Fluorine segregation and incorporation during solid-phase epitaxy of Si

We report on the F incorporation into Si during solid-phase epitaxy (SPE) at 580 degrees C and with the presence of B and/or As, clarifying the F incorporation mechanism into Si. A strong segregation of F at the moving amorphous-crystalline interface has been characterized, leading to a SPE rate retardation and to a significant loss of F atoms through the surface. In B- or As-doped samples, an enhanced, local F incorporation is observed, whereas in the case of B and As co-implantation (leading to compensating dopant effect), a much lower F incorporation is achieved at the dopant peak. The F enhanced incorporation with the presence of B or As is shown to be a kinetic effect related to the SPE rate modification by doping, whereas the hypothesis of a F-B or F-As chemical bonding is refused. These results shed new light on the application of F in the fabrication of ultrashallow junctions in future generation devices.