Thermal Boundary Conductance of Direct Bonded Aluminum Nitride to Silicon Interfaces
Tarmo Nieminen, Tomi Koskinen, V. V. Kornienko, Glenn Ross, Mervi Paulasto‐Kröckel
Abstract
High Resolution Image Download MS PowerPoint Slide Heat accumulation and self-heating have become key issues in microelectronics owing to the ever-decreasing size of components and the move toward three-dimensional structures. A significant challenge for solving these issues is thermally isolating materials, such as silicon dioxide (SiO 2 ), which are commonly used in microelectronics. The silicon-on-insulator (SOI) structure is a great demonstrator of the limitations of SiO 2 as the low thermal conductivity insulator prevents heat dissipation through the bottom of a device built on a SOI wafer. Replacing SiO 2 with a more thermally conductive material could yield immediate results for improved heat dissipation of SOI structures. However, the introduction of alternate materials creates unknown interfaces, which can have a large impact on the overall thermal conductivity of the structure. In this work, we studied a direct bonded AlN-to-SOI wafer (AlN-SOI) by measuring the thermal conductivity of AlN and the thermal boundary conductance (TBC) of silicon (Si)/AlN and Si/SiO 2 /aluminum–oxygen–nitrogen (AlON)/AlN interfaces, the latter of which were formed during plasma-activated bonding. The results show that the AlN-SOI possesses superior thermal properties to those of a traditional SOI wafer, with the thermal conductivity of AlN measured at roughly 40 W m –1 K –1 and the TBC of both interfaces at roughly 100 MW m –2 K –1 . These results show that AlN-SOI is a very promising structure for improving heat dissipation in future microelectronics.