High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films

摘要

A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPEgrown Aluminum Nitride (AlN) thin films at temperatures up to 1000DGC in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000DGC. Below 1000DGC the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300DGC for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300DGC possibly due to stress in the film.