Implantation damage in SIMOX structures

Summary form only given. Transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) have been used to study the implantation damage created by the dopants and their diffusion during subsequent annealing. TEM observations were performed after implantation of phosphorus in SIMOX (separation by implantation of oxygen) structures as well as in bulk silicon. The observations showed that the SIMOX structures are, in general, more sensitive to implantation than bulk silicon, revealing a deeper amorphization after implantation and a rougher surface after annealing. SIMS measurements of the dopant concentration in the SIMOX structures showed an enhanced diffusivity of the impurities as well as a peak of concentration near the surface that is about 150 Å for arsenic and 250 Å for boron. The results indicate that: (1) the trapping of the impurities is due to dopant-contaminant immobile complexes rather than to segregation at the surface: and (2) the locally enhanced diffusion of the dopants, mainly arsenic, corresponds to the region amorphized by the implantation