Method for forming 3D NAND flash memory

The invention relates to the technical field of semiconductor manufacturing, in particular to a method for forming a 3D NAND flash memory. The method comprises the steps that firstly, different stairs are made on the part where steps are opened through 1+log2N levels of light covers and the etching technology to form differences; then, 2N stairs are etched at a time through 1 level of a light cover or PR trimming and etching. Thus, the technological steps are reduced, and meanwhile technological cost is reduced. 本发明涉及半导体制造技术领域，尤其涉及种形成3D NAND闪存的方法，先通过1+㏒2N道光罩和刻蚀工艺将台阶打开的地方做成不同阶梯的差异，然后通过1道光罩或PR 修剪和刻蚀，1次刻蚀出2N个阶梯，从而减少工艺步骤，同时节省了工艺成本。