Ionic liquids: nondestructive, nonvolatile imaging fluids for submicrometer-scale monolayer patterns.

A method for visualizing submicrometer-scale patterns of approximately 1.0-nm-thick monolayers terminated with CF(3) and CH(3) groups using an ionic liquid (IL) is described. Bis(hydroxyethyl)dimethylammonium methanesulfonate (BHDAMS) was spin-cast onto the photolithographically patterned samples. The BHDAMS wetted the photodecomposed regions selectively. Pattern widths of the mask ranged from 500 nm to 10 microm, and the IL-replicated patterns were observed using optical and laser microscopy. The nonvolatile BHDAMS had sufficient contrast to image submicrometer-scale patterns of monolayers over large areas. We note that this imaging technique involves no damage and is compatible with readily available laboratory equipment.