A resonator includes a base; and at least three vibrating arms having first ends connected to a front end of the base and second ends that are open ends spaced away from the front end. Each vibrating arm includes an arm portion having a part that extends from the fixed end in a direction toward the open end with a constant width and a mass-adding portion that is connected to a tip of the arm portion and has a larger width than the arm portion. An interval between the mass-adding portions is larger than an interval between the arm portions for any two vibrating arms that are adjacent to each other.

A resonator includes a base, at least one vibration arm, a frame, and a holding arm. The vibration arm includes a piezoelectric film, an upper electrode, and a lower electrode. The inequality Fs/Fm<1.9 or the inequality 2.1<Fs/Fm holds, where Fm is a frequency of a main or primary mode in the vibration arm, and Fs is a frequency of a spurious mode in the holding arm.

A resonator is provided that includes a vibration part and a mass addition portion. The vibration part includes a piezoelectric film, an upper electrode, and a lower electrode. The upper electrode and the lower electrode are disposed on opposite sides with the piezoelectric film therebetween. The amount of displacement of the vibration part is greater in a region corresponding to at least part of the mass addition portion than in any other region. The mass addition portion has an inclined surface that slopes in such a manner that the mass addition portion has end regions and a central region thinner than at least one of the end regions when the vibration part is viewed in a plan view.

A resonance device is provided for reducing the influence on the resonant frequency of the resonance device of the electric charge borne by an insulating film of a frame. The resonance device includes a resonator including a vibration portion and a frame disposed in at least a part of a vicinity of the vibration portion. The frame includes a holding body and an insulating film, with the holding body holding the vibration portion to vibrate and the insulating film being formed above the holding body. A lower cover is provided having a recess forming at least a part of a space in which the vibration portion vibrates. An inner side surface of the insulating film is disposed at a first distance from an inner surface of a side wall defining the recess.

A resonance device that includes a lower cover, an upper cover joined to the lower cover, a resonator having vibrating arms that bend and vibrate in a vibration space between the lower cover and the upper cover, and particles attached to tip portions of the vibrating arms. When a median size of the particle is defined as D50, a specific gravity of the particle is defined as A, and a resonant frequency of the resonator is defined as X, D50≤189/(X×√A).

A resonance device is provided that includes a resonator including upper electrodes, a lower electrode, and a piezoelectric thin film formed therebetween. An upper cover is provided with a first surface facing the upper electrodes of the resonator. A power supply terminal is provided on a second surface of the upper cover with the power supply terminal electrically connected to the upper electrodes. Another power supply terminal is on the second surface of the upper cover and is electrically connected to the upper electrodes. A ground terminal is provided on the second surface of the upper cover and is electrically connected to the lower electrode. An area of each power supply terminal are different from one other such that a capacitance formed between the first power supply terminal and the ground terminal is approximately equal to a capacitance formed between the second power supply terminal and the ground terminal.

A resonator is provided that includes a base; at least three vibrating arms that include a piezoelectric film, an upper electrode, and a lower electrode; a frame; and a holding arm. Each vibrating arm includes an arm portion and a tip portion. The holding arm includes a holding side arm that extends parallel to the outer vibrating arm. A release width between the tip portion of the outer vibrating arm and the frame is larger than a release width between the holding side arm and the frame or a release width between the arm portion of the outer vibrating arm and the holding side arm.

A resonator including a lower electrode, an upper electrode, and a piezoelectric film that is formed between the lower electrode and the upper electrode. A MEMS device is provided that includes an upper lid that faces the upper electrode, and a lower lid that faces the lower electrode and that seals the resonator together with the upper lid. A CMOS device is mounted on a surface of the upper lid or the lower lid opposite a surface that faces the resonator. The CMOS device includes a CMOS layer and a protective layer that is disposed on a surface of the CMOS layer opposite a surface that faces the resonator. The upper or lower lid to which the CMOS device is joined includes a through-electrode that electrically connects the CMOS device to the resonator.

A piezoelectric film that includes crystalline AlN; at least one first element partially replacing Al in the crystalline AlN; and a second element doping the crystalline AlN and which has an ionic radius smaller than that of the first element and larger than that of Al.

A MEMS device that includes a substrate including an element and a connection wiring electrically connected to the element, and a connection portion electrically connected to the connection wiring. The connection portion is formed of a eutectic alloy of a first metal and a second metal. A line width of the connection wiring is smaller than a width of the connection portion when a main surface of the substrate is viewed in a plan view.