Non-uniform conduction induced reverse channel length dependence of ESD reliability for silicided NMOS transistors

Contrary to general understanding, ESD performance of NMOS devices can degrade for shorter channel length transistors in advanced silicided CMOS technologies. In this work, using test structures in a 0.13 /spl mu/m CMOS process, detailed characterization has been carried out for the first time to comprehend and model the physical mechanism causing this degradation. It is shown that the reverse channel length dependence of ESD performance is mainly due to severe non-uniformity in lateral bipolar conduction, which reduces the effective device width. Furthermore, it is demonstrated that substrate bias can be effective in alleviating this reverse channel length effect.