Patent ID: 8298955

Claim:
An etching method comprising the steps of: providing an object including a substrate, an underlying film made of a silicon-containing film formed on the substrate, and a film to be etched that is made of a tungsten-containing film formed on the underlying film; and using a plasma of a process gas to carry out an etching process for the object, wherein: a chlorine-containing gas, an oxygen-containing gas, and a nitrogen-containing gas are used as the process gas to etch the tungsten-containing film under a condition that an N 2 + /N 2 intensity ratio of N 2 + to N 2 , derived from emission spectra of the Plasma, is at least 0.6, the chlorine-containing gas is a Cl 2 gas, the oxygen-containing gas is an O 2 gas, and the nitrogen-containing gas is an N 2 gas, and the silicon-containing film is a polysilicon film, and the tungsten-containing film is a tungsten film of a stacked structure of a tungsten nitride film and a tungsten film.