A method for manufacturing a vibration element including a first protective film formation step of forming a first protective film, a first dry etching step of performing dry etching via the first protective film to form first grooves and the outer shapes of vibrating arms, a second protective film formation step of forming a second protective film in the first grooves, a second dry etching step of performing dry etching via the second protective film, a third protective film formation step of forming a third protective film, a third dry etching step of performing dry etching via the third protective film to form second grooves and the outer shapes of the vibrating arms, a fourth protective film formation step of forming a fourth protective film in the second grooves, and a fourth dry etching step of performing dry etching via the fourth protective film.

A vibration element manufacturing method includes a first dry etching step of dry-etching a quartz crystal substrate from the first surface side to form first grooves and the outer shapes of first and second vibrating arms, a second dry etching step of dry-etching the quartz crystal substrate from the second surface side to form second grooves and the outer shapes, and a wet etching step of wet-etching the side surfaces of the first and second vibrating arms, the first grooves, and the second grooves to form inclining surfaces that couple bottom surfaces to in-groove side surfaces of the first and second grooves, and the first and second grooves satisfy the relationship of D1/D ≥ 0.80, where D represents the depth of each of the first and second grooves, and D1 represents the result of subtraction of the length of the inclining surfaces in a direction Z from the depth in each of the first and second grooves.

When a thick frequency adjustment metal film of a tuning fork-type vibration piece is irradiated with a beam on a wafer for frequency coarse adjustment, projections are possibly formed on a roughened end of the frequency adjustment metal film. Such projections are pressurized and pushed down not to chip off under any impact, so that the risk of frequency fluctuations is suppressed.

When a thick frequency adjustment metal film of a tuning fork-type vibration piece is irradiated with a beam on a wafer for frequency coarse adjustment, projections are possibly formed on a roughened end of the frequency adjustment metal film. Such projections are pressurized and pushed down not to chip off under any impact, so that the risk of frequency fluctuations is suppressed.

A vibration element includes a base and a vibrating arm extending from the base. The vibrating arm includes an arm positioned between the base and a weight. A weight film is disposed on the weight. The weight has a first principal surface and a second principal surface in a front and back relationship with respect to a center plane of the arm. A center of gravity of the weight is located between the first principal surface and the center plane of the arm. A center of gravity of the weight film is located between the second principal surface and the center plane of the arm.

When a thick frequency adjustment metal film of a tuning fork-type vibration piece is irradiated with a beam on a wafer for frequency coarse adjustment, projections are possibly formed on a roughened end of the frequency adjustment metal film. Such projections are pressurized and pushed down not to chip off under any impact, so that the risk of frequency fluctuations is suppressed.

A method for manufacturing a vibration element that includes a base portion, a first vibration arm and a second vibration arm that extend from the base portion along a first direction and are arranged along a second direction intersecting the first direction, and bottomed grooves on both main surfaces of the first vibration arm and both main surfaces of the second vibration arm includes: a preparing step of preparing a crystal substrate; a protective film forming step of forming a protective film on the crystal substrate except for groove regions that are regions in which the grooves are formed; and a dry etching step of dry etching the crystal substrate through the protective film to form the grooves. The grooves provided in at least one of the first vibration arm and the second vibration arm include a first groove and a second groove arranged along the second direction.

A method for manufacturing a vibration element includes: a first dry etching step of dry etching the quartz crystal substrate from a first surface and forming first grooves and contours of a first vibrating arm and a second vibrating arm on the first surface; and a second dry etching step of dry etching the quartz crystal substrate from a second surface side and forming second grooves and contours of the first vibrating arm and the second vibrating arm on the second surface, in which Wa/Aa<1 in at least one of the first and second dry etching steps, Wa is a depth of the first and second grooves formed in the first and second dry etching steps, and Aa is a depth of the contours formed in the first and second dry etching steps.

A method for manufacturing a vibration element includes: a preparing step of preparing a quartz crystal substrate having a first surface and a second surface; a protective film forming step of forming a protective film on the first surface of the quartz crystal substrate, excluding groove forming regions where grooves are formed and an inter-arm region located between a first vibrating arm forming region where a first vibrating arm is formed and a second vibrating arm forming region where a second vibrating arm is formed; and a dry etching step of dry etching the quartz crystal substrate from a first surface side via the protective film and forming the grooves and contours of the first vibrating arm and the second vibrating arm. Wa/Aa<1, wherein Wa indicates a depth of the grooves formed in the dry etching step, and Aa indicates a depth of the contours.

The disclosed technology generally relates to packaging a quartz crystal, and more particularly to bonding a quartz crystal using sintering silver paste. In one aspect, a method of packaging a quartz crystal comprises attaching a quartz crystal to a package substrate using one or more silver paste layers comprising silver particles. The method additionally comprises sintering the silver paste in a substantially oxygen-free atmosphere and at a sintering temperature sufficient to cause sintering of the silver particles. The sintering is such that the quartz crystal exhibits a positive drift in resonance frequency of the quartz crystal over time. The method further comprises hermetically sealing the quartz crystal in the package substrate.