• Chen, Michelle E.
• Vaziri, Sam
• Kumar, Suhas
• Bao, Xinyu
• Asheghi, Mehdi
• Hood, Ryan
• Ueda, Scott T.
• Kummel, Andrew C.
• Talin, A. Alec
• Park, Woosung
• Perez, Christopher
• Yi, Su-In I.
• Goodson, Kenneth E.
• Mcleod, Aaron J.

Abstract

Aluminum nitride (AlN) is one of the few electrically insulating materials with excellent thermal conductivity, but high-quality films typically require exceedingly hot deposition temperatures (>1000 °C). For thermal management applications in dense or high-power integrated circuits, it is important to deposit heat spreaders at low temperatures (<500 °C), without affecting the underlying electronics. Here we demonstrate 100 nm to 1.7 μm thick AlN films achieved by low-temperature (<100 °C) sputtering, correlating their thermal properties with their grain size and interfacial quality, which we analyze by X-ray diffraction, transmission X-ray microscopy, as well as Raman and Auger spectroscopy. Controlling the deposition conditions through the partial pressure of reactive N2, we achieve an ∼3× variation in thermal conductivity (∼36-104 W m-1 K-1) of ∼600 nm films, with the upper range representing one of the highest values for such film thicknesses at room temperature, especially at deposition temperatures below 100 °C. Defect densities are also estimated from the thermal conductivity measurements, providing insight into the thermal engineering of AlN that can be optimized for application-specific heat spreading or thermal confinement.

Topics

• Deposition
• impedance spectroscopy
• grain
• grain size
• x-ray diffraction
• thin film
• aluminium
• reactive
• nitride
• defect
• interfacial
• thermal conductivity
• microscopy
• specific heat