Sharp Needles: Fabrication of Tungsten Nanotips by AC Electrochemical Etching and Laser Enhanced Etching for Nanoprobing on Interconnects of Advanced Technology Nodes.

ABSTRACTSharper nanotips are required for application in nanoprobing systems due to a shrinking contact size with each new transistor technology node. We describe a two-step etching process to fabricate W nanotips with controllable tip dimensions. The first process is an optimized AC electrochemical etching in KOH to fabricate nanotips with a radius of curvature (ROC) down to 90 nm. This was followed by a secondary nanotip sharpening process by laser irradiation in KOH. High aspect ratio nanotips with ROC close to 20 nm were obtained. Finally we demonstrate the application of the fabricated nanotips for nanoprobing on advanced technology SRAM devices.