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US 11,107,729 B2Granted
Semiconductor memory device and manufacturing method thereof
AssigneeSK hynix Inc.
InventorNam Jae Lee
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Abstract
A process of forming a 3D memory device includes forming a stacked structure with a plurality of stacked layers, etching the stacked structure to form stepped trenches each comprising a plurality of steps, forming a hard mask layer with a plurality of openings over the stepped trenches, forming a photoresist layer over the hard mask layer, and etching through the plurality of openings using the hard mask layer and the photoresist layers as an etch mask to extend a bottom of the stepped trenches to a lower depth.
Claims20
A method for forming a semiconductor device, the method comprising:
- forming a stacked structure having a plurality of stacked layers;
- forming a plurality of stepped trenches having a first depth in the stacked structure by etching the stacked structure, each of the stepped trenches having first and second opposing stepped sidewalls that each have a plurality of steps;
- forming an etch stop pattern having a hard mask material over a top surface of the stacked structure, the etch stop pattern including a plurality of openings exposing portions of the plurality of stepped trenches;
- forming a first photoresist pattern over the etch stop pattern, the first photoresist pattern filling a first portion of the openings and exposing a second portion of the openings;
- and
- etching the second portion of the openings using the etch stop pattern as an etch mask to extend a bottom of the stepped trenches exposed by the second portion of the openings to a second depth lower than the first depth.
3 more elements
Dependencies are inferred from the claim text.