Defect Interactions of ${\hbox{H}}_{2}$ in ${\hbox{SiO}}_{2}$: Implications for ELDRS and Latent Interface Trap Buildup

The energetics of the interactions between molecular hydrogen and common defects in SiO₂ that are typically associated with O deficiency have been obtained using atomic-scale quantum mechanical calculations. H₂ does not easily crack at neutral vacancies, but it will crack efficiently at O vacancy sites that have captured a hole and relaxed into the puckered configuration of an E_γ^' defect, releasing a proton into the oxide. Isolated Si dangling bonds also can play a role in cracking H₂, depending on their concentration in the oxides. These results provide significant insight into the underlying causes of latent interface trap buildup in MOS devices and enhanced low-dose-rate sensitivity in linear bipolar devices.

I. Introduction

Hydrogen is ubiquitous in semiconductor device manufacturing. It is introduced intentionally to passivate defects, e.g., dangling bonds at or near the interface, but is also bonded at sites throughout typical MOS and bipolar device structures. At elevated temperatures, under bias, and/or during irradiation, hydrogen can be released and act as an agent of degradation, depassivating existing defects or generating new ones. The atomic-scale mechanisms of these processes have been studied extensively [1]–[5]. During irradiation, for example, protons are released in the oxide, migrate to the interface, and react there to depassivate defects and cause interface trap buildup [2], [6]–[8].