CHARACTERIZATION OF ULTRA-SHALLOW P(-N JUNCTIONS FORMED BY PLASMA DOPING WITH BF3 AND N-2 PLASMAS())

Plasma doping (PLAD) is a promising alternative to conventional ion im plantation for the formation of ultra-shallow p(+)-n junctions. In the PLAD process, a silicon wafer is placed directly in a plasma containi ng the desired dopant ions and then pulse-biased to a negative potenti al to accelerate positive dopant ions into the silicon surface. Most o f Varian's work to date has used BF, source gas and wafer biases of -0 .5 to -5 kV to implant boron into 150 and 200 mm wafers. Data will be presented showing successful formation of ultra-shallow junctions, goo d sheet resistance uniformity and repeatability, and excellent structu ral quality of the silicon after rapid annealing. Very good device cha racteristics obtained from deep sub-half micron MOSFETs fabricated usi ng PLAD will also be shown. Finally, the combination of PLAD with an N -2 plasma followed by ultra-low energy B+ implantation to produce ultr a-shallow junctions with low sheet resistances will be discussed. (C) 1998 Elsevier Science S.A. All rights reserved.