Fabrication of molecular-electronic circuits by nanoimprint lithography at low temperatures and pressures

We have utilized a modified version of thermal nanoimprint lithography to fabricate a rewritable, nonvolatile, molecular memory device with a density of 6.4 Gbit/cm(2). It has the advantages of a relatively low operating temperature of (similar to70degreesC) and pressure of (<500 psi or 4.5 MPa), both of which are critical to preserving the integrity of the molecular layer. The architecture of the circuit was based on an 8x8 crossbar structure, with an active molecular layer sandwiched between the top and bottom electrodes. A liftoff process was utilized to produce the top and bottom electrodes made of Pt/Ti bilayers. The active molecular layer was deposited by the Languir-Blodgett technique. We utilized a new class of nanoimprint resist formulated by dissolving a polymer in its monomer. The formulation we used, was poly(benzyl methacrylate), dissolved in benzyl methacrylate with t-butyl peroxy 2-ethylhexanoate added as a self-initiator (8:90:2 by weight). The new resist allowed us to achieve Pt/Ti lines of 40 nm in width and 130 nm in pitch.