RF characterization of Mg0.2Zn0.8O thin film capacitors for MMIC applications

Mg_0.2Zn_0.8O thin films are proposed as a new dielectric material for monolithic microwave integrated circuit (MMIC) to replace current dielectric materials due to its high permittivity which can lead to size reduction, in addition to being compatible with semiconductor processing. In this work, Mg_0.2Zn_0.8O films were prepared using sol gel spin coating technique, and the films were deposited on Pt-coated Si substrates. Energy dispersive analysis by X-ray (EDAX), scanning (SEM) and field emission scanning electron (FESEM) microscopes were used to study the structural properties. The film thickness was found to be approximately between 0.3 to 0.4 μm with grain sizes about 25 nm. In order to study the radio frequency (RF) properties, capacitors with 50 × 50 μm² electrode area were patterned on the MgZnO layer using electron beam lithography (EBL). In this work, we report the RF properties of these films which were measured using Wiltron 37269A vector network analyzer (VNA) and Cascade Microtech on-wafer probes measured over the frequency range of 0.5 to 3 GHz. Our findings show that the films exhibit dielectric constant values between 5 to 55, and loss tangent between 0.02 and 0.04. We feel that our results represent the best RF performance so far by MgZnO films.