Erbium silicide growth in the presence of residual oxygen
Résumé
The chemical changes of Ti/Er/n-Si(100) stacks evaporated in high vacuum and grown ex situ by rapid thermal annealing were scrutinized. The emphasis was laid on the evolution with the annealing temperature of (i) the Er-Si solid-state reaction and (ii) the penetration of oxygen into Ti and its subsequent interaction with Er. For that sake, three categories of specimens were analyzed: asdeposited, annealed at 300 °C, and annealed at 600 °C. It was found that the presence of residual oxygen into the annealing atmosphere resulted in a substantial oxidation of the Er film surface, irrespective of the annealing temperature. However, the part of the Er film in intimate contact with the Si bulk formed a silicide (amorphous at 300 °C and crystalline at 600 °C) invariably free of oxygen, as testified by x-ray photoelectron spectroscopy depth profiling and Schottky barrier height extraction of 0.3 eV at 600 °C. This proves that, even if Er is highly sensitive to oxygen contamination, the formation of low SBH Er silicide contacts on n-Si is quite robust. Finally, the production of stripped oxygen-free Er silicide was demonstrated after process optimization.
Domaines
Physique [physics]
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