A macro-micro motion system for a scanning tunneling microscope

Abstract

As nano-lithography technology improves, more companies and research groups have the capability to create nano-scale structures. Scanning tunneling microscopes (STMs) are commonly used to create these structures and evaluate them afterward. One difficulty is that these nanostructures are difficult to find on a one centimeter-size die cut from a silicon wafer without very specialized hardware and post-processing and analysis. The National Institute of Standards and Technology (NIST) is conducting research into developing a macro-micro motion system that would allow these nano-structures to be more effectively located and identified on the die. An XY stage system using linear piezo-actuators can perform the macro motion by moving the sample to where the STM tip can scan a particular region of the die to make an analysis. The STM tip would then perform the micro motion by scanning the region for the nano-structure. A vibration isolation system has been designed for this macro-micro motion system using springs and eddy current dampers. This vibration isolation system will isolate the entire system from the outside world and the individual components from each other. A high-precision interferometer system is also installed to independently monitor a flexure driven stage for the STM tip. A graphical programming system was developed for controlling the motion of the STM tip. All of these systems combine to form the initial steps toward coordinated closed-loop control of the STM.