Control approach to high-speed large-range AFM imaging and nanofabrication

2009 2009

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Abstract (summary)

In this thesis, two inversion-based feedforward control approaches have been developed and implemented to high-speed large-range atomic force microscope (AFM) imaging and nanofabrication, respectively. High-speed large-range AFM imaging and nanofabrication are needed in many areas and have attracted great interests. Challenges, however, must be overcome because in high-speed large-range AFM operation, large positioning error of the AFM probe relative to the sample can be generated due to the adverse effects of the hardware. The nonlinear hysteresis and the vibrational dynamics effects of the piezotube actuator must be addressed during the high-speed lateral scanning of the AFM imaging over large imaging size. In addition, precision positioning of the AFM probe in the vertical direction is even more challenging (than the lateral scanning) because the desired trajectory (i.e., the sample topography profile) is unknown in general, and the probe positioning is also effected by and sensitive to the probe-sample interaction. Finally, in AFM multi-axis nanofabrication, additional positioning errors are induced by the large cross-axis dynamics coupling effect. The large positioning errors generated during high-speed, large-range fabrication will lead to large defects in the fabricated structures or devices. In the thesis, firstly, to compensate for the adverse effects generated during high-speed large-range AFM imaging, an integrated approach is proposed, which combines the enhanced inversion-based iterative control technique (EIIC) for lateral x-y axis scanning with a dual-stage piezoactuator for the vertical z-axis positioning. The main contribution of this integrated approach is the combination of an advanced control algorithm with an advanced hardware platform. This approach is demonstrated in experiments by imaging a large-size (50 μm) calibration sample at high speed (50 Hz scan rate). Then secondly, to achieve high-speed large-range multi-axis AFM nanofabrication, a recently developed model-less inversion-based iterative control technique (MIIC) is utilized to overcome the adverse effects involved in high-speed large-range multi-axis AFM nanofabrication. By using this advanced control technique, the adverse effects can be effectively accounted for and precision positioning control can be achieved in all x – y – z axes. This approach is illustrated experimentally by implementing it to fabricate large-size (∼50 μm) pentagram patterns via mechanical scratching on a gold-coated silicon sample surface at high speed (∼4.5 mm s–1).

Indexing (details)

Mechanical engineering
0548: Mechanical engineering
Identifier / keyword
Applied sciences; Atomic force microscope; Fast imaging; Iterative learning control; Nanofabrication
Control approach to high-speed large-range AFM imaging and nanofabrication
Yan, Yan
Number of pages
Publication year
Degree date
School code
MAI 47/05M, Masters Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Zou, Qingze
Committee member
Kelkar, Atul; Wang, Xinwei
Iowa State University
Mechanical Engineering
University location
United States -- Iowa
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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