Growth of AlN Thin Film on Sapphire Substrates and ZnO Templates by RF-magnetron Sputtering

AlN thin films were deposited on sapphire substrates and ZnO templates by rf-magnetron sputtering. Powder-sintered AlN target was adopted for source material. Thickness of AlN layer was linearly dependent on plasma power from 50 to 110 W, and it decreased slightly when working pressure increased from 3 to 10 mTorr due to short mean free path of source material sputtered from AlN target by Ar working gas. When N2 gas was mixed with Ar, the thickness of AlN layer decreased significantly because of low sputter yield of nitrogen. AlN layer was also deposited on ZnO template. However, it showed weak thermal stability that the interface between AlN and ZnO was deteriorated by rapid thermal annealing treatment above 700˚C. In addition, ZnO layer was largely attacked by MOCVD ambient gas of hydrogen and ammonia around 700˚C through inferior AlN layer deposited by sputtering. And AlN layers were fully peeled off above 900˚C.