Basic Techniques and Available Tools for MEMS Modeling and Simulation
Before trying to answer the above questions for MEMS, we need to look specifically at the tools and
techniques the MEMS designer has available for the modeling and simulation tasks. As pointed out in
[29,30], the bottom line is, in any simulator, all models are not created equal. The developer must be
very clear about what parameters are of greatest interest and then must choose the models and simulation
techniques (including implementation in a tool or tools) that are most likely to give the most accurate
values for those parameters in the least amount of simulation time. For example, the model used to
determine static behavior may be different from the model needed for an adequate determination of
dynamic behavior. Thus, it is useful to have a range of models and techniques available.
Basic Modeling and Simulation Techniques
We need to make the following choices:
• What kind of behavior are we interested in? IC simulators, for example, typically support DC
operating analysis, DC sweep analysis (stepping current or voltage source values) and transient
sweep analysis (stepping time values), along with several other types of transient analysis [30]. Will the computation be symbolic or numeric?
• Will use of an exact equation, nodal analysis, or finite element analysis be most appropriate?
Currently, these are the techniques which are favored by most MEMS developers.
To show what these choices entail, let us look at a simple example that combines electrical and mechanical
parts. The cantilever beam in Figure 7.5(a), fabricated in metal, polysilicon, or a combination, may be
combined with an electrically isolated plate to form a parallel plate capacitor. If a mechanical force or a
varying voltage is applied to the beam (Figure 7.5(b1)), an accelerometer or a switch can be obtained [31].
If instead the plate can be moved back and forth, a more efficient accelerometer design results (Figure
7.5(b2)); this is the basic design of Analog Devices’ accelerometer, probably the first truly successful
commercial MEMS device [32,33]. If several beams are combined into two “combs,” a comb-drive sensor
or actuator results, as in Figure 7.5(b3) [34]. Let us consider just the simplest case

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