Electron paramagnetic resonance evaluation of defects at the (100)Si/Al2O3 interface

Electron paramagnetic resonance (EPR) was conducted on aluminium oxide films deposited by atomic layer deposition on (100)Si. Multiplet spectra are observed, which can be consistently decomposed assuming the presence of only Pb0 and Pb1 centres, which are well known in Si/SiO2 structures. Al2O3 films deposited on HF-treated (100)Si exhibit unpassivated Pb0 and Pb1 centres, with concentrations of (7.7±1.0)x1011 cm-2 and (8±3)x1010 cm-2 respectively. Rapid thermal annealing of the substrate in NH3 prior to film deposition reduces the unpassivated Pb0 concentration to (4.5±0.7)x1011 cm-2. Forming gas annealing at temperatures in the range 400oC to 550oC causes no further reduction in defect density; this may be related to a spread in passivation activation energy, associated with low temperature deposition.