Anisotropic etching characteristics of platinum electrode for ferroelectric capacitor

Abstract

The effect of etch parameters of platinum etching using Cl-2/CO plasma on the etching properties and the etch profiles was investigated. The etching characteristics with respect to substrate temperature are different in two temperature regions below and above 210 degrees C and significantly depended on Cl-2 concentration in each temperature region. The etch rates of Pt were enhanced suddenly at the substrate temperature of around 210 degrees C when Cl-2 concentration is 50-80%, The etch rates of Pt below 210 degrees C did not change much with increasing temperature. The selectivity of Pt over SiO2 was governed by the etch rate of SiO2 in the lower temperature region but determined by the etch rates of Pt in the higher temperature region. The anisotropy of etch profiles was high enough to achieve vertical pattern without etch residues in the lower temperature region for the application in fabricating 1-Gbit era. In the higher temperature region, however, the slopes of etch profiles due to the volatile products of Pt were found. XPS was used to analyze the surface atomic compositions after various etching treatments.