Resolution Limits of Focused-Ion-Beam Resist Patterning
ABSTRACTWe have recently demonstrated the ability to focus a 50-keV Ga+ beam to an 8-nm-diameter spot diameter. This ultra-high resolution probe has been used to study the resolution limits of conventional resists for focused-ion-beam lithography. Lines and dots in poly (methylmethacrylate) resist as small as 7–8 nm have been formed with high throughput. In addition, no proximity effects have been observed for 25 to 30-nm size features on high-z substrates. However, for the smallest geometries obtainable, the pattern fidelity and resolution are most likely limited by ion scattering effects and statistical dose fluctuations. The use of lighter ions (such as He, Li, or Be) with lower sensitivity resists should, in principle, allow focused-ion-beam lithography to be extended to the sub-5 nm regime.