Engineering Commons^™

Layer-By-Layer Nanoassembly Combined With Microfabrication Techniques For Microelectronics And Microelectromechanical Systems, Jingshi Shi

Doctoral Dissertations

The objective of this work is to investigate the combination of layer-by-layer self-assembly with microfabrication technology and its applications in microelectronics and MEMS.

One can assemble, on a standard silicon wafer, needed multilayers containing different nanoparticles and polymers and then apply various micromanufacturing techniques to form microdevices with nanostructured elements.

Alternate layer-by-layer self-assembly of linear polyions and colloidal silica at elevated temperatures have been firstly studied by QCM and SEM. LbL self-assembly and photolithography were combined to fabricate an indium resistor. The RTA method was employed in the fabrication. Hot-embossing technique as a reasonably fast and moderately expensive technique was …

A Comparison Of Micro-Switch Analytic, Finite Element, And Experimental Results, Ronald A. Coutu Jr., P. E. Kladitis, Lavern A. Starman, J. R. Reid

Electrical and Computer Engineering Faculty Research and Publications

Electrostatically actuated, metal contact, micro-switches depend on having adequate contact force to achieve desired, low contact resistance. In this study, higher contact forces resulted from overdriving cantilever beam style switches, after pull-in or initial contact, until the beam collapsed onto the drive or actuation electrode. The difference between initial contact and beam collapse was defined as the useful contact force range. Micro-switch pull-in voltage, collapse voltage, and contact force predictions, modeled analytically and with the CoventorWare finite element software package, were compared to experimental results. Contact resistance was modeled analytically using Maxwellian spreading resistance theory. Contact resistance and contact …

Fully Compliant Tensural Bistable Mechanisms (Ftbm) With On-Chip Thermal Actuation, Daniel L. Wilcox

Theses and Dissertations

The Fully compliant Tensural Bistable Mechanism (FTBM) class is introduced. The class consists of fully compliant linear bistable mechanisms that achieve much of their displacement and bistable behavior through tension loading of compliant segments. Multiple topologies of designs arising from the FTBM class were designed using a finite element analysis (FEA) model with optimization. In a coupled design approach, thermal actuators were optimized to the force and displacement requirements of the bistable mech-anisms, and selected FTBM devices were combined in switching systems with the result-ing Thermomechanical In-plane Microactuators (TIMs) and Amplified Thermomechanical In-plane Microactuators (ATIMs). Successful on-chip actuation was demonstrated. …

Optimization Studies Of Thermal Bimorph Cantilevers, Electrostatic Torsion Actuators And Variable Capacitors, Wuyong Peng

Dissertations

In this dissertation, theoretical analyses and optimization studies are given for three kinds of MEMS devices: thermal bimorph cantilevers, electrostatic torsion actuators, and variable capacitors. Calculation, simulation, and experimental data are used to confirm the device behavior and demonstrate the application of the design approaches.

For thermal bimorph cantilevers, an analytical model is presented which allows theoretical analysis and quantitative optimization of the performance based on material properties and device dimensions. Bimorph cantilevers are divided into two categories for deflection optimization: either the total thickness is constant, or the cantilever has one constant and one variable layer thickness. The optimum …

Modeling And Control Of Surface Micromachined Thermal Actuators, Robert K. Messenger

Theses and Dissertations

A model that accurately describes the transient and steady-state response of thermal microactuators is desirable to provide guidance for design and operation. However, modeling the full response of thermal actuators is challenging due to the temperature-dependent material properties and nonlinear deformations that must be included to obtain accurate results. To meet these challenges a three-dimensional multi-physics nonlinear finite-element model was developed using commercial code. The Thermomechanical Inplane Microactuator (TIM) was chosen as a candidate application to validate the model. TIMs were fabricated using the SUMMiT V™ process and their response was measured using a high-speed camera. The TIMs were modeled …

A Micromachined Thermo-Optical Light Modulator Based On Semiconductor-To-Metal Phase Transition, Lijun Jiang

Dissertations

In this research, a micromachined thermo-optical light modulator was realized based on the semiconductor-to-metal phase transition of vanadium dioxide (VO₂) thin film. VO₂ undergoes a reversible phase transition at approximately 68 0C, which is accompanied with drastic changes in its electrical and optical properties. The sharp electrical resistivity change can be as great as five orders. Optically, VO₂ film will switch from a transparent semiconductor phase to a reflective metal phase upon the phase transition. The light modulator in this research exploits this phase transition related optical switching by using surface micromachined low-thermal-mass pixels to achieve …

Investigation And Development Of Air Bridges, Jay Cabacungan

Journal of the Microelectronic Engineering Conference

A study was done in order to develop a fabrication process for creating air bridges at RIT’s Semiconductor and Microsystems Fabrication Laboratory (SMFL). Process development looked at three key factors (i) a robust lithography process that would produce the necessary rounded profile for fabricating air bridges (ii) sputter deposition vs. evaporation as metal deposition techniques (iii) the strength of the structures by testing the maximum distance an air bridge could span, the minimum and maximum thickness the structure could support, and the dimensions of the support posts. Several samples were fabricated testing the three different factors studied and SEM micrographs …

Design And Fabrication Of A Micro-Size Thermionic Ionization/Flame Ionization Detector For Gas Phase Chemical Analytes, Robert Manley

Journal of the Microelectronic Engineering Conference

A simple, MEMS base micro-chemical detector utilizing the principles of gas ionization, has been designed and fabricated. The device contains a polysilicon micro air-bridge heater structure with integrated polysilicon electrodes. The design of the devices allows it not only functions via thermionic emission, but also via chemi-ionization if a proper Pt catalyst is applied and it is operated in an environment containing hydrogen. When properly biased the device has been shown to heat to high temperatures where thermionic emission can begin to occur. Hydrocarbon chemicals in the gas phase have shown to ionize, via thermionic ionization and have been collected, …

Fabrication And Characterization Of A Packaged Mems Gas Flow Sensor, Vee Chee Hwang

Journal of the Microelectronic Engineering Conference

A surface micromachined MEMS gas flow sensor has been fabricated and tested. The fabrication process of the device was presented. The heater glowed red hot when a voltage of 27V was applied if the underlying LTO was completely etched away. Both the upstream and downstream resistors changed when temperature changed. A proof of concept showing that output voltage changes with gas flow was shown.

Design And Fabrication Of Electromagnetic Micro-Relays Using The Uv-Liga Technique, John Dalton Williams

LSU Doctoral Dissertations

This dissertation reports a research effort to microfabricate an electromagnetic relay for power applications using a multilayer UV-LIGA process. A mechanically wrapped coil was used and very simple design for the magnetic circuit was adopted to increase the design flexibility and performances. The broad material selection and the capability of making high aspect ratio microstructures of the UV-LIGA make the technology best suited for fabricating microelectromechanical power relays. Fabrication of the device required significant advances in the optical lithography of SU-8 negative photoresist. Research proved that aspect-ratios up to 40:1 in isolated open field structures of thickness between 1 and …