N(+) P ULTRA-SHALLOW JUNCTION FORMATION WITH PLASMA IMMERSION ION-IMPLANTATION/

n(+) /p ultra-shallow junctions formed by PH3 plasma immersion ion imp lantation (PIII) have been studied and diodes with good electrical cha racteristics have been obtained. The influence of annealing conditions and carrier gas on junction depth and sheet resistance have been stud ied. It is found that a higher content of H and/or He in silicon can s low down the diffusion of phosphorus and the activation ability of imp lanted dopant ions in silicon; a shallower junction can been obtained with He rather than Hz as the carrier gas; and the influence of anneal ing at 850 degrees C for 20 s on sheet resistance is opposite to that of annealing at 900 degrees C for 6 s on sheet resistance. In addition , mechanisms of unusual electrical characteristics for some diodes are discussed and analyzed in this paper. (C) 1998 Elsevier Science Ltd. All rights reserved.