PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION OF FILMS FOR IMPROVED VERTICAL ETCH PERFORMANCE IN 3D NAND MEMORY DEVICES

摘要

Implementations of the present disclosure generally relate to thin films incorporating high aspect ratio feature definitions and methods for forming the same. As gate height increases, 3D NAND gate stacks are subject to higher aspect ratio etching. Due to the current limitations of etching techniques, the vertical etch profile typically tapers as the depth into the gate stack increases. The inventors have devised a unique deposition scheme that compensates for etch performance degradation in deep trenches by a novel plasma-enhanced chemical vapor deposition (PECVD) film deposition method. The inventors have found that by grading various properties (e.g., refractive index, stress of the film, dopant concentration in the film) of the as-deposited films (e.g., silicon nitride) a more uniform etch profile can be achieved by compensating for variations in both dry and wet etch rates.

主权项

1. 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 first 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 and the second film layer are either a silicon oxide layer or a silicon nitride layer and wherein the first film layer is different from the second film 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; andrepeating (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 and the fourth film layer are either a silicon oxide layer or a silicon nitride layer and wherein the third film layer is different from the fourth film layer.