| 摘要 |
A method for manufacturing a flash memory device is provided to lower effectively EFH(Effective Field Height) of an isolation layer without causing an attack to a floating gate. A tunnel oxide layer(102) and a first polysilicon layer(104) are formed on a semiconductor substrate(100). A trench is formed by etching partially the first polysilicon layer, the tunnel oxide layer, and the semiconductor substrate. An isolation layer(106) is formed within the trench. A second polysilicon layer(108), a hard mask nitride layer, and a head mask oxide layer are sequentially formed on the entire structure. The hard mask nitride layer and the hard mask oxide layer are patterned to expose an upper part of the second polysilicon layer. The second polysilicon layer and the isolation layer under the second polysilicon layer are etched by using the patterned hard mask oxide layer and the patterned hard mask nitride layer as etch masks.
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