Conductive polycrystalline diamond probes for local anodic oxidation lithography

Abstract

This is the first report characterizing local anodic oxidation (LAO) lithography performed using conductive monolithic polycrystalline diamond (MD) and conductive polycrystalline diamond-coated (DC) tips and comparing it to the diamond-like carbon-coated and metal-coated silicon tips. The range and the rate of increase in the lithographic linewidth and height with tip bias (dw/dV and dh/dV) differed based on the tip material. The DC tips resulted in wider and taller lines and a higher dw/dV and dh/dV compared to metal-coated tips with a similar force constant (kAvg). The metal-coated and the DC tips with comparable kAvg showed comparable threshold voltages, whereas the MD tips with similar kAvg showed a higher threshold voltage. The MD tips exhibited less than half the height and nearly half the dw/dV and dh/dV obtained with the metal-coated tips with similar kAvg, thus also resulting in a smaller width at −10 V. The linewidths were found to be proportional to the inverse of the log of write speed ( for all the tips; however, the proportionality constant varied with tip material; the DC tips had larger values, and the MD and the metal-coated tips had comparable values. When varying the speed, the height was found to be a sigmoidal function of width, with the MD probes achieving lower height compared to the metal-coated and the DC tips with comparable kAvg. This study expands the application of monolithic conductive polycrystalline diamond (PCD) probes with outstanding wear resistance to fine LAO lithography.