Oxide-Trapped Charges Induced by Electrostatic Discharge Impulse Stress

The characteristics of oxide-trapped charges Q_ot induced by electrostatic discharge high-field current impulse stress, i.e., transmission line pulsing (TLP), were studied. It was observed that for a 3.2-nm-thin oxide, the centroid evolution and the critical density of positive oxide-trapped charges Q_ot ⁺ to trigger oxide breakdown are about the same between dc and TLP impulse stresses. These results are consistent with the existing models of stress-induced trapping charges and hole-induced oxide breakdown. However, different behaviors of Q_ot and centroid were found for 14-nm-thick oxides subjected to different stress tests. TLP impulse stress generates far less amount of negative oxide- trapped charges Q_ot ^- than dc stress, and the positive oxide-trapped charges finally dominate over the negative oxide-trapped charges. This impulse stress imposes a high density and transient current on the oxide, which induces traps at the tunneling distance locally. The hotter injected electrons generate more efficient hole trappings to provoke breakdown with lower density of oxide-trapped charges in comparison with dc stress test.