Control of a Two-Axis Micromanipulator-Based Scanning Probe System for 2.5-D Nanometrology

This paper presents a versatile atomic-force-microscope (AFM)-based two-axis probing system for 2.5-D nanometrology. Central to this system is a two-axis compliant micromanipulator based on the AFM probe whose orientation and position can be actively changed in the scanning plane. Three enabling technologies are proposed to uniformly scan the section of the sample surface within this plane. First, an orientation control system is developed that controls the tip-orientation to track the changes in normal of the surface section. Second, tapping mode-based tip-sample interaction scheme is developed wherein the direction of tip oscillation and the peak force are controlled, according to the local orientation of the section. Third, a two-axis scanning scheme is developed wherein the scanning and interaction control axes are aligned along the tangent and normal to the local section. Taken together, these technologies enable the entire scanning process to conform to the geometry of the sample in the scanning plane and facilitate metrology of samples with large geometric variation along the two axes. In this paper, the developed probing system is used to scan the entire top surface of a micropipette and demonstrate greater access and absence of artifacts when compared to a conventional scan.