Bulk acoustic delay lines utilizing sub-micron platelet LiNbO3transducer

This article describes the fabrication technology and preliminary results of a new generation of bulk acoustic delay lines. The approach being taken is to use magnesium aluminate spinel (MgAl2O4) as the delay medium and to fabricate shear wave transducers from bulk lithium niobate (LiNbO3). We have recently developed a technology for fabrication of sub-micron bulk platelet instead of thin film transducers. Lithium niobate transducers with thicknesses as thin as 0.2 µm have been achieved. This technology employs a novel bonding technique, the room temperature vacuum bond, and a carefully controlled process of ion beam milling. Bulk wave acoustic delay lines consisting of LiNbO3transducers on spinel substrate have yielded very wideband and low loss operation in S-, C- and X-band frequencies.