Abdel-Motaleb, Ibrahim M.
M.S. (Master of Science)
Department of Electrical Engineering
The thesis investigates the dynamics of liquid cooling of the Three-Dimensional Integrated Circuit (3D-IC). Using 3D ICs is one of the most viable solutions for achieving high integration density of integrated circuits, without facing the unavoidable problems arising from shrinking the device dimensions. However, 3D ICs suffer from other types of problems. One of these problems is the heat generation creating extremely hot areas called hot spots. For high hot spots, effective thermal management techniques need to be developed. Conventional thermal management of surface cooling of chips using heat sinks and fans may reduce the surface temperature, but the embedded hot spots may not be cooled to safe operating temperatures. The objective of this thesis is to investigate the impact of hot spots on 3D ICs and to assess the effectiveness of different cooling techniques in reducing the temperature of the hot spots to acceptable levels. For the thermal management experimentations, a 1000 W/cm2 hot spot was created on a 5mmx5mm silicon chip. The chip temperature was simulated without any type of cooling. Then two mechanisms of liquid cooling were employed. The first was using a cooling block on top and another one at the bottom. Then, 3 liquid coolants, water, R22, and liquid nitrogen, were used. The cooling blocks were built using, SiO2, and diamond. The second is to use the chip embedded micro-channels inside the 3D ICs, for liquid coolants to flow to cool the hot spots. The same three coolants were used with the embedded micro-channel techniques as well. The temperature change of the cooled chip and thermal stress were investigated. The results show that without cooling, the chip temperature will reach over 2000 K after 1s, leading to the evaporation of the material. Using microchannel cooling block, it has been found that diamond microchannel cooling block ensures safe operating temperature whereas SiO2 microchannel cooling block ensures safe operating temperature for Liquid Nitrogen cooling only. The stress on the IC while utilizing these microchannel cooling blocks have been observed as well. The study shows that utilizing a rapid cooling technique does not guarantee the safer operation of the IC due to the thermal stress. Rather, the focus should be keeping the temperature difference lower from the initial temperature of the IC. A higher temperature difference makes the IC, a subject to severe stress. The chip embedded channel cooling for the 3D IC has been investigated as well. Furthermore, the adaptability of the cooling blocks for the next generation integration has been discussed. The result shows that even without using the diamond cooling block safe operating temperature and reduced thermal stress can be ensured using chip embedded cooling block.
Islam, A K M Toufiqul, "investigation of The Impact of Liquid Cooling on The integrity of Three-Dimensional integrated Circuits (3D-ICs)" (2020). Graduate Research Theses & Dissertations. 7218.
Northern Illinois University
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