Removal of hydrogen and deposition of surface charge during rapid thermal annealing

The submission of a hydrogenated oxide-passivated silicon wafer to a rapid thermal anneal (RTA) leads to a complicated change in effective lifetime τeff. Within seconds, τeff decreases rapidly before increasing to near its initial level, and then decreasing more slowly. The initial decline is shown to be due to hydrogen loss from the SiO2—Si interface, as is consistent with the literature. The recovery in τeff is due to the deposition of surface charge, somehow related to the placement of the sample on an as-cut silicon baseplate within the RTA chamber; this surface charge can be removed by washing the sample in isopropanol. The mechanism behind the final decrease in lifetime is unknown.