Crystal piece, crystal device using the same, intermediate wafer for crystal device

Abstract

To provide a crystal piece which is an appropriate and novel shape for use for manufacturing a crystal device.SOLUTION: A crystal piece 10 is an AT cut crystal piece which defines an X-Z' plane specified by an X axis of a crystal and a Z' axis of the crystal as principal surfaces 10ca and 10cb, defines a Y' axis of the crystal as a thickness direction, and has a rectangular shape in a planar view. When one of side faces at both ends along the X axis is defined as a first side face 10aa of the X axis, the other is defined as a second side face 10ab of the X axis, one of side faces at both ends along the Z' axis is defined as a first side face 10ba of a second axis and the other is defined as a second side face 10bb of the second axis, each of the side faces are composed of a crystal plane 10e derived from the crystal and a non-crystal plane which is a non-crystal plane 10f and has a contour 10fa in parallel with a normal 10cc of the principal surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a quartz crystal piece suitable for use in manufacturing quartz crystal devices such as quartz crystal resonators, quartz crystal resonators with temperature sensors, and quartz crystal oscillators (including quartz crystal oscillators with temperature compensation functions), as well as to the quartz crystal devices and intermediate wafers suitable for use in manufacturing the quartz crystal devices. [Background technology]

[0002] As communication devices become smaller and operate at higher frequencies, it becomes increasingly necessary to make crystal devices, which are the frequency reference sources for communication devices, smaller and higher in frequency. Therefore, it is desirable for the crystal pieces constituting the crystal devices to be small and thin. As a manufacturing technique for such crystal pieces, a widely used technique is to manufacture AT-cut crystal pieces using photolithography and wet etching techniques. Examples of this are described in, for example, paragraphs 42-48 and FIG. 3 of Patent Document 1, and in, for example, paragraphs 42-46 and FIG. 3 of Patent Document 2.

[0003] The quartz crystal piece disclosed in Patent Document 1 has a +X side of both ends along the X-axis of the quartz crystal that is made up of six crystal planes, and a -X side that is made up of two crystal planes. The quartz crystal piece disclosed in Patent Document 2 has both ends along the Z-axis of the quartz crystal that are made up of four crystal planes. In the techniques of Patent Documents 1 and 2, the above-mentioned side faces are formed by over-etching the quartz crystal piece by 10% or more of its thickness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-27505 A [Patent Document 2] JP 2014-27506 A Summary of the Invention [Problem to be solved by the invention]

[0005] Photolithography and wet etching are certainly useful techniques for miniaturizing quartz crystal pieces and increasing their frequency, but in the case of these techniques, the outer shape of the quartz crystal piece may end up being a shape that impairs the characteristics of the quartz crystal device due to the anisotropy of the crystal axis of the quartz crystal. For example, as described in Patent Documents 1 and 2, the side surface of a quartz crystal blank formed by photolithography and wet etching techniques is often composed of an inclined surface inclined with respect to the main surface of the quartz crystal blank due to the crystallinity of the quartz crystal. On the other hand, the vibration region of the quartz crystal blank is the part where the main surface faces, and the part with the inclined surface does not function as a vibration region. Therefore, the more inclined surfaces the side surface has, the narrower the vibration region becomes, which may not be desirable in terms of improving the characteristics of the quartz crystal device. This problem may become more serious as the size of the quartz crystal device becomes smaller, as the shape of the quartz crystal blank itself becomes smaller. This application has been made in consideration of the above points, and therefore, an object of this application is to provide a quartz piece having a novel shape suitable for use in the manufacture of quartz devices, a quartz device using the same, and an intermediate wafer for a quartz device. [Means for solving the problem]

[0006] In order to achieve this object, according to the first invention of this application, which is a quartz crystal blank, a first axis-second axis plane defined by a first axis derived from the X-axis of the quartz crystal and a second axis derived from the Z-axis of the quartz crystal is the main surface, and a third axis derived from the Y-axis of the quartz crystal is the thickness direction, and the quartz crystal blank has a rectangular shape in a plan view, When one of the sides of the crystal blank that intersect with the first axis is defined as the first side of the first axis, and the other is defined as the second side of the first axis, and when one of the sides of the crystal blank that intersect with the second axis is defined as the first side of the second axis, and the other is defined as the second side of the second axis, Each of the first side surface of the first axis, the second side surface of the first axis, the first side surface of the second axis, and the second side surface of the second axis is characterized by being composed of a crystal surface derived from quartz and a non-crystal surface having a contour parallel to the normal to the main surface. In this invention, the term "non-crystalline surface" refers to both a truly non-crystalline surface and a surface that is non-crystalline from a macroscopic perspective but contains minute crystalline surfaces derived from quartz from a microscopic perspective. In either case, the non-crystalline surface is a surface that has an outline parallel or approximately parallel to the normal to the main surface of the quartz piece. In addition, the non-crystalline surface in this invention preferably has minute irregularities on its surface, for example irregularities with height differences of several nm to several hundreds of nm, preferably several tens of nm to several hundreds of nm, because this is expected to reduce unwanted vibrations relative to the main vibration of the quartz crystal piece.

[0007] In carrying out the first invention, the quartz crystal piece of the first invention is typically a quartz crystal piece that vibrates in thickness shear mode, such as a so-called two-rotation quartz crystal piece, represented by an AT-cut quartz crystal piece or an SC-cut vibrating piece. When the quartz crystal piece is an AT-cut quartz crystal piece, the first axis is the quartz crystal's X-axis, the second axis is the quartz crystal's Z'-axis, and the third axis is the quartz crystal's Y'-axis. Here, as is well known, the Z'-axis and Y'-axis are angles that are offset from the quartz crystal's Z-axis and Y-axis, respectively, depending on the cutting angle of the AT-cut quartz crystal piece from the quartz crystal rough. The first invention can also be applied to a crystal piece having a first axis derived from the X-axis of the crystal, a first-axis-second axis plane of a second axis derived from the Y-axis of the crystal as the main surface, and a third axis derived from the Z-axis of the crystal as the thickness direction. For example, the first invention can also be applied to a contoured crystal piece such as a GT cut. In addition, in carrying out this first invention, it is preferable to manufacture the quartz piece by a process that includes, for example, a step of irradiating laser light, preferably ultrashort pulse laser light, along the intended outer edge portion of the quartz piece on the quartz wafer to form a region of loss of crystallinity in the thickness direction of the quartz wafer in the intended outer edge portion, and a step of immersing the quartz wafer on which the region of loss of crystallinity has been formed in an etchant for wet etching, for example a hydrofluoric acid-based etchant, to remove a region of the quartz wafer including the outer edge region, thereby forming the outer shape of the quartz piece.

[0008] In addition, according to the second invention of this application, which is a quartz crystal device, the invention is characterized by comprising a quartz crystal vibrating piece having the quartz crystal piece of the first invention and excitation electrodes provided on the front and back main surfaces of the quartz crystal piece, and a container that contains the quartz crystal vibrating piece. The crystal device referred to in the second aspect of the invention is typically a crystal unit, a crystal unit with a temperature sensor, or a crystal oscillator (including a crystal oscillator having a temperature compensation function). According to the third aspect of the present invention, which is an intermediate wafer for a quartz crystal device, the intermediate wafer is characterized in that it is made up of a quartz crystal wafer having, in a matrix arrangement, a large number of quartz crystal vibrating pieces each having the quartz crystal piece of the first aspect and excitation electrodes provided on the front and back of the quartz crystal piece. Effect of the Invention

[0009] According to the quartz crystal blank of the first invention of this application, the first side of the first axis, the second side of the first axis, the first side of the second axis, and the second side of the second axis are each composed of a crystal surface derived from quartz and a non-crystal surface having an outline parallel to the normal line of the main surface. Therefore, compared to a case where the side of the quartz crystal blank is composed only of a crystal surface of quartz, the influence of the shape caused by the anisotropy of the crystal axis of the quartz crystal can be reduced. Therefore, problems such as the effective vibration area of ​​the quartz crystal blank being narrowed due to the shape caused by the anisotropy of the crystal axis of the quartz crystal can be improved. In general, the wider the vibration area of ​​a quartz crystal blank, the easier it is to improve the electrical characteristics of the quartz crystal blank, and there is also an advantage that the degree of freedom in designing the quartz crystal blank is increased, so according to the present invention, the above advantages can be easily obtained. Therefore, a quartz crystal blank having a novel shape suitable for use in manufacturing quartz crystal devices can be provided. Furthermore, according to the invention of a quartz crystal device, which is the second invention of this application, it is possible to realize a quartz crystal device with superior characteristics compared to conventional ones. Furthermore, according to the intermediate wafer for quartz crystal devices, which is the third aspect of the present invention, quartz crystal devices having superior characteristics compared to conventional ones can be manufactured with good mass productivity. [Brief description of the drawings]

[0010] [Figure 1] 1A to 1C are diagrams illustrating a crystal piece 10 according to an embodiment. [Diagram 2] 1A and 1B are diagrams illustrating the shape of each side surface of a crystal piece 100 of a comparative example. [Diagram 3] 1A and 1B are diagrams illustrating a quartz crystal resonator 20 as an embodiment of a quartz crystal device. [Figure 4] 13(A) and 13(B) are diagrams illustrating a crystal device 30 according to another embodiment. [Diagram 5] 1A to 1C are diagrams illustrating an example of a method for manufacturing a crystal piece 10 according to an embodiment, and a diagram illustrating an intermediate wafer 50 according to an embodiment for use in a crystal device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments of the inventions of this application will be described with reference to the drawings. Note that the drawings used in the description are merely schematic illustrations to the extent that these inventions can be understood. In addition, in the drawings used in the description, similar components are indicated by the same numbers, and their explanation may be omitted. Furthermore, the shapes, materials, manufacturing methods, etc. described in the following embodiments are merely preferred examples within the scope of this invention. Therefore, the present invention is not limited to the following embodiments.

[0012] 1-1. Crystal piece according to the embodiment A crystal blank 10 according to an embodiment will be described with reference to FIG. 1. FIGS. 1A to 1C are explanatory diagrams of the crystal blank 10 according to an embodiment, in which FIG. 1A is a top view, FIG. 1B is a cross-sectional view of the crystal blank 10 taken along line PP in FIG. 1A, and FIG. 1C is a cross-sectional view of the crystal blank 10 taken along line QQ in FIG. 1A. However, the crystal blank 10 in FIG. 1A is shown in the state of a crystal vibrating blank having excitation electrodes 11 on the front and back principal surfaces 10c. Also, what is shown as 11a in FIG. 1A is an extraction electrode that is drawn from the excitation electrode 11 to one side of the crystal blank 10. All of FIGS. 1A to 1C are views using scanning electron microscope (SEM) photographs of the crystal blank 10 according to an embodiment.

[0013] The crystal blank 10 of the embodiment has a first axis-second axis plane defined by a first axis 10a derived from the X axis of the crystal and a second axis 10b derived from the Z axis of the crystal as the main surfaces 10ca and 10cb, and a third axis 10d derived from the Y axis of the crystal as the thickness direction, and is a quadrangular crystal blank in plan view. Specifically, the crystal blank 10 of the embodiment is an AT-cut crystal blank in this case. Therefore, the first axis 10a is the X axis of the crystal, the second axis 10b is the Z' axis of the crystal, and the third axis 10d is the Y' axis of the crystal. The Z' axis and Y' axis are axes that are offset from the Z axis and Y axis of the crystal due to the cutting angle of the AT cut. In addition, in the crystal blank 10, the two opposing main surfaces 10ca and 10cb are surfaces of the area where the thickness of the crystal blank 10 is t. In this crystal blank 10, when one of the sides intersecting the first axis (X axis of the crystal in this case) of the crystal blank 10 (the +X side in this case) is defined as the first side 10aa of the first axis, and the other side (the -X side in this case) is defined as the second side 10ab of the first axis, and one of the sides intersecting the second axis (Z' axis of the crystal) of the crystal blank 10 is defined as the first side 10ba of the second axis, and the other is defined as the second side 10bb of the second axis, the first side 10aa of the first axis, the second side 10ab of the first axis, the first side 10ba of the second axis, and the second side 10bb of the second axis are each composed of a crystal surface 10e derived from the crystal and a non-crystal surface 10f that is a non-crystal surface 10f and has an outline 10fa parallel to the normal 10cc of the main surface 10c. Each of the side surfaces 10aa to 10bb will be described in detail below.

[0014] First, with reference to FIG. 1(B), a first side surface 10aa of the first shaft and a second side surface 10ab of the first shaft will be described. In this case, the first side surface 10aa of the first axis is the side surface on the +X side of the crystal out of the two side surfaces that intersect with the X-axis of the crystal. The first side surface 10aa of the first axis is composed of a first crystal surface 10e that contacts one of the main surfaces 10ca of the crystal blank 10, a second crystal surface 10e that contacts the other main surface 10cb of the crystal blank 10, and a non-crystal surface 10f that is between these two crystal surfaces 10e. The one main surface 10ca of the crystal blank 10 and the first crystal surface 10e contact each other at an angle θ1. The other main surface 10cb of the crystal blank 10 and the second crystal surface 10e contact each other at an angle θ2. In this example, the angle θ1 is about 152 degrees, and the angle θ2 is about 149 degrees. The angles θ1 and θ2 are 150 degrees ±5 degrees. These angles θ1 and θ2 vary slightly depending on the amount of wet etching in the manufacturing method described later with reference to FIG. In addition, the non-crystalline surface 10f on the first side surface 10aa of the first axis is a surface that is uneven mainly along the Y' axis of the quartz piece, and the outline 10fa is parallel to the normal 10cc of the main surface 10c of the quartz piece 10. Here, "parallel" includes the case where it is substantially parallel. If the thickness of the portion of quartz crystal blank 10 where principal surfaces 10ca, 10cb face each other (thickness in the Y' direction in FIG. 1(B)) is defined as t, and the dimension of non-crystalline surface 10f in the Y' direction is defined as t1, then a larger t1 / t is preferable because it increases the proportion of the side surfaces perpendicular to the principal surfaces, making it easier to ensure a vibration region. t1 / t should be, for example, 50% or more, and preferably 70% or more. In this embodiment, t1 / t is approximately 74%.

[0015] On the other hand, the second side surface 10ab of the first axis is the side surface on the -X side of the crystal out of the two side surfaces that intersect with the X-axis of the crystal. The second side surface 10ab of the first axis is composed of a crystal surface 10e that contacts one of the main surfaces 10ca of the crystal piece 10, and a non-crystal surface 10f that continues from the crystal surface 10e to the other main surface 10cb of the crystal piece 10 and contacts the other main surface 10cb. In this example, the second side surface 10ab of the first axis is an example of a two-surface configuration of one crystal surface 10e and one non-crystal surface 10f, but there may be a case where a second crystal surface is minutely present on the other main surface side of the non-crystal surface 10f. In the case of the second side surface 10ab of the first axis, the contour 10fa of the non-crystalline surface 10f in the second side surface 10ab of the first axis is also parallel (including approximately parallel) to the normal 10cc of the main surface 10c of the crystal piece 10. Moreover, the non-crystalline surface 10f is a surface that is uneven mainly along the Y' axis of the crystal piece. Moreover, when the thickness of the portion where the main surfaces 10ca and 10cb of the crystal piece 10 face each other (thickness in the Y' direction in FIG. 1(B)) is defined as t, and the dimension of the non-crystalline surface 10f in the Y' direction is defined as t1, t1 / t is, for example, 50% or more, preferably 70% or more, and in this embodiment, t1 / t is about 90%. According to the quartz crystal blank 10 of the present invention, the first side surface 10aa and the second side surface 10ab of the first axis include non-crystalline surfaces 10f that are perpendicular to the main surface 10c. Therefore, compared to cases where this is not the case, the length of the main surface of the quartz crystal blank 10 in the direction along the X-axis of the quartz crystal is longer, resulting in the effect of expanding the vibration region of the quartz crystal blank 10 in the direction along the X-axis of the quartz crystal.

[0016] Next, with reference to FIG. 1(C), a first side surface 10ba of the second shaft and a second side surface 10bb of the second shaft will be described. In this case, the first side 10ba of the second axis is one of the two side surfaces that intersect with the Z' axis of the quartz crystal, and the second side 10bb of the second axis is the other of the two side surfaces that intersect with the Z' axis of the quartz crystal. The first side 10ba of the second axis is composed of a crystal surface 10e that contacts one of the main surfaces 10ca of the quartz crystal piece 10 at an angle θ3, and a non-crystal surface 10f that continues from the crystal surface 10e to the other main surface 10cb of the quartz crystal piece 10 and contacts the other main surface 10cb. The second side 10bb of the second axis is composed of a non-crystal surface 10f that contacts one of the main surfaces 10ca of the quartz crystal piece 10, and a crystal surface 10e that is between the non-crystal surface 10f and the other main surface 10cb of the quartz crystal piece 10 and contacts the other main surface 10cb of the quartz crystal piece 10 at an angle θ4. The non-crystalline surface 10f is a surface that is uneven mainly along the Y' axis of the quartz piece. Moreover, the contour 10fa of each of the non-crystalline surfaces 10f of the first side surface 10ba and the second side surface 10bb of the second axis is parallel (or approximately parallel) to the normal 10cc of the main surface 10c of the quartz piece 10.

[0017] Furthermore, if the thickness of the portion of quartz crystal blank 10 where principal surfaces 10ca, 10cb face each other (thickness in the Y' direction in FIG. 1(C)) is defined as t, and the dimension of non-crystalline surface 10f in the Y' direction is defined as t1, then a larger t1 / t is preferable because it increases the proportion of the side surfaces perpendicular to the principal surfaces, making it easier to ensure a vibration region. t1 / t should be, for example, 50% or more, and preferably 70% or more. In this embodiment, t1 / t is approximately 74%. Here, angles θ3 and θ4 are in the range of approximately 110 to 120 degrees, although they may vary slightly depending on the amount of wet etching in the manufacturing method described later with reference to Figure 5. Moreover, crystal planes 10e of first side surface 10ba and second side surface 10bb of the second axis are generally symmetrical with respect to center point R of quartz crystal piece 10 (see Figure 1(C)). According to the quartz crystal piece 10 of the present invention, the first side 10ba and the second side 10bb of the second axis include a non-crystalline surface 10f perpendicular to the main surface 10c. Therefore, compared to cases where this is not the case, the length of the main surface of the quartz crystal piece 10 in the direction along the Z' axis of the quartz crystal is longer, resulting in the effect of expanding the vibration area of ​​the quartz crystal piece 10 in the Z' direction as well. Moreover, when focusing on the four corners of the crystal blank 10 of the embodiment, it has the following structure. That is, as shown in FIG. 1A, the four corners 10g, 10h, 10i, and 10j are right-angled corners when viewed in a plan view. A right angle is an angle formed by intersecting pieces of 90±2 degrees, preferably 90±1 degree. It is preferable that the four corners 10g, 10h, 10i, and 10j are right-angled corners when viewed in a plan view, because this has the effect of expanding the vibration area of ​​the crystal blank 10 compared to when they are not.

[0018] In the above embodiment, an example was described in which the present invention is applied to an AT-cut quartz crystal piece with a flat vibrating area, but the present invention can also be applied to so-called table-top AT-cut quartz crystal pieces in which the vibrating part is thicker than other parts. The present invention can also be applied to a twice-rotated quartz crystal piece, such as an SC cut, which is obtained by rotating a surface perpendicular to the Y axis of the quartz crystal by φ degrees around the Z axis of the quartz crystal as the center of rotation, and then rotating it by θ degrees around the X axis of the quartz crystal. In this case, the first axis is the X' axis resulting from the two-fold rotation, the second axis is the Z' axis resulting from the two-fold rotation, and the third axis is the Y' axis resulting from the two-fold rotation. The first invention can also be applied to a quartz crystal piece having a vibration mode of a contour system such as a GT cut.

[0019] 1-2. Comparative example of crystal piece To better understand the crystal piece of the first invention, a comparative crystal piece 100 will be described with reference to Figure 2. That is, for the comparative crystal piece 100 manufactured using normal photolithography and wet etching techniques, the results of observing a total of four side surfaces, two of which intersect with the X-axis of the crystal and two of which intersect with the Z'-axis of the crystal, will be described. FIG. 2(A) is a comparative example corresponding to FIG. 1(B), and FIG. 2(B) is a comparative example corresponding to FIG. 1(C). In the case of the comparative crystal piece 100, the two side surfaces (FIG. 2(A)) that intersect with the X-axis of the crystal are both two crystal faces 100a, 100b or 100c, 100d, and are composed of two inclined crystal faces. In addition, in FIG. 2(A), what is shown by 101 is an air bubble that occurred in the embedding resin when the cross-sectional observation sample was created, and is unrelated to the present invention. In addition, the two side surfaces (FIG. 2(B)) that intersect with the Z'-axis of the crystal are both two crystal faces 100e, 100f or 100g, 100h, and are composed of inclined crystal faces and crystal faces that are approximately perpendicular to the main face, and there is no non-crystalline face. Note that each side surface in the comparative example data is just one example, and the number of crystal planes on the side surface varies depending on the amount of wet etching of the quartz crystal piece, resulting in surface conditions such as those in Patent Documents 1 and 2. In any case, the side surface in the comparative example is composed of multiple crystal planes that are inclined with respect to the main surface, which differs from the structure of the present invention.

[0020] 2. Crystal device according to the embodiment Next, a crystal device 20 according to an embodiment will be described with reference to Fig. 3. Figs. 3(A) and (B) are explanatory diagrams of a crystal unit 20 as the crystal device 20 according to an embodiment, in which Fig. 3(A) is a top view and Fig. 3(B) is a cross-sectional view of the crystal device 20 taken along line PP in Fig. 3(A). However, Fig. 3(A) omits the cover member 27 of the piezoelectric device 20. Fig. 3(A) is also a view using a scanning electron microscope (SEM) photograph of the crystal device 20 according to an embodiment. The quartz crystal vibrator 20 as a piezoelectric device of the embodiment includes a quartz crystal piece 21 having a quartz crystal blank 10 according to the first invention and excitation electrodes 11 provided on the front and back main surfaces of the quartz crystal blank 10, and a container 23 that contains the quartz crystal vibrator blank 21. In this example, the container 23 includes a recess 23a having a rectangular shape in a plan view for housing the quartz crystal vibrating piece 21, a bank portion 23b surrounding the recess 23a, an adhesive pad 23c to which the quartz crystal vibrating piece 21 is fixed and bonded, and an external connection terminal 23d provided on the outer bottom surface of the container 23 for connecting the quartz crystal device 20 to an arbitrary electronic device. The adhesive pad 23c and the external connection terminal 23d are electrically connected by via wiring or castellation (not shown). The container 23 can be constructed of a known ceramic package. In this case, the quartz crystal vibrating piece 21 has a cantilever support structure. The quartz crystal vibrating piece 21 is connected and fixed to an adhesive pad 23c of the container 23 at the position of the extraction electrode 11a with a conductive adhesive 25. A lid member 27 is bonded to the top surface of the bank portion 23b of the container 23 in a structure according to the sealing method, and the quartz crystal vibrating piece 21 is sealed in the container 23.

[0021] In the above embodiment, a quartz crystal resonator is shown as an example of a quartz crystal device, but the electronic device of the present invention also includes a piezoelectric device 30 in which a quartz crystal blank 10 and other electronic components 31 such as a temperature sensor and an oscillator circuit are mounted in a container 23 as shown in FIG. 4, that is, a quartz crystal resonator or quartz crystal oscillator with a temperature sensor (including those with a temperature compensation function). In addition, although the container 23 has been shown to have a structure having a recess 23a, the container 23 may also be a container composed of a flat base and a cap-shaped lid member having a recess for accommodating a quartz crystal vibrating piece. Also, although not shown in the figures, the electronic device may have a chamber for accommodating a quartz crystal vibrating piece and a chamber for accommodating other electronic components such as an oscillator circuit stacked back to back, and the cross section cut along the stacking direction has a so-called H-shaped structure.

[0022] 3. Example of manufacturing method of crystal piece 10 and intermediate wafer for forming crystal device Next, an example of a manufacturing method for the crystal piece 10 of the first invention and an embodiment of an intermediate wafer for a crystal device of the third invention will be described with reference to Figures 5(A) to (D). Figures 5(A) to (D) show the main parts of the manufacturing process for this purpose. Figures 5(B) and (C) are cross-sectional views taken along line PP in Figure 5(A). First, an AT-cut crystal wafer 50 is prepared (FIG. 5(A)). Next, a laser beam, preferably an ultrashort pulse laser beam, is irradiated along the outer edge planned portion 50a of the crystal piece 10 of the crystal wafer 50 to form a crystallinity loss region 50b along the thickness direction of the crystal wafer in the outer edge planned portion 50a (FIG. 5(B)). Note that, during the laser irradiation, the laser is not irradiated onto the portion 50c (see FIG. 5(A)) where each crystal piece 10 is connected to the crystal wafer 50. In addition, since the crystallinity loss region 50b is formed by laser irradiation, the width W (see FIG. 5(B)) of the crystallinity loss region 50b can be narrow, which has the effect of increasing the number of crystal pieces 10 in the crystal wafer 50.

[0023] The crystal wafer with the loss of crystallinity region 50b formed is immersed in an etchant for wet etching, such as a hydrofluoric acid-based etchant (not shown), to remove the region including the planned outer edge of the crystal wafer, and form the outer shape of the crystal piece 10 (FIG. 6(C)). In this etching process, the loss of crystallinity region 50b of the crystal wafer 50 is etched faster than the crystalline region. At that time, the surface of the crystal wafer 50 is etched in a direction intersecting the thickness direction of the crystal wafer 50, and a crystal plane 10e is generated. The size of the crystal plane 10e changes depending on the length of the etching time. It is considered that the loss of crystallinity region is etched in a state where the crystal plane of the crystal is lost, and a non-crystalline plane 10f is generated and a non-crystalline plane 10f having a contour 10fa parallel to the normal line of the main surface 10c of the crystal piece 10 is obtained (FIG. 6(C)). Next, excitation electrodes 11 are formed on the front and back of each crystal blank 10 using known film formation and photolithography patterning techniques. These steps result in an intermediate wafer 50x for forming crystal devices. That is, a crystal wafer 50x is formed that includes a large number of crystal blanks 10 and crystal vibrating blanks 20 with excitation electrodes 11 provided on the front and back of the crystal blank in a matrix arrangement (FIG. 6(D)). [Explanation of symbols]

[0024] 10: Crystal piece of embodiment; 10a: First axis (X-axis of crystal) 10b: Second axis (Z' axis of the crystal) 10ca: One of the main surfaces of the crystal piece 10cb: the other main surface of the crystal piece, 10cc: normal to the main surface 10d: 3rd axis (Y' axis of crystal) 10aa: First side of first axis 10ab: Second side of first axis 10ba: 1st side of 2nd shaft 10bb: 2nd side of 2nd shaft 10e: Crystalline surface of quartz 10f: Non-crystalline surface 10fa: Contours of non-crystalline surfaces 10g, 10h, 10i, 10j: The four corners of the crystal piece 11: Excitation electrode, 11a: Extraction electrode, 20: Piezoelectric device (quartz crystal unit) according to an embodiment 21: Crystal vibrating piece, 23: Container, 23a: recessed portion, 23b: bank portion, 23c: adhesive pad, 23d: external connection terminal 25: conductive adhesive, 27: cover member 30: Piezoelectric device of another embodiment 31: Other electronic components (temperature sensor, oscillator circuit, etc.) 50: AT-cut quartz crystal wafer L: Laser light 50a: Predetermined outer edge portion 50b: Crystallinity loss region 50x: Intermediate wafer through holes for forming quartz crystal devices

Claims

1. A quartz crystal piece having a principal plane defined by a first axis derived from the X-axis of the quartz crystal and a second axis derived from the Z-axis of the quartz crystal, and a third axis derived from the Y-axis of the quartz crystal as a thickness direction, the quartz crystal piece being rectangular in plan view, When one of the side surfaces of the quartz crystal piece that intersect with the first axis is defined as a first side surface of the first axis, and the other is defined as a second side surface of the first axis, and when one of the side surfaces of the quartz crystal piece that intersect with the second axis is defined as a first side surface of the second axis, and the other is defined as a second side surface of the second axis, a first side surface of the first shaft, a second side surface of the first shaft, a first side surface of the second shaft, and a second side surface of the second shaft, A quartz crystal piece comprising a crystalline surface derived from quartz crystal and a non-crystalline surface having an outline parallel to a normal to the principal surface.

2. 2. The quartz piece according to claim 1, wherein t is a thickness of the quartz piece, and t1 is a length of the non-crystalline surface along the third axis, and t1 / t≧0.

5.

3. 2. The quartz piece according to claim 1, wherein the crystal surface includes a crystal surface having one end continuous with at least one of the front and rear main surfaces of the quartz piece and the other end continuous with the non-crystalline surface.

4. 2. The quartz piece according to claim 1, wherein the crystal surface includes two crystal surfaces: a first crystal surface having one end continuous with one of the front and rear main surfaces of the quartz piece and the other end continuous with the non-crystalline surface; and a second crystal surface having one end continuous with the other of the front and rear main surfaces of the quartz piece and the other end continuous with the non-crystalline surface.

5. 2. The quartz crystal piece according to claim 1, wherein the crystal face is a crystal face that is continuous with the main face at a predetermined angle.

6. 2. The quartz crystal piece according to claim 1, wherein the four corners of the quadrangular quartz crystal piece are right-angled corners when viewed from above.

7. The quartz crystal piece is an AT-cut quartz crystal piece, the first axis being the X-axis of the crystal; The second axis is a Z′ axis that is offset from the Z axis of the quartz crystal due to the cutting angle of the AT cut, 2. The quartz element according to claim 1, wherein the third axis is a Y' axis that is offset from the Y axis of the quartz due to a cutting angle of the AT cut.

8. The quartz crystal piece is an AT-cut quartz crystal piece, the first axis being the X-axis of the crystal; The second axis is a Z′ axis that is offset from the Z axis of the quartz crystal due to the cutting angle of the AT cut, the third axis is a Y′ axis that is offset from the Y axis of the quartz crystal due to the cutting angle of the AT cut, 2. The quartz crystal piece according to claim 1, wherein the non-crystalline surfaces on both side surfaces along the X-axis have rough surfaces.

9. The quartz crystal blank is a two-rotation quartz crystal blank obtained by rotating a surface perpendicular to the y-axis of the quartz crystal by φ degrees around the z-axis of the quartz crystal as the center of rotation, and then rotating it by θ degrees around the x-axis of the quartz crystal from that state, the first axis is the X′ axis resulting from the two rotations; the second axis is the Z′ axis resulting from the two rotations; 2. The quartz crystal piece according to claim 1, wherein the third axis is a Y' axis resulting from the two-fold rotation.

10. A quartz crystal piece having a principal plane defined by a first axis derived from the X-axis of the quartz crystal and a second axis derived from the Y-axis of the quartz crystal, and a third axis derived from the Z-axis of the quartz crystal as a thickness direction, the quartz crystal piece having a rectangular shape in a plan view, When one of the side surfaces of the quartz crystal piece that intersect with the first axis is defined as a first side surface of the first axis, and the other is defined as a second side surface of the first axis, and when one of the side surfaces of the quartz crystal piece that intersect with the second axis is defined as a first side surface of the second axis, and the other is defined as a second side surface of the second axis, a first side surface of the first shaft, a second side surface of the first shaft, a first side surface of the second shaft, and a second side surface of the second shaft, A quartz crystal piece comprising a crystalline surface derived from quartz crystal and a non-crystalline surface having an outline parallel to a normal to the principal surface.

11. A quartz crystal device comprising: a quartz crystal piece according to any one of claims 1 to 10; and excitation electrodes provided on the front and back principal surfaces of the quartz crystal piece; and a container that contains the quartz crystal piece.

12. 12. The quartz crystal device according to claim 11, wherein the quartz crystal device is a quartz crystal resonator, a quartz crystal vibrator with a temperature sensor, or a quartz crystal oscillator.

13. An intermediate wafer for a quartz crystal device, comprising a quartz crystal wafer having a large number of quartz crystal vibrating pieces in a matrix form, the quartz crystal pieces comprising the quartz crystal piece according to any one of claims 1 to 10 and excitation electrodes provided on the front and back of the quartz crystal piece.

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