Hydrolysis protection and sintering of aluminum nitride powders with yttria nanofilms

Abstract Aluminum nitride (AlN) is a promising material for electronic substrates and heat sinks. However, AlN powders react with water that adversely affects final part properties and necessitates processing in organic solvents, increasing the cost of AlN parts. Small quantities of yttrium oxide (Y 2 O 3 ) are commonly added to AlN particles to enable liquid phase sintering. To mitigate the reaction of AlN particles with water, particle atomic layer deposition (ALD) was used to coat AlN powders with conformal films of Y 2 O 3 prior to densification and powder processing. When AlN particles were coated with 6 nm thick films of amorphous Y 2 O 3 , the hydrolysis reaction was significantly suppressed over 48 h, demonstrating that Y 2 O 3 nanofilms on AlN powders act as a barrier coating in an aqueous solution. AlN powders with Y 2 O 3 addition by particle ALD sintered to high relative densities (≥90% theoretical) after sintering at 1800°C for 50 min.