A Study on Reactive Ion Etching of Barium Strontium Titanate Films Using Mixtures of Argon (Ar), Carbon Tetrafluoride (CF4), and Sulfur Hexafluoride (SF6)

Report No. ARL-TR-6979
Authors: Samuel G. Hirsch; Ryan C. Toonen; Eric H. Ngo; Mathew P. Ivill; M.W. Cole
Date/Pages: July 2014; 14 pages
Abstract: Barium Strontium Titanate (BST) is a complex oxide material with ferroic properties which has been considered for applications ranging from non-volatile memory to microwave tunable devices. When grown in bulk films BST forms a continuum of domains. It is theorized however, that when the material can be grown on the order of a single domain, its properties will drastically change. To exploit the ferroic properties of BST we developed a device fabrication method utilizing self-aligned etching to create metal-insulator-metal (MIM) varactors. As part of this method we employed reactive ion etching (RIE) to remove BST and create cylindrical island stacks consisting of platinum top electrodes, atop a layer of BST, atop a platinum bottom electrode film, all on top of a sapphire substrate. Here we report and compare the results of a study on using RIE to remove BST using combinations of three gas, argon (Ar), carbon tetrafluoride (CF4), and sulfur hexafluroride (SF6).
Distribution: Approved for public release
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Last Update / Reviewed: July 1, 2014