Atomic Layer Deposition of Hafnium Oxide Passivating Layers on Silicon: Impact of Precursor Selection

Hafnium oxide (HfOx) films grown by atomic layer deposition (ALD) have recently been demonstrated to provide high-quality silicon surface passivation. Reports have suggested that changing the composition of the hafnium-containing precursor can enable films of both charge polarities to be produced. Herein, the passivation quality of hafnium oxide grown with metal amide precursors and a tetrakis(ethylmethylamido)hafnium (TEMAHf) precursor is examined, considering film charge polarity, chemical- and field-based passivation effects, and film crystallinity. Throughout, the properties of TEMAHf-HfOx are benchmarked against that of hafnium oxide grown with a tetrakis(dimethylamido)hafnium precursor. It is found that precursor choice has no influence on the fixed negative charge polarity (of order -1012 q cm-2) of HfOx films grown via plasma-enhanced ALD. TEMAHf-HfOx passivation is influenced by post-deposition annealing temperature and can passivate with a surface recombination velocity <= 3 cm s-1 on n-type silicon, compared to surface recombination velocities <= 11 cm s-1 for TDMAHf-HfOx of a similar thickness. Hafnium oxide (HfOx) films are grown via plasma-enhanced atomic layer deposition from a tetrakis(ethylmethylamido)hafnium (TEMAHf) precursor, and the properties (passivation, charge polarity, and crystallinity) are characterized. TEMAHf-HfOx properties are benchmarked against that of HfOx grown from tetrakis(dimethylamido)hafnium. It is found that negatively charged TEMAHf-HfOx offers good passivation (surface recombination velocities <= 3 cm s-1) and demonstrates that precursor choice does not influence HfOx charge polarity.image (c) 2024 WILEY-VCH GmbH