Micromachined microelectromechanical systems (MEMS) based resonators offer integration with other MEMS devices and electronics. Whilst piezoelectric film bulk acoustic resonators (FBAR) generally exhibit high electromechanical transduction efficiencies and low signal transmission losses they also suffer from low quality factors and limited resonance frequencies. In contrast electrostatic FBARs can yield high quality factors and resonance frequencies but suffer from increased fabrication complexity. lower electromechanical transduction efficiency and significant signal transmission loss. Accordingly, it would be beneficial to overcome these limitations by reducing fabrication complexity via a single metal electrode layer topping the resonator structure and supporting relatively low complexity/low resolution commercial MEMS fabrication processes by removing the fabrication requirement for narrow transduction gaps. Beneficially, embodiments of the invention provide MEMS circuits with electrostatic tuning and provide resonator designs combining the advantages of piezoelectric actuation and bulk-mode resonators.

A method for manufacturing a resonator that effectively addresses variations in resistivity for each wafer. The method for manufacturing a resonator includes forming a Si oxide film on a surface of a degenerated Si wafer, where the Si oxide film has a thickness set that is based on the doping amount of impurity in the degenerated Si wafer.

The present disclosure provides an aerosol sensing method. The aerosol sensing method includes steps of providing an entering process, providing a particle collecting process and providing a measuring process. The entering process is to allow an aerosol to enter a chamber of a thermal-piezoresistive oscillator-based aerosol sensor, and a thermal-piezoresistive resonator is disposed in the chamber. The particle collecting process is to allow particulate matters in the aerosol to land on at least one proof-mass of the thermal-piezoresistive resonator when the thermal-piezoresistive resonator is not driven. The measuring process is to use an electrical signal to drive the thermal-piezoresistive resonator and measure a resonant frequency of the thermal-piezoresistive resonator. The particle collecting process and the measuring process are operated in a repetitive cycle for measuring changes of the resonant frequency of the thermal-piezoresistive resonator to measure the particulate matters of the aerosol.

An apparatus includes a microelectromechanical system (MEMS) die having a first surface and an opposing second surface. The MEMS die includes a surface-mounted resonator on the first surface and includes a first inductor. The apparatus also includes first and second dies. The first die has a third surface and an opposing fourth surface. The first die is coupled to the MEMS die such that the third surface of the first die faces the first surface of the MEMS die. The first and second surfaces are spaced apart. The first die includes an oscillator circuit and a second inductor. The oscillator circuit is coupled to the second inductor. The second inductor is inductively coupled to the first inductor. The second die is electrically coupled to the first die.

A resonator is provided that suppresses vibration of a retainer caused by undesired vibration of a vibrating portion and also achieves size reduction. Specifically, the resonator includes a vibrating member that includes a semiconductor layer, a first piezoelectric film formed on the semiconductor layer, and a first upper electrode formed on the first piezoelectric film. Moreover, a retainer is provided to retain the vibrating member such that the vibrating portion can vibrate and one or more coupling members are provided to couple the vibrating member to the retainer. Finally, the resonator includes a vibration suppressing member that includes a second piezoelectric film formed on the retainer and a second upper electrode formed on the second piezoelectric film.

An example resonating structure comprises a substrate, a resonator body, and an anchoring body for anchoring the resonator body to the substrate. The resonator body includes a layer of base material and, deposited on top of the layer of base material, a layer of mismatch material having a mismatch in temperature coefficient of elasticity (TCE) relative to the base material. The base material is doped with a dopant having a concentration chosen so as to minimize a second order temperature coefficient of frequency for the resonator body. The thickness of the layer of the mismatch material is chosen so as to minimize a first order temperature coefficient of frequency for the resonator body.

A MEMS resonator is provided with improved electrical characteristics and reduced spurious resonances. The MEMS resonator includes two or more first rectangular resonator plates with lengths greater than their respective widths. Moreover, the MEMS resonator includes two or more second rectangular resonator plates that are positioned parallel to the first resonator plates in the widthwise direction of the MEMS resonator. The length of the second resonator plates is different than the length of the first resonator plates to reduce spurious resonances.

The present disclosure provides an aerosol sensing method. The aerosol sensing method includes steps of providing an entering process, providing a particle collecting process and providing a measuring process. The entering process is to allow an aerosol to enter a chamber of a thermal-piezoresistive oscillator-based aerosol sensor, and a thermal-piezoresistive resonator is disposed in the chamber. The particle collecting process is to allow particulate matters in the aerosol to land on at least one proof-mass of the thermal-piezoresistive resonator when the thermal-piezoresistive resonator is not driven. The measuring process is to use an electrical signal to drive the thermal-piezoresistive resonator and measure a resonant frequency of the thermal-piezoresistive resonator. The particle collecting process and the measuring process are operated in a repetitive cycle for measuring changes of the resonant frequency of the thermal-piezoresistive resonator to measure the particulate matters of the aerosol.

A vibration device that includes a support member, vibration arms connected to the support member and each having an n-type Si layer which is a degenerate semiconductor, and electrodes provided so as to excite the vibration arms, and silicon oxide films containing impurities in contact with a respective lower surface of the n-type Si layers of each vibration arm.

A bulk acoustic wave resonator apparatus includes a resonator member having an annulus shape, and at least one anchor structure coupling the resonator member to a substrate. A perimeter of the resonator member is at least partially defined by respective sidewalls that are slanted at an angle relative to a plane defined by a surface of the resonator member. The surface of the resonator member may be defined by a (100) crystal plane, and the angle of the respective sidewalls may be defined by a (111) crystal plane. Related fabrication methods are also discussed.