Circuit and Integration Technologies for Molecular Electronics

Abstract

Methods for fabricating a 2D array of gold nanoparticles were investigated for the purpose of creating a cross-linked molecular network. A controllable process for quickly and easily depositing and patterning regions of gold nanoparticles was developed. This process involves first patterning gold electrodes used for electrical measurement on the wafers. Regions are then defined in photoresist where the dense gold nanoparticles are desired. Finally, the nanoparticles are deposited using a short evaporation, resulting in island formation through the Volmer-Weber growth mechanism. The resist is then stripped in a process known as liftoff, and the result is a wafer-scale substrate with well-defined regions for molecular interconnect. Before assembly, these structures conduct less than 110pA of current at submicron electrode gap distances, and often less than 20pA.

As determined from SEM image analysis, it is possible to quickly and easily deposit and pattern regions on silicon dioxide containing over 4,100 per um2, each with an average area of approximately 80nm2. The number of particles, average area and fill density can be controlled to allow for a number of applications and at a variety of scales. The smaller, more numerous particles integrate into sub-500nm gaps, and the larger, meandering lines integrate into micron-scale structures.