Simple microfabrication process for quartz crystal using HF gas and catalytic materials

The fabrication of deep and vertical shape trench structures on quartz crystal has been difficult because of its crystal orientations and high chemical durability. In this study, we propose a new type of simple microfabrication process for quartz crystal substrates using hydrogen fluoride (HF) gas and catalytic materials. A vertical trench structure was obtained on AT-, X-, and Z-cut quartz crystal substrates using the proposed process. The results suggest that the chemical reactions in this process mostly proceed at the catalyst contact area on the substrate. In addition, the chemical reaction pathway between HF gas and catalyst on quartz substrates was discussed using density functional theory calculations. This unique microfabrication process will grow the market of new conceptual acoustic devices using quartz crystals.