DOMINANT FACTOR FOR THE CONCENTRATION OF PHOSPHORUS INTRODUCED BY VAPOR-PHASE DOPING (VPD)

The dominant factor for the surface concentration of n-type impurity, introduced by vapor phase doping technique using phosphine, was invest igated and the possibility of a high surface concentration was pursued . It was found that the surface concentration of phosphorus could be c ontrolled dominantly by the PH3 partial pressure. It was confirmed tha t the phosphorus atoms adsorb on the surface of the silicon substrate throughout the doping process. A new diffusion model via the adsorptio n layer at the surface is proposed. Electrically active phosphorus wit h a surface concentration as high as 8 x 10(19) atoms/cm(3) was succes sfully obtained.