Soft lithographic patterning of oxide thin films

An emerging non-photolithographic technology, soft lithography, is applied with the aim of patterning ferroelectric thin film oxides, in particular sol-gel deposited Lead Zirconate Titanate (PZT). Soft lithography relies on the replication of a patterned master using an elastomeric material and then, using this as a stamp to create micro- and nanometre scale patterns and structures. Following this procedure, a set of masters were fabricated both using photolithographic and Focused Ion Beam (FIB) methods. Masters were replicated using a commercial polymer (PDMS), satisfactorily reproducing the negative of the master's features down to a limit of 500 nm. The obtained stamps were used to produce patterned self-assembled monolayers (SAMs) of alkanethiols over surfaces of gold, using the technique of microcontact printing (mCP). The patterned SAMs were then employed as a molecular thin resist to create microstructures of gold by wet etching. This is a key step for establishing a new route for the fabrication of ferroelectric thin film capacitors made of Pt/PZT/Au by Reactive Ion Etching (RIE) using the patterned gold features as both mask and top electrode, thus avoiding alignment stages in the fabrication procedure.