Page 60 - MEMS Mechanical Sensors

3.2 Simulation and Design Tools 49

window the data points are given together with the literature source from which the
information was taken.
The various simulation solvers, which are mechanical, electromagnetic, electro-
mechanical, and electrostatic, can be run either from IntelliFab or directly. The
mechanical solver meshes the device to be analyzed. The meshing process can be
controlled by defining global or localized limits for the mesh of the certain areas of
interest. Then it computes the natural mechanical resonant modes, which can be
visualized in an animation. Furthermore, it allows the application of mechanical
loads such as forces and moments to the different surfaces of the structure, but also
thermal loads in form of heat convection. Thermal distribution generated by flow or
current through materials with varying resistivity and their mechanical deformation
caused by thermal strain can be simulated. Any analyses can be performed as a
response to a static load or dynamically as a result of a time varying load.
The electrostatic solver uses a very similar meshing process and computes a
capacitance matrix for the various layers and surfaces. Furthermore, it allows an
analysis of the resulting charge density, electrostatic forces and pressures.
The electromechanical solver allows the user to apply various loads to the
device under consideration such as electrostatic loads through applying voltages,
temperature, pressure, acceleration, and displacements, and subsequently calculate
the resulting mechanical reactions (such as stress distributions, deformations, and
displacements) and electrical properties (such as capacitance, charge density, and
electric field). As an example of an electromechanical simulation, Figure 3.8 shows

Figure 3.8 The result of a displacement simulation in the electromechanical solver. This particular
example shows a micromechanical switch actuated by electrostatic forces.