EFFECT OF BACKGROUND DOPING ON THE SUPERFICIAL SILICON LAYER OF SOI WAFERS SYNTHESIZED BY OXYGEN IMPLANTATION.

The effect of background dopant and dopant level on the structure of oxygen implanted silicon-on-insulator (SOI) material has been examined by transmission electron microscopy. All wafers, when oxygen implanted, either unheated or with a 400 degree C substrate temperature, developed a heavily damaged superficial Si layer above a buried oxide layer. After annealing, all wafers had a superficial layer with a precipitate-free region at the surface which was located above a precipitate-rich region. During annealing the buried oxide layer grew toward the surface in lightly B or P doped wafers, but did not grow at all in heavily doped As or Sb wafers. In the As and the Sb doped wafers implanted unheated, a thin, sharply bounded amorphous layer developed in the superficial layer above the buried oxide. Upon annealing, the amorphous layer transformed into two thin bands, above the buried oxide, of polycrystalline Si with precipitates and precipitate-free single crystal Si. Overall, the major effects of heavy background doping were to inhibit growth of the buried oxide layer during annealing and to produce unique structure at the interface region of the superficial Si and buried oxide layers.