Influence of Sputtering Target Material on Crystallinity and Orientation of AlN Thin Films.

We have investigated the influence of the sputtering target material on the crystallinity and crystal orientation of aluminum nitride (AIN) thin films. It was found that the type of sputtering target material affects the crystallinity and orientation of AIN thin films. The crystallinity and c-axis orientation of thin films deposited with an aluminum target are higher than those of thin films prepared with a sintered AIN target. The fullwidth at half maximum of the X-ray diffraction (XRD) rocking curves of thin films deposited with aluminum and AIN targets were 3.1 and 8.5°, respectively. From the results of X-ray photoelectron spectroscopy (XPS) analysis, the thin film deposited with an aluminum target contained 2 atom% oxygen, and the thin film deposited with an AIN target contained 8 atom% oxygen. Furthermore, the AIN target contained 3.1 atom% oxygen by fusion extraction analysis. This suggests that the oxygen included in the AIN target disarranges the crystallinity and orientation of the AIN thin films.