INFLUENCE OF FLUORINE PREAMORPHIZATION ON THE DIFFUSION AND ACTIVATION OF LOW-ENERGY IMPLANTED BORON DURING RAPID THERMAL ANNEALING

The diffusion and activation of low-energy implanted B in F preamorphi zed Si during rapid thermal annealing has been studied. Compared with low-energy B or BF2 implant into crystalline Si, low-energy B ion impl antation into F preamorphized Si allows the formation of shallow junct ions with reduced junction depth and increased B activation. F preamor phization suppresses the B transient enhanced diffusion in the low B c oncentration region resulting in a steep dopant profile which is neces sary for shallow junction formation. Secondary ion mass spectroscopy a nd cross-sectional transmission electron micrograph results show F acc umulation near the surface and at end-of-range defects. The interactio n of F with defects is believed to reduce B diffusion in the low B con centration region. Low-energy B implant into F preamorphized Si follow ed by rapid thermal annealing has been demonstrated as a promising pro cess for shallow junction formation. (C) 1994 American Institute of Ph ysics.