Etching Characteristics of YMnO3 Thin Films in Cl Based Industively Coupled Plasma

Abstract

Ferroelectric YMnO3 thin films were etched with Ar/Cl2 and CF4/Cl2 plasma. The maximum etch rate of YMnO3 thin film was 300 Å/min at a Cl2/Ar gas mixing ratio of 8/2, an RF power of 800 W, a dc bias of –200 V, a chamber pressure of 15 mTorr, and a substrate temperature of 30 ºC. From the X-ray photoelectron spectroscopy (XPS) analysis, yttrium was not only etched by chemical reactions with Cl atoms, but also assisted by Ar ion bombardments in Ar/Cl2 plasma. In CF4/Cl2 plasma, yttrium formed nonvolatile YFx compounds and remained on and the etched surface of YMnO3. Manganese etched effectively by forming volatile MnClx and MnFy. From the X-ray diffraction (XRD) analysis, the (0004) diffraction peak intensity of the YMnO3 thin film etched in Ar/Cl2 plasma shows lower than that in CF4/Cl2 plasma. It indicates that the crystallinty of the YMnO3 thin film is more easily damaged by the Ar ion bombardment than the changes of stoichiometry due to nonvolatile etch by-products.