| 摘要 |
PURPOSE: A method of forming a floating gate of a flash memory device is provided to secure easily the margin of a photoresist pattern and to obtain uniform EFH(Effective Field oxide Height) from the entire surface of a wafer by performing a hard mask etching process using an oxide layer and a pad nitride layer as an etching mask. CONSTITUTION: A tunnel oxide layer(12), a first polysilicon layer(14), a pad nitride layer(16) and an oxide pattern(18) are sequentially formed on a semiconductor substrate(10). A trench(20) is formed in substrate by performing a hard mask etching process using the oxide pattern as an etching mask. A gap-fill oxide layer for filling completely the trench is formed thereon and the oxide pattern is removed by planarizing the resultant structure using the pad nitride layer as a barrier.
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