Dopant profile engineering of advanced Si MOSFET's using ion implantation

Ion implantation has been used to realize non-uniform, steep retrograde (SR ) dopant profiles in the active channel region of advanced Si MOSFET's. Aft er defining the transistor configuration, SR profiles were formed by dopant implantation through the polycrystalline Si gate and the gate oxide (throu gh-the-gate, TG, implantation)The steep nature of the as-implanted profile was retained by applying rapid thermal annealing for dopant activation and implantation damage removal. For NMOS transistors,TG implantation of B yiel ds improved transistor performance through increased carrier mobility, redu ced junction capacitances, and reduced susceptibility to short-channel effe cts. Electrical measurements show that the gate oxide quality is not deteri orated by the ion-induced damage, demonstrating that transistor reliability is preserved. For PMOS transistors, TG implantation of P or As leads to un acceptable source/ drain junction broadening as a result of transient enhan ced dopant diffusion during thermal activation. (C) 1999 Elsevier Science B .V. All rights reserved.