| An investigation of the defect morphology of Si-irradiated SiGe structures has been conducted to characterize subthreshold defect evolution and point defect assisted B diffusion. Molecular beam epitaxial (MBE), unstrained Si 1-xGex layers of various Ge concentrations (ranging from 0% to 50%) were grown on top of a <100> Si substrate. The wafers were subjected to a 40 keV, 1 x 1014cm-2 Si+ non-amorphizing implant. To study the defect morphology, the samples were annealed at 750°C. Plan-view transmission electron microscopy (PTEM) was used to monitor the formation and dissolution of the defects. The Si1-xGex samples with ≤ 5% Ge exhibited {311} defect formation and dissolution; however, samples with Ge fractions ≥ 25% showed only dislocation loop formation caused by a decrease in bond strength with increasing Ge content.;The relationships between Boron Interstitial Cluster (BIC) evolution and boron diffusion in Si0.77Ge0.23 have been investigated. Structures were grown by molecular beam epitaxy (MBE) with surface boron wells of various compositions extending 0.25 mum into the substrate, as well as boron marker layers positioned 0.50 mum below the surface. The surface boron well concentrations are as follows: 0, 8.0 x 1018, 1.5 x 10 19, and 3.0 x 1019 atoms/cm3. The MBE boron marker layers are approximately 10 nm wide (full width half maximum) and have a peak concentration of 3 x 1018 atoms/cm3 . Samples were ion-implanted with 60 keV Si+ at a dose of 1x1014 atoms/cm2 and subsequently annealed at 750°C for various times. The agglomeration of injected silicon interstitials and the evolution of extended defects in the near surface region were monitored with PTEM. Secondary Ion Mass Spectroscopy (SIMS) concentration profiles facilitated the characterization of boron diffusion behaviors during annealing. Dislocation loops and traps associated with boron captures interstitials and regulate the diffusion of boron.;From these experiments, basic correlations among Ge compositions and defect evolution and among point defect-boron interactions and the associated diffusion were accessed. Extraneous information pertaining to the relaxation and solid phase epitaxial regrowth (SPER) of ion-implanted, strained Si are discussed as well. |
