Study of the effect of layer thickness, beam energy, and metal density on the resistless silicide direct-write electron-beam lithography process for the fabrication of nanostructures

To overcome the limitation of resists in electron beam lithography, a resis tless electron beam lithography technique was recently developed. In the si licide direct-write electron-beam lithography process (SiDWEL), a thin meta llic film is deposited on a silicon surface. A low-energy (<3 keV) electron beam is then used to enable the intermixing of the metal and the silicon l ayers through thermal effects. A chemical etch is then used to remove the u nexposed metal regions. Thermal calculations are performed using a Monte Ca rlo simulation of electron trajectories and are correlated with experiments using Ni as the thin metallic film. A comparison of the doses required for the formation of several metals is also done. Results show that the SiDWEL process is possible when the electrons lose all their energy in a layer th ickness comparable to the phonon mean free path. Finally, experiments are p erformed using multilayer samples to form silicide structures. (C) 2000 Ame rican Vacuum Society. [S0734-2101(00)02702-0].