| 摘要 |
PURPOSE: To prevent a gate oxidized film and a substrate from being damaged at the time of performing patterning for forming the gate electrode of a MOSFET. CONSTITUTION: An SiO2 gate oxidized film 11 and a polysilicon gate electrode film 12 are formed on a substrate 10, and the electrode film 12 is patterned by dry etching by utilizing a photoresist mask 13. In the patterning step, the polysilicon film 12 is left by about 100 Å in thickness by main etching which is performed while a Cl2/HBr/CF4 gas is made to flow and the thickness of the film 12 is measured. Then the remaining portion of the film 12 is removed by over-etching which is performed while HBr/O2 is made to flow. Even in a high-pattern density area, consequently, the formation of sub-trenches is suppressed by the presence of the CF4 and the surfaces of the gate oxidized film and substrate can be prevented from being damaged.
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