TWI844993B

According to the present invention, a substrate W is provided with a recess 95. The width of the recess 95 is smaller than the depth of the recess 95. An etching target which is at least one of a single crystal of silicon, a polysilicon and an amorphous silicon is exposed in at least a part of the upper part of a lateral surface 95s and in at least a part of the lower part of the lateral surface 95s. The etching target is etched by supplying an alkaline first etching liquid, in which an inert gas is dissolved, to the substrate W. The etching target is etched by supplying an alkaline second etching liquid, in which a dissolution gas is dissolved, and which has a dissolved oxygen concentration higher than that of the first etching liquid, to the substrate W before or after the first etching liquid is supplied to the substrate W.