Proximity X-ray lithography using self-assembled alkylsiloxane films: Resolution and pattern transfer

Self-assembled films of octadecyltrichlorosilane (OTS) on Si/SiO2 were patt erned with proximity X-rays (lambda = 1.0 nm) in air, resulting in the inco rporation of oxygen-containing functional groups, that is, hydroxyl and ald ehyde, into the film. Unexposed and exposed OTS exhibited sufficient chemic al contrast for patterning processes based on differences in wetting behavi or and chemical reactivity. Latent images of features as small as similar t o 70 nm, defined by the X-ray mask, were successfully fabricated in the OTS with high fidelity over areas of similar to1 cm(2). Patterned OTS was imag ed directly with lateral force microscopy and indirectly through atomic for ce microscopy of three-dimensional structures formed on the surface of thin films of diblock copolymers after deposition and annealing on the patterne d OTS. Pattern transfer of features with dimensions as small as similar to 150 nm into the underlying silicon substrate was achieved by reactive ion e tching using thin films of nickel selectively deposited onto the exposed ar eas of the OTS as etch masks.