Helium ion microscopy for low-damage characterization and sub-10 nm nanofabrication

This review introduces the technique of helium ion microscopy along with some unique applications of this technology in the fields of electronics and biology, as performed at the National Institute of Advanced Industrial Science and Technology, Japan, over the last several years. Observations of large-scale integrated circuits, analyses of low-dielectric-constant films with minimal damage, and assessments of copper metal in insulating films are discussed. The special characteristics of this technique are explained, including low-energy input to the material and minimal secondary electron energy resulting from helium ion irradiation. Applications to electronic materials, such as tuning the electrical conductivity of graphene films by helium ion beam irradiation and the formation of nanopore arrays on graphene films with nanometer-scale control, are presented. The use of helium ion microscopy to examine cellular tissues based on the low damage imparted by the ion beam is also evaluated.