Dear all, You are invited to the presentation for my Preliminary exam, the details of which are as follows. Coffee and cookies will be provided. Title: Charging and Transport in Amorphous Dielectrics and Reliability Implications for RF-MEMS Date: 01/29/2013 Time: 02:00 PM Venue: BRK 1001 Abstract: Thin film dielectrics have broad applications, and the performance degradation due to charge trapping in these thin films is an important and pervasive reliability concern. Historically, charge transport through dielectrics has been presumed to be either bulk dominated (Frenkel-Poole (FP) emission) or to be contact dominated (Fowler-Nordheim tunneling), dependent on the dielectric thickness. We develop a comprehensive dielectric charging modeling framework which solves for the transient and steady state charge accumulation and leakage currents in an amorphous dielectric, and show that for most thin film dielectrics in commercial use, the conventional assumption of FP dominated current transport is incorrect, and may lead to false extraction of dielectric properties. In order to correctly characterize dielectrics from their steady state leakage current characteristics, we propose an improved technique based on an analytical approximation of the dielectric charging model. We further show that our model replicates measured transient leakage characteristics in Silicon Nitride more accurately, given defect energy levels are known from first-principles calculations. Next, we study Radio Frequency Microelectromechanical Systems (RF-MEMS) capacitive switches as one of the target applications of these thin film dielectrics. Charge accumulation in dielectrics in RF-MEMS capacitive switches result in temporal shifts in actuation voltages, eventually resulting in failure due to stiction. Analysis and design of electromechanical actuators has historically been done on a case-by-case basis. We propose fundamental scaling relationships in electromechanical actuators in general, which are independent of specific physical dimensions and material properties. The scaling theory offers an intrinsic classification of all electromechanical actuators and consequently reduces the problem of analysis/design of complex electromechanical actuators to determining a few scaling parameters associated with specific geometry-classes. Finally, we propose a novel fully electronic, resonance based characterization technique for RF-MEMS capacitive switches to quantify degradation due to dielectric charging, which overcomes several limitations in conventionally used methods. The proposed technique also opens up possibilities for large scale parallelization for technology qualification and in-situ electronic degradation monitoring. In the future, we wish to generalize the theory of dielectric charging and degradation physics to polymer dielectrics. Even though polymer dielectrics are widely used as inter-layer dielectrics, diffusion barriers and passivants in conventional fabrication processes, their degradation is often modeled empirically. The techniques developed in this preliminary report will help explain and solve some of the long standing puzzles in this field.