Environmentally Benign Reactive Ion Etching of Complex-Oxide Films

A research and development program is proposed for developing and implementing a low temperature, highly anisotropic, reliable, environmentally benign reactive ion etching (RIE) for complex-oxide films. The RIE Process will be optimized such that it is highly selective (e.g., >5), with high etch rates (e.g., >50 nm/min) and there i minimal or no damage to underlying layers. Furthermore, effort will be focused on preserving film stoichiometry at the widewalls. Two different approaches will be pursued to achieve the goals of this project. The first approach is based on the use of etch gases which have very low values of ozone depletion potential (ODP) and global warming potential (GWP). Three potential etch gases have been identified, and preliminary studies using one of them resulted in very encouraging results. The second approach is very novel and based on a very broad and a new concept, which we call "Etching by Inverse MOCVD." The concept is simple in that, etching is performed by in-situ formation of metalorganic precursors by plasma/ion induced chemical reactions between the film to be etched and appropriate organic compounds. Inducing the reactions by plasma/ions is mandatory for anisotropic etching requirements. We have shown the proof of this concept (e.g., high selectivity and reasonable etch rates) for ferroelectrics, high T superconducitng oxides, and metlas. For the proposed project, our preliminary studies will be expanded for developing an optimized etch process which can be easily transferred to companies like Motorola for incorporating in their ferroelectric device processing schemes. Anticipated Benefits: Demonstration of reliable etching of complex-oxide films; establishment of new field entitled "Inverse-MOCVD.", extension to semiconductors