Electron Capture, Hydrogen Release, and Enhanced Gain Degradation in Linear Bipolar Devices

We present evidence that enhanced low-dose-rate sensitivity (ELDRS) in lateral and substrate pnp bipolar devices can occur because of the much lower probability for electron capture by protons in SiO2, as compared to mobile or trapped holes. New experimental results and a critical evaluation of previous work demonstrate that, at high dose rates and/or in oxides with low concentrations of hydrogen, electrons can more easily neutralize slowly diffusing or metastably trapped holes via annihilation (recombination) or compensation (offsetting trapping) before the holes can release H+. In contrast, at low dose rates and/or in oxides with higher concentrations of hydrogen, which can react with and modify the structure of O-vacancy-related defects, it is more likely that holes can release H+ during transport. This is because the cross section for electron capture by H+ is several orders of magnitude smaller than the electron capture cross section for a slowly moving or metastably trapped hole. This enhanced proton release at low dose rates or in oxides with high hydrogen concentrations can lead to increased interface trap formation, which is the most common source of enhanced gain degradation in lateral and substrate pnp bipolar transistors.