Anomalous drain current in n-MOSFET's and its suppression by deep ion implantation

Effects of the deep ion implantation on the characteristics of the short channel n-MOSFET have been investigated by two-dimensional numerical analysis and verified experimentally. By the analysis, it has been found that the anomalous drain current which flows in the relatively deep region between the source and the drain has been effectively suppressed by the deep ion implantation of acceptor impurities into the channel region. Structure of short channel n-MOSFET with deep ion-implanted layer has been optimized by computer simulation to suppress the anomalous drain current. Experimentally, the low and steep subthreshold current characteristics have been obtained by deep ion implantation for short channel n-MOSFETs with LEFF= 1.2µm. Furthermore, the back gate bias dependence of the threshold voltage of the implanted short channel device can be made almost likely to that of the unimplanted long channel device.