Chemistries for etching multi-stacked layers

A method for fabricating a 3D NAND flash memory having alternating layers of a first etching layer and a second etching layer on a substrate and a hardmask layer on the alternating layers, the method comprising 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 of the first etching layer and the second etching layer 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.