MANUFACTURING METHOD OF SEMICONDUCTOR DEVICE

PROBLEM TO BE SOLVED: To provide the manufacturing method of a semiconductor device that improves the reproducibility of the etching of slant-part formation, and prevents etching liquid from being contaminated by the peeling of a resist film when a taper angle θ at a slant part is small. SOLUTION: This manufacturing method of the semiconductor device includes a process that forms an oxide film 2 to be etched at first etching speed to the etching liquid on a substrate 1, a process that forms a thin-film layer 3 that is etched at second etching speed to the etching liquid on the oxide film 2, a process that removes one portion of the thin-film layer 3 for forming a cutout part 4, a process that forms a resist film 10 that fills the cutout part 4 and at the same time covers a region that becomes a slant part 24 in the thin-film layer 3, and a process that simultaneously etches the oxide film 2 and thin-film layer 3 by the etching liquid, and a process that forms the slant part 24 having the taper angle θ that is determined at the first and second etching speeds.