On the interface quality of MIS structures fabricated from Atomic Layer Deposition of HfO2, Ta2O5 and Nb2O5−Ta2O5−Nb2O5 dielectric thin films

Abstract

ABSTRACTA study of metal-insulator-semiconductor (MIS) structures based on atomic layer deposited HfO2, Ta2O5 and Nb2O5−Ta2O5−Nb2O5 thin films is presented. Our attention was focussed on interface quality and defect density in the dielectric. Interface states as well as defects inside the insulator bulk were measured by using capacitance-voltage (C-V), deep level transient spectroscopy (DLTS) and conductance transient (G-t) techniques. Nb2O5−Ta2O5−Nb2O5 based capacitors exhibit the highest interface state density, whereas the minimum is obtained for HfO2. Conductance transients are not observed in Al/HfO2/SiO2/Si stacks, thus indicating that disordered induced gap states (DIGS) are not present in these structures. We also observed that post-metallization annealing in forming gas diminishes the trap interface density at the expense of increasing DIGS in the Al/HfO2/Si cases.