Development of silicon chemical wet etching toward the realization of an integrated thermal-electronic package

This work presents the investigation of a variety of cooling schemes which contribute toward an all-silicon MCM (Multi Chip Module) with integrated thermal management system. These cooling devices were developed using MEMS (Micro Electro Mechanical Systems) technology, meaning they can be batch fabricated and be easily integrated into the larger MCM system. Wet chemical etching of silicon was the main micromachining technique to create the various parts, thereby making significant contributions by optimizing known, as well as developing new processing steps.; Arrays of microchannels of extraordinary depth (mm range) and a high aspect ratio (up to 20) were designed and fabricated. For these ultra deep channels, anisotropic etching of (110) silicon was investigated. It was shown that oxygen precipitates in Czochralski crystals destroy the known anisotropic etching behavior, and that a 1300°C treatment restores good etching characteristics. The deep microchannels were then built into a liquid cooling test section which included a heater, temperature sensors and plumbing connections. They were shown to have high cooling capacity (several 100s of W/cm2) at a lower pressure drop and pumping power than previously reported.; A micromachined porous wick for application in a Loop Heat Pipe was developed using Macro Porous Silicon etching. This fabrication step was established first by building the opto-electrochemical etch rig and carefully characterizing the system with respect to the relevant parameters. Samples with a pore diameter ranging from 1 to 5$m$m were fabricated and tested for permeability and capillary pressure. A concept for integrating the porous silicon wick into an integrated evaporator was developed.; In collaboration with Sunpower Inc., work was performed for an active refrigerator, based on a Free Piston Stirling machine. For this micro cooler, anisotropic (110) silicon and isotropic etching was utilized to create several micro heat exchangers of different geometry. The fabrication of solid-state heaters and temperature sensors was achieved, but the integration with critical wet etching steps proved difficult.; This research contributes to the modular MCM system. A cooling scheme can ultimately selected with respect to the heat load and other constrains.