Capacitive test-structures design methodology for the extraction of AIR-GAP and dielectric thickness of a MEMS process

The air-gap and dielectric thicknesses are key technology parameters of a micromachining fabrication process; their correct estimation is necessary for both good prediction of MEMS devices behavior and process monitoring. In this paper we present a methodology for their accurate quantification making use of capacitive test-structures, in order to allow automated data-extraction or, in general, capacitance measurements with standard lab instrumentation; the parameters are computed from measurements through a simple analytical model. Model validation and robustness to main parameters deviations and undesired mechanical effects are investigated by finite element analysis using CoventorWare