Nanoscale lithography via electron beam induced deposition

We demonstrate the resolution and characteristics of a nanolithography process utilizing electron beam induced deposition (EBID) of W(CO)6 and C10H8 to define the imaging and masking layers. Lines and dot matrices were defined/written with various electron beam doses onto both polymethylmethacrylate (PMMA) coated silicon substrates (PMMA-Si) and bare silicon substrates (Si). The selectivity of the W(CO)x for the PMMA dry development process (no measurable etching) and the silicon (∼18:1) reactive ion etch was very good. C10H8 directly patterned on Si also provided good selectivity for the silicon etch process, 21:1. The pattern transfer of the EBID material patterns into the silicon had high fidelity. The resolution scaled with exposure dose and was correlated with the EBID broadening/scattering via a Monte Carlo simulation. Using the bi-layer approach, imaging layers on PMMA-Si, a silicon nanowire resolution of 13.5 nm and linewidth of 24.5 nm are demonstrated. Furthermore, using the single-layer approach, EBID directly on Si, a silicon nanowire resolution of 33 nm is demonstrated.