Kink effect for 28 nm n-channel field-effect transistors after decoupled plasma nitridation treatment with annealing temperatures

摘要

The kink effect of drain leakage based on gated diode measurement metrology for the tested nMOSFETs with 28 nm HK/MG, gate-last and PDA or DPN nitridation processes was observed at V-G around -0.6 V when the gate voltage was swept from -Vcc to 0.2 volt as V-D = 0.1 V. Nevertheless, this interesting phenomenon was not evident as the gate voltage was reversely swept from 0.2 volt to -Vcc. The chief mechanism in speculation can be illustrated by the electrons coming from drain inducing capture-and-emission behaviour by the channel interface traps near the drain junction. While V-G changes from -Vcc towards +0.2 V, interface states near valence band become lower than Fermi-level of silicon substrate. Electrons flow from drain to fill these interface states so that drive current (I-D) increases. On the contrary, as V-G changes from +0.2 V to -Vcc, the trapped electrons are recombined with holes from substrate so that I-D is not affected. This kink effect for all of tested devices is not very distinct far and near. When the Poole-Frenkel (P-F) tunnelling electrons coming from gate to drain are evident in leakage, especially at the long-channel device, this effect will be probably counteracted, exhibited at the electrical characteristics of PDA group.