In this letter we describe how highly porous nanostructures can be directly printed into a poly(methylsilsequioxane) (PMSQ)-based organosilicate film, with high pattern fidelity, and develop the measurement infrastructure to quantitatively evaluate the effects of the imprint process on the critical porosity characteristics. Positron annihilation lifetime spectroscopy (PALS) measurements reveal an enhanced intrinsic microporosity of the patterned organosilicate material. Mesopores with an average diameter of approximately 2.2 nm are then incorporated into this material by adding a second phase sacrificial pore generation material (porogen). PALS measurements reveal that patterning this material decreases the population of this porogen-induced mesoporosity while maintaining enhanced intrinsic microporosity. The net result is decreased average pore size and interconnectivity.X-ray porosimetry (XRP) measurements suitable for characterizing patterned samples, beyond planar films, are introduced here and used to quantify the increased intrinsic porosity and decreased induced porosity as a result of the nanoimprint patterning. The XRP measurements further indicate a porosity that decreases with pattern height for the sample with the induced porosity. The origins of the height dependent porosity are discussed in terms of a dense skin induced by the nanoimprint process which would be highly attractive as self-sealing porous patterns for semiconductor interconnect structures.
Citation: Advanced Materials
Pub Type: Journals
low-k, nanoimprint lithography, nanoporous pattern, PALS, pore sealing, X-ray reflectivity, XRP