Interfacial state density and conductance-transient three-dimensional profiling of disordered-induced gap states on metal insulator semiconductor capacitors fabricated from electron-cyclotron resonance plasma-enhanced chemical vapor deposited SiOxNyHz films

Abstract

An electrical characterization of Al/SiOxNyHz/Si metal-insulator-semiconductor (MIS) structures has been carried out. SiOxNyHz films of different compositions have been obtained from these structures by varying gas flow in the electron-cyclotron resonance plasma-enhanced chemical vapor deposition (ECR-PECVD) system. The presence of nitrogen in the films increases the dielectric constant value and degrades the interface quality, as our measurements demonstrate. The effect of thermal annealing has also been determined. Capacitance-voltage (C-V) results show that unannealed samples exhibit positive flat-band voltages, whereas annealed ones exhibit negative values. On the other hand, from deep-level transient spectroscopy (DLTS) measurements we can conclude that interfacial state density diminishes when thermal treatments are applied. Moreover, conductance transient analysis provides the energetic and spatial distribution of defects in the films and demonstrates that thermal improvement affects not only the interface, but also the insulator bulk.