Patent ID: 7723236

Claim:
A gas setting method for setting mixing ratios and flow rates of gaseous mixtures supplied into a processing chamber in which substrates are etched, the method comprising: performing etchings on a part of the substrates while fixing a mixing ratio and a flow rate of a first gaseous mixture and changing a mixing ratio of a second gaseous mixture, and thereafter, setting the mixing ratio of the second gaseous mixture based on etching results thereof such that at least one of an etching selectivity and an etching shape is made uniform throughout central portions and outer peripheral portions of the part of the substrates, wherein while performing the etchings on the part of the substrates, the first and the second gaseous mixture are supplied to the central portions and the outer peripheral portions of the part of the substrates, respectively; and then performing etchings on a remaining part of the substrates while fixing the mixing ratio and the flow rate of the first gaseous mixture and the mixture ratio of the second gaseous mixture and changing a flow rate of the second gaseous mixture, and thereafter, setting the flow rate of the second gaseous mixture based on etching results thereof such that etching rates in the central portions and the outer peripheral portions of the remaining part of the substrates are made uniform, wherein while performing the etchings on the remaining part of the substrates, the first and the second gaseous mixture are supplied to the central portions and the outer peripheral portions of the remaining part of the substrates, respectively.