Physics-Based Diffusion Simulations for Preamorphized Ultrashallow Junctions
- PDF / 373,952 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 102 Downloads / 220 Views
D6.8.1
Physics-Based Diffusion Simulations for Preamorphized Ultrashallow Junctions N.E.B. Cowern1, B. Colombeau1, E. Lampin2, F. Cristiano3, A. Claverie3, Y. Lamrani3, R. Duffy4, V. Venezia4, A. Heringa4, C.C. Wang5, C. Zechner6 1
Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, UK IEMN/ISEN, UMR CNRS 8520, Villeneuve d’Ascq, France 3 Ion Implantation Group, CEMES/LAAS-CNRS, Toulouse, France 4 Philips Research Leuven, Kapeldreef 75, B-3001 Leuven, Belgium 5 Advanced Device Technology Department, R&D, Taiwan Semiconductor Manufacturing Company, Hsin-Chu, Taiwan 6 ISE Integrated System Engineering AG, Balgriststrasse 102, CH-8008 Zürich, Switzerland 2
ABSTRACT In recent years there have been major advances in our understanding of the energetics, Ostwald ripening and transformations between various types of extended self-interstitial defect in Si and Ge ion-implanted silicon. As a result we can now predict the detailed time- and temperaturedependent supersaturation of interstitials during thermal evolution of these defects. This opens the way to predictive simulation of transient enhanced diffusion and dose loss in preamorphized ultrashallow junctions, where dopant movement is driven by free interstitials emitted by selfinterstitial “end-of-range” defects. We present recent progress on this topic, emphasizing novel effects in highly doped ultrashallow junctions. Two key influences – the chemical pump effect due to the high concentration of dopants in ultrashallow junctions, and the ‘long hop’ behaviour of the dopant – are discussed in detail. The paper concludes by presenting simulation results that explain the recent observation of ‘uphill diffusion’ of B ultrashallow junction profiles. INTRODUCTION Preamorphizing implants (PAI) are a promising option for forming highly doped B ultrashallow junctions [1]. They overcome the traditional limitation of solid solubility by placing B atoms directly onto substitutional sites as a result of solid-phase epitaxial regrowth of the preamorphized region containing the B implant. A significant drawback, however, is that the PAI implant leaves a damage band, rich in self-interstitials, I, just beyond the amorphous /crystalline interface (see schematic concept in Fig. 1). These agglomerate into extended selfinterstitial defects that emit free interstitials back into the system during thermal annealing [2]. The free interstitials drive transient enhanced diffusion (TED) and deactivation of the B implant, limiting the improvement in device performance achievable by PAI. An understanding of the mechanisms by which the evolving defects emit interstitials and interact with the high-dose B USJ implant is needed to enable TCAD simulations and guide future research to optimise junction depths and sheet resistances. This paper discusses recent progress in understanding and modelling defect evolution and TED, and shows how this can be applied to the simulation of USJ formation. In addition to the physics of defect evolution, special emphasis is placed on understandin
Data Loading...
