Characterization and modeling of dynamic variability induced by BTI in nano-scaled transistors

摘要

In this paper, dynamic variability (DV) induced by BTI is deeply investigated in nano-scaled devices by means of statistical measurements and modeling. The impact of a single charge q on V-t is first investigated through 3D electrostatic simulations. In planar devices, this MC modeling allows proving that the average V-t shift induced by a single q denoted eta(t) is inversely proportional to the device area. In trigate 3D transistors, BTI trapping not only occurs at the top surface (TS) oxide but also at the device sidewalls (SW). For Pi fet Nanowire, this implies that eta(t) exhibits a complex variation with device scaling unlike in planar structures. In contrast, Finfet rather behaves as a vertical planar device for which SW plays now the role of TS. Finally the impact of device scaling on NBTI degradation is thoroughly studied in 3D technologies. Enhanced NBTI is measured on narrower devices. This phenomenon is well explained and reproduced by 3D MC simulations considering a poorer quality of the SW gate oxide with respect to its TS counterpart.