Ion implantation in epitaxial GexSi1-x on Si(100)

Citation

Lie, Yu-Chun Donald (1996) Ion implantation in epitaxial GexSi1-x on Si(100). Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/6GA1-F433. https://resolver.caltech.edu/CaltechETD:etd-12192007-083658

Abstract

The question of whether one can effectively dope or process epitaxial Si(100)/GeSi heterostructures by ion implantation is experimentally investigated. Results that cover several different ion species (Si, P, and As), doses (1.0x10[superscript 13]/cm[superscript 2] to 1.5x10[superscript 15]/cm [superscript 2]), implantation temperatures (RT to 150°C), as well as annealing techniques (steady-state and rapid thermal annealing) are included in this thesis. Implantation-induced damage and strain and their annealing behavior for both strained and relaxed GeSi are measured and compared with those in Si and Ge. The damage and strain generated in pseudomorphic GeSi by room-temperature implantation are considerably higher than the values interpolated from those of Si and Ge. Implantation at slightly elevated substrate temperatures (e.g., 100°C) can very effectively suppress the implantation-induced damage and strain in GeSi. The fractions of electrically active dopants in both Si and GeSi are measured and compared for several doses and under various annealing conditions. Solid-phase epitaxial regrowth of GeSi amorphized by implantation has also been studied and compared with regrowth in Si and Ge. For the case of metastable epi-GeSi amorphized by implantation, the pseudomorphic strain in the regrown GeSi is always lost and the layer contains a high density of defects, which is very different from the clean regrowth of Si(100). Solid-phase epitaxy, however, facilitates the activation of dopants in both GeSi and Si, irrespective of the annealing techniques used. For metastable GeSi films that are not amorphized by implantation, rapid thermal annealing is shown to outperform steady-state annealing for the preservation of pseudomorphic strain and the activation of dopants. In general, defects generated by ion implantation can enhance the strain relaxation process of strained GeSi during post-implantation annealing. The processing window that is optimized for ion-implanted Si therefore has to be modified considerably for ion-implanted GeSi.

Thesis Files