Characteristics of Hole Traps in Dry and Pyrogenic Gate Oxides

Thermally-stimulated-current and high-frequency C-V measurements have been used to characterize the differences between the hole trap properties of pyrogenic and dry oxides contained in radiation-hard and radiation-soft MOS devices. It was found that the activation energy distribution for dry oxides is the same for hard and soft devices. Pyrogenic oxides exhibit very different energy distributions for hard and soft devices, and these distributions differ from that measured for dry oxides. The interpretation of these observed differences is that the local structure of the trapped hole site is different for the two types of oxides, with the hydroxyl group playing an important role in the pyrogenic case. Possible modifications to existing models for the hole trap are also described.