Vibration Assisted Nanopositioning: An Enabler of Low-cost, High-throughput Nanotech Processes

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Nanotechnology is one of the most promising areas of technological development, and among the most likely to deliver substantial economic and societal benefits to the U.S. in the 21st century. Nanopositioning stages are mechanical devices used for precise positioning in a wide range of nanotech processes, ranging from spectroscopy to micro additive manufacturing. Hence their positioning speed and cost are critical to the throughput and scale up of many nanotech processes. Stages that use roller bearings are currently the only commercially viable option for a growing number of large-displacement nanopositioning applications performed in ultrahigh vacuum environments. However, roller bearing stages suffer from very low positioning speeds due to the adverse effects of so-called pre-rolling friction. This award supports a scientific investigation into a novel approach for mitigating the effects of pre-rolling friction on roller bearing nanopositioning stages by applying high frequency vibration to the stage. Results from this research will increase the positioning speed of roller bearing nanopositioning stages without significantly increasing their costs, hence enabling the scale up and increased throughput of a wide range of nanotech processes. This research is focused on vibration-assisted nanopositioning: a novel approach for applying high frequency vibration, combined with active vibration control, to nanopositioning stages. The objective of this research is to understand the interactions between high frequency vibration, pre-rolling friction, controller dynamics, and positioning speed. The method of direct partition of motion will be used to determine the influence of vibration parameters (vibration frequency and amplitude) on pre-rolling friction and stage position control, under ideal conditions where there is no active vibration control. Perturbation analyses (e.g., using the Poincaré-Lindstedt method) will then be carried out to understand the effects of active vibration control combined with high frequency vibration on the vibration of the stage. Control techniques that will be investigated include sliding mode control and harmonic cancellation control. In all analyses, pre-rolling friction will be modeled with increasing levels of complexity, starting from the simple Dahl model and building up to the Generalized Maxwell Slip model, in order to gain progressive insights into the effects of each model and its parameters on the results of the analyses. A simple roller bearing nanopositioning stage will be used to conduct point-to-point positioning experiments, with various high frequency vibration frequencies/amplitudes, friction conditions, and control techniques, to validate the theoretical analyses.