Damage in hydrogen plasma implanted silicon

Abstract

The damage and defects created in silicon by hydrogen plasma immersion ion implantation (PIII) are not the same as those generated by conventional beamline ion implantation due to the difference in the ion energy distribution and lack of mass selection in PIII. Defect generation must be well controlled because damage in the implanted and surface zones can easily translate into defects in the silicon-on-insulator structures synthesized by the PIII/wafer bonding/ion-cut process. The defect formation and its change with annealing temperature were investigated experimentally employing channeling Rutherford backscattering spectrometry, secondary ion mass spectrometry, and atomic-force microscopy. We also calculated the damage energy density of the three dominant hydrogen species in the plasma (H+, H2+, and H3+) as well as displacement of silicon atoms in the silicon wafer. H2+ creates the most damage because its damage energy density is very close to the silicon threshold energy. The effects of atmospheric gaseous impurities unavoidably coimplanted from the overlying plasma are also modeled. Even though their concentration is usually small in the plasma, our results indicate that these gaseous impurities lead to significant silicon atom displacement and severe damage in the implanted materials.