Optimizing the reactive ion etching conditions with minimal damage for high functional magnetic nano device application in BiFeO3-based thin film by Eu/Co substitution

Abstract

To reduce energy consumption in magnetic devices, effective magnetization control by electric fields is essential. Ferromagnetic and ferroelectric thin films are promising materials for the magnetization control by electric field. However, the BiFeO3-based thin films having good magnetic properties are developed, but there is no discussion about suitable microfabrication procedures which are important for growth of damage free magnetic devices. To determine the suitable etching conditions with low magnetic damage in BiFeO3-based (Bi,Eu)(Fe,Co)O3 thin film with high saturation magnetization, low coercivity, ferroelectricity, suitable reactive ion etching (RIE) conditions as well as process parameters for microfabrication procedures were investigated. A very poor etching rate, resulting in minimal material removal was obtained, when reactive etching gas of SF6 was used. We could achieve an efficient etching rate by using CHF3 as reactive etching gas, but morphological and magnetic damage were observed. One reason for this damage was the generation of oxygen vacancies in the grain boundaries. Effective etching rates with minimized damage were realized when CHF3/O2 was used as reactive etching gas.