Direct Writing Of High Frequency Surface Acoustic Waves Using Focus Ion Beam Etching.

The fabrication of Radio-Frequency Surface Acoustic Wave devices is mainly based on lithography techniques allowing for accurate and repetitive mass production of resonators and filters. The possibility of manufacturing single devices operating at the very limit of material properties for research purposes has been demonstrated using Electron-beam lithography machines, allowing to largely overcome the 10 GHz threshold. In this paper, we propose an original alternative to lithography techniques based on the Focused Ion Beam etching technique to fabricate SAW devices by directly "writing" the electrode pattern in the metal overlay. The fundaments of this technology are exposed in the first section of the paper. Examples of devices are then shown, illustrating the quality of the processed devices and the capability to fabricate accurate sub-micron patterns. After characterizing the fabricated devices, the conclusion will discuss the expected limit of such an approach for the fabrication of SAW devices.