Processing method and apparatus using focused energy beam

A processing method using a focused ion beam for etching a multilayer device having a metal wiring layer located under an insulating layer, said method comprising the steps of:

• introducing mixed reactant gases comprising a first reactive etching gas for said insulating layer and a second reactive etching gas for said second metal wiring layer into a processing chamber containing said multilayer device, said first reactive etching gas being a fluorine gas and said second reactive etching gas being a chlorine gas;
• irradiating said focused ion beam onto a local portion of a surface of said multilayer device in the presence of said mixed reactant gases;
• and,
• forming an etching hole by etch-reacting said mixed reactant gases on said local portion of said multilayer sample with said irradiated focused ion beam without changing between the introduction of said first reactive etching gas and said second reactive etching gas.