SENSITIVE DIFFERENTIAL METHOD FOR THE EXTRACTION OF THE MOBILITY VARIATION IN UNIFORMLY DEGRADED MOS-TRANSISTORS

A new method for the exploitation of the characteristics of uniformly degraded MOS transistors is proposed. The method, which is based on a first order differential analysis of the shift observed in the I(d)(V(g)) transfer characteristics after stress, enables an accurate determination both of the threshold voltage shift and of the mobility variation to be accurately obtained as a function of stress (e.g. injection dose). The method has been tested on Fowler-Nordheim stressed MOSFETs and this enabled us to demonstrate that the mobility is not a monotonous function of the interface charge created after stress, and, therefore, that no unique value for the Coulomb scattering coefficient can be extracted.