METHOD FOR FABRICATING FLASH MEMORY DEVICE

摘要

PURPOSE: A method for fabricating a flash memory device is provided to decrease the processing steps and increase the coupling ratio of a floating gate by using a lower oxide film or an upper oxide film of a dielectric film to prevent the floating gate damaging. CONSTITUTION: A tunnel oxide film(42) and the first polysilicon layer(43) are formed on a substrate(40). By depositing a lower oxide film(50), a dielectric nitride film(51) and an upper oxide film(52) on the first polysilicon film, a dielectric film is formed. After the first nitride film is formed on the dielectric film, a patterning process is performed by using a floating gate mask, and a spacer is formed on the sidewall of the first nitride film by using the second nitride film. The dielectric film and the first polysilicon layer(43) are patterned using the first and the second nitride film as a mask. A polyoxide film(48) is formed on the sidewall of the first polysilicon layer(43). The first and the second nitride film are removed by using the polyoxide film(48) and the dielectric film as an anti-etching film. After the second poly silicon layer(53) is formed on the whole structure, a floating gate and a control gate are formed by using a control gate mask.