Page 61 - MEMS Mechanical Sensors

50 MEMS Simulation and Design Tools

the displacement of a beam as a result of an applied voltage giving rise to an attrac-
tive electrostatic force.
Another solver is the microfluidic analysis module. This tool allows the user to
analyze thermal effects, concentrations, and flow within a fluid. It also simulates
velocity and electric field distributions as a result of electrokinetic phenomena.
Another very useful tool is AnisE, an anisotropic etch process simulator. With
AnisE, the user can use the layout of the microstructure to be prototyped to view a
three-dimensional representation of it, access information about the etch rates of
different etchants, and then simulate the etching under different time, temperature,
and concentration parameters.
Finally, Intellisense contains a module called 3-D Builder, which can be called
from any of the solvers or separately as a standalone application. This tool allows
for building and meshing the three-dimensional geometry of MEMS structures with
a graphical interface. The screen is divided into two areas: on the left is the two-
dimensional layer window where the outline of different layers can be drawn; and
on the right is the three-dimensional viewing window, which allows the user to visu-
alize the device in three dimensions and includes zooming, rotating, and panning
functions. Furthermore, the thickness of any layer can be changed. In this way, a
MEMS device can be created without having to define the full fabrication process
flow. The module produces a file that can be used for analysis in any of the solvers
or, alternatively, a mask file that can be processed further by IntelliMask.

3.2.2.3 ANSYS (ANSYS Inc.)
The ANSYS FEA software is a commercially available simulation tool capable of
structural, vibration (modal, harmonic, and transient), thermal, acoustic, fluidic,
electromagnetic, and piezoelectric analyses (or combinations of these). While not
specifically written for the simulation of MEMS, many of these analyses apply
equally well in the microdomain, and as such, ANSYS has been widely used
throughout the MEMS community. The software interface has evolved over many
years, and the latest ANSYS Workbench environment is now relatively straightfor-
ward to use even for the novice.
The ANSYS Multiphysics software is of particular relevance to the simulation of
MEMS and has the capability to simulate the following characteristics (shown
graphically in Figure 3.9):

Electromagnetic Fluid

Piezoelectric Structural
Thermal

Electrostatic Electrical

Figure 3.9 ANSYS MEMS capability.