Model‐Based Analysis of the ZrO2 Etching Mechanism in Inductively Coupled BCl3/Ar and BCl3/CHF3/Ar Plasmas

The etching mechanism of ZrO 2 thin films and etch selectivity over some materials in both BCl 3 /Ar and BCl 3 /CHF 3 /Ar plasmas are investigated using a combination of experimental and modeling methods. To obtain the data on plasma composition and fluxes of active species, global (0-dimensional) plasma models are developed with Langmuir probe diagnostics data. In BC 3 /Ar plasma, changes in gas mixing ratio result in nonlinear changes of both densities and fluxes for Cl, BCl 2 , and BCl 2 + . In this work, it is shown that the non-monotonic behavior of the ZrO 2 etch rate as a function of the BCl 3 /Ar mixing ratio could be related to the ion-assisted etch mechanism and the ion-flux-limited etch regime. The addition of up to 33% CHF 3 to the BCl 3 -rich BCl 3 /Ar plasma does not influence the ZrO 2 etch rate, but it non-monotonically changes the etch rates of both Si and SiO 2 . The last effect can probably be associated with the corresponding behavior of the F atom density.

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