A comparison of shallow implantation between B, BF/sub 2/ and B/sub 10/H/sub 14/ by molecular dynamics simulation

The creation of shallow junctions in the semiconductor industry is a crucial step for future devices. Conventional implanters have difficulties producing ion beams below 50 keV. Advanced silicon processing requires equivalent B energies below 1 keV. There are a number of potential ways of obtaining these low energy beams. The use of molecular species has been employed for several years and recently low energy implanters adopting a de-acceleration stage have become available. We look here at the potential differences that might occur by adopting the different molecular species or by using a low energy boron beam. The difference between these occurring because of the vast difference in the energy density of the impacting particle. The low energy B ion will arrive with little energy but the larger BF/sub 2/ and B/sub 10/H/sub 14/ ions arrive with as much as 10 times the energy, all of which is deposited in a similar volume of the target. This can lead to a loss of boron from the surface.