Silicon interstitials generation during the exposure of silicon to hydrogen plasma

Abstract

Interstitials in silicon can be produced by hydrogen ions through chemical action and physical impact. To establish the relative importance of the two processes, wafers of single crystal silicon kept at a temperature of 250 °C were exposed to a hydrogen plasma, with and without an accelerating voltage (500 V). As gettering centers interstitial-type discolation loops were made, before H exposure, by implanting 1.9 × 1015 at. cm−2 110 keV P atoms and annealing at 1000 °C for 30 s. The analysis was performed using MeV ion channeling, elastic recoil detection analysis and cross-section transmission electron microscopy. The results suggest that H is captured by the defects: in the case of unbiased plasma, H goes in the region of the extrinsic defects, while in the case of biased plasma, H is trapped near the surface where the defects are produced by the energetic H ions themselves. In both cases the data are consistent with the formation of hydrogen nanoblisters with the subsequent breaking of silicon bonds and injection of silicon interstitials. The migration of interstitials occurs at a temperature as low as 250 °C.