Design and Analysis of Scanning Probe Microscopy Cantilevers With Microthermal Actuation

The scanning probe microscope has revolutionized our ability to image and characterize the physical and chemical properties of material with atomic resolution. It has evolved as a versatile instrument for nanofabrication including atomic deposition, nanolithography, nanomachining, atomic manipulation, and assembly. However, in order to enable practical nanofabrication with scanning probe tips, it is critical to address the issues of throughput, tip wear effects, chemical cross contamination, and scalability. In this paper, we address these issues by designing, optimizing, fabricating, and testing active electromechanical cantilever probes with an integrated microgripper for automated modular tip exchange. The cantilevers are designed and optimized to be compatible with existing atomic force microscope systems. Mechanical performance and optimization are carried out by the development of an analytical electrothermomechanical model and multiphysics finite-element analysis. The silicon cantilevers are formed by microfabrication processes and characterized by scanning electron microscopy, laser vibrometry, and in situ optical microscopy current-voltage studies. The cantilever grippers are shown to actuate with a maximum displacement of 3 μm for each arm at an applied voltage of 4 V 6-μm total displacement for grasping modular tool-tips. Gripping is demonstrated by grasping and releasing of a cylindrical microtool (wire).

I. Introduction

Since the invention of the scanning probe microscope (SPM) more than three decades ago, in particular the atomic force microscope (AFM), has become a powerful tool for surface-topography imaging and metrology of features down to atomic-scale resolution [1], [2].