Luis A. Marqués

  • Atomistic modeling of ion implantation technologies in silicon

    Luis A. Marqués, L. Pelaz, I. Santos, P. López, M. Aboy, M. López

    Departamento de Electrónica, Universidad de Valladolid, E.T.S.I. de Telecomunicación, 47011 Valladolid, Spain

    Ion implantation is a very well established technique to create junctions in Si for the manufacturing of electronic devices. Apart from the introduction of dopants, the implantation process creates defects in the semiconductor substrate. Their complexity may range from point defects and small defect clusters, to extended defects such as dislocations, or even full amorphous layers, depending on the particular implantation parameters. Usually defects have negative effects on the final device performance, for example, causing the spread of dopant profiles or increasing leakage currents. Understanding how defects are generated during implantation and how they interact afterwards are key factors for defining strategies aimed to minimize such deleterious effects. Atomistic simulation techniques can be really helpful in this task, especially in conditions where experiments are difficult, expensive or just not feasible.

    This work will be focused on the role that implantation-induced defects have on the front-end processing of novel Si logic devices. Requirements for the manufacturing of such devices at the nanometric scale are becoming more and more demanding on each new technology node, driving the need for the fabrication of ultra-shallow junctions and ultra-thin body structures [1]. In particular, we use atomistic simulation techniques to study some of the aspects related to the application of novel implantation strategies, such as cluster and cold implants, aimed to reduce the amount of end-of-range defects through substrate amorphization. We also analyze the role played by surfaces and amorphous-crystal interfaces on damage generation and recombination. We show that, close to surfaces and amorphous-crystal interfaces, damage generation and damage stability are enhanced with respect to bulk. As a result, the threshold dose for amorphization is reduced in ultra-low energy implants, and the regrowth of ultra-thin body devices becomes more difficult.

    [1] International Technology Roadmap for Semiconductors, http://www.itrs.net/