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 the 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 presented showing sub-100 nm shallow p+-n junction with good sheet resistance uniformity and dose control repeatability. A high dose rate of > 10(15) cm-2 per minute at low energy (<5 keV) can be readily achieved. Excellent charging test device performance as well as surface contamination control are discussed. All of these results demonstrate the attractiveness of this unique alternate doping technique.