Formation of surface inversion layer in F +-implanted n-type silicon

Abstract

Influences of fluorine ion implantation on the electrical properties of n-type silicon have been investigated by electron beam induced current (EBIC), Hall and metal-oxide-semiconductor (MOS) high frequency capacitance-voltage (HFCV) measurements. A grating mask was used to delineate the implantation region so that the F +-implanted and unirradiated areas were located in the same A1/n-type Si Schottky diode region. EBIC images, obtained with different electron beam energies, normal and parallel to the diode surface, and EBIC collection efficiencies in the implanted and unirradiated areas were recorded. Fitting data of energy dependent EBIC collection efficiency into the theoretical EBIC model of Schottky diode, the thickness of the metal layer, depletion layer width, minority carrier diffusion length in the substrate and EBIC collection efficiency in the deletion region were determined. The minority carrier recombination in the fluorine implanted area was found to be higher than that of the blank Si area under Schottky contact. Outside the Schottky contact, an inversion layer was observed to form at the surface of the implanted area. The structural perfection of the F + implanted area was investigated by cross-sectional transmission electron microscopy (XTEM). The p-type characterization in the surface layer of the F + implanted area was also confirmed by the Hall and HFCV measurements.