Generation of P sub b centers by high electric fields; Thermochemical effects

The generation of P{sub b} centers by negative corona charging has been examined by electron spin resonance (ESR). Formation of P{sub b} centers has been found to saturate in about 25s. The corona-generation effect is maximized for samples oxidized in ambients containing about 0.1% H{sub 2}O, and disappears with dry or steam-growth oxides. Mild postoxidation anneals can also generate P{sub b} in these samples, and the activation energy for this thermal generation is lowest for samples showing the corona effect. Prolonged anneals have been found to passivate existing P{sub b} and, ultimately, to produce an interface that is very resistant to corona depassivation. It is proposed that the P{sub b} generation is due to weakening of the interface Si-H bond by attraction of a hole from the Si bulk in the negative field, followed by prompt abstraction and capture of a proton by a nearby H{sub 2}O molecule to yield H{sub 3}O{sup +} and P{sub b}. Capacitance-voltage curves show flatband shifts and stretchout, which indicate the generation of positive oxide charge and interface states.