The capability of scanning microwave microscopy for calibrated sub-surface and non-contact capacitance imaging of silicon (Si) samples is quantitatively studied at broadband frequencies ranging from 1 to 20 GHz. Calibrated capacitance images of flat Si test samples with varying dopant density (10(15)-10(19) atoms cm(-3)) and covered with dielectric thin films of SiO2 (100-400 nm thickness) are measured to demonstrate the sensitivity of scanning microwave microscopy (SMM) for sub-surface imaging. Using standard SMM imaging conditions the dopant areas could still be sensed under a 400 nm thick oxide layer. Non-contact SMM imaging in lift-mode and constant height mode is quantitatively demonstrated on a 50 nm thick SiO2 test pad. The differences between non-contact and contact mode capacitances are studied with respect to the main parameters influencing the imaging contrast, namely the probe tip diameter and the tip-sample distance. Finite element modelling was used to further analyse the influence of the tip radius and the tip-sample distance on the SMM sensitivity. The understanding of how the two key parameters determine the SMM sensitivity and quantitative capacitances represents an important step towards its routine application for non-contact and sub-surface imaging.

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The charging of the dielectric used for the actuation in microelectromechanical system (MEMS) devices is one of the major failure sources for switches based on this technology. For this reason, a better understanding of such an effect is vital to improve the reliability for both ground and space applications. In this paper, the expected response of MEMS switches to unipolar and bipolar dc actuation voltages has been measured and modeled. Two configurations of MEMS switches, namely, an Ohmic series and a shunt capacitive one designed for microwave applications, have been studied as a test vehicle for charging effects related to the dc actuation pads. The recorded data have been interpreted mainly through the Poole–Frenkel effect due to charge injection when a high voltage is applied to the dielectric layer. Metal-Insulator-Metal (MIM) structures have been also considered as a complementary information for the response of the dielectric material.

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In this paper we present a novel process based on SU-8 technology for the fabrication of double clamped RF MEMS capacitive shunt switches in coplanar configuration. The key element of the exploited process is the MicroChem SU-8 2002 negative photoresist. The polymeric material is widely used in MEMS device processes because of its excellent thermal and chemical stability. In this paper, SU-8 polymer has been utilized in a double way to get suspended structures as double clamped beams: (i) SU-8 for the lateral supports, and (ii) as a sacrificial layer for the release of the suspended membrane. Preliminary RF tests on the manufactured switches have been done, and the measured electrical performances are in good agreement with the performed simulations

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The reliability of RF MEMS switches is typically reduced by charging effects occurring in the dielectrics. The aim of this paper is to discuss these effects, and to propose analytical and equivalent circuit models which account for most of the physical contributions present in the structure.