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With increase in the number of three dimensional (3-D) nanometer-scale objects that are being either fabricated or studied, there is a need to accurately characterize their geometry. While the Atomic force microscope (AFM) is a versatile tool for performing nano-metrology, it suffers from issues of poor accessibility of 3-D features and inability to measure 3-D forces that limit its applicability in 3-D nano-metrology. This thesis investigates the design and development of a novel probing system based on AFM that improves accessibility and enables direct measurement of 3-D forces acting on the AFM tip. Two approaches are investigated to address the issue of poor accessibility. The first is to develop a novel system that enables in-situ replacement and reuse of specialized AFM tips that improve accessibility, and the second is to design a special AFM tip that can actively re-orient about two independent axes. In order to perform in-situ tip replacement, a liquid meniscus based micro-gripper is developed and integrated on to a conventional AFM probe. The stiffness of the gripper is analyzed and shown to be adequately high along all three axes for AFM imaging to be performed. Tip replacement and re-use are both experimentally demonstrated by employing a novel tip-exchange station. The replaced tips are employed to show artifact-free AFM imaging of a standard calibration grating in both tapping-mode and contact-mode. To actively re-orient a conventional tip, a novel magnetically-actuated micro-scale ball-and-socket joint is integrated onto an AFM probe. The quasi-static behavior of the joint is experimentally characterized, and the ability of the tip to independently re-orient about two axes is demonstrated. The achieved range is about +/- 90 degrees about both X- and Y-axes. In order to realize the potential of the proposed probes for 3-D nano-metrology, an AFM is developed in-house that possesses the capability to make direct measurement of 3-D forces. Optimization of the measurement system to achieve identical sensitivities and resolution along all three axes is studied. Subsequently, the necessary electronics for measurement, actuation and control are developed. All the subsystems are experimentally calibrated and integrated. The overall AFM is shown to have a resolution of about 0.2 nm when operated in tapping-mode. The developed AFM is employed to showcase the following applications: characterization of the coefficient of kinetic friction of Muscovite mica, force controlled nano-scribing on polymethyl methacrylate (PMMA) and tapping-mode imaging of a calibration grating with the developed re-orientable AFM probe. Finally, the unique ability of the re-orientable AFM probe to control its tip-orientation is employed to develop a nanometer-scale coordinate measurement machine (CMM). The developed nano-CMM is shown to access the vertical wall of a sample and obtain its topography.

No description available.

Ultraprecision single point diamond turning is required to produce parts with sub-nanometer surface roughness and sub-micrometer surface profiles tolerances. These parts have applications in the optics industry, where tight form accuracy is required while achieving high surface finish quality. Generally, parts can be polished to achieve the desired finish, but then the form accuracy can easily be lost in the process rendering the part unusable. Currently, most mid to low spatial frequency surface finish errors are inspected offline. This is done by physically removing the workpiece from the machining fixture and mounting the part in a laser interferometer. This action introduces errors in itself through minute differences in the support conditions of the over constrained part on a machine as compared to the mounting conditions used for part measurement. Once removed, the fixture induced stresses and the part’s internal residual stresses relax and change the shape of the generally thin parts machined in these applications. Thereby, the offline inspection provides an erroneous description of the performance of the machine. This research explores the use of a single, high resolution, capacitance sensor to quickly and qualitatively measure the low to mid spatial frequencies on the workpiece surface, while it is mounted in a fixture on a standard ultraprecision single point diamond turning machine after a standard facing operation. Following initial testing, a strong qualitative correlation exists between the surface profiling on a standard offline system and this online measuring system. Despite environmental effects and the effects of the machine on the measurement system, the capacitive system with some modifications and awareness of its measurement method is a viable option for measuring mid to low spatial frequencies on a workpiece surface mounted on an ultraprecision machine with a resolution of 1nm with an error band of ±5nm with a 20kHz bandwidth. / Thesis / Master of Applied Science (MASc)