US-12628564-B2 - Crystal element, crystal device, electronic equipment, and method for manufacturing crystal element

US12628564B2US 12628564 B2US12628564 B2US 12628564B2US-12628564-B2

Abstract

A crystal element includes a vibration part, a holding part, an electrode part, and a recess that corresponds to a recess and/or protrusion. The vibration part has a pair of vibration-part main surfaces. The holding part is formed integrally with the vibration part to be connected to an outer edge of vibration part and has a pair of holding-part main surfaces and holding-part side surfaces. The electrode part is provided at the vibration-part main surfaces. The recess is located at the holding-part side surfaces.

Inventors

Koki Honda
Seiichiro NAMIKAWA
Shogo Nakagawa

Assignees

KYOCERA CORPORATION

Dates

Publication Date: 20260512
Application Date: 20201125
Priority Date: 20191126

Claims (14)

1 . A crystal element comprising: a vibration part having a pair of vibration-part main surfaces; a holding part formed integrally with the vibration part to be connected to an outer edge of the vibration part and having a pair of holding-part main surfaces and a holding-part side surface; an electrode part provided at the vibration-part main surfaces; and a recess and/or protrusion provided at the holding-part side surface, and is distal from and extends parallel to the pair of holding-part main surfaces so as to reduce a secondary vibration that occurs along with a primary vibration in the vibration part.
2 . The crystal element according to claim 1 , wherein the holding part is thicker than the vibration part.
3 . The crystal element according to claim 2 , wherein the vibration part is approximately quadrangular in plan view.
4 . The crystal element according to claim 3 , wherein the holding part is located on at least one side of the vibration part in plan view.
5 . The crystal element according to claim 4 , wherein the holding part has a fixing portion including a portion configured to be in contact with an element mounting member, and the electrode part has an excitation electrode located at the vibration-part main surfaces, a mounting electrode located in the fixing portion, and a wiring electrode that electrically connects the excitation electrode to the mounting electrode.
6 . The crystal element according to claim 5 , wherein one of the pair of vibration-part main surfaces and one of the pair of holding-part main surfaces are on a same plane.
7 . The crystal element according to claim 6 , wherein based on a Cartesian coordinate system XY′Z′ including an X-axis, a Y′-axis, and a Z′-axis, defined by rotating a Cartesian coordinate system XYZ including the X-axis, a Y-axis, and a Z-axis of crystal axes of crystal, around the X-axis by 30° or more and 50° or less, the holding-part side surface of the holding part includes two holding-part side surfaces extending along an XY' plane and one holding-part side surface extending along a Y′Z′ plane, and the recess and/or protrusion is located in a portion from at least one of the two holding-part side surfaces extending along the XY' plane to the one holding-part side surface extending along the Y′Z′ plane.
8 . The crystal element according to claim 7 , wherein the recess and/or protrusion includes a first recess and/or protrusion located in a portion from one of the two holding-part side surfaces extending along the XY' plane to the one holding-part side surface extending along the Y′Z′ plane and a second recess and/or protrusion located in a portion from an other of the two holding-part side surfaces extending along the XY' plane to the one holding-part side surface extending along the Y′Z′ plane.
9 . A crystal device comprising: the crystal element according to claim 1 ; an element mounting member at which the crystal element is located; and a lid that, together with the element mounting member, hermetically encapsulates the crystal element.
10 . The crystal device according to claim 9 , wherein the holding part has an element mounting member, a mounting electrode of the crystal element is connected to the element mounting member with conductive adhesive, and the conductive adhesive is also placed inside a recess of the recess and/or protrusion.
11 . Electronic equipment comprising the crystal device according to claim 9 .
12 . A method for manufacturing the crystal element according to claim 1 by wet etching, comprising: based on a Cartesian coordinate system XY′Z′ including an X-axis, a Y′-axis, and a Z′-axis, defined by rotating a Cartesian coordinate system XYZ including the X-axis, a Y-axis, and a Z-axis of crystal axes of crystal, around the X-axis by 30° or more and 50° or less, a first step of preparing a crystal wafer having two wafer main surfaces parallel to an XZ' plane and having a relationship of front and back, and forming a mask of corrosion-resistant film on the two wafer main surfaces; a second step of immersing the crystal wafer with the mask formed thereon in etchant to form a crystal piece in the crystal wafer, the crystal piece including the vibration part, the holding part, and the recess and/or protrusion; and a third step of removing the mask from the crystal wafer with the crystal piece formed therein, wherein in the first step, the mask is formed such that the mask that protects a portion that serves as a holding-part main surface of the pair of holding-part main surfaces on a positive side of the Y′-axis is shifted in a positive direction of the Z′-axis relative to the mask that protects a portion that serves as a holding-part main surface of the pair of holding-part main surfaces on a negative side of the Y′-axis.
13 . The method for manufacturing the crystal element, according to claim 12 , wherein the crystal wafer has a thickness of 30 μm or more and 50 μm or less in a direction of the Y′-axis, and in the first step, the mask is formed such that the mask that protects the holding-part main surface on the positive side of the Y′-axis is shifted in the positive direction of the Z′-axis by 10 μm or more and 20 μm or less relative to the mask that protects the holding-part main surface on the negative side of the Y′-axis.
14 . The method for manufacturing the crystal element, according to claim 12 , further comprising a step of cutting part of a portion of the crystal wafer with the crystal piece formed therein along a plane parallel to an XY' plane, the portion serving as the recess and/or protrusion.

Description

TECHNICAL FIELD The present disclosure relates to a crystal element, a crystal device including the crystal element, electronic equipment including the crystal device, and a method for manufacturing the crystal element. Examples of crystal devices include crystal resonators and crystal oscillators. BACKGROUND ART A crystal element having a thickness-shear vibration mode includes an AT-cut crystal piece having main surfaces and excitation electrodes of metal film patterns formed on both of the main surfaces. The crystal device utilizes the piezoelectric effect and the inverse piezoelectric effect of the crystal element to generate a specified oscillation frequency. A typical crystal device has a structure in which a crystal element is contained in a package and hermetically encapsulated within by a lid (for example, see Japanese Unexamined Patent Application Publication No. 2016-139901). SUMMARY OF INVENTION A crystal element according to the present disclosure includes: a vibration part having a pair of vibration-part main surfaces;a holding part formed integrally with the vibration part to be connected to an outer edge of the vibration part and having a pair of holding-part main surfaces and a holding-part side surface;an electrode part provided at the vibration-part main surfaces; anda recess and/or protrusion at the holding-part side surface. A crystal device according to the present disclosure includes the crystal element according to the present disclosure, and electronic equipment according to the present disclosure includes the crystal device according to the present disclosure. A method for manufacturing the crystal element according to the present disclosure is a method for manufacturing the crystal element according to the present disclosure by wet etching, and the method includes the following first to third steps, based on a Cartesian coordinate system XY′Z′ including an X-axis, a Y′-axis, and a Z′-axis, defined by rotating a Cartesian coordinate system XYZ including the X-axis, a Y-axis, and a Z-axis of crystal axes of crystal, around the X-axis by 30° or more and 50° or less. A first step of preparing a crystal wafer having two wafer main surfaces parallel to an XZ′ plane and having a relationship of front and back, and forming a mask of corrosion-resistant film on the two wafer main surfaces. A second step of immersing the crystal wafer with the mask formed thereon in etchant to form a crystal piece in the crystal wafer, the crystal piece including the vibration part, the holding part, and the recess and/or protrusion. A third step of removing the mask from the crystal wafer with the crystal piece formed therein. Then, in the first step, the mask is formed such that the mask that protects a portion that serves as a holding-part main surface of the pair of holding-part main surfaces on a positive side of the Y′-axis is shifted in a positive direction of the Z′-axis relative to the mask that protects a portion that serves as a holding-part main surface of the pair of holding-part main surfaces on a negative side of the Y′-axis. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plan view of a crystal element of a first embodiment. FIG. 2 is a view seen through the back side of the crystal element in FIG. 1. FIG. 3 is a sectional view taken along line Ic-Ic in FIG. 1. FIG. 4 is a perspective view of the crystal element of the first embodiment. FIG. 5 is a sectional view of a portion corresponding to the cross section taken along line III-III in FIG. 4 and shows a first step for forming a recess. FIG. 6 is a sectional view of the portion corresponding to the cross section taken along line III-III in FIG. 4 and shows a second step for forming the recess. FIG. 7 is a sectional view of the portion corresponding to the cross section taken along line III-III in FIG. 4 and shows a third step for forming the recess. FIG. 8 is a perspective view of another example of a crystal element according to the first embodiment. FIG. 9 is a perspective view of a crystal device according to a second embodiment. FIG. 10 is a sectional view taken along line Vb-Vb in FIG. 9. FIG. 11 is a perspective view of a portion of the crystal device according to the second embodiment. FIG. 12 is a front view of a first example of electronic equipment according to a third embodiment. FIG. 13 is a front view of a second example of electronic equipment according to the third embodiment. FIG. 14 is a schematic plan view of a first example of a holding part in the first embodiment. FIG. 15 is a schematic plan view of a second example of a holding part in the first embodiment. FIG. 16 is a schematic plan view of a third example of a holding part in the first embodiment. FIG. 17 is a schematic plan view of a fourth example of a holding part in the first embodiment. DESCRIPTION OF EMBODIMENTS In a crystal element, when an alternating voltage is applied to the excitation electrodes, thickness-shear vibration occurs in a portion of the crystal pie