Method manifesting a wide process window and using hexafluoropropane or

Abstract

A plasma etch process, particularly applicable to a self-aligned contact etch or other advanced structures requiring high-selectivity to nitride or other non-oxide materials and no etch stop. The process is preferably performed in a high-density plasma reactor for etching holes with either high or low aspect rations. In this process, hexafluoropropane (C.sub.3 H.sub.2 F.sub.6) is the principal etching gas in the presence of a substantial amount of an inactive gas such as argon. The process can also be used with the closely related gases heptafluoropropane (C.sub.3 HF.sub.7) and pentafluoropropane (C.sub.3 H.sub.3 F.sub.5). The process may use one or more of the these gases in proportions to optimize selectivity over other materials without the occurrence of etch stop in narrow contact holes and with a wide process window. Difluoromethane (CH.sub.2 F.sub.2) or other fluorocarbons may be combined with the above gases for optimum selectivity for a design of a specific contact feature.