TY - GEN
T1 - Investigation of the heterogeneous thermal conductivity in bulk CVD diamond for use in electronics thermal management
AU - Yates, Luke
AU - Cheaito, Ramez
AU - Sood, Aditya
AU - Cheng, Zhe
AU - Bougher, Thomas
AU - Asheghi, Mehdi
AU - Goodson, Kenneth
AU - Goorsky, Mark
AU - Faili, Firooz
AU - Twitchen, Dan
AU - Graham, Samuel
N1 - Publisher Copyright:
© 2017 ASME.
PY - 2017
Y1 - 2017
N2 - From a materials perspective, diamond exhibits properties that are extremely well suited for use in the thermal management of high power and high heat flux electronic devices. While bulk diamond grown via chemical vapor deposition (CVD) has been demonstrated since the 1980s, and people have measured thermal conductivities ranging from 500 - 2000 W/m-K, these measurements have typically taken place over a large domain that encompasses numerous diamond grains. However, many of these techniques do not reveal the heterogenous nature of the diamond thermal conductivity which arises due to the local grain structure and orientation. The diamond sample investigated in this study contained a high level of boron doping on the order of 1021cm-3, giving rise to a reduced thermal conductivity measured as 714 W/m-K with a laser flash method. Similar bulk CVD diamond samples that are undoped show thermal conductivity values of greater than 1500 W/m-K with the same measurement technique. Through the use of time-domain thermoreflectance (TDTR) we are able to measure the thermal conductivity of bulk CVD diamond at a spatial resolution smaller than the size of the columnar grains. This allows us to examine significant changes in thermal conductivity as a function of spatial location, which is of great significance when the thermal source from electronics is on the size scale of this variation. Using TDTR, we present an approach involving a variation in the laser spot size using multiple focusing objectives to yield the heterogeneous thermal conductivity in bulk CVD diamond. The data show variations in thermal conductivity near 40% over a diameter of 40 μm. Scanning Electron Microscopy (SEM) and electron backscatter diffraction (EBSD) data are presented which also show variation in microstructure over this length scale giving rise to the heterogeneity.
AB - From a materials perspective, diamond exhibits properties that are extremely well suited for use in the thermal management of high power and high heat flux electronic devices. While bulk diamond grown via chemical vapor deposition (CVD) has been demonstrated since the 1980s, and people have measured thermal conductivities ranging from 500 - 2000 W/m-K, these measurements have typically taken place over a large domain that encompasses numerous diamond grains. However, many of these techniques do not reveal the heterogenous nature of the diamond thermal conductivity which arises due to the local grain structure and orientation. The diamond sample investigated in this study contained a high level of boron doping on the order of 1021cm-3, giving rise to a reduced thermal conductivity measured as 714 W/m-K with a laser flash method. Similar bulk CVD diamond samples that are undoped show thermal conductivity values of greater than 1500 W/m-K with the same measurement technique. Through the use of time-domain thermoreflectance (TDTR) we are able to measure the thermal conductivity of bulk CVD diamond at a spatial resolution smaller than the size of the columnar grains. This allows us to examine significant changes in thermal conductivity as a function of spatial location, which is of great significance when the thermal source from electronics is on the size scale of this variation. Using TDTR, we present an approach involving a variation in the laser spot size using multiple focusing objectives to yield the heterogeneous thermal conductivity in bulk CVD diamond. The data show variations in thermal conductivity near 40% over a diameter of 40 μm. Scanning Electron Microscopy (SEM) and electron backscatter diffraction (EBSD) data are presented which also show variation in microstructure over this length scale giving rise to the heterogeneity.
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U2 - 10.1115/IPACK2017-74163
DO - 10.1115/IPACK2017-74163
M3 - Conference contribution
AN - SCOPUS:85041733724
T3 - ASME 2017 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2017, collocated with the ASME 2017 Conference on Information Storage and Processing Systems
BT - ASME 2017 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2017, collocated with the ASME 2017 Conference on Information Storage and Processing Systems
PB - American Society of Mechanical Engineers
T2 - ASME 2017 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2017, collocated with the ASME 2017 Conference on Information Storage and Processing Systems
Y2 - 29 August 2017 through 1 September 2017
ER -