Rapid Anneal of Radiation-Induced Silicon-Sapphire Interface Charge Trapping

The rapid ahneal phenomenon of the radiation induced charge trapping at the silicon sapphire interface was experimentally investigated using a junction FET structure from 10 μsec through 1 second after an ionizing radiation pulse for various fabrication parameters and bias conditions. The fabrication parameters investigated include type of starting sapphire (Czochralski, ribbon, and gradient furnace), sapphire polish, pre-epitaxial anneal environment (air and hydrogen), and epitaxial growth method (uniform and burst). The "back channel" rapid anneal effect was also characterized as a function of bias applied to the device during the radiation pulse as well as the bias applied during the anneal time. The results show that the rapid anneal time constant is essentially independent of the bias applied during the radiation pulse as well as during the anneal time, although the initial and final values of leakage current are functions of drain bias. The experimental results also show that the rapid anneal time constant is essentially independent of the type of starting sapphire, but is a function of the pre-epitaxial sapphire anneal environment and epitaxial growth method.