Publication Date


Document Type


First Advisor

Abdel-Motaleb, Ibrahim Mohamed, 1954-

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Electrical Engineering


Engineering; Engineering; Cooling systems


This thesis focused on the design and fabrication of a thermal test chip for a new liquid cooling system. This cooling system consists of heaters, sensors, and liquid cooling block. This system is developed to address the thermal issues associated with next generation integrated circuits, especially for 3D ICs. This work covers the design, fabrication and testing of the thermal test chip, while the cooling system will be delivered to UTC aerospace systems to test the cooling efficiency of the whole system.;The thermal test chip consists of tungsten (W) resistive heaters and platinum (Pt) temperature sensors, with copper as metal routing to the aluminum wire bonding pads. It has 36 hot spot heaters of 10 W and 20 W with sizes of 2 mm x 1 mm and 2 mm x 2 mm, respectively. Resistive heaters are designed to dissipate 500W/cm2 heat flux density. The chip has 72 temperature sensors, which are placed below and next to each heater. Temperature sensors are used to measure the temperature variations of heaters with and without liquid flow in cooling system.;The cooling block was made by silicon substrate using MEMS technology. It has six channels, which are exactly on top of heaters. Channels are formed by oxide bonding of two silicon wafers in which trenches of depth 70 microm are etched by deep Reactive Ion Etching(RIE) followed by 1 microm Ultra Nano Crystalline Diamond (UNCD) thin film and 1 microm oxide deposition.;Cooling block was attached to a thermal test chip using wafer-to- wafer oxide bonding. The surface morphology of the Platinum, Tungsten and channels of cooling block was studied using scanning Electron microscope. The thickness and sheet resistance of the films were measured using profilometer and four-point probe techniques respectively. Wafer-to-wafer oxide bonding strength was measured using scotch tape, blue tape test and acoustic imaging.;The heaters and sensors characteristics have been tested and found to perform according to the design specifications. The cooling system wafers are then diced and delivered to UTC aerospace systems in order to further study the efficiency of liquid cooling system. This part of the work is not within the scope of the thesis.


Advisors: Ibrahim M. Abdel-Motaleb.


100 pages




Northern Illinois University

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