THE INFLUENCE OF SINX-H FILM PROPERTIES ON THE ELECTRICAL CHARACTERISTICS OF METAL-INSULATOR-SEMICONDUCTOR DEVICES

SiNx:H thin films were deposited by the electron cyclotron resonance p lasma method at low substrate temperature (200 degrees C) to fabricate metal-insulator-semiconductor devices. The effects of film properties on the electrical characteristics of two different devices, SiNx:H/Si and SiNx:H/InP, were analysed according to the C-V high-low frequency method. The results show that, in the devices based on Si, the presen ce of N-H bonds in the SiNx:H film increases the density of trapping c entres at the insulator/semiconductor interface. This behaviour was an alysed by the model recently proposed by Ying (1995 J. Vac. Sci. Techn ol. B 13 1613) for nitrided SiO2/Si interfaces. For the SiNx:H/InP cap acitors, the electrical characteristics of the interface were strongly dependent on the SiNx:H composition. When the nitrogen to silicon rat io of the film was N/Si = 1.49, the minimum of the interface trap dens ity was 2 x 10(12) cm(-2) eV(-1) This value was similar to the same da ta reported by other authors on devices where the InP surface was sulp hur passivated. This suggests that nitrogen atoms of the insulator pla y some passivation role at the InP surface. The plasma exposure of the semiconductor surface during the deposition of the SiNx:H film promot es the formation of phosphorus vacancies at the InP surface. Nitrogen atoms may fill these vacancies and this gives rise to an insulator/sem iconductor interface with few defects.