Characterization of structures maskless-etched by low-energy FIB

Characteristics of the structures microfabricated by 20-keV Ga⁺ FIB on Si have been investigated with AFM images and photographs from a Nomarski microscope. The images from AFM showed redeposition effect inside and near the edges of the holes etched by FIB. The images also showed significant damages of the as-implanted structures induced by high current density of FIB. The relationship between the dose of ion beam and the structures fabricated by FIB was studied. The results indicated that the depth of the structures is directly proportional to the dose of the ion beam with sputtering rate of 132 nm/minute, when the beam current is 28 pA. The depths of the fabricated structures in each material were directly proportional to the Mohs hardness of the material. The experimental results analysis also revealed the discrepancies between the beam diameter and the size of the structure, which is considered to be the results of combined effects from vibration, the part of ion beam with weaker intensity, and incomplete beam adjustment.