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Wear‐out and breakdown of thermally grown Ta 2 O 5 insulating films on plasma oxynitrided Si substrates
Author(s) -
Novkovski N.,
Atanassova E.
Publication year - 2006
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200521128
Subject(s) - substrate (aquarium) , materials science , dielectric , nitrogen , stress (linguistics) , analytical chemistry (journal) , permittivity , plasma , quantum tunnelling , capacitor , breakdown voltage , relative permittivity , monolayer , voltage , chemistry , electrical engineering , optoelectronics , nanotechnology , linguistics , oceanography , philosophy , organic chemistry , physics , chromatography , quantum mechanics , engineering , geology
Wear‐out and breakdown at constant current stress ( J = 10 mA/cm 2 ) were studied for Ta 2 O 5 insulating layers (30 nm thick) thermally grown over plasma oxynitrided (5 to 15 s at room temperature) Si substrates. For injected charges Q inj lower than 100 C/cm 2 hard breakdown occurs, while for Q inj higher than 100 C/cm 2 it appears that only progressive breakdowns are possible. An optimum of the dielectric properties was found for oxynitridation times as long as 10 s, simultaneously for the hard breakdown charge (33 C/cm 2 on a capacitors with an area of 2.5 × 10 –3 cm 2 ), the equivalent thickness (8.24 nm) and the wear‐out (variation of the gate voltage smaller than 50 mV, during the stress up to 100 C/cm 2 ). The observed optimum was attributed to a defect free relaxed interfacial structure containing approximately 1 × 10 14 cm –2 nitrogen atoms in the first atomic monolayer adjacent to the Si substrate, as one with a significant improvement of the SiO x N y interfacial layer relative permittivity (5.5) without considerable reduction of the tunneling barrier heights. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)