Sacrificial-film removal method and substrate processing device

A sacrificial-film removal method of removing a sacrificial film from a surface of a substrate provided with a plurality of struts, the sacrificial film being embedded between the plurality of struts, wherein a natural oxide film and a supporting film support the plurality of struts and have a plurality of hole portions, the method including:

• a wet etching step where the sacrificial film is removed to its halfway depth by supplying an etchant to the surface of the substrate;
• a rinse step where a residue adhering to the surface of the substrate is washed out by supplying a rinsing liquid to the surface of the substrate after the wet etching step;
• a drying step where a liquid component on the surface of the substrate is removed after the rinse step;
• a dry etching step where the sacrificial film remaining on the surface of the substrate is removed by supplying an etching gas to the surface of the substrate after the drying step, and
• a preprocessing step where the natural oxide film formed on the surface of the supporting film is removed prior to the wet etching step,
• wherein removal by the etchant is started from portions of the sacrificial film corresponding to the plurality of hole portions in the wet etching step.