Design and Fabrication of an Automatic Nanoscale Tool-Tip Exchanger for Scanning Probe Microscopy

The scanning probe microscope (SPM), in particular the atomic force microscope (AFM), is widely used as a metrology tool at the nanoscale. Recently, the instrument has shown tremendous potential to perform various nanoscale fabrication processes (e.g. nanolithography, atomic deposition, nanomachining, etc.) with high resolution (< 10 nm). However, use of SPMs for fabrication have a low throughput and require frequent manual replacement of the SPM tips due to damage or wear. Manual switching of tips for multiple operations, is relatively time consuming. Thus these issues hinder the throughput, quality, reliability, and scalability of SPM as a practical tool for nanofabrication. To address these issues, this paper presents the design, analysis, and fabrication of a novel nano tool-tip exchanger that automatically loads and unloads SPM tool-tips. The ability to provide fully automated on-demand tool-tip exchange would enable SPM as a scalable tool for nanomanufacturing. In this work, an active SPM cantilever is designed with an electrothermally actuated microgripper capable of locating, loading, and unloading tool-tips automatically. The microgripper has been designed to provide adequate range of actuation, gripping force, stiffness, and dynamic response required for securely holding the tool-tip and for functioning within existing SPM-based systems. The design has been validated by finite element analysis. Experiments have been conducted to establish the micro-electro-mechanical systems (MEMS) fabrication processes for successful fabrication of the prototype.