고밀도 Cl₂/Ar 플라즈마를 이용한 YMnO₃ 박막의 식각 특성에 관한 연구

A Study on the Etching characteristics of YMnO₃ Thin Films in High Density Cl₂/Ar Plasma

Ferroelectric YMnO₃ thin films are excellent dielectric materials for high integrated ferroelectric random access memory (FRAM) with metal-ferroelectric-silicon field effect transistor (MFSFET) structure. In this study, YMnO₃ thin films were etched with Cl₂/Ar gas chemistries in inductively coupled plasma (ICP). The maximum etch rate of YMnO₃ thin films is 285 A/min under Cl₂/Ar of 10/0, 600 W/-200 V and 15mTorr. The selectivities of YMnO₃ over CeO₂ and Y₂O₃ are 2.85, 1.72, respectively. The results of x-ray photoelectron spectroscopy (XPS) reflect that Y is removed dominantly by chemical reaction between Y and Cl, while Mn is removed more effective by Ar ion bombardment than chemical reaction. The results of secondary ion mass spectrometer (SIMS) were equal to these of XPS. The etch profile of the etched YMnO₃ film is approximately 65˚ and free of residues at the sidewall.