Drain structure optimization for highly reliable deep submicron nMOSFETs with 3.3 V high performance operation

A guideline for optimization of the n/sup -/ fully gate overlapped structure (FOLD) has been established. Its reliability and performance were investigated in comparison with optimized LDD (lightly doped drain) structure (op.LDD). It is found that the superiority in reliability for the two structures is reversed below 3.5 V, and the optimized FOLD structure (op.FOLD) has higher reliability than the op.LDD structure. This is due to a discrepancy between peak electric field and current flow caused by high controllability of the gate electrode of the FOLD structure at the n/sup -/ extension region. The op.FOLD structure achieves high performance on the trend at 3.3 V, in spite of nonscaled gate oxide thickness (11 nm), which results from TDDB limitation for 3.3 V operation.<
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