*Stefan Neuhaus, Hagen Bartzsch, Steffen Cornelius, Alexander Hinz, Peter Frach, Olaf Zywitzki, Manuela Junghähnel, Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, Dresden, Germany
Aluminum nitride layers (AlN) are a common approach to overcome the tremendous lattice mismatches between gallium nitride layer and the silicon wafer substrate in the GaN on Si technology. Compared to the conventional MOCVD process, magnetron sputter deposition of the AlN film has the potential of achieving lower substrate temperature, higher deposition rates and lower costs while maintaining the required crystalline quality of the AlN. This paper discusses the epitaxial deposition of high quality undoped AlN thin-films on Si(111) wafer substrates by reactive magnetron sputtering. Especially the effects of substrate temperature during coating, pretreatment, reactive gas flow and pulse parameters were studied during process development. The films were characterized using XRD rocking curves, XRD pole figures, film stress using wafer curvature measurement, and as well SEM cross section and AFM topography. The magnetron sputtering process for the epitaxial grown AlN films was upscaled to substrate sizes of 8” Si(111) substrates aiming at homogenous film thickness and crystalline quality across the wafer. The AlN thin-films on Si(111) wafer were grown under a rate of around 75 nm/min and achieved a FWHM of 0.7° for (002) out of plane and 1° for (100) in plane rocking curves.