High-energy recoil implantation of boron into silicon

One approach to fabricate shallow junctions made of B-doped Si is to deposi t B on Si, followed by knocking the B into the Si substrate with Si ions. C onventional belief is that the higher the implantation energy, the deeper t he recoil profile. While this is true for low-energy incident ions, we show here that the situation is reversed for incident Si ions of higher energy due to the fact that recoil probability at a given angle is a strong functi on of the energy of the primary projectile. Our experiments show that 500 k eV high-energy recoil implantation produces a shallower B profile than lowe r-energy implantation such as 10 and 50 keV. The secondary ion mass spectro metry analysis shows that the distribution of recoiled B atoms scattered by the energetic Si ions agrees with that calculated on the basis of interato mic potential suggested by W. D. Wilson, L. G. Haagmark, and J. P. Biersack [Phys. Rev. B 15, 2458 (1977)]. Sub-100 nm p(+)/n junctions have been real ized with a 500 keV Si ion beam. (C) 2000 American Institute of Physics. [S 0003-6951(00)04226-1].