Quantifying the nature of hot carrier degradation in the spacer region of LDD nMOSFETs

Abstract

A detailed quantitative analysis of the hot carrier degradation in the spacer region of LDD nMOSFETs using stress conditions for maximum hole (V/sub g/ /spl sim/ V/sub t/), substrate (I/sub submax/) and electron (V/sub g/ = V/sub d/) current from microseconds is presented. Damage in the spacer region reveals a two-stage drain series resistance degradation with an early stage lasting about 100 ms. The nature of damage is investigated by alternate electron, hole injection, and charge pumping measurements. It is seen that the hot carrier damage in the spacer oxide in the early stage is dominated by interface state creation with no evidence of significant damage by trapping mechanism either by electrons or holes. These results are in contrast to degradation behavior in the channel region where damage by trapping is a well-established mechanism of degradation under electron or hole injection.