Ammonia annealed and wet oxidized LPCVD oxide to replace ono films for high integrated flash memory devices

摘要

In one embodiment, the present invention relates to a method of forming a flash memory cell, involving the steps of forming a tunnel oxide on a substrate; forming a first polysilicon layer over the tunnel oxide; forming an insulating layer over the first polysilicon layer, the insulating layer comprising an oxide layer made by low pressure chemical vapor deposition at a temperature from about 600 C. to about 850. degree. C. using SiH.sub.4 and N.sub.2 O, annealing in an NH.sub.3 atmosphere at a temperature from about 800 C. to about 900. degree. C., and wet oxidizing using O.sub.2 and H.sub.2 at a temperature from about 820 C. to about 880 C.; forming a second polysilicon layer over the insulating layer; etching at least the first polysilicon layer, the second polysilicon layer and the insulating layer, thereby defining at least one stacked gate structure; and forming a source region and a drain region in the substrate, thereby forming at least one memory cell.