Abstract: A gaseous mixture of SF.sub.6, a nitriding gas component and an oxidizer gas component is disclosed as an effective SiO.sub.2 etchant having enhanced selectively for use in either the plasma or reactive ion etch process. By adding an oxidizing gas to the SF.sub.6 nitriding gas plasma etchant, the selectively for SiO.sub.2 over silicon or polysilicon is marked improved. The optional addition of an inert diluent gas did not substantially change these results.

Abstract: BF.sub.3 based mixtures for selectively etching thin layers of silicon dioxide over silicon for use in the plasma etch process for integrated circuits manufacture is disclosed.In the process, when trace amounts of formaldehyde are added to the etch system the rate on oxide inceases markedly. The effect on the silicon is not substantial. The optional addition of an inert diluent gas did not substantially change these results.

Abstract: A gaseous mixture of SF.sub.6 and a nitriding component such as NH.sub.3 is disclosed as an effective selective SiO.sub.2 etchant for use in either the plasma or reactive ion etch process. By adding NH.sub.3 to the SF.sub.6, which is a known effective plasma etchant for silicon or poly-silicon, the silicon etch rate decreases while the oxide rate is effectively constant. At about 14% nitriding gas component, the rates are equivalent and for higher nitriding gas fractions, the silicon dioxide rate dominates. The optional addition of an inert diluent gas did not substantially change these results. The addition of hydrogen to the gaseous SF.sub.6 /nitriding component mixture retards the etch rate on silicon still further and may increase the selectivity.