Leakage current variation with time in Ta2O5 MIM and MIS capacitors

Abstract

In this paper Ta2O5 current instability in MIM and MIS capacitors is studied over several sample thicknesses with a current versus time measurement and a low frequency dielectric spectroscopy. Three types of phenomena is identified: polarization current (attributed to dielectric relaxation phenomena), conduction current (attributed to a Poole-Frenkel mechanism) and resistance degradation. This last one has been attributed to ionic diffusion in dielectric and follows the space-charge-limited (SCL) theory. According to physical characterization the origin of resistance degradation has been attributed to oxygen vacancies migration