Plasma enhanced chemical vapor deposition of films for improved vertical etch performance in 3D NAND memory devices

A method for forming a high aspect ratio feature, comprising:

• depositing one or more silicon oxide/silicon nitride containing stacks on a substrate positioned in a processing chamber and in the presence of a vacuum, wherein depositing the one or more silicon oxide/silicon nitride containing stacks comprises:
• (a) energizing a first process gas into a first plasma;
• (b) depositing a first film layer on the substrate from the first plasma;
• (c) energizing a second process gas into a second plasma;
• (d) depositing a second film layer on the first film layer from the second plasma, wherein the second film layer has a refractive index;
• repeating (a), (b), (c), and (d) until a predetermined number of first film layers and second film layers have been deposited on the substrate, wherein the first film layer is a silicon oxide layer and the second film layer is a silicon nitride layer;
• (e) energizing a third process gas into a third plasma;
• (f) depositing a third film layer on a previous layer from the third plasma;
• (g) energizing a fourth process gas into a fourth plasma;
• (h) depositing a fourth film layer on the third film layer from the fourth plasma, wherein the fourth film layer has a refractive index greater than the refractive index of the second film layer;
• repeating (e), (f), (g), and (h) until a predetermined number of third film layers and fourth film layers have been deposited, wherein the third film layer is a silicon oxide layer and the fourth film layer is a silicon nitride layer;
• and
• forming one or more high aspect ratio features in the one or more silicon oxide/silicon nitride containing stacks using plasma etching or wet etching techniques, wherein the high aspect ratio feature has a height to width ratio of at least about 5:1 or more.