On the etching mechanism of ZrO2 thin films in inductively coupled BCl3/Ar plasma

The etching mechanism of ZrO2 thin films in BCl3/Ar plasma was investigated using a combination of experimental and modeling methods. It was found that an increase in the Ar mixing ratio causes the non-monotonic behavior of the ZrO2 etch rate which reaches a maximum of 41.4 nm/min at about 30–35% Ar. Langmuir probe measurements and plasma modeling indicated the noticeable influence of a BCl3/Ar mixture composition on plasma parameters and active species kinetics that results in non-linear changes of both densities and fluxes for Cl, BCl2 and BCl2+. From the model-based analysis of surface kinetics, it was shown that the non-monotonic behavior of the ZrO2 etch rate can be associated with the concurrence of chemical and physical pathways in ion-assisted chemical reaction.