Characterization of Ion Implanted Silicon Annealed with a Graphite Radiation Source
A Varian IA-200 isothermal annealer has been used to anneal ion implantation damage and electrically activate dopants in As and B implanted silicon with minimal redistribution of the impurity. The anneal occurs in vacuum using infrared radiation from a resistively heated sheet of graphite. Good quality anneals of /sup 11/B implanted samples have been obtained with minimal boron diffusion. Arsenic implanted wafers have also be annealed with excellent results except for a substantial loss of As which occurs unless the wafer has an SiO/sub 2/ cap. The anneal quality of (100) wafers was independent of dose, however, the anneal quality of the (111) wafers improved with increasing As dose.
Activation and diffusion during rapid thermal annealing of arsenic and boron implanted silicon
The redistribution of arsenic and boron implanted respectively in single crystal and in preamorphized silicon wafers is investigated after rapid thermal annealing (RTA) at temperatures ranging from 1000 up to 1150°C. SIMS dopant profiles are compared to calculated distributions for which the diffusion equation is solved with a diffusivity depending on temperature, on impurity concentration and, eventually, on time. For both ions, an additional diffusion has to be considered. This excess diffusivity is shown to be dependent on RTA duration. Using channeling-backscattering measurements, this behaviour is clearly related to the coarsening or to the annealing of residual extended defects. Thus, the enhanced diffusion is explained by an excess point defects surviving SPE regrowth, which can be trapped or released on dislocation arrays. The electrical characteristics of junctions prepared by implantation and RTA are presented.
Self-assembly of pyridinium-tailored anthracene amphiphiles into supramolecular hydrogels.
The mixing of a polyacid cross-linker with a pyridinium-functionalized anthracene amphiphile afforded a supramolecular hydrogel through a self-assembly process that was primarily driven by π-stacking and electrostatic interactions.