Patent ID: 8703619

Claim:
A taper-etching method for taper-etching a layer to be etched, the layer to be etched being made of a dielectric material and having a top surface, the taper-etching method comprising the steps of: forming an etching mask on the top surface of the layer to be etched, the etching mask having an opening; and taper-etching a portion of the layer to be etched, the portion being exposed from the opening, by reactive ion etching so that a groove having two wall faces that intersect at a predetermined angle is formed in the layer to be etched, wherein the step of taper-etching employs an etching gas containing a first gas contributing to the etching of the layer to be etched and a second gas contributing to deposition of a sidewall protective film, and changes, during the step, a ratio of a flow rate of the second gas to a flow rate of the first gas so that the ratio increases, wherein the layer to be etched is made of Al2O3, and the second gas contain at least one of N2 and CF4.