Pressure-Dependent Etching Mechanism and Induced Dielectric Properties Variation of BZN Thin Films in SF6/Ar Plasma

Abstract

Reactive ion etching was used to study bismuth zinc niobate (BZN) thin films etching in SF 6 /Ar plasma as a function of pressure. The etch rate increases as the pressure increases from 1 to 20 mTorr and decreases when the pressure exceeds 20 mTorr. The film surfaces were analyzed to determine the etching mechanism using X-ray photoelectron spectroscopy. Pressure is found to have an effect on etch reaction and non-volatile etch byproducts removal through different ion density and energy, thus resulting in varying compositions, element chemical binding states on the film surface. Dielectric properties of the film, modified by SF 6 /Ar plasma, show an obvious variation with pressure. The permittivity shows a slight decrease in the range of 1-20 mTorr but a sharp decrease at 30 mTorr. Instead, the dielectric loss variation exhibits an opposite trend.

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“…A higher ICP source power can give higher plasma density, while increasing the bias power can lead to higher energy of the bombarding etchant ions. As reported in the literature, we also observed that by raising either or both the powers [28,29] resulted in a higher etching rate [30], while raising the ICP power and/or gas pressure [31] leads to an increase in the etching rate as well as the undercut [32] in the masked area.…”