Patterned polymer growth on silicon surfaces using microcontact printing and surface-initiated polymerization

Patterned polymer films were grown on SiO₂/Si surfaces by a process starting with microcontact printing (μCP) of octadecyltrichlorosilane (OTS), formation of a monolayer derived from norbornenyl trichlorosilane (Nbn-SiCl₃) in areas not protected by OTS, activation of the surfaces derived from Nbn-SiCl₃ with a ruthenium catalyst, and surface-initiated ring-opening metathesis polymerization of derivatives of norbornene by the catalytically active ruthenium species. These patterned polymer films were successfully used as reactive ion etching resists. The combination of μCP and surface-initiated polymerization makes possible molecular-level control of polymer composition and thickness in both lateral and vertical directions: the smallest patterned lateral features were 2 μm lines; this width was determined by the features of the stamp used in μCP and is not the intrinsic limit of the method. The thickness of the polymer film was, typically, 5-100 nm and could be controlled by monomer concentration and reaction time.