Even in the manufacturing method in which the portion under the region 41 is folded, a protrusion is formed under the connecting region 41. Since this conventional protrusion is formed by breaking (brittle fracture), its tip shape is difficult to predict and tends to vary between the plurality of crystal pieces 15, and burrs are generated at the tip. It's easy to do. As a result, it is difficult to predict the effect of the protrusions on the vibration of the crystal piece 15, and the vibration tends to vary between the crystal pieces 15. On the other hand, the protrusion 15p of the present embodiment is constituted by a crystal plane that appears by etching. Therefore, the tip shape of the protrusion 15p is, for example, easy to predict and the variation between the crystal pieces 15 is suppressed, and no burrs are generated. As a result, the vibration characteristic of the crystal piece 15 is stabilized.

  In the present embodiment, the first mask 33 has an outer region 43 that overlaps the outer periphery of the wafer 31. The plurality of individual regions 39 are connected to the outer region 43 directly or indirectly by the plurality of connecting regions 41. In the etching step, the wafer 31 is immersed in the chemical solution in a state where the outer peripheral portion of the wafer 31 is held and the inner portion of the wafer 31 is separated from the bottom surface of the chemical bath 49 and the liquid surface of the chemical solution 51 ( 6 (a) to 6 (d)).

  Therefore, in the present embodiment, the plurality of crystal pieces 15 are held through the outer peripheral portion of the wafer 31 until they are separated into pieces, and are separated from the bottom surface of the chemical solution tank 49 and the liquid level of the chemical solution 51. Is maintained. Here, when the crystal piece 15 is singulated, the crystal piece 15 sinks and comes into contact with the bottom surface of the chemical solution tank 49 or floats and comes into contact with the liquid surface of the chemical solution 51 (the former is a common chemical solution). . When the crystal piece 15 comes into contact with the bottom surface of the chemical solution tank 49 or the liquid level of the chemical solution 51, the diffusion state of the reactive substance and / or the flow of the chemical solution 51 around the crystal piece 15 is the same as when the crystal piece 15 is in the chemical solution 51 Will be different. As a result, the progress rate of the etching of the crystal piece 15 changes before and after the singulation. As a result, for example, it becomes difficult to grasp the correlation between the etching progress of the side surface 23 and the end surface 25 of the crystal piece 15 and the etching time. Further, for example, the crystal piece 15 is moved by vibrating the wafer 31, so that a relative flow of the chemical solution 51 with respect to the crystal piece 15 cannot be generated. However, as described above, in the present embodiment, since the plurality of crystal pieces 15 are held at appropriate positions by the jig 53 or the like until they are separated into individual pieces, such inconvenience is solved.

  In the present embodiment, there is further provided a second mask forming step (step ST3) for forming a second mask 35 on the first mask 33 so as to overlap the plurality of individual regions 39 and expose the plurality of openings 37. ing. The second mask 35 exposes the plurality of connection regions 41.

  Therefore, for example, as already described, the connection region 41 is easier to peel from the wafer 31 than the individual region 39. As a result, for example, side etching is easier to proceed under the connection region 41 than under the piece region 39. Then, while suppressing excessive side etching under the individual piece region 39, the portion under the connection region 41 can be separated and the crystal piece 15 can be singulated.

  In the present embodiment, the second mask 35 overlaps each of the plurality of individual regions 39.

  Therefore, each piece region 39 is prevented from being peeled off from the wafer 31 with respect to the whole, and as a result, side etching is suppressed. As a result, for example, it is easier to grasp the correspondence between the shape of the piece region 39 and the planar shape of the crystal piece 15 as compared with the second embodiment described later. Easy to adjust.

  In the present embodiment, the first mask 33 is made of a metal film, and the second mask 35 is made of a resist film that is thicker than the metal film.

  Therefore, for example, in the non-arrangement region of the second mask 35, the first mask 33 is easily displaced so as to fall from the wafer 31 compared to the arrangement region of the second mask 35. The chemical 51 is likely to enter between the wafer 31. As a result, for example, the effect of suppressing the side etching in the individual region 39 that is the arrangement region of the second mask 35 while promoting the side etching in the connection region 41 that is the non-arrangement region of the second mask 35 described above. It is suitably realized.

  Moreover, in this embodiment, the some connection area | region 41 contains what connected both ends between two mutually opposing sides of the piece area | region 39 mutually adjacent, and connects the piece area | regions 39 directly.

  That is, some of the plurality of individual regions 39 are not directly connected to the outer region 43 or the partition region 45. As a result, for example, the partition area 45 can be made unnecessary, and the number of crystal pieces 15 that can be taken out from the wafer 31 can be increased by the amount that the partition area 45 is eliminated. Unlike the present embodiment, when the crystal piece 15 is folded from the outer region 43 and the partition region 45 as in the prior art, the outer region 43 and the partition region 45 are firmly supported and compared with the crystal piece 15. Therefore, it is very difficult to directly connect the individual regions 39 as in the present embodiment. That is, the structure and effect are realized by separating the wafer 31 into pieces by wet etching.

  In the present embodiment, the plurality of individual regions 39 are each rectangular, and the plurality of connection regions 41 extend from both ends of the short sides of the plurality of individual regions 39.

  Therefore, for example, when a residue is generated in the vicinity of the connection region 41, the residue can be separated from a position that easily affects vibration such as the center of the long side or the center of the short side. Further, for example, if it is assumed that the connection region 41 is not provided, the corner portion of the individual region 39 is side-etched from both the short side direction and the long side direction and is excessively chamfered. There is a fear. However, such inconvenience can be eliminated by the presence of the connection region 41. That is, excessive chamfering can be suppressed by conversely using the connection region 41 that may cause a residue. For example, when the protrusion 15p is formed, the protrusion 15p is located on the side of the crystal piece 15 where a space is secured for the arrangement of the extraction electrode 19 (that is, the short side). The influence on the vibration is reduced, and it can be used for the arrangement of the extraction electrode 19.

  In addition, the crystal element 15 for the vibration element of the present embodiment includes a plate-shaped main body 15b and a protrusion 15p that protrudes from the outer peripheral surface (end surface 25 in the present embodiment) of the main body 15b. . The tip surface of the protrusion 15p is constituted by a crystal plane. The crystal resonator element 3 of the present embodiment includes the crystal piece 15 of the present embodiment and the excitation electrodes 17 located on both surfaces of the main body portion 15b. The crystal resonator 1 of the present embodiment includes the crystal resonator element 3 of the present embodiment and an element mounting member 5 (mounting base) on which the crystal resonator element 3 is mounted.

  Therefore, the manufacturing method of the crystal piece 15 of this embodiment mentioned above can be utilized. Further, as already mentioned, since the tip surface of the projection 15p of the crystal piece 15 is constituted by a crystal face, the variation in the tip shape is small compared to the fracture surface due to brittle fracture, and the crystal piece 15 Vibration characteristics are stable. As a result, the electrical characteristics of the vibrator 1 are stabilized.

Second Embodiment
FIG. 9A is a diagram for explaining a method of manufacturing the crystal piece 15 according to the second embodiment. Specifically, FIG. 9A is a plan view showing a part of the second mask 235 of the present embodiment, and corresponds to FIG. 4B of the first embodiment. FIG. 9B is a cross-sectional view taken along the line IXb-IXb in FIG. 9A and corresponds to FIG. 5 of the first embodiment.

  The manufacturing method of the second embodiment is different from the manufacturing method of the first embodiment only in the shape of the second mask. Specifically, the second mask 35 of the first embodiment covers the entire individual area 39 of the first mask 33, whereas the second mask 235 of the present embodiment has the individual area 39. Only the central side portion is covered, and the outer peripheral side portion of the piece region 39 is exposed. The width with which the second mask 235 exposes the individual region 39 may be appropriately set according to the effect to be obtained (described later).

  FIG. 10A and FIG. 10B are cross-sectional views for explaining an example of the effect of this embodiment, and correspond to FIG. 8C and FIG. 8D of the first embodiment. Yes.

  As shown in FIG. 10A, also in the present embodiment, through holes are formed when the concave portions formed below the opening 37 are partially communicated on both main surfaces of the wafer 31. The shape of the concave portion is, for example, a trapezoidal shape with the first crystal face 55 and the second crystal face 57 as legs in a cross-sectional view, as in the first embodiment. However, in FIG. 10A, the first crystal face 55 is shown tilted from FIG. 8C.

  When the etching further proceeds, as shown in FIG. 10B, the protrusions on the side surface 23 or the end surface 25 caused by the shape of the concave portions on both main surfaces of the wafer 31 are removed. For example, the side surface 23 or the end surface 25 is configured by one crystal plane (in the illustrated example, the first crystal plane 55), as in the first embodiment.

  At this time, when the first crystal plane 55 is not perpendicular or nearly perpendicular to the main surface and is relatively inclined, in order to completely remove the protrusion, as shown in FIG. In addition, the etching needs to proceed to the bottom of the first mask 33 by side etching. On the other hand, in the present embodiment, since the outer peripheral portion of the piece region 39 is exposed from the second mask 35, the chemical solution 61 is peeled from the wafer 31 and the chemical solution 61 is placed between the wafer 31 and the connection region 41. Easy to invade. Therefore, it is possible to suitably cause side etching to obtain a state as shown in FIG.

  10A does not show the side etching under the first mask 33 for the sake of convenience of explanation, the side etching under the first mask 33 may be performed to some extent at the time of FIG. 10A. Good. Further, in FIG. 10B, for convenience of explanation, side etching under the first mask 33 is not shown on the side where the second crystal face 57 appears, but on the side where the second crystal face 57 appears. However, side etching may occur.

  In FIG. 10B, the width of the first mask 33 (piece region 39) exposed from the second mask 35 is set wider than the width that causes side etching. However, the exposed width may be equal to or smaller than the width that causes side etching. The exposed width may be appropriately set according to the ease of peeling of the first mask 33, the etching time, and the like.

  FIG.10 (c) is sectional drawing for demonstrating the example of an effect different from the example of the effect of FIG.10 (b), and is equivalent to FIG.10 (b). In this figure, the first crystal plane 55 is drawn vertically as in FIG. 8D and the like.

  Depending on the type of chemical 61 and the etching time, the portion of the first mask 33 exposed from the second mask 35 is also etched. As a result, in addition to the etching under the original opening 37, the wafer 31 is also etched under the opening 38 in which the opening 37 is enlarged. As a result, the side surface 23 or the end surface 25 is formed with a so-called mesa shape in which the center side in the thickness direction protrudes. Thus, the part exposed from the 2nd mask 35 of the piece area | region 39 may be utilized for formation of a mesa shape.

  FIG. 10C illustrates a case where a mesa shape is formed in a stepwise manner in a cross-sectional view by two-stage etching of etching under the opening 37 and etching under the opening 38. However, the mesa shape may be formed in a curved shape in a cross-sectional view by gradually peeling and removing the first mask 33.

  As described above, also in the second embodiment, the first mask 33 has the plurality of connection regions 41, and the etching step (ST4) etches the portion of the wafer 31 below the plurality of connection regions 41 by side etching. Since this is continued until the plurality of crystal pieces 15 are singulated, the same effects as those of the first embodiment are obtained. For example, the crystal piece 15 can be separated into pieces by wet etching, and the side face 23 and the end face 25 can be etched with high accuracy by delaying the piece separation time.

  Further, in the present embodiment, the second mask 235 overlaps the center side portion of each of the plurality of individual regions 39 and exposes the outer peripheral side portion of each of the plurality of individual regions 39. Therefore, for example, as described with reference to FIG. 10B, side etching is also performed around the individual region 39 to form a suitable side surface 23 or end surface 25, or FIG. As described with reference, a mesa shape can be realized.

(Modification)
FIG. 11A is a plan view showing a part of the first mask 101 according to the modification.

  In the first mask 33 of the embodiment, the connection region 41 extends from both ends of the short side of the individual region 39. On the other hand, in the first mask 101 of the modified example, the connection region 41 extends from the center of the short side of the piece region 39. Thus, the connection area 41 may extend from an appropriate position. As described above, from the viewpoint of reducing the influence of the residue on the vibration and suppressing excessive chamfering at the corner, the connecting region 41 has both ends of the short side as shown in the embodiment. It is preferable that it is located in.

  FIG. 11B is a plan view showing a part of the first mask 103 according to another modification.

  In the first mask 33 of the embodiment, the plurality of connection regions 41 include those that are located between the plurality of individual regions 39 and directly connect the plurality of individual regions 39 to each other. On the other hand, in the first mask 103 of the modification example, all the connection regions 41 are between the individual region 39 and the outer region 43 or the partition region 45 (the partition region 45 extending in the left-right direction in the drawing). The individual piece region 39 and the outer region 43 or the partition region 45 are directly connected to each other. In other words, all the individual regions 39 are indirectly connected to each other via the outer region 43 and the partition region 45.

  As described above, the plurality of individual regions 39 may not be directly connected by the connection region 41. In such a case, for example, it is easier to ensure the strength of the wafer 31 than in the embodiment. In the embodiment, as described above, for example, a part or all of the partition region 45 can be eliminated, so that the number of the individual regions 39 can be increased.

  In the above embodiment, the crystal piece 15 is an example of a piezoelectric piece. Each of the first masks 33, 101, and 103 is an example of a first etching mask. Each of the second masks 35 and 235 is an example of a second etching mask. The crystal resonator element 3 is an example of a piezoelectric resonator element. The crystal resonator 1 is an example of a piezoelectric vibration device. The element mounting member 5 is an example of a mounting substrate.

  The present invention is not limited to the above embodiment, and may be implemented in various aspects.

  The piezoelectric vibration device is not limited to the piezoelectric vibrator, and may be a piezoelectric oscillator including an oscillation circuit, for example. The piezoelectric vibrator may include components other than the piezoelectric vibration element such as a thermistor. The structure of the piezoelectric vibrator or the piezoelectric oscillator is not limited to that illustrated in the embodiment, and may be an appropriate structure such as one having an H-type element mounting member.

  The piezoelectric piece for piezoelectric vibration including the plate-like main body is not limited to the AT-cut one, and may be, for example, a BT-cut or GT-cut one. The plate-shaped main body (in another aspect, the individual region of the first etching mask) is not limited to a rectangle, and may be, for example, a polygon other than a circle, an oval, an ellipse, a square, or a quadrangle. . The material constituting the piezoelectric piece is not limited to quartz, and may be, for example, a polycrystalline body or a single crystal body other than quartz. The method for manufacturing the piezoelectric piece is not limited to the one for manufacturing the plate-like piezoelectric piece, and may be, for example, for forming a tuning fork type piezoelectric piece.

  As described in the embodiment, since the protrusion (15p) is formed by etching, the adverse effect of the protrusion on the vibration characteristics is reduced, and the protrusion is sufficient even after being singulated by etching. It may be removed by continuing the etching. From another viewpoint, a process different from the etching for removing the protrusion is not necessary. However, the protrusion may be removed by a process different from the etching.

  As mentioned in the description of the first embodiment, from the viewpoint of suppressing the etching accuracy from being varied between a plurality of piezoelectric pieces due to the etching after dividing into pieces, the wafer has an outer periphery held inside ( The portion where a plurality of piezoelectric pieces are formed) does not have to be held in the chemical solution (position floating from the chemical solution tank). For example, the wafer may sink to the bottom of the chemical bath. In this case, for example, the first etching mask (33) may not have the outer region (43). For example, the first etching mask may have a configuration including only a plurality of individual regions (39) and a plurality of connection regions (41) that directly connect the plurality of individual regions to each other.

  In the case where the outer peripheral portion of the wafer is held, the holding method is not limited to using a jig. For example, a pedestal for supporting the outer peripheral portion of the wafer may be provided at the bottom of the chemical solution tank, and thereby the outer peripheral portion of the wafer may be held (including simply supported). Further, the wafer may not be arranged horizontally, and may be arranged vertically. In such a case, the outer peripheral portion of the wafer may be held by contacting an appropriate member with the outer peripheral surface of the wafer. Further, the wafer may be supported at a portion other than the outer peripheral portion. The jig may serve as a mask that suppresses etching of the outer region and the like.

  In the case where the outer region (43) is provided in the first mask, the outer region has a frame-like shape (as shown in FIG. 6D) because the jig 53 holds the wafer 31 at two locations. It may not be an annular shape, and may be a pair of regions sandwiching a plurality of individual regions (39).

  DESCRIPTION OF SYMBOLS 1 ... Crystal oscillator (piezoelectric oscillating device), 3 ... Crystal oscillating element (piezoelectric oscillating element), 5 ... Crystal piece (piezoelectric piece), 31 ... Wafer, 33 ... 1st mask (1st etching mask), 35 ... 1st 2 masks (second etching mask), 37... Opening, 39... Individual region, 41 .. connection region, 43.

Claims (11)

A first mask forming step of forming a first etching mask on both main surfaces of the wafer;
An etching step of performing wet etching by immersing the wafer provided with the first etching mask in a chemical solution;
Have
The first etching mask is delimited by a plurality of openings exposing the main surface of the wafer,
A plurality of individual regions overlying a portion to be a plurality of piezoelectric pieces of the wafer;
A plurality of connecting regions extending from the plurality of individual regions and connecting the plurality of individual regions directly or indirectly, and
In the etching step, after the portions under the plurality of openings of the wafer are etched to form through holes, the portions under the plurality of connection regions of the wafer are etched by side etching. A method of manufacturing a piezoelectric piece, which is continued until the plurality of piezoelectric pieces are separated. The first etching mask has an outer region that overlaps an outer peripheral portion of the wafer,
The plurality of individual regions are directly or indirectly connected to the outer region by the plurality of connecting regions,
In the etching step, the wafer is immersed in a chemical solution in a state where the outer peripheral portion of the wafer is held and a portion inside the outer peripheral portion of the wafer is separated from a bottom surface of a chemical bath and a liquid level of the chemical solution. Item 2. A method for manufacturing a piezoelectric piece according to Item 1. A second mask forming step of forming a second etching mask on the first etching mask so as to overlap the plurality of individual regions and expose the plurality of openings;
The method for manufacturing a piezoelectric piece according to claim 1, wherein the second etching mask exposes the plurality of connection regions. The method for manufacturing a piezoelectric piece according to claim 3, wherein the second etching mask overlaps each of the plurality of individual regions. 4. The method of manufacturing a piezoelectric piece according to claim 3, wherein the second etching mask overlaps a central portion of each of the plurality of individual regions and exposes an outer peripheral side portion of each of the plurality of individual regions. 5. . The first etching mask is made of a metal film,
The method for manufacturing a piezoelectric piece according to claim 3, wherein the second etching mask is made of a resist film thicker than the metal film. The plurality of connection regions include one in which both ends are connected between two opposing sides of the individual region adjacent to each other, and the individual regions are directly connected to each other. The manufacturing method of the piezoelectric piece of description. The plurality of individual regions are each rectangular.
The method for manufacturing a piezoelectric piece according to claim 1, wherein the plurality of connection regions extend from both ends of a short side of the plurality of individual piece regions. A plate-like body,
A protrusion protruding from the outer peripheral surface of the main body,
Have
A piezoelectric piece for a vibration element, wherein a tip end surface of the protrusion is constituted by a crystal plane. A piezoelectric element for a vibration element according to claim 9,
Excitation electrodes located on both sides of the main body,
A piezoelectric vibration element having The vibration element according to claim 10,
A mounting substrate on which the vibration element is mounted;
A piezoelectric vibration device having:

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