SANTA: Self-aligned nanotrench ablation via Joule heating for probing sub-20 nm devices

Manipulating materials at the nanometer scale is challenging, particularly if alignment with nanoscale electrodes is desired. Here, we describe a lithography-free, self-aligned nanotrench ablation (SANTA) technique to create nanoscale “trenches” in a polymer like poly(methyl methacrylate) (PMMA). The nanotrenches are self-aligned with carbon nanotube (CNT) or graphene ribbon electrodes through a simple Joule heating process. Using simulations and experiments we investigated how the Joule power, ambient temperature, PMMA thickness, and substrate properties affect the spatial resolution of this technique. We achieved sub-20 nm nanotrenches, for the first time, by lowering the ambient temperature and reducing the PMMA thickness. We also demonstrated a functioning nanoscale resistive memory (RRAM) bit selfaligned with a CNT control device, achieved through the SANTA approach. This technique provides an elegant and inexpensive method to probe nanoscale devices using self-aligned electrodes, without the use of conventional alignment or lithography steps.