Overpressure contact printing

This paper describes a new method of using elastomeric stamps in the fabrication of patterned self-assembled monolayers and nanoparticles. By applying load on top of poly(dimethylsiloxane) (PDMS) stamps, we showed that new structure arrays of various materials could be generated on silicon wafer and metal substrates through the controlled deformation of elastomeric stamps. The feature sizes of the patterns generated by this technique have been shown to be up to an order of a magnitude smaller than those on the stamps. The created patterns also may not exist on the original masters; thus, this approach can be unique in making patterns at a reduced size that can sometimes be hard to fabricate otherwise. We referred this method as overpressure contact printing (oCP). By combining the patterned Langmuir-Blodgett (pLB) technique and oCP, we made arrays of FePt magnetic rings from Pt@Fe₂O₃ core-shell nanoparticles. Such rings resemble one basic prototype of structures used for magnetic random access memory (MRAM) applications. The patterned structures were characterized by field emission scanning electron microscopy (SEM), atomic force microscopy (AFM), and magnetic force microscopy (MFM).