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.

MEMS based sensors, particularly capacitive sensors, potentially can address critical considerations for users including accuracy, repeatability, long-term stability, ease of calibration, resistance to chemical and physical contaminants, size, packaging, and cost effectiveness. Accordingly, it would be beneficial to exploit MEMS processes that allow for manufacturability and integration of resonator elements into cavities within the MEMS sensor that are at low pressure allowing high quality factor resonators and absolute pressure sensors to be implemented. Embodiments of the invention provide capacitive sensors and MEMS elements that can be implemented directly above silicon CMOS electronics.

A resonator defining a longitudinal axis that includes a mounting pad, a pad connector, at least one isolation mechanism, and a pair of elongated tines extending in the direction of the longitudinal axis. The isolation mechanism including an outer block defining a first outer end and a second outer end on opposite sides, an inner block defining a first inner end and a second inner end on opposite sides, and a pair of interconnect members, where each respective interconnect member of the pair of interconnect members connects the second outer end to the first inner end. The respective first ends of the pair of elongated tines being connected to the second inner end and the pad connector connects the mounting pad to the first outer end.

The disclosure describes techniques to adjust the geometry of a pendulous proof mass VBA to operate with sufficient signal-to-noise performance while avoiding nonlinear mechanical coupling at specified frequencies. The techniques of this disclosure include adding anchor support flexures to a resonator connection structure, adjusting shape, thickness, and the material of VBA components and of the VBA support structure to both control the frequency of any mechanical resonant modes and to adjust the mechanical mode frequencies away from desired operating frequencies and, in some examples, away from harmonics of desired operating frequencies.

This disclosure describes techniques of configuring capacitive comb fingers of an accelerometer resonator into discreet electrodes with drive electrodes and at least two sense electrodes. The routing of electrical signals is configured to produce parasitic feedthrough capacitances that are approximately equal. The sense electrodes may be placed on opposite sides of the moving resonator beams such that the changes in capacitance with respect to displacement (e.g. dC/dx) are approximately equal in magnitude and opposite in sign. The arrangement may result in sense currents that are also opposite in sign and result in feedthrough currents of the same sign. The sense outputs from the resonators may be connected to a differential amplifier, such that the difference in output currents may mitigate the effect of the feedthrough currents and cancel parasitic feedthrough capacitance. Parasitic feedthrough capacitance may cause increased accelerometer noise and reduced bias stability.

The disclosure describes techniques to damp the proof mass motion of an accelerometer while achieving an underdamped resonator. In an example of an in-plane micro-electromechanical systems (MEMS) VBA, the proof mass may contain one or more damping combs that include one or more banks of rotor comb fingers attached to the proof mass. The rotor comb fingers may be interdigitated with stator comb fingers that are attached to fixed geometry. These damping comb fingers may provide air damping for the proof mass when the MEMS die is placed into a package containing a pressure above a vacuum. The geometry of the damping combs with a reduced air gap and large overlap area between the rotor comb fingers and stator comb fingers. The geometry of resonator of the VBA of this disclosure may be configured to avoid air damping.

MEMS based sensors, particularly capacitive sensors, potentially can address critical considerations for users including accuracy, repeatability, long-term stability, ease of calibration, resistance to chemical and physical contaminants, size, packaging, and cost effectiveness. Accordingly, it would be beneficial to exploit MEMS processes that allow for manufacturability and integration of resonator elements into cavities within the MEMS sensor that are at low pressure allowing high quality factor resonators and absolute pressure sensors to be implemented. Embodiments of the invention provide capacitive sensors and MEMS elements that can be implemented directly above silicon CMOS electronics.

A vibrating beam accelerometer (VBA) with an in-plane translational proof mass that may include at least two or more resonators and be built with planar geometry, discrete lever arms, four-fold symmetry and a single primary mechanical anchor between the support base and the VBA. In some examples, the VBA of this disclosure may be built according to a micro-electromechanical systems (MEMS) fabrication process. Use of a single primary mechanical anchor may minimize bias errors that can be caused by external mechanical forces applied to the circuit board, package, and/or substrate that contains the accelerometer mechanism.

A vibrating beam accelerometer (VBA) with an in-plane pendulous proof mass, which may include one or more resonators, planar geometry, a single primary mechanical anchor between the support base and the VBA, a resonator connector structure connecting the resonators to the single primary anchor and a hinge flexure mechanically connecting the proof mass to the single primary anchor. The techniques of this disclosure specify how the resonators can be solidly attached to the single anchor without compromising performance caused by forces applied on or by the support base. The geometry of the VBA may prevent bias errors that may otherwise result from a force applied to the support base that reaches the mechanism of the VBA. An example of force applied to the support base, may include the thermal expansion mismatch between the material of the support base and the material of the VBA.

A micromechanical resonator is provided that enables a smaller total package size with an acceptable quality factor for timing applications. The MEMS resonator includes a vibration portion with a base and three or more vibrating beams extending therefrom. Moreover, the MEMS resonator includes a frame that surrounds a periphery of the vibration portion and a pair of anchor between the vibrating beams for stabilizing the vibration portion within the frame. Furthermore, support beams couple the base of the vibration portion to the pair of anchors.