Bis-PCBM-Containing Electrically Conducting Electron-Beam Resist for Nanometer-Scale Organic Devices

A significant challenge with organic devices is simultaneously controlling the lateral sizes and positions of structures at the nanometer scale. This study utilized nanocomposite electron-beam (EB) organic resists due to their excellent electrically conductive components for lateral-scale electronic devices at the nanometer scale. The resist patterning and carrier conduction characteristics of the positive EB resist of ZEP520A containing bis(1-[3-(methoxycarbonyl)propyl]-1-phenyl)-[6,6]C₆₂: bis-PCBM were investigated. Regarding the resist patterning characteristics, line patterns (square patterns) of ZEP520A containing bis-PCBM were successfully implemented with outward widths (side lengths) of less than 200 nm utilizing a straightforward process that only uses EB exposure and development. The disappearance of bis-PCBM aggregations in the line patterns was observed near the sidewalls after development, owing to the penetration of the developer and rinse solution. As the bis-PCBM concentration increased relative to ZEP520A, less voltage was required to produce the same current. The carrier conduction mechanisms can be successfully explained by the fluctuation-induced tunneling conduction theory, which accounts for the thermally increasing temperature dependence of the current at high temperatures and the carrier conduction (similar to the normally temperature-independent tunneling mechanism) at extremely low temperatures. To obtain the current–voltage characteristics of ZEP520A containing bis-PCBM, the voltage drop across the diode with the same layers (but without the composite resist layer) was subtracted from the voltage drop across the entire diode device. The proposed composite resist demonstrates potential for use in highly sensitive biosensors with nanometer-wide channels for multiplexed and simultaneous diagnoses and in organic quantum information devices.