Open AccessAnomalous positive flatband voltage shifts in metal gate stacks containing rare-earth oxide capping layers
Author(s) -
J. A. Caraveo-Frescas,
Mohamed Nejib Hedhili,
H. Wang,
Udo Schwingenschlögl,
Husam N. Alshareef
Publication year - 2012
Publication title -
applied physics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 442
eISSN - 1077-3118
pISSN - 0003-6951
DOI - 10.1063/1.3692580
Subject(s) - overlayer , dielectric , metal , dipole , oxide , materials science , silicon , metal gate , condensed matter physics , gate oxide , analytical chemistry (journal) , chemistry , optoelectronics , voltage , electrical engineering , physics , organic chemistry , engineering , transistor , chromatography , metallurgy
It is shown that the well-known negative flatband voltage (VFB) shift, induced by rare-earth oxide capping in metal gate stacks, can be completely reversed in the absence of the silicon overlayer. Using TaN metal gates and Gd2O3-doped dielectric, we measure a ∼350 mV negative shift with the Si overlayer present and a ∼110 mV positive shift with the Si overlayer removed. This effect is correlated to a positive change in the average electrostatic potential at the TaN/dielectric interface which originates from an interfacial dipole. The dipole is created by the replacement of interfacial oxygen atoms in the HfO2 lattice with nitrogen atoms from TaN
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