There are many applications that use SiO2 in microelectronics systems for electrical and thermal isolation. A recent nano-electronic development necessitated understanding of the thermal performance of Si-SiO2-Si sandwich structures so that system level performance can be achieved. Based on a literature search, there have been numerous papers on Si-SiO2 structures, but none that dealt with a complete sandwich. Therefore our research designed, built and tested these sandwich devices to understand the thermal conductivity of the bonding layer. In this paper the transverse thermal conductivity through a Si-SiO2-Si sandwich, where the two layers of Silicon are heavily doped, is measured and used to calculate the thermal conductivity through the thin oxide film. Test samples have been manufactured in a class-1000 clean room with Silicon microfabrication techniques to deposit the thin films. Control of the interfaces depends on the chermical bond due to thin film deposition, so no additional thermal interface materials were used in the actual samples. While in the literature various techniques such as thermal reflectance, 3-Omega, and micro thermocouples have been widely used to determine the thermal conductivity of thin oxide films, in this study we explored two techniques based on a transient and a steady state measurement. First, a laser flash technique was utilized to measure the thermal diffusivity to obtain the thermal conductivity. A MicroFlash meter equipped with a custom-made holder was employed. Four different thickness square samples (5×5 mm) with oxide thicknesses of 56, 210, 1011 and 2136 nm were tested. Second, the same samples were tested via steady state measurements employing micro thermocouples. Results show that thin film oxide thermal conductivity follows the bulk oxide thermal conductivity, published as 1.4 W/m-K at room temperature, but then falls as oxide thickness decreases. A further study has been performed to better understand the uncertainty in the experimental measurements. It is found that uncertainty in the oxide thermal conductivity is on average 122%, 78%, 21% and 19% (higher uncertainties for the lower oxide thicknesses) within 95% confidence level for laser flash measurements. The effect of noise parameters such as settling time, nitrogen level and sample preparation have also been studied during the laser flash measurements.
- Heat Transfer Division
Thermal Conductivity Measurements of Si-SiO2-Si Sandwich Structures for Micro/Nano Electronics
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Royce, C, Arik, M, Weaver, S, Bray, JW, Ovsyuk, V, Klimenko, A, & Yartsev, A. "Thermal Conductivity Measurements of Si-SiO2-Si Sandwich Structures for Micro/Nano Electronics." Proceedings of the ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. Heat Transfer: Volume 2. Jacksonville, Florida, USA. August 10–14, 2008. pp. 735-744. ASME. https://doi.org/10.1115/HT2008-56001
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