Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 30: Si/Ge

HL 30.10: Vortrag

Mittwoch, 25. März 2009, 12:00–12:15, POT 51

Phosphorus doping by chemical vapour deposition for vertical p-MOSFETs — •Peter Iskra, Dorota Kulaga-Egger, Thomas Zilbauer, Helmut Lochner, Torsten Sulima, and Ignaz Eisele — Universität der Bundeswehr München, Institut für Physik, Werner-Heisenberg- Weg 39, 85577 Neubiberg

The major advantage of a vertical MOSFET concept is the capability of defining the channel length by the thickness of the deposited layer. This allows an inexpensive fabrication of short channel devices. The deposition of the epitaxy stacks can be realized by LP-CVD (low pressure chemical vapour deposition). But, while the CVD process for p-type doping provides sharp doping profiles, the n-type doping suffers from surface segregation. This leads to an inhomogeneous doping profile and to redistribution of dopands from an underlaying doped layer into subsequent layers. A suppression of this effect can be achieved by optimizing the deposition parameters, the use of additional precursors or an ex situ wafer cleaning process.

Epitaxial pnp-structures were grown using a commercial LPCVD system. Dichlorosilane, phosphine and diborane were used as silicon and dopand sources. The n-type process was investigated with respect to growth temperature and dopand precursor flow. Additionally n-doped SiGe layers ware deposited for studying the influence on the phosphorus surface segregation. The germanium content was adjusted by germane flow. Furthermore, an ex situ oxidation cleaning process was investigated. All samples were characterised by secondary ion mass spectrometry (SIMS).