| 摘要 |
PURPOSE:To provide uniform etching characteristics, by introducing He gas into an etching chamber in an amount equivalent to or larger than a total flow of an etching gas for a short period of time intermediate of a process for etching single wafers, so that the single wafers can be treated uniformly. CONSTITUTION:In order to etch a wafer 4 having an SiO2 film, the inside of a treating vasin 6 is evacuated to a vacuum and an etching gas is supplied to between electrodes 2 and 3 through a gas inlet 1. High-frequency power is supplied to the electrodes 2 and 3 from a high-frequency power supply 5, whereby discharge plasma is produced. When a sheet of object has been treated, He gas is subsequently introduced in an amount larger than that of the introduced etching gas so as to establish a pressure of 100-500 Pa, which is held for 5-20 seconds. The supply of the He gas is stopped and, after the inside of the treating vasin 6 is evacuated, the treated sheet object is exchanged with a new untreated one. In this manner, it is possible to minimize difference in etching rate among wafers, ununiform etching within one wafer and variation in possiblity for selectively etching the wafer with respect to underlying layers or photoresist.
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