Measurements and Applications of High-energy Boron Implants In Silicon

Boron ions were implanted into high resistivity Si wafers at energies in the 15-50 MeV range and doses in the 10(11)-10(16) cm-2 range. The distribution of the implanted ions was analyzed by spreading resistance profilometry and for the high fluences by secondary ion mass spectrometry. Some samples were implanted with the beam normal to the wafer surface to study the channeling effect in a pure electronic stopping power regime of slowing down. The experimental measurements of the projected ranges and of the stragglings are compared with calculations based on the usual LSS and Bethe-Bloch formulas for the stopping power. This classic approach justifies quantitatively the distribution for the samples implanted in a random direction. The I-V characteristic of a diode performed by multiple energy boron implants of 15, 22 and 50 MeV is presented. The obtained breakdown voltage, 5 x 10(3) V, represents a possible application of the high energy implants.