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Modeling of High Frequency Out-of-Plane Single Axis
MEMS Capacitive Accelerometer
Prashant
Singh, Pooja Srivastava, Ram Mohan Verma, and Saurabh Jaiswal
Department of Microelectronics, IIIT-Allahabad, India
{psingh3688,poojasrivastava1405,rammohanverma15,
jaiswalsaurabh2009}@gmail.com
Abstract.
The present paper deals with the modeling of high resonance
frequency electrostatically actuated MEMS accelerometer having out-of-plane
sensing axis. The accelerometer is based on folded beam support and comb
structure configuration. Capacitance change phenomenon is used to determine
the device acceleration. Effect of different structural parameters on the device
performance is analyzed and the simulation is carried out on COMSOL
Multiphysics, a strong 3D modeling software. The design is based on standard
SOI-MUMP'S technology and with in-house fabrication capabilities. SOI-
MUMP'S technology is preferred because of its outstanding performance and
ease of fabrication.
1
Introduction
Micro electro mechanical (MEMS) accelerometer is one of the most popular miniaturized
inertial sensor [1] used to measure displacement, velocity, acceleration/deceleration and
vibration [2]. Miniaturized devices are advantageous in the way that they possess high
frequency, small size, low power and low cost etc. The acceleration measures is in terms
of g-value, the specific force acting in a body relative to some frame, g-value is zero for
free falling body whereas g-value is very large for missile and navigation applications, the
maximum value measured by accelerometer is 500g. Also the accelerometer is a device
which is used to measure the acceleration producing forces, these force might be static
such as constant force acting on a body or dynamic such as force varying with time. In
present scenario MEMS accelerometer make its presence essential in all the applications
where motion is involved [3-5]. Several approaches such as piezoelectric, piezoresistive,
thermal, etc [6]. has been used for a long time in industry to design accelerometers but
capacitive approach revolutionize accelerometer application and its market as such it
replaces all other designing techniques. Capacitive accelerometer is the most fascinating
device in the sense that it covers all the fields of application ranging from kids toys,
motion sensor games [7], biomedical, military and navigation.
Capacitive accelerometer design is based on the measurement of change in
capacitance value. MEMS structures are designed to sense the change of capacitance,
an additional circuitry is required to convert change in capacitance into voltage value
[8]. Capacitive accelerometer is designed on the basis of number of axis it sensed, the
sensing axis can be one, two or three. Sensing is also based on the movement of
