Patent ID: 7067425
Filing Date: 2006-06-27
Classification: H01L

Abstract:
1. A method of manufacturing a flash memory, comprising the steps of: performing an ion implantation process for adjusting a threshold voltage on a semiconductor substrate; sequentially forming a tunnel oxide film, a first polysilicon film and a pad nitride film on the semiconductor substrate; etching the pad oxide film, the first polysilicon film, the tunnel oxide film and the semiconductor substrate to form a trench defining an active region and a device isolation region; forming a nitride film on an entire surface of the trench by means of an annealing process to prevent the implanted ions for adjusting the threshold voltage from diffusing to the device isolation region; forming a side wall oxide film on a surface of the nitride film and a sidewall of the polysilicon film; and forming a device isolation film by filling up inside the trench.