Etching method and plasma processing apparatus

An etching method comprising:

• preparing a substrate having laminated films including a first film and a second film that are alternately laminated, and a mask on the laminated films;
• and
• etching the laminated films by plasma of a process gas including a carbon and fluorine-containing gas that includes an unsaturated bond of C and a CF3 group, via the mask, thereby forming a recess in the laminated films, wherein
• the carbon and fluorine-containing gas dissociates, in the plasma, into a carbon fragment having the unsaturated bond of C and preferentially sticking on top of the mask during the etching, and a fluorocarbon fragment having the CF3 group and transported via the mask to a bottom of the recess and further etching the laminated films,
• the preparing uses the mask including, in a plan view, a plurality of first openings, and a plurality of second openings positioned to surround outer sides of the plurality of first openings, and
• the mask, in the plan view, includes no openings formed on outer sides of the plurality of second openings.