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| Fig. 1: Integrated Circuit Chip (Source: Wikimedia Commons) |
Recently, driven by advancements in semiconductor manufacturing technology (see Fig. 1) such as extreme ultraviolet lithography (EUV), the integration density of semiconductors has steadily increased. [1] Specifically, the number of transistors within an integrated circuit (IC) chip, which was around 100 million in 2003, has recently grown to over 100 billion. [2] The miniaturization of semiconductors has positively contributed to the increased integration density of IC chips, but it has intensified heat generation within the IC chips at the same time. [3] This internal heat in IC chips leads to threshold-voltage roll-off in the transistors and electromigration in the metal wiring, ultimately resulting in reduced IC chip lifespan. [4] For example, if the temperature increases by 10%, the mean time to failure (MTTF) of the semiconductor could decrease by 9.5%. [4]
Previous research showed that the approximate breakdown of total power used by digital electronics in the U.S. [5] According to this research, in 2007, in the united states, data centers consumed 7 GW, work PCs consumed 6.5 GW, work displays consumed 3.2 GW, and home PCs consumed 2.6 GW. [5]
Power consumption of semiconductor could vary according to IC chips. For example, Intel Atom N270 was documented to use 2.5 W power. [5] On the other hand, Intel 945GSE chipset was documented to use 11.8 W power. [5] Amount of power consumption within the same IC chip can vary depending on operating conditions. [5]
In semiconductor fabrication, materials such as silicon (Si), germanium (Ge), and silicon dioxide (SiO2) have been used. [5, 6] Previously, it was reported that Si at bulk scale has thermal conductivity of 148 W×m-1×K-1, and thin Si film (10 nm) has thermal conductivity of 13 W×m-1×K-1. [6] According to the thickness of material, these thermal conductivity could be changed due to phonon boundary scattering. [6] Besides, the SiO2 was reported with the thermal conductivity of 1.4 W×m-1×K-1. [6] This thermal conductivity could affect the overall heat dissipation in semiconductor. [6]
In modern semiconductors, semiconductor produces heat (measured in joules per switching event) at energy levels far above Landauer limit. [7] Landauer limit could be explained by the theoretical minimum energy per switch and represents the least energy that must be dissipated during a binary switch. [7] Previous research described that modern semiconductor transistors might consume over 10,000 times higher energy, compared to this limit per event. [5-7]
To simplify the calculation, I will assume that all transistors turn on simultaneously at a specific frequency. In reality, transistors may not turn on simultaneously, and the operating frequency may vary depending on the application. [5, 6] For simple calculation, by assuming that all transistors turn on simultaneously at a specific frequency and operate at 10,000 times the Landauer limit, the energy consumption of the IC chip could be calculated as follows.
For example, let's consider an IC chip with 1010 transistors operating at 1 GHz (109 Hz). If all transistors turn on at the same time, the power consumption could be calculated as follows:
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(1) |
As an another example, let's consider an IC chip containing 1010 transistors running at 5 GHz (5 × 109 Hz). Assuming all transistors simultaneously turn on, the power consumption can be calculated as follows:
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(2) |
To mitigate this phenomenon, recent research has designed semiconductor devices utilizing materials with high thermal conductivity and high thermal boundary conductivity. [8] By utilizing these materials, researchers aim to improve heat dissipation in semiconductors and consequently lower the energy required to cool semiconductor chips in computers. [9]
As an another example, previous research showed that the utilizing aluminum nitride (AlN) with thermal conductivity of 250 W×m-1×K-1 could decrease normalized temperature-rise in IC chip from 83 mm2K/W to 69 mm2K/W. [10] The authors mentioned that this could be achieved because AlN has high thermal conductivity of 250 W×m-1×K-1, compared to thermal conductivity of SiO2 1.5 W×m-1×K-1. [10]
The miniaturization of semiconductor devices has improved integration density but also concurrently brought heat generation issue in semiconductor. To mitigate these issues, researchers utilized materials with high thermal conductivity and thermal boundary conductivity to improve heat dissipation in semiconductor. These materials aim to improve heat dissipation, ultimately lowering cooling energy demands in computers.
© Y. Song. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] K. Choi et al., "Enhanced Reliability of 7-nm Process Technology Featuring EUV," IEEE 8897599, IEEE Trans. Electron Dev. 66, 5399, (2019).
[2] M. S. Lundstrom and M. A. Alam, "Moore's Law: The Journey Ahead," Science 378, 722 (2022).
[3] I. Myeong et al., "Self-Heating and Electrothermal Properties of Advanced Sub-5-nm Node Nanoplate FET," IEEE 9103552, IEEE Electron Device Lett. 41, 977 (2020).
[4] B. K. Liew, N. W. Cheung, and C. Hu, "Effects of Self-Heating on Integrated Circuit Metallization Lifetimes," IEEE 74289, International Technical Digest on Electron Devices Meeting, 3 Dec 89.
[5] E. Pop, "Energy Dissipation and Transport in Nanoscale Devices," Nano Research 3, 147 (2010).
[6] E. Pop, S. Sinha, and K. E. Goodson, "Heat Generation and Transport in Nanometer-Scale Transistors," Proc. IEEE 94, 1587 (2006).
[7] R. Landauer, "Irreversibility and Heat Generation in the Computing Process," IEEE 9103552, IBM J. Res. Devel. 5, 183 (1961).
[8] P.-Y. Liao et al., "Alleviation of Self-Heating Effect in Top-Gated Ultrathin In2O3 FETs Using a Thermal Adhesion Layer," IEEE 9955411, IEEE Trans Electron Dev. 70, 113 (2023).
[9] M. J. Kang et al., "Internal Thermoelectric Cooling in Nanosheet Gate-All-Around FETs Using Schottky Drain Contacts," IEEE 9462907, IEEE Trans. Electron Dev. 68, 4156 (2021).
[10] Ç. Köroǧlu and E. Pop, "High Thermal Conductivity Insulators for Thermal Management in 3D Integrated Circuits," IEEE Electron Device Lett. 44, 496 (2023).
