PATTERNING FOR VARIABLE DEPTH STRUCTURES

摘要

A method of forming a NAND flash memory includes forming a dielectric layer over NAND strings separated by shallow trench isolation structures, forming an opening in a mask layer over the dielectric layer, the opening extending over contact areas, the opening having a first width at first locations over contact areas and having a second width at second locations over shallow trench isolation structures, the second width being less than the first width.

主权项

1. A method of forming a NAND flash memory comprising:
forming an array of NAND flash memory cells across a surface of a silicon substrate, the NAND flash memory cells arranged in NAND strings, each NAND string having contact areas at ends, neighboring NAND strings separated by a shallow trench isolation structure; subsequently forming a dielectric layer over the NAND strings and the shallow trench isolation structures; subsequently forming a mask layer over the silicon substrate; and subsequently forming an opening in the mask layer, the opening being elongated along a direction that is perpendicular to the NAND strings, the opening extending over a plurality of contact areas, having a first width at first locations over contact areas and having a second width at second locations over shallow trench isolation structures, the second width being less than the first width.