High aspect ratio fabrications of micro journal air bearings for micro gas turbine engine

In micro fabricated gas turbine engine, a micro journal air bearing is used to offer high speed and low wear operations. Fabrication of such a journal bearing is a critical challenge since the clearance of the bearing is only several micrometers with aspect ratio of more than 20. This paper reports on the fabrication of ultra-high aspect ratio micro journal air bearing using ICP DRIE (inductively coupled plasma deep reactive ion etching) process. The process parameters that resulted in bowed and tapered journal bearing were investigated to improve the profile of the etched journal bearing. Micro journal bearings with sidewall verticality of almost 90° were obtained.