Radiation-induced depassivation of latent plasma damage

Plasma treatments are widely used in microelectronic industry but they may leave some residual passivated damage in the gate oxides at the end of the processing. The plasma-induced damage can be amplified by metal interconnects (antenna) attached to the gate during the plasma treatments. Ionising radiation reactivates this latent damage, which produces enhanced oxide charge and Si/SiO₂ interface state density. Two CMOS technologies have been investigated, with 5 and 7 nm gate oxides. Threshold voltage shifts, transconductance decrease, and interface traps build-up are always larger for plasma damaged devices than for reference devices.