| 摘要 |
PURPOSE:To increase the selection ratio of SiO2 with respect to Si by providing a control device to an introducing pipe for introducing an etching gas into a vacuum vessel and controlling the pressure and residence time of the etching gas in the vacuum vessel. CONSTITUTION:A material A to be treated, i.e., an Si substrate formed thereon with an SiO2 film, is imposed atop a lower electrode 4 and after the inside of the vacuum vessel 1 is evacuated to a vacuum by a vacuum evacuating device 9, the etching gas (CF4) is introduced through a gas introducing pipe 8 into the vessel. The etching gaseous pressure in the vessel 1 is maintained under a high pressure of 400Pa by a control device 11 in this stage and etching is executed by turning on an RF power source 7 to impress high-frequency electric power to the lower electrode 4, thereby generating plasma 12. The control device 11 controls the flow rate of the etching gas to that the residence time per unit of the etching gas in the vessel 1 is maintained for >=4sec. The selection ratio of SiO2 with respect to Si is thus remarkably increased.
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