6. Local Doping of Silicon Using Nanoimprint Lithography and Molecular Monolayers

Two fabrication schemes for the direct patterning of organic monolayers on oxide-free silicon are reported combining top-down nanoimprint lithography (NIL) and bottom-up monolayer formation. The first approach was designed to form monolayer patterns on the imprinted areas, while the second approach was designed for monolayer formation outside of the imprinted features. By both approaches, covalently bonded Si–C monolayer patterns with feature sizes ranging from 100 nm to 100 μm were created via a hydrosilylation procedure using diluted reagents. This novel patterning strategy was successfully applied for introducing dopant atoms using a phosphorus-containing molecular precursor on oxide-free silicon. The patterned sample was protected by a SiO₂ capping layer applied by e-beam evaporation and subjected to rapid thermal annealing (RTA) to diffuse the phosphorus dopant atoms into the bulk silicon locally. The doped sample was investigated by 3D time-of-flight secondary ion mass spectrometry (TOF–SIMS) and electrically characterized by Hall and Van der Pauw measurements.