SEQUENTIAL PHASE-FORMATION BY ION-INDUCED EPITAXY IN FE-IMPLANTED SI(001) - STUDY OF THEIR PROPERTIES AND THERMAL-BEHAVIOR

The epitaxial growth of FeSi2 silicides was studied by using ion-beam epitaxial crystallization (IBIEC) of Fe-implanted Si(001) samples. By employing Rutherford backscattering/channeling spectrometry and transm ission electron microscopy it was possible to determine that the IBIEC process produces a gamma-, alpha-, and beta-FeSi2 phase sequence, wit h increasing Fe concentration along the implantation profile. The crit ical concentrations for gamma --> alpha and alpha --> beta phase trans itions are 11 and 21 at. %, respectively. A study of the thermal behav ior of these phases shows that the gamma- and alpha-FeSi2 are metastab le with respect to the beta-FeSi2 phase. The gamma to beta-FeSi2 trans ition starts at 700 degrees C via an Ostwald ripening process. In addi tion a 800 degrees C, 1 h anneal of high Fe concentration samples prod uces a complete alpha and gamma to PFeSi2 transformation. Finally, it is demonstrated that a regular or a rapid thermal annealing on Fe-impl anted Si samples induces only the formation of a beta-FeSi2 phase. (C) 1996 American Institute of Physics.