|
|
Advanced techniques of micromachining
Šalomoun, Vojtěch ; Prášek, Jan (referee) ; Pekárek, Jan (advisor)
Fabrication of micro-electro-mechanical systems (MEMS) requires advanced level of miniaturization, which is not achievable by technology used in microeletronics. Socalled micromachining covers many unique techniques of material processing to get microstructures with possible dimensions below 1 m. This bachelor’s thesis gives a general introduce to micromachining of MEMS. Its focus is on bulk and surface micromachining by wet and dry etching. The practical part contains design of microstructures, their manufacturing process and creation of computer models in CoventorWare suite.
|
|
|
Gas Microsensors Based on Self-Organized 3D Metal-Oxide Nanofilms
Pytlíček, Zdeněk ; Husák, Miroslav (referee) ; Kolařík, Vladimír (referee) ; Prášek, Jan (advisor)
This dissertation concerns the development, fabrication and integration in a gas sensing microdevice of a novel 3-dimensional (3D) nanostructured metal-oxide semiconducting film that effectively merges the benefits of inorganic nanomaterials with the simplicity offered by non-lithographic electrochemistry-based preparation techniques. The film is synthesized via the porous-anodic-alumina-assisted anodizing of an Al/Nb metal bilayer sputter-deposited on a SiO2/Si substrate and is basically composed of a 200 nm thick NbO2 layer holding an array of upright-standing spatially separated Nb2O5 nanocolumns, being 50 nm wide, up to 900 nm long and of 8109 cm2 population density. The nanocolumns work as semiconducting nano-channels, whose resistivity is greatly impacted by the surface and interface reactions. Either Pt or Au patterned electrodes are prepared on the top of the nanocolumn array using an innovative sensor design realized by means of microfabrication technology or via a direct original point electrodeposition technique, followed by selective dissolution of the alumina overlayer. For gas-sensing tests the film is mounted on a standard TO-8 package using the wire-bonding technique. Electrical characterization of the 3D niobium-oxide nanofilm reveals asymmetric electron transport properties due to a Schottky barrier that forms at the Au/Nb2O5 or Pt/Nb2O5 interface. Effects of the active film morphology, structure and composition on the electrical and gas-sensing performance focusing on sensitivity, selectivity, detection limits and response/recovery rates are explored in experimental detection of hydrogen gas and ammonia. The fast and intensive response to H2 confirms the potential of the 3D niobium-oxide nanofilm as highly appropriate active layer for sensing application. A computer-aided microfluidics simulation of gas diffusion in the 3D nanofilm predicts a possibility to substantially improve the gas-sensing performance through the formation of a perforated top electrode, optimizing the film morphology, altering the crystal structure and by introducing certain innovations in the electrode design. Preliminary experiments show that a 3D nanofilm synthesized from an alternative Al/W metal bilayer is another promising candidate for advanced sensor applications. The techniques and materials employed in this work are advantageous for developing technically simple, cost-effective and environmentally friendly solutions for practical micro- and nanodevices, where the well-defined nano-channels for charge carriers and surface reactions may bring unprecedented benefits.
|
|
|
Piezoelectric MEMS resonators for sensing applications
Klempa, Jaroslav ; Svatoš, Vojtěch (referee) ; Gablech, Imrich (advisor)
Basic principles and processes used during fabrication of microelectromechanical systems are presented in this work. This thesis is focused on material properties, deposition, lithographic and micromachining processes. Fundamental principles and applications of piezoelectric resonant structures are described as well. Final part of this work is devoted to simulation of resonant beams using FEM method in ANSYS® Workbench, practical fabrication and characterization of piezoelectric MEMS resonators.
|
|
| |
|
|
Use of unconventional technologies in the production of a selected component
Havlínová, Denisa ; Kalivoda, Milan (referee) ; Dvořáková, Jana (advisor)
The biggest challenge during manufacturing copper part with microslit for optical spectrometer by the means of unconventional technologies was to meet specified narrow range of tolerances and reach right angles at the microslit corners. Electrical discharge machining and laser beam machining were two practically performed methos and both successfully met these tolerances. After consultation is focused ion beam also considered as suitable method for this task, while for photochemical machining is impossible to meet those narrow tolerances. Right angles were not achieved by any of tested methods. At laser cutting edges were proven defects (burrs, molten material), while we saw no negative defects on electrical discharge workpiece surface. Even after optimalization of EDM was machining time longer and there is assumed higher other production cost (tool manufacturing for every single workpiece), but still EDM seems to be more advantageous from financial and surface quality aspect. Based on theoretical research and practical manufacturing is recommend to manufacture specified component with microslit by EDM.
|
|
| |
|
|
Use of unconventional technologies in the production of a selected component
Havlínová, Denisa ; Kalivoda, Milan (referee) ; Dvořáková, Jana (advisor)
The biggest challenge during manufacturing copper part with microslit for optical spectrometer by the means of unconventional technologies was to meet specified narrow range of tolerances and reach right angles at the microslit corners. Electrical discharge machining and laser beam machining were two practically performed methos and both successfully met these tolerances. After consultation is focused ion beam also considered as suitable method for this task, while for photochemical machining is impossible to meet those narrow tolerances. Right angles were not achieved by any of tested methods. At laser cutting edges were proven defects (burrs, molten material), while we saw no negative defects on electrical discharge workpiece surface. Even after optimalization of EDM was machining time longer and there is assumed higher other production cost (tool manufacturing for every single workpiece), but still EDM seems to be more advantageous from financial and surface quality aspect. Based on theoretical research and practical manufacturing is recommend to manufacture specified component with microslit by EDM.
|
|
| |
|
|
Piezoelectric MEMS resonators for sensing applications
Klempa, Jaroslav ; Svatoš, Vojtěch (referee) ; Gablech, Imrich (advisor)
Basic principles and processes used during fabrication of microelectromechanical systems are presented in this work. This thesis is focused on material properties, deposition, lithographic and micromachining processes. Fundamental principles and applications of piezoelectric resonant structures are described as well. Final part of this work is devoted to simulation of resonant beams using FEM method in ANSYS® Workbench, practical fabrication and characterization of piezoelectric MEMS resonators.
|
|
| |
guest ::
