Chemistries for etching multi-stacked layers

摘要

Methods for fabricating a 3D NAND flash memory are disclosed. The method includes the steps of forming a hardmask pattern on the hardmask layer, and using the hardmask pattern to form apertures in the alternating layers by selectively plasma etching the alternating layers versus the hardmask layer using a hydrofluorocarbon etching gas selected from the group consisting of 1,1,1,3,3,3-hexafluoropropane (C₃H₂F₆), 1,1,2,2,3,3-hexafluoropropane (iso-C₃H₂F₆), 1,1,1,2,3,3,3-heptafluoropropane (C₃HF₇), and 1,1,1,2,2,3,3-heptafluoropropane (iso-C₃HF₇), wherein the first etching layer comprises a material different from that of the second etching layer.