Patent ID: 9548313
Date: 2017-01-17
CPC Classifications: H01L

Claim:
1. A method of making a monolithic three dimensional NAND string, comprising: forming a select gate layer of a third material over a major surface of a substrate; forming a stack of alternating first material and second material layers over the select gate layer, wherein the first material, the second material and the third material are different from each other; etching the stack using a first etch chemistry to form at least one opening in the stack at least to the select gate layer, such that the select gate layer acts as an etch stop layer during the step of etching; further etching the select gate layer using a second etch chemistry, wherein the second etch chemistry is different from the first etch chemistry; and forming a semiconductor channel and at least one charge storage region of the NAND string in the stack; wherein at least one end portion of the semiconductor channel extends substantially perpendicular to the major surface of the substrate; and wherein the at least one charge storage region is located adjacent to semiconductor channel.