TDDB on poly-gate single doping type capacitors

Abstract

Lifetime projections for polycrystalline silicon (poly) gate single doping type capacitors are complicated by gate poly depletion and inversion during the accelerated test. The presence of poly depletion and inversion was experimentally confirmed by CV and IV measurements. Simple high field straight line extrapolation was found to overestimate the 5-V lifetime by 1200 times in the 68-AA oxide equivalent poly/poly capacitors. The overestimate can be minimized by limiting the test voltage below the gate poly inversion voltage. A sensitivity analysis of the overestimate to gate poly doping is also presented.<>