Effect of Nitridation on Morphology, Structural Properties and Stress of AlN Films

We investigate effects of nitridation on AlN morphology, structural properties and stress. It is found that 3min nitridation can prominently improve AlN crystal structure, and slightly smooth the surface morphology. However, 10min nitridation degrades out-of-plane crystal structure and surface morphology instead. Additionally, 3-min nitridation introduces more tensile stress (1.5GPa) in AlN films, which can be attributed to the weaker islands 2D coalescent. Nitridation for 10min can introduce more defects, or even forms polycrystallinity interlayer, which relaxes the stress. Thus, the stress in AlN with 10min nitridation decreases to -0.2GPa compressive stress.