Germanium shallow junction formation by flash annealing


Germanium shallow junction formation by flash annealing

Satta, A.; D'Amore, A.; Simoen, E.; Janssens, T.; Clarysse, T.; Anwand, W.; Skorupa, W.

We have investigated flash-lamp annealing (FLA) of germanium wafers doped with phosphorous and boron introduced in the Ge crystal by ion implantation. Annealing was performed by using pre-heating at 400-450 oC in a conventional rapid thermal processing (RTP) unit and a fast (3-20 ms) FLA annealing at 800 oC or 900 oC. Diffusion of P is suppressed during the 800oC-20 ms FLA annealing, while concentration-enhanced diffusion occurs upon 900oC FLA anneals. At this higher temperature the FLA pulse time becomes a fundamental parameter, since the shortest FLA pulse (3 ms) causes less junction deepening and less P dose loss as compared to the longest (20 ms) pulse. Importantly, P activation seems to be enhanced by the FLA process. The FLA process applied to B-doped pre-amorphized Ge layers does not show advantages as compared to a RTP conventional annealing. B diffusion and activation behavior are indeed similar for the millisecond annealing approach and for a conventional RTP combined with a solid phase epitaxial regrowth of the doped Ge layer.
In summary, the FLA technique holds a potential for the development of P shallow junctions in germanium wafers. However, junction stability following the FLA process is a concern and needs to be further investigated.

Keywords: germanium; ion implantation; flash lamp annealing; RTP; diffusion; electrical activation

  • Lecture (Conference)
    15. International Conference on Ion Beam Modification of Materials, 18.-22.09.2006, Catania, Italy

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Publ.-Id: 9343