Abstract: A technique for creating openings in a polycarbonate film entails providing a liquid chemical formulation that contains polycarbonate material, a liquid that dissolves the polycarbonate, and possibly one or more other constituents. The liquid is typically capable of dissolving the polycarbonate to a concentration of at least 1% at 20.degree. C. and 1 atmosphere. Examples of the liquid include pyridine, a ring-substituted pyridine derivative, pyrrole, a ring-substituted pyrrole derivative, pyrrolidine, a pyrrolidine derivative, chlorobenzene, and cyclohexanone. A liquid film (36A) of the chemical formulation is formed over a substructure (30) and processed to remove the liquid, thereby converting the liquid film into a solid polycarbonate track layer (38). Charged particles (70) are passed through the track layer to form charged-particle tracks (72) at least partway through the layer. Apertures (74) are created through the track layer by a process that entails etching along the tracks.