Simulations are often used to determine the general behavior of Micro Electro Mechanical Systems (MEMS). However, the detailed geometry and material properties of the simulation model are often insufficiently accurate. Usually, when simulation results are compared to experimental measurements, these inaccuracies are lumped into either geometric or material property "fudge factors". Often, these fudge factors need to be changed when modeling a similar device of different dimensions. The goal of this project is to examine in detail the precise geometry and material properties of MEMS, especially near regions of discontinuity. This will enable the decoupling of geometric and material fudge factors, and support the accurate simulation of a wide range of devices based on calibrations to simple generic test structures built on the same wafer as the actual MEMS.
Progress:
Dynamic one-lump, two-lump and quasi-two-dimensional coupled electro-mechanical models have been developed for a micromachined microwave switch. We examined the effects of solid mechanics, electrostatics, squeezed-film damping and contact. The sensitivity of the device to geometrical and material parameter variations was also investigated.
Variations in the behavior of devices fabricated in the MUMPS process due to variations in processing characteristics were examined. Such simulations are important in examining the yield of a particular device given a particular process. Supposing the geometric and material properties of the blanket films in the process are well defined, we examined the effect of variations in these properties near discontinuities (step-ups, etch holes, interfaces of multilayers etc.) Although these effects are second-order, neglecting them would require specific fitting parameters for each device being simulated. The goal is to define the minimal set of process parameters necessary to characterize and simulate all the devices that might be built using a particular process.
Publications:
E.K. Chan, K. Garikipati, K. Hsiau and R.W. Dutton, "Measurements and modeling of detailed processing effects on device behavior," submitted to Modeling and Simulation of MEMS, April 1998.
Trips: