Dry Etching Mechanisms of ZrO2 Thin Films in BCl3/Cl2/Ar Plasma

Abstract

We investigated etching behavior of ZrO 2 thin films and selectivity of ZrO 2 thin films to SiO 2 and Si 3 N 4 by using inductively coupled plasma system. Experimental results have shown that higher etch rate of ZrO 2 thin films was achieved by the reactive ion etching using Cl radicals due to the high volatility of B x Cl y O z . Consequently, the increased chemical effect was caused to the increase in the etch rate of the ZrO 2 thin film. Small addition of Cl 2 to the BCl 3 /Ar mixture increased selectivities of ZrO 2 thin films to SiO 2 and Si 3 N 4 . The surface analysis by x-ray photoelectron spectroscopy (XPS) showed some evidences that Zr and O were reacted with Cl and BCl and formed nonvolatile metal chlorides and volatile boron-oxy-chlorides. This effect can be related to the concurrence of chemical and physical pathways in the ion assisted chemical reaction.