CHARACTERISTICS OF A PLASMA DOPING SYSTEM FOR SEMICONDUCTOR-DEVICE FABRICATION

A plasma doping system for semiconductor ion implantation is described . The target to be implanted is placed directly in the plasma and then biased to a negative potential to accelerate the positive ions into t he target. A wafer bias of up to -5 kV with a BF3 source gas are used to implant boron ions into 150 mm diameter Si wafers. Data are present ed showing sub-100 nm shallow p+-n junction with good sheet resistance uniformity and dose control repeatability. A high dose rate of > 10(1 5) cm-2 per minute at low energy (<5 keV) can be readily achieved. Exc ellent charging test device performance as well as surface contaminati on control are discussed. All of these results demonstrate the attract iveness of this unique alternate doping technique.