Nano-electro-mechanical systems fabricated by tip-based nanofabrication
This dissertation explores the use of a heated AFM tip for fabrication of NEMS devices. Two critical challenges hindering TBN from NEMS fabrication are addressed in this thesis. First, we experimentally found out that polystyrene nanopatterns deposited by a heated AFM tip can serve directly as etch mask and transfer the nanopatterns to solid-state materials such as silicon and silicon oxide through one step of etching, solving the first challenge for NEMS device fabrication using TBN; second, we developed a process that makes this TBN method seamlessly compatible with conventional nanofabrication processes. Polystyrene nanopatterns deposited can serve together with optical lithography patterned mask and transfer both micropatterns defined by optical lithography and nanopatterns defined by the heated AFM tip to silicon. After solving the two critical challenges, we demonstrated various types of silicon NEMS mechanical resonators such as single-clamped, double-clamped, wavy-shaped, spider-like and spiral-shaped using this TBN method with a heated AFM tip. Laser interferometer measurement on two NEMS resonators showed resonance frequencies of 1.2MHz and 2.2 MHz, close to the simulated resonance frequencies. Moreover, we demonstrated PDMS nanofluidic channels with arbitrary shapes using this TBN method with a heated AFM tip. Both ion conductance measurement and fluorescence measurement confirmed the functionality of the TBN-fabrication nanofluidic channels. Finally, we demonstrated a MESFET transistor using this TBN method with a heated AFM tip. MESFET devices with one, two, four and eight fins were fabricated, demonstrating the capability of this TBN method. I-V measurements proved the functionality of the transistor. This thesis work demonstrated that TBN with a heated AFM tip held great potential in nanodevice fabrication due to its simplicity, robustness, flexibility and compatibility with existing device nanofabrication process. For example, the whole TBN process takes place in ambient conditions and is very simple. And this TBN method is additive so that the heated AFM tip only deposits polymer where needed, thus only resulting in minimal contamination. Future work should improve the throughput and scalability to make this TBN method commercially available for NEMS fabrication.
Tip-based Nanofabrication, Nano-electro-mechanical systems, Heated atomic force microscopic tip, Nanofabrication
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign