| CPC B01F 35/82 (2022.01) [B01F 23/231 (2022.01); B01F 23/237611 (2022.01); B01F 23/237612 (2022.01); B01F 23/23765 (2022.01); B01F 35/2132 (2022.01); B01F 35/2202 (2022.01); G05D 11/00 (2013.01); G05D 21/02 (2013.01); H01L 21/30608 (2013.01); H01L 21/32134 (2013.01); H01L 21/67017 (2013.01); H01L 21/67028 (2013.01); H01L 21/67051 (2013.01); H01L 21/67075 (2013.01); H01L 21/6708 (2013.01); B01F 2101/58 (2022.01)] | 9 Claims |

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1. A chemical liquid preparation method of preparing a chemical liquid to be supplied to a substrate,
the chemical liquid being a TMAH-containing chemical liquid which contains tetramethylammonium hydroxide (TMAH),
the chemical liquid preparation method comprising:
a correspondence relationship preparing step of preparing a correspondence relationship between a supply flow rate ratio between an oxygen-containing gas and an inert-gas-containing gas and a convergent dissolved oxygen concentration in the TMAH-containing chemical liquid that is converged to when the oxygen-containing gas and the inert-gas-containing gas are supplied into the TMAH-containing chemical liquid at the supply flow rate ratio,
a concentration setting step of setting a target dissolved oxygen concentration in the TMAH-containing chemical liquid that corresponds to a desired etching rate,
a supply-flow-rate-ratio acquiring step of acquiring the supply flow rate ratio between the oxygen-containing gas and the inert-gas-containing gas corresponding to the target dissolved oxygen concentration in accordance with the correspondence relationship prepared in the correspondence relationship preparing step, and
a gas supplying step of supplying the oxygen-containing gas and the inert-gas-containing gas with the supply flow rate ratio acquired in the supply-flow-rate-ratio acquiring step.
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