Facile transfer of thickness controllable poly(methyl methacrylate) patterns on a nanometer scale onto SiO ₂ substrates via microcontact printing combined with simplified langmuir-schaefer technique

We report on the facile patterning of poly (methyl methacrylate) (PMMA) layers onto SiO ₂ substrates via microcontact printing combined with the simplified Langmuir-Schaefer (LS) technique. Langmuir film of PMMA was formed just by dropping a dilute PMMA solution onto the air/water surface in a glass Petri dish via self-assembly, and it was used as an ink for the patterned poly(dimethylsilioxane) (PDMS) stamp. The transferred film properties were systematically investigated with variation of postannealing temperature, molecular weight of PMMA, and the inking number. The patterned PMMA film surface was smooth with no vacancy defect in a few micrometers scale AFM images over the whole film area after post-annealing process. The thickness of the PMMA patterns was controlled on the nanometer scale by the number of inkings of the LS layer of PMMA on the PDMS stamp. By using the PMMA patterns as a barrier and a sacrificial layer against the chemical etching and metal deposition, SiO ₂ and metal patterns were fabricated, respectively. The PMMA layers also worked as a passivation layer against the patterning of V ₂O ₅ nanowires and the selective adsorption of single-walled carbon nanotubes (SWCNTs). We also fabricated thin film transistors using patterned SWCNTs with different percolation states and investigated the electrical properties.