Multiple implantations - experiments and computer simulations


Multiple implantations - experiments and computer simulations

Posselt, M.; Mäder, M.; Lebedev, A.; Grötzschel, R.

Advanced technologies use successive implantations of p- and/or n-dopants without any intermediate annealing steps. A characteristic example is the engineering of the regions of source, drain, extension and halo. The sequence of the implantations may influence the final distribution of dopants and radiation damage. In particular it affects the as-implanted distribution of dopants if in one or more implantation steps the direction of ion incidence is close to a major crystallographic axis of the silicon substrate. For example, extension implantations are often performed perpendicularly to the wafer surface, i.e. nearly parallel to the [100] axis. The defect production in previous implantations influences the shape of dopant and damage profiles in a subsequent channeling implantation step, since these defects may lead to increased dechanneling. Furthermore, the amorphization dose in a certain implantation step may be affected by the level of radiation damage formed during the previous steps. The present work deals with the simple example of two consecutive implantations in order to demonstrate the effects mentioned above. Two implantation sequences are investigated: (i) 35 keV B followed by 50 keV As into the [100] channel direction, (ii) 50 keV As followed by 35 keV B [100] channeling implantation. The depth profiles of B and As are measured by SIMS. The as-implanted damage is determined by RBS/C. The experimental data can be reproduced by atomistic computer simulations using the Crystal-TRIM code with an improved phenomenological model for damage buildup during multiple implantations. The present results contribute to a better understanding of ion-beam-induced defect formation and to progress in TCAD.

Keywords: ion implantation; silicon; process simulation

  • Lecture (Conference)
    MRS 2004 Spring Meeting, April 12 - 16, 2004, San Francisco, USA

Permalink: https://www.hzdr.de/publications/Publ-6193
Publ.-Id: 6193