Ja. Ruffner et al., Effect of substrate composition on the piezoelectric response of reactively sputtered AlN thin films, THIN SOL FI, 354(1-2), 1999, pp. 256-261
Deposition parameters were found to have a marked effect on piezoelectric r
esponse of reactive radio frequency (RF) sputtered AlN thin films. We obser
ved piezoelectric response values ranging from -3.5 to +4.2 pm/V for 1 mu m
thick AlN films deposited onto Ti//Ru electrode stacks. This substantial v
ariation in piezoelectric response occurred despite the fact that all of th
e AIN thin films exhibited the correct crystallographic orientation for pie
zoelectric activity ((0002) crystallographic planes parallel to the substra
te). An investigation of the effects of deposition parameters, in particula
r the nature of the Ru//AlN interface, was conducted. The lag time between
deposition of adjacent thin film layers appeared to have the greatest affec
t on the value of the piezoelectric response. This result suggests that a c
hemical reaction occurring on the Ru thin film surface is responsible for c
hanging an important thin film property such as dipole orientation within t
he overlying AlN thin film. (C) 1999 Elsevier Science S.A. All rights reser
ved.