Study of TiOxNy MOS Capacitors

Abstract

A set of MOS capacitors with TiOxNy films deposited by reactive r.f. magnetron sputtering varying the nitrogen partial pressure in an Ar/N2 gaseous mixture, as gate dielectric layer, was fabricated and characterized. These films were annealed at 550 and 1000oC in N2 environment. The TiOxNy films were characterized by Raman, Rutherford Backscattering (RBS), and High Resolution Transmission Electron Microscopy (HRTEM). Capacitance-voltage (1MHz) and current-voltage measurements were used to obtain the effective dielectric constant, the effective oxide thickness (EOT), the leakage current density, and the interface quality. MOS capacitors results show that the TiOxNy films present a dielectric constant varying from 15 to 35, good interface quality with silicon and leakage current density varying from approximately 1 to 10 mA/cm2 for VG = -1V and for EOT of approximately 2 nm. The leakage current density is reduced in 2 orders of magnitude with an increase in nitrogen concentration.