Uncoated observation and etching of non-conductive materials by ion beam bombardment in scanning electron microscopy

In a scanning electron microscope, techniques of uncoated observation and subsequent observation of internal and intracellular structures in nonconductive materials removed by ion beam etching have been successfully obtained. An apparatus in which a beam of argon ions is collimated and focused by an electrostatic lens onto an appropriate target and in addition, the specimens are both cooled and rotated during processing to avoid artifacts and thermal damages has been used. Organic and biological specimens can be directly observed without coating of metallic films by pre-bombardment of argon ions. High resolution images of structural details eroded by ion beam etching and coupled with tungsten sputter coating have been clearly observed. The role of angle of incidence of ion beam and accelerating voltage in determining the optimum etching condition without artifacts are experimentally obtained for soft biological specimens as well as hard materials. Step and general views of internal structures in soft biological specimens as well as ceramics and polyvinyl chlorides eroded by cleaning and subsequent etching are revealed without artifacts and thermal damages.