Effect of Reverse Body Bias on Hot Carrier Induced Degradation of n-MOSFETs

Abstract

The impact of the reverse body bias (RBB) on hot carrier induced degradation of n+ polysilicon gate n-channel MOSFETs is investigated. A comparison with conventional stresses at zero body bias is given. The key role of channel initiated secondary electrons (CHISELs) under RBB stress responsible for a degradation broadly distributed along the channel is discussed. The dependence of this mechanism on channel length is highlighted and special attention is given to long channel devices suitable for analog applications. A significant threshold voltage drift is linked to a peak transconductance increase attributed to the coexistence in the channel of an undamaged region in series with a damaged one at the drain side. Peculiar impact of CHISEL damage is also visible in the degradation of drain current both in linear and saturation regions.