Advanced materials integration and thermal operation of heated microcantilevers and microcantilever arrays

Thermal Probe;Advanced Materials;atomic force microscope (AFM);Microcantilever;Heated Cantilever

Kim, Hoe Joon

关键词: Thermal Probe;    Advanced Materials;    atomic force microscope (AFM);    Microcantilever;    Heated Cantilever;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/78329/KIM-DISSERTATION-2015.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This dissertation presents the development and characterization of novel heated microcantilevers and microcantilever arrays for atomic force microscope (AFM) applications. AFM microcantilevers with integrated solid-state resistive heaters enable heat flow measurements, manufacturing, and material characterization at the nanometer scale. However, current heated microcantilevers need to be improved in several areas, such as scan speed and scan area, tip stability, and thermal operation reliability for industrial applications. This dissertation focuses on tackling these issues by integrating advanced materials with heated microcantilevers and microcantilever arrays, along with detailed analysis of their thermal operation under various conditions. The microcantilevers and the microcantilever arrays demonstrate outstanding throughput and stability for applications in nanomanufacturing and nanometrology.Firstly, this work presents the design and fabrication of heated microcantilever arrays to improve throughput of heated cantilever AFM techniques. The microcantilever array consists of five identical independently-controlled heated cantilevers. The thermal crosstalk between the cantilevers is analyzed in steady and transient operating conditions when the array is either in contact with a substrate or freely suspended in air. Results show that the thermal crosstalk between neighboring cantilevers induces non-negligible increases in cantilever temperature, depending upon the operating conditions.Secondly, this work investigates the long term operation and reliability of heated microcantilevers. The electrical and thermal operation of heated microcantilevers is sensitive to the distribution of dopants within the silicon cantilever. For long term operation, or for operation at very high temperatures, the cantilever electro-thermal properties can change due to dopant diffusion from the high-doped region towards the low-doped heater. Such changes in cantilever properties are closely monitored and analyzed to understand the reliability of heated microcantilevers under harsh operating conditions.Thirdly, this work presents the integration of ultrananocrystalline diamond (UNCD) and multilayer graphene onto microcantilevers using conventional microfabrication processes. First, an ultrasharp and wear-resistant UNCD tip is integrated onto the heated AFM microcantilevers and microcantilever arrays. The UNCD tips are batch-fabricated and have apex radii of about 10 nm and heights up to 7 µm. The UNCD tips, used for thermal topography imaging and tip-based nanomanufacturing, demonstrate much improved tip stability compared to silicon tips. In addition, this work reports the direct integration of chemical vapor deposition (CVD) grown graphene with microcantilevers. A method of transfer-free graphene synthesis is developed, optimized, and applied to the batch fabrication of graphene-coated microcantilevers.Finally, a heated microcantilever is used to measure the temperature-dependent viscosity of water and ethylene glycol solutions. An applied AC voltage in the presence of an external magnetic field simultaneously heats and actuates the microcantilever. By monitoring the changes of resonant frequencies of the heated microcantilever inside liquid at different heater temperatures, the temperature-dependent liquid viscosities can be measured. The measurements match well with the finite difference model that predicts the dynamic response of the cantilever in the frequency domain.