유도 결합 플라즈마(Cl₂/Ar)를 이용한 CeO₂ 박막의 식각 특성 연구

A Study on the Etching Characteristics of CeO₂ Thin Films using inductively coulped Cl₂/Ar Plasma

Cerium oxide thin film has been proposed as a buffer layer between the ferroelectric film and the Si substrate in Metal-Ferroelectric-Insulator-Silicon (MFIS) structures for ferroelectric random access memory (FRAM) applications. In this study, CeO₂ thin films were etched with Cl₂/Ar gas combination in an inductively coupled plasma (ICP). The highest etch rate of CeO₂ film is 230 A/min at Cl₂/(Cl₂+Ar) gas mixing ratio of 0.2. This result confirms that CeO₂ thin film is dominantly etched by Ar ions bombardment and is assisted by chemical reaction of Cl radicals. The selectivity of CeO₂ to YMnO₃ was 1.83. As a XPS analysis, the surface of etched CeO₂ thin films was existed in Ce-Cl bond by chemical reaction between Ce and Cl. The results of XPS analysis were confirmed by SIMS analysis. The existence of Ce-Cl bonding was proven at 176.15 (a.m.u.).