Directly patterning dielectric insulator materials via nanoimprint lithography has the potential to simplify fabrication processes and significantly reduce the manufacturing costs for semiconductor devices. However, the prospect of mechanically forming these materials that typically suffer from poor mechanical properties, especially in their porous form, raises concerns regarding their integrity. We demonstrate that sub-100 nm features can be imprinted into a silsequioxane material that displays an enhanced modulus after vitrification in both its non-porous and porous forms. An excellent fidelity of the pattern transfer is quantified with nm precision using critical dimension small angle X-ray scattering and specular X-ray reflectivity. The porosity of the patterns is characterized with X-ray porosimetry and positron annihilation lifetime spectroscopy. In the material without the pore generating additive (porogen), imprinting increases the level of microporosity. For the sample with the porogen, imprinting decreases the mesoporosity while increasing the microporosity, effectively decreasing the interconnectivity of the pores. There is evidence for an imprint-induce sealing of the porous patterns and we interpret this to be a skin of porogen-free matrix material at the surface of the imprinted pattern.
Citation: Advanced Materials
Pub Type: Journals
critical dimension, low-k dielectric, nanoimprint lithography, organosilicate, patterning, porosity, positron annihilation lifetime, small angle x-ray scattering