A plasma processing method includes (a) providing a substrate on a substrate support in a chamber, the substrate having an underlying film, a first film on the underlying film, and a second film on the first film, the first film and the second film providing an opening exposing the underlying film, the second film comprising silicon; and (b) removing the second film by plasma generated from a process gas without supplying an electrical bias to the substrate support or by supplying an electrical bias having a level of 200 W or less, or 1 kV or less to the substrate support, the plasma comprising a hydrogen fluoride etchant.