Thin Film YBCO Pixels for MMW Detector

Abstract

This research addresses the fabrication of crack-free 40-nm thin film YBa2Cu3O7 (YBCO) pixel structures based on high temperature superconductor (HTSC) microbolometers for highly sensitive thermal detectors that can be miniaturized for affordable passive millimeter-wave (MMW) imaging. A completely dry etch process is described for suspended transition edge bolometers by removing (releasing) the silicon substrate underneath a 3 micrometer wide pixel using gaseous plasma sulfurhexafluoride (SF6) chemical reaction. This is an improvement over conventional selective wet chemical etching techniques that are both harsh on the YBCO and require additional complex alignment steps to the substrate material leading to very poor device yields and performance. Issues relating to material roughness, etch redeposition, and silicon undercutting will be analyzed and methodologies to overcome/minimize such problems will be explained in detail.