MEMS Component Library
MEMS+ is based on an extensive library of MEMS components (basic structural building blocks). Each component has a 3D view and an underlying model that captures mechanical, electrical and/or gas damping physical behavior. Similar to the way an IC designer builds an electronic circuit by selecting and assembling models from a SPICE model library, a MEMS designer selects components from the MEMS+ library and assembles them into a desired device design.
MEMS designers generate MEMS models for inclusion in circuit or system simulators, to support the design of control and read-out circuits for MEMS devices. There are three options for creating these types of MEMS models:
- Hand-crafted analytical models, implemented in SPICE or Verilog-A,
- Reduced-order models (macro models) extracted from FEA, or
- Models built from discrete element representation (behavioral models such as those created in MEMS+).
Design entry in MEMS+ starts with input of the fabrication technology, including the process stack and material properties. Next, a MEMS behavioral model can be generated using the MEMS Component Library. MEMS+ includes a library of parametric MEMS components, or building blocks, such as rigid shapes, flexible mechanical shapes, electrodes, and electorstatic combs. In MEMS+, models are assembled from a component library where electrical, mechanical, input and output ports can be defined. Designers assemble selected components from the library into MEMS device models, using an intuitive 3D user interface. Custom rigid shapes can be imported from GDS2 layout. Everything is scriptable in MATLAB® or Python. The assembled parametric MEMS device models enable rapid, automated design studies.
Over the last 15 years, Coventor has developed the theoretical background supporting the multi-physics and multi-domain mathematics for each item in the component library. The models have been validated for many different types of MEMS devices, over many years of experience. Our internal development team continuously enhances the model library, based upon the latest theory and based upon feedback from our customers.
The MEMS+ assembled models are extremely simple to build, highly accurate, extremely fast and quickly ready for simulation. In addition, they can be easily maintained, supported and modified as your design needs change, and fully support parametric design studies.
Key Features
- Linear and non-linear models
- Unlimited number of layers
- Arbitrary cross-sections and side-wall angle support
- Reduced-order model capabilities
- Variable-order flexible plates based on the latest generation of finite shell elements
- In and out-of-plane contact models
- Etch-hole models
- Stress and stress-gradient models
- Full electrostatic models
- Fringing field support in all electrostatic models
- and more…
The MEMS+ component library is hierarchical. The rigid plate includes parametric geometrical primitives such as rectangular segments, triangular segments, straight and curved comb fingers, etc that can be used to create additional arbitrary structures. The final rigid plate is the result of a boolean combination of the individual segments. The behavioral model of the rigid plate is based on Newton’s law and the Euler equations.
The second group of mechanical elements, the suspensions, includes parametric primitives for straight beams, serpentines, beam paths, vertical beams and many others. All suspension models are based on the Bernoulli beam theory.
The third group of mechanical elements, the flexible plates, include basic shapes like circles, arcs, rectangles and quadrilaterals that can be used to create complex flexible structures.
All flexible plate shapes are modeled by a single, variable-order, finite shell element known as the MITC (mixed interpolation of tonsorial components). For the suspension components, great care has been taken to include all process-relevant effects such as side-wall angles, pre-stress, multi-layer support, as well as nonlinear behaviors such as buckling.
The members of the mechanical model families can be “decorated” with electrostatic, piezo electric and contact models.
The behavioral models are based on various modeling techniques including analytic formulae, numerical integration and finite element analysis. A detailed description of the underlying models can be found in the comprehensive reference documentation of the MEMS+ design environment.
