| 摘要 |
PURPOSE: A doping method for a gate electrode of a flash memory device is provided to prevent a file-up of dopant and a remaining of polysilicon during an etch of the gate electrode. CONSTITUTION: After a gate oxide(20) is deposited on a semiconductor substrate(10), a lower polysilicon layer(30) is formed from an undoped amorphous polysilicon. The lower polysilicon layer(30) is then doped by POCl3 at a first temperature of about 800°C to about 900°C, and subsequently annealed to uniform construction thereof at a second temperature higher than the first temperature. Next, an oxide-nitride-oxide insulation layer(40) is formed on the lower polysilicon layer(30), and subsequently an undoped normal polysilicon layer(50) is formed as an upper polysilicon layer. The upper polysilicon layer(50) is then doped and annealed like the lower polysilicon layer(30). Next, after a gate electrode is formed by a selective etch of the whole layers(20,30,40,50) on the substrate(10), a spacer(60) is formed on sidewalls of the gate electrode. Besides, an inter-poly oxide(70) and a borophosphosilicate glass(BPSG) layer(80) are formed.
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