Improvement of ultrathin gate oxide and oxynitride integrity using fluorine implantation technique

The effects of fluorine on ultrathin gate oxide and oxynitride (similar to 40 Angstrom) have been studied. The incorporation of fluorine was done by fluorine ion implantation into polycrystalline silicon (polysilicon) gate followed by a high-temperature drive-in step. It has been found that the integrity of oxide has been improved with the incorporation of fluorine as demonstrated by the reduction of stress-induced leakage current and interface trap generation, Furthermore, unlike thicker dielectrics (>100 Angstrom) for which the charge-to-breakdown (Q(BD)) values decrease with increasing fluorine concentration, Q(BD)'s remain the same as those of the control samples for the ultrathin thickness regime, The mechanism for oxide quality improvement by F will also be discussed in the letter. (C) 1997 American Institute of Physics.