Characterization of Corner-Induced Leakage Current of a Shallow Silicided n + /p Junction for Quarter-Micron MOSFETs

In addition to the conventional area and perimeter intensive junctions, a corner intensive junction has been added to characterize the reverse current mechanism of a silicided shallow n + /p junction for quarter-micron metal oxide silicon field effect transistors (MOSFETs). The n + /p junction is fabricated using the novel quarter micron technology. The corner intensive junction shows a much larger reverse current than the area and perimeter intensive junctions. The main causes of reverse current in these three junctions are Poole-Frenkel barrier lowering and possibly phonon-assisted tunneling. Although additional phosphorus ion implantation improves junction quality of the area and perimeter diodes, it has had little effect on the corner diode. The corner diode shows a strong electric field dependence in spite of additional phosphorus ion implantation. The main cause of corner leakage current is believed to be the increased trap density and electric field at the corner area. As the MOSFET device shrinks, the corner leakage component will be important.