Chemical Kinetics of Hydrogen and P_b Centers

Abstract

Electron paramagnetic resonance (EPR) measurements indicate that P_b centers, which are a dangling-bond type of defect at the (111) Si-Si0₂ interface, can be passivated with H₂ at a rate which is proportional to the H₂ concentration in the thermal oxide and the interfacial density of P_b centers. This process is characterized by an activation energy, Ef, of 1.66 ± 0.06 eV with a second-order pre-exponential factor, _k(2)_of, of 1.94 (+2./-1.) x 10⁻⁶ cm³/sec for temperatures between 230 and 260°C. The passivation process is demonstrated to be consistent with a chemical process in which H₂ molecules, during the course of their diffusional motion among the accessible interstices of the Si0₂ network and the reaction site at P_b centers, react directly with P_b centers. EPR measurements indicate that passivated P_b centers, denoted as HP_b, in effect dissociate in vacuum above 550°C.