Interface dipole engineering via TiO2-doped HfO2 interlayers for flat-band voltage modulation in scaled high-k gate stacks
Journal
Materials Science and Engineering: B
Journal Volume
326
Start Page
119182
ISSN
09215107
Date Issued
2026-04
Author(s)
Abstract
In advanced semiconductor technology nodes below 10 nm, precise flat-band voltage (VFB) control is essential for tuning the threshold voltage. This study systematically investigates the incorporation of Ti-doped HfO2 (HTO) interlayers into metal-oxide-semiconductor capacitors to modulate VFB while maintaining favorable electrical performance. A ∼2 nm HTO interlayer was prepared via atomic layer deposition (ALD) supercycles with controlled Ti doping concentrations and strategically positioned within the high-k dielectric stacks. The results reveal that a 50 % Ti-doped HTO interlayer located at the dielectric/Si interface produces the most significant VFB shift, along with reduced equivalent oxide thickness (EOT) and an acceptable leakage current density. This VFB modulation is attributed to interface dipole engineering as a result of the difference in electronegativity between Ti–O–Si and Hf–O–Si bonds. Furthermore, VFB is strongly correlated with the spatial placement of the interlayer: VFB shifts are pronounced when the HTO interlayer is positioned at the dielectric/Si or metal/dielectric interfaces, but minimal when embedded within the HfO2 matrix due to the cancellation of opposite dipoles. This study establishes an effective and scalable approach to dipole modulation in high-k gate stacks, enabling precise VFB control and EOT scaling for future low-power applications.
Subjects
Atomic layer deposition (ALD)
Flat-band voltage (VFB)
Hafnium oxide
High-k gate dielectrics
Metal-oxide-semiconductor (MOS) capacitors
Publisher
Elsevier Ltd
Type
journal article