On the Effect of Oxygen on the Etch Behavior of ZrO2 in an Inductively Coupled BCl3/O-2 Plasma

Abstract

An investigation of ZrO2 etch behavior and mechanisms in a BCl3/O-2 inductively coupled plasma was carried out. An increase in the O-2 mixing ratio of up to 20 % was found to accelerate the ZrO2 etch rate, but to lower the ZrO2/SiO2 and the ZrO2/Si etch selectivities. Langmuir probe diagnostics was used to determine the effect of oxygen addition on the plasma parameters. Zero-dimensional plasma modeling indicated that both the formation kinetics and the densities of Cl atoms could be sufficiently influenced by the oxidative dissociation of BClx. From a model-based analysis of the etch kinetics, we showed that the experimentally mentioned behavior of the ZrO2 etch rate could result from an increase in the Cl atom density, but required a reaction-rate-limited etch process.