The deposition of aluminum nitride on silicon by plasma-enhanced metal-organic chemical vapour deposition

Aluminium nitride (AlN) films were deposited by electron cyclotron resonance plasma-enhanced chemical vapour deposition using trimethylaluminum (TMA) as precurser at temperatures from 25 to 600 degrees C and at different concentrations of TMA, Adhesive layers with a thickness ranging from 100 to 200 nm and a refractive index of 1.65-2.0 are obtained. By Auger electron spectroscopy, reflectum high energy electron diffraction and ellipsometric measurements at 632 nm we found in all layers a high oxygen concentrations only slightly dependent on the deposition conditions. A quadrupole mass spectrometer was used to investigate the composition of the gas phase. The gas spectra did not indicate partial pressures of oxygen and water. Sputtering effects and plasma chemical etching of the microwave window made of quartz glass seem to be the source for the incorporated oxygen.