| 摘要 |
According to the present invention, high-k film can be etched to provide a desired geometry without damaging the silicon underlying material. A silicon oxide film 52 is formed on a silicon substrate 50 by thermal oxidation, and a high dielectric constant insulating film 54 comprising HfSiOx is formed thereon. Thereafter, polycrystalline silicon layer 56 and high dielectric constant insulating film 54 are selectively removed in stages by a dry etching through a mask of the resist layer 58 , and subsequently, the residual portion of the high dielectric constant insulating film 54 and the silicon oxide film 52 are selectively removed by wet etching through a mask of polycrystalline silicon layer 56 . A liquid mixture of phosphoric acid and sulfuric acid is employed for the etchant solution. The temperature of the etchant solution is preferably equal to or lower than 200 degree C., and more preferably equal to or less than 180 degree C.
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