Charge trapping in thin gate oxides of NMOSFETs at 77K during uniform Fowler-Nordheim electron injection

Abstract

In this work, charge trapping in thin gate oxides of NMOSFETs at 77K during uniform F–N electron injection is investigated and compared with the situation at 295K. Due to the presence of a large number of neutral deep-level electron traps in gate oxide edges, produced during drain/source formation, significant electron trapping at 77K is detected in this region. In the gate oxide above the bulk channel on the other hand, net positive charges are trapped at 77K in contrast to the net negative charges at 295K. It is found that the enhanced electron trapping (or the more trappy property of gate edges) cannot only reduce device drive current but also significantly degrade device turn-o characteristics.