| Popis: |
The present work deals with the development of a very novel and prototypical Micro Loop Heat Pipe (LHP) using the Coherent Porous Silicon (CPS) technology developed at the University of Cincinnati for different thermal and space applications. The main emphasis of this thesis is the development of an automated process for batch fabrication of Coherent Porous Silicon (CPS) wicks and development/characterization of novel anodic bonding techniques. The micro cooling of Integrated Circuits (IC), solar cells are some of the applications of LHP. In this work, it was determined that individual wafers should be given individual attention in determining the critical parameters for etching. A generalized approach, while ignoring the wafer level details has many limitations. A method to determine critical current density was established by introducing a current-voltage sweeps, before etching. Different types of etching methods are studied viz., potentiostat etching mode, galvanostat etching mode, current compensation mode and light compensation mode. In this present study, it was also determined to have a higher etch rate and uniform concentration of the etchant in the etch rig. A new flow system was developed, which would increase the temperature of the etchant, for faster etch rates. This new system would supply fresh etchant to the etching rig. Etchant level controlling logic was also implemented. One of the challenging micro processing technique needed to make a LHP package is bonding wafers producing hermetic seals. The mechanisms of formation of anodic bonds between glasses and metals are examined. Prior research works suggests electrochemical, electrostatic and thermal mechanisms for bond formation, but the dominant mechanism has not been clearly defined. The process is found to be an electrochemical analog to thermal glass-to-metal seals, where the metal surface is oxidized into the glass due to the development of large electric fields across the anodic depletion layer. A novel anodic bonding technique was developed to facilitate bonding very thick silicon dioxides to glass and silicon. Characterization studies are performed and optimization of this process was suggested. Parametric approach was used to quantify the influence of each parameter on the bond strength. |
