Controlled localised melting in silicon by high dose germanium implantation and flash lamp annealing


Controlled localised melting in silicon by high dose germanium implantation and flash lamp annealing

Voelskow, M.; Pezoldt, J.; Kups, T.; Skorupa, W.

The annealing of semiconductor surfaces via pulsed laser melting has been practised since the 70 ' s. During the process a thin surface layer is molten up to a depth of mkm and recrystallises, after the pulse is over, epitaxially on the non molten substrat.
Depending on the segregation coefficient of additionally admixed atoms completely different doping profiles can be achieved. Typical for all pulse irradiation techniques is, that the melting process starts near the surface. The aim of the present work is to overcome this phenomen and to force a buried melting by large area flash lamp irradiation using an additional Ge admixture. The addition of Germanium locally leads to a reduction of the silicon melting temperature so that separated melting in the bulk of silicon can be observed. During cooling down of the sample the buried liquid layer recrystallises epitaxially on the non molten bulk material and for the case of additional doping of the layer special profiles can be observed. Ion implantation at high doses and high energies was used to produce structures with a buried germanium enriched layer. The pulse irradiation was performed at the Rossendorf flash lamp apparatus using intense light pulses with a duration of 20 ms from a field of Xe flash tubes. The energy density at the sample surface was varied within wide limits. For the determination of the Ge profiles after the flash lamp irradiation the RBS technique was used. The microstructure of the recrystallised films was observed by cross sectional TEM. It could be shown that buried melting takes place whereby the width of the molten zone depends on the energy density. Deep facetted melting, typical for virgin silicon material, was not observed.

Keywords: flash lamp annealing; buried melting; germanium; RBS TEM

  • Poster
    IBMM 08 - 16th International Conference on Ion Beam Modification of Materials, 31.08.-05.09.2008, Dresden, Deutschland
  • Nuclear Instruments and Methods in Physics Research B 267(2009), 1269-1272

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Publ.-Id: 11718