Characterization of shallow (R p <20 nm) As- and B-implanted and electron-beam annealed silicon

Abstract

The annealing characteristics of shallow (Rp <20 nm) arsenic- and boron-implanted layers were found to be a complex function of the thermal cycle which the sample experienced. Arsenic at 10 keV and boron at 4.5 keV (derived from 20 keV BF+2 ) were implanted in the dose range 1014–1016 cm−2 into (100) Si. The optimal implant doses to maximize conductivity with essentially undiffused layers of device quality material were 2 × 1015 and 1015 cm−2 for As and B, respectively. A comparison of rapid isothermal annealing using the multiple-scan electron-beam annealing method and conventional furnace annealing was made. For arsenic minimum resistivities of about 2 × 10−4 Ω cm were obtained after furnace annealing at 550 °C for 15 min or electron-beam annealing with a peak temperature between about 700 and 1100 °C during a 100 ms (or 1 s) anneal. For boron, electron-beam annealing for 100 ms (or 1 s) with a peak temperature of between ∼700 and 1000 °C produced a resistivity of 7 × 10−4 Ω cm which compared with 1.2 × 10−3 Ω cm following conventional furnace annealing. High-resolution SIMS showed that peak temperatures of up to about 1000 and 1100 °C for B and As layers, respectively, may be reached with essentially no diffusion. An extension of diffusion theory applicable to conventional furnace annealing of deeper implant gave results in accord with SIMS profiles.