FABRICATION OF STAIRCASE STRUCTURE BY ANISOTROPIC DEEP REACTIVE ION SILICON ETCHING

Abstract

In recent years, semiconductor developers have successfully scaled 2D NAND flash to sub-20-nm technology, but further 2D NAND scalability will be a considerable challenge. However, the recent advancement in the processes of deep reactive ion etching (DRIE) with its option to pattern photoresist onto the silicon substrate independent from its crystal orientation has opened up a bunch of new applications in various fields.

By integrating the application of multiple photoresist patterning and the application of DRIE of high aspect ratio features, this dissertation presents the outcome of investigations of a novel process whereby 3D NAND flash memory devices with ten-step structure with controlled depths and widths were fabricated successfully. The improvement of the fabrication process will act as a road-map to optimize the manufacturing process of 3D NAND flash memory products whereby reduction in cost and cycle time can be achieved without disregarding the reliability of the NAND system produced.