Affordable OTM Phased Array Antennas: Design and Fabrication of Temperature Stable and Performance Consistent Phase Shifters; Conference paper

摘要

Electronically scanned phased array antennas (ESAs) provide the means for achieving high data rate, beyond line of sight, on-the-move (OTM) communications. The phase shifter is a key component of ESAs, and the Army's Communications Engineering Research and Development Center (CERDEC) has recently acknowledged BaSrTiO3 (BST) thin film technology as the premier candidate for achieving affordable high performance phase shifter elements. Unfortunately, there is concern that in practical applications the device performance will be compromised due to the temperature dependence of the BST based device capacitance. We report a material design which controls the magnitude and the sign of the temperature coefficient of capacitance (TCC) via a multilayer paraelectric BST/buffer layer/ferroelectric BST coplanar device structure. To realize this multilayer device structure we have designed, fabricated, and optimized an Al doped Ta2O5 barrier layer with low loss, moderate permittivity, low TCC, and excellent bias stability of capacitance. The integration of the barrier layer with the BST layers was optimized for structure, microstructure, interfacial/surface morphology, and dielectric properties as a function of Al doping concentration, annealing temperature, material growth and integration process parameters.