An etching apparatus comprises a workpiece holder (21) for holding a workpiece (X), a plasma generator (10, 20) for generating a plasma (30) in a vacuum chamber (3), an orifice electrode (4) disposed between the workpiece holder (21) and the plasma generator (10, 20), and a grid electrode (5) disposed upstream of the orifice electrode (4) in the vacuum chamber (3). The orifice electrode (4) has orifices (4a) defined therein. The etching apparatus further comprises a voltage applying unit (25, 26) for applying a voltage between the orifice electrode (4) and the grid electrode (5) to accelerate ions from the plasma (30) generated by the plasma generator (10, 20) and to pass the extracted ions through the orifices (4a) in the orifice electrode (4), for generating a collimated neutral particle beam having an energy ranging from 10 eV to 50 eV.