Improved immunity to plasma damage in ultrathin nitrided oxides

Plasma-induced damage in various 3-nm thick gate oxides (i.e., pure O-2 and N2O-nitrided oxides) was investigated by subjecting both nMOS and pMOS ant enna devices to a photoresist ashing step after metal pad definition, Gate leakage current measurements indicated that large leakage current occurs at the wafer center as well as at the wafer edge for pMOS devices, while it o ccurs only at the wafer center for nMOS devices, These interesting observat ions could be explained by the polarity dependence of ultrathin oxides in c harge-to-breakdown measurements. Additionally, ultrathin N2O-nitrided oxide s show superior immunity to charging damage, especially for pMOS devices.