| 摘要 |
PURPOSE: A forming method of polysilicon electrode in a semiconductor device is provided to improve the quality of an oxide layer on an electrode. CONSTITUTION: A polysilicon layer is vaporized on a wafer using an LPCVD(Low Pressure Chemical Vapor Deposition) method at 620 deg.C. The wafer is loaded into a furnace, filled with N2 gas and at 800 deg.C. Until 830 deg.C or 850 deg.C, the temperature of the furnace is increased. Doping source gases as such as POCl3, N2, and O3 gas are injected, and doping process is executed. The doping time depends on the doping density. After the doping process, remained POCl3 gas is removed by injected N2 gas. N2 gas is injected more than 20 litters per minute. Drive-in process is enforced with injecting N2 gas after lifting up the temperature to 850 deg.C or 900 deg.C. Maintaining the temperature as 800 deg.C, the wafer is unloaded. An oxide layer is formed on the polysilicon layer through thermal oxidation process in 900 deg.C.
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