Thin MEMS microphone based on package-integrated fabrication process

Wafer-Level-Based Open-Circuit Sensitivity Model from Theoretical ALEM and Empirical OSCM Parameters for a Capacitive MEMS Acoustic Sensor

“…Most commercial MEMS acoustic sensors in IoT applications are capacitive-type devices due to their compatibility with the standard complementary metal–oxide–semiconductor (CMOS) process in terms of form factor, thermal stability, and linear frequency response. The capacitive-type MEMS acoustic sensor [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] is composed of two plates, namely, a rigid back plate fixed on a substrate and a flexible diaphragm that detects an input acoustic signal. The moving plate should respond flexibly to the input sound pressure, and the hard bottom plate must have etch holes to reduce the damping effect.…”

“…In addition, to investigate the frequency response, the first resonant frequency representing a linear frequency range must be modeled. Accordingly, for the measurement of the first resonant frequency, it is necessary to integrate the sensor with an ROIC converting a proper electric signal [3,5,7,8,9,11], which results in an intricate task. Considering the effective feedback, researchers developing such a sensor need an evaluation method that does not use an ROIC in the development stage, especially at the wafer level.…”

MEMS Capacitive Microphone with Dual-Anchored Membrane

“…Recently, MEMS-type capacitive microphones have been widely applied in mobile applications, especially smart phones and tablets [1]. MEMS microphones have been usually fabricated by bulk micromachining processes which include a complicated processes such as multi-layer patterning and bulk etching processes.…”

TiN/PECVD‐Si 3 N 4 /TiN diaphragm‐based capacitive‐type MEMS acoustic sensor

“…Introduction: Capacitive-type MEMS microphones have been widely applied in a variety of communication services, especially smart-phone modules, on the basis of their matured competitiveness combined with a monolithic integrated CMOS process [1][2][3]. Most conventional MEMS acoustic sensors have a polysilicon diaphragm and an oxide sacrificial layer [1,2], requiring additional aluminium (Al) or gold metal deposition for wire bonding pads, although they show good compatibility and excellent frequency responses.…”

“…Thus, for MEMS acoustic sensors to be simply implemented without an additional photolithography process, a capacitive-type TiN/plasma-enhanced chemical vapour deposition (PECVD)-Si 3 N 4 /TiN diaphragm-based MEMS acoustic sensor is proposed and investigated; it is fabricated with a planarised polyimide sacrificial layer to improve the dynamic characteristics. In addition, to properly evaluate the dynamic response, both an effective capacitance model and an equivalent circuit model equipped with a voltagecontrolled voltage source (VCVS) are proposed and compared with conventional models [1,3,4]. Generally, it is immensely intricate to extract the radial-direction portion of the fringe capacitance [5] due to nonlinear electric field, or it is impossible to separate the parasitic value from the simulated capacitance obtained from finite element method simulators.…”