Boron implants in silicon at tilt angles of O degrees and 7 degrees

Abstract

Implants of 80 keV B+ ions into a <100> Si n-type 5 in wafer were performed at tilt angles of 0 degrees and 7 degrees with a high-current implanter. The influence of the tilt, twist and flex angles on the carrier depth distribution and on the implant uniformity was evaluated by electrical measurements, SIMS and sheet resistance surface mapping. The range distribution of the B+ ions implanted at 0 degrees is broader than that of those implanted at 7 degrees with a shift of about 10% in the peak position. The junction depth is also increased by 20% at a substrate doping of 5*1015 cm-2, and the uniformity over the 5 in wafer is within 1%. The maximum penetration depth measured at a concentration of 10-2 of the peak value is not affected by the twist angle and by the implanted dose. The shape of the 0 degrees boron profile is instead modified by the fluence, i.e. the lattice damage created by the ions reduces the channelling effect. The experimental data are also compared with calculations performed with the Marlowe code.