GAS FIELD ION SOURCE AND ION BEAM DEVICE

摘要

This gas field ion source is characterized by emitting an ion beam in at least two operation states including: a first operation state in which ions are emitted from a first ion emission region at the tip of an emitter electrode when ionized gas pressure is set to a first gas pressure and a first extracting voltage is applied; and a second operation state in which ions are emitted from a second ion emission region larger than the first ion emission region when the gas pressure is set to a second gas pressure larger than the first gas pressure and a second extracting voltage larger than the first extracting voltage is applied. This makes it possible to obtain a large ion beam current while suppressing the possibility of an emitter electrode being broken.